JP2012180437A - Polychloroprene latex composition - Google Patents

Abstract

Disclosed is a polychloroprene latex excellent in adhesive strength and storage stability.
SOLUTION: Adhesive strength and storage are obtained by containing 0.05 to 10 parts by mass of zinc oxide having a fiber length of 0.5 to 100 μm with respect to 100 parts by mass in terms of solid content of polychloroprene latex. A polychloroprene latex composition having excellent stability can be obtained. The polychloroprene latex is preferably obtained by emulsion polymerization in the presence of polyvinyl alcohol in which the chloroprene polymer is a copolymer of chloroprene and a carboxyl group-containing vinyl monomer. Moreover, it is preferable to utilize as an adhesive agent.
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Description

  The present invention relates to an adhesive, non-woven fabric binder, latex-impregnated paper, rubberized cloth, resorcin-formalin-latex liquid (RFL liquid), gloves and boots for adhesion of rubber and fiber cloth of toothed belt and fiber processing of core wire. The present invention relates to a polychloroprene latex composition that can be used for immersion molding products such as

When the polychloroprene latex composition is stored for a long period of time in an environment exposed to sunlight or high temperatures, the pH gradually changes due to the dehydrochlorination reaction of the chloroprene polymer, and the compounding agent causes layer separation or precipitation. There are things to do. Conventionally, it has been known that it is effective to blend zinc oxide as an acid acceptor for hydrochloric acid in a polychloroprene latex composition for such problems. Further, when the chloroprene polymer in the polychloroprene latex composition is a copolymer of chloroprene and unsaturated carboxylic acid, it is possible to form a bridge between zinc ions and carboxyl groups by adding zinc oxide. It can also improve heat-resistant adhesive strength and the like in adhesive applications.
In order to improve the blending effect of such zinc oxide or to add new functions such as light discoloration resistance, blending carboxyl group-modified polychloroprene latex with zinc oxide with a large surface area called active zinc white And the adhesive agent which improved the water-resistant adhesive force is known (for example, refer patent document 1). Further, a latex composition and an adhesive in which fine zinc oxide having a particle size of less than 200 nm is blended with polychloroprene latex to improve adhesive strength and light discoloration resistance (see, for example, Patent Document 2 and Patent Document 3). A latex composition and an adhesive (for example, see Patent Document 4) in which light discoloration resistance is improved by blending scaly silica carrying zinc oxide fine particles with polychloroprene latex are known.
Furthermore, latex compositions and adhesives are known in which magnesium hydroxide or magnesium oxide is blended with polychloroprene latex at the same time as zinc oxide to improve light discoloration resistance (see, for example, Patent Document 5). .

JP 58-113224 A JP-A-11-209523 (Japanese Patent No. 3957384) WO2004 / 106422 (special table 2007-506851) JP 2002-47377 A JP 2002-155167 A

Although the performance of the polychloroprene latex composition has been improved by these means, each technique has the following drawbacks.
For example, since the technique described in Patent Document 1 uses active zinc white having a large surface area, particles of active zinc white are likely to aggregate, and it is difficult to mix finely and uniformly in latex. For this reason, viscosity stability during storage of the polychloroprene latex composition may be a problem.

The techniques of Patent Document 2 and Patent Document 3 lead to an increase in the cost of the latex composition and the adhesive because the price of the particulate zinc oxide having a particle diameter of less than 200 nm is high.
In the techniques of Patent Document 4 and Patent Document 5, silica particles and magnesium compound particles are likely to settle, and storage stability may be a problem when the type and amount of the thickener are inappropriate. .

  An object of the present invention is to provide a polychloroprene latex excellent not only in adhesive strength but also in storage stability.

  By including 0.05 to 10 parts by mass of acicular zinc oxide having a fiber length of 3 to 200 μm in terms of solid content with respect to 100 parts by mass in terms of solid content of polychloroprene latex, the adhesive strength and storage stability are excellent. The inventors have found that a polychloroprene latex composition can be obtained, and have solved the above problems. The polychloroprene latex is preferably obtained by emulsion polymerization in the presence of polyvinyl alcohol, in which the chloroprene polymer is preferably a copolymer of chloroprene and a carboxyl group-containing vinyl monomer. Is preferred. The resulting polychloroprene latex is a resorcin-formalin-latex solution (RFL solution) for bonding adhesives, nonwoven fabric binders, latex-impregnated paper, rubberized cloth, toothed belt rubber and fiber cloth, and fiber processing of core wires. It can be used for immersion molded products such as gloves and boots, and can be particularly suitably used as an adhesive.

  Even if the polychloroprene latex composition of the present invention is stored for a long period of time, it is possible to produce an adhesive that is less likely to cause a decrease in pH and that the compounding agent is precipitated and that has excellent adhesive strength.

  Hereinafter, embodiments for carrying out the present invention will be described in detail. Note that the present invention is not limited to the embodiments described below.

  The polychloroprene latex is a latex (emulsion) obtained by emulsifying a chloroprene polymer in water via an emulsifier. The chloroprene polymer is a homopolymer of 2-chloro-1,3-butadiene (hereinafter referred to as chloroprene) or a copolymer of chloroprene and a monomer copolymerizable with chloroprene.

Examples of monomers copolymerizable with chloroprene include carboxyl group-containing vinyl monomers such as 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, sulfur, acrylic acid and methacrylic acid. Examples thereof include esters and esters thereof, and two or more of them may be used as necessary. Among these, a carboxyl group-containing monomer is preferable. Particularly, when methacrylic acid is used, when a metal oxide such as zinc oxide or magnesium oxide is blended in an adhesive, a cross-linking between a divalent metal ion and a carboxyl group occurs. It is preferable because the adhesive performance such as heat resistance and solvent resistance of polychloroprene latex and an adhesive obtained using the same can be improved.
The charge amount of the monomer copolymerizable with chloroprene is preferably in the range of 0.01 to 5 parts by mass of the carboxyl group-containing vinyl monomer out of 100 parts by mass of the monomers.

  The emulsifier and / or dispersant used for emulsion polymerization of the monomer is not particularly limited, and anionic emulsifier, nonionic emulsifier and cationic emulsifier conventionally used for emulsion polymerization of chloroprene are used. That's fine. Specific examples of the anionic emulsifier include carboxylic acid type and sulfate ester type. For example, alkali metal salt of rosin acid, alkyl sulfonate having 8 to 20 carbon atoms, alkyl aryl sulfate, sodium naphthalene sulfonate and formaldehyde And the like. Specific examples of the nonionic emulsifier include polyvinyl alcohol or a copolymer thereof (for example, a copolymer with acrylamide), polyvinyl ether or a copolymer thereof (for example, a copolymer with maleic acid), a polyoxyethylalkyl. Examples include ether, polyoxyethylene alkylphenol, sorbitan fatty acid ester, polyoxyethylene acyl ester and the like. Specific examples of the cationic emulsifier include aliphatic amine salts, aliphatic quaternary ammonium salts, and the like, for example, octadecyltrimethylammonium chloride, dodecyltrimethylammonium chloride, dilauryldimethylammonium chloride and the like.

  Among these compounds, it is preferable to use polyvinyl alcohol. When polyvinyl alcohol is selected as an emulsifier, it becomes easy to uniformly disperse acicular zinc oxide described later in the latex. The amount of polyvinyl alcohol charged during emulsion polymerization is preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the total amount of initial charged monomers. If it is less than 0.5 part by mass, the emulsifying power may not be sufficient, and if it exceeds 10 parts by mass, the water resistance of the resulting adhesive may be reduced. The saponification degree of the polyvinyl alcohol used is preferably 70 to 95 mol%. When the degree of saponification is less than 70 mol%, the dissolution rate of polyvinyl alcohol in water may be slow, and productivity may be reduced. On the other hand, if the degree of saponification exceeds 95 mol%, the emulsifying performance of polyvinyl alcohol is lowered, and stable emulsion polymerization may not be performed. In addition, the saponification degree prescribed | regulated here is the value measured by the method prescribed | regulated to JISK6726.

  Polyvinyl alcohol preferably has an aqueous solution viscosity (viscosity at 20 ° C. of an aqueous solution having a concentration of 4% by mass) measured by a method defined in JIS K 6726 of 3 to 60 mPa · s. When this aqueous solution viscosity is less than 3 mPa · s, the aqueous solution may be easily scattered. Moreover, when aqueous solution viscosity exceeds 60 mPa * s, the melt | dissolution rate with respect to the water of polyvinyl alcohol may become slow, or the adhesion amount to the inner wall of a melt | dissolution tank may increase.

  When modified polyvinyl alcohol is used, if the degree of polymerization is measured by the method defined in JIS K 6726, crosslinking and insolubilization occur at the pretreatment stage in which unsaponified vinyl acetate units are completely saponified. In some cases, it is not possible to obtain an accurate degree of polymerization. Therefore, in the present invention, instead of the degree of polymerization, a preferred range of aqueous solution viscosity defined in JIS K 6726 is described. The preferred degree of polymerization when not insolubilized by pretreatment is preferably 200-2500.

  The polymer structure of the chloroprene polymer in the polychloroprene latex is not particularly limited, but the molecular weight, molecular weight can be selected by arbitrarily selecting the polymerization temperature, polymerization initiator, chain transfer agent, polymerization terminator, polymerization rate, etc. Distribution, gel content, molecular end structure, crystallization rate can be controlled.

  Although the polymerization temperature at the time of emulsion polymerization is not particularly limited, it is preferably 5 to 50 ° C. in order to carry out the polymerization reaction smoothly.

  In addition, the initiator added to start the emulsion polymerization is not particularly limited, and those conventionally used for emulsion polymerization of chloroprene can be used, for example, persulfates such as potassium persulfate. And organic peroxides such as 3-butyl hydroperoxide.

  The chain transfer agent added to advance the emulsion polymerization reaction is not particularly limited, and those conventionally used for emulsion polymerization of chloroprene can be used. For example, n-dodecyl mercaptan and tert-dodecyl mercaptan can be used. Long chain alkyl mercaptans such as diisopropyl xanthogen disulfide and diethyl xanthogen disulfide such as diethyl xanthogen disulfide, and iodoform.

  The polymerization terminator (polymerization inhibitor) added to stop the emulsion polymerization is not particularly limited, and those conventionally used for emulsion polymerization of chloroprene can be used. For example, 2,6- Examples include tertiary butyl-4-methylphenol, phenothiazine, and hydroxyamine.

  Although the final polymerization rate of a chloroprene polymer is not specifically limited, it can be arbitrarily adjusted at 70 to 100%. Removal of the unreacted monomer (demonomer) is performed by a known method such as heating under reduced pressure.

The chloroprene polymer contained in the polychloroprene latex of the present invention preferably has a toluene insoluble content of 10 to 99%. By adjusting to this range, when the polychloroprene latex composition is used as an adhesive, an adhesive having an excellent balance between the initial adhesive force and the normal adhesive force can be produced.
The toluene-insoluble content of the chloroprene polymer can be adjusted by arbitrarily selecting a polymerization temperature, a polymerization initiator, a chain transfer agent, a polymerization terminator, a polymerization rate, and the like when the monomer is emulsion polymerized.

  The acicular zinc oxide used in the present invention is zinc oxide crystal particles having a fiber length of 0.5 to 100 μm having an acicular tip. When the fiber length is shorter than 0.5 μm, the particles tend to aggregate and difficult to uniformly disperse in the latex. When the fiber length is longer than 100 μm, when the polychloroprelatex composition is used as an adhesive, the polymers This may hinder adhesion and cause poor adhesion. Zinc oxide may have a tetrapot shape in which 3 to 4 acicular crystals are bonded at one end, and each extends in 3 to 4 different directions.

The content of acicular zinc oxide is 0.05 to 10 parts by mass in terms of solid content with respect to 100 parts by mass in terms of solid content of polychloroprene latex. If it is less than 0.05 parts by mass, the effect of stabilizing the pH during storage of the polychloroprene latex composition cannot be obtained, and if it exceeds 10 parts by mass, precipitation tends to occur in the latex, which is not preferable.
The acicular zinc oxide may be added directly to the polychloroprene latex as a powder, but it is mixed with an emulsifier and water in a wet pulverizer such as a ball mill or a bead mill, and dispersed in water by 30 to 80% by mass. When the liquid is prepared and then added to the polychloroprene latex, it can be defoamed, which is desirable. Further, when pulverized in a wet pulverizer, the shape of the tetrapot is destroyed and the needle-like zinc oxide is separated into one by one, but this does not affect the adhesive strength and storage stability. Needle-shaped zinc oxide is surface-treated with a silane coupling agent, titanate coupling agent, aluminum coupling agent, etc. before being added to the polychloroprene latex, so that the adhesive strength of the polychloroprene latex composition is increased. It is also possible to improve.

  The use of the polychloroprene latex composition of the present invention is most preferably an adhesive. In order to use as an adhesive, depending on the application and required performance, polychloroprene latex, tackifier resin, thickener, vulcanization accelerator, filler (reinforcing agent), pigment, colorant, antioxidant , UV absorbers, antifungal agents, antiseptics, antibacterial agents, plasticizers, pH adjusters, antifoaming agents, rust preventives, polymer latexes other than polychloroprene, and the like are arbitrarily blended. Moreover, it is also possible to combine with a hardening | curing agent to make a two-component adhesive.

Examples of tackifying resins, rosin resins, rosin ester resins, hydrogenated rosin resins, polymerized rosin resins, alpha-pinene resins, beta-pinene resins, terpene phenol resins, C ₅ fraction petroleum resin, C ₉ fraction Examples thereof include branched petroleum resins, C ₅ / C ₉ fraction petroleum resins, DCPD petroleum resins, alkylphenol resins, xylene resins, coumarone resins, coumarone indene resins, and the like. As a method for adding the tackifying resin, it is preferable to add it as an emulsion in order to uniformly mix it in the adhesive. Further, the method for producing a tackifying resin emulsion includes a method in which a resin dissolved in an organic solvent such as toluene is emulsified / dispersed in water using an emulsifier, and then the organic solvent is removed while heating under reduced pressure. Although there is a method of pulverizing and emulsifying / dispersing, the former method capable of producing a finer particle emulsion is preferred.

  Specific examples of thickeners include organic thickeners such as polyacrylic acid-based, polyacrylamide-based, HUR-based (polymers in which both ends of polyethylene oxide are end-capped with hydrophobic groups), silicate compounds such as hectorite and montmorillonite. Inorganic thickeners such as Among these, the HEUR system is suitable because a large thickening effect can be obtained with a small addition amount and the viscosity stability after blending is excellent.

  Examples of the vulcanization accelerator include thiourea, dithiocarbamate and xanthate. Specific examples of the thiourea compound include ethylenethiourea, dibutylthiourea, dilaurylthiourea, N, N′-diphenylthiourea, trimethylthiourea (TMU), N, N′-diethylthiourea (EUR), and the like. Examples of dithiocarbamates include zinc dimethylcarbamate, zinc diethyldithiocarbamate, zinc dibutylthiocarbamate, zinc N-pentamethylenedithiocarbamate, zinc dibenzyldithiocarbamate, copper (II) dimethyldithiocarbamate, iron dimethyldithiocarbamate (III), tellurium dimethyldithiocarbamate (IV) and the like. Examples of xanthates include zinc butyl xanthate, zinc isopropyl xanthate, gallium (III) ethyl xanthate, and the like.

  When using a hardening | curing agent, it can be set as a two-component adhesive using a water dispersion type isocyanate compound. If a curing agent is used, water resistance and solvent resistance can be improved. The water-dispersed isocyanate compound is obtained by introducing a hydrophilic group into a polyisocyanate polymer obtained from an aliphatic and / or alicyclic diisocyanate and having a structure such as burette, isocyanurate, urethane, uretdione, or allophanate in the molecule. is there. That is, it is a self-emulsifying isocyanate compound that can be dispersed as fine particles in water when added and stirred in water. Examples of the aliphatic and / or alicyclic isocyanate include tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate, lysine diisocyanate (LDI), isophorone diisocyanate (IPDI), and hydrogenated xylylene diene. Isocyanate (hydrogenated XDI), tolylene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), polymerized MDI, xylylene diisocyanate (XDI), naphthylene diisocyanate (NDI), paraphenylene diisocyanate (PPDI), tetra Methylxylylene diisocyanate (TMXDI), dicyclohexylmethane diisocyanate (HMDI), isopropylide Bis (4-cyclohexyl isocyanate) (IPC), cyclohexyl diisocyanate (CHPI), tolidine diisocyanate (TODI), and the like. Among these, HDI, MDI, IPDI, and hydrogenated XDI are industrially easily available and good. The hydrophilic group is introduced by reacting an emulsifier having an ethylene oxide repeating unit with a part of the molecular chain of a polymer obtained from the above aliphatic and / or alicyclic diisocyanate. As the emulsifier having an ethylene oxide repeating unit, polyethylene glycol monomethyl ether is particularly preferable in view of dispersibility in water. The effect as a curing agent depends on the isocyanate group content calculated by the method defined in JIS K-7301 rather than the raw material compound. In order to obtain good adhesive strength, the isocyanate group content of the isocyanate compound used is preferably 17 to 25% by mass.

  When using a water-dispersed isocyanate compound as a curing agent to form a two-component adhesive, the polychloroprene latex in the main agent is 100 parts by mass in solid content, and the water-dispersed isocyanate compound in the curing agent is solid content. It is preferable to mix so that it may become 0.5-15 mass parts. If it is less than 0.5 parts by mass, the adhesive strength is insufficient, and if it is added more than 15 parts by mass, the pot life (usable time) after mixing the main agent and the curing agent may be shortened.

  The solid content of the polychloroprene latex composition of the present invention is preferably 45 to 60% by mass. If it is this range, thixotropic property can be controlled low and the aqueous adhesive agent with favorable coating property will be obtained.

  Hereinafter, the effects of the present invention will be specifically described with reference to Examples and Comparative Examples of the present invention.

[Examples 1 to 8] [Comparative Examples 1 to 8]
<Manufacture of polyvinyl alcohol>
A polymerization reactor was charged with 120 g of vinyl acetate, 560 g of methanol, and 1.6 g of a 1% methanol solution of azobisisobutyronitrile, and after heating with nitrogen, heated to the boiling point. Next, 1720 g of methyl acetate, 607 g of methanol, and 406 g of 1% methanol solution of azobisisobutyronitrile were continuously added over 14 hours, and after 1 hour from the end of continuous addition, the polymerization rate of vinyl acetate reached 99%. After confirming this, the polymerization reaction was stopped. Subsequently, unreacted vinyl acetate was removed by a conventional method, and the resulting polymer was saponified with sodium hydroxide by a conventional method. Thereafter, it was dried with hot air at 90 ° C. for 90 minutes to obtain polyvinyl alcohol. As a result of analysis according to JIS K 6726, the average polymerization degree of polyvinyl alcohol was 280, and the saponification degree was 79.4 mol%.

<Production of polychloroprene latex A>
Using a reactor having an internal volume of 3 liters, 86 parts by mass of water and 3.2 parts by mass of polyvinyl alcohol were dissolved at 60 ° C. under a nitrogen stream. After cooling this polyvinyl alcohol aqueous solution to room temperature, 97.5 mass parts of chloroprene monomers, 2.5 mass parts of methacrylic acid, and 0.25 mass parts of octyl mercaptan were added in this. While maintaining this at 40 ° C., polymerization was carried out using potassium persulfate as an initiator. After adding 20% by mass diethanolamine aqueous solution to the reaction-terminated liquid to adjust the pH to 7 and removing unreacted monomers under reduced pressure, the water is further evaporated under reduced pressure to perform concentration. A polychloroprene latex A having a concentration of 55% was obtained. The latex had a gel content of 55%. The solid content concentration and the gel content were measured by the following methods.

<Concentration of solid content>
Let A be the mass of the aluminum dish alone. Let B be the mass of an aluminum dish containing 2 ml of a latex sample. Let C be the mass after the aluminum dish containing the latex sample is dried at 125 ° C. for 1 hour. The solid content concentration (%) was calculated by the following formula.
Solid content concentration = {(C−A) / (B−A)} × 100

<Gel content (toluene insoluble matter)>
The latex sample was lyophilized and weighed to A. It was dissolved in toluene (adjusted to 0.6%) at 23 ° C. for 20 hours, and the gel was separated using a centrifuge and a 200-mesh wire mesh. The gel was air-dried, dried in an atmosphere at 110 ° C. for 1 hour, and weighed to give B. The gel content (%) was calculated according to the following formula.
Gel content = (B / A) × 100

<Production of polychloroprene latex B>
Using a reactor having an internal volume of 3 liters, 100 parts by mass of water, 4 parts by mass of disproportionated rosin acid, 1.0 part by mass of potassium hydroxide, sodium salt of formaldehyde naphthalenesulfonic acid condensate 0.8% under a nitrogen stream Then, 100 parts by mass of chloroprene and 0.3 parts by mass of n-dodecyl mercaptan were added with stirring. Polymerization was carried out at 40 ° C. in a nitrogen atmosphere using potassium persulfate as an initiator. When the polymerization rate reached 90%, an emulsion of phenothiazine was added to terminate the polymerization. After removing the unreacted monomer under reduced pressure, the water was further evaporated under reduced pressure to perform concentration, and a polychloroprene latex B having a solid content concentration of 55% was obtained. The latex had a gel content of 18%.

<Manufacture of zinc oxide B (aqueous dispersion of zinc oxide A)>
First, 100 parts by mass of casein, 70 parts by mass of ammonia water having a concentration of 28% by mass, 3 parts by mass of polyoxyethylene alkylphenyl ether (HS-210 / manufactured by NOF Corporation), and 827 parts by mass of water were mixed to obtain a concentration of 10 A mass% ammonium casein aqueous solution was prepared. Next, 100 parts by mass of acicular zinc oxide (Panatetra WZ-0501 / manufactured by Amtec Co., Ltd.), 3 parts by mass of sodium salt of formaldehyde naphthalenesulfonic acid condensate, 30 parts by mass of an aqueous ammonium casein solution having a concentration of 10% by mass, and water 167 Then, it was placed in a ceramic ball mill and pulverized and dispersed for 24 hours in an atmosphere of 25 ° C. to prepare an aqueous dispersion of zinc oxide having a concentration of 33% by mass.

<Production of polychloroprene latex composition>
With respect to polychloroprene latex A to B, zinc oxide, a tackifier resin, and a thickener were blended in the formulation of Table 1 to obtain adhesives of Examples 1 to 8 and Comparative Examples 1 to 8. The unit of the blending amount is a solid content conversion. The trade names and properties of each compounding agent are shown below.
Zinc oxide A: trade name is Panatetra WZ-0501 / Amtech Co., Ltd., acicular zinc oxide powder having a fiber length of 2 to 40 μm.
Zinc oxide B: aqueous dispersion of zinc oxide A, fiber length 1 to 10 μm, solid content 33%.
Zinc oxide C: trade name is AZ-SW, manufactured by Osaki Kogyo Co., Ltd., average particle size 0.20 μm, solid content 50%.
Zinc oxide D: trade name is zinc oxide 2 types / made by Hakusuitec Co., Ltd., powder having an average particle size of 1.0 μm.
Tackifying resin: Trade name is Tamanol E-100 / Arakawa Chemical Industries, Ltd., terpene phenol resin emulsion.
Thickener: Trade name is RM-8W / Rohm and Haas Japan Co., Ltd., HEUR thickener.

<Storage stability test>
The polychloroprene latex composition was sealed in a glass bottle and allowed to stand at 24 ° C. or 40 ° C. for 2 months, and the presence or absence of layer separation or sedimentation was visually confirmed. When there was no change in appearance, it was judged as ◯, and when layer separation or sedimentation occurred, it was judged as ×.

Below, the adhesive force test method at the time of utilizing a polychloroprene latex composition as an adhesive agent is demonstrated.
150 g (wet) / m ² of adhesive is applied to each of two canvases (size of glue margin is 25 mm wide x 70 mm long) with a brush and dried in an atmosphere at 23 ° C. for 3 hours. To 200 g (wet) / m2 of adhesive was applied with a brush, dried in an atmosphere at 70 ° C. for 5 minutes, and then bonded and pressure-bonded with a hand roller.
<Initial adhesive strength>
One day after the pressure bonding, 180 ° peel strength was measured with a tensile tester at a tensile speed of 200 mm / min.
<Normal adhesive strength>
Five days after the pressure bonding, the 180 ° peel strength was measured with a tensile tester at a tensile speed of 200 mm / min.
<Softening point>
On the ceiling of the oven, the gripping portion of one of the test pieces (the size of the adhesive margin portion is 25 mm in width × 25 mm in length) after 5 days has been fixed, and the inside of the oven was maintained at 38 ° C. In the procedure of 180 ° peeling test, attach a 500g weight to the other grip, heat at 38 ° C for 15 minutes, then raise the temperature by 2 ° C every 5 minutes, and the oven when the weight falls The internal temperature was recorded. A higher softening point means higher heat-resistant adhesion.

The evaluation results are summarized in Table 1.

  As can be seen from Table 1, it was shown that the polychloroprene latex compositions of Examples 1 to 8 were superior to the polychloroprene latex compositions of Comparative Examples 1 to 8 in adhesive strength. In particular, when polychloroprene latex obtained by emulsion copolymerization of chloroprene and a carboxyl group-containing vinyl monomer using the polyvinyl alcohol of Examples 1 to 4 is used, it can be seen that high heat-resistant adhesive strength is exhibited.

Claims (4)

  A polychloroprene latex composition containing 100 parts by mass of polychloroprene latex in terms of solid content and 0.05 to 10 parts by mass of zinc oxide having a fiber length of 0.5 to 100 μm in terms of solid content.   The polychloroprene latex according to claim 1, wherein the chloroprene polymer in the polychloroprene latex is a copolymer of chloroprene and a carboxyl group-containing vinyl monomer.   The polychloroprene latex composition according to claim 1 or 2, wherein the polychloroprene latex is obtained by emulsion polymerization in the presence of polyvinyl alcohol.   The polychloroprene latex composition according to any one of claims 1 to 3, which is used as an adhesive.