JP2005186490A - Method for molding thermoplastic resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molding method which can produce a high quality molding excellent in transfer properties of a minute uneven surface in high productivity when the press mold molding and embossing of a thermoplastic resin are carried out. <P>SOLUTION: A thermoplastic resin preform, after being heated to a temperature near the solidification temperature of the thermoplastic resin, is inserted between molds the temperature of which is kept close to the solidification temperature of the resin, and the molds are closed with low pressure. Next, carbon dioxide is injected between the surfaces of the molds and the preform and dissolved into the surface of the preform to lower the viscosity of the preform. Next, press force is increased, and the preform with the viscosity of the surface lowered is adhered to the surfaces of the molds. Next, after the carbon dioxide is discharged, the molding is taken out. The molding high in quality and excellent in transfer properties of the minute uneven surface can be produced in high productivity. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a molding method in which a resin-soluble gas such as carbon dioxide is dissolved on the surface of a preform made of a thermoplastic resin, and more specifically, the temperature conditions are set on the preform and the mold. The present invention relates to a method for molding a thermoplastic resin.

  Low birefringence is required for optical information recording media, light guide plates, etc. that have fine shapes on the surface, such as products that require high transferability of these surface shapes, or optical lenses for cameras and printers. The manufacture of such products is conventionally obtained by injection molding a thermoplastic resin such as polycarbonate (hereinafter PC) or acrylic resin (hereinafter PMMA).

In recent years, low birefringence and further fine transferability have been demanded, and there are limits to conventional injection molding to manufacture such products, so press molding methods, embossing methods, etc. Special molding methods and processing methods have been proposed.
The press mold forming method is a method in which after the preform is placed in the cavity of the mold, the cavity volume is reduced, and a high internal pressure is uniformly generated in the cavity to perform isobaric compression. Since the method of holding pressure is uniform unlike injection molding, residual distortion of the molded product is reduced. Further, the transferability of the mold is remarkably improved.
The embossing method usually refers to a processing method for transferring a design shape such as a pattern or design using a roll or a mold. In the present invention, a design shape is transferred using a press mold (the shape is formed). Does not).

In the press-molding method and embossing method of a preform made of a thermoplastic resin, conventionally, as described above, after the mold and the preform are heated above the solidification temperature of the thermoplastic resin, The mold is pressurized and pressed, and then the product is taken out after the mold is cooled below the solidification temperature of the thermoplastic resin. However, in these methods, since the preform is melted again and then pressed, fine shape transferability and low birefringence are improved, but the resin preheating time in the mold is long, and the cycle time is long. The problem of becoming longer is also occurring. Further, since the melt cooling of the preform is repeated, there is a problem that the shrinkage rate during cooling is not constant and the dimensional accuracy is lowered.
For the purpose of improving transferability to a molded product, the following molding method is known in which a gas body is filled in a cavity before injection.

JP, 10-128783, A In this invention, in injection molding of a thermoplastic resin, the method of preventing solidification of a resin and a viscosity rise in a resin filling process, and transferring a mold surface state to a molded product highly is complicated. In order to provide economically without using a simple apparatus or mold, the thermoplastic resin is melted in a cooling mold filled with carbon dioxide at a pressure that dissolves 0.1% by weight or more in the thermoplastic resin to be molded. And then molding by lowering the solidification temperature of the surface of the thermoplastic resin. However, the present invention is not a press mold molding method and an embossing method, and is a molding method in which the mold is filled with carbon dioxide in advance to lower the solidification temperature of the resin. Not applicable.

JP, 2002-052583, A In this invention, in order to obtain a molded article excellent in transferability and glossiness, the cavity 1 and the resin are in contact immediately after the resin is filled in the cavity 1 in the injection molding. By injecting carbon dioxide gas into the skin layer of the molded product and retracting the skin layer to form voids 13 between the cavity and the skin layer, the growth of the skin layer is stopped and the carbon dioxide gas is dissolved in the skin layer. Then, the skin layer is softened, and then the resin pressure is increased, the skin layer is brought into close contact with the cavity 1 again, and cooled and solidified while applying pressure. However, the present invention is not applicable to a molding method and an embossing method in which a preform is press-molded because the molding principle is different.

JP, 2003-320556, A In this invention, in order to be able to manufacture efficiently and cheaply the molding which changed only the surface part into the required property, without using resin which mixed the modifier beforehand. It is said that the modifying material is dissolved or dispersed in a pressurized gas that is soluble in the injected molten resin, the pressurized gas is injected into the mold cavity, and then the molten resin is injected into the mold cavity. This is a molding method. However, although the present invention uses a gas having solubility, it is a method of injecting a pressurized gas into a mold in advance, and therefore cannot be applied to a press mold forming method or an embossing method.

The first object of the present invention is to increase productivity by shortening the molding cycle time in a thermoplastic resin molding method.
Furthermore, the second object is to provide a molding method and a processing method for obtaining a molded product having further improved transferability and birefringence of a fine shape in a thermoplastic resin molding method.
Furthermore, the third object is to provide a molding method and a processing method for obtaining a molded product with high dimensional accuracy in the thermoplastic resin molding method.

  In order to achieve the above object, in the invention described in claim 1, in the method for molding a thermoplastic resin, a preform formed of the thermoplastic resin is brought to a temperature near the solidification temperature of the thermoplastic resin constituting the preform. After heating, this is inserted between molds maintained at a temperature lower than the solidification temperature of the thermoplastic resin, the mold is closed at a low pressure, and then the resin-soluble gas between the mold surface and the preform surface Is injected and dissolved on the surface of the preform body to lower the viscosity of the surface of the preform body, and then the press force of the mold is increased, and the preform body and the surface of the mold whose surface viscosity is reduced are increased at high pressure. Next, after discharging the remaining resin-soluble gas from the mold, the molded product is taken out, and a product with excellent transferability of fine uneven surfaces and good dimensional accuracy is obtained in a short molding cycle. Also characterized by getting in time It is.

  Furthermore, in the invention according to claim 2, in the method for molding a thermoplastic resin, after heating a preform made of the thermoplastic resin to a temperature equal to or higher than a solidification temperature of the thermoplastic resin constituting the preform, Is inserted between molds heated above the solidification temperature of the thermoplastic resin, the mold is closed at a low pressure, and then a resin-soluble gas is injected between the mold surface and the surface of the preform, and the preform is molded. By dissolving on the surface, the viscosity of the surface of the preform is lowered, then the press force of the mold is increased, and the preform and the surface of the mold whose surface viscosity is reduced are brought into close contact with each other at high pressure, and then the remaining The resin-dissolving gas is discharged from the mold, and after the mold and the resin are cooled to below the solidification temperature of the thermoplastic resin, the transferability of the fine uneven surface is dramatically improved by taking out the molded product, In addition, short molding of products with low birefringence It is characterized in that obtained in cycle time.

  Further, in the invention described in claim 3, in the invention described in claim 1 or 2, the pressure, temperature, and preforming of the resin-soluble gas injected between the mold cavity surface and the preform surface. By changing the contact time between the body and the resin-soluble gas, the amount of decrease in the viscosity of the surface of the preformed body and the thickness of the layer in which the viscosity decreases are strictly controlled.

  Furthermore, in the invention according to claim 4, in the method for molding a thermoplastic resin, a preformed body made of the thermoplastic resin is maintained at a temperature not higher than the solidification temperature of the thermoplastic resin and the solidification temperature of the thermoplastic resin. Fit between molds kept at the following temperature, close the mold at low pressure, and then inject resin-soluble gas between the stamper surface and the preform surface to dissolve it on the preform surface To reduce the viscosity of the surface of the preformed body, and then to increase the pressing force to bring the surface of the preformed body and the stamper into close contact with each other at a high pressure. After discharging from the inside, the molded product is taken out to obtain a high-quality molded article with excellent transferability on a fine uneven surface and a short molding cycle time.

  Furthermore, in the invention according to claim 5, in the method for molding a thermoplastic resin, a preformed body made of the thermoplastic resin is heated to a temperature equal to or higher than the solidification temperature of the thermoplastic resin, and is equal to or lower than the solidification temperature of the thermoplastic resin. By fitting between molds kept at a temperature of, closing the mold at low pressure, and then injecting a resin-soluble gas between the stamper surface and the preform surface to dissolve it on the preform surface, Lowering the viscosity of the surface of the preformed body, then increasing the pressing force, bringing the preformed body with the reduced surface viscosity into close contact with the stamper surface at high pressure, then discharging the remaining resin-soluble gas, And after cooling the resin to below the solidification temperature of the thermoplastic resin, the molded product is taken out to obtain a high-quality molded product with remarkably excellent transferability of the fine uneven surface. .

  Furthermore, in the invention described in claim 6, in the invention described in claim 4 or claim 5, the pressure and temperature of the resin-soluble gas injected between the stamper surface and the surface of the preform, and the preform By changing the contact time of the resin-soluble gas, the amount of decrease in the viscosity of the surface of the preformed body and the thickness of the layer in which the viscosity decreases are strictly controlled.

Furthermore, in the invention according to claim 7, in the invention according to any one of claims 1 to 6, as the resin-soluble gas, carbon dioxide, nitrogen, methane, ethane, propane, These hydrocarbons are characterized by using, for example, chlorofluorocarbons in which a part of hydrogen is substituted with fluorine, or the like in a mixed state.
The carbon dioxide injected into the mold is discharged as soon as the mold is opened after the pressing process. However, when the pressure of carbon dioxide is high, it is desirable to discharge from a separate circuit immediately before the mold is opened.
By the way, in the above claims 1, 2, 4, and 5, the mold temperature is defined as Tt, the solidification temperature of the resin as Tf, and the solidification temperature of the resin that is lowered by the dissolution of carbon dioxide as ΔTco2. The mold temperature is preferably set in the range of Tf−ΔTco2 ≦ Tt ≦ Tf.
In addition, the larger the Tt− (Tf−ΔTco2), the better the product transferability.

  In the inventions according to claims 1, 4, and 7, the viscosity of the surface of the preform is lowered by dissolving carbon dioxide or the like on the surface of the preform. For this reason, press mold forming or embossing is enabled while maintaining the mold temperature at a constant temperature below the solidification temperature of the thermoplastic resin. As a result, the molding cycle time is greatly improved and the productivity is improved as compared with the conventional method in which the mold temperature is raised before the pressing process and the mold temperature needs to be lowered during the cooling process. Further, since the resin temperature does not change when solidifying, a product can be obtained in which the dimensional accuracy is hardly lowered by the shrinkage of the resin.

  In the inventions according to claims 2, 5 and 7, it is necessary to raise the mold temperature before the pressing process and lower the mold temperature during the cooling process, as in the conventional press molding or embossing. Therefore, although the improvement in molding cycle time is small, the viscosity of the preform surface is greatly reduced, the transferability of the fine uneven surface is greatly improved, and the birefringence is greatly improved by strain relaxation. . Further, as described in claims 3, 6 and 7, by changing the pressure and temperature of carbon dioxide or the like injected between the mold surface and the preform surface, and the contact time of the preform and carbon dioxide The amount of decrease in the viscosity of the surface of the preformed body and the thickness of the layer where the viscosity is lowered can be strictly controlled. When the conditions are set so that the viscosity-decreasing layer is thicker than the preformed body, Since the overall viscosity is reduced, the internal strain is relaxed and a product having a low birefringence can be obtained.

  The thermoplastic resin used in the present invention is, for example, a styrene resin (for example, polystyrene, butadiene / styrene copolymer, acrylonitrile / styrene copolymer, acrylonitrile / butadiene / styrene copolymer, etc.), ABS resin, polyethylene, Polypropylene, ethylene-propylene resin, ethylene-ethyl acrylate resin, polyvinyl chloride, polyvinylidene chloride, polybutene, polycarbonate, polyacetal, polyphenylene oxide, polyvinyl alcohol, polymethyl methacrylate, saturated polyester resin (for example, polyethylene terephthalate, polybutylene terephthalate, etc. ), Biodegradable polyester resins (for example, hydroxycarboxylic acid condensates such as polylactic acid, diol and dibutyl such as polybutylene succinate) Condensates of rubonic acid, etc.) Polyamide resin, polyimide resin, fluororesin, polysulfone, polyethersulfone, polyarylate, polyetheretherketone, liquid crystal polymer, etc., one or a mixture of two or more, various inorganic and organic substances Examples thereof include a resin mixed with a filler. Among these thermoplastic resins, amorphous resins are particularly preferable.

  The resin-soluble gas used in the present invention is preferably a gas that efficiently dissolves the surface of the preform, and specifically includes hydrocarbons such as carbon dioxide, methane, ethane, and propane, and a part of hydrogen. One or a mixture of a plurality of chlorofluorocarbons substituted with fluorine or the like can be considered. These gases can be used alone or in combination, but carbon dioxide is the best in terms of safety, price, ease of handling, and influence on the environment.

  This embodiment corresponds to the invention described in claim 1, and details thereof will be described in detail with reference to the drawings. FIG. 1 shows the entire molding apparatus, FIG. 2 (a) is a plan view of the preform X-1, (b) is a cross-sectional view taken along the line AA ', and FIG. 3 (a) is a plan view of the molded product X-2. FIG. 4B is a sectional view taken along line B-B ′, FIG. 4A shows a molding flow, and FIG. 4B shows a change in the solidification temperature of the resin corresponding to the molding flow and the mold temperature.

  In each figure, reference numerals 8a and 8b denote press mold molds, and heat exchangers 9a and 9b are used to heat the molds 8a and 8b by circulating hot water in the molds 8a and 8b. And a sealing material 10 that secures a seal when the molds 8a and 8b are sealed is attached to the mold 8b side. The mold temperature is adjusted by the temperature adjuster 6 through the temperature adjustment lines 7a and 7b. The temperature regulator 6 is made in-house, and includes pumps 2a, 2b, a heater 3, a cooler 5, and solenoid valves 4a, 4b, 4c, 4d, 4e, 4f. The operation of the apparatus is as follows: the water from the water source 1 is poured by the pump 2a and converted into hot water by the heater 3, or the pump 2b is poured and cooled by the cooler 5, and these are cooled by the solenoid valves 4a, 4b, 4c, 4d, 4e, While switching by 4f, the heat exchangers 9a and 9b of the molds 8a and 8b are circulated. When flowing hot water through the molds 8a and 8b, the electromagnetic valves 4a, 4c and 4f are opened, and when flowing cold water through the molds 8a and 8b, the electromagnetic valves 4b, 4d and 4e are opened. Carbon dioxide is injected into the molds 8a and 8b through the carbon dioxide supply line 11 by the carbon dioxide generation and injection device 21. Carbon dioxide generating and injecting device 21 is made in-house, with solenoid valves 12a and 12b, pressure sensor 13, back pressure valve 14, safety valve 15, temperature sensor 16, pressure storage tank 17, warming machine 18, pressure reducing valve 19, and check valve 20. Composed. The operation of the apparatus is to store the carbon dioxide generated from the carbon dioxide generation source 22 by adjusting the pressure by the pressure reducing valve 19, adjusting the temperature by the warmer 18, and accumulating the pressure in the pressure accumulating tank 17. Next, the pressure is finely adjusted by the back pressure valve 14, and carbon dioxide is injected and discharged by the electromagnetic valves 12a and 12b. The electromagnetic valve 12b opens when carbon dioxide is injected, and the electromagnetic valve 12a opens when carbon dioxide is discharged. When the molds 8a and 8b are closed during the molding operation, the carbon dioxide injected into the molds 8a and 8b can maintain the pressure by the sealing material 10.

  Based on FIG. 4 or FIG. 5, the press mold forming method according to the present invention described in claims 1, 2, 3, and 7 will be described. PMMA (Sumitomo Chemical Co., Ltd., trade name MGSS) was used as the resin. The solidification temperature of this resin is about 100 ° C. The preform X-1 is shown in FIG. 2, and the shape of the molded product is shown in FIG. The shape of the preform X-1 is 28mm long, 28mm wide and 3mm thick, and the shape of the molded product X-2 is 32mm long, 32mm wide, 4mm high and 1.5mm thick. It is box-shaped and has a fine continuous V-groove 23 having a width of 20 μm and a depth of 5.7 μm at the center of the molded product X-2.

  The forming process described in claim 1 will be described with reference to FIG. First, as shown in (A), the PMMA preform X-1 heated to 80 ° C. is placed between the molds 8a and 8b maintained at 80 ° C. by the temperature adjuster 6 and the temperature adjustment lines 7a and 7b. Put. Next, as shown in (B), the mold 8a is closed to a state just before contacting the surface of the preform X-1, and the mold 8a is passed from the carbon dioxide generation injection device 21 through the carbon dioxide injection line 11. And carbon dioxide at a pressure of 8 MPa and a temperature of 40 ° C. are injected for 1 second between the preform X-1 and the preform X-1. As a result, the solidification temperature of the surface of the resin is about 40 ° C., which is about 60 ° C. lower than about 100 ° C. of PMMA. Next, as shown in (C), the mold 8a is tightened with a pressure of 50 MPa and held for 5 seconds. Next, as shown in (D), carbon dioxide in the carbon dioxide injection line 11 is discharged. Next, as shown in (E), the mold 8a is opened and the molded product X-2 is taken out. Table 1 shows the molding conditions, and Table 2 shows the evaluation of the molded product thus obtained.

  The same as Example 1 except that the injection pressure of carbon dioxide was 15 MPa. Table 1 shows the molding conditions, and Table 2 shows the evaluation of the molded product thus obtained.

  The same as Example 1 except that the temperature of carbon dioxide was 60 ° C. Table 1 shows the molding conditions, and Table 2 shows the evaluation of the molded product thus obtained.

  The same as Example 1 except that the contact time of carbon dioxide was 5 sec. Table 1 shows the molding conditions. Table 2 shows the evaluation of the molded product thus obtained.

  The same apparatus as in Example 1 and resin were used, and the process shown in FIG. 5 was performed. First, as shown in (A), the PMMA preform X-1 heated to 140 ° C. is placed between the molds 8a and 8b heated to 140 ° C. by the temperature adjuster 6 and the temperature adjustment lines 7a and 7b. Put. Next, as shown in (B), the mold 8a is closed to a state just before contacting the surface of the preform X-1, and the mold 8a is passed from the carbon dioxide generation injection device 21 through the carbon dioxide injection line 11. And carbon dioxide having a pressure of 8 MPa and a temperature of 40 ° C. are injected for 1 second between the preform 9a and the preform 9a. As a result, the solidification temperature of the surface of the resin is reduced by about 60 ° C. from about 100 ° C. of PMMA to about 40 ° C. Next, as shown in (C), the mold 8a is tightened with a pressure of 50 MPa and held for 5 seconds. Next, as shown in (D), carbon dioxide in the carbon dioxide injection line 11 is discharged, and the mold 8a is cooled to 80 ° C. by the temperature adjuster 6 and the temperature adjustment lines 7a and 7b. Next, as shown in (E), the mold 8a is opened and the molded product X-2 is taken out. Table 1 shows the molding conditions, and Table 2 shows the evaluation of the molded product thus obtained.

  Example 2 is the same as Example 2 except that the resin-soluble gas is a mixture of carbon dioxide and nitrogen in a ratio of 3: 1. Table 1 shows the evaluation of the molded product thus obtained. By changing the ratio of carbon dioxide and nitrogen, only the transferability of the molded product can be controlled.

評価基準 ◎＝非常に良い ○＝良い △＝やや劣る [Comparative Example 1]
The same as Example 1 except that carbon dioxide was not injected. Table 1 shows the molding conditions, and Table 2 shows the evaluation of the molded product thus obtained.

Evaluation criteria ◎ = very good ○ = good △ = slightly inferior

  This embodiment corresponds to claim 4, and the apparatus of this embodiment is shown in FIG. 6, the preform X-1 is shown in FIGS. 7 (a) and 7 (b), and the molded product X-2 is shown in FIG. FIGS. 9A and 9B show the steps shown in FIGS. 9A and 9B, and FIG. 9B shows the changes in the resin solidification temperature and the stamper temperature. Reference numerals 8a and 8b are embossing dies, 8c is a stamper, and the temperature of the stamper is adjusted by the temperature adjuster 6 through the temperature adjustment lines 7a and 7b in the heat exchanger 8d in the stamper 8c. This is done by circulating a medium. The temperature regulator 6 is made in-house, and includes pumps 2a and 2b, a heater 3 and a cooler 5, and solenoid valves 4a, 4b, 4c, 4d, 4e, and 4f. The operation of the apparatus is as follows: the water from the water source 1 is poured by the pump 2a and converted into hot water by the heater 3, or the pump 2b is poured and cooled by the cooler 5, and these are cooled by the solenoid valves 4a, 4b, 4c, 4d, 4e, While switching by 4f, the inside of the heat exchanger 8d of the stamper 8c is circulated. When flowing hot water through the stamper 8c, the electromagnetic valves 4a, 4c, 4e are opened, and when flowing cold water through the stamper 8c, the electromagnetic valves 4b, 4d, 4f are opened. Carbon dioxide is injected into the mold through a carbon dioxide supply line 11 by a carbon dioxide generating / injecting device 21. Carbon dioxide generating and injecting device 21 is made in-house, with solenoid valves 12a and 12b, pressure sensor 13, back pressure valve 14, safety valve 15, temperature sensor 16, pressure storage tank 17, warming machine 18, pressure reducing valve 19, and check valve 20. Composed. The operation of the apparatus is to store the carbon dioxide generated from the carbon dioxide generation source 22 by adjusting the pressure by the pressure reducing valve 19, adjusting the temperature by the warmer 18, and accumulating the pressure in the pressure accumulating tank 17. Next, the pressure is finely adjusted by the back pressure valve 14, and carbon dioxide is injected and discharged by the electromagnetic valves 12a and 12b. The electromagnetic valve 12b opens when carbon dioxide is injected, and the electromagnetic valve 12a opens when carbon dioxide is discharged. When the molds 8a and 8b are closed during the molding operation, the carbon dioxide injected into the molds can maintain the pressure by the sealing material 10.

  Based on FIG. 9 (a) (b) or FIG. 10 (a) (b), a press mold forming method according to the present invention described in claims 4, 5, 6 and 7 will be described. PMMA (Sumitomo Chemical Co., Ltd., trade name MGSS) was used as the resin. The solidification temperature of this resin is about 100 ° C. As shown in FIGS. 7 and 8, the shapes of the preform X-1 and the molded product X-2 are a flat plate shape having a length of 32 mm, a width of 32 mm, and a thickness of 1.5 mm. Has a fine continuous V-groove 23 having a width of 20 μm and a depth of 5.7 μm.

  Next, a shaping | molding process is demonstrated based on Fig.9 (a) (b). First, as shown in (A), a normal temperature PMMA preform X-1 was maintained at 80 ° C. by a temperature adjuster 6 and temperature adjustment lines 7a and 7b, and a mold maintained at 80 ° C. Put between 8b. Next, as shown in (B), the stamper 8c is closed to a state just before contacting the surface of the preform X-1, and the stamper 8c and the preparatory material are supplied from the carbon dioxide generating / injecting device 21 through the carbon dioxide injection line 11. Carbon dioxide having a pressure of 15 MPa and a temperature of 40 ° C. is injected into the compact X-1 for 1 second. As a result, the solidification temperature of the resin is reduced by about 60 ° C. from about 100 ° C. of PMMA to about 40 ° C. Next, as shown in (C), the mold 8a is tightened with a pressure of 50 MPa and held for 5 seconds. Next, as shown in (D), carbon dioxide in the carbon dioxide injection line 11 is discharged. Next, as shown in (E), the mold 8a is opened and the molded product X-2 is taken out. Table 3 shows the molding conditions, and Table 4 shows the evaluation of the molded product thus obtained.

  Using the same apparatus and resin as in Example 3, the steps shown in FIGS. 10 (a) and 10 (b) were performed. First, as shown in (A), a PMMA preform X-1 at room temperature was heated to 120 ° C. by a temperature adjuster 6 and temperature adjustment lines 7a and 7b, and a mold maintained at 80 ° C. Put between 8b. Next, as shown in (B), the stamper 8c is closed to a state just before contacting the surface of the preform X-1, and the stamper 8c and the preparatory material are supplied from the carbon dioxide generating / injecting device 21 through the carbon dioxide injection line 11. Carbon dioxide having a pressure of 8 MPa and a temperature of 40 ° C. is injected into the compact X-1 for 1 second. As a result, the solidification temperature of the resin is reduced by about 60 ° C. from about 100 ° C. of PMMA to about 40 ° C. Next, as shown in (C), the mold 8a is tightened with a pressure of 50 MPa and held for 5 seconds. Next, as shown in (D), carbon dioxide in the carbon dioxide injection line 11 is discharged, and the stamper 8c is cooled to 80 ° C. by the temperature adjuster 6 and the temperature adjustment lines 7a and 7b. Next, as shown in (E), the mold 8a is opened and the molded product X-2 is taken out. Table 3 shows the molding conditions, and Table 4 shows the evaluation of the molded product thus obtained.

評価基準 ◎＝非常に良い ○＝良い △＝やや劣る
なお、請求項６に関する実施例は、実施例２、実施例３、実施例４、実施例５に記載されている結果と同一であるため、説明文については省略する。 [Comparative Example 2]
Example 8 is the same as Example 8 except that carbon dioxide was not injected. Table 3 shows the molding conditions, and Table 4 shows the evaluation of the molded product thus obtained.

Evaluation Criteria ◎ = Very Good ○ = Good △ = Slightly Inferior In addition, the examples related to claim 6 are the same as the results described in Example 2, Example 3, Example 4, and Example 5. The explanation is omitted.

Explanatory drawing of the press mold shaping apparatus for implementing this invention. It is explanatory drawing of a preforming body, Comprising: (a) is a top view, (b) is AA 'sectional view taken on the line. It is explanatory drawing of a molded object, Comprising: (a) is a top view, (b) is a BB 'sectional view taken on the line. (A) (b) Explanatory drawing of the press molding process based on Claim 1 of this invention. (A) (b) Explanatory drawing of the press molding process based on Claim 2 of this invention. Explanatory drawing of the embossing apparatus for implementing this invention. It is explanatory drawing of a preforming body, Comprising: (a) is a top view, (b) is CC 'line sectional drawing. It is explanatory drawing of a molded object, Comprising: (a) is a top view, (b) is DD 'line sectional drawing. (A) (b) Explanatory drawing of the embossing process based on Claim 4 of this invention. (A) (b) Explanatory drawing of the embossing process based on Claim 5 of this invention.

Explanation of symbols

1 Water source
2a, 2b pump
3 Heating machine
4a, 4b, 4c, 4d, 4e, 4f Solenoid valve
5 Cooling machine
6 Temperature controller
7a, 7b Temperature adjustment line
8a, 8b mold
8c stamper
9a, 9b heat exchanger
10 Sealing material
11 CO2 injection line
12a, 12b Solenoid valve
13 Pressure sensor
14 Back pressure valve
15 Safety valve
16 Temperature sensor
17 Accumulation tank
18 Heater
19 Pressure reducing valve
20 Check valve
21 Carbon dioxide generator
22 Sources of carbon dioxide
23 Fine continuous V groove
X-1 preform
X-2 Molded product

Claims (7)

  After heating the preform made of the thermoplastic resin to near the solidification temperature of the thermoplastic resin constituting the preform, it is inserted between molds maintained at a temperature lower than the solidification temperature of the thermoplastic resin, The mold is closed at a low pressure, and then the viscosity of the preform surface is lowered by injecting a resin-soluble gas between the mold surface and the preform surface to dissolve the preform body surface. Then, the press force of the mold is increased, the preform having a reduced surface viscosity is brought into close contact with the mold surface, and then the remaining resin-soluble gas is discharged from the mold, A method for molding a thermoplastic resin that, by taking out, produces a product with excellent transferability on a fine uneven surface and good dimensional accuracy in a short molding cycle time.   A preform formed of a thermoplastic resin is heated to a temperature equal to or higher than the solidification temperature of the thermoplastic resin constituting the preform, and then inserted between molds heated to a temperature equal to or higher than the solidification temperature of the thermoplastic resin. Is closed at low pressure, and then the viscosity of the preform surface is lowered by injecting a resin-soluble gas between the mold surface and the preform surface to dissolve the preform surface. The press force of the mold is increased, and the preform and the mold surface with reduced surface viscosity are brought into close contact with each other at high pressure. Then, the remaining resin-soluble gas is discharged from the mold, and the mold and the resin are heated. Molding of a thermoplastic resin that cools to below the solidification temperature of the plastic resin and then takes out the molded product to obtain a product with a remarkably excellent transferability of fine uneven surfaces and a low birefringence in a short molding cycle time. Method.   By changing the pressure and temperature of the resin soluble gas injected between the mold cavity surface and the preform surface, and the contact time between the preform and the resin soluble gas, the amount of decrease in the viscosity of the preform surface, 3. The method for molding a thermoplastic resin according to claim 1, wherein the thickness of the layer in which the viscosity is lowered is strictly controlled.   A preform made of thermoplastic resin is fitted between a stamper maintained at a temperature lower than the solidification temperature of the thermoplastic resin and a mold maintained at a temperature lower than the solidification temperature of the thermoplastic resin, and the mold is closed at a low pressure. Next, by injecting a resin-soluble gas between the stamper surface and the preformed body surface and dissolving it in the preformed body surface, the viscosity of the preformed body surface is lowered, and then the pressing force is increased to increase the surface. The preform with reduced viscosity and the surface of the stamper are brought into close contact with each other at high pressure, and then the remaining resin-soluble gas is discharged from the mold, and then the molded product is taken out to obtain transferability on a fine uneven surface. A method of molding a thermoplastic resin to obtain an excellent, high-quality molded product in a short molding cycle time.   A preform made of thermoplastic resin is inserted between a stamper heated to a temperature higher than the solidification temperature of the thermoplastic resin and a mold maintained at a temperature lower than the solidification temperature of the thermoplastic resin, and the mold is closed at a low pressure. In addition, by injecting a resin-soluble gas between the stamper surface and the preformed body surface and dissolving it in the preformed body surface, the viscosity of the preformed body surface is lowered, and then the pressing force is increased to increase the surface viscosity. The preform and the surface of the stamper with reduced pressure are brought into close contact with each other at high pressure, and then the remaining resin-soluble gas is discharged, and the molded product is taken out after the stamper and the resin are cooled to below the solidification temperature of the thermoplastic resin. A method for molding a thermoplastic resin that yields a high-quality molded product that is remarkably excellent in the transferability of fine uneven surfaces.   By changing the pressure and temperature of the resin-soluble gas injected between the stamper surface and the preform surface, and the contact time between the preform and the resin-soluble gas, the amount of decrease in the viscosity of the preform surface and the viscosity 6. The method for molding a thermoplastic resin according to claim 4, wherein the thickness of the layer in which the temperature falls is controlled strictly. As a resin-soluble gas, carbon dioxide, nitrogen, methane, ethane, propane, chlorofluorocarbons in which a part of hydrogen of these hydrocarbons is substituted with fluorine, or the like is used alone, or a plurality of these are mixed. The method for molding a thermoplastic resin according to any one of claims 1 to 6, wherein the method is used in a state where the thermoplastic resin is used.

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