JPH04185483A - Production of liquid dispersed with color developing agent for pressure-sensitive recording paper - Google Patents

Abstract

PURPOSE:To obtain a liquid dispersed with color developing agent having high coloring rate and high stability in long term preservation by employing an ethyl cyanide polyvinyl alcohol as the dispersant. CONSTITUTION:An ethyl cyanide polyvinyl alcohol is produced by reacting polyvinyl alcohol with acrylonitrile under existence of alkaline such as NaOH and then substituting an ethylcyano group for the hydrogen atom of alcoholic hydroxide group in the molecule of polyvinyl alcohol where the polyvinyl alcohol preferably has saponification value higher than 85mol% and degree of polymerization in the range of 300-2000. It is added by 0.1-20wt.% to a color developing agent to be saponified. Organic soluvent solution of the color developing agent is added by 10-200wt.% to water and the average diameter of saponificated particle is preferably smaller than 2.0mum.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing a color developer dispersion for pressure-sensitive recording paper.

(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 combination of a bottom paper with a color developer layer coated on another support, and in some cases, a middle paper with a microcapsule layer coated on one side of the support and a color developer layer coated on the other side; Alternatively, there is one in which the capsule and the color developer are contained on the same side of the support, or one in which the capsule or the developer is contained in the support and the other is coated.

As color developers for pressure-sensitive recording sheets, acid clay, activated clay, attapulgite, zeolite, bentonite, clay materials such as kaolin, polyvalent metal salts of aromatic carboxylic acids or derivatives thereof, phenol formaldehyde resins, etc. are well known. ing.

The properties that a pressure-sensitive recording sheet should have are: 1) fast color development speed and no decline in color developing ability over time;

2) The coloring body has excellent light resistance.

3) There is little yellowing of the developing surface when exposed to light.

4) The color forming body has excellent water resistance and plasticizer resistance. 5) There is little yellowing of the color developing surface due to nitrogen oxides in the air.

etc. can be mentioned.

Among currently known color developers, polyvalent metal salts of aromatic carboxylic acids or derivatives thereof exhibit the best performance, but they are still insufficient in terms of color development speed.

A color developer dispersion using a metal salt of an aromatic carboxylic acid is prepared by mechanically adding the color developer to water using a sand mill, attritor, ball mill, etc. together with an inorganic pigment, a binder, a dispersant, and other additives. Generally, particles are obtained by dispersion, but with this type of pulverization method, particle aggregation tends to occur when dispersing at a high concentration, so it is difficult to obtain a stable dispersion with a high developer concentration. Very difficult. Furthermore, there is a limit to the atomization of color developer particles, making it impossible to obtain a sufficient color development rate. On the other hand, if a color developer is dissolved in an organic solvent and emulsified in water in the presence of a dispersant, the color developer particles can be finely divided and a highly concentrated emulsified dispersion can be obtained. Because it exists in droplets containing particles, coalescence of particles, phase separation, etc. occur, causing problems in storage stability. Japanese Patent Publication No. 63-984
No. 83 describes a method of preparing a color developer dispersion by dissolving a color developer in an organic solvent, emulsifying it in water containing a dispersant, and then removing the organic solvent. Agglomerates sometimes occur, and the liquid has poor thermal stability when heated for a long period of time, making it unfavorable in terms of suitability for production.

(Objective of the present invention) An object of the present invention is to provide a method for producing a color developer dispersion that has a fast color development rate, high stability during long-term storage, and is suitable for production.

(Structure of the Invention) An object of the present invention is to dissolve a color developer in an organic solvent and emulsify it in water in the presence of a dispersant to produce a color developer emulsion dispersion, or to remove the organic solvent after emulsification. This was achieved by using cyanoethylated polyvinyl alcohol as a dispersant in a method for producing a color developer dispersion.

By using the cyanoethylated polyvinyl alcohol of the present invention as a dispersant, the stability of the emulsion and the stability during desolvation can be improved, and a color developer dispersion with excellent handling and storage stability can be produced. Obtainable.

The cyanoethylated polyvinyl alcohol used in the present invention is a mixture of polyvinyl alcohol and acrylonitrile.
The reaction is carried out in the presence of an alkali such as OH, and the hydrogen atom of the alcoholic hydroxyl group in the molecule of polyvinyl alcohol is replaced with a cyanoethyl group. The polyvinyl alcohol used for cyanoethylation preferably has a saponification degree of 85 mo1% or more, more preferably 95 mo1% or more. In addition, the degree of polymerization of polyvinyl alcohol is 300~
A range of 2000 is preferred.

Although the degree of cyanoethylation can be changed arbitrarily by selecting reaction conditions for cyanoethylation, a preferable range is 2 to 50 mol%.

The cyanoethylated polyvinyl alcohol of the present invention can also be used in combination with other water-soluble polymers.

Other water-soluble polymers include polyvinyl alcohol, polyacrylamide, sodium polyacrylate, polyvinyl ether, sodium polystyrene sulfonate, maleic anhydride copolymer, and the like.

The amount of cyanoethylated polyvinyl alcohol is 0.00% relative to the amount of color developer to be emulsified. It is used in a range of 1 to 20% by weight, more preferably 0. 5 to 10% by weight.

In addition, when emulsifying an organic solvent solution in which a color developer is dissolved in water, together with the cyanoethylated polyvinyl alcohol,
Ionic or nonionic surfactants can be used in combination. Surfactants used include alkylbenzenesulfonates, alkylnaphthalenesulfonates, alkylsulfonates, dialkylsulfosuccinates, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyhydric alcohol fatty acid moieties. Examples include esters.

Moreover, an inorganic alkali metal salt can also be added during emulsification. Examples of inorganic alkali metal salts include carbonates, sulfates, nitrates, phosphates, etc., with sodium carbonate being particularly preferred.

The organic solvent that dissolves the color developer is one that dissolves the color developer in 10% or more, preferably 20% or more, and has a solubility in water of 10% or more.
% or less is preferable. Specific examples of the organic solvent required in the present invention include toluene, ethylbenzene, xylene, α-methylnaphthalene, dimethylnaphthalene, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, ethyl acetate, butyl acetate, amyl acetate, butanol, benzyl alcohol, Cresol, carbon tetrachloride,
Examples include dichloromethane, chloroform, paraffin, solvent naphtha, cottonseed oil, paraffin oil, naphthenic oil, alkylated biphenyls, alkylated terphenyls, chlorinated paraffins, alkylated naphthalenes, diphenylalkanes, and the like. In addition, the organic solvent used when dissolving the color developer is heated at normal pressure after emulsification to bring it azeotropically with water.
Alternatively, it can be used after being removed by a method such as vacuum distillation. In particular, when removing organic solvents, it is preferable to use methyl isobutyl ketone, toluene, or xylene.

The color developer is dissolved in the above solvent in an amount of 20 to 250% by weight, preferably 40 to 200% by weight.

Further, additives such as antioxidants and ultraviolet absorbers can be dissolved and emulsified in an organic solvent together with a color developer.

The organic solvent solution of the color developer is 10 to 200% by weight based on water.
, preferably 30 to 150% by weight and emulsified. The average emulsion particle size is 2. It is preferably 0 μm or less, more preferably 0.1 to 1. It is preferable to set the thickness to about 0 μm.

When preparing a 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, and improve visibility. Favorable effects such as improved color performance 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.

As a binder for the coating liquid, polyvinyl alcohol,
Polyacrylic acid, maleic anhydride-styrene copolymer,
Synthetic or natural polymeric substances such as starch, casein, gum arabic, gelatin, carboxymethylcellulose, methylcellulose, etc. are used.

The final amount of developer applied to the support ranges from 0.1 to 3.
0 g/m2, preferably 0.2 to 1.0 g/m2.

The color forming agent that reacts with the color developer used in the recording sheet of the present invention is not particularly limited, but includes triphenylmethane phthalide compounds, fluoran compounds, phenothiazine compounds, indolyl phthalide compounds, and leuco auramine compounds. , rhodamine lactam compounds, triphenylmethane compounds, triazene compounds, spiropyran compounds, and fluorene compounds.

The color former is dissolved in a solvent, encapsulated, and applied to a support. As the solvent, natural or synthetic oils can be used alone or in combination. Examples of solvents include cottonseed oil,
Kerosene, paraffin oil, naphthenic oil, alkylated biphenyls, alkylated terphenyls,! Examples include hydrogenated paraffins, alkylated naphthalenes, diphenylalkanes, and the like.

As a method for manufacturing the color former-containing microcapsules, an interfacial polymerization method, an internal polymerization method, a phase separation method, an external polymerization method, a coacervage method, etc. are used.

A water-soluble binder or a latex binder is generally used to prepare a coating solution containing microcapsules containing a color former. Further, cellulose powder, starch particles, talc, etc. are added as a capsule protectant to obtain a coloring agent-containing microcapsule coating solution.

The performance of the color developer sheet for pressure-sensitive recording 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° Og of penzoylloif methylene blue and 3-+4-(diethylamino)-2-ethoxyphenyl l-3-(2) were used as color formers.
3.0 g of -methyl-1-ethyl-3-indolyl)-4-azaphthalide are dissolved in 100 g of diisopropylnaphthalene. Add carbodiimide-modified diphenylmethane diincyanate (manufactured by Nippon Polyurethane Co., Ltd., trade name "Millionate MTLJ") as a polyvalent incyanate to this oily liquid.
), 5 g of incyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Co., Ltd., trade name "Coronate EHJ") and an alkylene oxide adduct of amine, a butylene oxide adduct of ethylenediamine (addition mole of butylene oxide to ethylenediamine is 16 .8 mol, molecular weight 1267) 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 into the secondary solution to form an oil-in-water emulsion. When the size of the oil droplets reached 7.0 μm, stirring was weakened, and then 100 g of water at 20°C was added to this emulsion, and the temperature of the system was gradually raised to 65°C and maintained at this temperature for 90 minutes. Ta.

To the capsule liquid thus obtained were added 80 g of a 15% aqueous solution of polyvinyl alcohol, 30 g of carboxylic modified SBR latex in solid content, and 60 g of powder particles (average particle diameter 15 μm).

Next, water was added to adjust the solid content concentration to 20% to prepare a coating solution. The dry weight of this coating liquid was 4.0g/r.
The mixture was coated onto a base paper of 40 g/m'' using an air knife coater so as to have n2, and dried to obtain a microcapsule sheet.

The color developer sheet for pressure-sensitive recording of the present invention will be specifically explained below with reference to Examples, but the invention is not limited to these Examples. Note that parts in each example represent weight unless otherwise specified.

(Examples of the invention) Example I [Preparation of color developer emulsion dispersion] 3. 100 parts of 5-di(α-methylbenzyl)zinc salicylate is dissolved in 80 parts of xylene to prepare a color developer xylene solution. Add 45 parts of water to 25 parts of a 10% aqueous solution of cyanoethylated polyvinyl alcohol (cyanoethylated ft5mo+%, degree of polymerization 300, degree of saponification approximately 98.5mo1%), and further add 5 parts of a 5% aqueous sodium lauryl sulfate solution, 1
0% sodium carbonate aqueous solution 1. Add 130 parts of the above color developer xylene solution to the aqueous phase to which 5 parts were added, and use a homogenizer (Nippon Seiki, Model AM-7) to reduce the average particle size to 1.
．． It was emulsified to a thickness of 0 μm. 130% in this emulsion
After adding 30% of water, the emulsion was heated, xylene was removed from the emulsion by azeotroping with water, and the solid content concentration was adjusted to 30% to prepare a color developer emulsion dispersion.

[Preparation of coating solution] 200 parts of water, 5 parts of 40% sodium hexametaphosphate aqueous solution, and calcium carbonate (manufactured by Shiraishi Kogyo, Br1111)
ant15, average particle size 0.5μ) 120 parts, activated clay 1
0 parts and 20 parts of zinc oxide were added and uniformly dispersed using a sand grinder to obtain an average particle size of 2 μm to obtain a dispersion.

Add 300 parts of this dispersion to PVA-117 (Kuraray!
20 parts of a 0% 10% aqueous solution was added, and 33 parts of the above color developer emulsified dispersion were added, and water was added so that the solid content concentration was 20% to obtain a coating liquid.

[Preparation of Color Developer Sort] This coating solution was bar coated onto a 50 g/m2 base paper so that the solid content was 5.0 g/m2, and dried to obtain a color developer sheet.

Example ■ Cyanoethylated polyvinyl alcohol (cyanoethylation degree 5m) used in Example I [Preparation of color developer emulsion dispersion]
ol%, degree of polymerization 300, degree of saponification approximately 9'8.5mol%
) Instead of 25 parts of a 10% aqueous solution, 25 parts of a 10% aqueous solution of cyanoethylated polyvinyl alcohol (degree of cyanoethylation: 5 mo1%, degree of polymerization: 500, degree of saponification: about 98.5 mo1%) was used. A color developer emulsion dispersion and a color developer sheet were obtained.

Example ■ Cyanoethylated polyvinyl alcohol (cyanoethylation degree 5) used in Example I [Preparation of IJ colorant emulsion dispersion]
mo 1%, degree of polymerization approximately 3001 degree of saponification approximately 98.5 mo1
%) Instead of 25 parts of a 10% aqueous solution, use cyanoethylated polyvinyl alcohol (cyanoethylation degree 15mo 1%).
, degree of polymerization 500, degree of saponification approximately 98.5 mo1%) 10%
A color developer emulsion dispersion and a color developer sheet were obtained in the same manner as in Example I except that 25 parts of the aqueous solution was used.

Example ■ Cyanoethylated polyvinyl alcohol (cyanoethylation degree 5m) used in Example ■ [Preparation of color developer emulsion dispersion]
o 1%, degree of polymerization 300, degree of saponification approximately 98.5mol1%
) Instead of 25 parts of 10% aqueous solution, cyanoethylated polyvinyl alcohol (cyanoethylation degree 15mo 1%,
Degree of polymerization: 1000, degree of saponification: approximately 98.5 mo1%) 10%
A color developer dispersion and a color developer sheet were obtained in the same manner as in Example I except that 25 parts of the aqueous solution was used.

Example V Cyanoethylated polyvinyl alcohol (cyanoethylation degree 5m) used in Example I [Preparation of color developer emulsion dispersion]
o 1%, degree of polymerization 300, degree of saponification approximately 98.5mol1%
) Instead of 25 parts of a 10% aqueous solution, 25 parts of a 10% aqueous solution of cyanoethylated polyvinyl alcohol (degree of cyanoethylation 30 mo1%, degree of polymerization 500, degree of saponification approximately 98.5 mo1%) was used. A color developer dispersion and a color developer sheet were obtained.

Comparative Example ■ Cyanoethylated polyvinyl alcohol (cyanoethylation degree 15) used in Example ■ [Preparation of color developer emulsion dispersion]
mo1%, polymerization degree 500, saponification degree approximately 98.5 mo1%
) Instead of 25 parts of 10% aqueous solution, use polyvinyl alcohol (Kuraray L PVA-105, saponification degree of about 98.5m)
A color developer dispersion and a color developer sheet were obtained in the same manner as in Example 2, except that 25 parts of a 10% aqueous solution was used.

Comparative Example■ Example ■ [Cyanoethylated polyvinyl alcohol used in Preparation 1 of Color Developer Emulsified Dispersion (degree of cyanethylation 15)]
mo 1%, degree of polymerization 1000, degree of saponification approximately 98.5mo
1%) 25 parts of 10% aqueous solution, polyvinyl alcohol (manufactured by Kuraray, PVA-110, degree of saponification approximately 9)
8.5mo1%, degree of polymerization 1000) 10% aqueous solution 25
A color developer dispersion and a color developer sheet were obtained in the same manner as in Example 2, except that 100% of the color developer was used.

Comparative Example ■ [Preparation of coating solution] 200 parts of water, 5 parts of 40% sodium hexametaphosphate aqueous solution, 12 parts of zinc 3.5-di(α-methylbenzyl)salicylate, calcium carbonate (manufactured by Shiraishi Kogyo, Brj
lliant 15, average particle size 0.5μ), 10 parts activated clay, and 20 parts zinc oxide were added and uniformly dispersed using a sand grinder to obtain an average particle size of 2μ to obtain a dispersion. 300 parts of this dispersion 1. :PVA-117(F
5) 200 parts of a 10% aqueous solution was added and water was added so that the solid content concentration was 20% to obtain a coating liquid.

[Preparation of Color Developer Sheet 1 This coating solution was bar coated onto a 50 g/m2 base paper so that the solid content was 5.0 g/m2, and dried to obtain a color developer sheet.

The stability of each dispersion during desolvation and the color development of the color developing sheet were evaluated as follows, and the results are summarized in Table 1.

(Stability during desolvation) 300 g of color developer dispersion obtained by removing the organic solvent by heating
was filtered through a sieve with a mesh size of 22 μm, and the dry weight of the residue on the sieve was measured to evaluate stability.

The smaller the residual amount, the better the stability during desolvation.

(Color development test) The microcapsule layer of the color former-containing microcapsule sheet was layered on a color developer sheet, and a pressure of about 300 kg/cm 2 was applied to develop color. The density Dr after 15 seconds and the density D2 after being left at room temperature for 24 hours were measured using a Macbeth reflection densitometer.

Table 1 As can be seen from Table 1, the color developer dispersion of the present invention has good stability during desolvation and has a fast color development rate.

Claims (2)

[Claims] (1) For pressure-sensitive recording paper characterized in that cyanoethylated polyvinyl alcohol is used as a dispersant when dissolving a color developer containing a substituted salicylic acid metal salt as a main component in an organic solvent and emulsifying and dispersing it in water. A method for producing a color developer dispersion. (2) The method for producing a color developer dispersion for pressure-sensitive recording paper according to claim (1), wherein the cyanoethylated polyvinyl alcohol has a degree of cyanoethylation of 2 to 50 mol%.