JP3912155B2 - Thermoforming method of resin film and manufacturing method of decorative resin molding - Google Patents

Description

【００４４】
実施例５
以上の各例で作製した予備賦形加飾フィルムを用いて射出成形体を製造した。すなわち、各例で予備賦形した加飾フィルムを、形状を合わせて作製された射出成形用金型キャビティーの内面に挿入し、金型の型締めを行った後、実施例１及び２、比較例１並びに参考例１についてはＡＢＳ樹脂層側に、また実施例３については着色アクリル樹脂層側に、それぞれＡＢＳ樹脂を射出して、射出樹脂の表面に加飾フィルムが一体貼合された成形体を得た。一方、実施例４については、そのポリプロピレン系樹脂層側にポリプロピレン樹脂を射出して、同様の成形体を得た。その結果、予備賦形時に表面不良が事実上発生しなかった実施例１〜４及び参考例１については、表面の意匠性の高い成形体が得られたのに対し、予備賦形時に表面不良が発生した比較例１については、表面不良が残存したままで、外観不良を有する成形体となった。
【００４５】
以上のように、フィルムの加熱前に予備乾燥を行った参考例１では、発泡状の表面不良が発生しないが、予備乾燥なしで室温から成形温度まで ０.０１０％／秒の水分減少速度で加熱した比較例１では、表面不良が多数発生する。これに対し、室温から成形温度まで加熱する際の水分減少速度を ０.０１０％／秒より小さくした実施例１〜４では、予備乾燥を省略しながら、良好な表面状態の賦形品が得られる。
【００４６】
【発明の効果】
本発明によれば、吸湿性の熱可塑性樹脂からなる層を少なくとも一層有する樹脂フィルムを賦形するための熱成形において、その樹脂フィルムを予備乾燥することなく、吸湿性樹脂層が吸湿した状態のままで、成形温度まで加熱する工程に付すことができる。そして、このように予備乾燥を省略しながら、良好な外観を有する賦形フィルム、さらにはそれを用いた外観良好な成形品を得ることができる。そのため、賦形フィルムの製造、さらにはそれを用いた成形品の製造において、工程の簡素化及び生産効率の向上が期待される。
【図面の簡単な説明】
【図１】実施例における成形前の加熱状態の概要を示すものであって、（Ａ）は加熱に用いたヒーターパネルの概要を示す平面図、（Ｂ）はヒーターパネルとフィルムの配置の概要を示す縦断面図である。
【符号の説明】
１……フィルム、
３，４……ヒーターパネル、
５……赤外線ヒーター、
７……クランプ。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermoforming method for shaping a resin film having at least one layer made of a hygroscopic thermoplastic resin. The present invention also relates to a method for producing a resin molded body in which the resin film thus shaped is integrally bonded to the surface.
[0002]
[Prior art]
Resin films are used in a variety of fields. Recently, as a printing alternative to molded products, resin films that have been printed or colored have been attracting attention, and the technology of integrally bonding them to the surface of molded products has attracted attention. Yes. Examples of the resin film used for decorating the surface of such a molded body include an acrylic resin film having a printing layer such as a pattern and characters, a laminated film of a transparent acrylic resin and a colored acrylic resin, and an acrylic film. There are laminated films of different types of resins such as acrylic resin / ABS (acrylonitrile-butadiene-styrene copolymer) resin and acrylic resin / polypropylene.
[0003]
When the decorative film is integrally bonded to the surface of the molded body, the film is pre-shaped by thermoforming such as vacuum forming or pressure forming, and then inserted into an injection mold or in-mold. In general, a method is used in which a preforming is performed by thermoforming such as vacuum forming in an injection mold having a forming function, and a thermoplastic resin is injected onto one side of the decorative film in that state. For example, Japanese Patent Laid-Open No. 2-503077 discloses that a layer containing an acrylic resin and a fluorinated polymer is used as a transparent surface layer to coat an automobile exterior part. Kaihei 10-279766 describes the use of an acrylic resin containing rubber particles as a decorative film for an injection molded article. Furthermore, JP-A-11-207896 and JP-A-2001-310427 are laminated films used for surface decoration, in which a polypropylene resin is disposed on the side (backing layer) on which the molten resin is injected. A laminated film is described.
[0004]
In the thermoforming of the decorative film that is performed prior to injecting the molten resin on one side of the decorative film, a method of heating the decorative film with a heater or contacting a hot plate is generally employed. Yes. However, acrylic resins, ABS resins, polycarbonate resins, and the like generally have hygroscopicity and absorb moisture into the resin over time. And if a decorating film is heated in the state which absorbed moisture, defects, such as foaming, will generate | occur | produce on the film surface. Therefore, it was necessary to perform preliminary drying before heating to the thermoforming temperature to remove moisture contained in the film.
[0005]
[Problems to be solved by the invention]
In thermoforming, which is a pre-shaping step, it is preferable from the viewpoint of simplifying the manufacturing process and improving production efficiency if the film can be heated directly from room temperature to the forming temperature without pre-drying.
[0006]
Accordingly, one of the objects of the present invention is to form a film comprising a hygroscopic resin or a film containing a hygroscopic resin layer without forming a pre-drying from the hygroscopic resin film in thermoforming. The object is to provide a method capable of obtaining a shaped product having a good appearance. Another object of the present invention is to obtain a shaped product having a good appearance without pre-drying by adding a device to the heating conditions for raising the film to the molding temperature. Furthermore, another object of the present invention is to produce a resin molded body having a good surface state by using the resin film thus shaped and integrally bonding it to the surface of a molded body made of another thermoplastic resin. There is to do.
[0007]
[Means for Solving the Problems]
As a result of diligent research under such a purpose, the present inventor, when heating the film to the thermoforming temperature, by setting the moisture reduction rate of the hygroscopic resin layer to an appropriate range, even if the moisture is absorbed. It was found that a shaped article having a good appearance can be obtained without pre-drying the film even if the film contains a hygroscopic resin layer. Based on this knowledge, various studies were further made to complete the present invention.
[0008]
That is, the present invention provides a resin film having at least one layer made of a hygroscopic thermoplastic resin, in a state where the moisture content in the hygroscopic resin layer is 0.25% by weight or more, in the hygroscopic resin layer. The present invention provides a method of heating to a molding temperature so that the water content decreases at a rate of 0.001 to 0.009% by weight / second, and then molding.
[0009]
Further, the present invention provides a resin film having at least one layer composed of a hygroscopic thermoplastic resin from a state where the moisture content in the hygroscopic resin layer is 0.25% by weight or more, the moisture in the hygroscopic resin layer. Is heated to a molding temperature so as to decrease at a rate of 0.001 to 0.009% by weight / second, then molded, and the resulting shaped film is placed on one surface of an injection mold to form a mold cavity. The present invention also provides a method for producing a resin molded body whose surface is decorated with the resin film by injecting a molten resin into a tee.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, a hygroscopic thermoplastic resin is the object of thermoforming. The hygroscopic resin referred to in this specification is a water absorption rate of 0.05% by weight or more when measured by Method A (method of measuring water absorption after being immersed in water at 23 ° C.) defined in JIS K 7209. Suppose that Examples of such hygroscopic resins include acrylic resins, ABS (acrylonitrile-butadiene-styrene copolymer) resins, and polycarbonate resins, but are not limited to these examples. On the other hand, polyolefin resins such as polypropylene, which is one of typical thermoplastic resins, usually do not exhibit hygroscopicity. Even if it is a mixed resin composition containing both a hygroscopic resin and a non-hygroscopic resin, if the water absorption rate of the whole mixture is the said range, it corresponds to the hygroscopic resin as used in this specification.
[0011]
The acrylic resin is a resin whose main component is a polymer derived from an ester of acrylic acid or methacrylic acid. In the present invention, a laminated film made of a hygroscopic resin or including a hygroscopic resin layer is an object of thermoforming. As the hygroscopic resin, a polymer mainly composed of an acrylic resin, particularly methyl methacrylate. (Usually called acrylic resin or methacrylic resin) is one of suitable ones. The acrylic resin may be, for example, a mixture of a fluorinated polymer as described in the above-mentioned Japanese National Publication No. 2-503077. Similarly, the above-mentioned Japanese Unexamined Patent Publication No. 8-323934 and Japanese Unexamined Patent Publication No. 10-279766. The rubber particles described in the publication may be blended.
[0012]
The film formed according to the present invention has at least one layer made of a hygroscopic resin, and may be a single-layer resin film made of a hygroscopic resin, or a plurality of films of the same type or different types. It may be a resin film having a multilayer structure composed of layers. Alternatively, a multilayer film having a multilayer structure in which a layer made of a hygroscopic resin and a layer made of a substantially non-hygroscopic resin are laminated may be used.
[0013]
In the case of a multilayer film, it is preferable in terms of design in the decorative state that an acrylic resin is used as a design surface, that is, the outermost layer when another thermoplastic resin is injected into one surface to form a molded body. . In particular, if a transparent acrylic resin is used as the design surface and a colored resin layer is arranged on the back side or printing is performed on the back side film, another thermoplastic resin is injected on the back side and integrally bonded. When it is done, it has a deep appearance as seen from the transparent acrylic resin film side and gives high designability. Examples of suitable multilayer films include those comprising a two-layer structure of transparent acrylic resin / colored acrylic resin, those comprising a two-layer structure of transparent acrylic resin / colored ABS resin, and transparent acrylic resin / colored acrylic resin. Examples thereof include those having a three-layer structure of / ABS resin and those having a four-layer structure of transparent acrylic resin / colored acrylic resin / adhesive / polypropylene resin.
[0014]
The total thickness of the resin film used for molding is generally about 25 to 1,000 μm, preferably 50 μm or more, more preferably 100 μm or more, and preferably 900 μm or less, more preferably 800 μm or less. is there. If the thickness of the resin film is too small, it is not preferable because it is inferior in design when used for decoration. On the other hand, if the thickness of the film is too large, shaping is difficult, which is not preferable.
[0015]
The resin film having at least one layer composed of the hygroscopic resin as described above is heated and molded to the molding temperature. At this time, in the present invention, the moisture in the hygroscopic resin layer is 0.001 to 0.009. Heat to decrease at a rate of weight% / second. The moisture reduction rate due to heating is obtained by calculating the moisture content of the hygroscopic resin layer before the start of heating and the moisture content of the hygroscopic resin layer immediately after the end of heating (in a state where the molding temperature has been reached). (Unit:% by weight) can be obtained by dividing by the time (seconds) from the start of heating until the surface temperature of the film reaches the molding temperature. The heating rate or the moisture reduction rate is not necessarily constant, and the moisture reduction rate averaged from the start of heating until reaching the molding temperature and finishing the heating may be within the above range.
[0016]
If the moisture reduction rate in the hygroscopic resin layer is heated so as to exceed 0.009% by weight / second, defects such as foaming are likely to occur in the preshaped object after molding, and as a result, the preshaped object is made of gold. When it is placed on one surface of the mold and injection molding of another thermoplastic resin is performed, the surface defect remains on the surface of the injection-molded film. On the other hand, it is impractical to heat the hygroscopic resin layer so that the water decrease rate is less than 0.001% by weight / second, because it takes a long time to raise the heating temperature.
[0017]
When the resin film is a laminated film including a layer made of a hygroscopic resin and a layer made of a non-hygroscopic resin, the moisture content in the hygroscopic resin layer is used as a reference for the moisture reduction rate. When the resin film has a plurality of layers made of a hygroscopic resin, the moisture content in the entire layer made of the hygroscopic resin is used as a reference for the moisture reduction rate. In the present invention, preliminary drying is omitted and the resin film is heated to the thermoforming temperature, so that the heating start temperature is generally room temperature, specifically 40 ° C. or less. Since the resin film to be heated includes at least one layer made of a hygroscopic thermoplastic resin, the layer made of the hygroscopic resin usually absorbs moisture. The layer made of the hygroscopic resin generally has a moisture content of 0.25% by weight or more.
[0018]
In the present invention, the heating method is not particularly limited, and for example, a method of heating using a heater such as a far infrared heater, a method of heating a heated hot plate in contact with a film, or the like is adopted. be able to.
[0019]
Thus, in the present invention, when thermoforming a resin film, heating is performed at a slow rate of 0.001 to 0.009% by weight / second from the start of heating at normal temperature until the molding temperature is reached. To do. In general, by reducing the rate of temperature rise, water can be reduced (evaporated) at such a slow rate. However, depending on the type of hygroscopic resin and the combination of each layer in the case of a laminated film, etc. Since the relationship between the moisture reduction (evaporation) rate and the temperature rising rate changes greatly, a simple preliminary experiment may be performed to determine an appropriate temperature rising rate.
[0020]
The resin film heated to the molding temperature is then thermoformed. Various known methods such as vacuum forming, pressure forming, and press forming can be employed for thermoforming. The form of thermoforming may be a method in which the film is supplied while being continuously heated and continuously formed, or a method in which the film is heated and supplied in a batch manner and is formed in a batch manner. Also good.
[0021]
Although the molding temperature is not particularly limited, it is generally at least the highest glass transition temperature of the resin constituting the resin film, and preferably at least 10 ° C. higher than this maximum glass transition temperature. For example, when the resin film is made of only an acrylic resin mainly composed of methyl methacrylate, the temperature is 110 ° C. or higher, particularly about 130 to 190 ° C. When the resin film is made of an ABS resin or is a multilayer film including an ABS resin layer, the temperature is 110 ° C. or higher, particularly about 120 to 190 ° C. Moreover, when the resin film is a multilayer film including a polypropylene resin layer, it is in the range of 90 ° C. or more, particularly about 110 to 180 ° C.
[0022]
The pre-shaped film is then placed in close contact with one surface of the injection mold, and the film is integrally bonded to the surface by injecting the molten thermoplastic resin into the mold cavity. An injection-molded body in which it becomes a decorative layer can be produced. And according to the present invention, by controlling the heating conditions while omitting the preliminary drying of the film, it is possible to obtain a shaped film with very few surface defects, and injecting another thermoplastic resin on one side thereof The molded body also has a good surface condition.
[0023]
【Example】
EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated further more concretely, this invention is not limited by these examples. In the examples, “%” and “part” representing the content or amount used are based on weight unless otherwise specified. In addition, the moisture content of the resin film, the moisture reduction rate due to heating, and the number of defects on the design surface of the preshaped object were determined by the following methods.
[0024]
[Moisture content of resin film]
A sample of a predetermined size is cut out from the film, and it is precisely weighed with an electronic precision balance to determine the moisture content weight a. Next, the sample is dried with a vacuum dryer at 120 ° C. for 3 days, cooled to room temperature, and then weighed again to determine the weight b in a state where the moisture content is 0%. From these weights a and b, the water content of the resin is determined by the following formula (I). When the film is a laminate of a hygroscopic resin and a non-hygroscopic resin, the hygroscopic resin layer is separated from the laminated film, and the moisture content is reduced by performing the same operation as above. Ask.
Moisture content (%) = (weight a−weight b) ÷ weight b × 100 (I)
[0025]
[Moisture reduction rate due to heating]
The moisture content (%) immediately before the start of heating and immediately after the end of heating before thermoforming is determined, and the difference between the two in percentage is divided by the heating time (seconds) to determine the rate of moisture reduction. The collected sample is immediately stored in a moisture-proof bag so that the moisture content of the sample does not change with the time until measurement, and the sample is opened immediately before measurement and used for measurement.
[0026]
[Number of defects on the design surface of the preshaped object]
Observe the design surface of the pre-shaped object shaped by thermoforming, 100cm ² Count the number of defective foams.
[0027]
Example 1
(A) Preparation of acrylic film
Here, an acrylic film comprising two layers of a transparent acrylic resin layer and a colored acrylic resin layer was produced. For the transparent layer, general-purpose grade methacrylic resin “SUMIPEX EX” manufactured by Sumitomo Chemical Co., Ltd. was used. This resin had a water absorption of 0.3% after being immersed in water at 23 ° C. for 24 hours in accordance with A method of JIS K 7209. The colored layer consists of 99.99% impact-resistant methacrylic resin “SUMIPEX HT01X” manufactured by Sumitomo Chemical Co., Ltd., 2% aluminum powder manufactured by Toyo Aluminum Co., Ltd. with an average particle size of 38 μm, and titanium yellow. Pellets prepared by melt-kneading 0.01% of the dye were used. Methacrylic resin “SUMIPEX HT01X” used for the colored layer has a water absorption rate after being immersed in water at 23 ° C. for 24 hours in accordance with A method of JIS K 7209.
It was 0.4%.
[0028]
Each resin was melted using two uniaxial extruders at a preset temperature of 260 ° C., and each layer was sequentially laminated with a feed block at a preset temperature of 280 ° C., and then extruded from a T-die having a preset temperature of 280 ° C. Furthermore, using a forming roll consisting of three polishing rolls set at a roll temperature of 70 ° C., the first and second rolls are cooled in a state where they are sandwiched in contact with both sides of the extruded molten resin, An acrylic bilayer film was prepared. The obtained bilayer film had a transparent layer thickness of 100 μm, a colored layer thickness of 200 μm, and a total thickness of 300 μm.
[0029]
(B) Production of ABS resin film
ABS resin “MTH-2” manufactured by Nippon A & L Co., Ltd. was put into a T-die film processing machine and extruded at a cylinder set temperature of 260 ° C. to obtain a film. The ABS resin “MTH-2” used here had a water absorption of 0.3% after being immersed in water at 23 ° C. for 24 hours in accordance with A method of JIS K 7209. The obtained ABS resin film had a thickness of 200 μm.
[0030]
(C) Production of decorative film
The acrylic two-layer film produced above and the ABS resin film were bonded using a laminate roll set at 100 ° C. At this time, the design surface was a transparent acrylic resin layer, and the colored acrylic resin layer and the ABS resin layer were laminated so as to contact each other. The thickness of the obtained laminated film (decorative film) was 480 μm. Moreover, the moisture content of this decorative film was 0.31%.
[0031]
(D) Pre-shaped decorative film
The decorative film having a length of 1200 mm and a width of 500 mm was fixed to a clamp frame of a vacuum / pressure forming machine (“CUPF1015-PWB” manufactured by Fuse Vacuum Co., Ltd.). Far infrared heater panels are respectively provided above and below the clamp frame. The outline of this heater panel and the outline of the arrangement of the heater panel are shown in FIG. That is, the far-infrared heater panels 3 and 4 arranged above and below the decorative film are 120 mm × 120 mm in size infrared heaters 5, 5... As shown in a schematic plan view in FIG. A total of 70 sheets are arranged, 7 sheets vertically at intervals of 150 mm and 10 sheets horizontally at intervals of 150 mm. Here, the infrared heaters 5, 5... Are composed of “HFS” (200 V × 400 W) manufactured by Elestein-Werk Steinmetz. The far-infrared heater panels 3 and 4 have both a 165 mm upper side and a 210 mm lower side of the decorative film 1 set on the clamps 7 and 7 as shown in a schematic longitudinal sectional view in FIG. Is installed.
[0032]
The set temperature of the upper and lower heater panels 3 and 4 was set to 350 ° C. and 300 ° C., respectively, and the decorative film 1 was heated. The surface temperature of the decorative film 1 before the start of heating was 20 ° C. From here, it heated until the surface temperature of the decorative film 1 became 160 degreeC. The heating time to reach 160 ° C. was 44 seconds, and therefore the rate of temperature increase was 3.2 ° C./second. Then, after the heater panels 3 and 4 are withdrawn from the system, the decorative film is shaped by bringing the vacuum forming mold into contact with the heating film and evacuating the air between the mold and the film. did. At this time, vacuum suction was performed from the transparent acrylic resin layer side so that the ABS resin layer side was concave. Subsequently, after cooling with a blower, the preformed decorative film was taken out. When the design surface of this preshaped decorative film was observed, no defects were observed, and a preshaped object with a good surface state could be obtained.
[0033]
Separately, the same operation as described above was performed, and the water content of the film in a state where the surface temperature just before the mold shaping reached the thermoforming temperature was measured and found to be 0.17%. In addition, the moisture content of the film after mold shaping was 0.17%.
[0034]
Example 2
The same operation as in Example 1 was performed except that the set temperatures of the heater panels 3 and 4 disposed above and below the film during heating were 300 ° C. and 250 ° C., respectively. At this time, the time required for heating until the film surface reached 160 ° C. was 83 seconds, and therefore the rate of temperature increase was 1.7 ° C./second. The moisture content of the film before the start of heating was 0.31%, the moisture content of the film immediately before mold shaping was 0.20%, and the moisture content of the film after shaping was 0.20%. When the design surface of the obtained preshaped film was observed, no defects were observed, and a preshaped object having a good surface state could be obtained.
[0035]
Example 3
In Example 1, the ABS resin film was not bonded, and the acrylic bilayer film was used alone as a decorative film. Moreover, the set temperature of the heater panels 3 and 4 arrange | positioned at the upper and lower sides of a film at the time of heating was 400 degreeC and 350 degreeC, respectively, and it heated until the temperature of the film surface became 130 degreeC. Otherwise, the same operation as in Example 1 was performed. At this time, the time required for heating until the film surface reached 130 ° C. was 13.5 seconds, and thus the rate of temperature increase was 8.1 ° C./second. The moisture content of the film before the start of heating was 0.45%, the moisture content of the film immediately before mold shaping was 0.35%, and the moisture content of the film after shaping was 0.35%. When the design surface of the obtained preshaped film was observed, the number of defects found was 2/100 cm. ² Thus, it was possible to obtain a preshaped object having a good surface state.
[0036]
Example 4
In this example, a film obtained by laminating a polypropylene resin film on an acrylic two-layer film produced by the same method as in Example 1 (a) was used.
[0037]
(A) Production of polypropylene resin film
27% propylene-ethylene copolymer resin “Sumitomo Nobrene FH1016” (230 ° C., melt flow rate 0.5 g / 10 min load at 2.16 kg) manufactured by Sumitomo Chemical Co., Ltd. Ethylene-butene copolymer “Esprene SPO N0416” (230 ° C., melt flow rate 13 g / 10 min at 230 ° C., 2.16 kg load) with a butene content of 22% manufactured by Chemical Industry Co., Ltd. and Hayashi Kasei ( Resin composition comprising 43% talc masterbatch, which is a 70:30 weight ratio mixture of talc “JR46” manufactured by KK and propylene homopolymer (230 ° C., melt flow rate 120 g / 10 min at 2.16 kg load) After the product was dry blended, it was put into a T-die film processing machine and extruded at a cylinder set temperature of 260 ° C. to produce a polypropylene resin film. The thickness of the obtained film was 200 μm. This film had a water absorption of 0.03% after being immersed in water at 23 ° C. for 24 hours in accordance with A method of JIS K 7209, and did not exhibit hygroscopicity.
[0038]
(B) Bonding of acrylic two-layer film and polypropylene resin film
To 100 parts of “TKS 3989”, a polyurethane adhesive manufactured by Toyo Morton Co., Ltd., add 4 parts of “CAT-RT”, an isocyanate curing agent manufactured by Toyo Morton Co., Ltd., and dilute with toluene. The coating amount is 7g / m ² The adhesive was used as an adhesive. A predetermined amount of the adhesive was applied to the colored layer side of the acrylic bilayer film and dried at 80 ° C. for about 1 minute. On the other hand, one side of the polypropylene resin film obtained in (a) above is subjected to corona treatment, and this corona treatment surface is overlaid on the adhesive application surface of the acrylic two-layer film, and a laminate roll set at 90 ° C. is used. And pasted. Thereafter, the film was cured at 40 ° C. for 72 hours to obtain a laminated film. The thickness of this laminated film was 500 μm.
[0039]
(C) Pre-shaping of laminated film
Using the laminated film obtained in the above (b), according to the method shown in (d) of Example 1, the set temperatures of the heater panels 3 and 4 placed above and below the film during heating are 320 ° C. and The film was heated to 300 ° C. until the film surface temperature reached 180 ° C. Thereafter, the same operation as in Example 1 was performed to produce a preshaped film. In addition, vacuum suction was performed from the transparent acrylic resin layer side, and it shape | molded so that the polypropylene resin layer side might become a concave surface. At this time, the time required for heating until the surface temperature of the film reached 180 ° C. was 92 seconds, and therefore the rate of temperature increase was 1.7 ° C./second. The moisture content of the acrylic bilayer film portion in the laminated film before the start of heating is 0.83%, the moisture content of the acrylic bilayer film portion immediately before mold shaping is 0.27%, and the acrylic bilayer film portion after shaping is The water content was 0.27%. When the design surface of the obtained preshaped film was observed, no defects were observed, and a preshaped object having a good surface state could be obtained.
[0040]
Comparative Example 1
A laminated film of an acrylic two-layer film and an ABS resin film produced by the same method as in Example 1 (a) to (c) was used. However, the laminated film used here had a moisture content of 0.43% before heating. This laminated film has the same arrangement as that shown in (d) of Example 1, except that the upper and lower heater panels 3 and 4 are set to 400 ° C. and 350 ° C., respectively, and the surface temperature of the laminated film is 20 It heated until it changed from 180 degreeC to 180 degreeC. At this time, the time required for heating until the film surface reached 180 ° C. was 37 seconds, and therefore the rate of temperature increase was 4.3 ° C./second. Subsequently, vacuum forming was performed in the same manner as in (d) of Example 1 to obtain a preshaped film. The moisture content of the film immediately before mold shaping was 0.07%, and the moisture content of the film after shaping was 0.07%. When the design surface of the obtained preshaped film was observed, 320 pieces / 100 cm ² A large number of defects were observed, and a preshaped object having a good surface condition could not be obtained.
[0041]
Reference example 1
The same acrylic bilayer film and ABS resin film laminated film (initial moisture content 0.43%) used in Comparative Example 1 was pre-dried for 3 hours in a hot air circulating oven set at 80 ° C. in advance. After pre-drying, the film temperature dropped to room temperature in a few minutes when removed from the oven and placed in a room temperature atmosphere. When the moisture content of the film was measured in this state, it was 0.23%. In the same manner as in Comparative Example 1, the pre-dried film was heated up and down by heater panels 3 and 4 set at 400 ° C. and 350 ° C., respectively, until the film surface temperature was changed from 20 ° C. to 180 ° C. Heated. At this time, the time required for heating until the film surface reached 180 ° C. was 38 seconds, and thus the rate of temperature increase was 4.2 ° C./second. Subsequently, vacuum forming was performed in the same manner as in Comparative Example 1 to obtain a pre-shaped decorative film. The moisture content of the film immediately before mold shaping was 0.12%, and the moisture content of the film after shaping was 0.12%. When the design surface of the obtained preshaped film was observed, no defects were observed, and a preshaped object having a good surface state could be obtained.
[0042]
The results of Examples 1 to 4, Comparative Example 1 and Reference Example 1 are summarized in Table 1.
[0043]
[Table 1]

[0044]
Example 5
An injection molded article was manufactured using the pre-shaped decorative film produced in each of the above examples. That is, after the decorative film pre-shaped in each example was inserted into the inner surface of an injection mold cavity produced by matching the shape and the mold was clamped, Examples 1 and 2 For Comparative Example 1 and Reference Example 1, ABS resin was injected to the ABS resin layer side, and for Example 3 to the colored acrylic resin layer side, and the decorative film was integrally bonded to the surface of the injection resin. A molded body was obtained. On the other hand, about Example 4, the polypropylene resin was inject | poured into the polypropylene resin layer side, and the same molded object was obtained. As a result, for Examples 1 to 4 and Reference Example 1 in which surface defects did not occur at the time of pre-shaping, molded products having a high surface design were obtained, whereas surface defects at the time of pre-shaping were obtained. In Comparative Example 1 in which the defect occurred, a molded article having a defective appearance was obtained with the surface defect remaining.
[0045]
As described above, in Reference Example 1 in which preliminary drying was performed before heating of the film, no foamy surface defect occurred, but at a moisture reduction rate of 0.010% / second from room temperature to molding temperature without preliminary drying. In the heated comparative example 1, many surface defects occur. On the other hand, in Examples 1 to 4, in which the moisture reduction rate when heating from room temperature to the molding temperature was smaller than 0.010% / second, a shaped article with a good surface condition was obtained while omitting preliminary drying. It is done.
[0046]
【The invention's effect】
According to the present invention, in thermoforming for shaping a resin film having at least one layer composed of a hygroscopic thermoplastic resin, the hygroscopic resin layer is in a state of absorbing moisture without pre-drying the resin film. As it is, it can be subjected to a step of heating to the molding temperature. And while pre-drying is omitted in this way, a shaped film having a good appearance and a molded product having a good appearance using it can be obtained. Therefore, simplification of the process and improvement of production efficiency are expected in the production of the shaped film and further in the production of the molded product using the shaped film.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 shows an outline of a heating state before molding in an embodiment, wherein (A) is a plan view showing an outline of a heater panel used for heating, and (B) is an outline of the arrangement of the heater panel and film. FIG.
[Explanation of symbols]
1 …… Film,
3, 4 ... Heater panel,
5 …… Infrared heater,
7 …… Clamp.

Claims (5)

A resin film having at least one layer made of a hygroscopic thermoplastic resin is used in a state where the moisture content in the hygroscopic resin layer is 0.001 to 0.005% from the state where the moisture content in the hygroscopic resin layer is 0.25% by weight or more. A method for thermoforming a resin film, characterized by heating to a molding temperature so as to decrease at a rate of 0.009% by weight / second and then molding. The thermoforming method according to claim 1, wherein the hygroscopic thermoplastic resin layer constituting the resin film includes an acrylic resin layer. The thermoforming method according to claim 2, wherein the acrylic resin comprises two layers of a transparent layer and a colored layer, and the transparent acrylic resin layer constitutes the design surface of the resin film. The thermoforming method according to claim 2 or 3, wherein the resin film is a multilayer film in which an acrylic resin and another thermoplastic resin are laminated, and the acrylic resin constitutes a design surface of the resin film. . A resin film having at least one layer made of a hygroscopic thermoplastic resin is used in a state where the moisture content in the hygroscopic resin layer is 0.001 to 0.005% from the state where the moisture content in the hygroscopic resin layer is 0.25% by weight or more. Heat to molding temperature to decrease at a rate of 0.009 wt% / second, then mold, place the resulting shaped film on one side of the injection mold and place the molten resin in the mold cavity A method for producing a resin molded body decorated with the resin film, wherein the resin film is injected.

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