JP2003103548A - Method for manufacturing compressed molded article of synthetic resin foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a compressed molded article of synthetic resin foam reduced in the irregularity of thickness or whole density, high in the uniformity of internal density, hard to generate thermal deterioration at the time of production and reduced in pressure loss in a case used as a filter medium. SOLUTION: The compressed molded article of synthetic resin foam reduced in the irregularity of thickness or whole density, high in the uniformity of internal density and reduced in pressure loss in the case used as the filter medium is manufactured by preheating the synthetic resin foam in a preheating process and holding the synthetic resin foam preheated in the preheating process between the hot plates of a hot press in the next hot press process to be hot-pressed to fix a compressed state. As the synthetic resin foam, one having a three- dimensional reticulated structure can be also used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a compression molded article of synthetic resin foam by utilizing a hot press.

[0002]

2. Description of the Related Art Conventionally, synthetic resin foams have been used in various fields such as interior materials for helmets, shoulder pads for clothes, cups for brassieres, foams for ink cartridges for printers, and filter materials. Among them, there is a high precision requirement for the thickness of the synthetic resin foam.

Further, as the synthetic resin foam for the filter material, a synthetic resin foam having a three-dimensional network structure with the cell membrane removed may be used. The synthetic resin foam for such a filter material is preferably one in which the skeletons of the cells are brought close to each other to increase the density in order to enhance the capillary phenomenon and obtain excellent filtering performance. Moreover, as the synthetic resin foam for the filter material, it is preferable that the accuracy of the entire density is high and that the density of the synthetic resin foam is uniform. Depending on the object to be filtered, the synthetic resin foam having the higher density is not used as a filter material as it is, but the synthetic resin foam having the higher density is impregnated with a thermosetting resin. Porous carbide obtained by carbonizing carbon may also be used as the filter material.

As a conventional method for producing a synthetic resin foam having high thickness accuracy or high density, a synthetic resin foam having elasticity such as soft polyurethane foam is sandwiched between hot plates of a hot press machine. A method for obtaining a compression-molded article in a compressed state by hot press molding is often used. If the thickness precision of the compression-molded product is high, the variation in the compression rate from the synthetic resin foam before compression is small and the precision of the density in the compression-molded product is high. It would be better to improve the accuracy.

However, in the conventional manufacturing method, in order to improve the thickness accuracy of the compression molded product, the hot pressing temperature must be raised to hot press the synthetic resin foam for a long time, and the hot pressing is performed. In the meantime, there is a problem that the surface of the synthetic resin foam that is in pressure contact with the hot plate deteriorates and the physical properties of the compression molded product deteriorate (yellowing, strength decrease, etc.). For example, in order to obtain a compression molded product of 10 mm ± 1.0 mm from a flexible polyurethane foam having a thickness of 50 mm by a conventional manufacturing method, the flexible slab polyurethane foam is hot-pressed for 15 minutes or more with a hot plate set at 210 ° C. Therefore, the resulting compression-molded product may be yellowed or deteriorated in strength, and may not be suitable depending on the intended use of the compression-molded product.

Further, in the winter season, the atmospheric temperature of the manufacturing work place is lower than in the summer season, and the synthetic resin foam whose temperature is lowered due to the influence of the atmospheric temperature is sandwiched between hot plates and hot-pressed. Compared with, the synthetic resin foam has to be hot pressed with a hot plate for a long time, not only the surface of the synthetic resin foam is prone to thermal deterioration, but also the thickness and density of the compression molded product obtained are accurate in the summer. And it tends to vary between winter.

Further, in the compression molded article for the filter material, while the heat is efficiently heated in the vicinity of the surface of the synthetic resin foam to which the hot plate is pressed during the hot pressing, the compression becomes good, whereas In the vicinity of the inner center away from the plate, the heating efficiency is inferior to that of the surface and compression is insufficient, so the density is low in the inner center of the compression molded product, but on the other hand, the density is high near the surface and uniform There is a problem that it is difficult to become. The problem of non-uniformity of the density increases as the synthetic resin foam used becomes thicker. In addition, the compression-molded product in which the dense layer is formed by increasing the density in the vicinity of the surface has a high pressure loss, so that its use as a filter material is restricted.

[0008]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above points, and has little variation in thickness and overall density, has high internal density uniformity, and is less likely to suffer thermal deterioration during manufacturing. Furthermore, the present invention provides a method for producing a compression molded product of a synthetic resin foam having a low pressure loss when used as a filter material.

[0009]

The invention of claim 1 comprises a preheating step of preheating a synthetic resin foam, and a hot pressing step of hot pressing the synthetic resin foam after the preheating step. The present invention relates to a method for producing a compression molded article of synthetic resin foam.

The invention of claim 2 is characterized in that the synthetic resin foam according to claim 1 has a three-dimensional network structure in which the cell membrane is removed.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, a synthetic resin foam is prepared by a preheating step of preheating a synthetic resin foam and a hot pressing step of hot pressing the synthetic resin foam after the preheating with a hot plate. To produce a compression-molded article.

As the synthetic resin foam used in the present invention, an appropriate one having compressible elasticity is used. Among them, flexible polyurethane foam is preferable from the viewpoint of cost and moldability. Further, the flexible polyurethane foam is preferably a slab foam product manufactured by open foaming and having an appropriate size. This slab foam product does not have a dense coating layer on the surface as compared with the mold foam product molded using the molding die, so the difference in density between the surface vicinity of the foam and the central part is small. There is.

Further, as the synthetic resin foam, when the compression molded article obtained by the practice of the present invention is used as a filter material or the like, a polyurethane foam having a known three-dimensional network structure with the cell membrane removed. Etc. are suitable. The polyurethane foam having a three-dimensional network structure from which the cell membrane is removed has a structure in which only the skeleton of the foam remains, and thus has high air permeability and is suitable as a filter material. The type, thickness, cell size, etc. of the synthetic resin foam used in the present invention are appropriately set according to the application of the compression molded product obtained by carrying out the present invention.

In the preheating step, the synthetic resin foam is heated in advance so that the subsequent hot pressing step can be performed in a short time. In this preheating step, the synthetic resin foam is stored in or passed through a heating furnace or the like, heated by hot air or the like, and not compressed by a hot plate such as a hot press.
In addition, the heating temperature in this preheating step is preferably equal to or lower than the upper limit temperature that does not significantly accelerate the thermal deterioration of the synthetic resin foam used. For example, when the upper limit temperature that significantly accelerates the thermal deterioration of the synthetic resin foam used is 200 ° C., the temperature of the preheating step is set to around 180 ° C. Furthermore, it is preferable to set the heating time so that the inside of the synthetic resin foam can be heated. The heating means is not limited to the one using the hot air, and any appropriate means can be used as long as it does not press the hot plate.

In the hot pressing step, the preheated synthetic resin foam is sandwiched between hot plates of a hot pressing device to be hot pressed to compress a required amount, and is heated to a temperature at which the compressed shape can be fixed. The hot pressing is continued for the time required to fix the compressed shape. At that time, since the synthetic resin foam is already heated in the preheating step which is the previous step and the temperature is high, the heating time by the hot press can be shortened, and the time of the entire hot press can be shortened. You can As a result, the time during which the synthetic resin foam directly contacts the hot plate is shortened, and heat deterioration due to contact with the hot plate can be suppressed. Furthermore, the synthetic resin foam to be hot pressed is already preheated in the preheating step, and heat is transmitted not only to the surface but also to the inside, so that the overall temperature rises, so that not only the surface but also the inside is softened. It is Therefore, in this hot pressing, the synthetic resin foam is likely to be uniformly compressed not only on the surface but also inside, and a compression molded product having a small density difference between the surface and the central portion can be obtained.

As the hot pressing device used for the hot pressing, any appropriate device can be used, such as one in which two opposing hot plates are moved forward and backward by a cylinder or the like to sandwich the synthetic resin foam. . The temperature of the hot plate during the hot pressing is preferably set to be equal to or lower than the upper limit temperature that does not significantly accelerate the thermal deterioration of the synthetic resin foam. For example,
When the upper limit temperature that significantly accelerates the thermal deterioration of the synthetic resin foam is 200 ° C, the temperature of the hot plate is set to around 180 ° C. The compression amount of the synthetic resin foam is
It is appropriately determined depending on the intended use of the compression molded product. After completion of the hot pressing, the desired compression molded product can be obtained by taking out the molded product with the hot plate interval widened.

Although the manufacturing equipment for the preheating step and the hot pressing step is appropriate, a preheating furnace is provided in the middle of a conveyor on which a synthetic resin foam of a predetermined size is placed and moved.
Preheating is carried out by passing the synthetic resin foam through the preheating furnace, and a manufacturing facility in which a hot pressing device for hot pressing the preheated synthetic resin foam is arranged on the downstream side of the conveyor is used. If so, a compression molded product can be efficiently manufactured.

The compression-molded product obtained as described above is cut into an appropriate size to be a product, or further covered with a cloth material or the like to be a product. Further, in order to obtain a porous carbide used for a filter material or the like,
The compression molded product may be impregnated with a thermosetting resin and then carbonized.

[0019]

Example 1 A polyurethane foam (trade name: MF-80, manufactured by Inoac Corporation) having a three-dimensional mesh structure with dimensions of 150 × 150 × 10 mm was heated in a hot air heating furnace for 15 minutes.
After preheating at 0 ° C for 180 seconds, it was sandwiched between hot plates at 150 ° C by a heat press device (tabletop test press SA-302-IS, manufactured by Tester Sangyo Co., Ltd.) to a thickness of 1 /.
Compress it to 5 (5 times the compression ratio), then 18
After holding for 0 seconds and hot pressing, it was cooled to room temperature to obtain the compression molded article of Example 1.

Example 2 Preheating in Example 1 was carried out at 175 ° C. for 85 seconds,
Example 1 except that the heat pressing was performed at 175 ° C. for 85 seconds.
A compression molded product of Example 2 was obtained in the same manner as in.

Example 3 A compression molded product of Example 3 was obtained in the same manner as in Example 1 except that the preheating in Example 1 was 200 ° C. for 85 seconds and the hot pressing was 200 ° C. for 85 seconds. .

Example 4 The size of the polyurethane foam in Example 1 was set to 150.
A compression-molded article of Example 4 was obtained in the same manner as in Example 1 except that the preheating was 175 ° C for 130 seconds, and the hot pressing was 175 ° C for 130 seconds.

Example 5 A compression molded article of Example 5 was obtained in the same manner as in Example 4 except that the preheating in Example 4 was 200 ° C. for 85 seconds and the hot pressing was 200 ° C. for 85 seconds. .

Comparative Example 1 A compression molded product of Comparative Example 1 was obtained in the same manner as in Example 1 except that the preheating in Example 1 was omitted.

Comparative Example 2 A compression molded product of Comparative Example 2 was obtained in the same manner as in Example 2 except that the preheating in Example 2 was omitted.

Comparative Example 3 A compression molded product of Comparative Example 3 was obtained in the same manner as in Example 3 except that the preheating in Example 3 was omitted.

Comparative Example 4 A compression molded product of Comparative Example 4 was obtained in the same manner as in Example 4 except that the preheating in Example 4 was omitted.

Comparative Example 5 A compression molded product of Comparative Example 5 was obtained in the same manner as in Example 5 except that the preheating in Example 5 was omitted.

With respect to the compression-molded articles of the respective Examples and Comparative Examples, the air permeability was measured according to JIS L 1004, and the overall density A and the density B near the surface of the portion 1 mm from the surface were measured. The total density A is the value obtained by dividing the weight of the entire compression molded product by the volume, and the surface vicinity density is the value obtained by cutting the relevant portion and dividing the weight of the relevant portion by the volume of the relevant portion. The measurement results are shown in Tables 1 and 2.

[0030]

[Table 1]

[0031]

[Table 2]

As can be seen from Tables 1 and 2, the compression-molded articles of the respective examples subjected to hot pressing after preheating were compared with the compression-molded articles of the comparative examples subjected to hot pressing without preheating. Also has high breathability (low pressure loss). Further, as is clear from the measurement results of the overall density A and the surface vicinity density B, the difference between the overall density A and the surface vicinity density B is smaller in the example. From these measurement results, it can be seen that in each of the examples subjected to the preheating, the density of the compression molded article as a whole was more uniform and the pore diameters were also more uniform than in each of the comparative examples not subjected to the preheating.

[0033]

As described above, according to the first aspect of the present invention, since the compression molded product is manufactured by preheating the synthetic resin foam and then hot pressing, the hot pressing time can be shortened, and It is possible to suppress the thermal deterioration of the synthetic resin foam that is caused by long pressure contact with the hot plate during hot pressing. Furthermore, since the entire synthetic resin foam is preheated by preheating and the synthetic resin foam in that state is hot pressed, the synthetic resin foam is smoothly heated to near the center of the synthetic resin foam at the time of hot pressing and the whole is uniformly compressed. As a result, the obtained compression-molded article has a uniform density and high thickness accuracy. Further, the compression-molded article obtained by the invention of claim 1 is suitable for various fields such as clothing and filter materials since it is less likely to undergo discoloration or deterioration of physical properties due to heat deterioration as described above. Further, since the compression molded product obtained by the invention of claim 1 has a uniform density and a small pressure loss, it is particularly suitable as a filter material as it is or as a porous carbide by other treatment. Is.

Further, the invention of claim 2 not only has the effect obtained by the invention of claim 1, but also uses the synthetic resin foam having the three-dimensional network structure with the cell membrane removed, so that the obtained compression molding is obtained. The product has better breathability,
The pressure loss is also small, and as it is as a filter material
Alternatively, it becomes more suitable as a porous carbide.

Front page continuation (51) Int.Cl. ⁷ identification code FI theme code (reference) C08L 75:04 C08L 75:04 (72) Inventor Kaneyasu Nakane 2-70, Jinno-cho, Atsuta-ku, Nagoya, Aichi Prefecture Co., Ltd. Inoac Corporation Kanno Factory F-term (reference) 4F074 AA78 CC03Z CC04Z 4F204 AA42 AG20 AH03 AH66 FB01 FE06 FF01 FG04 FH06 FN15 4F212 AA42 AG20 AH03 AH66 UA15 UB01 UB30 UW06 UW27

Claims (2)

[Claims] 1. A compression molding of a synthetic resin foam, comprising: a preheating step of preheating the synthetic resin foam; and a hot pressing step of hot pressing the synthetic resin foam after the preheating step. Method of manufacturing goods. 2. The method for producing a compression molded article of synthetic resin foam according to claim 1, wherein the synthetic resin foam has a three-dimensional network structure with the cell membrane removed.