JPS62121702A - Fine polymer particle - Google Patents

Abstract

PURPOSE:To obtain fine polymer particles excellent in dispersibility, etc., and suitable as a resin modifier, etc., by suspension-polymerizing a vinyl- polymerizable monomer, adding an amino compound/formaldehyde precondensate and an acid catalyst to the suspension and heating the mixture. CONSTITUTION:A vinyl-polymerizable monomer (e.g., butyl acrylate or butyl acetate) is suspension-polymerized in an aqueous medium in the presence of a protective colloid (e.g., polyvinyl alcohol or gelatin). The obtained suspension is mixed with an amino compound/formaldehyde precondensate (e.g., melamine/ formaldehyde precondensate or urea/formaldehyde precondensate) and an acid catalyst (e.g., dil. sulfuric acid), and the obtained mixture is heated at a temperature of about 40-100 deg.C for about 1-5hr. This suspension is subjected to solid/ liquid separation, and the obtained solid matter is dried to obtain the purpose fine polymer particles as a nonsticky powder.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to small coalescing microparticles. More specifically, the present invention relates to small, non-adhesive powder-like fine particles that have excellent dispersibility and molecular stability and are useful as modifiers for resins.

(Prior art) A polymer is separated from a suspension obtained by suspending and bonding a vinyl monomer monopolymer in an aqueous medium in the presence of a protective colloid such as polyvinyl alcohol to produce a powdered polymer. Methods for producing these are well known, and polymers obtained by such methods are used in various applied fields.

However, in the method for manufacturing powdered polymers, agglomeration of polymer fine particles may occur when separating the polymer from an aqueous medium, or fusion of fine particles may occur during drying. It was difficult to extract the 1!7% I fine particles as they were in the form of powdery polymer fine particles during the polymerization process. This tendency was particularly remarkable for polymers exhibiting stickiness.

As a method to prevent the above-mentioned agglomeration and fusion, methods such as mixing non-adhesive inorganic fine powders have been proposed, but it is still not possible to directly extract sticky particles from an aqueous medium. However, when used dispersed in various media such as for modifying resins, there were problems in terms of dispersibility and dispersion stability.

(Problems to be Solved by the Invention) The present invention solves the problem of agglomeration of fine particles when separating polymer fine particles obtained by suspension polymerization from an aqueous medium and fusion of fine particles with each other during the drying process. 1!7 in the Nakadai process without causing any problems.
This makes it possible to take out the fine particles as they are as powdered polymer fine particles, and also improves dispersibility and
The object of the present invention is to provide powdery polymer fine particles having excellent dispersion stability.

(Means and effects for solving the problems) The present invention has the following features:
An amino compound-formaldehyde initial condensate and an acid catalyst are mixed into a suspension obtained by suspension polymerization of a vinyl polymerizable monoa in an aqueous medium in the presence of a protective colloid, and the suspension is heated. This relates to polymer fine particles obtained by separating and drying a turbid liquid.

The vinyl polymerizable monoconvex body used in the present invention is not particularly limited, and includes, for example, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid, or maleic acid, fumaric acid, and itaconic acid. Nisderic acrylates such as ethyl nitride acrylate, butyl acrylate, and 2-delhexyl acrylate;
Methacrylic acid esters such as methyl methacrylate, methyl methacrylate, and cyclohexyl methacrylate; Banko IJX vinyls such as styrene and vinyltoluene; Unsaturated di-1-lyls such as acrylonitrile and methacrylonitrile; vinyl acetate and propio-resistant Vinyl esters such as vinyl, )i′! In addition, a crosslinkable matrix having two or more polymerizable double bonds in one molecule can also be used as appropriate. Crosslinkability 13! ii1 bodies include ethylene glycol di(meth)acrylate, 1-sameethylene di(meth)acrylate-1-, trimethylolpropane 1-ly(meth)acrylate, pentaerythritol tri(meth)acrylate, triallylisocyanurate, divinylben Commonly used crosslinking monomers such as U can be used.

These vinyl polymerizable intermediates may contain any one or more types depending on the purpose of the finally obtained rF combined fine particles.
It can be used in one go. For example, when forming a small aggregate with soft, rubber-like properties, a (meth)acrylic ester having 4 or more carbon atoms is used as the main component.

Protective colloids used as stabilizers during suspension polymerization include water-soluble polymer compounds such as polyvinyl alcohol, pyratine, starch, carbo-4-2-cymedyl cellulose, and polyacrylates, and sparingly soluble inorganic fine powders such as calcium carbonate and bentonoite. etc., and anionic surfactants and nonionic surfactants may also be used in part. Among these, polyvinyl alcohol is preferable because it reacts with formaldehyde in a later step to form a non-adhesive small lumal compound, further enhancing the effect of modifying the surface of the polymer fine particles as described below. Polyvinyl alcohol (P) that can be used in the present invention
VA) may be any of the generally used partially saponified PVA, completely saponified PVA, and carboxyl group-modified PVA, and its molecular weight is not particularly limited. The amount of protective colloid to be used may be selected depending on the relationship with the particle size of the polymer fine particles to be obtained, the Φ synthetic leather quality, etc.;
1 to 15 ΦM parts, preferably 0.5 to 10 ΦM parts, is suitable.

Suspension polymerization may be carried out in an aqueous medium according to a known method. The solid content concentration during polymerization is 10 to 70% by weight, more preferably 20 to 50% by weight from the viewpoint of polymerization stability. As the polymerization catalyst, common polymerization catalysts such as benzoyl peroxide and azobisisobutyronitrile are used.

The amino compound-formaldehyde initial condensate used in the present invention is a water-soluble compound obtained from formaldehyde and an amino compound such as melamine, benzoguanamine, acetoguanamine, sp[]guanamine, phenylacetoguanamine, dicyandiamide, urea, or thiourea. This is a reaction product of 1, which is further condensed and cured in the presence of an acid catalyst to form a non-tacky cured resin.

For example, an amino compound and formaldehyde may be added to the initial mixture at 11° C. and 1.2 mol of the latter per 1 mole of the latter.
The reaction is carried out using a skewer of ~6°C to 12°C, preferably 6 to 10°C, and a reaction temperature of 131,130 to 150°C, preferably 50 to 100°C. Any formaldehyde that generates formaldehyde, such as formalin, trioxane, and paraformaldehyde, can be used. This reaction can be arbitrarily terminated at any stage from the time when the amino compound disappears to just before the reaction product becomes water-insoluble.

Among the initial condensates obtained in this way, one or two selected from melamine, benzoguanamine, and urea.
Particularly preferred is an initial condensate of an amino compound and formaldehyde in which at least one of these compounds is used in a desired ratio.

The amount of the amino compound-formaldehyde initial condensate to be used is 1 to 100 parts per 100 parts per vinyl monomer suspension used to obtain the polymer suspension, Yl: 1
Niji < is 5 to 50 thousand hanging parts. If the amount is less than 1 part, it will be difficult to prevent separation and drying [1.
In addition, if more than 100 parts by weight of PolyG is used, the system becomes unstable during the integrated curing of the initial condensate in the presence of an acid catalyst, resulting in the formation of aggregates. This is not preferable because it occurs and reduces VJ.

Examples of acid catalysts used as curing catalysts for amino compounds - formaldehyde first 191 condensates include mineral acids such as hydrochloric acid, sulfuric acid, and phosphoric acid; , sulfones such as dodecylbenzenesulfonic acid If! 2: Organic acids such as phthalic acid and sulfamic acid; one or more selected from sulfamic acid and the like can be used in any proportion. The amount of the acid catalyst to be used is 0.1 to 40 parts by weight, preferably 1 to 20 parts by weight, based on 100 parts by weight of the initial condensate.

As a method of mixing a polymer suspension with an amino compound-formaldehyde initial condensate and an acid catalyst and heat-treating the mixture, for example, the initial condensate and an acid catalyst are added and mixed to the suspension, and the mixed liquid is heated. may be added by heating and stirring, and the addition order may be in any order. Furthermore, during mixing, the initial condensate or acid catalyst may be used as an aqueous solution or diluted with water. Heat treatment ranges from a low temperature of 30℃ to 100℃
It can be carried out under the above pressure, but preferably carried out at a humidity of 40 to 100°C for 1 to 5 hours.

After the heat treatment, the suspension is subjected to solid-liquid separation, and the iq solid content is dried to obtain polymerized fA fine particles of the present invention in the form of non-adhesive powder. For separation and drying, any known method may be used; for example, various separation methods such as natural sedimentation, centrifugal sedimentation, and separation by filtration, and various drying methods such as natural (drying), vacuum drying, hot air drying, etc. may be used. I was able to get hired.

In the present invention, it is not clear why small aggregate particles in the form of non-adhesive powder with excellent dispersibility are obtained; Then, fine droplets of the hydrophobized amino compound-formaldehyde condensate are deposited on the surface of the polymer fine particles in the suspension. - Due to the effect of encapsulation and modification with the formaldehyde condensate, aggregation of the polymer fine particles with each other during separation and fusion during the drying process are completely prevented.

In addition, if polyvinyl alcohol is used as the protective covalent compound for 1 q of the suspension, it will react with the TI-formaldehyde in the amino compound-formaldehyde initial condensate to form a non-adhesive It can be predicted that a formalized product of polyvinyl alcohol will be generated on the surface of the polymer fine particles, and it is thought that the encapsulation and modification effect on the surface of the polymer fine particles described in (-) will be further enhanced. However, the present invention is not limited in any way by these reasons, and the excellent dispersibility of the final polymer fine particles in various media is surprising.

(Effects of the Invention) The small fine particles of the present invention have their surfaces treated with an amino compound-formaldehyde condensate during the manufacturing process, so even if they are made of vinyl, which can only be obtained from polymers with a low softening point and easy to fuse. Even if a polymerizable monomer is used, the fine particles obtained during suspension polymerization can be easily obtained as a powder without causing aggregation or fusion. In addition, when the polymer fine particles of the present invention are used as a modifier for resins, they have excellent dispersibility in resins and dispersion stability over time, so they can be used as modifiers for polyvinyl chloride, polyethylene, polypropylene, etc. It is useful as a modifier such as a shrinkage softener for thermosetting resins such as thermoplastic resins, unsaturated polyester resins, and epoxy resins. Furthermore, it can be used as a valley absorption agent, filler, paint additive, etc.

The present invention will be explained below with reference to Examples, but the scope of the present invention is not limited in any way by these Examples. In addition, in the examples, unless otherwise specified, % means weight M%, and part means 1
It shall represent 0 parts.

Example 1 400 parts of water was charged into a reaction vessel equipped with a thermometer, a stirrer, a reflux condenser, and a dropping funnel, and without stirring, 3 parts of completely saponified polyvinyl alcohol with a degree of saponification of 98 to 99 mol% and a polymerization TC of 11000 was added. After adding and dissolving, 100 parts of butyl acrylate in which 0.5 part of azobisisobutyronitrile was dissolved was added dropwise, followed by sufficient nitrogen exchange and the temperature was raised to 65°C. After confirming the start of the reaction by the generation of polymerization heat, continue for an additional 2 hours 7
The reaction proceeded at 0°C to obtain a suspension of butyl acrylate polymer. The polymerization rate was 98.6%.

Meanwhile, in another reaction vessel equipped with a thermometer, a stirrer, and a reflux condenser, 40 parts of melamine, 100 parts of 37% formalin, and 1 part of 28% ammonia aqueous solution were charged, and while stirring,
After raising the temperature to 0° C. and proceeding with the reaction for 10 minutes at the same temperature, 244 parts of water was added to obtain an aqueous solution of an initial melamine-formaldehyde saccharide.

Of the butyl acrylate polymer obtained as above!
! ! 50 parts of the aqueous solution of the melamine-formaldehyde initial condensate and 20 parts of 5% dodecylbenzenesulfonic acid aqueous solution FIi were mixed with 100 parts of the turbid liquid, and 8 parts of the aqueous solution of 5% dodecylbenzenesulfonic acid was mixed with stirring.
The stomach was dried to 0°C and then heated at 80°C for 3 hours. After the heat treatment, the resulting suspension was cooled to remove the polymer cake by filtration and dried in a hot air dryer at 100°C for 5 hours. did.

The polymer cake obtained by drying is a non-adhesive white powder that becomes fine particles by simple force, and the cake is deagglomerated using a hammer mill to obtain fine polymer particles of the present invention. iq
The particle size of the polymer fine particles obtained was measured using a particle size distribution analyzer (Coulter counter model TA-■, Q-I Q Q Q
, manufactured by Coulter Electric Inc), and I! 11, more than 95% of particles had a particle size of 20~
It was in the range of 50μ. In addition, the 1q polymer fine particles were mixed with unsaturated polyester resin (manufactured by Nippon Shokubai Chemical Co., Ltd., ■
When added and mixed with Borac G-105), the dispersibility was very good, and no separation occurred even after being left at room temperature for one month.

Example 2 Into the same reaction vessel as used in Example 1, 200 parts of water was charged, and while stirring, 3 parts of partially saponified polyvinyl alcohol with a degree of saponification of 87 to 89% and a degree of polymerization of 500 was added and dissolved. did. Next, a mixture consisting of 97 parts of acrylic butyl, 3 parts of trimethylolpropane]-remethacrylate, and 0.3 parts of azobisisobutyl nitrile was added dropwise thereto, and the mixture was purged with nitrogen and heated to 65°C for 4 days.

After the initiation of the reaction was confirmed by the generation of polymerization heat, the reaction was further continued at 70° C. for 2 hours to obtain a suspension of butyl acrylate crosslinked polymer. The percentage rate was 99.5%.

Meanwhile, 30 parts of melamine, 30 parts of benzoguanamine, 100 parts of 37% pomarin, and 0.4 part of 10% sodium carbonate aqueous solution were charged into the same reaction vessel as b used in Example 1, and the mixture was cooled to 80°C while stirring. After the reaction proceeded for 20 minutes at the same temperature, 325 parts of water was added to prepare an aqueous solution of melamine-benzoguanamine-formaldehyde initial condensate.

The above melamine-benzoguanamine-bormaldehyde was added to 100 parts of the suspension of the butyl acrylate crosslinked polymer obtained as described above. 70 parts of an aqueous solution of the IIJ condensate and 2 parts of 1N to dilute sulfur M were mixed, heated to 80°C with stirring, and further heated at 80°C for 3 hours. After the heat treatment, the same operations as in Example 1 were repeated to obtain fine polymer particles of the present invention.

More than 95% of the trI-treated polymer particles have a molecular weight of 10 to 30%.
It was a non-tacky white powder in the μ range.

In addition, 0.5% of the polymer fine particles prepared by 1!7 was added to polypropylene pellets, a molded plate with a thickness of IM was made using an injection molding machine, and the dispersion state of the polymer fine particles was observed using a microscope. It was confirmed that the spherical particles were uniformly dispersed.

Example 3 Into the same reaction vessel as used in Example 1, 300 parts of water was charged, and while stirring, 3 parts of partially saponified polyvinyl alcohol with a degree of saponification of 87 to 89 mol% and a degree of polymerization of 500 and sodium dodecylbenzenesulfonate were added. 1 part was added and dissolved. Next, a mixture consisting of 190 parts of 2-ethylhexyl acrylate, 10 parts of 1-limethylolbroban trimethacrylate, and 1 part of benzoyl peroxide was added dropwise thereto, and after purging with nitrogen, the temperature was set at 75°C. After the reaction started due to the generation of polymerization heat, it continued for another 3 hours at 80
The reaction was carried out at 19°C, and a suspension of the 1-syl acrylate crosslinked polymer in 2-ethyl was heated to 19°C. The 15% ratio was 99.7%.

On the other hand, in the same reaction vessel as B used in Example 1, 3 urea
0 parts, 80 parts of 37% formalin, 0.2 parts of 10% sodium carbonate aqueous solution, and 1 part of 28% ammonia aqueous solution were charged, heated to 60°C with stirring, and after proceeding with the reaction for 10 minutes at the same temperature, water was added. 298 parts were added to obtain an aqueous solution of the initial urea-formaldehyde sulfate.

150 parts of the aqueous solution of the urea-formaldehyde Hatsutomo condensate and 5 parts of sulfamic acid were mixed with 100 parts of the suspension of the 2-ethyl to 4-syl acrylate crosslinked polymer prepared as above and stirred. The temperature was raised to 70℃ while
It was further heat-treated at 80°C for 3 hours. After the heat treatment, the same operation as in Example 1 was repeated to obtain 19 fine polymer particles of the present invention. 95% or more of the obtained polymer fine particles have a concentration of 5 to 1
It was a non-tacky white powder in the 5μ range.

In addition, the polymer fine particles prepared by i and 9 were added to vinyl chloride resin by 1
% was added, and a sheet 1 with a thickness of 0.5 tea was made using a press molding machine, and when the dispersion state of the polymer fine particles was observed using a microscope, it was found that spherical particles of about 5 to 15 μ were uniformly dispersed. I was able to confirm the matter.

Comparative Example 1 1 in Example 1! The resulting suspension of butyl acrylate polymer was immediately filtered without heat treatment in the presence of the melamine-formaldehyde precondensate and dodecylbenzenesulfonic acid, and the polymer cake was taken out and heated at 100°C.
It was dried for 5 hours in a hot air drying mold. The dried polymer cake obtained in Example 17 was a sticky lump that could not be broken into small pieces by simple force, and could not be made into fine polymer particles as obtained in Example 1 using a hammer mill. Furthermore, when the polymer cake was observed under a microscope, it was observed that the polymer particles were fused together.

Comparative Example 2 The suspension of the butyl acrylate cross-linked polymer obtained in Example 2 was immediately heated in the presence of a melamine-benzoguaminane-formaldehyde initial condensate and sulfur without manual heat treatment. Polymer K-4- was taken out by filtration and dried in a hot air dryer at 100°C for C5 hours. The polymer powder obtained by drying is a sticky lump that cannot be broken into small pieces by the force of the cylinder, and is converted into fine polymer particles in a hammer mill as shown in Example 2-17. I couldn't do that. Furthermore, when the polymer cake was examined under a microscope, it was observed that the polymer particles were fused together.

Roughly, using the obtained polymer cake, a polypropylene molded plate was made in the same manner as in Example 2, and when the dispersion state of the small aggregate particles was observed under a microscope, it was found that the particles were large and fused together. 'J1 was confirmed to be distributed as a block.

Claims (1)

[Claims] 1. An amino compound-formaldehyde initial condensate and an acid catalyst are mixed into a suspension obtained by suspension polymerizing a vinyl polymerizable monomer in an aqueous medium in the presence of a protective colloid. Polymer fine particles obtained by heat-treating, separating from the suspension, and drying. 2. The polymer fine particles according to claim 1, wherein the protective colloid is polyvinyl alcohol.