JPH02196686A - Pressure-sensitive recording sheet - Google Patents

Abstract

PURPOSE:To obtain a pressure-sensitive recording sheet having a high color forming speed and imparting a high developed color density by incorporating a metal salt of aromatic carboxylic acid and a specific naphthol derivative in an electron acceptive coupler layer. CONSTITUTION:In a pressure-sensitive recording sheet obtaining a developed color image by the reaction of an almost colorless electron donating dye (color former) and an electron acceptive coupler (coupler), the electron acceptive coupler layer contains a metal salt of aromatic carboxylic acid and a naphthol derivative represented by general formula (I) (wherein R is an alkyl group, an aryl group, an alkylcarbonyl group, an arylcarbonyl group, an alkylsulfonyl group or an arylsulfonyl group.) As aromatic carboxylic acid in the metal salt of aromatic carboxylic acid, one having a hydroxyl group at an ortho or para position with respect to a carboxyl group is useful and, especially, a salicylic acid derivative is pref. and one having a substituent such as an alkyl group, an aryl group or an aralkyl group and containing 8 or more carbon atoms in its substituent in total is pref.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a pressure-sensitive recording sheet. More specifically, it relates to a pressure-sensitive recording sheet that obtains a colored image from the reaction between an almost colorless electron-donating dye (hereinafter referred to as a color former) and an electron-accepting color developer (hereinafter referred to as a color developer). .

(Prior art) A pressure-sensitive recording sheet includes a top sheet formed by dissolving a coloring agent in a suitable solvent and coating a support with a microcapsule layer containing microcapsules encapsulating oil droplets, and a color developer. A lower paper coated with a color developer layer on another support, and in some cases a microcapsule layer on one side of the support.
A combination of paper sheets coated with a color developer layer on the other side, or a support containing the above capsules and a color developer on the same side, or a support containing the above capsules or a color developer. There are products that contain one of these and coated with the other.

Well-known color developers for pressure-sensitive recording sheets include clay materials such as acid clay, activated clay, attapulgite, zeolite, bentonite, and kaolin, metal salts of aromatic carboxylic acids, and phenol formaldehyde resins.

Performance that a pressure-sensitive recording sheet should have is 1) high color density;

2) There is little decline in color developing ability over time.

3) Fast color development speed.

4) The color image should have excellent light resistance.

5) Less yellowing on the developing surface.

etc. can be mentioned.

Among currently known primary coloring agents, metal salts of aromatic carboxylic acids exhibit the best overall performance.

However, one of the above-mentioned performances is not sufficient in terms of color development speed, and particularly under low temperature conditions, the color development density immediately after printing is low and it takes a long time to reach the saturated density. Also, the color density is not sufficient.

(Objective of the Invention) An object of the present invention is to provide a pressure-sensitive recording sheet that has a fast coloring speed and a high coloring density.

(Invention 1**> The purpose of the present invention is to:

In a pressure-sensitive recording sheet that obtains a colored image by a reaction between a nearly colorless electron-donating dye and an electron-accepting color developer, the electron-accepting color developer layer comprises (a) a metal salt of an aromatic carboxylic acid and (b) a metal salt of an aromatic carboxylic acid;
) This was achieved by a pressure-sensitive recording sheet characterized by containing a naphthol derivative represented by the following general formula (1).

The metal salts of aromatic carboxylic acids used in the present invention are, for example, U.S. Pat.
No., Special Publication No. 51-25174, Japanese Patent Publication No. 62-1948
No. 6, JP-A No. 63-254124, etc.

The aromatic carboxylic acid in the above-mentioned metal salt of aromatic carboxylic acid is preferably one having a hydroxyl group at the ortho or bara position with respect to the carboxy group, and among these, salicylic acid derivatives are preferable, and two groups such as an alkyl group, an aryl group, an aralkyl group, etc. It is preferable that the substituents have a total number of carbon atoms of 8 or more.

Specific examples of preferred metal salts of salicylic acid derivatives used in the present invention are as follows: 3.5. -di-t-butylsalicylic acid, 3,5-di-t-octylsalicylic acid, 3,5-di-
t-nonylsalicylic acid, 3゜5-di-t-dodecylsalicylic acid, 3-methyl-5-t-dodecylsalicylic acid, 3
-t-dodecylsalicylic acid, 5-t-dodecylsalicylic acid, 5-cyclohexylcyclohexylsalicylic acid, 3
゜5-bis(α-methylbenzyl)salicylic acid, 3゜5
-bis(α,α-dimethylbenzyl)salicylic acid, 3-
Methyl-5-(α-methylbenzyl)salicylic acid, 3.
-(α,α-dimethylpencyl)-5-methylsalicylic acid, 3-(α,α-dimethylbenzyl)-6-methylsalicylic acid, 3-(α-methylbenzyl)-5-(α,α
-dimethylbenzyl)salicylic acid, 3-(α,α-dimethylbenzyl)-6-nitylsalicylic acid, 3-phenyl-5-(α,α-dimethylbenzyl)salicylic acid, carboxy-modified terpene phenolic resin, 3.5-bis( α
Examples include zinc salts, nickel salts, aluminum salts, calcium salts, etc. of salicylic acid resin, which is a reaction product of -methylbenzyl) salicylic acid and benzyl chloride.

The naphthol derivative used in the present invention has the following general formula (1)
It is expressed as

The substituent represented by R may further have a substituent<,
? Examples of IE substituents include alkyl groups, aryl groups, alkoxy groups, halogen atoms, and the like. These substituents may further have a substituent.

Among the substituents represented by R, alkyl groups having 4 to 20 carbon atoms, alkylcarbonyl groups having 2 to 20 carbon atoms, and 7 to 20 carbon atoms
20 arylcarbonyl groups are preferred.

In the above general formula, the naphthalene ring may further have a substituent, and examples of these preferable substituents include an alkyl group, a halogen atom, a hydroxy group, an alkoxy group, an aryloxy group, an alkylcarbonyloxy group, and an aryl group. Examples include carbonyloxy group, alkoxycarbonyl group, and aryloxycarbonyl group. These substituents may have additional substituents.

Among the substituents of the naphthalene ring, halogen atom, carbon number 1-
Preferred are alkyl groups having 10 carbon atoms, alkyloxycarbonyl groups having 2 to 20 carbon atoms, aryloxycarbonyl groups having 7 to 20 carbon atoms, and alkoxy groups having 1 to 10 carbon atoms.

Next, specific examples of naphthol derivatives according to the present invention are as follows: 1) 1-benzyloxynaphthalene 2) 2-benzyloxynaphthalene 3) 2-p-chlorobenzyloxynaphthalene 4) 2-
p-isopropylbenzyloxynaphthalene 5) 2-octyloxynaphthalene 6> 2-octanoyloxynaphthalene 7) 2-myristoyloxynaphthalene 8) 2-benzoyloxynaphthalene 9) 2-benzyloxy-3-benzyloxycarbonylnaphthalene 10) 1-benzyloxy-2-benzyloxycarbonylnaphthalene 11) 1-p-methoxybenzyloxynaphthalene 12) 2-β~phenethyloxynaphthalene 13) 2-
α-phenethyloxynaphthalene 14) 2-β-butoxyethoxynaphthalene 15) 2-p-toluenesulfonyloxynaphthalene 16) 1-benzyl-2-benzyloxynaphthalene 17) 2-benzyloxy-6-isopropylnaphthalene 18) 2- Benzyloxy-6-methoxynaphthalene 19) 2-benzyloxy-6-butoxycarbonylnaphthalene 20) 2,6-dimethoxynaphthalene 21) 2,3-dimethoxynaphthalene 22) 1,4-dimethoxy-2-benzylnaphthalene 23) 1 -Benzyloxy-4-methoxynaphthalene 24) 1-benzyloxy-4-ethoxynaphthalene 25) 1-benzyloxy-4-benzyloxynaphthalene 26) 1-benzyloxy-4-methylnaphthalene 27) 1-benzyloxy-4 -ethylnaphthalene28) 1-benzyloxy-4-acetyloxynaphthalene, etc.

The amount of the naphthol derivative used is 1 to 400 parts by weight, preferably 5 to 200 parts by weight, per 100 parts by weight of the metal salt of aromatic carboxylic acid.

Metal salts of aromatic carboxylic acids and naphthol derivatives are used after being mechanically dispersed in an aqueous system using a ball mill, an attritor, a sand mill, or the like. Metal salts of aromatic carboxylic acids and naphthol derivatives.

They may be distributed and processed separately, or both may be distributed and processed together.

When adjusting the coating solution, use of inorganic pigments such as titanium oxide, zinc oxide, silicon oxide, calcium carbonate, aluminum hydroxide, kaolin, activated clay, talc, barium sulfate, magnesium oxide, etc. can improve coating suitability and hiding power. Favorable effects such as improved color developing ability can be obtained. The preferred amount of the inorganic pigment used is 1 to 1 part by weight of the color developer.
00 parts by weight, and more preferably 2 to 40 parts by weight.

Binders for the coating solution include latexes such as styrene-butadiene copolymer latex, vinyl acetate latex, and acrylic ester latex, polyvinyl alcohol, polyacrylic acid, maleic anhydride-styrene copolymer, starch, casein, Synthetic or natural polymeric substances such as gum arabic, gelatin, carboxymethylcellulose, methylcellulose, etc. are used.

The final amount of developer applied to the support was 0°1 g/
m" ~ 3.0g/m" preferably 0.2g/m" ~
The 1.0 g/m proverb is appropriate.

Color formers that react with the color developer used in the recording sheet of the present invention are not particularly limited, but include triphenylmethane phthalide compounds, fluoran compounds, phenothiazine compounds, indolylphthalide compounds, and indolyl azaphthalide compounds. compound, leucoauramine compound, rhodamine lactam compound, triphenylmethane compound,
Examples include triazene compounds and spiropyran compounds.

The color former is dissolved in a solvent, encapsulated, and applied to a support.

As a solvent, natural or synthetic oils can be used alone or in combination. Examples of solvents include kerosene, paraffin, naphthenic oil, alkylated biphenyls, alkylated terphenyls, chlorinated paraffins, alkylated naphthalenes, diarylalkane, phthalate esters, and the like.

As a method for producing color former-containing microcapsules, interfacial heavy metal method, internal polymerization method, phase separation method, external polymerization method, core cell page method, etc. are used.

In preparing a coating solution containing microcapsules containing a color former, a water-soluble binder or a latex binder is generally used. Furthermore, a capsule shin protectant such as cellulose powder, starch particles, talc, etc. is added to obtain a microcapsule coating liquid containing a coloring agent.

The performance of the color developer sheet for pressure-sensitive recording paper of the present invention was tested using the following color former-containing microcapsule sheet.

[Preparation of microcapsule sheet containing color former] 5.0 g of crystal violet lactone, 1°0 g of benzoyl leucomethylene blue and 3-[4-(
dimethylamino)-2-ethoxyphenyl] -3-(
2-Methyl-1-ethyl-3-indolyl)-4-azaphthalide2. Og to diimpropylnaphthalene 100g
dissolve in To this oily liquid, 15 g of an adduct of 37 tolylene diincyanate/1 mole of trimethylolpropane was added as a polyvalent isocyanate, and a butylene oxide adduct of ethylenediamine was added as an alkylene oxide adduct of amine (the number of moles of butylene oxide added to ethylene diamine was 16 g). 8 mol, molecular weight 1267>3.0g
was dissolved to prepare a primary solution.

Next, 10 g of polyvinyl alcohol and 5 g of carboxymethyl cellulose were dissolved in 140 g of water to prepare a secondary solution. While vigorously stirring the secondary solution, the primary solution was poured to form an oil-in-water emulsilane. When the size of the oil droplets reached 6°0μ, stirring was weakened, and then 100g of water at 20°C was added to this emulsion, the temperature of the system was gradually raised to 65°C, and at this temperature 90°C I kept it.

To the capsule liquid thus obtained, 80 g of a 15% aqueous solution of polyvinyl alcohol, 20 g of solid content of carboxy-modified SBR latex, and starch particles (average particle size 15 μm) were added.
)60g was added.

Next, water was added to adjust the solid content concentration to 20% to prepare a coating solution.

Apply this coating solution to a dry weight of 4.0 g/-.
It was coated on 0g1rlK paper using an air knife coater and dried to obtain a microcapsule sheet.

The color developer sheet for pressure-sensitive recording paper of the present invention will be specifically explained below with reference to Examples, but the invention is not limited to these Examples.

(Examples of the invention) Examples 1-1 to I-8 and comparative example Summer [Preparation of dispersion] 3.5-bis(α-methylbenzyl)zinc salicylate 1
A dispersion (A ) was obtained.

[Adjustment of coating liquid]

100 parts of a 10% PVA-117 (manufactured by Kuraray) aqueous solution and 7 parts (as solid content) of carboxy-modified SBR latex (manufactured by Sumitomo Naugatac, 5N307) were added to 300 parts of dispersion liquid (A), so that the solid content concentration was 20%. Water was added to obtain a coating solution.

[Application of color developer sheet]

This coating liquid was applied to a 50 g/m'' base paper using an air knife coater so that the solid content was 5.0 g/m1, and dried to obtain a color developer sheet.

Examples 11-1 to n-4 and Comparative Example ■ [Preparation of dispersion liquid] 15 parts of zinc 3.5-di-t-octylsalicylate, 1st
6 parts of the naphthol derivative shown in the table, 120 parts of calcium carbonate
A dispersion (B) was obtained which was atomized from sand mill camphor using 20 parts of kaolin, 20 parts of zinc oxide, 1 part of sodium hexametaphosphate and 2.0 parts of water.

[Adjustment of coating liquid]

100 parts of 10X PVA-117 (manufactured by Kuraray) aqueous solution and 5 parts (as solid content) of carboxy-modified SBR latex (manufactured by Sumitomo Naugatac, 5N-307) were added to 300 parts of dispersion liquid (B), so that the solid content concentration was 20%. Water was added to obtain a coating liquid.

[Application of color developer sheet]

Apply this coating liquid to 50g/rrr(7)jI paper at 5.0g/+
It was coated with an air knife coater so that the solid content of rr was coated and dried to obtain a color developer sheet.

An evaluation test was conducted using a combination of each of the color developer sheets and color former-containing microcapsule sheets as an angry pressure recording sheet, and the results are listed in Table 1. The evaluation test was conducted using the following method.

(1) Color development speed and color density test Color developer sheet and color developer-containing microcapsule sheet
The microcapsule layer of the color developer-containing microcapsule sheet was placed on the color developer sheet in the constant temperature and constant temperature room for at least 1 hour.
A load pressure of 00 b/cnt was applied for 1 second to develop color. Measure the density (D,) 15 seconds after pressurization using a Macbeth reflection densitometer.

Thereafter, this non-colored developer sheet was left at room temperature (25°C) for 24 hours, and the density (D2) was measured using a Macbeth reflection densitometer.
) was measured.

The Dt/D+a ratio was defined as the color development rate, and D2 was defined as the color development density.

As shown in Table 1, the color developer sheet of the present invention has excellent color development speed and color density, and has extremely good performance compared to the comparative color developer sheet.

Claims (1)

[Scope of Claims] A pressure-sensitive recording sheet that obtains a colored image by a reaction between a nearly colorless electron-donating dye and an electron-accepting color developer, the electron-accepting color developer layer comprising (a) an aromatic carboxylic acid; Metal salt and (b
) A pressure-sensitive recording sheet characterized by containing a naphthol derivative represented by the following general formula (I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) In the above formula, R represents an alkyl group, an aryl group, an alkylcarbonyl group, an arylcarbonyl group, an alkylsulfonyl group, or an arylsulfonyl group.