US 20100139855A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2010/0139855A1 Edler et al. (43) Pub. Date: Jun. 10, 2010

(54) POLYMERS HAVING A HIGH (30) Foreign Application Priority Data ABSORPTION CAPACITY Aug. 15, 2005 (DE) ...... 102005038774.8 (76) Inventors: Gerhard Edler, Trebur (DE); Rainer Linzmeier, Gross-Zimmern Publication Classification (DE) (51) Int. Cl. Correspondence Address: Sk 54 :08: MILLEN, WHITE, ZELANO & BRANGAN, P.C. CSK 9/02 (200 6. 01) 2200 CLARENDON BLVD., SUITE 1400 CSK 700 (2006.015 ARLINGTON, VA 22201 (US) (52) U.S. Cl...... 156/272.2:523/200: 523/216 (21) Appl. No.: 12/063,817 (57) ABSTRACT (22) PCT Filed: Jul. 26, 2006 The present invention relates to polymers comprising absorp (86). PCT No.: PCT/EP06/07385 tion pigments, which are distinguished by the fact that they have high absorption in the near IR region, and to the use S371 (c)(1), thereof, in particular in thermoforming and in IR light weld (2), (4) Date: Feb. 14, 2008 1ng. Patent Application Publication Jun. 10, 2010 US 2010/O139855A1

Temperature behaviour of film under the influence of an IR emitter

O 100 200 300 400 500 600 7OO Time in sec US 2010/O 139855A1 Jun. 10, 2010

POLYMERS HAVINGA HIGH INFRARED 0010 Surprisingly, it has now been found that the addition ABSORPTION CAPACITY of absorption pigments based on finely divided pale or trans parent semiconductor materials gives a polymer system which has high absorption in the near IR, in particular in the 0001. The present invention relates to polymers which are region from 750 to >2500 nm, very particularly preferably in distinguished by the fact that they have high absorption in the the region from 850 to 2500 nm, without changing the colour near IR region, and to the use thereof, in particular in ther in the visible region. Although the absorption pigment has moforming and in IR light . very high absorption in the near IR, the pigment is itself 0002 The heating of plastics using IR radiation is wide virtually white and thus only influences the properties of the spread in the area of thermoforming, Such as the deep drawing polymer, Such as colour and transparency, to an insignificant of plastic sheets and films, and the conditioning of preforms extent. Furthermore, the absorption pigment increases the for stretch blow moulding. However, this radiation is also thermal conductivity within the polymer matrix and acceler employed for accelerating polymerisation and curing pro ates polymerisation and curing processes. cesses and the welding of plastic parts. 0011. The invention therefore relates to polymers, prefer 0003. The IR source used here are hot bodies which emit ably , which comprise, as absorption pigment, IR radiation over a broad wavelength spectrum. The higher pale or transparent particulate semiconductor materials or the temperature of the radiating body, the higher also the particulate substrates coated with pale or transparent semi emitted energy and the shorter the wavelength. The electro conductor materials. magnetic spectrum of IR sources can be divided into three 0012 Suitable pale or transparent semiconductor materi regions in accordance with their wavelength: als are preferably those which absorb in the near IR region, in particular in the region from 750 to 2500 nm. The particulate semiconductor materials are preferably spherical, needle shaped or flake-form particles or flake-form, spherical or IR type Wavelength (nm) Temperature C. needle-shaped Substrates coated with semiconductor materi Short 1000-1500 1SOO-2700 als. Moderate 1500-2SOO 750-1500 0013 The semiconductor materials are built up homoge Long 3OOO-SOOO 200-7SO neously from pale or transparent semiconductor materials or applied as coating to a particulate Substrate. The semiconduc 0004 More recent developments in emitter technology tor materials are preferably based on oxides and/or sulfides, even reach wavelengths of up to 800 nm, i.e. as far as the Such as, for example, indium oxide, antimony oxide, tin region of visible light. oxide, zinc oxide, zinc sulfide, tin sulfide or mixtures thereof. 0005 Since high-temperature emitters emit more energy, 0014 Suitable semiconductor materials generally have they represent the best heat source. However, most polymer particle sizes of 0.01 to 2000 um, preferably 0.1 to 100 um, in groups only exhibit good absorption in a range from 2900 to particular 0.1 to 30 um. 3700 and above 5500 nm. This means that the energy of very 0015 The semiconductor materials either consist homo effective high-temperature emitters cannot be utilised suffi geneously of the said semiconductors or are particulate, pref ciently for heating polymeric systems. erably spherical, needle-shaped or flake-form substrates 0006. In the case of pigmented plastics, the situation is which are mono- or multicoated with the said semiconductor even more complex, since the absorption and reflection of the materials. The substrates are preferably coated with only one pigment are now added. Black pigments have high absorption layer. in the near infrared and therefore heat up very quickly in the 0016. The substrates can be spherical, flake-form or short-wave IR. White pigments, by contrast, reflect visible needle-shaped. The shape of the particles is not crucial perse. light very well, and this property is valid into the IR region. In In general, the particles have a diameter of 0.01-2000 um, the case of pale colours, this results in a significant delay in particularly 0.1-300 um and in particular 0.5-60 lum. The heating compared with black or dark colours. Owing to this particularly preferred substrates are spherical and flakeform delay, it not only takes much longer until, for example, a pale substrates. Suitable flake-form substrates have a thickness plastic sheet has reached the forming temperature necessary between 0.02 and 5um, in particular between 0.1 and 4.5um. for thermoforming, but the long dwell time may even result in The size in the two other dimensions is generally between 0.1 damage to the plastic Surface. and 1000 um, preferably between 1 and 500 um and in par 0007. However, the absorption pigments known from the ticular between 1 and 60 um. prior art, such as, for example, carbon black, all have the 0017. The substrates are preferably natural or synthetic disadvantage that they permanently colour the plastic. In mica flakes, SiO flakes, Al-O flakes, glass flakes, alu addition, they have to be added in comparatively high con minium flakes, BiOCl flakes, SiO, beads, silica gel, kiesel centrations and are frequently toxicologically unacceptable. guhr, glass beads, hollow glass beads, TiO, beads, polymer 0008. The object of the present invention was to find a pale beads, for example comprising or , or or white plastic colouring which simultaneously has good TiO, needles, or mixtures of the said substrates. absorption in the near infrared region and can be carried out in 0018. The coating of the particulate substrates with the a simple manner. The absorber material must exhibit pro semiconductor materials is either known or can be carried out nounced absorption and an adequate reaction in this specific by processes known to the person skilled in the art. The NIR region. substrates are preferably coated by hydrolysis of the corre 0009. The absorber here should be easy to incorporate into sponding metal salts. Such as, for example, metal chlorides or the polymer system, have high transparency and only be metal Sulfates, metal alkoxides or carboxylic acid salts in employed in low concentrations. aqueous or conventional solvent solution. US 2010/O 139855A1 Jun. 10, 2010

0019. In the case of the semiconductors with a homoge mance, can be added to the plastics. Suitable colorants are, in neous structure and also in the case of the Substrates coated particular, coloured metal oxide pigments and organic pig with one or more semiconductor materials, the semiconduc ments and dyes. tor material preferably has a microcrystalline structure. 0031 All known polymer systems, in particular thermo 0020 Particularly preferred absorption pigments are plastics and thermoelastic plastics, as described, for example, flake-form or spherical tin oxide, antimony oxide, indium tin in Ullmann, Vol. 15, pp. 457 ff. Verlag VCH, can be doped oxide (ITO) and mica flakes coated with ITO, tin oxide or with the absorption pigments. Suitable plastics are thermo antimony oxide, and mixtures of the said oxides. plastics and thermoelastic plastics, such as, for example, 0021 Particularly preferred absorption pigments are (PE, HDPE, LDPE), (PP), transparent or pale semiconductor materials having a powder , polyesters, polyester-esters, polyether-esters, resistance of <20 S2 m, preferably <5 S2 m. polyphenylene ether, polyacetals, polyalkylene terephtha 0022. A particularly preferred absorption pigment is a tin lates, in particular polybutylene terephthalate (PBT) and oxide doped with antimony oxide or a substrate coated there polyethylene terephthalate (PET), polymethyl methacrylate with, such as, for example, a mica flake. Preference is fur (PMMA), polyvinyl acetal, (PVC), thermore given to spherical SiO particles coated with anti polyphenylene oxide (PPO), (POM), mony oxide-doped tin oxide. The particle sizes of these polystyrene (PS), acrylonitrile-butadiene-styrene (ABS), preferred absorption pigments are preferably 1-2 um. acrylonitrile-styrene-acrylate (ASA), acrylonitrile-butadi 0023 Besides antimony, preferably antimony oxide, the ene-styrene (ABS), (PC), polyether sulfones, elements of main group 3, 5 and 7 are suitable as dopant, polyurethanes (TPU) and polyether ether ketones (PEEK), preferably the halides, in particular chlorides and fluorides. and copolymers, mixtures and/or polymer blends thereof, 0024. The doping is dependent on the semiconductor such as, for example, PC/ABS, MABS. Besides the thermo material employed and is generally 0.01-30% by weight, plastics and thermoelastic plastics, thermosets, elastomers, preferably 0.1-25% by weight, in particular 1-16% by weight, biopolymers (semisynthetic plastics or modified natural based on the semiconductor material. products) are furthermore suitable. 0.025 Preferred mixtures are indium tin oxides with anti 0032. The absorption pigment is incorporated into the mony-doped tin oxides and indium tin oxide with doped Zinc polymer System by mixing the plastic granules with the oxides. absorption pigment and then shaping the mixture under the 0026. It is also possible to add mixtures of two, three or action of heat. During incorporation of the absorption pig more absorption pigments to the polymer system, where the ment, it is furthermore possible to add colour and/or effect mixing ratio is unlimited. The total concentration is depen pigments and optionally additives. Such as, for example, dent on the polymer composition, but should not be greater adhesives, organic polymer-compatible solvents, stabilisers than 30% by weight in the polymer system. and/or surfactants which are heatstable under the working 0027. Owing to the high absorption rate, the absorption conditions, to the plastic granules. The polymer system pigment is effective in the polymer system even in relatively according to the invention is generally prepared by charging low concentration of <1%. This also enables use in natural a suitable mixer with the plastic granules, wetting the latter coloured plastics, to which it merely imparts a slight haze. with any additives and then adding and mixing-in the absorp The absorption pigment can be added in amounts of 0.1-30% tion pigment. The pigmentation of the plastic with (in)organic by weight, preferably 0.3-20% by weight, based on the poly colour, white, black and/or effect pigments is generally car mer system. Taking into account efficacy and economy, the ried out via a colour concentrate (masterbatch) or compound. range from 0.3 to 10% by weight is particularly preferred. 0033. The resultant mixture can then be processed directly 0028. However, the concentration of the absorption pig in an extruder or injection-moulding machine. The mouldings ment in the polymer is dependent on the plastic employed. formed during processing exhibit a very homogeneous distri The low proportion of absorption pigment changes the plastic bution of the absorption pigment. Thermoforming or IR system insignificantly and does not influence its processabil welding is Subsequently carried out using a suitable IR light ity. SOUC. 0029. The uniform distribution of the absorption pigment 0034. The invention also relates to a process for the prepa throughout the plastic matrix causes heating of the plastic ration of the polymer system according to the invention hav material even in the interior of the material. A more uniform ing high absorption in the near infrared, characterised in that heat distribution over the entire cross section is thus obtained. a polymer or plastic granules, preferably a , is Particularly in the case of thick-walled parts, this reduces the (are) mixed with the absorption pigment and optionally fur formation of internal stresses during thermoforming of the ther additives and then shaped under the action of heat. plastic material, significantly shortens the warm-up time and 0035. The polymers according to the invention are particu prevents damage to the plastic Surface. At the same time, the larly Suitable for thermoforming, such as the deep drawing of shortening of the heat-up time reduces the energy require plastic sheets and films, and the conditioning of preforms for ment, which is in turn associated with significantly lower stretch blow moulding, for example PET bottles. production costs. 0036. The injection stretch blow moulding of hollow ware 0030 Transparent thermoplastics comprising the said is carried out starting from injection-moulded preforms, absorption pigments in pure colouring exhibit a slight haze, which have to be brought to the corresponding stretching but retain their transparency. The addition of 0.2 to 10% by temperature (for example 90-120° C. in the case of PET) weight, preferably 0.5 to 3% by weight, of opaque pigments, before the actual stretch blow moulding operation. This is Such as, for example, titanium dioxide, can, if required, com frequently carried out with the aid of a series of IR emitters, pletely hide this haze, in particular in polyolefins. Further past which the preforms are transported with rotation. The use more, colorants, which allow colour variations of any type of the plastics according to the invention having high absorp and at the same time ensure retention of the absorber perfor tion compared with conventional plastics results in faster US 2010/O 139855A1 Jun. 10, 2010

heating of the preforms. Depending on the cycle time of the maximum emitter power. 10 Elstein FRS/2 emitters having a blow-moulding unit, either the cycle time can thus be reduced power of 200 W each are used. The maximum achievable or alternatively the length of the emitter Zone can be short temperature is 600° C. The heat-up time required for an ened. In both cases, the energy costs per finished part are optimum result which is comparable between the individual reduced. The absorption pigment enables the heating rates of films is measured in each case: the polymer systems to be shortened to 10% of the original heat-up time, depending on the pigment concentration, emit ter power and geometry of the plastic (for example wall PP film natural (comparison) heat-up time: 18 sec thickness). PP film comprising 0.1% of absorption pigment heat-up time: 17.5 sec 0037. The plastics according to the invention are further PP film comprising 0.3% of absorption pigment heat-up time: 16 Sec more eminently suitable for the welding of plastic parts by means of IR light. In a similar manner to laser welding, infrared light welding uses a short-wave infrared radiation for 0046. As the measurement values show, the concentration melting of the join area. The radiation source used is usually of 0.1% already has a small measurable influence in this a halogen lamp having a light emission in the range 500-1500 plastic system. Even with 0.3%, however, a significant short nm. The light from the lamp is focused on a focal point by ening of the heat-up time by 2 sec, i.e. about 11%, can be means of an ellipsoidal reflector, enabling a light power of achieved. >3000 W/cm to be achieved with a focal point diameter of about 2 mm. Example 2 0038. The process is suitable both for direct welding of Comparison of Two Pearlescent Films with and parts and also for welding in the transmission process, in which a transparent part is welded to an absorbent part. The without Addition of an IR-Absorbent Pigment use of the pale and transparent absorption pigment in the 0047 Pearlescent films having a thickness of 350 um are polymer matrix has the advantage that the two join partners produced from polypropylene (Sabic PP 575 P) with the can be made the same colour, since it has virtually no effect on following recipe: colours present. 0039. The polymer system pigmented in accordance with a) 99% of Sabic PP 575 P the invention can be used in all areas where thermoplastics (0.048. 1% of Iriodin(R) 123 Bright Lustre Satin pearles have been employed to date. For example, mouldings of the cent pigment from Merck KGaA (a TiO-coated mica plastic according to the invention can be used in the electrical, pigment) electronics and motor vehicle industries. The plastic system according to the invention can also be employed in packaging (films) in the foods sector. Furthermore, the polymer system b) 98% of Sabic PP575 P according to the invention can be used in the area of construc 0049) 1% of Iriodin(R) 123 Bright Lustre Satin pearles tion and architecture, as well as sport and leisure. cent pigment 0040. The invention also relates to the use of the polymers 0050 1% of IR absorption pigment analogous to according to the invention having high NIR absorption in the Example 1 area of thermoforming and in the IR welding of plastic parts. 0051 Film pieces measuring 5 cmx5 cm are cut out of 0041 Further embodiments according to the invention are these films and irradiated using a quartz ceramic emitter revealed by the examples and the claims. having a power of 1000 watts at a distance of 30 cm. The temperature change during the irradiation is recorded and BRIEF DESCRIPTION OF DRAWINGS plotted graphically (FIG. 1). 0042 FIG. 1 shows temperature change during irradia 0052. In both films, a temperature equilibrium becomes tion. established after a certain irradiation time. This is about 13° 0043. The following examples are intended to explain the C. or 20% higher in the case of the film comprising absorber invention, but without limiting it. The percent data indicated than in the comparison without absorber, with the film with are percent by weight. out absorber reaching its equilibrium temperature of about 52°C. after an exposure time of 120s, while this temperature EXAMPLES is reached after only 60s in the case of the film comprising absorber. Example 1 1. Polymer system, characterised in that it comprises, as Comparison of Natural-Coloured, Unpigmented PP absorption pigment, pale or transparent particulate semicon with PP Which is Natural-Coloured, but is Pig ductor materials or particulate Substrates coated with pale or mented with Absorbent Pigment transparent semiconductor materials in order to increase the 0044 Films having a thickness of 350 um are produced thermal conductivity. from polypropylene (Sabic PP 575 P) with pigmenting by 2. Polymer system according to claim 1, characterised in a) 0.1% that the semiconductor materials have a homogeneous struc b) 0.3% ture comprising pale or transparent semiconductor materials of the absorption pigment (an antimony oxide-doped tin diox or are applied as coating to a particulate Substrate. ide having a particle size of about 1 um). 3. Polymer system according to claim 1, characterised in 0045. As comparison, a film without pigmentation is pro that the particulate semiconductor materials and particulate duced. Parts are shaped from these films using athermoform Substrates are spherical, flake-form or needle-shaped materi ing machine from Illig (model KFG 37) with 90% of the als or Substrates. US 2010/O 139855A1 Jun. 10, 2010

4. Polymer system according to claim 1, characterised in 11. Polymer system according to claim 1, characterised in that the semiconductor material has an oxidic or Sulfidic that the polymer is a thermoplastic or thermoelastic plastic. Structure. 12. Polymer system according to claim 1, characterised in 5. Polymer system according to claim 1, characterised in that the polymer is selected from the group polyethylene (PE, that the semiconductor material is built up on the basis of HDPE, LDPE), polypropylene (PP), polyamides, polyesters, indium oxide, antimony oxide, tin oxide, Zinc oxide, Zinc polyester-esters, polyether-esters, polyphenylene ether, poly sulfide, tin sulfide or is a mixture of the said materials. acetals, polyalkylene terephthalate, polymethyl methacrylate 6. Polymer system according to claim 1, characterised in (PMMA), polyvinylacetals, polyvinyl chloride (PVC), that the mixture is indium tin oxide (ITO). polyphenylene oxide (PPO), polyoxymethylene (POM), 7. Polymer system according to claim 1, characterised in polystyrene (PS), acrylonitrile-butadiene-styrene (ABS), that the substrate is selected from the group of the mica flakes acrylonitrile-styrene-acrylate (ASA), acrylonitrile-butadi (synthetic or natural), SiO flakes, Al2O flakes, glass flakes, ene-styrene (ABS), polycarbonates (PC), polyether sulfones, aluminium flakes, BiOCl flakes, SiO, beads, silica gel, kie polyurethanes (TPU) and polyether ether ketones (PEEK), Selguhr, glass beads, hollow glass beads, TiO beads, polymer and copolymers and/or mixtures thereof. beads, TiO, needles or mixtures thereof. 13. Process for the preparation of the polymer system 8. Polymer system according to claim 1, characterised in according to claim 1, characterised in that a suitable mixer is that the semiconductor materials are doped. charged with the plastic granules, the latter are wetted with 9. Polymer system according to claim 1, characterised in any additives, and the absorption pigment, optionally with that the semiconductor material has an amorphous, crystal further additives, is then mixed in. line or microcrystalline structure. 14. A method of thermoforming or IR welding of plastic 10. Polymer system according to claim 1, characterised in parts comprising using a polymer system of claim 1. that the absorption pigment is present in amounts of 0.1-30% by weight, based on the polymer system. c c c c c