JPH07290482A - Propylene resin foam - Google Patents

Abstract

PURPOSE:To provide a propylene resin foam member excellent in heat resistance and pressure resistance and suitably used as a core material such as an interior material for a vehicle. CONSTITUTION:When a test piece with a thickness of 2-8mm is pressed under such a condition that pressing force is 60-80kgf/cm<2> and a pressing time is 20sec-1min. by a heating press in such a state that one surface thereof is heated to 200-220 deg.C while the other surface thereof is held to a normal temp., the thickness reduction ratio at the normal temp. thereof is 40% or less. The compression strength of the test piece at the time of 50% compression is 2.0kg/cm<2> or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a propylene-based foam which is excellent in heat resistance and pressure resistance and is preferably used as a core material for interior materials for vehicles.

[0002]

2. Description of the Related Art Conventionally, when a vehicle interior material is manufactured, a propylene-based foam is used as a core material, and a skin material is laminated on one surface by heat lamination or extrusion lamination,
A method in which this laminated body is supplied to a stamping mold to perform stamping molding to form a base material layer of a molten thermoplastic resin on the surface of a propylene-based foam and to integrally mold it into a desired shape is generally performed. .

[0003]

In this case, the propylene-based foam used as the core material is crushed as a whole by heat or pressure during heat lamination, extrusion lamination or stamping molding, and sagging occurs. However, there is a problem in that during heat lamination, extrusion lamination, or stamping molding, the surface of the resin is partially crushed due to contact with the melted resin, particularly near the resin gate portion, resulting in unevenness on the surface.

The present invention solves the above-mentioned problems of the prior art, does not cause sagging or unevenness on the surface, has excellent heat and pressure resistance, and is a core for interior materials for vehicles and the like. The purpose of the present invention is to provide a propylene-based foam that is preferably used as a material.

[0005]

The present invention has a thickness of 2 to 8 m.
The test piece of m was heated at a temperature of 2 on one side with a heating press.
00-220 ° C, other surface at room temperature, pressure 60-60k
gF / cm ² , a reduction rate of the thickness at room temperature after applying pressure of 20 seconds to 1 minute is 40% or less,
Further, it is a propylene-based resin foam characterized by having a compressive strength at 50% compression of 2.0 kg / cm ² or less.

The propylene resin composition as a raw material used for producing the propylene resin foam of the present invention includes a propylene resin, a thermal decomposition type foaming agent, a crosslinking accelerator and a crosslinking accelerator. Examples thereof include peroxides used in combination as required, antioxidants added as required, pigments, and other additives.

Examples of the propylene resin include a homopolymer of propylene, a block copolymer with an olefinic monomer such as ethylene having 50% by weight of a propylene component, a random copolymer, ethylene and butene. For example, a terpolymer of the above olefinic monomer is used. These polymers may be used alone or in combination of two or more.

As the thermal decomposition type foaming agent, any one can be used as long as it has a thermal decomposition temperature higher than the melting temperature of the resin composition, for example, azodicarbonamide or the same as or equivalent to azodicarbonamide. Examples thereof include hydradodicarbonamide, azodicarboxylic acid amide, azodicarboxylic acid barium salt, dinitrosopentaethylenetetramine, nitrosoguanidine, p, p'-oxybisbenzenesulfonyl semicarbazide, which have higher thermal decomposition temperatures. These thermal decomposition type foaming agents may be used alone or in combination of two or more kinds.

The content of the thermal decomposition type foaming agent is preferably 0.01 to 30% by weight of the propylene resin, and 0.05 to 1
5% by weight is more preferable.

As the crosslinking accelerator, for example, divinylbenzene, diallylbenzene, divinylnaphthalene, polyethylene dimethacrylate, trimethylolpropane methacrylate, triallyl isocyanurate and the like are used. These cross-linking accelerators may be used alone or in combination of two or more. The content of the crosslinking accelerator is preferably 0.01 to 30% by weight of the propylene resin, and more preferably 0.05 to 15% by weight.

As another cross-linking method, it is possible to carry out cross-linking by irradiating with ionizing radiation after molding at a temperature lower than the thermal decomposition temperature of the thermal decomposition foaming agent.

As the peroxide which is optionally used in combination with a crosslinking accelerator for chemical crosslinking, for example, methyl ethyl ketone peroxide, t-butyl peroxide,
Dicumyl peroxide or the like can be used. The content of the peroxide is preferably 0.01 to 10% by weight of the propylene resin, and more preferably 0.05 to 5% by weight.

The polypropylene-based foam used as a core material in the production of vehicle interior materials and the like by the stamping molding method is used for thermal lamination or extrusion lamination.
Since it is brought into contact with the molten resin at 0 to 220 ° C. and is further pressed during stamping molding, the bubbles are easily collapsed as a whole.

Therefore, the propylene-based foam of the present invention is
In order to prevent the above-mentioned air bubbles from collapsing so that the air bubbles retain their functions as interior materials for vehicles, etc., the thickness is 2 to 8 m.
The test piece of m was heated at a temperature of 2 on one side with a heating press machine.
00-220 ° C, other surface at room temperature, pressure 60-60k
gF / cm ² , a reduction rate of the thickness at room temperature after applying pressure of 20 seconds to 1 minute is 40% or less,
In addition, the compressive strength at 50% compression must be 2.0 kg / cm ² or less.

The relationship between the pressure at the time of hot pressing and the thickness reduction rate will be described in more detail with reference to FIG. FIG. 1 shows that a test piece having a thickness of 2 to 8 mm is supplied to a hot press machine, one surface of which is 200 to 220 ° C. and the other surface of which is at room temperature.
Pressurizing pressure (kgf / cm ² ) for 20 seconds to 1 minute,
It shows the relationship with the rate of decrease (%) in thickness at room temperature after a predetermined time has elapsed after taking out from the hot press after pressurization.

The propylene resin foam of the present invention is shown in FIG.
When the pressure is 60 to 80 kgf / cm ² , it is necessary to satisfy the condition of the range shown by the diagonal line surrounded by the thickness reduction rate of 40%. Pressure is 60-80kgf / cm
If the thickness reduction rate at ² exceeds 40%, is generally crushed bubbles, the vehicle interior materials obtained, sag occurs.

Further, in the propylene-based foam of the present invention, in order to prevent stress from concentrating on a portion in contact with the molten resin, a test piece having a thickness of 2 to 8 mm is compressed at 50% according to JIS K6767. Compressive strength of 2.0kg /
It must be below cm ² .

The relationship between the compressibility and the compressive strength during the hot pressing will be described in more detail with reference to FIG. Thickness 2-8
Compressive strength (kgf) of 25-75% compression of mm test piece
/ Cm ² ) is plotted. The propylene-based resin foam of the present invention needs to satisfy the condition that the compressive strength at 50% compression is 2 kgf / cm ² or less, as in sample X in FIG.

When the compressive strength of the propyne foam at 50% compression exceeds ² kgf / cm 2, as in sample Y in FIG. 2, especially in the vicinity of the resin gate portion during thermal lamination, extrusion lamination or stamping molding. The stress concentrates on the portion that comes into contact with the molten resin, and the bubbles are partially collapsed, resulting in unevenness on the surface of the obtained vehicle interior material or the like.

The propylene-based foam of the present invention is used for automobile ceiling materials, door linings, instrument covers,
Console box cover, rear wheel house cover,
It is preferably used as a core material for interior materials for vehicles, which is molded by a stamping molding method, in a lagged house cover, a luggage compartment cover, particularly a door lining for an automobile, an instrument cover and the like.

When the propylene-based foam of the present invention is used as a core material for a vehicle interior material, a skin material is laminated on one surface thereof. As the skin material, if it is a cloth type, a polyester type, a polyamide type, a synthetic fiber such as an acrylic type, a natural fiber such as a cellulose type, or a vinyl chloride resin type if the resin type is used,
Any thermoplastic elastomer system or the like can be used. As a laminating method, an arbitrary method such as an adhesive method, a heat laminating method, or an extrusion laminating method can be adopted.

[0022]

The propylene-based foam of the present invention has a thickness of 2 to 8 m.
The test piece of m was heated at a temperature of 2 on one side with a heating press machine.
00-220 ° C, other surface at room temperature, pressure 60-60k
Since the reduction rate of the thickness at room temperature after pressing under the conditions of gf / cm ² and pressing time of 20 seconds to 1 minute is 40% or less, it is used as a core material for thermal lamination or extrusion. When secondary processing is performed on a vehicle interior material, etc. via lamination or stamping molding, air bubbles are not crushed as a whole, and the obtained vehicle interior material does not suffer from settling. Compressive strength at 50% compression is 2.0k
When it is g / cm ² or less, stress concentrates on a portion which is in contact with the molten resin during thermal lamination, extrusion lamination or stamping molding, and bubbles are partially collapsed,
No unevenness is generated on the surface.

[0023]

EXAMPLES The present invention will be described below with reference to examples. EXAMPLE A propylene-based resin composition comprising 75 parts by weight of polypropylene, 25 parts by weight of polyethylene, 3 parts by weight of a crosslinking aid (divinylbenzene), and 12 parts by weight of a foaming agent (azodicarboxylic acid amide) was used as a foaming agent. An unfoamed sheet was obtained by extruding with an extruder at a temperature below the decomposition point.

A crosslinked unfoamed sheet was obtained by irradiating the unfoamed sheet with ionizing radiation from the upper and lower sides for the first time of 3 to 4 Mr and for the second time of 4 to 5 Mr. This cross-linked unfoamed sheet is heated to 220 ° C. in a foaming machine to apply tension in the longitudinal direction to foam, and at the same time also apply tension in the width direction to stretch in the width direction and then cool to foam. Magnification 15 times,
A propylene resin foam having a thickness of 3 mm was obtained.

From the resulting propylene resin foam, 10
A test piece 1 as shown in FIG. 3 was prepared by cutting into cm squares, and the thickness of about 5 points was measured by a thickness meter according to JIS k6767, and the thickness measurement points were marked.

The test piece 1 was prepared by placing a Teflon plate 23 made of Teflon and glass cloth and having a thickness of 0.8 mm or less and a 200 mm square stainless steel between an upper mold 21 and a lower mold 22 of a heating press 2 as shown in FIG. It is sandwiched with a mirror surface plate 24 made of a plate, the pressurizing pressure is 75 kg / cm ² , the temperature of the lower mold is increased, and the heating temperature by the upper mold 21 is changed variously as shown in Table 1, and the pressing time is changed. As shown in Table 1, various hot pressing was performed.

The test piece after the hot pressing was taken out by peeling it from the Teflon plate 23 and the mirror-finished plate 24, and was taken at room temperature for 1
After standing for 2 hours, the thickness of the portion marked with the thickness measurement point was measured. Then, the reduction rate of the thickness of the test piece after hot pressing was calculated by the following calculation method. Reduction rate of thickness = [(A′−A) / A ′] × 100 However, in the formula, A ′ represents the five-point average thickness of the test piece before hot pressing, and A is the test piece after hot pressing. The five-point average thickness is shown. The results are shown in Table 1.

Further, the obtained propylene resin foam was subjected to extrusion lamination to prepare a foam in which a skin material made of vinyl chloride resin was laminated on one surface. The sag condition of the obtained foam with a skin material was evaluated. The results are also shown in Table 2.

The obtained foam with skin material was supplied to a stamping mold to perform stamping molding to obtain an automobile ceiling material. The appearance of the obtained automobile ceiling material was observed and its surface condition was evaluated. The results are also shown in Table 2.

Comparative Example From the top and bottom of the unfoamed sheet, 1 to 3-4Mr of ionizing radiation was applied.
A foaming ratio of 15 was obtained in the same manner as in the example except that an unfoamed sheet that was crosslinked by irradiation only once was used.
A propylene resin foam having a thickness of 3 mm was obtained.

With respect to the obtained propylene-based resin foams, the reduction rate of the thickness after hot pressing was measured in the same manner as in Examples, and the evaluations at the time of hot laminating and stamping molding were performed. The results are also shown in Tables 1 and 2.

[0032]

[Table 1]

[0033]

[Table 2]

As is clear from Table 1 and Table 2, in the case of the examples, bubbles are not collapsed and sagging does not occur during heat lamination or extrusion lamination, and unevenness is generated on the surface during stamping molding. It never happens. On the other hand, in the case of the comparative example, air bubbles are crushed as a whole at the time of thermal lamination or extrusion lamination, and sagging occurs,
In addition, unevenness was generated on the surface during stamping molding.

[0035]

EFFECTS OF THE INVENTION Since the propylene-based foam of the present invention has the above-mentioned constitution, when it is used as a core material to be secondarily processed into an interior material for a vehicle, it causes a sag or a surface. No unevenness is generated.

[0036]

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a relationship between a pressure applied to a foam under a predetermined condition and a thickness reduction rate.

FIG. 2 is an explanatory diagram showing a relationship between a compression rate and a compression strength when a foam is compressed.

FIG. 3 is a plan view showing a test piece of the propylene-based foam of the present invention.

FIG. 4 is a plan view showing a state of hot pressing a test piece of the propylene-based foam of the present invention.

[Explanation of symbols]

 1 Test piece 2 Heating press 21 Upper mold 22 Lower mold 23 Teflon plate 24 Mirror surface plate

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Claims (1)

[Claims] 1. A test piece having a thickness of 2 to 8 mm is heated by a heating press machine so that one surface has a temperature of 200 to 220 ° C., the other surface has a normal temperature, a pressing force of 60 to 80 kgf / cm ² , and a pressing time of 2
The reduction rate of the thickness at room temperature after pressing under the condition of 0 second to 1 minute is 40% or less, and the compressive strength at 50% compression is 2.0 kg / cm ² or less. A characteristic propylene resin foam.