JPS59143683A - Heat-sensitive recording material - Google Patents

Abstract

PURPOSE:To prevent the adherence and sticking phenomenon of dregs by using a heat-sensitive recording material containing the fine particles of a copolymer obtaned from styrene and a cross linking agent or styrene, a monomer copolymerizable with styrene and a cross linking agent. CONSTITUTION:A heat-sensitive luminous layer contains the fine particles of a copolymer obtained from styrene (a) and a cross linking agent (c) or/and a copolymer obtained from styrene (a), a monomer (b) copolymerizable with styrene (a), and a cross linking agent (c). The monomer (b) simple or a mixture of acrylnitrile, methyl (metha)acrylate, etc., and the preferred amount of the monomer (b) is 60pts.wt. or less on the basis of 100pts.wt. of the whole component. The cross linking agent (c) used includes oil-soluble multi-functional unsaturated monomers or multi-functional unsaturated prepolymers which are used solely or in combination. The mixing ratio of the cross linking agent (c) is 0.02pts.wt. or more on the basis of 100pts.wt. of the whole components. The grain size of the copolymer is preferably 0.1-20mum and the preferred amount of the copolymer used in the recording layer is 5-60wt%.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-sensitive recording material. More specifically, it contains copolymer fine particles obtained from styrene and a crosslinking agent, or/and copolymer fine particles obtained from styrene, a monomer copolymerizable with styrene, and a crosslinking agent. Concerning recording materials. A heat-sensitive recording material is a recording material in which a heat-sensitive color-forming layer that forms a colored image by heating is provided on a support such as paper. Sensitive to heat from thermal pens, etc.
The throat is used.

Because such heat-sensitive recording materials can easily produce colored images simply by heating, their uses are increasingly expanding with the advancement of the information society, and today they are used in electronic computers, facsimiles, telex machines, and various physical and chemical measuring instruments. It is widely used as a recording material for automatic ticket vending machines, etc., and in recent years, with the increase in speed and density of information, there has been an increasing demand for the development of heat-sensitive recording paper with a quality that can meet these demands.

Conventional heat-sensitive coloring layers of heat-sensitive recording materials include lactone rings,
Those containing a colorless or light-colored leuco dye having a lactam ring or a spiropyran ring and an acidic substance that reacts with the leuco dye to color it when heated are widely used because of their vivid color tones. It's here. However, when a thermosensitive recording material comprising a thermosensitive coloring layer having the composition described above is brought into contact with a thermal element such as a thermal head or a thermal pen to obtain a colored image, the components in the thermosensitive coloring layer melt, and the melted components melt. , it adheres to a hot pen or a thermal pen, causing so-called scum adhesion and O-sticking phenomena. In particular, when the heat-sensitive coloring layer contains an amide compound known as a heat sensitivity enhancer or various other sensitivity enhancers, the phenomenon of scum adhesion and sticking occurs significantly.

Furthermore, since such a heat-sensitive recording material is sensitive to scratch friction, it also has the disadvantage of being accompanied by a "pressure coloring phenomenon" in which color develops due to scratch I≠rubbing.

Conventionally, in order to solve these problems, in the heat-sensitive coloring layer support,
Alternatively, inorganic compound powder such as kaolin, clay, titanium oxide, alumina, calcium carbonate, silicon dioxide, etc., or organic resin powder such as phenol resin, urea-formalin resin, polystyrene resin, etc. is added to the intermediate layer between the heat-sensitive coloring layer and the support. Attempts have been made to contain it.

However, none of these methods can be said to be satisfactory. For example, by adding the above-mentioned inorganic compound powder, the adhesion of residue and the sticking phenomenon can be prevented to some extent, but the pressure coloring caused by scratching, etc. is not improved, and in this case, a new problem of abrasion of the thermal head occurs. It cannot withstand long-term use. These problems can be solved to some extent by using thermosetting resins such as urea resins and phenolic resins, but the resins for these purposes are spherical and extremely moldy with particle diameters of 0.1 to 10μ. It requires a special manufacturing process and is expensive. Furthermore, when fine particles of polystyrene or copolymers of polystyrene and other monomers that do not contain a conventional crosslinking agent as a copolymerization component are used, these resins are melted by heat, resulting in scum adhesion and sticking. cause a phenomenon.

The object of the present invention is to provide a heat-sensitive recording material free from such drawbacks.

The present inventors conducted intensive research to improve the above-mentioned drawbacks, and as a result, the thermosensitive coloring layer contains the following (al and (C1 to (al) styrene (bl) monomer copolymerizable with styrene (c), crosslinking agent, etc. copolymer or (aj, (1)l and (C)
The present invention has been completed based on the discovery that the above-mentioned drawbacks can be improved by incorporating fine particles of a copolymer or a mixture thereof.

In the present invention, a copolymer of (al, (cl) or (a).

The copolymer fine particles from (1)) and (C) can be prepared by using a conventionally known emulsion polymerization method in an aqueous medium. For example (a) (c) or (alO
)) (Mixing C1 in an appropriate ratio 1 to emulsifying this in an aqueous medium using an emulsifier and polymerizing (emulsion polymerization) using a polymerization initiator will yield the desired copolymer fine particles.

The copolymer fine particles may be used in the form of an emulsion, or the emulsion may be broken using an emulsion breaking agent, or it may be dried and used as a powder. Examples of intermediate substances (1)) that can be copolymerized with styrene include acrylonitrile, methyl (meth)acrylate, α-methylstyrene, acrylic acid, ethyl (meth)acrylate, vinyl acetate, glinosyl (meth)acrylate, and 2-hydroxy Ethyl (meth)acrylate, 2
-Hydroxypropyl (meth)acrylate and the like. These monomers may be used alone or in combination of two or more. In addition, the mixing ratio of copolymer (al (b) (C1) (1)) and (a) and (C) varies depending on the type of (b) and the intended final product. , (a) (+)+ (for 100 parts of total weight of C1 (
It is preferable that bl is below 60 heavy ground.

Examples of the crosslinking agent (C1) include conventionally known oil-soluble polyfunctional unsaturated monomers or polyfunctional unsaturated prepolymers, such as divinylbenzene, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1.4-butanediol di(meth)acrylate,
Neopentyl glycol di(meth)acrylate, 1,
6-hexanediol di(meth)acrylate, alkylene glycolone(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)-azilylate, dipropylene glycol di(meth)acrylate, polyethylene Glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, ζ °.

゛ ・“ - Pentaerythritol di(meth)acrylate, trimethylolpropane di(meth)acrylate, neopentyl glycol di(meth)acrylate, halogen-substituted alkylene glycol di(meth)acrylate, hydrogen group-substituted alkylene glycol di(meth)acrylate substituted alkylene glycol di(meth)acrylates such as, di(meth)acrylates of alkylene oxide adducts of bisphenol A such as ethylene oxide and/or propylene oxide adducts to hisphenol, ethylene oxide of hydrogenated bisphenol A, etc. Or/and a terminal isocyanate group-containing compound obtained by reacting a di(meth)acrylate or diisocyanate compound of an alkylene oxide adduct of hydrogenated bisphenol A- such as a propylene oxide adduct with two or more alcoholic hydroxyl group-containing compounds in advance. To,
Furthermore, a urethane-modified di(meth)acrylate having two (meth)acryloyloxy groups in the molecule obtained by reacting an alcoholic hydroxyl group-containing (meth)acrylate, and a urethane-modified di(meth)acrylate having two or more epoxy groups in the molecule. Epoxy di(meth)acrylate obtained by reacting a compound with acrylic acid or/and methacrylic acid, acrylic acid or methacrylic acid as the carboxylic acid component, and a polyhydric carboxylic acid, and a polyhydric alcohol of dihydric or higher valence as the alcohol component. Oligoester di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, obtained by reacting
Polyhydric (meth)acrylate of trihydric or higher aliphatic polyhydric alcohol such as pentaerythritol tetra(meth)acrylate, or polyhydric (meth)acrylate of trihydric or higher hydric aliphatic polyhydric alcohol substituted with hydrogen (meth)acrylate-1・3 or more ( Urethane-modified polyvalent (meth)acryloyloxy group-containing
Meta) acrylate. 04 or higher algylene glycol di(meth)acrylate, glycerin tri(meth)acrylate, trimethylolepropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, and bisphenol A ethylene oxide and/or
Or propylene oxide adduct di(meth)acrylate, dipentaerythritol poly(meth)acrylate, 1.2 polybutadiene, 14 polybutadiene, and the like. These crosslinking agents may be used alone or in combination of two or more. The mixing ratio of crosslinking agent (C1 and (a) or (al (II)l) varies depending on the type of crosslinking agent and the intended final product, but (aHc) or (a)
(1) It is preferable to use l (0.02 parts by weight or more based on 100 parts of total weight of C1)-H1 or 0.1 parts by weight or more.The larger the amount of cross-linking agent yF! , the crosslink density increases, heat resistance improves, and scum adhesion and stinking phenomena are improved, but
It is desirable to appropriately select and adjust the type and amount of these crosslinking agents depending on the purpose of the final product. When a polymer copolymerized with such a crosslinking agent is heated, it exhibits some degree of plasticity, but loses its tackiness, and when it is applied to thermal paper, no sticky substances adhere to it, and the stinking phenomenon can be prevented.

Furthermore, by using such a crosslinked polymer, pressure coloring due to scratching friction can be prevented.

We (copolymer obtained from al and (C) or/
The particle size of the copolymer leaked from (al, (1)) and (C) is preferably about 01 to 20μ. The amount of this substance applied to the heat-sensitive recording layer varies depending on the coloring agent, acidic substance, binder, coloring property improver, and other additives used in combination with it or the characteristics of the final product. It is preferable that 5 to 60% (by weight) of the material be contained in the material. Of course, it may be used in combination with a conventionally known inorganic compound powder or organic resin powder, if necessary.

Next, the chemicals constituting the heat-sensitive recording layer will be specifically explained, but they are not limited to this range, and various known chemicals can be used.

First, as a coloring agent, a colorless or light-colored substance known as a leuco substance, which develops color by reacting with an acidic substance such as an organic acid containing a phenolic substance, is used. ~diethylamino-6-methyl~7
-Fluoran dyes such as anilifluorane, 3,3
~Triarylmethane dyes such as bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, other spiropyran dyes, India IJ 7 dyes, thiazine dyes fS1. etc.

In addition, the acidic substance is solid at room temperature, preferably 7
Compounds that have a melting point of 0'C or more and act on a color former to develop color when heated are used. Examples of such compounds include bisphenol A, 4.4'-isoglopylidene bis(2-tert- butylphenol), 4.4'
-5ec-butylidene diphenol, hyrogallol,
70 locrisin, 71:I loglycine carboxylic acid, salicylic acid, 0-hydroxybenzoic acid, m-hydroxybenzoic acid, 2-hydroxy-p-t-ruylic acid, 35-xylenol, thymol, p-tert-butylphenol 14 -Hydroxyphenoxide, methyl-4-hydroxybenzoate, 4-hydroxyacetophenone, α-nanthol, β-naphthonepecatechol, resorcinol, hydroquinone 4-terL-octylcatechol, 4.4'-5ec-butylidenephenol,
Examples include 2'-dihydroxydiphenyl, boric acid, oxalic acid, maleic acid, tartaric acid, citric acid, succinic acid, benzoic acid, and stearic acid.

Examples of color development improvers include higher fatty acid amides, acetoacetanilide, and sulfonic acid ester compounds.

In addition, by incorporating small amounts of vegetable waxes such as carnauba wax and casderilla wax, animal waxes such as beeswax and shellac, petroleum waxes such as paraffin wax, and alkyl ketene dimers into the heat-sensitive recording layer, This has the effect of reducing the sticking phenomenon that occurs due to a drop in the melting point of the melt when color develops.

Furthermore, as a binder, polyvinyl alcohol
Examples include xycellulose, methoxycellulose, carboxymethylcellulose, carboxyethylcellulose, polyacrylic acid, polyacrylamide, polyvinylpyrrolidone, starch, gelatin, etc. These are found in heat-sensitive recording materials and are used to properly disperse and bind various chemicals. It has the effect of imparting smoothness to the surface of the coloring layer.

Surfactants, antifoaming agents, etc. may also be used depending on other necessities.

Next, as a support, paper is generally used, but a film made of synthetic resin or the like can also be used. Koga 1. It is preferable that the support has a smooth surface, and the higher the smoothness, the better the reproducibility and the clearer the image.

This article describes the preparation of heat-sensitive recording materials. Appropriate amounts of the color former, acidic substance, color improver, low-melting wax, binder, and other additives are dispersed in water and then micronized using a ball mill or the like to obtain the desired particle size. Next, like this K
Applying the obtained heat-sensitive coating liquid to the support by a conventional method,
After drying and smoothing treatment such as calendering, the desired heat-sensitive recording material is obtained.

Next, the present invention will be specifically explained with reference to examples and reference examples for comparison. The polymers used are copolymers obtained from the constituent monomers shown in Attached Table 1 and have particle sizes shown in the table. It is.

Table 1 Example 1 After pulverizing all liquids A, B, and C in a ball mill for 2 days, liquid A: liquid B, liquid C, 4:25:25 (parts by weight) were thoroughly mixed to form a heat-sensitive coating liquid. did. 50P of the coating liquid
It was coated on general high-quality paper having a basis weight of /m2 so that the coated amount after drying was about 1051-1, dried, and then subjected to super calendering to obtain a heat-sensitive recording paper with a smoothness of 300 seconds and low gloss. . The results of various tests conducted on this thermal paper with respect to background color development, color density, scratching, thermal head abrasion, residue adhesion, and sticking are shown in Table 2, and all results were satisfactory.

Example 2 The same procedure as in Example 1 was carried out except that the polymer of Deaf 4 (Table 1) was used instead of the polymer of N3. The various test results are shown in Table 2 and were satisfactory.

Example 3 The same procedure as in Example 1 was carried out, except that the polymer of Arashi 5 (Table 1) was used instead of the polymer of Ashi 3.

The various test results are shown in Table 2 and were satisfactory.

Example 4 In Example 1, lV! The procedure was the same as in Example I except that 18 polymers of N6 (Table 1) were used in place of polymer 13.

The various test results are shown in Table 2 and were satisfactory.

Example 5 Interval 7 instead of polymer M3 in Example 1 (Table 1)
The same procedure as in Example 1 was carried out except that the polymer was used.

The results of the various tests are shown in Table 2 and were satisfactory.

Example 6 The same procedure as in Example 1 was carried out except that Polymer Arashi 8 (Table 1) was used in place of Polymer Cavity 3 in Example 1. The various test results are shown in Table 2 and were satisfactory.

(i'it) (11) Background coloring test: Whitening of the obtained thermal paper was measured using a Macbeth densitometer (RD914).

(2) Color density: Color was developed for 5 seconds at lOO'C and measured using a Macbeth densitometer (R, D914).

(3) Scratch test: 0.3mm x l, 3mi
The sample was scratched on a needle with a 5 o o yS load applied, and those with considerable color development were marked with an X mark, and those with almost no color development were marked with an ○ mark.

(4) Wear of the hem: display tint 1
A durability long-run test was conducted on the head using a Thermal Henodo DC-1157 (manufactured by Manufacturer), and those with no wear on the head after 30,000,000 characters were marked with a D mark, and those with obvious wear were marked with an X mark.

(5) Noise adhesion: In the gutter abrasion test described above, a mark ○ was given to those in which no debris was observed on the thermal head, and an X mark was given to those in which it was clearly observed.

(6) Sticking: display tee.

Using a thermal head DC-1,157 (dot type) manufactured by Co., Ltd., those in which no sticking was observed were marked with a circle, and those in which sticking was marked were marked with an x.

Reference Example 1 The same procedure as in Example 1 was carried out except that the N13 polymer in the composition of liquid C was removed. The results of the various tests are shown in Table 2, and were unsatisfactory, with large background color development, low color density, and color development due to scratching, so other tests were omitted.

Reference Example 2 The same procedure as in Example 1 was carried out except that Cal/Rum carbonate was used in place of the tooth 30 polymer in the composition of the liquid.The various test results are shown in the table. In case 2, the background color was large, some color was caused by scratching, and the head was considerably worn, which was not satisfactory.

@Labor 3 The same procedure as in Example 1 was carried out except that the polymer of Shoulder 1 (Table 1) was used in place of the polymer of Section 3 in Example IK.

The results of various tests are shown in Table 2, and were unsatisfactory due to poor adhesion and sticking.

Reference Example 4 The same procedure as in Example 1 was conducted except that a polymer of N112 (Table 1) was used in place of the polymer of Nn3 in Example 1. The results of various tests are shown in Table 2, and the results were unsatisfactory, with poor scum and sticking.

Patent applicant: Nippon Kayaku Co., Ltd.

Claims (1)

[Claims] (11) A heat-sensitive recording material characterized by containing copolymer fine particles comprising styrene and a crosslinking agent, or/and copolymer fine particles comprising styrene, a monomer copolymerizable with styrene, and a crosslinking agent.