JPH04314582A - Pressure-sensitive recording material - Google Patents

Abstract

PURPOSE:To obtain a pressure-sensitive recording material superior in mechanical strength and water resistance and uniform in coloring density in a pressure- sensitive recording material obtaining a coloring image by the reaction of a colorless dye with a color developer. CONSTITUTION:In a pressure-sensitive recording material obtaining a coloring image by the reaction of a colorless dye with a color developer, a sheet material obtained by injection molding a synthetic fiber having a Bekk smoothness of 60 sec or more is used as a substrate. The use of a sheet material obtained by injection molding a high-smoothness synthetic fiber as a substrate ensures a pressure-sensitive recording material superior in mechanical strength and water resistance and uniform in coloring density.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive recording material that produces a colored image through the reaction of a colorless dye and a color developer. More specifically, the present invention relates to a pressure-sensitive recording material that has excellent mechanical strength and water resistance and can provide uniform color density.

0002

[Prior Art] Pressure-sensitive recording materials usually include an upper sheet in which an electron-donating colorless dye is dissolved in a non-volatile oil and contained in fine capsules, and an electron-accepting color developer is coated thereon. It consists of a lower sheet, i.e., a color developing sheet. When the coated surfaces of both sheets are stacked facing each other and pressure is applied by writing or with an impact printer, the capsule in the pressurized area is destroyed and the colorless dye solution is transferred to the color developing sheet. It transfers to the surface, develops color, and produces an image.

[0003] Furthermore, if an intermediate sheet coated with a color developer on the surface and a capsule containing a colorless dye on the back side is used by sandwiching it between an upper sheet and a lower sheet, a plurality of records can be obtained.

Furthermore, self-contained sheets are also used in which a colorless dye and a color developer are placed on the same side of a support sheet.

Conventionally, inorganic minerals such as activated clay, acid clay, attapulgite, and zeolite have been used as color developers for pressure-sensitive recording, but these have insufficient color developing ability and easily deteriorate colored images. From, various phenol resins,
Aromatic carboxylic acid heavy metal salts, and more recently, color developers such as resinous salicylic acid derivative zinc salt emulsions, which have high color developing ability and whose colored images are not easily deteriorated, have been used.

On the other hand, colorless dyes for pressure-sensitive recording include crystal violet lactone, benzoylleucomethylene blue, malachite green lactone, rhodamine anilinolactam, and 3-diethylamino-6-methyl-7.
-Colorless dyes such as anilinofluorane are well known.

[0007] Pressure-sensitive recording materials are usually combined in multiple sheets and used mainly for forms, but in recent years pressure-sensitive recording materials have been used for luggage labels for the luggage transportation industry called courier services. Its uses have also become more diverse. Along with this, pressure-sensitive recording materials are also being required to have higher functionality than ever before in order to suit each application. For example, the above-mentioned parcel labels for courier services are currently widely used with paper as a support, which prevents the labels from being damaged by external forces or moisture from rain during transportation. In order to provide mechanical strength and water resistance, vinyl tape or film is pasted onto the label.

A common method for improving the mechanical strength and water resistance of the paper support is to coat or impregnate the sheet with a water-soluble resin or water-based emulsion. In order to obtain mechanical strength and water resistance, it is necessary to increase the amount of coating and the amount of impregnation, which increases cost.

Another method is to use a film with high mechanical strength and water resistance as a support, but this is not practical because it is difficult to improve the adhesion between the support and the coating layer and the cost is high. Not in a good way.

Furthermore, there is a method of providing mechanical strength and water resistance by using a support made of a laminate of film and paper; It has the disadvantage of not being strong enough.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide an inexpensive pressure-sensitive recording material that has excellent mechanical strength and water resistance, which have not been achieved with the prior art.

0012

[Means for Solving the Problems] The present inventors produced a pressure-sensitive recording material using a sheet-like support obtained by injection molding synthetic fibers, and found that a pressure-sensitive recording material using paper as a support In addition, mechanical strength and water resistance are dramatically improved compared to those that use film as a support, and because the sheet contains air, the mechanical strength per unit weight is higher than that of sheets that use film as a support. It became clear that the cost was low. In addition, as a result of examining the relationship between the surface smoothness of such a sheet-like support and the uniformity of color density, we found that the sheet with higher surface smoothness has a more uniform colorless dye-containing microcapsule coating layer and color developer coating layer. It became clear that uniform color density could be obtained when pressure printing was performed using a combination of upper and lower sheets. Therefore, it was found that by using a sheet with high surface smoothness obtained by injection molding synthetic fibers as a support, an inexpensive pressure-sensitive recording material with excellent mechanical strength and water resistance and uniform color density can be obtained. However, the present invention was completed.

Materials for the injection-molded sheet support used in the present invention include resins such as polyethylene, polypropylene, polyester, nylon, rayon, polyacrylate, polyurethane, and mixtures thereof. Further, a wettability improver, an antistatic agent, an antioxidant, a dyeing agent, etc. may be added to the sheet-like support as necessary.

In the present invention, the method of injection molding synthetic fibers to obtain a sheet-like support is to heat and melt resin in the form of pellets or chips, extrude it into a fiber form from a die head having pores at the tip, and then The melt-blown method involves blowing air to randomly orient the fibers, reorienting them on a forming belt, and then thermally fusing them with a heat roll to obtain a sheet. After melting the resin and extruding it from a die head, The spunbond method uses airflow to elongate the fibers to make the fiber diameter thinner, then heat-seals the fibers to obtain a sheet.The spunbond method involves adding a solvent to the resin and extruding it from a die head.
A flash spin method, which obtains a sheet in the same manner as the spunbond method, can be used.

In the present invention, the Bekk smoothness of the sheet-like support obtained by injection molding of synthetic fibers is set to 60 seconds or more, so that the colorless dye-containing microcapsule coating layer and the color developer coating layer are uniformly coated. This enables uniform color density to be obtained when pressure printing is performed using a combination of upper and lower sheets. However, if the Beck smoothness of the sheet-like support is lower than 60 seconds, it becomes impossible to uniformly apply the colorless dye-containing microcapsule coating layer and the color developer coating layer due to the unevenness of the sheet surface. , uneven color density occurs when pressure printing is performed using a combination of upper and lower sheets.

[0016] In the present invention, the coating liquid containing microcapsules is generally a liquid in which microcapsules are dissolved or dispersed in water together with a binder and a protective agent, and the concentration of the microcapsules, binder, and protective agent is 10 to 6.
0% by weight. The blending ratio of microcapsules, binder, and protective agent is generally 100 microcapsules.
The total ratio of the binder and the protective agent to parts by weight is 5 parts by weight or more, preferably 10 to 70 parts by weight, more preferably 30 to 60 parts by weight, and the ratio of the binder to the protective agent is 100 parts by weight of the binder. 5 parts of the protective agent
It is preferably 0 to 200 parts by weight.

[0017] In the present invention, microcapsules are
They are microcapsules that contain a basic colorless dissolved oily substance and are covered with a wall material made of a polymeric substance that is insoluble in both water and oily liquids. As the wall material, a material made of a combination of a polycation and a polyanion such as gelatin-gum arabic, or a combination of a condensed composition such as polyisocyanate-polyamine is used.

[0018] As a method for producing microcapsules in the present invention, a phase separation method from an aqueous solution (US Pat. No. 280
0457, 2800458, etc.), interfacial polymerization method (Japanese Patent Publication No. 38-19574, 42-446, etc.)
42-771, 42-2882, 42-28
No. 83, No. 42-8693, No. 42-9654, No. 42-11344, British Patent No. 950443,
1046409), method by polymerization of wall material in oil droplets (Japanese Patent Publications No. 36-9168, 49-45)
133, etc.), or a melting and dispersion cooling method (British Patent No. 952807, British Patent No. 965074, etc.).

[0019] In the present invention, colorless dyes have the property of developing color by donating electrons or accepting protons such as acids, and are not particularly limited. Specific compounds of these colorless dyes are shown below. For example, triarylmethane compounds include 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, that is, crystal violet lactone, 3,3-bis(p-dimethylaminophenyl)phthalide, 3- (p-dimethylaminophenyl)-3-(1,2-dimethylindol-3-yl)phthalide, 3-(p-dimethylaminophenyl)-3-(
2-methylindol-3-yl)phthalide, 3-(p
-dimethylaminophenyl)-3-(2-phenylindol-3-yl)phthalide, 3,3-bis(1,2-
dimethylindol-3-yl)-5 dimethylaminophthalide, 3,3-bis(1,2-dimethylindole-
3-yl)-6 dimethylaminophthalide, 3,3-bis(9-ethylcarbazol-3-yl)-5-dimethylaminophthalide, 3,3-bis-(2-phenylindol-3-yl) -5-dimethylaminophthalide, 3-
p-dimethylaminophenyl-3-(1-methylpyrrol-2-yl)-6-dimethyl-aminophthalide, etc.;

As a diphenylmethane compound, 4,4
'-bis-dimethylaminobenzhydrin benzyl ether, N-halophenyl-leucoolamine, N-2,
4,5-trichlorophenylleucoauramine etc.;

0
[021] As xanthene compounds, rhodamine B-anilidolactam, rhodamine Bp-nitroanilinolactam, rhodamine B-p-chloroanilinolactam, 7-
Dimethylamino-2-methoxyfluorane, 7-diethylamino-2-methoxyfluorane, 7-diethylamino-3-methoxyfluorane, 7-diethylamino-3
-Chlorofluorane, 7-diethylamino-3-chloro-2-methylfluorane, 7-diethylamino-2,2
-dimethylfluorane, 7-diethylamino-3-acetylmethylaminofluorane, 7-diethylamino-3
'-Methylaminofluorane, 3,7-diethylaminofluorane, 7-diethylamino-3-dibenzylaminofluorane, 7-diethylamino-3-methylbenzylamino-fluorane, 7-diethylamino-3-chloroethylmethylaminofluorane orane, 7-diethylamino-3-diethylaminofluorane, etc.;

As thiazine compounds, benzoyl leucomethylene blue, p-nitrobenzyl leucomethylene blue, etc.;

Examples of spiro compounds include 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3,3'-dichloro-spiro-dinaphthopyran,
3-benzylspiro-dinaphthopyran, 3-methyl-naphtho-(3-methoxy-benzo)-spiro-pyran, 3
-propyl-spiro-dibenzopyran, etc., or a mixture thereof.

These colorless dyes are encapsulated by being dissolved in a solvent, and natural or synthetic oils can be used alone or in combination as the solvent. Examples of solvents include cottonseed oil, kerosene, paraffins, naphthenic oils, alkylated biphenyls, alkylated Tafels, chlorinated paraffins, alkylated naphthalenes, and the like.

In the present invention, binders include, for example, latexes such as styrene-butadiene-rubber latex, styrene-butadiene-acrylonitrile latex, styrene-maleic anhydride copolymer latex, and proteins (eg, gelatin, albumin, casein, etc.). , water-soluble natural polymer compounds such as cellulose derivatives (e.g., carboxymethylcellulose, hydroxyethylcellulose, etc.), saccharose derivatives (e.g., agar, sodium alginate, starch, carboxymethylstarch, etc.), polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid. Examples include water-soluble synthetic polymer compounds such as polyacrylamide, organic solvent-soluble polymer compounds such as nitrocellulose, ethyl cellulose, polyester, polyvinyl acetate, polyvinylidene chloride, and vinyl chloride-vinylidene chloride copolymers. can. These polymeric substances used as binders usually have a molecular weight of about 1,000 to 1,000,000, but
Particularly preferred are those having a molecular weight range of 10,000 to 5,000,000.

In the present invention, protective agents include cellulose fine powder, starch particles, glass beads, and microspheres, as well as polymer particles such as polyolefin particles, nylon particles, vinyl chloride particles, methyl methacrylate polymer particles, and mineral particles. If the particle size is larger than microcapsules, such as titanium powder, white carbon, calcium carbonate, calcium tungstate, or zinc sulfide,
Although it can be used, relatively spherical particles and colorless particles are preferable.

Further, as a color developer in the present invention, clays such as acid clay, activated clay, attapulgite, zeolite, and bentonite, phenolic resin, and
Polyvalent metal salts of various aromatic carboxylic acids as described in No. 25174, 2, as described in JP-A-54-106316,
Zinc salts of 2'-bisphenolsulfone compounds and mixtures thereof can be used.

Examples of the combination of a metal salt and a ligand compound include the following combinations of compounds known in the field of pressure-sensitive copying paper.

Nickel stearate and N,N'-di-benzyl-di-thio-oxamide, nickel laurate and α-benzylglyoxime, tricaptylmethylammonium vanadate and dodecylamine 8-hydroxyquinolinesulfonate, molybdenum Benzyllauryldimethylammonium acid and lauryl protocatechuate, titanium stearate and lauryl gallate, iron naphthenate and benzyl gallate, polyferrophenylmethylsiloxane and methylenebis(8-oxyquinoline), copper palmitate and N,N'-bis -2-octanoylexyethyldiethyldithiooxamide, cobalt laurate and di-o
- Tolylguanidine, hinokitiol and polyvanadophenylmethylsiloxane, combinations of organoiron phosphate and lauryl gallate described in JP-A-58-38191, and mixtures thereof.

In order to obtain uniform color development and high printing density in the present invention, the coating amount of the colorless dye-containing microcapsule dispersion is preferably in the range of 0.5 to 15 g/m2 in terms of dry coating amount, and more preferably 2 to 15 g/m2. A range of ~6 g/m2 is preferred. The dry coating amount of the color developer is preferably in the range of 1 to 15 g/m2, more preferably in the range of 3 to 10 g/m2. If the amount of coating is too small, uniform color development cannot be obtained due to exposure of the base fibers, and if the amount of coating is too large, production costs will increase, making it impractical.

In the present invention, the coating method for coating the colorless dye-containing microcapsule dispersion and the color developer onto the support is not particularly limited, and may be an air knife coater, a rod coater, a curtain coater, or a die coater. Various coating devices such as , roll coater, blade coater, etc. can be used.

[0032]

EXAMPLES The present invention will be explained in more detail with reference to Examples, but the present invention is of course not limited to these. Note that all parts and percentages shown below are based on weight, and unless otherwise specified, the coating amounts are dry coating amounts.

Example 1 Method for manufacturing coating liquid <Capsule dispersion> Crystal violet lactone (
200 parts of high-boiling oil (KMC-113, manufactured by Kureha Chemical Co., Ltd.) in which 5 parts of CVL) were dissolved was added to 250 parts of a 5% styrene maleic anhydride copolymer aqueous solution (PH 5.0), and the average particle size was 6 μm. It was emulsified so that

Next, 20 parts of a 40% melamine-formalin initial condensate aqueous solution (Sumilets Resin, manufactured by Sumitomo Chemical Co., Ltd.) was added to the above emulsion, the temperature was raised to 75°C, and the mixture was reacted for 2 hours. pH 9.0 with sodium oxide aqueous solution
The mixture was cooled to room temperature to obtain a 40% microcapsule dispersion.

<Coating Liquid 1> A coating liquid (solid content concentration: 40%) having the following composition was obtained from the microcapsule dispersion thus obtained. 40% microcapsule dispersion 100 parts wheat starch (
Average particle size: 20 μm) 50 parts 48% carboxy-modified styrene-butadiene copolymer latex 20 parts Added water 79 parts

<Coating Solution 2> A developer layer coating solution (solid content concentration 40%) having the following formulation was also obtained. Commercially available heavy calcium carbonate 20 parts Commercially available secondary kaolin 30 parts Commercially available light calcium carbonate 50 parts Color developer 20 parts 10% Polyvinyl alcohol 10 parts 48% Carboxy-modified styrene-butadiene copolymer latex 10
Department

A polyethylene resin injection molded sheet having a basis weight of 56.0 g/m 2 was smoothed using a supercalender to obtain a support having a Bekk smoothness of 73 seconds. The above coating liquid 1 was coated onto this support so that the dry coating amount was 5 g/m<2 >and dried to obtain a colorless dye-containing top sheet. Also,
The dry coating amount of the coating liquid 2 on the support is 5 g/m2.
It was coated and dried to obtain a color developing sheet.

Example 2 An injection molded polypropylene resin sheet having a basis weight of 67.2 g/m 2 was smoothed using a thermal calendar to obtain a support having a Beck smoothness of 86 seconds. A colorless dye-containing top sheet and a color developing sheet were obtained in the same manner as in Example 1 except that the support in Example 1 was changed to this support.

Comparative Example 1 A colorless dye-containing top sheet and a color developer were prepared in the same manner as in Example 1, except that the support in Example 1 was changed to high-quality paper with a basis weight of 82.0 g/m2 and a Beck smoothness of 78 seconds. Got a sheet.

Comparative Example 2 The Beck smoothness of an injection molded polyethylene sheet having a basis weight of 56.0 g/m2 was measured to be 28 seconds. A colorless dye-containing top sheet and a color developing sheet were obtained in the same manner as in Example 1 except that the support in Example 1 was changed to this support.

Comparative Example 3 The Beck smoothness of an injection molded polypropylene resin sheet having a basis weight of 67.2 g/m2 was measured to be 44 seconds. A colorless dye-containing top sheet and a color developing sheet were obtained in the same manner as in Example 1 except that the support in Example 1 was changed to this support.

The evaluation results are summarized in Table 1. Beck smoothness was measured using a Beck smoothness tester (Kumagai Riki Kogyo), and dry tensile strength and wet tensile strength were measured using a Tensilon CR-7000 tester (Orientec Co., Ltd.). In addition, to evaluate the uniformity of color development, the colorless dye-containing upper sheet and the lower color developer sheet are stacked together and passed through the nip of a super calendar to develop color, and the uniformity is visually evaluated. , those with slight unevenness in coloring are △
, Those with noticeable color unevenness were rated as ×.

[0043]

[Table 1]

[0044]

As is clear from the above description, according to the present invention, a pressure-sensitive recording material having excellent mechanical strength and water resistance and good color uniformity can be obtained.

Claims (2)

[Claims] Claim 1: A pressure-sensitive recording material that produces a colored image through the reaction of a colorless dye and a color developer, characterized in that the support is a sheet-like material obtained by injection molding synthetic fibers. material. 2. The pressure-sensitive recording material according to claim 1, wherein the Bekk smoothness of the support is 60 seconds or more.