KR100470131B1 - Film for a thermosensitive copying record medium and process of preparing same - Google Patents

Abstract

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a film for thermal transfer recording media having excellent heat resistance and easy activity, and a method for producing the same, comprising a polysiloxane main chain and an acrylic resin side chain on one side after stretching an extruded polyester sheet in a longitudinal direction. The film according to the present invention prepared by applying an aqueous coating solution containing a copolymer and a fluorine-based anionic surfactant, transversely stretching and drying it, has not only excellent heat resistance and diactivation but also a problem of back transfer during winding storage. It does not produce and can be usefully used as a film for thermal transfer recording media.

Description

FILM FOR A THERMOSENSITIVE COPYING RECORD MEDIUM AND PROCESS OF PREPARING SAME}

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a film for thermal transfer recording media and a method for manufacturing the same, specifically, a graft copolymer having a main chain of polysiloxane and a side chain of an acrylic resin on one side of a longitudinally stretched polyester base film and a fluorine-based anionic interface. The present invention relates to a film for a thermal transfer recording medium having excellent heat resistance and diactivity, and a method for producing the same, which are prepared by applying an aqueous coating solution containing an active agent, and then stretching and drying the film.

In recent years, with advances in image processing systems, cad, computer graphics, etc. centering on word processors or personal computers, color or black and white hard copy technology as a terminal for image output is rapidly advancing. The demand for color hard copy is also increasing for output by video and digital cameras.

Representative hard copy techniques include conventional photography techniques using photosensitive silver halide salts, inkjet techniques, electrophotographic techniques and thermal transfer techniques, among which thermal transfer techniques are simple to operate and convenient to use. It is simple in terms of device and has advantages such as miniaturization and easy facility maintenance and repair.

According to the thermal transfer method, a thermal head and a nib roll adhere closely to a thermal transfer recording medium and an aqueous phase, and ink or dye applied to one side of the thermal transfer recording medium is the back surface (ink layer). Is transferred to a watertight body which is in close contact by a heat head that applies heat to the opposite side to form an image. At this time, it is preferable to control the heating temperature by the heat head to be equal to or lower than the melting point of the medium and equal to or higher than the melting point of the thermally meltable ink or the sublimation point of the dye. Due to this principle, the contact surface with the thermal head of the thermal transfer recording medium is required to have excellent heat resistance as well as excellent deactivation in a heated state.

On the other hand, as the printing speeds up, it is required to increase the input power to shorten the input time to the thermal head, but in this case, the thermal transfer recording medium is fused to the thermal head, which hinders the running of the thermal transfer recording medium. Will receive. This phenomenon is called sticking, which causes a decrease in recording resolution and poor driving of the medium.

In order to solve this phenomenon, a method of forming an application layer capable of preventing sticking to the thermal head on one side (the opposite side of the ink layer) of the base film of the thermal transfer recording medium in contact with the thermal head is used. Has been. However, this method has a problem in that the components of the coating layer are easily transferred to the back side when the film product is wound up and stored. Specifically, the components to be applied to achieve excellent heat resistance and activity are mostly low surface tension materials such as wax and silicone, so that the adhesion between these coating layer components and the base film is not considered in the product design stage, Upon contact with the material, the application layer components are easily removed from the film and transferred to the contacting material. When only the back coating layer is applied to the film and the product is wound and stored, the applied component is transferred to the back surface, so that the adhesion between the film and the ink / dye may be abnormally reduced when the ink / dye is applied. Formation is impossible. In addition, when the back coating layer and the ink / dye layer are applied to both sides of the film at the same time, and the product is wound and stored, the applied component is transferred onto the ink / dye layer and the adhesion between the ink / dye layer and the print receiving body is inevitably inevitable. Because it is weakened, it is accompanied by side effects such as factor dropout.

Specific embodiments thereof are disclosed in Japanese Patent Laid-Open Nos. 95-81017 and 96-1887. Here, waxes, higher fatty acid metal salts, and phosphate esters are used as components of the back coating layer, but these are compounds that do not exert a special adhesive force on the film and are transferred to the back during product storage, and then, as a product after 3 to 4 months, The value is lost.

Accordingly, a method of firmly attaching a back coating layer on a film by applying an additive such as a reactive resin and a slipping agent to one side of the film and curing the same by ultraviolet or electron beam irradiation is performed (US Patents 5,700,756, 5,372,988 and 5,324,583). According to this method, the problem of the back transfer of the applied component can be improved, but it is complicated and disadvantageous in terms of the price, such as the need to install an ultraviolet or electron beam irradiation apparatus separately.

Further, JP-A-92-262,066 and U.S. Patent No. 5,397,764 disclose that a layer of a graft copolymer having a main chain as an acrylic resin and a side chain as a silicone resin is formed on one side of the film without side effects of back transfer. Disclosed are a method for improving heat resistance and diactivity. However, since this method adopts an application method using an organic solvent and inevitably volatilizes the organic solvent in the manufacturing process, it is not preferable in terms of the environment, such as volatile organic solvent is released into the atmosphere, the coating step is a film forming process Since it must be carried out separately from the manufacturing cost has a problem that greatly increases.

Accordingly, the inventors have intensively studied, and as a result, by applying an aqueous coating solution containing a graft copolymer having a main chain of polysiloxane and a side chain of an acrylic resin and a fluorine-based anionic surfactant to one side of the film during the film forming process, The present invention has been completed by discovering that a film for thermal transfer recording media having excellent properties can be produced.

SUMMARY OF THE INVENTION An object of the present invention is to provide a film for thermal transfer recording media excellent in heat resistance and diactivity and a method of manufacturing the same.

In order to achieve the above object, in the present invention, the extruded polyester sheet is stretched in the longitudinal direction, and then, on one side of the longitudinally stretched film, a polysiloxane main chain and an acrylic resin side chain in a weight ratio of 3: 7 to 6: 4. Applying an aqueous coating solution comprising 1.5 to 15% by weight of the graft copolymer constituted and 0.01 to 0.1% by weight of a fluorine-based anionic surfactant, and then stretched and dried in a transverse direction so that the dry coating amount is 0.075 to 0.095 g / m ^2. A method for producing a film for thermal transfer recording media, comprising the; And a film for a thermal transfer recording medium produced by such a method.

Hereinafter, the present invention will be described in more detail.

According to the present invention, a film for thermal transfer recording media having excellent heat resistance and active activity by applying an aqueous coating solution containing a polysiloxane-acrylic graft copolymer and a fluorine-based anionic surfactant to one side of a longitudinally stretched film during the film forming process. Can be prepared.

The polysiloxane-acrylic graft copolymer used in the present invention is composed of a polysiloxane backbone and an acrylic resin side chain in a weight ratio of 3: 7 to 6: 4, which is prepared by preparing an emulsion of polysiloxane in an aqueous dispersion system and then adding an acrylic monomer thereto. It can be prepared by addition and graft copolymerization.

Looking at the manufacturing method of the graft copolymer according to the present invention in detail, first, using a surfactant to disperse a silicone monomer mixture consisting of a silicone-containing monomer, a molecular weight regulator, a silicone crosslinking agent and a graft enabler in distilled water, and then acidic Or hydrolysis and polymerization of each raw material at 40 to 50 ° C. under a basic atmosphere to prepare an emulsion of polysiloxane. Subsequently, an acrylic monomer and a polymerization initiator are added to the prepared polysiloxane emulsion, and a polysiloxane-acrylic graft copolymer according to the present invention is prepared by graft copolymerizing an acrylic monomer to polysiloxane at 60 to 80 ° C.

Silicone-containing monomers used in the present invention are hydrolyzed or ring-opened under an acidic or basic atmosphere to polymerize into high molecular weight polysiloxanes with two reactive hydroxy groups. Representative examples of the silicone-containing monomers include dimethyldimethoxysilane, dimethyldichlorosilane, dimethylhydrogensilane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and mixtures thereof, and the like, from 60 to 60 based on the total amount of the silicone monomer mixture. It can be used in an amount of 80% by weight.

Molecular weight modifiers used in the present invention serve to inhibit the persistence of unwanted reactions after the reaction and to control the molecular weight of the polysiloxanes. Representative examples of the molecular weight modifier include trimethylmethoxysilane, trimethylethoxysilane, trimethylhydrogensilane, hexamethyldisiloxane, and mixtures thereof, and may be used in an amount of 0.5 to 2% by weight based on the total amount of the silicone monomer mixture. Can be.

The silicone crosslinking agent used in the present invention plays an important role in controlling the particle size of the silicone emulsion, and also affects the strength and friction coefficient of the copolymer. Representative examples of the silicone crosslinking agent include tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane and mixtures thereof, and may be used in an amount of 10 to 40% by weight based on the total amount of the silicone monomer mixture.

The graft enabler used in the present invention further promotes graft copolymerization with acrylic monomers. Representative examples of the graft enabler include methacryloyloxypropyltrimethoxysilane, vinyltrimethoxysilane, allyltrimethoxysilane, methacryloyloxypropylmethyldimethoxysilane, methacryloyloxypropyldimethylmethoxy Methoxysilane and mixtures thereof, and the amount of use thereof varies depending on the ratio of polysiloxane and acrylic resin, the ratio of acrylic resin and polymerization initiator, the shape design of the graft copolymer, and the like. Preference is given to using in amounts by weight.

In addition, as the acrylic monomer used in the present invention, methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, styrene, butyl acrylate, a mixture thereof, and the like, which can exhibit adhesion to a film, may be used. Can be. In particular, when the methyl acrylate and ethyl acrylate are used in combination, it is preferable to mix the two components in a weight ratio of 3: 7 to 5: 5.

According to the present invention, 1.5 to 15% by weight of the graft copolymer thus prepared is mixed with 0.01 to 0.1% by weight of the fluorine-based anionic surfactant to form an aqueous coating solution. At this time, the fluorine-based anionic surfactant having low interfacial tension is strong in water repellency and oriented on the surface of the silicon component that causes cratering on the film surface, thereby preventing the water repellency of the silicone component, thereby preventing the cratering phenomenon. Representative examples of fluorine-based anionic surfactants used in the present invention include ammonium perfluoroalkyl sulfonates, potassium fluoroalkyl carboxylates, ammonium perfluoroalkyl carboxylates and sodium fluoroalkyl sulfonates.

The aqueous coating liquid formed according to the present invention is applied so that the dry coating amount is on the one side of the longitudinally stretched film during the film forming process is 0.075 to 0.095 g / m ² . Subsequently, the film for the thermal transfer recording medium according to the present invention can be produced by stretching the film in the transverse direction and then passing it through a heat-opening portion.

Examples of the polyester base film for thermal transfer recording media include polyethylene terephthalate, polybutylene terephthalate, polycarbonate, and the like, and it is preferable to use polyethylene terephthalate which is advantageous in terms of cost and heat resistance.

The film produced according to the method of the present invention can achieve excellent heat resistance and diactivity through the polysiloxane of the graft copolymer applied to one side, the acrylic resin of the graft copolymer to enhance the adhesion to the base film It can be usefully used as a base film for thermal transfer recording media without causing a problem of back transfer even during winding storage.

The thermal transfer ink or the thermal sublimation dye is applied to the opposite surface of the coating layer of the base film thus produced, and can be used in the thermal transfer method as a thermal transfer recording medium.

Hereinafter, the present invention will be described in more detail based on the following examples. However, the following examples are not intended to limit the present invention, but are not limited thereto. Various performance evaluations of the films prepared in Examples and Comparative Examples of the present invention were performed by the following methods.

(1) back transfer rate

Put a polyethylene terephthalate film (SG00 50㎛, SKC Co., Ltd.) on the coating layer of the film prepared according to the present invention and left for 24 hours at a temperature of 70 ℃ and a pressure of 25 g / m ² coated layer on the SG00 film Transcription of components was induced. The industrial tape (Nitto tape, Japan) was attached to the SG00 film thus induced, and left for 24 hours at a temperature of 70 ° C. and a pressure of 25 g / m ² , followed by using a peel tester (Heidon-17). Peeling force was measured while peeling SG00 and industrial tape (peel force A). On the other hand, by using the SG00 film in which no transfer was induced, the peel force was measured in the same manner (peel force B), and the back transfer rate was calculated according to the following equation (1):

Back Transfer Factor (%) = (B-A) / B × 100

(2) Print Test (Heat Resistant)

On one side of the film having no coating layer, a hot melt method was applied to a thermal transfer ink composition comprising 100 parts by weight of carnauba wax, 25 parts by weight of polyethylene microcrystalline wax, 20 parts by weight of acrylic acid-ethylene copolymer, and 20 parts by weight of carbon black. To a thickness of 3 mu m to produce a thermal transfer recording medium.

Using a manufactured thermal transfer recording medium, use a Zebra 140XI II printer (darkness setting: 1 to 30) to change the printer's contrast setting to produce a black rectangle of 2 cm x 3 cm at a speed of 4 inches / sec. Printed. When the contrast setting is increased, the thermal transfer medium is fused to the thermal head of the printer, whereby a longitudinal or transverse wrinkle appears in the printed rectangle, and the maximum contrast setting value where such wrinkle does not appear is denoted as heat resistant activity.

Example 1

1) Polymerization of Graft Copolymer

2,000 g of distilled water was added to 5,000 ml of a four-necked flask equipped with a thermometer, a nitrogen dosing device, and a stirrer, and then 20 g of sodium dodecyl benzene sulfonate, a surfactant, was completely dissolved in distilled water. While stirring the solution at high speed using a stirrer, 200 g of octamethylcyclotetrasiloxane (silicone-containing monomer), 40 g of trimethylmethoxysilane (molecular weight regulator), 150 g of methyltrimethoxysilane (crosslinking agent) and methacrylo 40 g of a silicone monomer mixture of yloxypropyltrimethoxysilane (grafting agent) was introduced into the reactor over 1 hour using a dropping apparatus. Here, 60 g of 1% acetic acid was added thereto, while maintaining the acidic condition, the temperature of the reactor was increased to 40 ° C. to perform hydrolysis and polymerization of the silicone monomer for 3 hours.

After completion of the polymerization reaction, while stirring the resulting polysiloxane emulsion at high speed, 200 g of methyl methacrylate and 300 g of ethyl acrylate were added to the reactor over 1 hour using a dropping apparatus. 250 g of potassium persulfate (polymerization initiator) at a concentration of 1% was added thereto, and the temperature of the reactor was raised to 70 ° C for graft copolymerization for 4 hours. When the graft copolymerization was completed, the resulting solids were measured and distilled water was added so that the solids were 25% by weight.

2) Preparation of Aqueous Coating Liquid

An aqueous coating solution consisting of 20% by weight of the graft copolymer emulsion prepared in step 1), 0.05% by weight of Fluorad FC-100 3M, and the remaining amount of distilled water were prepared.

3) Production of film for thermal transfer recording medium

During the process of producing a polyethylene terephthalate film having a thickness of 4.6 μm, on one side of the longitudinally stretched film using an application method by Meyer bar (# 4), the aqueous coating liquid prepared in step 2) was 250 m / The application was carried out at the rate of minutes. The film was then stretched in the transverse direction and dried by passing through an open section. At this time, the dry coating amount was 0.085 g / m ² . The back transfer rate and the heat-resistant activity of the prepared film were measured and shown in Table 1a.

Examples 2-4 and Comparative Examples 1-3

The polyethylene terephthalate film was manufactured by the method similar to Example 1, changing the component and composition ratio of an application layer as shown to following Table 1a and 1b. The rear transfer rate and the heat resistance activity of the prepared film were measured and shown in Tables 1a and 1b.

From the above Tables 1a and 1b, the films of Comparative Examples 1 and 2 to which the graft copolymer having no weight ratio of the polysiloxane main chain and the acrylic resin side chain presented in the present invention were applied, the rear transfer rate was too high or the heat resistance activity was large. In the case of Comparative Example 3, the polysiloxane and the acrylic resin are not graft copolymerized, so that the rear transfer rate is abnormally high, and thus the product may not have a value as a product.

The film produced according to the present invention can be usefully used as a film for a thermal transfer recording medium because it not only has excellent heat resistance and diactivity but also does not cause a problem of back transfer during winding storage.

Claims (6)

Graft copolymer 1.5-15 consisting of a polysiloxane backbone and an acrylic resin side chain in a weight ratio of 3: 7 to 6: 4 on one side of the longitudinally stretched base film after stretching the extruded polyester base sheet A thermal transfer recording comprising applying an aqueous coating solution comprising a weight percent and 0.01 to 0.1 weight percent of a fluorine-based anionic surfactant, and then transversely stretching and drying the film so that the dry coating amount is 0.075 to 0.095 g / m ^2. The manufacturing method of the film for media. The method of claim 1, The graft copolymer hydrolyzes and polymerizes a silicone monomer mixture comprising a silicone-containing monomer, a molecular weight modifier, a silicone crosslinking agent and a graft enabler in an acidic or basic atmosphere in water to produce a polysiloxane emulsion, and then an acrylic monomer is added thereto. Method characterized in that it is prepared by graft copolymerization. The method of claim 1, And the fluorine-based anionic surfactant is at least one selected from the group consisting of ammonium perfluoroalkyl sulfonate, potassium fluoroalkyl carboxylate, ammonium perfluoroalkyl carboxylate and sodium fluoroalkyl sulfonate. The method of claim 2, And at least one acrylic monomer is selected from the group consisting of methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, styrene and butyl acrylate. A film for thermal transfer recording media produced according to the method of any one of claims 1 to 4. A thermal transfer recording medium, wherein a thermal transfer ink or a thermal sublimation dye is applied to an opposite surface of the film of claim 5.