JP2006307019A - Breathable foam and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a breathable foam and a method for manufacturing the same. <P>SOLUTION: The breathable foam is obtained by pre-expanding polystyrene material beads to prepare pre-expanded beads, adding block particles chosen from calcium carbonate, talc, mica, silica, zeolite, wood flour or paper dust and a binder chosen from a vinyl acetate polymer, starches or gelatin to the pre-expanded beads and mixing, drying, pulverizing and molding the same, wherein the block particles are previously kneaded with the binder. A method for manufacturing the breathable foam is also provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a breathable foam and a method for producing the same.

  Conventionally, foam products made by mixing raw material beads with a hydrocarbon-based foaming agent such as butane or pentane, applying foam to foam, and placing in a mold and heat molding are known. Since such a foam product contains about 98% air, it is very light, has excellent heat retaining properties and cold retaining properties, is strong in impact, and has excellent characteristics of blocking water and moisture. Because of these characteristics, foam products have many uses such as marine and vegetable food transport boxes, cup ramen containers, shock absorbers that protect household appliances from impacts, lightweight embankment methods, and artificial soil.

  The largest amount of foam products shipped by application is for food containers, which account for about 60% of the total. However, in terms of preserving live materials for a long time, foam products have a problem that the materials are easily corroded because they are not breathable.

  The present invention has been made in view of such problems, and provides a breathable foam having air permeability in addition to the excellent properties of conventional foams such as heat retention and a method for producing the same. With the goal.

  As a result of intensive studies, the present inventors have found a method for producing a breathable foam having both the properties of a closed cell type and an open cell type, and have reached the present invention.

  That is, in order to achieve the above object, the present invention includes pre-expanding raw material beads to prepare pre-expanded beads, mixing the pre-expanded beads with block particles and a binder, and thereafter forming the beads.

  The raw material beads are preferably polystyrene raw material beads. The raw material beads are preferably pre-expanded 30 to 60 times. Moreover, it is preferable to knead | mix the said block particle | grain and the said binder beforehand, and to make it a kneaded material. The addition amount of the block particles is preferably 5 parts by weight to 60 parts by weight with respect to 100 parts by weight of the raw material beads after preliminary foaming. The mixture of the kneaded product and the pre-expanded beads is preferably dried in advance at a drying temperature of 18 ° C. to 60 ° C., and the drying time of the mixture is 3 minutes to 20 minutes depending on the volume. It is preferable. As the block particles, inorganic compound or organic compound powders such as calcium carbonate, talc, mica, silica, zeolite, wood powder, paper powder and the like are used. Of these, calcium carbonate is preferred. The binder is preferably at least one selected from the group consisting of vinyl acetate polymers, starches, and gelatins. As the block particles, those having an average particle size of 10 μm to 2 mm are used. Among them, it is preferable to use an average particle size of 100 μm to 1 mm.

  In another aspect, the present invention is a breathable foam, which is obtained by the above-described method for producing a breathable foam.

  According to the present invention, in addition to the superior properties of conventional foams such as heat retention, a breathable foam having breathability and a method for producing the same are provided.

  In the breathable foam and the production method thereof according to the present invention, the breathable foam is preferably obtained by adding premixed block particles and a binder to the pre-foamed beads, mixing, drying, pulverizing, and thermoforming. Manufacturing. The foaming ratio of the foam is preferably 30 to 60 times. As a result, the conventional foam has air permeability and water permeability, and maintains the same performance as the conventional foam with respect to heat retention.

  In the method for producing a breathable foam according to the present invention, polystyrene raw material beads are preferably used as the raw material beads.

  Such raw material beads are preferably pre-expanded 30 to 60 times. Most commonly, it is prefoamed about 50 times.

  The block particles and the binder are preferably kneaded in advance to form a kneaded product.

  Examples of the block particles to be kneaded include inorganic compound or organic compound powders such as calcium carbonate, talc, mica, silica, zeolite, wood powder, and paper powder, among which calcium carbonate is preferable.

  By adding the block particles to the pre-expanded beads as described above, air permeability and water permeability are imparted to the foam according to the present invention.

  The particle size of the block particles is preferably 100 μm to 2 mm, and particularly preferably 500 μm.

  The addition amount of the block particles is preferably 5 parts by weight to 60 parts by weight with respect to 100 parts by weight of the raw material beads after preliminary foaming.

  The binder to be kneaded is preferably at least one selected from the group consisting of starches, vinyl acetate polymers, and gelatins. The above binders may be used alone or in combination of two or more.

  As the vinyl acetate polymer, polyvinyl acetate, ethylene-vinyl acetate copolymer, vinyl chloride-vinyl acetate copolymer and the like are preferable.

  It is preferably used in the range of 35 to 45 parts by weight of the binder with respect to 100 parts by weight of the raw material beads, and more preferably 40 parts by weight of the binder with respect to 100 parts by weight of the raw material beads.

  Moreover, it is preferable to dry in advance the mixture of the kneaded material and the pre-expanded beads according to the present invention. The drying temperature is preferably 18 ° C. to 60 ° C., and particularly preferably 45 ° C. Further, the drying time of the mixture is preferably 3 minutes to 12 minutes, particularly preferably about 10 minutes.

  Further, the mixture is preferably put in a mold and heated by steam at 110 ° C. to 120 ° C. and optimally 115 ° C.

  According to the present invention, as described above, in addition to excellent characteristics such as heat retention, air permeability can be obtained, but such an air permeability mechanism has not been investigated accurately. However, in general, foams are classified into a closed cell type and an open cell type depending on how the units (cells) of the cell structure are in contact with each other. A cell structure unit (cell) that is completely independent is called a closed cell type. The cell is not connected, and air and water are not passed through, so it has excellent shock absorption, workability, and buoyancy. Used for shock absorbing cushions, beet plates, gaskets, etc. On the other hand, the open cell type allows air and water to pass through because the cells are adjacent to each other. Therefore, the open-cell breathable foam has excellent breathability, water absorption, and sound absorption, and is mainly used for kitchen sponges and filter media.

  Therefore, if it is possible to develop a foam having the properties of the above-mentioned closed cell type and open cell type, in addition to the conventional heat retaining property, breathability is imparted, and fresh foods such as marine products and vegetables can be kept fresh. It can be stored for a long time.

  According to the present invention, an intermediate foam between a closed cell type and an open cell type is obtained. This is demonstrated by the following examples.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples.

  100 parts by weight of polystyrene beads (trade name: JQ-251, manufactured by JSP Corporation) were heated with steam for 3 minutes and prefoamed 50 times. 80 parts by weight of a kneaded material obtained by kneading 40 parts by weight of a binder and 40 parts by weight of calcium carbonate having a particle diameter of 500 μm in advance is added to 100 parts by weight of pre-expanded polystyrene beads and mixed. After drying for a minute, it was pulverized, placed in a mold and molded at 115 ° C. with a molding machine to obtain a breathable foam.

Water permeability imparting test In order to verify the water permeability of the breathable foam, measurement was performed using the following experimental method.
A breathable foam container (sample A) and a conventional foam container (sample B) produced by the method of Example 1 were used. 200 ml of water is put into each foam molded product (length 20 cm x width 30 cm x height 15 cm), weighed, and then left for one week, then the water is discarded and a breathable foam container and a conventional foam container The weight of was measured. The results are shown in Table 1.

  As is clear from Table 1, it was found that the breathable foam (sample A) was given water permeability as compared to the conventional product (sample B).

Breathability test (1)
In order to verify the breathability of the breathable foam, measurement was performed using the following experimental method.
A breathable foam container produced by the method of Example 1 was used. For the block particles, calcium carbonate having an average particle diameter of 500 μm was used. Put a container containing 100 ml of water into the breathable foam container (length 20 cm × width 30 cm × height 15 cm) obtained in Example 1 and the conventional foam container (length 20 cm × width 30 cm × height 15 cm). The temperature and humidity in the breathable foam container were measured using a thermohygrometer in a thermostat set to 30 ° C. The results are shown in FIGS.

  As is clear from FIG. 1 and FIG. 2, when the breathable foam container of the present invention is compared with the conventional foam container, there is almost no difference in the temperature change in the container over time, and a constant temperature. I knew I could keep Further, in the humidity change, there is a difference between the breathable foam container of the present invention and the conventional foam container, and the breathable foam container maintains a lower humidity than the conventional foam container. I understood.

Breathability test (2)
According to the method of Example 1, vegetables (lettuce) were put into a breathable foam container (foam container of the present invention) and a normal foam container (conventional foam container), and left for one week. It was confirmed.

  The lettuce placed in the conventional foam container is gradually corroded with the passage of days, but the lettuce placed in the breathable foam container of the present invention does not corrode even after 7 days and is fresh. I found out that

  The breathable foam of the present invention is characterized by having breathability and water permeability while maintaining heat retention as in the conventional foam. For example, an example of a product that takes advantage of heat retention and breathability is a flower box. In addition to breathability, helmets and heat insulating materials that use the original lightweight properties of foam, and slats made of breathable foam instead of wood are less likely to grow and are easy to handle.

In Example 3, it is a line graph which shows the temperature change in the foam container by a breathability provision test about the conventional foam container and the breathable foam container shape | molded using calcium carbonate as a block particle. In Example 3, it is a line graph which shows the humidity change in the foam container by the air permeability provision test about the conventional foam container and the breathable foam container shape | molded using calcium carbonate as a block particle.

Claims (11)

A method for producing a breathable foam comprising pre-expanding raw material beads to prepare pre-expanded beads, mixing block particles and a binder into the pre-expanded beads, and then forming the mixture. The method for producing a breathable foam according to claim 1, wherein the raw material beads are polystyrene raw material beads. The method for producing a breathable foam according to claim 1 or 2, wherein the raw material beads are pre-foamed 30 to 60 times. The method for producing a breathable foam according to any one of claims 1 to 3, wherein the block particles and the binder are kneaded in advance. The amount of the block particles added is 5 to 60 parts by weight with respect to 100 parts by weight of the raw material beads after the pre-foaming, The breathable foam according to any one of claims 1 to 4, Production method. The method for producing a breathable foam according to claim 4, comprising drying a mixture of the kneaded product and the pre-expanded beads at a drying temperature of 18 ° C. to 60 ° C. in advance. The method for producing a breathable foam according to claim 6, wherein the drying time of the mixture is 3 minutes to 20 minutes. The aeration according to any one of claims 1 to 7, wherein the block particles are at least one selected from the group consisting of calcium carbonate, talc, mica, silica, zeolite, wood powder, and paper powder. For producing a porous foam. The air-permeable foam according to any one of claims 1 to 8, wherein the binder is at least one selected from the group consisting of a vinyl acetate polymer, starches, and gelatins. Method. The method for producing a breathable foam according to claim 1, wherein the block particles have a particle size of 100 μm to 2 mm. A breathable foam obtained by the method for producing a breathable foam according to any one of claims 1 to 10.

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