JPWO2020111144A1 - Latex manufacturing method and latex - Google Patents

Abstract

An elastomer solution in which an elastomer is dissolved in water in which polyvinyl alcohol having a saponification degree of 60 to 97 mol% is dissolved and a water-insoluble organic solvent having a specific gravity of 0.8 or more and a boiling point of 95 ° C or less at 20 ° C. A method for producing a latex, which comprises a step of mixing and stirring.

Description

The present invention relates to a method for producing latex and latex. More specifically, a method for producing a latex having one or more aqueous phases inside and drying the aqueous phases to form elastomer particles forming voids, and one or more aqueous phases inside. The present invention relates to a latex containing elastomer particles in which the aqueous phase forms voids when dried.

Particles with voids inside have basic characteristics such as weight reduction (low specific density), heat insulation and sound insulation, low dielectric loss, low electrical conduction, reflection / scattering anomaly, impact resistance, rigidity improvement, and texture. It is known that it exhibits peculiar properties from the viewpoint of impartation. For this reason, particles having voids inside have conventionally been used in various molded bodies, wallpaper, paints, building materials, sealants, adhesives, soles, synthetic leather, tires, paper, cement, tiles, FRP, capacitors, etc. It is used in a very wide range of fields.

Examples of the particles having voids inside include hollow granules made of fine particle titanium oxide surface-treated with silicic anhydride (Patent Document 1). We also propose hollow silica-based fine particles (Patent Documents 2 and 3) and hollow particles of metal oxide produced by removing the polymer after forming a coating layer made of metal oxide on the surface of spherical polymer fine particles. (Patent Document 4). Further, hollow fine particles of fullerene-like boron nitride obtained by reacting carbon nanotubes with a boron oxide at a high temperature have also been proposed (Patent Document 5). However, these particles have poor flexibility in a room temperature environment and may not be suitable for product fields where flexibility is required.

Therefore, a technique for producing particles having voids inside and having flexibility in a normal temperature environment using an elastomer has been studied. For example, hollow microcapsules made of a styrene-based thermoplastic elastomer containing a polystyrene block and a polyolefin block and having a void ratio of 10 to 95% have been proposed (Patent Document 6). Further, an elastomer particle having a glass transition point of −100 to 0 ° C. and having at least one void has also been proposed (Patent Document 7).

Japanese Unexamined Patent Publication No. 2014-58441 Japanese Unexamined Patent Publication No. 2013-1219111 Japanese Unexamined Patent Publication No. 2014-58683 Japanese Unexamined Patent Publication No. 2000-34582 Japanese Unexamined Patent Publication No. 2001-294409 JP-A-2009-207973 International Publication No. 2016/031845

Elastomer particles having such characteristics are expected to be used in fields different from conventional hollow particles lacking flexibility, and demand is expected to increase. Therefore, there is a demand for a technique capable of more efficiently producing elastomer particles having voids inside.

Therefore, the present invention provides a method for producing latex, which has one or more aqueous phases inside and can improve the yield of elastomer particles in which the aqueous phases form voids by drying. Is the main purpose.

That is, the present invention
Water in which polyvinyl alcohol with a saponification degree of 60 to 97 mol% is dissolved, and
An elastomer solution in which an elastomer is dissolved in a poorly water-soluble organic solvent having a specific gravity of 0.8 or more and a boiling point of 95 ° C. or less at 20 ° C.
Provided is a method for producing latex, which comprises a step of mixing and stirring.
In the production method, a surfactant having an HLB of 8.0 or less may be dissolved in the poorly water-soluble organic solvent.
In addition, the present invention
water and,
An elastomer solution in which an elastomer and a surfactant having an HLB of 8.0 or less are dissolved in a water-insoluble organic solvent having a specific gravity of 0.8 or more and a boiling point of 95 ° C or less at 20 ° C.
After mixing and stirring
Provided is a method for producing a latex, which comprises a step of adding water in which polyvinyl alcohol having a degree of saponification of 60 to 97 mol% is dissolved and stirring the mixture.
The surfactant having an HLB of 8.0 or less may be at least one selected from the group consisting of sorbitan monooleate, sorbitan trioleate and glycerol monostearate.
At least one of the polyvinyl alcohol having a saponification degree of 20 to 59 mol% and the carboxy-modified polyvinyl acetate in at least one of the elastomer solution and the water in which the polyvinyl alcohol having a saponification degree of 60 to 97 mol% is dissolved. One may be dissolved.
The polyvinyl acetate is at least one selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, maleic acid monoester, fumaric acid monoester and itaconic acid monoester. It may be a copolymer of vinyl acetate.
The elastomer may be chloroprene rubber, nitrile rubber or a styrene-based block copolymer.
The poorly water-soluble organic solvent may be a halogen-based organic solvent.

In addition, the present invention
Elastomer particles that have one or more aqueous phases inside and that are dried to form voids.
Provided is a latex containing water in which polyvinyl alcohol having a degree of saponification of 60 to 97 mol% is dissolved.
The latex may contain a surfactant having an HLB of 8.0 or less.
The latex may contain at least one of polyvinyl alcohol having a saponification degree of 20 to 59 mol% and carboxy-modified polyvinyl acetate.
The cast film produced by using the latex according to the following production conditions may have a thermal conductivity of 0.100 W / mk or less, a breaking strength of 3.5 MPa or more, and a breaking elongation of 180% or more.
Production conditions:
The latex was poured onto a glass plate placed horizontally and dried at room temperature for 3 days to form a film film having a thickness of 0.5 mm, and then vacuum dried at room temperature for 1 day to evaporate water, and the length was 100 mm and the width was 50 mm. To make a cast film.
The latex may be used for water-based adhesives or water-based paints.
The present invention also provides a water-based adhesive or a water-based paint using the latex.

According to the present invention, there may be provided a method for producing a latex which has one or more aqueous phases inside and can improve the yield of elastomer particles in which the aqueous phases form voids by drying. ..

Hereinafter, modes for carrying out the present invention will be described. It should be noted that the embodiments described below show an example of the embodiments of the present invention, and the scope of the present invention is not narrowly interpreted by this. The upper limit value and the lower limit value of each numerical range can be arbitrarily combined as desired.

<1. Latex manufacturing method>
The method for producing latex according to an embodiment of the present invention is a method for producing latex for producing elastomer particles having one or more voids inside. Further, the method for producing latex according to the present embodiment may also be a method for producing latex containing elastomer particles having one or more aqueous phases inside and the aqueous phases forming voids by drying. .. It should be noted that the elastomer particles having one or more aqueous phases inside and forming voids in the aqueous phase by drying have one aqueous phase inside, and the aqueous phase becomes 1 by drying. Both mononuclear elastomer particles forming one void and multi-hollow elastomer particles having a plurality of aqueous phases inside and the aqueous phase forming a plurality of voids by drying are included.

The manufacturing method of this embodiment is roughly classified into a manufacturing method I and a manufacturing method II, which will be described later. Both of the latexes obtained from the production method I or the production method II have one or more aqueous phases inside, and when the latex is dried, the elastomer particles in which the aqueous phases form voids are produced in good yield. It is preferably used. Hereinafter, the manufacturing method I and the manufacturing method II will be described in detail.

(1) Manufacturing method I
In the production method I, the elastomer is dissolved in water in which a polyvinyl alcohol having a saponification degree of 60 to 97 mol% is dissolved and a water-insoluble organic solvent having a specific gravity of 0.8 or more and a boiling point of 95 ° C or less at 20 ° C. It is a method for producing a latex, which comprises a step of mixing and stirring the elastomer solution which has been prepared.

In the step of mixing and stirring the water and the elastomer solution, preferably, the water and the elastomer solution are mixed and stirred, and the elastomer solution is put into the water as fine droplets having an aqueous phase inside. This is a step of obtaining a finely dispersed dispersion liquid. The “fine particle droplet” means a droplet having a number average particle diameter of 10.0 μm or less.

The production method I is not particularly limited as long as it includes the step of stirring as described above, but is preferably the following production method:
An elastomer solution preparation step of dissolving an elastomer in a poorly water-soluble organic solvent having a specific gravity of 0.8 or more and a boiling point of 95 ° C. or less at 20 ° C. to obtain an elastomer solution.
Water in which polyvinyl alcohol having a saponification degree of 60 to 97 mol% is dissolved and the above-mentioned elastomer solution are mixed and stirred, and the above-mentioned elastomer solution is finely divided into the above-mentioned water as fine droplets having an aqueous phase inside. A dispersion liquid preparation process for obtaining a dispersed dispersion liquid, and
Latex manufacturing methods, including.

The dispersion liquid is a W / O / W type emulsion in which the elastomer solution is finely dispersed in water as fine droplets having an aqueous phase inside. The production method I stabilizes the aqueous phase (internal aqueous phase) inside the fine droplets in the dispersion liquid (W / O / W type emulsion) by using a specific polyvinyl alcohol and a specific water-soluble organic solvent. As a result, a stable W / O / W type emulsion can be formed.

Although details will be described later, by evaporating the poorly water-soluble organic solvent contained in the dispersion liquid, the fine droplets in the dispersion liquid become elastomer particles. The aqueous phase inside the fine droplets (internal aqueous phase) is the "void nucleus" that forms the void structure by being immobilized inside the elastomer particles and then subjected to drying, and the stability of the internal aqueous phase. Affects the yield of elastomer particles having voids inside. That is, by stabilizing the internal aqueous phase, the separation of the internal aqueous phase when the poorly water-soluble organic solvent evaporates is suppressed, and as a result, elastomer particles having no internal voids are generated when subjected to drying. Since it is suppressed, it is possible to increase the yield of elastomer particles having voids inside.

As the elastomer, synthetic rubber and / or thermoplastic elastomer is preferable. The synthetic rubber is preferably chloroprene rubber (CR), styrene-butadiene rubber (SBR), acrylic rubber (ACM), nitrile rubber (NBR), epichlorohydrin rubber (ECO), butadiene rubber (BR), ethylene-propylene-diene rubber. (EPDM), natural rubber (NR) and isoprene rubber (IR). The thermoplastic elastomer is preferably a styrene-based block copolymer.

The "styrene-based block copolymer" means a block copolymer of styrene and a monomer copolymerizable with styrene. Examples of the monomer copolymerizable with styrene include isoprene, butadiene, and chloroprene. Examples of the styrene-based block copolymer include a styrene-isoprene-styrene triblock copolymer (SIS), a styrene-butadiene-styrene triblock copolymer (SBS), and a styrene-ethylenebutylene-styrene triblock copolymer. (SEBS), styrene-ethylenepropylene-styrene triblock copolymer (SEPS), styrene-chloroprene-styrene triblock copolymer (SCS) and the like.

From the viewpoint of improving the thermal conductivity, breaking strength and breaking elongation of the obtained elastomer particles, the elastomer is more preferably chloroprene rubber, nitrile rubber or styrene-based block copolymer, and even more preferably chloroprene rubber. These elastomers may be used alone or in combination of two or more.

The poorly water-soluble organic solvent has a specific gravity of 0.8 or more at 20 ° C., more preferably 0.9 or more, and the upper limit thereof is not particularly limited, but is preferably 1.8 or less, preferably 1.8 or less. Is 1.6 or less. If the specific gravity at 20 ° C. is less than 0.8, the elastomer solution floats when the water in which polyvinyl alcohol is dissolved and the elastomer solution are stirred, and the elastomer solution is stably finely dispersed in the water. It's difficult.

The poorly water-soluble organic solvent has an upper limit of boiling point of 95 ° C. or lower, preferably 90 ° C. or lower, more preferably 80 ° C. or lower, and further preferably 70 ° C. or lower. The lower limit of the boiling point of the poorly water-soluble organic solvent is preferably 30 ° C. or higher, more preferably 40 ° C. or higher. When the elastomer particles are produced from the latex obtained by the production method of the present embodiment, it is necessary to evaporate the poorly water-soluble organic solvent. However, when the boiling point of the poorly water-soluble organic solvent exceeds 95 ° C., the poorly water-soluble organic solvent is used. However, water may evaporate first, and the yield of elastomer particles having voids inside may decrease.

The poorly water-soluble organic solvent is not particularly limited, and examples thereof include halogen-based organic solvents such as chloroprene monomer (2-chloro-1,3-butadiene), methylene chloride, chloroform, and carbon tetrachloride, and benzene. At least one or two or more selected from the group consisting of can be used.

The poorly water-soluble organic solvent having a specific gravity of 0.8 ° C. or higher and a boiling point of 95 ° C. or lower at 20 ° C. can be appropriately selected depending on the type of elastomer.
Elastomers include, for example, chloroprene rubber (CR), styrene-butadiene rubber (SBR), acrylic rubber (ACM), styrene-butadiene-styrene triblock copolymer (SBS) and styrene-chloroprene-styrene triblock copolymer (Styrene-chloroprene-styrene triblock copolymer). In the case of at least one of SCS), the poorly water-soluble organic solvent is preferably a halogen-based organic solvent such as chloroprene monomer (2-chloro-1,3-butadiene), methylene chloride, chloroform, carbon tetrachloride, and benzene.
When the elastomer is, for example, at least one of chloroprene rubber (CR), styrene-isoprene-styrene triblock copolymer (SIS) and styrene-chloroprene-styrene triblock copolymer (SCS), the poorly water-soluble organic solvent is , Chloroprene monomer is more preferable. When the elastomer is, for example, nitrile rubber (NBR) and epichlorohydrin rubber (ECO), the poorly water-soluble organic solvent is preferably a halogen-based organic solvent such as chloroprene monomer, methylene chloride, chloroform, or carbon tetrachloride.
When the elastomer is, for example, butadiene rubber (BR), ethylene-propylene-diene rubber (EPDM), natural rubber (NR) and isoprene rubber (IR), benzene is preferable as the poorly water-soluble organic solvent.
When a chloroprene rubber, a nitrile rubber or a styrene-based block copolymer is used as the elastomer from the viewpoint of improving the thermal conductivity, breaking strength and breaking elongation of the obtained elastomer particles, the poorly water-soluble organic solvent is preferably a halogen-based organic solvent. Chloroprene monomers are more preferred.

The elastomer solution used in the production method I can be obtained by a step of producing an elastomer solution in which the elastomer is dissolved in the poorly water-soluble organic solvent. The method for dissolving the elastomer in the poorly water-soluble organic solvent is not particularly limited, and for example, the poorly water-soluble organic solvent and the elastomer may be stirred using a stirrer. The temperature at this time is not particularly limited as long as it can dissolve the elastomer, but for example, it may be carried out at room temperature, and more specifically, it may be carried out at 5 to 40 ° C. or 10 to 30 ° C.

A polymerization inhibitor or the like may be appropriately added to the poorly water-soluble organic solvent or elastomer solution in order to prevent the polymerization reaction from occurring. The type of the polymerization inhibitor is not particularly limited, and for example, amine compounds such as phenothiazine and thiodiphenylamine; 4-tert-butylcatechol, 2,2'-methylene (bis-4-methyl-6-tert-butylphenol). ) And the like, one or more selected from the group consisting of phenolic compounds and the like can be used. Of these, phenolic compounds are preferable, and 4-tert-butylcatechol is more preferable.

The content of the elastomer in the elastomer solution is not particularly limited, but is preferably 5 to 50 parts by mass, more preferably 10 to 40 parts by mass, out of 100 parts by mass of the elastomer solution.

In the production method I, it is preferable that a surfactant having an HLB of 8.0 or less is dissolved in the poorly water-soluble organic solvent. That is, the above-mentioned elastomer solution is an elastomer solution in which an elastomer and a surfactant having an HLB of 8.0 or less are dissolved in a water-insoluble organic solvent having a specific gravity of 0.8 or more and a boiling point of 95 ° C or less at 20 ° C. It is preferable to have.

The HLB of the surfactant is preferably 8.0 or less, more preferably 7.0 or less, still more preferably 6.0 or less, and particularly preferably 5.0 or less. By using a surfactant having an HLB of 8.0 or less, the stability of the internal aqueous phase in the dispersion is further improved, and the separation of the internal aqueous phase during evaporation of the poorly water-soluble organic solvent is suppressed. It is possible to further increase the yield of elastomer particles having voids in the solvent.

The surfactant is not particularly limited, and is, for example, a sucrose fatty acid ester; a sorbitan fatty acid ester-based surfactant such as sorbitan monostearate, sorbitan monopalmitate, sorbitan monobehenate, and sorbitan monomontanate; glycerin monolaur. Examples include glycerin fatty acid ester-based surfactants such as rate, glycerin monopalmitate, glycerin monostearate, diglycerin disstearate, triglycerin monostearate, and tetraglycerin monomontanate, which are selected from the group consisting of these. At least one species.
Of the above-mentioned surfactants, nonionic surfactants are preferable.

Surfactants with an HLB of 8.0 or less are preferably sorbitan monopalmitate (Span40, HLB: 6.7), sorbitan monostearate (Span60, HLB: 4.7), sorbitan tristearate (Span65, HLB: 2.1), sorbitan monooleate (Span80, HLB: 4.3), sorbitan sesquioareart (Span83, HLB: 3.7), sorbitan trioleate (Span85, HLB: 1.8), and Polysorbate fatty acid esters such as sorbitan isostearates (Span120, HLB: 4.7); glycerol monostearate (MS-60, HLB: 3.5), glycerol monostearates (MS-50, HLB: 2.8). ), Glycerin fatty acid ester type such as glycerol monooleate (MO-60, HLB: 2.8); and the like; at least one selected from the group. Among these, more preferably, at least one selected from the group consisting of sorbitan monooleate, sorbitan trioleate and glycerol monostearate.

The surfactant may be used alone or in combination of two or more. When two or more types of surfactants are used in combination, "surfactant having an HLB of 8.0 or less" means that the HLB of each surfactant is 8.0 or less, and two or more types of interfaces It does not mean that the average HLB value of the activator is 8.0 or less.

When a surfactant is used, the content of the surfactant in the elastomer solution is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 5 parts by mass in 100 parts by mass of the elastomer solution. In the above-mentioned elastomer solution preparation step, the method for dissolving the surfactant in the poorly water-soluble organic solvent is not particularly limited. For example, the poorly water-soluble organic solvent and the surfactant are stirred using a stirrer, and then the elastomer is added. Then, it may be further stirred.

The polyvinyl alcohol having a saponification degree of 60 to 97 mol% used in the production method I has a lower limit of the saponification degree of preferably 70 mol% or more, more preferably 75 mol% or more, still more preferably 80 mol% or more. be. The upper limit of the degree of saponification of the polyvinyl alcohol is preferably 95 mol% or less, more preferably 90 mol% or less. A degree of saponification of polyvinyl alcohol of less than 60 mol% or more than 97 mol% is also applicable, but when the polyvinyl alcohol is used alone, when water in which polyvinyl alcohol is dissolved and an elastomer solution are stirred, when the polyvinyl alcohol is stirred, It cannot be emulsified stably, and it is difficult to stably finely disperse the elastomer solution in water.

Polyvinyl alcohol having a degree of saponification of 60 to 97 mol% may be used alone or in combination of two or more. When two or more kinds of polyvinyl alcohols having a degree of saponification of 60 to 97 mol% are used in combination, "polyvinyl alcohol having a degree of saponification of 60 to 97 mol%" means that the degree of saponification of each polyvinyl alcohol is 60 to 97 mol. It does not mean that the average value of the saponification degree of two or more kinds of polyvinyl alcohols is 60 to 97 mol%.

In at least one of the elastomer solution and the water in which the saponification degree of polyvinyl alcohol of 60 to 97 mol% is dissolved, further, the saponification degree of polyvinyl alcohol of 20 to 59 mol% and the carboxy-modified polyvinyl acetate are added. It is preferable that at least one of them is dissolved. When polyvinyl alcohol having a saponification degree of 20 to 59 mol% and / or carboxy-modified polyvinyl acetate are used in combination, the aqueous phase inside the fine droplets is more stabilized, and the internal aqueous phase when the poorly water-soluble organic solvent evaporates. Withdrawal is more effectively suppressed. As a result, when the latex is subjected to drying, the generation of elastomer particles having no voids inside is suppressed, so that the yield of elastomer particles having voids inside can be increased.

Polyvinyl alcohol having a degree of saponification of 20 to 59 mol% has a lower limit of the degree of saponification of preferably 25 mol% or more, more preferably 30 mol% or more, still more preferably 35 mol% or more, and has a degree of saponification. The upper limit is preferably 50 mol% or less, more preferably 45 mol% or less.

Polyvinyl alcohol having a degree of saponification of 20 to 59 mol% may be used alone or in combination of two or more. When two or more kinds of polyvinyl alcohols having a saponification degree of 20 to 59 mol% are used in combination, "polyvinyl alcohol having a saponification degree of 20 to 59 mol%" means that each polyvinyl alcohol has a saponification degree of 20 to 59 mol. It does not mean that the average value of the saponification degree of two or more kinds of polyvinyl alcohols is 20 to 59 mol%.

The carboxy-modified polyvinyl acetate is a copolymer of vinyl acetate and an unsaturated carboxylic acid. The unsaturated carboxylic acid is at least one selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, maleic acid monoester, fumaric acid monoester and itaconic acid monoester. It is preferable to have. Commercially available products of carboxy-modified polyvinyl acetate include, for example, Denka ASR CH-09 (manufactured by Denka Co., Ltd.). The carboxy-modified polyvinyl acetate may be used alone or in combination of two or more.

A method for obtaining a dispersion liquid in which the water in which the polyvinyl alcohol is dissolved and the elastomer solution are mixed and then stirred to obtain a dispersion liquid in which the elastomer solution is finely dispersed in the water as fine droplets having an aqueous phase inside. , Not particularly limited. For example, water in which polyvinyl alcohol is dissolved and an elastomer solution may be placed in a reaction vessel and stirred using a stirrer. At the time of stirring, the reaction vessel may be cooled in order to suppress the temperature rise due to shear heat generation. The cooling temperature at this time is not particularly limited, and examples thereof include 20 to 0 ° C., 10 to 0 ° C., and 4 to 0 ° C. The number average particle size of the fine particle droplets in the dispersion liquid is preferably adjusted to 10.0 μm or less by adjusting the rotation speed of the stirring device or the like.

In the above dispersion, the content of water in which polyvinyl alcohol is dissolved is preferably 50 to 300 parts by mass, more preferably 50 to 200 parts by mass with respect to 100 parts by mass of the elastomer solution. Further, in the above dispersion, the content of polyvinyl alcohol having a saponification degree of 60 to 97 mol% is preferably 5 to 30 parts by mass, more preferably 5 to 25 parts by mass with respect to 100 parts by mass of the elastomer solution. ~ 20 parts by mass is more preferable. Further, in the above dispersion, the total content of polyvinyl alcohol having a saponification degree of 20 to 59 mol% and / or carboxy-modified polyvinyl acetate is 0.1 to 10% by mass with respect to 100 parts by mass of the elastomer solution. Parts are preferable, 0.5 to 10 parts by mass is more preferable, and 0.5 to 5 parts by mass is further preferable.

In the production method I, in addition to the step of mixing and stirring water in which polyvinyl alcohol having a saponification degree of 60 to 97 mol% is dissolved and an elastomer solution to obtain a dispersion liquid, water problems in the dispersion liquid are added. It is preferable to include a step (solvent evaporation step) of evaporating the soluble organic solvent under normal pressure or reduced pressure to generate elastomer particles having one or more aqueous phases inside. The temperature at the time of evaporation is not particularly limited, but the upper limit thereof is preferably 50 ° C. or lower, more preferably 40 ° C. or lower, and the lower limit thereof is preferably 20 ° C. or higher, more preferably 30 ° C. or higher. The depressurizing condition is not particularly limited, but the upper limit thereof is preferably 100 mmHg or less, more preferably 80 mmHg or less, and the lower limit thereof is preferably 20 mmHg or more, more preferably 40 mmHg or more.

As described above, in the dispersion liquid, the elastomer solution is finely dispersed as fine droplets having an aqueous phase inside. By performing the solvent evaporation step, the poorly water-soluble organic solvent in the elastomer solution constituting the fine droplets evaporates and disappears. As a result, the structure of the elastomer constituting the fine droplets is immobilized, and elastomer particles are generated. Further, due to the immobilization, the aqueous phase (internal aqueous phase) inside the fine droplets is confined in the voids inside the elastomer particles. After that, the latex containing the elastomer particles is subjected to drying, so that the aqueous phase remaining inside the elastomer particles is removed, and the portion where the aqueous phase is removed becomes a void. As described above, the internal aqueous phase can be said to be a "void nucleus" because it is immobilized inside the elastomer particles to form a void structure.

If the internal aqueous phase is unstable, when the poorly water-soluble organic solvent evaporates in the solvent evaporation step, the internal aqueous phase may separate from the fine droplets to generate elastomer particles having no void nuclei inside. Since the property is enhanced, the yield of elastomer particles having voids inside may decrease when the latex is subjected to drying. However, in the production method I, since the internal aqueous phase can be stabilized by using a specific poorly water-soluble organic solvent and a specific polyvinyl alcohol, the separation of the internal aqueous phase is suppressed and the internal aqueous phase is suppressed. Form a stable void nucleus. As a result, the generation of elastomer particles having no voids inside can be suppressed, and the yield of elastomer particles having voids inside can be increased.

The above is the description of the manufacturing method I. Next, the manufacturing method II will be described.

(2) Manufacturing method II
The production method II comprises water and an elastomer solution in which an elastomer and a surfactant having an HLB of 8.0 or less are dissolved in a water-soluble organic solvent having a specific gravity of 0.8 or more and a boiling point of 95 ° C or less at 20 ° C. , Are mixed and stirred, and then water containing a polyvinyl alcohol having a saponification degree of 60 to 97 mol% is added and stirred, which is a method for producing a latex.

The production method II is not particularly limited as long as it includes the above steps, but is preferably the following production method:
Water (A) and
An elastomer solution in which an elastomer and a surfactant having an HLB of 8.0 or less are dissolved in a water-insoluble organic solvent having a specific gravity of 0.8 or more and a boiling point of 95 ° C or less at 20 ° C.
Was mixed and stirred to obtain a dispersion liquid (a) in which water (A) was finely dispersed in the above elastomer solution, and then the dispersion liquid (a) was obtained.
Water (B) in which polyvinyl alcohol having a saponification degree of 60 to 97 mol% is dissolved is added to the dispersion liquid (a) and stirred, and the dispersion liquid (a) is added to the water (B). A method for producing latex, which comprises a step of obtaining a finely dispersed dispersion liquid (b).

The production method II is more preferably the following production method:
An elastomer solution preparation step of dissolving an elastomer and a surfactant having an HLB of 8.0 or less in a poorly water-soluble organic solvent to obtain an elastomer solution, and
A first dispersion liquid preparation step of mixing and stirring the elastomer solution and water (A) to obtain a dispersion liquid (a) in which the water (A) is finely dispersed in the elastomer solution.
Water (B) in which polyvinyl alcohol having a saponification degree of 60 to 97 mol% is dissolved is added to the dispersion liquid (a) and stirred, and the dispersion liquid (a) is added to the water (B). A second dispersion preparation step of obtaining a finely dispersed dispersion (b), and
Latex manufacturing methods, including.

The dispersion liquid (b) is a W / O / W type emulsion, and is a dispersion liquid in which the elastomer solution is finely dispersed in water (B) as fine droplets having an aqueous phase inside. In the production method II, the aqueous phase (internal aqueous phase) inside the fine droplets in the dispersion liquid (b) (W / O / W type emulsion) is used by using a specific polyvinyl alcohol and a specific poorly water-soluble organic solvent. Can be stabilized, and thus a stable W / O / W type emulsion can be formed. As described in the above-mentioned production method I, by stabilizing the internal aqueous phase, it is possible to suppress the generation of elastomer particles having no voids inside and increase the yield of elastomer particles having voids inside. Become.

The details of the elastomer, the poorly water-soluble organic solvent, and the polyvinyl alcohol having a saponification degree of 60 to 97 mol% used in the production method II are as described in the above production method I, and thus the description thereof will be omitted here.

In at least one of the elastomer solution and the water in which the saponification degree of polyvinyl alcohol of 60 to 97 mol% is dissolved, further, the saponification degree of polyvinyl alcohol of 20 to 59 mol% and the carboxy-modified polyvinyl acetate are added. It is preferable that at least one of them is dissolved. When polyvinyl alcohol with a saponification degree of 20 to 59 mol% and / or carboxy-modified polyvinyl acetate are used in combination, the aqueous phase inside the fine droplets is stabilized, and the internal aqueous phase when the poorly water-soluble organic solvent evaporates. Withdrawal is suppressed. As a result, when the latex is subjected to drying, the generation of elastomer particles having no voids inside is suppressed, so that the yield of elastomer particles having voids inside can be increased.

The details of the polyvinyl alcohol having a saponification degree of 20 to 59 mol% and the carboxy-modified polyvinyl acetate used in the production method II are as described in the above production method I, and thus the description thereof will be omitted here.

The HLB of the surfactant used in Production Method II is 8.0 or less, preferably 7.0 or less, more preferably 6.0 or less, and even more preferably 5.0 or less. If the HLB is greater than 8.0, it is difficult to form a stable W / O / W emulsion.

The details of the surfactant having an HLB of 8.0 or less are as described in the above-mentioned production method I, and thus the description thereof will be omitted here.

The elastomer solution used in Production Method II can be obtained by a step of producing an elastomer solution in which an elastomer and a surfactant having an HLB of 8.0 or less are dissolved in the water-soluble organic solvent to obtain an elastomer solution. The method for dissolving the elastomer and the surfactant in the poorly water-soluble organic solvent is not particularly limited. For example, if the poorly water-soluble organic solvent and the surfactant are stirred using a stirrer, the elastomer is added and further stirred. good.

In the production method II, the content of the elastomer in the elastomer solution is preferably 5 to 50 parts by mass, more preferably 10 to 40 parts by mass in 100 parts by mass of the elastomer solution. The content of the surfactant in the elastomer solution is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 5 parts by mass, out of 100 parts by mass of the elastomer solution.

The method for obtaining the dispersion liquid (a) in which the water (A) and the elastomer solution are mixed and stirred, and then the water (A) is finely dispersed in the elastomer solution is not particularly limited. For example, the dispersion liquid (a) can be obtained by putting water (A) and the elastomer solution in a reaction vessel and stirring them using a stirrer. At the time of stirring, the reaction vessel may be cooled in order to suppress the temperature rise due to shear heat generation. The number average particle size of the fine particle droplets in the dispersion liquid (a) is preferably adjusted to 7.0 μm or less by adjusting the rotation speed of the stirring device or the like. The cooling temperature at this time is not particularly limited, and examples thereof include 20 to 0 ° C., 10 to 0 ° C., and 4 to 0 ° C.

In the dispersion liquid (a), the content of water (A) is preferably 10 to 100 parts by mass, more preferably 10 to 50 parts by mass with respect to 100 parts by mass of the elastomer solution.

Water (B) in which polyvinyl alcohol having a saponification degree of 60 to 97 mol% is dissolved is added to the dispersion liquid (a) and stirred, and the dispersion liquid (a) is added to the water (B). The method for obtaining the finely dispersed dispersion liquid (b) is not particularly limited as long as the above elastomer solution can be finely dispersed in water (B) as fine droplets having an aqueous phase inside. For example, the water (B) may be added to the dispersion liquid (a) and stirred using a stirring device, or may be cooled during stirring in order to suppress a temperature rise due to shear heat generation. The number average particle size of the fine particle droplets in the dispersion liquid (b) is preferably adjusted to 10.0 μm or less by adjusting the rotation speed of the stirring device or the like.

In the production method II, one or more water-insoluble organic solvents in the dispersion liquid obtained by the above-mentioned steps, that is, one or more water-insoluble organic solvents in the dispersion liquid (b) are evaporated under normal pressure or reduced pressure. It is preferable to include a step (solvent evaporation step) of producing elastomer particles having an aqueous phase of. Since the details of the solvent evaporation step are as described in the above-mentioned production method I, the description thereof will be omitted here.

In the production method I and the production method II described in detail above, the aqueous phase inside the fine droplet is stabilized by using a specific surfactant, a specific water-soluble organic solvent, and a specific polyvinyl alcohol, and inside. It is possible to improve the yield of the elastomer particles having voids. The reason why the stabilization of the aqueous phase inside the fine droplets contributes to the improvement in yield is as described in the above-mentioned production method I.

<2. Latex>
The latex according to the embodiment of the present invention is a dispersion liquid (latex) obtained by the above-mentioned latex production method (production method I or production method II). The latex of the present embodiment is preferably a latex obtained through a solvent evaporation step after the sparingly water-soluble organic solvent has been evaporated.

The latex after the poorly water-soluble organic solvent is evaporated preferably contains elastomer particles having one or more aqueous phases inside and forming voids in the aqueous phases when dried, and a degree of saponification of 60. A latex containing water in which ~ 97 mol% of polyvinyl alcohol is dissolved. More preferably, the latex further contains a surfactant having an HLB of 8.0 or less. More preferably, the latex further contains at least one of polyvinyl alcohol having a saponification degree of 20 to 59 mol% and carboxy-modified polyvinyl acetate. In latex, there is an aqueous phase inside the elastomer particles that forms voids by drying.

Since the elastomer particles contained in the latex of the present embodiment have an aqueous phase in which voids are formed by drying and are composed of an elastomer which is a soft material, the basic characteristics of the void structure are It has a certain heat insulating property (low thermal conductivity) and flexibility which is a basic property of elastomers. Therefore, the latex of the present embodiment exhibits excellent heat insulating properties, breaking strength and breaking elongation when formed into a film.

Specifically, a cast film produced by using the latex of the present embodiment according to the following production conditions has a thermal conductivity of 0.100 W / mk or less, a breaking strength of 3.5 MPa or more, and a breaking elongation of 180%. That is all.
Production conditions:
The latex was poured onto a glass plate placed horizontally and dried at room temperature for 3 days to form a film film having a thickness of 0.5 mm, and then vacuum dried at room temperature for 1 day to evaporate moisture, and the length was 100 mm and the width was 50 mm. To make a cast film.

The thermal conductivity can be measured using a rapid thermal conductivity meter QTM-500 (manufactured by Kyoto Electronics Industry Co., Ltd.). Breaking strength and breaking elongation can be measured based on JIS K6251 of Japanese Industrial Standards.

The latex of the present embodiment can be used for applications such as water-based adhesives, water-based paints, water-based coating agents, and linings, but is suitable for applications of water-based adhesives and water-based paints. The method for producing a water-based adhesive and a water-based paint using the latex is not particularly limited as long as the latex is blended. That is, the water-based adhesive and the water-based paint using the latex can be produced according to a conventional method using a known machine or device.

<3. Elastomer particles>
The elastomer particles according to the embodiment of the present invention are elastomer particles having one or more voids inside. The elastomer particles of the present embodiment can be obtained by drying the latex after evaporating a poorly water-soluble organic solvent. The drying method is not particularly limited, and water may be evaporated by drying the latex under reduced pressure at room temperature.

The elastomer particles of the present embodiment have a number average particle diameter of preferably 0.05 to 10.0 μm, more preferably 0.1 to 5.0 μm. Further, the elastomer particles of the present embodiment have an internal void diameter of preferably 10 to 1000 nm, more preferably 50 to 500 nm. The number average particle diameter of the elastomer particles and the diameter of the voids can be measured by a transmission electron microscope.

The "number average particle diameter" referred to here is a value calculated by image analysis using a scanning electron microscope (SEM) photograph, and is an average value obtained by observing 100 particles. Microscopic observation can be performed, for example, by pretreating the particles to be measured and using, for example, a field emission scanning electron microscope (SU6600 / manufactured by Hitachi High-Technologies Corporation) at an acceleration voltage of 5 kV.

The pretreatment of the elastomer particles to be observed by SEM is as follows.
(I) Put 0.5 ml of pure water in a 6 ml screw tube bottle (manufactured by AS ONE), add 2 drops of an elastomer particle dispersion liquid with a dropper, and mix them.
(Ii) A drop of the liquid mixed in (i) is placed on the collodion film-attached mesh, and steam fixation is performed for 1 hour using a _{2% OsO 4 aqueous solution.}
(Iii) After air-drying at room temperature, OsO ₄ coat (coat thickness 7 nm) is applied.

Further, the diameter of the voids of the elastomer particles can be measured by scanning electron microscope (SEM) observation in the same manner as the above-mentioned number average particle diameter.

Hereinafter, the present invention will be described in more detail based on Examples. The examples described below show examples of typical examples of the present invention, and the present invention is not limited to the following examples.

[Example 1]
<Preparation of elastomer solution>
76 g of chloroprene monomer (20 ° C. specific gravity: 0.96, boiling point: 59 ° C.) and 24 g of chloroprene rubber (manufactured by Denka Co., Ltd., trade name: A-30) in which 4-tert-butylcatechol is added to a 200 mL glass bottle. And, and stirred at room temperature for 12 hours to dissolve the chloroprene rubber. The room temperature in this example is 20 ° C.

<Preparation of polyvinyl alcohol aqueous solution>
In a 200 mL beaker, 85 g of pure water and 15 g of polyvinyl alcohol (PVA) (manufactured by Kuraray Co., Ltd., trade name: PVA 3-88, degree of saponification: 88 mol%) are placed and stirred at 60 ° C. for 2 hours. Polyvinyl alcohol was dissolved.

<Preparation of dispersion liquid>
100 g of the above-mentioned elastomer solution and 100 g of a polyvinyl alcohol aqueous solution were placed in a beaker and stirred at 12000 rpm using a homogenizer AHG-160D (manufactured by AS ONE Co., Ltd.) while cooling in an ice bath to obtain a dispersion liquid.

<Solvent evaporation process (generation of elastomer particles)>
The dispersion was transferred to a 500 mL eggplant flask, an antifoaming agent was added, and the mixture was dried under reduced pressure at 35 ° C. and 60 mmhg for 30 minutes with an evaporator to evaporate the poorly water-soluble organic solvent. As a result, a dispersion liquid in which elastomer particles (chloroprene rubber fine particles) having an aqueous phase inside were dispersed in water was obtained.

<Making cast film>
A dispersion liquid in which elastomer particles are dispersed in water is poured onto a glass plate placed horizontally and dried at room temperature for 3 days to form a film film having a thickness of 0.5 mm, and then vacuum dried at room temperature for 1 day to evaporate water. Then, the film was formed into a length of 100 mm and a width of 50 mm to prepare a cast film.

[Example 2]
<Preparation of elastomer solution>
In a 200 mL glass bottle, 75 g of chloroprene monomer added with 4-tert-butylcatechol and 1 g of Span80 (Sorbitan Monooleart) (manufactured by NOF CORPORATION, trade name: Nonion OP-80R, HLB: 4.3). Was put in, sealed, and stirred at room temperature for 10 minutes. Then, 24 g of chloroprene rubber was added, and the mixture was stirred at room temperature for 12 hours to dissolve the chloroprene rubber.

Then, a polyvinyl alcohol aqueous solution was prepared in the same procedure as in Example 1, a dispersion liquid was obtained, and a solvent evaporation step was performed to prepare a cast film.

[Example 3]
In the preparation of the elastomer solution, except that Span85 (Sorbitan trioleate) (manufactured by NOF CORPORATION, trade name: Nonion OP-85R, HLB: 1.8) was used instead of Span80 (Sorbitan monooleart). A cast film was prepared in the same procedure as in Example 2.

[Example 4]
After preparing an elastomer solution and a polyvinyl alcohol aqueous solution in the same procedure as in Example 2, a dispersion liquid was prepared in the following procedure.

<Preparation of dispersion liquid>
(First dispersion liquid preparation process)
100 g of an elastomer solution and 25 g of pure water were placed in a 300 mL beaker and stirred with a homogenizer AHG-160D at 12000 rpm while cooling in an ice bath to prepare a dispersion liquid (a). The ice bath in this example is 0 ° C.
(Second dispersion liquid preparation process)
Next, 100 g of a polyvinyl alcohol aqueous solution was added to the dispersion liquid (a), and the mixture was stirred with a homogenizer AHG-160D at 12000 rpm while cooling in an ice bath to prepare a dispersion liquid (b).

Using the dispersion liquid (b), a cast film was prepared after performing a solvent evaporation step in the same procedure as in Example 1.

[Example 5]
In the preparation of the elastomer solution, the dispersion liquid (b) was obtained in the same procedure as in Example 4 except that Span85 (sorbitan trioleate) was used instead of Span80 (sorbitan monooleart), and the solvent evaporation step was performed. After that, a cast film was prepared.

[Example 6]
In the preparation of the polyvinyl alcohol aqueous solution, in addition to 85 g of pure water and 15 g of polyvinyl alcohol (PVA 3-88), polyvinyl alcohol (manufactured by Kuraray Co., Ltd., trade name: PVA LM-10, degree of saponification: 40 mol%) ) The dispersion liquid (b) was obtained in the same procedure as in Example 5 except that 2.5 g was used, and a solvent evaporation step was performed to prepare a cast film.

[Example 7]
In the preparation of the polyvinyl alcohol aqueous solution, in addition to 85 g of pure water and 15 g of polyvinyl alcohol (PVA 3-88), carboxylic acid-modified polyvinyl acetate (manufactured by Denka Co., Ltd., trade name: Denka ASR CH-09) 1 A dispersion liquid (b) was obtained in the same procedure as in Example 5 except that 0.0 g was used, and a solvent evaporation step was performed to prepare a cast film.

[Example 8]
In the preparation of the elastomer solution, except that glycerol monostearate (manufactured by Kao Corporation, trade name: Leodor MS-60, HLB: 3.5) was used instead of Span80 (sorbitan monooleate), as in Example 2. A cast film was prepared by the same procedure.

[Example 9]
In the preparation of the elastomer solution, except that Span20 (sorbitan monolaurate) (manufactured by NOF CORPORATION, trade name: Nonion LP-20R, HLB: 8.6) was used instead of Span80 (sorbitan monooleart). A cast film was produced in the same procedure as in Example 2.

[Example 10]
In the preparation of the polyvinyl alcohol aqueous solution, in addition to 85 g of pure water and 15 g of polyvinyl alcohol (PVA 3-88), polyvinyl alcohol (manufactured by Kuraray Co., Ltd., trade name: PVA LM-10, degree of saponification: 40 mol%) ) A cast film was prepared in the same procedure as in Example 1 except that 2.5 g was used.

[Example 11]
In the preparation of the polyvinyl alcohol aqueous solution, in addition to 85 g of pure water and 15 g of polyvinyl alcohol (PVA 3-88), carboxylic acid-modified polyvinyl acetate (manufactured by Denka Co., Ltd., trade name: Denka ASR CH-09) 1 A cast film was prepared in the same procedure as in Example 1 except that 0.0 g was used.

[Example 12]
In the preparation of the elastomer solution, methylene chloride (specific gravity at 20 ° C.: 1.33, boiling point: 40 ° C.) was used instead of the chloroprene monomer, and nitrile rubber (manufactured by Nippon Zeon Co., Ltd., trade name: Nipol1043) was used instead of the chloroprene rubber. A cast film was prepared in the same procedure as in Example 3 except that the above was used.

[Example 13]
In the preparation of the elastomer solution, the procedure was the same as in Example 1 except that a styrene-isoprene-styrene triblock copolymer (SIS) (manufactured by Nippon Zeon Corporation, trade name: Quintac3421) was used instead of the chloroprene rubber. A cast film was produced.

[Example 14]
In the preparation of the polyvinyl alcohol aqueous solution, in addition to 85 g of pure water and 15 g of polyvinyl alcohol (PVA 3-88), polyvinyl alcohol (manufactured by Kuraray Co., Ltd., trade name: PVA LM-10, degree of saponification: 40 mol%) ) A cast film was prepared in the same procedure as in Example 3 except that 2.5 g was used.

[Example 15]
In the preparation of the polyvinyl alcohol aqueous solution, in addition to 85 g of pure water and 15 g of polyvinyl alcohol (PVA 3-88), carboxylic acid-modified polyvinyl acetate (manufactured by Denka Co., Ltd., trade name: Denka ASR CH-09) 1 A cast film was prepared in the same procedure as in Example 3 except that 0.0 g was used.

[Comparative Example 1]
In the preparation of the polyvinyl alcohol aqueous solution, except that polyvinyl alcohol (manufactured by Kuraray Co., Ltd., trade name: PVA 3-98, degree of saponification: 98 mol%) was used instead of polyvinyl alcohol (PVA 3-88). A cast film was prepared in the same procedure as in Example 1.

[Comparative Example 2]
A cast film was prepared in the same procedure as in Example 1 except that an aqueous solution was prepared using Tween 20 (manufactured by NOF CORPORATION, trade name: Nonion LT-221, HLB: 16.7) instead of polyvinyl alcohol. ..

[Comparative Example 3]
Example 1 except that the amount of pure water was changed from 85 g to 96 g and 4 g of polyvinyl alcohol (PVA LM-10) was used instead of 15 g of polyvinyl alcohol (PVA 3-88) in the preparation of the polyvinyl alcohol aqueous solution. A cast film was prepared in the same procedure as above.

[Comparative Example 4]
In the preparation of the elastomer solution, cyclohexane (specific gravity at 20 ° C.: 0.78, boiling point: 81 ° C.) was used instead of chloroprene monomer, and ethylene-propylene-diene rubber (manufactured by Mitsui Chemicals, Inc., trade name) was used instead of chloroprene rubber. : A cast film was prepared in the same procedure as in Example 1 except that Mitsui EPT4045) was used.

[Comparative Example 5]
A cast film was prepared in the same procedure as in Example 1 except that toluene (specific gravity at 20 ° C.: 0.87, boiling point: 110 ° C.) was used instead of the chloroprene monomer in the preparation of the elastomer solution.

<Measurement of breaking strength and breaking elongation>
A tensile test was performed based on JIS K 6251, and the breaking strength (MPa) and breaking elongation (%) of the cast film were measured. The breaking strength was 3.5 MPa or more, and the breaking elongation was 180% or more.

<Measurement of thermal conductivity>
The thermal conductivity (W / mk) of the cast film was measured using a rapid thermal conductivity meter QTM-500 (manufactured by Kyoto Denshi Kogyo Co., Ltd.).

<Calculation of hollow particle ratio>
0.1 ml of the dispersion liquid obtained in the procedures of each Example and Comparative Example was added to 50 ml of pure water and dropped onto a collodion membrane-attached mesh for TEM. Thereafter, exposed to 30 minutes 2% OsO ₄ aqueous vapor at room temperature, air-dried, with a transmission microscope particles observations were performed. 200 particles in the image obtained by the transmission electron microscope were randomly selected, and the ratio was calculated by counting the particles having one or more voids.

The results of Examples and Comparative Examples are shown in Tables 1 to 3 below. In Tables 1 to 3, the blending amount of each component is the amount when the elastomer solution is 100 parts by mass, and the unit is "parts by mass".

In Examples 1 to 15, it was confirmed that the yield of the elastomer particles having one or more voids inside was high. Further, it was confirmed that the cast films of Examples 1 to 15 had low thermal conductivity and excellent heat insulating properties, and also had good breaking strength and breaking elongation. Specifically, the cast films of Examples 1 to 15 had a thermal conductivity of 0.100 W / mk or less, a breaking strength of 3.5 MPa or more, and a breaking elongation of 180% or more.
Further, when each of the elastomer particles of Examples 1 to 15 obtained in the <solvent evaporation step (generation of elastomer particles)> was measured with a transmission electron microscope, the number average particle diameter of these was 0.1 to 5. It was in the range of 0.0 μm, and the diameter of the voids inside them was in the range of 50 to 500 nm.

In Comparative Example 1 in which a polyvinyl alcohol having a degree of saponification of more than 97 mol% was used, Comparative Example 2 in which Tween 20 was used instead of polyvinyl alcohol, and Comparative Example 3 in which a polyvinyl alcohol having a degree of saponification of less than 60 mol% was used. It could not be emulsified stably and elastomer particles could not be produced. In Comparative Example 4 using a poorly water-soluble organic solvent having a specific gravity of less than 0.8 at 20 ° C. and Comparative Example 5 using a poorly water-soluble organic solvent having a boiling point of more than 95 ° C., an elastomer having one or more voids inside. The yield was extremely low.

Claims (14)

Water in which polyvinyl alcohol with a saponification degree of 60 to 97 mol% is dissolved, and
An elastomer solution in which an elastomer is dissolved in a poorly water-soluble organic solvent having a specific gravity of 0.8 or more and a boiling point of 95 ° C. or less at 20 ° C.
A method for producing latex, which comprises a step of mixing and stirring. The method for producing latex according to claim 1, wherein a surfactant having an HLB of 8.0 or less is dissolved in the poorly water-soluble organic solvent. water and,
An elastomer solution in which an elastomer and a surfactant having an HLB of 8.0 or less are dissolved in a poorly water-soluble organic solvent having a specific gravity of 0.8 or more and a boiling point of 95 ° C or less at 20 ° C.
After mixing and stirring
A method for producing latex, which comprises a step of adding water in which polyvinyl alcohol having a degree of saponification of 60 to 97 mol% is dissolved and stirring the mixture. The production of the latex according to claim 2 or 3, wherein the surfactant having an HLB of 8.0 or less is at least one selected from the group consisting of sorbitan monooleate, sorbitan trioleate and glycerol monostearate. Method. Of the polyvinyl alcohol having a saponification degree of 20 to 59 mol% and the carboxy-modified polyvinyl acetate in at least one of the elastomer solution and the water in which the polyvinyl alcohol having a saponification degree of 60 to 97 mol% is dissolved. The method for producing a latex according to any one of claims 1 to 4, wherein at least one of them is dissolved. The polyvinyl acetate is at least one selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, maleic acid monoester, fumaric acid monoester and itaconic acid monoester. The method for producing a latex according to claim 5, which is a copolymer of vinyl acetate. The method for producing latex according to any one of claims 1 to 6, wherein the elastomer is chloroprene rubber, nitrile rubber, or a styrene-based block copolymer. The method for producing latex according to claim 7, wherein the poorly water-soluble organic solvent is a halogen-based organic solvent. Elastomer particles that have one or more aqueous phases inside and that are dried to form voids.
Latex containing water in which polyvinyl alcohol having a saponification degree of 60 to 97 mol% is dissolved. The latex according to claim 9, which contains a surfactant having an HLB of 8.0 or less. The latex according to claim 9 or 10, which contains at least one of polyvinyl alcohol having a degree of saponification of 20 to 59 mol% and carboxy-modified polyvinyl acetate. Any one of claims 9 to 11, wherein the cast film produced according to the following production conditions has a thermal conductivity of 0.100 W / mk or less, a breaking strength of 3.5 MPa or more, and a breaking elongation of 180% or more. Latex described in.
Production conditions:
The latex was poured onto a glass plate placed horizontally and dried at room temperature for 3 days to form a film film having a thickness of 0.5 mm, and then vacuum dried at room temperature for 1 day to evaporate the moisture to 100 mm in length and 50 mm in width. Mold to make a cast film. The latex according to any one of claims 9 to 12, which is for a water-based adhesive or a water-based paint. A water-based adhesive or water-based paint using the latex according to any one of claims 9 to 13.