JPH01289814A - Preparation of acrylic microgel - Google Patents

Abstract

PURPOSE:To obtain a typical acrylic microgel while a polymn process and a crosslinking process are simultaneously performed, by carrying out non-aq. dispersion polymn. of methyl acrylate and a specified radical-polymerizable polyfunctional crosslinking agent by using a specified dispersing agent. CONSTITUTION:Non-aq. polymn. of a monomer mixture wherein 98.0-99.9mol% methyl acrylate and 0.1-2.0mol% divinyl adipate and/or diallyl adipate are compounded in a total content of 100mol% is performed in an aliph. hydrocarbon (e.g., hexane, heptane etc. are pref.) by using a comb-shaped graft copolymer wherein a segment (a backbone part of the comb) consisting mainly of poly(methyl methacrylate) and a segment (a blade part of the comb) consisting of poly(12-hydroxystearic acid) are the constituents as a dispersing agent.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing acrylic microgels used as paint film performance improvers, rheology control agents, etc.

(Prior art) A method for preparing methyl acrylate/divinylbenzene microgels by emulsion polymerization is described in Journal of Polymer Science, Vol. 33.

pp. 101-117 (1958) (Journal
of Polymer 5science, Vol. 3
3. PPI O1-117 (1958)). For example, a method for preparing methyl methacrylate/ethylene glycol dimethacrylate microgels by emulsion polymerization is described in British Patent No. 967051.

On the other hand, methyl methacrylate in an aliphatic hydrocarbon,
A non-aqueous dispersion polymerization method is performed using a comb-shaped graft copolymer whose main components are segments made of poly(methyl methacrylate) and segments made of poly(12-hydroxystearic acid) as a dispersant. The method for producing polymer particles is also covered by British Patent No. 11.
No. 22397.

Furthermore, as a method for preparing cross-linked polymer fine particles (microgels) using a non-aqueous dispersion polymerization method, 2 for example, methyl methacrylate is subjected to non-aqueous dispersion polymerization in substantially the same manner as described above. Journal describes a method in which acid/glycidyl methacrylate is added to carry out non-aqueous dispersion polymerization, and triethylenediamine is further added in the latter stage of the polymerization to cause the carboxyl group of methacrylic acid to react with the glycidyl group of glycidyl methacrylate to form a crosslink.・Op Coating Technology, Volume 54, N [L693゜pages 83-90 (
1982) (Journal of Coating
sTechnologies Vol, 54. , NQ
639. J'P83-90 (1982)).

However, in the past, radical polymerizable crosslinking was carried out simultaneously during non-aqueous dispersion polymerization using a radical polymerizable crosslinking agent.
It was not possible to obtain typical cross-linked polymer microparticles (microgels).

(Problems to be Solved by the Invention) The method of preparing acrylic microgels by emulsion polymerization is easy to prepare the microgels, but it is difficult to prepare emulsifiers (anionic surfactants) and salting-out agents in the microgels produced. (N
aCl! , MgSO4, etc.), so there was a serious problem that it could not be used for applications that dislike ionic impurities.

On the other hand, unlike the emulsion polymerization method, the method of preparing acrylic microgels using non-aqueous dispersion polymerization does not involve the contamination of ionic impurities. Reaction and crosslinking cannot be carried out at the same time, and it is necessary to carry out crosslinking after preparing the polymer particles.

There was a problem that the preparation process was complicated.

The present invention has been made in view of the above-mentioned problems, and allows the polymerization reaction and the crosslinking reaction to be carried out simultaneously using a radically polymerizable polyfunctional crosslinking agent. This paper attempts to provide a typical method for producing microgels using a non-aqueous dispersion polymerization method.

(Means for solving the problem) That is, the present invention is methyl acrylate) 98.0 to 99
．． A monomer mixture containing 9 moles of divinyl adipate and/or diallyl adipate and 0.1 to 2.0 moles of divinyl adipate and/or diallyl adipate to a total of 100 moles is mixed with a segment mainly consisting of poly(methyl methacrylate) and poly(12-hydroxy A comb-shaped graft copolymer containing segments consisting of (stearic acid) as a dispersant.

The present invention relates to a method for producing an acrylic microgel characterized by non-aqueous dispersion polymerization in an aliphatic hydrocarbon.

In the present invention, a typical microgel is defined as one having an intrinsic viscosity of 0.3 di79 or less when measured in toluene at 30° C., and whose toluene dispersion exhibits a pale blue color.

In the present invention, the monomer mixture consists of 9 & 0 to 99.9 moles of methyl acrylate and divinyl adipate and/or
or diallyl adipate) 0.1 to 2.0 molti should be blended so that the total amount is 100 molti. Acrylic monomers other than methacrylate, such as ethyl acrylate.

If butyl acrylate, methyl methacrylate, butyl methacrylate, etc. are used in the same proportions, the particles will aggregate and become coarse during polymerization, and either microgels will not be obtained or non-aqueous dispersion polymerization will not occur.

Further, radically polymerizable polyfunctional crosslinking agents other than divinyl adipate and/or diallyl adipate 9 such as ethylene glycol dimethacrylate and ethylene glycol diacrylate.

If 1.4-butanediol diacrylate, 1.4-butanediol dimethacrylate, 1.6-hexanethiol diacrylate, 1.6-hexanethiol dimethacrylate, etc. are used in the same proportions, the intrinsic viscosity is 0.
．． 3, it is not possible to obtain a typical microgel. Furthermore, when the proportion of divinyl adipate and/or diallyl adipate in the monomer mixture is less than 0.1 molar (methyl acrylate exceeds 99.9 molar), the intrinsic viscosity exceeds 0.3, making it difficult to obtain typical microgels. 9 On the contrary, when this ratio exceeds 2 molt (
If the amount of methyl acrylate is less than 98 mol), the particles will aggregate and become coarse during polymerization, making it impossible to obtain a microgel.

In the present invention, the above monomer mixture must be subjected to non-aqueous dispersion polymerization in an aliphatic hydrocarbon.

If organic solvents other than aliphatic hydrocarbons such as alcohols, ketones, aromatic hydrocarbons, acetic esters, etc. are used, either solution polymerization will occur or the entire polymerization system will become sticky. It is. The boiling point of the aliphatic hydrocarbon used in the present invention is preferably within the range of about 50-200°C. When the boiling point is less than 50°C, there are many restrictions on the polymerization initiators that can be used, while when the boiling point is over 200°C, the resulting microgel can be converted from aliphatic hydrocarbons to other organic solvents using an azeotropic distillation method. It becomes difficult to relocate. Examples of preferred aliphatic hydrocarbons include hexane, heptane, octane, nonane and mixtures thereof.

The dispersant used in the present invention, that is, the comb-shaped graft copolymer, consists of segments cA) of poly(12-hydroxystearic acid) having an affinity for hydrocarbons in the shape of comb blades.
Furthermore, it is necessary to be a graft copolymer having segments (B) mainly of poly(methyl methacrylate) in the shape of a comb back, which have affinity with the methyl acrylate microgel to be produced.

The segment (B) is particularly preferably one in which methyl methacrylate is copolymerized with a small amount of methacrylic acid and/or acrylic acid (for example, methyl methacrylate 98% by weight, methacrylic acid 2(i')). If the polymer described here does not have the segment structure and morphology, either the non-aqueous dispersion polymerization does not occur well and the entire polymerization system becomes sticky, or the produced polymer particles aggregate and become coarse. be.

Examples of the preparation of comb-shaped copolymers that can be used in the present invention include 9 E, J.

Palette edition “Disversion Polymerization
In Organic Medium” John Willie
and Sons (1975), p. 108 (K, E,
J, Barrel (Edit, ) “Dispers
ion Polymerization in Org
anic Media” John Wiley &
5ons (1975), P2O3). The comb-shaped graft copolymer is preferably used in an amount of 5 to 20 parts by weight per 100 parts by weight of the monomer mixture to obtain a typical microgel.

In the present invention, in the non-aqueous dispersion polymerization, it is desirable that the weight ratio of hydrocarbons to the monomer mixture is 115 or less compared to the conventionally known method.

The polymerization initiator may be selected from conventionally known initiators that have the ability to initiate polymerization depending on the double polymerization temperature. Examples of suitable polymerization initiators include benzoyl peroxide, azobisisobutyronitrile, 42'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2°4-dimethyl Valeronitrile), lauroyl peroxide, etc. The amount of the polymerization initiator is determined from the viewpoints of polymerization initiation ability, control of polymerization heat generation, etc., but it is desirable to use about 0.3 to 3 parts by weight of the polymerization initiator per 100 parts by weight of the monomer mixture. The polymerization temperature is determined by the initiator used and the degree of the aliphatic hydrocarbon, but is generally within the range of 40 to 140°C.

By the above 9 manufacturing methods of the present invention, 30
The intrinsic viscosity measured at °C is 0.3 dJ/g or less, and the toluene dispersion exhibits a pale blue color.

A typical microgel is obtained.

(Example) (<Synthesis of C-shaped graft copolymer) 12- and 180 g of droxystearic acid were heated at 195°C for 10.5 hours in the presence of 20 g of xylene and 0.189 g of dibutyltin oxide (esterification catalyst). Poly(12-hydroxystearic acid) was prepared by carrying out intercondensation polymerization and azeotropically distilling the resulting condensed water together with xylene and distilling it off.

The oxidation of the obtained poly(hydroxystearic acid) was 35
．． OffIgKOH/.

Furthermore, 140 g of poly(12-hydroxystearic acid) obtained above and 17.6 g of glycidyl methacrylate
9 was dissolved in 140 g of xylene.

Hydroquinone (polymerization inhibitor) 0.149 and N.

12 at 140°C in the presence of 0.269 N-dimethyllaurylamine (catalyst for the reaction of carboxyl groups and epoxy groups)
Poly(12-hydroxystearic acid)/glycidyl methacrylate adduct (
macromonomer) was prepared.

The acid value of the xylene solution of the macromonomer produced is 1 KO.
It was H/9 or less.

Then, azobisisobutyronitrile a, og was added to a mixed solvent of 53 g of ethyl acetate and 26.59 g of butyl acetate refluxed at 82-84°C.

Macromonomer obtained above (as xylene solution) 144
g, methyl methacrylate 729 and methacrylic 1
．． Add 5 g of the mixture dropwise over 3 hours.

Reflux was further continued at 97 to 101°C for 2 hours to prepare a scoop-shaped graft copolymer. The nonvolatile content of the reactant (measured at 150° C./lh) was 55.7% by weight. This was diluted with n-hexane until the nonvolatile content became 30% by weight.

It was used as a dispersant for non-aqueous dispersion polymerization. All n-hexane was manufactured by Wako Tsumugi Kogyo (■) and was used as it was without purification.

Example 1 30 mL of n-hexane was placed in a 500 d flask equipped with a cooling tube, a stirring device, a nitrogen blowing tube, and a thermocouple for temperature control.
09. 30 g of a monomer mixture of 99.5 molt methyl acrylate and 0.5 molt divinyl adipate9
Polymerization initiator: 2'-azobis(4-dimethylvaleronitrile), 3 g and the above dispersant (non-volatile content: 30
% by weight) was charged and polymerized at 60° C. for 5 hours with stirring. The polymerization solution was initially transparent, then gradually became cloudy and milky.

Next, 100 g of the polymerization liquid was poured into 40 g of toluene while stirring, and the mixture was poured into an evaporator (depressurization degree of about 100 m).
mHg), n-hexane, unreacted monomers, etc. were azeotropically distilled off with hedolene outside the system. The resulting polymer dispersion was transparent and had a pale blue color. Impurities such as n-hexane and unreacted monomer determined by gas chromatography were found to be 0.1 fold tS. A toluene dispersion of this polymer was used as a sample and measured at 30±0.1° C. using a Cannon-Fenske viscometer.

As a result, the intrinsic viscosity was 0.13 di/9.

Example 2 A toluene dispersion of a polymer was prepared in exactly the same manner as in Example 1, except that a monomer mixture of 99.9 mol of methyl acrylate and 0.1 mol of divinyl adipate was used. The obtained polymer dispersion was
It was transparent and had a pale blue color. The amount of impurities such as 90-hexane and unreacted monomers was determined by gas chromatography to be less than 0.1% by weight. The intrinsic viscosity of a toluene dispersion of this polymer was 0.28 di/9.

Example 3 A toluene dispersion of a polymer was prepared in exactly the same manner as in Example 1, except that a monomer mixture of methyl acrylate-598 and divinyl adipate-2 was used. The resulting toluene dispersion of the polymer was transparent and had a pale blue color. The amount of impurities such as n-hexane and unreacted monomers determined by gas chromatography was less than 0.1% by weight. The intrinsic viscosity of the toluene dispersion of this polymer was 0.3061/g.

Example 4 A toluene dispersion of a polymer was prepared in exactly the same manner as in Example 1 except that diallyl adipate was used instead of divinyl adipate. The resulting toluene dispersion of the polymer.

It was transparent and had a pale blue color. It was determined by gas chromatography. Impurities such as n-hexane and unreacted monomers were all less than 0.1% by weight. The intrinsic viscosity of a toluene dispersion of this polymer is 0.20 dl/
It was a.

Comparative Example 1 A toluene dispersion of a polymer was prepared in exactly the same manner as in Example 1, except that a monomer mixture of 99.95 mol of methyl acrylate and 0.05 mol of divinyl adipate was used. The resulting toluene dispersion of the polymer was transparent and colorless to pale yellow.

n-hexane determined by gas chromatography method,
All impurities such as unreacted monomers were less than 0.1 weight tS.

The intrinsic viscosity of a toluene dispersion of this polymer is 0.50 dl
! /g.

Comparative Example 2 Polymerization was carried out in exactly the same manner as in Example 1, except that a monomer mixture of 97 mol of methyl methacrylate and 37 mol of divinyl adipate was used, but in the middle of the 2-polymerization, the produced polymer particles were visible. It aggregated and became coarse. This could no longer be homogeneously dispersed in toluene.

Comparative Example 3 A toluene dispersion of a polymer was prepared in exactly the same manner as in Example 1 except that ethylene glycol dimethacrylate was used instead of divinyl adipate. The obtained toluene dispersion of the polymer was transparent and had a colorless to pale yellow color.

n-hexane determined by gas chromatography method,
All impurities such as unreacted monomers were less than 0.1 weight. The intrinsic viscosity of this polymer toluene dispersion is 0.80
dl! /g.

Comparative Example 4 A toluene dispersion of a polymer was prepared in exactly the same manner as in Example 1 except that ethylene glycol diacrylate was used instead of divinyl adipate. The resulting toluene dispersion of the polymer was transparent and had a colorless or pale blue color.

n-hexane determined by gas chromatography method,
All impurities such as unreacted monomers were less than 0.1% by weight. The intrinsic viscosity of a toluene dispersion of this polymer is 0.
It was 40 dl/g.

Comparative Example 5 In Example 1, divinyl adipate was replaced with 1.6
A toluene dispersion of a polymer was prepared in exactly the same manner as in Example 1 except that -hexanediol diacrylate was used. The resulting toluene dispersion of the polymer was transparent and had a colorless or pale blue color. The amount of impurities such as n-hexane and unreacted monomers determined by gas chromatography was less than 0.1% by weight. The intrinsic viscosity of this polymer dispersion was 0.42 di/g.

Comparative Example 6 Polymerization was carried out in exactly the same manner as in Example 1 except that butyl acrylate was used instead of methyl acrylate, but the polymerization solution did not become milky, which is characteristic of non-aqueous dispersion polymerization. It remained translucent.

Comparative Example 7 Polymerization was carried out in exactly the same manner as in Example 1 except that methyl methacrylate was used instead of methyl acrylate, but during the polymerization, the polymer particles formed were agglomerated and coarsened to the extent that they were visible. did. This could no longer be homogeneously dispersed in toluene.

(Effects of the Invention) According to the present invention, a typical microgel can be obtained by carrying out the non-aqueous dispersion polymerization of 9% acrylic monomer at a specific ratio as described above, while performing the polymerization process and the crosslinking process simultaneously. It will be done. In addition, compared to the conventional emulsion polymerization method,
No ionic impurities mixed in. Furthermore, the manufacturing process of the nine polymerization steps and crosslinking is simpler than the conventional non-aqueous dispersion polymerization method in which the steps are separated.

−.

Claims (1)

[Claims] 1. Methyl acrylate 98.0-99.9 mol% and divinyl adipate and/or diallyl adipate 0
．． A monomer mixture containing 1 to 2.0 mol% so that the total amount is 100 mol% is composed of a segment mainly consisting of poly(methyl methacrylate) and a segment consisting of poly(12-hydroxystearic acid). A method for producing an acrylic microgel, which comprises performing non-aqueous dispersion polymerization in an aliphatic hydrocarbon using a comb-shaped graft copolymer as a dispersant.