JPS586743B2 - Latex materials for blocks - 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 add an emulsifier and water to a rubber polymerization solution or a solution of solid rubber dissolved in a suitable solvent, and then emulsify the resulting emulsion. This is done by removing the solvent from the liquid 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 B is an inelastic block made of an aromatic vinyl compound, B is an elastic block made of a conjugated diene compound, and n is an integer of 2 or more.

).

Generally, the A block has a second order transition temperature of 25°C or less,
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. However, block copolymer latex has a wide range of applications such as rubber thread, carpet back sizing agent, paper processing agent, fiber processing agent, surface coating agent, adhesive, paint binder, latex-added asphalt, and cement compounding agent. When used for the above-mentioned purposes, it may have major drawbacks depending on the processing material.

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

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

) is called.

It is said that the MFT of normal latex shows a strong correlation with the second-order 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 higher than its second-order transition temperature, it will not exhibit its unique properties.

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 copolymer latex, but although it is effective for random copolymers, it is not effective for block copolymers. This is not necessarily a preferable method, as it is hardly expected to be effective, 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 it has the drawback that although the MFT is reduced, the strength of the film formed from the latex is significantly reduced.

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 drawback that it significantly reduces the mechanical stability of the latex when added, and also generates a large amount of precipitation and agglomerates.

Under these circumstances, the inventors of the present invention have conducted extensive research with the aim of solving the above-mentioned drawbacks of conventional methods, and as a result, they have developed a method of mixing block copolymer latex with an aqueous emulsion consisting of certain specific resins and solvents. The present inventors have discovered that a block copolymer latex with improved film-forming properties and high mechanical stability can be obtained by using the above composition, leading to the present invention.

That is, in the present invention, (a) a block copolymer latex 10 consisting of an aromatic vinyl compound and a conjugated diene compound;
0 parts by weight and (mouth) are an aqueous emulsion consisting of 10 to 100 parts by weight of an aromatic resin with a softening point of 50 to 150°C and 10 to 100 parts by weight of a hydrocarbon or halogenated hydrocarbon solvent with a boiling point of 50 to 150°C. , above (a) and (o
) A block copolymer latex composition with improved film-forming properties is provided.

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 ( However, A is an inelastic block made of an aromatic vinyl compound, B is an elastic block made of a conjugated diene compound, and n is an integer of 2 or more.

), the molecular weight is 10,000 to 500,000, and the content of component A is 10 to 70 with respect to the total polymer]
These percent block copolymers can be polymerized by living anionic polymerization with alkali metal-based initiators.

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.

Preferred examples of the conjugated diene compound forming the elastic block include 1,3-butadiene, Inglene, etc., which may be a homopolymer or a copolymer of two or more types; A random copolymer of a compound and an aromatic vinyl compound may also be used.

Such block copolymers can be produced by sequentially polymerizing monomers block by block in the presence of the initiator, or by simultaneously charging and polymerizing two or more monomers having different copolymerization reactivity ratios. The above-mentioned general formula A-B {
-B-A) The block copolymer represented by n is A-B
It can be obtained by coupling a living block copolymer ○ with a polyfunctional coupling agent. For example, when a tetrafunctional coupling agent such as tin tetrachloride is used, a block copolymer having the 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 properties of the thermoplastic elastomer 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 a 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 precipitate and coagulation occurs, resulting in extremely poor productivity and poor mechanical stability of the final product. Problems tend to arise and it is never easy.

As a method for producing a block copolymer latex which solves the above problems, there is Japanese Patent Application No. 49-92148 or 1982-4264, which precedes the present application.

Japanese Patent Application No. 49-92148 discloses that (a) a rosinate salt or a disproportionated stomate salt and (b) an HLB value of 1 are used as emulsifiers when producing a latex of a block copolymer.
The present invention is characterized in that a colloid mill type emulsifier is used as an emulsifier using a nonionic surfactant of 2 to 17, and the linear velocity of the rotor tip of the emulsifier is set to 2000 m/min or more.

Furthermore, Japanese Patent Application No. 50-4264 discloses that (1) a higher fatty acid selected from rosinates, dialkyl sulfosuccinates, alkylbenzene sulfonates, and mono- or dialkylnaphthalene sulfonates; 0.5 to 15 parts by weight of an anionic surfactant consisting of two or more types per 100 parts by weight of the polymer; (2) an ethylene oxide adduct of a phenol having two or more aromatic nuclei in at least two parts; 0 nonionic surfactant 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.

Examples of aromatic resins having a softening point of 50 to 150° C. constituting the aqueous emulsion that is the second component of the block copolymer latex composition of the present invention include the following.

Coumaron resin, indene resin, styrene resin, α-vinyltoluene resin, α-methylstyrene resin, coumaron-indene resin, coumaron-indene-styrene resin, coumaron-indene-inprene resin, styrene-α vinyltoluene resin, etc. blend. The softening point is 50 to 150°C, preferably 70 to 140°C.

If the temperature is less than 50°C, it has the effect of lowering the MFT, but it causes a significant decrease in the physical properties of the composition, especially the tensile strength. Not only is it difficult to create, but the effect of lowering the MFT is small and undesirable.

The proportion of the above-mentioned aromatic resin in the composition of the present invention is 10 to 100 parts by weight, preferably 15 to 75 parts by weight, based on 100 parts by weight of the block copolymer.

If it is less than 10 parts by weight, the effect is not sufficient, and if it exceeds 100 parts by weight, although the effect of improving film formability is sufficient, it weakens the properties of the thermoplastic elastomer of the film formed from the composition, making it undesirable. .

Examples of the solvent consisting of a hydrocarbon or logenated hydrocarbon having a boiling point of 50 to 150°C, which is the second component of the block copolymer latex composition of the present invention and is another component constituting the aqueous emulsion, include: The following solvents may be mentioned.

Hydrocarbons such as n-hexane, n-hebutane, n-octane, isooctane, neooctane, cyclohexane, methylcyclohexane, benzene, toluene, xylene, ethylbenzene, etc., and petroleum benzine, ligroin, gasoline, petroleum spirit, petroleum, and mixtures thereof. Nafta et al.

Chloroform, carbon tetrachloride, ethylene chloride, ethylidene chloride, 1,1,1-trichloroethane, 1,1,2-trichloroethane, 1,1,2-2-tetrachloroethane, ■,2-)chloroethane, trichlor Halogenated hydrocarbons such as ethylene, tetrachloroethylene, 2-dichloropropane, amyl chloride, chlorobenzene, ethylene bromide, chloromethane, ethylene chlorobromide, etc., and mixtures thereof.

Furthermore, mixtures of the above hydrocarbons and halogenated hydrocarbons.

The boiling point of these solvents is 50 to 150°C, preferably 75 to 145°C.

If the temperature is less than 50°C, the solvent will evaporate before the water when forming a film from the composition, resulting in no effect.
If the temperature exceeds .degree. C., conversely, evaporation is too slow and it takes more than 6 hours for the film formed from the composition to fully exhibit its properties as a thermoplastic elastomer, which is not preferable.

The amount of solvent used is 10 to 100 parts by weight, preferably 15 to 75 parts by weight, per 100 parts by weight of the block copolymer.
Parts by weight.

If it is less than 10 parts by weight, the effect of lowering MFT is not sufficient, and if it exceeds 100 parts by weight, the composition has characteristics that are in a latex emulsion state, such as being non-toxic, non-polluting, and non-hazardous. I don't like it because I don't want to lose it.

The above-mentioned aqueous emulsion containing a resin and a solvent as main components can be easily obtained by mixing and emulsifying a resin dissolved in a solvent with an emulsifier and water.

There is no need to limit the type of emulsifying machine used for emulsification, and any known emulsifying machine may be used as long as it has a sufficiently strong emulsifying ability.

Examples include homomixers, homogenizers, dispermil colloid mills, etc.

The emulsifier used for emulsification is not particularly limited, and various types of known emulsifiers can be used.

For example, rosin acid salts (including salts of disproportionated rosin acid and hydrogenated rosin acid), higher fatty acid salts, higher alcohol sulfate ester salts, higher alkyl ether sulfate ester salts, alkylbenzene sulfonates, mono- or dialkylnaphthalene sulfones. Anionic surfactants such as acid salts, dialkyl sulfoconocinates, various phosphate ester salts, cationic surfactants such as amine salt type or quaternary ammonium salt type, polyoxyethylene alkyl ethers, polyoxyethylene Examples include nonionic surfactants such as polyoxyethylene type surfactants such as alkylphenol ethers, polyoxyethylene alkyl esters, and polyoxyethylene alkylamines, and block type polyoxyethylene and polyoxypropylene types.

A particularly preferred emulsifier is the same emulsifier as that of the block copolymer latex.

For example, when mixing with the block copolymer latex obtained by the method of Japanese Patent Application No. 1983-92148 to obtain a block copolymer composition, an aqueous emulsion consisting of an aromatic resin and a solvent (a) rosin acid Preference is given to using salts or disproportionated sulfate salts and ib) nonionic surfactants with an HLB number of 12 to 17.

The block copolymer latex composition of the present invention has the above two
It consists of components and may be prepared by any conventionally known method.

The simplest method is to mix the two by stirring, and almost no precipitation or coagulation occurs during mixing.

After mixing, the mixture can be used for final use immediately, but if it is to be used particularly effectively, it is preferable to allow at least one hour of aging.

The block copolymer latex composition of the present invention can be applied to the wide range of uses mentioned above, but 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.

Particularly preferred dispersion stabilizers include
0-4264, using 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 No. 0-4264, based on 100 parts by weight of the polymer. .

General formula (1) (where 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 casting a film on a glass plate with a thickness of approximately 0.1 w/m.
It was determined according to the method of IS K-6310.

Reference Example 1 Thermoplastic elastic body made of styrene and putadiene block copolymer obtained by solution polymerization (Solprene T414) 1
2 parts by weight of disproportionated rosin acid and 4 parts by weight of polyoxine ethylene nonyl phenyl ether having an HLB value of 15.0 were dissolved in a 33 weight percent toluene solution containing 0.00 parts by weight, and this and disproportionated rosin were dissolved. Using a pressure pump, the acid and an aqueous solution containing equimolar amounts of sodium hydroxide were mixed at a weight ratio of 2:1, and the linear velocity at the tip was 250 per minute.
Emulsification was performed while continuously press-fitting into a colloid mill type emulsifier having a trapezoidal rotor rotating at 0 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 was 1200 seconds, and the MFT was not 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 kglcm2 and an elongation of 950%.

Reference Example 2 A 33 weight percent toluene solution containing 100 parts by weight of butadiene-styrene-butadiene-styrene block copolymer rubber (molecular weight 70,000, bound styrene content 40 weight percent}) was added with 2.5 parts by weight of disproportionated sulfate acid. and 2.5 parts by weight of polyoxyethylene nonyl phenyl ether with an oxyethylene polymerization degree of 15, and further 2.0 parts of a compound obtained by adding 100 parts by weight of ethylene oxide to 100 parts by weight of di(α-phenylethylphenol). This solution was mixed with an aqueous solution containing equimolar amounts of sodium hydroxide as disproportionated sulfuric acid in a weight ratio of 2:1, and mixed with a disper mill. Emulsified.

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

Reference example 3 Styrene resin with a softening point of 75°C (Picola Stake A-75
, manufactured by Esso Chemical Co., Ltd.) to 100 parts by weight of toluene.
2 parts by weight of disproportionated rosin acid, HL
Add 4 parts by weight of polyoxyethylene nonyl phenyl ether with a B number of 15, and mix this with water in which equimolar amounts of sodium hydroxide are dissolved, such as disproportionated rosin acid, etc., at a weight ratio of 2:
The mixture was emulsified in a homomixer at a ratio of 1:1 to obtain an aqueous emulsion.

This emulsion remained stable even after being left at room temperature for several tens of days under closed conditions without any separation of the components.

Example 1 The block copolymer latex obtained in Reference Example 1 was placed in a container so that 100 parts by weight of the copolymer component was contained in the latex, and the aqueous emulsion obtained in Reference Example 3 was added to the container with an aromatic resin. The solvents were gradually added to the emulsion in an amount of 50 parts by weight with stirring, and then aged for 2 hours to obtain a block copolymer latex.

The mechanical stability of this product was sufficiently stable for 1500 seconds, and the MFT was also below room temperature, forming a uniform transparent strong film at room temperature.

The tensile test result of this film showed that the maximum tensile strength was 178
The kg/cm2 elongation was 900%, and the film-forming property was significantly improved.

Example 2 The amount of aromatic resin and solvent added to the aqueous emulsion used in Example 1 was 20 parts by weight each in the emulsion.
A composition obtained in the same manner as in Example 1 was subjected to a test except that the amount contained was changed to 70 parts by weight.

For 20 parts by weight, mechanical stability is 1200 seconds, MFT
formed a nearly uniform, transparent, strong film at room temperature.

The maximum tensile strength of this film was 108 kg/cm 2 and the elongation was 950%.

For 70 parts by weight, mechanical stability is 1620 seconds, MFT
formed a uniform, transparent, strong film at room temperature or below.

The maximum tensile strength of this film was 58 kg/cm 2 and the elongation was 1000%.

Example 3 In place of the aqueous emulsion used in Example 1, an aromatic resin was used: Coumaron-indene-styrene resin with a softening point of 90°C (Nippon Steel Coumaron ND41/2, Nippon Steel Chemical Industry Co., Ltd.)
A block copolymer latex composition was prepared in the same manner as in Example 1, using an aqueous emulsion prepared in the same manner as in Reference Example 3 using n-octane as the solvent.

The mechanical stability of this product was 900 seconds, the MFT was below room temperature, and a uniform transparent strong film was formed at room temperature.

The maximum tensile strength of this film was 143 kg/cm2, and the elongation was 650%.

Example 4 A block copolymer latex composition was prepared in the same manner as in Example 1 except that the block copolymer latex obtained in Reference Example 2 was used instead of the block copolymer latex used in Example 1. .

The mechanical stability of this product was 1500 seconds, the MFT was below room temperature, and a uniform transparent strong film was created at room temperature.

The maximum tensile strength of this film was 75 kg/cm 2 and the elongation was 1100%.

Example 5 A composition was prepared in the same manner as in Example 4 except that the aqueous emulsion used in Example 3 was replaced with the aqueous emulsion used in Example 4.

The mechanical stability of this product was 1500 seconds, the MFT was below room temperature, and a uniform transparent strong film was formed at room temperature.

The maximum tensile strength of this film was 152 kg/cm 2 and the elongation was 600%.

Example 6 In place of the aqueous emulsion used in Example 4, styrene resin (Hymer) with a softening point of 100°C was used as the aromatic resin.
A composition was prepared in the same manner as in Example 4, using SU100 (manufactured by Sanyo Chemical Industries, Ltd.), xylene as the solvent, and an aqueous emulsion prepared in the same manner as in Reference Example 3.

The mechanical stability of this product was 1500 seconds, the MFT was below room temperature, and a uniform transparent strong film was formed at room temperature.

The maximum tensile strength of this film was 100 kg/cm 2 and the elongation was 800%.

Example 7 Only the amount of the aqueous emulsion used in Example 5 was
A composition was prepared in the same manner as in Example 5, except that the amounts of aromatic resin and solvent were changed to 30 parts by weight each in the emulsion.

The mechanical stability of this product was 960 seconds, the MFT was below room temperature, and a uniform transparent film was formed at room temperature.

The maximum tensile strength of this film was 136 kg/cm2, and the elongation was 850%.

Comparative Example 1 An aqueous emulsion containing only n-octane, toluene, and xylene was prepared by a method similar to Reference Example 3, and blocks were added to the latex of Reference Example 1 at a ratio of 50 parts by weight to 100 parts by weight of the block copolymer. A copolymer latex composition was prepared.

The mechanical stability of these solvents was extremely low at 120 seconds, 480 seconds, and 360 seconds, respectively, and a large amount of coagulum was generated during composition preparation.

In addition, all of these MFTs were at room temperature or below, but although the film formed at room temperature was transparent, it developed numerous cracks of various sizes, making it impossible to subject it to a tensile test.

Comparative Example 2 The aqueous emulsion obtained in Reference Example 3 was heated and the solvent toluene was removed by evaporation to create an aqueous emulsion containing only the aromatic resin Picolastake A-75.

A composition consisting of this material and a block copolymer latex (containing 50 parts by weight of aromatic resin per 100 parts by weight of the block copolymer).

Although the mechanical stability of ) was sufficiently stable for 1200 seconds, the MFT was 58° C., making it impossible to form a film at room temperature.

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 100 parts by weight of a block copolymer latex consisting of an aromatic vinyl compound and a conjugated diene compound, (
1) is an aqueous emulsion consisting of 10 to 100 parts by weight of an aromatic resin having a softening point of 50 to 150°C and 10 to 100 parts by weight of a hydrocarbon or logenated hydrocarbon solvent having a boiling point of 50 to 150°C; 1. A block copolymer latex composition with improved film-forming properties, characterized by comprising a mixture of (1) and (2).