JPH0739212B2 - Thermal recording medium - Google Patents

Description

TECHNICAL FIELD The present invention relates to a light-fixing type thermal recording medium.

(Problems to be Solved by Conventional Techniques and Inventions) It is known to use hydrophobic guanidines as a basic agent in a diazo-based thermosensitive recording medium. However, since free hydrophobic guanidines are alkaline, they are water-soluble that cause blurring of color-recorded characters on the thermosensitive recording medium when they come into contact with inorganic acids such as sulfuric acid, phosphoric acid, and halogens, and organic acids such as acetic acid. Therefore, there is a problem in that a volatile salt is formed, or a coloring phenomenon occurs by contact with a coupling agent used in the recording layer. Therefore, in order to prevent such a phenomenon, it has been proposed to use free hydrophobic guanidines in the form of a basic salt obtained by reacting with an acid, and the above problems have been solved. Since it is high, it does not sufficiently dissolve in the binder due to the printing heat of an ordinary thermal head, and there is a problem that sufficient thermal sensitivity cannot be obtained.

(Means for Solving Problems) The present invention has been made in view of the above points.

That is, an object of the present invention is to improve the thermal sensitivity of a diazo-based heat-sensitive recording medium using a hydrophobic guanidine as a base agent.

The heat-sensitive recording medium of the present invention has a recording layer containing a diazonium compound, a coupling agent and a binder as main components on a support, a hydrophobic aromatic substituted guanidine and a primary dissociation constant of 10 ^−1.
A base agent which is a salt with an organic or inorganic acid in the range of to 10 ^-5 , and a developing layer containing a binder composed of a copolymerized polymer compound containing methyl methacrylate as a main component as a main component, It is characterized by being laminated in this order.

In the present invention, as the organic or inorganic acid that reacts with the hydrophobic aromatic-substituted guanidines to form a salt, either a monobasic or polybasic acid can be used. From the viewpoint of improving, it is preferable that the salt formed is insoluble or hardly soluble in water,
Moreover, in order not to reduce the alkalinity of the hydrophobic aromatic-substituted guanidines in the form of the salt formed, those having a first-order dissociation constant in the range of 10 ^-1 to 10 ^-5 are desirable.

Any acid can be used as long as it has an acid having the above-mentioned properties, but as the acid that is preferably used, inorganic acids such as HSCN, HPF ₆ , and H ₂ SnF ₆ can be mentioned. Examples of the acid include tartaric acid, citric acid, malic acid, maleic acid, terephthalic acid, isophthalic acid, adipic acid and paratoluenesulfonic acid.

As the hydrophobic aromatic substituted guanidines used in the present invention, those generally known may be used, for example, 1,3-diphenylguanidine, 1,3-di-O-tolylguanidine, triphenylguanidine, 1,3-di-O-tolyl-2-phenylguanidine and the like are preferably used.

The salt used in the present invention formed by the reaction of the above-mentioned acid and the hydrophobic aromatic-substituted guanidine can be obtained by a conventional production method. That is, after pre-weighed equivalent amounts of the hydrophobic aromatic-substituted guanidines and the acid are dissolved or dispersed in a suitable solvent, stirring is continued until the reaction is completed, and the produced reaction product is mixed with a suitable solvent. After extraction or crystallization, the salt of the hydrophobic aromatic-substituted guanidines and acid used in the present invention can be obtained by separating and drying by a conventional method.

In the above reaction, there is no problem in heating at an appropriate temperature to accelerate the reaction and using an acid in a slightly excess amount so as not to leave free guanidines.

The salt of the hydrophobic aromatic-substituted guanidines obtained as described above is a conventional method for coating, for example, using a means such as a sand mill, a roll mill, a pole mill, or a pearl mill, and other additives added as necessary. It is desirable to grind at the same time as the agent.

The pulverization of the salt of the hydrophobic aromatic-substituted guanidine thus obtained is kneaded into the binder to form the material for the developing layer constituting the thermal recording medium of the present invention.

If necessary, the binder may include polyethylene waxes for improving thermal color development properties and storage stability, higher fatty acids such as stearic acid, amides such as stearic acid amide, and melting point depressants such as zinc stearate. Can be added.

The resin constituting the binder of the developing layer contains methyl methacrylate as a main component in terms of thermal sensitivity and resistance to a plasticizer in a commuter pass, which is one form of application of the thermal recording medium of the present invention. A copolymerized polymer compound is used.

That is, since polymethylmethacrylate alone has a high glass transition point, sufficient thermal sensitivity cannot be obtained due to insufficient fluidity due to the printing heat of the thermal head, but copolymerization containing methylmethacrylate as a main component. In the case of a polymer compound, the glass transition point is lowered, so that sufficient fluidity is generated by the printing heat of the thermal head, and the salt of guanidines is dispersed and dissolved to improve the thermal sensitivity.

In the present invention, compounds having a reactive double bond can be widely used as the compound which reacts with methyl methacrylate to form a copolymerized polymer compound, and examples thereof include styrene, butadiene, acrylic acid and methacrylic acid acrylic acid. Derivatives and those that react with methyl methacrylate such as vinyl acetate to form linear copolymerized polymer compounds, or oligomers such as polyesters, polystyrene, and acryl having a double bond at the end, which are methyl methacrylate What reacts with and produces | generates a kraft copolymer high molecular compound can be used, and you may use 2 or more types of the said compounds. However, from the viewpoint of improving thermal sensitivity and plasticizer resistance, a derivative of methacrylic acid among the above compounds, for example, ethyl methacrylate, n-butyl methacrylate, -isobutyl methacrylate, 2-hydroxyethyl methacrylate, It is preferable to use stearyl methacrylate, methacrylic acid amide, or the like, or an acrylic or polyester oligomer having a double bond at the terminal.

The polymerization reaction of the above compound and methyl methacrylate can be carried out by a conventional radical polymerization, but the copolymerized polymer compound of the reaction product is methyl methacrylate 100
On the other hand, it is necessary to operate the reaction conditions so that the reaction compound is 100 to 5 (molar ratio).

Further, the molecular weight of the copolymerized polymer compound is preferably 5,000 to 300,000, preferably 20,000 to 200,000 from the viewpoint of thermal sensitivity and sticking property in a commuter pass which is one form of use of the thermal recording medium of the present invention. .

The ratio of the salt of the guanidines and the binder obtained as described above is 0.2 to 5.0, preferably 0.5 to 2.0 parts by weight of the binder to 1 part by weight of guanidine, and the mixture is dissolved in an organic solvent to form a mixture. A coating material forming the developing layer of the invention can be obtained.

The coating material obtained as described above is used in a conventional manner on a recording layer containing a diazonium compound, a coupling agent and a binder provided on a support as a main component and a binder. In consideration of the types of the above, the thermal sensitive recording medium of the present invention is constructed by forming a developing layer by coating with a thickness of 0.5 to 5 μm.

Further, in the present invention, a protective layer may be formed on the developing layer in order to improve the running property on the thermal head.
This protective layer can be formed by a coating material obtained by adding wax or fluororesin powder to an appropriate synthetic resin, and its thickness is about 1 to 5 μm.

(Effect of the Invention) The developing layer of the thermal recording medium of the present invention is composed of a hydrophobic aromatic-substituted guanidine as a low water-soluble salt with an organic or inorganic acid, and therefore is contained in an aqueous electrolyte solution or the like. Almost no reaction with the generated acid occurs, and the storability of the recording medium after fixing is improved. Further, since this salt has a lower polarity in an organic solvent having a higher polarity and a lower polarity than the free guanidines, the chemical resistance of the recording medium is improved.

Further, since the binder used in the phenomenon layer of the present invention is composed of a copolymer compound having methyl methacrylate as a main component, it has good fluidity at the time of thermal head printing and improves thermal sensitivity of the recording medium. In addition, the resistance to the plasticizer is improved.

Furthermore, in the case where the protective layer is provided, not only the running property of the thermal head is improved but also the printing durability is improved.

Hereinafter, the present invention will be described in more detail based on specific examples, but the present invention is not limited to the following examples.

Example 1 A primer layer was formed on a milky white polyester (Toray Lumirror E-20) having a thickness of 188 μm by a roll coating method using a coating composition having the following composition to a dry coating thickness of 1 μm.

Then, a recording layer was formed by coating the primer layer with an ink having the following composition to a dry coating thickness of 1 μm by a roll coating method.

Then, a developing layer was formed by coating the recording layer with a coating composition having the following composition by a gravure coating method so as to have a dry coating thickness of 1 μm.

Next, a coating composition having the following composition was used to form a protective layer by coating the development layer with a dry coating thickness of 2 μm by a roll coating method to obtain a heat-sensitive recording medium of the present invention.

(Primer layer) Linear polyester resin (Du Pont # 49000) 10 parts Cyclohexanone 45 parts Methyl ethyl ketone 45 parts (Recording layer) 4-morpholino-2,5-di-n-butoxybenzenediazonium hexafluorophosphate 1 part 2-hydroxy-3 -Naphthoic acid-2'-ethoxyanilide 1.5 parts Vinyl chloride vinyl acetate copolymer resin (UCCVAGH) 6 parts Methyl ethyl ketone 31 parts Toluene 11 parts (Development layer) 1,3-di-O-tolylguanidine adipic acid 1 part Methyl methacrylate -Ethyl methacrylate copolymer (7:
3 molar ratio, molecular weight 100,000) 1 part Toluene 4 parts (protective layer) Methyl metamethyl resin 10 parts Polyethylene wax (ADEKA AGERS FC-113)
1.5 parts Fluorocarbon thermal mold release agent (MOLDWIZ F-57) 1.5 parts Toluene 90 parts Example 2 Methyl methacrylate-ethyl methacrylate as a binder used in the developing layer of Example 1 was replaced with methyl methacrylate and polyester oligomer ( Daicel Chemical Co., Ltd., Placel FM-
A thermosensitive recording medium of the present invention was obtained in the same manner as in Example 1 except that the copolymer (5) (95: 5 molar ratio, molecular weight 120,000) was used.

Comparative Example 1 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that the binder used in the developing layer of Example 1 was changed from methyl methacrylate-ethyl methacrylate to polymethyl methacrylate (molecular weight 100,000). .

Comparative Example 2 A thermosensitive recording medium was prepared in the same manner as in Example 1 except that the binder used in the developing layer of Example 1 was changed from methyl methacrylate-ethyl methacrylate to poly (n-butyl methacrylate) (molecular weight 100,000). Obtained.

The evaluation results of Examples 1 and 2 and Comparative Examples 1 and 2 are shown in the table.

From the above results, it can be seen that the thermal recording medium of the present invention has excellent thermal sensitivity and high resistance to the plasticizer.

Evaluation method (1) Color density This is the color density when recorded at 1 mJ / dot with a line type thermal head.

(2) Plasticizer resistance In a vinyl chloride pass case, the printed characters are allowed to stand for 10 days under the conditions of temperature of 40 ° C, humidity of 90%, and pressure of 200 g / cm ² for bleeding observation.

Front page continuation (72) Inventor Ryohei Takiguchi 5-16-13 Yatsu, Narashino, Chiba Prefecture Echo Heights 102 (72) Inventor Masao Fukagawa 3-6-6 Kirigaoka, Midori-ku, Yokohama-shi, Kanagawa (56) References 58-205145 (JP, A) JP 58-128893 (JP, A) JP 58-220790 (JP, A)

Claims (1)

[Claims] 1. A recording layer containing a diazonium compound, a coupling agent, and a binder as main components on a support, a hydrophobic aromatic-substituted guanidine, and a first-order dissociation constant in the range of 10 ^-1 to 10 ^-5. A base agent which is a salt with an organic or inorganic acid, and a developing layer containing a binder composed of a copolymerized polymer compound containing methyl methacrylate as a main component, as a main component, are laminated in this order. Thermal recording medium.