JP2003320579A - Molding method for open-cell foam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molding method for a molded article which can be molded by a simple equipment and a short process, can retain a flexible feeling even after the molding, and is useful for housing fruit or the like, in molding an open-cell foam. <P>SOLUTION: An open-cell foam 1 (of which an expansion ratio is 10 to 40 times) such as EPDM is housed along the internal surface of a molding die 3 having a recess 2. Then, a ring-shape fixing member 4 is bonded to the opening part 6 of the housed foam, in the molding method for the open-cell foam. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding an open-cell foam used as a holding material or cushioning material for fruits and vegetables.

[0002]

2. Description of the Related Art Conventionally, a method of molding a foam has been to heat and mold it by a method such as thermocompression molding according to a desired shape. For example, while heating (1) one or more pieces of a crosslinked foamed product of a polyolefin or a mixture of a polyolefin and a rubber or a plastic which can be polymerized with the polyolefin in a mold to a temperature not lower than the softening point of the polyolefin. Molding method of compressing by 20% or more from one direction and then cooling while applying pressure (Japanese Patent Publication No. 52-49022), (2) crosslinked foamed ethylene polymer sheet having a gel fraction of 60 to 98% is used for male and female. A method of forming a mold by inserting it between a pair of molds and heating under pressure (JP-A-55-55834), (3) heating a crosslinked polyethylene-based open-cell sheet to 90 ° C to 120 ° C. A method (Japanese Patent Laid-Open No. 9-48035) of compressing with a mold at room temperature to form a desired shape has been proposed.

[0003]

However, in any of the above methods, the open cells were crushed during the heat molding, and the soft texture peculiar to the open cells was lost.
Further, the thermocompression molding requires equipment for repeating heating and cooling, and requires a long molding time. Therefore, an object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a method for molding an open-cell foam, which is capable of molding in a short time with simple equipment and maintaining a soft texture even after molding.

[0004]

According to the present invention, in order to achieve the above-mentioned object, a method for forming an open-cell body of the present invention comprises a continuous-cell sheet along an inner surface of a mold having a recess. A method for molding an open-cell foam, comprising storing and adhering a ring-shaped fixing member to the opening of the stored foam.

In the present invention, the base material of the open-cell foam is not particularly limited as long as the foam such as polyurethane, polyethylene and polyolefin such as ethylene-vinyl acetate copolymer is a flexible material. In view of the above, EPDM open-cell foam is preferable.

The open-cell foam of the present invention has a foaming ratio of 10
-40 times is preferable. If the expansion ratio is less than 10 times, it cannot be pushed into the mold during the molding process.
When the expansion ratio exceeds 40 times, it is too soft to obtain a desired shape.

In the present invention, the shape of the concave portion of the mold is not particularly limited, but a substantially hemispherical shape is preferable in terms of molding and storage of fruits and the like.

In the present invention, the shape of the open-cell body is appropriately selected according to the shape of the final molded product, but it is preferable in terms of molding to store the substantially circular sheet in the substantially hemispherical recess.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of the method for producing an open-cell body used in the present invention include (1) rubbers and softeners, fillers, reinforcing agents and sulfur powders, vulcanization accelerators, vulcanization aids. Kneading a rubber composition comprising an agent, a foaming agent, a foaming aid, etc. with a kneader,
An unvulcanized sheet formed into a sheet by an extruder is compression-molded in a mold and heated, and the rubber material is pressed and heated.
Substantially 1 part scorch state, after pre-treatment of the primary heating stage to form microscopic foam nuclei on the whole rubber fabric except thin skin, then taken out from the mold and separately adjusted to the expansion ratio In a large mold, a method of manufacturing by the secondary heating stage of the treatment process of foaming and vulcanizing,
(2) In addition to the thermal decomposition type foaming agent, a crosslinking agent, a foaming auxiliary agent, etc. are added to the polyolefin resin to which an inorganic filler is added as necessary, and the thermal decomposition type foaming agent is substantially contained. Melt-kneading at a temperature that does not decompose into a mixture, molded into a predetermined shape, and then crosslinked and foamed by heating, and the resulting crosslinked foam is mechanically deformed to allow bubbles to communicate with each other, after which a communication hole is further enlarged. Is mentioned.

In the present invention, as the rubbers, ethylene propylene diene copolymer rubber (EPDM), chloroprene rubber, styrene-butadiene copolymer rubber and the like are preferably used.

In the present invention, as the softening agent, process oil such as paraffin type process oil and naphthene type process oil, paraffin such as liquid paraffin, vaseline, polybutene, liquid polybutylene and the like can be used.

In the present invention, as the filler, for example, calcium carbonate, talc, and hard clay for rubber are preferably used.

In the present invention, as a foaming agent, an azo compound such as azodicarbonamide, diazoaminobenzene or the like is used as a main component, and another foaming agent component and, if necessary, other compounding agents are added and mixed, A foaming agent, a nitroso compound, a sulfonyl hydrazide system, etc., whose thermal decomposition temperature is lowered are used. These may be used alone or in combination of two or more.

In the present invention, the crosslinking agent is not particularly limited, and any conventionally known one may be used.
For example, dicumyl peroxide, 1,1-bis (t-
Butylperoxy) 3,3,5-trimethylcyclohexane, di-t-butylperoxyside, 2,5-dimethyl-2,5-di (t-butylperoxy) hexene-3, and the like. These may be used alone or in combination of two or more.

The polyolefin resin may be preliminarily crosslinkable by grafting a silane compound on the polyolefin resin without adding the crosslinking agent. The silane compound is not particularly limited, and any conventionally known silane compound may be used. For example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyldimethoxysilane, 3-
Methacryloxypropyltrixysilane and the like can be mentioned.

Further, crosslinking may be carried out by irradiation with ionizing radiation. Examples of ionizing radiation include electron beams,
α-rays, β-rays, γ-rays, etc. may be mentioned, and the irradiation amount thereof may be appropriately adjusted.

The foaming aid in the present invention is not particularly limited, and any conventionally known one may be used.
Examples thereof include zinc oxide, urea or a derivative thereof, magnesium stearate, zinc stearate, and the like, and these may be used alone or in combination of two or more kinds. The foaming aid is for adjusting the decomposition temperature, the decomposition rate, etc. of the heat decomposition type foaming agent, and the addition amount thereof is appropriately adjusted according to the production conditions, the amount of the foaming agent and the like.

In the molding of the present invention, the open-cell body is sliced into a thickness of preferably 5 to 40 mm. If the thickness exceeds 40 mm, it is difficult to mold, and if it is less than 5 mm, the cushioning property of the molded product is insufficient. Next, the sliced sheet of open cells is housed along the inner surface of the mold having the recess. The recess of the mold has a shape desired by the molded product, and preferably has a substantially hemispherical shape. In this case, the open-cell body sheet has a substantially circular shape, and its diameter is 1.1 times the diameter of the opening of the molding die.
2.0 times is preferable.

Next, a ring-shaped fixing member is adhered to the opening of the stored foam. The material of the fixing member is not particularly limited as long as it is a material having the strength to stop the spreading force of the open cells, and for example, the expansion ratio is 5 to 3
Zero-fold polyolefin foam, cardboard, resin molded products, etc. can be used.

As a method for adhering the above-mentioned fixing member to the opening of the open-cell body sheet, a method such as an adhesive, heat fusion or adhesion is adopted, and the method by adhesion is the simplest.

The present invention will be specifically described below with reference to the drawings. FIG. 1 shows a mold 3 having a substantially circular open cell sheet 1 and a substantially hemispherical recess 2. FIG. 2 is a schematic view in which the open-cell body sheet 1 is being accommodated along the inner surface of the recess 2 of the molding die 3. FIG. 3 shows a ring-shaped fixing member 4,
FIG. 3 is a schematic view before being bonded to the opening 6 of the open-cell body sheet 1 housed in the recess 2 of the molding die 3, in which the lower surface of the fixing member 4 is provided with an adhesive treatment 5. FIG. 4 is a schematic view showing a state where the fixing member 4 is bonded to the opening 6 of the open-cell body sheet 1 housed in the recess 2 of the molding die 3. Figure 5
FIG. 3 is a schematic view in which the final molded product 7 is released from the mold 3. FIG. 6 shows a molded product 7 obtained by the molding method of the present invention.
It is a schematic diagram of a usage example in which fruit 8 is stored in.

[0022]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples.

Example 1 EPDM open-cell foam (trade name: OPSELER OP-
130, foaming ratio 13 times, Sanwa Kako Co., Ltd.) diameter 21
A circular sheet with a thickness of 0 mm and a thickness of 10 mm has a diameter of 150 m
m and a depth of 75 mm are housed along the inner surface of a molding die (made of metal) having a hemispherical recess, and a polyethylene closed-cell foam (foaming ratio 14
A ring-shaped core material (outer diameter of 150 mm, inner diameter of 130 mm, thickness of 2 mm) made of double adhesive) was pasted with an acrylic adhesive to fix the shape of the open-cell foam and remove it from the molding die. .

The open-cell foam after molding retained the shape of a hemispherical mold, did not crush cells, and maintained a soft texture, had cushioning properties, and was suitable as a bag for storing fruits. .

Example 2 In Example 1, instead of the EPDM open cell, a polyethylene open cell (trade name: Opcel LC-30) was used.
It was molded in the same manner as in Example 1 except that 0 # 1, foaming ratio of 30 times, manufactured by Sanwa Kako Co., Ltd. was used. The obtained molded product retained the shape of a hemispherical mold, was not crushed by air bubbles, maintained a soft texture, had cushioning properties, and was suitable as a fruit storage bag.

Embodiment 3 In Embodiment 1, the fixing member is made of thick paper (the outer diameter and the inner diameter are the same).
A molded product was obtained in the same manner as in Example 1 except that
The shape of the obtained hemispherical mold was maintained, air bubbles were not crushed, the soft texture was maintained, and it had cushioning properties and was suitable as a fruit storage bag.

Comparative Example 1 In Example 1, the EPDM open-celled body sheet was housed along the inner surface of the concave portion of the molding die, adjusted in shape, and then heated directly below to fix the shape. Although the open-cell foam after molding retained a hemispherical shape, the cells on the surface were crushed by heat, resulting in poor flexibility.

[0028]

As described above, in the method for molding an open-cell foam according to the present invention, since the desired shape is formed without the heating step, the molding time is short, the energy is saved, and the heating / cooling equipment is installed. do not need. Since the open-cell foam molded product obtained in the present invention has open cells remaining on the surface thereof, it has excellent flexibility and is useful as a holding material or cushioning material for fruits and vegetables.

[Brief description of drawings]

FIG. 1 is a forming die and an open-cell body sheet before forming of the present invention.

FIG. 2 is a schematic view of a state in which an open-cell body sheet is being housed in a molding die in the molding process of the present invention.

FIG. 3 is a schematic view before the fixing member in the molding step of the present invention is bonded to the opening of the open-cell body sheet.

FIG. 4 is a schematic view showing a state in which a fixing member in the molding step of the present invention is bonded to an opening of an open-cell body sheet.

FIG. 5 is a schematic view of a molded product obtained by the molding method of the present invention in a state of being released from a mold.

FIG. 6 is a schematic view showing an example of use of a molded product obtained by the molding method of the present invention.

[Explanation of symbols]

1 Open cell sheet 2 recess 3 Mold 4 fixing members 5 Adhesive processing 6 Opening of open cell sheet 7 molded products 8 fruits

Claims (5)

[Claims] 1. An open-cell foaming method characterized in that an open-cell foam sheet is accommodated along an inner surface of a mold having a recess, and a ring-shaped fixing member is adhered to an opening of the accommodated foam. Body shaping method. 2. The molding method according to claim 1, wherein the open-cell foam is an EPDM open-cell foam. 3. The expansion ratio of the open-cell foam is 10 to 40.
The molding method according to claim 1, 2 or 3, wherein the molding method is doubled. 4. The molding method according to claim 1, 2 or 3, wherein the recess of the molding die is substantially hemispherical. 5. The molding method according to claim 4, wherein the open-cell foam is a substantially circular sheet.