JP2866657B2 - Microcapsule composition - Google Patents

Description

The present invention relates to a microcapsule composition. More specifically, the present invention relates to an organic solvent-based microcapsule composition having improved dispersibility.

[Conventional technology]

The pressure-sensitive copying paper is a sheet (CB paper) coated with microcapsules of a non-volatile organic solvent containing a colorless dye precursor having electron donating properties, and a sheet coated and dried with an aqueous coating composition containing an acidic developer. The microcapsules are broken by the printing pressure of a ballpoint pen, a typewriter, etc., with the application surfaces of (CF paper) facing each other, so that the dye precursor solution that has flowed out comes into contact with the color developer to develop color. .

Normally, pressure-sensitive copying paper has one or both of the above two components applied to the entire surface of the paper. Therefore, desensitizing ink is printed and applied to portions where copying is not desired so as not to color the portions, thereby preventing color formation. On the contrary, a method of printing and applying only a desired portion to one or both of the above two components, a so-called “spot printing method” is known.

At present, compounds having a lactone ring in the molecule such as triphenylmethanephthalide such as crystal violet lactone (CVL), fluoran and azaphthalide are used as a dye precursor, and phenol resins are used as a color developing agent. A polyvalent metal modified phenol resin, an aromatic carboxylic acid or a polyvalent metal salt thereof are used.

[Problems to be solved by the invention]

As long as the microcapsules can be applied only to the necessary parts in the spot printing method, pressure coated paper coated on the entire surface is not required,
Desensitization with desensitizing ink is no longer required, and it is an advantageous printing method from the viewpoint of resource saving, energy saving and cost saving such as reduction of the amount of expensive dye precursor and solvent used, and various attempts have been made in the past. .

However, when the microcapsules are to be partially printed on the paper by the spot printing method, the following problem occurs.

Generally, a microcapsule liquid is produced using water as a dispersion medium.A water-soluble or water-dispersed adhesive and an additive are added to form an aqueous microcapsule printing ink and spot printing is performed on paper. Not only requires a lot of energy for drying, but also tends to cause wrinkles and dimensional changes due to expansion and contraction of the paper at the spot printing portion.

In the case where an organic solvent such as benzene, toluene, xylene, cyclohexane, hexane, ligroin, ethyl acetate, methyl acetate, and methyl ethyl ketone is used instead of water as the ink solvent, drying is quick, and paper wrinkles are less likely to occur. Since the mixing with the liquid is not good, the microcapsules need to be once solidified in the form of a powder, and further redispersed in these organic solvents to obtain a printing ink. However, this redispersion is not easily dispersed in these organic solvents because the microcapsules are a hydrophilic dispersion system that is easily dispersed in water.

Among the organic solvents, it is preferable to use a hydrophilic organic solvent such as methanol, ethanol, or isopropyl alcohol. However, when the mixing ratio with the microcapsule solution becomes a certain value or more, the dispersion of the microcapsules is broken, and the viscosity increases or agglomerates.

Therefore, the spot printing method of such a microcapsule printing ink has not become widespread, and a method of printing a desensitizer at a predetermined position on the entire surface of the coated paper of the color developer is mainly used when providing a portion where copying is not desired. ing.

However, the method of printing a desensitizer on the entire coated paper from the top further uses an expensive chemical substance, and there is a strong demand for improvement in terms of resource saving, energy saving and cost saving.

[Means for solving the problem]

The present inventors have conducted intensive studies to solve the problems of the printing ink containing such microcapsules, and as a result, by using a specific compound, it is suitable for a spot printing method meeting the above-mentioned object. The inventors have found that a microcapsule composition can be obtained, and have reached the present invention.

That is, the present invention provides a synthetic resin microparticle containing a hydrophobic substance obtained by dissolving a phosphate compound in a hydrophobic organic solvent, further adding a synthetic resin microcapsule liquid containing a hydrophobic substance, and azeotropically dehydrating the solution. An organic solvent-based microcapsule composition comprising a capsule, a hydrophobic organic solvent, and a phosphate compound is provided.

The present invention is characterized in that a highly hydrophilic microcapsule composition comprising a hydrophobic organic solvent-based high concentration and excellent stability is obtained by using a phosphate compound.

As the phosphate compound used in the present invention,
For example, those represented by the general formula (I) or (II).

(HO) PO (OR) ₂ (I) (HO) ₂ PO (OR) (II) (wherein R is a C ₁ -C ₁₈ alkyl group) Specific examples of such a phosphate compound include: Methyl acid phosphate, isopropyl acid phosphate, butyl acid phosphate, dibutyl acid formate, monobutyl formate, 2-ethylhexyl acid phosphate, di-2-ethylhexyl formate, phenyl acid phosphate, isodecyl acid phosphate , Monodecyl phosphate, tridecyl acid phosphate, octyl phenyl acid phosphate,
Dilauryl phosphate, tridecanol azide phosphate, tricetyl acid phosphate, tristearyl acid phosphate and the like can be mentioned. These can be used alone or in combination of two or more.

The hydrophobic substance in the present invention is a phthalide derivative, a fluoran derivative, an acylleucophenothiazine derivative, a leukotrial methane derivative, a leucoindol methane derivative, a spiropyran derivative, a phthalimidine derivative, etc. What is dissolved in a hydrophobic high boiling point solvent such as terphenyl chloride is used.

Since a synthetic resin microcapsule containing a hydrophobic substance used in the present invention uses an organic solvent as a solvent, it preferably has a microcapsule membrane wall having excellent solvent resistance.

For example, JP-A-53-84881, JP-A-53-84882, JP-A-60-88
As described in JP-A-28819 and JP-A-60-216838, microcapsules using a urea formaldehyde resin or a melamine formaldehyde resin as a membrane material and JP-A-61-4018
As described in JP-A No. 8 (1996), a micropolymer comprising a radical polymer of a monomer component comprising an unsaturated double bond (for example, acrylonitrile, acrylamide, acrylate ester, N, N-methylenebisacrylamide as a cross-linking agent) as a film material. Capsules and the like.

As the hydrophobic organic solvent used in the present invention, toluene,
Examples thereof include aromatic hydrocarbons such as xylene, and hydrocarbons such as hexane, n-heptane and mineral spirit, and these solvents may be used alone or in combination, and may be mixed with water depending on the case.

The composition ratio of the microcapsule composition of the present invention is generally in the range of 2 to 30 parts by weight of the phosphoric ester compound and 30 to 100 parts by weight of the organic solvent per 100 parts by weight of the microcapsules.

The microcapsule composition of the present invention can be obtained by mixing and dissolving a phosphate compound in a hydrophobic organic solvent, adding a microcapsule solution, and removing water from the system by azeotropic dehydration.

A printing ink can be produced by using an adhesive, a protective material, a stilt as a buffer material, and the like, if necessary, for the microcapsule composition of the present invention.

Examples of the adhesive include natural resin and modified rosin such as shellac, rosin, hydrogenated rosin, rosin ester, and maleic acid-modified rosin as a modified natural resin, or petroleum resin, nitrated cotton, ethylene-malein as a synthetic resin. Acid resins, styrene-maleic acid resins, modified alkyd resins, phenolic resins, ethylene-vinyl acetate polymers, vinyl chloride-vinyl acetate polymers, acrylic resins, synthetic rubbers, and the like.

As the stillt, cellulose powder, wheat, corn, potato, sweet potato, starch manufactured from raw materials such as tapioca, oxidized starch obtained from them and an oxidizing agent,
Examples include starch derivatives such as esterified starch, etherified starch and aldehyde starch represented by acetylated starch, starch particles such as modified starch, and stilts for preventing pollution such as particles of talc, calcium carbonate and polystyrene resin. Other additions of pigments, thickeners, waxes, etc., as required, can be used without any problem for the purpose of improving the physical properties of the ink.

The printing ink containing the microcapsule composition prepared by the above combination is used to produce a printing paper in which microcapsules are partially applied by spot printing by a normal printing method, for example, a printing method such as flexographic printing, screen printing, gravure printing or the like. It is possible to do.

〔Example〕

Production Example 5% aqueous solution of acrylic acid, acrylonitrile, 2-acrylamido-2-methylpropanesulfonic acid copolymer
120 parts of a 10% NaOH aqueous solution was used to adjust the pH to 4.0, and 3% by weight of crystal violet lactone was dissolved in phenylxylylethane (Nippon Petrochemical "Hisol SAP-29").
6) Add 130 parts and emulsify with a homomixer.
After adding 24 parts of a wt% methylated methylolmelamine aqueous solution (Mitsui Toatsu Chemical “Euramine T-30”), the mixture is stirred at 80 ° C.
For 2 hours to obtain a microcapsule solution having an average particle size of 5.0 μm.

Example 1 After 300 parts of toluene and 10 parts of dioctyl phosphate were added to form a mixed solution, 100 parts (solid content) of the microcapsules obtained in Production Example were added, and water was removed by azeotropic dehydration.

When the microcapsule solution was observed with a microscope, the microcapsule particles were individually dispersed and no aggregation was observed.

In this microcapsule solution, 10 parts of Marquid 32 (maleic acid resin, Arakawa Chemical Co., Ltd.) was dissolved, and cellulose powder 20 was dissolved.
Parts were mixed to obtain a gravure ink.

This gravure ink was spot-printed with a sheet-fed gravure printing machine to obtain an upper sheet for pressure-sensitive copying paper.

When the upper sheet was combined with a commercially available lower sheet for pressure-sensitive copying paper, coloration was excellent.

When the printed surface of the upper paper was observed with a scanning electron microscope, no destruction of the microcapsules was observed.

Comparative Example 1 When 260 parts of ethanol was added to 100 parts (solid content) of the microcapsules produced in the Production Example, the viscosity increased, and when ethanol was further added, the dispersion was broken and aggregation occurred.

Comparative Example 2 The microcapsules produced in the Production Examples were powdered using a spray drying apparatus.

Observation of the powder microcapsules with a microscope revealed that the microcapsule particles aggregated into giant particles.

The powder microcapsules were placed in toluene and dispersed, but the aggregated particles were not loosened.

〔The invention's effect〕

As is clear from the above results, according to the present invention, the use of a phosphate ester compound in obtaining an organic solvent-based microcapsule composition increases the viscosity of the microcapsule solution even in a hydrophobic organic solvent-based, disperse breakage and micro-encapsulation. A stable microcapsule composition without aggregation of capsule particles is obtained.

Printing Ink By applying the present invention, a printing ink containing microcapsules which is easy to produce and has excellent dispersion stability and printability can be produced.

However, in the comparative example in which the phosphate compound is not used, it is difficult to stably disperse the microcapsules in the solvent, so that a practical printing ink cannot be obtained.

Claims (1)

(57) [Claims] 1. A synthetic resin microcapsule containing a hydrophobic substance, obtained by dissolving a phosphate compound in a hydrophobic organic solvent, further adding a microcapsule solution, and azeotropically dehydrating the organic compound and a phosphate ester. An organic solvent-based microcapsule composition containing a compound.