JP2010216056A - Uniform heating method of air permeable board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a uniformly heating method of an air permeable board, capable of uniformly heating an air permeable board provided by laminating an air permeable resin layer and a fiber layer, within a shorter time than conventional methods even the intermediate layer of the board. <P>SOLUTION: An air permeable board W provided by laminating an air permeable resin layer 1 of the rear surface and a fiber layer 2 of the surface is heated with hot air in a heating furnace by supplying the hot air from the upper side and sucking from the down side to compulsorily pass through the inner part of the air permeable board W while the board carried. Simultaneously, radiation heating is performed with an infrared heater 9 from the down side to uniformly heat even the inner part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for uniformly heating a breathable plate-like body in which a breathable resin layer and a fiber layer are laminated in a heating furnace.

  In the manufacturing process of automotive interior materials, a carpet-like air-permeable plate-like body in which an air-permeable resin layer and a fiber layer, which are intermediate products, are laminated is heated to evaporate organic substances contained therein and resin layers Is softened and then press-molded to produce an interior product with a desired shape. In order to obtain a press-formed product with good quality, it is desired to uniformly heat not only the surface layer portion of the breathable plate-like body but also the inner intermediate layer. In the present specification, the intermediate layer does not mean a specific layer, but means the central portion in the thickness direction of the breathable plate-like body.

  As a method for heating a plate-like body, as shown in Patent Document 1, there is a method of radiant heating with an infrared heater from both the upper and lower sides in a furnace. However, when this radiant heating method is applied to a breathable plate-like body as described above, the surface layer heats up in a short time, but the fiber layer has poor thermal conductivity, so the intermediate layer does not heat up easily, and the intermediate layer is the target. There is a problem that the surface layer is excessively heated before reaching the temperature and the fiber layer is thermally contracted or the resin layer starts to melt. In order to avoid these problems, the surface temperature of the infrared heater must be lowered and heated over time.

  Further, a hot air heating method in which hot air is blown to raise the temperature is also known as a heating method for the plate-like body. In this method, when the object to be heated is a breathable plate, the hot air can reach the intermediate layer, so that the temperature can be increased while the temperature difference between the surface layer and the intermediate layer is reduced. However, since the temperature of the hot air must be suppressed to a temperature at which the fiber layer does not thermally shrink, it is impossible to raise the intermediate layer to the target temperature unless a longer time is used than the above-described radiation heating. There was a problem.

  As described above, in the conventional heating method, it takes time to uniformly heat the air permeable plate-like body in which the air permeable resin layer and the fiber layer are laminated to the intermediate layer. In order to improve the property, there is a problem that a large heating furnace is required.

Japanese Patent Laid-Open No. 10-27955

  Accordingly, the object of the present invention is to solve the above-mentioned conventional problems and to uniformly heat the breathable plate-like body in which the breathable resin layer and the fiber layer are laminated to the intermediate layer in a shorter time than before. It is to provide a method for uniformly heating a breathable plate.

  The present invention was made to solve the above problems, while conveying a breathable plate-like body in which a breathable resin layer on the back surface and a fiber layer on the front surface are laminated, inside the heating furnace with the back surface facing down. The hot air is forcibly permeated through the inside of the air-permeable plate by supplying hot air from above and sucked downward, and at the same time, radiant heating with an infrared heater is performed from below. It is what.

  In addition, it is preferable that the temperature of the hot air is a temperature at which the fiber layer is not thermally contracted, and the surface temperature of the infrared heater is preferably higher than the melting temperature of the breathable resin layer.

  In the present invention, hot air is forcibly permeated into the inside of the air-permeable plate-like body by supplying hot air from above the air-permeable plate-like body and sucking it downward, and at the same time from the lower side. Radiant heating is performed with an infrared heater. Since the air-permeable plate-like body has air permeability at the start of heating, the hot air permeates from the front surface to the back surface, and can raise not only the surface layer but also the intermediate layer. Also, as the temperature rises, the breathable pores are blocked by the softening and melting of the resin layer and the breathability is lowered, but the intermediate layer continues to rise due to heat conduction from both the front and back surfaces. It is possible to uniformly heat up to the intermediate layer in a short time of about half.

  For this reason, productivity can be improved compared with the conventional heating method, and a heating furnace can be reduced in size. Moreover, there is no heat shrinkage of the fiber layer, and the quality when press-molded in the next step is also good.

It is a typical expanded sectional view of the air permeable plate-shaped object which is a heating target object of this invention. It is sectional drawing of the heating furnace which shows embodiment of this invention. It is sectional drawing of the furnace width direction of the heating furnace which shows embodiment of this invention. It is a graph which shows the temperature rising state of the hot air heating method in an Example. It is a graph which shows the temperature rising state of the radiant heating method in an Example. It is a graph which shows the temperature rising state of the method of this invention in an Example.

Embodiments of the present invention will be described below.
FIG. 1 is a schematic enlarged cross-sectional view of a breathable plate-like body. As shown in this figure, the breathable plate-like body W is a carpet in which a breathable resin layer 1 on the back surface and a fiber layer 2 on the front surface are laminated. Intermediate product. The breathable resin layer 1 is made of a thermoplastic resin and has numerous breathable pores. The fiber layer 2 is made of, for example, polyester long fibers. The thickness is about 5 to 10 mm. In this embodiment, the thickness of the breathable resin layer 1 is about 2 mm, the thickness of the fiber layer 2 is about 5 mm, and the total thickness is 7 mm. This intermediate product is press-molded in the next step, but prior to that, uniform heating is required to evaporate and remove internal organic solvents and the like, and to raise the temperature of the resin to a temperature suitable for press molding. .

  2 and 3 are cross-sectional views showing the structure of a heating furnace used for carrying out the heating method of the present invention, 3 is a furnace body, and 4 is a conveyor horizontally penetrating the inside of the furnace chamber. . Although the kind of conveyor 4 is not specifically limited, It is preferable that it is a mesh conveyor which can let a hot air pass, and the net conveyor provided with the slat bar is used in this embodiment. The breathable plate-like body W is placed on the conveyor 4 with the breathable resin layer 1 on the back side as the lower side, and is uniformly heated to a desired temperature while being conveyed in the furnace chamber. The conveying method may be continuous feeding or intermittent feeding.

  A hot air supply box 5 is installed on the ceiling of the furnace chamber. The hot air supply box 5 has a large number of hot air outlets on its lower surface, and the hot air supplied from the hot air generator 7 is uniformly blown onto the upper surface of the breathable plate-like body W. A suction box 6 is installed below the conveyor 4, and hot air is sucked almost uniformly through suction holes formed on the upper surface thereof and is circulated to the hot air generator 7 by a heat-resistant blower 8. The temperature of the hot air is set to a temperature at which the fiber layer does not thermally shrink, and is set to 250 ° C., for example.

  A large number of infrared heaters 9 are arranged between the conveyor 4 and the suction box 6. In this embodiment, a planar ceramic heater manufactured by the applicant company is used as the infrared heater 9, but the present invention is not limited to this. The infrared heater 9 is installed with a predetermined interval between the air-permeable plate-like body W conveyed on the conveyor 4, and in this embodiment, the interval is set to 150 mm. It is more preferable that the interval can be adjusted according to the type of the plate-like body W. The infrared heaters 9 need to be installed with a space between them so that hot air can pass therethrough. Since the infrared heater 9 is disposed with a space between the air-permeable plate-like body W, the surface temperature can be set higher than the melting temperature of the air-permeable resin layer 1, for example, set to 750 ° C. Keep it.

  When the air-permeable plate-like body W is sent to such a heating furnace and hot air heating from the upper surface and radiation heating from the lower surface are performed, hot air is generated in a state where the air-permeable plate-like body W at the initial heating stage has high air permeability. Since the gas flows through the air-permeable plate W, not only the surface layer but also the intermediate layer is heated. However, as the temperature rises, the breathable pores of the breathable resin layer 1 gradually close and the breathability of the breathable plate-like body W decreases. Thereafter, the temperature rise of the intermediate layer is caused by heat conduction from both the front and back surfaces. Continuing, as shown in the data of the next embodiment, it is possible to raise the temperature uniformly to the intermediate layer in a short time of half or less than the conventional one.

  For this reason, productivity can be improved compared with the conventional method, or size reduction of a heating furnace can be achieved. Further, since the fiber layer 2 is not thermally shrunk and is uniformly heated to the inside, the molding quality when the press molding is performed in the next step is also good.

  In order to confirm the effect of the present invention, a heating test of the air-permeable plate-like body W is performed by a heating method using only hot air, a heating method using only an infrared heater, and a heating method of the present invention. The temperature was measured with a thermocouple thermometer. The used air-permeable plate-like body W is a flat plate having a thickness of 7 mm described in the embodiment. The hot air temperature was set to 250 ° C., the surface temperature of the infrared heater was set to 750 ° C., and the hot air temperature was set 150 mm below the breathable plate-like body W.

  FIG. 4 is a graph showing the temperature rise state of the heating method using only hot air. Although the temperature difference between the intermediate layer and the surface layer is relatively small, it takes time to raise the temperature, and the intermediate layer set as the temperature rise index is 150 ° C. The time to reach is about 75 seconds. FIG. 5 is a graph showing the temperature rise state of the heating method using only the infrared heater. The surface layers on both the front and back surfaces are heated rapidly, but the intermediate layer is only heated gradually by heat transfer. The time until the intermediate layer reaches 150 ° C. is about 90 seconds. On the other hand, according to the method of the present invention, as shown in FIG. 6, the intermediate layer rises smoothly with a small temperature difference from the surface layer, and reaches 150 ° C. in about 30 seconds. Thus, according to the present invention, it was confirmed that the temperature could be increased uniformly to the intermediate layer in a short time of half or less of the conventional method.

W Breathable plate 1 Breathable resin layer 2 Fiber layer 3 Furnace 4 Conveyor 5 Hot air supply box 6 Hot air outlet 7 Hot air generator 8 Blower 9 Infrared heater

Claims (3)

  By supplying hot air from above and sucking downward while transporting the breathable plate-like body in which the breathable resin layer on the back surface and the fiber layer on the front surface are laminated inside the heating furnace A method for uniformly heating a breathable plate-like body, wherein hot air is forcibly permeated through the inside of the breathable plate-like body and heated with hot air, and at the same time, radiant heating is performed from below with an infrared heater.   The method for uniformly heating a breathable plate according to claim 1, wherein the temperature of the hot air is set to a temperature at which the fiber layer does not thermally contract.   2. The method for uniformly heating a breathable plate-like body according to claim 1, wherein the surface temperature of the infrared heater is higher than the melting temperature of the breathable resin layer.

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