JPS5865702A - Emulsion polymerization of (meth)acrylate ester - Google Patents

Abstract

PURPOSE:To obtain a stable emulsion polymer without suffering difficulties such as formation of coarse particles or gelation, by emulsion-polymerizing a (meth)acrylate ester in the presence of a modified polyvinyl alcohol which is a saponificate of a copolymer of a specified composition. CONSTITUTION:A copolymer is prepared from (A) a monomer selected from the group consisting of a vinyl ester of a 5C or higher fatty acid, a vinyl ether of a 4C or higher alkyl group and a 6C or higher alpha-olefin, (B) an ethylenically unsaturated carboxylic acid, its lower alkyl ester or its anhydride, and (C) a vinyl acetate ester. Then, this copolymer is saponified to obtain a polyvinyl alcohol satisfying formulasIand 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 defined by formula III. A (meth)acrylate ester is emulsion-polymerized in the presence of the above sponificate.

Description

Detailed Description of the Invention The present invention relates to a specific modified polyvinyl alcohol (hereinafter referred to as polyvinyl alcohol) having a hydrophobic group and a hydrophilic group.
It is abbreviated as ) as a stabilizer for emulsion polymerization of acrylic esters and methacrylic esters (hereinafter collectively referred to as (meth)acrylic esters).

Conventionally, alkylbenzenesulfone 11tj! has been used as a stabilizer for emulsion polymerization of (meth)acrylic acid esters. It is known that low-molecular surfactants such as lunaphthalene sulfonate in alcohol, higher fatty acid salt, polyoxyethylene alkyl ether, and sodium alkyl sulfosuccinate are used. However, when the emulsion obtained by such a method using a low-molecular-weight surfactant is used as a paint, adhesive, paper processing agent, etc., coarse particles are generated when urea resin or pigment is added.■ Mechanical stability It has disadvantages such as cohesive failure of the emulsion when it is transferred by a small pump or applied with a Nupretsudar roll, so it must be handled with great care when used as an adhesive. Sometimes, low-molecular-weight surfactants migrate to the surface of the film, resulting in poor adhesion. It has been proposed to use a water-soluble polymer such as KPVA to solve this problem. PVA is useful as an emulsion polymerization stabilizer for vinyl acetate ester. Vinyl acetate polymer emulsions obtained using PVA as an emulsion polymerization stabilizer have various stability properties such as mechanical stability and freeze-thaw stability, and can be used in adhesives and paints. It is often used as such.

However, when emulsion polymerization of (meth)acrylic acid esters is attempted using PVA as a stabilizer, a good emulsion cannot be obtained, as coarse particles are generated during polymerization, or in extreme cases, the entire gelation occurs. be. Emulsion polymerization using a combination of a low-molecular-weight surfactant and PVA is possible, but the above-mentioned difficulties such as the need for adhesion due to the transfer of the low-molecular-weight surfactant to the surface of the film cannot be overcome.

However, the present inventors have conducted extensive research with the aim of eliminating the above-mentioned drawbacks by using an emulsion polymerization method using a specific modified PVA alone.

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 large monomer selected from the above α-olefins, at least one homoethylenically unsaturated carboxylic acid or its lower alkyl ester or acid anhydride, and 0 vinyl acetate are essential. A specific modified PVA which is a saponified product of a copolymer obtained by copolymerization as a component and satisfies the following formula (1)
It was discovered that when emulsion polymerization of (meth)acrylic acid esters is carried out in the presence of an emulsion polymer, an emulsion polymer can be obtained without any difficulties such as generation of coarse particles or gelation. It is the turtle that arrived.

Margin below is 0.0! $<Dri4 (1)B However, the copolymerization ratio (on a molar basis) of the AFi (A) component is o, ooos or more in mole fraction, and B is the copolymerization ratio (on a molar basis) of the component <8). Yes, the mole fraction is 0.001 or more.

C is the polymerization ratio (molar basis) of component C) and the molar fraction is 0.5 or more, and n is an integer of 4 or more. (5) When the component is a vinyl ester of fatty acid, n = fatty acid. Carbon number -1
．． When the inner component is an alkyl vinyl ether, the number of carbon atoms in the n-alkyl group, when the ^ component is an α-olefin, n = the number of carbon atoms in the a-olefin - 2, the number of carboxyl groups in the IFi (E) component, Δ is ( C) Component Hydrocarbon group of a specific size introduced as a component in this way (introduced as a component and a sil group in 9 carboxylic acids, and as a component 0 and introduced as a large vinyl ester and/or its saponified large group) It is surprising that emulsion polymerization can be carried out stably only when the components (6), (B), and (C) satisfy a specific relationship. ) and 0, which is unimaginable from the combination.

In the present invention, vinyl esters of fatty acids having 5 or more carbon atoms to be used as component (5) include, for example, vinyl ester, vinyl capric acid, vinyl myristate, vinyl stearate, etc. Hybaric acid vinyl ester%
1.1.3.3 Fatty acid vinyl esters having a branched alkyl group, such as tetramethylbutyric acid vinyl ester or saturated branched fatty acid vinyl esters having an average carbon number of 10, are suitable. When the number of carbon atoms is 4 or less, it is difficult to obtain an emulsion polymer with good stability. Also, as the vinyl ether of alkyl having 4 or more carbon atoms, there is butyl vinyl ether.

Octyl vinyl ether b5')') Rubinyl ether, etc. Among these, vinyl ethers having a branched alkyl group such as in-amyl vinyl ether are preferred.

If the number of carbon atoms is 3 or less, it is difficult to obtain an emulsion polymer with good stability. Also, the number of carbon atoms is 6 or more. Dodecene-1 etc. are suitable. If the number of carbon atoms is 5 or less, emulsion polymerization will proceed stably. If the above-mentioned alkyl group having 4 or more carbon atoms is a branched alkyl group, a good emulsion polymer will be obtained. It is more suitable for use. The reason for this is not clear, but it is due to the fact that the ratio of methyl, methylene, and methine groups in the alkyl group is different between branched and straight-chain alkyl groups, and differences in crystallinity, orientation, association, etc. It is thought that they may do so.

Furthermore, the ethylenically unsaturated carboxylic acid or its lower alkyl ester or acid anhydride used as component (B) is acrylic acid or methacrylic acid.

Crotonic acid, maleic acid, itaconic acid, acrylic acid ethyl ester, methacrylic acid methyl ester, crotonic acid methyl ester, citraconic acid, citraconic acid diethyl ester, maleic acid, maleic acid monomethyl ester, maleic acid diethyl ester, itaconic acid dimethyl ester, Maleic anhydride, aconitic acid, etc. are used, but citraconic acid, maleic acid, i/)ic acid, -v
Ray 7g1l 7 methyl ester and maleic anhydride are preferably used, but maleic acid, maleic anhydride, maleic acid monomethyl ester, and itaconic acid are more suitable because they provide greater stability of the emulsion polymer. The reason for this is not clear, but it is thought that the polymerizability with components (C) and (5) and the mutual positional relationship of the introduced carboxyl groups may have an impact on the performance of modified PVA.

The modified PVAFi used in the present invention was described above (~
(A) (B) (C) contained in a copolymer obtained by copolymerization with the three components , (B) and 0 as essential components.
The copolymerization ratio of the three components and the saponification ratio of the acetyl group of the zero component are selected from within the range of the following formula (1).

0.05<D<4 (1) However, Ai (A) is the copolymerization ratio (on a molar basis) of the component, and the mole fraction is 0.0005 or more. Mole fraction of 0.001 or more C; copolymerization ratio of component (C) (mole basis) mole fraction of 0
．． 5 or more n, 4 or more ■ (5) When the component is a vinyl ester of a fatty acid, n = number of carbon atoms in the fatty acid - 1 ■ (A) When the component is an α-olefin, n - the number of carbon atoms in the α-olefin. 2 7; (B) Number of carboxyl groups in component Δ; G) The saponification ratio (mole basis) of component exceeds the range of formula (1) above. When using modified PVA, emulsion polymerization proceeds smoothly. Even if the polymerization is somehow successful, the resulting emulsion polymer has the disadvantage of poor stability, and thus does not satisfy the purpose of the present invention. The reason for this is that the balance between the hydrophobicity mainly based on the ^ component and the unsaponified (q component) and the hydrophilicity mainly based on the same component is disrupted in modified PvAKTo, making it impossible to maintain emulsion and dispersion stability. Conceivable.

Furthermore, the present invention uses modified PVA that satisfies the above-mentioned formula (1).
Emulsion polymerization can be carried out effectively only by using %(5) component, which is less than 0.0005 when the entire modified Pvm is 1 based on 1 mole.
If the O content is less than 0.001, smooth emulsion polymerization or stable emulsion polymerization will no longer be possible.
If the 19C) component is less than 0.5, the modified PVA will no longer have the strong film-forming properties inherent in PVA, and the obtained round-pore polymer will not be suitable for practical applications such as adhesive performance. The modified PVA used in the present invention is a saponified product of a copolymer containing the three components (iB) and (C) as essential components, as described above, but it does not meet the objectives of the present invention. Other copolymerized components within the range that does not cause damage.

For example, methacrylamide, N-substituted methacrylamide, acrylamide, N-substituted acryland.

N-vinylpyrrolidone, vinyl ether of an alkyl group having 3 or less carbon atoms, olefin having 5 or less carbon atoms, etc. are also copolymerized in addition to the above three components (5), Φ), and (C). There is no problem in using a saponified copolymer.

There are no difficulties in producing the modified PVA used in the present invention, and conventionally known polymerization methods and saponification methods can be applied. That is, as a single polymerization method, (5)
, ω) and C) are added to a combined system all at once, in parts, or continuously depending on their respective copolymerization reactivity ratios, and mixed with methyl alcohol, ethyl alcohol, etc. without a solvent or in an aqueous medium. A method of polymerization using a radical polymerization catalyst such as 2,2'-azobisisobutyronitrile or benzoyl peroxide in the coexistence of a lower alcohol can be applied. As a method for saponifying the copolymer containing components (8), (B) and C) obtained in this way, many known methods used for saponification of polyvinyl acetate copolymers can be applied. 1. Usually, saponification is carried out by using an alkali such as sodium alcoholade, caustic soda, or caustic potash in an alcoholic solvent or a hydrous alcoholic solvent. As the alcohol, lower alcohols such as methyl alcohol and ethyl alcohol are particularly suitable. In addition, these alcohol il agents
It may contain 440% by weight or less of a low dielectric constant solvent such as acetone, methyl acetate, ethyl acetate, or benzene.

The degree of polymerization of the modified PVA used in the present invention should be appropriately selected depending on the purpose of use, but is usually 100-
A range of 3000 is suitable.

Using the above-obtained modified PVAI alone as a stabilizer, in the presence of an initiator in the aqueous phase, acrylic esters such as ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, methacrylic ether A good emulsion polymer can be obtained by emulsion polymerization of methacrylic acid esters such as methyl methacrylate, 2-ethyl methacrylate, methacrylic acid ester, and lauryl methacrylate. As a small component in emulsion polymerization.

It is also possible to copolymerize with gold such as vinyl acetate, styrene, acrylic acid, acrylamide, itaconic acid, etc. In this invention, the use of a low-molecular activator is not an essential condition, but it can be used, for example, to adjust the particle size. It is permissible to use them together as an auxiliary measure.

In addition, optionally other protective colloids, such as unmodified PVA, polyacrylic acid, polymethacrylic acid and their salts, polyvinyl alkyl ethers, copolymers of vinyl acetate and acrylic acid or methacrylic acid, or vinyl acetate and maleic anhydride. copolymers with and saponified products thereof, lower alkyl vinyl ether-maleic anhydride copolymers, cellulose derivatives such as alkyl cellulose, hydroxyalkyl cellulose, alkyl hydroxy alkyl cellulose, carboxymethyl cellulose, alkyl starch, carboxymethyl starch , oxidized starch, gum arabic, gum tragacanth, polyalyl alcohol, etc. are used during polymerization.

Alternatively, it can be added after polymerization. In addition, there are liquid aS agents used in ordinary emulsion polymerization.

Monohydric or polyhydric alcohols, opacifying agents, sodium chloride, sodium chloride, sodium phosphate.

There is no problem in using auxiliary agents such as inorganic salts such as sodium sulfate, state regulators such as ammonia, sodium hydroxide, and hydrochloric acid, and antifoaming agents during and after the polymerization.

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 monomer.

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

Sulfinic acids and their salts 11% Combinations with oxidialdehydes, water-soluble iron salts, etc., persulfates.

Percarbonates, perborates, peroxides, etc. can be applied.

The emulsion polymerization emulsion obtained in this way exhibits excellent stability and moderate viscosity, and is effective in adhesives, pressure-sensitive adhesives, fiber processing agents, paper processing agents, and even cement mixtures. The value of industrial use is truly great.

Next, the present invention will be explained in more detail with reference to Examples.

In the examples, parts J and rLI are based on weight unless otherwise specified.

Example 1 (0.3 mol% lauryl vinyl ether as a gradient component)
, more than 97.8 moles of the vinyl acetate component of the polyvinyl acetate ester copolymer containing 3.7 moles of crotonic acid as component (B) was saponified, and the viscosity of the 4% aqueous solution at 20°C was 37 centes. 4 X Teh 7;+
D; 0.99 R property P V A 10 s *
9 yal-Dissolve 1.0 part of sodium in 225 parts of water and keep at 65°C. Butyl acrylate 1 under N3 atmosphere
6 parts and 10 parts of a 5-aqueous solution of ammonium persulfate were added to initiate polymerization f:. After 15 minutes, 150 parts of butyl acrylate was continuously added over 2 hours to carry out one polymerization. After the addition was completed, the internal temperature was kept at 65° C. for 30 minutes and then cooled. When the emulsion was removed, a clean emulsion with no coarse particles was obtained, and it was stable after being left for 3 months. The emulsion was measured using a Bwi viscosity needle with 10 rotations.
The viscosity at G'C was measured to be 1920 centipoise.

Further, the film formed by flowing the emulsion to a thickness of 0.5 cm was slightly cloudy.

Comparative Example 1 More than 98.1 mol of the vinyl acetate component of a polyvinyl acetate ester copolymer containing 0.3 mol of lauryl vinyl ether as component (A) and not containing component (A) was saponified and heated at 20°C. The viscosity of the 4-chi aqueous solution is 1
Emulsion polymerization of butyl acrylate was attempted in the same manner as in Example 1 except for using modified PVA with 85 centivoids, but when 20 parts of butyl acrylate was added, the whole became a muddy gel and smooth emulsion polymerization was not possible. I couldn't do it.

Comparative Example 2 97.9 moles of the vinyl acetate component of a polyvinyl acetate copolymer containing 3.7 moles of crotonic acid as component (B) and no four components was saponified and 20"C Emulsion polymerization of butyl acrylate was attempted in the same manner as in Example 1 except that modified PvAt whose aqueous solution viscosity was 10 centipoise was used, but when 25 parts of butyl acrylate was added, the entire product turned into a muddy gel. Therefore, smooth emulsion polymerization could not be carried out.

Comparative Example 3 PVA which is unmodified PVA whose 4ts aqueous solution is 28 centipoise and saponification degree is 98.5 molar or more when heated to 20°C
Emulsion polymerization of butyl acrylate was attempted in the same manner as in Example 1 except that 117 (Kuraray tS Co., Ltd.) was used, but when 35 parts of butyl acrylate was added, the entire product turned into a muddy gel and smooth emulsion polymerization was not possible. I couldn't do it.

Example 2 0.5 mol m of branched fatty acid vinyl ester having an average carbon number of 10 (VeoVa-10 manufactured by Shell) as the four components
, tL at which 96.5 moles of the vinyl acetate component of the polyvinyl acetate copolymer containing 3.0 moles of itaconic acid as component (B) is saponified and the viscosity of the aqueous solution at 20°C is lθ centiboise. D=0.
When emulsion polymerization of butyl acrylate was carried out in the same manner as in Example 1 except that modified PVA No. 60 was used, a clean emulsion without coarse particles was obtained and was stable even after being left for 6 months. The B-type viscosity of the emulsion at 30° C. and 110 revolutions per minute was 2340 centipoise, and the transparency of the film formed by casting the emulsion to a thickness of 0.5 w×K was good.

Example 3 A polyacetate vinyl ester copolymer containing 0.2 mol % of a branched fatty acid vinyl ester having an average carbon number of 10 as the (A) component and 7.0 mol % of crotonic acid as the (B) component. 97.1 mol of the vinyl acetate component was saponified and the viscosity of the 45G aqueous solution at 20°C was 12
Centiboise 1)=-Q. Emulsion polymerization was carried out in the same manner as in Example 1 except that modified PVA of No. 27 and acrylic 1:2 ethylhexyl were used as the emulsion polymerization monomer. As a result, a clean emulsion without coarse particles was obtained.
It remained stable even after being left alone for several months.

Mukuro emulsion at 30℃, lO rotation/min 17) B! The viscosity of the emulsion is 620 centipoise, and the thickness of the emulsion is 0.
．． The transparency of the film produced by casting so as to have a diameter of 5.5 cm was good.

Comparative Example 4 Butyl vinyl ether 0.06-1- as component (A)
Jl/9L (B) 96.8 mol of the vinyl acetate component of the polyvinyl acetate ester copolymer containing 9.8 mol of itaconic acid as the component was saponified and 20
D whose viscosity of a 4% aqueous solution at °C is 19 centiboise
Emulsion polymerization of 2-ethylhexyl acrylate was attempted in the same manner as in Example 3 except for using modified PVA of =0.018, but when 80 parts of 2-ethylhexyl acrylate was added, the gold body gelled and a good emulsion was not obtained. was not obtained.

Comparative Example 5 Acetic acid of a polyacetate vinyl ester copolymer containing 2.8 moles of crotonic acid as a component (in 0.9 moles of normal propyl vinyl ether t having an alkyl group having 3 carbon atoms as a component) 97 of vinyl ester components
．． D = 1.0 mole is saponified and the viscosity of the 4% aqueous solution at 20°C is 16 centepoise. Modified PV of OO
Acrylic acid 2 was prepared in the same manner as in Example 3 except that A was used.
- An attempt was made to emulsion polymerize ethylhexyl, but when 40 parts of 2-ethylhexyl acrylate was added, the mixture turned into a muddy gel and a good emulsion could not be obtained.

Comparative Example 6 (5) Branched fatty acid vinyl ester having an average carbon number of 10 (Shell Chemical Co., Ltd.) 4
Mol 1. (B) After saponifying 96 moles of the vinyl acetate component of the polyvinyl acetate ester copolymer containing 1 mole of maleic anhydride as the component, 2
Example 3 except that modified PVA1 with a viscosity of 41 g aqueous solution at 0°C of 25 centiboise and a cut D of 14.0 was used.
An attempt was made to carry out emulsion polymerization in the same manner as above, but when 2-ethylhexyl acrylate was added to 9011S, the entire mixture turned into a muddy gel, and a good emulsion could not be obtained.

Example 4 Emulsion polymerization was carried out in the same manner as in Example 3 except that methyl methacrylate was used as the monomer, and a clean emulsion without coarse particles was obtained, which was stable even after being left for 6 months.

Bfi viscosity F of the emulsion at 30°C, lO revolutions/min
It was i1720 centiboise.

Example 5 Emulsion polymerization Emulsion polymerization was carried out in the same manner as in Example 3 except that a 70:30 mixture of butyl acrylate and vinyl acetate was used as the monomer, and a clean emulsion without coarse particles was obtained. After being left for 6 months. was also stable.

The emulsion has a BW viscosity of 1 at 30°C and 10 revolutions/min.
940 centipoise, and the emulsion has a thickness of 5
The transparency of the coating formed by casting was good.

Patented wheat flour Kuraray Co., Ltd. Benefactor Patent Attorney Honda Bar

Claims (1)

[Scope of Claims] (1) (A) 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 monomer. (B) A saponified product of a copolymer containing as an essential copolymer component a ternary product of at least one kind of ethylenically unsaturated carboxylic acid or its lower alkyl ester or acid anhydride and zero acetate vinyl ester, and the following: (1) A method of emulsion polymerization of (meth)acrylic acid esters in the presence of modified polyvinyl alcohol that satisfies the formula. 0.05<D<4 ...-(1)B However, A is the copolymerization ratio (molar basis) of the ^ component in seconds, -V
The nil fraction is o, ooos or more, B is the copolymerization ratio (mole basis) of the same component, and the mole fraction is 0.001 or more, cF
i (c) is the copolymerization ratio (on a molar basis) of the component, which is a mole fraction of 0.5 or more, n is an integer of 4 or more, and (5) when the component is a vinyl ester of a fatty acid. n = number of carbon atoms in fatty acid - 1, when component (5) is an alkyl vinyl ether, n = number of carbon atoms in the alkyl group, component (5) is α
- When it is an olefin, n = α- Number of carbon atoms in the olefin - 2, l
represents the number of carboxyl groups in component (B), and Δ represents the saponification ratio of the nine components in the copolymer. (2) In component (8), the carboxyl group is tertiary or 4-
A branched fatty acid vinyl ester existing at the α-position relative to the carbon atom of A method of emulsion polymerization of the described (meth)acrylic esters. (8) A method for emulsion polymerization of (meth)acrylic acid esters according to claim (2)K, wherein component (B) is itaconic acid.