JPH05221148A - Micro resin particle, varnish and preparation of micro resin particle - Google Patents

Abstract

PURPOSE:To prepare micro resin particles useful as additive for various materials, excellent in dispersibility, heat resistance, and the like, easily dispersible into solvent, and having uniform size distribution. CONSTITUTION:In the preparation of micro resin particles, an organic solvent solution of thermoplastic resin containing hydroxyl group is dripped into an organic solvent solution of polyisocyanate and varnish consisting of a liquid medium, a thermoplastic resin and micro resin particles composed of a reaction product of a thermoplastic resin containing hydroxyl group and polyisocyanate thus depositing reaction product in the form of micro particles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to resin fine particles, and more particularly, it is useful as an additive for various materials, and particularly has excellent dispersibility, heat resistance, etc., and is easily dispersible in a solvent and has a uniform particle size distribution. The purpose is to provide fine resin particles.

[0002]

2. Description of the Related Art Conventionally, various inorganic particles such as talc, silica, calcium carbonate, etc., organic resin particles such as acrylic resin, melamine resin, phenol resin, benzoguanamine resin, polyurethane resin, fluorine resin, silicone resin, etc. are known. For example, in various applications such as paints, printing inks, molding resins, surface treatment agents, etc., they are used for the purpose of extending agents, extender pigments, fillers, heat-resistant agents, lubricants, matting agents and the like. As an example of the use of the particles as described above, there is an example of being used as a heat-resistant agent for the back layer of a thermal transfer sheet for forming an image with a thermal head. As these thermal transfer sheets, a sublimation type thermal transfer sheet in which a dye layer comprising a sublimable dye and a binder is provided on one surface of a polyester film or the like, and an ink layer comprising a pigment and a wax is provided in place of the dye layer. Thermal melting type thermal transfer sheets are known. These thermal transfer sheets are heated imagewise from the back side by a thermal head to transfer the dye of the dye layer or the ink layer to the transfer material to form an image.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the above-mentioned thermal transfer sheet, the purpose of forming a heat-resistant layer on the back surface is to form an image with a thermal head, and when the base film is a thermoplastic film such as polyester film. Since the thermal head is heated to a high temperature, the thermal head is fused to the base material film, which hinders good running performance of the thermal head, and prevents problems such as damage and wrinkles on the thermal transfer sheet. Is. As a method of solving these problems, a method of forming a back layer made of a heat-resistant resin on the contact surface of the thermal head is known, but the heat-resistant resin does not lower the sensitivity. It is difficult to form a thin film. Even if the thermal head can be formed, the thermal head does not have sufficient slip properties, and the running performance of the thermal head cannot be satisfied.

Further, a coating material containing a thermoplastic or thermosetting resin having a good coating property is filled with the above-mentioned inorganic particles of talc, silica or the like, fine particles of the thermosetting resin, a lubricant and the like to obtain heat resistance. And a method for forming a back layer having good lubricity is known, but it is required that these particles are fine particles, that the thermal head is not abraded and that they are uniformly dispersed in the formed coating film. However, inorganic fine particles such as talc have a problem that the thermal head is severely worn, and in the case of resin particles, it is difficult to make fine particles and uniformly disperse them. Therefore, an object of the present invention is to be useful as an additive for various materials, and particularly to provide resin fine particles having excellent dispersibility, heat resistance, and the like, which are easily dispersible in a solvent and have a uniform particle size distribution. ..

[0005]

The above object can be achieved by the present invention described below. That is, the present invention, resin fine particles characterized by comprising a reaction product of a hydroxyl group-containing thermoplastic resin and polyisocyanate, varnish and polyisocyanate characterized by comprising the resin fine particles, the thermoplastic resin and a liquid medium The method for producing resin fine particles is characterized in that the reaction product is precipitated as fine particles by dropping an organic solvent solution of a hydroxyl group-containing thermoplastic resin into the organic solvent solution.

[0006]

[Function] By forming and depositing a reaction product of a hydroxyl group-containing thermoplastic resin and polyisocyanate in the form of fine particles, it is useful as an additive for various materials, and particularly excellent in dispersibility, heat resistance, etc. and in a solvent. Further, resin fine particles which are easily dispersible and have a uniform particle size distribution are provided.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the preferred embodiments. The resin fine particles of the present invention are formed from a reaction product of a hydroxyl group-containing thermoplastic resin and polyisocyanate. As the hydroxyl group-containing thermoplastic resin,
Polyester resin, polyacrylic ester resin,
Polyvinyl acetate resin, styrene acrylate resin,
Polyurethane resin, polyolefin resin, polystyrene resin, polyvinyl chloride resin, polyether resin, polyamide resin, polycarbonate resin, polyethylene resin, polypropylene resin, polyacrylate resin, polyacrylamide resin, polyvinyl chloride resin, polyvinyl Butyral resin, thermoplastic resin such as polyvinyl acetal resin such as polyvinyl acetoacetal resin is used, and particularly preferable resin among them is polyvinyl butyral resin and polyvinyl acetoacetal resin having many hydroxyl groups in the molecule. Is a polyvinyl acetal resin.

As the polyisocyanate which reacts with the hydroxyl group-containing thermoplastic resin to form fine particles, any polyisocyanate which has been used in the conventionally known coatings, adhesives, polyurethane synthesis and the like may be used. These polyisocyanate compounds are trade names such as Takenate (manufactured by Takeda Pharmaceutical), Burnock (manufactured by Dainippon Ink and Chemicals), Coronate (manufactured by Nippon Polyurethane), Duranate (manufactured by Asahi Kasei Kogyo), and Dismodur (manufactured by Bayer). It can be obtained and used in the present invention. The above-mentioned method for producing heat-resistant fine particles may be any method, but a preferable method is a non-solvent for the fine particles to be produced, but the raw material polyisocyanate and the hydroxyl group-containing resin are dissolved in an organic solvent which is well dissolved. To a solution of polyisocyanate
It can be obtained by dropping an organic solvent solution of a hydroxyl group-containing resin while appropriately adjusting the temperature, and reacting both under conditions where polyisocyanate is always excessive. The organic solvent used in the reaction can be easily prepared by mixing organic solvents such as acetone, methyl ethyl ketone, toluene, xylene, ethyl acetate, acetonitrile and dimethylformamide at an appropriate ratio.

The amount of polyisocyanate used is determined by the proportion of the hydroxyl group-containing resin to be micronized. When the total amount of resin is micronized, N with the resin is used.
The CO / OH ratio is about 1.2 to 2.0. When 50% by weight of the resin is made into fine particles, the NCO / OH ratio is 1/2 as a whole as a whole, but actually they are synthesized by the above dropping method, and thus they react with each other. The ratio NCO / OH of the resin and the polyisocyanate is the same as in the case of reacting the entire amount. In this way, the resin particles can be made in any proportion of the hydroxyl group-containing resin. In the most preferred embodiment of the present invention, in the above production method, a part of the hydroxyl group-containing resin is reacted with polyisocyanate in an organic solvent to precipitate as fine particles, and the unreacted or insufficiently reacted resin is brought into a dissolved state. Dissolve and disperse. In this case, the generated fine particles are not separated once, and the dissolved dispersion is used as a varnish according to the purpose of use, and other necessary additives such as other known binder resins, lubricants, antistatic agents, etc. Can be added for use. In this way, the unreacted or incompletely reacted thermoplastic resin acts as a protective colloid, and the fine particles are extremely fine and uniformly and stably dispersed. The process can be omitted. Of course, the above fine particles can be used once separated from the organic solvent, but in this case, the fine particles are prevented from secondary aggregation,
It is preferable to use the fine particles in a wet state with a solvent and re-disperse them without drying. The resin fine particles of the present invention obtained as described above are usually 0.1 to 5 according to the production conditions.
It has an average particle size of μm, its particle size distribution is very narrow and the particle diameters are very well aligned.

Next, an example in which the resin fine particles and varnish of the present invention are used for forming a backside heat-resistant layer of a thermal transfer sheet will be described, but the present invention is not limited to these applications and is useful for various other applications. is there. The base sheet used in the thermal transfer sheet may be any one as long as it has a conventionally known degree of heat resistance and strength, for example, 0.5 to
Paper having a thickness of about 50 μm, preferably about 3 to 10 μm, various processed papers, polyester film, polystyrene film, polypropylene film, polysulfone film,
An aramid film, a polycarbonate film, a polyvinyl alcohol film, cellophane, etc., and a polyester film is particularly preferable. These substrate sheets may be of single-wafer type or continuous film and are not particularly limited. Among these, polyethylene terephthalate film is particularly preferable,
It is also preferable to form an adhesive layer on one side or both sides of the film, if necessary.

The heat resistant slipping layer formed on one surface of the base sheet is formed of the resin fine particles of the present invention and a binder. In the most preferred embodiment, in the above-mentioned production method, a part of the hydroxyl group-containing resin is reacted with polyisocyanate in an organic solvent to precipitate as fine particles, and an unreacted or insufficiently reacted resin is a dissolved dispersion liquid. To use as. Other well-known binder resins, lubricants, antistatic agents, etc. can be added to this dissolved / dispersed liquid to be used as a coating liquid for forming the heat resistant slipping layer. In this way, the unreacted or incompletely reacted thermoplastic resin acts as a protective colloid, and the fine particles are extremely fine and uniformly and stably dispersed. The process can be omitted.

In forming a heat resistant slipping layer from the above materials, a heat release agent or a lubricant such as wax, higher fatty acid amide, ester or surfactant for the purpose of improving the slip property of the heat resistant slipping layer. An organic powder such as an antistatic agent or a fluororesin, and inorganic particles such as silica, clay, talc, calcium carbonate and the like can be included as necessary. Further, in order to improve the antistatic property of the resulting thermal transfer sheet, an antistatic agent such as a surfactant or a conductive agent such as carbon black may be added. To form the heat resistant slipping layer, the coating solution as described above is adjusted to an appropriate viscosity and solid content with an appropriate solvent such as acetone, methyl ethyl ketone, toluene and xylene, if necessary, and the coating solution is gravure-coated. It is formed by coating with a conventional coating means such as a coater, a roll coater, or a wire bar and drying. The coating amount, that is, the thickness of the heat resistant slipping layer is also important and is 5.0 g / m ² or less, preferably 0.1 to 1.0, based on the solid content.
A heat resistant slipping layer having sufficient performance can be formed with a thickness of g / m ² . In the present invention, after formation of the heat resistant slipping layer, if unreacted isocyanate groups remain in the layer, it is preferable to perform sufficient aging treatment after forming the layer. By such treatment, the heat resistant slipping layer has a pencil hardness of H
The hardness is about 2H. It is also effective to form a primer layer made of polyurethane resin or the like prior to forming the heat resistant slipping layer.

As the coloring material layer formed on one surface of the base sheet, a layer containing a sublimable dye is formed in the case of a sublimation type thermal transfer sheet, and on the other hand, in the case of a heat melting type thermal transfer sheet. Forms a wax ink layer colored with a pigment.
The case of a sublimation type thermal transfer sheet will be described below as a typical example, but the present invention is not limited to the sublimation type thermal transfer sheet. As the dye used in the dye layer, any of the dyes used in conventionally known thermal transfer sheets can be effectively used and is not particularly limited. For example, some preferred dyes include red dyes such as MS Red G, Macrol
ex Red Violet R, CeresRed7B, Samaron Red HBSL, Reso
lin Red F3BS and the like, and as the yellow dye,
Holon Brilliant Yellow 6GL, PTY-52, Macrolex Yellow 6G, and the like, and blue dyes such as Kayaset Blue 714, Waxolin Blue AP-FW, Holon Brilliant Blue SR, and MS Blue 100.

Preferred binder resins for carrying the above dyes are exemplified by cellulose resins such as ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, cellulose acetate butyrate, polyvinyl resins. Alcohol, polyvinyl acetate,
Examples thereof include vinyl resins such as polyvinyl butyral, polyvinyl acetal and polyvinyl pyrrolidone, acrylic resins such as poly (meth) acrylate and poly (meth) acrylamide, polyurethane resins, polyamide resins and polyester resins. Among them, cellulose-based, vinyl-based, acrylic-based, polyurethane-based, polyester-based resins and the like are preferable from the viewpoint of heat resistance and dye migration.

The dye layer is prepared by dissolving one of the above-mentioned base sheet and the above-mentioned dye and binder, if necessary, with additives such as a release agent, dissolved in a suitable organic solvent. Or a dispersion dispersed in an organic solvent or water,
For example, it can be formed by applying and drying by a forming means such as a gravure printing method, a screen printing method, and a reverse roll coating method using a gravure plate. The dye layer thus formed has a thickness of about 0.2 to 5.0 μm, preferably about 0.4 to 2.0 μm, and the sublimable dye in the dye layer contains 5% by weight of the dye layer. Suitably it is present in an amount of ˜90% by weight, preferably 10 to 70% by weight. The dye layer to be formed is formed by selecting one color from the dyes when the desired image is a mono-color image, and when the desired image is a full-color image, for example, a suitable cyan, magenta and Yellow (and optionally black) is selected to form yellow, magenta and cyan (and optionally black) dye layers.

The image-receiving sheet used for forming an image using the thermal transfer sheet as described above may be any image-receiving sheet as long as its recording surface has dye receptivity to the above-mentioned dye, and Paper, metal, which does not have dye receptivity
In the case of glass or synthetic resin, a dye receiving layer may be formed on at least one surface thereof. In the case of a heat-melting type heat transfer sheet, the material to be transferred is not particularly limited, and may be ordinary paper or plastic film.
A known thermal transfer printer can be used as it is as a printer used when performing thermal transfer using the thermal transfer sheet and the image receiving sheet as described above, and is not particularly limited. Although the present invention has been described above with reference to preferred embodiments, the resin fine particles and varnish of the present invention are not limited to the above applications, and for example, in various applications such as paints, printing inks, molding resins, and surface treatment agents. Extender, extender pigment,
Needless to say, it can be used for the purpose of a filler, a heat resistance agent, a lubricant, a matting agent and the like.

[0017]

EXAMPLES Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. In the text, “part” or “%” is based on weight unless otherwise specified. Example 1 (Synthesis of varnish containing heat-resistant fine particles) While stirring 30 parts of a mixed solvent (methyl ethyl ketone / toluene = 1/1) containing 26 parts of polyisocyanate (Coronate 2030, made by Nippon Polyurethane), acetoacetal resin was added therein. 5% of (KS-5, Sekisui Chemical)
About 200 parts of a solution (solvent: methyl ethyl ketone / toluene / ethanol = 47.5 / 47.5 / 5) at 30 ° C.
The solution was added dropwise over a period of time, and the reaction was continued for 10 hours.
A part of the obtained emulsion was sampled, coated on a polyethylene terephthalate film and dried to obtain a coating film. When the surface of the obtained coating film was observed with a scanning electron microscope, substantially spherical particles having a diameter of about 0.8 μm to 3 μm were confirmed. Further, the obtained emulsion was filtered, separated into particles and varnish, and the weight of the acetoacetal resin converted into particles was determined to be 80 to 90%.

Example 2 (Synthesis of varnish containing heat-resistant fine particles) While stirring 38 parts of a mixed solvent (methyl ethyl ketone / toluene = 1/1) containing 28 parts of polyisocyanate (Takenate D218, manufactured by Takeda Pharmaceutical Co., Ltd.), 5% solution of acetoacetal resin (KS-8, manufactured by Sekisui Chemical Co., Ltd.) (solvent: methyl ethyl ketone / toluene / ethanol =
200 parts of 47.5 / 47.5 / 5) was added dropwise at 30 ° C. over about 3 hours, and the reaction was continued for 10 hours. A part of the obtained emulsion was sampled, coated and dried on a polyethylene terephthalate film to obtain a coating film. When the obtained coating film surface was observed with a scanning electron microscope,
Almost spherical particles having a diameter of about 1.0 μm to 4 μm were confirmed.

Example 3 (Synthesis of varnish containing heat-resistant fine particles) While stirring 38 parts of a mixed solvent (methyl ethyl ketone / toluene = 1/1) containing 28 parts of polyisocyanate (Takenate D212, manufactured by Takeda Pharmaceutical Co., Ltd.), A 5% solution of acetoacetal resin (KS-1, Sekisui Chemical Co., Ltd.) (solvent: methyl ethyl ketone / toluene / ethanol =
200 parts of 47.5 / 47.5 / 5) was added dropwise at 30 ° C. over about 3 hours, and the reaction was continued for 10 hours. A part of the obtained emulsion was sampled, coated and dried on a polyethylene terephthalate film to obtain a coating film. When the obtained coating film surface was observed with a scanning electron microscope,
Almost spherical particles having a diameter of about 0.7 μm to 3 μm were confirmed.

Inks A to E for heat resistant slipping layers having the following compositions were prepared. Ink A for heat resistant slipping layer: Butyral resin BX-1, manufactured by Shin-Etsu Chemical 62.5 parts Isocyanate curing agent (Barnock D750-45, manufactured by Dainippon Ink) 26.5 parts Containing heat resistant fine particles of Example 1 Varnish 10.0 parts ・ Prysurf A208S 4.0 parts ・ Phosphanol RD720 1.5 parts ・ Mixed solvent (methyl ethyl ketone / toluene = 1/1) 38.0 parts (solid content 15%)

Ink B for heat resistant slipping layer: • Butyral resin (BX-1, manufactured by Shin-Etsu Chemical) 62.5 parts • Isocyanate curing agent (Takenate D218, manufactured by Takeda Chemical Industries) 26.5 parts • Heat resistance of Example 2 Varnish containing fine particulates 10.0 parts-Elegan A2000S 3.0 parts-Reodol SP-O30 2.5 parts-Mixed solvent (methyl ethyl ketone / toluene = 1/1) 38.0 parts (solid content 15%)

[0022]Ink C for heat resistant slipping layer: -Acetoacetal resin (KS-5, manufactured by Shin-Etsu Chemical Co., Ltd.) 100.0 parts-Heat-resistant fine particle-containing varnish of Example 3 10.0 parts-Fosphanol RD720 1.8 parts (solid content 7%) Ink D for heat resistant slipping layer (comparative example): -Butyral resin (BX-1, manufactured by Shin-Etsu Chemical) 62.5 parts-Isocyanate curing agent (Barnock D750-45, manufactured by Dainippon Ink) 26.5 parts-Nylon powder (Orgasol, manufactured by Rilsan Japan) 1.0 part -Plysurf A208S 4.0 parts-Fosphanol RD720 1.5 parts-Mixed solvent (methyl ethyl ketone / toluene = 1/1) 47.0 parts (solid content 15%)

Ink E for heat resistant slipping layer (comparative example): acetoacetal resin (KS-5, manufactured by Shin-Etsu Chemical) 100.0 parts Silica (Aerosil R972, manufactured by Nippon Aerosil) 1.0 part Phosphanol RD720 2.0 parts (solid content 8%) Use example 1 Each ink A was dried on one side of a polyethylene terephthalate substrate sheet (thickness 4.5 μm, made of diamond foil) using a miya bar * 5 to dry 1. After application, the coating was dried with warm air to a thickness of 0 μm, and further heated in an oven at 60 ° C. for 2 days for curing treatment to form a heat resistant slipping layer. Next, the following ink for forming a dye layer was applied to the opposite surface of the heat resistant slipping layer by gravure printing so that the thickness when dried was 1.0 g / m ² , and dried to obtain a thermal transfer sheet. Dye layer forming ink: CI Solvent Blue 22 5.50 parts Acetoacetal resin 3.00 parts Methyl ethyl ketone 22.54 parts Toluene 68.18 parts

Use Example 2 Heat-resistant slip layer inks B to E were used in place of the heat-resistant slip layer ink A in Use Example 1, and other thermal transfer sheets were obtained in the same manner as in Use Example 1. The above-mentioned thermal transfer sheet is overlaid on a conventionally used thermal transfer sheet, and transfer is performed using a transfer recording device under the following transfer conditions, whereby the thermal head and the thermal transfer sheet are fused and wrinkles are generated, and dye transferability (60 Table 1 below shows the results of the examination at 210 ° C. and 210 g / m ² for 1 day. Transfer conditions : pulse width: 1 ms Recording period: 2.0 ms / line Recording energy: 3.0 J / cm ²

[Table 1] Evaluation method: Generation of fusion and wrinkles: By visual observation. Dye transferability: By visual observation. ○: No transfer △: Some transfer is recognized ○: Significant transfer

[0025]

[Effect] According to the present invention as described above, by forming a reaction product of a hydroxyl group-containing thermoplastic resin and polyisocyanate into fine particles, it is useful as an additive for various materials, and particularly dispersibility and heat resistance. Provided are resin fine particles which are excellent in, etc., are easily dispersible in a solvent and have a uniform particle size distribution, and a varnish containing the particles. In addition, as an example, by using the above resin fine particles, excellent coating properties, slip properties, etc., good running performance of the thermal head, and no slag buildup on the thermal head or abrasion of the thermal head are obtained. A thermal transfer sheet having a heat resistant slipping layer is provided.

Claims (7)

[Claims] 1. Resin fine particles comprising a reaction product of a hydroxyl group-containing thermoplastic resin and polyisocyanate. 2. The resin fine particles according to claim 1, wherein the hydroxyl group-containing thermoplastic resin is a polyvinyl acetal resin. 3. The resin fine particles according to claim 1, wherein the acetal resin is polyvinyl butyral or polyvinyl acetoacetal. 4. A varnish comprising the resin fine particles according to claim 1, a thermoplastic resin and a liquid medium. 5. The varnish according to claim 4, wherein the resin fine particles according to claim 4 and the thermoplastic resin forming the fine particles are the same or similar resins. 6. A method for producing fine resin particles, which comprises dropping an organic solvent solution of a hydroxyl group-containing thermoplastic resin into an organic solvent solution of polyisocyanate to precipitate a reaction product as fine particles. 7. The method for producing resin fine particles according to claim 6, wherein the organic solvent of the reaction mixture is a good solvent for the polyisocyanate and the hydroxyl group-containing thermoplastic resin and a poor solvent for the reaction product.