JP3716015B2 - Polystyrene molded product with pattern and method for producing the same - Google Patents

Description

【００２９】
【発明の効果】
以上説明したとおり、本発明によれば、絵柄層の密着性に優れ、かつ耐クレージング性及び耐油性に優れた、絵柄付ポリスチレン成形品及びその成形品の製造方法を提供することができる。
また、本発明は、ＡＳ樹脂からの代替が可能となり、コストダウンが達成される。
【図面の簡単な説明】
【図１】本発明で用いる熱転写箔の一実施態様を示す断面図である。
【符号の説明】
１・・・基体シート
２・・・離形層
３・・・絵柄層
４・・・アンカー層
５・・・接着層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a patterned polystyrene molded article and a method for producing the same. More specifically, the present invention relates to a polystyrene molded article with a pattern which is excellent in adhesion of a pattern layer, crazing resistance after transfer and oil resistance, and a method for producing the molded article.
[0002]
[Prior art]
In general, as a method of decorating a plastic molded product and obtaining a plastic molded product with a pattern, for example, while pressing a transfer foil having a pattern layer on a base molded product using a heating body such as a heating roll or a hot stamper The mainstream method is to heat and adhere the pattern layer to the surface of the molded product. The thermal transfer foil is composed of a base sheet, a release layer, a pattern layer, an adhesive layer, etc., and the adhesive layer has no tackiness at room temperature, and is given tackiness by heating, and then solidifies completely. It has adhesiveness. Since this method is simple in operation and excellent in decorating properties, it is widely used particularly in home appliances such as refrigerator interior parts, and packaging containers such as food or cosmetic containers.
[0003]
Conventionally, a resin with high heat resistance and oil resistance, such as acrylonitrile / styrene copolymer resin (AS resin), has been used as a material for a base molded product for a transparent molded plastic product.
In recent years, there has been a demand to replace AS resin with polystyrene due to the demand for cost reduction. However, when heat transfer is performed to a molded product whose base material is polystyrene to form a molded product with a pattern, the heat during thermal transfer reaches the molded product. For this reason, crazing that can be observed with the naked eye occurs, and the commercial value of the product is impaired.
[0004]
Examples of a method for preventing crazing from being thermally transferred to a polystyrene molded product include a method for lowering the heating temperature during thermal transfer and a method for shortening the time for pressing the transfer foil while heating. According to the method, it is difficult to obtain a sufficient adhesion strength of the pattern layer, and there is a problem that the pattern layer is easily scratched due to an external frictional force or the like.
[0005]
In addition, when the pattern layer is composed of two or more layers (two or more colors), there is a problem in that the unevenness of the pattern layer becomes intense and the adhesiveness further decreases.
[0006]
Japanese Patent Application Laid-Open No. 6-305094 discloses that a transfer foil composed of a resin layer having a specific glass transition temperature (Tg) is used for an adhesive layer, and the heating time while pressing the transfer foil is within a specific range. A technique for obtaining a polystyrene-based resin molded product with a picture that is excellent in adhesion of the picture layer and does not generate crazing after transfer is disclosed.
However, according to this method, crazing does not occur when left at room temperature after thermal transfer, but when oil film such as butter, salad oil, and hand fat adheres for some reason, crazing occurs from that part. As a result, the oil resistance is poor.
[0007]
[Problems to be solved by the invention]
In such a situation, the problem to be solved by the present invention is that the pattern layer has excellent adhesion, and crazing does not occur even when oil or grease adheres during or after thermal transfer, and the pattern has excellent oil resistance. The point lies in providing a polystyrene molded article and a method for producing the molded article.
[0008]
[Means for Solving the Problems]
That is, the present invention relates to a thermal transfer foil comprising at least a picture layer and an adhesive layer having a glass transition temperature of 10 to 35 ° C. on the surface of a molded article made of polystyrene (A) having a Vicat softening point of 90 ° C. or higher. (B) is a polystyrene molded product with a pattern formed by close contact, and with a pattern formed by thermal transfer under the conditions of the following formula and the base material surface temperature of the molded product at the time of thermal transfer is 55 to 85 ° C. A polystyrene molded article is provided.
A _Tg <T <H
A _Tg (° C.): Glass transition temperature of adhesive layer of thermal transfer foil T (° C.): Base material surface temperature of molded product during thermal transfer H (° C.): Heat distortion temperature of polystyrene
In addition, the present invention is a method for producing a polystyrene molded article with a pattern by heating while pressing the thermal transfer foil (B) on the surface of a molded article made of polystyrene (A), and bringing the pattern layer into close contact with the substrate. in, Vicat softening point of 90 ° C. or more polystyrene (a) and, with the picture layer and the thermal transfer foil having a glass transition temperature comprising the adhesive layer is 10 to 35 ° C. (B), under the conditions of the following formula and The present invention provides a method for producing a patterned polystyrene molded product, wherein thermal transfer is performed under the condition that the substrate surface temperature of the molded product during thermal transfer is 55 to 85 ° C.
A _Tg <T <H
A _Tg (° C.): Glass transition temperature of adhesive layer of thermal transfer foil T (° C.): Base material surface temperature of molded product during thermal transfer H (° C.): Heat distortion temperature of polystyrene The present invention will be described in detail below.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The polystyrene that is the base resin of the molded article with a pattern of the present invention has a Vicat softening point of 90 ° C. or higher, preferably 95 to 105 ° C. When the base material is a resin having an excessive Vicat softening point, the crazing resistance is poor. Here, the upper limit of 105 ° C. is the highest known Vicat softening point of polystyrene.
Here, the Vicat softening point is measured according to ASTM-D1525. A flat test piece having a thickness is applied to a needle having a constant cross-sectional area, and a predetermined ascending value is obtained. This is the temperature at which the needle has entered a specified depth under the temperature speed.
The method for producing a molded product made of polystyrene is not particularly limited, and examples thereof include an extrusion vacuum / pressure forming method and an injection molding method.
[0011]
The thermal transfer foil of the present invention comprises at least a pattern layer and an adhesive layer. For example, (1) a substrate sheet, a release layer, a pattern layer, an adhesive layer and a metal vapor deposition layer, (2) a substrate sheet, a release layer Examples include a layer, a pattern layer, an anchor layer, and an adhesive layer.
In addition, the thermal transfer foil of the present invention is preferably a thermal transfer foil including two or more pattern layers and an adhesive layer, and including an anchor layer between the pattern layer and the adhesive layer.
Specifically, as shown in FIG. 1, the thermal transfer foil includes a base sheet 1, a release layer 2, a pattern layer 3 including two layers, an anchor layer 4, and an adhesive layer 5.
FIG. 1 is a cross-sectional view showing one embodiment of a thermal transfer foil used in the present invention.
The thickness of the thermal transfer foil of the present invention is not limited at all, and is, for example, 10 to 50 μm.
[0012]
The adhesive layer of the thermal transfer foil is obtained by adding, for example, an adhesion imparting agent or a plasticizer to a base resin.
As the base resin, a resin having a relatively low glass transition temperature, for example, a styrene resin, an acrylic resin, an amide resin, a vinyl chloride resin, or a mixture of one or more resins is used. Among these, acrylic resins are preferable.
In addition, a resin having a functional group such as an epoxy group or a hydroxyl group can be added to the resin serving as the base of the adhesive layer. By adding these resins, it is possible to obtain an adhesive layer that is further excellent in the adhesion of the pattern layer. Examples of the resin having a functional group include epoxy resins such as bisphenol A epoxy resin and cresol novolac epoxy resin, acrylate resin, and vinyl acetate resin.
The adhesive layer of the thermal transfer foil used in the present invention is preferably made of a mixture of acrylic resin and epoxy resin.
[0013]
The anchor layer of the thermal transfer foil is provided between the pattern layer and the adhesive layer, and is selected from, for example, acrylic resin, epoxy resin, polyamide resin, chlorinated polyolefin resin, vinyl chloride resin, and vinyl acetate resin. At least one resin is used. Among these, acrylic resins are preferable.
The anchor layer is a resin having adhesiveness between the release layer, the pattern layer, and the adhesive layer.
The thickness of the anchor layer is not limited at all, and is usually 1 to 10 μm.
[0014]
Furthermore, since the transfer temperature of the present invention is lower than that of ordinary thermal transfer and the Tg of the adhesive layer is low, it is better to take sufficient blocking measures. By mixing and dispersing silica, calcium carbonate, polyethylene wax or the like in the adhesive layer, blocking resistance is improved.
Conventional substrates, release layers, and pattern layers are used, and if the Tg of the adhesive satisfies the formula of claim 1, a pigment foil, a pattern foil, a metal vapor-deposited foil, and the like are known. A configuration may be used.
[0015]
In the present invention, the substrate surface temperature (T (° C.)) of the molded product at the time of thermal transfer, the glass transition temperature (A _Tg (° C.)) of the adhesive layer of the thermal transfer foil, and the heat deformation temperature (H (° C.)), thermal transfer may be performed so as to satisfy the condition of the following formula.
A _Tg <T <H
When the substrate surface temperature in thermal transfer is excessive, the crazing resistance is inferior, and when it is excessively low, the adhesion of the pattern layer is inferior.
Preferably, the thermal transfer foil (B) may be thermally transferred under the conditions that the glass transition temperature of the adhesive layer is 10 to 35 ° C. and the substrate surface temperature of the molded product at the time of thermal transfer is 55 to 85 ° C.
[0016]
Here, the base material surface temperature of the molded product at the time of thermal transfer is the base material when heating the thermal transfer foil having a pattern layer against the base molded product using a heating body such as a heating roll or a hot stamper. It is the maximum value of the surface temperature of the molded product, and can be measured by the following method. That is, it can be obtained as the instantaneous maximum temperature indicated by the thermolabel when the thermolabel is sandwiched between the base molded product and the thermal transfer foil and heated.
[0017]
The glass transition temperature of the adhesive layer of the thermal transfer foil can be obtained by differential scanning heat (DSC) measurement. For example, the differential heat in the range of −100 to 100 ° C. is measured with a 7700 type DSC apparatus manufactured by PERKIN ELMER (Perkin Elmer). It can be determined by doing. Details are described in, for example, the book “New Experimental Chemistry Course 2 (3. Thermal Analysis Measurement)” (edited by Chemical Society of Japan, published by Maruzensha, 1984, pp. 87-122).
The heat distortion temperature of polystyrene is measured according to ASTM-D648, and is determined by applying a constant load to a needle having a certain roundness on a test piece having a certain width, thickness and length. This is the temperature at which a test piece is deformed at a constant temperature.
[0018]
【Example】
EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to an Example.
Of the evaluation items, items other than those described above were carried out as follows.
(1) Adhesiveness of pattern layer Using a 24 mm width cellophane tape manufactured by Nichiban Co., Ltd., an instantaneous peel test was performed. The residual of the pattern layer after the instantaneous peel test was judged visually, and the adhesion was evaluated by the residual ratio of the pattern layer.
The remaining rate of 100% was rated as ◯, and the others were marked as x.
(2) Crazing resistance After thermal transfer, the presence or absence of crazing after the lapse of 14 days was judged visually by leaving at room temperature (25 ° C.). The case where crazing did not occur was marked with ○, and the case where crazing occurred was marked with ×.
(3) Neosoft Margarine made by Snow Brand Co., Ltd. was applied to the oil-resistant thermal transfer portion, and the presence or absence of crazing after 14 days was visually determined.
The case where crazing did not occur was marked with ○, and the case where crazing occurred was marked with ×.
[0019]
Example 1
A 150 mm × 150 mm × 2 mm flat plate using a J150 type injection molding machine (manufactured by Nippon Steel), polystyrene (Sumitomo Chemical Co., Ltd. GPPS; ST970) having a Vicat softening point of 102 ° C. and a heating deformation temperature of 90 ° C. A shaped molded product was obtained. An adhesive layer (glass transition temperature 20 ° C.) comprising a mixture of 100 parts by weight of acrylic resin having a glass transition temperature of 15 ° C. and 100 parts by weight of acrylic resin having a glass transition temperature of 25 ° C. Using the RT-300 type roll thermal transfer machine manufactured by Navitas Co., Ltd., the roll (silicon rubber) temperature is 160 ° C., the roll speed is 50 mm / sec, and the transfer pressure is 1.5 mm. Thermally transferred. At this time, the surface temperature of the base material molded product was 75 ° C. The results are shown in Table 1.
[0020]
Example 2
100 parts by weight of an acrylic resin having a glass transition temperature of 15 ° C., 100 parts by weight of an acrylic resin having a glass transition temperature of 25 ° C., and 30 parts by weight of a bisphenol-based epoxy resin containing an epoxy group for improving adhesion The same procedure as in Example 1 was performed except that a thermal transfer foil containing an adhesive layer (glass transition temperature 30 ° C.) made of a mixture was used. The results are shown in Table 1.
[0021]
Example 3
A 150 mm × 150 mm × 2 mm flat plate using a J150 type injection molding machine (manufactured by Nippon Steel), polystyrene (Sumitomo Chemical Co., Ltd. GPPS; ST970) having a Vicat softening point of 102 ° C. and a heating deformation temperature of 90 ° C. A shaped molded product was obtained. In order to improve adhesiveness, 100 parts by weight of an acrylic resin having a glass layer transition temperature of 15 ° C. and 70 parts by weight of an acrylic resin having a glass transition temperature of 25 ° C. An adhesive layer (glass transition temperature 35 ° C.) composed of a mixture of 60 parts by weight of a bisphenol-based epoxy resin containing an epoxy group, and a thermal transfer foil containing an acrylic resin between the pattern layer and the adhesive layer, ) Using an RT-300 roll thermal transfer machine manufactured by the same method, thermal transfer was performed at a roll (silicon rubber) temperature of 160 ° C., a roll speed of 50 mm / second, and a transfer pressure of 1.5 mm. At this time, the surface temperature of the base material molded product was 75 ° C. The results are shown in Table 1.
[0022]
Comparative Example 1
A 150 mm × 150 mm × 2 mm flat plate having a Vicat softening point of 88 ° C. and a heat distortion temperature of 80 ° C. using a JPS type injection molding machine manufactured by Nippon Steel Co., Ltd. (GPPS manufactured by Sumitomo Chemical Co., Ltd .; ST730). A shaped molded product was obtained. A thermal transfer foil containing an image layer consisting of two layers and an adhesive layer having a glass transition temperature of 60 ° C. was used for this base molded article, the roll (silicon rubber) temperature was 190 ° C., and other conditions were the same as in Example 1. Thermal transfer was performed in the same manner. At this time, the surface temperature of the base material molded product was 90 ° C. The results are shown in Table 1.
[0023]
Comparative Example 2
This was carried out in the same manner as in Example 1 except that a thermal transfer foil containing a pattern layer composed of two layers and an adhesive layer having a glass transition temperature of 60 ° C. was used, and the roll (silicon rubber) temperature was thermally transferred at 190 ° C. At this time, the surface temperature of the base material molded product was 90 ° C. The results are shown in Table 1.
[0024]
Comparative Example 3
This was carried out in the same manner as in Example 1 except that a thermal transfer foil containing a pattern layer composed of two layers and an adhesive layer having a glass transition temperature of 60 ° C. was used and the thermal transfer was performed at a roll speed of 70 mm / second. At this time, the surface temperature of the base material molded product was 45 ° C. The results are shown in Table 1.
[0025]
Comparative Example 4
It was carried out in the same manner as Comparative Example 1 except that a thermal transfer foil containing an image layer composed of two layers and an adhesive layer having a glass transition temperature of 20 ° C. was used and the thermal transfer was performed at a roll speed of 70 mm / sec. At this time, the surface temperature of the base material molded product was 70 ° C. The results are shown in Table 1.
[0026]
Comparative Example 5
Example 1 was performed except that a thermal transfer foil containing a pattern layer composed of two layers and an adhesive layer having a glass transition temperature of 80 ° C. was used, and heat transfer was performed at a roll temperature of 210 ° C. and a roll speed of 50 mm / sec. It was. At this time, the surface temperature of the base material molded product was 100 ° C. The results are shown in Table 1.
[0027]
The following can be seen from the results. Examples 1 to 3 satisfying the conditions of the present invention show excellent results in all evaluation items.
On the other hand, Comparative Example 1 in which the Vicat softening point of the polystyrene resin of the base material molded article is too low and the base material surface temperature is too high is inferior in crazing resistance and oil resistance.
Comparative Example 2 in which the substrate surface temperature is excessive is inferior in oil resistance.
The comparative example 3 whose base-material surface temperature is too low is inferior to the adhesiveness of a pattern layer.
The comparative example 4 whose Vicat softening point of base resin is too small is inferior to crazing resistance and oil resistance.
Comparative Example 5 in which the substrate surface temperature is excessive is inferior in oil resistance.
[0028]
[Table 1]

[0029]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a polystyrene molded article with a pattern and a method for producing the molded article, which are excellent in the adhesion of the pattern layer and excellent in crazing resistance and oil resistance.
In addition, the present invention can be replaced with AS resin, and cost reduction is achieved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing one embodiment of a thermal transfer foil used in the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Base sheet 2 ... Release layer 3 ... Picture layer 4 ... Anchor layer 5 ... Adhesive layer

Claims (10)

A thermal transfer foil (B) comprising at least a pattern layer and an adhesive layer having a glass transition temperature of 10 to 35 ° C. is in close contact with the surface of a molded article made of polystyrene (A) having a Vicat softening point of 90 ° C. or higher. A polystyrene molded product with a pattern, which is obtained by thermal transfer under the following formula and under the condition that the substrate surface temperature of the molded product at the time of thermal transfer is 55 to 85 ° C.
A _Tg <T <H
A _Tg (° C.): Glass transition temperature of adhesive layer of thermal transfer foil T (° C.): Base material surface temperature of molded product during thermal transfer H (° C.): Heat distortion temperature of polystyrene   The polystyrene molded article with a picture according to claim 1, wherein the thermal transfer foil (B) is a thermal transfer foil containing two or more picture layers and an adhesive layer, and an anchor layer between the picture layer and the adhesive layer.   The polystyrene molded article with a pattern according to claim 1, wherein the adhesive layer of the thermal transfer foil (B) is made of an acrylic resin.   The polystyrene molded article with a picture according to claim 1, wherein the adhesive layer of the thermal transfer foil (B) is made of a mixture of an acrylic resin and an epoxy resin.   The polystyrene molded article with a pattern according to claim 2, wherein the anchor layer of the thermal transfer foil (B) is made of an acrylic resin. In the method of manufacturing a polystyrene molded article with a pattern by heating the thermal transfer foil (B) while pressing the thermal transfer foil (B) on the surface of the molded article made of polystyrene (A), the Vicat softening point is Using a thermal transfer foil (B) comprising at least 90 ° C. polystyrene (A) and an adhesive layer having at least a pattern layer and a glass transition temperature of 10 to 35 ° C., a molded product under the conditions of the following formula and during thermal transfer A method for producing a patterned polystyrene molded article, wherein the substrate surface temperature is thermally transferred under the condition of 55 to 85 ° C.
A _Tg <T <H
A _Tg (° C.): Glass transition temperature of adhesive layer of thermal transfer foil T (° C.): Base material surface temperature of molded product during thermal transfer H (° C.): Heat distortion temperature of polystyrene   The method for producing a patterned polystyrene molded article according to claim 6, wherein the thermal transfer foil (B) is a thermal transfer foil including two or more pattern layers and an adhesive layer, and an anchor layer between the pattern layer and the adhesive layer.   The method for producing a patterned polystyrene molded article according to claim 6, wherein the adhesive layer of the thermal transfer foil (B) is made of an acrylic resin.   The method for producing a patterned polystyrene molded article according to claim 6, wherein the adhesive layer of the thermal transfer foil (B) comprises a mixture of an acrylic resin and an epoxy resin.   The method for producing a patterned polystyrene molded article according to claim 7, wherein the anchor layer of the thermal transfer foil (B) is made of an acrylic resin.

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