JPH10157028A - High pressure molding sheet - Google Patents

Abstract

(57) [Abstract] [Problem] Excellent in heat resistance and high-pressure moldability such as injection molding,
Further, a high-pressure molding sheet excellent in flexibility (foamability) and resistance to compression at room temperature is provided. A resin mixture 1 comprising 40 to 90% by weight of a propylene-based resin and 60 to 10% by weight of an ethylene-based resin.
A sheet for high-pressure molding, wherein a propylene-based resin sheet is laminated on one surface of a foamed sheet comprising 00 parts by weight and 5 to 50 parts by weight of an inorganic compound and having a gel fraction of 45 to 70%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to stamping molding,
The present invention relates to a high-pressure molding sheet used for high-pressure molding such as injection molding.

[0002]

2. Description of the Related Art As a vehicle interior material such as a ceiling, a door and an instrument panel, a propylene-based resin foam sheet having excellent heat resistance is generally used. The propylene-based resin foam sheet is formed into a desired shape by stamping molding or the like, but in recent years, the unevenness of the shape of the door, instrument panel, and the like has become larger, and particularly in the case of an armrest having a larger unevenness, the foamed sheet has a larger shape. The expansion rate increases, and the foamed sheet may be cut. In general, hot stamping molding is performed after supplying an aggregate resin made of a thermoplastic resin to a foam sheet in which a skin material is laminated. At this time, the aggregate resin partially enters or enters the foam sheet. In many cases, a good molded product cannot be obtained because the foamed sheet is cut by the heat of the aggregate resin.
Thus, stamping molding requires both heat resistance and high-temperature elongation.

[0003] molding pressure of conventional stamping as described above is a 40~60kg / cm ^2, recently it has been studied molding method according molding pressure 100 kg / cm ² or more high-pressure stamping molding or injection molding or the like Therefore, a foam having more excellent heat resistance is required. Also, depending on the molded body, there are some places where the foam is not used,
The aggregate resin must have a high molecular weight in order to maintain the strength of that portion. When the aggregate resin has a high molecular weight, the heat resistance and pressure resistance during stamping molding are improved, but the resin does not easily flow, and it is necessary to increase the molding pressure, and the heat of the aggregate resin easily deteriorates the foam. Therefore, also in this case, a foam having excellent heat resistance is required.

[0004] As a sheet used for stamping molding or the like, for example, Japanese Utility Model Publication No. 5-4190 discloses an aggregate resin made of a thermoplastic resin laminated on one surface of a foamed propylene resin sheet having a gel fraction of 46% or more. A sheet is illustrated. However, in the conventional stamping molding, a good molded body was obtained from this sheet.
In the case of very high injection molding of 0 to 500 kg / cm ² ,
In order to reduce the thickness of the molded article to a desired thickness, it is necessary to reduce the foaming ratio, or to increase the thickness of the foam sheet before molding. There is a problem that the cost increases when the thickness is increased.

[0005]

An object of the present invention is to provide a sheet for high-pressure molding excellent in heat resistance and high-pressure moldability such as injection molding, and also excellent in flexibility (foamability) and resistance to compression at room temperature. Is to provide.

[0006]

The high-pressure molding sheet of the present invention comprises 100 parts by weight of a resin mixture composed of 40 to 90% by weight of a propylene resin and 60 to 10% by weight of an ethylene resin, and 5 to 50 parts by weight of an inorganic compound. Gel fraction of 45
A propylene-based resin sheet is laminated on one side of a 70% foam sheet.

The propylene resin used in the present invention includes a propylene homopolymer, a block copolymer with an α-olefin containing propylene as a main component, a random copolymer and a terpolymer. These may be used alone or in combination of two or more. Examples of the α-olefin include ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene and the like. When the melt index (hereinafter referred to as MI) of the propylene-based resin is small, it is difficult to form a sheet and the sheet surface is rough, and when it is large, heat resistance and high-temperature elongation tend to decrease, so that moldability tends to decrease. It is preferably from 0.3 to 10 g / 10 min, more preferably from 0.4 to 3 g / 10 min. The above MI is a value measured according to JIS K 7210, and the measurement conditions are a temperature of 230 ° C. and a load of 2.16 kgf.

The ethylene resin used in the present invention includes, for example, low density polyethylene, medium density polyethylene,
Examples include ethylene homopolymers such as high-density polyethylene, linear low-density polyethylene, and branched low-density polyethylene, and copolymers with α-olefins containing ethylene as a main component, and have excellent high-temperature elongation. In terms of point, linear low density polyethylene is preferred. These may be used alone or in combination of two or more. Examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene and the like. When the MI of the ethylene-based resin is small, it is difficult to form a sheet and the sheet surface is rough, and when the MI is large, the heat resistance and high-temperature elongation tend to be low, so that the moldability tends to be low, so that 0.5 to ²⁰ g / cm ^2. And more preferably ² to 15 g / cm ² . MI above
Is a value measured in accordance with JIS K 7210,
The measurement conditions are a temperature of 190 ° C. and a load of 2.16 kgf.

The foamed sheet used in the present invention comprises a resin mixture comprising the above-mentioned propylene resin and ethylene resin and an inorganic compound.

When the amount of the propylene-based resin in the above resin mixture is reduced, the heat resistance and the high-temperature elongation are reduced, so that the moldability is reduced. Since the thickness tends not to recover when an impact is applied, the thickness is 40 to 90% by weight. The ethylene resin is mixed with the propylene resin in order to improve resistance to compression at room temperature, and the amount of the ethylene resin is 60 to 10% by weight.

Examples of the inorganic compound include talc,
Examples thereof include silicic acid, calcium carbonate, aluminum hydroxide, and magnesium hydroxide, which may be used alone or in combination of two or more. When the amount of the inorganic compound is small, the heat resistance and pressure resistance are not improved, and when the amount is large, the foaming property tends to be reduced.
It is 5 to 50 parts by weight, preferably 10 to 40 parts by weight based on parts by weight. The inorganic compound is preferably subjected to a surface treatment by stirring and dispersion processing with stearic acid, a coupling agent or the like in order to improve dispersibility.

As a method for obtaining the foamed sheet, any conventionally known method can be adopted. For example, a thermally decomposable foaming agent, a crosslinking assistant, an antioxidant, a pigment, etc. Additives, extruder, melt-kneading in a conventionally known kneading device such as a roll, then molded into a sheet below the decomposition temperature of the pyrolysis type foaming agent,
A method in which crosslinking is performed by irradiation with ionizing radiation or the like, followed by heating and foaming may be used.

The thermal decomposition type blowing agent is not particularly limited as long as it has a decomposition temperature higher than the melting temperature of the resin mixture. For example, azodicarbonamide, hydrazodicarbonamide, azodicarboxylic acid amide, Barium dicarboxylate, dinitrosopentaethylenetetramine, nitrosoguanidine, p, p'-oxybisbenzenesulfonyl semicarbazide, trihydrazine symmetric triazine, bisbenzenesulfonylhydrazide barium azodicarboxylate, azobisisobutyronitrile, toluenesulfonyl Hydrazide and the like may be mentioned, and these may be used alone or in combination of two or more. In general, the amount of the pyrolytic foaming agent to be added is preferably 1 to 50 parts by weight, more preferably 1 to 30 parts by weight, based on 100 parts by weight of the resin mixture, and is adjusted according to a desired expansion ratio.

Examples of the crosslinking aid include divinylbenzene, 1,6-hexanediol dimethacrylate,
1,9-nonanediol di (meth) acrylate, 1,
10-decanediol di (meth) acrylate, divinylnaphthalene, vinyltoluene, trimethylolpropane trimethacrylate, triallyl trimellitate, triallyl cyanurate, etc., and these may be used alone or in combination of two or more. You may. In general, the amount of the crosslinking aid added is 0.1 to 100 parts by weight of the resin mixture.
It is preferably 5 to 30 parts by weight, more preferably 2 to 15 parts by weight, and is adjusted according to a desired gel fraction.

The ionizing radiation includes, for example, electron beams, α-rays, β-rays, γ-rays and the like. When the irradiation amount of the ionizing radiation is small, crosslinking does not proceed, and when it is large, decomposition tends to proceed simultaneously with crosslinking, so that a desired gel fraction tends to be hardly obtained.
And is adjusted according to the desired gel fraction.

When the gel fraction of the foamed sheet is small, the heat resistance is reduced, and when the gel fraction is large, a desired expansion ratio is hardly obtained, and bubbles tend to be non-uniform.
70%, preferably 5% in consideration of stability during foaming.
0 to 65%. First, about 100 mg of a sample was precisely weighed in the thickness direction, and the gel fraction was measured.
After being immersed in 100 ml of xylene at 24 ° C. for 24 hours, the mixture is filtered through a 200-mesh stainless steel wire gauze, and the insoluble portion of the wire gauze is vacuum-dried. Next, the weight of the insoluble portion is precisely weighed, and the gel fraction is calculated as a percentage by the following formula. Gel fraction = [(weight of insoluble portion−weight of inorganic compound) /
Sample weight] × 100 The weight of the inorganic compound is determined from the weight remaining after insoluble matter is heated to 800 ° C. and incinerated.

The cross-linking may be carried out by adding a chemical cross-linking agent in advance instead of the above-mentioned method of irradiating with ionizing radiation. Examples of the chemical crosslinking agent include isobutyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane,
1,3-bis (t-butylperoxyisopropyl) benzene, t-butylcumyl peroxide, di-tert-butyl peroxide, t-butylperoxybenzoate, cyclohexane peroxide, 1,1-bis (t
-Butylperoxy) cyclohexane, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 2,2-bis (t-butylperoxy)
Octane, n-butyl-4,4-bis (t-butylperoxy) berrate, benzoyl peroxide, cumylperoxyneodecanate, 2,5-dimethyl-2,
5-di (benzoylperoxy) hexane, t-butylperoxyisopropyl carbonate, t-butylperoxyallylcarbonate, -butylperoxyacetate, 2,2-bis (t-butylperoxy) butane,
Examples thereof include di-t-butylperoxyisophthalate and t-butylperoxymaleic acid, which may be used alone or in combination of two or more. The amount of the chemical crosslinking agent is not particularly limited, but is generally preferably 1 to 5 parts by weight based on 100 parts by weight of the resin mixture, and is adjusted according to a desired gel fraction.

The propylene-based resin sheet used in the present invention is made of the above-mentioned propylene-based resin, and may be blended with the above-mentioned ethylene-based resin. Since the heat resistance tends to decrease as the amount of the ethylene-based resin increases, the amount is preferably less than 20% by weight. Further, if necessary, an inorganic compound such as talc, silicic acid, or calcium carbonate may be added.

The propylene resin sheet may be crosslinked in the same manner as described above. The gel fraction at that time is 70% or less because the elastic modulus and the high-temperature elongation tend to decrease as the gel fraction increases, preferably 10 to 70% in view of heat resistance, more preferably 20 to 40%. is there.

When crosslinking is performed, it is preferable to add a crosslinking aid. As the cross-linking aid, the same ones as described above can be used.When the amount of addition is small, it becomes difficult to obtain a desired degree of cross-linking, and when the amount is large, the compatibility with the propylene-based resin is reduced, Therefore, the amount is preferably 0.5 to 10 parts by weight, more preferably 1 to 5 parts by weight, based on 100 parts by weight of the propylene resin.

The thickness of the propylene-based resin sheet is not particularly limited, but when it is thin, the heat resistance during stamping tends to be low, and when it is thick, the elongation tends to be low. Is 10
0 to 300 μm.

The high-pressure molding sheet of the present invention is obtained by laminating the above-mentioned foamed sheet and propylene-based resin sheet, or by laminating a resin composition constituting each layer and then foaming. The method of lamination can be any conventionally known method,
For example, a method of melting and laminating the surfaces of a foamed sheet and a propylene-based resin sheet with an infrared heater or the like, a method of co-extruding and laminating a resin composition constituting each layer, and a method of simultaneously extruding a resin composition constituting each layer. A method for laminating, a method for laminating a propylene-based resin sheet in a molten state on an unfoamed sheet made of a resin composition constituting a foamed sheet, a method for laminating a propylene-based resin sheet in a molten state on a foamed sheet, and the like are exemplified.

When the sheet for high-pressure molding of the present invention is used for a vehicle interior material or the like, a skin material is generally laminated on the foam sheet side with an adhesive or the like. As the skin material, any conventionally known materials can be used.For example, cloth materials made of natural or artificial fibers, vinyl chloride resin sheets, thermoplastic elastomer sheets, leather, acrylonitrile-butadiene-styrene copolymer and vinyl chloride resin And the like. Among them, a vinyl chloride resin sheet is preferred in that it has excellent moldability and is low in cost.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Hereinafter, the following compounds were used. PE copolymer 1: a propylene-ethylene random copolymer having an MI of 1.8 g / 10 minutes and an ethylene content of 3.6% by weight PE copolymer 2: an MI of 2.4 g / 10 minutes Propylene-ethylene random copolymer having an ethylene content of 4.8% by weight PE copolymer 3: propylene-ethylene random copolymer having an MI of 2.8 g / 10 minutes and an ethylene content of 3.4% by weight Polymer LLDPE1: MI 6.0 g / 10 min, density 0.9
20 g / cm ³ linear low density polyethylene LLDPE2: MI 2.0 g / 10 min, density 0.9
20 g / cm ³ linear low density polyethylene LLDPE3: MI 8.0 g / 10 min, density 0.9
20 g / cm ³ linear low density polyethylene 1,10-DD: 1,10-decanediol dimethacrylate

【Example】

(Example 1, Comparative Examples 1-4) A predetermined amount of P-
E copolymers 1-3, LLDPE1-3, aluminum hydroxide (trade name “Heidilite H-3, manufactured by Showa Denko KK”)
2)), the resin compositions (a) and (b) comprising 1,10-DD and azodicarbonamide were melt-kneaded in different extruders, respectively, extruded simultaneously at a temperature lower than the decomposition temperature of azodicarbonamide, and laminated. An unfoamed sheet having the predetermined thickness and layer ratio shown in FIG. 2 was formed. 800 kv for the unfoamed sheet
4Mrad in the same amount from each side
, And foamed in a hot-air foaming furnace at 280 ° C. to obtain a foamed sheet.

(Embodiment 2) A predetermined amount of PE shown in Table 1
Copolymers 1-2, LLDPE1-2, aluminum hydroxide (trade name "Heidilite H-32", manufactured by Showa Denko KK),
The resin composition (a) composed of 1,10-DD and azodicarbonamide is melt-kneaded with an extruder and extruded simultaneously at a temperature lower than the decomposition temperature of azodicarbonamide to obtain an unfoamed sheet having a predetermined thickness shown in Table 2. Formed. The unfoamed sheet was irradiated with a predetermined amount of an electron beam of 800 kv shown in Table 2 from both sides to perform crosslinking, and then foamed in a hot-air foaming furnace at 280 ° C. PE copolymer 3, L
The resin composition (b) composed of LDPE3 and 1,10-DD was laminated to a thickness of 0.02 mm to obtain a foamed sheet.

Layer A comprising (a) of the obtained foamed sheet
The gel fraction, thickness, expansion ratio, and gel fraction and thickness of layer B composed of (b) were as shown in Table 2.

The resulting foamed sheet was evaluated for flexibility and resistance to compression at room temperature as follows. (Flexibility) When the expansion ratio of A was in the range of 15 ± 2 cc / g, the flexibility was evaluated as ○, and when it was not within the range, as ×, the results are shown in Table 2.

(Resistance to compression at room temperature) Temperature 23
Under a condition of 70 ° C. and a relative humidity of 70%, the foamed sheet was subjected to finger pressure from the side A for 1 second so as to have a depth of 1 mm. After that, let it stand and observe the state of recovery.
Those that did not recover immediately were rated as x, and the results are shown in Table 2.

300 × 300 m from the obtained foamed sheet
Five samples of each m were prepared, and the stamping formability of each sample was evaluated by the following method. (Evaluation of stamping formability) diameter 100 mm x depth 3
The sample is placed on the concave cup of 0 mm such that B is on the inner side of the concave cup, and 20 g of 210 ° C. molten polypropylene (MI = 15 g / 10 min) is supplied to the B side to match the concave cup. 210kgf with convex shape
Hot stamping molding was performed by embossing at a pressure of / cm ² . Table 1 shows the number of the obtained molded articles in which the polypropylene did not partially enter the foamed sheet or was not partially cut.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

According to the high-pressure molding sheet of the present invention, since the inorganic compound is added to the resin mixture constituting the foamed sheet, the specific heat is higher than that of the resin mixture alone,
Cutting of the resin mixture due to thermal deterioration and an increase in molding temperature are unlikely to occur, and the resin mixture is excellent in heat resistance and rigidity.
In addition, since the propylene-based resin sheet is laminated on the foam sheet, the specific heat of the high-pressure molding sheet is higher than that of the foam sheet, and the sheet has excellent heat resistance during stamping molding and the like. Furthermore, it is excellent in flexibility and resistance to compression at room temperature.

Claims (1)

[Claims] 1. A resin mixture 1 comprising 40 to 90% by weight of a propylene resin and 60 to 10% by weight of an ethylene resin.
A sheet for high-pressure molding, wherein a propylene-based resin sheet is laminated on one surface of a foamed sheet comprising 00 parts by weight and 5 to 50 parts by weight of an inorganic compound and having a gel fraction of 45 to 70%.