JPH05147343A - Carbonless pressure-sensitive paper - Google Patents

Abstract

PURPOSE:To enhance light fastness in an ultraviolet region by providing a coating layer containing microcapsules including an electron donating color former and a specific ultraviolet absorbing polymer on a support. CONSTITUTION:An electron donating color former is compounded with a polymeric electrolyte such as a styrene/maleic anhydride copolymer and an interfacial polymerization process is adapted to the obtained compound to encapsulate the color former to obtain microcapsules including the color former. The microcapsules, a buffer material, a binder and an ultraviolet absorbing polymer being a polymer obtained from a monomer represented by the formula are compounded in a predetermined ratio to prepare a coating solution. A predetermined amount of this coating solution is applied to a support such as acidic paper or neutral paper based on a cellulose fiber and dried to obtain carbonless pressure-sensitive paper excellent in light (ultraviolet) fastness. The ultraviolet absorbing polymer may be a polymer obtained by polymerizing only the monomer having an ultraviolet absorbing group represented by the formula or a polymer of said monomer and other radical generating monomer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon-free pressure-sensitive copying paper having a coating layer of microcapsules. More specifically, it relates to a carbon-free pressure-sensitive copying paper which is excellent in light resistance (ultraviolet ray) of a sheet coated with an electron-donating color-forming agent-encapsulating microcapsule of the carbon-free pressure-sensitive copying paper.

[0002]

2. Description of the Related Art Carbon-free pressure-sensitive copying paper is usually produced by coating a support with microcapsules containing a colorless leuco dye (electron-donating color former) and an electron-accepting developer. Each is applied individually on a support, top paper,
It is used as a lower sheet, and is generally used as a medium sheet coated on both sides. Self-paper is also used in which one side or two sides are coated on one side of a support.
A plurality of these sheets are appropriately combined, the physical pressure of writing, typewriter, impact printer, etc. is applied to destroy the microcapsules, and the leuco dye inside the capsules develops color by contact with the color developer and records. This is a system that can obtain images.

However, these carbonless pressure-sensitive copying papers do not always have satisfactory performance. For example, top paper (CB) and middle paper (CF) coated with microcapsules.
In B), there is a phenomenon in which the leuco dye in the microcapsules is decomposed by natural light, particularly light in the ultraviolet wavelength range, and the coloring ability is reduced. This tendency is CVL (3,3
It is particularly remarkable in the blue color development mainly containing -bis (p-dimethylaminophenyl) -6-dimethylaminophthalide). As measures against this, 1. Make the leuco dye itself light resistant. 2. Add UV absorber into the microcapsule internal phase. 3. An ultraviolet absorber and a light stabilizer are used together and added to the inner phase of the microcapsule. 4. Add a water-soluble UV absorber to the coating solution. Etc. methods have been proposed. Examples of the leuco dye of No. 1 include 3- (4-dimethylamino-2-ethylphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide as a blue color developing system. Examples of the ultraviolet absorber of 2 include salicylic acid type such as phenyl salicylate, benzophenone type such as 2,4 dihydroxybenzophenone, and benzotriazole type such as 2- (2-hydroxy-5-methylphenyl) benzotriazole. As the light stabilizer of No. 3, there are hindered amines and the like.

A number of methods for producing microcapsules containing an electron-donating color former are known, but typical methods are: -a coacervation method using a polyion complex of gelatin-arabia gum (US Pat. No. 2800).
No. 457 and No. 2800458). An interfacial polymerization method in which an insoluble film is formed at the interface between a hydrophilic liquid serving as a dispersion medium and a hydrophobic liquid to be included.・ In situ after adding a film resin initial condensate such as melamine-formalin resin or urea-formalin resin from the side of the hydrophilic liquid serving as a dispersion medium, and then encapsulating the resin by in situ
Polymerization method (Japanese Patent Publication No. 36-9168, 47-231)
65, JP-A-48-57892, 51-
No. 9079, No. 54-25277, etc.) and the like. Among these, high-concentration microcapsule emulsions can be obtained, in which the raw materials are cheaply and stably supplied,
Due to the simple manufacturing process, etc., synthetic resin capsules, especially in s
In situ polymerization capsules are widely used.

In US Pat. No. 4,001,480, a method of encapsulating a substance soluble in the lipid in a fungus having a lipid content of 40 to 60 wt% is introduced. Further, in JP-A-58-107189, as a method for increasing the lipid content of growth microorganisms, lipids are added to growth microorganisms recovered from a medium having a lipid content of 10 wt% or more (for example, oil-fat-forming yeast, brewer's yeast, etc.). A core substance soluble in these lipid-increasing organic substances after containing a liquid selected from organic compounds for use in lipids (eg, aliphatic alcohols, esters, aromatic hydrocarbons, hydrogenated aromatic hydrocarbons) The microbial microcapsules obtained by encapsulating a liquid to be used are listed. In addition, recently, application of microbial microcapsules (in particular, having yeast as a wall membrane) to carbonless pressure-sensitive copying paper has been proposed (Japanese Patent Laid-Open Nos. 62-294079 and 62-186937).
63-88033, etc.).

[0006]

Problems to be Solved by the Invention It is a fact that the method of improving the light resistance specified above has the following problems. For example, in the "method for imparting light resistance to the leuco dye itself", there are many drawbacks such as a decrease in coloring ability, a low solubility in a microcapsule internal phase solvent, and a high cost. "Method of adding ultraviolet absorber to the internal phase of microcapsules", "Method of adding ultraviolet absorber and light stabilizer to the internal phase of microcapsules"
In this case, there are problems such as low solubility in the microcapsule internal phase solvent. Further, there is an inconvenience that it cannot be added afterwards, for example, when preparing a coating solution. An ultraviolet absorber can be added to the coating layer, but if it is an insoluble solid, it requires crushing, dispersion in water, and the like, which increases the number of working steps. Further, since it is granular, the effect of covering the entire coating layer cannot be expected. There is also a method of adding a water-soluble ultraviolet absorber, but it is generally a single molecule and has high penetrability, and the ratio of penetrating the support (especially paper) layer from the coating layer is high. Therefore, it does not exist in the vicinity of the microcapsule and its effect is very low. Furthermore, if the coated paper is processed at 100 ° C or higher,
It also has a drawback that the ultraviolet absorber itself decomposes and loses its effectiveness. For this reason, there is a need for an ultraviolet absorber that can be added later like a binder, has a low rate of penetrating into the coating layer, is easy to handle, and has heat resistance.

As described above, various measures have been proposed for the resistance to light (ultraviolet rays) of the sheet of the carbon-free pressure-sensitive copying paper coated with the electron-donating color former-containing microcapsules, but still a satisfactory method has been proposed. The current situation is that there are none.

[0008]

Means for Solving the Problems As a result of intensive studies, the inventors of the present invention have basically applied a coating liquid containing microcapsules containing an electron-donating color former, a buffer material and a binder, and drying the coating liquid. In a carbon-free pressure-sensitive copying paper having a layer provided on a support, the above-mentioned problems could be solved by adding an ultraviolet absorbing polymer in the coating layer. In the following, a detailed description of means for solving the problem will be specified. The present invention can be manufactured without any difference in structure from ordinary carbonless pressure-sensitive copying paper except that an ultraviolet absorbing polymer is added to the coating layer.

The ultraviolet absorbing polymer is a polymerized ultraviolet absorbing agent, and means a compound in which a monomer having an ultraviolet absorbing group is used as a part or all of the polymer. As the monomer having an ultraviolet absorbing group, it is preferable to use Chemical formula 1. As the monomer to be copolymerized with Chemical formula 1, various monomers can be used as long as they are radical-generating monomers. For example, in the monomers listed below,
Radical generating monomers can be used. As the monomer, {olefin derivative (ethylene, 1-butene,
2-butene, isobutene, 3-methyl-1-butene, etc., diene derivatives (propadiene, 1,2-butadiene, 1,3-
Butadiene, 2,3-Dimethyl-1,3-butadiene, 1,2
-Pentadiene, 3-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene, 1,4-pentadiene, 2-methyl-1,4-pentadiene, 1,2-hexadiene, 1,3
-Hexadiene, 1,4-hexadiene, 1,5-hexadiene, 2,5-dimethyl-1,5-hexadiene, 3,3-dimethyl-1,5-hexadiene, 2-methyl-1,5-hexadiene, 3 -Methyl-1,5-hexadiene, 2,4-hexadiene, 2,5-dimethyl-2,4-hexadiene, 5,5-
Dimethyl-2,4-hexadiene, octadiene, nonadiene, 1,9-decadiene, 1,10-undecadiene,
Etc.), styrene derivatives (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, dimethylstyrene, trimethylstyrene, isopropylstyrene, methoxystyrene, nitrostyrene, aminostyrene, p-vinylbenzenesulfonic acid, p- Vinylbenzenesulfonic acid Na, p-vinylbenzenesulfonic acid K, α-
Methylstyrene, α-ethylstyrene, etc.), vinyl ester derivatives (vinyl acetate, vinyl butyrate, vinyl pivalate, vinyl caprylate, vinyl laurate, vinyl palmitate, vinyl stearylate, vinyl methacrylate,
Vinyl crotonate, vinyl cinnamate, vinyl benzoate,
Vinyl nitrobenzoate, vinyl formate, etc., vinyl ether derivatives (methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, tert-butyl vinyl ether, 2-ethylhexyl vinyl ether, n-octadecyl vinyl ether, Vinyl vinyl ether, allyl vinyl ether, benzyl vinyl ether, phenyl vinyl ether, 2-
Methoxyethyl vinyl ether, diethylene glycol divinyl ether, etc.), acrylic acid derivatives (acrylic acid, acrylic acid anhydride, acrolein, crotonic acid, isocrotonic acid, angelic acid, tiglic acid, dimethylacrylic acid, methylethylacrylic acid, α- [N-acryloyl ] Aminoacrylic acid, α-acetoxyacrylic acid, α-
Trimethylsilyl acrylic acid, Na acrylate, etc., methacrylic acid derivatives (methacrylic acid, methacrylic anhydride,
Methacrolein, Na methacrylic acid, etc., acrylic ester derivatives (methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 1
0-undecyl acrylate, 2-ethylbutyl acrylate, vinyl acrylate, 2-ethylhexyl acrylate, 2-ethoxyethyl acrylate, octadecyl acrylate, cyclohexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, phenyl acrylate, etc., methacryl Acid ester derivatives (methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, 2-
Cyanoethyl methacrylate, isobutyl methacrylate, tridecyl methacrylate, vinyl methacrylate, etc., acrylamide derivatives (acrylamide, N-methyl acrylamide, N-tert-butyl acrylamide,
N-benzylacrylamide, etc.), methacrylamide derivative (methacrylamide, N-methylmethacrylamide, N-tert-butylmethacrylamide, N-benzylmethacrylamide, etc.), acrylonitrile derivative (acrylonitrile, 2-ethylacrylonitrile, 2-phenylacrylonitrile) Etc.), methacrylonitrile derivative, maleic acid derivative (maleic anhydride, methyl maleic anhydride, dimethyl maleic anhydride, phenyl maleic anhydride, maleic acid, methyl maleic acid, dimethyl maleic acid, phenyl maleic acid, etc.), maleic acid Ester derivatives (monomethyl maleate, dimethyl maleate, monoethyl maleate, diethyl maleate, monobutyl maleate, dibutyl maleate, etc.), maleamide derivatives (maleamic acid, maleic acid) Amide), maleimide derivative (maleimide, N-methylmaleimide, N-ethylmaleimide, etc.), dicarboxylic acid derivative (oxalic acid, malonic acid, succinic acid, tartaric acid, itaconic acid, acetylenedicarboxylic acid, glutaric acid, 3-methylglutaric acid) Acid, etc.), dicarboxylic acid ester derivative (monoethyl oxalate, monophenyl oxalate, monoethyl malonate, monophenyl malonate, monoethyl succinate, monophenyl succinate, monoethyl tartrate, monoethyl fumarate, monoethyl fumarate, acetylene monocarboxylic acid) Monoethyl acid,
Monoethyl glutarate, diethyl oxalate, diphenyl oxalate, diethyl malonate, diphenyl malonate, diethyl succinate, diphenyl succinate, diethyl tartrate, diethyl itaconate, diethyl fumarate, diethyl acetylenedicarboxylate, diethyl glutarate, etc.) Can be given. The above example is a very small part, and the details include the monomers described in “Polymer Data Handbook, Basic Edition” (Polymer Society of Japan, Baifukan Publishing, 1986). Among these, acrylic acid esters such as methyl acrylate and ethyl acrylate are preferable.
The effect is sufficient in the range of 0.1 to 2.0 solid parts by weight with respect to 100 parts by weight of dry solid microcapsules, and the range of 0.1 to 0.5 solid parts by weight is preferable. It may be used in an amount of 2.0 solid parts by weight or more, but further effects cannot be obtained and it is economically disadvantageous. The addition method is not particularly limited, but it is preferable to adjust the coating solution.

As the binder used in the present invention, various latexes (styrene-butadiene type copolymer latex, vinyl acetate type, acrylic type latex and their alkali thickening type latexes), as well as soluble starch,
Examples include water-soluble polymer substances such as casein, gelatin, arabic gum, polyvinyl alcohol, methyl cellulose and CMC. Furthermore, it is also possible to use mixtures of these. Usually, the amount of these used is preferably in the range of 5 to 100 solid parts by weight with respect to 100 parts by weight of dry solid microcapsules. Particularly preferably, it is in the range of 5 to 50 solid parts by weight.

The buffer material used in the present invention is preferably a known one such as wheat starch granules, corn starch granules, pea starch granules and various plastic pigments, and the size thereof is preferably in the range of 1 to 100 μm.

The color-forming agent (electron-donating color-forming agent) used in the present invention is not particularly limited as long as it can be used for general pressure-sensitive copying paper. To give a specific example,

(1) As a triarylmethane compound,
3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (crystal violet lactone), 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) −
3- (1,2-dimethylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-
Methylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-phenylindol-3-yl) phthalide, 3,3-bis- (1,2-dimethylindol-3-yl) ) -5-Dimethylaminophthalide, 3,3-bis- (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide, 3,3-
Bis- (9-ethylcarbazol-3-yl) -5-dimethylaminophthalide, 3,3-bis- (2-phenylindol-3-yl) -5-dimethylaminophthalide, 3-p-dimethylamino Phenyl-3- (1-methylpyrrol-2-yl-6-dimethyl-aminophthalide, etc.

(2) As a diphenylmethane compound,
4,4'-bis-dimethylaminobenzhydrin benzyl ether, N-halophenyl leuco auramine, N-
2,4,5-trichlorophenyl leuco auramine, etc.

(3) Rhodamine B-anilinolactam, rhodamine B-p-nitroanilinolactam, rhodamine B-p-chloroanilinolactam, 3-diethylamino-7-dibenzylaminofluorane, as xanthene compounds. 3-diethylamino-7-octylaminofluorane, 3-diethylamino-7-phenylfluorane, 3-diethylamino-7-3,4-dichloroanilinofluorane, 3-diethylamino-7- (2-chloroanilino) fluorane , 3-diethylamino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3-ethyl-tolylamino-6-methyl-7-anilinofluorane, 3- Ethyl-tolylamino-6-methyl-7-phenethylfluorane, 3-diethyl Amino-7- (4-nitroanilino) fluorane, etc.,

(4) As thiazine compounds, benzoyl leuco methylene blue, p-nitrobenzoyl leuco methylene blue, etc.

(5) As a spiro compound, 3-methyl-
Spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3,3′-dichloro-spiro-dinaphthopyran, 3-benzylspiro-dinaphthopyran, 3-methylnaphtho- (3-methoxy-benzo) -spiropyran, 3
-Propyl-spiro-dibenzopyran, etc.,

In addition, JP-A-63-230387 and "Dye for pressure-sensitive and heat-sensitive recording paper" (coloring material, 61 [5] P
292-302. 1988). Alternatively, mention may be made of a mixture thereof. These are determined by the application and the desired properties.

The hydrophobic medium used as the internal phase of the microcapsules is not particularly limited as long as it is one used for general pressure-sensitive copying paper. To give a specific example, (a)
As aromatic hydrocarbons, diarylethane, alkylbiphenyl, alkylterphenyl, alkylnaphthalene, triarylmethane, diphenylalkane, hydroanthracene, hydrophenanthrene, dibenzyltoluene, etc.

(B) Kerosene, paraffin, naphthene oil, chlorinated paraffin, etc. as mineral oil, (c) Cotton oil, corn oil, coconut oil, etc. as vegetable oil, (d) Oleyl alcohol, tridecyl alcohol as alcohol Alcohol, benzyl alcohol, 1-phenylethyl alcohol, glycerin, etc., (e) Organic acid, oleic acid, etc., (f) Ester, dimethyl phthalate, diethyl phthalate, di-
n-butyl phthalate, dioctyl phthalate, diethyl adipate, propyl adipate, di-n adipate
-Butyl, dioctyl adipate, etc. (g) As organic phosphoric acid compounds, tricresyl phosphate, tributyl phosphite, tributyl phosphite oxide, etc., (h)
As an ether, phenyl cellosolve, benzyl carbitol, polypropylene glycol, propylene glycol monophenyl ether, etc., (i) As an amide, N,
N-dimethyllauramide, N, N-dimethylstearamide, N, N-dihexyloctylamide, etc., (j) Ketone as diisobutyl ketone, methylhexyl ketone, etc., (k) Alkyl carbonate as ethylene carbonate, propylene carbonate, etc. Or, a mixture of these may be mentioned. These are determined by the application and the desired properties.

Further, when the electron-donating color former is microencapsulated, it is also possible to dissolve the ultraviolet absorbing substance and the infrared absorbing substance in the inner phase and use them, as is conventionally used. In the invention, it is possible to reduce the amount of the ultraviolet absorbing substance used. These are not particularly limited as long as they are substances used for general pressure-sensitive copying paper. Specific examples of the ultraviolet absorbing material include (a) salicylic acid-based phenyl salicylate, p-
tert-Butylphenyl salicylate, p-octylphenyl salicylate, etc .: (b) As a benzophenone type, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy- 4-dodecyloxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-
Sulfobenzophenone, etc .: (C) As a benzotriazole type, 2 (2′-hydroxy-5′-methylphenyl) benzotriazole, 2
(2'-hydroxy-5'-tert-butylphenyl) benzotriazole, 2 (2'-hydroxy-
3 ', 5'-di-tert-butyl-phenyl) benzotriazole, 2 (2'-hydroxy-3'-tert
-Butyl-5'-methylphenyl) -5chlorobenzotriazole, 2 (2'-hydroxy-3 ', 5'-di-
tert-aluminumphenyl) benzotriazole, 2
(2′-Hydroxy-4′-octoxyphenyl) benzotriazole, etc .: (d) As a cyanoacrylate-based compound, 2-ethylhexyl-2-cyano-3,3′-diphenylacrylate, ethyl-2-cyano-3,3. '-Diphenyl acrylate, etc .: or a mixture thereof can be mentioned. These are determined by the application and the desired properties.

The encapsulation method used in the present invention is not particularly limited, but the microcapsules prepared by the coacervation method generally have the possibility that the film is broken in the latex, so that the interfacial polymerization method, in It is desirable to use the in situ polymerization method or the microbe microencapsulation method. The emulsifier used for in situ polymerization encapsulation is preferably a polymer electrolyte. Specifically, styrene-maleic anhydride copolymer, styrene-benzyl methacrylate-
Maleic anhydride copolymer, α-alkylstyrene-maleic anhydride copolymer, nuclear monoalkyl-substituted styrene-maleic anhydride copolymer, nuclear dialkyl-substituted styrene-maleic anhydride copolymer, styrene-monoalkyl maleic anhydride Aqueous solution of ester copolymer, ethylene-maleic anhydride copolymer, polystyrene sulfonic acid, polyacrylic acid, acrylic acid-acrylic acid ester copolymer, etc.,
And mixed aqueous solutions of these are used. As the emulsifier used for the interfacial polymerization encapsulation, in addition to the in situ encapsulation, an aqueous solution of PVA, CMC, HEC, various (wheat, potato, corn, etc.) starch, etc., and a mixed aqueous solution thereof are also used. Incidentally, known substances having nonionic, cationic, and amphoteric surface-active substances may be added to such an extent that they do not cause a problem in the encapsulation step and used in combination.

As a coating method used in the present invention, coating and drying are carried out by an ordinary coating machine (coater). Specific coating machines include air knife coaters, blade coaters, rod coaters, bar coaters, roll coaters,
A size press coater, a curtain coater or the like is used.

As the support, acid paper or neutral paper mainly composed of cellulose fibers is usually used, but synthetic paper or the like may be used.

As the color developer used in combination with the carbonless pressure-sensitive copying paper obtained by the present invention, phenol resin compounds, salicylic acid metal salt compounds, salicylic acid resin metal salt compounds, solid acid compounds and the like are preferable.

[0026]

EXAMPLES Next, the features of the present invention will be described in detail with reference to Comparative Examples and Examples. Of course, the present invention is not limited to the Examples, and therefore the substances used, the production conditions, etc. are also included in the Examples. It is not limited to the description of. In Comparative Examples and Examples, unless otherwise specified, it is expressed as parts by dry solid.

Example 1 [Preparation of electron-donating color former-containing microcapsules] CV
L (3-diethylamino-7,8-benzofluorane: (3-
Diethylamino-7,8-benzofluoran)) was dissolved in 96 parts of a diarylethane solvent (Hisol SAS N-296: manufactured by Nippon Petrochemical Co., Ltd.) to prepare a solution. To 180 parts of a 5% aqueous solution of styrene-maleic anhydride copolymer,
220 parts of the above hydrophobic liquid was gradually added under strong stirring, and
Stirring was continued until the 0% volume average diameter became 5 μm to obtain an emulsion. Separately, 11 parts of melamine, 21.2 parts of a 37% aqueous formaldehyde solution, and 28.2 parts of water were dissolved by heating to obtain an aqueous solution of a melamine-formaldehyde initial condensate, which was added to the emulsion for 2 hours at a temperature of 70 ° C. The mixture was stirred to obtain a microcapsule liquid.

[Preparation of carbonless paper (CB)] 35 parts of wheat starch, 18 parts of styrene-butadiene copolymer latex (manufactured by Japan Synthetic Rubber Co., Ltd.) and 100 parts of ultraviolet rays were added to 100 parts of the microcapsules containing the electron-donating color former. absorbent polymer (of _{1 (R: -CH 3, 10mol} %) and ethyl acrylate (90 mol%) copolymerized polymer compound: Ipposha Yushi) was added 0.1 part. Adjust to pH = 9.0,
A coating solution for carbonless pressure-sensitive copying paper was obtained. The coating liquid was applied by an air knife coating method so that the dry coating amount of the electron-donating color-forming agent-encapsulating microcapsules was 3.0 g / m ² to obtain a carbonless upper paper (CB).

[Measurement of recoloring ability after CB surface irradiation with sunlight] The coated surface of the obtained CB was irradiated with direct sunlight (in the clear weather in late April, at any time from 10 am to 3 pm). Commercially available carbonless pressure-sensitive copy paper bottom paper (Mitsubishi NCR paper bottom paper N-4
Color was developed in combination with 0, 40 g / m ² base lower paper). The color density of the lower paper can be measured by the color difference meter CR-200.
(Manufactured by Minolta). Color recurrence rate is ((Density Y of sun-irradiated area) / (Density Y of un-irradiated area)) ×
Calculated at 100%. The larger the number is, the less the storage stability is, and the better the quality is.

Example 2 In [Preparation of carbonless paper (CB)], except that the addition amount of the ultraviolet absorbing polymer was changed to 0.3 part.
All were carried out in the same manner as in Example 1. Example 3 In [Preparation of carbonless paper (CB)], except that the addition amount of the ultraviolet absorbing polymer was changed to 0.5 part.
All were carried out in the same manner as in Example 1. Example 4 In [Preparation of carbonless paper (CB)], except that the addition amount of the ultraviolet absorbing polymer was changed to 0.7 part.
All were carried out in the same manner as in Example 1. Example 5 In [Preparation of carbonless paper (CB)], except that the addition amount of the ultraviolet absorbing polymer was changed to 0.8 part.
All were carried out in the same manner as in Example 1. Example 6 In [Preparation of carbonless paper (CB)], except that the addition amount of the ultraviolet absorbing polymer was changed to 2.0 parts.
All were carried out in the same manner as in Example 1.

Comparative Example 1 In [Preparation of carbonless paper (CB)], the same procedure as in Example 1 was carried out except that no ultraviolet absorbing polymer was added. Comparative Example 2 In [Preparation of carbonless paper (CB)], the same procedure as in Example 1 was carried out except that the addition amount of the ultraviolet absorbing polymer was changed to 0.05 part. Comparative Example 3 In [Preparation of carbonless paper (CB)], except that the addition amount of the ultraviolet absorbing polymer was changed to 2.5 parts.
All were carried out in the same manner as in Example 1. Example 7 [Preparation of carbonless top paper (CB)] The same procedure as in [Preparation of carbonless top paper (CB)] in Example 3 was carried out. [Measurement of recoloring ability of CB after heating after CB surface irradiation with sunlight] The obtained CB was heated at 150 ° C for 2 hours to perform heat treatment. The same procedure as in [Measurement of recoloring ability after CB surface exposure to sunlight] in Example 3 was performed, except that the irradiation time of direct sunlight was 60 minutes. Comparative Example 4 Instead of the ultraviolet absorbing polymer in Example 7, a finely ground emulsion of the ultraviolet absorbent Sumisorb 130 (2-hydroxy-4-n-octylbenzophenone: manufactured by Sumitomo Chemical Co., Ltd.) was used in a solid amount of 0. Example 7 was repeated except that 5 parts were used. Comparative Example 5 Instead of the ultraviolet absorbing polymer in Example 7, the ultraviolet absorber Tinuvin 327 (2- (2'-hydroxy-3 ', 5'-
Di-t-butylphenyl) -5-chloro-benzotriazole: manufactured by CIBA-GAIGY) was used in the same manner as in Example 7 except that 0.5 part of a finely divided emulsion was used as a solid amount of an ultraviolet absorber. .. Comparative Example 6 The procedure of Example 6 was repeated except that the ultraviolet absorbing polymer was not added. The results of Examples 1 to 6 and Comparative Examples 1 to 3 are shown in Table 1. The results of Example 7 and Comparative Examples 4 to 6 are shown in Table 2.
It was shown to.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

As is apparent from the above, according to the present invention,
In the top paper (CB) coated with microcapsules containing an electron-donating color former, the light resistance (particularly in the ultraviolet range) was significantly improved. Furthermore, the light resistance (particularly in the ultraviolet range) of the CB after the heat treatment was significantly improved. Further, since it has become possible to suppress the permeability, which has been a problem in the past, a sufficient effect can be obtained even with post-addition and the number of working steps can be reduced.

Claims (2)

[Claims] 1. A carbonless pressure-sensitive copying system comprising a support and a coating layer formed by coating and drying a coating liquid containing microcapsules containing an electron-donating color former, a buffer and a binder. A carbonless pressure-sensitive copying paper, characterized in that a UV-absorbing polymer polymerized by using a monomer having an UV-absorbing group is added to the coating layer. 2. The carbon-free pressure-sensitive copying paper according to claim 1, wherein the ultraviolet absorbing polymer is a polymer compound obtained by polymerizing a part or all of the monomers represented by the formula 1 below. [Chemical 1]