JPH06246151A - Microcapsule - Google Patents

Abstract

PURPOSE:To provide microcapsules excellent in compatibility with a resin and dispersibility and capable of satisfactorily controlling various catalytic functions of a quat. phosphonium salt as the core material in an ordinary environment. CONSTITUTION:Each of the objective microcapsules has a quat. phosphonium salt as the core material and a coating film of an aggregate of a fine particle- shaped org. polymer with inorg. fine particles carried on the surface.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a microcapsule body containing a quaternary phosphonium salt. The microcapsule body of the present invention is easily mixed with a low molecular weight compound, a resin or a resin composition (hereinafter referred to as “resin etc.”), and is suitable as a catalyst for the condensation reaction or oxidation reaction or a phase transfer catalyst. It is used and has the function of enhancing smooth reaction and pot life.

In particular, when the microcapsule body of the present invention is blended with an epoxy resin, the curing reaction can be controlled to suppress the reaction as much as possible at a low temperature, and a rapid reaction can be caused at a high temperature, so that the storage stability is good. An epoxy resin composition exhibiting high reactivity at high temperature can be obtained.

[0003]

2. Description of the Related Art It is known that quaternary phosphonium salts act as catalysts for resin condensation reactions, oxidation reactions or phase transfer catalysts. However, the quaternary phosphonium salt has a markedly poor compatibility and dispersibility with respect to resins and the like, and since this compound has high reactivity and is difficult to control, it is difficult to handle in processing, However, it has the drawback of producing a non-uniform reaction.

On the other hand, since the quaternary phosphonium salt has poor compatibility with resins and the like and is also poorly soluble in water as described above, it is difficult to produce a microcapsule body containing this compound by an ordinary method. It was

[0005]

The quaternary phosphonium salt has poor compatibility and dispersibility when blended with a resin or the like, and it is difficult to control the reaction, so that a heterogeneous reaction easily occurs. It is difficult to handle in the process of processing, and this is a problem to be solved.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventor has found that a quaternary phosphonium salt is formed by using a film made of an aggregate of finely divided organic polymers carrying inorganic fine particles on the surface. The inventors have found that they can be microencapsulated and have completed the present invention.

The elements of the microcapsule body of the present invention will be described below. (1) Organic Polymer As the organic polymer used in the present invention, conventionally known thermoplastic resins and thermosetting resins can be used, but those which are easily emulsified in water are preferred. Examples of such an organic polymer include acrylonitrile-butadiene rubber, acrylic rubber, styrene-butadiene rubber or ethylene-vinyl acetate rubber; or vinyl chloride resin, vinylidene chloride resin, fluorine resin, silicone polymer or styrene-acryl. Examples thereof include acid copolymers.

The fine-particle organic polymer having the fine inorganic particles supported on the surface thereof is obtained by, for example, emulsion-polymerizing a monomer constituting the above-mentioned organic polymer by a usual method, and the fine-particle organic polymer obtained has inorganic fine particles on the surface thereof. Can be carried to obtain.
At this time, it is preferable that the surface of the fine particle polymer and the inorganic fine particles have a sufficient affinity. For example, in order to support colloidal silica as inorganic fine particles on the surface of the fine particle polymer, the surface of the fine particle polymer may be modified by the presence of silanol groups. There are various methods for producing a finely divided organic polymer having a surface modified as described above, but those obtained by the core-shell type emulsion polymerization method have high stability in an emulsified state, and when encapsulated. The film-forming property is good, which is preferable.

In the core-shell type emulsion polymerization method, an emulsion of an organic polymer serving as a core is formed in advance, and then a monomer as a raw material of a polymer serving as a shell is added to the emulsion to carry out copolymerization. You can get it. As a surfactant used for forming an emulsion of an organic polymer serving as a core, an anionic surfactant, particularly a derivative of sodium sulfonate or sodium sulfate can be used to obtain an organic polymer having a large molecular weight. It is possible and preferable. The particle size of the core organic polymer is 0.05
˜1.0 μm is preferable. The organic polymer component serving as the core is preferably contained in an amount of 10 to 90% by weight, more preferably 50 to 9 of the obtained core-shell type polymer.
It is 0% by weight. If it is less than 10% by weight, the characteristics of the organic polymer itself are not sufficiently exhibited when it is formed into a microcapsule film, which is not preferable.

Monomers which are the raw materials of the shell polymer are acrylonitrile, methacrylonitrile, N
-Vinylpyrrolidone or N-vinylcaprolactam;
Used in combination with three components of an alkoxysilane having an acryloxy group, a methacryloxy group or a vinyloxy group; and another monomer having a vinyl group such as styrene, vinyltoluene, methyl (meth) acrylate or ethyl (meth) acrylate. It is preferable that a stable emulsion of polymer particles is easily formed.

Specific examples of the alkoxysilane having an acryloxy group, a methacryloxy group or a vinyloxy group include γ-acryloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane and γ- (meth) acryloxypropyltris. (Trimethylsiloxy) silane, vinyltrimethoxysilane,
Examples thereof include vinyltris (methoxyethoxy) silane and vinyltrichlorosilane.

Another method for producing a surface-modified fine particle organic polymer is to produce an emulsion of an organic polymer, and add a silane coupling agent, titanate coupling agent or aluminum silane coupling agent to the emulsion. There is a method of adding and reacting.

(2) Inorganic Fine Particles The inorganic fine particles used in the present invention can be used as long as the diameter is 50 μm or less. However, when they are in a colloidal form in which ultrafine powder is dispersed in water, It is preferable because it can be easily supported on the surface of the modified fine particle organic polymer. Examples of such inorganic fine particles include colloidal silica, alumina sol, zirconia sol, antimony oxide sol, tin oxide sol, silica having a diameter of 50 μm or less, or alumina powder.

The method of supporting the inorganic fine particles on the surface of the fine particle organic polymer is, for example, an emulsion of the above organic polymer in which the above inorganic fine particles are directly or dispersed in an aqueous medium and the surface is modified as described above. A method of gradually adding it with stirring is preferred. At this time, the system is 40 ~
It is preferable to heat to 60 ° C. because loading is easily performed.

The combined ratio of the organic polymer emulsion and the inorganic fine particles is adjusted according to the properties required for the final microcapsule film, but it is 2 in the total amount of the organic polymer component and the inorganic component in the emulsion. It is general that about 98% by weight is the organic polymer component, preferably 2
It is 0 to 90% by weight. If it is less than 2% by weight, the performance of the organic polymer in the film does not appear, and if it exceeds 98% by weight,
The dispersibility of the fine particle organic polymer during microencapsulation is not preferable, which is not preferable.

The fact that the inorganic fine particles are supported on the surface of the fine particle organic polymer means that, for example, in the case of an organic polymer having high tackiness, a film is formed from an organic polymer emulsion before and after supporting the inorganic fine particles, and It can be confirmed by measuring the presence or absence of a significant decrease in the tackiness of.

(3) Core Material The quaternary phosphonium salt used as the core material in the present invention is
It is a compound represented below. R ₄ P ⁺ X ⁻ Here, R represents an alkyl group, a phenyl group or a derivative having these in the skeleton, and X represents a halogen atom.

Specific examples include tetrabutylphosphonium bromide, tetraphenylphosphonium bromide, ethyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide and benzyltriphenylphosphonium chloride.
Of these, tetraphenylphosphonium bromide and benzyltriphenylphosphonium chloride are preferred because of their high reactivity with resins and the like.

Since the quaternary phosphonium salt is a fine powdery compound having extremely low solubility in water, it has poor dispersibility when directly added to an aqueous medium in the encapsulation process, but the compound is once added to a basic sol or water glass. In the medium, the compound is kneaded or pulverized to obtain a dispersion of the compound in the form of fine particles, which is easily added to the aqueous medium in the encapsulation step. It can be dispersed as a fine powder in an aqueous medium. Specifically, it can be made into fine particles by dispersing in an alumina sol, water glass or aluminum lactate sol and then kneading with a ball mill. At this time, the positively charged alumina sol also acts as an aggregating agent for solidifying the negatively charged fine particle organic polymers in the encapsulation step.

(4) Encapsulation method The above core material is dispersed in an aqueous medium, and an aggregating agent for aggregating the particulate organic polymer, particularly preferably a positively charged alumina sol, is added, and subsequently, under high agitation. Then, an emulsion of an organic polymer carrying inorganic fine particles on the surface is added little by little.

If necessary, a deionizing agent such as an amphoteric ion exchanger is added and stirring is continued to form a composite film of an organic polymer and inorganic fine particles on the core material to obtain a microcapsule slurry. At this time, it is better to heat when the film forming temperature of the organic polymer is high. The use of a deionizing agent, the formation of the composite film gradually progresses to facilitate encapsulation, and at the same time, the generated slurried capsule body can remove the leaching ionic compound from the vicinity of the interface between the core material and the film,
This is a preferred method because the elution of the core material from the capsule body can be further prevented.

When fine particle antimony oxide is allowed to exist in the slurry capsule body, dust explosion of the obtained fine powder capsule body can be prevented, which is safe in handling.

When the slurry is filtered to remove coarse particles and then applied to a spray drier, fine powdery microcapsule bodies are obtained.

[0024]

The microcapsule body of the present invention is obtained by encapsulating the core material while aggregating an emulsion of an organic polymer having inorganic fine particles supported on its surface with an aggregating agent. A practical capsule body having a tetraphosphonium salt as a core material could be obtained. Further, since the microcapsule body of the present invention covers the quaternary phosphonium salt with a dense composite film composed of an inorganic and an organic polymer, it is easily dispersed in a resin or the like, and has a catalytic function under a normal environment. Can be sufficiently suppressed.

The microcapsule body of the present invention is softened and expanded by heating above the glass transition point (Tg point) of the organic polymer forming the film, and as a result, it is the core material. It is considered that the tetraphosphonium salt is opened to the outside and exerts a function as a catalyst. By adjusting the Tg point of the polymer, it is possible to prevent the film from being destroyed at about the temperature of the heat roll when the capsule is mixed with the resin or the like.

[0026]

EXAMPLES The present invention will be described in more detail with reference to examples. Example 1 (Synthesis of core-shell type emulsion having silanol group) 1000 cc of pure water and Lebenol WZ (26 of sodium polyoxyethylene alkylphenyl ether sulfate) were placed in a stainless steel autoclave having an internal volume of 2 liters.
Wt% aqueous solution, manufactured by Kao Corporation) 19.2 g, potassium persulfate 2.5 g, tertiary dodecyl mercaptan 1.0 g,
Butyl acrylate 250 g and butadiene 250 g
Was charged with stirring with a propeller type stirring blade at 350 rpm,
The reaction is carried out at 50 ° C for 15 hours, and then Lebenol WZ
19.2 g, potassium persulfate 0.5 g, styrene 60
g, 30 g of acrylonitrile and 10 g of NUC silane monomer A-171 (vinyltrimethoxysilane, manufactured by Nippon Unicar Co., Ltd.) were added, and emulsion polymerization was continued at 70 ° C. for 5 hours.

The resulting emulsion was a styrene / acrylonitrile copolymer having silanol groups in the shell portion, with butyl acrylate / butadiene copolymer rubber particles as the core, and the solid content was 36% by weight. .

(Preparation of fine particle dispersion of tetraphenylphosphonium bromide) 300 g of tetraphenylphosphonium bromide, alumina sol 200 (positively charged alumina sol having a particle size of 30 to 100 μm, concentration 10% by weight, manufactured by Nissan Chemical Industries, Ltd.) 380g and pure water 10
A magnetic ball mill having an internal volume of 5 liters was charged with 00 g, and wet pulverized at room temperature at 300 rpm for 12 hours to obtain a dispersion liquid.

(Support of Inorganic Fine Particles) One 660 g of an organic polymer emulsion having a silanol group on the surface is used.
Charge into a liter beaker and use a propeller-type stirring blade for 200
With stirring at rpm, 2 g of 2,4,7,9-tetramethyl-5-decyne-4,7 diol was added as an antifoaming agent, and then Snowtex UP (solid content 20% by weight, diameter 5
An aqueous sol of elongated colloidal silica having a length of 20 μm and a length of 40 to 300 μm. Nissan Chemical Industries, Ltd.) 23
0 g was gradually added, and stirring was continued at 40 to 45 ° C. for 1 hour to obtain a preparation liquid.

(Synthesis of Microcapsule Body) Internal Volume 12
In a liter mixing tank, 8 liters of pure water and 1440 of the fine particle dispersion of tetraphenylphosphonium bromide.
g at a temperature of 400 rpm with a propeller-type stirring blade at room temperature.
With stirring, 381 g of the organic polymer emulsion having the above-mentioned inorganic fine particles supported on the surface was added over 1 hour. Next, ion exchange resin Amberlite IRN-150 (mixed ion exchanger of cation and anion having sulfonic acid and quaternary amine group. Particle size 0.40 to 1.19).
mm beads. 390 g of Organo Co., Ltd. was added and stirring was continued at 50 ° C. for 3 hours.

The obtained slurry-like mixture was passed through a 80-mesh filter cloth to remove coarse particles, and then passed through a disc-type spray dryer to be dried.
2 μm tetraphenylphosphonium bromide 62.
A fine powder microcapsule body containing 7% by weight and having a composite film of 37.3% by weight made of a butadiene copolymer, silica and alumina was obtained.

(Preparation of Epoxy Resin Composition) Epoxy equivalent 190, 100 parts by weight of epoxy resin having a softening point of 80 ° C.,
80 parts by weight of a phenol equivalent of 130 as a curing agent, 50 parts by weight of a phenol novolac resin having a softening point of 80 ° C., 150 parts by weight of spherical fused silica having a particle diameter of 3 to 120 μm as an inorganic filler, and 1.6 parts by weight of the above microcapsule body,
The mixture was melt-mixed for 3 minutes with a hot roll at ˜90 ° C., cooled, and ground.

(Curing Test) The obtained pulverized product was subjected to a JSR type curast meter to measure the curing start time at 100 ° C., the curing start time at 190 ° C. and the curing completion time. The results are shown in Table 1.

Comparative Examples 1 to 3 Instead of the capsule body, the above tetraphenylphosphonium bromide itself was used, and the above epoxy resin 10 was used.
Table 1 shows the results of carrying out similar experiments under the same conditions except that 1, 2 and 3 parts by weight were used with respect to 0 parts by weight.

Example 2 The same amount of benzyltriphenylphosphonium chloride was used in place of the tetraphenylphosphonium bromide used in Example 1, and the encapsulation was performed under the same conditions as in Example 1 except that the particle size was 3 A fine powdery microcapsule body was obtained which contained 62.2% by weight of benzyltriphenylphosphonium chloride having a particle size of ˜15 μm and had a composite film of 37.8% by weight made of a butadiene copolymer, silica and alumina. The results of evaluating the microcapsule body in the same manner as in Example 1 are shown in Table 1.

Comparative Examples 4 to 6 Benzyltriphenylphosphonium chloride itself was used instead of the capsule body in an amount of 1, 2 and 3 parts by weight based on 100 parts by weight of the epoxy resin, and the other conditions were the same. The results of similar experiments are shown in Table 1.

[0037]

[Table 1]

[0038]

INDUSTRIAL APPLICABILITY The microcapsule body of the present invention is excellent in compatibility and dispersibility with respect to resins and the like, and sufficiently suppresses the chemical reaction accelerating property of the core quaternary phosphonium salt under a normal environment. Therefore, the pot life is improved, and the effect as a catalyst for a condensation reaction or an oxidation reaction or a phase transfer catalyst can be exhibited for the first time under the conditions of use, for example, at a high temperature. INDUSTRIAL APPLICABILITY The microcapsule body of the present invention can remarkably enhance the industrial utility of various organic reactions.

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Claims (1)

[Claims] 1. A microcapsule body obtained by coating a quaternary phosphonium salt with a film made of a particulate organic polymer having inorganic fine particles supported on the surface thereof.