3,749,769 United States Patent Office Patented July 31, 1973 2 good properties such as water-proofness, adhesiveness 3,749,769 and luster to nitrocellulose lacquers. NAIL LACQUER COMPOSITIONS AND PROCESS FOR THE PREPARATION THEREOF DETALED DESCRIPTION Iwakichi Sugiyama, Narashino, and Haruki Tomozuka, The oligomers and co-oligomers of acrylic esters used Tokyo, Japan, assignors to Matsumoto Chemical indus try Co., Ltd., Ichikawa-shi, Chiba-ken, Japan in the invention can be prepared by polymerizing acrylic No Drawing. Continuation of abandoned application Ser. ester monomers in the medium of a great quantity of the No. 753,745, Aug. 19, 1968. This application Jan. 22, solvent having a relatively large chain-transfer constant. 1971, Ser. No. 108,971 Such solvents, include, for instance, methyl isobutyl Claims priority, application Japan, Feb. 1, 1968, O ketone, methyl ethyl ketone, isobutyl alcohol, isopropyl 43/5,832 alcohol, sec, butyl alcohol, and toluene. These solvents int, C. A61k 7/04 are used in amounts of 4-20 moles, preferably 6-15 U.S. C. 424-6 5 Clains moles, per mole of the acrylic ester monomers. As mentioned above, the oligomers or co-oligomers ABSTRACT OF THE DISCLOSURE 5 used in the invention can be synthesized with the use of A nail lacquer having a good water-proofness, ad generally known solvents having a large chain-transfer hesiveness and luster is obtained by polymerizing acrylic constant. But it is necessary to make the molar ratio of monomers in a solvent having a relatively large chain solvent to monomer considerably large, and yet the yield transfer constant to form oligomers or co-oligomers, of the intended oligomer is very low. This is a serious 20 problem in the commercial practice of the process. and blending the obtained oligomers or co-oligomers The present invention also includes a process wherein with a nitrocellulose lacquer in the amount of 30-65% the above problem is solved by using lactic ester as the based on the solid content of the nitrocellulose lacquer. solvent having a large chain-transfer constant. Useful solvents having a large chain-transfer constant This application is a continuation application of Ser. 25 to be used in the invention are lactic acid esters of the No. 753,745, Aug. 19, 1968, now abandoned. alcohols having an alkyl or cycloalkyl group, such as methyl lactate, ethyl lactate, propyl lactate and butyl BACKGROUND OF THE INVENTION lactate. The alkyl or cycloalkyl group may, substantially, This invention relates to a nail lacquer having a good have more than 6 carbon atoms, but should preferably water-proofness, adhesiveness and luster. have not more than 6 carbon atoms in view of the recov Generally, nail lacquers are prepared from nitrocellu ery of solvents. lose, natural or synthetic resins and liquid plasticizers. Such a lactic ester is used in an amount of 0.5-8 moles, Because the nitrocellulose has a high glass transition point preferably 1.0–4.0 moles, per mole of the acrylic ester and cannot by itself form a tough film, it is necessary monomer to obtain the desired oligomer or co-oligomer. to plasticize it with a plasticizer. Nitrocellulose and a 35 The acrylic ester monomers of the invention are ex liquid plasticizer give a tough film to a certain extent, pressed by the following formula: but such film does not prove to be satisfactory in respect X X of luster, beautiful appearance and brush coating prop f (i.Y erties. CH2=C-COO-)-CHCH---YV An To remedy these defects, attempts are being made to 40 incorporate therein natural and synthetic resins. Natural wherein each of X and X represents a hydrogen atom resins had been preferably used for this purpose up or a methyl group; n is 0 or 1; when n is O, Y represents to several years ago. Since then, many synthetic resins an alkyl of 1-10 carbon atoms, benzyl or cycloalkyl of were prepared, and it is these synthetic resins that are up to 10 carbon atoms; when n is 1, Y represents OR, blended with ordinary nitrocellulose lacquers. It is im 45 possible however to incorporate into a nail lacquer a resin such as used generally in the paint industry, because most of synthetic resins that will give desirable properties when blended with nitrocellulose are either formalin type or a hydroxyl group, where R is an alkyl or cycloalkyl resins or resins undesirable for nail lacquers. These resins 50 group having not more than 10 carbon atoms, and R2 connot be used for nail lacquers. and R3 may be the same or different, and each represents Synthetic resins most generally used now in the art an alkyl group having not more than 4 carbon atoms. are alkylbenzenesulfonic acid amide/formalin resins. It The acrylic ester can be used also in the form of a mix is said that these resins hardly liberate formalin, but it ture containing at least 2 mole percent of an acid expressed is doubtful if they will not liberate it at all. Furthermore, 55 by the above formula wherein n is O and Y is a hydrogen these resins must be used together with liquid plasticizers. atom. The above acrylic ester monomers may be used However, liquid plasticizers generally deteriorate the either alone or in mixtures with each other. (However, water-proofness of nail lacquers, and weaken the adhesive methacrylic esters should always be used together with power by moving to a surface to which the lacquer ad 60 Ef esters, in an amount not exceeding 30 mole per heres. These defects are the causes of exfoliation of a nail Ceit. enamel from nails, reduction in luster, and therefore a Specific examples of such monomers are alkyl acrylates considerable deterioration in beauty. Such as n-butyl acrylate, cycloalkyl acrylates, benzyl acry With these problems in mind, the invention provides late, alkyl methacrylates, benzyl methacrylate, alkylcello new nail lacquer compositions and a process for their Solve acrylates, propylene glycol monoalkylether acrylates, preparation, which comprises blending, with nitrocellu 65 alkylcelloSolve methacrylates, and propylene glycol mono lose lacquers. oligomers or co-oligomers of acrylic esters alkyl ether methacrylates. which act concurrently as a resin and a plasticizer, with The polymerization reaction can be carried out at 60 out any positive necessity of such liquid plasticizers. Such 180 C. in a stream of nitrogen gas with the use of an oligomers and co-oligomers are low-molecular-weight ordinary polymerization vessel provided with a stirrer, a polymers which never separate formalin, nor cause a 70 reflux column, a thermometer, a monomer dropping problem in respect of toxicity. Moreover, they impart device and a nitrogen gas introducing tube. Preferably, 8,749,769 3 4. the reaction temperature should be between the boiling and was negative against Tollens reagent. Fifty to sixty point of the used solvent and a point slightly lower than parts of this resin were blended with 50 parts of nitro it. The reaction is initiated by a polymerization initiator. cellulose. Ordinary initiators which are in the general use can be Example 3 employed, but especally preferred are the initiators of dialkyl type such as di-tertiary butyl peroxide and the 5 The same reaction apparatus as used in Example 1 was initiators of perester type such as tertiary-butyl perace charged with 49.1 parts of ethyl lactate and part of tate which have a high proton-accepting power. It is be di-tertiary butyl peroxide (97%). While the temperature cause of a high hydrogen abstracting ability and difficulty was being maintained at 140-150° C., 57.5 parts of of subjecting to induced decomposition that these initiators O n-butyl acrylate was added dropwise in a stream of nitro are preferred. The amount of the initiator may be at least gen over a period of 3 hours, and the reaction was con 0.1% based on the monomer, but usually an amount of tinued for further 5 hours at the same temperature. In about 1% is sufficient, the same manner as in Example 1, a 75% toluene solution An oligomer or co-oligomer synthesized in this manner of the reaction product was prepared. This resin Solution is, after the end of the reaction, incorporated into a nail exhibited a viscosity of about 100 centistokes at 25 C., lacquer, unless there are inconveniences. "No inconven and was negative against Tollens reagent. Fifty to sixty ience expressed here means that the resulting nail lacquer parts of this resin were blended with 50 parts of nitro contains only negligible amounts of unreacted monomer cellulose. having toxicity and residual peroxide which is detrimental Example 4 to the stability of the lacquer, and the solvent used in the The same reaction apparatus as used in Example 1 was reaction does not cause any inconvenience even when charged with 68 parts of ethyl lactate, 19.6 parts of n-butyl present in the nail lacquer. In general, however, Such a acrylate and 1 part of di-tertiary butyl peroxide. While the suitable means as a distillation under reduced pressure, temperature was being maintained at 140-150° C., a mix distillation under normal atmospheric pressure or aZeo ture of 38.0 parts of n-butyl acrylate, 50 parts of ethyl tropic distillation is employed to recover the Solvent used lactate and 7.21 parts of 2-butoxyethyl acrylate was added in the reaction and remove the unreacted monomer and dropwise in a stream of nitrogen over a period of 3 hours, residual initiator to a concentration such as will not cause and the reaction was continued for further 5 hours at the troubles, and the lacquer is diluted with other Suitable same temperature.