JP3553235B2 - Manufacturing method of rigid foam - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing a rigid foam, and more particularly, to a method for producing a rigid foam suitable for, for example, filling and reinforcing a hollow portion formed of a steel plate with a rigid foam.
[0002]
[Prior art]
Conventional rigid foams are manufactured by forming a resin body containing a fibrous substance and foaming it at a low magnification of about twice, or by including a porous filler in the resin layer. are doing. However, the rigid foam produced by the former conventional method described above can satisfy the rigidity, but since the foaming gas escapes from the contained fibrous portion, only a foaming ratio of about 2 times can be secured as a volume, and a sufficiently lightweight foam is obtained. Most of them were not achieved. Even when a fibrous substance is included in a compound having a high expansion ratio of more than 2 times, the foaming gas is released from the fiber portion, and the foam has a high ratio of more than 2 times and is reinforced with fibers. The body could not be manufactured.
On the other hand, in the latter production method using a porous filler, it is difficult to set the filler in a metal cavity (hereinafter, the metal cavity is simply referred to as a cavity).
[0003]
[Problems to be solved by the invention]
Therefore, in the research to obtain the lightweight and rigidity of the foam, the present inventor did not normally think that adding fiber to a high-magnification foam would promote outgassing, When the experiment was continued, it was experimentally confirmed that the foamed gas was contained at a high magnification of more than 2 times and had a rigid physical property despite the fact that the fiber was blended in the case of a specific blend. Knowing that the present invention has been achieved.
[0004]
That is, the object of the present invention is to solve the above-described disadvantages in the conventional rigid foam production by utilizing the experimental results of the present inventor, and it is easy to arrange in the cavity, and A method for producing a rigid foam that can be made into a lightweight and rigid foam structure that can achieve a higher expansion ratio than conventional ones, has a sufficient filling property with respect to the cavity, and has good adhesiveness with the cavity surface. To provide.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the invention of claim 1 is to form a foamable mixture by mixing a metal adhesive resin, a foaming agent, a foaming accelerator, a crosslinking agent, a polymerizable monomer, and a fibrous substance. Is disposed in the metal cavity of the component and heated.
[0006]
The invention according to claim 2 for solving the above-mentioned problem is characterized in that, in claim 1, mixing of a metal adhesive resin, a foaming agent, a foaming accelerator, a crosslinking agent, a polymerizable monomer, and a fibrous substance, foaming of the foaming agent. It is performed at a temperature that does not occur.
[0007]
According to a third aspect of the invention for solving the above-mentioned problems, in the first aspect, the metal adhesive resin is an ethylene-methyl acrylate copolymer resin (hereinafter, referred to as EMA) or an ethylene-ethyl acrylate copolymer resin (hereinafter, referred to as EEA). ) And ethylene-butyl acrylate copolymer resin (hereinafter referred to as EBA).
[0008]
According to a fourth aspect of the present invention, in order to solve the above-mentioned problem, in the first aspect, the metal adhesive resin contains low-density polyethylene in a proportion of 50% by weight or more of EMA, EEA, or EBA and 50% by weight or less of low-density polyethylene. It is a mixture.
[0009]
According to a fifth aspect of the invention for solving the above-mentioned problems, in the first aspect, the fibrous substance is a fiber having a fiber length of about 5 to 20 mm, and 10 parts by weight with respect to 100 parts by weight of the resin (hereinafter simply referred to as “part”). ~ 100 parts are mixed.
[0010]
The invention according to claim 6 for solving the above-mentioned problem is characterized in that the foamable mixture is formed into a block having a predetermined shape which can be arranged in a metal cavity.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Mixing and molding to obtain a foamable mixture are performed at a temperature that does not cause foaming of the blowing agent. For mixing and molding in the present invention, a known device can be selectively used as necessary. The heating of the foamable mixture arranged in the cavity can be performed under atmospheric pressure (normal pressure) using an appropriate heating means.
[0012]
The metal-adhesive resin is preferably a polymer of ethylene and an acrylate of an alcohol having 1 to 5 carbon atoms, and a resin having a polarity that can be bonded to a metal during heating and foaming, such as EMA, EEA, or EBA, may be used. . The metal adhesive resin may be a mixture containing LDPE in a proportion of 50% by weight or more of EMA or EEA or EBA and 50% by weight or less of low density polyethylene (LDPE). LDPE is preferably used in an amount of 50% or less to ensure adhesion. As the foaming agent, azodicarbonamide (ADCA), oxybis (benzenesulfonylhydrazide), dinitrosopentamethylenetetramine and the like can be used alone or in combination of two kinds.
As the foaming accelerator, Zn stearate, ZnO, MgO, stearic acid, and the like can be used.
As the crosslinking agent, dicumyl peroxide (DCP), 1,3-bis- (t-butylperoxyisopropyl) benzene, or the like can be used alone or in combination.
[0013]
Examples of the polymerizable monomer include triallyl cyanurate (TAC), triallyl isocyanurate (TAIC), and trimethylolpropane-trimethacrylate (TMP).
As the fibrous material, glass fiber (chopped strand), cut organic fiber, or the like can be used.
The fibrous substance is a chopped strand having a fiber length of about 5 to 20 mm, and is mixed in an amount of 10 to 100 parts by weight with respect to 100 parts by weight (hereinafter simply referred to as "part") of the resin. If the fiber length is less than 5 mm, the rigidity of the foamed product will not be sufficient. If the fiber length exceeds 20 mm, it is difficult to mix. If the amount of the fibrous substance is less than 10 parts, the effect of rigidity is not obtained, and if it exceeds 100 parts, the compound is difficult to knead and gas at the time of foaming easily escapes.
In addition, additives (calcium carbonate, talc, clay, and the like), reaction aids, and the like may be appropriately used.
Further, the foamable mixture is preferably formed into a block having a predetermined shape that can be arranged in a metal cavity.
[0014]
The foamable mixture is in an unreacted state in which each mixed component is simply mixed. Upon heating, each mixed component of the foamable mixture reacts to form a foam of about 2 to 5 times. The fibrous material does not significantly impair the foaming properties of the foaming gas and helps to improve the strength of the cured foam.
The foam of EMA, EEA or EBA has good adhesion to the metal surface of the cavity.
Fibers having a length of 5 to 20 mm do not significantly impair the foamability and serve to improve the strength.
The foamable mixture formed in the block is easy to arrange in the cavity.
[0015]
Hereinafter, a first embodiment of the present invention will be described.
100 parts of EMA, 3 parts of ADCA, 1 part of DCP, 0.2 part of ZnO, and 50 parts of glass fiber having a fiber length of 6 mm were kneaded with an oven roll and extruded into a sheet. This sheet was pressed at a low temperature at which foaming did not occur to form a sheet having a thickness of 10 mm. A molded body of a foamable mixture having a size of 20 × 70 mm was punched from the sheet. The molded body of the foamable mixture was placed in a cavity of a sheet metal-formed part of a steel sheet, and heated in an oven at 170 ° C. under atmospheric pressure for 25 minutes.
[0016]
As a result, the cavity portion was completely filled, and a good rigid foam (cured product) having rigidity after the filling was cured was obtained.
The cured product of this foam had a magnification of 4 times, and had strong rigidity. Its hardness was 45 according to JIS K6301C hardness tester.
The adhesiveness between the structure of the cured rigid foam and the cavity surface was strong.
[0017]
Next, a second embodiment of the present invention will be described.
100 parts of EMA, 2 parts of ADCA, 0.7 part of DCP, 0.2 part of ZnO, 1.0 part of stearic acid, 50 parts of calcium carbonate, and 30 parts of glass fiber having a fiber length of 13 mm are kneaded with an oven roll and sheet-shaped. Extruded. This sheet was put into a press at a low temperature at which foaming did not occur to form a sheet having a thickness of 5 mm. A molded article of the foamable mixture having a size of φ65 mm was punched from the sheet. The molded article of the foamable mixture was placed in a concave cavity of a sheet metal processed part and heated at 165 ° C. in an oven at atmospheric pressure for 30 minutes.
[0018]
As a result, a good rigid foam (cured product) having the cavity portion completely filled and having rigidity was obtained.
The cured product of this foam had a magnification of 3 times, and had strong rigidity. Its hardness was 38 according to JIS K6301C hardness tester. The adhesiveness between the structure of the cured rigid foam and the cavity surface was strong.
[0019]
【The invention's effect】
According to the first aspect of the present invention, the metal-adhesive resin adheres to the metal surface of the cavity during heating and foaming. Since the fibrous substance does not significantly hinder the foaming property of the foaming gas and makes the foam rigid, it is possible to obtain a cured product of a lightweight, rigid rigid foam.
According to the first aspect of the present invention, since each of the mixed components is a foamable mixture, which is arranged in the cavity, it is easy to handle and easily arranged in the cavity. According to the first aspect of the present invention, since a foaming ratio of about 2 to 5 times can be obtained, the filling property in the cavity is sufficient, the adhesiveness to the cavity surface is good, and a lightweight and rigid foam structure is provided. I can do it.
[0020]
According to the second aspect of the present invention, since the mixed components are mixed at a temperature at which the foaming agent does not foam, a foamed mixture of each component in an unreacted state can be obtained.
[0021]
In the invention of claim 3, since EMA, EEA, or EBA is used as the metal adhesive resin, a rigid foam (cured product) having good adhesion to the metal surface of the cavity can be obtained.
[0022]
According to the invention of claim 4, a rigid foam adhered to the metal surface of the cavity can be obtained. The greater the amount of EMA or EEA or EBA, the greater the degree of adhesion and rigidity.
[0023]
According to the fifth aspect of the present invention, a fiber having a length of about 5 to 20 mm can provide a good rigid foam (cured product).
[0024]
According to the sixth aspect of the present invention, since the foamable mixture is made into a block, it is easy to handle and arrange in the cavity.
In addition, the rigid foam according to the present invention has high rigidity and is lightweight, so that it is convenient for reinforcing hollow portions of various metal parts.

Claims (6)

Mixing a metal adhesive resin, a foaming agent, a foaming accelerator, a crosslinking agent, a polymerizable monomer, and a fibrous material to form a foamable mixture, disposing the mixture in a metal cavity of a part, and heating the mixture. A method for producing a rigid foam that has been characterized. 2. The rigid foam according to claim 1, wherein the mixing of the metal adhesive resin, the foaming agent, the foaming accelerator, the crosslinking agent, the polymerizable monomer, and the fibrous substance is performed at a temperature at which the foaming agent does not foam. Manufacturing method. The method for producing a rigid foam according to claim 1, wherein the metal adhesive resin is any one of an ethylene-methyl acrylate copolymer resin, an ethylene-ethyl acrylate copolymer resin, and an ethylene-butyl acrylate copolymer resin. Metal adhesive resin is an ethylene - methyl acrylate copolymer resin or ethylene - ethyl acrylate copolymer resin or an ethylene - butyl acrylate copolymer Oite the proportion of 50 wt% or less of 50% by weight or more with low density polyethylene polymer resin low density polyethylene The method for producing a rigid foam according to claim 1, which is a mixture containing: The method for producing a rigid foam according to claim 1, wherein the fibrous substance is a fiber having a fiber length of about 5 to 20 mm, and 10 to 100 parts by weight is mixed with 100 parts by weight of the resin. The method for producing a rigid foam according to claim 1, wherein the foamable mixture is formed into a block having a predetermined shape that can be arranged in a metal cavity.