JP2542507B2 - OHP sheet for thermal transfer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a novel OHP (overhead project) sheet for thermal transfer, and particularly provides an extremely clear print quality of characters and images by using a thermal transfer color printer or the like. The present invention relates to a heat transfer OHP sheet that can be used.

(Prior Art) In a thermal fusion transfer method, which is one of thermal transfer recording methods, an ink ribbon having a thermal fusible ink layer is superimposed on a recording material, and a pattern such as a character or a graphic is heated from the ink ribbon. This is a method in which heating is performed in a pattern to transfer the heat-meltable ink of the ink ribbon onto a recording material.

On the other hand, in the OHP that transmits light to the created sheet to project characters, figures, and the like on the sheet onto a screen, the above-described method of transferring a hot-melt ink is used to create the sheet.

In this case, the recording material conventionally used as an OHP sheet is a transparent film in which a rubber-based adhesive layer or an acrylic-based adhesive layer is applied, or a coating layer containing a solid wax having good compatibility with hot-melt ink. No. 60-154096) has been used and proposed.

(Problems to be Solved by the Invention) However, with the development of a thermal transfer printer for high-speed printing in recent years, it has been required to improve the printing quality of a sheet on the image receiving side. Is not being met.

In particular, in OHP sheets, when the ink receiving layer is composed of only organic polymer materials as in the above-mentioned conventional technology, if a recent high-speed printing model is used, part or all of characters are missing, and in solid printing, Insufficient ink loading causes irregular transfer of edges, irregular or blurred or almost no transfer, and it is difficult to obtain stable print quality. .

Of course, as a solution to this problem, many improvements have been made to the ink of the ink ribbon, but at present, a satisfactory one has not been obtained. In particular, when an ink ribbon compatible with plain paper is used, the print quality is further degraded in the conventional film processing method.

(Means for Solving Problems) In order to solve the above problems, the present invention provides an OHP sheet obtained by coating a base material with a coating agent for forming a thermal transfer ink receiving layer. OHP sheet for thermal transfer, characterized in that the agent is composed of organic polymer material, polyethylene wax, and hydrophobic powder having a degree of hydrophobicity of 30 v / v% or more of Degussa method methanol wettability as essential components. Is proposed.

In the present invention, the organic polymer material is an alkyd resin, an acrylic resin, an ethylene-vinyl acetate copolymer, a styrene-acrylic copolymer, a styrene-maleic acid copolymer, a polyester resin, an epoxy resin, a phenol resin, a polyurethane resin. , Melamine resin, polyolefin, coumarone resin, xylene resin, ketone resin and the like.

Further, those obtained by adding other polymer as a side chain to these resins can also be used. Furthermore, the above resins may be used alone or in combination of two or more. Further, among the above resins, those having reactivity can be used in combination with a known curing agent.

The polyethylene wax used in the present invention is a low molecular weight polyethylene having a molecular weight of 800 to 10000, including high density polyethylene wax, medium density polyethylene wax,
It means a low-density polyethylene wax and an oxidized polyethylene wax into which a polar group has been introduced.

These are produced by a method of producing ethylene by polymerization such as a method of polymerizing at high temperature and high pressure by a radical catalyst or a method of polymerizing at low pressure by a Ziegler catalyst, or synthesizing carbon monoxide and hydrogen by Fischer-Tropsch synthesis. It is produced by a method or by a method of reducing the molecular weight of polyethylene for general molding by thermal decomposition.

On the other hand, with the hydrophobic powder in the present invention, silica, clay, quartz, light calcium carbonate, colloidal calcium carbonate, precipitated barium sulfate, mica, talc, aluminum hydroxide, magnesium carbonate, colloidal hydrous aluminum silicate, It is an inorganic powder such as diatomaceous earth, quartz, and glass beads that has been subjected to hydrophobic treatment.

The hydrophobic treatment is generally a treatment in which the hydrophilic group on the surface of the powder is treated with a treating agent such as dimethyldichlorosilane or trimethylchlorosilane to make it hydrophobic, but in the present invention, the treating agent other than these is used. It is also possible to use a silane monomer, a silane coupling agent, a polysiloxane, a modified polysiloxane, or a powder that has been subjected to a hydrophobic treatment with an organic polymer material.

According to an experiment conducted by the inventors of the present invention, the degree of hydrophobicity of the hydrophobic powder and the methanol wettability by the Degussa method are 30 v / v% or more, preferably 40 v / v% or more.

Here, methanol wettability by the Degussa method means that 0.2 g of hydrophobic powder is sampled in a 100 ml beaker, 50 ml of pure water is added, methanol is added to the liquid surface while stirring, and the powder is formed on the liquid surface. The end point is the point where it is no longer recognized, and the amount of methanol (xml) required for this is expressed as the methanol concentration (v / v%) as in the following formula.

Hydrophobicity = {x / (x + 50)} × 100 (v / v%) That is, when the hydrophobicity of the hydrophobic powder becomes 30 v / v% or more, the lipophilicity of the powder advances and The affinity is improved, and as a result, the ink receptivity is improved.

Regarding the blending ratio of the organic polymer material, polyethylene wax, and hydrophobic powder, the printing performance tended to decrease when the polyethylene wax was relatively small, and the coating film strength tended to decrease when the polyethylene wax was large.

In addition, for hydrophobic powder, improvement in adhesion to ink due to increase in physical adhesion area due to unevenness of coating film surface,
In the heated part, heat is hard to be transferred from the heated part due to the adiabatic hardening due to the unevenness of the surface, and there is an excellent effect in improving the printing quality such as sharpening of the printing end face
If the amount added is increased, the powder is likely to fall off, and if it is reduced, the printing performance is deteriorated.

Due to the above tendency of each component, the mixing ratio of these components is 10 parts by weight of the organic polymer material and 3 parts of polyethylene wax.
The amount may be in the range of not more than 10 parts by weight, preferably 0.1 to 3 parts by weight, and the hydrophobic powder is 0.5 to 50 parts by weight, and a dispersion medium may be appropriately added thereto to obtain a solution-like coating agent. it can.

The dispersion medium used here may be an organic polymer material, compatible with polyethylene wax, and one that can uniformly disperse the hydrophobic powder, for example, petroleum solvent such as toluene and xylene, MEK, DMF and the like. A polar solvent, a chlorine-based solvent such as 1.1.1-trichloroethane, trichlorethylene, or perchlorethylene can be used.

The base material used for the OHP sheet for thermal transfer of the present invention must be a transparent plastic sheet material. For example, a transparent film of polyethylene terephthalate, polycarbonate, polyacetal or the like is used, and in particular, biaxially oriented polyethylene terephthalate film thickness 25 The thickness is in the range of up to 100 μm, and the film thickness may be appropriately determined according to the purpose of the characteristics of the printer.

The film thickness when the above-mentioned coating material is applied to the substrate may be a dry thickness of 0.01 μm or more, and is preferably 0.05 to 3 μm in consideration of performance, economy and the like.

As a coating method, an air knife coater, a bar coater, a reverse coater, a gravure coater, a hot melt coater method or the like can be used.

(Effects of the Invention) In summary, in the OHP sheet for thermal transfer of the present invention, the organic polymer material, the polyethylene wax, and the degree of hydrophobicity are 30 v / v% or more of the Degussa method methanol on the substrate surface. The thermal transfer ink receiving layer is formed by coating with a hydrophobic powder, which eliminates a transfer failure such that a part or all of the print is lost,
Accurate absorption of the thermal transfer ink is achieved.

Therefore, in this OHP sheet, stable and clear high print quality can be obtained even when a high speed printer is used.

In addition, the coated surface is extremely physically strong and stable without adversely affecting its transparency, and the printing characteristics are excellent, and therefore it is suitable as an OHP sheet.

(Example) Hereinafter, the Example of this invention is shown.

Example 1 As a substrate, polyethylene terephthalate [manufactured by Toray Industries:
A coating of various compositions is applied to a 50 μm thick film of trade name Lumirror T by a bar coater # 5 and dried at 130 ° C. for 30 seconds to prepare a transparent thermal transfer coating, and its printing performance, haze, The powder was removed and the film strength was evaluated.

The evaluation criteria are as follows, and the composition of the coating material and the evaluation results are shown in Table 1.

Evaluation Criteria (1) Printing performance: When printing with NEC's thermal transfer printer PC-PR-101T and the same printer PC-PR-101TL, the print with extremely clear printing was transferred. The good ones were marked with ○, the good ones were marked with △, and the bad ones were marked with x.

(2) Haze (transparency): Judged on OHP and compared the transparency with those not coated on the same base material, and those showing almost the same transparency were marked with ○, and slightly poorer with △. Poor performance was rated as x.

(3) Powder drop: When the coated surface was rubbed with the finger surface, the coating surface was not peeled off, ○ was given when the coating surface was peeled off a little, and x was given when the coated surface was peeled off indefinitely.

(4) Film strength: When the coated surface was rubbed with a nail, the coated surface was not peeled off, ○ was peeled off slightly, and △ was peeled off easily.

Blending example Blending example is shown below. In the formulation examples, MW of each powder indicates the degree of hydrophobicity [methanol wettability (v / v%) by the Degussa method].

(1) Epoxy resin (Epicoat 1007: Yuka Shell Epoxy Co., Ltd.) 10 parts by weight Polyethylene wax (High Wax 210MP: Mitsui Petrochemical Co., Ltd.) 1 part by weight Hydrophobic powder (Aerosil R972 (MW40): Nippon Aerosil Co., Ltd.) ) Add 5 parts by weight or more of MEK / toluene mixed solution to make a solution with a solid content of 2.0%.

(2) Styrene-acrylic copolymer (Oxylac SH210
0: Nippon Shokubai Chemical Co., Ltd.) 10 parts by weight Polyethylene wax (Sun Wax 151: Sanyo Chemical Co., Ltd.) 1 part by weight Hydrophobic silica (Aerosil R812 (MW60): Nippon Aerosil Co., Ltd.) 8 parts by weight MEK / Add a toluene mixed solution to make a solution with a solid content of 2.5%.

(3) Polyester resin (Chemit K1294: manufactured by Toray) 10
Part by weight Polyethylene wax (High Wax 4252E: manufactured by Mitsui Petrochemical Co., Ltd.) 1 part by weight Hydrophobic silica (HDK H-2000 (MW50): manufactured by WACHER) 15 parts by weight MEK / toluene mixed solution is added to the above composition and solidified. Use a solution with a mold component concentration of 2.5%.

(4) Isocyanate cross-linking type polyester resin (Adcoat 76H5, CAT10 = 100: 6.5: manufactured by Toyo Morton)
10 parts by weight Polyethylene wax (Hoechst wax PED521 Hoechst Japan Co., Ltd.) 1 part by weight Hydrophobic titanium oxide (T-805 (MW60): Nippon Aerosil Co., Ltd.) 0.5 parts by weight MEK / toluene mixed solution is added to the above composition and solidified. Use a solution with a mold component concentration of 2.0%.

Comparative Example (1) Polyester resin (Chemit 1809: manufactured by Toray) 10
Parts by weight Polyethylene wax (High wax 200MP: Mitsui Petrochemical Co., Ltd.) 1 part by weight Hydrophilic silica (Syloid 244 (MW <10): Fuji Davison Co., Ltd.) 5 parts by weight Add the MEK / toluene mixed solution to the above composition. A solution having a solid content of 2.0% was prepared.

(2) Xylene resin (Nikanol HP100: Mitsubishi Gas Chemical Co., Ltd.) 10 parts by weight Hydrophobic silica (Aerosil R974 (MW35): Nippon Aerosil Co., Ltd.) 5 parts by weight MEK / toluene mixed solution is added to the above composition and solid form. Use a solution with a concentration of 2.5%.

(3) BLANK: The base material as it is without any coating applied.

Claims (1)

(57) [Claims] 1. An OHP sheet obtained by applying a coating agent for forming a thermal transfer ink receiving layer on a substrate, wherein the coating agent is an organic polymer material, polyethylene wax, and the degree of hydrophobicity is Degussa. Method Methanol wettability 30v / v%
An OHP sheet for thermal transfer characterized in that it comprises the above hydrophobic powder as an essential component.