JPH028089A - Thermal transfer polyester film - Google Patents

Abstract

PURPOSE:To improve the travelling performance, sticking resistance, and printing property of a film by a method wherein an insolouble infusible organic particle is contained in a molten polyester having a specific average particle size. CONSTITUTION:An organic particle which is insoluble and infusible in molten polyester is used as a particle to be contained in a polyester film. Those obtained by suspension or emulsion polymerization of, for instance, methyl methacrylate or methacrylic acid and divinylbenzene or ethylene glycol dimethacrylate as start raw materials can be exemplified. The film in which those organic particles are mixed is good in slitting property and excellent in flatness and transfer to a travelling surface of ink is not observed. An average particle size of the organic particle is 0.05 to 5mum, and a mixing amount in the polyester film shall be 0.01 to 10wt.%. When the average particle size or the mixing amount is under those values, the film creases very easily and sticking of a thermal head part is generated. In the case of exceeding those values, a surface of the film is coarsened and printing property is deteriorated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a thermal transfer recording film,
More specifically, the present invention relates to a film that has excellent running properties and staking resistance, excellent slitting properties, and good flatness, and is suitable for high-speed printing.

[Problems to be solved by conventional technology and invention]

Although various recording methods have been known in the past, thermal transfer using a thermal recording device such as a thermal printer is widely used because of its excellent operability and maintainability. As the base film for this transfer material for printers, polyester films, especially U-axis oriented films of polyethylene terephthalate, are used because they have excellent properties in terms of high melting point, heat resistance, chemical resistance, mechanical strength, etc. Ta.

It is also well known that inorganic particles such as silicon dioxide or titanium dioxide, which are inert to the polyester and have an appropriate particle size, are blended into the film in order to improve its runnability and staining resistance.

However, in recent years, in high-speed transfer, the surface roughness of the base film has tended to be relatively large in order to maintain a high level of runnability, and according to the inventor's knowledge, new problems arise in this case. .

That is, in order to develop such surface roughness, it is necessary to increase the particle size and amount of inorganic particles contained in the film, but as a result, the slitting properties of the film become poor.

In other words, heat-sensitive transfer agents are used as strips by applying an ink layer on one side of a polyester film and, if necessary, providing a heat-resistant protective layer on the opposite side, which is then slit and used as strips. Because of the inorganic particles added to the film to improve kingability, the slitting blade is easily damaged, and the edges of the film often bulge.

As a result, the ink layer applied to the film tends to be transferred to the opposite surface (running surface), which causes problems such as staining the guide bins and thermal heads of the running system.

[Means for solving problems]

As a result of intensive studies in view of the above-mentioned problems, the inventors of the present invention found that polyester containing certain specific particles is useful as a film for heat-sensitive transfer, and completed the present invention.

That is, the gist of the present invention is that the average particle diameter is 0.05 to S μm.
The present invention relates to a polyester film containing 0.01 to 10% by weight of an insoluble and infusible crosslinked polymer in molten polyester.

The present invention will be explained in more detail below.

The polyester referred to in the present invention refers to terephthal e-2,4
- It refers to a polyester obtained as the main starting materials of an aromatic dicarboxylic acid such as naphthalene dicarboxylic acid or its ester and ethylene glycol, but it may contain other components. In this case, the dicarboxylic acid components are terephthalic acid, phthalic acid, and isophthalic acid.

6-naphthalene dicarboxylic acid and its isomers.

One or more kinds of oxycarboxylic acids such as adipic acid, sebacic acid, and p-oxyethoxybenzoic acid can be used. The glycol component is diethylene glycol.

One or more of propylene glycol, butanediol-/, U-cyclohexane dimetatool, neopentyl glycol, etc. can be used. In any case, the polyester of the present invention is a repeating structural unit of go
Refers to a polyester having ethylene terephthalate units or ethylene-2, &-naphthalene units.

Further, the polyester film of the present invention refers to a polyester film oriented in at least one axis direction using such a polyester as a starting material, and a known method can be used for its production. For example, normal core 0-3
After melting and extruding into a sheet at 20°C, it is cooled and solidified at 0~gθ°C to form an amorphous sheet, then biaxially stretched vertically and horizontally, or simultaneously stretched, and heat treated at 760~250°C. (For example, the method described in Tokkosho, IO-!T439) can be used.

In the present invention, the sum of the Young's moduli of the polyester film thus obtained in the vertical and horizontal directions is goθkf/
110112, preferably 90θkt/parrot2 or more. Further, the thickness thereof is preferably O, S to 30 μm, preferably 1 to 10 μm.

By the way, a feature of the present invention lies in the use of specific organic particles as the particles contained in the polyester film.

The organic particles that can be used in the present invention are not particularly limited as long as they are substantially insoluble and infusible in molten polyester.For example, thermosetting phenolic resin, thermosetting epoxy resin,
Examples include thermosetting urea resins, benzoguanamine resins, and fluororesins such as polytetrafluoroethylene. However, most preferably, for example, Tokko Akira! ;9-s2/1. A crosslinked polymer having heat resistance as described in the above publication, for example, (1) a compound having only one aliphatic unsaturated group in the molecule such as methyl methacrylate or methacrylic acid; and (2) Typical examples include those obtained by suspension or emulsion polymerization using a compound having two or more aliphatic unsaturated groups in the molecular chain, such as divinylbenzene or ethylene glycol dimethacrylate, as a starting material. However, it is of course not limited to these.

In the present invention, these organic particles may have a group capable of reacting with polyester. Further, it can be used regardless of the presence or absence of porosity and the shape.

A film containing such organic particles instead of conventionally used inorganic particles has good slitting properties, good flatness, and no ink transfer to the running surface.

In addition, in the present invention, the average particle diameter of the organic particles is o, os
-S μm, preferably 0.1 to 3 μm. Further, the amount of organic particles blended into the polyester film is θ, 01-/θ weight %, preferably Q, selected from the range of 1 to 7 weight %. If the average particle diameter or the blending amount is less than these values, the film is likely to wrinkle, resulting in poor workability and sticking of the thermal head, which is undesirable. On the other hand, if the average particle diameter or blending amount exceeds these values, the surface of the film becomes too rough and printability deteriorates.

In the present invention, these organic particles in a certain range are blended into a polyester film, and the resulting film surface has a centerline average roughness of 0.00 g to 7.
．． Preferably it is 0 μm, preferably 0.0/−0.3 μm.

There is no particular restriction on the timing of blending these organic particles into the polyester film, and it may be at any time as long as good dispersibility is maintained. For example, a so-called tri-blend method may be employed in which organic particles are blended with polyester immediately before film formation, or the particles may be added and dispersed during the polyester manufacturing process.

In this way, the present invention allows a polyester film to contain a specific amount of organic particles with a specific particle size, thereby maintaining a high level of runnability and staking resistance while also satisfying slitting properties, which have been difficult to improve in the past. It could have been done,
Its industrial value is high.

In the present invention, the type of heat-sensitive transfer layer formed on the base film is not limited, and either a non-reactive type or a reactive type can be used. Non-reactive types include, for example, a transfer layer made of hot-melt ink or a transfer layer made of sublimable dye, and -! An example of a reaction type dye is a combination of a leuco dye and a color developer.

〔Example〕

The present invention will be explained in more detail below using Examples and Comparative Examples; however, the present invention is not limited to the following Examples unless it exceeds the gist thereof.

In the examples and comparative examples, "parts" indicate "parts by weight."

Further, the measurement method used in the present invention is as follows.

m Center line average roughness was determined as follows using a surface roughness meter (SE-, 7FK) manufactured by Koita Research Institute. The tip radius of the stylus was 2 μm, and the load was 30 m9. A part with a standard length of 2.5 am) is extracted from the film cross-sectional curve in the direction of its center line, and the roughness curve my-f (5 ), the value given by the linear equation is expressed in μm.

(2) Average particle size Measure the particle size using a microscope and convert it to 1 equivalent sphere, and the cumulative weight is 5
The zero point was taken as the average particle diameter.

In the present invention, the average particle size is expressed in terms of diameter.

(3) Film running properties during printing If transfer ink was applied to the base film. That is, a heat-melting color material layer consisting of 35 parts of paraffin wax, 30 parts of carnauba wax, low molecular weight polyethylene 1S parts, and 12 parts of carbon black was coated on one side of the film so that the dry film thickness was 2.5 μm. . Note that a silicon-based heat-resistant protective layer with a thickness of 0.0 S μm was provided on the opposite side to the coloring material layer.

Next, Fuji Xerox's facsimile Telecopier 2
The running condition of the heat-sensitive transfer film obtained as above was evaluated using a type S type machine and divided into the following three stages.

○...The feeding condition is good and there are no problems at all.

Δ...The ribbon may be slightly wrinkled.

×: The ribbon is wrinkled and the feeding condition is often poor.

(4) Stick characteristics The stick characteristics were evaluated using the same evaluation machine and film as in the evaluation of film runnability during printing, and were divided into the following three stages.

O: Good or good with no problems at all.

−υ! △...Slight adhesion is observed.

X...Fusion often occurs, resulting in poor ribbon conveyance.

(5) Printability Printability was evaluated using the same evaluation machine and film as in the evaluation of film runnability during printing, and was divided into the following three stages.

○: Good with no shading or bleeding.

Δ: Slight unevenness in shading and bleeding are observed.

X: Unevenness in shading or blurring is clear.

(6) Slitting properties of the film The film coated with the transfer ink and heat-resistant protective layer used to evaluate the film runnability during printing was slit continuously soooom, and the degree of swelling on the end face of the roll was observed. It was divided into three stages.

○: There is almost no swelling and the winding appearance is good.

Δ: There is relatively little bulge, but the edges are slightly swollen.

X: The bulge is large and the edges are swollen.

(Ink transferability) A ribbon slit to a width of 19 m and rolled was unwound and run over 200 lengths, and dirt on the guide bin where the heat-resistant protective layer came into contact was observed and divided into the following three stages.

○...Almost no ink adhesion is observed.

Δ: Some ink adhesion is observed.

×: Considerable ink adhesion is observed.

Example 1 (Production of organic particle-containing polyester) 29 parts of methyl methacrylate, 110 parts of divinylbenzene, 31 parts of ethylvinylbenzene, 1 part of benzoyl peroxide, and 100 parts of toluene were uniformly dispersed in 600 parts of water. Next, the mixture was heated under a nitrogen atmosphere with stirring for 6 hours to perform polymerization. The average particle diameter of the obtained polymer particles was 0.1 rraa, and the degree of crosslinking was 0%.

Next, the produced polymer was washed with demineralized water and extracted twice with 500 parts of toluene to remove a small amount of unreacted monomer linear polymer. Next, the polymer granules were coarsely ground with a hammer mill, and then further ground with a sand grinder for 5 hours.

A crosslinked polymer fine powder with an average particle size of 0.7 μm was obtained.

Next, in the polyester manufacturing process, after the transesterification reaction, the crosslinked polymer fine powder is added as an ethylene glycol slurry, and the polycondensation reaction is carried out by a conventional method, and finally the organic particles are made into polyethylene terephthalate containing O, S weight%. Obtained.

(Manufacture of polyester film containing organic particles) After vacuum drying the obtained polyester at 100°C for 6 hours,
It was melted at a temperature of 0.degree. C., extruded from a T-die, and rapidly cooled to obtain an unstretched sheet. The film was then stretched 3.5 times in the machine direction and 3.6 times in the transverse direction, and then heat treated at 230° C. to obtain a co-axis oriented polyethylene terephthalate film with a thickness of q μm.

Material (evaluation as thermal transfer) Transfer ink and a heat-resistant protective layer were applied to the thus obtained polyethylene terephthalate film containing 0.5% by weight of organic particles with an average particle diameter of 067μ, and thermal transfer was performed. We evaluated it as a material.

These results are shown in Table 1 together with the results of other Examples and Comparative Examples.

Example A co-axis oriented polyethylene terephthalate film was obtained in the same manner as in Example 1 except that the average particle diameter and amount of organic particles blended into the film were changed.
Evaluation as a thermal transfer material was conducted in the same manner as above.

A λ-axis oriented polyethylene terephthalate film was obtained in the same manner as in Example 3 and Example 3, except that benzoguanamine particles or polytetrafluoroethylene particles were used instead of the crosslinked polymer particles in Example 3 and Example 3. Next, evaluation as a thermal transfer material was performed in the same manner as in Example.

Comparative Example 1 and λ In Example 1, aluminum oxide or silicon dioxide was used instead of organic particles to obtain a co-axis oriented polyethylene terephthalate film.Then, the film was evaluated as a thermal transfer material in the same manner as in Example 1.

Comparative Examples 3 and q A co-axis oriented polyethylene terephthalate film was obtained in the same manner as in Example 1 except that the average particle diameter of the organic particles and the amount added to the polyester film were changed.
Next, evaluation as a thermal transfer material was conducted in the same manner as in Examples.

The results obtained above are summarized in Table-/.

〔Effect of the invention〕

According to the present invention, the running properties, anti-staking properties, and printing properties of the film, which tend to cause thermal transfer time problems, are highly satisfied, and the slitting properties are significantly improved. As a result, the cut surface is smooth, no ink transfer stains are observed, and there is no stain on the guide bottle or thermal head, making it suitable as a film for thermal transfer.

Applicant: Diafoil Co., Ltd.

Claims (1)

[Claims] A polyester film for thermal transfer, characterized in that it has an average particle diameter of 0.05 to 5 μm and contains 0.01 to 10% by weight of organic particles that are insoluble in molten polyester.