JPS586744B2 - If you want to use the latest version of your computer, please use the latest latex software. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a block copolymer latex composition with improved film-forming properties.

Synthetic rubber latex is generally produced by emulsion polymerization and is widely used.

However, in recent years, with the rapid progress of polymerization technology, a large number of characteristic solution-polymerized synthetic rubbers have been produced, and attempts have been made to use these as latexes.

The general method for obtaining latex from this type of solution-polymerized synthetic rubber is to make a solution by dissolving a rubber polymerization solution or solid rubber in an appropriate solvent, add an emulsifier and water, and emulsify it. This is done by removing the solvent from the emulsion by stripping, flushing, distillation, or the like.

Furthermore, if the latex thus obtained is dilute, it is also known to concentrate it by operations such as creaming, centrifugation, evaporation, etc., if necessary.

One of the characteristic synthetic rubber latexes obtained by this method is an inelastic block (A) made of an aromatic vinyl compound.
There is a block copolymer latex in which elastomer blocks (B) consisting of a conjugated diene compound and a conjugated diene compound are alternately present.

This block copolymer has the general formula A-B-A (A-B)n B+(A-B)n (A-B)+nA or A-B{-B-A)n (where A is aromatic A non-elastic block made of a vinyl compound; B is an elastic block made of a conjugated diene compound;
n represents an integer of 2 or more.

).

Generally, the A block has a second order transition temperature of 25°C or higher,
In addition, B has a second-order transition temperature of 10°C or less and is called a thermoplastic elastomer, and it has high strength and elongation comparable to ordinary vulcanized rubber without undergoing the usual crosslinking treatment with sulfur compounds. This shows very low residual strain characteristics.

Latex made from such block copolymers has the above-mentioned unique properties and features that are in a latex state compared to conventional solvent-dissolved types, such as high solid content, relatively low viscosity, and quick drying. , water is a solvent, so it is not flammable or toxic, and it does not contain photochemically reactive substances and does not cause air pollution. , rubber thread carpet back sizing agents, paper processing agents, fiber processing agents, surface coating agents, adhesives, paint binders,
It has a wide range of applications, including latex-added asphalt and cement compounding agents.

However, when block copolymer latex is used for the above-mentioned purposes, it may have major drawbacks depending on the processing charges.

That is, if water does not evaporate at a temperature higher than a certain temperature during the process of forming a film from the block copolymer, a continuous and uniform film will not be formed.

Generally, the lowest temperature at which a continuous and uniform film is formed is referred to as minimum film forming temperature (hereinafter referred to as MFT).

) is called.

It is said that the MFT of normal latex shows a strong correlation with the secondary transition temperature of the polymer that is the main component, and even in the case of the block copolymer, it is usually difficult to form a film at around room temperature. Unless it is heat treated at a temperature above the next transition temperature, its unique properties will not be exhibited.

As methods for lowering MFT, methods such as internal plasticization, external plasticization, and temporary plasticization are known.

Among these methods, the internal plasticization method is based on changing the copolymerization ratio in the copolymer latex, but although it is effective for random copolymers, it is not effective for block copolymers. This is not necessarily a preferable method, since almost no effect can be expected and, furthermore, the unique properties of the block copolymer itself will change.

Next, the Sotomachi plasticization method is a known method in which a plasticizer such as dibutyl phthalate is added to latex, but although it reduces MFT, it has the drawback of significantly reducing the strength of the film formed from latex.

Furthermore, the temporary plasticization method involves adding solvents such as benzene, toluene, etc., which reduces MFT, and although the film formed from latex has sufficient physical properties, it requires the use of a relatively large amount. Moreover, it has the major disadvantage of significantly lowering the mechanical stability of latex when added, and also generating a large amount of precipitation and agglomerates.

The present inventors have conducted extensive research with the aim of improving the film-forming properties of block copolymer latex, and have found that by mixing a certain type of water-soluble dihydric alcohol derivative with the block copolymer, A block copolymer latex capable of lowering MFT without lowering physical stability was obtained.

That is, the present invention group (a) a block copolymer latex consisting of an aromatic vinyl compound and a conjugated diene compound; and (o)
Film formation consisting of a solvent whose main component is a water-soluble dihydric alcohol diester, diether or n-ester/ether derivative with a boiling point of 100 to 250°C, and an amount of 4 to 40 parts by weight per 100 parts by weight of the block copolymer. The present invention provides a block copolymer latex composition with improved properties.

The block copolymer used in the present invention has the general formula A-B-A (A-B)n B{-A-B)n (A-B)+nA or A-B+(B-A)n (but A is an inelastic block made of an aromatic vinyl compound, B is an elastic block made of a conjugated diene compound,
n represents an integer of 2 or more.

), and is a block copolymer having a molecular weight of 10,000 to 500,000 and a content of component A of 10 to 70% by weight based on the total polymer.

These can be polymerized by a living anionic polymerization method using an alkali metal-based initiator.

Preferred aromatic vinyl compounds forming the inelastic block include styrene, α-methylstyrene vinyltoluene, etc., and may be a homopolymer or a copolymer of two or more types.

Preferred examples of the conjugated diene compound forming the elastic block include 1.3-butadiene isoprene, which may be a homopolymer or a copolymer of two or more types; and an aromatic vinyl compound.

Such block copolymers can be produced by sequentially polymerizing one monomer block by block in the presence of the initiator, or by simultaneously charging and polymerizing two or more monomers having different copolymerization reactivity ratios. It can be obtained by a method of obtaining a living block copolymer or a method of coupling a living block copolymer using the above-mentioned initiator.

The block copolymer represented by the general formula A-B{-B-A)n can be obtained by coupling a living block copolymer of A-B○ with a polyfunctional coupling agent, For example, when a tetrafunctional coupling agent such as tin tetrachloride is used, a block copolymer having a structure is obtained.

The molecular weight of the block copolymer is 10,000 to 500
000, and if the molecular weight is less than 10,000, the mechanical strength of the film obtained from the latex will be poor;
If it exceeds 000, the viscosity of the solution becomes too high during emulsification, resulting in incomplete or difficult emulsification, which adversely affects the properties of the obtained latex.

Inelastic block portion in the block copolymer, that is, A
The content of the components can be selected within the range of 10 to 70% by weight based on the total polymer; anything outside this range is not preferred because the thermoplastic properties will be poor.

The block copolymer latex, which is the first component of the composition of the present invention, can be produced using the above-mentioned block copolymer by the general method of obtaining latex from the solution-polymerized synthetic rubber described above. When removing the solvent from the emulsion after emulsification and concentrating the obtained dilute latex, a large amount of precipitation and coagulation occurs, resulting in extremely poor productivity and poor mechanical stability of the final product. This is not an easy task as it tends to cause mesenchyma.

As a method for producing a block copolymer latex which solves the above problems, there is Japanese Patent Application No. 49-92148 or No. 50-4264 which precedes the present application.

Japanese Patent Application No. 49-92148 discloses that (a) a rosinate salt or a disproportionated rosinate salt and (b) H L B are used as emulsifiers when producing a latex of a block copolymer.
It is characterized in that a nonionic surfactant having a value of 12 to 17 is used, a colloid mill type emulsifier is used as the emulsifier, and the linear velocity of the rotor tip of the emulsifier is set to 2000 m/min or more. .

Furthermore, Japanese Patent Application No. 1983-4264 discloses that (1) a compound selected from higher fatty acids, rhodinates, dialkyl sulfosuccinates, alkylbenzenesulfonates, and mono- or dialkylnaphthalene sulfonates is used as an emulsifier when producing a polymer latex. 0.5 to 1 anionic surfactant consisting of one or more types per 100 parts by weight of the polymer
(2) 0.5 parts by weight of a nonionic surfactant consisting of ethylene oxide/adduct of a phenol having at least one part thereof two or more aromatic nuclei per 100 parts by weight of the polymer.
It is characterized by using 5 to 15 parts by weight.

The block copolymer latex, which is the first component of the composition of the present invention, may be produced by any method, but it must be a latex with excellent mechanical stability obtained by the above method etc. is preferred.

The second component of the block copolymer latex composition of the present invention has water solubility and has a boiling point of 100 to 250°C.
Diester/dietherester/ether derivatives of alcohols are those that are freely mixed with water at room temperature or dissolve in water at 2.0% by weight, preferably 5.0% by weight or more, and have a boiling point of 100% by weight or more.
The temperature is from 125 to 230°C, preferably from 125 to 230°C.

If the water solubility is less than 2.0% by weight in water, the mechanical stability will be significantly reduced, and if the boiling point is less than 100°C, the M
FT improvement is not sufficient, and temperatures exceeding 250°C are undesirable because it takes several days for the solvent to evaporate during film formation.

Examples of the above derivatives include the following.

Diether derivatives such as ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, propylene glycol diethyl ether, diglopylene glycol dimethyl ether, and mixtures thereof.

Diester derivatives such as ethylene glycol diacetate, ethylene glycol formate diester, diethylene glycol diacetate, and mixtures thereof.

Ester/ether derivatives such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether 7 cetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, and mixtures thereof.

The solvent, which is the second component of the present invention, is mainly composed of the above-mentioned derivatives, and may be used alone or as a mixture.
Furthermore, it may contain other solvents, such as solvents consisting of hydrocarbons with a boiling point of 50 to 150°C, but at least two of them may be included.
It is necessary that at least 5 weight percent consists of the above derivatives.

The amount of the solvent is 4 to 40 parts by weight, preferably 10 to 30 parts by weight, based on 100 parts by weight of the block copolymer.

If it is less than 4 parts by weight, the improvement in MFT will not be sufficient;
If the amount exceeds 1 part by weight, the mechanical stability will decrease, and it will take time for the solvent to evaporate after film formation.Also, the latex emulsion form is non-toxic and non-polluting. This is undesirable because it loses its features such as not being a dangerous substance.

The block copolymer latex composition of the present invention can be easily obtained by mixing the above-mentioned two components constituting the composition, and can be used for final use immediately after mixing, but it can be used particularly effectively. If this is the case, it is preferable to allow one hour or more of aging time.

The block copolymer latex composition of the present invention can be applied to the wide range of uses mentioned above, but depending on its use, it can also be used in combination with natural rubber latex or other synthetic rubber latex.

It can also be used in combination with emulsions or aqueous solutions of plastics such as urethane resins, acrylic resins, epoxy resins, vinyl acetate resins, and ethylene-vinyl acetate copolymer resins.

A thickener can also be added to the block copolymer latex composition of the present invention to increase the viscosity.

As the thickener, methylcellulose, carboxymethylcellulose, hydroxymethylcellulose, casein, polyvinyl alcohol, polyacrylic acid or its derivatives, sodium salt or ammonium salt of polyacrylic acid, etc. can be used.

A filler in the block copolymer latex composition of the present invention,
Compounding agents such as anti-aging agents, colorants, and dispersion stabilizers may also be added as necessary.

Examples of fillers include inorganic fillers such as aluminum carbonate, clay, talc, hydrated silicic acid, anhydrous silicic acid, magnesia, zinc white, carbon black, and barium sulfate.

As the anti-aging agent, those generally used in the rubber industry are suitable, and an ultraviolet inhibitor may also be included.

Furthermore, as for the coloring agent, inorganic and organic coloring agents may be used as necessary.

Examples of dispersion stabilizers include the following, which are commonly known as dispersion stabilizers for latex compounding.

Naphthalene sulfonate, condensed alkylnaphthalene sulfonate, condensed naphthalene sulfonic acid, potassium oleate, oleyl sulfate, polyoxyethylene alkyl allyl ether, polyacrylic acid polymer surfactant,
Alkyl ether type nonionic surfactant, polyoxyethylene, polyoxypropylene type surfactant.

A particularly preferred dispersion stabilizer is
The method is to use 0.2 to 15 parts by weight of a compound obtained by adding ethylene oxide to an aldehyde condensate of phenols represented by the general formula (1) described in 0-4264, based on 100 parts by weight of the polymer. .

General Meat (1) (However, R1 is an aryl group, an aralkyl group, or an alkyl group having 8 to 18 carbon atoms, R2 is hydrogen or an alkyl group having 8 or less carbon atoms, and n and m are integers of 1 to 3. When m+n is 5 or less and n or m is 2 or more, R1 or R2 may be different from each other.

) The present invention will be explained in more detail with reference to the following Reference Examples, Examples, and Comparative Examples, but the contents of the present invention are not limited thereto.

The mechanical stability, MFT, maximum tensile strength and elongation of the composition were measured as follows.

That is, mechanical stability was determined by the method of JISK-6381.

MFT was measured using a thermal gradient tester.

The maximum tensile strength and elongation were determined by JIS after one day of forming a film with a thickness of approximately 0.1%, which was created by casting on a glass plate.
It was determined according to the method of K-6310.

Reference example 1 Thermoplastic elastic body made of styrene-butadiene block copolymer obtained by solution polymerization (Solprene T414) 1
2 parts by weight of disproportionated rosin acid and 4 parts by weight of polyoxyethylene nonyl phenyl ether having an HLB value of 150 were dissolved in a 33% by weight toluene solution containing 00 parts by weight, and this and disproportionated rosin acid were dissolved. A pressure pump was used to prepare an aqueous solution containing equimolar sodium hydroxide at a weight ratio of 2:1, and the linear velocity at the tip was 2500 per minute.
Emulsification was carried out by continuously press-fitting the mixture into a colloid mill type emulsifier having a trapezoidal rotor rotating at m.m.

The produced emulsion containing toluene was immediately sent to a toluene removal tank equipped with a heating jacket, and the toluene was evaporated off by heating.

At this time, some of the water evaporates together with toluene, resulting in a solid content of 50
．． A 6 weight percent block copolymer latex was obtained.

The mechanical stability of this product is 1200 seconds, and the MFT
No film was formed at room temperature at 65°C.

The film was formed at 100° C., and the tensile test results showed a maximum tensile strength of 184 kg/cm 2 and an elongation of 950%.

Reference Example 2 2.5 parts by weight of disproportionated sulfate acid was added to a 33 weight percent gg luene solution containing 100 parts by weight of butadiene-styrene-butadiene-styrene block copolymer rubber (molecular weight 70,000, bound styrene content 40 weight percent). and 2.5 parts by weight of polyoxyethylene nonyl phenyl ether with an oxyethylene polymerization degree of 15, and further 2.0 parts by weight of a compound obtained by adding 100 parts by weight of ethylene oxide to parts by weight of di(α-phenylethyl)phenol. This solution was mixed with an aqueous solution containing sodium hydroxide in an equimolar amount to the disproportionated rosin acid at a weight ratio of 2:1, and emulsified using a disper mill.

The toluene in the produced emulsion was removed by evaporation, and the solid content was reduced to 53.
A 2 weight percent block copolymer lux was obtained.

The mechanical stability of this product is over 1800 seconds, and M
FT was 67°C and no film was formed at room temperature.

Furthermore, a film is formed at 100℃ and has a maximum tensile strength of 163kg/c.
m2, and elongation was 1100%.

Example 1 10 parts by weight of diethylene glycol dimethyl ether was mixed with 100 parts by weight of the block copolymer into the block copolymer latex obtained in Reference Example 1, and the mixture was aged for 3 hours to obtain a block copolymer latex composition. Ta.

The mechanical stability of this composition was 1200 seconds, with almost no decrease in mechanical stability observed.

In addition, MFT forms a uniformly transparent strong film at room temperature or below, with a maximum tensile strength of 153 kg/cm2 and an elongation of 8.
00%, and had significantly improved film formability.

Example 2 Bronok copolymer latex compositions obtained in the same manner as in Example 1 except that diethylene glycol dimethyl ether used in Example 1 was replaced with the above-mentioned solvents in different amounts were evaluated.

The results are shown in Table 1.

Comparative Example 1 A block copolymer latex obtained in the same manner as in Example 1 except that diethylene glycol dimethyl ether used in Example 1 was replaced with the above solvent in different amounts was evaluated.

The results are shown in Table 1. Reduced mechanical stability or MFT
No improvement effect was observed and good results were not obtained.

Example 3 Various blocks were prepared in the same manner as in Example 2 except that the block copolymer latex obtained in Reference Example 2 was used in place of the block copolymer latex obtained in Reference Example 1 used in Example 2. Table 2 shows the results of analysis and evaluation of the copolymer latex composition obtained.

Comparative Example 2 In addition to the block copolymer latex obtained in Reference Example 2 used in Comparative Example 1, the block copolymer latex obtained in Reference Example 2 was used, and various blocks were prepared in the same manner as in Comparative Example 1. A copolymer latex was obtained and the results of analysis and evaluation are shown in Table 2.

As is clear from the above reference examples, examples, and comparative examples, the block copolymer latex composition of the present invention has sufficient mechanical stability, has an MFT of less than room temperature, and is uniformly transparent at room temperature. It formed a film and exhibited the high strength and elongation that are characteristic of thermoplastic elastic materials without any heat treatment or other treatments.

Claims (1)

[Claims] 1 (a) is a block copolymer latex consisting of an aromatic vinyl compound and a conjugated diene compound, and (a) is a water-soluble dihydric alcohol diester, diether, or ester/ether derivative with a boiling point of 100 to 250°C as the main component. 100 parts by weight of the above (a);
(0) A block copolymer latex composition with improved film-forming properties, characterized in that it contains 4 to 40 parts by weight.