JPS59202889A - Manufacture of pressure sensitive recording sheet - Google Patents

Abstract

PURPOSE:To improve color-forming property and reduce fogging due to self color forming by using aqueous emulsion of organic color-developing agent resolved in an organic solvent of specific boiling point and urine-formaldehyde resin or melamine as a capsule wall material including color forming agent. CONSTITUTION:An organic color developing agent is resolved in an oragnic solvent of boiling point of 150-330 deg.C and after emulsion in water with an agitator, a color-developing coating is manufactured. Then, as the main wall material of capsule, a capsule coating liquid including a color-forming agent is manufactured using melamine-formaldehyde or urine-formaldehyde resin. A simultaneous multi-layer curtain is manufactured by a curtain coating method from a paper carrier sheet coated with capsule liquid and color-developing liquid and a single-layer curtain film is manufactured by a mixing method. A pressure- sensitive recording sheet of self-color-forming type is credited with high color- forming intensity and speed and the fogging by humidity can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a self-coloring pressure-sensitive recording sheet.

Conventionally, various types of pressure-sensitive recording sheets are known, but a layer containing a color developer (hereinafter referred to as a "color developer layer") is coated on the same side of a support. A self-coloring pressure-sensitive recording sheet coated with a layer containing both a capsule containing a color former and a color developer is known.

However, clay, which is currently widely used as a color developer for pressure-sensitive papers, such as activated clay or acid clay, is applied onto the capsule coating layer or mixed with the capsule coating and applied to develop self-coloring. When molded recording paper is made, it has drawbacks such as poor light resistance or water resistance of the coloring material, and poor stability over time.

Organic color developers are known as color developers that have improved these drawbacks.

Color developer coating liquids using these organic color developers are generally obtained by mechanically dispersing the color developer together with inorganic pigments, binders, dispersants, and other additives in water.

When self-coloring pressure-sensitive recording paper is made by coating this developer coating on the capsule coating layer or by mixing it with the capsule coating, the disadvantages of using the above-mentioned clay are: Solvable. However, if the organic color developer is merely mechanically dispersed, the particle size is large and the organic color developer is scattered on the coating layer. For this reason, when the capsule is destroyed and the color former is released, the efficiency of contact with the organic color developer is reduced, resulting in a fatal drawback that the color development speed is slow and the color development density is low. In order to solve this problem, attempts have been made to increase the amount of organic color developer applied, but it has been disclosed that the organic color developer itself has a very high color content and is used by dissolving it in an oily substance and encapsulating it. Although this method is somewhat effective, since the organic color developer is encapsulated, unless the capsule is completely destroyed, the organic color developer will not be released from inside the capsule, reducing the efficiency of contact with the color former. However, they have the disadvantages of slow color development and difficulty in achieving density. Further, dissolving the color developer in an oily substance and encapsulating it requires a very large amount of time, which is disadvantageous in production.

Therefore, an object of the present invention is to provide a self-coloring type pressure-sensitive recording sheet that can solve the above-mentioned drawbacks, exhibit excellent coloring properties with the use of a small amount of color developer, and have less self-coloring fog. An object of the present invention is to provide a method for manufacturing a pressure-sensitive recording sheet.

The above-mentioned object of the present invention is that a layer containing microcapsules containing a color former and a layer containing a color developer that develops a color by contacting the color former are coated on the same surface of a support. A method for producing a self-coloring pressure-sensitive recording sheet comprising microcapsules containing microcapsules and a layer containing a color developer that develops a color when in contact with the color former, wherein a coating liquid containing the color developer is provided. contains a water emulsion of an organic color developer dissolved in an organic solvent having a boiling point of 1RO0C to 3.300C, and uses melamine formaldehyde resin or urea-formaldehyde resin as the wall material of the capsule containing the color former. This was achieved by a method for producing a self-coloring pressure-sensitive recording sheet.

The manufacturing method according to the present invention includes five self-coloring pressure-sensitive recording sheets having various layer configurations, for example: (1) a capsule layer provided as a lower layer and an upper layer provided on the same surface of a support;
(3) Applicable to microcapsules containing a color former and a color developer contained in one layer.

In the present invention, when capsules containing gelatin and a coloring agent prepared by the coacervate method are used, the gelatin capsules have poor wall density, resulting in fogging and self-coloring when stored under high humidity. ing.

On the other hand, melamine obtained by external polymerization method
Capsules with formaldehyde polymerized walls or urea-formaldehyde polymerized walls are outstanding.

These two products have excellent wall tightness and are highly water resistant, so it can be said that they do not cause self-coloring fog because the coloring agent is tightly encapsulated within the capsule.

As the organic color developer used in the present invention, aromatic carboxylic acids and metal salts thereof, or phenolic resins are preferable.

Examples of these aromatic carboxylic acids and their metal salts include Japanese Patent Publication Sho≠2-10za56, U.S. Pat.
Examples include those described in No. 4'4 and No. 3,913,292.

The above-mentioned aromatic carboxylic acids are useful those having a hydroxyl group at the ortho or -ξ position with respect to the carboxy group, and salicylic acid derivatives are particularly preferred; Particularly preferable are those having substituents such as , aryol group, aralkyl group, etc., and the total number of carbon atoms of the substituents is r or more.

Examples of particularly preferred aromatic carboxylic acids include 3! −
Di-t-butylsalicylic acid, 3. J-di-1-amylsalicylic acid, 3. ! -bis(α,α-dimethylbenzyl)
salicylic acid, 3. ! -bis(α-methylbenzyl)salicylic acid, 3-(α-methylbenzyl)-4-(α,α-
dimethylbenzyl)salicylic acid, 3. ! -di-t-octylsalicylic acid, 3-cyclohexyl-j(α,α-dimethylbenzyl)salicylic acid, and the like.

In addition, the metals for forming metal salts with the above aromatic carboxylic acids include magnesium, aluminum, calcium, scandium, titanium, vanadium, chromium, manganese, iron,
Examples include cobalt, nickel, copper, zinc, h')'y, germanium, strontium, yttrium, zirconium, molybdenum, cadmium, indium, tin, antimony, barium, tungsten, lead, and bismuth. Among these metals, the most effective are zinc,
These include tin and aluminum.

The most effective of these is zinc.

As Saraniphenol resins, Tokko Shogu λ-20/'
The so-called novolak type phenol resin shown in No. A≠ is known, and phenol formaldehyde resin, phenol acetaldehyde resin, and phenol acetylene resin are used. For example, p-cresol, I]-ethylphenol, p-7f ruphenol,
p-alkylphenols such as p-cyclohexylphenol, p-octylphenol, and p-nonylphenol; aralkylphenols such as p-phenylphenol and allylphenols; α-naphthylphenol, β-naphthylphenol, cumylphenol, and benzylphenol; Examples include polycondensation resins of halogenated phenols such as phenol m and p-chlorophenol with formaldehyde or acetaldehyde, and so-called metal salt-modified phenol resins obtained by modifying these with zinc, manganese, etc.

Two or more types of these color developers can also be used.

The solvent used in the present invention has a boiling point of /j00c to 330
°C and is preferably an organic solvent that further dissolves 10% or more of the organic color developer. For example, aliphatic or aromatic esters, biphenyl-derived 4L-naphthalene-derived L-biphenyl alkanes, and the like can be mentioned. Specifically, /-isopropylphenyl, 2-phenylethane, methylamyl acetate (/, 3-dimethylbutyl acetate) 1.2-ethylbutyl acetate, λ-
Ethylhexyl acetate, amyl propionate, n
-Butyl butyrate, 1so-butyl-is.

-butyrate, 2,2. ≠-trimethyl-/, 3-bentanediol monoimbutyrate, 2,2゜≠-trimethyl-7,3-bentanediol diisobutyrate, λ
, Goo-dimethyl-co, ≠-bentanediol diacetate, 2,2-dimethyl-/, 3-butanediol diisobutyrate, λ-methyl-co, Hiro-pentanediol dipropionate,! l 3j 3j goutetramethylco, goubentanediol monoacetate, amyl lactate), J-methylbiphenyl, 3-methylbifu x
= -A/, 3, 3-') y' Tilbiphenyl, co.

≠-dimethylbiphenyl, 2. O-dimethylbiphenyl, 2. ≠rl')! J methylbiphenyl, cyclohexylbenzene, bicyclohexylbenzene, monoisopropylbiphenyl, monoinopropylnaphthalene, diimpropylnaphthalene, methylphenylxylylmethane, and the like.

A poor solvent such as a petroleum fraction having a boiling point of lso 0c to 3300c may be used in combination with these solvents as a diluent.

In the present invention, if a solvent with a boiling point lower than 1j00C is used, evaporation will occur during the coating process, resulting in poor workability. On the other hand, a solvent with a boiling point higher than 3300C is not advantageous because it is difficult to evaporate during the drying process after coating. That is, if the solvent remains in the coated paper, the color developing ability and the resistance of the color former will be impaired.
1o-so is dissolved. This organic solvent solution is emulsified in water using a stirrer or the like to form a coating liquid.

The organic solvent solution is preferably 100% soluble in water.
Add approximately 0% of 3Q-♂ and emulsify.

In this case, adding an ionic or nonionic surfactant water-soluble polymer has the advantage that a stable emulsion can be prepared in a short time.

Furthermore, when preparing the coating solution, inorganic pigments such as titanium oxide, zinc oxide, silicon oxide, calcium oxide, calcium carbonate, aluminum hydroxide, kaolin, Merck, barium sulfate, etc. can be used in combination to improve coating suitability, hiding power, and color developing ability. Desirable effects such as improvement in performance can be obtained. The desirable combined use amount is /-1000 parts, more preferably 2 to 50 parts, based on the oil-soluble acidic substance. A binder is added to the coating liquid thus obtained.

Binders for cholera include those generally known in the art, such as latexes such as styrene-butadiene copolymer latex, polyvinyl alcohol, maleic anhydride-styrene copolymer, starch, casein,
Synthetic or natural polymeric substances such as gum arabic, gelatin, carboxymethyl cellulose, and methyl cellulose can be used.

When applied mixed with microcapsules containing a color former or applied on a layer coated with a microcapsule solution, the final amount of organic color developer is 0°/, iil 7m
2-3, 0, j97m2 preferably o, 2g/m2
~/, Og/m2 is suitable.

The color former that reacts with the color developer of the present invention is not particularly limited, but specific compounds of these color formers are (1)
) 1.1 As an allylmethane compound, 3゜3-bis(p-dimethylaminophenyl)-A-dimethylaminophthalide (i.e., crystal violet lactone),
3.3-bis(p-dimethylaminophenyl)phthalide, 3-(p-dimethylaminophenyl)-3-(/,2
-dimethylindol-3-yl)phthalide, 3-(
p-dimethylaminophenyl)-3-(2-methylindol-3-yl)phthalide, 3-(p-dimethylaminophenyl)-j-(2-phenylindol-3-yl)phthalide, 3,3-bis -(/.

λ-dimethylindole-3-yl)-! -dimethylaminophthalide, 3,3-bis(/,2-dimethylindol-3-yl)-6-dimethylaminophthalide, 3,
3-bis(terethylcarbazol-3-yl) -1
-dimethylaminophthalide, 3,3-bis(2-phenylindol-3-yl)-! -dimethylaminophthalide, 3-p-dimethylaminophenyl-j-(/-methylbi-l-λ-yl)-6-dimethyl-amino7thalide, etc.; C2) as a diphenylmethane compound, ≠.

3'-bis-dimethylaminobenzhydrin benzyl ether, N-halophenylleucoolamine, N-2,
≠, j−1')? Lolophenyl leuco auramine etc.; (
3) Rhodamine B-anilinolactam, Rhodamine B-p nitroanilinolactam, Rhodamine B-p-chloroanilinolactam, λ-
Dimethylamino-7-medoxyfluorane, λ-diethylamino-7-methoxyfluorane, 3-diethylamino-7-methoxyfluorane, 3-diethylamino-7
-Chlorofluorane, λ-diethylamino-3-di0t
ff-7-mer/-fluorane, 7-diethylamino-, z , , 2-dimethylfluorane, 7-diethylamino-3-acetylmethylaminofluorane, 7-
Diethylamino-3'-methylaminofluorane, 3-
Diethylamino-6-methyl-7-anilinofluorane, 3,7-dinitylaminofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-methylbenzylamino-fluorane, 3-
Diethylamino-7-chloroethylmethylaminofluorane, 3-diethylamine-7-ethylaminofluorane, etc.; (4) Thiazine compounds such as benzoylleucomethylene blue, p-nitrobenzoylleucomethylene blue, etc.; (5) Spiro compounds 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-
Dinaphthopyran 3, 3/-Cyclolosespiro-dinaphthopyran, 3-benzylspiro-dinaphthopyran, 3
-Methyl-naphtho-(3-methoxy-benzo)-spiro-bilane, 3-propyl spirodi, ndzopyran, etc.
Alternatively, a mixture thereof can be mentioned.

As a solvent for dissolving these coloring agents, natural or synthetic oils can be used alone or in combination. As examples of solvents, mention may be made of cottonseed oil, kerosene, paraffin, naphthenic oil, alkylated biphenyls, alkylated terphels, alkylated naphthalenes, diarylethanes, triarylmethanes, chlorinated nografins, and the like.

Melamine-formaldehyde resin or urea-formaldehyde resin is used as the main wall material of the capsule.

Furthermore, capsule protectants, such as cellulose powder, starch particles, and talc, which have been conventionally used in the production of pressure-sensitive recording copy sheets and self-coloring recording sheets, are used. Furthermore, a dispersant, a surfactant, and an antifoaming agent may be added.

The self-coloring copying sheet of the present invention provides significantly superior color development compared to conventional self-coloring copying sheets, and also significantly improves self-coloring fog when attached to water and under high humidity.

In addition, in the present invention, as a method for providing a capsule layer, a color developer 1-, a mixed layer of microcapsules and a color developer on a support, an air knife coating method (fc, for example, U.S. Pat. No. 3.IR, Zaj No. 7, No. 3, Hiroshi 72,671/
-, etc.), blade coating method (for example, Tokuko Akihirota No. 31330, etc.), curtain coating method (for example, Tokuko Shoj3-2101, etc.), but it is possible to perform simultaneous multilayer coating and high-speed coating. The curtain coating method is preferable in certain respects because a coating film with a smooth surface can be obtained.

The self-coloring recording sheet of the present invention will be specifically explained below with reference to Examples, but it is not limited to this one example.

Example (1) Preparation of color developer coating liquid (sample layer/) 30 parts of tertiary α-methylbenzyl salicylic acid (mlO parts) was added to 20 parts of 1-isopropyl and cophenylethane, and the mixture was heated and dissolved at 20°C. Add this to 2% hollyhinyl alcohol (
PVA-2oz (manufactured by Kuraray) was added to 10 parts of an aqueous solution, and further 1 part of a 10% sodium sulfosuccinate aqueous solution was added as a surfactant, and the emulsion was mixed with a homogenizer so that the average particle size of the emulsion was 3μ. Prepared.

Next, a dispersion of 10 parts of aluminum hydroxide, 20 parts of zinc oxide, 1 part of sodium hexametaphosphate, and 200 parts of water was prepared using a Keddy mill, and after the above emulsion was mixed, 10% P V A was added as a binder. −／／
0 (5 L'H) Add 10 parts of water FJ liquid and 10 parts (as solid content) of carboxy-modified SBR latex (SN-30 Hiro, manufactured by Sumitomo Naugatux) so that the solid content concentration is 20%. (hereinafter referred to as sample /16/) (2) Preparation of color developer coating liquid (sample Mako) 3. P, P, P resin, ( A developer coating liquid (hereinafter referred to as sample/I6) used in the present invention was obtained in the same manner as in Example 1 except that ξ-ra phenylphenol and formaldehyde resin (manufactured by Sumitomo Duress) were used.

(3) Preparation of comparative color developer coating liquid (sample, %j) 3
, j-di α-methylbenzyl salicylate zinc lQ part,
0 parts of aluminum hydroxide, 20 parts of zinc oxide, 1 part of sodium hexametaphosphate and 200 parts of water were uniformly dispersed using an attritor.

To the obtained dispersion, Ioo parts of an aqueous solution of /0% PVA-//o (manufactured by Kuraray) and 70 parts (as solid content) of carboxy-modified SBR latex (SN-3o≠ manufactured by Sumitomo Naugatux) were added to adjust the solid content concentration. A developer coating solution (hereinafter referred to as sample/163) to be used for comparison was obtained by adding water and adjusting the concentration to 2 parts %.

(4) Preparation of color former-containing capsule coating solution (sample I) Part of polyvinylbenzene sulfo/acid sodium salt (%VER8A, manufactured by National Starch Co., Ltd., average molecular weight jOθ, ooo) was added to approximately to 'C. The mixture was added to 5 parts of hot water with stirring and dissolved. After dissolving for about 30 minutes, it is cooled. The pH of the aqueous solution is 2 to 3, and 20
z Aqueous sodium hydroxide solution was added to set pE (≠, θ.Meanwhile, 27,700 parts of diisopropyl naphtha in which crystal violet lactone and 1.0% benzoyl leucomethylene blue were dissolved was added to a portion of the polyvinylbenzenesulfonic acid. Aqueous solution of sodium salt 10
The particles were emulsified and dispersed in 0 parts to obtain an emulsion having a particle size of +1μ in average diameter. Separately, 6 parts of melamine, 1 part of a 37% formaldehyde aqueous solution, and 30 parts of water were heated and stirred to tOoC, and after 30 minutes, a transparent mixed aqueous solution of melamine, formaldehyde, and melamine-formaldehyde initial condensate was obtained. The pH of this mixed aqueous solution was t-♂. Hereinafter, this mixed aqueous solution of melamine, formaldehyde, and melamine-formaldehyde initial condensate will be referred to as an initial condensate solution. The initial condensate solution obtained by the above method was added to and mixed with the above emulsion, the pH was adjusted to t, o with 3.6% by weight hydrochloric acid solution while stirring, and the liquid temperature was raised to +t'c.
Partial stirring was continued. This capsule liquid is cooled to room temperature and λ
The pH was adjusted with 0% by weight sodium hydroxide and the OVC was adjusted.

To this capsule dispersion, 200 parts of a 10-weight layer aqueous solution of ribinyl alcohol and 50 parts of starch particles were added, and water was added to adjust the solid content concentration to 20%. (hereinafter referred to as Sample I) was obtained.

(5) Preparation of capsule coating liquid containing color former (sample ■) Neutralize isopane-10 (molecules (i/7 to /70,000, /:1 molar ratio copolymer of imbutylene and maleic anhydride, manufactured by Kuraray) A 10% aqueous solution was prepared by heating and dissolving it with sodium hydroxide to give a 0° angle.
0% water m Liquid gum arabic 10% water gi: /
70 parts of urea and 1 part of resorcinol to 1100 parts of water F8?
1 part and SS part of water were added and dissolved with stirring. then t
The I) H of the system was adjusted to 3°j using H hydrochloric acid.

2゜j% crystal myiolet lactone and/or
7,700 parts of diisopropyl naphthalene in which 0% benzoyl leucomethylene blue was dissolved was added to the above aqueous solution with vigorous stirring to emulsify it to form a 0 part wu emulsion, and when the oil droplet size reached an average diameter of about 10,000 mm, stirring was stopped. I stopped it.

To this emulsion were added 6 parts of ammonium chloride 1OM% aqueous solution. While stirring, 27 parts of aqueous formaldehyde solution was added to adjust the temperature of the system to atoc. The temperature was then maintained for 2 hours with continued stirring, then 2 hours.
! Lower it to 0c. Adjust the pH of the system using an aqueous sodium hydroxide solution. 0 to obtain a capsule dispersion containing color former oil.

To this capsule dispersion, 200 parts of a 10% by weight polyvinyl alcohol aqueous solution and 50 parts of starch particles were added, and water was added to adjust the solid content. adjusted to %. A capsule coating liquid containing a coloring agent (hereinafter referred to as sample ①) used in the present invention was obtained.

(6) Preparation of Comparative Color Former-Containing Capsule Coating Solution (Sample ■) Acid-treated gelatin with 5 tar and o. and gum arabic, 20 parts. . C's water/co. Sodium alkylbenzene sulfonate was dissolved in 0.0 parts as an emulsifier.
Add ≠ part to this and add 2. ! Add 2□0 parts of diimpropylnaphthalene in which crystal bi-olet lactone and/or 0% benzoyl leucomethylene blue have been dissolved while stirring vigorously to emulsify. 200 parts of water from C was added to suppress the progress of emulsification.

While continuing to stir, add 3o0c of water paste. Add part, 2
The pH of the system was adjusted to ≠, ≠ by adding 0% hydrochloric acid. The liquid was further cooled to g0c while stirring, and then 5 parts of 2θ glutaraltehyde was added.

Subsequently, 10% carboquine methylcellulose aqueous solution 60
Then add 2 parts % sodium hydroxide solution dropwise to pH &♂. After adjustment in the evening, the liquid temperature was heated to 3θoc to obtain microcapsules having hardened walls. 2 oti of 10% polyvinyl alcohol aqueous solution for Konocapsule fraction liquid,
B3 and starch particles! θ part was added, and the solid content concentration was 2.
Water was added to adjust the amount to 0% to obtain a color former-containing capsule coating liquid to be used for comparison. (hereinafter referred to as sample ■) (
7) Coating In the Examples and Comparative Examples below, the capsule liquid and developer liquid were applied in combination as shown in Table 1, and the capsule liquid and developer ti were simultaneously layered on the paper support using a curtain coating method. A curtain or capsule solution and a color developer solution were mixed to form a single layer curtain film and applied.

The coating amount is tog7rt of capsule liquid in case of multilayer coating.
1. The color developer liquid was set to a, o97m, and the capsule layer was the lower layer. Also, when mixing the capsule liquid and developer liquid and applying it in a single layer, the capsule liquid and developer liquid should be mixed together.
Mix at a ratio of :l and adjust to 1.0g/m2
Coating was carried out at a coating speed of H1/min to obtain a self-coloring pressure-sensitive recording sheet.

(8) Performance comparison The color development and fog (humidity fog) of each self-coloring pressure-sensitive recording sheet were compared with respect to the following items, and the results are shown in Table 1.

B) Color development (color development density and color development speed) Self-color development type pressure-sensitive recording sheet has low pressure range color development! Oky / cm 2 and high pressure range color development 300 y / CrIL2 (7) Develop color under static pressure and measure the color density after 70 minutes using a Hitachi spectrophotometer, model 307 (A
10 mμ).

(1) Humidity fog After leaving the self-coloring pressure-sensitive recording sheet under high temperature and high humidity at /j'O0C/0% relative humidity for 2≠ hours, the fog density was measured using a Hitachi spectrophotometer model 307 (610 mμ). did.

...) Evaluation The concentrations measured in A) and A) above were evaluated from a practical standpoint and ranked as A), B), and C) below.

A) Good performance B) Slightly problematic in practice C) Impractical

Claims (1)

[Claims] A layer containing microcapsules containing a color former and a layer containing a color developer that develops a color when in contact with the color former are coated on the same surface of the support, or microcapsules containing a color former and In a method for producing a self-coloring pressure-sensitive recording sheet coated with a layer containing a color developer that develops a color when in contact with the color former, the coating liquid containing the color developer is /j00c
A melamine-formaldehyde resin or a urea-formaldehyde resin is used as a wall material of a sulcafu cell containing an aqueous emulsion of an organic color developer dissolved in an organic solvent having a boiling point of from 33o'C to 33o'C. A method for producing a self-coloring pressure-sensitive recording sheet, characterized in that: