JP2011194806A - Color developing sheet for pressure-sensitive copying - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color developing sheet for pressure-sensitive copying which shows an improved balance among color developing capability, conservation (humidity resistance: deterioration of sensitivity due to storage under high-temperature and high-humidity environment).SOLUTION: The color developing sheet for pressure-sensitive copying includes a developer layer formed on the support. The developer layer contains an aldehydic starch, to obtain the color developing sheet having an improved balance among color developing capability, conservation (humidity resistance: deterioration of sensitivity due to storage under high-temperature and high-humidity environment) and printing strength.

Description

The present invention relates to a color developing sheet for pressure-sensitive copying, and more particularly to a color developing sheet for pressure-sensitive copying having an improved balance of color development ability, storage stability (moisture resistance) and printing strength.

The pressure-sensitive copying sheet is a “upper sheet” provided with a layer containing a microcapsule containing an electron donating dye (hereinafter referred to as “dye”) on one side of a support, and develops color when contacted with the dye. “Lower sheet” provided with a layer containing an electron-accepting compound (hereinafter referred to as “developer”), a layer containing a microcapsule containing a dye on one side of the support, and a developer on the other side There are suitable combinations of “medium sheets” provided with a layer containing them, and “self-contained paper” in which a microcapsule containing a dye and a developer are laminated or mixed on the same surface of a support.

Pressure-sensitive copying sheets are applied to various forms because they have the function of being able to copy many sheets, and are usually used for form printing by offset printing, ink-jet recording printing methods, etc. When printing is performed on the provided developer sheet, a part of the coating layer is deposited on a roll, a blanket, or a plate, and problems such as color loss and printing stains may occur.

Therefore, for the purpose of imparting printing strength, it is conceivable to increase the binder ratio of the coating layer and use a binder with strong binding strength, but the penetration of the dye oil into the developer layer is inhibited,
Detrimental effects such as a reduction in coloring ability occur. Patent Documents 1 and 2 disclose that an acrylamide polymer is included as an adhesive, but the coating amount must be increased in order to obtain a sufficient color development ability. Patent Document 3 discloses that a binder of a copolymer mainly composed of acrylamide having a molecular weight of 500,000 to 1,000,000 is included.

JP-A 63-170079 Japanese Patent Laid-Open No. 01-234288 Japanese Patent Laid-Open No. 06-227118

However, the conventional technology impedes the penetration of dye-containing oil into the developer layer, resulting in a decrease in color development sensitivity (color development speed and concentration) and storage stability (humidity resistance: stored in high temperature and high humidity environments). This causes a problem of lowering the sensitivity after the reduction.

Accordingly, the present invention provides a color-developing sheet for pressure-sensitive copying, which has an improved balance of coloring ability, storage stability (humidity resistance: reduced sensitivity after storage in a high temperature / high humidity environment) and printing strength. With the goal.

As a result of intensive studies, the inventors of the present invention have developed a pressure-sensitive copying developer sheet provided with a developer layer on a support, and the developer layer contains aldehyde-modified starch. (Moisture resistance: reduced sensitivity after storage in a high-temperature and high-humidity environment), the inventors found that a pressure-sensitive copying color-developing sheet having a good balance of printing strength can be obtained, leading to the present invention.

According to the present invention, it is possible to obtain a color developing sheet for pressure-sensitive copying having a good balance of color development ability, storage stability (humidity resistance: sensitivity reduction after storage in a high temperature / high humidity environment), and printing strength. .

Embodiments of the present invention will be described below.
In general, the occurrence of missing coating layer during printing is considered to be caused mainly by the weakness of the coating layer, but if the strength of the coating layer is too strong, an oil developer containing a dye is used. The penetration into the layer is hindered and the color development sensitivity is lowered.

On the other hand, the present invention has found that the balance of color development ability, storage stability (moisture resistance), and printing strength is improved by containing an aldehyde starch in a specific proportion in the developer layer. Is.

In the present invention, aldehyde-modified starch is starch obtained by treating untreated starch with dialdehyde or polyaldehyde.

In the present invention, the blending amount of the aldehyde-modified starch contained in the developer layer is desirably 10 to 20 parts by weight with respect to 100 parts by weight of the total solid content of the developer layer. Further, the blending amount of the aldehyde starch is preferably 5 to 90 parts by weight with respect to 100 parts by weight of the total binder contained in the developer layer.

The reason why an excellent effect is obtained in the present invention is not clear, but is considered as follows. The dye contained in the “layer coated with microcapsules” is an electron-donating substance and a kind of base, and the developer contained in the “layer coated with developer” is an electron-accepting substance. It is a kind of acid, and the color development reaction of the pressure-sensitive copying sheet can be regarded as a kind of acid-base reaction. That is, it is presumed that the color development reaction between the dye and the developer on the pressure-sensitive copying sheet is strongly influenced by the acid or base of the pressure-sensitive copying sheet.
For this reason, starch having a functional group derived from a weak acid, such as oxidized starch having a carboxyl group and hydroxyetherified starch having a hydroxy ether group, which has been conventionally used in a color developing sheet of a pressure-sensitive copying sheet, is a kind of Since it is difficult to ionize in the presence of a developer that is an acidic substance, the developer layer of the developer sheet is biased toward basicity, and the basic dye is stabilized and preserved (
Moisture resistance) is thought to deteriorate.
On the other hand, the aldehyde-modified starch having an aldehyde group used in the present invention has higher acidity than oxidized starch and hydroxyetherified starch, and can be appropriately ionized even in the presence of a developer which is a kind of acidic substance. Therefore, the developer layer of the developer sheet is inclined to be acidic, and the basic dye is likely to react, and it is considered that good color development ability and storage stability (humidity resistance) can be obtained.

The pressure-sensitive copying color developer sheet of the present invention is produced according to a conventional method. For example, the developer layer coating solution prepared by dispersing the developer in the binder together with the pigment is applied on the support. Coating /
Obtained by drying.

Next, various materials used in the present invention are exemplified.
As the developer used in the present invention, any known developer in the field of conventional pressure-sensitive or heat-sensitive recording paper can be used, and is not particularly limited. For example, activated clay, attapulgite, colloidal silica , Inorganic acidic substances such as aluminum silicate, 4,4′-isopropylidenediphenol, 1,1-bis (4-hydroxyphenyl) cyclohexane, 2
, 2-bis (4-hydroxyphenyl) -4-methylpentane, 4,4′-dihydroxydiphenyl sulfide, hydroquinone monobenzyl ether, benzyl 4-hydroxybenzoate, 4,4′-dihydroxydiphenyl sulfone, 2,4 ′ -Dihydroxydiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, 4-hydroxy-4'-n-propoxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4'- Methyldiphenylsulfone, 4-hydroxyphenyl-4′-benzyloxyphenylsulfone, 3,4-dihydroxyphenyl-4′-methylphenylsulfone, aminobenzenesulfonamide derivatives described in JP-A-8-59603, bis (4- Hydroxyph Nylthioethoxy) methane, 1,5-di (4-hydroxyphenylthio) -3-oxapentane, butyl bis (p-hydroxyphenyl) acetate, methyl bis (p-hydroxyphenyl) acetate, 1,1-bis ( 4-hydroxyphenyl) -1-phenylethane, 1,4-bis [α-methyl-α- (4′-hydroxyphenyl) ethyl] benzene, 1,3-bis [α-methyl-α- (4′- Hydroxyphenyl)
Ethyl] benzene, di (4-hydroxy-3-methylphenyl) sulfide, 2,2′-
Phenolic compounds such as thiobis (3-tert-octylphenol), 2,2′-thiobis (4-tert-octylphenol), diphenylsulfone bridged compounds described in International Publication WO97 / 16420, International Publication WO02 / 081229 or JP2002-2002
No. 301873, a phenolic compound described in International Publication WO 02/098774 or WO 03/029017, and International Publication WO 0
0/14058 or JP-A 2000-143611, urea urethane compounds, thiourea compounds such as N, N′-di-m-chlorophenylthiourea, p-chlorobenzoic acid, stearyl gallate, bis [4- ( n-octyloxycarbonylamino) zinc salicylate] dihydrate, 4- [2- (p-methoxyphenoxy) ethyloxy] salicylic acid,
4- [3- (p-Tolylsulfonyl) propyloxy] salicylic acid, 5- [p- (2-p
-Methoxyphenoxyethoxy) cumyl] aromatic carboxylic acids of salicylic acid and salts of these aromatic carboxylic acids with polyvalent metal salts such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin, nickel, and thiocyan Examples thereof include an antipyrine complex of zinc acid, and a complex zinc salt of terephthalaldehyde acid and other aromatic carboxylic acid. These developers can be used alone or in combination of two or more. In addition, JP-A-10-
Metal chelate coloring components such as higher fatty acid metal double salts and polyvalent hydroxy aromatic compounds described in Japanese Patent No. 258577 can also be contained.

In the present invention, the developer layer may contain a sensitizer. Examples of the sensitizer include fatty acid amides such as stearic acid amide and palmitic acid amide, ethylene bisamide, montanic acid wax, polyethylene wax, and 1,2. -Di- (3-methylphenoxy) ethane, p-
Benzylbiphenyl, β-benzyloxynaphthalene, 4-biphenyl-p-tolyl ether, m-terphenyl, 1,2-diphenoxyethane, dibenzyl oxalate, di (p-chlorobenzyl) oxalate, di (p -Methylbenzyl), dibenzyl terephthalate, benzyl p-benzyloxybenzoate, di-p-tolyl carbonate, phenyl-α
-Naphtyl carbonate, 1,4-diethoxynaphthalene, 1-hydroxy-2-naphthoic acid phenyl ester, o-xylene-bis- (phenyl ether), 4- (m-methylphenoxymethyl) biphenyl, 4,4'- Ethylenedioxy-bis-benzoic acid dibenzyl ester, dibenzoyloxymethane, 1,2-di (3-methylphenoxy) ethylene, bis [2- (4-methoxy-phenoxy) ethyl] ether, p-nitrobenzoic acid Examples thereof include methyl and phenyl p-toluenesulfonate, but are not particularly limited thereto. These sensitizers may be used alone or in combination of two or more.

In the present invention, various binders can be used in combination with aldehyde-modified starch as long as the desired effect is not inhibited. As binders that can be used in combination, fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, acetoacetylated polyvinyl alcohol ,
Carboxyl-modified polyvinyl alcohol, amide-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, butyral-modified polyvinyl alcohol, olefin-modified polyvinyl alcohol, nitrile-modified polyvinyl alcohol, pyrrolidone-modified polyvinyl alcohol, silicone-modified polyvinyl alcohol, other modified polyvinyl alcohols,
Hydroxyethylcellulose, methylcellulose, ethylcellulose, carboxymethylcellulose, styrene-maleic anhydride copolymer, styrene-butadiene copolymer and cellulose derivatives such as ethylcellulose, acetylcellulose, casein, arabic gum, oxidized starch, etherified starch, dialdehyde starch Esterified starch, polyvinyl chloride, polyvinyl acetate, polyacrylamide, polyacrylic ester, polyvinyl butyral, polystyrose and copolymers thereof, polyamide resin, silicone resin, petroleum resin, terpene resin, ketone resin, couma resin Etc. can be illustrated. These polymer substances are used by dissolving them in solvents such as water, alcohol, ketones, esters, hydrocarbons, etc., and are used in the state of being emulsified or pasted in water or other media to achieve the required quality. It can also be used in combination.

In the present invention, a pigment can be contained in the developer layer as necessary. Examples of pigments include kaolin, (baked) kaolin, calcium carbonate, aluminum oxide, titanium oxide,
Examples thereof include, but are not limited to, magnesium carbonate, aluminum silicate, magnesium silicate, calcium silicate, aluminum hydroxide, silica and the like.

In the present invention, a crosslinking agent can be added to the developer layer as necessary. Cross-linking agents include glyoxal, methylol melamine, melamine formaldehyde resin, melamine urea resin, polyamine epichlorohydrin resin, polyamide epichlorohydrin resin, potassium persulfate, ammonium persulfate, sodium persulfate, ferric chloride, magnesium chloride And borax, boric acid, alum, ammonium chloride, and the like.

In the present invention, a lubricant can be added to the developer layer as necessary. Examples of the lubricant include fatty acid metal salts such as zinc stearate and calcium stearate, waxes, and silicone resins.

Further, in the present invention, 4,4′-butylidene (6-tert-butyl-3) is used as an image stabilizer exhibiting an oil resistance effect of a recorded image within a range that does not impair a desired effect on the above problem.
-Methylphenol), 2,2'-di-t-butyl-5,5'-dimethyl-4,4'-sulfonyldiphenol, 1,1,3-tris (2-methyl-4-hydroxy-5- Cyclohexylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-t-)
Butylphenyl) butane, 4-benzyloxy-4 ′-(2,3-epoxy-2-methylpropoxy) diphenylsulfone, and the like can also be added.

In addition, benzophenone and triazole ultraviolet absorbers, dispersants, antifoaming agents, antioxidants, fluorescent dyes, and the like can be used.

In the present invention, the developer and, if necessary, the material to be added are atomized to a particle size of several microns or less by a pulverizer such as a ball mill, an attritor, a sand glider, or an appropriate emulsifier, and are used for the binder and purpose. Accordingly, various additive materials are added to obtain a coating solution. As a solvent used for the coating liquid, water, alcohol, or the like can be used.

In the present invention, the method for forming the developer layer is not particularly limited, and for example, an appropriate coating apparatus such as an air knife coater, a roll coater, a blade coater, a rod coater, or a curtain coater can be used. Further, the developer layer is high-quality paper, recycled paper, it is common to be formed to about ^2g / m ² ~7g / m 2 on a synthetic paper consisting of a support or the like.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples. Unless otherwise specified, parts and% represent parts by weight and% by weight.

[Example 1]
22 parts of a 45% aqueous dispersion of 3,5-di (α-methylbenzyl) salicylic acid zinc salt with an average particle diameter of 2 μm using a sand grinder, 90 parts of calcium carbonate, 10 parts of kaolin, 10% polyvinyl alcohol (trade name) : Poval 117, manufactured by Kuraray Co., Ltd.) 20 parts of an aqueous solution and 50 parts of an aldehyde-modified starch 20% solution were blended, and the concentration was adjusted with water to obtain a coating solution having a final concentration of 25%. This coating solution was applied to a high-quality paper of 40 g / m 2 with a brate coater to obtain a pressure-sensitive copying color developing sheet having a solid coating amount of 5 g / m 2.

[Comparative Example 1]
A pressure-sensitive copying color developing sheet was obtained in the same manner as in Example 1 except that 50 parts of 20% aqueous solution of aldehyde-modified starch was not distributed and 50 parts of 20% aqueous solution of oxidized starch was added.

[Comparative Example 2]
A pressure-sensitive copying color developing sheet was obtained in the same manner as in Example 1 except that 50 parts of 20% aqueous solution of aldehyde-modified starch was not distributed and 50 parts of 20% aqueous solution of hydroxyethyl etherified starch was added.

[Comparative Example 3]
A pressure-sensitive copying developer sheet was obtained in the same manner as in Example 1 except that 50 parts of an aldehyde-modified starch 20% aqueous solution was dispensed and 10 parts of SBR latex was added as a solid content.

[Comparative Example 4]
50 parts of 20% aqueous solution of aldehyde-modified starch was dispensed with and completely saponified PVA (manufactured by Kuraray Co., PVA)
A pressure-sensitive copying developer sheet was obtained in the same manner as in Example 1 except that 50 parts of 105 (polymerization degree 500, 20% solution) were blended.

The developer sheets prepared in Example 1 and Comparative Examples 1 to 4 were evaluated as follows. The evaluation results are shown in Table 1.

(1) Color development test The commercially available upper paper NW40T (Nippon Paper) and the coated surface of the developer sheet are overlapped, sandwiched between the base papers, and calendered at 20 ° C, 65% RH, 100kg / cm2. It was. The color density after 1 hour of calendering was measured with a Macbeth densitometer (RD914, Latin # 25 filter, Macbeth).

(2) Humidity resistance test The developed color sheet was stored in an environmental tester (60 ° C x 90% RH x 16h). Then, “(1
The color density was measured in the same manner as in “A) Color development test”. In addition, the concentration difference between the sample treated with 60 ° C. × 90% RH × 16 h and the sample not treated is calculated, and the smaller the difference value, the better.

(3) Printing strength test The color developing sheet 1500 m was printed with an offset rotary printing press (manufactured by Apollo), and the state of powder falling off from the blanket after printing was visually evaluated and represented by the following criteria.
○ No powder fall △ Some powder fall, but no problem in practical use × There is powder fall

As shown in Table 1, the color developing sheet for pressure-sensitive copying of the present invention has coloring ability and storage stability (moisture resistance).
And the printing intensity balance has been improved.

Claims (1)

A pressure sensitive color developing sheet having a color developer layer provided on a support, wherein the color developer layer contains an aldehyde starch.