JP2001071334A - Method and apparatus for heating resin sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve heating efficiency and to heat a resin sheet well by setting a minute temperature distribution in the sheet. SOLUTION: In an apparatus for heating a resin sheet, a heater using a middle-near infrared region of 1.5-2.5 μm maximum wavelength of the radiation energy of the heater is mounted on a heating part. The heater 1 is composed of a metal filament 2 to be a heating body, a glass tube 3, reflection plates 4 having mirror surface properties, and a heater fixing terminals 5. A heater unit in which radiatin energy from the filament 2 is reflected by a metal reflectin membrane 3A on the back of the glass tube 3 and the reflection plate 4 or only by the plate 4, and radiation enrgy from upper and lower heater is reflected mutually by the upper and lower reflection plates 4 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin sheet heating apparatus and a resin sheet heating method using the same.

[0002]

2. Description of the Related Art Conventionally, techniques in such a field include:
There were the following.

FIG. 19 is a diagram showing an outline of such a continuous sheet thermoforming machine.

In FIG. 1, reference numeral 101 denotes a roll-shaped resin sheet held by a sheet support, and reference numeral 102 denotes a sheet heating zone provided downstream of the sheet support to heat the resin sheet 101 from above and below. Reference numeral 103 denotes a sheet forming zone provided on the downstream side of the sheet heating zone 102, and a mold (upper and lower molds) 104 is provided so as to sandwich the resin sheet 101 from above and below. Reference numeral 105 denotes a table provided between the upper and lower molds 104, and reference numeral 107 denotes a sheet supply unit.

Conventionally, a heater mainly used for heating a resin sheet has a maximum temperature of about 300 ° C. to 500 ° C. in which a filament heating element is embedded in ceramic, and a wavelength of radiant energy of 4.0 μm to 7.0 μm. This is a far infrared heater.

[0008] As shown in FIG. 19, this is installed above and below a heating zone 102 of a continuous sheet thermoforming machine, and the sheet 101 is heated from above and below the sheet 101 by indirect heating. Resin sheet 101 heated in heating zone 102
When a certain forming temperature or a certain heating time is reached, the sheet is sent to a sheet forming zone 103 located next to the heating zone 102 and is formed.

Here, when the resin sheet 101 is a foamed resin sheet, the heating zone 10 is not used in the conventional far-infrared heater.
2 is taken in two or three zones, the sheet is heated for two or three shots, and then the next molding zone 1
It is necessary to send the sheet to 03 and form it. It had to be heated for a long time because of its low heating capacity.

Therefore, the heating time is required to be twice or three times as long as the molding time (molding cycle), and the heating takes a long time. On the other hand, if the heating zone 102 is lengthened to shorten the molding cycle, the length of the apparatus becomes longer. Conversely, if the length of the apparatus is shortened, the heating time becomes longer.

In general, in the case of a transparent non-foamed sheet such as a crystalline polypropylene sheet (PP sheet), a polyethylene terephthalate sheet (PET sheet) or a polybutylene terephthalate sheet (PBT sheet),
Thin material (0.2
In the case of (approximately 0.5 mm), heating with two shots is usually sufficient in time in the sheet heating zone 102 shown in FIG. 19, but the transparency of the heated sheet is greater than that of the original sheet before heating. The problem that the property is inferior occurs.

Here, the crystalline resin is characterized in that a polymer is crystallized and a part of a long chain-like polymer is regularly arranged in a certain direction, so that heat resistance, mechanical strength and transparency change. Resin, especially when crystallization progresses,
It has the property that the transparency of the resin deteriorates.

As an example of using a bar-type heater other than the conventional ceramic type far-infrared heater as the heater, Japanese Utility Model Publication No. 6-27388 discloses a heating device using a sheathed heater which is a high-temperature type. I have.
This is a heating device characterized by incorporating a swinging mechanism for the heater in parallel with the sheet feeding direction. However, since the heater is a long bar-shaped heater, it is impossible to control the temperature in the heater longitudinal direction. Since the radiation cannot be made uniform, it was necessary to incorporate a swing mechanism.

Therefore, with such a heating apparatus, it is impossible to control the heating temperature of a partial sheet, which is the most important function in sheet forming.

A method and an apparatus for heating a resin sheet using a heater having a short wavelength or a medium wavelength having a maximum radiant energy of 1 to 3 μm as a heater have been proposed (see Japanese Patent Application Laid-Open No. 7-276490). ).

However, since the heater used in this apparatus is integrally formed in the width direction of the resin sheet, there is a problem that the heating temperature cannot be controlled in the width direction of the resin sheet.

[0015]

As described above, in the conventional heating method, when a foamed resin sheet in which a thermoplastic resin is impregnated with a foaming agent is heated, it takes a long time to heat the foamed resin sheet. In the case of the heating, the transparency is inferior due to the heating, so that there is a problem in terms of performance and quality.

For example, in the case of a foamed resin sheet in a state in which a thermoplastic resin is impregnated with a foaming agent and is primarily foamed, a conventional ceramic type is used when reheating in a heating section of a thermoforming machine to form a secondary foam. Heating with a far-infrared heater based on
There has been a problem that the temperature rises only on the surface of the material and the temperature inside the material is heated only by the heat conduction in the thickness direction, so that the temperature rise takes a long time.

As a result, it is necessary to set the heater temperature to a low temperature in advance, and to slowly heat for a long time at a low temperature to reduce the temperature unevenness in the thickness direction. Had become.

That is, in the case of the foamed sheet, unlike the case of the non-foamed sheet, the thickness is generally large, and the thickness is further increased due to the secondary foaming caused by heating, and the heat conduction in the thickness direction is worse. Will be. Therefore, the temperature inside the material did not rise easily, and the heating efficiency was lower than in the case of the non-foamed sheet.

In addition, the crystalline resin is inferior in transparency to the original sheet due to heating. For example, in the case of use as a food container, there is a problem that the contents do not look clear and the commercial value is reduced. .

In addition, there is also a problem that uneven heating occurs between the center and the end of the resin sheet, whereby good molding cannot be performed, and the commercial value is reduced.

Therefore, the present invention eliminates the above problems,
It is an object of the present invention to provide a heating apparatus for a resin sheet and a method for heating a resin sheet using the same, which can improve the heating efficiency and perform good and uniform heating of the resin sheet.

[0022]

According to the present invention, in order to achieve the above object, [1] In a heating apparatus for a resin sheet, the heating section has a maximum radiant energy wavelength of the heater of 1.5 μm to 2.5 μm.
A plurality of heater units each including a heater having a middle / near infrared region are arranged.

[2] The apparatus for heating a resin sheet according to the above [1], wherein the heater comprises a metal filament serving as a heating element, and a glass tube containing the metal filament.
The apparatus has a reflector unit provided on the non-heating side of the glass tube and having a mirror surface, and a heater unit including a heater fixing terminal supporting both ends of the glass tube.

[3] In the resin sheet heating apparatus according to [2], the heater unit mounting base for mounting the heater unit is provided with a groove adapted to the shape of the head of the heater unit mounting bolt. This prevents the unit mounting bolts from rotating together.

[4] In the apparatus for heating a resin sheet according to the above [1] or [2], the size of the heater unit is planar, 1: 1, 1: 2, 1: 3, 2: 2, or 2 : 3, and these heater sizes are combined to form a heating zone.

[5] The apparatus for heating a resin sheet according to the above [1] or [2], wherein the temperature of the heater of the heater unit can be individually set and changed.

[6] In the apparatus for heating a resin sheet according to the above [1] or [2], the upper and lower heaters are provided in the heating section, and the lower heater unit is provided with respect to the upper heater unit. The arrangement is changed or the positions of the heaters are shifted and arranged.

[7] In the apparatus for heating a resin sheet according to the above [6], the heaters of the heater unit are arranged so as to be shifted by a half pitch between the upper heater and the lower heater.

[8] The apparatus for heating a resin sheet according to the above [6], wherein the heaters of the heater unit are arranged in a direction orthogonal to the upper heater and the lower heater.

[0030]

[9] The foamed polystyrene sheet (PSP) is heated to 180 ° C. to 220 ° C. in the heating device by using the resin sheet heating device according to any one of the above [1] to [8].
155 ° C while maintaining the temperature range
By performing secondary foaming and heating while maintaining the temperature range from 175 ° C. to 175 ° C., the foam thickness is increased while maintaining a favorable surface state, and the foaming ratio inside the material is increased.

[10] Any one of the above [1] to [8]
By using the heating device for the resin sheet described above, by heating the crystalline resin in a state where the temperature in the heating device is maintained in the temperature range of 180 ° C. to 220 ° C., the transparency after heating is excellent in transparency close to the original sheet. It is something that you get.

[11] Any one of the above [1] to [8]
The polypropylene sheet (PP sheet), which is a crystalline resin, was maintained at a temperature in the range of 180 ° C. to 220 ° C. in the heating apparatus using the resin sheet heating device described above, and the sheet surface temperature was 165 ° C. to 190 ° C. By heating while maintaining the temperature in the temperature range, the transparency after heating is to obtain excellent transparency close to that of the raw sheet.

[12] Any one of the above [1] to [8]
The amorphous polyethylene terephthalate sheet (A-PET sheet) which is a crystalline resin but is in a non-crystalline state was maintained in a temperature range of 180 ° C. to 220 ° C. in the heating device using the resin sheet heating device described in the above. By heating the sheet while maintaining the sheet surface temperature in a temperature range of 125 ° C. to 150 ° C. in the state, excellent transparency after heating is obtained, which is close to that of the original sheet.

[13] Any one of the above [1] to [8]
Polybutylene terephthalate sheet (PBT sheet) which is a crystalline resin using the resin sheet heating device described in the above.
Is heated while maintaining the sheet surface temperature in the temperature range of 160 ° C. to 185 ° C. in a state where the temperature in the heating device is maintained in the temperature range of 180 ° C. to 220 ° C., so that the transparency after heating is close to that of the original sheet. This is to obtain transparency.

[14] Any one of the above [1] to [8]
The sheet surface temperature of the polypropylene sheet having a foaming ratio of 1.3 to 5 which is a crystalline resin is maintained in a temperature range of 180 ° C. to 220 ° C. in the heating device by using the resin sheet heating device described in the above section. The secondary foaming and heating are performed while maintaining the temperature range of 170 ° C to 185 ° C.

[0036]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a structural view of a heater unit showing an embodiment of the present invention. FIG. 1 (a) is a front view of the heater unit, and FIG. 1 (b) is a view taken along line A in FIG. 1 (a). Figure, Figure 1
1C is a cross-sectional view taken along line B of FIG. 1A, and FIG. 1D is a cross-sectional view taken along line C of FIG. 1A.

As shown in these figures, a heater 1 includes a metal filament 2 serving as a heating element and a metal filament 2 serving as a heating element.
, A reflector plate 4 provided on the anti-heating side of the glass tube 3, and a ceramic heater fixing terminal 5 supporting both ends of the glass tube 3. . Therefore, most of the radiant energy from the metal filament 2 is reflected by the gold reflection film 3A on the back surface (reflection plate side) of the glass tube 3 toward the heated portion and further reflected on the opposite side of the heated portion. By arranging 4, the radiant energy is completely reflected to the heated portion side.
In addition, there is an effect that the reflected irradiation energy of the heaters from the opposite sides of the upper heater A and the lower heater B is also reflected from each other, so that the heating efficiency is further improved.

Further, a holding member 6 for supporting the heater fixed terminal 5 is provided between the heater fixed terminals 5, and a mounting base 7 is disposed thereon, and nuts 9 A, 9 B Thereby, the reflection plate 4 and the holding member 6 are fixed. Further, the wiring 10 is configured to be connected to the metal filament 2.

As described above, the heater 1 is fixed to the mounting base 7 by the bolts 8 and the nuts 9A and 9B. A groove 7A having the same width as the head of the bolt 8 is cut in the bolt insertion side of the mounting base 7 side. The rotation of the bolt 8 can be suppressed by fitting the head of the bolt 8 into the groove 7A. Therefore, the heater alone can be removed only by loosening the nut 9B on the heater side, so that the workability is excellent.

FIG. 2 is a structural view of a heater unit showing another embodiment of the present invention. FIG. 2 (a) is a front view of the heater unit, and FIG. It is a D line arrow line view. Here, only the upper heater A is shown, and the same parts as those in FIG. 1 are denoted by the same reference numerals and their description is omitted.

In this embodiment, as the heater fixing terminal,
It has metal mounting brackets 11 arranged on both sides. Then, metal mounting brackets 11 are provided at both ends of the holding member 12, and a mounting base 13 is disposed on the holding member 12, and the central portion thereof is passed through the bolt 14 and reflected by the nuts 15 </ b> A and 15 </ b> B. The plate 4 and the holding member 12 are fixed. The metal mounting bracket 11 is fixed to the holding member 12 and the reflection plate 4 by bolts 16 and nuts 17. In addition, bolt 1
In order to suppress the rotation of 4, a groove 14 </ b> A having a shape corresponding to the width of the head of the bolt 14 is formed in the mounting base 13. Further, the wiring 18 is configured to be connected to the metal filament 2.

Next, the dimensions of the heater unit (block-shaped heater) will be described.

FIG. 3 is an explanatory view of dimensions of various heater units showing an embodiment of the present invention. FIG. 3A shows a heater unit 21 of a square type (one-to-one) and a heater unit 22 of FIG.
FIG. 3B shows an example in which the heater unit 21 is a square type (one-to-one) and three heaters 22 are arranged (FIG. 11 described later, Rectangular type), FIG. 3 (c)
FIG. 3D shows an example in which the heater unit 23 is a rectangular type (1: 2) and two heaters 24 are arranged. FIG. 3D shows the heater unit 25 in a square type (2: 2).
FIG. 3E shows an example in which four heater units 26 are arranged.
FIG. 3F shows an example in which six heaters 24 are arranged in a rectangular type (3 to 2), and FIG. 3F shows an example in which two heaters 28 are arranged in a rectangular type (1 to 3). I have.

As described above, the dimensions of the heater unit (block-shaped heater) are basically square and rectangular, and the length of each unit is 1: 1, 1: 2, 2: 2, 3: 2 or 1: 3 size. In addition, FIG.
As shown in FIG. 3B, the heater output can be easily adjusted by increasing or decreasing the number of heaters 22 attached to the square type heater unit 21 from two to three (or one). Similarly, FIG. 3 (c), FIG.
As shown in FIG. 3 (d), FIG. 3 (e) or FIG. 3 (f), the number of heaters 24 and 28 can be various.

According to the present invention, a heating device can be constructed by combining such heater units (block-shaped heaters).

FIG. 4 is a plan view showing an arrangement of block heaters according to a first embodiment of the present invention, FIG. 5 is a plan view showing an arrangement of block heaters according to a second embodiment of the present invention, and FIG. FIG. 7 is a plan view showing an arrangement of block heaters showing a third embodiment of the present invention, FIG. 7 is a plan view showing an arrangement of block heaters showing a fourth embodiment of the present invention, and FIG. 8 is a fifth embodiment of the present invention. FIG. 9 is a plan view showing an arrangement of block heaters showing an example, FIG. 9 is a plan view showing an arrangement of block heaters showing a sixth embodiment of the present invention, and FIG. 10 is a block heater showing a seventh embodiment of the present invention. FIG. 11 is a plan view showing an arrangement of block heaters according to an eighth embodiment of the present invention, and FIG.
Is a plan view showing an arrangement of block heaters according to a ninth embodiment of the present invention, and FIG. 13 is a plan view showing an arrangement of block heaters according to a tenth embodiment of the present invention.

According to the first embodiment, as shown in FIG.
In both the first shot heating zone 31 and the second shot heating zone 32, a heater unit 21 having two square type heaters 22 shown in FIG. With such an arrangement, even if the sheet width is different, by eliminating unnecessary heater rows at the ends, it is possible to finely set the heating area according to the sheet width, and to reduce the sheet feed amount. Even if it changes, by turning off the heater in an unnecessary portion according to the feed amount, it is possible to heat only a necessary region. As described above, even if the sheet width and the feed amount are different, there is an advantage that a necessary heater area can be set finely.
Of course, it is also possible to set a small and partial heating temperature in the sheet heating area.

According to the second embodiment, as shown in FIG.
A heater unit 21 having two square type heaters 22 as shown in FIG.
Is disposed on the entire surface, and only one heater unit 27 having two heaters 28 shown in FIG. 3F is provided at a central portion on the entry side of the first shot heating zone 31 at right angles to the sheet flow direction. 3 and four heater units 26 having six heaters 24 shown in FIG. 3E are arranged along the sheet flow direction.

At both sides of the center, first, FIG.
The heater units 23 having two heaters 24 shown in FIG. 3 are arranged one by one in a direction orthogonal to the sheet flow direction, and further along the sheet flow direction, the heater unit 23 shown in FIG.
Four heater units 25 each having one heater 24 are arranged. Furthermore, on the outermost sides of both sides,
The heater units 21 having the two heaters 22 shown in FIG. 3A are arranged one by one along the sheet flow direction, and further along the sheet flow direction, the two heaters 24 shown in FIG. Are disposed four by four.

As described above, according to this embodiment, the second shot heating zone 32 is constituted by the heater unit 21, and the first shot heating zone 31 is constituted by the heater unit 2.
1, 23, 25 and 27 are combined.

Therefore, the first shot heating zone 31
By roughly dividing the heater units, the number of heater blocks to be controlled can be reduced, and the manufacturing cost can be reduced.

In such an arrangement, the heater division of the first shot heating zone 31 is somewhat large, but from the viewpoint of formability, the first shot heating zone 31 warms the sheet as a whole and heats the second shot heating zone 31. If the sheet temperature heating can be finely and partially controlled in the zone 32, a sufficient molded product can be obtained, and there is no problem in terms of function.

According to the third embodiment, as shown in FIG.
In the case of the second embodiment (FIG. 5), the number of heaters 24 of the heater units 25 and 26 in the first-shot heating zone 31 is halved to reduce the heater output. In that case, the heater units 25 and 2
6 heater 24 adjacent heater unit 24
Are arranged so as to be staggered in a direction orthogonal to the sheet flow direction.

Also in this embodiment, the temperature is finely controlled in the second shot heating zone 32. Therefore, uneven heating can be eliminated with a small number of heaters.

According to the fourth embodiment, as shown in FIG.
As shown in the first embodiment (see FIG. 4), the upper heater 41 has a square-type sheet flow direction in both the first-shot heating zone 31 and the second-shot heating zone 32 as shown in FIG. A heater unit 21 having two heaters 22 is arranged on the entire surface.

On the other hand, the heater arrangement of the lower heater 42 is arranged in a direction perpendicular to the sheet flow direction. That is, the heater arrangement of the lower heater 42 is set in the vertical direction with respect to the heater arrangement of the upper heater 41. By arranging the upper and lower heaters at right angles, there is a feature that local uneven heating of the heaters can be eliminated.

According to the fifth embodiment, as shown in FIG.
As in the fourth embodiment, the upper and lower heaters are arranged so as to be perpendicular to each other. The upper heater 43 has the same arrangement of the heater units as in the second embodiment (FIG. 5). On the other hand, the lower heater 44 is arranged in a direction orthogonal to the sheet flow direction so as to be entirely orthogonal to the heater arrangement of the upper heater 43.

That is, the first shot heating zone 31 has a heater unit 27 having two heaters 28 in the center, a heater unit 23 having two heaters 24 on both sides thereof, and two heater units 23 on both outermost sides. Nine heater units 21 each having the heater 22 are arranged in a direction orthogonal to the sheet flow direction. Here, the heater used is changed between the first and second shots. Also in this embodiment, local uneven heating of the heater can be eliminated.

According to the sixth embodiment, as shown in FIG.
The heater arrangement of the upper heater 45 of the first shot heating zone 31 is the same as that of the third embodiment (FIG. 6). For this heater arrangement, the first shot heating zone 3 of the lower heater 46
One heater arrangement is arranged so as to be at an alternate position with the heater arrangement of the upper heater. In addition, 1
Upper heater 4 of the sheet entrance of the shot heating zone 31
5 and the lower heater 46 have the same heater arrangement.

As described above, in a certain area in the first-shot heating zone, the positions of the heaters facing each other are shifted, so that there is a feature that uneven heating can be eliminated from each other.

According to the seventh embodiment, as shown in FIG. 10, the upper heater 47 and the lower heater 48 of the second-shot heating zone 32 are arranged to be orthogonal to each other. Also, 1
The heater arrangement of the upper heater 47 of the shot heating zone 31 is the same as that of the third embodiment (FIG. 6). With respect to this heater arrangement, the first shot heating zone 31 of the lower heater 48
Is arranged so that it is located at an alternate position with the heater arrangement of the upper heater. The arrangement of the heaters of the upper heater 45 and the lower heater 46 of the sheet entrance of the first shot heating zone 31 is the same. Also in this embodiment, local uneven heating of the heater can be eliminated.

According to the eighth embodiment, as shown in FIG. 11, in the heater arrangement, the heater pitch in the width direction of the heater is vertically shifted from each other by a half pitch. That is, in the upper heater 49, as shown in the first embodiment (FIG. 4), the heater unit 21 having two heaters 22 is arranged on the entire surface, but the lower heater 5
0, the three heaters 2 shown in FIG.
By arranging a heater unit 21 'having 2' and arranging a heater unit 21 having two heaters 22 in the other, the heater pitch is shifted vertically by half a pitch from each other. Also in this embodiment, local uneven heating of the heater can be eliminated.

According to the ninth embodiment, as shown in FIG. 12, the position of the upper and lower heaters 51 and 52 in the first shot heating zone 31 is shifted by a half pitch in a direction perpendicular to the sheet flow. Arranged in a state to prevent uneven heating. In addition, the second shot heating zone 32 is installed in a direction perpendicular to the heater arrangement of the first shot heating zone 31 to eliminate uneven heating of the first shot heating zone 31 and the second shot heating zone 32. I do.

According to the tenth embodiment, as shown in FIG. 13, the heater arrangement of the first-shot heating zone 31 and the second-shot heating zone 32 is shifted up and down, respectively, as compared with the case of the ninth embodiment (FIG. 12). It is characterized in that it is arranged in a state of being inverted by 90 °. That is, the rod-shaped heaters 29 are disposed so as to be perpendicular to the sheet flow direction, and the rod-shaped heaters 29 are disposed so as to be shifted by a half pitch between the upper heater 53 and the lower heater 54. Also in this embodiment, local uneven heating of the heater can be eliminated.

As described above, the heater used in the present invention has a very high heating element temperature of 800 ° C. to 1600 ° C. and a wavelength range of 1.5 to 2.5
μm, which is a very short wavelength range. It is characterized in that a heater having such a short wavelength is used for heating the resin, and the characteristic of this heater is that energy can penetrate and be absorbed deep inside the material, and heating can be performed from inside the material.

For this reason, the temperature of the conventional heating element, in which most of the energy is absorbed only by the material surface, is increased from 300 ° C. to 5 ° C.
Compared to a far-infrared heater of about 00 ° C., a uniform heating effect to the inside of the material can be expected.

As a result, in the case of a foamed sheet, it is possible to heat the material in a short time by penetrating the energy into the material and heating the material, and to increase the internal expansion ratio by increasing the temperature inside the material as compared with the conventional case. As a result, it is possible to approach an ideal sandwich structure of light weight and high rigidity.

Further, since the inside can be sufficiently heated without increasing the material surface temperature so much, the material surface roughness is improved as compared with the conventional far-infrared heater.

(1) As a first specific example of the present invention, FIG.
As shown in the figure, the expanded polystyrene sheet of Company A (PS
4 shows the results of a heating temperature rise test performed while P) was maintained in a temperature range of 180 ° C. to 220 ° C. in the heating device.

With the conventional far-infrared heater, it took 17 to 18 seconds to heat to around 170 ° C., which is the molding temperature. With the heating device of the present invention, heating was possible in about 4 seconds. The heating time is shortened.

(2) FIG. 15 shows the result of measuring the foam thickness of the material when heated by the heating device of the present invention.
Similarly, with the temperature inside the heating device kept in the range of 180 ° C. to 220 ° C., under the conditions of the heater output, upper: 90%, and lower: 100%, a sufficient thickness (5 mm
Above) is obtained. Also, under the conditions of the heater output, upper: 60%, lower: 70%, a secondary sheet thickness of sufficient thickness (5 mm or more) with excellent surface condition was obtained in 5 seconds. Moreover, the thickness of the obtained secondary sheet is thicker than the case of heating by the conventional far-infrared heater shown in FIG. In the far-infrared heater, as the heater temperature is increased, the favorable thickness of the surface state tends to gradually decrease.

The conventional far-infrared heater can be heated in about 5 seconds if the heater temperature is raised to 350 ° C., but the secondary sheet can only be about 4 mm thick.
Further heating will result in a slightly thicker, but poorer sheet surface.

Then, the heater temperature is changed from 300 ° C. to 250 ° C.
→ Even if the temperature is lowered sequentially to 200 ° C,
mm or more, and a long heating time is required.

(3) As a second specific example of the present invention, as a crystalline resin, a polypropylene sheet (PP sheet), a polybutylene terephthalate sheet (PBT sheet), and an amorphous resin which is a crystalline resin but is in an amorphous state,
The polyethylene terephthalate sheet (A-PET sheet) was heated while the temperature inside the heating device was kept in the range of 180 ° C. to 220 ° C., and the result of comparative measurement of the change in sheet transparency after the heating was shown in FIG. Although the effect differs somewhat depending on the type of resin and the thickness or the manufacturer, in general, the transparency of the material after heating can be improved by using the middle / near infrared heater according to the present invention in each material, as compared with the case of heating by the conventional far infrared heater. We confirmed that it was excellent.

Further, as shown in FIG. 17, in the case of heating a solid sheet, when a crystalline resin such as PP, PET, or PBT is heated, the radiant energy wavelength of the heater absorbed at the polymer level is short. Therefore, the crystallization rate is slow, and the influence on the crystal structure of the resin is small, and as a result, the heating can be performed while maintaining the transparency of the sheet, so that a molded article having extremely excellent transparency can be obtained. Can be

FIG. 18 shows the wavelength ranges of the heater radiation energy in the near-infrared region, the mid-infrared region, and the far-infrared region which are generally defined.

Further, as a specific example of the present invention, a polypropylene sheet having a foaming ratio of 1.3 to 5, which is a crystalline resin, is kept in a heating device at a temperature range of 180 ° C. to 220 ° C., and the sheet surface temperature is maintained. While maintaining the temperature in a temperature range of 170 ° C. to 185 ° C., and then heating.

That is, the foamed polypropylene sheet (foamed PP sheet) of Company B is heated to a temperature of 180 ° C.
The result of performing a heating temperature test while maintaining the temperature range of 20 ° C. is shown. Here, (1) Material: foamed PP sheet, thickness 1.3 mm, primary expansion ratio about 1.5 times (2) Heating result is as follows.

[0080] Conventional far-infrared heaters require a heating time of 40 seconds to 45 seconds, and even if the heater temperature is increased to shorten the heating time, the surface becomes rough and cannot be used. By using it, good heating in 30 seconds or less was made possible.

Further, since heating can be performed in a short time, there is an advantage that the amount of sag of the sheet is reduced, wrinkles caused by sagging of the molded product do not occur, and a good molded product is easily obtained. It was confirmed that there was.

The same technology is used for all foamed resin sheets, such as foamed PET sheets (polyethylene terephthalate), and resin sheets impregnated with a foaming material, so that unprecedented heating efficiency is exhibited. As a result, good-quality molding can be easily performed.

The present invention is not limited to the above-described embodiment, but various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0084]

As described above, according to the present invention, the following effects can be obtained.

(1) According to the apparatus for heating a resin sheet according to the first aspect, the heating efficiency can be improved, and fine temperature distribution of the resin sheet can be set, so that the sheet can be favorably heated.

(2) According to the apparatus for heating a resin sheet according to the second aspect, most of the radiant energy from the metal filament is reflected by the gold reflection film on the back surface of the glass tube to the heated portion side, and furthermore, By arranging the reflector on the opposite side of the heating section, the energy is completely reflected to the heated section side, and the reflected irradiation energy of the heaters from the opposite sides of the upper heater and the lower heater also reflects each other. This has an effect and can further improve the heating efficiency.

(3) According to the resin sheet heating device of the third aspect, it is possible to prevent the heater unit mounting bolt from turning around and to make the heater unit detachable from one side.

(4) According to the apparatus for heating a resin sheet according to the fourth aspect, a necessary heater area can be set finely even if the sheet width and the feeding amount are different.

(5) According to the resin sheet heating device of the fifth aspect, the temperature of the heater of the heater unit can be individually set and changed, so that the temperature of the partial heating in the sheet heating area is fine. Settings can be made.

(6) According to the resin sheet heating apparatus of the sixth aspect, by changing or displacing the arrangement of the upper and lower heaters, it is possible to eliminate local uneven heating of the heaters.

(7) According to the resin sheet heating apparatus of the seventh aspect, the heaters of the heater unit are arranged so as to be shifted by a half pitch between the upper heater and the lower heater, thereby locally heating the resin sheet. Unevenness can be eliminated.

(8) According to the resin sheet heating apparatus of the eighth aspect, the heater of the heater unit is arranged in the orthogonal direction between the upper heater and the lower heater, thereby eliminating local uneven heating of the sheet. It is something to do.

(9) According to the method for heating the expanded polystyrene sheet according to the ninth aspect, the foam thickness is large while maintaining a good surface condition, and the expansion ratio inside the material can be increased.

(10) According to the method for heating a crystalline resin sheet according to the tenth aspect, it is possible to obtain an excellent transparency whose transparency after heating is close to that of an original sheet.

(11) According to the method for heating a polypropylene sheet according to the eleventh aspect, it is possible to obtain excellent transparency whose transparency after heating is close to that of the original sheet.

(12) The amorphous material according to claim 12
According to the heating method of the polyethylene terephthalate sheet, it is possible to obtain excellent transparency whose transparency after heating is close to that of the raw sheet.

(13) According to the method for heating a polybutylene terephthalate sheet according to the thirteenth aspect, it is possible to obtain an excellent transparency whose transparency after heating is close to that of an original sheet.

(14) According to the method for heating a foamed polypropylene sheet according to the fourteenth aspect, good heating can be performed in 30 seconds or less.

Further, since the heating can be performed in a short time, the amount of sag of the sheet is reduced, and wrinkles caused by the sagging of the molded product are not generated, and a good molded product can be obtained.

[Brief description of the drawings]

FIG. 1 shows a heater (unit) showing an embodiment of the present invention.
1 (a) is a front view of the heater unit, FIG. 1 (b) is a view taken along line A in FIG. 1 (a), and FIG.
1C is a cross-sectional view taken along line B of FIG. 1A, and FIG. 1D is a cross-sectional view taken along line C of FIG. 1A.

FIG. 2 is a configuration diagram of a heater alone (unit) showing another embodiment of the present invention, FIG. 2 (a) is a front view of the heater unit, and FIG. 2 (b) is D in FIG. 2 (a). FIG.

3A and 3B are explanatory diagrams of dimensions of various heater units showing an embodiment of the present invention. FIG. 3A shows an example in which the heater unit is a square type (one-to-one) and two heaters are arranged. FIG. 3B shows an example in which the heater unit is a square type (one-to-one) and three heaters are arranged. FIG. 3C shows that the heater unit is a rectangular type (one-to-two) and two heaters are arranged. FIG. 3D shows an example in which the heater unit is a square type (2 to 2) and four heaters are arranged, and FIG. 3E shows a heater unit in a rectangular type (3 to 2) and the heater is FIG. 3F illustrates an example in which six heater units are arranged, and FIG. 3F illustrates an example in which two heater units are arranged in a rectangular type (1: 3).

FIG. 4 is a plan view showing an arrangement of block heaters according to the first embodiment of the present invention.

FIG. 5 is a plan view showing an arrangement of block heaters according to a second embodiment of the present invention.

FIG. 6 is a plan view showing an arrangement of block heaters according to a third embodiment of the present invention.

FIG. 7 is a plan view showing an arrangement of block heaters according to a fourth embodiment of the present invention.

FIG. 8 is a plan view showing an arrangement of block heaters according to a fifth embodiment of the present invention.

FIG. 9 is a plan view showing an arrangement of block heaters according to a sixth embodiment of the present invention.

FIG. 10 is a plan view showing an arrangement of block heaters according to a seventh embodiment of the present invention.

FIG. 11 is a plan view showing an arrangement of block heaters according to an eighth embodiment of the present invention.

FIG. 12 is a plan view showing an arrangement of block heaters according to a ninth embodiment of the present invention.

FIG. 13 is a plan view showing an arrangement of block heaters according to a tenth embodiment of the present invention.

FIG. 14 is a view showing the heating and heating characteristics of a fired PSP by the heating device of the present invention.

FIG. 15 is a diagram showing a heating test result by the heating device of the present invention.

FIG. 16 is a diagram showing a heating test result using a conventional far-infrared heater.

FIG. 17 is a diagram showing the results of a transparency comparison test after heating various materials.

FIG. 18 is a diagram showing a spectrum (wavelength, frequency, and photon energy) of an electromagnetic wave.

FIG. 19 is a view showing an outline of a thermoforming machine for a continuous sheet.

[Explanation of symbols]

1, 22, 22 ', 24, 28 Heater 2 Metal filament 3 Glass tube 3A Gold reflective film 4 Reflector 5 Heater fixing terminal 6, 12 Holding member 7, 13 Mounting base 7A, 14A Groove 8, 14, 16 Bolt 9A, 9B, 15A, 15B, 17 Nut 10, 18 Wiring 11 Metal mounting bracket 21, 21 ', 23, 25, 26, 27 Heater unit 29 Bar-shaped heater 31 First shot heating zone 32 Second shot heating zone A, 41, 43, 45, 47, 49, 51, 53 Upper heater B, 42, 44, 46, 48, 50, 52, 54 Lower heater

Claims (14)

[Claims] 1. A heating device for a resin sheet, wherein a maximum radiant energy wavelength of a heater is 1.5 μm in a heating section.
A heating apparatus for a resin sheet, wherein a plurality of heater units each including a heater having a mid / near infrared region of m to 2.5 μm are arranged. 2. The resin sheet heating apparatus according to claim 1, wherein the heater is a metal filament serving as a heating element, a glass tube containing the metal filament, and a mirror surface provided on the non-heating side of the glass tube. A reflective plate having properties,
An apparatus for heating a resin sheet, comprising a heater unit comprising a heater fixing terminal for supporting both ends of the glass tube. 3. The resin sheet heating apparatus according to claim 2, wherein the heater unit mounting base on which the heater unit is mounted has a groove adapted to the shape of the head of the heater unit mounting bolt. A heating device for a resin sheet, wherein co-rotation of bolts is prevented. 4. The resin sheet heating apparatus according to claim 1, wherein the heater unit has a planar size of 1: 1, 1: 2, 1: 3, 2: 2, or 2: 3. And a heater zone configured by combining these heater sizes. 5. The resin sheet heating device according to claim 1, wherein the temperature of the heater of the heater unit can be individually set and changed. 6. The resin sheet heating apparatus according to claim 1, wherein upper and lower heaters are provided in the heating unit, and an arrangement of the lower heater unit is changed or changed with respect to the upper heater unit. A heating apparatus for a resin sheet, wherein heaters are shifted in position. 7. The resin sheet heating device according to claim 6, wherein the heaters of the heater unit are arranged so as to be shifted by a half pitch between the upper heater and the lower heater. 8. The resin sheet heating apparatus according to claim 6, wherein the heaters of the heater unit are arranged in a direction orthogonal to an upper heater and a lower heater. 9. The method for heating a resin sheet according to any one of claims 1 to 8, wherein the expanded polystyrene sheet is maintained in a temperature range of 180 ° C. to 220 ° C. in the heating apparatus. A method for heating a resin sheet, comprising performing secondary foaming and heating while maintaining a surface temperature in a temperature range of 155 ° C to 175 ° C. 10. The crystalline resin is heated by using the resin sheet heating device according to any one of claims 1 to 8 while maintaining the temperature in the heating device in a temperature range of 180 ° C. to 220 ° C. A method for heating a resin sheet, comprising: 11. A heating apparatus for a resin sheet according to any one of claims 1 to 8, wherein a polypropylene sheet as a crystalline resin is heated to a temperature in a heating apparatus of 180 ° C. to 220 ° C.
The sheet surface temperature is maintained at 165 ° C
A method for heating a resin sheet, wherein heating is performed while maintaining the temperature in a temperature range of 190 ° C. 12. An amorphous polyethylene terephthalate sheet which is a crystalline resin but is in an amorphous state by using the heating apparatus for a resin sheet according to any one of claims 1 to 8, wherein the temperature in the heating apparatus is 180. A method for heating a resin sheet, wherein the heating is performed while maintaining the sheet surface temperature in a temperature range of 125 ° C to 150 ° C while maintaining the temperature range of ° C to 220 ° C. 13. A polybutylene terephthalate sheet, which is a crystalline resin, is heated to a temperature of 18 by using the resin sheet heating apparatus according to any one of claims 1 to 8.
A method for heating a resin sheet, wherein heating is performed while maintaining the sheet surface temperature in a temperature range of 160 ° C to 185 ° C while maintaining the temperature range of 0 ° C to 220 ° C. 14. A polypropylene sheet having a foaming ratio of 1.3 to 5, which is a crystalline resin, is heated to a temperature of 180 ° C. in the heating device by using the heating device for a resin sheet according to any one of claims 1 to 8. A method for heating a resin sheet, comprising: performing secondary foaming and heating while maintaining a sheet surface temperature in a temperature range of 170 ° C to 185 ° C while maintaining a temperature range of 220 ° C to 220 ° C.