JPH0445905A - Heating method for fiber reinforced thermoplastic resin sheet and its device - Google Patents

Abstract

PURPOSE:To heat efficiently and manufacture a resin sheet of good surface property by giving pressure to a fiber reinforced thermoplastic resin sheet expanded during heating when said sheet is heated before compression molding. CONSTITUTION:A plurality of tact ovens 1 are, for instance, disposed continuously, and infrared ray heaters 2 are installed on the upper and lower sections of respective tact ovens 1, and for instance, wire type conveyors 4 are disposed almost on the central sections of respective tact ovens 1, and pressurizing devices such as roll-type pressurizing device 6 are set on the outlet sides of respective tact ovens 1. Fiber reinforced thermoplastic resin sheet 3 cut in the given length are fed into a first tact oven 1 by the conveyors 4 and heated for a given time by a heater 2. The thermoplastic resin starts to be softened, and a sheet 3 starts to be expanded, and the sheet 3 expanded by the roll type pressurizing devices 6 provided on the outlet sides of respective tact ovens 1 is pressed and its thickness is also reduced, which makes the heat conduction in the vicinity of the surface better to transmit the heat to the inside of the sheet 3 and can be heated up to the temperature fit for the pressure molding to connect the thermoplastic resin with the inside of the sheet 3.

Description

[Detailed Description of the Invention] [Field of Application in Industry-1-] The present invention relates to a heating method before molding a fiber-reinforced thermoplastic resin sheet, which is a material for a 1a fiber-reinforced thermoplastic resin molded product, by a compression molding method. and devices.

[Prior art] A fiber-reinforced thermoplastic resin sheet is heated to soften the thermoplastic resin, and the resin is pressure-molded while the resin is in a fluid state to obtain a fiber-reinforced thermoplastic resin molded product. is well known. 2. Fiber Reinforcement Heat - 11 When a plastic resin sheet is heated, when the resin in the sheet begins to soften, it becomes stiff and expands due to the elastic force of the reinforcing fibers restrained by the resin. This expansion occurs from the heated surface of the sheet () and inhibits heat conduction into the interior of the sheet.

As a method to increase heating efficiency under such conditions, the heating area is divided into multiple zones, and the initial heating is performed at a high temperature and rapidly until the surface layer of the sheet melts. A method of heating to a temperature that is almost equal to the molding temperature is disclosed in JP-A-63-3020 (17-1+
is proposed.

[Problems to be Solved by the Invention] Fiber-reinforced thermoplastic resin sheets can be classified in various ways depending on the combination of materials and manufacturing history. A fiber-reinforced thermoplastic resin sheet manufactured using a method of manufacturing and then subjected to a neat link treatment and a fiber-reinforced thermoplastic resin sheet manufactured using a paper-making method using short fibers both expand, but the bender's sheet = [. 1. Since it is treated with links, it becomes stiff when it reaches a certain thickness, and cannot expand beyond a certain thickness. On the other hand, the latter sheet is made by cutting it into lengths of about 3 mm to about 50 mm, and dispersing reinforcing fibers in a wet state.
A blanket-like web made of
A fiber-reinforced thermoplastic resin sheet made by melting resin powder, compressing it, cooling it, and solidifying it in a noss, so-called a fiber-reinforced thermoplastic resin sheet manufactured by the papermaking method using short fibers, has three fine particles when the resin reaches its melting point. Due to its dimensional orientation, it expands significantly, as if a damp mass had been dried by the sun. , II. Physically, it expands to about 5 ir7 of the sheet's original thickness.

As the sheet thickness increases, Rli 1llf from the surface to the center of the sheet thickness becomes longer, and the heat conduction of the sheet at the surface area where there are more voids due to expansion becomes worse. The inside of the sheet does not reach its melting point even though it is so overheated that the surface of the sheet begins to burn due to the rise of warm air at the top of the sheet.

Therefore, the method of Japanese Patent Laid-Open No. 6:1-302007 provides a certain effect when the sheet is subjected to the needling treatment described above, but it requires a so-called navigation treatment. For the latter type of sheet, it takes a long time to heat the surface layer to a temperature where the internal temperature is almost equal to the molding temperature, even at a low temperature, so the molding cycle time becomes longer, and in some cases, the surface layer may Thermal deterioration of the resin may occur. Another disadvantage is that the amount of resin in the surface layer decreases and the reinforcing fibers float on the surface of the molded product, leading to surface defects.

The objective of the present invention is to eliminate such drawbacks (1) and provide a heating method and apparatus thereof that can perform efficient heating and obtain resin sheet molded products with good surface properties. .

[Means for Solving the Problems] The present invention provides that when heating a fiber-reinforced thermoplastic resin sheet, which is a material for a fiber-reinforced thermoplastic/T resin molded product, before compression molding, the sheet expanded during heating is ':1. A method for heating a fiber-reinforced thermoplastic resin sheet, characterized by rolling down the sheet, a method characterized by repeating the rolling operation of the sheet that expands once during the heating, and then rolls down the sheet several times,
The method is characterized in that the surface of the long sheet is cooled first and then heated while downstream, and a plurality of tact furnaces are arranged continuously or in parallel, and each tact furnace is arranged continuously. Fiber reinforcement heat t4)'
? A heating device for a fiber-reinforced thermoplastic resin sheet, characterized in that it is equipped with a pressurizing device for a lj-based resin sheet; The heating device is characterized by using a pressurizing device, and the heating device is characterized by having a cooling means attached to the −1° pressurizing device.

[Function] As described above, in the present invention, when a fiber-reinforced thermoplastic resin sheet, which is a material for a 1a fiber-reinforced thermoplastic resin molded product, is heated, the temperature of the sheet surface increases and eventually reaches the melting point of the resin. When the melting point is reached, the fibers become free and begin to expand. The sheet thickness is reduced by pressing and drying the Swallow sheet, which has expanded during heating, for a month, so that during heating after rolling, heat conduction near the compressed sheet surface improves, and the heat given from the sheet surface is reduced. Energy is now transmitted to the inside of the seat. As a result, the unsoftened resin is softened or preserved.

It is preferable to press the sheet as described above, for example, when the sheet expands to about double its thickness.

In the process of heating the sheet, a tendency to decrease in resin is observed, especially in the surface layer of the sheet, but the rolling operation of the expanded sheet during heating causes the resin to soften and melt and stagnate between the reinforcing fibers. Since the resin is brought into contact with the resin for 1 degree,
This has the effect of evenly dispersing the resin.

It goes without saying that infrared heating, which is commonly used in this field, can be used as a heating means for the sheet.

Further, in the present invention, by repeating the rolling operation of the expanded sheet during heating a plurality of times, for example, 2 to 3 times, heat conduction near the compressed sheet surface improves, and the thermal energy given from the sheet surface is improved. This can be said to be an effective heating method, especially for thick sheets, as the heat is transmitted to the inside of the sheet more quickly. Furthermore, the chance of re-contacting the reinforcing fibers with the softened and molten resin increases, and the effect of uniformly dispersing the resin increases. .

In addition, the present invention has the following advantages: - If the surface of the sheet expanded during heating is cooled while being compressed and then heated, it is disadvantageous in terms of heating energy, or the surface of the sheet is cooled. This helps prevent overheating and reduces the temperature difference between the sheet surface and the inside, resulting in a more evenly heated sheet. Furthermore, the softened and molten resin has the possibility of accumulating in equipment that comes into contact with the sheet in the transport range of the sheet, such as pressing devices such as rolls, which will be described later. If you keep it cool, you can reduce the phenomenon of adhesion.

Next, the apparatus according to the present invention will be explained based on the drawings.

FIG. 1 shows an embodiment in which a plurality of tact furnaces 1 are arranged in succession, and specifically, three tact furnaces 1 are arranged in succession. An infrared heater 2 is provided at the bottom of each tact furnace l. Further, approximately in the center of each tact furnace 1, for example, a wire type conhair 4 is arranged for conveying a fiber-reinforced thermoplastic ++1 resin sheet 3 cut into a predetermined length. The song conveyor 4 is supported by rolls 5 and is also driven.

A pressurizing device 6 is installed at the outlet side of each tact furnace 1. In this example, a pressurizing device 6, specifically a roll type pressurizing device 6, is installed at the outlet side of the first tact/furnace 1 and the second tact furnace 1.

In the heating device configured as described above, the TDIA fiber-reinforced heat-strengthened thermoplastic resin sheet 3 cut into a predetermined length is conveyed in the direction of the arrow by the bear 4 and charged into the first tact furnace 1, and then the infrared heating heater 2), the sheet 3 is heated from the L1 side for a predetermined period of time. During this heating process, the thermoplastic resin starts to soften due to the heat supplied from the front and back surfaces of the sheet 3. At the same time, the sheet 3 starts to expand. After a predetermined time, the sheet 3 is transferred from the first tact furnace 1 to the second tact furnace 1.
The expanded sheet 3 is conveyed to the tactile furnace 1 by a roll-type pressurizing device 6 provided on the outlet side of the first tact furnace 1, and
Then, the second
By heating in the tact furnace 1, heat conduction near the surface of the compressed sheet 3 improves, and the thermal energy obtained from the surface of the sheet 3 is transmitted to the inside of the sheet 3 7'f15. Similarly, while being conveyed from the second tact furnace 1 to the third tact furnace 1, the sheet 3 expands by 1ff degree (the sheet 3 is compressed and heated, so the inside of the sheet 3 is heated. Plastic +
+[The resin can be heated to a temperature suitable for subsequent pressure molding (not shown).

FIG. 2 shows one tact furnace 1 in which a plurality of tact furnaces 1 are arranged in parallel, except that a roll type pressurizing device 6 is installed approximately in the center of the tact furnace 1. The other configurations are the same as in FIG. 1.

, the roll of the above-mentioned roll-type addition device 6 has an internal water-cooled structure 1. Therefore, the fiber-reinforced thermoplastic resin sheet 3 cut into a predetermined length is conveyed by a conveyor 4 in the direction of the arrow and placed in a tact furnace. 1, and is heated from the L upper surface of the sheet 3 by an infrared heating beater 2 for a predetermined period of time. In this heating process, the thermoplastic resin begins to soften due to the heat supplied from the front and back surfaces of the sheet 3, and at the same time, the sheet 3 begins to swell and claw. After a predetermined time, the expanded sheet 3 is compressed by a roll-type pressure device 6 provided at the center of the tact furnace 1 to reduce the thickness of the sheet. Shrinked notebook 3
Heat conduction near the surface is improved, and thermal energy applied from the surface of the sheet 3 is transmitted to the inside of the sheet 3. Since the roll surface of the roll-type pressurizing device 6 is cooled, depositing of resin e on the roll during sheet pressing is suppressed.

FIG. 3 shows an embodiment in which one tact furnace 1 is arranged continuously and a pressurizing section 7 is separately constructed between the two furnaces. A caterpillar type pressurizing device 6 is installed in the pressurizing section 7. This pressurizing device 6 has a configuration in which reticular entress belts 8 are arranged one above the other. When the inflated seat 3 is pressurized by this caterpillar type pressurizing device 6, the ambient air gas present in the seat 3 can be discharged in a desired direction. In this pressurizing section 7, instead of the caterpillar type pressurizing device 6, a press type pressurizing device 6 as shown in FIG. 4 can be installed. The press surface 9 of this press type pressurizing device 6 is composed of a mesh plate or a perforated plate, and for example, when the L portion press surface 9 is moved up and down by the movement device η10, the atmosphere existing in the expanded sheet 3 is removed. The waste can be discharged in any direction.

[Example] Example 1 Setting conditions: The heating furnace shown in FIG. 1 was used. In the conventional heating power method, heating was performed using a pressure trol. The results are shown in the table below.

・Infrared heating heater set at 260℃, compared with heating conditions that bring the sheet surface temperature to 220℃ ・Cara y & fiber content 40wt! A+ resin is polypropylene 1 non-fio+w1. '14 [Effects of the Invention] - According to the heating method and apparatus of the present invention described above, the following effects can be expected.

■Papermaking method: Expansion of thickness range of stampable sheets.Conventionally, the thickness of stampable sheets with a glass content of 40% is 3 mrn.
However, in the present invention, it is possible to heat even a plate with a thickness of 5 mm. 1 ■ Paper-making method that reduces heating time without burning the stampable sheet.
When trying to heat the center of f, in the conventional method, the set temperature of the heating heater is set to "1", which is about the same as the standard temperature, 'Xl-
In other words, if one standard is set at 220℃, the heating time will be extremely long, but in the present invention, the temperature of the heating heater can be lowered to make it more efficient. heating is possible.

■Reduced charging time and handling effort Since JI7-sized sheets can be used, handling time is saved and time is reduced.

Improvement of 0 surface + 1 condition Since the handling time is shortened, there is less temperature drop, and the flow of resin to the molded product surface is improved, so the lifting of reinforcing fibers to the molded product surface is reduced, and the surface quality is improved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an embodiment in which a plurality of tact furnaces are arranged continuously. FIG. 2 is an explanatory diagram of an embodiment in which a plurality of tact furnaces are arranged in parallel. FIG. 3 is an explanatory diagram of another embodiment in which a plurality of tact furnaces are successively arranged. FIG. 4 is an explanatory diagram of one aspect of the pressurizing device. 1... Tough I Furnace, 2... Infrared heating heater, 3
... Fiber-reinforced thermoplastic +11 resin sheet cut to a predetermined length, 4 ... Wire conveyor, 5 ... Conveyor support, drive roll, 6 ... Rolling down device, 7 ... Pressure section , 8... Reticulated en l<' 1 Nosbelt, 9...
・Mesh plate or perforated plate press surface, 10...old 'F
It is a cantering device. .

Claims (1)

[Claims] 1. A fiber characterized in that when heating a fiber-reinforced thermoplastic resin sheet, which is a material for a fiber-reinforced thermoplastic resin molded product, before compression molding, the sheet expanded during heating is once compressed. Method for heating reinforced thermoplastic resin sheets. 2. The method according to claim 1, characterized in that the rolling down operation of the expanded sheet during the heating is repeated a plurality of times. 3. Claim 1, characterized in that the surface of the sheet expanded during the heating is cooled while being compressed, and then heated.
Or method 2. 4. Multiple tact furnaces are arranged continuously or in parallel,
A fiber-reinforced thermoplastic resin, characterized in that a pressurizing device for a heated fiber-reinforced thermoplastic resin sheet is provided at the outlet side of each tact furnace arranged in series or at the middle part of each tact furnace arranged in parallel. Seat heating device. 5. The apparatus according to claim 4, wherein a press type pressurizing device is used as the pressurizing device. 6. The apparatus according to claim 4, wherein a roll type pressurizing device is used as the pressurizing device. 7. The apparatus according to claim 4, wherein a caterpillar type pressurizing device is used as the pressurizing device. 8. The apparatus according to any one of claims 4 to 7, characterized in that the pressurizing device is provided with a cooling means.