JPH04101881A - Pressure-sensitive copy paper - Google Patents

Abstract

PURPOSE:To obtain pressure-sensitive copy paper excellent in light fastness, whiteness and color forming properties by providing a color forming layer containing a developer and pigment on a support and adding rutile type titanium dioxide having a specific particle size to the pigment. CONSTITUTION:Pressure-sensitive copy paper is formed by providing a color forming layer containing a developer and pigment on a support. The developer is an org. one and the pigment contains calcium carbonate and rutile type titanium dioxide having a mean particle size of 0.04-1.5mum and the content of calcium carbonate is pref. 50% by wt. of the total amount of the org. developer and the pigment and that of rutile type titanium dioxide is pref. 1-20% by wt. of the total amount of the org. developer and the pigment. The mean particle size of rutile type titanium dioxide is pref. set to 0.08-0.4mum.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention relates to pressure-sensitive copying paper, and particularly to pressure-sensitive copying paper with improved color development, light fastness, and whiteness.

``Prior Art'' Pressure-sensitive copying paper uses a microcapsule composition mainly composed of microcapsules containing oil droplets in which an electron-donating organic coloring agent (hereinafter simply referred to as coloring agent) is dissolved, on one side of a support. A coloring agent composition containing an electron-accepting coloring agent (hereinafter simply referred to as a coloring agent) as a main component that changes color when it comes into contact with the above-mentioned coloring agent is applied to the coated upper paper and one side of the support. There are two types of paper: inner paper, which has a coloring layer applied to it, and a microcapsule composition coated on the other side, and bottom paper, which has a coloring layer applied to one side of the support by coating a coloring agent composition. It has been put into practical use as a copy cent by combining the sheets in the order of top paper, bottom paper, or top paper, middle paper, and bottom paper. Also known as a form of pressure-sensitive copying paper is a self-coloring pressure-sensitive copying paper that allows pressure-sensitive recording on one sheet by coating a coloring agent and a coloring agent on the same side of a support.

However, when a pressure-sensitive copying paper provided with a coloring agent-containing layer, that is, a coloring layer, is exposed to sunlight, its coloring ability decreases, and when it is exposed to sunlight after printing, it has the disadvantage that the print density decreases. Therefore, there is a demand for the development of technology to improve light resistance.

As coloring agents for pressure-sensitive copying paper, inorganic coloring agents such as acid clay, activated clay, acpulgite, zeolite, bentonite, silica, aluminum silicate, etc., phenol-aldehyde polymers, phenol-acetylene polymers, etc. Organic coloring agents such as phenol polymers, aromatic carboxylic acids or their polyvalent metal salts are known, and organic coloring agents have higher coloring ability than inorganic coloring agents, and are It has the advantage that the color image does not suffer from a decrease in recording density due to moisture adhesion or normal file storage. However, even pressure-sensitive copying papers using organic coloring agents having such advantages are currently required to have improved light fastness.

"Problems to be Solved by the Invention" An object of the present invention is to provide a pressure-sensitive copying paper that is excellent in light fastness, whiteness, and color development.

"Means for Solving the Problem" The present inventors investigated ultraviolet absorbers, zinc oxide, titanium oxide, aluminum hydroxide, etc. as materials for improving light resistance, and found that zinc oxide and titanium dioxide were effective. I discovered something. However, zinc oxide has the problem of regulating the concentration of zinc in wastewater, making wastewater treatment difficult.

Furthermore, when titanium dioxide is used in the coloring layer, it has the disadvantage that the coloring layer tends to be colored yellow.

As a result of further detailed examination of the crystal type, particle size, etc., we found that anatase-type titanium dioxide has an insufficient effect on improving light resistance, and that it needs to be contained in a large amount in the coloring layer, resulting in a decrease in the oil absorption of the coloring layer. There was also a problem in that the coloring property was lowered due to the yellowing of the coloring layer, and the whiteness was lowered due to yellowing of the coloring layer. However, it has been found that rutile-type titanium dioxide is more effective in improving light resistance than anatase-type titanium dioxide, and in particular, when rutile-type titanium dioxide having a specific particle size is included in a small amount, light resistance is significantly improved. In addition, sufficient effects can be obtained even if the amount of rutile titanium dioxide used is small, so yellowing of the coloring layer is minimized.
Another advantage is that there is almost no decrease in whiteness.

The present invention provides a pressure-sensitive copying paper in which a support is provided with a coloring layer containing a coloring agent and a pigment, wherein the pigment has an average particle size of 0.04.
This is a pressure-sensitive copying paper characterized by containing rutile-type titanium dioxide of ~1.5 μm.

Further, in the pressure-sensitive copying paper of the present invention, the coloring agent is an organic coloring agent, the pigment contains calcium carbonate and rutile titanium dioxide, and the calcium carbonate is 50% by weight of the total weight of the organic coloring agent and the pigment. % or more, and rutile titanium dioxide preferably accounts for 1 to 20% by weight of the total weight of the organic coloring agent and pigment.

Further, in the pressure-sensitive copying paper of the present invention, it is preferable that the average particle size of the rutile titanium dioxide is 0.08 to 0.4 μm.

"Action J Among rutile-type titanium dioxide, the average particle size is 0.04 to 1.
．． A layer having a thickness of 5 μm has an excellent effect of improving light resistance. If rutile titanium dioxide outside this range is not contained in a large amount in the color forming layer, sufficient light resistance will be obtained, resulting in a decrease in color development and whiteness of the pressure-sensitive copying paper. Therefore, the average particle diameter of rutile titanium dioxide (primary particles measured by electron microscopy) is 0.04 to 1.5 μm, preferably 0.04 to 1.5 μm.
08-0.4 μm, more preferably 0.1-0.3 μm
It is. Note that two or more types of rutile titanium dioxide having different average particle diameters may be used in combination.

Since rutile titanium dioxide has low oil absorption, if too much is used, there is a risk of deterioration in color development, and if too little is used, sufficient effects may not be obtained. Therefore, preferably 1 to 20% of the total weight of the coloring agent and pigment in the coloring layer.
When it is contained in an amount of about 3% to 17% by weight, pressure-sensitive copying paper with excellent light resistance can be obtained without reducing color development and whiteness.

In order to improve the pigment suitability of titanium dioxide, the surface can also be treated with aluminum, zinc, silica, organic substances, etc.

The coloring layer may also contain pigments other than rutile titanium dioxide. Examples of such pigments include inorganic pigments such as calcium carbonate, kaolin, calcined kaolin, silica, zinc oxide, magnesium oxide, aluminum hydroxide, magnesium sulfate, and calcium sulfate. In particular, inclusion of calcium carbonate can further improve whiteness. Calcium carbonate is preferably contained in an amount of 50% by weight or more based on the total weight of the coloring agent and pigment.

Although not particularly limited, the color forming layer contains approximately 70% to 95% by weight of pigment, approximately 1% to 30% by weight of coloring agent, and 1% of binder based on the total solid content of the coloring layer. weight%
It is blended in an amount of about 40% by weight.

When an organic coloring agent is used as a coloring agent, the water resistance of the colored image,
Pressure-sensitive copying paper with excellent normal file storage properties can be obtained.

Examples of organic coloring agents include Japanese Patent Application No. 2-81239;
Benzoic acid, pter t-butyl-benzoic acid, 4-methyl-3-nitrobenzoic acid as described in Japanese Patent Publication No. 49-10856, Japanese Patent Publication No. 51-25174, Japanese Patent Publication No. 49-55410, etc. , salicylic acid, 3-phenylsalicylic acid, 3-cyclohexylsalicylic acid, 3-ter
t-butyl-5-methylsalicylic acid, 3-tert-butyl-5-tert-octylsalicylic acid, 3-tert
-butyl-5-isononylsalicylic acid, 3-tert-
Butyl-5-(α-methylbenzyl)salicylic acid, 3-
tert-butyl-5-(α,α-dimethylbenzyl)
Salicylic acid, 3,5-di-tert-butylsalidylic acid, 3,5-di-tert-butylsalicylic acid, 3,5
-diisononylsalicylic acid, 3.5-ditert-
Butyl-6-methylsalicylic acid, 3゜5-diter
t-Amyl-6-tylsalicylic acid, 3.5-di5e
c-hexylsalicylic acid, 3-5ecoctylsalicylic acid, 3-sec-octyl-5methylsalicylic acid, 3-
sec-octyl-5 isopropylsalicylic acid, 3-t
ert-octylsalicylic acid, 3-tert-octyl-5-methylsalicylic acid, 3-tert-octyl-6
-Methylsalicylic acid, 3-isononylsalicylic acid, 3-
Isononyl-5-methylsalicylic acid, 3-isononyl-
6-methylsalicylic acid, 3-methyl-5-hensylsalicylic acid, 3-phenyl-5-(α,α-dimethylbenzyl)salicylic acid, 3-cyclohexyl 5-(α,α-dimethylhensyl)salicylic acid, 23-(α , α-dimethylpencyl)-5-methylsalicylic acid, 3-(α, α-
dimethylbenzyl)6-methylsalicylic acid, 3.5-di-cyclohexylsalicylic acid, 3.5-di(α-methylbenzyl)salicylic acid, 3.5-di(α-methylhensyl)-6-methylsalicylic acid, 3. 5-G (α,
α-dimethylbenzyl)salicylic acid, 3-(α-methylhensyl)-5-(α,α-dimethylpencyl)salicylic acid, 4-methyl-5-cyclohexylsalicylic acid, 2
-hydroxy-1-hensyl-3-naphthoic acid, 1-hensyl-2-hydroxy-3-naphthoic acid, 3-hydroxy-5-cyclohexyl-2-naphthoic acid, 2-hydroxy-4-CC4-carboxy-5-hydroxy)phenyl) -1-naphthoic acid, 3-methyl-5-secandarioctylsalicylic acid, 3-methyl-5-tertiaryoctylsalicylic acid, 3-methyl-5-isononylsalicylic acid,
3-Methyl 5-secondary decylsalicylic acid, 3-methyl 5-secondary 1-decylsalicylic acid, 3-methyl 5
-Ittodecylsalicylic acid, 3-methyl-5(α-methylhensyl)salicylic acid, 3-methyl-5-(α,α-
dimethylhensyl) salicylic acid, 3-isobut[]]bi-5-tertiaryocdylsalicylic acid 3-isopropyl-5-isononylsalicylic acid, 3-isopropyl-5-
(α~methylbenzyl)salicylic acid, 3-isopropyl-5(α,α-dimethylhensyl)salicylic acid, 3isononyl-5-(α-methylhensyl)salicylic acid, 3-
Secondary denolzalicylic acid, 3 secondary denol-5
-Methylsalicylic acid, 3-secondarydecyl-6-methylsalicylic acid, 3-secondarydodecylsalicylic acid, 3-secondarydodecyl-5-methylsalicylic acid, 3-secondarydodecyl-6-methylsalicylic acid, 3-ythodecylsalicylic acid, 3-isododecyl- 5-methylsalicylic acid, 3-iso1-decyl-6-methylsalicylic acid, 3-
Cyclohekinru 5-turnybutylsalicylic acid, 3
-cyclohexyl-5-isononylsalicylic acid, 3-cyclohexyl-5(α-methylbenzyl)salicylic acid,
3-phenyl-5-isononylsalicylic acid, 3-phenyl 5-(α-methylbenzyl)salicylic acid, 3-phenyl-5-(α,α-dimethylbenzyl)salicylic acid, 3
-(α-methylhensyl)salicylic acid, 3-(α-methylhensyl)-5-methylsalicylic acid, 3-(α-methylhensyl)-5-isononylsalicylic acid, 3,5-di(α-methylbenzyl)salicylic acid and benzyl chloride or condensation or addition products with styrene. However, here, the tertiary octyl group refers to a dimer of diisobutylene or 1-butene, the isononyl group refers to a trimer of propylene, and the isododecyl group refers to a tetramer of propylene or a trimer of 1-butene. The substituents are defined as substituents that are generated by adding to the nucleus of salicylic acid. These aromatic carboxylic acids and their salts with polyvalent metals such as zinc, aluminum, magnesium, calcium, cobalt, etc.: Japanese Patent Publication No. 40-9309, Japanese Patent Publication No. 42-2
6,6'-methylenebis(4-chloro-m-
Phenol-aldehyde resins such as P-phenylphenol-formaldehyde resins, phenolic acetylene resins such as p-tert-butylphenol-acetylene resins, and polyvalent metal salts thereof: maleic acid-rosin resins. , styrene, ethylene or a copolymer of vinyl methyl ether and maleic anhydride: Japanese Patent Publication No. 48
-8215, special public show 4E! -8216, Special Publication No. 1977
Examples thereof include polymers of aromatic carboxylic acids and aldehydes or acetylenes as described in No. 1326, and polyvalent metal salts thereof.

Among these organic coloring agents, aromatic carbonic acids and their polyvalent metal salts, phenolic resins and their polyvalent metal salts, copolymers of aromatic carboxylic acids and aldehydes or acetylene, and their polyvalent metal salts are particularly useful. Preferably used.

One or more of these coloring agents may be used in combination.

By the way, the softening point of the organic coloring agent is preferably about 20 to 85°C. The first method to adjust the softening point is to mix coloring agents with different softening points, and the second method is to lower the softening point of the coloring agent by adding substances that lower the softening point, metals of fatty acids, etc. Adding salts, trialkylphenols, trialkylphenols or styrene oligomers, etc. Thirdly, adding substances that increase the softening point which is too low, such as polystyrene, poly-alpha-methylstyrene or petroleum resins. can be mentioned. The mixing ratio and manufacturing method are not particularly limited.

If necessary, the coating solution may contain binders (adhesives) such as lees, casein, gum arabic, carboxymethyl cellulose, polyvinyl alcohol, styrene-bookdiene copolymer latex, vinyl acetate latex, etc. . Furthermore, various auxiliary agents known in the field of producing colored paper may be appropriately added within a range that does not impede the effects of the present invention.

The method for preparing the coating liquid for forming the coloring layer is not particularly limited, and may be prepared as appropriate. For example, a method in which a color former is mechanically dispersed in water together with an inorganic pigment, a binder, a dispersant, and other additives is applied to the support, or a method in which the color former is dissolved in an organic solvent and then soaked in water. A method in which a coating liquid obtained by emulsifying, removing the 18 agent as necessary, and adding inorganic li+, a binder, and other additives is applied to a support, or a coating liquid obtained by mixing the two is applied to a support. A method such as applying it to the surface is used.

The coating solution for coloring layer prepared in this way is applied to a support such as paper, synthetic paper, film, etc. using an air knife coater, plate coater, roll coater, size press coater, curtain coater, short dwell coater, etc. It is applied using conventional coating equipment and finished as a pressure-sensitive duplex paper.

"Examples" Examples and comparative examples are given below to further clarify the effects of the present invention, but the present invention is not limited to these examples. Note that parts and % in the examples represent parts by weight and % by weight, respectively, unless otherwise specified.

Example 1 (Preparation of coloring layer coating solution) 40 parts of a 25% aqueous dispersion of 3,5-di(α-methylbenzyl)zinc salicylate that had been atomized using a sand mill, 82 parts of calcium carbonate, and an average particle size of 0. 8 parts of 19 μm rutile titanium dioxide and 100 parts of water were mixed and dispersed, and as a binder, 100 parts of a 10% polyvinyl alcohol aqueous solution and 48% carboxy-modified SBR latex (S
N-307, manufactured by Sumitomo Naugatuck Co., Ltd.) 10 parts were mixed,
A dispersion was obtained.

[Manufacture of coloring paper for pressure-sensitive copying paper] The above coloring layer coating liquid was applied to one side of a 40 g/% base paper using an air knife coater so that the dry weight was 4.0 g/rrr, dried, and then sensitized. A colored paper for pressure copying paper was obtained.

Example 2 [Preparation of coloring layer coating liquid] 100 parts of a 25% aqueous dispersion of p-phenylphenol-formaldehyde polymer atomized by a sand mill, 65 parts of calcium carbonate, rutile type with an average particle size of 0.24 μm 10 parts of titanium dioxide and 100 parts of water are mixed and dispersed, and 4 parts of a 25% oxidized modified starch aqueous solution is used as a binder.
0 parts and 48% carboxy-modified SBR latex (SN-
307 (manufactured by Sumitomo Noga Tatsuta Co., Ltd.) were mixed to obtain a dispersion.

Thereafter, a colored paper for pressure-sensitive copying paper was obtained in the same manner as in Example 1.

Example 3 [Preparation of coloring layer coating liquid] 3.5-di(α-methylhensyl)zinc salicylate 70
100 parts of toluene and 3.0% polyvinyl alcohol dissolved in water. r! 150 parts of the emulsion was emulsified using a homomixer, and then toluene was distilled off to obtain an aqueous dispersion of the coloring agent. Is this water soluble? F9 was mixed with 900 parts of water, 830 parts of calcium carbonate, and 50 parts of rutile titanium dioxide with an average particle size of 0°19 μm (combined and dispersed in X~, and further 25% oxidized modified starch water as a binder) with a volume of 200 parts and 48 parts. % carboxy-modified SBR latex (SN-307, manufactured by Sumitomo Naugatac) were mixed to obtain a dispersion.

Thereafter, a colored paper for pressure-sensitive copying paper was obtained in the same manner as in Example 1.

Example 4 Instead of using 70 parts of zinc 3,5-di(α-methylhensyl)salicylate in Example 3, 3,5-di-t
A colored paper for pressure-sensitive copying paper was obtained in the same manner as in Example 3 except that 35 parts of zinc ert-butylsalicylate and 35 parts of zinc 3-isododecylsalicylate were used.

Comparative Example 1 Performance% In Example 1, titanium dioxide had an average particle size of 0.
A colored paper for pressure-sensitive copying paper was obtained in the same manner as in Example 1 except that 20 parts of 12 μm Anacuse type titanium dioxide was used.

Example 5 A colored paper for pressure-sensitive copying paper was obtained in the same manner as in Example 2, except that 30 parts of rutile-type titanium dioxide having an average particle size of 0.24 μm was used instead of 10 parts.

Comparative Example 2 The same procedure as in Example 3 was carried out except that 200 parts of rutile titanium dioxide with an average particle size of 0.02 μm was used instead of 50 parts of rutile titanium dioxide with an average particle size of 0.19 μm in Example 3. For pressure-sensitive copy paper? I got colored paper.

Comparative Example 3 Instead of 50 parts of rutile titanium dioxide having an average particle size of 0.19 μITI in Example 3, an average particle size of 2.0 μm was used.
A colored paper for pressure-sensitive copying paper was obtained in the same manner as in Example 3, except that 200 parts of rutile-type titanium dioxide was used.

Comparative Example 4 Pressure sensitive material was produced in the same manner as in Example 1, except that 8 parts of rutile titanium oxide with an average $M diameter of 0.19 μm was not used in Example 1, and 8 parts of calcium carbonate was added instead. A colored paper for copying paper was obtained.

Example 6 A colored paper for pressure-sensitive copying paper was obtained in the same manner as in Example 2 except that 65 parts of calcium carbonate in Example 2 was replaced with 30 parts of calcium carbonate and 35 parts of aluminum hydroxide.

[Preparation of top paper] A capsule coating liquid prepared by dissolving crystal violet lactone in alkylated naphthalene and microcapsulating this oily liquid was coated on one side of high-quality paper with a dry weight of 4 g/r.
d and dried to obtain a top paper.

[Performance comparison test]

(1) Chromogenicity The colored paper and top paper were stacked so that the coated surfaces faced each other, a colored image was formed by applying a load of 100 kg 7 cm2, and the color density was measured using a Macbeth densitometer (the larger the value, the higher the color density). Good color development).

(2) Whiteness The whiteness of the colored paper obtained was measured using a Hunter colorimeter (manufactured by Toyo Seiki Seisakusho).

(3) ■Layer the colored paper and clay paper so that the coated surfaces are facing each other, 100 kg/cm! A colored image was formed by applying a load of 1, and the color density was measured using a Macbeth densitometer, and the value was designated as A. Next, after exposing it to sunlight for 6 hours, the color density was measured and the value was designated as B.

Light resistance (colored area) is defined by the following formula, but if the value is 100
The closer it is, the better the light resistance is.

Lightfastness (colored part) - The color density was measured using a Maches densitometer and the value was designated as C. Light resistance (blank area)
is defined by the following formula, and the closer the value is to 100, the better the light resistance is.

Light resistance (blank area) -X100 Table 1 "effect" As shown in Table 1, The difference is color development, whiteness, I understand.

Pressure sensitive copying paper of the present invention Yes Excellent light resistance

Claims (3)

[Claims] (1) In a pressure-sensitive copying paper in which a coloring layer containing a coloring agent and a pigment is provided on a support, the pigment has an average particle size of 0.04 to 1.
．． A pressure-sensitive copying paper containing 5 μm rutile titanium dioxide. (2) The coloring agent is an organic coloring agent, the pigment contains calcium carbonate and rutile type titanium dioxide, and the calcium carbonate is 50% by weight or more of the total weight of the organic coloring agent and the pigment, and the pigment is rutile type. Claim (1) characterized in that titanium dioxide is 1 to 20% by weight of the total weight of the organic coloring agent and pigment.
Pressure-sensitive copy paper as described. (3) The average particle size of rutile titanium dioxide is 0.08 to 0.
．． The pressure-sensitive copying paper according to claim 1 or 2, which has a thickness of 4 μm.