JP5954700B2 - Apparatus and method for thermoforming - Google Patents

Description

  The present invention relates to a method for producing a thermoformed article using a thermoplastic resin sheet or film, and relates to heating and / or cooling a shaped body during thermoforming at high speed, and further to a crystalline thermoplastic resin. In the process of thermoforming, the heat treatment at a temperature higher than the preheating temperature of the sheet is performed, and regarding the high-speed and efficient production of thermoformed products with high mechanical properties such as heat resistance and transparency, the crystalline resin It relates to performing this thermoforming using a stretched sheet.

The thermoforming method is a method in which a preheated thermoplastic resin sheet or film is formed on a mold by pressing or vacuuming and then released, but in normal thermoforming, the shaped body is cooled by a low-temperature mold. It is released in the state. As a mold material, a material such as aluminum or zinc alloy that is lightweight and has good workability and good thermal conductivity is used, and it is often continuously formed by natural heat dissipation. However, in particular, if it is desired to adjust the temperature, the jacket provided inside the mold is cooled through a heat medium. On the other hand, cheap and easy-to-process materials such as wood and plastic may be used, but these are not durable and difficult to control temperature, causing problems such as heat accumulation, making them suitable for continuous mass production. However, its use is limited to sample trial production or small-scale production on a single-wafer molding machine.
And as a special molding method, when you want to heat or cool the shaped body arbitrarily during the molding cycle, change the heating medium in the middle of the heating medium passed through the jacket, or adjust the temperature of the shaped body separately It is performed to move to the mold. However, with such a method, a molded product that has been subjected to a desired heat treatment cannot be produced continuously at high speed and efficiently.

As a specific thermoforming method that requires special heating or cooling, (1) Japanese Examined Patent Publication No. 56-7855 is a method of thermoforming a polyester sheet by uniaxially stretching and heat-shrinking the sheet, Although a method of heat setting by using hot air at the time of molding is disclosed, the heat treatment takes a very long time and is not practical. In addition, (2) Japanese Patent Publication No. 5-45412 discloses a method of performing thermoforming and heat treatment using a sheet biaxially stretched under specific conditions and thermally contracted. Here, a method of transferring to a heating type, a heating method using hot air, hot water, infrared rays, etc. has been proposed, but it is not specifically described, and even if these are simply executed, there is no effect. And, if at all, it is not a fast, efficient and practical method. (3) Japanese Patent Publication No. 60-031651 also shows that a specific stretched polyester sheet is thermoformed and heat treated, and it is shown that it is molded with a heated mold, but the mold or molded product is cooled and separated. There is no mention of typing. However, for heat treatment molding of such materials, it is desirable to cool the molded body to at least a temperature lower than the heat treatment temperature and release the mold. However, if this is done by a known method, the mold itself is electrically heated. And a method of cooling in advance by passing water through a mold jacket immediately after molding, or a method of alternately passing a high temperature heat medium and a low temperature heat medium through the mold manifold. However, such a method cannot perform continuous molding at high speed. Also, (4) Patent 2532730 shows a method in which a non-stretched crystalline PET sheet is molded with a heated female mold, transferred to a low-temperature female mold, cooled, and released. At that time, deformation of the molded product, displacement, and generation of wrinkles become problems, and it is necessary to create a special dedicated molding apparatus capable of such operations.
In addition, (5) Japanese Patent Publication No. 7-102608 (Patent No. 2141026) shows a method of forming with a high-temperature female mold, taking it into a low-temperature male mold fitted thereto, cooling and releasing the mold. It can be said that it is a method of transferring the mold (4). Similarly, deformation and wrinkling of the molding become a problem, and it is difficult to apply to a molded product having an offset or undercut. In addition to these examples, in the so-called CPET molding as in (4) and (5), when molding is performed with a high-temperature mold from the beginning, the molding material does not slip on the mold surface, resulting in uneven patterns such as waves and irregularities. In order to avoid this problem, there is known a process in which a low-temperature mold is first molded and then transferred to a high-temperature mold, but this is also complicated.
(6) Japanese Patent Publication No. 06-16609 also discloses a method of molding a specific molding material by molding one of the male and male molds at a high temperature and fitting another cold mold to cool the molded body. .
(7) The method disclosed in Japanese Patent No. 4057487 relates to thermoforming of a crystalline resin, and a sheet preheated in contact with a heating plate is compressed and shaped with hot air passing through the heating plate and a molding die. Then, cooling air jetting means prepared separately is carried in and cooled, but this heating plate is adjusted to an appropriate temperature for sheet preheating, and heated air is supplied from behind to produce heated and compressed air. In this case, the heated gas is cooled in a conduit passing through the hot plate, and a very high temperature gas must be passed through the heat treatment, in which case the hot plate temperature is localized and non-uniform, and the material sheet is Local overheating tends to hinder good molding. In addition, the disclosed cooling means makes a wide area uniform. It cannot be cooled efficiently. Also, heat from the high temperature gas is easily dissipated into the mold, and the sheet cannot be easily heated to a high temperature in a short time, and high speed molding cannot be performed.
(8) The inventor of the present invention (hereinafter referred to as the present inventor) has filed at least 11 prior applications related to the present invention. These will be introduced and explained as appropriate in the relevant parts of the text.

Japanese Patent Publication No. 56-7855 Japanese Patent Publication No. 5-45412 Japanese Patent Publication No. 60-031651 Patent 2532730 Japanese Patent Publication No. 7-102608 Japanese Patent Laid-Open No. 6-166099 Japanese Patent No. 4057487

  The present invention has been made in view of such problems of the prior art. Its main purpose is to heat the shaped body at high speed and cool it as necessary at high speed in the process from thermoforming to mold release, especially heat treatment at a temperature higher than the preheating sheet temperature before shaping. It is an object of the present invention to provide a molding apparatus and a molding method that can perform thermoforming for releasing at high speed and efficiently continuously, and obtain a molded product in a uniform and good state.

(1) In a resin sheet thermoforming apparatus, a function of injecting at least one of a cooling gas and a heating gas by providing an injection hole on the molding surface of either a female mold or a male mold, and shaping the injection gas A male-male mold comprising a mold having a space forming function for diffusion over the entire surface (hereinafter referred to as an injection mold) and another mold corresponding thereto (hereinafter referred to as a holding mold), and compression into the gas injection mold A gas introducing means is provided, and is configured to heat or cool the shaped body held by the holding mold by injecting the gas from the injection mold forming surface at a distance away from the shaped body after shaping the resin sheet. An apparatus for molding a thermoplastic resin sheet is provided.
In the present invention, “molding” indicates the entire molding process from preheating to mold release,
In addition, “pressure forming” indicates a forming method including a process of “pressure forming” by compressed air. In addition, compressed air is providing a gas pressure. Further, the “shaped body” indicates a molded product before release in a state of being held in the mold.

(2) The molding apparatus according to the above (1), which has means for holding the shaped body on the molding surface of the holding mold.

(3) At least the molding surface of the holding mold is made of a material having a thermal permeability (b value) (kJ / m ² s ^1/2 K) of 0.01 to 25. The thermoforming mold according to the above (1) or (2) is provided.
The definition of the molding surface here excludes a coating agent for lubrication, mold release, etc., paint or plating of 50 μm or less applied to the molding surface.
The heat permeability of the surface layer forming material is preferably 20 or less, more preferably 15 or less, and still more preferably 10 or less.

(4) The shaped body holding mold comprises a surface layer made of a material having a heat permeability (b value) of 20 or less and a back body made of a material having a heat permeability (b value) larger than that of the surface layer. The thermoforming mold according to any one of the above (1) to (3), which is characterized in that it is provided.

(5) As means for heating the shaped body held by the holding mold, 1) at least one means for injecting heated gas from the gas injection mold, or 2) means for heating and using the shaped body holding mold The molding apparatus according to any one of the above (1) to (4) is provided.

(6) In the injection type, in addition to a mechanism for injecting gas from the injection hole, a mechanism for injecting the injected gas from a suction hole provided separately from the injection hole and exhausting it to the outside is provided. The molding apparatus according to any one of (1) to (5) above is provided.

(7) In the above injection mold, injection can be performed while changing the type of gas during one molding step, and the above “injecting mechanism” functions as a mechanism for exhausting from the middle, and the above “exhaust mechanism” The molding apparatus according to any one of claims 1 to 6, wherein the molding apparatus functions as a mechanism for injecting from the middle.

(8) The above-described male and female molds are formed so as to form a compressed air space that is closed when they are joined with a resin sheet interposed therebetween, and compressed air shaping can be performed by ejecting gas from the ejection mold. The molding apparatus according to any one of (1) to (7) is provided.

(9) A resin sheet molding method using the molding apparatus according to any one of (1) to (8) above, wherein the resin sheet is preheated, shaped, and heat treated at a temperature higher than the sheet preheat temperature. The present invention provides a method for forming a thermoplastic resin sheet comprising a heat treatment step and a cooling step.

(10) As a method for heat-treating the shaped body at a high temperature, at least one of 1) a method of ejecting a heated gas from the gas ejection mold or 2) a method of heating and using the holding mold is used. The molding method according to (9) is provided.

The apparatus configuration using the special male and female mold of the present invention has the following effects.
1) Molding can be performed by combining press shaping or male assist (plug assist) shaping capable of powerful shaping, and high-speed heating and / or cooling.
2) A specific simple mechanism can be added to enable pneumatic forming or vacuum forming, and it is also possible to form a molded product having an offset portion that cannot be achieved by a known male and female mold.
3) By performing gas injection at a position close to the shaped body, the shaped body can be subjected to strong blow heating and / or blow cooling, and the molding cycle with heat treatment can be shortened.
4) Gas injection can be performed at a uniform distance from each part of the shaped body, uniform blow heating or blow cooling is possible, and a uniform molded product can be obtained.
5) By using a specific material or a specific structure using a specific material for either of the male and female dies, heating or cooling of the shaped body with air having a small heat capacity can be performed efficiently.
6) Due to the effects described above, the process of pre-heating and releasing the resin sheet at a high temperature, which is significantly higher than the pre-heating temperature of the resin sheet, and then cooling and releasing at a very high speed. Can be run continuously, efficiently and stably.
7) The shortening of the molding cycle and the efficiency increase the energy-saving production, and the applicable molding material objects can be expanded.
Specific applications include: a) molding involving heat setting of a stretched sheet of a crystalline resin such as PET, b) molding involving crystallization of a crystalline resin sheet such as a crystal nucleating agent-added PET (CPET), or In addition, c) heat treatment molding can be proposed in which the residual stress distortion associated with SPPF molding (solid phase high pressure molding) of polypropylene is relaxed. d) Residual distortion is eliminated even by thermoforming of amorphous (amorphous) resin, and a product with high dimensional accuracy can be obtained.
8) In addition, products that have been limited to special applications can be made into general-purpose products.
For example, stretched PET efficiently produces thermoformed products having excellent mechanical strength such as heat resistance, transparency, and rigidity. Here, it is possible to use the rigidity to reduce the thickness of the molded product to save material, and to replace the commercially available normal molded product by high-speed molding equivalent to the normal molding obtained above.

It is sectional drawing which shows the structural example of the shaping | molding apparatus of this invention. It is sectional drawing which shows the example of the male-and-male shaping | molding die used for this invention. It is sectional drawing which shows another example of the male-and-male shaping | molding die used for this invention. It is sectional drawing which shows another example of the male-and-male shaping | molding die used for this invention. It is sectional drawing which shows another example of the male-and-male shaping | molding die used for this invention.

<Overall configuration of molding apparatus>
The thermoplastic resin sheet molding apparatus of the present invention is configured by incorporating a male and female molding die having a specific configuration into a thermoforming machine. The thermoforming machine is equipped with male and female mold separating means such as a press machine, preheating means for resin sheet of molding material, compressed gas introducing means, vacuum suction means, molding material conveying means, molded product unloading means, etc. use. Note that it is preferable that both the compressed gas introducing means and the vacuum suction means are aligned, but there are cases where only one of them is sufficient. The resin sheet preheating means may employ any known method such as indirect heating using a heating oven or the like, or direct heating in contact with a heating plate.
In the thermoforming method, a mold called a male and female mold (also referred to as a fitting mold or a matched die) is sometimes used. In the present invention, a male and female mold having a new specific configuration is used.
In the configuration of the present invention, a gas injection hole is provided on the molding surface of either the female mold or the male mold to inject at least one of a cooling gas and a heating gas, and the injection gas is diffused over the entire shaped body. A male-male mold comprising a spray mold having a space forming function and a holding mold corresponding thereto, and a compressed gas introducing means to the spray mold, and a distance separated from the shaped body after the resin sheet is shaped The injection gas is injected from the injection mold forming surface, and the shaped body held by the holding mold is heated or cooled.
There are several methods for providing the above-mentioned space forming function. For example, as a first method, the gap between the female male mold is approximately the thickness of the molding material sheet, and the gas injection mold is formed after shaping. It can be given by forming it into a molded body shape that allows a space for gas injection to be formed between the shaped body and the substantially entire surface of the shaped body. The second method is to make the gap between the female male mold larger than the thickness of the molding material sheet, bring the female mold closer to the male mold across the molding material sheet, and perform the vacuum shaping action from the shaped article holding mold side. Are also operated together to form a space for gas injection. In the third method, the gap between the female male molds is made larger than the thickness of the molding material sheet, and a bank (closing wall) is provided so that a closed space is formed when the female male molds are joined. The shaping action by the compressed air from the gas injection type is caused to cooperate to form a space for heating or cooling injection. Note that the closed space forming bank or the like may be provided in any of the female and male molds, or may be inserted as an independent member when both molds are approaching.
In the case of the second and third methods, the gas injection type may be approached after vacuum forming, which is also included in the method of the present invention.
The compressed gas introducing means is a gas compressor, a compressed gas heating device, and the like arranged outside the mold, and equipment that introduces the gas and appropriately supplies it into the mold.
One of the female mold and the male mold is fixed to the top plate of the press machine, the other is fixed to the bottom plate directly below it, and at least one of the top plate and the bottom plate is movable up and down. Allows the mold and female molds to be separated.
The resin sheet for molding is preheated and brought between the female mold and the male mold, and the sheet is sandwiched by lowering one side or the other, and is subjected to shaping, heat treatment, cooling, and release.
The heat treatment of the shaped body is performed by 1) jetting of heated gas from the injection mold, or 2) heating by the preheated temperature-controlled shaped body holding mold. The shaped body is cooled by 1) a relatively low temperature gas injection from the injection mold, or 2) a holding mold that is controlled to a relatively low temperature.
In addition, it is desirable that the shaped body holding mold has a mechanism for holding and fixing the shaped body. The mechanism for holding and fixing the shaped body is, for example, a) providing a vacuum exhaust hole penetrating from the molding surface of the shaped body holding mold, b) providing a vacuum exhaust narrow groove on the molding surface of the shaped body holding mold, c) molding There is a method of providing a partial offset portion of the product.
The shaped body is released when the gas injection mold and the holding mold are largely separated after the cooling step.
As the above-mentioned injection gas, any one can be used as long as it is harmless to the human body and the molded product such as air, nitrogen, carbon dioxide, etc., and water is mixed into these in order to enhance the heating effect or the cooling effect. In order to enhance the cooling effect, fine droplets of a volatile substance, for example, a volatile substance such as alcohol may be mixed therein.
In addition, even if the said injection gas is a gas for cooling or a gas for heating, you may utilize the same thing for compressed air shaping.
The thermoforming machine constituting the present invention may be a single-wafer forming machine that forms short material sheets one by one, or may be a continuous molding machine that sequentially forms long material sheets. However, the latter is particularly preferable, and the characteristics of the present invention are exhibited to enable high-speed and efficient repetitive molding.
The structure and operation of the above-described injection type will be described in detail in the subsequent <About injection type> column, and the structure and operation of the holding type will be described in detail in the subsequent <About holding type> column.

Known methods using male and female molds are disclosed in Japanese Patent Publication No. 7-102608 (Patent No. 2141026) and Japanese Patent Publication No. 06-16609. The details are as described in the “Technical Background” section. However, if further described, none of the above methods has the gas injection mechanism as described above. It does not have a structure that uniformly contacts the entire shaped body.
Note that the present invention relates to a prior application whose inventor is the inventor, Japanese Patent Application 2010-118555, Japanese Patent Application 2010-118490, Japanese Patent Application 2010-118489, Japanese Patent Application 2010-18562, Japanese Patent Application 2011-41294, and Japanese Patent Application 2011. -165067, Japanese Patent Application No. 2011-65068, Japanese Patent Application No. 2011-165069, Japanese Patent Application No. 2011-206514, Japanese Patent Application No. 2011-206515, Japanese Patent Application No. 2011-206516, and improved the product quality of thermoforming with heat treatment, It was made to improve productivity and expand application fields. It is also intended to present a new and specific device form that embodies them.

A specific example of the apparatus configuration of the present invention will be described with reference to FIG. Reference numeral 40 denotes an injection type (male type), 60 denotes a holding type (female type), 50 denotes an injection space (gap), and 110 denotes a shaped body. Although not shown in the drawing, the injection mold (male mold) 40 and the holding mold (female mold) 60 are respectively fixed to the top plate and the bottom plate of the press machine and are vertically movable. The resin sheet preheated in the preheating oven is guided between both molds, and can be shaped by bringing both molds close to each other.
The injection mold (male and female) 40 is configured to inject compressed gas or heated compressed gas introduced from an external device into an injection space (gap) 50 from an injection hole 45 provided in the molding surface 44. In this drawing, the other parts of the molding machine, the compressed gas or heated compressed gas generating device, etc. are not shown.
The holding mold (female mold) 60 heats a plurality of main bodies composed of a surface layer 61 made of a material having a relatively small heat permeability and a back layer (back body) 62 made of a material having a relatively large heat permeability. It is fixed to a collecting plate 66 provided with a medium passage 65.
In this figure, the injection mold 40 has a shape similar to that of the molded product and is smaller than that. When combined with the injection mold, the injection mold 40 has a dimension that forms a gap larger than the resin sheet thickness, and this injection mold (male mold) is inserted. In addition, gas is injected into the space 50 and the injected gas is exhausted through the exhaust passage 46 in a state where the shaped body is formed and held by evacuation from the holding die (female die) 60 side. .
At least two molding methods are possible using the male and female molds of this mechanism. One method is to raise the temperature of the surface layer 61 or the molding surface of the holding die (female die) 60 to a necessary heat treatment temperature and inject non-heated low-temperature gas from the injection holes 45 after the shaping heat treatment. Then, the shaped body is cooled and released. The other is that the back body 62 of the holding mold (female mold) 60 is adjusted to a temperature not higher than the upper limit of mold release capability, and a high-temperature gas heated from the gas injection hole 45 at the same time as shaping or after shaping. This is a method in which the shaped body is heated and heated, the injection is stopped, and the shaped body is cooled and released by heat transfer from the back body 62 via the surface layer 61.
The heater 47 warms the molding surface 42 to about the preheating temperature of the resin sheet so as not to cool the preheated sheet. However, for this purpose, there is a method in which the molding surface 44 is covered with a heat insulating material such as cloth without using the heater 47.
In addition, when injecting heating gas with this apparatus, you may heat the whole injection body 40 with the heater 47 at high temperature so that introduction gas may not be cooled. In this case, it is preferable to cover the molding surface 44 with a heat insulating material such as cloth so as not to overheat the resin sheet.

<About injection type>
The injection type is provided with a gas injection hole, an injection space forming function, and compressed gas introduction means for jetting and diffusing at least one of a cooling gas and a heating gas on the surface. The injection space forming function and the gas injection means are described above. The above-described injection type mechanism is not limited to this, but the following four modes can be shown.
In the first aspect, gas is injected from the injection mold surface, and the injection gas is exhausted along the injection space (gap). In this case, the method for forming the injection space may be a male / female complete fitting method or an incomplete fitting (hereinafter also referred to as loose fitting) method.
The second aspect has intake holes provided separately from the injection holes on the injection mold surface, and the gas injected from the injection holes into the injection space (gap) is sucked from the intake holes and exhausted to the outside. Also in this case, the method for forming the injection space may be a male / female complete fitting method or a loose fitting method.
The third mode has substantially the same structure as the second mode, and injects and exhausts the heated high-temperature gas introduced from the outside in the preceding process in the same manner, and relatively low temperature in the subsequent process. Injects and exhausts air from the injection holes. In this case, it is preferable that the preceding process is performed in the same manner, and the gas injection mechanism is switched to perform the work of the intake and exhaust and the mechanism of the intake and exhaust is performed to perform the work of gas injection in the subsequent process. It is preferable to adjust the temperature of each contact member so as to be suitable for low-temperature gas injection. However, this does not preclude injecting heated high-temperature gas and low-temperature gas from the same injection hole, and intake and exhaust from the gas intake hole. Also in this case, the method for forming the injection space may be a male / female complete fitting method or a loose fitting method.
In the fourth aspect, the form of the injection mechanism and exhaust is the same as in any one of the above aspects 1 to 3, and a bank (closed wall) is provided so that a closed space is formed when the female male mold is joined. . In this aspect, compressed air shaping can be performed. In this aspect, male and female loose fitting is performed. In addition, when this is performed by the aspect 1 and the injection / exhaust mechanism, the female / male die is separated from each other to perform gas injection / exhaust. In addition, this bank (closing wall) does not necessarily need to be provided in the injection type, and may be provided in the holding type. Further, it may be inserted as an independent member without being attached to the mold. Alternatively, the injection type or the holding type may be stored in a storage box having a high outer wall, and the outer wall may be a bank (closing wall).

The first aspect has already been described with reference to FIG. Here, an example of the gas injection type of the second aspect will be described with reference to FIG. The injection mold 40 in this figure is similar in shape to the molded product and slightly smaller than that, and when combined with the holding mold (female mold) 60 side, the injection mold 40 has dimensions that allow fitting and shaping with a gap close to the thickness of the coarse resin sheet. It has been. Further, when only 40 is lifted slightly after shaping, it is formed into a shape that can form an injection space 50 having a substantially uniform gap. This figure shows a state in which the injection mold 40 is lifted slightly after the resin sheet is fitted and shaped by the male and female molds, gas is injected from the injection mold 40, and the injected gas is exhausted through the exhaust passage 46. Yes. The shaped body is vacuum-sucked and held by the holding mold (female mold) 60. The holding mold (female mold) 60 in this figure will be described later separately.
In the configuration of this figure, the non-heated gas may be injected as in the case of FIG. 1, or the heating high-temperature gas can be similarly used.

The injection type of the second aspect will be further described. In this embodiment, in addition to the gas ejection holes, a plurality of suction holes for sucking the ejected gas and exhausting it to the outside are used on the molding surface. This aspect corresponds to the sixth aspect. With this configuration, a wider target area can be efficiently and uniformly heated or cooled so that it can be used preferably.
FIG. 3 shows an example of this aspect. The relationship between the female type and the male type may be the case of complete fitting as shown in FIG. 1 or the case of loose fitting as shown in FIG. FIG. 3 shows a state in which the gas is injected into the injection space 50 formed after shaping and the gas is exhausted to the outside. The injection mold 40 in this figure is composed of an injection port 41 and an exhaust port 51. The injection body injects the introduced compressed gas from an injection hole 45 provided in the molding surface 44, and the exhaust body is provided separately in the same surface layer 44. From the suction hole 55, the injected gas is sucked, led to the outside, and exhausted. The heater 47 is for preheating the molding surface 44 to an appropriate shaping temperature. The holding mold (female mold) in this figure is the same as that described in FIGS. 1 and 2 and will be described later.
The above basic structure can be left as it is, and the upper injection port 41 can be used as an exhaust port and the lower exhaust port 51 can be used as an injection port.

The injection type of the third aspect will be further described. In this aspect, the molding surface has a heating gas injection hole and a cooling gas injection hole, and during the heating gas injection, the cooling gas injection hole operates as the intake hole, and the cooling gas During the injection, the one configured such that the injection hole for the heating gas operates as the intake hole is used. This aspect corresponds to claim 7 of the present invention.
A specific example is shown in FIG. In the configuration of this figure, as in the case of FIG. 3, both the complete fitting and the loose fitting are included. FIG. 3 shows a state in which the gas is injected into the injection space 50 formed after shaping and the gas is exhausted to the outside.
The injection mold 40 in this figure is composed of an injection port) 41 and an exhaust port 51. The high temperature compressed gas introduced by the injection port 41 is injected into the injection space 50 from the injection hole 45, and the exhaust port 51 sucks the injection space 50 gas. The air is sucked from the hole 55 and led to the outside to be exhausted. Then, at any appropriate time, these functions are changed, the non-heated compressed gas introduced into the exhaust port 51 is injected from the intake hole 55, and the injected gas is sucked and guided from the injection hole 45 and exhausted to the outside. It is a mechanism to do.
The above basic structure can be left as it is, and the upper injection port 41 can be used as an exhaust port and the lower exhaust port 51 can be used as an injection port.
By this mechanism, it is possible to efficiently heat-treat the shaped body held by the shaped body holding mold by injecting the high-temperature compressed gas, and then efficiently cool the shaped body by injecting the non-heated compressed gas.
In addition, vacuum shaping may be used in combination with vacuum shaping, or may be used in combination with compressed air shaping. When using compressed air shaping, injection of hot compressed gas may be used, or unheated compressed gas may be used. However, it goes without saying that it is desirable to close the valve on the exhaust side when using compressed air shaping.

The injection type according to the fourth aspect will be further described. A closed air space is formed when the male and female molds are joined with a resin sheet interposed therebetween, and a gas is injected from the die having the injection holes so as to perform compressed air shaping. This aspect corresponds to the eighth aspect of the present invention.
A specific example is shown in FIG. The configuration of this figure includes a bank (closing wall) 51b, and other names and operation mechanisms are the same as those in FIG. When the bank 51b joins the female mold and the male mold across the resin sheet, a closed space is formed. This figure shows that either the high-temperature gas or the non-heated gas is compressed and shaped, and either the high-temperature gas or the non-heated gas can be injected.
Note that the bank (closing wall) 51b does not necessarily have to be able to be completely closed, and it is sufficient if the pressure can be maintained to the extent that compressed air shaping is possible.
In addition, in the structure of this aspect, you may perform vacuum shaping not only in compressed air shaping. Also,
You may comprise so that either heating injection or cooling injection may be performed independently.
The above basic structure can be left as it is, and the upper injection port 41 can be used as an exhaust port and the lower exhaust port 51 can be used as an injection port.
The formation of the bank (closing wall) as described above can be applied to any injection type as long as it is loosely fitted regardless of the injection or exhaust mechanism.

The injection type can be further modified as follows.
1) An exhaust enhancement means for suction exhaust such as a flower may be added to the injection type exhaust body of each aspect described above, which can be suitably used.
2) When using heated compressed gas, you may make it the structure which introduces normal temperature compressed gas and heats inside an injection type, and it can use it suitably.
3) It is also preferable to spray or spray a volatile liquid such as water or alcohol in combination with the compressed gas injection for cooling the shaped body. In this case, the injection hole may be used also as the gas injection hole, or another independent injection or spray nozzle may be provided, which can be suitably used.
4) The compressed gas used in the cooling step of the shaped body is preferably lower than room temperature, and the compressed gas may be cooled by immersing it in the dry ice lump, or mixed with dry ice powder. You may spray, or you may make it the structure which cools using the means of adiabatic expansion, and these can be used suitably.
5) In the above aspects 2 and 3, not only one kind of injection gas but also different temperatures are prepared. For example, the apparatus is configured to inject a high temperature gas first and then a low temperature gas. May be.
6) It is possible to carry out the three steps of shaping heat treatment cooling at once with compressed gas injection at one temperature. Note that a mechanism may be employed in which a specific amount of exhaust is always performed without providing a valve. In that case, there is no problem if the apparatus is set in anticipation of the pressure drop when accompanied by compressed air shaping.
7) In the case where a foamable resin sheet is used, the male and female molds may be configured with a gap thicker than the material sheet, or the structure may be configured such that the gas injection mold is evacuated temporarily in the shaping process. Can be configured.

In relation to the above-described concept of the injection type, the present inventor has previously made Japanese Patent Application Nos. 2011-41294, 2011-165067, Japanese Patent Application 2011-165068, Japanese Patent Application 2011-206514, Japanese Patent Application 2011-206515, Japanese Patent Application 2011. -206516 has been filed. The present invention further advances or complements these. In particular, Japanese Patent Application No. 2011-206516 includes a configuration similar to a part of the figure and the like, but the present invention has not been achieved and the present invention is required.
The injection type used in the configuration of the present invention has the following effects. 1) Gas can be sent out continuously at any time, and the process can proceed quickly from shaping to the next heating or cooling process. 2) Heating or cooling by gas injection can be uniformly and powerfully applied to all molding surfaces. It can be carried out. 3) The entire molding apparatus can be simply configured.

<Holding type>
The holding mold used as the apparatus component of the present invention is not particularly limited as long as it includes necessary elements for known thermoforming such as a vacuum exhaust hole.
However, as the holding mold used as the device component of the present invention, a mold having at least a molding surface formed of a material having a thermal permeability (kJ / m ² s ^1/2 K) of 0.01 to 25 is used. It is preferable to use it. The molding die may be configured by the above material, or may be a composite configuration having the above material as a surface layer.
However, plating or coating of 50 μm or less for the purpose of protection or lubrication is not subject to the restrictions on the forming material of the molding surface.
Examples of materials having a thermal permeability within the above range include plastics, ceramics, and a small number of selected metal materials. These include aluminum materials and zinc alloy materials that are commonly used as thermoforming molds. Is a value smaller than. Examples of materials having a preferred range of heat permeability can also be selected from Table 1. However, the notation is shown for reference to general substances or objects, and what can be used is not limited to these.
The thermal permeation rate and the significance of the numerical limitation will be described later in the section “Supplemental explanation about the contents of the present invention”.

As a further special embodiment of the holding type preferable for use in the above-described configuration of the present invention, a surface layer made of a material having a heat permeability (b value) of 20 or less and a heat permeability (b value) of that of the surface layer It is particularly preferable that the back body is made of a large material. Further, it is preferable to use a material that comprises a means for heating and controlling the surface layer constantly and uniformly from behind.
As a more specific preferable method for this, 1) a method in which a back layer close to the surface layer is provided with a material having a thermal permeability greater than that of the surface layer, and indirect heating temperature control is performed through the back layer; and 2 ) A method of directly heating the surface layer or heating it closely behind the surface layer can be mentioned.
In this case, the heat permeability of the surface layer forming material is more preferably 15 or less, and still more preferably 10 or less. Further, the thickness of the surface layer is required to be 0.04 mm or more, preferably 0.06 mm or more, and more preferably 0.1 mm or more. The thickness is preferably 30 mm or less, more preferably 10 mm or less, and even more preferably 5 mm or less.

When the above-mentioned back body is indirectly heated and controlled, the means may be any known method such as electric heater or heat medium temperature control, and it may be provided in the back layer or provided externally. Also good. The surface layer is heated at a constant temperature by conduction heat from the back layer.
In this case, the thermal permeability of the back layer is preferably 3 or more, more preferably 6 or more, and even more preferably 10 or more. The thermal permeability of the back layer is preferably 2 times or more, and more preferably 10 times or more than that of the surface layer.
Note that the thickness of the back layer is not limited, and is not limited to a certain thickness or shape. Further, this layer is not limited to a single material layer, and may be an arbitrary multilayer.

  FIG. 2 shows an example of the structure 1). The molding die 60 is composed of a surface layer 61 and a back body 62, 63 is a vacuum exhaust hole, 64 is an exhaust passage, and 65 is a temperature control heat medium passage. With the configuration shown in this figure, a PEEK resin layer having a thickness of 0.1 to 2 mm is formed on the back body of the aluminum material 5052, and a fine thermocouple is exposed on the molding surface through the back layer and the surface layer. The mold is high performance. In addition, temperature control means, such as this heat-medium channel | path, are not provided here, You may make it provide arbitrary heating means for the fixing plate which fixes a shaping | molding die.

  When the surface layer is directly heated, the heat permeability and dimension of the surface layer are the same as those in the case of indirect heating temperature control, and the desirable configuration is also the same. The formation of the heating means is not limited to this, and there is a method in which a) a planar heating layer is formed behind the surface layer, and b) a planar high heat transfer layer is formed to conduct heat from a specific position. In this case, the back body (layer) is not particularly limited in terms of the presence, material, or shape, and if the surface layer or heating means can be held without hindering the function of the heating means, and the mold itself can be fixed somewhere. Good.

  In addition, the mold shown as a desirable aspect for the configuration of the present invention is a prior application in which the present inventor is an inventor, Japanese Patent Application Nos. 2010-118555, 2010-118490, 2010-118489, Japanese Patent Application No. 2010-118562, and This is disclosed in either Japanese Patent Application No. 2001-065069 or Japanese Patent Application No. 2011-165069.

<About molding method>
Using the molding apparatus of the present invention described above, a method for molding a thermoplastic resin sheet comprising a resin sheet preheating step, a shaping step, a heat treatment step for heat treatment at a temperature higher than the preheating step, and a cooling step is performed. Can do. Moreover, these processes can be advanced at high speed, and efficient continuous molding can be performed using a long molding material resin sheet.
In the above molding process, the resin sheet is preheated with a preheating oven or a heating plate, then guided to the female mold and the male mold, and the female mold or the male mold is moved up and down, and both molds are fitted by mixing the resin sheets. Then, it is formed by heating and cooling the shaped body by gas injection, separating both molds and releasing the shaped body.
Methods for heating the shaped body include 1) a method of ejecting heated gas from the injection mold, and 2) a method of heating and using the holding mold, both of which may be used. You can also use one or the other.
There are two methods for cooling the form: 1) a method of ejecting a relatively low temperature gas from the ejection type, and 2) a method of using the holding type while maintaining the temperature at a relatively low temperature. However, it can also be performed using any one of them. Among these cooling methods, at least a method of ejecting a relatively low temperature gas from the above injection mold is preferably used.
As a shaping method, a) a method by completely mating male and female dies, b) a method using both male and female dies incomplete fitting and vacuum, and c) using both male and female dies incomplete fitting and compressed air. Method, d) Any of the respective methods of vacuum shaping (vacuum shaping is preceded and male and female molds are incompletely fitted) can be adopted. However, in the method in which gas is injected from the above injection type and combined with compressed air shaping, the cooling gas can be used as it is, or the heating gas can be used as it is, which is convenient. Can be preferably employed.
In addition, without using an oven or other device for preheating the resin sheet, the unheated resin sheet is guided between the injection mold and the holding mold, and slowly fitted while injecting heated gas from the injection mold. It can be shaped by a predetermined method. In this case, the molding apparatus may not include a preheating device such as an oven.

The condition setting of the above-described molding method can be broadly described in three patterns.
The molding process involving heat treatment can draw a sine curve-like continuous molding cycle when looking at changes in the surface temperature (T) of the mold and the internal temperature (S) of the mold. As an example, consider the case of using a mold consisting of a surface layer and a back layer as described above. The back layer temperature is S, the mold surface temperature is T, and the maximum temperature is Tt and the minimum temperature Tb.
Pattern A is a pattern in which S is adjusted to a constant temperature between Tt and Tb of the surface temperature cycle. In this case, Tt is a temperature reached by high-temperature gas injection, and Tb is a temperature reached by the cooling means. Direct temperature control of the back layer may or may not be performed. If molding is continued continuously for a long time in a state in which heat does not escape much from the back feeding, the back layer temperature S settles between Tt and Tb of the surface temperature cycle. In this case, if the thermal permeability of the back layer is not so large, S is not linear in time in the vicinity of the surface layer, but draws a small temperature cycle following the surface layer. It is desirable to adjust the temperature of the back layer to an appropriate temperature, and the heating means and the cooling means can be set to the optimum shortest time depending on the temperature.
Pattern B is a pattern for adjusting S to a constant temperature equal to or lower than Tb. In this case, Tb is reached mainly by heat transfer at the temperature of S in the back layer. The cooling means is not essential, but if used, the cycle can be shortened. Tt is reached by high temperature gas injection.
Pattern C is a pattern for adjusting S to a constant temperature equal to or higher than Tt. In this case, Tt is reached mainly by the heat transfer from the back layer, that is, the temperature of S. Therefore, the heating temperature control of the back layer is essential. Although heating by high-temperature gas injection is not essential, the cycle can be shortened if used. Note that Tb is reached by cooling gas injection.
In the configuration of the molding apparatus of the present invention, molding with heat treatment can be performed at a high speed corresponding to any of the A, B, and C patterns.

Normal thermoforming is performed through the process of preheating, shaping, cooling and releasing the resin sheet. On the other hand, the molding method of the present invention is characterized by performing a heat treatment at a temperature higher than that at the time of shaping of the resin sheet between shaping and cooling, and is characterized by being able to be performed at high speed continuously. .
The method of the present invention makes it possible to produce various molded products that are easily heat-treated with a wide range of resins. Specific applications include: a) molding involving heat setting of a stretched sheet of a crystalline resin such as PET, b) molding involving crystallization of a crystalline resin sheet such as a crystal nucleating agent-added PET (CPET), or In addition, c) heat treatment molding can be proposed in which the residual stress distortion associated with SPPF molding (solid phase high pressure molding) of polypropylene is relaxed.
In particular, stretched PET can efficiently produce a thermoformed product having excellent mechanical strength such as heat resistance, transparency, and rigidity. Further, a material-saving molded product can be obtained by utilizing rigidity.
(Supplementary explanation about the contents of the present invention)

(1) <About heat penetration rate>
The thermal permeation rate (b value) used as the specified value of the present invention is a characteristic value of an object related to the amount of heat moving through the interface and the contacting object, and is obtained by the following equation.
b = (λρC) ^1/2 (1)
λ; thermal conductivity (J s ⁻¹ m ⁻¹ K ⁻¹ )
ρ; density (kg m ⁻³ )
C; Specific heat (J kg ⁻¹ K ⁻¹ )
An object having a small b value flows only a small amount of heat to the interface and does not give a large temperature change to the counterpart object, and is greatly influenced by the counterpart object near the interface.
Therefore, when the material having a small b value is used as the mold surface material, the heat from the shaped body is not diffused, so that the shaped body can be easily heated and cooled by the high-temperature gas and the cooling gas. However, since the heat of the back layer is not easily transferred to the surface layer surface (interface with the shaped body), the surface temperature is highly uniform, and the surface layer thickness is reduced for fast and stable condition setting. Or by increasing this b value to some extent, it can be optimized in accordance with the molding material.
In addition, as a reference example of the b value, for example, the aluminum material is about 17 to 23, the iron material is about 13 to 16, the copper is about 34, the non-rust steel (SUS306) is 8.0, and many synthetic resins are 0.0. About 2 to 0.8, many ceramics fall between 1 and 20.
Table 1 illustrates the b values of some materials. The b value also shows a slightly different value depending on the measurement temperature, but in the present application, strictly, it is defined by a measurement value of 20 ° C. However, in the case of a composite material with a material having no linearity in a change between 20 ° C. and 200 ° C., for example, a heat storage agent accompanied by a phase change, an average value of 100 ° C. and 150 ° C. should be adopted. To do.
It should be noted that even if the same material is used, if the shape changes to a foam or a porous body, this value will change greatly.

(2) <Significance of numerical limitation of mold configuration>
When a surface material having a large thermal permeability b value is used as the surface layer of the mold, heat is easily dispersed from the shaped body to the back, so that heated air or cooling air having a relatively small heat capacity is used. Then, it becomes impossible to heat and cool the shaped body easily, and when this value is more than 25, it is not possible to efficiently perform the heat treatment. This value is preferably small, but if it is smaller than 0.01, there is no material that can withstand use such as strength. The above mold has a structure of two or more layers, the back layer of the surface layer is controlled to a constant temperature, and the molding surface temperature of the surface layer that changes in temperature by the heating gas and the cooling gas through the shaped body is set to a desired level. Quick return to the reference temperature.
In this case, if the thickness of the surface layer exceeds 30 mm, the control of the back layer takes too much time to reach a steady state in response to the surface temperature, which is not practically effective. Moreover, when this thickness is less than 0.03 mm, the influence of the temperature of a back layer is received greatly, and the effect which accelerates | stimulates temperature rising / falling of a quick shaping body loses. For example, in a known molding method, even if a mold such as a fluorine resin is temporarily formed on the mold for lubrication and release, the coating thickness is as thin as 30 μm or less. There is no need to do this, and it is difficult to apply a thick and smooth coating.
As described above, a single material may be used, but in this case, there may or may not be direct temperature control on the mold, and in either case, the desired surface temperature may be stabilized to some extent. If the time is taken, the desired molding is possible. However, in this case, it is preferable that the heat permeation rate b value (kJ / m ² s ^1/2 K) is made of a single material having a temperature of 0.01 to 3 without a heating temperature adjustment mechanism. As for those composed of three or more single materials, those equipped with a heating temperature control mechanism can be used more preferably.
In addition, it is desirable that the above-mentioned mold has a fine hole that enables vacuum forming or evacuation at the time of forming, and is housed in the above-mentioned mold storing box so as to be evacuated.

(3) <Temperature measurement of shaped body>
In the apparatus of the present invention, it is important to measure the change in the surface temperature of the mold or the interface temperature between the mold and the shaped body or the temperature change of the shaped body by some method. Specifically, for example, an extremely delicate measurement probe, for example, a thermocouple tip having a wire diameter of about 0.1 mm is projected on the molding surface of the mold, and this can be measured. As another method, there is a method of measuring the shaped body from the opposite surface without contact with an infrared thermometer. However, there are points to note.
In the patterns A and C, the temperature of the S-line is actively controlled to control the temperature of the mold itself. However, depending on the distance from the molding surface or the distance from the heat source, the molding cycle is repeated with a temperature gradient. It is also a value that stabilizes at.
When strictly considering the heat treatment temperature or mold release temperature of the shaping material, it should be noted that these temperatures are considerably different from the surface temperature or interface temperature shown here. This is because when heating and cooling are performed in units of seconds or less, a large temperature gradient occurs in the thickness direction of the shaped body. Also, temperature measurement from the back of the shaped body with infrared rays or the like does not accurately represent the material temperature. In the present invention, it is expressed by the surface temperature (interface temperature), but there is a difference from this temperature and it is necessary to consider it as a relative value.

Using the mold shown in FIG. 2, the stretched PET sheet was molded with heat treatment.
1) Molding material: A 2.3 times uniaxially stretched sheet of homopolyethylene terephthalate resin (though not heat-set) and a thickness of 0.23 mm were used.
2) Molding equipment
Molding machine: A single-wafer vacuum / pressure forming machine having a pressure capacity of 10 tons was used.
Mold: A fully-fitting male-female mold having a structure shown in FIG. 2 for forming a circular dish having a diameter of 90 mm and a depth of 30 mm.
Injection type (male type): Five gas injection holes having a diameter of 1.5 mm were provided around the top of the molding surface of the injection port 41 made of aluminum A5052. The molding surface was coated with 30 μm of tetrafluoroethylene resin. It should be noted that when the gas injection mold is lifted slightly after fitting and shaping, the molded product shape design is such that a gap is formed where any part of the shaped body is separated and gas can freely flow.
Holding type; surface layer / back body system shown by 60 in FIG. 2, with aluminum A 5052 (b value 17.4) as the back layer, and PEEK resin (b value 0.35) 0.14 mm on it The surface layer was formed by a coating baking method.
The outer dimension of the mold was 110 mm square, and the surface layer was indirectly heated through a heating medium in the heating medium passage of the back body.
Temperature measurement: The tip of the thin wire thermocouple was exposed on the molding surface to allow measurement of the molding surface temperature and the shape body interface temperature.
3) Molding method and molding conditions;
Preheating of resin sheet: The resin sheet was preheated and moved for 9 seconds in a preheating oven set at 550 ° C. and placed on the upper part of the mold. The sheet preheating temperature is 95 ° C.
Injection mold molding surface preheating temperature: 95 ℃
Preheating temperature of holding mold surface; 185 ° C
Shaping process: Shaping for 0.4 seconds by mold fitting
However, the vacuum operation of the shaped object holding type was started at the same time.
The molding surface instantaneously decreased to 163 ° C.
Temperature rising and heating process: 0.8 seconds
Immediately after shaping, the gas injection mold was lifted and held as it was, and the temperature was raised due to heat transfer. The surface temperature was about 180 ° C.
The mold float was 6 mm, and a gas injection space (gap) of 3 to 6 mm was formed.
Cooling step: Gas injection 3.2 seconds Compressed air having an original pressure of 0.7 MPa was introduced and injected at about 30 ° C.
The injected gas was exhausted from the periphery of the flow type along the gas injection space (gap). After the air injection, the injection mold was separated again to release the mold. The surface temperature at the time of mold release was about 170 ° C. In addition, the vacuum holding of the shaped body was continued until release.
4) Molding result;
The obtained molded product had a good shape. The test was immersed in silicon oil having a heat resistance of 130 ° C. for 2 minutes, and there was no deformation or noticeable shrinkage, and the heat resistance was excellent. In addition to using a mold with a surface layer with relatively low thermal permeability, it was found that this mechanism enables powerful jet cooling.

Using the mold shown in FIG. 3, the material-stretched PET sheet was changed to perform molding with heat treatment.
1) Molding material: Homopolyethylene terephthalate resin 2.5 times uniaxially stretched sheet (however, not heat-set), thickness 0.23 mm was used.
2) Molding device Molding machine: The same one as in Example 1 was used.
Mold: A fully-fitting male and female mold that molds a round dish with a diameter of 90 mm and a depth of 30 mm. However, the structure shown in FIG.
A jet type (male type): a structure having the structure shown in FIG. The molding surface was coated with 30 μm of tetrafluoroethylene resin. In addition, when the gas injection mold is lifted slightly after fitting and shaping, the molded product shape design is such that a gap is formed where any part of the shaped body is separated and gas can freely flow.
A holding type (female type); a structure of FIG. 3 constituted by a single body of S45C (b value 14.0) was used. The outer dimension of the mold was 110 mm square, and the surface layer was indirectly heated through a heating medium on the back body.
3) Molding method and molding conditions Preheating of resin sheet; 95 ° C
The same operation as in Example 1 was performed.
Injection mold molding surface preheating temperature: 95 ℃
Preheating temperature of holding mold surface; 198 ° C
Shaping process; vacuum fitting shaping; 0.4 seconds,
However, the vacuum operation of the shaped object holding type started simultaneously with the shaping.
The surface temperature instantaneously became about 175 ° C. almost simultaneously with shaping.
Heating and heating step; 0.3
Immediately after shaping, the injection mold was lifted and held as it was, and the temperature of the shaped body was increased due to heat transfer. The surface temperature remained at about 175 ° C.
The mold float was 6 mm, and a gas injection space (gap) of 3 to 6 mm was formed.
Cooling step; gas injection from the injection mold for 3.7 seconds
Compressed air of about 30 ° C. and an original pressure of 0.7 MPa was introduced and injected.
Valve operation was performed so that the gas injected into the injection space (gap) was accommodated in the exhaust body through the suction hole and exhausted to the outside.
The surface temperature at the time of mold release was about 170 ° C. The vacuum holding of the shaped body was continued until release.
3) Molding result;
A good molded product was obtained in the same manner as in Example 1. Despite the use of a mold with a relatively high thermal permeability, it was found that mold release was possible in a short time, and that this mechanism was capable of powerful jet cooling.
In this example, the surface temperature does not show a great change during the heat treatment and cooling, but it is a powerful cooling jet and has a cooling effect with a large temperature gradient in the thickness direction of the shaped body. It is considered possible.

Using the mold shown in FIG. 4, the stretched PET sheet was molded with heat treatment.
1) Molding material: Homopolyethylene terephthalate resin 2.5 times uniaxially stretched sheet (however, not heat-fixed), thickness 0.21 mm was used.
2) Molding device Molding machine: the same as in Example 1 was used.
Mold: A male / female mold having an incomplete fitting (loose fitting) for forming a circular dish having a depth diameter of 90 mm and a depth of 30 mm and having a structure shown in FIG.
The injection type is made smaller than the shaped object holding type, and when fitted, a uniform gap space of about 6 mm is formed.
Injection type (male type): a structure shown in FIG. 4 comprising an air supply 41 and an exhaust 51 made of aluminum A5052. The molding surface was coated with 30 μm of tetrafluoroethyne resin. The gas supply 41 injects a high-temperature gas, then takes in a low-temperature gas and exhausts it, and the exhaust body 51 first takes in the high-temperature injection gas and exhausts it.
Holding type; surface layer / back body system shown by 60 in FIG. 4, with aluminum A 5052 (b value 17.4) as the back layer, and PEEK resin (b value 0.35) 0.3 mm on it A surface layer formed by a coating baking method was used.
The outer dimension of the mold was 110 mm square, and the surface layer was indirectly heated through a heating medium in the heating medium passage of the back body.
3) Molding method and molding conditions Preheating of resin sheet; 95 ° C
The same operation as in Example 1 was performed.
Injection mold molding surface preheating temperature: 95 ℃
Preheating temperature of holding mold surface; 130 ° C
Forming step: Performed by fitting and vacuum forming. Shaping is completed in an instant.
The vacuum operation was started simultaneously with the mold fitting. The surface temperature was about 130 ° C. and there was no significant change.
The mold was fitted to the position where the horizontal surface of the gas injection mold floated leaving a gap of 6 mm.
Heating temperature raising step: High-temperature air was jetted from the jet-type gas supply for 2.8 seconds.
The jet gas was contained in an exhaust body and exhausted.
The jet gas temperature was 310 ° C. The surface temperature was raised to 180 ° C.
Cooling step: Low-temperature air was injected from the injection-type exhaust body for 1.5 seconds.
The jet gas was contained in a gas feed and exhausted.
The introduced gas was compressed air having an original pressure of 0.4 MPa at about 30 ° C.
After gas injection, the gas injection mold was separated again to perform release.
In addition, the vacuum holding of the shaped body was continued until release.
The surface temperature at the time of mold release was 135 ° C.
4) Molding result;
A good molded product was obtained. The molded product was resistant to silicon oil heat of about 130 ° C., and the heat treatment was effective.

Using the mold shown in FIG. 5, the stretched PET sheet was molded with heat treatment.
1) Molding material: The same material as in Example 2 was used.
2) Molding device Molding machine: The same one as in Example 1 was used.
Mold: Unable to mold round dish shape with a diameter of 90mm and a depth of 30mm
A male-female mold having a complete fitting (loose fitting) and having a structure shown in FIG.
Note that the gas injection type is smaller than the shaped object holding type, and when fitted, a closed space is formed with a uniform gap of about 6 mm.
Injection type (male type): The structure shown in FIG. 5 comprising an injection port 41 and an exhaust port 51 made of aluminum A5052. The molding surface was coated with 30 μm of tetrafluoroethylene resin. As in the case of the third embodiment, the gas supply 41 injects a high temperature gas, then takes in a low temperature gas and exhausts it, and the exhaust body 51 first takes in the high temperature injection gas and exhausts it, but in the next step, the low temperature gas is exhausted. It is a mechanism to inject.
This mold is provided with a bank (closing wall) for forming a closed space.
Holding type; surface layer / back body type shown in 60 of FIG. 5, with aluminum A052 (b value 17.4) as the back body, on which PEEK resin (b value 0.35) 0.14 mm A surface layer formed by a coating baking method was used. The outer dimension of the mold was 110 mm square, and the surface layer was indirectly heated through the heating medium passage in the heating medium passage of the back body.
3) Molding method and molding conditions;
Preheating of resin sheet; 95 ° C
The same operation as in Example 1 was performed.
Injection type gas supply set temperature; 270 ° C
Injection type exhaust body set temperature: 95 ° C
Preheating temperature of holding mold surface; 160 ° C
Forming process: After mold fitting, vacuum / pneumatic forming by hot gas injection and vacuum operation was activated. The hot gas was injected for 0.3 seconds from the gas injection type gas supply, which led to the next process of opening the exhaust valve of the exhaust body.
The introduced hot gas is the same as the next step.
The surface temperature temporarily decreased slightly to 158 ° C.
Heating temperature raising step: Heating air was jetted from a gas jet type gas supply for 2.8 seconds.
The valve of the exhaust body was opened, and the injection gas was accommodated in the exhaust body and exhausted.
The jet gas temperature was 265 ° C. The surface temperature was raised to 181 ° C.
Cooling step: Low-temperature air injection was performed from an injection-type exhaust body for 0.8 seconds.
The jet gas was contained in a gas feed and exhausted.
The injected low-temperature air was injected by introducing compressed air having an original pressure of 0.4 MPa at about 30 ° C. After gas injection, the gas injection mold was separated again to perform release.
In addition, the vacuum holding of the shaped body was continued until release.
The surface temperature at the time of mold release was 135 ° C. The surface temperature at the time of mold release was 158 ° C.
4) Molding result A good molded product was obtained. The molded product withstood at least about 140 ° C. silicone oil, and heat treatment was effective.

The following is possible for thermoforming according to the present invention.
(1) A molding process involving heat treatment and cooling mold release for heating the shaped body above the preheating temperature for shaping can be carried out at a very high speed, continuously, efficiently and stably.
(2) A specific application that requires such heat treatment is thermoforming that involves heat setting of a stretched crystalline resin sheet. Examples of the material include stretched sheets such as PLA, thermoplastic resin such as PET, crystalline resin such as polypropylene, polyamide, and PEEK.
(3) Among them, in particular, by performing thermoforming that performs the above heat treatment using a stretched PET sheet, it is possible to efficiently produce thermoformed products having excellent mechanical strength such as heat resistance, transparency, and rigidity. Can do. Further, it is possible to obtain a material-saving molded product using rigidity, and to meet the social needs of resource saving.
(4) A crystalline resin sheet that has not been subjected to stretching treatment, for example, can be used for molding involving crystallization of PET (CPET) to which a crystal nucleating agent is added, and this can be performed at a higher speed than before. it can.
(5) In addition, expecting a new method, etc. that can be applied to SPPF molding of polypropylene (solid phase high pressure molding) to solve the disadvantages of this molding method (reducing residual stress distortion and improving heat-resistant dimensional stability). Can do.
(6) Molding with heat treatment can be performed precisely, uniformly, without variation, at high speed and with energy saving, and the improvement in strength and rigidity due to orientation and crystallization has been converted to a material with reduced thickness, It is possible to contribute to the social needs for resource conservation.

11 Press machine top plate 12 Press machine bottom plate 13 Insulation material 40 Injection mold (part of male and female mold)
41 Injection port (changes to exhaust port function from the middle of the process depending on the mode)
42 Air supply passage (changes to exhaust passage from the middle of the process depending on the mode)
43 branch passage (changes to the air collection passage from the middle of the process depending on the mode)
43b Relay space 44 Molding surface 45 Injection hole (changes to intake hole in the middle of the process depending on the mode)
46 Gas introduction passage 47 Heater 48 Air supply board 49 Operation valve 50 Injection space (gap)
51 Exhaust port (changes to the function of air supply port from the middle of the process depending on the mode)
52 Exhaust passage (change from the middle of the process to the air supply passage depending on the mode)
53 Air collection passage (changes to a branch passage from the middle of the process depending on the mode)
53b Relay space 54 Heater 55 Intake hole (change from the middle of the process to a gas injection hole depending on the mode)
56 Exhaust passage 57 Heater 58 Heat insulation material 59 Operation valve 51b Bank (closing wall)
60 Holding mold (part of male and female mold)
61 Surface layer
62 Back layer (back body)
63 Vacuum exhaust hole
64 Vacuum exhaust passage 65 Heat medium passage
66 Stacking plate
110 Shaped body of thermoplastic resin sheet A Compressed gas
A 'Exhaust HA High-temperature compressed gas HA' High-temperature exhaust

Claims (6)

In thermoforming apparatus using the male and female molds of the resin sheet, it gave a function to inject a heating gas body and the cooling gas to the gas injection hole provided in the molding surface of either type of the female and male injection Using a mold and a holding mold that is opposite to the injection mold and holds the shaped body closely on its molding surface,
Comprising at least one compressed gas introduction means for cooling or heating the injection mold,
Further, in the holding mold, at least the molding surface has a heat permeability (b value) (kJ / m ² s ^{1 /
2} K) using a surface layer of a material having a value of 0.01 to 20 and a back body of a material having a b value larger than the surface layer behind the surface layer,
Furthermore, as means for heating the shaped body held in the holding mold to a temperature higher than the preheating temperature of the resin sheet, 1) means for injecting heated gas from the injection mold, or 2) heating the holding mold Use at least one of the means to use,
A thermoplastic resin sheet configured to heat and cool the shaped body held in the holding mold by injecting the compressed gas from the injection mold at a distance away from the shaped body after shaping the resin sheet. Molding equipment. The molding apparatus according to claim 1, wherein a heating temperature adjusting means is provided on the back body in the holding mold. In the injection type, in addition to a mechanism for injecting gas from the gas injection hole, a mechanism for inhaling and exhausting the injected gas from an intake hole provided separately from the injection hole is provided. The molding apparatus according to claim 1 or 2. In the course of one molding cycle, the functions of the mechanism for injecting the gas and the mechanism for exhausting the gas are exchanged with each other, and the compressed gas for heating is injected through the former mechanism to inject the exhaust. The molding apparatus according to any one of claims 1 to 3, wherein the molding apparatus is configured to inject and exhaust the compressed gas for cooling through the latter exhausting mechanism. The male and female molds are configured to form a compressed air space that is closed when the resin sheet is sandwiched between them and to perform compressed air shaping by injecting the compressed gas from the injection mold. The molding apparatus according to any one of claims 1 to 4, wherein A resin sheet molding method using the molding apparatus according to any one of claims 1 to 5, wherein the resin sheet is preheated, shaped, and heat treated at a temperature higher than the sheet preheating temperature.
And the molding method of a thermoplastic resin sheet provided with a cooling process.

Images