JP4166502B2 - Molding method of open cell foam - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for forming an open-cell foam used for holding materials and cushion materials such as fruits and vegetables.
[0002]
[Prior art]
Conventionally, the foam is molded by heating by a method such as hot-pressure molding according to the target shape. For example, (1) while heating one or two or more pieces of a cross-linked foam of a polyolefin or a mixture of a polyolefin and a polymerizable rubber or plastic to a temperature above the softening point of the polyolefin in a mold A molding method (Japanese Patent Publication No. 52-49022) in which compression is performed at least 20% from one direction and then pressure is applied, and (2) a cross-linked foamed ethylene polymer sheet having a gel fraction of 60 to 98% is male and female. A method of forming a mold by inserting between a pair of molds and pressurizing and heating (Japanese Patent Application Laid-Open No. 55-55834), (3) heating a cross-linked polyethylene-based open cell sheet to 90 ° C. to 120 ° C. A method of compressing with a normal temperature mold and forming it into a desired shape (Japanese Patent Laid-Open No. 9-48035) has been proposed.
[0003]
[Problems to be solved by the invention]
However, in any of the above methods, the open cells were crushed during the heat molding, and the soft texture peculiar to open cells was lost. In addition, hot pressing requires equipment for repeated heating and cooling, and requires a long molding time. Accordingly, an object of the present invention is to provide a method for forming an open-cell foam that eliminates the disadvantages of the prior art and retains a soft texture even after molding by simple molding with a short period of time.
[0004]
[Means for Solving the Problems]
According to the present invention, in order to achieve the above-mentioned object, the method for molding an open cell body of the present invention is to store an open cell sheet along the inner surface of a mold having a recess, An open-cell foam molding method characterized by adhering a ring-shaped fixing member to an opening.
[0005]
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 has flexibility, but in terms of flexibility and touch. EPDM open cell foam is preferred.
[0006]
The open-cell foam of the present invention preferably has an expansion ratio of 10 to 40 times. If the expansion ratio is less than 10, it cannot be pushed into the mold during molding. When the expansion ratio exceeds 40 times, it is too soft and the desired shape cannot be obtained.
[0007]
In the present invention, the shape of the concave portion of the mold is not particularly limited, but a substantially hemispherical shape is preferable for molding and storage of fruits and the like.
[0008]
In the present invention, the shape of the open-cell body is appropriately selected depending on the shape of the final molded product, but it is preferable in terms of molding to store a substantially circular sheet in a substantially hemispherical recess.
[0009]
DETAILED DESCRIPTION OF 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 powder, vulcanization accelerators, vulcanization aids, foaming agents, foaming aids. A kneading machine is used to knead a rubber composition composed of an agent, etc., and an unvulcanized sheet molded into a sheet by an extruder is compression-molded in a mold frame and heated, and the rubber fabric is pressurized and heated. After a pre-treatment in the primary heating stage to form a very small foam core on the entire rubber fabric other than the thin skin, it was then removed from the mold frame and separately adjusted to the expansion ratio. A method of manufacturing by a secondary heating stage of a foaming and vulcanizing treatment process in a large mold frame, (2) a pyrolytic foaming agent to a polyolefin resin to which an inorganic filler is added if necessary In addition, if necessary, a crosslinking agent, a foaming aid, etc. are added, After melt-kneading at a temperature that does not qualitatively decompose and molding into a predetermined shape, it is heated to cross-link and foam, and the resulting cross-linked foam is mechanically deformed to allow bubbles to communicate, and then the communication hole is further expanded. The method of letting it be mentioned.
[0010]
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.
[0011]
As the softening agent in the present invention, process oil such as paraffinic process oil and naphthenic process oil, paraffin such as liquid paraffin, petrolatum, polybutene, liquid polybutylene, and the like can be used.
[0012]
In the present invention, as the filler, for example, calcium carbonate, talc, and hard clay for rubber are preferably used.
[0013]
In the present invention, as a foaming agent, for example, an azo compound such as azodicarbonamide, diazoaminobenzene or the like is a main component, and another foaming agent component and other compounding agents are added to and mixed with this, and a thermal decomposition temperature is added. For example, a foaming agent, a nitroso compound, a sulfonyl hydrazide, or the like that is used for reducing the temperature of the resin is used. These may be used alone or in combination of two or more.
[0014]
In the present invention, the crosslinking agent is not particularly limited, and any conventionally known crosslinking agent may be used. For example, dicumyl peroxide, 1,1-bis (t-butylperoxy) 3, 3, Examples include organic peroxides such as 5-trimethylcyclohexane, di-t-butylperoxyside, 2,5-dimethyl-2,5-di (t-butylperoxy) hexene-3, and these may be used alone. Two or more kinds may be used in combination.
[0015]
A silane compound may be grafted to the polyolefin resin without adding the crosslinking agent, and the polyolefin resin may be previously crosslinkable. The silane compound is not particularly limited, and any conventionally known silane compound may be used. Examples thereof include vinyltrimethoxysilane, vinyltriethoxysilane, vinyldimethoxysilane, and 3-methacryloxypropyltrixysilane. .
[0016]
Further, crosslinking may be performed by ionizing radiation irradiation. Examples of the ionizing radiation include electron beams, α rays, β rays, γ rays, and the dose may be appropriately adjusted.
[0017]
In the present invention, the foaming aid 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. May be used alone or in combination of two or more. The foaming assistant adjusts the decomposition temperature, decomposition rate, and the like of the above pyrolyzable foaming agent, and the amount added is appropriately adjusted according to the production conditions, the amount of foaming agent, and the like.
[0018]
In the molding of the present invention, the open cell body is preferably sliced to a thickness of 5 to 40 mm. When the thickness exceeds 40 mm, molding is difficult, and when the thickness is less than 5 mm, the cushioning property of the molded product is insufficient. Next, the sheet | seat of the sliced open cell body is accommodated along the inner surface of the shaping | molding die which has a recessed part. The concave portion of the mold has a shape desired by the molded product, and preferably has a substantially hemispherical shape. In this case, the open cell sheet is substantially circular, and its diameter is preferably 1.1 to 2.0 times the diameter of the opening of the mold.
[0019]
Next, a ring-shaped fixing member is bonded to the opening of the accommodated foam. The material of the fixing member is not particularly limited as long as it is a material having the strength of stopping the spreading force of open cells, for example, a polyolefin foam having a foaming ratio of 5 to 30 times, a cardboard, a resin molded product, etc. Can be used.
[0020]
As a method of adhering the fixing member to the opening of the open cell sheet, methods such as an adhesive, heat fusion, and adhesion are adopted, and the method using adhesion is the simplest.
[0021]
Hereinafter, the present invention will be specifically described 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 showing that the open cell sheet 1 is being stored along the inner surface of the recess 2 of the mold 3. FIG. 3 is a schematic view before the ring-shaped fixing member 4 is bonded to the opening 6 of the open cell sheet 1 accommodated in the recess 2 of the molding die 3. Processing 5 has been applied. FIG. 4 is a schematic view showing a state in which the fixing member 4 is bonded to the opening 6 of the open cell sheet 1 accommodated in the recess 2 of the mold 3. FIG. 5 is a schematic view in which the final molded product 7 is released from the mold 3. FIG. 6 is a schematic view of a usage example in which fruits 8 are stored in a molded product 7 obtained by the molding method of the present invention.
[0022]
【Example】
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.
[0023]
Example 1
EPDM open cell foam (trade name: Opsealer OP-130, expansion ratio 13 times, manufactured by Sanwa Kako Co., Ltd.) Molding a circular sheet with a diameter of 210 mm and a thickness of 10 mm with a hemispherical recess having a diameter of 150 mm and a depth of 75 mm It is housed along the inner surface of the mold (made of metal), and a ring-shaped core material (outer diameter 150 mm, inner diameter) made of polyethylene closed cell foam (expanding ratio 14 times) as a fixing member on the upper surface of the molding mold The diameter of 130 mm in diameter and 2 mm in thickness) was pasted with an acrylic pressure-sensitive adhesive to fix the shape of the open-cell foamed material and taken out from the molding die.
[0024]
The open-cell foam after molding maintained the shape of a hemispherical mold, the bubbles were not crushed, kept a soft texture, had cushioning properties, and was suitable as a fruit storage bag.
[0025]
Example 2
In Example 1, Example 1 was used except that a polyethylene-based open cell (trade name: Opcell LC-300 # 1, foaming ratio 30 times, manufactured by Sanwa Chemical Co., Ltd.) was used instead of the EPDM open cell. The same method was used. The obtained molded article retained the shape of a hemispherical mold, did not crush bubbles, maintained a soft texture, had cushioning properties, and was suitable as a fruit storage bag.
[0026]
Example 3
In Example 1, a molded product was obtained in the same manner as in Example 1 except that the fixing member was changed to cardboard (the same outer diameter and inner diameter). The shape of the obtained hemispherical mold was maintained, bubbles were not crushed, a soft texture was maintained, cushioning properties, and suitable as a fruit storage bag.
[0027]
Comparative Example 1
In Example 1, the EPDM open cell sheet was stored so as to be along the inner surface of the concave portion of the molding die, and after adjusting the shape, it was heated immediately below to fix the shape. Although the open-cell foam after molding maintains a hemispherical shape, the bubbles on the surface are crushed by heat and the flexibility is poor.
[0028]
【The invention's effect】
As described above, the method for forming an open-cell foam according to the present invention is formed into a desired shape without going through a heating step. Therefore, the forming time is short, energy is saved, and heating / cooling equipment is not required. The open-cell foamed molded article obtained by the present invention has excellent flexibility because it has open cells on its surface, and is useful for holding materials such as fruits and vegetables, cushioning materials, and the like.
[Brief description of the drawings]
FIG. 1 shows a molding die and an open cell sheet before molding according to the present invention.
FIG. 2 is a schematic view of a state in which an open cell sheet is being stored in a mold 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 sheet.
FIG. 4 is a schematic view of a state in which a fixing member is bonded to an opening of an open cell sheet in the molding process of the present invention.
FIG. 5 is a schematic view showing a state where a molded product obtained by the molding method of the present invention is 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]
DESCRIPTION OF SYMBOLS 1 Open cell sheet 2 Recessed part 3 Mold 4 Fixing member 5 Adhesion processing 6 Opening part 7 of open cell sheet Molded article 8 Fruit

Claims (4)

The continuous cell foam sheet is accommodated along the inner surface of the molding die having a recess without being heated and processed, and a ring-shaped fixing member is adhered to the opening of the accommodated foam. A method of forming a cellular foam.   2. The molding method according to claim 1, wherein the open cell foam is an EPDM open cell foam. The molding method according to claim 1 or 2 , wherein the open cell foam has an expansion ratio of 10 to 40 times.   4. The molding method according to claim 1, wherein the concave portion of the molding die is substantially hemispherical.

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