JPH0463128A - Microcapsule and pressure-sensitive manifold paper using microcapsule - Google Patents

Abstract

PURPOSE:To remarkably improve heat resistance and solvent resistance by incorporating o-tolidinediisocyanate so that it comprises 1-90wt.% of the whole polyvalent isocyanate. CONSTITUTION:A microcapsule consists of an oily core material and a principal wall film consisting of a high polymer product of polyvalent isocyanate compound and a compound having active hydrogen. Further, as the polyvalent isocyanate compound, 1-90wt.% of o-tolidinediisocyanate and 10-99wt.% of polyvalent isocyanate compound having the other structure are combinedly used. This microcapsule can be used, e.g. for pressure-sensitive manifold paper.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to thermally stable microcapsules and pressure-sensitive copying paper using the microcapsules.

(Prior art) Microcapsules are made by emulsifying and finely dispersing a core substance and coating it with a back wall membrane, and are suitable for stably retaining unstable or liquid substances, such as pharmaceuticals, agricultural chemicals, and fragrances. It has applications in adhesives, dyes, liquid crystals, etc., but its most well-known use is in pressure-sensitive copying paper.

Traditionally, microcapsule manufacturing methods include complex coacervation method, interfacial polymerization method, and in situ polymerization method.
Methods such as in situ polymerization and mechanochemical methods are known, and each has advantages and disadvantages. Although the interfacial polymerization method for manufacturing microcapsules is characterized by a simple manufacturing method, the capsule wall membrane is thin and the membrane quality is porous and poor in density, resulting in microcapsules of thermally unstable quality. It has the disadvantage of being stored away. Many polyvalent isocyanate compounds are known that can be used to produce microcapsules using interfacial polymerization. For example, JP-A-57-140638, JP-A-64-728
MDI-based polyisocyanate compounds such as diphenylmethane-4,4-diisocyanate, polymethylene polyphenyl diisocyanate, and 3-3-dimethyldiphenylmethane diisocyanate described in JP-A-86; TD such as 2-6 tolylene diisocyanate and 2-4) lylene diisocyanate described in Publication No. 120633/1982
I-series polyvalent isocyanate compounds, JP-A-60-2278
Hexamethylene diisocyanate, propylene-1,2 diisocyanate, butylene-1,2 diisocyanate described in Publication No. 28
- Aliphatic polyisocyanate compounds such as diisocyanates, 1.1. I.

- Adducts of polyvalent isocyanate compounds and polyol compounds such as trimethylolpropane and tolylene diisocyanate 3-molecule adducts and 1.1.1 trimethylolpropane and hexamethylene diisocyanate 3-molecule adducts, JP-A-55-159990 A vinylet conjugate of three molecules of xamethylene diisocyanate, tolylene diisocyanate and hexamethylene diisocyanate 3 described in the publication
Molecular incyanurate bonded structures and the like are known.

However, microcapsules produced by interfacial polymerization using these materials alone or in combination have major drawbacks, such as RtlS, in which the capsule wall is thin, porous, and thermally unstable. For example, when a certain microcapsule is used as a microcapsule for pressure-sensitive copying paper, unexpected damage may occur due to destruction of the microcapsule during the coating and drying process of paint, printing of form paper, etc., or during normal handling and transportation of the product. This will cause color development and significantly reduce its commercial value.

(Problems to be Solved by the Invention) The present invention provides thermally stable microcapsules produced by an interfacial polymerization method using a polyvalent isocyanate compound and a compound having active hydrogen.

(Means for Solving the Problems) The present invention uses o-tolidine diisocyanate as a polyvalent isocyanate compound in a range of 1 to 90% of all polyvalent isocyanates.
The feature is that the content is % by weight, and this makes it possible to dramatically improve the heat resistance and solvent resistance of the microcapsules. o-) Lysine diisocyanate is generally produced by reacting 0-tolidine with phosgene.

0-) Polyvalent isocyanate compounds having other structures used in combination with lysine diisocyanate are:
Any type of isocyanate can be used as long as it is soluble in the oily liquid that is contained in the capsule, and typical examples include those having the structure described in the prior art section above.

A general method for producing the microcapsules of the present invention will be described below.

1) o-) Lysine diisocyanate and a polyvalent isocyanate compound having another structure used together with the target substance to be encapsulated are dissolved in an oily medium to prepare an oily core material.

2) Prepare an emulsified aqueous solution in which a compound having active hydrogen and an emulsifying/protective colloid agent are dissolved.

3) Emulsify and disperse the oily core substance from 1) above into the emulsified aqueous solution from 2).

4) At the interface between the oily core substance and the emulsified aqueous solution, a polyvalent isocyanate compound and a compound having active hydrogen are reacted to form a film and encapsulation is performed.

It consists of the above four steps.

In the case of microcapsules for pressure-sensitive copying paper, the target substance to be encapsulated is often an electron-donating color former;
Of course, it is also possible to manufacture microcapsules that do not contain an electron-donating coloring agent, and in this case, the microcapsules are used in combination with ordinary microcapsules for pressure-sensitive copying paper, as described in JP-A-62-267184. Therefore, it can also be used as a pollution prevention material.

Specific compounds of the electron-donating color former, which is a dye for pressure-sensitive copying paper, include 3.3-bis-(p-dimethylaminophenyl)-6-dimethylaminophthalide (crystal violet lactone); -bis-(dimethylamino)10-benzoylphenothiazine, di(N-methyl-N-phenylanilino)-rubazolylmethane, 3-
Diethylamino-6-methyl-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-0-
Examples include phenyl-dimethylanilinofluorane.

Oil-based media for dissolving dyes for pressure-sensitive copying paper include:
Diarylalkane such as phenylxyl ethane, phenyl xylyl methane, phenylethyl phenylethane, phenyl butylphenyl methane, alkyl biphenyls such as isopropylbiphenyl, butylbiphenyl, and partially hydrogenated terphenyl, such as diisopropyl naph9'J. At least one species such as Al-lunaphthalene is used as the main solvent.

As the emulsifying/protective colloid agent, water-soluble polymers such as polyvinyl alcohol, gum arabic, gelatin, carboxymethyl cellulose, casein, ethylene maleic anhydride copolymer, acrylic acid copolymer, etc. can be used.

As the compound having active hydrogen, known compounds can be used. Polyvalent amines such as ethylenediamine, diethylenetriamine, hexamethylenediamine, triethylenetetramine, piperazine, amine adducts of epoxy compounds,
These include polyhydric alcohols such as catechol, resorcinol, 1.2 hydroxy-4-methylbenzene, bisphenol A, ethylene glycol, 1.3 flopylene glycol, 4-butylene glycol, and chrycerin, and water.

(Function) The reason why the heat resistance and solvent resistance of the capsule wall film are dramatically improved by the present invention is not clear, but the capsules of a polymer compound produced by the reaction of a polyvalent isocyanate compound and a compound having active hydrogen are This is believed to be because the film becomes dense and thick due to the addition of o-tolidine diisocyanate.

Next, the present invention will be explained by examples. In addition, in the following examples, % and parts are weight % and parts by weight.

(Example) After dissolving 3 g of crystal violet lactone (CVL) as an electron-donating coloring agent in 82 g of a diarylalkane-based solvent (trade name: Hysol 5AS-296, manufactured by Nippon Petrochemical Co., Ltd.) In addition, 3 g of 0-tolidine diisocyanate and 12 g of MDI 3-molecule incyanurate conjugate polyvalent isocyanate compound (trade name Coronet 1-EH) were added as polyvalent isocyanate having other structures.
(manufactured by Nippon Polyurethane Co., Ltd.) was added and dissolved to obtain an oily core material.

This oily core material was added to 200 g of an emulsifying aqueous solution in which 4 g of polyvinyl alcohol (trade name Gohsenol GH-17 manufactured by Nippon Gohsei Co., Ltd.) was dissolved with vigorous stirring.
An 8μ O/W type emulsion was obtained. To this emulsion were added 15 ml of a 10% ethylenediamine aqueous solution and 15 ml of a 10% diethylenetriamine aqueous solution, and the mixture was stirred at room temperature for 15 minutes, and the temperature of the yarn was set at 65°C.

When reacted at this temperature for 1 hour, a polyurea resin was formed around the oily core material, yielding microcapsules for pressure-sensitive copying paper coated with the oily core material.

1 instead of 12g of Coronate EHO in Example 1
Microcapsules for pressure-sensitive copying paper were obtained in the same manner as in Example 1, except that 0 g of MDI vinylet-conjugated polyvalent isocyanate (trade name Sumidur N-3600, manufactured by Sumitomo Bayer Urethane) was used.

1" l instead of 12 g of Coronate EH in Example 1
Microcapsules for pressure-sensitive copying paper were prepared in the same manner as in Example 1, except that 7 g of tetraxylylene diisocyanate (trade name: Takene) m-TMDXDI (manufactured by Shikinichi Pharmaceutical Co., Ltd.) was used.

1 instead of 12 g of Coronate EH in Example 1
0 g of Sumidur and 6 g. - Microcapsules for pressure-sensitive copying paper were prepared in the same manner as in Example 1 except that tolidine diisocyanate was used.

To 80 g of carbon tetrachloride, 15 g of 0-tolidine diisocyanate, and 5 g of heliminethylene diisocyanate, 4 g of cinnamic aldehyde as a fragrance ingredient is added to obtain an oily core material. Add 4g of this oily core substance to Gohsenol GH-1.
The mixture was added to 200 g of an emulsifying aqueous solution in which 7 was dissolved, with vigorous stirring, to form an O/W type fractional dispersion with a diameter of 10 μm. Thereafter, perfume microcapsules were prepared in the same manner as in Example 1. This fragrance capsule had good heat and solvent retention properties.

Ratio] U-Uni: ± Same as in each example except that the 0-tolidine diisocyanate used in Examples 1 to 3 was not used and the amount of polyvalent isocyanate compound used in each example was 15 g, 13 g, 20 g, and 16 g. Microcapsules for pressure-sensitive copying paper were prepared.

The microcapsules for pressure-sensitive copying paper were evaluated as follows.

20 g of starch particles were added to 150 g of microcapsule slurries for pressure-sensitive copying paper obtained in Examples 1 to 4 and Comparative Examples 1 to 4, and water was added so that the concentration was 12%. In addition, a test paint was obtained. Apply this paint with a No. 12 Meyer bar for 40 minutes.
The sample was applied to a base paper of g/if at a solid content of 3.5 g/rd to prepare a sample for a heat resistance test.

In addition, this paint was applied in the same manner to the developer-coated surface of the lower paper to prepare a sample for the solvent resistance test.

Capsule surface and bottom paper of test piece for Nijiryo Indigo shell heat resistance test (N made by Jujo Paper Industries)
W40-B) with the developer side facing each other and stacked 80g/
A load of crrr was placed on it and it was left at a temperature of 105° C. for 2916 hours. The heat resistance of the capsule was determined by the degree of coloring of the bottom paper. The degree of coloring of the bottom paper was measured using a color difference meter manufactured by Tokyo Juishokusha (
The reflectance was measured using a Model TC-1500) and expressed as the difference from the whiteness of the lower paper before the test. The larger the difference, the worse the heat resistance.

After leaving the test piece for solvent resistance test in methyl cellosolve (oxyethyl methyl ether) saturated steam at 20°C for 1 hour, the stains on the colorant surface were determined as in the heat resistance test, and the whiteness before and after the test was Solvent resistance was indicated by the difference in .

The larger the difference, the worse the solvent resistance.

The test results are shown in Table-1. From Table 1, Examples 1 to 4 in which o-)lysine diisocyanate was used in combination as the polyvalent isocyanate were compared to Comparative Examples 1 to 4 in which only a single polyvalent isocyanate was used without o-tolysine diisocyanate in combination.
It can be seen that the heat resistance and solvent resistance are dramatically improved compared to No. 4.

Table 1 Test Results Example 1 Comparative Example 1 Example 2 Comparative Example 2 Heat Resistance 10.1 21.0 8.8 11.8 Solvent Resistance 12.5 26.8 9,8 18.0 Example 3 Comparison Example 3 Example 4 Comparative Example 4 Heat resistance 9,7 22.5 10.6 23.
5 Solvent resistance 13.7 27.7 15,7 2
9.1 (Effects) The heat resistance and solvent resistance properties, which are said to be disadvantageous in interfacial polymerization microcapsules using polyvalent isocyanates, are solved by the present invention. - By using a diisocyanate mixture containing toridine diisocyanate as a raw material for forming a capsule membrane, dramatic improvements have been made, and it has become possible to encapsulate materials to which the interfacial polymerization method cannot be applied conventionally due to its drawbacks.

Claims (3)

[Claims] (1) Microcapsules consisting of an oily core material and a polymer product whose main wall film is a polyvalent isocyanate compound and a compound having active hydrogen, with 1 to 90% by weight of o-tolidine diisocyanate as the polyvalent isocyanate compound. , 10 to 99% by weight of a polyvalent isocyanate compound having another structure. (2) an oily medium in which the oily core substance contains one or more of diarylalkanes, alkylnaphthalenes, alkylbiphenyls, or partially hydrogenated terphenyls;
The microcapsule according to claim 1, characterized in that the microcapsule is an oily core material containing o-tolidine diisocyanate in the oily medium at a solubility of not more than 1 part by weight per 100 parts by weight of the oily medium. (3) A pressure-sensitive copying paper having the microcapsules according to claim (2) on a support.