JPS5852311A - Emulsion polymerization of styrene - Google Patents

Abstract

PURPOSE:To conduct emulsion polymerization smoothly without troubles such as formation of coarse particles and gelation, by employing a specified modified polyvinyl alcohol having hydrophobic groups and hydrophilic groups in emulsion- polymerizing styrene. CONSTITUTION:A copolymer is prepared which contains, as essential copolymer components, the following three components: (A) a monomer selected from the group consisting of a vinyl ester of a C5 or higher fatty acid, a vinyl ether of a C4 or higher alkyl group, a C6 or higher alpha-olefin, (B) an ethylenically unsaturated carboxylic acid (derivative) and (C) vinyl acetate. Then, this copolymer is saponified into a modified polyvinyl alcohol satisfying relationshipsIand II, wherein A, B and C are copolymerization ratios of components A, B and C, respectively, n >=4, l is the number of carboxyl groups in component B and DELTA is the saponification degree of component C. Then, styrene is emulsion-polymerized in the presence of the modified polyvinyl alcohol.

Description

Detailed Description of the Invention The present invention relates to a specific modified polyvinyl alcohol (hereinafter referred to as polyvinyl alcohol (PvA)) having a hydrophobic group and a hydrophilic group.
This invention relates to a method for carrying out styrene l-emulsion polymerization in the presence of

Conventionally, when emulsion polymerizing styrene.

It is known that low-molecular-weight surfactants such as alkylbenzene sulfonates, alkylnaphthalene sulfonates, higher fatty acid salts, and disproportionated rosin salts are used singly or in mixtures as emulsion polymerization stabilizers. When using the emulsion obtained by a method using a low-molecular surfactant as a paint, adhesive xtJ as a paper processing agent, etc., coarse particles are generated when urea resin, pigment, etc. are added. ■
Due to its poor mechanical stability, it has drawbacks such as cohesive failure of the emuldiene when transferred by a pump or applied by a spreader roll, so extreme care must be taken when handling it.O When used as an adhesive: Low-molecular surfactant power: It has the disadvantage that it migrates to the surface of the film and tends to cause poor adhesion. In order to solve this problem, it has been proposed to use water-soluble polymer tubes such as PVA. PVA is useful as an emulsion polymerization stabilizer for vinyl acetate ester, and the vinyl acetate polymer emuldiene obtained using PVA as an emulsion polymerization stabilizer has various stability properties such as mechanical stability and freeze-thaw stability, and is used as adhesive paint. It is often used as such.

However, even if emulsion polymerization of styrene is attempted using PVAt as a stabilizer, the polymerization progresses extremely slowly, and smooth polymerization cannot be achieved, as coarse particles are generated during polymerization or the entire product gels.

Emulsion polymerization using a combination of a low-molecular-weight surfactant and PVA is possible, but it has been difficult to solve problems such as poor adhesion due to the migration of the low-molecular-weight surfactant to the surface of the film.

However, the inventors of the present invention have conducted intensive research with the aim of eliminating the above-mentioned drawbacks by using an emulsion polymerization method using only 1% modified PVA.

Vinyl esters of fatty acids with 5 or more carbon atoms, vinyl ethers of alkyl groups with 4 or more carbon atoms, and 6 carbon atoms
At least one of nine monomers selected from the group consisting of the above α-olefins, (B) at least one of edelenic unsaturated carboxylic acid or its lower alkyl ester or acid anhydride, and q vinyl acetate ester. A specific modified PV which is a saponified product of a nine copolymer obtained by combining co-X as an essential component and satisfies the following formula (1)
It was discovered that when emulsion polymerization of styrene is carried out in the presence of A, the polymerization proceeds in the middle, and an emulsion polymer can be obtained without any problems such as generation of coarse particles or gelation. This led to the completion of the invention.

0.2<I)<10 (1)B However, A is the copolymerization ratio (on a molar basis) of component (5), and the mol fraction is o, o o o s or more, and B is the copolymerization ratio of component (B). Polymerization ratio (mole basis) and mole fraction is 0.001
that's all.

C is the copolymerization ratio (molar basis) of component (C), and the mole fraction is 05 or more, and n is an integer of 4 or more. ．． H
When the component is an alkyl vinyl ether, the number of n-furkyl groups, when the four components are α to olefin, the number of carbon atoms in the n-α-olefin is CB) d) The number of carboxyl groups in the d portion, △
Hie) shows the saponification cracking of the components.

In the present invention, vinyl esters of fatty acids having 5 or more carbon atoms used as component (8) include, for example, vinyl valerate, vinyl caprate, vinyl myristate, vinyl stearate, and especially vinyl pivalate. ester, 1,
Fatty acid vinyl esters having a branched alkyl group, such as 1,3,3-tetramethylbutyric acid vinyl ester or saturated branched fatty acid vinyl esters having an average carbon number of 10, are preferred. If the number of carbon atoms is 4 or less, it is difficult for emulsion polymerization to proceed smoothly. Examples of alkyl vinyl ethers having 4 or more carbon atoms include butyl vinyl ether, octyl vinyl ether, lauryl vinyl ether, and the like. Among them, vinyl ethers having a drum-shaped alkyl group such as in-amyl vinyl ether are preferred. If the number of carbon atoms is 3 or less, it is difficult for the emulsion to polymerize smoothly. In addition, α-olefins having 6 or more carbon atoms include hebutene-1, octene-1, dodecene-1,
1 etc. are suitable. If the number of carbon atoms is 5 or less, smooth emulsion polymerization cannot be carried out and it cannot be applied. As the alkyl group having 4 or more carbon atoms, a branched alkyl group is more preferably used since a good emulsion polymer can be obtained. The reason for this is not clear, but the ratio of methyl group, methylene group, and methane/group in the alkyl group is different between branched alkyl groups and linear alkyl groups, and there are differences in crystallinity, orientation, association, etc. Furthermore, (B)
As the ethylenically unsaturated carboxylic acid or its lower alkyl ester or acid anhydride used as a component, acrylic acid and methacrylic acid are used.

Crotonic acid, maleic acid, itaconic acid, acrylic acid ester, methacrylic acid methyl ester.

Crotonic acid methyl ester, citraco/acid, citonic acid monomethyl ester, maleic acid diethyl ester, itaconic acid dimethyl ester, maleic anhydride, aconitic acid, etc. are used, and cytodiconic acid, maleic acid, etc.
．． (Taconic acid, maleic acid monomethyl ester, and maleic anhydride are preferably used, but maleic acid, maleic anhydride, maleic acid monomethyl ester, and itaconic acid are more preferable because of their greater stability of emulsion polymers.) The reason for this is not clear, but it is thought that the polymerizability with components (C) and ^, the mutual positional relationship of the introduced carboxyl groups, etc. influence the performance of modified PVA.

Modified PVAFi used in the present invention The fA described above
), (B) and FC+ contained in a copolymer obtained by copolymerization with three components as essential components (5) (uniform 1c)
The copolymerization ratio of the three components and the saponification ratio of the acetyl group of component (C) are selected from within the range of formula (1) below.

0.2<D<10 (1) D: n people + (1-ΔC27,5 8 However, A: ^ component copolymerization ratio (molar basis), mole fraction of 0.0005 or more B;...) component The copolymerization ratio (on a molar basis) of component (C) is 0.001 or more in terms of mole fraction;
．． 5 or more n: a number of 4 or more ■ (5) When the component is a vinyl ester of a fatty acid, n - the number of carbon atoms in the fatty acid - 1 ■ (^ When the component is an alkyl vinyl ether, n = number of alkyl groups In the case of α-olefin, n = number of carbon atoms in α-olefin −2, number of carboxyl groups in component (B) Δ; saponification ratio (on a molar basis) of component (C)
1) When modified PvAt beyond the range of the formula is used, the emulsion polymerization of Sti μ/ may not proceed smoothly, or even if the polymerization is somehow possible, the stability of the obtained emulsion polymer is poor. It has the following drawbacks. This does not satisfy the purpose of the present invention. The reason is denatured PV
This is thought to be because the balance between the hydrophobicity mainly based on the component (C) and the unsaponified component (C) and the hydrophilicity mainly based on the component (B) is lost due to the presence of AK, and emulsion dispersion stability can no longer be maintained.

Furthermore, the present invention uses modified PVA that satisfies the above-mentioned formula (1).
Emulsion polymerization can be carried out effectively only by using PVA, and the total modified PVA t is
When set to -1, the ^ component is ViO, 0O05, ■)
If the component is less than 0.001, it is no longer possible to carry out smooth emulsion polymerization or to obtain a stable emulsion polymerization. In addition, when the amount of zero component is 0.5 or less, the modified PVA no longer has the strong film-forming properties inherent to PVA, and the obtained emulsion polymer has a decrease in practical physical properties such as adhesive performance. The modified PVA used in the present invention is a saponified copolymer containing the three components mentioned above as essential components, but within the range that does not impair the purpose of the present invention. Other copolymerization components such as methacrylamide, N-substituted methacrylamide, acrylamide, N-substituted acrylamide, N-vinylpyrrolidone, vinyl ether of an alkyl group having 3 or less carbon atoms, and solute fluorine having PI number of 5 or less can also be used. The above (5
), (B), and (C), there is no problem in using a saponified copolymer of the copolymer. There are particularly difficult points in producing the modified PVA used in the present invention. Instead, conventionally known polymerization methods and saponification methods can be applied. That is, as a single polymerization method, (5)
, (B) and zero component gold are added to the polymerization system all at once, in parts, or continuously according to the respective copolymerization reactivity ratios, and then added to the polymerization system without a solvent or in an aqueous medium or with a lower alcohol such as methyl alcohol or ethyl alcohol. A method of polymerization using a radical polymerization catalyst such as 2,2'-azobisopteronitrile or benzoyl peroxide in the coexistence of is applicable. As a method for saponifying the thus obtained copolymer containing components (A), (B) and C), many known methods used for saponifying polyvinyl acetate copolymers can be applied. 1. Usually, a suitable method is saponification in an alcoholic solvent or a hydrous alcoholic solvent by the action of an alkali such as sodium alcoholade, caustic soda, or caustic potash. As the alcohol, lower alcohols such as Fi, methyl alcohol, and ethyl alcohol are particularly suitable. In addition, these alcohol solvents are
It may contain a solvent with a low electric potential such as acetone, methyl acetate, ethyl acetate, and benzene in an amount of 0 weight or less.

The degree of polymerization of the modified PVA used in the present invention should be appropriately selected depending on its intended use.

Normally, a suitable value is within the range of 100 to 3000.0 Using the modified PVA obtained above alone as a stabilizer, emulsion polymerization of styrene is carried out in the aqueous phase in the presence of an initiator by a known method to obtain good emulsification. A polymer is obtained. Emulsion polymerization Kl contains dienes and acrylic esters as minor components.
, methacrylic acid ester I1. vinyl chloride acrylic acid,
It is also possible to copolymerize acrylic acid, itaconic acid, and the like.

In this invention, the use of a low-molecular active agent in combination is not an essential condition, but it may be used in combination as an auxiliary means, for example, to adjust the particle size.In addition, in some cases, other protective colloids, such as unmodified PVA, may be used in combination. , polyacrylic acid, polymethacrylic acid and their salts polyvinyl alkyl ether.

Copolymers of vinyl acetate and acrylic acid, tfcFi, methacrylic acid, copolymers of vinyl acetate and maleic anhydride, and saponified products thereof, lower alkyl vinyl ether-ruic anhydride copolymers, cellulose in alkali, Hydroxyalkylcellulose.

alkylhydroxyalkylcellulose, carboxy)
cellulose VS conductor such as cellulose.

Alkyl starch, carboxymethyl starch, acid starch, gum arabic, gum tragacanth, polyalkylene glycol, etc. can be added during polymerization or after polymerization. In addition, liquid regulators used in ordinary emulsion polymerization, monohydric or polyhydric alcohols,
Additives such as plasticizers, inorganic salts such as sodium chloride, sodium iodide, sodium phosphate, and sodium sulfate, conditioners such as ammonia, sodium hydroxide, and hydrochloric acid, and antifoaming agents during or after polymerization. There is no problem with using them together.

The modified PVA used in the present invention is used in an amount of 0.5 to 40% by weight, preferably 2 to 25% by weight, based on the styrene monomer.

The polymerization initiator used in this invention is a water-soluble initiator system used in conventional emulsion polymerization, such as hydrogen peroxide alone or hydrogen peroxide and an oxycarboxylic acid such as tartaric acid, citric acid, ascorbic acid, or oxalic acid.

Combinations with sulfinic acids and their salts, oxidialdehydes, water-soluble iron salts, etc., persulfates, percarbonates, perborates, peroxides, etc. can be applied.

In general, the object of the present invention can be fully achieved by using the above-mentioned modified PVA until the emulsion polymerization is completed.

The emulsion polymerization emulsion obtained in this way shows excellent stability and has an appropriate viscosity, and is effective for adhesives, adhesives, fiber processing agents, paper processing agents, and even cement mixtures. Therefore, the industrial value is truly great.Next, the present invention will be explained in more detail with reference to Example 1. In the Examples, "part" and "饅" are based on weight unless otherwise specified.

Example 1 (8) 2-uryl vinyl ether I O,94 as component
μ% iB) A polyvinyl acetate copolymer containing 2.4 moles of crotonic acid as a component, in which 98.5 moles of the vinyl acetate component of the copolymer is saponified and 4 moles of crotonic acid at 20°C. 0 parts of modified PVAl with an aqueous solution viscosity of 49 centiboise, 3 m of ammonia water made of 1.0 parts of disodium phosphate, and 260 parts of water were dissolved under an atmosphere of chitun gas and kept at 60°C. 150 parts of styrene was added. After stirring for a minute, 5 parts of an aqueous solution of ammonium persulfate was poured into the mixture to obtain a clean emulsion free of coarse particles with an average particle size of 0.2 μm. The polymerization rate of styrene was 98%. This product was completely stable even if left for three months. Furthermore, the f-type PVAFiD used in this example
= 4.2 fS.

Comparative Example 1 0.04 mol% of lauryl vinyl ether as the component (5), 15 mol of crotonic acid as the Bl component, and 98.2 mol of the vinyl acetate component was saponified, D = 0.036 Emulsion polymerization of styrene was attempted in the same manner as in Example 1, except that modified PVA of 1 was used.The polymerization rate of styrene was 9.0%, and the polymerization rate was extremely slow, and smooth polymerization did not proceed.

Oka, the viscosity of a 4% aqueous solution of modified PVA at 20°C is 4.
I got a 3cm bois.

Comparative Example 2 Vinyl of an alkyl group having 3 carbon atoms as a quaternary component: r--
f lef h le/lumalpropylene vinyl ether 4
．． 3 mol - 1.2 maleic anhydride as component (B)
Mol-containing vinyl acetate ester of vinyl acetate copolymer S + 090, D = where 1 mol- is saponified
Example 1 except that modified PvA with a viscosity of 5.52 cm and a 4s aqueous solution having a viscosity of 19 cm at 20°C was used.
When emulsion polymerization was attempted in the same manner as above, the polymerization rate of styrene reached 89.2% after 1.5 hours, but coarse particles were generated and the result was not a good emulsion polymer.

Example 2 (5) Average charcoal as a component: Saturated orobranched fatty acid vinyl ester with Aa of 1O (Shell Co., Ltd. H, VeoVa-10)
D = 1.2 mol %, (97.5 mol % of the vinyl acetate portion of the vinyl acetate copolymer containing Itacon #3.0 mol as the Bl component is saponified). Emulsion polymerization of styrene was carried out in the same manner as in Example 1, except that modified PVA having a viscosity of 42 and a 41G water bath solution having a viscosity of 8 centivoids at 20°C was used. The particle size was 98.8 cm, the average particle size was 0.15 μm, and there were no #!Higashi particles at all.This product was completely stable even after being left for 6 months.

Comparative Example 3 Saturated branched fat dl with an average carbon number of 10 as component (A)
A vinyl acetate-based copolymer containing 1.2 mol of VeoVa-IQ but not containing the same amount of component (B), in which 82 moles of the beer acetate portion of the copolymer is An attempt was made to use modified PVA with saponified mole as an emulsion polymerization stabilizer, but the modified PV
Since A did not dissolve at all in either cold water or hot water, it could not be used as the intended stabilizer for emulsion polymerization of styrene.

Comparative Example 4 Component (5) does not contain any components. First, component (B) is a vinyl acetate copolymer containing 3.2 mol of maleic anhydride, and 88.2 mol of the vinyl acetate ester portion of the copolymer is used.
Emulsion polymerization of styrene was carried out in the same manner as in Example 1, except that modified PVA, in which the mulch had been saponified and whose aqueous solution viscosity at 20°C had a viscosity of 15.2 cm, was used as the emulsion polymerization stabilizer. However, the polymerization rate of styrene after 1 and 5 hours was 2.0-, meaning that almost no polymerization occurred.

Example 3 Contains 1.0 mol of saturated branched fatty acid vinyl ester (V@oVa-10) with an average carbon number of 10 as a prison component,
(B) 9 of the vinyl acetate ester portion of the vinyl acetate copolymer containing 3.1 moles of itaconic acid as the component.
9.0 molti was saponified. D = 1.47 and the viscosity of the aqueous solution at 20°C is 11 - 0 parts of modified PVAl of antibodies is heated and dissolved in 200 parts of water, cooled, and then dissolved with 1.5 parts of potassium permate and ethylenediaminetetraacetic acid. (E
Add and dissolve 0.1 part of DTA). Thereafter, 90 parts of styrene and 60 parts of butadiene were added, and the mixture was kept at 60'C for 12 hours with stirring, then cooled and the contents were taken out.

The reaction rate was 98.5-, and the latex was clean with no agglomeration and had an average particle size of 0.2 microns. This product remained stable without aggregation or thickening even when left at room temperature for 6 months.

This latex was heated at 30℃ using a B-type precision needle.
The viscosity measured in ptn was 8900 tnb and gave a clear film.

Example 4 98.8 mol of the vinyl acetate ester portion of a vinyl acetate copolymer containing 1.3 mol of lauryl vinyl ether as the component (A) and 3.0 mol of itaconic acid as the component (B) It has been saponified.

Emulsion polymerization of styrene-butadiene was carried out in the same manner as in Example 3, except that modified PVA with D = 2.61 and a 4% aqueous solution having a viscosity of 13 cm at 20°C was used as the emulsion polymerization stabilizer. Obtained. This product remained stable without aggregation or thickening even when left at room temperature for 6 months.

This latex was measured at 30°C using a B-type viscometer for 10
The viscosity measured at rpm was 3200 centivoise and gave a slightly cloudy coating.

Comparative Example 5 Contains 20 mol of heptene as component (A), (B)
Croton as an ingredient! Modified PVA1 with D=25.0 where 90 moles of the vinyl acetate ester part of the vinyl acetate copolymer containing 't4 moles has been saponified.
An attempt was made to emulsion polymerize styrene-butadiene in the same manner as in Example 3 except that it was used as an emulsion polymerization stabilizer, but coarse particles were generated and smooth emulsion polymerization could not be carried out.

Patent applicant Kurashi Co., Ltd. Representative Patent Attorney Sei Honda

Claims (1)

[Scope of Claims] (1) A large polymer selected from the group consisting of vinyl esters of fatty acids having 5 or more carbon atoms, vinyl ethers of alkyl groups having 4 or more carbon atoms, and α-olefins having 6 or more carbon atoms. At least one type of. ■) At least -IF and Hc of ethylenically unsaturated carboxylic acid or its lower alkyl ester or acid anhydride
c> A method of emulsion polymerizing Sten/ in the presence of modified polyvinyl alcohol which is a saponified product of a copolymer containing three components of vinyl acetate as essential copolymerization components and which satisfies the following formula (1). 0, 2 < D < 10 (1) B However, A is the copolymerization ratio (molar basis) of the Al component,
0.0005 or more in mole fraction, B is the copolymerization ratio (molar basis) of component (B) and 0.001 or more in 1 mole fraction,
CVi is the copolymerization ratio (on a molar basis) of the (C) component, which is a mole fraction of 0.5 or more, n Fi is an integer of 4 or more when the four components are vinyl esters of fatty acids. Number of carbon atoms in n-fatty acid is -1, when the 4th component is rubinyl ether in alcohol, n = number of alkyl groups, (7! When the component is α-olefin, n2 is the prime number of the leg of α-olefin – 2, l is (B)
The number of carboxyl groups in the component, △ indicates the saponification ratio (mole group) of component C) in the copolymer. The method for emulsion polymerization of styrene according to claim (1), wherein the branched fatty acid vinyl ester is present at the - position and the component (B) is an ethylenically unsaturated dicarboxylic acid or its lower alkyl ester or acid anhydride. (8) Claim (2) in which the component is itaconic acid
) A method for emulsion polymerization of styrene as described in .