JPH03202387A - Coloring agent sheet for non-carbon pressure-sensitive copying sheet - Google Patents

Abstract

PURPOSE:To obtain a coloring agent sheet for non-carbon pressure-sensitive copying sheet which doe not become colored during its storage and which colored image does not fade by adding an adduct of melamine/cyanuric acid to a coloring agent sheet and using synthetic resin for the capsule film of a microcapsule containing a coloring agent. CONSTITUTION:An adduct of melamine/cyanuric acid is an almost water- insoluble white fine powder crystal obtained by allowing melamine to react with cyanuric acid or isocyanuric acid. Sufficient effect can be obtained by mixing less than 30 pts.wt. of the adduct of melamine/cyanuric acid with 100 pts.wt. of microcapsule. If the adduct is 15 pts.wt., significant effects are seen and if the adduct is 5 pts.wt., some effect are seen. The micro-capsule containing a coloring agent has a capsule film consisting of synthetic resin. Synthetic resin capsule films should preferably be of such resin as polyurethane, epoxy, polyurea, urea-formalin or melamine-formalin from the viewpoint of humidity/ heat resistance and solvent resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Industrial Application Field The present invention relates to carbonless pressure-sensitive copying paper, and more particularly to microcapsules containing an electron-donating dye of a color former sheet for carbonless pressure-sensitive copying paper. The present invention relates to a coloring agent sheet for carbonless pressure-sensitive copying paper that prevents coloring of the coated surface due to light and the like and also prevents fading of colored images.

(B) Prior Art A carbonless pressure-sensitive copying paper using an electron-donating dye and an electron-accepting acidic substance is disclosed in, for example, US Pat. No. 2,505,489.
As described in detail in No. 4480052, basically, a color former sheet is coated with microcapsules containing an electron-donating dye (hereinafter referred to as a color former) dissolved in a high boiling point solvent. and electron-accepting acidic substances (hereinafter referred to as
It consists of a color developer sheet coated with a color developer (referred to as a color developer).

As a coloring agent, crystal violet lactone, 3
-3bis(P-dimethylaminophenyl)phthalide, 3
-(P-dimethylaminophenyl)=3-(2-methylindol-3-yl)-6=trialylmethanephthalide series such as dimethylaminophthalide and acyl derivatives such as methylene blue benzoyl, aminoyl, pivaloyl; There are xanthine phthalides such as 3-diethylamino-6-methyl-7-chlorofluoran and 3-diethylamine-7-sibenzylaminofluorane, which are also used in the present invention.

Examples of high boiling point solvents that dissolve color formers include alkylnaphthalenes such as diisopropylnaphthalene, diallylalkanes such as 1-phenyl-1-xylylethane, alkylbiphenyls such as isopropylbiphenyl, and other Aromatic hydrocarbons such as allyldimethanes, alkylbenzenes, benzylnaphthalenes, diallylalkylenes, and allylindanes; Carboxylic acid ester compounds represented by dibutyl phthalate, dioctyl maleate, etc.; Typical phosphoric acid ester compounds include: vegetable oils such as castor oil, soybean oil, and cottonseed oil, or their modified oils; high-boiling fractions of natural products (consisting of aliphatic hydrocarbons) such as mineral oils, etc.
Also used in the present invention.

Methods for producing microcapsules containing a coloring agent include generally well-known coacervation methods, in-situ methods, interfacial polymerization methods, and the like.

Examples of color developers include inorganic color developers such as acid clay, natural clay minerals such as attapulgide, activated clay obtained by treating acid clay with mineral acids, and semi-synthetic solid acids described in JP-A-57-15996. , various phenolic compounds, novolac type phenolic resins, polyvalent metal salts of aromatic carboxylic acids, and the recently proposed JP-A-63-18672 as organic color developers.
Polyvalent metallized salicylic acid resins described in No. 9 and No. 63-254124 have already been used.

Carbonless pressure-sensitive copying paper is produced by coating microcapsules containing a color former on the back side of a support such as paper, applying a dried color former sheet to the upper paper, applying a color developer to the surface of the support such as paper, and drying. The developed color developer sheet is used as the bottom paper, and when the coated surfaces of the top paper and the bottom paper are overlapped and printed under pressure using a writing or dot printer, the microcapsules in the pressure area are destroyed and the color developer and color developer that flow out are destroyed. Upon contact, a color reaction occurs and a colored image is obtained.

Furthermore, since carbonless pressure-sensitive copying paper requires and is required to make a large number of copies, microcapsules containing a color developer on the surface of a support such as paper and a color former on the back are coated, dried, A large number of copies can be made by combining a sheet containing a color developer and a color forming agent in one sheet as an inner sheet, and combining a large number of inner sheets such as upper sheet, middle sheet, middle sheet, etc., as shown in the lower sheet.

Also, self-coloring type carbonless pressure-sensitive copying paper, which is made by applying a coloring agent and a color developer to the same surface of a support such as paper, has also been put into practical use.

(C) Problems to be Solved by the Invention Carbonless pressure-sensitive copying paper is mainly used as slips and office paper.

Normally, an important property required when used as slips and office paper is that the surface coated with microcapsules containing a coloring agent is affected by sunlight, fluorescent light, indoor nitrogen oxides, etc. during storage. Examples include: no coloring caused by pen pressure, and little fading of the printed image on the developer-coated surface that develops color due to pen pressure, etc.

Conventionally, for example, as a method of preventing discoloration of color former sheets, countermeasures have been taken by mixing or dissolving fluorescent dyes, antioxidants, anti-aging agents, and ultraviolet absorbers in microcapsule coating layers or microcapsules. , fluorescent dyes, antioxidants, and anti-aging agents have the problem of not maintaining their preventive effects. In addition, in most cases, ultraviolet absorbers are dissolved in a high-boiling point solvent together with a color former and incorporated into microcapsules, but in general, in order to improve printing density, a large amount of color former is used, especially for black coloring. Therefore, the amount of coloring agent built into the microcapsules must be increased, and the solubility and/or usage amount of the ultraviolet absorber decreases (despite the black coloring agent sheet being easily colored). There was a problem that the coloring prevention effect was reduced.

On the other hand, as a method to prevent fading of the printed image on the color developer sheet, there is a method of mixing white pigments such as zinc oxide and titanium oxide in the color developer coating layer, but titanium oxide causes the colored image to tingle with chroma. In addition, in order to obtain the effect of zinc oxide, it was necessary to increase the amount added, which increased the degree of abrasion of the color developer coated surface and caused problems during printing. .

Accordingly, an object of the present invention is to provide an excellent color former sheet for carbonless pressure-sensitive copying paper, in which the surface coated with microcapsules is not colored and the colored image obtained on the color developer sheet is less likely to fade.

(D) Means for Solving the Problems As a result of extensive experiments and research, the inventors of the present invention have found that excellent color development for carbonless pressure-sensitive copying paper that does not cause coloring during storage and also reduces fading of colored images. We have developed a drug sheet.

That is, the present invention can be achieved by incorporating a melamine/cyanuric acid adduct into a coloring agent sheet, and it has also been found that remarkable effects can be obtained by using a synthetic resin as the capsule membrane of the microcapsules containing the coloring agent. Ta.

The production method of the melamine/cyanuric acid adduct used in the present invention is described in detail in JP-A-54-141792 and JP-A-56-32470. The reacted product is a white fine powder crystal that is almost water-insoluble. Generally, melamine/cyanuric acid adducts are used as flame retardants for polyester and polyamide fibers and resins, curing agents for epoxy resins, and fillers for polyolefin rubbers. The reason why this method is effective and also prevents fading of the colored image printed on the color developer sheet, which is colored by pressure of the pen, etc., is unknown at present.

The melamine/cyanuric acid adduct used in the present invention is sufficiently effective at 30 parts by weight or less per 100 parts by weight of microcapsules, extremely effective at 15 parts by weight, and effective from 5 parts by weight.

The microcapsule containing the coloring agent used in the present invention has a capsule membrane made of a synthetic resin, and is made of polyurethane, epoxy resin, polyurea, etc. from the viewpoint of heat and humidity resistance and solvent resistance.
Synthetic resin capsule membranes such as urea-formalin resin and melamine-formalin resin are preferred.

The present invention includes buffering agents such as wheat starch and pulp powder, starch, water-soluble polymeric binders such as polyvinyl alcohol,
A latex emulsion binder, which is a hydrophobic polymer such as styrene-butadiene, acrylic, or vinyl acetate, is used in combination with a dispersant, antifoaming agent, penetrating agent, and desalkalinizing agent for increasing pH, if desired. It will be done. After forming the coating liquid for the color former sheet, it is applied using an air knife coater, a three-roll coater, a one-bar coater, and a curtain coater.
By drying, the color former sheet of the present invention can be obtained.

(E) Examples Preferred embodiments and excellent effects of the present invention will be specifically explained below using the most typical examples. Note that all parts below are parts by weight, and all % represents weight %.

Example 1 200 parts of high boiling point oil (KMC-113 manufactured by Kureha Chemical Co., Ltd.) in which 7 parts of crystal violet lactone (CVL) was dissolved.
) to 5% styrene maleic anhydride copolymer aqueous solution (pH
5,0) and emulsified to have an average particle size of 6 μm.

Next, 20 parts of a 40% melamine-formalin initial condensate aqueous solution (Sumilets Resin, manufactured by Sumira Chemical Co., Ltd.) was added to the above emulsion, the temperature was brought to 75°C, and the mixture was reacted for 2 hours.
The pH was adjusted to 9.0 with an aqueous sodium hydroxide solution, and the mixture was cooled to room temperature to obtain a 40% microcapsule dispersion.

The 40% microcapsule dispersion thus obtained was used as a coating liquid for color former sheets in the following formulation. Apply this coating liquid to high-quality paper with a basis weight of 40 g/rd in an amount of 3.5 g/rd (
The mixture was coated with an air knife coater and dried to obtain a coloring agent sheet (absolutely dry solid content).

[Coating liquid for color former sheet]

40% microcapsule dispersion 250 parts Wheat starch 25 parts 10% polyvinyl alcohol aqueous solution 200 parts Melamine/cyanuric acid adduct 5 parts (reaction product of 1 mole of melamine and 1 mole of cyanuric acid heated at 50°C in an aqueous solvent: oil) (manufactured by Melamine ■) Added water 270 parts Example 2 The 40% microcapsule dispersion obtained in Example 1 was made into a coating liquid for a color former sheet with the following formulation.

Apply this coating liquid to high-quality paper with a basis weight of 40 g/rd in an amount of 3°7.
g/nf (absolutely dry solid content) was coated and dried using an air knife coater to obtain a coloring agent sheet.

[Coating liquid for color former sheet]

40% microcapsule dispersion 250 parts Wheat starch 25 parts 10% polyvinyl alcohol aqueous solution 200 parts Melamine/shea superacid adduct 15 parts (manufactured by Yuka Melamine ■) Added water 310 parts Example 3 40% obtained in Example 1 The microcapsule dispersion liquid was used as a coating liquid for a color former sheet in the following formulation.

This coating liquid was applied to a high-quality paper with a basis weight of 40 g/rr to a coating amount of 4.1 g/yrr (absolutely dry solid content) using an air knife coater and dried to obtain a color former sheet.

[Coating liquid for color former sheet]

40% microcapsule dispersion 250 parts Wheat starch 25 parts 10% polyvinyl alcohol aqueous solution 200 parts Melamine/shea superacid adduct 30 parts (manufactured by Yuka Melamine ■) Added water 370 parts Comparative Example 1 40% obtained in Example 1 The microcapsule dispersion was used as a coating liquid for a color former in the following formulation. This coating liquid has a basis weight of 40g.
/ m high-quality paper with an air knife coater to coat the coating amount at 3.4 g/rri (absolutely dry solid content) and dry.
A color former sheet was obtained.

[Color former coating liquid B# 40% microcapsule dispersion 250 parts wheat starch
25 parts 10% polyvinyl alcohol aqueous solution 200 parts Added water
250 parts (Test method) Using the color former sheets of the above examples and comparative examples, the coloring degree of the color former sheet coated surface against light, and the coated surfaces of the color former sheet and the color developer sheet were brought together and colored under pressure. Discoloration of the image area of the color developer sheet against light (color image survival rate)
was tested based on the following evaluation, and the resulting values are shown in Table 1.2.
The evaluation is shown in Table 3.4.

(b) Evaluation of degree of coloring of the coloring agent sheet Place the microcapsule-coated surface of the coloring agent sheet in direct sunlight for 1 hour.
Time, fluorescent light 5000L x 24 hours, 2 on the wall in the office
After being exposed and left for a week, the degree of coloring was measured using a color difference meter as L value.

The larger the value, the less coloring.

(b) Evaluation of color fading properties of color-developed images of color-developing agent sheet Combining the color-developing agent sheet with commercially available Mitsubishi NCR paper base paper (N40),
Color was developed through a super calendar, and after 24 hours, it was exposed to direct sunlight for 3 hours, a fluorescent lamp of 5000L x 72 hours, and a wall in an office for 1 month. After being left to stand, it was measured with a densitometer along with the untreated colored parts, and the following values were determined.

The larger the value, the less fading of the colored image and the higher the residual rate.

D density image residual rate after exposure (%) = X100 Table 1 Table 2 Untreated D density Table 3 Evaluation By containing the melamine/cyanuric acid adduct of the present invention, coloring of the microcapsule coating layer due to light etc. is prevented. In addition, an excellent color former sheet for carbonless pressure-sensitive copying paper has been developed which can prevent color fading of colored images.

○: Excellent effect, △: Effective, ×: Problems.

(F) In the coloring agent sheet coated with synthetic resin membrane microcapsules containing the effect coloring agent, as described above, the procedural amendment (spontaneous) 1゜2゜3゜Invention No. 1999 Patent Application No. 329967 Name Relationship with the case of a person who corrects color former sheets for carbonless pressure-sensitive copying paper Patent applicant address 3-4-2 Marunouchi, Chiyoda-ku, Tokyo Name (598) Mitsubishi Paper Mills Co., Ltd. 4゜5゜ Contact information Mitsubishi Paper Mills Co., Ltd. Patent Department, 4-1 Toganecho-chome, Katsushika-ku, Tokyo 125 <600) 2481 Detailed explanation of the invention in the specification subject to amendment Column of contents of amendment Page 12, line 10 "Coloring agent sheet coating liquid b#"

Claims (1)

[Claims] A coloring agent sheet for carbonless pressure-sensitive copying paper that contains a melamine/cyanuric acid adduct in a coloring agent sheet coated with synthetic resin film microcapsules containing an electron-donating dye.