111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111 US 20210214223Al (19) United States (12) Patent Application Publication (lO) Pub. No.: US 202110214223 Al FERNÁNDEZ LOZANO et al. (43) Pub. Date: Jul. 15, 2021

(54) ANTIMICROBIAL COMPOSITE MATERIAL Publication Classification (51) Int. Cl. (71) Applicants:CONSEJO SUPERIOR DE C01B 25130 (2006.01) INVESTIGACIONES CIENTÍFICAS, A01N 25134 (2006.01) Madrid (ES); ENCAPSULAE, S.L., A01N 25110 (2006.01) Castellón (ES) C08K 3132 (2006.01) A01N 43178 (2006.01) (72) Inventors: José Francisco FERNÁNDEZ (52) U.S. Cl. LOZANO, Madrid (ES); Julián CPC ...... C01B 25130 (2013.01); A01N 25/34 JIMENEZ REINOSA, Madrid (ES); (2013.01); A01N 43178 (2013.01); C08K 3/32 Alberto MOURE ARROYO, Madrid (2013.01); A01N 25110 (2013.01) (ES); José Javier MENÉNDEZ MEDINA, Castellón de la Plana (ES) (57) ABSTRACT

(21) Appl. No.: 15/734,264 The present invention relates to activated and ground sodium hexametaphosphate frit particles and antimicrobial (22) PCT Filed: Jun. 4, 2019 composite material comprising said activated and ground sodium hexametaphosphate frit particles embedded in a thermoplastic polymer such as low density polyethylene (86) PCTNo.: PCT/ES2019/070378 (LDPE). The invention also relates to the method for obtain­ § 371 (c)(l), ing the composite material of the invention and a thermal (2) Date: Dec. 2, 2020 activation method for the thermal activation of a sodium hexametaphosphate salt in order to generate the activated (30) Foreign Application Priority Data and ground sodiUlll hexametaphosphate frit particles. The antimicrobialmaterial ofthe invention is preferably used in Jun. 5, 2018 (ES) ...... P201830547 the food industry.

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ANTIMICROBIAL COMPOSITE MATERIAL ofpolyphosphates on Clostridium perfringens growth, spo­ rulation and spore outgrowth. Food Microbiology 25,6 FIELD OF THE INVENTION (2008)802-808] describes bacteria! growth inhibition pro­ cesses for a relevant number of bacteria for polyphosphate [0001] The present invention relates to the area of anti­ salt concentrations commonly used in the food industry, i.e., microbial materials. More specifically, the present invention 0.2-0.8% by weight. However, the efficacy of said poly­ relates to the area of antimicrobial composite materials. phosphate salts as antimicrobial agents described in the state of the art is extremely limited and does not allow the use BACKGROUND OF THE INVENTION thereof in a large number of bacteria. Another difficulty in [0002] Today, microbial infections still account for a quar­ the use of polyphosphate salts as antimicrobial agents is the ter of deaths worldwide. This situation is aggravated if the slow dissolution thereof in aqueous media. Furthermore, a increase in antibiotic resistance by microorganisms is taken simultaneous antimicrobial effect of polyphosphate salts in into account. Many substances can be described as antimi­ Gram-positive and Gram-negative bacteria has not been crobial, for example disinfectants, antibiotics, and obviously proven so far. antimicrobial agents. However, many of these compounds [0005] There is therefore a need to provide new composite can be toxic or harmful to human beings. The document by materials which exhibit antimicrobial activity against dif­ Kenawy et al. [E. Kenawy, S. D. Worley and R. Broughton. ferent bacteria, a high efficacy, and are free ofthe drawbacks The Chemistry and Applications ofAntimicrobial Polymers: related to toxicity phenomena. A State-ofthe-Art Review. Biomacromolecules, 85, 1359­ BRIEF DESCRIPTION OF THE INVENTION 1384(2007)] propases the use ofpolymers for improving the efficacy of sorne antimicrobial agents. In particular, Kenawy [0006] The authors of the present invention have devel­ et al. propase the introduction of antimicrobial functional oped a composite material comprising activated and ground groups in polymer molecules, generating antimicrobial poly­ sodium hexametaphosphate frit particles and a polymer mers. In this manner, the residual toxicity of said functional matrix with antimicrobial properties. groups is reduced and their efficiency, selectivity, and shelf [0007] Therefore, a first aspect of the invention relates to life are increased. However, attempts at reducing the toxicity a composite material comprising: of said antimicrobial agents are far from guaranteeing their [0008] a) activated and ground sodium hexametaphos­ use in areas as susceptible as food and medica! applications, phate frit particles obtainable by means of a thermal among others. activation method comprising the steps of: [0003] In the food industry, sodium hexametaphosphate is [0009] i) heating a sodium hexametaphosphate salt used as a synthetic stabilizer and an acidity regulator. It can until it melts such that a molten sodium hexameta­ be applied in meat and fish to improve their water retention phosphate salt is obtained; capacity and to prevent fat oxidation. In emulsions, it [0010] ii) abruptly cooling the molten sodium hex­ increases viscosity and prevents product precipitation, ametaphosphate salt obtained in step (i) in a dry improving the texture and color of the food products. For medium to obtain activated sodium hexametaphos­ these reasons, it is often found in processed meat, chewing phate frit particles; and gums, sugary drinks, ready-made meals and dairy products, [0011] iii) grinding the activated sodium hexameta­ such as lactase-free milk or different types of cheese, sauce, phosphate frit particles obtained in step (ii) to obtain fruit jellies, frozen desserts, salad dressing, breakfast cereal, activated and ground sodium hexametaphosphate frit ice-cream, beer, and bottled drinks, among others. For particles; and example, document CN104542895A describes a water­ [0012] b)a polymer matrix; soluble polymer composite material for use as pork meat wherein said activated and ground sodium hexametaphos­ preservative. The composition of said polymer material phate frit particles are embedded in said polymer matrix. includes a commercial sodium hexametaphosphate salt in a [0013] A second aspect of the present invention relates to proportion between about 15-25% by weight to preserve the the use ofthe composite material ofthe present invention as moisture in the meat. Furthermore, by means of adding an antimicrobial agent; preferably as an antibacterial agent; specific natural bactericida! agents such as pomelo peel more preferably as an antibacterial agent against Gram­ polysaccharides, a bactericida! effect is generated in the positive bacteria and Gram-negative bacteria. polymer material described in said document. The polymer [0014] A third inventive aspect relates to a method for material described in document CN104542895A is used as obtaining the composite material of the present invention, preservative, although it would be limited to specific appli­ comprising the steps of cations and could not be used, for example, for food pack­ [0015] i) providing aging, due to its water-soluble nature. [0016] a) activated and ground sodium hexameta­ [0004] In the scientific literature, phosphate salts have phosphate frit particles obtainable by means of a been described as acting indirectly as preservatives or thermal activation method comprising the steps of: microorganism growth inhibitors. The document by Tomp­ [0017] i) heating a sodium hexametaphosphate salt kin [R. B. Tompkin, Indirect antimicrobial effects in foods: until it melts such that a molten sodium hexam­ phosphates. Journal of Food Society 6(1983)13-17] etaphosphate salt is obtained; describes the inhibitory mechanism produced by said phos­ [0018] ii) abruptly cooling the molten sodium hex­ phate salts due to interferences with the divalent cation ametaphosphate salt obtained in step (i) in a dry metabolism of the microorganisms by causing a deficiency, medium to obtain activated sodium hexameta­ mainly of magnesium, which inhibits cell division and phosphate frit particles; and causes the loss of cell wall. The document by Akhtar et al. [0019] iii) grinding the activated sodium hexam­ [S. Akhtar, D. Paredes-Sabja, M. R. Sarker. Inhibitory effects etaphosphate frit particles obtained in step (ii) to US 2021/0214223 Al Jul. 15, 2021 2

obtain activated and ground sodium hexameta­ [0035] FIG. 6 shows conductivity values (¡.tS/cm) with phosphate frit particles; and respect to time for activated and ground sodium hexameta­ [0020] b) a polymer matrix; and phosphate frit particles embedded in a low density polyeth­ ylene. [0021] ii) embedding said activated and ground sodium hexametaphosphate frit particles in said polymer [0036] FIG. 7 shows (a) an optical confocal microscopy matrix. image of an activated and ground sodium hexametaphos­ phate frit particle (4) embedded in a low density polyethyl­ [0022] An additional inventive aspect relates to activated ene (2) together with a drop ofwater (3) after immersing the and ground sodium hexametaphosphate frit particles obtain­ compound in water for 15 minutes and subsequently drying able by means of a thermal activation method comprising same at 60° C. for 1 hour. (b) representative Raman spectra the steps of: corresponding to the image ofthe LDPE polymer matrix (2), [0023] i) heating a sodium hexametaphosphate salt until a drop of water (3) stabilized on the surface of the compound it melts such that a molten sodium hexametaphosphate in the proximity of an activated and ground sodium hexam­ salt is obtained; etaphosphate frit partide (4). [0024] ii) abruptly cooling the molten sodium hexam­ [0037] FIG. 8 shows micrographs at different magnifica­ etaphosphate salt obtained in step (i) in a dry medium tions (a) and (b) of the surface of the polymer film formed to obtain activated sodium hexametaphosphate frit par­ by the composite material comprising activated and ground ticles; and sodium hexametaphosphate frit particles encapsulated in a [0025] iii) grinding the activated sodium hexameta­ polymer matrix according to Example 6. Said film was phosphate frit particles obtained in step (ii) to obtain exposed to environmental humidity for 60 days and oven activated and ground sodium hexametaphosphate frit dried at 60° C. for 1 hour. partid es. [0026] Finally, the last inventive aspect of the present DETAILED DESCRIPTION OF THE invention relates to a thermal activation method for the INVENTION thermal activation of a sodium hexametaphosphate salt in [0038] Unless otherwise stated, all the scientific terms arder to generate the activated and ground sodium hexam­ u sed herein have the meaning commonly understood by one etaphosphate frit particles as defined above, comprising the skilled in the art for whom this description is intended. In the steps of present invention, the singular forms include plural forms [0027] i) heating a sodium hexametaphosphate salt until unless otherwise indicated. it melts such that a molten sodium hexametaphosphate salt is obtained; Composite Material and Activated and Ground [0028] ii) abruptly cooling the molten sodium hexam­ Sodium Hexametaphosphate Frit Particles etaphosphate salt obtained in step (i) in a dry medium to obtain activated sodium hexametaphosphate frit par­ [0039] The main aspect of the present invention is to ticles; and provide a composite material comprising: [0029] iii) grinding the sodium hexametaphosphate frit [0040] a) activated and ground sodium hexametaphos­ particles obtained in step (ii) to obtain activated and phate frit particles obtainable by means of a thermal ground sodimn hexametaphosphate frit particles. activation method comprising the steps of: [0041] i) heating a sodium hexametaphosphate salt FIGURES until it melts such that a molten sodium hexameta­ phosphate salt is obtained; [0030] FIG. 1 shows the Raman spectra obtained for (a) [0042] ii) abruptly cooling the molten sodium hex­ activated and ground sodium hexametaphosphate frit par­ ametaphosphate salt obtained in step (i) in a dry ticles (continuous line) and for (b) ground sodium hexam­ medium to obtain activated sodium hexametaphos­ etaphosphate salt (discontinuous line ). phate frit particles; and [0031] FIG. 2 shows an enlargement ofthe Raman spectra [0043] iii) grinding the activated sodium hexameta­ obtained for (a) activated and ground sodium hexametaphos­ phosphate frit particles obtained in step (ii) to obtain phate frit particles (continuous !ine) and for (b) ground activated and ground sodimn hexametaphosphate frit sodium hexametaphosphate salt (discontinuous line ). particles; and [0032] FIG. 3 shows the thermogravimetric curves corre­ [0044] b) a polymer matrix; sponding to sodium hexametaphosphate salt (continuous wherein said activated and ground sodium hexametaphos­ line, FIG. 3a), ground sodium hexametaphosphate salt (dis­ phate frit particles are embedded in said polymer matrix. continuous line, FIG. 3a), activated sodium hexametaphos­ [0045] The term "composite material" refers to combina­ phate frit particles (continuous line, FIG. 3b), and the tions of at least two types of materials to achieve the activated and ground sodium hexametaphosphate frit par­ combination of properties which is impossible to obtain in ticles (discontinuous line, FIG. 3b). the original materials. Generally, composite materials have [0033] FIG. 4 shows conductivity values (mS/cm) with a continuous matrix and a discrete load. The composite respect to time for ground sodium hexametaphosphate salt material of the present invention comprises a continuous (square symbol) and for activated and ground sodium hex­ matrix which is a polymeric matrix preferably hydrophobic ametaphosphate frit particles (circular symbol). or water-repellent, anda discrete load comprising activated [0034] FIG. 5 shows the confocal microscopy image of an and ground sodium hexametaphosphate frit particles obtain­ activated and ground sodium hexametaphosphate frit par­ able by means of a thermal activation method as mentioned ticle (1) embedded in a low density polyethylene (2). above. US 2021/0214223 Al Jul. 15, 2021 3

[0046] The authors of the present invention have surpris­ related to a chemical reaction, such as the synthesis of a ingly found an antimicrobial behavior in the composite material other than the precursor, rather it refers to a method material of the present invention. related to the modification of the material characteristics [0047] An inventive aspect ofthe present invention relates ancl/or properties which are acquired through a process to activated and ground sodium hexametaphosphate frit requiring a heat treatment as defined in the present invention partides obtainable by means ofa thermal activation method and performed with the means known by one skilled in the comprising the steps of: art. In the present invention, said method further comprises [0048] i) heating a sodium hexametaphosphate salt until a step of grinding which can be performed by means of it melts such that a molten sodium hexametaphosphate methods known by one skilled in the art. salt is obtained; [0060] In the context ofthe present invention, the expres­ [0049] ii) abruptly cooling the molten sodium hexam­ sion "heating a sodium hexametaphosphate salt until it etaphosphate salt obtained in step (i) in a dry medium melts" refer to a sufficient heating so that the sodium to obtain activated sodium hexametaphosphate frit par­ hexametaphosphate salt changes its physical state, going ticles; and from salid state to liquid state by the action of heat. Said [0050] iii) grinding the activated sodium hexameta­ heating can be carried out using any of the means known by phosphate frit particles obtained in step (ii) to obtain one skilled in the art, for example, by means ofheating in an activated and ground sodium hexametaphosphate frit oven. partid es. [0061] In a particular embodiment, step (i) ofthe method [0051] In the present invention, the activated and ground for the activation of the activated sodium hexametaphos­ sodium hexametaphosphate frit particles are obtainable by phate frit particles of the present invention comprises heat­ means of a thermal activation method comprising step (i) of ing said sodium hexametaphosphate salt of step (i) at a heating a sodium hexametaphosphate salt until it melts such temperature between 630° C. and 1000° C., preferably that a molten sodium hexametaphosphate salt is obtained. between 650 and 900° C., more preferably between 660 and [0052] In the context ofthe present invention, the expres­ 800° c. sion "sodium hexametaphosphate" refers to a chemical [0062] In a particular embodiment, step (i) of the method compound formed by a mixture of linear polyphosphate for the activation of the activated sodium hexametaphos­ polymers with general formula (NaP03)w Among other phate frit particles of the present invention comprises heat­ names, said chemical compound can also be called: "Gra­ ing said sodium hexametaphosphate salt of step (i) for at ham's salt", Caigan S, glassy sodium, sodium tetraphos­ least 30 minutes, preferably for at least 1 hour, more phate, sodium metaphosphate, sodium polymetaphosphate, preferably for a period of time comprised between 1 hour sodium polyphosphate, hexasodium metaphosphate, hexa­ and 5 hours. sodium salt, metaphosphoric acid, and the like. [0063] In a particular embodiment, step (i) of the method [0053] In the context of the present invention, the expres­ for the activation of the activated sodium hexametaphos­ sion "sodium hexametaphosphate salt" refers to a sodium phate frit particles of the present invention comprises heat­ hexametaphosphate salt generated by heating sodium di­ ing for at least 30 minutes at a temperature between 650 and hydrogen phosphate (NaH2P04 ), disodium di-hydrogen 900° C. pyrophosphate (Na H P 0 ) or NaH(NH )P0 .4H 0 , or 2 2 2 7 4 4 2 [0064] In the present invention, the activated and ground other sodium salt or salts to their melting point, and then sodium hexametaphosphate frit particles are obtainable by quenching it. means ofa thermal activation method comprising step (ii) of [0054] In the context of the present invention, the term abruptly cooling the molten sodium hexametaphosphate salt "frit" refers to an inorganic compound having no long -range obtained in step (i) in a dry medium to obtain activated crystalline arder or subcooled glass or liquid compound. Frit sodium hexametaphosphate frit particles. is in the fonn of irregular fragments, flakes, or granules obtained from melting a starting material, having the same [0065] In a particular embodiment, step (ii) of the method chemical composition as the initial material, at high tem­ for the activation of the activated sodium hexametaphos­ peratures and a rapid quenching. phate frit particles of the present invention comprises pour­ ing said molten sodium hexametaphosphate salt obtained in [0055] In the context of the present invention, the expres­ sion "activated and ground sodium hexametaphosphate frit step (i) on a metal plate, preferably on a bronze or stainless particles" refers to particles obtainable from a sodium hex­ steel plate, preferably a bronze plate. ametaphosphate salt by means of a thermal activation [0066] In a particular embodiment, step (ii) of the method method comprising the steps of: for the activation of the activated sodium hexametaphos­ [0056] i) heating a sodium hexametaphosphate salt until phate frit particles of the present invention comprises pour­ it melts such that a molten sodium hexametaphosphate ing said molten sodium hexametaphosphate salt obtained in salt is obtained; step (i) on a fritting device; preferably a dry fritting device. [0057] ii) abruptly cooling the molten sodium hexam­ [0067] In the context ofthe present invention, the expres­ etaphosphate salt obtained in step (i) in a dry medium sion "dry fritting device" refers to fritting equipment of the to obtain activated sodium hexametaphosphate frit par­ types commonly known by one skilled in the art, preferably ticles ; and to a frit cooler-laminator to which a device for having a [0058] iii) grinding the activated sodium hexameta­ controlled and stable final frit particle temperature is phosphate frit particles obtained in step (ii) to obtain applied. activated and ground sodium hexametaphosphate frit [0068] In a particular embodiment, step (ii) of the method partid es. for the activation of the activated sodium hexametaphos­ [0059] In the context of the present invention, the expres­ phate frit particles of the present invention comprises pour­ sion "thermal activation method" refers to a method not ing said molten sodium hexametaphosphate salt obtained in US 2021/0214223 Al Jul. 15, 2021 4

step (i) on a metal plate, wherein said metal plate is at a [0081] In a particular embodiment, the activated sodium temperature between 15 and 50° C., preferably at room hexametaphosphate frit particles are hydrophilic. temperature. [0082] In a more particular embodiment, the activated and [0069] In a particular embodiment, step (ii) ofthe method ground sodium hexametaphosphate frit particles are hydro­ for the activation of the activated sodium hexametaphos­ philic. phate frit particles of the present invention comprises pour­ [0083] In a particular embodiment, the activated sodium ing said molten sodium hexametaphosphate salt obtained in hexametaphosphate frit particles have a higher rate of dis­ step (i) on a metal plate, wherein said metal plate is cooled solution than the sodium hexametaphosphate salt. by means of a water coi! or by means of an air stream. [0084] In a more particular embodiment, the activated and [0070] In the context ofthe present invention, the expres­ ground sodium hexametaphosphate frit particles have a sion "room temperature" refers to a temperature comprised higher rate of dissolution than the sodium hexametaphos­ between 15 and 35° C. phate salt. [0071] In the context ofthe present invention, the expres­ [0085] In a particular embodiment, the activated sodium sion "abruptly", in reference to the cooling of said molten hexametaphosphate frit particles are in an irregular form, sodium hexametaphosphate salt obtained in step (i), refers to preferably in the form of a granule or fiake, more preferably a reduction of the temperature of said molten sodium a fiake. hexametaphosphate salt from its melting temperature to a [0086] In a more particular embodiment, the activated and temperature below 500° C. in less than one minute, i.e., with ground sodium hexametaphosphate frit particles are in an a cooling speed greater than 200° C./min. irregular form, preferably in the form of a granule or fiake, [0072] In a particular embodiment, step (ii) ofthe method more preferably a fiake. for the activation of the activated sodium hexametaphos­ [0087] In a particular embodiment, the activated and phate frit particles of the present invention comprises a ground sodium hexametaphosphate frit particles are trans­ cooling speed greater than 200° C./min, preferably greater parent. than 300° C./min. [0088] In a particular embodiment, the activated and [0073] In the context ofthe present invention, the expres­ ground sodium hexametaphosphate frit particles have a sion "in a dry medium", in reference to the cooling of said refractive index value comprised between 1.3 and 1.7, molten sodium hexametaphosphate salt obtained in step (i), preferably between 1.4 and 1.6. refers to rapidly cooling said molten salt without the aid of In the context ofthe present invention, the expres­ a liquid medium, such as for example water, using means [0089] sion "particle size", in reference to the activated sodium commonly known by one skilled in the art. hexametaphosphate frit particles of step (ii) or to the acti­ [0074] Additionally, the authors of the present invention vated and ground sodium hexametaphosphate frit particles have surprisingly found that the thermally activated sodium of step (iii), refers to the particle size distribution or granu­ hexametaphosphate frit particles of the present invention lometric curve which is statistically determined and charac­ have a higher dissolution capacity and rate of dissolution terized by d50 and d90 parameters. In the context of the than the sodium hexametaphosphate salt. present invention, the expressions "d50 parameter" and "d90 [0075] Without being bound to a particular theory, the parameter" refer to the equivalent size corresponding to 50% authors of the present invention have found that, when using and 90%, respectively, of the cumulative particle size dis­ cooling in a dry medium, costs are saved in the conditioning tribution or granulometric curve. The equivalent size refers of the frit particles of the present invention associated with to the diameter of the sphere having the same specific area the formation ofbonds between said particles during drying. as the specified particle population. Furthermore, an increase in yield expressed as kilograms of frit produced per hour has been observed by means of dry [0090] In a particular embodiment, the activated sodium cooling. hexametaphosphate frit particles of the present invention have a d90 parameter below 5 cm, preferably below 2 cm, [0076] In a particular embodiment, the activated sodium more preferably below 1 cm. hexametaphosphate frit particles are formed by a glass material. [0091] In a particular embodiment, the activated and [0077] In a more particular embodiment, the activated and ground sodium hexametaphosphate frit particles of the pres­ ground sodium hexametaphosphate frit particles are formed ent invention have a d90 parameter below 100 micra, by a glass material. preferably below 50 micra, more preferably below 20 micra, [0078] In the context ofthe present invention, the expres­ even more preferably below 10 micra. sion "glass material" refers to an inorganic material having [0092] In a particular embodiment, the activated and an atom arrangement showing no long-range ordered struc­ ground sodium hexametaphosphate frit particles of the pres­ ture unlike in the crystalline state. ent invention are micrometric particles, preferably with an [0079] In a particular embodiment, the activated and average diameter between 0.5 and 100 micra, more prefer­ ground sodium hexametaphosphate frit particles have a ably between 1 and 50 micra, even more preferably between Raman spectrum with a red shift in a manner corresponding 1 and 10 micra. to the symmetric stretching of the terminal oxygen atoms in [0093] In a preferred embodiment, the activated sodium the P02 units formed by Q2-type tetrahedral chains as the hexametaphosphate frit particles of the present invention sodium hexametaphosphate salt. have less than 50% ofthe particles thereofwith at least one [0080] In a particular embodiment, the activated and of their dimensions below 100 nm. ground sodium hexametaphosphate frit particles comprise a [0094] In the present invention, the activated and ground mass percentage of absorbed water in the composition sodium hexametaphosphate frit particles are obtainable by thereof greater than 2.5%, preferably greater than 5%, more means of a thermal activation method comprising step (iii) preferably greater than 10%. of grinding the activated sodium hexametaphosphate frit US 2021/0214223 Al Jul. 15, 2021 5

particles obtained in step (ii) to obtain activated and ground micra, preferably below 20 micra, and particularly prefer­ sodium hexametaphosphate frit particles. ably below 10 micra, and since these partid es are embedded [0095] In the context ofthe present invention, the expres­ in a polymer matrix, their dispersion in the composite sion "activated and ground sodium hexametaphosphate frit material improves and the fiow lines in the composite partid es" refers to activated sodium hexametaphosphate frit material are reduced. particles which have been subjected to a grinding andlor [0103] In a particular embodiment, the composite material crushing method or a combination of grinding or crushing of the present invention comprises a polymer matrix, processes to select a specific range of sizes. Said grinding wherein the polymer matrix comprises at least one thermo­ andlor crushing method can be selected from any of those setting polymer, at least one thermoplastic polymer, at least known by one skilled in the art. Non-limiting examples of one elastomer polymer, or combinations thereof; preferably said grinding processes are those performed by means of at least one thermosetting polymer, at least one thermoplas­ milis, such as by means of planetary milis or jaw crushers, tic polymer, or combinations thereof; more preferably at for example. Non-limiting examples of milis suitable for least one thermoplastic polymer; even more preferably a grinding of the present invention are ring milis such as thermoplastic polymer; still more preferably a hydrophobic tungsten carbide ring milis, jet milis, or ball or microball thermoplastic polymer. milis, among others. [01 04] In the context of the present invention, the expres­ [0096] In a particular embodiment, the grinding of step sion "thermoplastic polymer" refers to a polymer material (iii) comprises at least a dry grinding in a planetary mili, which becomes deformable or flexible at relatively high preferably at least a dry grinding, preferably a dry grinding temperatures, melts when heated, and hardens in a glass in a planetary mili, more preferably in a planetary mili with transition state when su:fficiently cooled; preferably hydro­ alumina or zirconium balls. phobic or water-repellent. [0097] In a particular embodiment, the grinding of step (iii) comprises at least a dry grinding, preferably a dry [0105] In a particular embodiment, the composite material grinding in a jaw crusher, preferably at least a dry grinding of the present invention comprises a polymer matrix, in a jaw crusher with tungsten rings. wherein said polymer matrix comprises at least one ther­ [0098] In a particular embodiment, the grinding of step moplastic polymer; preferably at least one thermoplastic (iii) comprises at least a dry grinding, wherein said dry polymer selected from polyether ether ketone, polyethylene grinding comprises severa! steps of milling. terephthalate (PET), polyethylene (PE), high density poly­ [0099] In a particular embodiment, the activated and ethylene (HDPE), low density polyethylene (LDPE), poly­ ground sodium hexametaphosphate frit particles are a white vinyl chloride (PVC), polypropylene (PP), polystyrene (PS); or transparent powdery material, preferably transparent. polyvinylidene fiuoride, poly(methyl methacrylate ), polytet­ rafiuoroethylene (PTFE), cellulosic polymers and deriva­ [0100] In the context ofthe present invention, the param­ tives, polyamide (PA), acrylonitrile butadiene styrene, poly­ eters defining the size distribution of the activated sodium carbonates; polyacetals, fiuoroplastics, and combinations hexametaphosphate frit particles or the activated and ground thereof. sodium hexametaphosphate frit particles can be measured by means of the methods known to one skilled in the art, for [0106] In a preferred embodiment, the composite material example, by means of a dry method using a particle size ofthe present invention comprises a polymer matrix selected distribution laser analyzer such as a MASTERSIZER 2000 from polyethylene terephthalate (PET), high density poly­ from MALVERN. The d90 parameter is statistically deter­ ethylene (HDPE), polyvinyl chloride (PVC), low density mined based on the equivalent size corresponding to 90% by polyethylene (LDPE), polypropylene (PP), polystyrene weight of the population of the cumulative distribution of (PS), poly(methyl methacrylate ), polytetrafiuoroethylene, the partid e size distribution or granulometric curve. In tum, polyamide (PA), ABS resin, cellulose derivatives such as the d50 parameter is statistically determined based on the cellophane, polycarbonates, polyacetals, and fiuoroplastics. equivalent size corresponding to 50% by weight of the [0107] In a more preferred embodiment, the composite population ofthe cumulative distribution ofthe particle size material of the present invention comprises a low density distribution or granulometric curve. In turn, in the context of polyethylene (LDPE) or polypropylene (PP) polymer the present invention, "equivalent size" refers to the diam­ matrix. eter of the sphere having the same specific area as the [0108] In a particular embodiment, the composite material specified particle population. of the present invention comprises a polymer matrix, [0101] In the context of the present invention, the term wherein the polymer matrix comprises at least one thermo­ "embed", in relation to the activated and ground sodium setting polymer; preferably at least one thermosetting poly­ hexametaphosphate frit particles, refers to the introduction mer selected from Hexcel 8852, RTM6, nitrile, silicone, or incorporation of said particles in a polymer matrix by polyamide, vinyl ester, polyester, polyurethane, formalde­ means of processes of the polymer industry known by one hyde, amino urea, epoxy or phenolic resins. skilled in the art. In the context of the present invention, the term "embedded" or "embedded", in relation to the activated [01 09] In the context of the present invention, the expres­ and ground sodium hexametaphosphate frit particles, refers sion "thermosetting polymer" refers to an infusible and to the fact that said particles can be found dispersed or insoluble polymer material, preferably hydrophobic or agglomerated or aggregated, completely surrounded by the water-repellent. polymer matrix. [0110] In a particular embodiment, the composite material [0102] Without being bound to a particular theory, the of the present invention comprises a polymer matrix, authors of the present invention have observed that, when wherein the polymer matrix comprises at least one elastomer the size of the activated and ground sodium hexametaphos­ polymer, preferably at least one elastomer polymer selected phate frit partid es is reduced below d90 corresponding to 50 from natural rubber, polyisoprene, polychloroprene, polyb­ US 2021/0214223 Al Jul. 15, 2021 6

utadiene, styrene-butadiene rubber, acrylonitrile-butadiene antibacterial response against Gram-positive and Gram­ rubber, polychloroprene, neoprene, polyester, polysulfite, negative bacteria, even more preferably against Staphylo­ polyurethane, and silicone. coccus aureus, Listeria innocua, and Escherichia coli. [0111] In a particular embodiment, the composite material [0125] In a preferred embodiment, the composite material of the present invention comprises a polymer matrix with a ofthe present invention exhibits an antimicrobial response, refractive index value comprised between 1.3 and 1.7, preferably an antibacterial response, more preferably an preferably between 1.4 and 1.6. antibacterial response comprising bacteria! population [0112] In a particular embodiment, the composite material reduction (R) values greater than 2, preferably greater than of the present invention comprises a hydrophobic or water­ 3. repellent polymer matrix, preferably hydrophobic. [0126] In a preferred embodiment, the composite material [0113] In a more preferred embodiment, the composite of the present invention exhibits an antimicrobial response material of the present invention comprises a polymer in a hmnid enviromnent, preferably an antibacterial response matrix consisting of a hydrophobic or water-repellent poly­ in a humid enviromnent. mer, preferably hydrophobic. [0127] In a preferred embodiment, the composite material [0114] In the context ofthe present invention, the expres­ of the present invention exhibits an antibacterial response sion "hydrophobic surface" refers to a surface of a material comprising bacteria! population reduction (R) values greater that repels water. than 2 for a time above 24 hours, preferably greater than 3 [0115] In the context of the present invention, the terms for a time above 24 hours. "hydrophobic" and "hydrophilic" are antonyms and refer to [0128] In a preferred embodiment, the composite material the tendency of a material to interact with water. In the of the present invention exhibits an antibacterial response context of the present invention, the term "hydrophobic" comprising bacteria! population reduction (R) values greater refers to a material or substance that repels water or with a than 2 for a time above 1 month, preferably bacteria! low a:ffinity for water and will be used in the sense of population reduction (R) values greater than 3 for a time repelling water. In the context of the present invention, the above 1 month. term "hydrophilic" refers to a material with a:ffinity for [0129] In the context of the present invention, the expres­ water. sion "bacteria! population reduction (R) value" is expressed [0116] In a more preferred embodiment, the composite by means of the following formula: material of the present invention can be formed by means of one or severa! conventional forming methods in the plastic R=Ut-At industry such as in conventional thermoplastic or thermo­ where: setting material fonning processes, for example. Non-lim­ [0130] R: bacteria! population reduction (R) or bacteria! iting examples of forming processes are extrusion, pressure activity reduction or log reduction; molding, blow molding, rotational molding, calendering, [0131] Ut: log mean ofthe count ofbacteria in control vacuum molding, and the like. samples (without antimicrobial treatment) after 24 h of [0117] In a particular embodiment, the composite material incubation; and of the present invention comprises activated and ground [0132] At: log mean of the count of bacteria in the sodium hexametaphosphate frit particles in a mass percent­ age less than 60%, preferably less than 40%, more prefer­ samples with antimicrobial treatment after 24 h of incubation. ably between 0.1% and 40%, even more preferably between 0.5 and 30%. [0133] Therefore, in the context of the present invention [0118] In a particular embodiment, the composite material the munber expressed as bacteria! population reduction (R) of the present invention comprises activated and ground is the log-based capacity for eliminating bacteria which are sodium hexametaphosphate frit particles in a mass percent­ in contact with the surface within a time of 24 hours. The age less than 6%, preferably between 0.1% and 5%, more higher the factor R is, the greater the capacity of the treated preferably between 0.5 and 2.5% by mass. material for eliminating the test microorganisms. [0119] The composite material of the present invention [0134] In a particular embodiment, the composite material comprises activated and ground sodium hexametaphosphate of the present invention prevents the formation of bacteria! frit particles, wherein said particles are embedded in said bio-films or organized microbial ecosystems; it preferably polymer matrix. comprises surfaces preventing the fonnation of bacteria! [0120] In a particular embodiment, the composite material bio-films or organized microbial ecosystems. of the present invention retains water; preferably it retains [0135] In a particular embodiment, the composite material water; more preferably it retains water in a humid environ­ of the present invention is an anti-fouling material. ment. [0136] In a particular embodiment, the composite material [0121] In a particular embodiment, the composite material of the present invention comprises surfaces functionalized ofthe present invention comprises hydrophobic and hydro­ preferably with polyethylene glycol (PEG) or oligoethylene philic areas on the surface thereof. glycol. [0122] The authors ofthe present invention have observed [0137] Without being bound to a particular theory, the that the composite material of the present invention has authors of the present invention have observed that, when antimicrobial properties. the activated and ground sodium hexametaphosphate frit [0123] In a preferred embodiment, the composite material particles ofthe present invention are embedded in a polymer of the present invention has antibacterial properties. matrix in arder to genera te a composite material, a compos­ [0124] In a preferred embodiment, the composite material ite material with antimicrobial properties is surprisingly of the present invention exhibits an antimicrobial response, obtained. Furthermore, it has been observed that said anti­ preferably an antibacterial response, more preferably an microbial properties are maintained for a long time and work US 2021/0214223 Al Jul. 15, 2021 7

on different types of bacteria. Anti-fouling surface charac­ [0153] Furthermore, without being bound to a particular teristics have also been surprisingly observed. theory, the authors of the present invention have observed [0138] In a particular embodiment, the composite material that the activated and ground sodium hexametaphosphate of the present invention is in the form of a sheet or film, frit particles embedded in the polymer matrix have a con­ preferably in the form of a translucent sheet or film, more ductivity value per gram in an aqueous solution that is less preferably in the form of a colorless and translucent sheet of than the same particles not embedded in the polymer matrix. film. (0154] In a particular embodiment, the composite material (0139] In a particular embodiment, the composite material of the present invention further comprises at least one of the present invention is in the fonn of a film with a antimicrobial additive, antibiotic, antifungal, antiparasitics, thickness between 1 and 1000 micra, preferably between 1O antiviral, or antiseptic, preferably an antimicrobial additive. and 500 micra, more preferably between 20 and 200 micra. [0155] In a particular embodiment, the composite material (0140] In a particular embodiment, the composite material of the present invention further comprises at least one of the present invention is in the form of a film with a smooth antimicrobial additive, preferably at least one antimicrobial surface, preferably with a roughness below 2 ¡.un, more additive selected from silver derivatives, copper derivatives, preferably below 1 ¡.tm. zinc derivatives, phenolic biocides, quatemary ammonium [0141] In a particular embodiment, the composite material compounds, titanium oxides, fungicides such as tiabenda­ of the present invention is in the form of a pellet. zole, antimicrobial glass, and combinations thereof. [0156] In the context of the present invention, the term [0142] In the context of the present invention, the term "antimicrobial" refers to substances exhibiting the capacity "pellet" refers to a salid granulated form which the com­ to eliminate, inhibit the growth of, or reduce the presence of posite material of the present invention may adopt for microorganisms such as bacteria, fungi, or parasites, and improved handling and transport. Non-limiting examples of comprises antibiotic, antifungal, antiparasitic, antiviral, or pellet are granule-type amorphous agglomerates, crystalline antiseptic substances. agglomerates (spherulites), small macaroni-like cylinders, [0157] In a particular embodiment, the composite material or glass-like beads. of the present invention comprises silver derivatives, pref­ [0143] In a particular embodiment, the composite material erably positive silver ions (Ag+). of the present invention has a low toxicity. [0158] In a particular embodiment, the composite material (0144] In a particular embodiment, the composite material of the present invention further comprises at least one of the present invention is not toxic. additive selected from plasticizers, stabilizers, lubricants, [0145] In the context of the present invention, the term extenders, wetting agents, pare forming agents, impact "toxicity" refers to a substance which can cause adverse modifiers, flame retardants, foaming agents, fillers, pig­ effects on a living organism when it comes into contact ments, dyes, antistatic agents, adhesion promoters, fortifiers, therewith. anti-wear agents, and combinations thereof. [0146] In a particular embodiment, the composite material [0159] In a particular embodiment, the composite material of the present invention comprises activated and ground of the present invention comprises at least one additional sodium hexametaphosphate frit particles which can be dis­ !ayer comprising a material other than that ofthe composite persed or agglomerated in the polymer matrix. material of the present invention. [0147] In a particular embodiment, the composite material [0160] In a particular embodiment, the composite material of the present invention comprises activated and ground of the present invention comprises organic functional sodium hexametaphosphate frit particles dispersed in the groups, preferably organic functional groups with antibac­ matrix. terial properties. [0148] In a particular embodiment, the composite material of the present invention comprises activated and ground Uses sodium hexametaphosphate frit particles unifonnly dis­ (0161] An additional aspect of the present invention persed in the matrix. relates to the use of the composite material of the present (0149] Without being bound to a particular theory, the invention as an antimicrobial agent, preferably as an anti­ authors of the present invention have observed that the bacterial agent, more preferably as an antibacterial agent antimicrobial properties of the antimicrobial composite against Gram-positive bacteria and Gram-negative bacteria. material are not affected by the state of the activated and (0162] In a particular embodiment, the use of the com­ ground sodium hexametaphosphate frit particles embedded, posite material of the present invention is in the cosmetic, either by being dispersed or agglomerated, in the polymer medica!, and food industry, particularly in the food industry. matrix. (0163] In a more particular embodiment, the composite [0150] The composite material of the present invention material ofthe present invention is used as a protective film comprises activated and ground sodium hexametaphosphate in the food industry, preferably as an antibacterial contact frit particles embedded in said polymer matrix. film. [0151] In a particular embodiment, the composite material (0164] In a particular embodiment, the composite material ofthe present invention increases the dissolution time ofthe of the present invention is used in the industrial sector, in activated and ground sodium hexametaphosphate frit par­ construction, in the packaging industry, in agriculture, and in ticles. consumer industries. (0152] In a particular embodiment, the composite material (0165] In a particular embodiment, the composite material of the present invention comprises normalized conductivity of the present invention is used in the form of containers, values ofless than 0.7 mS.cm- 1.g.ml-1 per gram ofactivated food packaging, bags and packaging, greenhouse plastics, and ground sodium hexametaphosphate frit particles and per raflia, irrigation pipes, films, cutlery, fumishings, electrical milliliter of water after 15 minutes in an aqueous solution. appliances, personal hygiene and personal care products. US 2021/0214223 Al Jul. 15, 2021 8

Method for Obtaining the Composite Material [0181] Furthermore, the method for obtaining the com­ posite material of the present invention comprises all the [0166] One inventive aspect relates toa method for obtain­ features described for the composite material of the present ing the composite material as defined above, comprising the invention in any of the particular embodiments thereof. steps of: [0167] i) providing Examples [0168] a) activated and ground sodium hexameta­ phosphate frit particles obtainable by means of a [0182] The invention is described below by means of the thermal activation method comprising the steps of: following examples which must be considered as merely illustrative and in no way limiting the scope of the present [0169] i) heating a sodimn hexametaphosphate salt invention. until it melts such that a molten sodium hexam­ etaphosphate salt is obtained; Example 1: Obtaining Activated Sodium [0170] ii) abruptly cooling the molten sodium hex­ Hexametaphosphate Frit Particles ametaphosphate salt obtained in step (i) in a dry medimn to obtain activated sodium hexameta­ [0183] Activated sodium hexametaphosphate frit particles phosphate frit particles; and were obtained as follows. 200 grams of sodium hexameta­ [0171] iii) grinding the activated sodium hexam­ phosphate salt with chemical fonnula (NaP03 ) 6 were heated etaphosphate frit particles obtained in step (ii) to in a 600 mi alumina crucible at 10° C./min to a temperature obtain activated and ground sodium hexameta­ of 800° C. and this temperature was maintained for 1 hour. phosphate frit particles; and Then, the molten sodimn hexametaphosphate salt was [0172] b) a polymer matrix; and poured on a bronze plate that was at a room temperature. Said molten salt was therefore cooled abruptly, reaching a [0173] ii) embedding said activated and ground sodium temperature <300° C. in a time less than 1 minute, forming hexametaphosphate frit particles in said polymer irregular fragments in the form of transparent flakes or matrix. granules, i.e., activated sodium hexametaphosphate frit par­ [0174] In a particular embodiment, step (ii) of the method ticles. for obtaining the composite material ofthe present invention comprises embedding said activated and ground sodium Example 2: Obtaining Activated and Ground hexametaphosphate frit particles in said polymer matrix, Sodimn Hexametaphosphate Frit Particles wherein said activated and ground sodimn hexametaphos­ phate frit particles are completely covered by the polymer [0184] Activated sodium hexametaphosphate frit particles matrix. were obtained according to Example 1 and they were then [0175] In a particular embodiment, step (ii) of the method ground to different sizes according to two grinding processes for obtaining the composite material ofthe present invention I and II as described below. The particle sizes were deter­ comprises incorporating the activated and ground sodium mined from the d50 and d90 parameters (also referred toas hexametaphosphate frit particles in said polymer matrix by mass median diameters) of the particles which were deter­ means of processes known by one skilled in the art, pref­ mined by means of a dry method using a particle size erably mixing, melting, and extrusion processes. distribution laser analyzer MASTERSIZER 2000 from MALVERN. The particle size distribution or granulometric Thermal Activation Method curve was statistically determined and characterized by means ofthe d50 and d90 parameters defined as the equiva­ [0176] Finally, a last inventive aspect ofthe present inven­ lent size corresponding to 50% and 90% by weight, respec­ tion relates to a thermal activation method for the thermal tively, of the population of the cumulative distribution. activation of a sodium hexametaphosphate salt in arder to Equivalent size refers to the diameter of the sphere having generate the activated and ground sodium hexametaphos­ the same specific area as the specified particle population. phate frit particles as defined above, comprising the steps of [0177] i) heating a sodimn hexametaphosphate salt until Grinding Method I it melts such that a molten sodium hexametaphosphate [0185] The transparent irregular fragments obtained in salt is obtained; Example 1 were ground by hand to obtain activated sodium [0178] ii) abruptly cooling the molten sodimn hexam­ hexametaphosphate frit with a size smaller than 1 cm. etaphosphate salt obtained in step (i) in a dry medium [0186] The sodium hexametaphosphate frit was dry to obtain activated sodimn hexametaphosphate frit par­ ground in a 1000 mi, porcelain, laboratory planetary mili ticles; and with alumina balls of 14-20 mm for 30 minutes, generating [0179] iii) grinding the activated sodium hexameta­ an activated and ground sodimn hexametaphosphate frit phosphate frit particles obtained in step (ii) to obtain with a particle size distribution characterized by the d50 and activated and ground sodimn hexametaphosphate frit d90 parameters of 16.8 and 80.5¡.tm, respectively. A second partides. dry grinding step using 425 grams of yttrium-stabilized [0180] The composite material, the method for obtaining zirconium microballs having sizes comprised between 0.6 said composite material, and the activation method for the and 1.5 mm in a 400 mi laboratory planetary mili and 100 activation of a sodium hexametaphosphate salt in order to grams of previously ground sodium hexametaphosphate frit generate the activated and ground sodium hexametaphos­ for 30 minutes produced particle sizes with the d50 and d90 phate frit particles of the present invention comprises all the parameters of 11.3 and 52.85 ¡.tm, respectively. An equiva­ features described for the activated and ground sodium lent additional grinding with yttrimn-stabilized zirconium hexametaphosphate frit particles of the present invention in microballs having sizes comprised between 0.3 and 0.6 mm any of the particular embodiments thereof. produced an activated and ground sodium hexametaphos­ US 2021/0214223 Al Jul. 15, 2021 9

phate frit with an average d50 and d90 size of 8.5 and 44.3 Comparative Example 4: Water Absorption ¡.un, said frit was then characterized in Examples 3-5. Capacity of the Activated and Ground Sodium Hexametaphosphate Frit Particles and the Ground Sodium Hexametaphosphate Salt Grinding Method II [0191] For comparison purposes, the water absorption [0187] Altematively, the activated sodium hexametaphos­ capacity of the following components was evaluated: the phate frit particles according to Example 1 were ground by starting sodium hexametaphosphate salt, the starting ground means of an altemative grinding method as follows. The sodium hexametaphosphate salt, the activated sodium hex­ transparent irregular fragments obtained in Example 1 are ametaphosphate frit particles, and the activated and ground fractionated using a tungsten carbide jaw crusher to obtain sodium hexametaphosphate frit particles of Example 3. fragments with size smaller than 200 ¡.un. Said fragments are [0192] The samples were exposed to enviromnental humidity of 40-45% for 48 hours and the water absorption ground in a tungsten carbide ring mili for 1 minute. The capacity was studied by means of thermogravimetric curves grinding resulted in activated and ground sodium hexam­ recorded in TA Instruments TGA QSO equipment. etaphosphate frit particles with a particle size characterized [0193] FIG. 3 depicts the comparative thermogravimetric by a d50 of 4.2 ¡.tm anda d90 of 8.3 ¡.tm, said particles were curves corresponding to the starting sodium hexametaphos­ then characterized in Examples 3-6. phate salt (continuous line, FIG. 3a), the ground sodium hexametaphosphate salt (discontinuous line, FIG. 3a), the Comparative Example 3: Structure of the Activated activated sodium hexametaphosphate frit particles (continu­ and Ground Sodium Hexametaphosphate Frit ous line, FIG. 3b) , and the activated and ground sodium Particles and the Sodium Hexametaphosphate Salt hexametaphosphate frit particles (discontinuous line, FIG. 3b). The main differences that were observed between the [0188] For comparison purposes, the structure of the acti­ samples consisted of the % of weight loss and the tempera­ vated and ground sodium hexametaphosphate frit particles tures at which said weight losses take place. The starting of Example 2 and the sodium hexametaphosphate salt also sodium hexametaphosphate salt experienced a mass loss of ground in the same marmer was evaluated. 2.5% by weight at 600° C., whereas said loss was 5.3% by weight for the activated sodium hexametaphosphate frit [0189] The structure ofthe samples was studied by means particles and 12.8% by weight for the activated and ground ofRaman spectroscopy by means ofBWTEK 785S i-Raman sodium hexametaphosphate frit particles. equipment with a 785 mn laser. FIG. 1 shows the Raman spectra obtained for (a) activated and ground sodium hex­ Comparative Example 5: Rate of Dissolution of the ametaphosphate frit particles (continuous line) and for (b) Activated and Ground Sodium Hexametaphosphate Frit Particles and the Ground Sodium ground sodium hexametaphosphate salt (discontinuous Hexametaphosphate Salt Particles line). The main Raman modes characteristic ofthe sodium hexametaphosphate structure were present in the two [0194] For comparison purposes, the rate of dissolution of samples as follows: vibrational modes of the symmetric the ground sodium hexametaphosphate salt and the activated stretching of the oxygen bridge between P- 0 - P tetrahe­ and ground sodium hexametaphosphate frit particles of drons located at about 683 cm-1, symmetric stretching ofthe Example 3 with an average d50 and d90 size of8.5 and 44.3 terminal oxygen atoms in the P0 units that are doubly ¡.tm was evaluated. To that end, conductivity variation in a 2 suspension of0.5 grams ofthe product to be evaluated in 50 conuected forming Q2-type tetrahedral chains at about 1163 mi of deionized water, the conductivity value of which is cm-1, and symmetric stretching of the P= OR terminal 12.6 ¡.tS/cm, was determined. oxygen atoms found in Q3-type, three-dimensional, tetra­ 1 [0195] FIG. 4 shows the conductivity values (mS/cm) with hedral nets located at about 1280 cm- . Vibrational modes respect to time for the ground sodium hexametaphosphate below 400 cm-1 correspond to tetrahedral chain net bending salt (square symbol) and for the activated and ground modes. sodium hexametaphosphate frit particles (round symbol). [0190] FIG. 2 shows a sample enlargement ofthe Raman Although the maximum conductivity reached in both cases spectra obtained for (a) activated and ground sodium hex­ was the same at 3.83 mS/cm (FIG. 4), in the frit particles this ametaphosphate frit particles (continuous line) and for (b) value was reached at 200 seconds, whereas the salt requires ground sodium hexametaphosphate salt (discontinuous a longer time to reach said value, about 450 seconds. The line). Structurally, the main difference between ground values obtained for the activated and ground sodium hex­ sodium hexametaphosphate salt and activated and ground ametaphosphate frit particles with a particle size character­ sodium hexametaphosphate frit particles consisted of a ized by a d50 of 4.2 ¡.tm and a d90 of 8.3 ¡.tm of Example 2 smaller red shift of the Raman mode corresponding to the were similar to those of the activated and ground particles symmetric stretching of the terminal oxygen atoms in the with an average d50 and d90 size of 8.5 and 44.3 ¡.tm.

P02 units formed by Q2-type tetrahedral chains which Therefore, the activated and ground sodium hexametaphos­ decreases from a ground salt Raman shift value of 1163 phate frit particles have a higher rate of dissolution than the cm-1 to a ground frit value of 1161.5 cm-1 (FIG. 2). This initial ground sodium hexametaphosphate salt. lower Raman shift value for the activated and ground sodium hexametaphosphate frit particles is associated with a Example 6: Encapsulating the Activated and smaller force constant of said bond or with a longer bond Grmmd Sodium Hexametaphosphate Frit Particles length. Therefore, the Q2 tetrahedral net in the ground frit in a Polymer Matrix to Yield a Composite Material has a more open net in comparison to the starting material [0196] The activated and ground sodium hexametaphos­ of the sodium hexametaphosphate sal t. phate frit particles with a particle size characterized by a d50 US 2021/0214223 Al Jul. 15, 2021 10

of 4.2 ¡.tm and a d90 of 8.3 ¡.tm of Example 2 were LDPE polymer matrix of Example 6 was evaluated. The incorporated in a low density polyethylene, LDPE. conductivity variation of 0.056 g of a composite material [0197] First, the particles were incorporated in a LDPE film containing 2% by weight of activated and ground polymer pellet generating a concentrated product or mas­ sodium hexametaphosphate frit to be evaluated in 100 mi of terbatch. To that end, the activated sodimn hexametaphos­ deionized water, the conductivity value of which is 3.3 phate frit particles were dried at a temperature between 80 ¡.tS.cm- 1, was determined. FIG. 6 shows the conductivity and 160° C. The activated and ground sodium hexameta­ values (¡.tS/cm) with respect to time for the activated and phosphate frit particles were then incorporated in the poly­ ground sodium hexametaphosphate frit particles embedded mer in a weight percentage of 20% by means of polymer in a low density polyethylene. The composite material mixing, melting, and extrusion processes. In a first step, the reached a conductivity of 5.5 ¡.tS.cm- 1 at about 900 seconds polymer was melted or heated to a viscoelastic state, mixed given that the water conductivity was 3.3 ¡.tS.cm-1, the with the activated and ground sodium hexametaphosphate activated sodium hexametaphosphate frit particles encapsu­ frit particles. The polymer that is melted (or in viscoelastic lated in the polymer provided 2.2 ¡.tS.cm- 1 to the water state) was then forced through a die, also referred to as a conductivity. The normalized conductivity value given per head, by means of the thrust generated by the rotary action unit of gram of salt and per milliliter of water after 15 of a concentrically-rotating screw, and it is passed through minutes would correspond to 0.196 mS.cm- 1 g.ml- 1 which a mold in charge of rendering it the desired shape in a is a value substantially lower than the values reached by the double-screw extruder in a temperature range between 160 "free" activated and grmmd sodium hexametaphosphate frit and 205 ° C., the masterbatch or concentrated material of particles at that same time in Example 5 corresponding to 1 activated and ground sodium hexametaphosphate frit par­ 0.766 mS.cm- g.ml- • The dissolution of the activated and ticles encapsulated in a polymer matrix being obtained. ground sodium hexametaphosphate frit particles embedded [0198] By means of adding the LDPE pellet to the con­ in a polymer in an aqueous solution thereby decreases centrated product or masterbatch described above and by significantly, so the time the inorganic particles are available means of a new mixing, melting, and extrusion method, a in the polymer matrix increases. composite material with a mass percentage of activated and ground sodium hexametaphosphate frit particles embedded Example 9: Characterizing the Surface of the in the polymer film of 2% and a thickness of 80±4 ¡.tm was Composite Material Comprising Activated and obtained. Said composite material has a uniform appearance Ground Sodium Hexametaphosphate Frit Particles and a high transparency as a result of the refractive index Encapsulated in a Polymer Matrix values ofthe frit particles of 1.48 and ofthe LDPE of 1.51. (0202] The surface of a film formed by the composite The percentage of activated and ground sodium hexameta­ material comprising activated and ground sodium hexam­ phosphate frit particles which are incorporated in the LDPE etaphosphate frit particles encapsulated in a polymer matrix polymer matrix was changed from 0.1 to 5% by mass, according to Example 6 was characterized. similar results being observed. (0203] Said film was immersed in water for at least 15 (0199] The same process for obtaining a concentrated minutes. It was then extracted, dried in an oven at 60° C. for composite material and for obtaining a composite material 1 hour, and observed again by means of Raman confocal with concentrations of activated and ground sodium hexam­ microscopy. FIG. 7a shows an optical confocal image in etaphosphate frit particles from 0.1% to 5% by weight was which there is observed on the surface ofthe polymer (2) the repeated using polypropylene (PP). Furthermore, the pro­ presence of smallliquid droplets (3) found in the proximity cess was also repeated to obtain the corresponding compos­ of the frit particles (4). In other words, said areas of the ite materials from hexametaphosphate salt particles. surface of the composite material clase to an activated sodium hexametaphosphate frit particle act as hydrophilic Example 7: Characterizing the Activated and areas and the rest of the surface acts as hydrophobic areas. Ground Sodium Hexametaphosphate Frit Particles [0204] FIG. 7b shows the Raman spectra characteristic of Encapsulated in a Polymer Matrix the main elements (4), (3), and (2) shown in FIG. 7a. A [0200] The composite material described in Example 6 Raman spectroscopy analysis of the nature of the spherical with 2% of activated and ground sodium hexametaphos­ liquid droplets (3) confirmed that said droplets contain water phate frit particles was characterized by means of Raman due to the presence of a Raman band located in the 3000­ 1 confocal microscopy (WITEC Alfa 500). FIG. 5 shows a 3500 cm- region and sodium hexametaphosphate structural Raman image in which each pixel ofthe image corresponds units similar to those present in the activated and ground with a Raman spectrum. The activated and ground sodium sodium hexametaphosphate frit particles dispersed and hexametaphosphate frit particles are embedded in an iso­ encapsulated (4) in the polymer film (2). The liquid droplets lated manner (with contour anda darker color and indicated are therefore stabilized by the presence of sodium hexam­ with (1)) isolated in the continuous LDPE polymer matrix etaphosphate structural units, particularly by the presence of (with a lighter color and indicated with (2)). FIG. 5 shows an oxygen bridge between the P-0- tetrahedrons that are the activated and ground frit particles which are inside the shifted considerably to blue and ofthe symmetric stretching LDPE film with particle size values below 15 micra. modes of the terminal oxygen atoms in the P02 units that are shifted to red. Said structural modifications are indicative of Example 8: Rate of Dissolution of the Activated the presence of depolymerized phosphorus tetrahedral units. and Ground Sodium Hexametaphosphate Frit Likewise, the Raman spectra demonstrated that the activated Particles Encapsulated in a Polymer Matrix and ground sodium hexametaphosphate frit particles encap­ sulated in the polymer matrix (4) have water inside the [0201] The rate of dissolution of the activated and ground polymer film after the immersion thereof in water. After the sodium hexametaphosphate frit particles encapsulated in a immersion thereof in water, the active, ground frit particles US 2021/0214223 Al Jul. 15, 2021 11

dispersed inside the polymer experience, to a lesser extent, in ISO 22196. Then, a sterile plastic film was deposited on a depolymerization process. The presence of droplets con­ each aliquot such that a thin !ayer of the suspension was taining water and depolymerized phosphorus tetrahedral generated below the film and in contact with the antibacte­ units allow for the coexistence of polymer regions with rial surface of the sample. After inoculation, microorganism hydrophobic characteristics along with hydrophilic regions count was performed on 3 samples to determine the amount related to the presence of activated and ground sodium ofrecovered microorganisms befare incubation. To that end, hexametaphosphate frit particles incorporated in the poly­ the inoculated samples were introduced in a Stomacher® mer matrix. bag to which 10 mi of culture broth (agar with lecithin, [0205] FIG. 8 shows the surface of the polymer film polysorbate SCDLP) was added. The sample and the film formed by the composite material comprising activated and were then washed such that the microorganisms present ground sodium hexametaphosphate frit particles encapsu­ therein are recovered in the broth. With the resulting solu­ lated in a polymer matrix according to Example 6. Said film tion, the microorganisms in the plate count agar (PCA) was exposed to environmental humidity for 60 days and culture medium were counted at an incubation temperature observed by means of scanning electron microscopy (FE­ of 35±1 o C. for 48 hours. SEM Hitachi S-4700). The film was observed after drying in [0213] After inoculating the rest ofthe samples, they were an oven at 60° C. for 1 hour and after depositing a gold !ayer incubated for 24±1 h at 35±1 o C. and ata minimum relative <1 00 nm on the surface thereof. The film shows the presence humidity of 90%. After the incubation period, and following of multiple liquid droplets distributed on the surface of the the previously indicated method, counting of the samples polymer film (FIG. 8b) . The distances between adjacent was performed to determine the antibacterial activity value liquid droplets observed on the surface of the composite of the test materials. material are less than 1O ¡.un, with there being regions where [0214] Based on the obtained results, the antibacterial the distance between droplets is even less than 1 ¡.un. These activity which will be expressed by means of the bacteria! droplets are generated as a result of the existence of vacuum population reduction (R) value defined as follows was in the observation chamber of the electron microscope and calculated: indicate the positions ofthe ground frit particles dispersed in R=Ut-At the polymer matrix. This arrangement ofhydrophilic regions on a hydrophobic surface represents an unexpected aspect of where: the encapsulation of the ground frit partides of the present [0215] R: bacteria! population reduction (R) or bacteria! invention. These surfaces are characteristic of anti-fouling activity reduction or log reduction; surfaces that are usually designed from hydrophobic and [0216] Ut: log mean of the count of bacteria in control hydrophilic polymer mixtures. samples (without antimicrobial treatment) after 24 h of incubation; and Example 10: Antimicrobial Assay of the Surface of [0217] At: log mean of the count of bacteria in the the Composite Material Comprising Activated and samples with antimicrobial treatment after 24 h of Ground Sodium Hexametaphosphate Frit Particles incubation. Encapsulated in a Polymer Matrix [0218] The number expressed as bacteria! population [0206] Antibacterial assays were performed based on ISO reduction (R) value is the log-based capacity for eliminating 22196:2011 standard. Measurement of antibacterial activity bacteria which are in contact with the surface treated with on plastics and other non-porous surfaces. the antibacterial agent within a time of 24 hours. The higher [0207] Antimicrobial assays were performed on 8 samples the factor R is, the greater the capacity ofthe treated material consisting of a colorless and translucent polymer sheet. Two for eliminating the test microorganisms. types of polymers, i.e., low density polyethylene (LDPE) [0219] The assays were repeated in cultures kept under and polypropylene (PP), were studied. Four samples were incubation conditions for one month. assayed for each polymer: a polymer sheet, a polymer sheet incorporating 1% by weight of hexametaphosphate salt, a TABLE 1 polymer sheet incorporating 0.5% by weight of activated Results of the antimicrobial assays and ground sodium hexametaphosphate frit microparticles, anda polymer sheet incorporating 1% by weight ofactivated R and ground sodium hexametaphosphate frit microparticles. In both cases, the films made ofplastic material were cut into S. Aureus L. Inn ocua E. Coli pieces measuring 5x5 cm befare performing the assay. t = 24 t = 1 t = 24 t = 1 t = 24 t = 1 [0208] The following microorganisms were used to per­ Composition h month h month h month form the assay: Control [0209] Gram-positive bacteria: Staphylococcus aureus LDPE and Listeria innocua; and LDPE + 1% [0210] Gram-negative bacterium: Escherichia coli salt [0211] The test microorganisms were pre-incubated and LDPE + 0.5% 4.08 3.27 4.44 2.7 4.10 5.62 frit cultured according to the requirements ofiSO 22196. After LDPE + 1% 2.34 4.65 4.44 4.57 4.72 5.62 reconstitution, an inoculum ata concentration of 106 cfu/ml frit was prepared for each of the microorganisms. Control PP pp + 1% [0212] The samples (polymer sheets) were placed in ster­ salt ile plates and each of them was inoculated with aliquots of pp + 0.5% 4 .02 5.33 4.17 3.29 5.74 4 .32 the suspension prepared from the test microorganism used in frit each case, according to the size of the surface, as indicated US 2021/0214223 Al Jul. 15, 2021 12

TABLE 1-continued TABLE 2

Results of the antimicrobial assays Antimicrobial assays by means of an ATP marker

R Sample RLU (24 hours)

S. Aureus L. Innocua E. Coli Standard water 1995 Present invention: LDPE with 1% 158 t ~ 24 t ~ 1 t ~ 24 t ~ 1 t ~ 24 t ~ 1 frit Composition h month h month h month LPDE sheet without additive 617 Comparative material: LDPE with 299 pp + 1% 4.02 4.17 4.17 3.29 5.74 5.29 1.6% by weight of antimicrobial frit glass containing Ag+, obtained by means of extrusion

[0220] The R values correspond with an effective micro­ [0226] Table 2 shows the results of the antimicrobial bial product for both types of Gram-positive and Gram­ assays performed on the different samples under study. The negative bacteria. Table 1 shows the results of the antimi­ performed assays demonstrated that the antimicrobial capac­ crobial assays perfonned on the different samples under ity studied by means of the ATP test shows a greater study. It should be pointed out that, while the control reduction of relative light units for a composite material samples and the samples of a polymer material comprising comprising activated and ground sodium hexametaphos­ the initial sodium hexametaphosphate salt did not yield any phate frit particles encapsulated in a polymer matrix than for R value, the samples of a composite material comprising a composite material comprising a standard antimicrobial activated and ground sodium hexametaphosphate frit par­ additive based on glass comprising positive silver ions ticles encapsulated in a polymer matrix yielded R values (Ag+). greater than 2, and R values >3 are recorded in most assays. [0227] Having sufficiently described the nature of the Therefore, Table 1 demonstrates the antimicrobial effect of present invention as well as at least one way ofputting it into activated and ground sodium hexametaphosphate frit par­ practice, it only remains to be said that changes in terms of ticles encapsulated in a polymer matrix. form, materials, and arrangement can be introduced in the [0221] Furthermore, the R values over 24 hours in time for present invention as a whole and in parts making up same the composite materials comprising 0.5 to 1% by mass of provided that said alterations do not substantially change activated and ground frit particles should be highlighted. said invention.

1.-22. (canceled) Example 11: Antimicrobial Assay of the Surface of the Composite Material Comprising Activated and 23. A composite material comprising: Ground Sodium Hexametaphosphate Frit Particles a) activated and ground sodium hexametaphosphate frit Encapsulated in a Polymer Matrix particles obtainable by means of a thermal activation method comprising the steps of: [0222] The antimicrobial capacity of a polymer sheet i) heating a sodium hexametaphosphate salt until it made of the composite material comprising activated and melts such that a molten sodium hexametaphosphate ground sodium hexametaphosphate frit particles encapsu­ salt is obtained; lated in a polymer matrix was studied. To that end, the developed Clean-Trace™ surface total ATP technique for ii) abruptly cooling the molten sodium hexametaphos­ phate salt obtained in step (i) in a dry medium to evaluating microorganism load with an ATP marker was u sed. obtain activated sodium hexametaphosphate frit par­ ticles; and [0223] A Gram-negative bacterium, Proteus mirabilis, iii) grinding the activated sodium hexametaphosphate was used to perform the assay. Said bacterium was diluted frit particles obtained in step (ii) to obtain activated 1 in water in a proportion of !Íoo, forming an initial load of and ground sodium hexametaphosphate frit particles; 4365 RLU (relative light units ). After 24 h, the bacterialload and in said aqueous solution was measured, with an RLU of 1995 being obtained (Table 2). b) a polymer matrix; wherein said activated and ground sodium hexametaphos­ [0224] The samples evaluated as polymer sheets are the phate frit particles are embedded in said polymer matrix. composite material comprising activated and ground sodium hexametaphosphate frit particles encapsulated in a LDPE 24. The composite material according to claim 23, polymer matrix with a load of 1% by weight of frit particles wherein in step (ii) the temperature is reduced from the salt in comparison to the same product without said particles. melting temperature to a temperature below 500° C. in less Furthermore, in the same assay, an LDPE polymer sheet than one minute. comprising a load of 1.6% by weight of a soluble silver 25. The composite material according to claim 23, the antimicrobial glass was also evaluated. All the samples had activated and ground sodium hexametaphosphate frit par­ the same size, mass, and thickness. ticles have a d90 parameter below 1O micra. [0225] The results were compiled in RLU (relative light 26. The composite material according to claim 23, units), determining the presence of bacteria in water, by wherein the activated and ground sodium hexametaphos­ means of ATP, which is an energy measurement and indi­ phate frit particles comprise a mass percentage of absorbed cates the presence of bacteria. water greater than 2.5%. US 2021/0214223 Al Jul. 15, 2021 13

27. The composite material according to claim 23, iii) grinding the activated sodium hexametaphos­ wherein the activated and ground sodium hexametaphos­ phate frit particles obtained in step (ii) to obtain phate frit particles have refractive index values comprised activated and ground sodium hexametaphosphate between 1.4 and 1.6. frit particles; and 28. The composite material according to claim 23, b) a polymer matrix; and wherein said composite material comprises the activated and ii) embedding said activated and ground sodium hexam­ ground sodium hexametaphosphate frit particles in a mass etaphosphate frit particles in said polymer matrix. percentage less than 60%. 37. The method for obtaining the composite material 29. The composite material according to claim 23 , according to claim 36, wherein in step (ii) the temperature wherein said composite material comprises the activated and is reduced from the salt melting temperature to a tempera­ ground sodium hexametaphosphate frit particles in a mass ture below 500° C. in less than one minute. percentage comprised between 0.1 and 5%. 38. Activated and ground sodium hexametaphosphate frit 30. The composite material according to claim 23, partides obtainable by means ofa thermal activation method wherein the polymer matrix is hydrophobic. comprising the steps of: 31. The composite material according to claim 23, i) heating a sodium hexametaphosphate salt until it melts wherein the polymer matrix comprises at least one thermo­ such that a molten sodium hexametaphosphate salt is setting polymer, at least one thermoplastic polymer, or obtained; combinations thereof. ii) abruptly cooling the molten sodium hexametaphos­ 32 . The composite material according to claim 23, com­ phate salt obtained in step (i) in a dry medium to obtain prising normalized conductivity values of less than 0.700 activated sodium hexametaphosphate frit particles; and mS.cm- 1 .g.ml- 1 per gram of frit particles and milliliters of iii) grinding the activated sodium hexametaphosphate frit water of activated and ground sodium hexametaphosphate particles obtained in step (ii) to obtain activated and frit particles after 15 minutes in an aqueous solution. grmmd sodium hexametaphosphate frit particles. 33. The composite material according to claim 23, com­ 39. Activated and ground sodium hexametaphosphate frit prising hydrophobic and hydrophilic areas on the surface particles according to claim 38, wherein in step (ii) the thereof. temperature is reduced from the salt melting temperature to 34. The composite material according to claim 23, com­ a temperature below 500° C. in less than one minute. prising at least one antimicrobial additive. 40. A thermal activation method for the thermal activation 35. The composite material according to claim 34, of a sodium hexametaphosphate salt in arder to generate the wherein said at least one antimicrobial additive is selected activated and ground sodium hexametaphosphate frit par­ from sil ver derivatives, copper derivatives, zinc derivatives, ticles defined in claim 38, comprising the steps of: phenolic biocides, quaternary ammonium compounds, tita­ i) heating a sodium hexametaphosphate salt until it melts nium oxides, fungicides, antimicrobial glass, and combina­ such that a molten sodium hexametaphosphate salt is tions thereof. obtained; 36. Amethod for obtaining the composite material defined ii) abruptly cooling the molten sodium hexametaphos­ in claim 23 , comprising the steps of: phate salt obtained in step (i) in a dry medium to obtain i) providing activated sodium hexametaphosphate frit particles; and a) activated and ground sodium hexametaphosphate frit iii) grinding the activated sodium hexametaphosphate frit particles obtainable by means of a thermal activation particles obtained in step (ii) to obtain activated and method comprising the steps of: ground sodium hexametaphosphate frit particles. i) heating a sodium hexametaphosphate salt until it 41. The thermal activation method according to claim 40, melts such that a molten sodium hexametaphos­ where in step (ii) the temperature is reduced from the salt phate salt is obtained; melting temperature to a temperature below 500° C. in less ii) abruptly cooling the molten sodium hexameta­ than one minute. phosphate salt obtained in step (i) in a dry medium 42 . The composite material according to claim 35, to obtain activated sodium hexametaphosphate frit wherein the fungicide comprising tiabendazole. partides; and * * * * *