JP2001315446A - Thermal transfer film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low cost thermal transfer film, which has favorable heat resistance, chemical resistance and flexibility and the elongation of which is small. SOLUTION: In the thermal transfer film having a layer made of a thermally transferable ink and a base material as its constitutional components, the base material is a film made of a liquid crystalline polymer, which shows an optical anisotropy at its melting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inexpensive thermal transfer film having good heat resistance, chemical resistance, flexibility, etc., low elongation and low cost.

[0002]

2. Description of the Related Art In recent years, a thermal transfer printing system has been applied to printers, copiers, facsimile machines and the like. In this method, a heating head is pressed from the base film side of a heat transfer film having a base film such as a heat-resistant plastic film and a heat transferable ink layer as components, and the ink in the pressed portion is a paper as a receiver. This method is widely used in the market because it has good storage stability of the record, is excellent in prevention of falsification of the record, and is easy to maintain.
However, at present, conventional thermal transfer films do not sufficiently satisfy the demands from the market. For example,
Thermal transfer film based on a film such as polyethylene terephthalate,
In some cases, the heat resistance of polyethylene terephthalate was not sufficient. In addition, there are cases where the chemical resistance of the thermal transfer film when subjected to a solvent treatment or the flexibility of the thermal transfer film is insufficient. In addition, when the thermal transfer film is used at a high speed, problems such as stretching of the film have been pointed out by the market. On the other hand, thermal transfer films based on films such as polyimide, heat resistance and chemical resistance,
Good but very expensive. To cope with these problems, for example, JP-A-63-95991 describes a thermal transfer film having a base film of a crosslinked polyester. However, transfer at a high temperature in the case of high-speed transfer, which is required in recent years, sometimes has insufficient heat resistance. Also, JP-A-2-4575
Japanese Patent Application Laid-Open Publication No. HEI 9-265, describes a thermal transfer film composed of an oriented liquid crystal film. However, there has not been anything that satisfies the market requirements, such as insufficient flexibility and difficult handling.

[0003]

Under such circumstances, an object of the present invention is to provide an inexpensive thermal transfer film which has good heat resistance, chemical resistance and flexibility, has small elongation, and is inexpensive.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to solve such a problem and arrived at the present invention. That is, the present invention is characterized in that, in a thermal transfer film comprising a layer composed of a heat transferable ink and a substrate, the substrate is a film composed of a liquid crystalline polymer exhibiting optical anisotropy when melted. The present invention relates to a thermal transfer film.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. Various liquid crystalline polymers exhibiting optical anisotropy when melted are known, and examples thereof include wholly aromatic polyesters, polyimides, polyesteramides, and resin compositions containing them. In the present invention, the liquid crystalline polymer is preferably a liquid crystalline polyester or a composition containing the liquid crystalline polyester. In view of the moldability and the performance of the obtained film, (A) the liquid crystalline polyester is continuously used in the present invention. It is more preferable to use a liquid crystal polyester resin composition in which (B) a copolymer having a functional group reactive with the liquid crystal polyester is used as a dispersed phase.

[0006] The liquid crystal polyester referred to here is a polyester called a thermotropic liquid crystal polymer.
Specifically, (1) a combination of an aromatic dicarboxylic acid, an aromatic diol and an aromatic hydroxycarboxylic acid, (2) a combination of different aromatic hydroxycarboxylic acids, and (3) an aromatic hydroxycarboxylic acid Consisting of a combination of an aromatic dicarboxylic acid and a nucleus-substituted aromatic diol, (4)
Examples thereof include those obtained by reacting an aromatic hydroxycarboxylic acid with a polyester such as polyethylene terephthalate and the like, which form an anisotropic melt at a temperature of 400 ° C. or lower. In addition, in place of these aromatic dicarboxylic acids, aromatic diols, and aromatic hydroxycarboxylic acids, ester-forming derivatives thereof may be used.

The repeating structural units of the liquid crystal polyester include the following repeating structural units derived from an aromatic dicarboxylic acid, the following repeating structural units derived from an aromatic diol,
Examples of the repeating structural unit derived from an aromatic hydroxycarboxylic acid include, but are not limited to, these.

A repeating structural unit derived from an aromatic dicarboxylic acid:

[0009]

A repeating structural unit derived from an aromatic diol:

[0011]

A repeating structural unit derived from an aromatic hydroxycarboxylic acid:

A liquid crystal polyester which is particularly preferable from the balance of heat resistance, mechanical properties and workability is And more preferably at least 30 mol% of the entire repeating unit.
The above is included. Specifically, the combination of repeating structural units is preferably any one of the following (I) to (VI).

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

The production methods of the liquid crystal polyesters (I) to (VI) are described, for example, in JP-B-47-47870, JP-B-63-3888, JP-B-63-3891, and JP-B-56-18016. JP-A-2-515
No. 23, and the like. Of these, a combination of (I), (II) or (IV) is preferable, and a combination of (I) or (II) is more preferable.

In the field in which high heat resistance is required in the liquid crystal polyester resin composition of the present invention, the liquid crystal polyester of the component (A) contains 30 to 80 mol% of the following repeating unit (a '), A liquid crystal polyester in which b ′) is 0 to 10 mol%, the repeating unit (c ′) is 10 to 25 mol%, and the repeating unit (d ′) is 10 to 35 mol% is preferably used.

[0022] (In the formula, Ar is a divalent aromatic group.)

In the liquid crystal polyester of the present invention, the fields in which easy disposal such as incineration after use is required from the viewpoint of environmental problems and the like are included in the preferred combinations of the fields required so far. In particular, a liquid crystal polyester made of a combination consisting of only carbon, hydrogen, and oxygen is particularly preferably used.

The component (B) used in the liquid crystal polyester resin composition of the present invention is a copolymer having a functional group reactive with the liquid crystal polyester. The functional group reactive with the liquid crystal polyester is not particularly limited as long as it has reactivity with the liquid crystal polyester, and specific examples include an oxazolyl group, an epoxy group, and an amino group. Preferably, it is an epoxy group. The epoxy group or the like may be present as a part of another functional group, and such an example includes a glycidyl group.

In the copolymer (B), the method for introducing such a functional group into the copolymer is not particularly limited, and it can be carried out by a known method. For example, at the stage of synthesizing the copolymer, it is possible to introduce the monomer having the functional group by copolymerization, or it is also possible to graft copolymerize the monomer having the functional group to the copolymer. It is.

As a monomer having a functional group reactive with the liquid crystal polyester, and particularly as a monomer having a glycidyl group, unsaturated glycidyl carboxylate and / or unsaturated glycidyl ether are preferably used.

The unsaturated carboxylic acid glycidyl ester is
Preferably a general formula (R is a hydrocarbon group having an ethylenically unsaturated bond and having 2 to 13 carbon atoms.) Also,
The unsaturated glycidyl ether preferably has the general formula (R ′ has 2 to 18 carbon atoms having an ethylenically unsaturated bond.
A hydrocarbon group, X is -CH ₂ -O- or It is. ).

Specifically, examples of the unsaturated carboxylic acid glycidyl ester include glycidyl acrylate, glycidyl methacrylate, itaconic acid diglycidyl ester, butenetricarboxylic acid triglycidyl ester,
Glycidyl p-styrenecarboxylate and the like can be mentioned. As unsaturated glycidyl ethers,
For example, vinyl glycidyl ether, allyl glycidyl ether, 2-methylallyl glycidyl ether, methacryl glycidyl ether, styrene-p-glycidyl ether and the like can be mentioned.

The copolymer (B) having a functional group reactive with the liquid crystal polyester preferably contains 0.1 to 30% by weight of an unsaturated carboxylic acid glycidyl ester unit and / or an unsaturated glycidyl ether unit. It is a copolymer containing.

The copolymer (B) having a functional group reactive with the liquid crystal polyester may be a thermoplastic resin or a rubber, or a mixture of a thermoplastic resin and a rubber. You may. A rubber having excellent thermal stability and flexibility of a molded product such as a film or sheet obtained by using the liquid crystal polyester resin composition is more preferable.

More preferably, the copolymer (B) having a functional group reactive with the liquid crystal polyester is
A copolymer having a heat of fusion of crystal of less than 3 J / g. The copolymer (B) preferably has a Mooney viscosity of 3 to 70, more preferably 3 to 30 and more preferably 4 to 30.
25 are particularly preferred. The Mooney viscosity here refers to a value measured using a large rotor at 100 ° C. according to JIS K6300. Outside these ranges, the thermal stability and flexibility of the composition may be undesirably reduced.

The rubber mentioned here corresponds to a polymer substance having rubber elasticity at room temperature according to a new edition of Polymer Dictionary (edited by the Society of Polymer Science, published in 1988, Asakura Shoten).
Specific examples thereof include natural rubber, butadiene polymer, butadiene-styrene copolymer (including random copolymer, block copolymer (including SEBS rubber or SBS rubber, etc.), and graft copolymer), or The hydrogenated product, isoprene polymer, chlorobutadiene polymer, butadiene-acrylonitrile copolymer, isobutylene polymer, isobutylene-butadiene copolymer rubber,
Isobutylene-isoprene copolymer, acrylate-ethylene copolymer rubber, ethylene-propylene copolymer rubber, ethylene-butene copolymer rubber, ethylene-propylene-styrene copolymer rubber, styrene-isoprene copolymer Rubber, styrene-butylene copolymer, styrene-ethylene-propylene copolymer rubber, perfluoro rubber, fluoro rubber, chloroprene rubber, butyl rubber, silicone rubber, ethylene-propylene-non-conjugated diene copolymer rubber, thiol rubber, polysulfide Examples include rubber, polyurethane rubber, polyether rubber (for example, polypropylene oxide, etc.), epichlorohydrin rubber, polyester elastomer, polyamide elastomer, and the like. Among them, an acrylate-ethylene copolymer is preferably used, and a (meth) acrylate-ethylene copolymer rubber is more preferred.

These rubber-like substances are produced by any production method (eg, emulsion polymerization method, solution polymerization method, etc.) and any catalyst (eg, peroxide, trialkylaluminum, lithium halide, nickel-based catalyst, etc.). It may be something.

In the present invention, the copolymer (B)
Is a rubber having a functional group reactive with the liquid crystal polyester in the rubber as described above. In such a rubber, a method for introducing a functional group reactive with the liquid crystal polyester into the rubber is not particularly limited, and can be performed by a known method. For example, it is possible to introduce the monomer having the functional group by copolymerization at the stage of synthesizing the rubber, or it is also possible to graft copolymerize the monomer having the functional group to the rubber.

As specific examples of the copolymer (B) having a functional group reactive with the liquid crystal polyester, rubbers having an epoxy group include (meth) acrylate-ethylene- (unsaturated glycidyl carboxylate and And / or unsaturated glycidyl ether) copolymer rubber.

Here, the (meth) acrylic acid ester is
An ester obtained from acrylic acid or methacrylic acid and an alcohol. Alcohols have 1 carbon atom
~ 8 alcohols are preferred. Specific examples of (meth) acrylates include methyl acrylate, methyl methacrylate, n-butyl acrylate, n-butyl methacrylate, tert-butyl acrylate, ter
Examples thereof include t-butyl methacrylate, 2-ethylhexyl acrylate, and 2-ethylhexyl methacrylate. As the (meth) acrylic acid ester, one kind thereof may be used alone, or two or more kinds may be used in combination.

The (meth) acrylate unit is preferably more than 40% by weight and less than 97% by weight, more preferably 45 to 70% by weight, and the ethylene unit is 3% by weight to 50% by weight.
%, More preferably 10 to 49% by weight, and 0.1 to 30% by weight, more preferably 0.5 to 20% by weight, of unsaturated carboxylic acid glycidyl ether units and / or unsaturated glycidyl ether units. If the ratio is outside the above range, the resulting molded product such as a film or sheet may have insufficient thermal stability and mechanical properties, which is not preferable.

The copolymer rubber can be produced by a conventional method, for example, bulk polymerization, emulsion polymerization, solution polymerization or the like using a free radical initiator. Typical polymerization methods are described in JP-B-46-45085 and JP-B-6-45085.
No. 1-127709, pressure of 500 k in the presence of a polymerization initiator generating free radicals
g / cm ² or more and a temperature of 40 to 300 ° C.

Other rubbers that can be used in the copolymer (B) of the present invention include acrylic rubber having a functional group reactive with liquid crystal polyester, and vinyl aromatic having a functional group reactive with liquid crystal polyester. Hydrocarbon compounds
A conjugated diene compound block copolymer rubber can also be exemplified.

The acrylic rubber mentioned here is preferably represented by the general formula (1) (In the formula, R ¹ represents an alkyl group having 1 to 18 carbon atoms or a cyanoalkyl group.), A general formula (2) (Wherein, R ² is an alkylene group having 1 to 12 carbon atoms, R ³
Represents an alkyl group having 1 to 12 carbon atoms. ) And general formula (3) (Wherein, R ⁴ is a hydrogen atom or a methyl group, R ^{5 is} an alkylene group having 3 to 30 carbon atoms, R ⁶ is an alkyl group having 1 to 20 carbon atoms or a derivative thereof, and n is an integer of 1 to 20) .)) At least one monomer selected from the compounds represented by formula (1).

Specific examples of the alkyl acrylate represented by the general formula (1) include, for example, methyl acrylate, ethyl acrylate, propyl acrylate,
Examples thereof include butyl acrylate, pentyl acrylate, hexyl acrylate, actyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, dodecyl acrylate, and cyanoethyl acrylate.

The alkoxyalkyl acrylate represented by the general formula (2) includes, for example, methoxyethyl acrylate, ethoxyethyl acrylate, butoxyethyl acrylate, ethoxypropyl acrylate and the like. One or more of these can be used as the main component of the acrylic rubber.

As a constituent of the acrylic rubber, an unsaturated monomer copolymerizable with at least one monomer selected from the compounds represented by the above general formulas (1) to (3), if necessary. Can be used. Examples of such unsaturated monomers include styrene, α-methylstyrene,
Acrylonitrile, halogenated styrene, methacrylonitrile, acrylamide, methacrylamide, vinylnaphthalene, N-methylolacrylamide, vinyl acetate, vinyl chloride, vinylidene chloride, benzyl acrylate, methacrylic acid, itaconic acid, fumaric acid, maleic acid, and the like. .

The preferred constituent ratio of the acrylic rubber having a functional group reactive with the liquid crystal polyester is at least one monomer selected from the compounds represented by the above general formulas (1) to (3). 0 to 99.9% by weight, 0.1 to 30.0% by weight of unsaturated carboxylic acid glycidyl ester and / or unsaturated glycidyl ether, selected from the compounds represented by the above general formulas (1) to (3). Unsaturated monomer copolymerizable with at least one monomer 0.0
３30.0% by weight. When the constituent ratio of the acrylic rubber is within the above range, heat resistance and impact resistance of the composition,
The molding processability is good and preferable.

The method for producing the acrylic rubber is not particularly limited, and examples thereof include JP-A-59-113010,
JP-A-62-64809, JP-A-3-16000
No. 8, or a known polymerization method described in WO95 / 04764 or the like, which can be produced by emulsion polymerization, suspension polymerization, solution polymerization or bulk polymerization in the presence of a radical initiator. it can.

The vinyl aromatic hydrocarbon compound-conjugated diene compound block copolymer rubber having a functional group reactive with the liquid crystal polyester is preferably (a)
Epoxidation of a rubber obtained by epoxidizing a block copolymer consisting of a sequence mainly composed of a vinyl aromatic hydrocarbon compound and (b) a sequence mainly composed of a conjugated diene compound, or epoxidation of a hydrogenated product of the block copolymer This is the rubber obtained.

The vinyl aromatic hydrocarbon compound-conjugated diene compound block copolymer or its hydrogenated product can be produced by a known method, for example, Japanese Patent Publication No. 40-23.
798 and JP-A-59-133203.

As the aromatic hydrocarbon compound, for example,
Styrene, vinyltoluene, divinylbenzene, α-methylstyrene, p-methylstyrene, vinylnaphthalene and the like can be mentioned, among which styrene is preferable.
Examples of the conjugated diene compound include butadiene, isoprene, pyrrylene, 1,3-pentadiene, 3-butyl-1,3-octadiene and the like, butadiene or isoprene is preferred.

The rubber used as the copolymer (B) is preferably (meth) acrylate-ethylene-
(Unsaturated carboxylic acid glycidyl ester and / or unsaturated glycidyl ether) copolymer rubber is used.

The rubber used as the copolymer (B) can be vulcanized as required and used as a vulcanized rubber. The above (meth) acrylic acid ester-ethylene-
Vulcanization of the (unsaturated carboxylic acid glycidyl ester and / or unsaturated glycidyl ether) copolymer rubber is achieved by using a polyfunctional organic acid, a polyfunctional amine compound, an imidazole compound, and the like. It is not limited.

Further, as a specific example of the copolymer (B) having a functional group reactive with the liquid crystal polyester, the thermoplastic resin having an epoxy group includes (a) 50 to 99% by weight of ethylene units, (b) ) 0.1 to 30% by weight, preferably 0.5 to 20% by weight of unsaturated carboxylic acid glycidyl ester units and / or unsaturated glycidyl ether units.
% By weight, and (c) an epoxy group-containing ethylene copolymer having an ethylenically unsaturated ester compound unit of 0 to 50% by weight.

Examples of the ethylenically unsaturated ester compound (c) include vinyl carboxylate such as vinyl acetate, vinyl propionate, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate and butyl methacrylate. Esters, α, β-unsaturated carboxylic acid alkyl esters, and the like. Particularly, vinyl acetate, methyl acrylate and ethyl acrylate are preferred.

Specific examples of the epoxy group-containing ethylene copolymer include, for example, a copolymer composed of ethylene units and glycidyl methacrylate units, a copolymer composed of ethylene units and glycidyl methacrylate units, and a methyl acrylate unit. Copolymers composed of glycidyl methacrylate units and ethyl acrylate units, and copolymers composed of ethylene units, glycidyl methacrylate units and vinyl acetate units are exemplified.

The melt index of the epoxy group-containing ethylene copolymer (hereinafter sometimes referred to as MFR. JI
SK6760, 190 ° C., 2.16 kg load) is preferably 0.5 to 100 F-10 minutes, more preferably 2 to 100 F-10 minutes.
５０50 F-10 minutes. The melt index may be outside this range, but the melt index is 100
If it exceeds F-10 minutes, it is not preferable in view of the mechanical properties of the composition, and if it is less than 0.5F-10 minutes, the compatibility with the liquid crystal polyester of the component (A) is inferior.

[0055] Also, the epoxy group-containing ethylene copolymer is preferably in the range stiffness modulus of 10~1300kg / cm ^2, further preferably from 20~1100kg / cm ^2. If the flexural rigidity is outside this range, the molding processability and mechanical properties of the composition may be insufficient, which is not preferable.

The epoxy group-containing ethylene copolymer is usually prepared by reacting an unsaturated epoxy compound and ethylene in the presence of a radical generator at 500 to 4000 atm and 100 to 300 ° C. in the presence or absence of a suitable solvent or chain transfer agent. It is produced by a high-pressure radical polymerization method in which copolymerization is carried out in the presence. It can also be produced by a method in which an unsaturated epoxy compound and a radical generator are mixed with polyethylene and melt-grafted and copolymerized in an extruder.

The liquid crystal polyester resin composition, which is a preferred specific example of the liquid crystal polymer used in the present invention, is a copolymer having (A) a liquid crystal polyester as a continuous phase and (B) a functional group reactive with the liquid crystal polyester. Is a resin composition having a dispersed phase. If the liquid crystal polyester is not a continuous phase, the film using the liquid crystal polyester resin composition, heat resistance, chemical resistance, etc. are reduced,
Not preferred.

The details of the mechanism of the resin composition of such a copolymer having a functional group and the liquid crystal polyester are not clear, but the composition between the component (A) and the component (B) is not clear. It is considered that a reaction occurs, and the component (A) forms a continuous phase, and the component (B) is finely dispersed, thereby improving the moldability of the composition.

One embodiment of the liquid crystal polyester resin composition comprises (A) 56.0 to 99.9 liquid crystal polyester.
44% by weight, preferably 65.0 to 99.9% by weight, more preferably 70 to 98% by weight, and (B) a copolymer having a functional group reactive with a liquid crystal polyester.
The resin composition contains 0 to 0.1% by weight, preferably 35.0 to 0.1% by weight, and more preferably 30 to 2% by weight. If the content of the component (A) is less than 56.0% by weight, the heat resistance and chemical resistance of a film obtained from the composition may be undesirably reduced. Component (A)
If it exceeds 99.9% by weight, the molding processability of the composition may be reduced, and the price is also undesirably high.

As a method for producing such a liquid crystal polyester resin composition, a known method can be used. For example, there is a method in which each component is mixed in a solution state and the solvent is evaporated or precipitated in the solvent. From an industrial point of view, a method of kneading each component in a molten state is preferred. For the melt kneading, kneading apparatuses such as a single-screw or twin-screw extruder and various kneaders which are generally used can be used. In particular, a biaxial high kneader is preferred. At the time of melt-kneading, the cylinder set temperature of the kneading device is 200 to 3
The temperature is preferably in the range of 60 ° C, more preferably 230 to 3
50 ° C.

At the time of kneading, the respective components may be previously mixed uniformly using a device such as a tumbler or a Henschel mixer, or if necessary, the mixing may be omitted, and each component may be separately supplied to the kneading device. Methods can also be used.

In the liquid crystalline polymer used in the present invention, if necessary, an antistatic agent, an organic filler, an inorganic filler, an antioxidant, a heat stabilizer, a light stabilizer, a flame retardant, a lubricant,
Various additives such as inorganic or organic colorants, rust inhibitors, cross-linking agents, foaming agents, fluorescent agents, surface smoothing agents, surface gloss improvers, release improvers such as fluororesins, etc. during or after the manufacturing process It can be added in the processing step.

As the film comprising the liquid crystalline polymer used in the present invention, such a liquid crystalline polymer may be used, for example,
T-die method for extruding and winding the molten resin from the die, extruding the molten resin into a cylindrical shape from an extruder equipped with an annular die,
The film or sheet obtained by the inflation film forming method cooled and wound, the film or sheet obtained by the hot press method or the solvent casting method, or the sheet obtained by the injection molding method or the extrusion method is further uniaxially stretched or biaxially stretched. A film or sheet obtained by stretching can also be used. In the case of injection molding, extrusion molding, etc.,
Without going through a kneading step in advance, a film or a sheet can be obtained by dry blending and melt-molding the pellets of the components at the time of molding.

In the T-die method, a uniaxially stretched film or a biaxially stretched film obtained by winding a molten resin extruded through a T-die while stretching it in the machine direction (longitudinal direction) is preferably used.

The setting conditions of the extruder at the time of forming the uniaxially stretched film can be appropriately set according to the composition of the composition. The cylinder setting temperature is preferably in the range of 200 to 360 ° C., and more preferably in the range of 230 to 350 ° C. Is more preferred.
If the ratio is outside this range, thermal decomposition of the composition may occur or film formation may be difficult, which is not preferable.

The slit interval of the T die is 0.2 to 2.0.
mm is preferable, and 0.2 to 1.2 mm is more preferable.
The draft ratio of the uniaxially stretched film is preferably in the range of 1.1 to 40, more preferably 10 to 40, and particularly preferably 15 to 35.

Here, the draft ratio is a value obtained by dividing the cross-sectional area of the T-die slit by the cross-sectional area of the film perpendicular to the longitudinal direction. If the draft ratio is less than 1.1, the film strength is insufficient, and if the draft ratio exceeds 45, the surface smoothness of the film may be insufficient, which is not preferable. The draft ratio can be set by controlling the setting conditions of the extruder, the winding speed, and the like.

For the biaxially stretched film, the same extruder setting conditions as those for forming the uniaxially stretched film, that is, the cylinder set temperature is preferably in the range of 200 to 360 ° C., more preferably 230 to 350 ° C. The composition is melt-extruded at a slit interval of preferably 0.2 to 1.2 mm, and the melt sheet extruded from the T-die is simultaneously stretched in the longitudinal direction and the direction perpendicular to the longitudinal direction (lateral direction). First, the melt sheet extruded from the T-die is stretched in the longitudinal direction, and then the stretched sheet is stretched in a transverse direction from the tenter at a high temperature of 100 to 300 ° C. in the same step. Can be

When a biaxially stretched film is obtained, the stretching ratio is preferably in the range of 1.2 to 20 times in the longitudinal direction and 1.2 to 20 times in the transverse direction. If the stretching ratio is out of the above range, the strength of the composition film may be insufficient, or it may be difficult to obtain a film having a uniform thickness, which is not preferable.

An inflation film obtained by forming a melt sheet extruded from a cylindrical die by inflation is also preferably used.

That is, the liquid crystal polyester resin composition obtained by the above method was supplied to a melt kneading extruder equipped with a die having an annular slit, and was set at a cylinder set temperature of 20.
The melt-kneading is performed at 0 to 360 ° C, preferably 230 to 350 ° C, and the molten resin is extruded upward or downward from the annular slit of the extruder. The annular slit interval is usually 0.1 to 5 mm, preferably 0.2 to 2 m
m, the diameter of the annular slit is usually 20 to 1000 mm,
Preferably it is 25 to 600 mm.

Draft is applied to the melt-extruded molten resin film in the longitudinal direction (MD), and air or an inert gas, for example, nitrogen gas, is blown from the inside of the cylindrical film, so that the transverse direction perpendicular to the longitudinal direction is obtained. The film is expanded and stretched in the direction (TD).

In inflation molding (film formation),
The preferred blow ratio is 1.5 to 10, and the preferred MD stretching ratio is 1.5 to 45. If the setting conditions during the inflation film formation are outside the above range, it may be difficult to obtain a high-strength liquid crystal polyester resin composition film having a uniform thickness and no wrinkles, which is not preferable. The expanded film is usually air-cooled or water-cooled on its circumference, and then passed through a nip roll and taken up. Upon inflation film formation, conditions can be selected according to the composition of the liquid crystal polyester resin composition such that the cylindrical melt film expands to a uniform thickness and a smooth surface state.

The thickness of the film composed of the liquid crystalline polymer in the present invention is not particularly limited, but is preferably 2 to 2
It is 5 μm, more preferably 2 to 15 μm, even more preferably 2 to 10 μm.

In the present invention, the surface of the film made of a liquid crystalline polymer can be subjected to a surface treatment in advance. Such surface treatment methods include, for example, corona discharge treatment, plasma treatment, flame treatment, sputtering treatment,
Solvent treatment, ultraviolet treatment, polishing treatment, infrared treatment, ozone treatment and the like can be mentioned.

The thermal transfer film of the present invention comprises a layer composed of a thermal transferable ink and a film composed of the above liquid crystalline polymer as a substrate. The heat transferable ink as used herein is a layer composed of a heat-meltable ink and / or a heat-sublimable ink, and the ink is not particularly limited. However, the colorant alone or the colorant and its binder Consists of As the colorant, for example, a pigment such as carbon black or a dye such as a heat sublimable dye is used.

Examples of the binders for the pigments and dyes as the above colorants include polyester resins, butyral resins such as ethylene-vinyl acetate copolymer and polyvinyl butyral, polyamide resins, acrylic resins, cellulose acetate butyrate resins, and the like. , Wax such as wood wax and beeswax. The above colorants and binders may be used alone or in combination of two or more. The layer made of such a heat transferable ink may be formed by hot-melt coating the ink on a substrate of a film made of the above liquid crystalline polymer, or by gravure coating a liquid obtained by dispersing the hot ink in a solvent, or reversely. It is formed by a method such as coating. The thickness of the heat transferable ink layer may be any thickness required depending on the application. The form when using the thermal transfer film in the present invention is not particularly limited, and for example, any form of a ribbon, a continuous film, a cut film such as an A4 plate, or a roll formed by winding a cut film. Also used.

[0078]

The present invention will be described in more detail with reference to the following examples. (1) Liquid crystal polyester of component (A) (i) 8.3 kg (60 mol) of p-acetoxybenzoic acid, 2.49 kg (15 mol) of terephthalic acid, 0.83 kg (5 mol) of isophthalic acid and 4,4 ′ 5.45 kg (20.2 mol) of diacetoxydiphenyl was charged into a polymerization tank having a comb-shaped stirring blade, the temperature was increased while stirring under a nitrogen gas atmosphere, and polymerization was performed at 330 ° C. for 1 hour. During this time, polymerization was carried out under strong stirring while liquefying and collecting and removing acetic acid gas produced as a by-product in a cooling tube. Thereafter, the system was gradually cooled, and the polymer obtained at 200 ° C. was taken out of the system. The obtained polymer was pulverized with a hammer mill manufactured by Hosokawa Micron Co., Ltd. to obtain particles of 2.5 mm or less. This is further reduced to 28 in a nitrogen atmosphere in a rotary kiln.
By treating at 0 ° C. for 3 hours, the flow temperature becomes 324
A wholly aromatic polyester comprising the following repeating structural units in the form of particles at a temperature of ° C was obtained. Here, the flow temperature is defined as 4 ° C. using a Koka type flow tester CFT-500 manufactured by Shimadzu Corporation.
/ Kg of resin heated at a heating rate of
/ Cm ² means a temperature at which the melt viscosity shows 48000 poise when extruded from a nozzle having an inner diameter of 1 mm and a length of 10 mm. Hereinafter, the liquid crystal polyester is represented by A-1.
Abbreviated. This polymer showed optical anisotropy at 340 ° C. or more under pressure. The repeating structural units of the liquid crystal polyester A-1 are as follows.

[0079]

(2) Component (B) (i) According to the method described in Example 5 of JP-A-61-127709, methyl acrylate / ethylene / glycidyl methacrylate = 59.0 / 38.7 / 2.3
(Weight ratio), Mooney viscosity = 15, heat of fusion of crystal <1
A rubber of J / g was obtained. Hereinafter, the rubber may be abbreviated as B-1. Here, the Mooney viscosity is JIS K6300
It is a value measured using a large rotor at 100 ° C. according to The heat of fusion of the crystal was determined by using a DSC and heating the sample from -150 ° C to 100 ° C at a rate of 20 ° C / min.

(3) Physical property measurement method The obtained film was measured in the following manner. (I) Tensile properties: The tensile properties in the MD and TD directions were measured using a No. 2 type test piece according to JIS Z1727. (ii) Flex resistance: The laminated material is cut out in the MD and TD directions of the laminated film, and each is cut out by Toyo Seiki
MIT Flex Testing Machine Folding Enduran
Use ce Tester MIT-D type and JIS-
Load 1 kgf, bending angle 13 based on p-8115
5 degrees, bending surface radius of curvature 1 mm, bending speed 175
The bending test was performed at times / min. (Iii) Permanent set of heating: The film was placed in a circulating hot air oven, heated at 200 ° C. for 30 minutes, cooled, and the length of the cooled film was measured and compared with the length measured before heating.

Example 1 A-1 was used at a ratio of 80% by weight and B-1 at a ratio of 20% by weight using a TEX-30 type twin screw extruder manufactured by Nippon Steel Corporation with a cylinder set temperature of 350 ° C. and a screw rotation. Several 200 rp
m, melt kneading was performed to obtain a composition. The flow start temperature of the composition was 328 ° C. Also, the composition is 340
It showed optical anisotropy above ℃. A pellet of this composition is supplied to a 60 mmφ single screw extruder equipped with a cylindrical die, melt-kneaded at a cylinder set temperature of 350 ° C. and a rotation speed of 60 rpm, and has a diameter of 50 mm, a lip interval of 1.0 mm, and a die set temperature of 355. The molten resin is extruded upward from a cylindrical die at a temperature of 0 ° C. At this time, dry air is press-fitted into the hollow portion of the cylindrical film to expand the cylindrical film, and after cooling, is passed through a nip roll and a take-up speed of 75 m / min. Take over,
A film composed of a liquid crystalline polymer to be used as a thermal transfer film was obtained.

At this time, the stretching ratio in the film MD direction is 3
6.8, blow ratio 4.6, measured thickness of film 6.
It was 0 μm. Hereinafter, the film may be abbreviated as g-1. g-1 has a tensile strength of 25 kg / MD.
mm ² , TD 12 kg / mm ² , elongation ratio is MD 2
%, TD 12%. In the MIT bending test of g-1, the film did not break in both MD and TD even after bending 100,000 times. In the heating test of g-1, 20
The film length did not change in both MD and TD even after heating at 0 ° C. for 30 minutes.

Using g-1 as a base film, a composition comprising 55 parts by weight of paraffin wax, 25 parts by weight of ethylene-vinyl acetate and 20 parts by weight of carbon black was hot-melt coated on one surface. The thickness of the heat transferable ink layer in the obtained heat transfer film was 4 μm. The film obtained here may be abbreviated as F-1. When micro slitting was performed on F-1 and a trial shot was performed using a commercially available thermal printer, no damage was found on the film.

Hereinafter, the present invention will be described with reference to FIG.
Fig. 1- (a) is a cross-sectional view of an example of the thermal transfer film of the present invention, wherein 1 is a film (g-1) composed of a liquid crystal polymer as a substrate, 2 is a layer composed of a thermal transfer ink, For example, a film obtained by mixing 50 parts by weight of paraffin wax, 25 parts by weight of carbon black, 25 parts by weight of ethylene-vinyl acetate copolymer, and the like, is used as a base material, and is a film made of a liquid crystalline polymer (g-1). It is formed by hot melt coating on top. Figure 1
(B) shows an example of a method for performing thermal transfer using the thermal transfer film of the present invention. The thermal transfer film of the present invention is a film (substrate) composed of a liquid crystalline polymer
1 and a layer 2 made of a heat transferable ink are constituents.
The thermal head 3 descends from above the substrate 1 to heat the thermal transfer film, and the thermal transfer ink is transferred onto the receiver 4 made of paper or a plastic film.

[0086]

According to the present invention, it is possible to obtain an inexpensive heat transfer film having good heat resistance, chemical resistance, flexibility, etc., small elongation, and widely used in printers, facsimile machines, copiers and the like. Is possible.

[Brief description of the drawings]

FIG. 1A shows a cross-sectional view of an example of the heat transferable film of the present invention. (B) is a diagram illustrating a thermal transfer method using the thermal transferable film of the present invention.

[Explanation of symbols]

 1 Film of liquid crystalline polymer as base material 2 Layer of thermal transfer ink 3 Thermal head 4 Receptor

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (Reference) C08L 33:14) B41M 5/26 101A F-term (Reference) 2H111 AA01 AA26 AA27 AA33 BB06 4F071 AA33 AA43 AA83 AA88 AF02 AF12 AF26 AF35 AF45 AH16 BA01 BB09 BC01 4J002 BG072 CF041 CF181 GS00

Claims (17)

[Claims] 1. A thermal transfer film comprising a layer composed of a thermal transfer ink and a base material, wherein the base material is a film made of a liquid crystalline polymer exhibiting optical anisotropy when melted. Heat transfer film. 2. A liquid crystalline polymer exhibiting optical anisotropy upon melting, wherein (A) a liquid crystalline polyester is a continuous phase and (B) a copolymer having a functional group reactive with the liquid crystalline polyester is a dispersed phase. The thermal transfer film according to claim 1, which is a liquid crystal polyester resin composition. 3. A liquid crystalline polymer exhibiting optical anisotropy when melted comprises (A) 56.0 to 99.9% by weight of a liquid crystal polyester and (B) a copolymer having a functional group reactive with the liquid crystal polyester. 2. A composition obtained by melt-kneading 44.0 to 0.1% by weight of a polymer.
Or the thermal transfer film according to 2. 4. The thermal transfer film according to claim 2, wherein the functional group reactive with the liquid crystal polyester is an oxazolyl group, an epoxy group or an amino group. 5. A copolymer (B) having a functional group reactive with a liquid crystal polyester, wherein the copolymer (B) contains 0.1 to 30% by weight of an unsaturated glycidyl carboxylate unit and / or an unsaturated glycidyl ether unit. The thermal transfer film according to any one of claims 2 to 4, which is a polymer. 6. The copolymer (B) having a functional group reactive with a liquid crystal polyester has a crystal heat of fusion of 3 J / g.
The thermal transfer film according to any one of claims 2 to 5, wherein the copolymer is a copolymer of less than 7. The method according to claim 2, wherein the Mooney viscosity of the copolymer (B) having a functional group reactive with the liquid crystal polyester is in the range of 3 to 70. Thermal transfer film. Mooney viscosity here is J
A value measured using a large rotor at 100 ° C. according to IS K6300. 8. The thermal transfer film according to claim 2, wherein the copolymer (B) having a functional group reactive with the liquid crystal polyester is a rubber having an epoxy group. 9. The rubber having an epoxy group comprises (meth) acrylate-ethylene- (unsaturated carboxylic acid glycidyl ester and / or unsaturated glycidyl ether) copolymer rubber. The thermal transfer film as described in the above. 10. The (meth) acrylic acid ester is methyl acrylate, methyl methacrylate, n-butyl acrylate, n-butyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate,
The thermal transfer film according to claim 9, comprising at least one selected from -ethylhexyl acrylate and 2-ethylhexyl methacrylate. 11. The thermal transfer film according to claim 2, wherein the copolymer (B) having a functional group reactive with the liquid crystal polyester is a thermoplastic resin having an epoxy group. 12. A thermoplastic resin having an epoxy group,
(A) 50 to 99% by weight of ethylene units, (b) 0.1 to 30% by weight of unsaturated carboxylic acid glycidyl ester units and / or unsaturated glycidyl ether units,
(C) 0-50 ethylenically unsaturated ester compound units
The thermal transfer film according to claim 11, wherein the thermal transfer film is an epoxy group-containing ethylene copolymer in an amount of 1% by weight. 13. The thermal transfer film according to claim 2, wherein the liquid crystal polyester (A) contains at least 30 mol% of the following repeating structural units. 14. The liquid crystal polyester (A) according to claim 2, wherein the liquid crystal polyester (A) is obtained by reacting an aromatic dicarboxylic acid, an aromatic diol and an aromatic hydroxycarboxylic acid. The thermal transfer film as described in the above. 15. The thermal transfer film according to claim 2, wherein the liquid crystal polyester (A) is obtained by reacting a combination of different aromatic hydroxycarboxylic acids. 16. The thermal transfer film according to claim 2, wherein the thermal transfer recording medium uses a heat-meltable ink. 17. The thermal transfer film according to claim 2, wherein the thermal transfer recording medium uses a heat sublimable ink.