WO2020111144A1

WO2020111144A1 - Method for producing latex, and latex

Info

Publication number: WO2020111144A1
Application number: PCT/JP2019/046431
Authority: WO
Inventors: 友貴坂井; 小林　直紀; 英博松田; 智加子斉藤
Original assignee: デンカ株式会社
Priority date: 2018-11-29
Filing date: 2019-11-27
Publication date: 2020-06-04
Also published as: JPWO2020111144A1

Abstract

A method for producing a latex that comprises a step wherein a water in which a polyvinyl alcohol having a saponification degree of 60-97% by mole is dissolved and an elastomer solution which is obtained by dissolving an elastomer into a poorly water-soluble organic solvent that has a specific gravity at 20°C of 0.8 or more and a boiling point of 95°C or less are mixed with each other and stirred.

Description

Method for producing latex and latex

The present invention relates to a latex manufacturing method and a latex. More specifically, a method for producing a latex having one or more water phases inside and producing an elastomer particle in which the water phase forms voids by drying, and one or more water phases inside And a latex containing elastomer particles whose aqueous phase forms voids upon drying.

Particles with voids inside have basic properties such as weight reduction (low specific gravity), heat insulation and sound insulation, and low dielectric loss, low electrical conduction, reflection/scattering abnormality, impact resistance, rigidity improvement, texture It is known that a unique property is also expressed from the viewpoint of application. For these reasons, particles having voids in the interior have hitherto been used in various molded articles, wallpaper, paints, building materials, sealing agents, adhesives, shoe soles, synthetic leather, tires, paper, cement, tiles, FRP, capacitors, etc. Is used in an extremely wide range of fields.

The particles having voids inside are, for example, hollow granules made of fine particle titanium oxide surface-treated with silicic acid anhydride (Patent Document 1). Also proposed are hollow silica-based fine particles (Patent Documents 2 and 3) and hollow particles of metal oxide produced by removing a polymer after forming a coating layer made of a metal oxide on the surface of spherical polymer fine particles. (Patent Document 4). Furthermore, hollow fine particles of fullerene-like boron nitride obtained by reacting carbon nanotubes with boron oxide at 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 a product field requiring flexibility.

Therefore, research is being conducted on a technology for producing particles that have flexibility inside a room temperature environment while having voids inside by using an elastomer. For example, there has been proposed a hollow microcapsule composed of a styrene-based thermoplastic elastomer containing a polystyrene block and a polyolefin block and having a porosity of 10 to 95% (Patent Document 6). Further, an elastomer particle having an glass transition point of −100 to 0° C. and having at least one void has been proposed (Patent Document 7).

JP, 2014-58441, A JP, 2013-121911, A JP, 2014-58683, A Japanese Patent Laid-Open No. 2000-34582 JP, 2001-294409, A JP, 2009-207973, A International Publication No. 2016/031845

Demand for elastomer particles with such properties is expected to grow, as they are expected to be used in fields other than conventional hollow particles that lack flexibility. 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 a latex, which has one or more water phases inside and can improve the yield of elastomer particles in which the water phase forms voids by drying. The main purpose is.

That is, the present invention is
Water in which polyvinyl alcohol having a saponification degree of 60 to 97 mol% is dissolved,
An elastomer solution in which an elastomer is dissolved in a poorly water-soluble organic solvent having a specific gravity at 20°C of 0.8 or more and a boiling point of 95°C or less,
There is provided a method for producing a latex, which comprises the step of mixing and stirring.
In the manufacturing method, a surfactant having an HLB of 8.0 or less may be dissolved in the poorly water-soluble organic solvent.
Further, the present invention is
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 at 20°C of 0.8 or more and a boiling point of 95°C or less,
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 saponification degree 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 polyvinyl alcohol having a saponification degree of 20 to 59 mol% and carboxy-modified polyvinyl acetate in at least one of the water in which the elastomer solution and the polyvinyl alcohol having a saponification degree of 60 to 97 mol% are dissolved. One kind 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 with vinyl acetate.
The elastomer may be chloroprene rubber, nitrile rubber, or styrene block copolymer.
The poorly water-soluble organic solvent may be a halogen-based organic solvent.

Further, the present invention is
Elastomer particles having one or more aqueous phases therein, and the aqueous phases forming voids when dried,
A latex containing water in which polyvinyl alcohol having a saponification degree of 60 to 97 mol% is dissolved is provided.
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.
A cast film produced using the above 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.
Manufacturing conditions:
The latex is poured on 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, 100 mm in length, 50 mm in width. And molded into a cast film.
The latex may be for water-based adhesives or water-based paints.
The present invention also provides a water-based adhesive or water-based coating material using the latex.

INDUSTRIAL APPLICABILITY According to the present invention, there can be provided a method for producing a latex that has one or more aqueous phases inside and can improve the yield of elastomer particles in which the aqueous phase forms voids when dried. ..

Hereinafter, modes for carrying out the present invention will be described. It should be noted that the embodiment described below is an example of the embodiment 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 production method>
A method for producing a latex according to an embodiment of the present invention is a method for producing a latex for producing an elastomer particle having one or more voids inside. Further, the method for producing a latex according to the present embodiment may also be a method for producing a latex containing elastomer particles having one or more water phases inside and drying the water phase to form voids. .. It should be noted that the elastomer particles having one or more water phase inside and forming a void in the water phase when dried have one water phase inside and are dried to have a water phase of 1 Both a mononuclear elastomer particle forming one void and a multi-hollow elastomer particle having a plurality of aqueous phases therein and the aqueous phase forming a plurality of voids when dried are included.

The manufacturing method of this embodiment is roughly classified into a manufacturing method I and a manufacturing method II described later. In order to produce elastomer particles in which the latex obtained from the production method I or the production method II has one or more water phases inside and the water phase forms voids when dried, the yield is high. 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 polyvinyl alcohol having a saponification degree of 60 to 97 mol% is dissolved, and a poorly water-soluble organic solvent having a specific gravity at 20°C of 0.8 or more and a boiling point of 95°C or less. Is a method for producing a latex, which comprises a step of mixing the above-mentioned elastomer solution and stirring.

The step of mixing and stirring the water and the elastomer solution is preferably mixing and stirring the water and the elastomer solution, and the elastomer solution in the water as fine droplets having an aqueous phase inside. This is a step of obtaining a finely dispersed dispersion liquid. The “fine 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 performing stirring as described above, but the following production method is preferable:
An elastomer solution preparation step of obtaining an elastomer solution by dissolving the elastomer in a poorly water-soluble organic solvent having a specific gravity at 20°C of 0.8 or more and a boiling point of 95°C or less;
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 dispersed in the above-mentioned water as fine droplets having an aqueous phase therein. A dispersion liquid preparation step of obtaining a dispersed dispersion liquid,
A method for producing a latex, comprising:

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 (W/O/W type emulsion) by using a specific polyvinyl alcohol and a specific poorly water-soluble organic solvent. It is possible to form a stable W/O/W type emulsion.

Details will be described later, but by evaporating the poorly water-soluble organic solvent contained in the dispersion, the fine droplets in the dispersion become elastomer particles. The stability of the internal aqueous phase is the “aqueous core” that forms the void structure when the aqueous phase (internal aqueous phase) inside the fine droplets is fixed inside the elastomer particles and then dried. Influences the yield of elastomer particles having voids inside. That is, by stabilizing the internal water phase, the separation of the internal water phase at the time of evaporation of the poorly water-soluble organic solvent is suppressed, as a result, the generation of elastomer particles having no voids when subjected to drying Since it is suppressed, it is possible to increase the yield of the elastomer particles having voids inside.

As the above 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 block copolymer.

“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, chloroprene and the like. Examples of the styrene block copolymer include styrene-isoprene-styrene triblock copolymer (SIS), styrene-butadiene-styrene triblock copolymer (SBS), styrene-ethylenebutylene-styrene triblock copolymer. (SEBS), styrene-ethylene propylene-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 block copolymer, and even more preferably chloroprene rubber. These elastomers may be used alone or in combination of two or more.

The water-insoluble organic solvent has a specific gravity at 20° C. of 0.8 or more, more preferably 0.9 or more, and its upper limit is not particularly limited, but preferably 1.8 or less, and preferably Is 1.6 or less. If the specific gravity at 20° C. is less than 0.8, the elastomer solution will float when the water in which the polyvinyl alcohol is dissolved and the elastomer solution are stirred, and the elastomer solution will be stably finely dispersed in water. Difficult to do.

The upper limit of the boiling point of the poorly water-soluble organic solvent is 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 producing elastomer particles from the latex obtained by the production method of the present embodiment, it is necessary to evaporate the poorly water-soluble organic solvent, but when the boiling point of the poorly water-soluble organic solvent is higher than 95° C., it is better than the poorly water-soluble organic solvent. 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 a chloroprene monomer (2-chloro-1,3-butadiene), a halogen-based organic solvent such as methylene chloride, chloroform and carbon tetrachloride, and benzene. At least one kind or two or more kinds selected from the group consisting of can be used.

The poorly water-soluble organic solvent having a specific gravity at 20° C. of 0.8 or more and a boiling point of 95° C. or less can be appropriately selected according to the type of elastomer.
Examples of the elastomer include chloroprene rubber (CR), styrene-butadiene rubber (SBR), acrylic rubber (ACM), styrene-butadiene-styrene triblock copolymer (SBS) and styrene-chloroprene-styrene triblock copolymer ( In at least one of SCS), the poorly water-soluble organic solvent is preferably a chloroprene monomer (2-chloro-1,3-butadiene), a halogen-based organic solvent such as 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 The 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 and carbon tetrachloride.
When the elastomer is, for example, butadiene rubber (BR), ethylene-propylene-diene rubber (EPDM), natural rubber (NR) and isoprene rubber (IR), the sparingly water-soluble organic solvent is preferably benzene.
From the viewpoint of improving the thermal conductivity of the obtained elastomer particles, the breaking strength and the breaking elongation, when using chloroprene rubber as the elastomer, nitrile rubber or a styrene block copolymer, the water-insoluble 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 an elastomer solution preparation step of dissolving the elastomer 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 may be, for example, room temperature, and more specifically, 5 to 40° C. or 10 to 30° C.

A polymerization terminator or the like may be appropriately added to the poorly water-soluble organic solvent or the elastomer solution in order to prevent the polymerization reaction from occurring. The type of the polymerization terminator is not particularly limited, and examples thereof include amine compounds such as phenothiazine and thiodiphenylamine; 4-tert-butylcatechol, 2,2′-methylene (bis-4-methyl-6-tert-butylphenol). 1) or 2 or more selected from the group consisting of phenolic compounds such as ). Of these, a phenolic compound is 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 and more preferably 10 to 40 parts by mass in 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 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 poorly water-soluble organic solvent having a specific gravity at 20° C. of 0.8 or more and a boiling point of 95° C. or less. Preferably.

The HLB of the above-mentioned surfactant is preferably 8.0 or less, more preferably 7.0 or less, further 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 liquid is further improved, and the internal aqueous phase is prevented from being desorbed during evaporation of the poorly water-soluble organic solvent. It is possible to further increase the yield of elastomer particles having voids.

The surfactant is not particularly limited, and examples thereof include sucrose fatty acid ester; sorbitan monostearate, sorbitan monopalmitate, sorbitan monobehenate, sorbitan monomontanate, and other sorbitan fatty acid ester surfactants; glycerin monolaurate. Rate, glycerin monopalmitate, glycerin monostearate, diglycerin distearate, triglycerin monostearate, glycerin fatty acid ester-based surfactants such as tetraglycerin monomontanate, and the like, selected from the group consisting of these. It is at least one kind.
Among the above-mentioned surfactants, nonionic surfactants are preferable.

The surfactant having an HLB of 8.0 or less is preferably sorbitan monopalmitate (Span 40, HLB: 6.7), sorbitan monostearate (Span 60, HLB: 4.7), sorbitan tristearate (Span 65, HLB: 2.1), sorbitan monooleate (Span80, HLB: 4.3), sorbitan sesquioaleate (Span83, HLB: 3.7), sorbitan trioleate (Span85, HLB: 1.8), and Sorbitan fatty acid ester system such as sorbitan isostearate (Span120, HLB: 4.7); glycerol monostearate (MS-60, HLB: 3.5), glycerol monostearate (MS-50, HLB: 2.8) ), glycerol monooleate (MO-60, HLB: 2.8), and other glycerin fatty acid ester-based compounds; and the like. Among these, more preferable is at least one selected from the group consisting of sorbitan monooleate, sorbitan trioleate and glycerol monostearate.

The surfactants may be used alone or in combination of two or more. When two or more kinds of surface active agents are used in combination, the term “surfactant having an HLB of 8.0 or less” means that the HLB of each surfactant is 8.0 or less. It does not mean that the average value of HLB 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 elastomer solution preparation step described above, the method of dissolving the surfactant in the poorly water-soluble organic solvent is not particularly limited, and for example, after stirring the poorly water-soluble organic solvent and the surfactant with a stirring device, the elastomer is added. And stir further.

The polyvinyl alcohol having a saponification degree of 60 to 97 mol% used in the production method I has a lower saponification degree of preferably 70 mol% or more, more preferably 75 mol% or more, still more preferably 80 mol% or more. is there. The upper limit of the saponification degree of the polyvinyl alcohol is preferably 95 mol% or less, more preferably 90 mol% or less. The 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, It cannot be stably emulsified, and it is difficult to stably finely disperse the elastomer solution in water.

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

At least one of the elastomer solution and water in which polyvinyl alcohol having a saponification degree of 60 to 97 mol% is dissolved, polyvinyl alcohol having a saponification degree of 20 to 59 mol% and carboxy-modified polyvinyl acetate are further 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 is used together, 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 suppressed more effectively. As a result, when the latex is dried, the generation of elastomer particles having no voids inside is suppressed, so that it is possible to increase the yield of elastomer particles having voids inside.

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

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

Carboxy-modified polyvinyl acetate is a copolymer of vinyl acetate and 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. Preferably. Examples of commercially available carboxy-modified polyvinyl acetate include DENKA ASR CH-09 (manufactured by DENKA CORPORATION). The carboxy-modified polyvinyl acetate may be used alone or in combination of two or more kinds.

The method 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 is It is not particularly limited. For example, water in which polyvinyl alcohol is dissolved and the 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 increase due to shearing heat generation. The cooling temperature at this time is not particularly limited, but examples thereof include 20 to 0° C., 10 to 0° C., and 4 to 0° C. The number average particle diameter of the fine droplets in the dispersion is preferably adjusted to 10.0 μm or less by adjusting the rotation speed of the stirring device.

In the dispersion liquid, 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, relative to 100 parts by mass of the elastomer solution. 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, based on 100 parts by mass of the elastomer solution. It is more preferably about 20 to 20 parts by mass. 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 parts by mass with respect to 100 parts by mass of the elastomer solution. Part by weight is preferred, 0.5 to 10 parts by weight is more preferred, and 0.5 to 5 parts by weight is even more preferred.

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

As described above, in the above 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 forming the fine droplets evaporates and disappears. As a result, the structure of the elastomer forming the fine droplets is fixed and the elastomer particles are generated. Further, by the immobilization, the aqueous phase (internal aqueous phase) inside the fine droplets is confined in the voids inside the elastomer particles. Then, the latex containing the elastomer particles is subjected to drying, whereby the aqueous phase remaining inside the elastomer particles is removed, and the portions where the aqueous phase is removed become voids. In this way, the internal aqueous phase is fixed inside the elastomer particles to form a void structure, and can therefore be said to be a “void nucleus”.

When the internal water phase is unstable, when the sparingly water-soluble organic solvent evaporates in the solvent evaporation process, the internal water phase separates from the fine droplets, and elastomer particles without void nuclei inside can be generated. Therefore, the yield of the elastomer particles having voids inside may decrease when the latex is dried. However, in the production method I, it is possible to stabilize the internal aqueous phase by using the specific poorly water-soluble organic solvent and the specific polyvinyl alcohol, so that the internal aqueous phase is prevented from being released and the internal aqueous phase is suppressed. Form stable void nuclei. As a result, generation of elastomer particles having no voids inside is suppressed, and the yield of elastomer particles having voids inside can be increased.

The above is a description of 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 poorly water-soluble organic solvent having a specific gravity of 0.8 or more at 20° C. and a boiling point of 95° C. or less. Is mixed and stirred, and then a method for producing a latex is provided, which comprises a step of adding water in which polyvinyl alcohol having a saponification degree of 60 to 97 mol% is dissolved and stirring.

The production method II is not particularly limited as long as it includes the above steps, but the following production method is preferable:
Water (A),
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 at 20°C of 0.8 or more and a boiling point of 95°C or less,
Are mixed and stirred to obtain a dispersion liquid (a) in which 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 (a) and stirred, and the dispersion (a) is added to the water (B). A method for producing a latex, which comprises a step of obtaining a finely dispersed dispersion liquid (b).

The above production method II is more preferably the following production method:
An elastomer solution preparation step of obtaining an elastomer solution by dissolving an elastomer and a surfactant having an HLB of 8.0 or less in a poorly water-soluble organic solvent;
A first dispersion liquid preparation step in which the elastomer solution and water (A) are mixed and stirred 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 liquid producing step for obtaining a finely dispersed dispersion liquid (b);
A method for producing a latex, comprising:

The above 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. The production method II uses a specific polyvinyl alcohol and a specific poorly water-soluble organic solvent to obtain an aqueous phase (internal aqueous phase) inside the fine droplets in the dispersion (b) (W/O/W type emulsion). 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, generation of elastomer particles having no voids inside can be suppressed, and the yield of elastomer particles having voids inside can be increased. Become.

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 the same as those described in the production method I, and therefore the description thereof is omitted here.

At least one of the elastomer solution and water in which polyvinyl alcohol having a saponification degree of 60 to 97 mol% is dissolved, polyvinyl alcohol having a saponification degree of 20 to 59 mol% and carboxy-modified polyvinyl acetate are further 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 is used in combination, the aqueous phase inside the fine droplets is stabilized and the internal water phase when the sparingly water-soluble organic solvent evaporates Withdrawal is suppressed. As a result, when the latex is dried, the generation of elastomer particles having no voids inside is suppressed, so that it is possible to increase the yield of elastomer particles having voids inside.

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 the same as those described in the production method I, and therefore the description thereof is 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 further preferably 5.0 or less. When the HLB is more than 8.0, it is difficult to form a stable W/O/W type emulsion.

The details of the surfactant having an HLB of 8.0 or less are the same as those described in the above manufacturing method I, and thus the description thereof is omitted here.

The elastomer solution used in the production method II can be obtained by an elastomer solution preparation step in which an elastomer and a surfactant having an HLB of 8.0 or less are dissolved in the poorly water-soluble organic solvent to obtain an elastomer solution. The method of dissolving the elastomer and the surfactant in the poorly water-soluble organic solvent is not particularly limited, for example, after stirring the poorly water-soluble organic solvent and the surfactant using a stirring device, if 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 and more preferably 10 to 40 parts by mass in 100 parts by mass of the elastomer solution. Further, 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.

The method of obtaining the dispersion liquid (a) in which the water (A) is finely dispersed in the elastomer solution after mixing and stirring the water (A) and the elastomer solution is not particularly limited. For example, the dispersion liquid (a) can be obtained by placing water (A) and the elastomer solution in a reaction container and stirring the mixture using a stirring device. At the time of stirring, the reaction vessel may be cooled in order to suppress the temperature increase due to shearing heat generation. The number average particle diameter of the fine droplets in the dispersion liquid (a) is preferably adjusted to 7.0 μm or less by adjusting the rotation speed of the stirring device. The cooling temperature at this time is not particularly limited, but 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, and 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 elastomer solution can be finely dispersed in water (B) as fine particle droplets having an aqueous phase therein. For example, the water (B) may be added to the dispersion liquid (a) and stirred using a stirrer, and cooling may be performed during stirring in order to suppress a temperature increase due to shear heat generation. The number average particle diameter of the fine droplets in the dispersion liquid (b) is preferably adjusted to 10.0 μm or less by adjusting the rotation speed of the stirring device.

Manufacturing method II is one in which at least one is obtained by evaporating the poorly water-soluble organic solvent in the dispersion obtained by the above-mentioned steps, that is, the poorly water-soluble organic solvent in the dispersion (b) under normal pressure or reduced pressure. It is preferable to include the step (solvent evaporation step) of producing the elastomer particles having the aqueous phase. The details of the solvent evaporation step are the same as those described in the above manufacturing method I, and thus the description thereof is omitted here.

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

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

The latex after the sparingly water-soluble organic solvent has been evaporated preferably has at least one aqueous phase therein, and has an saponification degree of 60 and the elastomer particles having the aqueous phase forming voids. And a water in which about 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 the latex, an aqueous phase that forms voids when dried exists inside the elastomer particles.

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

Specifically, the cast film produced according to the following production conditions using the latex of the present embodiment 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.
Manufacturing conditions:
The above latex 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, 100 mm in length, 50 mm in width. And molded into a cast film.

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

The latex of this embodiment can be used for applications such as water-based adhesives, water-based paints, water-based coating agents, and linings, but is suitable for water-based adhesives and water-based paints. The method for producing an aqueous adhesive and an aqueous paint using the above latex is not particularly limited as long as the above latex is blended. That is, the water-based adhesive and water-based coating material using the above latex can be manufactured by a conventional method using a known machine or device.

<3. Elastomer particles>
The elastomer particles according to one 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 the poorly water-soluble organic solvent. The method of drying is not particularly limited, and water may be evaporated by drying the latex under reduced pressure at room temperature.

The number average particle size of the elastomer particles of the present embodiment is preferably 0.05 to 10.0 μm, more preferably 0.1 to 5.0 μm. Further, in the elastomer particles of the present embodiment, the diameter of the voids inside is 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" here is a value calculated by image analysis using a scanning electron microscope (SEM) photograph, and is a value obtained by observing 100 particles and averaging them. Microscopic observation can be performed, for example, by pre-treating particles to be measured and using 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) 0.5 ml of pure water is put into a 6 ml screw tube bottle (manufactured by AS ONE), and 2 drops of the elastomer particle dispersion liquid is dropped therein with a dropper and mixed.
(Ii) One drop of the liquid mixed in (i) is placed on the collodion film-attached mesh, and vapor fixation is performed for 1 hour using a 2% OsO ₄ aqueous solution.
(Iii) After air-drying at room temperature, an OsO ₄ coat (coat thickness 7 nm) is applied.

Also, the diameter of the voids of the elastomer particles can be measured by observation with a scanning electron microscope (SEM), like the number average particle diameter described above.

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

[Example 1]
<Preparation of elastomer solution>
In a 200 mL glass bottle, 76 g of chloroprene monomer (specific gravity at 20° C.: 0.96, boiling point: 59° C.) to which 4-tert-butylcatechol was added, and 24 g of chloroprene rubber (manufactured by DENKA CORPORATION, trade name: A-30) And were added, and the mixture was 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, saponification degree: 88 mol%) were placed and stirred at 60° C. for 2 hours, Polyvinyl alcohol was dissolved.

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

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

<Production of cast film>
The dispersion in which the elastomer particles are dispersed in water is poured onto a horizontally placed glass plate 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, it was molded into a length of 100 mm and a width of 50 mm to produce 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, 1 g of Span80 (sorbitan monooleate) (NOF Corporation, trade name: Nonion OP-80R, HLB: 4.3), , Sealed and stirred at room temperature for 10 minutes. Then, 24 g of chloroprene rubber was added and stirred at room temperature for 12 hours to dissolve the chloroprene rubber.

After that, in the same procedure as in Example 1, an aqueous polyvinyl alcohol solution was prepared, a dispersion liquid was obtained, and a solvent evaporation step was performed, and then a cast film was prepared.

[Example 3]
In preparation of the elastomer solution, except that Span 80 (sorbitan monooleate) was replaced by Span 85 (sorbitan trioleate) (NOF Corporation, trade name: Nonion OP-85R, HLB: 1.8). A cast film was produced in the same procedure as in Example 2.

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

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

Using the above dispersion liquid (b), a solvent evaporation process was performed in the same procedure as in Example 1, and then a cast film was produced.

[Example 5]
In the preparation of the elastomer solution, a dispersion liquid (b) was obtained in the same procedure as in Example 4 except that Span 85 (sorbitan trioleate) was used instead of Span 80 (sorbitan monooleate), and the solvent evaporation step was performed. After that, a cast film was produced.

[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, saponification degree: 40 mol%) ) A 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, and then a cast film was produced.

[Example 7]
In the preparation of an aqueous polyvinyl alcohol 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 CORPORATION, trade name: DENKA ASR CH-09) 1 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 carried out to produce a cast film.

[Example 8]
Example 2 was repeated except that glycerol monostearate (manufactured by Kao Corporation, trade name: Rheodor MS-60, HLB: 3.5) was used in place of Span 80 (sorbitan monooleate) in the preparation of the elastomer solution. A cast film was produced by the same procedure.

[Example 9]
In the preparation of the elastomer solution, Span 20 (sorbitan monolaurate) (NOF Corporation, trade name: Nonion LP-20R, HLB: 8.6) was used instead of Span 80 (sorbitan monooleate). 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, saponification degree: 40 mol%) ) A cast film was produced in the same procedure as in Example 1 except that 2.5 g was used.

[Example 11]
In the preparation of an aqueous polyvinyl alcohol 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 CORPORATION, trade name: DENKA ASR CH-09) 1 A cast film was produced by 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 chloroprene rubber. A cast film was produced in the same procedure as in Example 3 except that was used.

[Example 13]
In the preparation of the elastomer solution, the same procedure as in Example 1 was performed except that styrene-isoprene-styrene triblock copolymer (SIS) (manufactured by Zeon Corporation, trade name: Quintac3421) was used instead of 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, saponification degree: 40 mol%) ) A cast film was produced in the same procedure as in Example 3 except that 2.5 g was used.

[Example 15]
In the preparation of an aqueous polyvinyl alcohol 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 CORPORATION, trade name: DENKA ASR CH-09) 1 A cast film was produced by 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, saponification degree: 98 mol%) was used instead of polyvinyl alcohol (PVA 3-88). A cast film was produced in the same procedure as in Example 1.

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

[Comparative Example 3]
Example 1 except that in the preparation of the polyvinyl alcohol aqueous solution, 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). A cast film was produced by the same procedure as in.

[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 the chloroprene monomer, and ethylene-propylene-diene rubber (trade name, manufactured by Mitsui Chemicals, Inc.) was used instead of chloroprene rubber. : A cast film was produced in the same procedure as in Example 1 except that Mitsui EPT4045) was used.

[Comparative Example 5]
In the production of the elastomer solution, a cast film was produced 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.

<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 Electronics Manufacturing Co., Ltd.).

<Calculation of hollow particle ratio>
0.1 ml of the dispersion liquid obtained by the procedure of each Example and Comparative Example was added to 50 ml of pure water, and the solution was dropped on the mesh for attaching a collodion film for TEM. Then, it was exposed to the vapor of 2% OsO ₄ aqueous solution for 30 minutes at room temperature, air-dried, and then the particles were observed with a transmission microscope. The ratio was calculated by randomly selecting 200 particles in the image obtained by a transmission electron microscope and 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 elastomer particles having one or more voids inside was high. It was also 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.
The number average particle diameter of these elastomer particles of Examples 1 to 15 obtained in the <solvent evaporation step (production of elastomer particles)> was 0.1 to 5 when measured with a transmission electron microscope. It was in the range of 0.0 μm and the diameter of the voids inside these was in the range of 50 to 500 nm.

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

Claims

Water in which polyvinyl alcohol having a saponification degree of 60 to 97 mol% is dissolved,
An elastomer solution in which an elastomer is dissolved in a poorly water-soluble organic solvent having a specific gravity at 20°C of 0.8 or more and a boiling point of 95°C or less,
A method for producing latex, which comprises the step of mixing and stirring.
The method for producing a 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 at 20°C of 0.8 or more and a boiling point of 95°C or less,
After mixing and stirring,
A method for producing a latex, which comprises a step of adding water in which polyvinyl alcohol having a saponification degree of 60 to 97 mol% is dissolved and stirring the mixture.
The production of a 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.
At least one of water in which the elastomer solution and the polyvinyl alcohol having a saponification degree of 60 to 97 mol% are dissolved in polyvinyl alcohol having a saponification degree of 20 to 59 mol% and carboxy-modified polyvinyl acetate The method for producing a latex according to any one of claims 1 to 4, wherein at least one kind 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 with vinyl acetate.
The method for producing a latex according to any one of claims 1 to 6, wherein the elastomer is chloroprene rubber, nitrile rubber or styrene block copolymer.
The method for producing a latex according to claim 7, wherein the poorly water-soluble organic solvent is a halogen-based organic solvent.
Elastomer particles having one or more aqueous phases therein, and the aqueous phases forming voids when dried,
A latex containing water in which polyvinyl alcohol having a saponification degree of 60 to 97 mol% is dissolved.
The latex according to claim 9, wherein the HLB contains a surfactant having a pH of 8.0 or less.
The latex according to claim 9 or 10, containing at least one of polyvinyl alcohol having a saponification degree of 20 to 59 mol% and carboxy-modified polyvinyl acetate.
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.
Manufacturing conditions:
The latex is poured on a glass plate placed horizontally and dried at room temperature for 3 days to form a film having a thickness of 0.5 mm, and then vacuum dried at room temperature for 1 day to evaporate the water content to 100 mm in length and 50 mm in width. Mold to form a cast film.
The latex according to any one of claims 9 to 12, which is for water-based adhesive or water-based paint.
A water-based adhesive or water-based coating material, which comprises the latex according to any one of claims 9 to 13.