JPH05139063A - Film with roughened surface for thermal transfer medium - Google Patents

Abstract

PURPOSE:To provide a film with roughened face which can be used for delustered transfer or multiple transfer and exhibits excellent resistance to sticking to a thermal head and can be used as a substrate for a thermal transfer body. CONSTITUTION:The title film consists of a compsn. of 97-40 pts.wt. crystalline polyester resin and 3-60 pts.wt. (total of both components is 100 pts.wt.) maleimide polymer having a Tg of at least 10 deg.C higher than that of the crystalline polyester resin and has a mean roughness of the central face of the surface of at least 0.1mum. As an example, a compsn. of 80 pts.wt. PET and 20 pts.wt. maleimide copolymer is extruded through a T-die into a film, which is then uniaxially oriented by 3.5 times at 100 deg.C and heat-set at 230 deg.C to obtain a film with roughened face which has a mean roughness of the central face of the surface of 0.26mum and is excellent as a substrate for thermal transfer.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a special surface-roughened film used as a support for a thermal transfer medium. More specifically, the present invention relates to a roughened film that can be used for matte transfer or multiple transfers, and has excellent sticking resistance with a thermal head and that is used as a support for a thermal transfer medium.

[0002]

2. Description of the Related Art Conventionally, a heat-sensitive transfer medium in which a heat-meltable ink layer or a heat-sublimable ink layer is provided on one side of a smooth polyester resin film or a condenser paper is often used for heat-sensitive transfer recording. A method has been adopted in which the support is heated from the side opposite to that to transfer the ink to the transfer paper.

[0003]

SUMMARY OF THE INVENTION In this conventional method,
In the case of heat-melt type, the surface of the transferred ink is smooth and very glossy, and at first glance it looks beautiful, but on the other hand,
It may be difficult to see and cheap, and matte transfer has been newly demanded. Moreover, the conventional thermal transfer medium is often used only once, and there are many problems in terms of cost. On the other hand, since the conventional support is smooth, the slip property with the thermal head is poor, and so-called stick phenomenon easily occurs. In order to prevent this, the thermal head side of the support is often coated. In addition, an antistatic coat is often applied to prevent troubles due to static electricity. To solve these problems,
For example, JP-A-60-101083 discloses a method in which a mat layer is provided on a support film and an ink layer is laminated thereon. In addition, JP-A-60-10108
Japanese Patent Publication No. 4 discloses a method in which a film matted by sandblasting or kneading inorganic fine particles is used as a support. Further, JP-A-60-13594 describes a method of providing a sublimable ink layer on a roughened support having a thickness of 0.5 to 3 μm. In all of these, the cost was high because the film had to be roughened by a usual method, and the precision of the roughened surface was not good.

[0004]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventors have invented the following roughened film for a thermal transfer medium. That is, the present invention comprises 97 to 40 parts by weight of a crystalline polyester resin and 3 to 60 parts by weight of a maleimide copolymer having a glass transition temperature higher by at least 10 ° C. than the crystalline polyester resin (the total of the two is 100 parts by weight). And a center surface average roughness of the surface is 0.1 μm or more, and a roughened film for a thermal transfer medium. It also relates to a roughened film for a thermal transfer medium, which is laminated with a polyester resin film. Hereinafter, the present invention will be described in detail.

The crystalline polyester resin used in the present invention is a crystalline polyester resin containing an aromatic dicarboxylic acid residue and an aliphatic diol residue and / or an alicyclic diol residue as main constituent components. Representative examples of such aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid and the like. The aromatic ring of these aromatic dicarboxylic acids may be substituted with a halogen, an alkyl group or another substituent. Typical examples of the aliphatic diol or alicyclic diol include ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, cyclohexylene dimethanol and the like. Two or more kinds of these aromatic dicarboxylic acids, aliphatic diols and / or alicyclic diols can be mixed and used.

In the present invention, a particularly preferable crystalline polyester resin is polyethylene terephthalate (P
ET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and polycyclohexylene dimethylene terephthalate (PCT).

In the present invention, two or more kinds of such crystalline polyester resins may be mixed and used, or a crystalline polyester resin obtained by copolymerizing other components may be used. These crystalline polyester resins are produced by directly reacting an aromatic dicarboxylic acid with an aliphatic diol and / or an alicyclic diol, and also produce an alkyl ester of an aromatic dicarboxylic acid with an aliphatic diol and / or an alicyclic diol. It is produced by a method such as transesterification with a diol and then polycondensation, or polycondensation of a diglycol ester of an aromatic dicarboxylic acid.

The molecular weight of the crystalline polyester resin used in the present invention is not particularly limited as long as it has a film forming ability, but at 25 ° C. in a mixed solvent of phenol / tetrachloroethane = 1/1 (polymerization ratio). The measured intrinsic viscosity is preferably 0.4 (dl / g) or more. It is also within the scope of the present invention to add a cross-linking agent or provide a cross-linkable branch to cross-link with heat, light or radiation before or after stretching.

The maleimide-based copolymer used in the present invention comprises a maleimide-based monomer group, an aromatic vinyl monomer group, and, if necessary, an unsaturated dicarboxylic acid anhydride monomer group and other copolymers. It is composed of a polymerizable monomer group and has a glass transition temperature at least 10 ° C. higher than that of the crystalline polyester resin constituting the composition.
Representative examples of such maleimide-based monomers include maleimide, N-methylmaleimide, N-ethylmaleimide, N
-Propylmaleimide, N-hexylmaleimide, N-
Cyclohexylmaleimide, N-phenylmaleimide,
N-tolylmaleimide, N- (halogenated phenyl) maleimide, N- (alkylphenyl) maleimide, N-
(Nitrophenyl) maleimide, N- (hydroxyphenyl) maleimide, N-naphthylmaleimide, α-chloro-N-phenylmaleimide, α-methyl-N-phenylmaleimide and the like.

Typical examples of the aromatic vinyl monomer include styrene, α-methylstyrene, vinyltoluene, t-butylstyrene and halogenated styrene. Representative examples of unsaturated dicarboxylic acid anhydride monomers include maleic anhydride, methylmaleic anhydride, 1,2-dimethylmaleic anhydride, ethylmaleic anhydride, phenylmaleic anhydride and the like.

Acrylic monomers are examples of other copolymerizable monomers, and typical examples of these are methyl (meth) acrylate, ethyl (meth) acrylate,
Butyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, decyl (meth) acrylate, octadecyl (meth) acrylate, hydroxyethyl (meth) acrylate, methoxyethyl (meth) acrylate, glycidyl (meth) There are acrylates. Here, the methyl (meth) acrylate means methyl acrylate or methyl methacrylate.

The maleimide-based copolymer used in the present invention usually contains 30 to 50 mol% of maleimide monomer groups and 30 to 70 mol% of aromatic vinyl monomers. The saturated dicarboxylic acid anhydride monomer group is 0 mol% to 40 mol% and the other copolymerizable monomer group is 0 mol% to 50 mol%. When the maleimide-based monomer group is less than 30 mol% or the aromatic vinyl monomer group exceeds 70 mol%, the glass transition temperature of the maleimide-based copolymer is lowered, which is not preferable. Conversely, the maleimide-based monomer group is 50
When the amount of the aromatic vinyl monomer group is more than 30 mol% and more than 30 mol%, it is difficult to industrially produce a homogeneous copolymer. If the unsaturated dicarboxylic acid anhydride monomer group exceeds 40 mol% or the other copolymerizable monomer group exceeds 50 mol%, the glass transition temperature of the maleimide copolymer decreases. In addition, the thermal stability of the composition with the crystalline polyester resin decreases, which is not preferable.

The maleimide-type copolymer used in the present invention can be used by mixing two or more kinds of the respective copolymerization components, if necessary, and can also be copolymerized with other different monomers. It is possible.

The maleimide copolymer used in the present invention can be produced by a known radical polymerization method. As another method for producing a maleimide-based copolymer, a copolymer of an unsaturated dicarboxylic acid anhydride monomer and an aromatic vinyl monomer, and optionally another copolymerizable monomer An example is a method of reacting with an ammonia or a primary amine to imidize all or part of the acid anhydride group. For example, Japanese Patent Publication 61-26
According to the method exemplified in Japanese Patent Publication No. 938 or Japanese Patent Publication No. 62-8456, a maleimide copolymer can be produced by such imidization reaction of a polymer having an acid anhydride group in the molecule with an amine compound. it can.

The maleimide copolymer used in the present invention is at least 10 times as much as the crystalline polyester resin.
C., more preferably at least 20.degree. C. higher glass transition temperature. When the glass transition temperature of the maleimide-based copolymer is equal to or lower than that of the crystalline polyester resin, the degree of fine irregularities on the surface of the stretched film becomes insufficient.

The molecular weight of the maleimide copolymer used in the present invention is not particularly limited, and it gives a melt viscosity of at least 1/10 or more of the melt viscosity of the crystalline polyester resin at the temperature at which the composition is melt extruded. The molecular weight is sufficient.

The amounts of these components to be mixed are 97 to 40 parts by weight of the crystalline polyester resin, preferably 94 to 60 parts by weight, and 3 to 60 parts by weight of the maleimide copolymer, preferably 6 to 40 parts by weight. The combination is within the appropriate range.
If the amount of the maleimide copolymer is less than these ranges, the surface is too smooth and unsuitable as a rough surface film.If it exceeds these ranges, the mechanical properties are inferior and stretching is impossible. In some cases.

[0018]

The maleimide copolymer of the present invention is microscopically dispersed in a crystalline polyester resin to form small irregularities on the film surface, and as a result, a roughened film having uniform irregularities can be obtained.

It is also possible to add an inorganic additive to the roughened film of the present invention. The amount of the inorganic additive is 1 in total of the crystalline polyester resin and the maleimide copolymer.
0.3 to 10 parts by weight, preferably 0.
5 to 7 parts by weight is suitable. If it is less than this amount, it is too small to have the effect of addition, and if it is more than 10 parts by weight, it is no different from the conventional inorganic matte film, and the characteristics of the present invention are lost. The average particle size of the inorganic particles is 0.01 to 3
0 μm is preferable. The material of the inorganic particles is SiO ₂ ,
TiO ₂ , CaCO ₃ , BaSO ₄ , TiO ₄ , Al ₂ O ₃ ,
Kaolin, mica, talc and the like are preferable, but not limited thereto.

The surface-roughened film of the present invention has relatively smooth surface irregularities in the unstretched state, but it exhibits irregularities when stretched. When used as a surface-roughened film for a thermal transfer support, the stretching ratio is usually 1.5 times or more, preferably 2 times or more in at least one direction. Further, a better film can be obtained by biaxially stretching in the longitudinal and lateral directions. Also in this case, it is preferable to perform biaxial stretching at least 1.5 times in the length and width directions.

The surface-roughened film of the present invention may be used as a single layer, but may be formed as a multi-layer when higher strength and cost reduction are intended. That is, in this case, a roughened film layer is provided on one side or both sides of the polyester resin film, and the roughened film layer is a film stretched at least 1.5 times in at least one direction. In this case, the mechanical properties are retained by the polyester resin layer, and since the roughened film layer is used only as the surface layer, it is inexpensive. As the polyester resin of the polyester resin film, the same resin as the crystalline polyester resin is exemplified. The method for stretching the film is not particularly limited, but uniaxial stretching, sequential biaxial stretching, simultaneous biaxial stretching and the like can be applied. There are also two stretching devices used for this.
Le type uniaxial stretching machine A tender type or tuber type simultaneous biaxial stretching machine can be applied, but the invention is not particularly limited thereto. Further, in this case, the stretching temperature of the film is better in the matting property in a temperature range higher than the usual stretching temperature of the polyester resin film, and is preferably 90 ° C. or higher and 125 ° C. or lower.

The surface roughness of the surface-roughened film is 0.1 μm or more, preferably 0.2 to 1.0 μm in terms of average roughness of the center surface.
Is appropriate. The center plane average roughness represents the average distance from the center plane to the peaks or troughs with the center plane being the plane where the sum of the peaks and the sum of the troughs of the film surface are equal. The thickness of the roughened film is 10 to 1.5 μm,
It is preferably 6 to 2.5 μm.

The coating of the ink layer on these roughened films is mainly carried out by a hot melt coating method, a gravure coating method, a reverse coating method or the like. When the ink is a hot-melt type, a mixture of pigments and waxes or a polyester resin, ethylene / vinyl acetate resin is suitable, and when the ink is a thermal sublimation type, a sublimable dye and a polyolefin resin, a polyester resin, vinyl acetate. A mixture of resins having a low melting point or a low softening point such as a system resin is suitable, but is not particularly limited thereto.

[0024]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Example 1 Polyethylene terephthalate resin (1600 poise (280 ° C., 1000 se)
c ^-1 )) 80 parts by weight and maleimide-based copolymer (Denka IP MSN: Denka IP MSN: 9000 poise (280 ° C, 1000 sec ^-1 ), glass transition temperature 19)
20 parts by weight (7 ° C.) were mixed by heating with a twin-screw extruder to form chips. Next, these chips were put in a 50 mm extruder and the resin temperature was changed to 2
It was melted at 80 ° C. and extruded from a T die to form a film having a thickness of 50 μm. This unstretched film was uniaxially stretched 3.5 times at 100 ° C. by a test stretching machine and heat set at 230 ° C. The center plane surface roughness measured by a three-dimensional surface roughness meter manufactured by Kosaka Laboratory was 0.26 μm. A mixture of 10 parts by weight of paraffin wax, 30 parts by weight of carnauba wax, 40 parts by weight of ester wax, and 20 parts by weight of pigment was hot-melt coated on this stretched film to give a thickness of 4 μm.
m ink layer was provided. The laminated film was micro-slit, and thermal transfer was performed using a thermal printer (“Picoward” manufactured by Brother Industries, Ltd.).
The value was 24 when measured, and good matte printing was obtained.

Example 2 Using a coextrusion film forming apparatus equipped with three 40 mm extruders, a polyethylene terephthalate layer having a thickness of 30 μm at the center and 10 μm at each end were mixed resin having the same composition as in Example 1. An unstretched film was made that was laminated in layers. This unstretched film was stretched 3.3 times in the longitudinal direction at 90 ° C. by a roll type longitudinal stretching machine, and then 10 times.
At 0 ° C., a tenter-type stretching machine was used to stretch the film in the transverse direction by 3.4 times and immediately heat-set at 230 ° C. The center plane average roughness of the stretched film was 0.81 μm. A mixture of 10 parts by weight of paraffin wax, 30 parts by weight of carnauba wax, 40 parts by weight of ester wax, and 20 parts by weight of pigment was hot-melt coated on the stretched film to give a thickness of 4
A μm ink was provided. The laminated film was microslit, and thermal transfer was performed using a thermal printer ("Picoward" manufactured by Brother Industries, Ltd.). The gloss of the surface of the transferred ink is measured by a gloss meter (Murakami Color Research Laboratory, incident angle 6
It was 19 when measured at 0 °), and good matte printing was obtained.

[0027]

EFFECT OF THE INVENTION Since the present invention is a roughened film comprising a composition of a crystalline polyester resin and a maleimide copolymer used as a support for a thermal transfer medium, the roughened film alone can be used as a thermal transfer medium. Or a polyester resin film laminated on at least one surface of the polyester resin film for use as a heat-sensitive transfer medium, which can be used for matte transfer or multiple transfer, and is a stick with a thermal head. It also has excellent prevention properties.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location B44C 1/17 E 9134-3K C08J 5/18 CFD 9267-4F C08L 35/00 LJW 7921-4J 67 / 02 LPK 8933-4J // B29K 67:00 4F 79:00 B29L 7:00 4F 9:00 4F C08L 67:00 (72) Inventor Yoshiaki Kozuka 23 Uji Kozakura, Uji City, Kyoto Unitika Stock Company Central Research (72) Inventor Hiroyuki Matsuda 23 Uji Kozakura, Uji City, Kyoto Prefecture Unitika Ltd. Central Research Laboratory

Claims (2)

[Claims] 1. 97 to 40 parts by weight of a crystalline polyester resin, and at least 10 parts by weight of the crystalline polyester resin.
Maleimide copolymer 3 having a glass transition temperature higher by ℃
A surface-roughened film for a heat-sensitive transfer medium, which is composed of a composition of -60 parts by weight (total of 100 parts by weight of both) and has a center surface average roughness of 0.1 µm or more. 2. A surface-roughened film for a heat-sensitive transfer medium, characterized in that the surface-roughened film comprising the composition according to claim 1 is laminated on one side or both sides of a polyester resin film. ..