JP2000212367A - Surface-modified fine particles, production method and composition thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably modify the surface of a fine particle with a polyvinyl alcohol-based polymer regardless of the amount thereof. SOLUTION: Surface-modified fine particles obtained by reacting a fine particle having a functional group reactive with an amino group on the particle surface with a polyvinyl alcohol polymer having a primary or secondary amino group in the molecule.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to surface-modified fine particles, a method and a composition for producing the same, and more particularly, to fine particles whose surface is modified with a polyvinyl alcohol-based polymer and a method for producing the same.

[0002]

2. Description of the Related Art Fine particles whose surface is modified with a polyvinyl alcohol-based polymer are used as films, paints, resin modifiers, adhesives, and fiber processing agents because the polyvinyl alcohol-based polymer is extremely hydrophilic. It is expected that a very characteristic property will be exhibited in the case where it occurs. However, fine particles whose surface is modified with a polyvinyl alcohol-based polymer are obtained by emulsion polymerization of vinyl acetate or the like using a polyvinyl alcohol-based polymer as a dispersion stabilizer,
It is difficult to stably introduce a large amount of a polyvinyl alcohol-based polymer onto the surface of fine particles of a polymer composed of a (meth) acrylic acid derivative, a styrene derivative, a conjugated diene compound, and the like, and no method is known.

[0003]

DISCLOSURE OF THE INVENTION The present invention has been made in view of such prior art, and has as its object to provide fine particles having polyvinyl alcohol stably modified on the surface of the fine particles, a method for producing the same, and a composition thereof. Aim.

[0004]

The object of the present invention is to provide fine particles (A) having a functional group reactive with an amino group on the particle surface,
This is achieved by providing surface-modified fine particles that have been reacted with a polyvinyl alcohol-based polymer (B) having a primary or secondary amino group in the molecule.

Another object of the present invention is to provide the above-mentioned surface modification wherein the functional group reactive with an amino group is at least one functional group selected from an epoxy group, an oxazoline group, a carboxyl group, a carboxylic anhydride group and an isocyanate group. This is achieved by providing finely divided particles.

Further, the above-mentioned object is achieved by providing the above-mentioned surface-modified fine particles having a number average particle diameter of 0.01 to 100 μm.

Further, it is desired to react fine particles (A) having a functional group reactive with an amino group on the particle surface with a polyvinyl alcohol polymer (B) having a primary or secondary amino group in the molecule. This is achieved by providing a method for producing surface-modified microparticles that are characterized.

The present invention is also achieved by providing a method for producing the above-mentioned surface-modified fine particles, wherein the fine particles are obtained by emulsion polymerization or suspension polymerization.

Further, the above object is achieved by providing a composition comprising the above-mentioned surface-modified fine particles and a polyvinyl alcohol-based polymer.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The present invention relates to a fine particle (A) having a functional group reactive with an amino group on the particle surface, particularly preferably a fine particle (A) having a number average particle diameter of 0.01 to 100 μm measured by a dynamic light scattering method, Surface-modified fine particles reacted with a polyvinyl alcohol-based polymer (B) having a primary or secondary amino group, a method for producing the same, and a composition comprising the fine particles and a polyvinyl alcohol-based polymer.

The fine particles (A) used in the present invention preferably have a functional group reactive with an amino group on the particle surface, and are preferably fine particles produced by emulsion polymerization or suspension polymerization. Fine particles in which a functional group reactive with the polymer is unevenly distributed on the particle surface are more preferable. As a method of unevenly distributing a functional group to the particle surface by emulsion polymerization, a monomer (a1) containing a functional group reactive with an amino group and a And a method of increasing the ratio (a1 / a2) of the monomer (a2) having no functional group reactive with the polymerization with the progress of polymerization.

The amount of the monomer (a1) containing a functional group reactive with an amino group is from 0.1 to 30% of all monomers.
%, More preferably 0.2 to 20% by weight. Further, in order to make the functional group exist on the particle surface, after adding 90% by weight of all the monomers to the polymerization system, (a1) of the monomers added to the polymerization system is 1%.
It is preferably from 80 to 80% by weight, more preferably from 3 to 50% by weight.

As the monomer (a1) containing a functional group reactive with an amino group, glycidyl (meth) acrylate,
Allyl glycidyl ether, p-glycidyl styrene,
Epoxy group-containing monomers such as styrene-p-glycidyl ether; oxazoline group-containing monomers such as vinyl oxazoline; (meth) acrylic acid, itaconic acid, maleic acid,
Carboxyl group-containing monomer such as fumaric acid; carboxylic anhydride group-containing monomer such as maleic anhydride; methacryloyl isocyanate isocyanate group-containing monomer; and one or more of these are used. Can be. Among these, glycidyl (meth) acrylate,
It is preferable to use a monomer having an epoxy group such as allyl glycidyl ether.

The monomer (a2) containing no functional group reactive with an amino group includes methyl (meth) acrylate,
Ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, ( Meta)
2-ethylhexyl acrylate, cyclohexyl (meth) acrylate, hydroxyethyl (meth) acrylate,
(Meth) acrylates such as hydroxypropyl (meth) acrylate; styrene, α-methylstyrene, p
-Methylstyrene, p-tert-butylstyrene,
Aromatic vinyl compounds such as 3,4-dimethylstyrene, p-chlorostyrene, vinylnaphthalene and vinylanthracene; conjugated diene compounds such as butadiene, isoprene and chloroprene; vinyl esters such as vinyl acetate and vinyl pivalate; N-methyl Imide monomers such as maleimide and N-phenylmaleimide; nitrile monomers such as (meth) acrylonitrile; amide monomers such as (meth) acrylamide and maleic amide; ethylene, propylene, n Α-olefins such as -butene; vinyl ethers such as ethyl vinyl ether and butyl vinyl ether; heterocyclic vinyl compounds such as vinyl pyrrolidone; and the like, and one or more of these can be used.

As the monomer (a2) having no functional group reactive with an amino group, a polyfunctional monomer can be used in combination, if necessary. Examples of these monomers include ethylene glycol di (meth) Acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth)
Di (meth) acrylates such as acrylate, neopentyl glycol di (meth) acrylate, dimethylol tricyclodecane di (meth) acrylate, glycerin di (meth) acrylate; trimethylolpropane tri (meth) acrylate, pentaerythritol tri ( Tri (meth) acrylates such as meth) acrylate; tetra (meth) acrylates such as pentaerythritol tetra (meth) acrylate; polyfunctional aromatic vinyl compounds such as divinylbenzene and trivinylbenzene; allyl (meth) acrylate and vinyl Examples include two or more different ethylenically unsaturated bond-containing compounds such as (meth) acrylate, and one or more of these can be used. The polyfunctional monomer is composed of all monomers (a1 + a
2% or less, preferably 8% by weight or less.
And more preferably 5% by weight or less.

The emulsion polymerization or suspension polymerization can be carried out by a known method. The polymerization initiator at this time is not particularly limited, and examples thereof include hydrogen peroxide, potassium persulfate, sodium persulfate, ammonium persulfate, benzoyl peroxide, lauroyl peroxide, dicumyl peroxide, and di-t-butyl peroxide. Peroxides such as oxide, cumene hydroperoxide, t-butyl hydroperoxide and diisopropylbenzene hydroperoxide; 2,2'-azobisisobutyronitrile, 2,2 '
Azo compounds such as -azobis- (2,4-dimethylvaleronitrile), azobiscyanovaleric acid, and 2,2'-azobis- (2-amidinopropane) dihydrochloride. Further, a redox initiator system using a reducing agent and, if necessary, a chelating agent together with the polymerization initiator may be used. Examples of the reducing agent include alkali metal formaldehyde sulfoxylates such as Rongalit (sodium sulfoxylate formaldehyde);
Sulfites such as sodium sulfite and sodium bisulfite; pyrosulfites such as sodium pyrosulfite; thiosulfates such as sodium thiosulfate; phosphites such as phosphorous acid and sodium phosphite; sodium pyrophosphite and the like Mercaptans; ascorbic acids such as ascorbic acid and sodium ascorbate; erythorbic acids such as erythorbic acid and sodium erysorbate; sugars such as glucose and dextrose; ferrous sulfate, copper sulfate and the like. Metal salts and the like. Examples of the chelating agent include sodium pyrophosphate and ethylenediaminetetraacetate. These are used in appropriate amounts depending on the combination of the respective initiator systems.

The polyvinyl alcohol polymer having a primary or secondary amino group in the molecule (B) used in the present invention may be a polyvinyl alcohol polymer having a primary or secondary amino group in the molecule. There are no particular restrictions. Examples of the method for producing the polyvinyl alcohol polymer (B) having an amino group include: (1) an ethylenically unsaturated monomer having a primary amino group or a secondary amino group, or a primary amino group or A method in which an ethylenically unsaturated monomer having a functional group capable of forming a secondary amino group is copolymerized with vinyl acetate and then saponified; (2) a monomer having an epoxy group such as allyl glycidyl ether; (3) polyvinyl alcohol by reacting a mercaptan having an amino group with an epoxy group in a side chain of a polymer obtained by copolymerizing a polymer and vinyl acetate with sodium hydroxide or the like as a catalyst; A compound having a functional group capable of reacting with a hydroxyl group of an alcohol in a molecule and having a primary or secondary amino group is reacted with a polyvinyl alcohol-based polymer. That method; (4) in the presence of a polyvinyl alcohol polymer having a mercapto group, a method of polymerizing an ethylenically unsaturated monomer having a primary or secondary amino group; and the like.

The polyvinyl alcohol-based polymer (B) is
Even if the molecule has a functional group other than the primary or secondary amino group, it does not matter as long as the effect of the present invention is not impaired.
Examples of the monomer unit that provides such a functional group include ethylene, isobutylene, acrylonitrile, methacrylonitrile, acrylic acid, methacrylic acid, fumaric acid, (anhydride)
Maleic acid, (anhydride) itaconic acid, allylsulfonic acid,
Methallylsulfonic acid, vinylsulfonic acid, acrylamide-2-methylpropanesulfonic acid, methacrylamide-2-methylpropanesulfonic acid, sulfopropyl acrylate, sulfopropyl methacrylate, and their alkali salts, acrylamide, methacrylamide, trimethyl -(3-acrylamido-3-dimethylpropyl) -ammonium chloride, ethyl vinyl ether,
Examples thereof include butyl vinyl ether, N-vinylpyrrolidone, vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene fluoride, and tetrafluoroethylene. Further, a polymer having a functional group at a terminal obtained by polymerizing a vinyl ester monomer such as vinyl acetate in the presence of a thiol compound such as thiolacetic acid or mercaptopropionic acid may be used.

The content of the primary or secondary amino group of the polyvinyl alcohol polymer (B) is not particularly limited.
Although the preferred range varies depending on the degree of polymerization and the like, generally, the content of the nitrogen atom derived from the amino group is 0.05 to 5% by weight based on the total weight of the polyvinyl alcohol-based polymer.
And more preferably 0.1 to 3% by weight. The content of nitrogen atoms derived from amino groups is 0.05
When the amount is less than the weight percentage, the reactivity of the amino group with the fine particles having a reactive functional group is reduced, and the surface of the fine particles is not sufficiently modified. On the other hand, when the content of the nitrogen atom derived from the amino group exceeds 5% by weight, the reactivity between the amino group and the fine particles having a reactive functional group is too high, and the system tends to gel during the reaction.

The saponification degree of the polyvinyl alcohol-based polymer (B) is preferably at least 50 mol%, more preferably at least 60 mol%, even more preferably at least 70 mol%. When the saponification degree is less than 50 mol%, the hydrophilicity of the polyvinyl alcohol-based polymer is small, and the surface modification effect is insufficient. The molecular weight of the polyvinyl alcohol-based polymer is determined by measuring the intrinsic viscosity in dimethyl sulfoxide (JIS).
The viscosity average molecular weight calculated from is preferably 200,000 or less, more preferably 100,000 or less. If the molecular weight exceeds 200,000,
When the content of the nitrogen atom derived from the amino group exceeds 5% by weight, the reactivity between the amino group and the fine particles having a reactive functional group is too high, and the system tends to gel during the reaction.

The weight of the polyvinyl alcohol-based polymer (B) having a primary or secondary amino group in the molecule with respect to the fine particles (A) having a functional group reactive with an amino group on the particle surface is 100 g of (A). On the other hand, (B) 0.1 to 50 g
Is preferred, 0.5 to 30 g is more preferred, and 1 to 20 g
g is more preferred.

The reaction between the fine particles (A) having a functional group reactive with an amino group on the particle surface and the polyvinyl alcohol polymer (B) having a primary or secondary amino group in the molecule is carried out, for example, by emulsion polymerization. After (A) is produced by the method described above, (B) can be added to the polymerization system, followed by stirring at room temperature or under heating. The thus-obtained fine particles whose surface has been modified with a polyvinyl alcohol-based polymer have their surface modified very stably, and have various excellent properties, for example, as shown in Examples described later. Solvent resistance.

The composition of the present invention comprising fine particles whose surfaces are modified with a polyvinyl alcohol-based polymer and a polyvinyl alcohol-based polymer can be obtained by subjecting (I) the surface-modified fine particles and the polyvinyl alcohol-based polymer to an aqueous solution. A method of mixing in a medium, (II) reacting fine particles having a functional group reactive with an amino group with an amino group-containing polyvinyl alcohol polymer in the presence of a polyvinyl alcohol polymer containing no amino group. It can be obtained by a method or the like.
The weight ratio between the fine particles whose surfaces are modified with a polyvinyl alcohol-based polymer and the polyvinyl alcohol-based polymer is preferably such that the ratio of the surface-modified fine particles / polyvinyl alcohol-based polymer is from 1/99 to 99/1. , 5/9
It is more preferably 5 to 95/5, and
More preferably, it is 90/10. Since the fine particles whose surfaces are modified with polyvinyl alcohol are well mixed with polyvinyl alcohol, a uniform and transparent flexible film can be obtained as is clear from the examples described later.

The surface-modified fine particles of the present invention and the composition comprising the surface-modified fine particles and a polyvinyl alcohol-based polymer can be used by adding conventionally known additives, if necessary. . For example, a polyvinyl acetate emulsion, an ethylene-vinyl acetate copolymer emulsion, an aqueous emulsion of a composition comprising the surface-modified fine particles or the surface-modified fine particles of the present invention and a polyvinyl alcohol-based polymer, and the like. ) Acrylate (co) polymer emulsions, styrene-butadiene copolymer emulsions, epoxy emulsions,
Various resin emulsions such as urethane emulsion; N-
Various organic solvents such as methylpyrrolidone, toluene, perchrene, dichlorobenzene, trichlorobenzene; starch, modified starch, oxidized starch, sodium alginate, carboxymethylcellulose, methylcellulose,
Hydroxymethylcellulose, maleic anhydride / isobutylene copolymer, maleic anhydride / styrene copolymer,
Water-soluble polymers such as maleic anhydride / methyl vinyl ether copolymer; urea / formalin resin, urea / melamine /
Thermosetting resins such as formalin resin and phenol / formalin resin; fillers such as clay, kaolin, talc, calcium carbonate, and wood flour; bulking agents such as flour; reaction accelerators such as boric acid and aluminum sulfate; titanium oxide Various additives such as a pigment, an antioxidant, an ultraviolet absorber, an antifoaming agent, a leveling agent, an antifreezing agent, a preservative, and a rust preventive can be added.

The surface-modified fine particles of the present invention, and the composition comprising the surface-modified fine particles and a polyvinyl alcohol-based polymer, take advantage of the fact that the particle surface is extremely hydrophilic, and thus the film, paint, resin modification, etc. It can be used as a filler, an adhesive, a fiber processing agent, and the like.

[0026]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

The abbreviations relating to the compounds used in the following Examples are shown below. BA: butyl acrylate MMA: methyl methacrylate GMA: glycidyl methacrylate HDDA: 1,6-hexanediol diacrylate ALMA: allyl methacrylate SDOSS: sodium dioctyl sulfosuccinate KPS: potassium persulfate

<< Production of Amino Group-Containing Polyvinyl Alcohol >> [Reference Example 1] A reaction vessel equipped with a reflux condenser was charged with 405 parts of vinyl acetate monomer and allyl glycidyl ether 1
1 part and 30 parts of methanol were weighed out, and after sufficiently purging the inside with nitrogen, an initiator solution obtained by dissolving 4.5 parts of 2,2′-azobisisobutyronitrile in 15 parts of methanol was added. After polymerization at 60 ° C for 4 hours, the polymerization was stopped by cooling. The solid content concentration at this time was 54.8%. Next, unreacted vinyl acetate monomer was removed while occasionally adding methanol at 30 ° C. under reduced pressure, and a methanol solution of a polyvinyl acetate copolymer (solid content: 4%) was obtained.
4.5%). Next, 100 parts of the methanol solution of the polyvinyl acetate copolymer was weighed into a reaction vessel equipped with a reflux condenser, and the inside was sufficiently purged with nitrogen. Then, 8.0 parts of 2-aminothiophenol and water were added. Sodium oxide
A solution in which 0.03 part was dissolved in 48 parts of methanol was added, and reacted at 50 ° C. for 2 hours. Then, 10% concentration
Of methanol solution of sodium hydroxide was added and left at 40 ° C. for 5 hours to carry out a saponification reaction. The obtained reaction product was pulverized, neutralized by adding 8 parts of acetic acid, and then neutralized with methanol using a Soxhlet extractor.
After washing for 8 hours or more, followed by drying at 60 ° C. for 20 hours or more, a primary amino group-containing polyvinyl alcohol (hereinafter, referred to as amino group-modified PVA) was obtained. According to IR and 1H-NMR measurements of the amino group-modified PVA, the epoxy group had completely disappeared, nitrogen atoms derived from the amino group were introduced at 0.67% by weight, and the saponification degree was 9%.
It was confirmed to be 9.0 mol%. Amino group modified P
Intrinsic viscosity measurement of VA in dimethyl sulfoxide (J
IS) and the viscosity average molecular weight was calculated.
It was 0000.

Reference Example 2 In Reference Example 1, a vinyl acetate copolymer was obtained using 350 parts of a vinyl acetate monomer and 24.4 parts of allyl glycidyl ether to obtain 28 parts of 2-aminothiophenol and sodium hydroxide. 1
A primary amino group-containing polyvinyl alcohol (hereinafter, referred to as amino group-modified PVA) was obtained in the same manner as in Reference Example 1 except that the reaction was carried out at 0 part. Amino group-modified PV
The IR and 1H-NMR measurements of A confirmed that the epoxy group had completely disappeared, that a nitrogen atom derived from the amino group had been introduced at 1.77% by weight, and that the degree of saponification was 88.5 mol%. Was done. The intrinsic viscosity measurement (JIS) of the amino group-modified PVA in dimethyl sulfoxide was performed to calculate the viscosity average molecular weight, which was 15,000.

<< Production of Surface-Modified Fine Particles >> [Example 1] SDOSS 0.1.
75 g, 0.15 g of sodium hydrogen carbonate and 430 g of distilled water were weighed and heated to 80 ° C., and the inside of the system was sufficiently purged with nitrogen. Then, 12.82 g of BA, HDDA
0.405 g, ALMA 0.270 g and SDOS
S 0.135 g of the mixture (monomer) and KPS
An aqueous solution (initiator) in which 0.054 g was dissolved in 3.0 g of distilled water was dropped into the flask from a separate dropping funnel over 20 minutes, and after the completion of the dropping, the mixture was kept for 30 minutes to drive the polymerization. Thereafter, 117.85 g of BA,
Mixture (monomer) of 2.430 g of HDDA, 1.215 g of ALMA and 1.215 g of SDOSS
And an aqueous solution (initiator) obtained by dissolving 0.122 g of KPS in 15.0 g of distilled water was dropped into the flask from separate dropping funnels over 120 minutes.
The mixture was held for one minute to drive the polymerization. Next, BA 1
0.5 g, GMA 4.5 g and SDOSS 0.0
75 g of the mixture (monomer) and KPS 0.023
g dissolved in 2.0 g of distilled water (initiator)
Was dropped into the flask from separate dropping funnels over a period of 40 minutes, and further maintained for 30 minutes after completion of the dropping to complete the polymerization, thereby obtaining an emulsion having an epoxy group introduced on the particle surface. The number average particle size of this emulsion was 100 nm as measured by the dynamic light scattering method. 15 g of the PVA obtained in Reference Example 1 was added to this emulsion using distilled water 1
An aqueous solution dissolved in 35 g was added, and the mixture was stirred at 80 ° C. for 60 minutes to carry out a reaction, thereby obtaining an emulsion whose particle surface was modified with PVA. This emulsion is centrifuged,
Analysis of the amount of unreacted PVA indicates that the added PVA
, Which was almost quantitatively and stably reacted. The resulting emulsion was cast to obtain a film, which was immersed in acetone at 20 ° C. for 5 hours to obtain an area swelling ratio of the film [(area after immersion−area before immersion) / before immersion. Area × 100] and elution rate [(weight before immersion−weight after immersion) / weight before immersion × 100]
Was measured. As a result, the area swelling rate was 150% and the elution rate was 1
It was 0%.

Example 2 In a flask equipped with a cooling tube, SD
OSS 0.207 g, sodium bicarbonate 0.18
g and 400 g of distilled water were weighed and heated to 80 ° C., and the inside of the system was sufficiently purged with nitrogen. Then, BA15.
39g, HDDA 0.486g, ALMA 0.324
g and SDOSS 0.065 g (monomer), and an aqueous solution (initiator) obtained by dissolving 0.065 g of KPS in 3.0 g of distilled water were dropped into the flask from separate dropping funnels over 20 minutes, and further dropped. 30 after the end
The mixture was held for one minute to drive the polymerization. Then BA
138.51 g, HDDA 4.374 g, ALMA
A mixture (monomer) of 2.916 g and 0.583 g of SDOSS and 0.146 g of KPS were added to distilled water 1
An aqueous solution (initiator) dissolved in 5.0 g was dropped into the flask from a separate dropping funnel over 150 minutes, and after the completion of the dropping, the mixture was held for 60 minutes to drive the polymerization.
Next, 14.4 g of MMA, 3.6 g of GMA and SD
A mixture (monomer) of 0.072 g of OSS and KP
An aqueous solution (initiator) obtained by dissolving 0.018 g of S in 2.0 g of distilled water was placed in a flask from a separate dropping funnel.
The mixture was added dropwise over 0 minutes, and further maintained for 30 minutes after completion of the addition to complete the polymerization, thereby obtaining an emulsion having an epoxy group introduced on the particle surface. The number average particle diameter of this emulsion was 250 nm as measured by a dynamic light scattering method.
10 g of PVA obtained in Reference Example 2 was added to this emulsion.
Was dissolved in 90 g of distilled water, and the mixture was stirred at 80 ° C. for 60 minutes to carry out a reaction, thereby obtaining an emulsion having a particle surface modified with PVA. When this emulsion was centrifuged and the amount of unreacted PVA was analyzed, it was 3% of the added PVA, and it was almost quantitatively and stably reacted. The obtained emulsion was cast to obtain a film, which was immersed in acetone at 20 ° C. for 5 hours. As a result, the area swelling rate was 180% and the elution rate was 12%.
%Met.

Comparative Example 1 In Example 1, PVA was used.
The reaction was carried out in the same manner as in Example 1 except that unmodified polyvinyl alcohol containing no amino group (molecular weight: 40,000, saponification degree: 98.8 mol%) was used instead of When this emulsion was centrifuged and the amount of unreacted PVA was analyzed, it was 99% of the added PVA and almost no reaction occurred. When this emulsion was centrifuged to analyze the amount of unreacted PVA,
This was 3% of the added PVA, and the reaction was almost quantitatively performed. The obtained emulsion was cast to obtain a film, which was immersed in acetone at 20 ° C. for 5 hours. As a result, the area swelling ratio was 300% and the elution ratio was 21%.

Comparative Example 2 A reaction was carried out in the same manner as in Example 1 except that GMA was not used. The emulsion is centrifuged to remove unreacted PVA
The amount of PVA was 100% of the PVA added, and no reaction was observed. When this emulsion was centrifuged and the amount of unreacted PVA was analyzed, it was 3% of the added PVA, and it was almost quantitatively reacted. The obtained emulsion was cast to obtain a film, which was immersed in acetone at 20 ° C. for 5 hours. As a result, the film dissolved.

<< Production of Composition Comprising Surface-Modified Fine Particles and Polyvinyl Alcohol Polymer >> [Example 3] 100 g of the particle surface-modified emulsion obtained in Example 1 was added to unmodified polyvinyl alcohol ( (Molecular weight 40,000, degree of saponification 98.8 mol%)
An aqueous solution of 20 g dissolved in 80 g of distilled water was added and mixed. The 100 μm-thick film obtained by casting the obtained aqueous solution of the composition at a temperature of 50 ° C. was a uniform transparent and flexible film.

Example 4 In Example 1, PVA was used.
With unmodified polyvinyl alcohol (molecular weight 4
The reaction was carried out in the same manner as in Example 1 except that 15 g of the polymer was used. The 100 μm-thick film obtained by casting the obtained aqueous solution of the composition at a temperature of 50 ° C. was a uniform transparent and flexible film.

Comparative Example 3 The procedure of Example 3 was repeated, except that the emulsion having an unmodified particle surface was used instead of the emulsion having a modified particle surface. To obtain an aqueous solution of the composition. The 100 μm-thick film obtained by casting the resulting aqueous solution of the composition at a temperature of 50 ° C. was a soft, but non-uniform, slightly cloudy, and translucent one having an aggregated portion.

[0037]

According to the present invention, the surface of the fine particles can be stably modified with the polyvinyl alcohol-based polymer regardless of the amount thereof, and the obtained fine particles, and the fine particles and the polyvinyl alcohol-based polymer can be used. The composition is a polyvinyl alcohol-based polymer is extremely hydrophilic,
It is useful as a film, paint, resin modifier, adhesive, fiber processing agent and the like.

 ──────────────────────────────────────────────────の Continued on the front page F term (reference) 4F070 AA46 AC80 AE30 BA08 BB02 DB10 DC12 DC13 4J002 AC02X AC09X BB04X BB14X BB17X BC04X BC08X BC09X BC11X BC13X BE02W BE04X BF01X BF02X BG01X BG04X BG04X BG04X BG04X BG04X BG04X BG04X GJ01 GK02 4J031 AA12 AA13 AA15 AA16 AA17 AA20 AA22 AA23 AA25 AA29 AB02 AC07 AC08 AC09 AD01 AF10 AF12 AF13 AF16 AF30

Claims (6)

[Claims] 1. Surface modification by reacting fine particles (A) having a functional group reactive with an amino group on the particle surface with a polyvinyl alcohol-based polymer (B) having a primary or secondary amino group in the molecule. Particles. 2. The surface-modified surface according to claim 1, wherein the functional group reactive with the amino group is at least one functional group selected from an epoxy group, an oxazoline group, a carboxyl group, a carboxylic anhydride group and an isocyanate group. Fine particles. 3. The fine particles having a number average particle size of 0.01 to 1
The surface-modified fine particles according to claim 1 or 2, which have a diameter of 00 µm. 4. A method comprising reacting fine particles (A) having a functional group reactive with an amino group on the particle surface with a polyvinyl alcohol-based polymer (B) having a primary or secondary amino group in the molecule. A method for producing surface-modified fine particles. 5. The method for producing surface-modified fine particles according to claim 4, wherein the fine particles are obtained by emulsion polymerization or suspension polymerization. 6. A composition comprising the surface-modified fine particles according to claim 1 and a polyvinyl alcohol-based polymer.