WO2020149396A1

WO2020149396A1 - Latex for foam rubber and foam rubber

Info

Publication number: WO2020149396A1
Application number: PCT/JP2020/001442
Authority: WO
Inventors: 淑乃河口; 昂浜田; 成相廣瀬; 友哉谷山; 伊賀　隆志
Original assignee: 第一工業製薬株式会社; 日本ゼオン株式会社
Priority date: 2019-01-18
Filing date: 2020-01-17
Publication date: 2020-07-23
Also published as: JPWO2020149396A1; JP7381499B2

Abstract

Provided is a latex for foam rubber containing a nitrile group-containing conjugated diene copolymer, a urethane polymer, and a nonionic surfactant, wherein the urethane polymer is anionic and the content of the nonionic surfactant is 0.5-10 wt% relative to the urethane polymer.

Description

Latex for foam rubber and foam rubber

The present invention relates to a latex for foam rubber and foam rubber used for manufacturing foam rubber.

Rubber foams (foam rubbers) manufactured using polymer latex are used for various purposes as mattresses, puffs (cosmetic sponges), rolls, shock absorbers, etc. Among such uses of the rubber foam, in particular, the rubber foam used for the puff has a good foaming state, has a uniform foaming structure, and has an excellent balance of elasticity and texture. It has been demanded.

For example, in Patent Document 1, a composition containing a water-soluble NBR (nitrile-butadiene-rubber) emulsion, a water-soluble urethane emulsion, a cross-linking agent, a surfactant and a gelling agent is mixed with air to be foamed by stirring. Then, a method for producing a puff base material having a predetermined shape by heat vulcanization, wherein the solid content concentration of the water-soluble NBR emulsion is 60% by weight or more, and the blending ratio of the water-soluble urethane emulsion is in terms of solid content. Thus, a method for producing a cosmetic puff base material having high physical properties, which comprises 5 to 15% by weight of the total solid content of both emulsions, is disclosed.

Japanese Patent Publication No. 8-5988

However, there is a demand for a technology that can produce foam rubber that is even more moldable and that does not easily deform even when it contains an ultraviolet absorber contained in cosmetics.

The present invention has been made in view of such circumstances, and provides a latex for foam rubber, which is excellent in moldability and is capable of producing a foam rubber that is not easily deformed even when an ultraviolet absorber is included. The purpose is to do.

The present inventors, as a result of intensive research to achieve the above object, in a latex containing a nitrile group-containing conjugated diene copolymer and a urethane polymer, using a nonionic surfactant, As the urethane polymer, an anionic one is used, and further, it is found that the above object can be achieved by appropriately adjusting the content ratio of the urethane polymer and the nonionic surfactant, and the present invention is completed. Came to.

That is, according to the present invention, a latex for foam rubber containing a nitrile group-containing conjugated diene-based copolymer, a urethane polymer and a nonionic surfactant, wherein the urethane polymer is anionic, Provided is a latex for foam rubber, wherein the content of the nonionic surfactant is 0.5 to 10% by weight based on the urethane polymer.

In the latex for foam rubber of the present invention, the content ratio of the nitrile group-containing conjugated diene copolymer and the urethane polymer is 50: in a weight ratio of the nitrile group-containing conjugated diene copolymer: urethane polymer. It is preferably 50 to 95:5.
The latex for foam rubber of the present invention preferably has a solid content concentration of 60% by weight or more.
The latex for foam rubber of the present invention preferably has a viscosity of 100 to 900 mPa·s measured with a B-type viscometer at a rotation speed of 60 rpm.

According to the present invention, there is also provided a foam rubber obtained by using the above latex for foam rubber.

According to the present invention, it is possible to provide a latex for foam rubber which is excellent in moldability and can be manufactured into a foam rubber that is hard to be deformed even when a cosmetic is included.

<Latex for foam rubber>
The latex for foam rubber of the present invention contains a nitrile group-containing conjugated diene-based copolymer, a urethane polymer and a nonionic surfactant.

Nitrile group-containing conjugated diene-based copolymer Nitrile group-containing conjugated diene-based copolymer is a copolymer obtained by copolymerizing a conjugated diene monomer and an ethylenically unsaturated nitrile monomer, In addition, it may be a copolymer obtained by copolymerizing another ethylenically unsaturated monomer copolymerizable therewith, which is used as necessary.

The ethylenically unsaturated nitrile monomer is not particularly limited as long as it is a nitrile group-containing ethylenically unsaturated monomer, and examples thereof include acrylonitrile, methacrylonitrile, fumaronitrile, α-chloroacrylonitrile, α-cyanoethylacrylonitrile. And so on. Of these, acrylonitrile and methacrylonitrile are preferable, and acrylonitrile is more preferable. These ethylenically unsaturated nitrile monomers may be used alone or in combination of two or more.

The content ratio of the ethylenically unsaturated nitrile monomer unit formed by the ethylenically unsaturated nitrile monomer in the nitrile group-containing conjugated diene copolymer is preferably 5 to 80% by weight, more preferably Is 15 to 70% by weight, more preferably 20 to 60% by weight, and particularly preferably 31 to 60% by weight. By setting the content ratio of the ethylenically unsaturated nitrile monomer unit within the above range, a latex for foam rubber having more excellent moldability can be obtained, and the foam rubber is less likely to be deformed even when it contains an ultraviolet absorber. Can be manufactured.

Examples of the conjugated diene monomer include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,3-pentadiene and chloroprene. To be Of these, 1,3-butadiene and isoprene are preferable. These conjugated diene monomers can be used alone or in combination of two or more.

The content ratio of the conjugated diene monomer unit formed by the conjugated diene monomer in the nitrile group-containing conjugated diene copolymer is preferably 20 to 95% by weight, more preferably 30 to 85% by weight. %, more preferably 40 to 80% by weight, particularly preferably 40 to 69% by weight. By setting the content ratio of the conjugated diene monomer unit in the above range, a latex for foam rubber having more excellent moldability can be obtained, and a foam rubber that is more resistant to deformation even when an ultraviolet absorber is contained is produced. be able to.

Further, from the viewpoint that a foam rubber latex having further excellent moldability can be obtained and a foam rubber that is less likely to be deformed even when an ultraviolet absorber is contained, 1,3-butadiene and isoprene can be produced. Both are preferably used, and the ratio of the 1,3-butadiene unit and the isoprene unit in the nitrile group-containing conjugated diene-based copolymer is 5/5 to 9 in terms of the ratio of 1,3-butadiene unit/isoprene unit. It is preferably in the range of /1.

Other ethylenically unsaturated monomers copolymerizable with the conjugated diene monomer and the ethylenically unsaturated nitrile monomer include, for example, (meth)acrylic acid, (anhydrous) maleic acid, fumaric acid, itaconic acid. Ethylenically unsaturated carboxylic acid such as; methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, maleic acid mono- or dimethyl, fumaric acid mono Or mono- or di-alkyl ester of ethylenically unsaturated carboxylic acid such as diethyl, mono- or di-n-butyl fumarate, mono- or di-n-butyl itaconic acid; ethylenic such as methoxy acrylate, ethoxy acrylate, methoxy ethoxy ethyl acrylate Alkoxyalkyl ester of unsaturated carboxylic acid; (meth)acrylate having hydroxyalkyl group such as 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate; glycidyl (meth)acrylate; (Meth)acrylic acid amides such as (meth)acrylamide, N-methylol (meth)acrylamide, N-butoxymethyl (meth)acrylamide and derivatives thereof; acrylates having an amino group such as dimethylaminomethyl acrylate and diethylaminomethyl acrylate; styrene; Aromatic vinyl monomers such as α-methylstyrene, vinyltoluene and chlorostyrene; α-olefins such as ethylene and propylene; non-conjugated diene monomers such as dicyclopentadiene and vinylnorbornene. These monomers can be used alone or in combination of two or more kinds. The content ratio of the other monomer unit formed of the other ethylenically unsaturated monomer in the nitrile group-containing conjugated diene copolymer is preferably 40% by weight or less, more preferably 30% by weight. % Or less, more preferably 20% by weight or less. By setting the content ratio of the other monomer units in the above range, a foam rubber latex having further excellent moldability can be obtained, and a foam rubber which is more resistant to deformation even when an ultraviolet absorber is contained is produced. be able to.

Urethane Polymer The urethane polymer is a polymer having a urethane bond, and those contained in the latex of the urethane polymer can be used. The latex for foam rubber of the present invention contains an anionic urethane polymer. By using the anionic urethane polymer, a latex for foam rubber having excellent moldability can be obtained, and a foam rubber that is hard to be deformed even when an ultraviolet absorber is contained can be manufactured.

As the anionic urethane polymer, a urethane polymer having an anionic group is preferable. The latex of the urethane polymer is not particularly limited, but for example, an active hydrogen-containing compound, a compound having an anionic group, and an organic solvent solution of a urethane resin having an anionic group obtained by reacting a polyisocyanate or A latex obtained by mixing an organic solvent dispersion with an aqueous solution containing a neutralizing agent and removing the organic solvent as needed is mentioned. Alternatively, as the latex of the urethane polymer, an active hydrogen-containing compound, a compound having an anionic group, and a terminal isocyanate group-containing urethane prepolymer having an anionic group obtained by reacting a polyisocyanate, It may be a latex obtained by mixing an aqueous solution containing a neutralizing agent and a polyamine and reacting the polyamine.

The active hydrogen-containing compound is not particularly limited, and examples thereof include polyester polyols, polyether polyols, polycarbonate polyols, polyacetal polyols, polyacrylate polyols, polyester amide polyols, polythioether polyols, polyols such as polybutadiene-based polyolefin polyols; polyesters. Polyhydroxy compounds such as glycol compounds, glycerin, trimethylolethane, trimethylolpropane, sorbitol and pentaerythritol used as raw materials for polyols; ethylenediamine, 1,6-hexamethylenediamine, piperazine, 2,5-dimethylpiperazine, isophoronediamine Amine such as 4,4′-dicyclohexylmethanediamine, 3,3′-dimethyl-4,4′-dicyclohexylmethanediamine, 1,4-cyclohexanediamine, 1,2-propanediamine, hydrazine, diethylenetriamine, triethylenetetramine A compound etc. are mentioned.

The compound having an anionic group is not particularly limited, but, for example, has at least one active hydrogen atom in the molecule and has a carboxylate group, a sulfonate group, a phosphate group, a quaternary ammonium salt group, a carboxylic acid group. Examples thereof include compounds having an anionic group containing at least one functional group selected from the group consisting of acid groups, sulfonic acid groups, phosphoric acid groups, and tertiary amino groups. As the compound having an anionic group, among others, a compound having at least one active hydrogen group and at least one carboxyl group (or salt thereof) or at least one active hydrogen group and at least one sulfonic acid group (or salt thereof). Compounds having are preferred.

The compound having at least one active hydrogen group and at least one carboxyl group (or salt thereof) is not particularly limited, and examples thereof include 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, and 2,2-dimethylolamine. In addition to carboxylic acid-containing compounds such as herbic acid, dioxymaleic acid, 2,6-dioxybenzoic acid and 3,4-diaminobenzoic acid, their derivatives and salts thereof, and polyester polyols obtained by using them To be Further, amino acids such as alanine, aminobutyric acid, aminocaproic acid, glycine, glutamic acid, aspartic acid and histidine, and carboxylic acids such as succinic acid, adipic acid, maleic anhydride, phthalic acid and trimellitic anhydride are also included.

Examples of the compound having one or more active hydrogen groups and one or more sulfonic acid groups (or salts thereof) include 2-oxyethanesulfonic acid, phenolsulfonic acid, sulfobenzoic acid, sulfosuccinic acid, 5-sulfoisophthalic acid, sulfanilic acid. 1,3-phenylenediamine-4,6-disulfonic acid, 2,4-diaminotoluene-5-sulfonic acid and other sulfonic acid-containing compounds and derivatives thereof, and polyester polyols and polyamides obtained by copolymerizing these compounds Examples thereof include polyols and polyamide polyester polyols.

By neutralizing these carboxyl groups or sulfonic acid groups to form a salt, the finally obtained polyurethane can be made water-dispersible. Examples of the neutralizing agent in this case include non-volatile bases such as sodium hydroxide and potassium hydroxide, tertiary amines such as trimethylamine, triethylamine, dimethylethanolamine, methyldiethanolamine and triethanolamine, and volatility of ammonia and the like. A base etc. are mentioned. Neutralization can be performed before the urethanization reaction, during the reaction, or after the reaction.

The polyisocyanate is not particularly limited, and examples thereof include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4′. -Diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenylene diisocyanate, 3,3'-dichloro-4 ,4'-biphenylene diisocyanate, 1,5-naphthalene diisocyanate, 1,5-tetrahydronaphthalene diisocyanate, tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethylhexamethylene diisocyanate, 1,3-cyclohexylene diisocyanate , 1,4-cyclohexylene diisocyanate, xylylene diisocyanate, tetramethyl xylylene diisocyanate, hydrogenated xylylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, 3,3′-dimethyl-4,4 Examples thereof include'-dicyclohexylmethane diisocyanate.

With the urethane polymer, a latex for foam rubber that is more excellent in moldability can be obtained, and a foam rubber that is less likely to be deformed even when an ultraviolet absorber is contained can be produced. Therefore, (A) polyisocyanate, ( A hydrophilic group-containing polyurethane comprising (D) a chain extender in addition to (B) an active hydrogen-containing compound and (C) a compound having one or more active hydrogen groups and one or more anionic groups. Is also preferable. The chain extender (D) is not particularly limited, and examples thereof include diamines and polyamines, and since it is possible to produce a foam rubber that is more resistant to deformation even when it contains an ultraviolet absorber, it is trifunctional or higher functional. It is preferable to contain the polyamine. Examples of the diamine include ethylenediamine, trimethylenediamine, piperazine and isophoronediamine. Examples of polyamines include diethylenetriamine, dipropylenetriamine, and triethylenetetramine.

Nonionic Surfactant The latex for foam rubber of the present invention contains a nonionic surfactant. As the nonionic surfactant, those contained in the latex of the urethane polymer can be used. Examples of the nonionic surfactant include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylamine ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters and the like. To be Among them, polyoxyethylene alkylphenyl ethers and/or sorbitan fatty acid ester are preferable.

The HLB of the nonionic surfactant is preferably in the range of 4 to 20, more preferably in the range of 10 to 20.

In the latex for foam rubber of the present invention, the content of the nonionic surfactant is 0.5 to 10% by weight, preferably 0.5 to 8% by weight, based on the urethane polymer. It is preferably 0.5 to 7% by weight. By setting the content of the nonionic surfactant in the above range, a latex for foam rubber having excellent moldability can be obtained, and a foam rubber that is difficult to deform even when an ultraviolet absorber is contained can be produced. ..

In the latex for foam rubber, the content ratio of the nitrile group-containing conjugated diene copolymer and the urethane polymer is from 50:50 by weight ratio of (nitrile group-containing conjugated diene copolymer: urethane polymer). The ratio is preferably 95:5, more preferably 60:40 to 90:10, and further preferably 70:30 to 85:15. By setting the content ratio within the above range, a latex for foam rubber that is more excellent in moldability can be obtained, and a foam rubber that is more resistant to deformation even when it contains an ultraviolet absorber can be manufactured.

The solid content concentration of the latex for foam rubber (the total content ratio of the nitrile group-containing conjugated diene copolymer and the urethane polymer) is preferably 60% by weight or more, more preferably 62 to 70% by weight. By setting the solid content concentration within the above range, a latex for foam rubber having further excellent moldability can be obtained, and a foam rubber that is more resistant to deformation even when an ultraviolet absorber is contained can be produced. The method for controlling the solid content concentration of the foam rubber latex within the above range is not particularly limited, and examples thereof include a method of subjecting the foam rubber latex to a concentration treatment so that the latex has a desired solid content concentration. ..

The viscosity of the foam rubber latex is preferably 100 to 900 mPa·s, more preferably 100 to 800 mPa·s. By setting the viscosity within the above range, a latex for foam rubber having further excellent moldability can be obtained, and a foam rubber that is more resistant to deformation even when an ultraviolet absorber is contained can be manufactured. The viscosity of the latex for foam rubber is measured at a rotation speed of 60 rpm using a B-type viscometer.

The latex for foam rubber can be produced, for example, by blending a latex of a nitrile group-containing conjugated diene copolymer, a latex of a urethane polymer, and a nonionic surfactant. As the nonionic surfactant, the nonionic surfactant contained in the latex of the nitrile group-containing conjugated diene copolymer or the latex of the urethane polymer may be used.

The solid content concentration of the latex of the nitrile group-containing conjugated diene copolymer used for preparing the latex for foam rubber is preferably 40 to 72% by weight, more preferably 60 to 70% by weight.

The solid content concentration (nonvolatile content concentration) of the urethane polymer latex used for preparing the latex for foam rubber is preferably 35 to 65% by weight, more preferably 40 to 55% by weight.

As the foam rubber latex, it is preferable to use a compounded compounding agent such as a crosslinking agent. That is, it is preferably used as a latex composition for foam rubber.

As the cross-linking agent, for example, sulfur powder, sulfur flower, precipitated sulfur, colloidal sulfur, surface-treated sulfur, sulfur such as insoluble sulfur; sulfur chloride, sulfur dichloride, morpholine disulfide, alkylphenol disulfide, N,N'-dithio. Examples thereof include sulfur-containing compounds such as -bis(hexahydro-2H-azepinone-2), phosphorus-containing polysulfide, polymeric polysulfide, and 2-(4'-morpholino dithio)benzothiazole. Among these, sulfur can be preferably used. The crosslinking agent may be used alone or in combination of two or more.

The content of the cross-linking agent is not particularly limited, but is preferably 0.1 to 10 parts by weight, more preferably 0.2 parts by weight with respect to 100 parts by weight of the nitrile group-containing conjugated diene copolymer in the latex for foam rubber. ~3 parts by weight. By setting the content of the cross-linking agent within the above range, the strength of the obtained foam rubber can be further increased.

The latex for foam rubber preferably further contains a crosslinking accelerator.
As the crosslinking accelerator, those usually used in the production of foam rubber can be used, and examples thereof include diethyldithiocarbamic acid, dibutyldithiocarbamic acid, di-2-ethylhexyldithiocarbamic acid, dicyclohexyldithiocarbamic acid, diphenyldithiocarbamic acid, dibenzyldithiocarbamic acid and the like. Dithiocarbamic acids and zinc salts thereof; 2-mercaptobenzothiazole, 2-mercaptobenzothiazole zinc, 2-mercaptothiazoline, dibenzothiazyl disulfide, 2-(2,4-dinitrophenylthio)benzothiazole, 2-( N,N-diethylthiocarbaylthio)benzothiazole, 2-(2,6-dimethyl-4-morpholinothio)benzothiazole, 2-(4'-morpholinodithio)benzothiazole, 4-morphonylyl-2-benzothiazyl disulfide , 1,3-bis(2-benzothiazyl.mercaptomethyl)urea, and the like, and zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate, and zinc 2-mercaptobenzothiazole are preferable. The crosslinking accelerator may be used alone or in combination of two or more.

The content of the crosslinking accelerator is preferably 0.1 to 5 parts by weight, more preferably 0.2 to 4 parts by weight based on 100 parts by weight of the nitrile group-containing conjugated diene copolymer in the latex for foam rubber. Parts by weight. By setting the content of the crosslinking accelerator within the above range, the strength of the foam rubber obtained can be further increased.

Furthermore, the foam rubber latex preferably contains zinc oxide.
The content of zinc oxide is not particularly limited, but is preferably 0.5 to 10 parts by weight, more preferably 0.5 to 100 parts by weight with respect to 100 parts by weight of the nitrile group-containing conjugated diene copolymer in the latex for foam rubber. ~8 parts by weight. By setting the content of zinc oxide within the above range, the strength of the foam rubber obtained can be further increased.

The latex for foam rubber further includes a dispersant (for example, NASF (naphthalenesulfonic acid formalin condensate) for stably dispersing the above-mentioned various compounding agents in the latex, such as an anti-aging agent, a colorant, and a foam stabilizer. Sodium salt), a thickener (for example, polyacrylic acid and its sodium salt, sodium alginate, polyvinyl alcohol, etc.), and a surfactant as a foaming agent (for example, an aliphatic alkali soap such as potassium oleate), Sulfate salts of higher alcohols such as sodium dodecyl sulfate) can be added if necessary.

The method for mixing various compounding agents into the foam rubber latex is not particularly limited, and for example, after obtaining the foam rubber latex as described above, using a dispersing machine such as a ball mill, a kneader, or a disperser, foam A method for mixing various compounding agents to be added to the rubber latex as needed, or an aqueous dispersion of compounding ingredients other than the foam rubber latex is prepared using the above-mentioned disperser, and then the aqueous dispersion is prepared. And a method of mixing with a latex for foam rubber.

<foam rubber>
A foam rubber can be obtained by foaming and coagulating the above-mentioned latex for foam rubber at a desired expansion ratio. Air is usually used for foaming, but carbonates such as ammonium carbonate and sodium bicarbonate; azo compounds such as azodicarboxylic acid amide and azobisisobutyronitrile; gas generating substances such as benzenesulfonyl hydrazide can also be used. When air is used, the latex for foam rubber can be agitated and bubbled by incorporating air. At this time, for example, an Oaks foaming machine, an ultrasonic foaming machine or the like can be used.

After foaming the foam rubber latex, in order to fix the foamed state, the foamed foam rubber latex is solidified. Any coagulation method may be used as long as it can gelate and solidify the latex, and conventionally known methods can be used. For example, sodium hexafluorosilicate (sodium fluorosilicate), potassium hexafluorosilicate (silica) can be used. Dunlop method (cold coagulation method) of adding a room temperature coagulating agent such as a potassium fluoride) or a silicon fluoride compound such as titanium silicofluoride to the foamed latex for foam rubber; organopolysiloxane, polyvinyl methyl ether, sulfuric acid A heat-sensitive coagulation method in which a heat-sensitive coagulant such as a zinc ammonium complex salt is added to the foamed latex for foam rubber; a freeze coagulation method or the like is used. The amount of the coagulant such as the room temperature coagulant or the heat-sensitive coagulant is not particularly limited, but preferably 0.5 to 10 per 100 parts by weight of the nitrile group-containing conjugated diene copolymer in the latex for foam rubber. By weight, more preferably 0.5 to 8 parts by weight.

Then, the foam rubber can be obtained by adding a coagulant to the foamed latex for foam rubber, transferring it to a mold having a desired shape, and coagulating it. When a cross-linking agent is added to the foam rubber latex, it is preferable that the latex is cross-linked by heating after coagulation. The conditions for the cross-linking can be a temperature of 100 to 160° C., and preferably a heat treatment of 15 to 120 minutes.

It is preferable to wash the obtained foam rubber after removing it from the mold. The washing method is not particularly limited, and examples thereof include a method of washing with a washing machine or the like by stirring with water at about 20 to 70° C. for about 5 to 15 minutes. After washing, it is preferable to drain water and dry at a temperature of about 30 to 90° C. so as not to impair the texture of the foam rubber. The foam rubber thus obtained can be used as a puff (cosmetic sponge) by, for example, slicing it into a predetermined thickness, cutting it into a predetermined shape, and polishing the side surface with a rotary grindstone or the like. it can.

The foam rubber obtained by using the latex for foam rubber of the present invention can be suitably used for various applications such as mattresses, puffs (cosmetic sponges), rolls and shock absorbers. In particular, the foam rubber obtained using the latex for foam rubber of the present invention does not easily deform even when it contains a UV absorber such as octyl paramethoxycinnamate (ethylhexyl methoxycinnamate). It can be suitably used as a puff (sponge for cosmetics) impregnated with a composition containing the.

The present invention will be specifically described below with reference to examples and comparative examples. In the following, "part" is based on weight unless otherwise specified. The tests and evaluations were as follows.

Nonvolatile matter The weight of the nonvolatile matter in the latex of the urethane polymer was measured according to JIS K6828.
Measurement method of nonionic surfactant and preparation of calibration curve Measured by dissolving a predetermined amount of polyoxyethylene lauryl ether (DKS NL-70) in 5 ml of solvent (5 mM ammonium formate aqueous solution/acetonitrile=40/60 mass ratio) As a sample, the measurement sample was measured using GPC (gel permeation chromatography) under the following conditions to prepare a calibration curve.
<Measurement conditions>
Column: Asahipak GF-310HQ 4.6x300m
Mobile phase: 5 mM ammonium formate/acetonitrile=40/60 mass ratio flow rate: 0.5 ml/min
Detector: RI
-Measurement of Content 1.5 g of the latex composition produced in each of the Examples and Comparative Examples was measured and lyophilized at -80°C and -100 mbar for 5 hours. Soxhlet extraction was performed on all the obtained dried components with methanol, and the extract was vacuum dried at room temperature to obtain extracted components. The obtained extract was dissolved in 5 ml of a solvent (5 mM ammonium formate aqueous solution/acetonitrile=40/60 mass ratio) to give a measurement sample. The measurement sample was measured using GPC (gel permeation chromatography) under the above conditions, and the content was determined based on a calibration curve.

Solid content concentration The solid content concentration of the latex and the latex mixture of the nitrile group-containing conjugated diene copolymer was calculated by the following method. A sample (2 g) was precisely weighed (weight: X2) in an aluminum dish (weight: X1) and dried in a hot air dryer at 105°C for 2 hours. Then, after cooling in a desiccator, the weight of each aluminum dish was measured (weight: X3), and the solid content concentration was calculated according to the following calculation formula.
Solid content concentration (% by weight)=(X3-X1)×100/X2

Viscosity The viscosity of the latex mixture was measured using a viscometer (BII viscometer (model name: BLII), manufactured by Toki Sangyo Co., Ltd.) at a rotation speed of 60 rpm and a temperature of 25°C.

Foamability With respect to the latex compositions prepared in Examples and Comparative Examples, the time required for foaming to 5 times in volume was measured and evaluated according to the following criteria.
Excellent: within 2 minutes Good: over 2 minutes Poor: Could not foam 5 times.

The state from the pouring of the gelled foam to the molding frame to the gelation was observed and evaluated according to the following criteria.
Excellent: The bubbles were stably maintained.
Poor: Foaming was observed.

The foam rubber before shrinkage cutting was observed, the area of the portion that contracted in the height direction was calculated, and evaluated according to the following criteria.
Excellent: The area of the portion contracted in the height direction was 10% or less of the entire area.
Good: The area of the portion contracted in the height direction was more than 10% and 90% or less of the entire area.
Poor: The area of the portion contracted in the height direction was more than 90% of the total area.

Comprehensive Evaluation Based on the evaluation results of foaming property, gelled state and shrinkage, evaluation was made according to the following criteria.
A: All three evaluation results were “excellent”.
B: One of the evaluation results was “good” but not “bad”.
C: One of the evaluation results was “poor”.

The ultraviolet absorbent-resistant foam rubber was immersed in octyl paramethoxycinnamate for 3 days at 23° C., and the ratio of the volume of foam rubber after immersion to the volume of foam rubber before immersion (swelling ratio (%)=( The volume of foam rubber after immersion)/(volume of foam rubber before immersion)×100) was calculated and evaluated according to the following criteria.
Excellent: The swelling rate was 135% or less.
Poor: The swelling ratio was more than 135%.

<Preparation of latex for foam rubber>
Example 1
Urethane polymer latex (trade name "F-2968D", manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., contains anionic urethane polymer, content of nonionic surfactant is 2% by weight based on weight of urethane polymer) ) And a latex of a nitrile group-containing conjugated diene copolymer (trade name "LX531B", manufactured by Nippon Zeon Co., Ltd.), the solid content weight ratio of "urethane polymer: nitrile group-containing conjugated diene copolymer" is , 20:80 to obtain a latex mixture. The solid content concentration and the viscosity of the obtained latex mixture were measured according to the methods described above. The results are shown in Table 1.

A vulcanization type aqueous dispersion (colloidal sulfur/dithiocarbamate type vulcanization accelerator NOXCELLER EZ (manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.) was added to the latex mixture obtained as described above, based on 100 parts of the polymer in the latex mixture. /Thiazol-based vulcanization accelerator Nocceller MZ (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) = 2/1/1 (weight ratio), solid content concentration 50% by weight, 4 parts, zinc oxide aqueous dispersion (solid content concentration 50 weight% %) 3 parts and a bubble stabilizer (Trimen base: manufactured by Crompton Corp.) 1 part, and sufficiently dispersed to obtain a latex composition.

The latex composition was stirred using a stand mixer (model “ESM945”, manufactured by Electrolux) and foamed to have a volume five times that of the aqueous dispersion of sodium silicate (solid content 20% by weight). ) 1.5 parts was added and the mixture was further stirred for 1 minute to obtain a foam.

Next, the obtained foam is poured into a mold for molding (15 cm in length×25 cm in width×1 cm in height), solidified, and then vulcanized by heating at 110° C. for 1 hour, and then taken out from the mold. It was washed with water of 40° C. for 10 minutes, dried in an oven of 60° C. for 4 hours, and punched into a circle having a diameter of 3 cm to obtain a disk-shaped foam rubber. Then, with respect to the obtained foam rubber, the difficulty of deformation was evaluated according to the above method when the foam rubber contained an ultraviolet absorber (octyl paramethoxycinnamate). The results are shown in Table 1.

Example 2
A latex mixture and a latex composition were prepared in the same manner as in Example 1 except that the latex mixture was concentrated under reduced pressure under the conditions of 70° C. and 70 kPa for one hour, and the solid content concentration and the viscosity were changed as shown in Table 1. , Foam and foam rubber were obtained and evaluated in the same manner. The results are shown in Table 1.

Comparative Example 1
Urethane polymer latex (trade name "Superflex E-2000", manufactured by Daiichi Kogyo Seiyaku Co., Ltd., containing a nonionic urethane polymer, and the content of the nonionic surfactant is relative to the weight of the urethane polymer. 3% by weight) and the solid content concentration and viscosity of the latex mixture were changed as described in Table 1 to obtain a latex mixture, a latex composition, a foam and a foam rubber in the same manner as in Example 1. And evaluated in the same manner. The results are shown in Table 1.

Comparative example 2
The same as Example 1 except that the latex of the nitrile group-containing conjugated diene copolymer was used without using the latex of the urethane polymer and the solid content concentration and the viscosity of the latex mixture were changed as shown in Table 1. Then, a latex composition, a foam and a foam rubber were obtained and evaluated in the same manner. The results are shown in Table 1.

Comparative Example 3
A latex of a urethane polymer (trade name "F-2471D", manufactured by Dai-ichi Kogyo Seiyaku Co., containing an anionic urethane polymer, containing no surfactant) was used to display the solid content concentration and viscosity of the latex mixture. A latex mixture and a latex composition were obtained and evaluated in the same manner as in Example 1 except that the changes were made as described in 1. The results are shown in Table 1.

As shown in Table 1, a nitrile group-containing conjugated diene-based copolymer, an anionic urethane polymer and a nonionic surfactant were contained, and the content of the nonionic surfactant was relative to the urethane polymer. Thus, the latex of 0.5 to 10% by weight was excellent in moldability, and it was possible to produce a foam rubber which was not easily deformed even when an ultraviolet absorber was contained (Examples 1 and 2).

On the other hand, the latex containing a nonionic urethane polymer was inferior in moldability (Comparative Example 1).
Further, when a latex containing no urethane polymer was used, it was not possible to produce a foam rubber that was difficult to deform even when it contained an ultraviolet absorber (Comparative Example 2).
Further, the latex containing no nonionic surfactant was inferior in moldability, and a foam rubber could not be produced (Comparative Example 3).

Claims

A latex for a foam rubber containing a nitrile group-containing conjugated diene copolymer, a urethane polymer and a nonionic surfactant,
The urethane polymer is anionic,
A latex for foam rubber, wherein the content of the nonionic surfactant is 0.5 to 10% by weight based on the urethane polymer.
The content ratio of the nitrile group-containing conjugated diene copolymer and the urethane polymer is 50:50 to 95:5 as a weight ratio of the nitrile group-containing conjugated diene copolymer:urethane polymer. The latex for foam rubber according to 1.
The latex for foam rubber according to claim 1 or 2, which has a solid content concentration of 60% by weight or more.
The latex for foam rubber according to any one of claims 1 to 3, wherein a viscosity measured with a B-type viscometer at a rotation speed of 60 rpm is 100 to 900 mPa·s.
A foam rubber obtained by using the latex for foam rubber according to any one of claims 1 to 4.