JPS6138038B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD This invention relates to pressure-sensitive recording paper, and more particularly to polymeric materials used as color developers therein. Pressure-sensitive recording paper utilizes the reaction between a leuco dye (hereinafter referred to as a coloring agent), which is an electron donating substance, and an electron accepting substance (hereinafter referred to as a color developer) to form a colored substance. That is, a coloring agent is dissolved in a solvent such as a non-volatile hydrocarbon or an organic acid ester, and a microcapsule of this solution is applied to the back of the support, and a top sheet of paper and a color developer are applied to the surface of the support. When the coated bottom paper is used as a unit and pressure is applied with the coated surfaces facing each other, the capsules coated on the back side of the top paper break and the solvent in which the coloring agent is dissolved oozes out, which is then applied to the bottom paper. This is a recording paper that develops color when it comes into contact with a color developer. As such color developers for pressure-sensitive recording paper, acid clays, phenolic resins, organic acid derivatives, and the like are conventionally known. In particular, phenolic resin-based color developers are preferred because they produce stable color hues. However, phenolic resin color developers have poor solubility in dye solvents and have insufficient color developing ability.
In addition, the colored image may fade if left indoors for a long time, exposed to sunlight, or exposed to ester solvents (such as plasticizers contained in large amounts in PVC etc.).
Paper coated with phenolic resin also has properties such as being susceptible to yellowing. Recently, aromatic carboxylic acid-aldehyde polymers having hydroxyl groups with improved properties have been published as color developers (Japanese Patent Publication No. 48-8215
No., Special Publication No. 48-8216, Special Publication No. 13452, Special Publication No. 49-13455). However, these polymers do not have improved solubility in solvents, and therefore react slowly with color formers, resulting in decreased color development properties and color development rates. In addition, when producing a p-phenylphenol-aldehyde polycondensate to improve the solubility of a color developer, a trowel in which xylene or the like is added and polymerized is disclosed in JP-A-51-56315, Disclosed in No. 19244. Although the color developer obtained by this method has excellent solubility, it has the disadvantage that yellowing occurs and the color image is easily faded by ester solvents. Conventionally, it was known that xylene resin becomes an ester compound when reacted with an organic carboxylic acid in the presence of an acidic catalyst, but the present inventors discovered that an aromatic carboxylic acid containing a hydroxyl group can be reacted with xylene under certain conditions. It was discovered that when reacted with a resin, a co-condensate of an aromatic carboxylic acid having a hydroxyl group and a xylene resin was obtained, with almost no corresponding ester compound produced. It has also been found that the solubility in solvents can be further increased by adding phenols or phenolic resins as a third component and carrying out the same reaction. Aromatic carboxylic acids having a hydroxyl group and polymers thereof used in the present invention include salicylic acid, p-hydroxybenzoic acid, 2,6-dihydroxybenzoic acid, and aldehyde polymers thereof. The amount added is 0.5 to 7 parts, preferably 1 to 5 parts, per part of xylene resin (parts are parts by weight, the same applies hereinafter). Phenols or phenol-aldehyde polymers added as the third component include alkylphenols such as paracresol, paraoctylphenol, and paranonylphenol, aralkylphenols such as paraphenylphenol and paracumylphenol, parachlorophenol, and parabromophenol. These are halogenated phenols such as phenols and their aldehyde polymers. The amount added to 1 part of xylene resin is 0.5 to 7 parts, preferably 1 to 5 parts. Hydrochloric acid, sulfuric acid, para-toluenesulfonic acid, metaxylenesulfonic acid, etc. are used as catalysts for condensation by adding these.
The reaction conditions are 100 to 110°C for 1 to 5 hours. The method for producing pressure-sensitive recording paper using the color developer of the present invention includes (i) dissolving the color developer of the present invention in an organic solvent, and optionally adding a polyvalent metal compound, an inorganic pigment, a binder, etc. Method (ii) After dispersing the color developer of the present invention in water, adding a polyvalent metal compound, an inorganic pigment, or a binder as necessary and impregnating or coating the support. Coating method (iii) Method of mixing the color developer, polyvalent metal compound, inorganic pigment, etc. of the present invention into the support during production of the support (iv) Each of (i), (ii), and (iii) A method in which a color former or a microcapsule containing a color former is further added to the method. Furthermore, the color developer of the present invention has excellent compatibility with dye solvents, so it can be easily formed into an ink.
That is, by mixing the color developer of the present invention into a vehicle to form an ink, and then printing it onto a support such as paper, a bottom paper in which only the printed portion develops color can be obtained. As mentioned above, various methods can be mentioned, but the method is not limited to these methods. Examples of the support used in the present invention include paper, various nonwoven fabrics, plastic films, synthetic papers, metal foils, and composite sheets made by combining these materials. Moreover, the polyvalent metal compound used in the present invention is
Cu, Ca, Ba, Mg, Zn, Al, K, Ti, Sn, Cr,
These include oxides, inorganic acid salts, hydroxides, organometallic compounds, etc. of Mn, Co, Fe, Ni, etc. Binders include latex, water-soluble and water-dispersible binders, and inorganic pigments include activated clay, acid clay, cartilage, talc, zeolite,
Asbestos, diatomaceous earth, etc. are used. The performance of the color developer of the present invention was confirmed using microcapsule sheets containing the following color former. Microcapsules containing color formers are disclosed in British Patent No. 989264, British Patent No. 1237489, and Japanese Patent Publication No. 36-9168.
It was manufactured by a microencapsulation method as shown in Japanese Patent Application Laid-Open No. 51-9079. That is,
10% aqueous solution of ethylene-maleic anhydride copolymer
100 parts (% is weight %), 10 parts of urea, 1 part of resorcinol, and 200 parts of water were mixed to form a solution, and the pH was adjusted to 3.5 using an aqueous sodium hydroxide solution. Crystal violet lactone (CVL)
) 7.2 parts of Nippon Oil Co., Ltd.'s Hysol SAS-
296 was dissolved in 172.8 parts to prepare a dye solution. This dye solution is emulsified and dispersed in the above mixed aqueous solution,
An oil-in-water emulsion with oil droplets of 4 to 8 microns was created. Then 37% formaldehyde aqueous solution
25 parts were added and the temperature of the system was maintained at 55°C while stirring. After 2 hours, a wall film mainly of urea-formaldehyde polymer was formed around the oil droplets. The mixture was further stirred for 2 hours to complete the encapsulation. To 100 parts of the obtained microcapsules, 25 parts of wheat starch and 100 parts of an oxidized starch aqueous solution were added, and water was further added to make the total amount 540 parts. This coating liquid was applied onto a base paper having a basis weight of 40 g/m ² and dried to a coating amount of 5 g/m ² as a total solid content. As described above, a top paper (microcapsule sheet) containing CVL as a coloring agent was obtained. Next, the present invention will be specifically explained with reference to Examples. Example 1 63 g of salicylic acid, 52 g of xylene resin [Nicanol L (manufactured by Mitsubishi Gas Chemical Co., Ltd.)], 150 ml of toluene,
And 1 g of para-toluenesulfonic acid as a catalyst was placed in a glass reactor, and condensation was carried out at a reaction temperature of 100 to 110°C for 1 hour. Next, hot water was added to the condensate obtained by removing toluene, and the mixture was washed with stirring, and the upper layer of water was removed. Thereafter, the temperature was raised to 140° C. under reduced pressure of 50 mmHg, and water and volatile substances were distilled off to obtain 105 g of pale yellow resin. Example 2 Salicylic acid 81g, paraformaldehyde (80g
%), 200 ml of toluene, and 0.8 g of para-toluenesulfonic acid as a catalyst were placed in a glass reactor and condensed at a reaction temperature of 95 to 100°C for 2 hours to obtain a salicylic acid-aldehyde polymer, followed by 20 g of xylene resin and a catalyst. 0.5 g of para-toluenesulfonic acid was added thereto, and co-condensation was carried out at a reaction temperature of 100 to 110°C for 1 hour. After the reaction was completed, it was treated in the same manner as in Example 1 to obtain 97 g of a pale yellow resin. Example 3 Salicylic acid 42g, paraphenylphenol 34g
g, 52 g of xylene resin, 200 ml of toluene, and 1 g of para-toluenesulfonic acid as a catalyst were placed in a glass reactor and condensed for 1 hour at a reaction temperature of 100-110°C. After the reaction was completed, the mixture was treated in the same manner as in Example 1 to obtain 115 g of a pale reddish brown resin. Example 4 100g of paraphenylphenol, 10g (80%) of paraformaldehyde, 200ml of toluene, and 1g of paratoluenesulfonic acid as a catalyst were placed in a glass reactor and condensed at a reaction temperature of 95 to 100°C for 1.5 hours to produce paraphenylphenol. After obtaining the aldehyde polymer, add 20g of xylene resin and salicylic acid.
30 g and 1 g of para-toluenesulfonic acid as a catalyst were added, and co-condensation was carried out at a reaction temperature of 100 to 110° C. for 1 hour. After the reaction was completed, it was treated in the same manner as in Example 1 to obtain 145 g of a light brown resin. Comparative example 1 Salicylic acid 81g, paraformaldehyde 10g
(80%), 150 ml of toluene, and 2 g of para-toluenesulfonic acid as a catalyst were placed in a glass reactor and condensed at a reaction temperature of 95-100°C for 2 hours. After the reaction, the mixture was treated in the same manner as in Example 1 to obtain 85 g of a white resin. Comparative Examples 2 and 3 The samples of Comparative Examples 2 and 3 are commercially available products 3 and 5, respectively.
- ditertiary butylsalicylic acid, and paraphenylphenol-aldehyde polymer were used. Comparative test results 15 g each of the resins obtained in Examples 1 to 4 and Comparative Example 1, and the commercially available products of Comparative Examples 2 and 3 were dispersed in 45 parts of an aqueous polyvinyl alcohol solution, and water was added with stirring.
A dispersion of 120 parts of zinc oxide was added to 240 parts.
Next, 12 parts of styrene-butadiene copolymer was added to form a coating solution, and the coating solution was applied onto base paper with a basis weight of 40 g/m ² so that the total solid content was 5.4 g/m ² .
It was dried to obtain a paper sheet. (i) Color development and ester-based solvent fading resistance The bottom paper obtained as above was overlapped with the top paper (microcapsule sheet), and after printing with a typewriter IBM82, the color development density of the bottom paper was I looked into it. In addition, the printed bottom paper was placed in a bag made of vinyl chloride (thickness: 0.2 m/m) and heated for two days and nights, and the concentration of the color faded by the plasticizer, an ester solvent contained in the vinyl chloride, was examined. . The results are shown in Table-1. Note that the blue color density was measured using a Sakura Densitometer PDA45.

[Table] (ii) Solubility Using Hysol N296 manufactured by Nippon Oil Co., Ltd. as a solvent, each sample was dissolved by heating and left at room temperature for 25 days. %) was calculated. The results are shown in Table-2.

[Table] (iii) Yellowing of lower paper Before printing the lower paper of Examples 1 to 4 and Comparative Examples 1 to 3, a xenon fade meter was used to
It was irradiated with xenon light for 3 hours under the conditions of W/m ² , 40° C., and 60%, and yellowing was examined. We also examined yellowing after leaving similar paper on a wall for 20 days.
The results are shown in Table-3.

[Table] Yes, × indicates yellowing.
As shown in Tables 1, 2, and 3, the color developer of the present invention has significantly improved solubility in solvents, is less likely to cause yellowing, and the color image obtained by printing is It can be seen that it is highly durable and hardly fades.

Claims (1)

[Claims] 1. Aromatic carboxylic acid having a hydroxyl group,
Alternatively, for pressure-sensitive recording paper, 0.5 to 7 parts (by weight) of an aromatic carboxylic acid aldehyde polymer having a hydroxyl group is added to 1 part of xylene resin and co-condensed with the xylene resin in the presence of an acidic catalyst. Color developer. 2 aromatic carboxylic acid having a hydroxyl group,
Alternatively, add 0.5 to 7 parts (by weight) of an aldehyde polymer of an aromatic carboxylic acid having a hydroxyl group to 1 part of xylene resin, and then add phenols or a phenol-aldehyde polymer as a third component to 1 part of xylene resin. 0.5-7 for
(parts by weight) of a color developer for pressure-sensitive recording paper, which is co-condensed with a xylene resin in the presence of an acidic catalyst.