JP2001171248A - Thermal transfer recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal transfer recording medium, which is excellent in heat resistance and lubricating properties and, in addition, in which a backing layer also excellent in a Si migration resistance is provided. SOLUTION: In this thermal transfer recording medium, a heat resistant and lubricity layer (or the backing layer) consisting of a copolymer of a reactive silicon and a vinyl monomer and a self-cross-linkable acryl-based resin is provided on a surface abutting against the thermal head provided on the under surface of a base material, on the top surface of which a thermal transfer ink layer is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer recording medium having excellent heat resistance and lubricity.

[0002]

2. Description of the Related Art In recent years, recording methods of a full-color printer include an electrophotographic method, an ink jet method, a thermal transfer recording method, and the like. Among these, the thermal transfer recording method has no noise and has excellent storage stability. Widely used. In the thermal transfer recording method, a recording paper (transfer object) is brought into contact with a thermal transferable ink layer provided on a base material, and selectively heated by a thermal head or the like from the base material side in accordance with a pulse signal or the like, and the heated ink is heated. The recording image is formed by transferring to a recording paper by melting or sublimation. Thermal transfer recording media are used in printers and recorders of various office equipment and the like that employ such a thermal transfer recording method, and as described above, the basic configuration is to provide a thermal transfer ink layer on a base material. It is a thing.

When such a thermal transfer recording medium is heated by a thermal head or the like, a base material, for example, a part of the base material film is melted and adheres to the thermal head or the like, the conveyance becomes poor, and the transfer to the recording paper is difficult. There is a problem that so-called sticking occurs, which becomes difficult.

In order to solve such a problem, there has been proposed a substrate in which a stick preventing agent, for example, a stick preventing agent using a silicone material is applied to the surface of the substrate opposite to the heat transferable ink layer. For example, those using a stick preventive composed of a silicon-based graft polymer (Japanese Patent Laid-Open No. 62-30082) and those using a stick preventive composed of a silicon-modified polyvinyl chloride resin (Japanese Patent Laid-Open No. 4-201491) Using a stick inhibitor consisting of a reaction product of an acrylic silicone graft polymer, an amino-modified silicone oil and a polyfunctional isocyanate (JP-A-4-16390)
Etc. have been proposed.

[0005] These thermal transfer recording media have good lubricity but have a problem of Si migration. That is, a normal thermal transfer recording medium is manufactured by applying a stick inhibitor to a base film, winding it up once, then rewinding it, and forming a thermal transferable ink layer on the other surface. When a stick preventing agent made of a silicone material is used as in the thermal transfer recording medium, the unreacted silicone forms the thermal transfer ink layer of the base film during winding or storage of the wound roll. Side surface, causing poor adhesion to the base film in the formation of the ink layer, or during storage of the manufactured thermal transfer recording medium with a roll, unreacted silicone is transferred from the stick prevention layer to the thermal transferable ink layer. After the transfer of the ink layer to the receptor, the ink layer has a problem of Si migration, such as causing poor adhesion of the ink layer to the receptor. Further, the above-described thermal transfer recording medium has insufficient heat resistance.

As a thermal transfer recording medium improved in such Si transferability, a medium using a stick inhibitor consisting of a reaction product of an acrylic silicon graft polymer and an isocyanate has been proposed (Japanese Patent Application Laid-Open No. 3-155987). ing. However, the thermal transfer recording medium,
Although Si migration resistance and heat resistance are good, there is a problem that lubricity is insufficient.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a thermal transfer method provided with a heat-resistant / slip layer made of a silicone-based material having excellent lubricity and heat resistance, and further excellent mechanical strength, and excellent Si migration resistance. It is intended to provide a recording medium.

[0008]

According to the present invention, a thermal transfer ink layer is provided on the upper surface of a substrate, and the surface of the lower surface of the substrate which is in contact with the thermal head is coated with a reactive silicone and vinyl monomer. A thermal transfer recording medium is provided, wherein a heat-resistant / slip layer comprising a self-crosslinkable acrylic resin is provided. According to the present invention, the thermal transfer recording medium is characterized in that the copolymer of the reactive silicone and the vinyl monomer is a copolymer of the reactive silicone and an acrylic monomer. Provided. Further, according to the present invention, there is provided the thermal transfer recording medium, wherein the self-crosslinkable acrylic resin is a polymer of methacrylic acid having a reactive group.

That is, the present inventors have proposed that the back layer of a thermal transfer recording medium be made of a heat-resistant and lubricous material comprising a mixture of a copolymer of a reactive silicone and a vinyl monomer and a self-crosslinkable acrylic resin. It has been found that the above object can be achieved by using a material having excellent mechanical strength and resistance to Si migration, and the present invention has been completed. In the present invention, the reason why such a back layer is provided with excellent slipperiness, heat resistance, mechanical strength, resistance to Si migration, and the like by providing such a back layer is not clear, but is considered as follows. The back layer in the present invention, that is, the heat-resistant / slippery layer, is constituted by mixing a self-crosslinkable acrylic resin with a copolymer of a reactive silicone and a vinyl monomer, thereby forming the self-crosslinkable acrylic resin. By forming a cross-linked structure in which both components are entangled during self-cross-linking of the system resin, heat resistance and mechanical strength are improved, and because of the silicone part, not only lubricity is good, but also stick Since the prevention layer is strongly bonded to the base film, and thus the silicone portion is firmly bonded, the surface of the base film on which the heat transferable ink layer is provided, and the transfer and transfer of the Si component to the ink layer are prevented. Think of what you can do.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. As described above, the thermal transfer recording medium of the present invention comprises a heat-resistant and lubricating layer comprising a copolymer of reactive silicone and a vinyl monomer (hereinafter referred to as a modified copolymer) and a self-crosslinkable acrylic resin. And characterized in that: In the present invention, the copolymer of a reactive silicone and a vinyl monomer is a copolymer of a vinyl monomer having a silicone chain with another vinyl monomer, and a reactive silicone having a functional group. And a graft copolymer in which a vinyl monomer is copolymerized.

The reactive silicone used as the raw material of the modified copolymer used in the present invention includes a silicone compound having a functional group such as an OH group or an epoxy group at one end, and a poly-silicon having a radically polymerizable unsaturated group at one end. Alkyl siloxane compounds, etc., having a molecular weight of 100 to 5000
A thing of about 0 is preferable. Specific examples of the reactive silicone in the present invention include the following. Molecular weight 5
As the reactive silicone of less than 00, OH group, epoxy group, SH, COO at one end as shown in Tables 1 and 2
Those having a functional group such as H, an unsaturated double bond, or a polydimethylsiloxane-based polymer initiator as shown in Table 3 can also be used.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

[Table 3]

In the present invention, the amount of the reactive silicone in the modified copolymer is important, preferably in the range of 5 to 60% by weight, particularly preferably in the range of 10 to 40% by weight. . When the amount of the reactive silicone in the modified copolymer is small, the strength of the film is improved, but the lubricity, the releasability, and the resistance to fusion to the thermal head are inferior. Of the ink, adhesion of oily residue to the thermal head due to increase of the unreacted silicone component, migration of Si to the base film and the heat transferable ink layer, and the like occur.

In the present invention, the vinyl monomer as a raw material for forming the modified copolymer together with the reactive silicone component is selected from the viewpoints of heat resistance, adhesion to the substrate, reactivity with the reactive silicone, and the like. It can be selected from conventionally known ones.
Examples of the copolymerizable with the reactive silicone include the following vinyl monomers. For example, methyl acrylate, ethyl acrylate, n-butyl acrylate, i
So-butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, methyl vinyl ether, ethyl vinyl ether, n
-Propyl vinyl ether, n-butyl vinyl ether, iso-butyl vinyl ether, styrene, α-methylstyrene, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, allyl alcohol, glycidyl acrylate, glycidyl methacrylate, glycidyl allyl ether, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, maleic anhydride, Citraconic acid, acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide,
Vinyl monomers such as N, N-dimethylacrylamide, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate, and diacetone acrylamide. Further, silane coupling agents such as γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane can also be used. Two or more of the above monomers may be used.

In the present invention, the modified copolymer has a large effect in improving the adhesion to the base material and the heat resistance and in preventing sticking.
It is also important that the glass transition point at the homopolymer level is high. The glass transition point at the homopolymer level is preferably 80 ° C. or higher. In the present invention, methyl methacrylate (Tg: 105 ° C.), methacrylic acid (T
g: 130 ° C.) is particularly preferred from the viewpoint of heat resistance and copolymerization reactivity.

The above modified copolymer is usually produced by solution polymerization. In the solution polymerization, aromatic hydrocarbon solvents such as toluene and xylene, ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as ethyl acetate and butyl acetate, and alcohol solvents such as ethanol and isopropanol. And the like can be used alone or as a mixed solvent. In the solution polymerization, an oil-soluble polymerization initiator such as benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide, azobisisobutyronitrile, and azobisvaleronitrile is used.

The self-crosslinkable acrylic resin used in the present invention includes acrylic acid, methacrylic acid, polymers and copolymers of these esters having reactivity to the crosslinking reaction, and a monomer and styrene. , Vinyl acetate,
It is a copolymer with vinyl chloride, acrylonitrile, acrylamide and the like. These reactive groups include a carboxyl group, an epoxy group, a hydroxyl group, an amide group, a methylol group, and the like, which react with each other during crosslinking.

Examples of the self-crosslinkable acrylic resin include acrylic acid-alkyl methacrylate copolymer, acrylic acid-alkyl acrylate copolymer, vinyl acetate-acrylic acid copolymer, vinyl acetate-methacrylic acid copolymer, Vinyl acetate-alkyl acrylate copolymer, vinyl acetate-alkyl methacrylate copolymer, acrylonitrile-acrylic acid copolymer, acrylonitrile-acrylic acid-alkyl acrylate copolymer, acrylonitrile-acrylic acid-alkyl methacrylate copolymer Copolymer, acrylonitrile-methacrylic acid copolymer, styrene-acrylic acid copolymer, styrene-acrylic acid-alkyl acrylate copolymer, styrene-methacrylic acid copolymer, styrene-acrylic acid-methacrylic acid copolymer and these It is possible to use derivatives of That. However, these polymers and copolymers have a carboxyl group, an epoxy group, a hydroxyl group, an amide group, a methylol group and the like as reactive groups. Of these, a self-crosslinkable acrylic resin, which is a polymer of methacrylic acid having a reactive group, is most preferable in terms of Si migration resistance and heat resistance.

In the heat and slip resistant layer of the thermal transfer recording medium of the present invention, the mixing ratio of the modified copolymer and the self-crosslinkable acrylic resin is 95 to 40% by weight of the modified copolymer, 5 to 60% by weight of the hydrophilic acrylic resin. If the proportion of the self-crosslinkable acrylic resin is less than 5% by weight, the effect of improving Si migration is not sufficiently exhibited, while if it exceeds 60% by weight, the stick prevention effect is reduced.

The heat-resistant and lubricating layer is formed by coating a base film with an organic solvent solution of a mixture of the modified copolymer and the self-crosslinkable acrylic resin, using a gravure roll coater, a reverse roll coater, and an air knife. It can be performed by a method of applying by a coating method or the like, heating and drying.

The thickness of the heat-resistant / slip layer of the present invention is as follows:
0.01 to 2.00 μm is preferable, and 0.04 to 0.6 μm
μm is more preferred.

The substrate in the thermal transfer recording medium of the present invention includes polycarbonate, polyarylate, polyetherimide, polysulfone, polyphenylether, polyamideimide, polyimide, polyethylene naphthalate, polyphenylsulfide, polyetheretherketone, and fluororesin. In addition to films such as, polyethylene terephthalate, polybutylene terephthalate, polybutylene naphthalate, polyethylene, polypropylene,
Polystyrene, polyvinyl chloride, polyvinylidene chloride,
Films such as nylon can be used. Preferably, the film has biaxial orientation.

In the present invention, a conventionally known ink layer is used as it is as the thermal transferable ink layer, and is not particularly limited. That is, the heat transferable ink layer used in the present invention is composed of a coloring agent, waxes, resins and additives such as a lubricant and a surfactant. Examples of the coloring agent include pigments and dyes such as carbon black, red bengala, lake red C, fast sky blue, benzidine yellow, phthalocyanine green, phthalocyanine blue, direct dyes, oil dyes, and basic dyes.

Examples of the waxes include carnauba wax, olicury wax, candelilla wax,
Examples include natural waxes such as Japan wax, cane wax, montan wax, ozokerite, microcrystalline wax, ceresin wax, and paraffin wax, and synthetic waxes such as Fischer-Tropsch wax, low molecular weight polyethylene, oxidized wax, and hydrogenated wax.

As the resins, for example, polyacrylic acid, polyacrylate, polymethacrylic acid,
Vinyl resins such as polymethacrylic acid ester, polyacrylamide, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl pyrrolidone, polyvinyl chloride, polyvinylidene chloride; ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxycellulose, hydroxypropyl cellulose,
Cellulose resins such as methyl cellulose and cellulose acetate; polyester resins; polyacetal resins; epoxy resins; terpene resins; rosin resins;

The additives include fatty acids, metal salts of fatty acids, esters of fatty acids, fatty acid amides, inorganic salts, nonionic surfactants, cationic surfactants, anionic surfactants, amphoteric surfactants, and the like. It can be used and is not particularly limited. The method for forming the thermal transfer ink layer is not limited at all.

The formation of the above-mentioned heat transferable ink layer can be carried out by the same method as that for the heat-resistant and slippery layer.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. Parts and% are based on weight.

Example 1 A coating solution for forming a heat-resistant and lubricating layer having the following composition was applied to one surface of a 4.5 μm-thick polyethylene terephthalate film with a wire bar, dried at 100 ° C. for 5 seconds, and dried at 0.3 μm.
A thick heat and lubricious layer was provided. Then, a coating liquid for forming a melt-type thermal transferable ink layer having the following composition is applied to the other surface of the polyester film so as to have an adhesion amount of 2.8 g / m ^2, and dried to form an ink layer. A recording medium was created. Heat resistant / slip layer Copolymer of reactive silicone (A in Table 1) and styrene (Reactive silicone / styrene = 3/7) 60 parts Copolymer of methyl acrylate having carboxyl group and vinyl acetate 40 parts MEK / cyclohexanone = 9/1, diluted to 4% Melt-type thermal transfer ink layer Carnauba wax 6 parts Paraffin wax 8 parts Carbon black 4 parts Toluene 82 parts

Example 2 A thermal transfer recording medium was prepared in the same manner as in Example 1, except that the coating composition for forming a heat-resistant and lubricious layer was changed to the one having the following composition. Heat resistant / slip layer Copolymer of reactive silicone (A in Table 1) and methyl methacrylate (reactive silicone / methyl methacrylate = 3/7) 60 parts Copolymerization of methyl acrylate having carboxyl group and vinyl acetate 40 parts of MEK / cyclohexanone = 9/1 diluted to 4%

Example 3 A thermal transfer recording medium was prepared in the same manner as in Example 1, except that the coating composition for forming a heat-resistant and slippery layer was changed to the one having the following composition. Heat resistant / slip layer Copolymer of reactive silicone (A in Table 1) and methyl methacrylate (reactive silicone / methyl methacrylate = 3/7) 60 parts Methacrylic acid having a carboxyl group and a methylol group, and vinyl acetate 40 parts of MEK / cyclohexanone = diluted to 4% with 9/1

Comparative Example 1 A thermal transfer recording medium was prepared in the same manner as in Example 1, except that the coating composition for forming a heat-resistant and lubricating layer was changed to the one having the following composition. Heat resistant / slip layer Copolymer of reactive silicone (A in Table 1) and methyl methacrylate (reactive silicone / methyl methacrylate = 3/7) 60 parts MEK / cyclohexanone = 9/1 diluted to 4%

Comparative Example 2 A thermal transfer recording medium was prepared in the same manner as in Example 1, except that the coating composition for forming a heat-resistant and lubricious layer was changed to the one having the following composition. Heat resistant / slip layer Copolymer of reactive silicone (A in Table 1) and methyl methacrylate (reactive silicone / methyl methacrylate = 3/7) 60 parts Methacrylic acid 40 parts MEK / cyclohexanone = 9/1 4 Diluted to%

The following performance evaluations were performed on the thermal transfer recording media obtained in Examples 1 to 3 and Comparative Examples 1 and 2. Table 4 shows the results. <Slipperiness> Evaluation criteria ◎: Very excellent, ○: Excellent, ×: Poor <Heat resistance> Evaluation criteria ◎: Very good, ○: Excellent, ×: Poor <Si migration resistance> Evaluation criteria ：: Very excellent, ：: Excellent, ×: Poor

[0037]

[Table 4]

[0038]

According to the thermal transfer recording medium of the present invention, a heat-resistant and lubricating layer comprising a copolymer of the reactive silicone and a vinyl monomer and a self-crosslinkable acrylic resin is provided as a back layer. As a result, not only lubricity but also heat resistance is excellent, sticking does not occur, and Si migration resistance is also excellent. In addition, a heating step for crosslinking is not required when an isocyanate crosslinking agent is used as in the case of a sticking prevention layer of a conventional thermal transfer recording medium, and a decrease in heat resistance caused by the remaining isocyanate crosslinking agent occurs. Absent.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazura Inamura 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Mitsuru Naruse 1-3-6 Nakamagome, Ota-ku, Tokyo Share Ricoh Co., Ltd. (72) Inventor Katsushi Shishido 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (Reference) 2H111 AA01 AA15 AA26 AA27 AA33 BA08 BA53 BA64 BA73

Claims (3)

[Claims] A thermal transfer ink layer is provided on an upper surface of a base material, and a copolymer of a reactive silicone and a vinyl monomer and a self-crosslinkable acrylic resin are provided on a lower surface of the base material which is in contact with a thermal head. A heat transfer recording medium characterized by comprising a heat-resistant / slippery layer composed of: 2. The thermal transfer recording medium according to claim 1, wherein the copolymer of the reactive silicone and the vinyl monomer is a copolymer of the reactive silicone and an acrylic monomer. . 3. The thermal transfer recording medium according to claim 1, wherein said self-crosslinkable acrylic resin is a polymer of methacrylic acid having a reactive group.