Method of making microcapsules

[Detailed Description of the Invention]

The present invention relates to the new manufacturing method of the microcapsule which includes a hydrophobic core substance. It is related with the method that the capsule excellent in especially the holdout of a capsule core substance can be manufactured very easily. It is cotton intermediary To have very broadly and in many fields noting that progress of microcapsule-ized art is remarkable and the use field of these microcapsule ghost will also begin carbonless copying paper in recent years. Although various kinds of methods, such as the coacervation method, the interface polymerizing method, and the in-situ polymerizing method, are known as a manufacturing process of a microcapsule, Since the microcapsule which has amino aldehyde pile condensation resin as wall membrane is especially excellent in water resistance, solvent resistance, etc., For example, a microcapsule-ized method which forms urea-formaldehyde pile condensation resin wall membrane under existence of a carboxymethyl cell rose (USP-3016308 No.), Various methods, such as a microcapsule-ized method (JP,47-23165,B) which forms urea-formaldehyde pile condensation resin wall membrane in the suspension which does not contain a dispersing agent substantially, are proposed. However, since deposition of heavy condensation resin on the capsule core substance surface is not efficiently made in this encapsulating method, the manufacture conditions, such as addition of dilution water, need to be controlled very careful. chemical [ as a dispersing agent ], for example, in order to increase the efficiency of deposition of heavy condensation resin on the capsule core substance surface -- it is -- carrying out -- the method (JP,37-12380,B) of using together the substance which has an active group which can perform physicochemical combination, The method (JP,38-12518,B, JP,48-4717,B, JP,49-13456,B) of using the phase separation by an electrostastic interaction, etc. are proposed. In these improved methods, not only [ however, ] need a complicated process like the encapsulating method using the conventional complex coacervation. Probably because the soluble constituent which has a heterogeneous electric charge in capsule wall films contains, the defect which produces a cracking crack of capsule wall films at the time of dryness accompanies. Without this artificer spoils the characteristic of amino aldehyde pile condensation resin in view of this present condition, And as a result of studying wholeheartedly deposition of heavy condensation resin on the capsule core substance surface about the method of making it increase in efficiency, it is under existence of cation denaturation polyvinyl alcohol (it outlines following PVA), It was which finds out that the capsule wall films which have the characteristic which is very efficient, and was moreover excellent in it when heavy condensation of the amino aldehyde resin was carried out are obtained, and requires it up for attaining the present invention. [ of deposition on the core substance surface of heavy condensation resin ] In the present invention, heavy condensation of the amino aldehyde resin is carried out in a hydrophilic medium which distributes a hydrophobic core substance and contains cation denaturation PVA. Therefore, it is a manufacturing process of a microcapsule Envelope(ing) the hydrophobic core substance surface. Cation denaturation PVA used in the present invention, If PVA which has a nitrogen atom which can present cationicity to a main chain or a side chain is meant, and introduction of the cationic machine to PVA is generally performed by copolymerization, graft polymerization, polymeric reaction, etc. and also it explains concretely, the method like the following will be mentioned, for example. (1) Organic acid vinyl ester, such as formic acid vinyl, acetic acid vinyl, and vinyl propionate, The acrylate or the methacrylate monomer containing a cationic machine, How to saponify a copolymer with the vinyl monomer containing cationic machines, such as vinyl ether containing a cationic machine, organic acid vinyl ester containing a cationic machine, N-N-Sial kill acryl amide, amino substitution styrene, and N-hetero ring content vinyl monomer. (2) How to carry out the partial saponification of the organic acid vinyl ester polymer and copolymer containing a cationic machine. (3) A method to which the hydroxyl group of polyvinyl alcohol is made to add the vinyl monomer containing cationic machines, such as N-N-Dimethyl acryl amide and N-N-Diethyl acryl amide. (4) Organic halide which has a cationic machine for the hydroxyl group of polyvinyl alcohol How to make it react to the polymeric reaction reagent which has cationic machines, such as epoxy compounds which have a cationic machine, ether which has a cationic machine, and aldehyde which have a cationic machine, and introduce a cationic machine by a polymeric reaction. (5) How to introduce an amino group simultaneously with saponification by processing the copolymerization thing or its solution of reaction monomers, such as VCM/PVC, and vinyl ester with amine, such as ammonia. Among various kinds of methods like the above, since especially the method of (3) can obtain cationic PVA to need by being stabilized easily, it is one of the desirable methods. Although the introductory rate of a cationic machine is suitably adjusted according to the kind of cationic machine, etc., it is desirable to introduce the cationic machine equivalent to 0.05~30-mol %, more preferably 0.2~10-mol% of all the monomer units. In the present invention, since the capsule which was further excellent in the holdout of a capsule core substance is obtained, cation denaturation PVA which has a hydrophobic radical in part is used especially preferably. A way introduction of the hydrophobic radical to cation denaturation PVA introduces a hydrophobic monomer unit at the time of cation denaturation PVA manufacture, Although the active hydrogen which cation denaturation PVA has can also be performed using a reaction peculiar to PVA(s), such as Acetal-izing of the method of canal-izing by alkylation reactions, such as methylation and ethylation, and also Formal-izing, formation of Acetoase tar, butyral-izing, etc., and lactonization in a molecule, Also economically by controlling saponification of a Organic acid vinyl ester copolymer with especially a cationic machine, the method of making a hydrophobic monomer unit remain directly by the manufacturing process of cation denaturation PVA is used advantageously and preferably. The hydrophobic radical introduced during cation denaturation PVA is although it is suitably chosen according to the capsule core substance which PVA obtained is a range which does not lose water solubility, and is used, especially -- hydrophobic radicals, such as hydrophobic monomer units, such as ethylene and propylene, a methyl group, an ethyl group, a Formal machine, a Acetoase tar machine, a butyral machine, and an acetyl group, -- 0.1~20-mol% more preferably of all the monomer unit, and 0.2~10-mol % -- introducing is desirable. Although this cation denaturation PVA is made to contain in a capsule manufacture hydrophilicity medium in the present invention, when the ease of capsule manufacture, the capsule quality obtained, etc. are taken into consideration, it is desirable in a hydrophilic medium 0.5 % of the weight or more, more preferably that you make it contain 2% of the weight or more. Although the maximum of content is generally adjusted by the viscosity of a system, the capsule preparation device used, etc., it is desirable to limit to 20% of the weight or less. About the amino aldehyde pile condensation resin used in order to Envelope the hydrophobic core substance surface in the present invention, For example, urea, thiourea, alkylurea, ethylene urea, acetoguanamine, Benzoguanamine, melamine, Granidine, dicyandiamide, biuret, The amine more than kinds, such as cyanamid, formaldehyde, acetaldehyde, The resin obtained by pile-condensing or Joint weight condensing the aldehyde more than kinds, such as paraformaldehyde, hexamethylenetetramine, butylaldehyde, crotonic aldehyde, benzaldehyde, and furfural, is meant, These are added into a hydrophilic medium in the state of a monomer or pre polymer, and a capsule manufacture system is constituted with a hydrophobic core substance and cation denaturation PVA. Since the capsule outstanding in the homogeneity of wall membrane and physical intensity is obtained, it is preferred to use especially in the state of Prepolymer. In the present invention, parts for a part of Copolycondensation composition other than amine and aldehyde can also be contained as occasion demands for the purpose of the property modification of amino aldehyde resin, etc. And this capsule manufacture system is adjusted to acidity, more preferably PH field of 2~6 as occasion demands, and the polycondensation reaction of amino aldehyde resin is advanced. In order to maintain a capsule manufacture system into acidity in that case, what is called an acid catalyst generally used, for example in the Like amino aldehyde resin manufacture fields, such as formic acid, acetic acid, citrate, oxalic acid, Paratoluenesulfon acid, chloride, sulfuric acid, nitric acid, phosphoric acid, ammonium chloride, and ammonium sulfate, is used. Since the polycondensation reaction of amino aldehyde resin is promoted by heating a system, it is preferred to heat a system to the temperature of 20~100 degreeC. Since the capsule which has the quality especially stable in the range of 35~70 degreeC is formed comparatively for a short time, it is desirable. Although the usual protection colloid agent, a surface-active agent, etc. can also be used together if needed in the capsule manufacture system of the present invention, it is necessary to limit the amount used to the range which does not check the effect of a request of the present invention. Without it requires very careful control of capsule manufacture conditions, such as addition of dilution water, in this way according to the method of the present invention, Capsule formation material is only mixed, and heavy condensation resin is efficient only by giving easy heavy condensation conditions, it deposits on the capsule core substance surface, and the microcapsule outstanding in capsule quality, such as core substance holdout, moreover is obtained. Although it is not clear about the cause by which this operation effect is obtained, cation denaturation PVA provides the place of a reaction and is considered to form advance of a polycondensation reaction, and the atmosphere which increases conjointly the efficiency of deposition on the capsule core substance surface of amino aldehyde pile condensation resin. Especially as a hydrophobic core substance included in a microcapsule in the present invention, although it does not limit, the substance like the following is illustrated. Like animal oil, such as fish oil and lard oil, olive oil, peanut oil, linseed oil, Like vegetable oil, such as soybean oil and castor oil, oil, kerosene, xylene, Like mineral oil, such as toluene, alkyl substitution diphenyl Alekan, Alkyl substitution naphthalene, diphenyl ethane, Phutar acid Dibutyl, It is a fluid of insolubility [ water ] insolubility or substantially in water like Like composition oil, such as salicylic acid methyl, The textiles-like substance like the oxide of the metal of insolubility [ water ], salts, cellulose, or asbestos, the synthetic polymer substance of insolubility [ water ], minerals, paints, glass, spice, spices, sterilization constituents, physiological constituents, manure constituents. In order to explain the method of the present invention more concretely below, an example is indicated about the case where it applies to the field of carbonless copying paper, but, of course, it is not limited to these. Unless it refuses in particular, the part in an example and % express a weight section and weight %, respectively. Example 1 19 copies of acetic acid vinyl, one copy of N-N-Dimethyl acryl amide, and 0.02 copy of alpha-alpha '-azobis isobutyronitrile were dissolved in ten copies of benzene, and it polymerized in 60 degreein nitrogen air current C for 24 hours. The obtained polymerization solution was put in superfluous petroleum ether, the copolymerization thing was taken out, and it saponifies and dried [ dissociated and ] by sodium hydroxide in methanol, and acquired 2.2 mol of saponification degree 99.9 mol % cationic machine content% of cation denaturation PVA. After adding three copies of urea, and 0.3 copy of resorcin to 100 copies of 3.5% solution of this cationic PVA, PH of the system was adjusted to 3.3 and it was considered as the water medium for capsule manufacture. 35 copies of solution which dissolved and obtained 2.8 copies of crystal violet lactone and 0.7 copy of benzoyl leucomethylene blue independently to 100 copies of Alkyl naphthalene (brand name KMC oil, the KUREHA chemicals company make) is isolated preparatively, Emulsification distribution was carried out into the above-mentioned water medium for capsule manufacture so that it might become the average particle diameter of 3.5 micro as a capsule core substance. Next, agitating loosely, after adding 7.5 copies of formaldehyde solution 37% into this system, it held to 70 degreeC for 3 hours, and obtained capsule dispersion liquid. Example 2 Ten copies of polyvinyl alcohol (degree-of-polymerization 1700 and degree % of 98 mol of saponification) is dissolved into 90 copies of deionized water, 9.1 copies of sodium hydroxide solution was added 10%, after adding 17 copies of N-N-Dimethyl acryl amide and making it react by 70 degreeC under churning for 3.5 hours, reprecipitation refining was carried out with methanol and 6.7 mol of cationic machine content% of cation denaturation PVA was acquired. PH of 100 copies of 5% solution of this cation denaturation PVA was adjusted to 2.8 to make the water medium for capsule manufacture. Subsequently, after carrying out emulsification distribution of the same capsule core substance as Example 1 so that it may become the average particle diameter of 4 micro, After adding the urea-formaldehyde-resins pre polymer solution obtained by making react for 1 hour by 70 degreeC which added three copies of urea to 7.5 copies of formaldehyde solution (PH8.0) 37% independently and also adding 0.3 copy of resorcin, it held by 65 degreeC for 3 hours, and obtained capsule dispersion liquid. Example 3 Used degree% of 88 mol of saponification (degree of polymerization 1700) of partial saponification PVA, it was made to react by 60 degreeC for 2.5 hours instead of PVA used in Example 2, and 11.2 mol of cationic machine content% of cation denaturation PVA was acquired. Capsule dispersion liquid were obtained completely like Example 2 except having used this cation denaturation PVA. Example 4 Instead of ten copies of PVA(s) used in Example 2, 10.8 copies of ethylene vinyl alcohol copolymers (degree %, degree of polymerization 1500 of 99.4 mol of ethylene 7.4 mol % and saponification) were used, and 7.3 mol of cationic machine content% of cation denaturation PVA was acquired. Capsule dispersion liquid were obtained completely like Example 2 except having used this cationic PVA. After cooling radiationally four kinds of capsule dispersion liquid obtained in Example 1~4 in this way, ten copies of cell rose powder and 50 copies of 20% oxidization starch solution were added, and capsule coating liquid was prepared. 40g/m²The amount of dry applications is 4g/m about capsule coating liquid on Base paper.²It was alike, and it applied and dried and created the upper lobe paper for carbonless copying paper so that it might become. Comparative example 1 The place completely carried out in a similar manner in Example 1 except having used commercial undenatured PVA (brand name Kuraray PVA217 and degree % of 88 mol of saponification) Kuraray Co., Ltd. make instead of cation denaturation PVA, When the capsule which has sufficient wall membrane intensity was not obtained but application dryness of the coating liquid was carried out on stencil paper, a capsule core substance was not able to flow out and it was not able to finish as upper lobe paper for carbonless copying paper. Independently, they are 15 copies of mix melting things (mix melting ratios 80/20) of 65 copies of aluminium hydroxide, 20 copies of zinc oxides, 3 and 5-Di (alpha-methylbenzyl) salicylic acid zinc, and a alpha-methylstyrene styrene copolymer, It is 40g/m about the coloration agent coating liquid which added 20 copies (solid content) of Carboxy denaturation styrene butadiene copolymer latex to the dispersion liquid which obtained five copies (solid content) of polyvinyl alcohol solution, and 300 copies of water by grinding them for 24 hours by the ball mill, and was prepared.²Dry weight is 5g/m to Base paper.²It was alike, and it applied and dried and created the lower lobe paper for carbonless copying paper so that it might become. To the opposite side of the coloration agent application side of the above-mentioned lower lobe paper, the above-mentioned capsule coating liquid was applied and dried like the case of upper lobe paper, and paper was created the middle for carbonless copying paper. The performance comparative test was done by the upper lobe paper obtained in this way and a method which is indicated below using paper and lower lobe paper in the middle, and the result was indicated to the 1st table. () Heat resistance Upper lobe paper and lower lobe paper are piled up so that an application side comrade may counter, and it is 5kg/cm.²Where Load is applied, it processed with the heat setting machine of 115 degreeC for 3 hours, and the degree of the coloring dirt of a coloration agent application side was judged. () Solvent resistance Paper was neglected in the saturation atmosphere of trichloroethylene under room temperature in the middle for 1 hour, and the degree of the coloring dirt of a coloration agent application side was judged. () Moisture resistance Three sheets of papers are piled up in the middle, and it is 5kg/cm.²Where Load is applied, it was neglected for three days in the atmosphere of 50degreeC and 90%RH, and the degree of the coloring dirt of the coloration agent application side of central middle paper was judged.

[Table]

O : it is slightly dirty. Each carbonless copying paper using the microcapsule obtained by the method of the present invention so that clearly from the result of the 1st table was excellent in heat resistance, solvent resistance, and moisture resistance.