JP2013028048A - Thermoforming device and forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoforming device and forming method, capable of efficiently and continuously performing thermoforming at a high speed, in which a shaping body is heated at a high speed or heated at a high speed and subjected to a cooling stroke in a process from the shaping of thermoforming to mold release, in particular, the mold release is performed by performing heat treatment at a high temperature equal to or more than a preheated sheet temperature before the shaping.SOLUTION: In this device for forming a thermoplastic resin sheet, at least one of heating and cooling of a shaping body of a resin sheet fixed to a mold is performed by a means for jetting a heat medium or radiating infrared rays. Further, as the mold, a structure including a surface layer comprising a material having a heat penetration rate (kJ/m2s1/2K) of 0.01-15 and a heat generating means spreading over the entire development surface of the layer or a means for enhancing heat transfer of the layer in the development surface direction is used.

Description

  The present invention relates to a method for producing a thermoformed product 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, in particular, crystalline resin is used for high-speed and efficient production of thermoformed products with high properties such as heat resistance, transparency, and mechanical strength by performing heat treatment higher than the preheating temperature of the resin sheet. It is related with performing this thermoforming using the extending | stretching sheet | seat.

The thermoforming method is a method in which a preheated thermoplastic resin sheet or film is formed on a mold by pressing or evacuation and then released. Usually, the shaped body is released in a cooled state with a low-temperature mold. Typed. As the mold material, a material such as aluminum or zinc alloy that is lightweight and has good workability and good thermal conductivity is used, and 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 heating or cooling the shaped body arbitrarily during the molding cycle, the heating medium passed through the jacket is changed in the middle or the shaped body is temperature-controlled separately It is done to move to. However, such a method is inconvenient for efficiently producing a molded product subjected to a desired heat treatment at a high speed continuously.

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 shows a method of forming with a high-temperature female mold, taking it into a low-temperature male mold fitted thereto, cooling it, and releasing the mold. It may be said that the method is the same as (4), and deformation and wrinkling of the molding become a problem as well, 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.
In addition, the disclosure of (6) Japanese Patent No. 4044876 relates to thermoforming of a resin material in which sag (hanging of the sheet during heating) is likely to be a problem during sheet preheating. In such a material, a material sheet is usually used as a porous heating plate. After adsorbing for a short time, it is shaped away from it. In the case of this method, it is intended to avoid scratches at the time of adsorption of the hot plate, and the sheet is heated while supporting the sheet with the pressure of weak heated air, and then additional preheating is performed with the air passed through the hot plate. However, it does not require heat treatment at a temperature equal to or higher than the preheating temperature after shaping, nor does it require active cooling and mold release, and there is no suggestion to do this. In addition, since the stretched sheet formed by the apparatus of the present invention causes a shrinkage action to preheating, if the sheet end is fixed and this is done, it becomes a tension state and the problem of sag does not occur.
(7) The method disclosed in Japanese Patent No. 4057487 relates to thermoforming of a crystalline resin, and a sheet preheated by being brought into contact with a heating plate is compressed and compressed with heated compressed air passing through the heating plate and a molding die. Then, cooling air injection means prepared separately is carried and cooled. When the shaped body is to be heat-treated, it is necessary to use a very high temperature gas because the mold is deprived of heat. When this is passed through a heating body adjusted to the preheating appropriate temperature of the sheet, various inconveniences occur. The heated gas is cooled in a conduit passing through the heating plate, and the heating plate is locally heated to make the temperature non-uniform, which hinders good molding. For this reason, it cannot heat-process using sufficient high temperature gas, and cannot perform high-speed shaping | molding.
(8) The inventor of the present invention (hereinafter referred to as the present inventor) has filed a plurality of applications related to the present invention prior to this. 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 Japanese Patent No. 2532730 Japanese Examined Patent Publication No. 7-102608 Japanese Patent No. 4044876 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 thermoforming apparatus that can perform thermoforming for releasing at high speed and efficiently and can obtain a molded product in a uniform and good state.

(1) In a thermoforming apparatus configured to perform at least one of heating and cooling of a shaped body of a resin sheet fixed to a mold by means of spraying a heat medium or irradiating infrared rays, And a surface layer made of a material having a thermal permeation rate (b value) (kJ / m2s1 / 2K) of 0.01 to 15, and heat generating means spreading over the entire development surface of this layer or heat in the development surface direction of this layer The present invention provides a thermoplastic resin sheet thermoforming apparatus using a structure having means for promoting movement.
In the present invention, the “surface layer” refers to a layer including the molding surface of the mold. “Shaping” and “shaping step” indicate a part of the operation during molding, and “shaped body” means a molded product held in a mold.
Note that 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.
The heat permeability of the surface layer material is preferably 10 or less, more preferably 5 or less, and even more preferably 3 or less. The thickness of the surface layer is preferably 0.04 mm or more.
The surface layer may be a single layer or multiple layers as long as the entire layer satisfies the above constraints.

(2) The resin sheet shaped body fixed to the mold is heated by means for injecting heated gas or by means for irradiating infrared rays, and then cooled by means for injecting a cooling heat medium. The molding apparatus according to the above (1), characterized in that it is configured, is provided.

(3) The above mold (1) or (2), wherein the mold is configured to steadily heat the surface layer by heat generating means in close contact with the substantially entire surface behind the surface layer. ) Is provided.

(4) The molding apparatus according to any one of (1) to (3), wherein the molding die is configured such that the surface layer itself generates heat.

(5) The molding die is provided in close contact with the substantially entire surface behind the surface layer, and a heat storage uniform layer made of a material having a thermal permeability (kJ / m2s1 / 2K) larger than that of the surface layer is provided. The molding apparatus according to any one of the above (1) to (4), characterized in that a back body made of a material having a smaller heat permeability than that of the heat storage and homogenization layer is provided on the back. To do. The heat permeability of the material for the heat storage homogenization layer is preferably 10 or more, and more preferably 15 or more.
The warp of the back body is preferably 15 or less, and more preferably 10 or less. The thickness of the heat storage homogenizing layer is preferably 10 mm or less, and more preferably 5 mm or less. Further, this thickness is preferably 0.01 mm or more, and more preferably 0.03 mm or more.

(6) A configuration in which the molding die is in close contact with substantially the entire surface behind the surface layer, and a temperature uniformizing layer made of a material having a thermal permeability in at least one direction of the development surface larger than that in the thickness direction is formed. The molding apparatus according to any one of the above (1) to (5) is provided.
The means for heating and controlling the surface layer may be provided separately from the mold, but it is preferable that the mold itself has a heating means for constantly heating the temperature uniformizing layer.

(7) The mold has a material in which the heat permeability in the thickness direction of the surface layer has the predetermined value and the heat permeability in at least one direction of the plane has an arbitrary value larger than that in the thickness direction. The molding apparatus according to any one of the above (1) to (6) is provided.
In addition, although the means for heating and controlling the surface layer may be provided separately from the mold, it is preferable that the mold itself has a heating means for constantly heating the surface layer.

(8) A resin sheet molding method using the resin sheet molding apparatus according to any one of (1) to (7) above, wherein the resin sheet preheating step, the shaping step, and the shaped body are resinized. It is an object of the present invention to provide a thermoplastic resin sheet forming method for performing a heat treatment step for raising the temperature to a temperature higher than the sheet preheating temperature and a cooling step.

<Advantages of the present invention>
When heating and cooling a shaped body by jetting a gas cooling medium, or by infrared irradiation or jetting of a gas heating medium, large heat is transferred between the mold surface layer and the heating medium through the shaped body. Large temperature irregularities are likely to occur depending on the part of the mold.
This is due to the presence of non-uniformity in the injection of the heat medium, the difference in distance due to the infrared irradiation part, the part that is easily affected by the heat medium such as the tip part or the edge part, and the part that is difficult to be affected such as the back part. And this nonuniformity tends to become large when it repeats and repeats forming.
Under the influence, the molded product tends to be non-uniform in transparency, shape, and the like, and in extreme cases, even a melt crack occurs at a sharp edge.
The mold used in the present invention is a novel mold itself having a function of eliminating the temperature unevenness of the surface layer. And when it is used as a component of the apparatus of the present invention, the above-mentioned temperature unevenness is eliminated, and a uniform molded product can be efficiently and continuously increased in speed.
In addition, the above-described effects can reduce the restrictions on the performance, position, number, and the like of the heating and cooling medium jet nozzles, facilitate the overall design of the apparatus, and reduce the cost of the apparatus.

It is sectional drawing which shows the principal part of the shaping | molding apparatus of this invention. It is sectional drawing which shows another principal part of the shaping | molding apparatus of this invention. It is sectional drawing which shows the shaping | molding die which comprises the shaping | molding apparatus of this invention. It is sectional drawing which shows another shaping | molding die which comprises the shaping | molding apparatus of this invention. It is sectional drawing which shows another shaping | molding die which comprises the shaping | molding apparatus of this invention. It is sectional drawing which shows another shaping | molding die which comprises the shaping | molding apparatus of this invention. It is sectional drawing which shows another shaping | molding die which comprises the shaping | molding apparatus of this invention.

<Configuration of molding apparatus>
The molding apparatus of the present invention constitutes a thermoforming machine such as a vacuum / pressure forming machine, a pressure forming machine, a vacuum forming machine, and a fitting die press forming machine. The constitution of the present invention may be constituted by a known thermoforming machine, and the preheating of the resin sheet may be a direct heating method using a heating plate, or an indirect heating method using an infrared oven, a hot air oven or the like.
Further, it may be a sheet-fed molding machine that molds a short material sheet one by one, or may be a continuous molding machine that molds a long material sheet sequentially from one end, and the latter is particularly preferable. .
The molding apparatus of the present invention is provided with at least one of 1) a cooling means by jetting a cooling medium, 2) a heating means by jetting a heated gas, and 3) a heating means by irradiating infrared rays in the molding machine described above. It is configured such that at least one of heating and cooling of the fixed shaped body of the resin sheet can be performed by any of these means. A mold having a structure in which a surface layer made of a specific material and heat generating means spreading over the entire development surface of this layer or means for promoting heat transfer in the development surface direction of this layer are combined is used.
When continuous molding is performed with a normal mold using the heating means or cooling means as described above, heat is diffused into the mold and heating or cooling cannot be performed easily, or a specific part of the mold Tends to be overheated or overcooled, and easily produces molding unevenness and defects in the molded product.
It is possible to make good use of the molding die of Japanese Patent Application No. 2010-118555 of the prior application in which the present inventor is the inventor. However, the mold used in the present invention is a new one which is a further improvement of the mold of the prior application in view of the above-mentioned problem tendency, and heats and cools the shaped body by heat medium injection or infrared irradiation effectively uniformly and at high speed. be able to.
Hereinafter, description will be made separately for each component of the cooling means, the heating means, the mold, and the molding method.

<About the structure having a cooling means>
One aspect of the apparatus configuration of the present invention is a configuration having a cooling means by injection of a cooling heat medium and not having a heating means by heat medium injection or infrared irradiation.
The cooling means is located in the upper part or the periphery of the mold, and after cooling the resin sheet, the cooling medium is injected from the upper part of the mold toward the shaped body sucked and fixed to the mold to perform cooling. Composed. As the cooling medium, compressed gas such as air, nitrogen and carbon dioxide, volatile liquid such as water and alcohol can be used alone or in combination. There is also a method of spraying powder particles such as dry ice together with air. The injection device may inject from a hole in the perforated plate, may inject an arbitrary injection nozzle, and any known device can be used.
A specific example of the apparatus of the present invention is shown in FIG. This figure shows a process in which the cooling means 40 operates on the upper part of the mold and cools the shaped body sucked and fixed to the mold after the compressed air or vacuum shaping. The compressed air A is distributed through the branched conduit 44, is injected from the injection nozzle 43, collides with the surface of the shaped body 110, is reflected, and escapes through the pipe gap 46. Reference numeral 45 denotes a fixed frame such as an introduction pipe, and 60 denotes a molding die. In the configuration of this figure, the heating means is not present and is not shown. However, even if the heating means is not present, if the molding process is performed with the surface temperature of the mold sufficiently high, the shaped body can be heat-treated. it can.

<Configuration with heating means>
Another aspect of the apparatus configuration of the present invention is a configuration having heating means by heat medium injection or infrared irradiation, and no cooling means by cooling heat medium injection.
1) The means for injecting the heated gas may be an externally heated compressed gas introduced and injected from the nozzle, or a normal compressed gas introduced into the box and heated and injected from the pores. Any known method can be used. In addition, it is efficient and preferable to perform the temperature raising heat treatment of the shaped body continuously while performing compressed air shaping with a high-temperature compressed gas.
2) The means for irradiating infrared rays can be implemented by bringing the irradiating means such as an infrared irradiation lamp and a high heat infrared radiation plate close to the shaped body. It is desirable that the radiation efficiency of the surface of the infrared radiation plate is enhanced by black body paint or the like. Specifically, the irradiation means may be brought closer to the shaped body while performing vacuum forming, or infrared radiation may be emitted by a radiation plate provided at the bottom of the compressed air box while performing compressed air shaping. In addition, near infrared rays and far infrared rays can be suitably used as infrared rays.
These heating means are very convenient when added to a pressure box for pressure forming. A specific example is the heated compressed air box shown in part of FIG. The heated pressurized gas may be introduced from the outside, or the room temperature compressed gas may be heated in the compressed air box. The heating means described above may be arbitrarily constructed separately from the infrared pressure pneumatic box.
When the temperature of the heat treatment is increased by the temperature of the heated gas introduced and discharged, the temperature of the gas introduced and discharged is preferably much higher than the preheating temperature of the resin sheet. Specifically, the temperature of the compressed gas to be introduced is desirably 250 to 600 ° C. For example, in the heat setting accompanying the shaping of the stretched PET sheet, the hot plate preheating is appropriately about 90 to 100 ° C, but the temperature of the exhaust gas from the outlet is preferably 250 to 500 ° C. Since the heat capacity of the gas is small, the amount of heat is dissipated to the mold through the shaped body, so that the temperature cannot be raised rapidly when the temperature of the exhaust gas is lower than this.
As the high-temperature and high-pressure gas, air, nitrogen, carbon dioxide or the like compressed and heated by another apparatus is used. Note that dry superheated steam containing moisture can also be suitably used.
Although the configuration of this aspect does not have a cooling means by heat medium injection, the surface temperature is automatically reduced to the original low temperature after the mold release by controlling the setting of the back body temperature of the mold sufficiently low. Can be regressed.

<Configuration having both cooling means and heating means>
In the present invention, in addition to the cooling means, a heating gas injection means or infrared irradiation means is provided, and the cooling means is operated after heating the shaped body of the resin sheet fixed to the mold. It can comprise and it can be set as a preferable aspect.
FIG. 2 shows a specific example of this configuration. In this figure, after the temperature increasing heat treatment of the shaped body is performed by the heated compressed gas introduced from the outside together with the pressure forming, the cooling means 40 that has entered the upper part of the forming die is operated and sucked and fixed to the forming die. The process which is cooling the shaped body is shown. 30 is a heating means, 40 is a cooling means, and 20 is a group of molds stored in a storage box. The heating means 30 includes a compressed air box body 31, a heater 32, a distribution space 34, and a gas delivery hole 35. Note that the gas delivery surface 36 formed with 35 is coated with a black body, and is configured to emit infrared rays efficiently while being kept at a high temperature by the heater 32. Although the heated compressed gas is introduced from the outside, the generating device is omitted in this figure.
The cooling means 40 includes a box-shaped main body 44, a compressed gas introduction path 41, an introduction space 42, and a large number of injection holes 43, and the introduced compressed gas is injected from 43. The mold group 20 includes a plurality of molds fixed to a fixed plate 96 and stored in a storage box 97. The surface layer 91 is heated and controlled by a heating heat medium passing through the heat medium passage 95 through a back body 92. Is done. The material of 91 has a large heat permeability in the surface direction and has a function of self-temperature equalization. Reference numeral 112 denotes a main part of the shaped body fixed by suction, and 111 denotes a shaped body edge.

<About molds>
As a basic configuration, the mold has a surface layer made of a material having a thermal permeability (b value) (kJ / m2s1 / 2K) of 0.01 to 15 and heat generating means that spreads over the entire development surface of this layer or the layer. A means for promoting heat transfer in the direction of the development surface is provided.
Both of the two means shown here are means for adjusting the surface temperature of the surface layer to an appropriate and uniform temperature. In the former means, the temperature is equalized to the heat generated on the entire surface. However, both the former and the latter can be provided with a mold provided with another heating means but not. The specific contents of the means will be described later by dividing into each mode.
Examples of the material having a thermal permeation rate (kJ / m2s1 / 2K) of 0.01 to 15 include plastics, ceramics, a small number of selected metal materials, and the like. The value is smaller than that of a commonly used aluminum material, zinc alloy material or the like. For reference, the thermal permeabilities of some materials are shown in Table 1, but are not intended to limit anything described in this table, and those not described can be used arbitrarily.
The above-mentioned heat permeability of the surface layer material is preferably 10 or less, more preferably 5 or less, and even more preferably 3 or less. The thickness of the surface layer is preferably 0.04 mm or more, more preferably 0.06 mm or more, and still 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.
The surface layer may be a single layer or multiple layers as long as the entire layer satisfies the above constraints.
The mold is provided with a fine hole for exhausting during shaping as a conventional method of the thermoforming mold so that vacuum suction can be performed.
The meaning of the heat permeability and the data of various materials will be described later in detail in the column “Supplementary explanation about contents of the present invention” and Table 1. And also in the meaning of the above numerical limitation, it will be explained in the same column.

The aspect 3) of “problem solving means” in the present invention will be described. The mold used in this aspect is provided with a heat generating layer in contact with substantially the entire surface behind the surface layer having the predetermined heat permeability so that the surface layer is heated uniformly and uniformly. The further back of the heat generation layer is not specified. If there is no shortage of functions as a mold such as shape retention or fixing with only the surface layer and the heat generation layer, there is no need for an object behind it, and it can be configured with a back body if necessary. A material as small as possible having a heat permeability of 10 or less is preferred. The heat generation layer may always generate heat or may be intermittent according to the molding cycle.
An example of a specific mold of this embodiment is shown in FIG. The mold main body 60 having a heat generating layer on the back includes a surface layer 61, a heat generating layer 65, and a rear body 62, 63 indicates a vacuum exhaust hole, 64 indicates an exhaust passage, and 66 indicates a lead wire. More specifically, for example, ceramic or the like may be used as a back body, and a sheet heating element may be laid and pasted thereon, and a surface layer may be formed thereon with a material having the predetermined heat permeability. Instead of attaching the sheet heating element, a heating element layer may be formed by plating and etching a nickel-based resistor metal on the back body. Examples of the surface layer material include heat-resistant resins such as epoxy resin, fluorine resin, polyimide, and PEEK. Although not shown, a mold manufactured by exposing a fine thermocouple tip to the molding surface through the back body and the surface layer is convenient for management of the molding process.

The aspect 4) of “problem solving means” in the present invention will be described. The mold used in this embodiment is such that the surface layer having the predetermined heat permeability is directly heated to adjust the surface layer to a uniform temperature. A back layer or back body is formed behind the surface layer to hold and fix the surface layer. The material and shape of the back layer are not specified, but a material as small as possible having a heat permeability of 10 or less is preferable. It should be noted that an object behind the surface layer is not necessarily required if the surface layer alone has sufficient functions as a mold such as shape retention or fixation. The heat generation layer may always generate heat or may be appropriately performed according to the molding cycle.
A specific example of this mold is shown in FIG. The mold 70 having a heat generating surface layer includes a heat generating surface layer 71, a back body 72, a vacuum exhaust hole 73, a 74 exhaust passage, and a lead wire 76. More specifically, for example, a ceramic or the like is used as a back body, and a planar heating element having the predetermined heat permeability is attached as a surface layer thereon, or can be produced by forming it thereon. . Examples of commercially available planar heating elements include an impregnated body and a composite resin body containing graft carbon (Nippon Pioneix Corporation).

The aspect 5) of the “problem solving means” in the present invention will be described. The mold used in this embodiment is provided in close contact with the substantially entire surface behind the predetermined surface layer, and provided with a heat storage and homogenization layer made of a material having a thermal permeability (kJ / m2s1 / 2K) larger than that of the surface layer. Further, a back body made of a material having a heat permeability smaller than that of the heat storage homogenization layer is provided behind it.
In this mold, the means for heating and heating the surface layer may be a structure associated with the mold, but it may not be provided. In that case, it may be irradiated by infrared irradiation or hot gas blowing during the molding process. It can be carried out. Specifically, the surface layer and the lower layer thereof can be adjusted to a stable temperature while the molding with heat treatment of the shaped body using these is controlled and repeated continuously.
In this molding, the heat storage homogenization layer not only corrects the temperature non-uniformity of the surface layer, but also stores the heat during the heat treatment of the previous molding cycle, and the surface layer for the next cycle. Work to supply to. However, it is not always necessary for the heat storage homogenization layer to transmit heat to the back body, and it is preferable that heat transfer to the back body is small when additional auxiliary heating is not performed.
Therefore, the heat permeability of the material for the heat storage and homogenization layer is preferably 10 or more, and more preferably 15 or more. The heat permeability of the back body is preferably 15 or less, and more preferably 10 or less. The thickness of the heat storage homogenizing layer is preferably 10 mm or less, and more preferably 5 mm or less. Further, this thickness is preferably 0.01 mm or more, and more preferably 0.03 mm or more. Outside this range, heat cannot be sufficiently stored to recover the temperature of the surface layer, and temperature unevenness cannot be corrected sufficiently. On the other hand, if the thickness is too thick, it takes time to stabilize the temperature and is difficult.
Note that the shape and thickness of the back body may be any, and it is not necessary to be in close contact with the entire surface of the heat storage homogenization layer.
A specific example of this mold is shown in FIG. The mold 50 is composed of a heat storage and homogenization layer of a surface layer 52 of 51, a vacuum exhaust hole of 53, an exhaust passage of 54, and a back body of 55. For the surface layer 51, the aforementioned material may be used. As the material of 52, a material such as copper (b value 33.9), aluminum (b value 23.3), silicon carbide (b value 16 to 21) may be used. For the back body of 55, a material having a small b value such as engineering plastic or selected ceramics may be used.

The aspect 6) of “problem solving means” in the present invention will be described. The mold used in this embodiment forms a temperature uniformizing layer in contact with the entire development surface on the back surface of the surface layer having the predetermined heat permeability. This temperature uniformizing layer can be formed by using a material having a thermal permeability in at least one direction of the plane larger than that in the thickness direction. As for the further back of the temperature uniformizing layer, the shape can be maintained or fixed only by the surface layer and the temperature uniformizing layer, and the back body may not be provided if there is no shortage of functions as a mold. The back body may be provided with a heating mechanism to indirectly control the heating temperature of the surface layer, or those not provided may be used. When the heating temperature adjustment mechanism is provided on the back body, it is desirable that the heat penetration rate of the back body material is large, and is preferably 10 or more. When the heating temperature adjustment mechanism is not provided, the heat penetration rate should be smaller. Desirably, 10 or less is desirable.
An example of a specific mold of this embodiment is shown in FIG. A mold 80 having a temperature uniformizing layer includes a surface layer 81, a temperature uniforming layer 82, a vacuum exhaust hole 83, an exhaust passage 84, a heating oil passage 85, a back body 86, and a fixed mold 87. It consists of a plate.
A stretched graphite sheet can be given as a typical example that can be used as a temperature uniformizing layer. Further, the surface layer may be formed of a heat-resistant resin having a low thermal permeability such as epoxy resin, fluorine resin, polyimide, PEEK.

The aspect 7) of the “problem solving means” in the present invention will be described. The mold used in this aspect is a material in which the heat permeability in the thickness direction of the surface layer of the mold is the predetermined value, but the heat permeability in at least one plane is larger than that in the thickness direction. It consists of. A back layer or back body is formed behind the surface layer to hold and fix the surface layer. In addition, a heating mechanism may be provided on the back body to indirectly control the heating temperature of the surface layer, or a device not provided with it may be used.
In addition, when providing a heating temperature control mechanism in a back body, it is desirable that the heat penetration rate of a back body material is large, and it is desirable that it is 10 or more, and when a heating temperature control mechanism is not provided, the heat penetration rate is small. It is desirable that the number is 10 or less. The shape of the back body is not specified.
An example of a specific mold of this embodiment is shown in FIG. The mold 90 having a temperature equalizing function includes a surface layer 91 having a uniform function, a back body of 92, a vacuum exhaust hole of 93, an exhaust passage of 94, and a heating oil passage of 95. The material structure may be formed, for example, by forming a surface layer made of the above-mentioned stretched graphite sheet on an aluminum back body.

<About molding method>
A method for molding a thermoplastic resin sheet, comprising the resin sheet preheating step, the shaping step, the heat treatment step of raising the shaped body to a temperature higher than the resin sheet preheating temperature, and the cooling step using the apparatus of the present invention described above. Can be implemented. And these processes can be advanced at high speed and efficient continuous shaping | molding can be performed using a long molding material resin sheet.
As described above, the preheating of the resin sheet can be performed by a direct heating method using a heating plate or an indirect heating method using infrared irradiation, a hot air oven, or the like.
The subsequent shaping step can be performed by a known method of vacuum forming, pressure forming, vacuum pressure forming or fitting die press forming, and the method of vacuum pressure forming can be preferably used.
When molding is performed using a fitting die (core cavity mold), either the core or the cavity only needs to have the configuration of the main mold, and in that case, a heating or cooling medium is sprayed on the other side. This may be convenient.
The high-temperature heat treatment of the shaped body can be performed by using a mold whose temperature is adjusted in 1) or by 2) irradiating the shaped body with infrared rays and / or spraying a heated compressed gas. In addition, the methods 1) and 2) may be performed alone or in combination.
The compressed air shaping may be performed with a normal temperature gas, but it is desirable to perform the compressed air shaping with a heated gas and subsequently perform the heat treatment of the shaped body by heated gas injection. Strictly speaking, when performing pressurized air shaping using infrared irradiation or heated gas injection, the process proceeds with overlapping with the next process, preheating is replenished by these heating means, and shaping proceeds. However, the temperature of the material may be increased.
In the subsequent cooling step, if necessary, the cooling means draws up to the upper part of the mold, cools the shaped body that is vacuum-fixed to the mold by injection of the cooling medium, and finally releases the mold after releasing the vacuum fixation.
Normal thermoforming is performed through the process of preheating, shaping, cooling and releasing the resin sheet. On the other hand, the method of the present invention is characterized in that a heat treatment at a temperature higher than that at the time of shaping of the resin sheet can be performed between shaping and cooling, and this can be carried out continuously at a high speed.
Molding materials suitable for the method of the present invention will be described later in the section “Application Fields and Advantages of the Present Invention”.
(Supplementary explanation about the contents of the present invention)

(1) <About heat penetration rate>
The thermal permeability (b value) (kJ / m2s1 / 2K) used as the specified value of the present invention is a characteristic value of an object in contact with an object in contact with the amount of heat moving through the interface, and is obtained by the following equation: .
b = (λρC) 1/2 (1)
λ; thermal conductivity (Js-1m-1K-1)
ρ; density (kgm-3)
C; Specific heat (Jkg-1K-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.
For reference, Table 1 shows b values of some materials, but this does not specify a material to be used anywhere in the present invention. 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 form is changed to a foam or a porous body, this value changes 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 a material exceeding 10, it is impossible 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.
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. In addition, it is difficult to apply a uniform thick wall, and no mold has been manufactured so far to exert the effects of the present invention.

(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 a shaped body without contact with an infrared thermometer. By repeated molding, the surface temperature of the surface layer draws a constant cycle of rising and falling.
When strictly considering the heat treatment temperature or mold release temperature of the shaping material, it should be noted that there is a temperature gradient in the thickness direction of the shaped body, and that the surface temperature or interface temperature shown here and the shaped body temperature are considerably different. There is a need. Further, temperature measurement from the back side of the shaped body with infrared rays or the like generally does not accurately represent the shaped body temperature.

<Application field of the present invention>
Specific applications requiring high-temperature heat treatment are as follows: (1) It can be particularly suitably used for heat-fixing molding of stretched polyester. Besides, thermoplastic polyester resin, PLA resin, polypropylene, polyamide, PEEK, etc. It can be used for molding involving heat setting of a stretched sheet of crystalline resin. Of these, the stretched polyethylene terephthalate resin sheet can be particularly suitably used for thermoforming with heat setting, and is heated to a preheating temperature of 80 to 100 ° C. and quickly heated to 160 to 190 ° C. suitable for heat setting. And it can take the process of quick cooling and mold release. And, a stable and efficient and continuous molded article having high transparency, high heat resistance and high rigidity can be obtained.
Also, it is applied to materials that have not been particularly stretched, such as (1) molding of normal crystalline PET (CPET), or (3) polypropylene SPPF molding (solid phase high pressure molding). It is possible to propose a novel method for solving (relaxing residual stress strain and improving heat-resistant dimensional stability).

Only a manufacturing example of a molding die, which is an important element of the molding apparatus of the present invention, is described, and other components of the apparatus are described in detail in the text, and thus description thereof is omitted here.
1) Production example of the mold shown in FIG. 3 Machin (Ishihara Pharmaceutical Co., Ltd., b value of 1.7), a machinable ceramic material, is cut to produce a back body, and a nickel alloy thin film is patterned on it. A PEEK resin film (Victrex, thickness 0.2 mm, b value) pre-heated as a surface layer was spread with a sheet-like heating element sandwiched between PEEK resin thin films and spotted with an adhesive. 0.35) was pressure-air shaped, fixed in vacuum, and baked at 380 ° C. together with the main body. By this baking, adhesion between the respective layers was achieved, and crystallization of the PEEK resin progressed, so that the heat resistance became high. The molded product was a 75 × 150 mm square and 30 mm deep tray-shaped product, and the outer dimension of the mold was a 84 × 168 mm square and a height of 55 mm.
The thickness of the surface layer was about 0.2 mm. The b-value of the PEEK resin in the surface layer seems to have increased somewhat due to crystallization, but it does not exceed the most preferred range of the present invention.
This type of temperature rise test was conducted, and it was found that the variation was within several degrees when the surface temperature was 180 ° C., which was very preferable.
Although not shown in the drawings, the thermocouple tip was made to be exposed on the molding surface through the back body and the surface layer.
2) Manufacturing example of the mold shown in FIG. 4 A back body (back layer) is manufactured using the same material as 1) above, and a tape-like graft carbon-impregnated glass cloth (manufactured by Nippon Pioneix, Inc., generates heat when energized from both ends) Material to be produced) Attached side by side, further coated with PEEK powder suspension (manufactured by Okitsumo), soaked and dried, and fired at 380 ° C. for the whole. Although the value of the thermal permeability of the formed surface layer is not accurately measured, it is estimated to be about 0.5 to 2.0 in view of the material used, and does not exceed the most preferable range of the present invention. .
The dimensional shape of the molded product and the mold was the same as 1) above.
This type of temperature rise test was conducted, and it was found that the variation was within several degrees when the surface temperature was 180 ° C., which was very preferable.
3) Production example of the mold shown in FIG. 5 A polyimide resin block material (DuPont Bespel, b value 0.36) is cut to produce a back body, and copper plating (thickness 0.2 mm) is applied thereon. Then, a temperature uniformizing layer was formed, and a heat-resistant epoxy resin coating (b value 0.7, thickness 0.25 mm) was further formed thereon to form a surface layer. The coating unevenness was corrected by cutting by machining. Further, a delicate temperature sensor tip was provided in contact with the temperature uniformizing layer and the molding surface. The dimensional shape of the molded product and the mold was the same as 1) above.
Since this molding die itself is not equipped with a heating means, a molding test was conducted with the apparatus of the present invention capable of jetting heated gas with external line irradiation. First, a molding test with actual heat treatment is performed by heating the temperature uniformizing layer to a certain steady temperature by repeating heating by air injection and cooling by room temperature air injection without molding material at intervals of the molding cycle. went. Even when the molding test was repeated continuously, uneven portions such as whitening, cracks, and partial transparency reduction did not occur at the edge of the molded product.
In this molding result, the heat storage homogenization layer not only corrects the temperature non-uniformity of the surface layer, but also stores heat from the heat treatment of the previous molding cycle and supplies it to the surface layer in the next cycle. Indicates that you have been able to continue.
4) Manufacturing example of the mold shown in FIG. 6 Aluminum material A5052 (b value 17.4) is cut to produce a back body, and a stretched graphite sheet (manufactured by Otsuka Electric Co., Ltd., SS400 thickness 0.13 mm) is heat resistant. Laminate with an adhesive to form a layer with a thickness of about 0.3 mm and a self-homogenizing function for temperature, and then apply PEEK sheet on the same as the example in 1) above. Shaped and fired for the same purpose to form a surface layer. This mold was fixed to a fixed plate with a built-in cartridge heater. The surface layer has a thickness of about 0.16 mm and the same b value as in the above 1), and can be subjected to temperature equalization from the back layer.
The dimensional shape of the molded product and the mold was the same as 1) above.
The temperature of the fixing plate was raised and this type of temperature rise test was conducted. When the surface temperature was set to 180 ° C., the variation was within several degrees and was found to be very favorable.
5) Production example of mold shown in FIG. 7 The same aluminum material A5052 as in 3) above is cut to produce a back body, and the same stretched graphite sheet is laminated thereon using a heat-resistant adhesive, and about 0. A layer having a thickness of 3 mm and having a temperature self-homogenizing function was formed, and this layer was used as a surface layer as it was. Further, a heat medium passage was provided inside the back body.
The dimensional shape of the molded product and the mold was the same as 1) above.
The b value of the used graphite sheet is 3.5 in the thickness direction and 29.1 in the horizontal direction, which forms a preferable surface layer of the present invention. This mold was mounted on a heated fixed plate and subjected to a temperature rise test. When the surface temperature was 180 ° C., the variation was within several degrees and was found to be very preferable.

A stretched PET sheet was thermoformed by a method in which a heat treatment was performed by using a molding die having a surface layer and a back heating layer in the structure shown in FIG.
1) Molding material: 2.5 times uniaxially stretched seam of homopolyethylene terephthalate resin (but not heat-set), 0.23 mm thick non-heat-fixed product was used.
2) Molding equipment
Molding machine: A single-wafer vacuum / pneumatic molding machine, having a pneumatic capacity of 10 ton and an infrared preheating oven.
Compressed air means: Uses a known compressed air box for normal temperature compressed air forming. The compressed air box is made of aluminum and has a compressed air surface of 170 × 170 mm.
Cooling means: a system shown by 40 in FIG. 1 was used.
Molding die: having the structure shown in FIG. 3 and two pieces shown in 1) of Example 1 were arranged on a fixing plate without a heating mechanism and fixed to the fixing plate, and housed in a storage box having an inner size of 170 × 170 mm. The upper surface of the mold was made 3 mm lower than the side wall of the storage box.
Temperature measurement: The tip of the thin wire thermocouple was exposed on the molding surface, and the molding surface temperature and the shape body interface temperature could be measured. Similarly, a thin wire thermocouple is inserted into the compressed air box space and arranged so that the compressed air temperature can be measured.
3) Molding method and molding conditions;
Preheat temperature of resin sheet; Preheat to about 95 ° C in preheat oven
Preheating temperature of surface layer surface: 185 ° C
Pressure box perforated plate surface temperature: about 35 ° C
Vacuum pressure forming; Uses normal temperature compressed gas with a pressure of 0.4 MPa for 5 seconds.
The compressed air space is a closed space, and substantially no injection after shaping is performed.
Heat treatment temperature (interface temperature); about 177 ° C
At the time of shaping, the surface temperature instantaneously decreased by about 10 ° C. and recovered quickly to this temperature.
Cooling means operating time: 3 seconds
At the time of mold release, the surface (interface) temperature dropped to 120 ° C., and then returned to the original set temperature within a few seconds. However, it cooled with the heating layer energized.
4) Molding result;
The obtained molded product was a good shape, transparent and uniform. In a 2-minute immersion test of silicon oil having a heat resistance of 120 ° C., there was no noticeable deformation and the heat resistance was excellent. It was found that the used mold can easily set the surface temperature, can be easily blown-cooled, can recover the surface temperature quickly, and can be molded at high speed.
In addition, it was found that the sheet can be stably formed even by a repeated test using a short sheet.

The same stretched PET sheet was thermoformed by a method of performing pressure forming by heat medium injection and heat treatment using the apparatus 30 shown in FIG. However, the same mold as in Example 2 was used. Further, a cooling means such as 40 in FIG. 1 was used.
1) Molding apparatus Molding machine: the same as in Example 2 Pneumatic shaping and heating means: A heated / pneumatic box of the type 30 shown in FIG. 2 was used. In addition, heated compressed gas was introduced from the outside, and the jetting surface was coated with a black body and kept at a high temperature by an internal heater so that infrared irradiation could be performed efficiently. In addition, an exhaust hole was provided in the lower part of the side wall of the compressed air box so that the air was arbitrarily exhausted from the compressed air space. The compressed air box was made of aluminum and the size of the compressed air surface was 170 × 170 mm.
2) Molding method and molding conditions
Preheating of resin sheet: Preheated to about 95 ° C. as in Example 2.
Pressure box perforated plate set temperature: 350 ° C
Mold setting surface temperature; set to 175 ° C by controlling heating element layer
Maximum temperature reached at the mold / shaped object interface; 180 ° C
Introducing air from outside into the compressed air box; 350 ° C, source pressure 0.4 MPa
Compressed air vacuum compressed air shaping; 4 seconds, compressed air pressure 0.2 MPa,
The compressed air space was not completely closed, and shaping and temperature raising of the shaped body were performed while exhausting hot compressed air.
Air blow time of cooling means; 6 seconds
At the time of mold release, the surface (interface) temperature dropped to 130 ° C., and then recovered to the original set temperature within a few seconds. The cooling was performed while the heating layer was energized.
3) Molding result;
The obtained molded product was a good shape, transparent and uniform. The heat resistance was the same test as in Example 2, and was excellent without deformation and noticeable shrinkage at 150 ° C. In addition, it was found that even in a continuous repeated test using a short sheet, a uniform molded product can be molded stably and at high speed without the occurrence of cracks, whitening, or a texture-reduced portion at the edge of the molded product.

Except for changing the mold, thermoforming was performed using the same molding apparatus and the same molding material as in Example 2. The mold used was 2) of Example 1, that is, a mold in which two molds whose surface layer itself has a heat generation function was fixed to the same fixing plate as in Example 2 and similarly stored in a storage box.
1) Molding method and molding conditions
Preheating of resin sheet; approx. 95 ° C
Pressure box perforated plate surface temperature: about 35 ° C
Mold setting surface temperature: 180 ° C
Maximum temperature reached at the mold / shaped object interface; 180 ° C
Air introduced from the outside to the compressed air box; about 25 ° C., 0.4 MPa
Pressure vacuum Vacuum pressure shaping; 4 seconds, 0.2 MPa Simultaneous vacuum operation
Air blow time of cooling means: 5 seconds (surface heating energization stops during cooling)
2) Molding result A molded product with a transparent and highly uniform appearance was obtained. It was found that high speed molding was possible. In addition, it was found that even in a continuous repeated test using a short sheet, a uniform molded product can be molded stably and at high speed without the occurrence of cracks, whitening, or a texture-reduced portion at the edge of the molded product.

Except having changed the shaping | molding die, it thermoformed using the same molding material as the Example 3 and the same molding material. The mold used was 3) of Example 1, that is, a mold in which two molds having a temperature equalizing function behind the surface layer were fixed to a fixed plate containing a heater and housed in a storage box.
1) Molding method and molding conditions
Preheating of resin sheet; approx. 95 ° C
Pressure box perforated plate surface temperature: 400 ° C
Mold setting surface temperature; 160 ° C
Maximum temperature reached at the mold / shaped object interface; 182 ° C
Air introduced from outside into the compressed air box; 400 ° C 0.4 MPa
Compressed air vacuum compressed air shaping; 4 seconds 0.2 MPa
Air blow time of cooling means; 4 seconds
2) Molding result A molded product with a transparent and highly uniform appearance was obtained. It was found that high speed molding was possible. In addition, it was found that even in a continuous repeated test using a short sheet, a uniform molded product can be molded stably and at high speed without the occurrence of cracks, whitening, or a texture-reduced portion at the edge of the molded product.

Except having changed the shaping | molding die, it thermoformed using the same molding material as the Example 3 and the same molding material. The mold is the same as that in Example 1 4), that is, two molds whose surface layer itself has a temperature equalizing function are fixed to a fixing plate not having a heating mechanism similar to that of Example 2 to form a storage box. The housed one was used.
1) Molding method and molding conditions
Preheating of resin sheet; approx. 95 ° C
Pressure box perforated plate surface temperature: 400 ° C
Mold setting surface temperature: 175 (heated by oil passing through heat medium passage)
(It was confirmed that any part of the surface could be set with almost no temperature difference.)
Maximum temperature reached at the mold / shaped object interface; 183
Air introduced from outside into the compressed air box; 400 ° C 0.4 MPa
Compressed air vacuum compressed air shaping; 4 seconds 0.2 MPa
Air blow time of cooling means: 6 seconds 2) Molding result A molded product having a transparent and highly uniform appearance was obtained. It was found that high speed molding was possible. In addition, it was found that even in a continuous repeated test using a short sheet, a uniform molded product can be molded stably and at high speed without the occurrence of cracks, whitening, or a texture-reduced portion at the edge of the molded product.
(Comparative Example 1)

In the same apparatus as in Example 2, a known and commonly used mold only was mounted, and the following test was performed using the same molding material sheet as in Example 2. As the mold, a generally used aluminum material A5052 made of a simple structure was fixed to a fixed plate equipped with a cartridge heater. The b value of A5052 is 17.4, which is not suitable for forming the surface layer of the mold used in the present invention.
1) Molding method and molding conditions Preheating of the resin sheet; Preheating to about 95 ° C. in a preheating oven; Vacuum pressure forming; 0.4 MPa, 3 seconds. In addition, the compressed air space is closed and air blow after shaping is not performed.
Mold set surface temperature: 185 ° C (by adjusting fixed plate temperature)
Heat treatment temperature at the mold / shaped object interface; 175 ° C
At the instant of shaping, the mold surface temperature (interface temperature) decreased by about 10 ° C., and the heat treatment temperature became about 175 ° C.
Cooling means operating time: 20 seconds
The mold surface temperature (interface temperature) at the time of mold release was about 155 ° C.
2) Test results;
Although the cooling blow time was set to 20 seconds, the mold could be released while maintaining a temporary shape, but it was not sufficiently precise.
Furthermore, it has been found that this method requires at least about 10 seconds to return to the preheating temperature of the surface temperature after the mold release along with a long cooling time, and is not suitable for high-speed continuous molding.
(Comparative Example 2)

In the same molding apparatus as in Example 3, the same mold as in Comparative Example 1 was used, and the following test was performed using the same molding material sheet as in Example 1. The mold used was an aluminum single piece fixed to a fixed plate.
1) Molding method and molding conditions Preheating of resin sheet; Preheating to about 95 ° C in a preheating oven.
Mold surface temperature: Tested by preheating to 155 ° C. by adjusting the fixing plate temperature.
Air introduced into the heating plate; temperature 400 ° C., source pressure 0.4 MPa
Vacuum pressure forming; 0.2 MPa, 6 seconds (However, vacuuming on the mold side is also activated simultaneously)
The compressed air space was not completely closed, and the shape and the temperature of the shaped body were raised while exhausting some of the hot compressed air.
Maximum point temperature reached at the mold / shaped object interface; the mold surface (interface) temperature did not decrease, but increased by about 10 ° C. to about 170 ° C.
Cooling means actuated; air blower actuated for 20 seconds to release mold,
2) Test results;
The molded product could be released from the mold while maintaining a temporary shape with a cooling blow for a long time of 20 seconds, but it was not sufficiently precise.
It should be noted that the return of the surface temperature to the set preheating temperature after release requires at least about 10 seconds, and it was found that this apparatus configuration is not suitable for high-speed continuous molding.
(Comparative Example 3)

With the same apparatus as in Example 3, only the mold was changed, the same molding material was used, and a molding test was performed. As the molding die, a known simple structure manufactured by cutting a urethane resin foam (manufactured by Sanyo Chemical Co., Ltd., Sun Module 33) was used by fixing it to an aluminum fixing plate incorporating a heater. The b value of the mold material is 0.7, which satisfies the restriction as a material for forming the surface of the mold used in the present invention.
1) Molding method and molding conditions
Preheat resin sheet; Preheat to about 95 ° C in preheat oven
Mold surface preheating temperature: 75 ° C. However, the temperature is not uniform at the same time as the heating by the fixing plate.
It was preheated to this temperature with a 300 ° C. hot air blow.
Air temperature introduced to the heating plate: 400 ° C
Vacuum pressure forming; 0.2 MPa, 8 seconds (the vacuum on the mold side is also activated at the same time), the pressure space is not completely closed, and the shape and the temperature of the shaped body are raised while high-temperature pressure air is exhausted It was broken.
There was no drop in the mold surface (interface) temperature, and the temperature rose to 183 ° C.
Cooling means actuated; air blower actuated for 5 seconds to release mold,
The mold surface (interface) temperature at the time of mold release was 113 ° C.
2) Test results;
In the method of heating the back body of the mold, the temperature difference depending on the site reached several tens of degrees C., and the required surface temperature could not be reached. The molding test was not practical, but was pre-heated with hot air. The molded product obtained initially was good and heat resistant. In this apparatus configuration, cooling is very easy, but severe heating conditions must be set for a significant temperature increase. Therefore, when the test was repeatedly performed, the temperature unevenness due to the portion of the mold surface layer gradually increased, and finally, the edge portion and the like were cracked due to overheating, which hindered the molding.

<Effectiveness using this molding device>
Thermoforming using the mold of the mechanism of the present invention has the following effects.
(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 thermoformed product having excellent mechanical strength such as heat resistance, transparency, and rigidity can be efficiently obtained by thermoforming a crystalline resin stretched sheet, for example, a stretched PET sheet material as described above. Can be produced. Moreover, the utility which can save the material of the existing molded product using rigidity is great.
(3) By reflecting the measurement result of the fluctuating temperature and adjusting or controlling the heating condition and the cooling condition, the optimum product and the shortest cycle can be easily realized and stable control can be performed. Moreover, it can shift to stable production conditions in a short time.
(4) Uniform molded products and molded products with few variations can be efficiently produced by molding many pieces.
(5) A wide variety of molds or molding materials can be selected and used for molding.
(6) Production can be performed while saving energy consumption.
(7) The apparatus of the present invention can be applied to a wide range of materials other than a stretched sheet of crystalline resin, such as an unstretched material, such as a CPET material.

20 Mold assembly structure
30 Heating means (heating and pressure box)
31 Pneumatic box body (for heated gas)
32 Heating heater 33 Heated compressed gas introduction path
34 Branch space
35 Gas delivery hole
36 Gas delivery surface (infrared radiation surface)
40 Cooling means (each method)
41 Compressed gas introduction path
42 Introduction space 43 Injection hole or injection nozzle
44 Conduit or box 45 Fixed frame
46 Ventilation space (gap between pipes)
50 Mold (Uniform layer on the back)
51 Surface layer
52 Heat storage uniform layer 53 Vacuum exhaust hole
54 Exhaust passage 55 Back body
60 Mold (heat generation layer behind)
61 Surface layer 62 Back body 63 Vacuum exhaust hole 64 Exhaust passage 65 Heat generation layer 66 Lead wire
70 Mold (Surface layer generates heat)
71 Heat generation surface layer
72 Back body 73 Vacuum exhaust hole
74 Exhaust passage 76 Lead wire
80 Mold (Uniform layer on the back)
81 Surface layer
82 Temperature uniformity layer 83 Vacuum exhaust hole
84 Exhaust passage 85 Heat transfer oil passage
86 Back layer (back body)
87 Mold fixing plate 90 Mold (surface layer has a uniform function)
91 Self-temperature uniformized surface layer
92 Back layer (back body)
93 Vacuum exhaust hole
94 Exhaust passage 95 Heating oil passage
96 Fixed plate 97 Mold storage box
110 Shaped body of thermoplastic resin sheet (whole)
A Cooling medium (compressed gas, etc.) HA Heated compressed air

(1) In a thermoforming apparatus configured to perform at least one of heating and cooling of a shaped body of a resin sheet fixed to a mold by means of spraying a heat medium or irradiating infrared rays, And a surface layer made of a material having a thermal permeation rate (b value) (kJ / m ² s ^1/2 K) of 0.01 to 15, and a heating means that spreads over the entire development surface of this layer or the development of this layer The present invention provides a thermoplastic resin sheet thermoforming apparatus using a structure having means for promoting heat transfer in the surface direction.
In the present invention, the “surface layer” refers to a layer including the molding surface of the mold. “Shaping” and “shaping step” indicate a part of the operation during molding, and “shaped body” means a molded product held in a mold.
Note that 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.
The heat permeability of the surface layer material is preferably 10 or less, more preferably 5 or less, and even more preferably 3 or less. The thickness of the surface layer is preferably 0.04 mm or more.
The surface layer may be a single layer or multiple layers as long as the entire layer satisfies the above constraints.

(5) A heat storage uniform layer made of a material having a heat permeability (kJ / m ² s ^1/2 K) larger than that of the surface layer is in close contact with substantially the entire surface behind the surface layer. The structure according to any one of (1) to (4) above, further comprising a back body made of a material having a lower thermal permeability than that of the heat storage homogenization layer. A molding apparatus is provided. The heat permeability of the material for the heat storage homogenization layer is preferably 10 or more, and more preferably 15 or more. That of the back body is preferably 15 or less, more preferably 10 or less. The thickness of the heat storage homogenizing layer is preferably 10 mm or less, and more preferably 5 mm or less. Further, this thickness is preferably 0.01 mm or more, and more preferably 0.03 mm or more.

<About molds>
As a basic configuration, the mold has a surface layer made of a material having a thermal permeability (b value) (kJ / m ² s ^1/2 K) of 0.01 to 15 and heat generating means that spreads over the entire development surface of this layer. Or it shall have a means to accelerate | stimulate the heat transfer of the expansion | deployment surface direction of this layer.
Both of the two means shown here are means for adjusting the surface temperature of the surface layer to an appropriate and uniform temperature. In the former means, the temperature is equalized to the heat generated on the entire surface. However, both the former and the latter can be provided with a mold provided with another heating means but not. The specific contents of the means will be described later by dividing into each mode.
Examples of the material having a thermal permeability (kJ / m ² s ^1/2 K) of 0.01 to 15 include plastics, ceramics, a small number of selected metal materials, and the like. It has a smaller value than aluminum materials, zinc alloy materials, etc. that are usually used as molds. For reference, the thermal permeabilities of some materials are shown in Table 1, but are not intended to limit anything described in this table, and those not described can be used arbitrarily.
The above-mentioned heat permeability of the surface layer material is preferably 10 or less, more preferably 5 or less, and even more preferably 3 or less. The thickness of the surface layer is preferably 0.04 mm or more, more preferably 0.06 mm or more, and still 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.
The surface layer may be a single layer or multiple layers as long as the entire layer satisfies the above constraints.
The mold is provided with a fine hole for exhausting during shaping as a conventional method of the thermoforming mold so that vacuum suction can be performed.
The meaning of the heat permeability and the data of various materials will be described later in detail in the column “Supplementary explanation about contents of the present invention” and Table 1. And also in the meaning of the above numerical limitation, it will be explained in the same column.

The aspect 5) of the “problem solving means” in the present invention will be described. The mold used in this embodiment is in close contact with substantially the entire surface behind the predetermined surface layer, and has a uniform heat storage made of a material having a thermal permeability (kJ / m ² s ^1/2 K) larger than that of the surface layer. And a back body made of a material having a thermal permeability smaller than that of the heat storage homogenization layer is provided behind it.
In this mold, the means for heating and heating the surface layer may be a structure associated with the mold, but it may not be provided. In that case, it may be irradiated by infrared irradiation or hot gas blowing during the molding process. It can be carried out. Specifically, the surface layer and the lower layer thereof can be adjusted to a stable temperature while the molding with heat treatment of the shaped body using these is controlled and repeated continuously.
In this molding, the heat storage homogenization layer not only corrects the temperature non-uniformity of the surface layer, but also stores the heat during the heat treatment of the previous molding cycle, and the surface layer for the next cycle. Work to supply to. However, it is not always necessary for the heat storage homogenization layer to transmit heat to the back body, and it is preferable that heat transfer to the back body is small when additional auxiliary heating is not performed.
Therefore, the heat permeability of the material for the heat storage and homogenization layer is preferably 10 or more, and more preferably 15 or more. The heat permeability of the back body is preferably 15 or less, and more preferably 10 or less. The thickness of the heat storage homogenizing layer is preferably 10 mm or less, and more preferably 5 mm or less. Further, this thickness is preferably 0.01 mm or more, and more preferably 0.03 mm or more. Outside this range, heat cannot be sufficiently stored to recover the temperature of the surface layer, and temperature unevenness cannot be corrected sufficiently. On the other hand, if the thickness is too thick, it takes time to stabilize the temperature and is difficult.
Note that the shape and thickness of the back body may be any, and it is not necessary to be in close contact with the entire surface of the heat storage homogenization layer.
A specific example of this mold is shown in FIG. The mold 50 is composed of a heat storage and homogenization layer of a surface layer 52 of 51, a vacuum exhaust hole of 53, an exhaust passage of 54, and a back body of 55. For the surface layer 51, the aforementioned material may be used. As the material of 52, a material such as copper (b value 33.9), aluminum (b value 23.3), silicon carbide (b value 16 to 21) may be used. For the back body of 55, a material having a small b value such as engineering plastic or selected ceramics may be used.

(1) <About heat penetration rate>
The heat permeability (b value) (kJ / m ² s ^1/2 K) 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. It is calculated by the formula.
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.
For reference, Table 1 shows b values of some materials, but this does not specify a material to be used anywhere in the present invention. 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 form is changed to a foam or a porous body, this value changes greatly.

Claims (8)

In a thermoforming apparatus configured to perform at least one of heating and cooling of a shaped body of a resin sheet fixed to a mold by means of spraying a heat medium or irradiating infrared rays, It has a surface layer made of a material having a permeation rate (kJ / m2s1 / 2K) of 0.01 to 15, and a heating means that spreads over the entire development surface of this layer or a means for promoting heat transfer in the development surface direction of this layer. An apparatus for forming a thermoplastic resin sheet using a structure. The resin sheet shaped body fixed to the mold is heated by means of jetting heated gas or irradiating infrared rays, and then the cooling heat medium is cooled by means of jetting. The molding apparatus according to claim 1, characterized in that: 3. The molding apparatus according to claim 1 or 2, wherein the molding die is configured so as to steadily heat the surface layer by heat generating means in close contact with the substantially entire surface behind the surface layer. . 4. The molding apparatus according to claim 1, wherein the molding die is configured such that the surface layer itself generates heat. The mold is in close contact with substantially the entire surface behind the surface layer, and a heat storage and homogenization layer made of a material having a thermal permeability (kJ / m2s1 / 2K) larger than that of the surface is provided, and a heat The molding apparatus according to any one of claims 1 to 4, wherein a back body is provided by a material having a permeability smaller than that of the heat storage and homogenization layer. The mold is in close contact with the substantially entire surface behind the surface layer, and a temperature uniformizing layer is formed of a material having a thermal permeability of at least one direction of the development surface larger than that in the thickness direction. The molding apparatus according to claim 1, wherein the molding apparatus is characterized. The mold has a surface layer formed of a material having a heat permeability in the thickness direction having the predetermined value and having a heat permeability in at least one plane larger than that in the thickness direction. The molding apparatus according to claim 1, wherein: A resin sheet molding method using the resin sheet molding apparatus according to any one of claims 1 to 7, wherein the resin sheet preheating step, the shaping step, and the shaped body are heated to a temperature higher than the resin sheet preheating temperature. A method for forming a thermoplastic resin sheet, which includes performing a heat treatment step for raising the temperature and a cooling step.

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