JPH02283489A - Microcapsule sheet for pressure-sensitive recording - Google Patents

Abstract

PURPOSE:To obtain a microcapsule sheet for pressure-sensitive recording which becomes less contaminated due to a strong pressure or friction and outstanding coloring properties by dispersing fine particles of benzoguanamine resin in a layer where a microcapsule is applied. CONSTITUTION:Fine particles of benzoguanamine resin are dispersed in a layer where a microcapsule is applied formed on a sheet-like support. The fine particles of this benzoguanamine has a strong bonding power with the support because of their high compatibility with various kinds of bonding agents. In addition, the fine particles have an appropriate hardness as a stay material. The fine particles of benzoguanamine resin used for the microcapsule sheet should be of spherical shape, so that they protect the microcapsule against pressure and friction effectively. Furthermore, the fine particles prevent contamination satisfactorily and have the ability to help develop color with good contrast.

Description

Detailed Description of the Invention "Industrial Field of Application" The present invention relates to a microcapsule sheet for pressure-sensitive recording.More specifically, the present invention has excellent color development and prevents staining. This invention relates to a microcapsule sheet for pressure-sensitive recording.

[Prior Art] Pressure-sensitive recording paper, also called a carbonless sheet, is a top paper whose back surface is coated with microcapsules containing a colorless dye, such as a leuco dye, which is substantially colorless and develops color when it comes into contact with an acidic substance. and a lower paper coated with a color developer that develops the color by contacting the colorless dye, and if necessary, a color developer layer is applied to the back side between the upper and lower papers. One or more inner sheets coated with a layer of dye microcapsules may be inserted. By stacking the top, middle, and bottom sheets of paper and applying pressure from a pen or a printer, etc., the dye microcapsules are destroyed and the dye comes into contact with the color developer, forming a colored image on the color developer layer. This allows you to make multiple copies at once. The important properties required of microcapsule sheets for pressure-sensitive recording are that clear, high-density colored images can be obtained during recording, and that unnecessary colored stains do not occur during manufacturing, processing, printing, and other processes. can be given.

In order to satisfy the above characteristics, it is ideal for the microcapsules themselves to have sufficient mechanical strength such as pressure resistance, friction resistance, and impact resistance, as well as excellent coloring performance. It is difficult to impart such characteristics to the microcapsules themselves.

For this reason, generally, by dispersing particulate matter (hereinafter referred to as stay material) with a larger particle size than the microcapsules in the microcapsule coating layer, this stay material will support the microcapsules when subjected to weak pressure or friction. Measures are being taken to prevent capsule destruction and reduce staining. Materials commonly used as this stay material include various starch particles (Japanese Patent Publication No. 47-1178, 48
-33204, etc.) and Cellulose Mi: (US Pat. No. 2,711,375, etc.) are known. Other stay materials include inorganic pigments, fine particles of natural polymeric substances, fine particles of synthetic polymeric substances made by methods such as suspension polymerization or mechanical crushing (US Patent No. 3,625,786, etc.), and polymeric substance particles. Aggregates treated near the Tg point (Unexamined Japanese Patent Publication No. 5
1-78422), microspheres (Unexamined Japanese Patent Publication No. 1978)
-32013), dye-free capsules (Special Publication No. 47209)
No. 72), grape-like lumps of inorganic pigment fine particles (JP-A No. 5
No. 4-143325) are known, but all of them have drawbacks.

For example, when starch particles are used as a stay material, it is necessary to add a large amount in order to impart sufficient pressure and abrasion resistance, which has the drawback of significantly reducing coloring performance. In addition, when cellulose fiber is used as a stay material, the fiber width is small compared to the fiber length (and the strength of the fiber itself is weak, so the pressure resistance effect is not sufficient. The viscosity of the coating liquid is higher and the fluidity is poorer than in the conventional case, so there are problems when applying it with an air knife.

Furthermore, when mechanically crushed inorganic pigments or natural or synthetic polymer substances are used as stay materials, these particles have a wide particle size distribution and contain many microparticles smaller than the effective particle size that function as stay materials. These inhibit the transfer of capsule oil to the color developing sheet and significantly reduce color development. Furthermore, when microspheres or dye-free capsules are used as the stay material, they have low mechanical strength and collapse under weak pressure, so they are insufficient to impart pressure resistance to the capsule sheet.

In addition, as stay materials, polystyrene, polyvinyl chloride, polyvinyl acetate, etc. obtained by methods such as suspension polymerization,
When using particles of synthetic polymers such as polyolefin, polyurethane, and nylon, or aggregates of polymer particles made by the method described in JP-A-51-78422, these particles have a relatively sharp particle size distribution. Therefore, it has a clear coloring ability, and its pressure resistance is similar to that of starch particles.
Although it is better than natural polymeric substances such as cellulose fibers, its strength against strong pressure is insufficient. In addition, because the particles themselves have no or very weak adhesive ability, they lack bonding strength between the particles, between the particles and the support, and between the particles and the microcapsules, and the particles can be detached from the coated surface due to friction, causing the particles to form a bond between the capsule surface and the microcapsule. The phenomenon is similar to that caused when sand is inserted between the colored surface and friction occurs, and the abrasion resistance is conversely inferior.

In addition, when a grape-like lump of inorganic pigment fine particles described in JP-A No. 54-143325 is used as a stay material,
Since the specific gravity of the particles increases, continuous coating has the disadvantage that the ratio of stay abrasions in the coating liquid gradually increases due to sedimentation of the particles.

In addition to the use of stay materials, the pressure resistance of the pressure-sensitive recording sheet,
As a means to improve the abrasion resistance, a method has been proposed in which a large amount of a binder such as a natural or synthetic water-soluble polymer substance or latex is added to the microcapsule coating layer. However, this method has the disadvantage that the color development property is significantly reduced due to poor transfer of the capsule oil to the color development surface.

[Problem to be solved by the invention] The present invention was made in view of the above-mentioned drawbacks of microcapsule sheets for pressure-sensitive recording. It is an object of the present invention to provide a microcapsule sheet for pressure-sensitive recording that is less stained and has high color development.

[Means for Solving the Problems] As a result of intensive studies to achieve the above object, the present inventors have found that the drawback described in 1 above can be effectively solved by using fine particles of benzoguanamine resin as a stay agent. I found it.

That is, the present invention relates to a microcapsule sheet for pressure-sensitive recording, characterized in that fine particles of benzoguanamine resin are dispersed in a microcapsule coating layer formed on a sheet-like support.

When benzoguanamine resin fine particles are dispersed in the microcapsule coating layer, the microcapsules can be effectively protected from pressure and friction, exhibiting excellent stain prevention effects, and exhibiting excellent color development. This is thought to be because the benzoguanamine resin fine particles have a high affinity with various binders, so they have a strong bonding force with the support, and their hardness is suitable for use as a stay material.

Furthermore, when using benzoguanamine resin fine particles, it has become possible to obtain the same or better effect with a smaller amount of use than known starch particles, cellulose fibers, etc.

The benzoguanamine resin fine particles used in the microcapsule sheet of the present invention have a spherical particle shape. The particle size of the fine particles of benzoguanamine resin varies depending on the particle size of the microcapsules used. For example, if the particle size of the microcapsules is large, it is preferable that the stay material is also large; if the particle size of the microcapsules is small, it may be smaller to some extent.

Generally, it is preferable to selectively use particles having an average particle diameter of 3 to 100 μm. Particles having an average particle diameter of less than 3 μm contain many fine particles that do not function as a retainer, which causes a decrease in coloring performance.

On the other hand, particles having an average particle diameter exceeding 100 μm have drawbacks such as poor adhesion to the support and roughness of the surface.

Preferably, the particle size is 10 to 40μ.

It is desirable for the particle size distribution of the stay abrasive used in the present invention to have a sharper distribution for the above-mentioned reasons, but even if it has a wide distribution, there is no problem since the color development property is not significantly reduced.

The benzoguanamine resin used in the present invention may be produced by any production method.

Generally, it can be produced by reacting benzoguanamine and formaldehyde in an aqueous solution under appropriate conditions to cause polycondensation.

There is no particular limitation on the content of benzoguanamine resin fine particles in the microcapsule coating layer of the present invention (it is adjusted as appropriate depending on the use of the pressure-sensitive recording paper, the type of microcapsules, etc.). Generally, 100 parts by weight of microcapsules is used. It is used in a range of 5 to 300 parts by weight, and 10 to 20 parts by weight.
Preferably, it is 0 parts by weight.

The benzoguanamine resin fine particles of the present invention are subjected to classification treatment if necessary, and a desired particle size is fractionated for use.

Further, it is possible to use other types of stay materials such as starch particles and cellulose fibers in combination without impairing the effects of the present invention.

The microcapsules used in the present invention do not need to be specific, and can be produced by any method known in the art, such as physical methods, phase separation methods, interfacial polymerization methods, and in-5 in-itu methods. can.

Further, the electron-donating colorless dye contained in the microcapsules of the present invention is not particularly limited, and examples thereof include 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3,3-bis(p-
dimethylaminophenyl) phthalide, 3-(p-dimethylaminophenyl)-3-(1,3-dimethylindol-3-yl)phthalide, 3-(p-dimethylaminophenyl)-3-(2-methylindole- Triarylmethane compounds such as 3-yl) phthalide, 4.4'
-bisdimethylaminobenzhydrin benzyl ether, N-halophenyl-leucoolamine, N-2,4,
Diphenylmethane compounds such as 5-trichlorophenylleucoolamine, rhodamine lactam compounds such as rhodamine-B-anilinolactam, rhodamine (p-nitroanilino)lactam, rhodamine B-(p-chloroanilino)lactam, 7-diethylamino 3 -Chlorofluorane, 7-danitylamino 3-chloro-2-methylfluorane, 2-phenylamino-3-methyl-6-(
N-ethyl-Np-tolyl)aminofluorane, 2-dibenzylamino-6-diethylaminofluorane, 2-
A q Fluoran compounds such as urino-6-diethylaminofluorane, 2-anilino-3-methyl-6-cytylaminofluorane, 2-anilino-3-methyl-6-cyclohexylmethylaminofluorane, benzoyl leuco Thiazine compounds such as methylene blue p-nitrobenzoylleucomethylene blue, 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3
-Propyl-spiro-dibenzopyran, 3.3'cyclospirodinaphthopyran, 3-benzyl-spiro-
Spiro compounds such as dinaphthopyran and 3-methyl-naphtho-(3-methoxy-benzo)spiropyran can be used as appropriate.

Binders used in the microcapsule coating layer include water-soluble binders such as carboxymethyl cellulose, gelatin, hydroxyethyl cellulose, oxidized starch, acetate starch, phosphate starch, hydroxyalkylated starch, polyvinyl alcohol, and polyacrylic acid. In addition, latex such as styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, acrylic acid (methacrylic acid) ester polymer, and vinyl acetate copolymer may be used, and these may be used alone or in combination. Used as a mixture of the above.

The sheet-like support used in the color developing sheet of the present invention can be selected from wood-free paper, medium-quality paper, Japanese paper, thin paper, and coated paper (including lightly coated paper, lightweight coated paper, art paper, etc.). Furthermore, non- or low heat shrinkable films made of synthetic resins such as polyester, polyolefin, nylon, synthetic paper, etc. can be used.

These supports preferably have a basis weight of 20 to 200 g/J'1'1'. The above-mentioned paper is composed of pigments such as kaolin, clay, calcium carbonate, aluminum hydroxide, and plastic pigments, water-soluble adhesives such as starch, and /
Or coated with a paint containing an emulsion adhesive made of a synthetic polymer material obtained from styrene, butadiene, etc., the basis weight is 40 to 200 g/rrf', and the coating amount is about 5 to 20 g/rf'. Preferably.

Next, as the color developer that contacts the electron-donating colorless dye to form a coloring body, any conventionally known color developer, such as an inorganic color developer or an organic color developer, can be used. be. Examples of the inorganic color developer include acid clay, activated clay, calcined activated clay, and attapulgite. Examples of organic color developers include p-phenylphenol novolak resin disclosed in Japanese Patent Publication No. 42-20144, and p-
- Novolac-type phenolic resins such as octylphenol novolac resin, phenolic resins such as phenolacetylene resin, and polyvalent metal salts thereof, or Japanese Patent Publication No. 10856/1985, Japanese Patent Publication No. 251/1986
Benzoic acid, nitrobenzoic acid, p-t as described in No. 74 and Japanese Patent Publication No. 49-55410, etc.
ert-butylbenzoic acid, 4-methyl 3-nitrobenzoic acid, p-isopropylbenzoic acid, 2,5-dinitrobenzoic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, 2-hydroxy-1-benzyl-3 - naphthoic acid,
1-benzoyl-2-hydroxy-3-naphthoic acid, 3
-hydroxy-5-cyclohexyl-2-naphthoic acid,
Salicylic acid, 5-tert-butylsalicylic acid, 3-phenylsalicylic acid, 3-cyclohexylsalicylic acid, 3
-Methyl-5-tert-butylsalicylic acid, 3,5-
Di-tert-butylsalicylic acid, 3-methyl-5-benzylsalicylic acid, 5-cyclohexylsalicylic acid, 3-
Methyl-5-isoamylsalicylic acid, 3,5-di-5e
c-Butylsalicylic acid, 3-phenyl-5-(α, α-
dimethylbenzyl)salicylic acid, 3-cyclohexyl-
5(α,α-dimethylbenzyl)salicylic acid, 3(α,
α-dimethylbenzyl)-5-methylsalicylic acid, 3.
5-di-cyclohexylsalicylic acid, 3.5-di (
α-Methylbenzyl)salicylic acid, 3.5-di(α
, α-dimethylbenzyl)salicylic acid, 3-(α-methylbenzyl)-5(α,α-dimethylbenzyl)salicylic acid, 4methyl-5-cyclohexylsalicylic acid, and polyesters of these compounds. valent metal salts, or metal salts of oligobenzylated aromatic hydroxycarboxylic acids as described in JP-A-63-132857, or JP-A-63-1
A polyvalent metal salt of a carboxine-modified terpene phenol resin as disclosed in No. 9786, or a salicylic acid novolak resin (Japanese Patent Application Laid-open No. 488215), or
JP-A-62-176875, JP-A-63-53092
Copolymers of salicylic acid and compounds such as alkoxyquinrene, trialkylbenzene, or styrene derivatives, or polyvalent metal salts thereof, as disclosed in JP-A No. 63-186729, etc. I can give it to you.

These acidic substances can be used alone or in combination of two or more.

[Example] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto. In addition, "part" and "%" in the examples represent a polymerized part and a percentage of overlap unless otherwise specified.

(Preparation of microcapsule dispersion) 3 parts of 3-bis-(p-dimethylaminophenyl)6-dimethylphthalide was dissolved in diisopropylnaphthalene (KM
C-113, Kureha Chemical Pressure-sensitive recording paper oil) 10
0 parts of the internal oil was emulsified at 60°C in 100 parts of a 5% aqueous solution of styrene-maleic anhydride copolymer (pH 5.5). 10 parts of melamine, 2 parts of 37% formalin solution
0 parts and 30 parts of water were heated and dissolved with caustic soda to pH 9.5 to obtain a melamine-formalin initial condensate, which was added to the above emulsion, stirred at a temperature of 70°C, and reacted for 2 hours. Thereafter, the mixture was cooled to room temperature, and the pH was raised to 9.5 with caustic soda to produce a microcapsule dispersion of melamine-formalin resin by an in 5 in situ method.

(Creation of color developing sheet) Calcium carbonate aqueous dispersion in 20 parts of water (solid content 60%)
100 parts of p-phenylphenol resin aqueous emulsion (solid content 40%) as a color developer, 25 parts of styrene butadiene latex (solid content 50%), oxidized starch aqueous solution (solid content 15%). 10 parts of each were mixed with stirring to prepare a color developer coating solution. This coating liquid was applied to one side of a base paper having a basis weight of 50 g/rrf' so that the coating amount after drying was 6 g/rrr, and dried to prepare a color developing sheet.

Examples 1-3. Comparative Examples 1 to 2 100 parts of an oxidized starch aqueous solution (solid content 10%) was added to 100 parts of the microcapsule dispersion obtained by the above method,
A microcapsule coating solution was prepared by adding 200 parts of water to the mixture in the amount shown in Table 1 while stirring.

Next, apply this coating solution to a coating amount of 3 microcapsules after drying.
A microcapsule sheet was prepared by coating one side of a base paper with a basis weight of 50 g/rd so as to give a weight of 50 g/rd.

Table 1 A performance comparison test I was conducted using this microcapsule sheet and the color developing sheet. The test method and quality evaluation method are as follows.

(2) Color development density The microcapsule sheet and the color development sheet were combined and passed between pressurized rolls, then stored in a dark place, and the color density 24 hours later was measured using a Macbeth reflection densitometer. The larger the value, the higher the color density, which is preferable.

■Abrasion resistance Using a Gakushin type friction tester, bring the capsule surface of the microcapsule sheet into contact with the developer surface of the color developer sheet. In this state, the sample was rubbed back and forth 5 times to form a colored mark on the developer surface, and then stored in a dark place, and the color density after 24 hours was measured using a Macbeth reflection densitometer. The smaller the value, the less staining caused by friction, which is preferable. Two friction test conditions were conducted: no load and 300g load.

■ (Multiple sheets) Copyable microcapsule sheets and color developer sheets are combined, and 3 sets of 6 sheets are stacked one on top of the other, and then printed continuously using a typewriter in 3mm x 3mm solid letters to develop color on the entire surface. 24 hours after color development, the color density of the sixth sheet was measured using a Macbeth reflection densitometer. The higher the numerical value is, the higher the multi-sheet copyability is, which is preferable.

The results are shown in Table 2.

[Effects of the Invention] In the present invention, by dispersing benzoguanamine resin fine particles in the microcapsule coating layer, a microcapsule sheet for pressure-sensitive recording with extremely little staining and clear color development can be obtained. It became so. Moreover, it has become possible to obtain the same or better stain prevention effect with a smaller amount than the conventional one.

Procedures Amendment letter■, Indication of the case 1999 Patent Application No. 1050002, Name of the invention Microcapsule sheet for pressure-sensitive recording3, Person making the amendment Relationship to the case Patent applicant address name Oji Paper Co., Ltd.4 , Agent 6, Contents of amendment 1, ``No weight'' on page 19, line 10 of the specification is amended to ``no weight.''

2. Correct "weight" in the 11th line of the same amount peno to "load".

3. Table 2 of the 20th page is amended as follows.

Phone (270)-6641~6 [Detailed description of the invention] column of the specification ■■ trivial

Claims (1)

[Claims] A microcapsule sheet for pressure-sensitive recording, characterized in that fine particles of benzoguanamine resin are dispersed in a microcapsule coating layer formed on a sheet-like support.