JPH06115242A - Biodegradable heat-sensitive recording material - Google Patents

Abstract

PURPOSE:To obtain a heat-sensitive recording material which holds required merits and causes no problem of disposal and discard after it is used, by a method wherein a support having a heat-sensitive color forming layer disposed on its upper surface is formed of a biodegradable plastic material mainly composed of fatty polyester. CONSTITUTION:A heat-sensitive recording material has a heat-sensitive color forming layer disposed on a support, said layer being mainly composed of a colorless or light-colored color forming compound and a developing compound for causing the color forming compound to develop a color when heated. In this case, the support is formed of a biodegradable plastic material mainly composed of fatty polyester. Thus, it is possible to obtain a heat-sensitive recording material which holds the merits of heat-sensitive recording characteristic and mechanical strength that recording materials made of conventional paper do not have but those made of plastic or synthetic paper have, and which causes no problem of disposal and discard after it is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosensitive recording material having good biodegradability.

[0002]

2. Description of the Related Art Generally, a heat-sensitive recording material is prepared by separately dispersing a leuco dye and a color developing agent such as a phenolic substance in the form of fine particles and mixing them together, and then adding a binder, a sensitizer, a filler, It is a coating liquid prepared by adding additives such as lubricants, and is applied to paper, film, synthetic paper, etc., and it develops color due to the chemical reaction that occurs when one or both of the leuco dye and developer melts and is heated by heating. Get the record. A thermal printer or the like having a built-in thermal head is used for color development of such a thermal recording sheet. Compared to other recording methods, this heat-sensitive recording method has (1) no noise during recording,
Due to the features of (2) no need for development and fixing, (3) maintenance-free, (4) relatively inexpensive machines, the field of facsimiles, computer output, printers such as calculators, medical It is widely used in the fields of measurement recorders, automatic ticket vending machines, and heat-sensitive recording labels.

In recent years, an increasing number of examples are using a plastic film, synthetic paper or the like instead of the paper typified by the support of the thermal recording material. Thermosensitive recording materials with a plastic film or synthetic paper as a support have excellent recording surface smoothness, mechanical strength and water resistance, and are functionally transparent, so that prepaid cards, video Applications are expanding to printer paper, OHP sheets, etc.

However, the heat-sensitive recording material using a plastic film, synthetic paper or the like as a support has good recording characteristics and storability in use as described above, but is disposed of when it becomes unnecessary. Alternatively, when it is discarded, it is not decomposed even if it is buried in the soil, and there are problems of flame retardancy and generation of toxic gas when incinerated. The used recording materials are
The current situation is accumulation of garbage or industrial waste, and there is an urgent need to quickly find a disposal method that is environmentally friendly.

[0005]

The objects of the present invention are as follows.
It is to solve the problems of the prior art. That is, while disposing of when used, disposal and disposal while maintaining the advantages such as thermal recording characteristics and mechanical strength that the recording material using plastic film or synthetic paper does not have compared to conventional recording materials using paper. The object is to provide a heat-sensitive recording material having no problem.

[0006]

The inventors of the present invention have completed the present invention as a result of various studies to achieve the above object. That is, the present invention is a heat-sensitive recording material comprising a thermosensitive color-developing layer containing a colorless or light-colored color-developing compound and a color-developing compound capable of thermally coloring the color-developing compound as a main component on a support, A heat-sensitive recording material characterized in that the support is made of a biodegradable plastic material mainly composed of an aliphatic polyester.

The present invention will be described in detail. In the present invention, as the biodegradable plastic material mainly composed of aliphatic polyester used for the support for forming the thermosensitive coloring layer, those having high water resistance are preferably used. You may use these as a composite of 2 or more types.

Specific examples include poly (3-hydroxybutyric acid), poly (3-hydroxyvaleric acid), copolymers of 3-hydroxybutyric acid and 3-hydroxyvaleric acid, and 3-hydroxybutyric acid and 4-hydroxybutyric acid. Copolymers, aliphatic polyester compounds produced by microorganisms generally called 3-hydroxyalkanoate, polyglycolic acid, polylactic acid, polycaprolactone, polyethylene succinate,
Examples thereof include chemically synthesized aliphatic polyester compounds such as polybutylene adipate, polybutylene sebacate, and polyhexamethylene adipate, and copolymers thereof.
It is preferable that these have a weight average molecular weight of about 5,000 to 1,000,000. Further, it can be modified by adding a plasticizer or reacting with a small amount of a diisocyanate compound or an epoxy compound without impairing the biodegradability, and these also meet the object of the present invention.

Further, as the complex, for example, a complex can be obtained by combining the above-mentioned aliphatic polyester compound and a commonly used biodegradable polymer compound such as cellulose, starch, polyvinyl alcohol and casein, These can also be used in the present invention, but the condition is that the surface of the composite is made of a biodegradable aliphatic polyester compound.

The heat-sensitive recording material of the present invention has a thickness of 5 to 1,
000 μm, preferably 50 to 300 μm, on the biodegradable plastic sheet having the above composition, the following (A) color-developing compound, (B) color-developing compound, (C) binder and other additives if necessary. It is obtained by forming a thermosensitive coloring layer consisting of.

(A) Examples of chromophoric compounds Fluoran compounds, triarylmethane compounds, spiropyran compounds, diphenylmethane compounds, thiazine compounds, lactam compounds, fluorene compounds, etc., and specific examples thereof are listed. For example, the following compounds may be mentioned. Fluoran compounds; 2-aniline-3
-Methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6- (N-methyl-N-cyclohexylamino) fluorane, 2-anilino-3-methyl-6
-(N-ethyl-N-isopentylamino) fluorane, 2- (p-chloroanilino) -3-methyl-6-diethylaminofluorane, 2- (p-fluoroanilino) -3-methyl-6-diethylaminofluor Oran, 2
-Anilino-3-methyl-6- (p-toluidinoethylamino) fluorane, 2- (p-toluidino) -3-methyl-6-diethylaminofluorane, 2- (o-chloroanilino) -6-dibutylamino Fluoran, 2-
(O-Fluoroanilino) -6-dibutylaminofluorane, 2-anilino-3-methyl-6-piperidinofluorane, 2-anilino-3-methyl-6-pyrrolidinofluorane, 2-ethoxyethyl Amino-3-chloro-6
-Diethylaminofluorane, 2-anilino-3-chloro-6-diethylfluorane, 2-chloro-6-diethylaminofluorane, 2-methyl-6-diethylaminofluorane, and the like,

Triarylmethane compounds; 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone), 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3-
(1,2-Dimethylaminoindole-3-) isophthalide and other spiropyran compounds; 3-methyl-3-spirodinaphthopyran, 1,3,3-trimethyl-6-
Nitro-8'-methoxyspiro (indoline-2,2 '
-Benzopyran), etc., diphenylmethane compounds; N
-Halophenyl-leuco auramine and other thiazine-based compounds; benzoyl leuco methylene blue and other lactam-based compounds; Rhodamine-B-anilinolactam and other fluorene-based compounds; ) -6'-Dimethylaminophthalide, 3,6-bis (dimethylamino) fluorene spiro (9,3 ')-6'-pyrrolidinophthalide, 3-dimethylamino-6-diethylaminofluorenspiro (9,3) ') -6'-Pyrrolidinophthalide

(B) Examples of color-developing compounds α-naphthol, β-naphthol, p-octylphenol, 4-t-octylphenol, pt-butylphenol, p-phenylphenol, 1,1'-bis (p- Hydroxyphenyl) propane, 2,2'-bis-
(P-Hydroxyphenyl) propane, 2,2'-bis (p-hydroxyphenyl) butane, 1,1'-bis (p-hydroxyphenyl) cyclohexane, 4,4 '
-Thiobisphenol, 4,4'-cyclo-hexylidene diphenol, 4,4'-sulfonyldiphenol,
2,2'-bis (2,5-dibromo-4-hydroxyphenyl) propane, 4,4'-isopropylidenebis (2-t-butylphenol), 2,2'-methylenebis (4-chlorophenol), etc. Phenolic compounds,
Benzyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, dibenzyl 4-hydroxyphthalate, 4-
Dimethyl hydroxydiphthalate, ethyl 5-hydroxyisophthalate, 3,5-di-t-butylsalicylic acid, 3,
Examples thereof include aromatic carboxylic acid derivatives such as 5-di-α-methylbenzyl salicylic acid, aromatic carboxylic acids, and polyvalent metal salts thereof.

(C) Examples of binders Methylcellulose, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, cellulose, polyvinyl alcohol (PVA), carboxylated modified polyvinyl alcohol, sulfonated modified polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide. , Polyacrylic acid, starch and its derivatives, casein, gelatin, water-soluble isoprene rubber, styrene / maleic anhydride copolymer, iso (or diiso) butylene / maleic anhydride copolymer, polyvinyl acetate, vinyl chloride / acetic acid Copolymer of vinyl, polystyrene, polyacrylic acid ester and its copolymer, polyurethane, styrene / butadiene (SB) copolymer, carboxylated polystyrene A water-soluble emulsion such as a copolymer / butadiene copolymer, composite particles of colloidal silica and acrylic acid resin, or the like is used.

Examples of Other Additives Examples of fillers include calcium carbonate, magnesium carbonate, magnesium oxide, silica, white carbon, talc, clay, alumina, magnesium hydroxide, aluminum hydroxide, aluminum oxide, barium sulfate, There are polystyrene resin, urea-formalin resin and the like.

Examples of the heat-fusible compound include waxes such as animal and vegetable wax, polyethylene wax and synthetic wax, higher fatty acids, higher fatty acid amides, higher fatty acid metal salts, acetylated aromatic amines, aromatic ether compounds and biphenyls. Examples include derivatives that are solid at room temperature and have a melting point of about 80 ° C. or higher. In addition, lubricants such as zinc stearate, calcium stearate and aluminum stearate, various surfactants, antifoaming agents and the like are added as necessary.

The heat-sensitive recording material of the present invention is prepared by using the above-mentioned material, for example, by the following method. Preparation of support: A sheet having a thickness of 50 to 300 μm is prepared by subjecting an aliphatic polyester produced by a microorganism to a solvent casting method or a melt extrusion method. Preparation of thermosensitive color developing layer coating liquid: The color-developing compound and the color-developing compound are separately pulverized and dispersed by a dispersing machine such as a ball mill, attritor, or sand mill together with a binder or other additives as required. After that, the color-developing compound and the color-developing compound are mixed in a weight ratio of 1: 1 to 1: 5 when dried to prepare a thermosensitive color-developing layer coating solution. Preparation of thermosensitive recording material: 10 g of the thermosensitive coloring layer coating liquid on the above-mentioned support when dried.
/ M ² is applied and dried to obtain the heat-sensitive recording material of the present invention. Further, a protective layer may be provided on the thermosensitive coloring layer, if necessary.

The heat-sensitive recording material of the present invention is excellent in heat-sensitive recording characteristics and mechanical strength at the time of use, and when it is used and disposed of, it is biodegradable by burying it in the soil. It is functional and contributes as a solution to the waste problem currently facing society.

[0019]

EXAMPLES The present invention will be described in more detail by way of examples, but the present invention is not limited thereto. In the examples, "part" indicates part by weight.

Example 1 Preparation of Support: Copolymer of 3-hydroxybutyric acid and 3-hydroxyvaleric acid (20 mol of 3-hydroxyvaleric acid component was used)
1%, melting point = 142 ° C., molecular weight = about 750,000)
A biodegradable sheet having a thickness of about 200 μm was prepared by a solvent casting method using dichloroethane as a solvent.

Preparation of thermosensitive recording material: A mixture having the following composition was pulverized for 30 minutes using a sand grinder to prepare solutions (A) and (B), respectively. Liquid (A): 2-anilino-3-methyl-6-dibutylaminofluorane 25 parts 25% PVA aqueous solution 20 parts Water 55 parts Liquid (B): 2,2′-bis (p-hydroxyphenyl) propane 25 parts 25% PVA aqueous solution 20 parts water 55 parts Next, (A) solution 4 parts (B) solution 16 parts 50% carboxylated SB copolymer latex 6 parts are mixed to prepare a thermosensitive color developing layer coating solution, and the above-mentioned raw material is prepared. The weight when dried using a bar coater on the degradable sheet is 10 g /
The heat-sensitive recording material of the present invention was obtained by applying and drying so as to obtain m ² .

Example 2 Instead of the copolymer of 3-hydroxybutyric acid and 3-hydroxyvaleric acid of Example 1, a copolymer of 3-hydroxybutyric acid and 4-hydroxybutyric acid (4-hydroxy) having a thickness of about 100 μm was used. A thermosensitive recording material of the present invention was obtained in the same manner as in Example 1 except that the butyric acid component was 9.5 mol%, the melting point was 160 ° C., and the molecular weight was about 320,000.

Synthesis Example 1 In a 100 ml four-necked flask, 10.4 g of succinic acid,
1,4-butanediol 8.19 g, poly 3-hydroxybutyric acid 0.77 g, L-tartaric acid 0.45 g, methanesulfonic acid 0.05 g, and toluene 45 ml were charged, and 100
After reacting for 12 hours while removing water distilled near ℃,
When 3 ml of water had distilled off, 0.5 ml of isophorone diisocyanate was added and reacted at 110 ° C. for 4 hours. This was opened in the evaporation dish as it was, and the toluene was scattered. An aliphatic polyester having a number average molecular weight of about 150,000 was obtained.

Example 3 Instead of the copolymer of 3-hydroxybutyric acid and 3-hydroxyvaleric acid of Example 1, the aliphatic polyester compound (melting point = 100 ° C., molecular weight = about 150,000) shown in Synthesis Example 1 was used. A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1 except that the film produced by the melt extrusion method was used.

Comparative Example 1 A transparent polyester film having a thickness of 100 μm (made by Toray: Lumirror S, polyethylene terephthalate) is used as a support.
A thermal recording material for comparison was obtained in the same manner as in Example 1 except that was used.

Comparative Example 2 A thermal recording material for comparison was obtained in the same manner as in Example 1 except that a transparent triacetate film having a thickness of 180 μm (Fuji Photo Film, Fuji Photo Film) was used as the support.

Comparative Example 3 Synthetic paper having a thickness of 80 μm (made by Oji Yuka: Yupo S
A thermosensitive recording material for comparison was obtained in the same manner as in Example 1 except that GG-80) was used.

Comparative Example 4 A heat-sensitive recording material for comparison was obtained in the same manner as in Example 1 except that the support used was high-quality paper (manufactured by Kishu Paper Co., Ltd .: gold sand) having a basis weight of 55 g / m ² . The following quality tests were carried out on the heat-sensitive recording materials of the present invention and comparative examples obtained as described above.

Table 1 Quality performance test Color density 1) Mechanical strength 2) Biodegradability 3) Example 1 1.43 ○ ○ Example 2 1.45 ○ ○ Example 3 1.42 ○ ○ Comparative example 1 1. 42 ○ × Comparative Example 2 1.44 ○ × Comparative Example 3 1.40 ○ × Comparative Example 4 1.13 × ×

Note 1) Color density: value obtained by printing a sample with a thermal printer D-805P type manufactured by Ishida Koki Co., Ltd. measured by a Macbeth reflection densitometer RD-914 type (reflection density). 2) Mechanical strength: The state when the sample is soaked in water for about 5 minutes and then picked up by hand. ○ = Maintain the original form. × = When damaged. 3) Biodegradability: The morphology was observed after the sample was buried in the soil of Shimo, Kita-ku, Tokyo for two months. ○ = Almost no morphology
△ = morphology is recognized, but many holes are open, × = morphology is maintained as it was when buried.

As is apparent from the above quality performance test table, the heat-sensitive recording material of the present invention has excellent biodegradability while maintaining excellent heat-sensitive recording characteristics like conventional plastic films and synthetic papers. Show. Such an effect has an advantage that there is no problem in disposal when considering the disposal of used products.

[0032]

EFFECTS OF THE INVENTION A heat-sensitive recording material having advantages such as a heat-sensitive recording property and mechanical strength like a plastic film or a synthetic paper and having no problem in disposal and disposal when used is obtained.

Claims (1)

[Claims] 1. A thermosensitive recording material comprising a support and a thermosensitive coloring layer containing a colorless or light-colored coloring compound and a color-developing compound capable of coloring the coloring compound when heated as a main component. A heat-sensitive recording material characterized in that the support is made of a biodegradable plastic material mainly composed of an aliphatic polyester.