JP2003041040A - Foamable polypropylene resin composition, method for producing molded ceiling member using the same and molded ceiling member used for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive molded ceiling member which is used for an automobile, has excellent fogging resistance, a light weight, high rigidity, excellent dimensional stability, excellent acoustic characteristics, excellent molding environmental property, excellent designing property, excellent attaching workability, excellent recyclability, and excellent surface skin touch, can freely be molded. SOLUTION: This foamable polypropylene resin composition comprises a polypropylene resin, glass fibers, a radical-producing agent, a cross-linking agent and a foaming agent in a specified ratio. The cross-linking agent is a polymethylolalkane-poly(meth)acrylate and/or a polymethylolalcohol-poly(meth) acrylate.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a foamable polypropylene resin composition, a method for producing a molded ceiling material for automobiles using the same, and a molded ceiling material for automobiles. More specifically, it is lightweight and has rigidity. The present invention relates to a foamable polypropylene resin composition capable of providing a molded ceiling material for automobiles made of a recyclable polypropylene foam molded article, a method for producing the molded ceiling material for automobiles, and the molded ceiling material.

[0002]

BACKGROUND OF THE INVENTION Polypropylene resin is widely used as an interior / exterior material for automobiles because it has an excellent balance between rigidity and impact resistance, heat resistance and moldability. Polypropylene resin is also used in automobile ceiling materials. Among automobile ceiling materials, a resin used as a strength member for a molded ceiling material of a fitting type is required to have heat resistance and rigidity so that it does not hang down under its own weight even in a high temperature in a room in the summer. Therefore, glass fiber-blended polypropylene is usually used for the above applications.

For automobile materials, strength and weight reduction are required at the same time. To reduce the weight of the resin material, it is possible to use a resin foam. To produce a glass fiber-blended polypropylene foam, a method of producing a glass fiber-blended polypropylene foam by melting a polypropylene composition blended with a foaming agent and glass fibers with an injection molding machine and injection-molding it into a mold. Then, two methods are conceivable: a polypropylene composition containing a foaming agent and glass fibers is melted by a sheet molding machine and extrusion-molded to produce a foamed sheet. For example, JP-A-7-9462 and JP-A-7-16933.
No. 2000-239433, 2000-2
The foaming techniques described in Japanese Patent Laid-Open No. 39531, JP-A-2000-255270 and the like are techniques relating to the former method. On the other hand, JP-A-5-193039 and JP-A-8-
The foaming technique described in the publication of 207068 is a technique relating to the latter method.

When a glass fiber-blended foamed sheet is manufactured by the extrusion method, it is possible to foam the foamed sheet at the same time as the sheet molding. However, since polypropylene has a low melt tension, most of it has a cell diameter of open cells when foamed as it is. Only large foams can be produced. Further, the above foamed sheet is stamped or vacuum / pneumatically molded to form a ceiling material having a final shape, but a foam obtained by a usual method is inferior in secondary moldability.

For these reasons, generally, in the process for producing a polypropylene foam, there has been proposed a method for improving the melt tension by a crosslinking treatment before the foaming process. However, unlike polyethylene, polypropylene does not crosslink with normal peroxide, so it has been proposed to blend a polypropylene with a crosslinking aid, irradiate it with an electron beam to crosslink, and then heat the sheet to foam it. (JP-A-8-207068) To manufacture a ceiling material from a glass fiber-blended polypropylene foam sheet, a cushion material is optionally interposed in the polypropylene foam sheet, and a skin material is provided on the surface of the foam sheet or the cushion material. It is necessary to attach them to form a multi-layered structure, and then form them into a predetermined shape.

For example, JP-A-5-70621 discloses a foamable sheet-forming composition containing a propylene-based resin consisting of a propylene / α-olefin block copolymer, a radical generator, a crosslinking aid and a foaming agent. The foaming agent is formed into a sheet at a temperature at which the foaming agent does not decompose, and a skin material is laminated on one surface of the obtained foamable sheet to be integrated, and then the foamable sheet is irradiated with ionizing radiation to obtain the propylene resin. There has been proposed a method for producing a foam-molded article, which comprises cross-linking and then heating the foamable sheet to foam it and simultaneously molding the foamed sheet.

However, when triallyl isocyanurate (TAIC) which has been conventionally used as a crosslinking aid is used, the fogging resistance is not at a sufficiently satisfactory level. Here, "fogging" refers to a phenomenon in which when the molded ceiling material receives heat, volatile components are generated from the sheet and condensed on the inner surfaces of the windshield and window glass of the automobile to cause fogging.

Therefore, it is desired to develop a foamable polypropylene resin composition capable of producing a molded ceiling material for automobiles having excellent fogging resistance, a method for producing the molded ceiling material for automobiles, and the molded ceiling material for automobiles. There is.

[0009]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the problems associated with the prior art as described above, and is a foamable polypropylene resin composition capable of producing a molded ceiling material for automobiles having excellent fogging resistance. An object of the present invention is to provide a method for producing the molded ceiling material for automobiles and the molded ceiling material for automobiles.

Another object of the present invention is to provide a foamable polypropylene resin composition capable of producing a molded ceiling material for automobiles having excellent heat resistance and heat resistance, a method for producing the molded ceiling material for automobiles, and the automobile. To provide a molded ceiling material for use. Still another object of the present invention is to provide a lightweight molded ceiling material for automobiles and a method for manufacturing the same.

Still another object of the present invention is to provide a molded ceiling material for automobiles having an excellent appearance and a method for producing the same.

[0012]

SUMMARY OF THE INVENTION The expandable polypropylene resin composition according to the present invention comprises 75 to 95 parts by weight of a propylene resin (A), 5 to 25 parts by weight of a glass fiber (B) [components (A) and (B). The total amount of the radical generator (C) is 0.01 to 0 relative to 100 parts by weight of the total amount of the propylene resin (A) and the glass fiber (B). 0.1 parts by weight, 0.1 to 5 of the crosslinking aid (D)
In the composition for forming a foamable sheet, which comprises 2 parts by weight and 2 parts by weight of the foaming agent (E), the crosslinking aid (D) is polymethylolalkane poly (meth) acrylates and / or polymethylol. Characterized by alcohol and poly (meth) acrylates.

The propylene resin (A) is a propylene / α-olefin block copolymer (F) 15-85.
It is preferable that the resin composition is composed of 85% by weight and 85 to 15% by weight of propylene homopolymer (G). The propylene / α-olefin block copolymer (F) is
The ethylene / propylene copolymer segment is contained in an amount of 2% by weight or more and less than 20% by weight, the crystalline polypropylene segment is contained in an amount of more than 80% by weight and 98% by weight or less, and the ethylene content is 2 mol% or more. It is less than 20 mol% and the intrinsic viscosity [η] of the ethylene / propylene copolymer segment measured in decalin at 135 ° C. is 2
It is preferably a propylene / ethylene block copolymer (F-1) in the range of ˜8 dl / g.

The melt flow rate (ASTM D-1238, L, 230 ° C., 2.16 kg load) of the propylene resin (A) is
It is preferably 0.5 to 20 g / 10 minutes. The glass fiber (B) has an average fiber diameter of 5 to 20 μm,
The fiber length is preferably 0.1 to 20 mm. The glass fiber (B) is preferably a glass fiber coated with modified polypropylene obtained by graft-polymerizing an unsaturated carboxylic acid or its derivative.

The method for producing a molded ceiling material for automobiles according to the present invention comprises the above-mentioned propylene resin (A), glass fiber (B), radical generator (C), crosslinking aid (D) and foaming agent ( The expandable polypropylene resin composition containing E) was molded into a sheet at a temperature at which the foaming agent (E) was not decomposed, and one side of the resulting expandable sheet was lined with a backing material to be integrated. Then, the foamable sheet is irradiated with ionizing radiation to crosslink the propylene resin (A),
Next, after the foamable sheet is heated to be foamed, a molded ceiling material for automobiles comprising a step of placing a skin material on the surface of the foamed sheet and press-molding the foamed sheet before the foamed sheet is cooled and solidified. The method is characterized in that polymethylolalkane / poly (meth) acrylates and / or polymethylolalcohol / poly (meth) acrylates are used as the crosslinking aid (D).

The dose of the ionizing radiation is 2 to 10 KG.
It is preferably y. The gel fraction of the foamable sheet after irradiation with the ionizing radiation is preferably 1 to 10% by weight based on the weight of the propylene resin (A). A molded ceiling material for an automobile according to the present invention is characterized by being a molded ceiling material obtained by the above-described method for producing a molded ceiling material for an automobile according to the present invention.

[0017]

DETAILED DESCRIPTION OF THE INVENTION The expandable polypropylene resin composition according to the present invention, the method for producing a molded ceiling material for automobiles using the same, and the molded ceiling material for automobiles will be specifically described. Expandable polypropylene resin composition First, the expandable polypropylene resin composition according to the present invention will be described.

The expandable polypropylene resin composition according to the present invention contains at least a propylene resin (A), a glass fiber (B), a radical generator (C), a crosslinking aid (D) and a foaming agent (E). In addition, it contains a heat-resistant stabilizer and, in some cases, an additive such as a coloring agent. [Propylene-based resin (A)] As the propylene-based resin (A) used in the present invention, a polymer containing a propylene (co) polymer as a main component or a resin composition can be used.

The propylene (co) polymer is a propylene homopolymer or a copolymer of propylene and ethylene or an α-olefin having 4 to 20 carbon atoms. Here, as the α-olefin having 4 to 20 carbon atoms, specifically, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-
Dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene and the like can be mentioned. The α-olefin copolymerized with propylene is preferably ethylene or an α-olefin having 4 to 10 carbon atoms.

These α-olefins may form a random copolymer with propylene or may form a block copolymer. The constituent unit derived from these α-olefins may be contained in the propylene / α-olefin copolymer in an amount of 40 mol% or less, preferably 20 mol% or less. Among propylene copolymers, propylene, which has an excellent balance between rigidity and impact resistance,
Ethylene block copolymers are preferred.

The propylene / α-olefin block copolymer may be a so-called non-polymer blend type (that is, chemical blend type) propylene / α-olefin block copolymer, or may be a polymer blend type, that is, propylene / α-olefin block copolymer. It may be a propylene resin composition comprising an α-olefin block copolymer (F) and a propylene homopolymer (G).

In the present invention, the propylene resin (A)
Specifically, the propylene / ethylene block copolymer (F-1) preferably used as the compound has an intrinsic viscosity [η] measured in decalin at 135 ° C. of preferably 2 to 8 dl.
/ G, particularly preferably 3 to 6 dl / g ethylene.
A propylene / ethylene block copolymer containing a propylene copolymer segment in an amount of 2% by weight or more and less than 20% by weight and a crystalline polypropylene segment in an amount of more than 80% by weight and 98% by weight or less. The ethylene / propylene copolymer segment has low crystallinity or rubber-like properties.

The content of the ethylene / propylene copolymer segment and the content of the crystalline polypropylene segment are determined as follows. That is, a sample propylene / ethylene block copolymer (F-1) is put into n-decane, dissolved by heating, and then allowed to cool. The crystalline component of the precipitated sample is stirred and separated into a soluble component and an insoluble component. Acetone, which is a poor solvent, was added to the separated soluble fraction to precipitate a dissolved polymer component, which was then filtered, and the dry weight of the precipitate was defined as the ethylene / propylene copolymer segment content. The dry weight of the insoluble component is determined as the crystalline polypropylene segment content.

The content of the structural unit derived from ethylene (ethylene content) in the propylene / ethylene block copolymer (F-1) is preferably 2 mol% or more and less than 20 mol%. Propylene / ethylene block copolymer (F-1) having an ethylene content within the above range
Is used as the propylene-based resin (A), crosslinking of the propylene-based resin due to ionizing radiation proceeds to an appropriate degree of crosslinking, so that heating can mainly cause foaming in the thickness direction of the sheet, and a foaming ratio of 5 to 10 times. And the thickness is 3m
It is possible to obtain a foamable polypropylene resin composition capable of providing a foamed sheet having a length of m or more.

In the present invention, the ethylene / propylene copolymer segment constituting the propylene / ethylene block copolymer (F-1) is indispensable for obtaining a uniform foam. The ethylene content in the propylene / ethylene block copolymer (F-1) is determined as follows.

That is, a film or sheet having a thickness of 200 to 300 μm is produced by a press molding machine set at a temperature of 180 ° C. Using this film or sheet as a sample, each peak attributed to the polypropylene chain is measured using an infrared spectrophotometer, and the composition is calculated from a calibration curve obtained in advance to determine the ethylene content. The propylene / ethylene block copolymer (F-1)
Can be obtained by polymerizing olefins in the presence of a stereoregular catalyst, preferably a catalyst consisting of a transition metal component with a support and an organoaluminum compound. For example, homopolymerization of propylene is first carried out, then random copolymerization of propylene and ethylene is carried out in the same polymerization system, and if necessary, homopolymerization of ethylene is carried out to obtain a propylene / ethylene block copolymer. Obtainable. The block copolymer obtained by this method is a so-called non-polymer blend type or chemical blend type copolymer. That is, the crystalline polypropylene, the ethylene / propylene random copolymer, and the crystalline polyethylene are directly blended in the polymerization reaction system by the multistage polymerization method. This specific manufacturing method is described in detail in Japanese Patent Application Laid-Open No. 52-98045 and Japanese Patent Publication No. 57-26613.

In the propylene resin composition comprising the propylene / ethylene block copolymer (F-1) and the propylene homopolymer (G), the propylene / ethylene block copolymer (F-1) and the propylene homopolymer are used. 100 parts by weight of the total amount of (G) and propylene
The ethylene block copolymer (F-1) is used in a proportion of 15 to 85 parts by weight, preferably 30 to 80 parts by weight, more preferably 40 to 70 parts by weight, and the propylene homopolymer (G) is 85 parts by weight. ~ 15 parts by weight, preferably 70-2
It is used in an amount of 0 part by weight, more preferably 60 to 30 parts by weight.

The propylene homopolymer (G) used together with the propylene / ethylene block copolymer (F-1) has a melt flow rate (MFR; ASTM D).
-1238, L, 230 ℃, 2.16kg load) 0.5-20g / 10
Min, preferably 1 to 10 g / 10 min. The propylene-based resin (A) used in the present invention, that is, the propylene / α-olefin block copolymer and the propylene resin composition, has a melt flow rate (MFR; ASTM D-123).
8, L, 230 ℃, 2.16kg load) 0.5 ~ 20g / 10 minutes,
It is preferably 1.0 to 10 g / 10 minutes. When the melt flow rate of the propylene-based resin (A) is within the above range, kneading and extrusion are easy, and high mechanical strength can be maintained with a small amount of the crosslinking aid used, which is suitable as a material for ceiling materials. Is.

The propylene resin (A) as described above is
It is used in a proportion of 75 to 95 parts by weight, preferably 80 to 90 parts by weight, based on 100 parts by weight of the total amount of the propylene resin (A) and the glass fiber (B). [Glass Fiber (B)] The glass fiber (B) used in the present invention has an average fiber diameter of usually 5 to 20 μm, preferably 10 to 15 μm, and a fiber length of 0.1 to 20 mm.
It is preferably 0.3 to 10 mm.

The glass fiber (B) is used in a proportion of 5 to 25 parts by weight, preferably 10 to 20 parts by weight, based on 100 parts by weight of the total amount of the propylene resin (A) and the glass fiber (B). To be When the glass fiber (B) is used in the above proportion, it is possible to obtain a foamable sheet which can provide a molded ceiling material for automobiles having high rigidity, heat resistance and dimensional stability.

Molded ceiling materials for automobiles have a temperature of 90 ° C. to −40.
It is required that the temperature does not sag by 10 mm or more in the wet / cool heat test at 0 ° C. This requirement is satisfied by using the above glass fiber (B). Moreover, conventionally
As a filler to improve rigidity, talc is inexpensive and most commonly used. However, since it is necessary to improve not only the rigidity of the ceiling material but also the heat resistance, the amount of talc used is too large to satisfy those physical properties,
There are drawbacks that the weight of the obtained ceiling material becomes heavy and the foamability of the foamable sheet is lowered. Such drawbacks of talc can be remedied by using the above glass fiber (B).

In the present invention, from the viewpoint of enhancing the adhesiveness between the glass fiber (B) and the propylene resin (A), polypropylene (modified polypropylene) graft-modified with an unsaturated carboxylic acid or a derivative thereof is directly added to the glass fiber. It is desirable to coat or add an appropriate amount to the propylene resin (A). Specific examples of the unsaturated carboxylic acid used for modifying polypropylene include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, crotonic acid, endocis-bicyclo [2,2,1] heptate. Examples include -5-ene-2,3-dicarboxylic acid (Nadic acid ^TM ).

Examples of unsaturated carboxylic acid derivatives include acid halides, esters, amides, imides, anhydrides, and the like. Specifically, maleimide, acrylic acid amide, methacrylic acid amide, glycidyl methacrylate, maleic anhydride. Acid, citraconic anhydride, monomethyl maleate, dimethyl maleate, glycidyl maleate and the like can be mentioned.

These compounds may be used alone or in combination of two or more. Of these, acrylic acid, methacrylic acid, and maleic anhydride are preferable. For example, glass fiber (B) can be impregnated with a modified polypropylene obtained by graft-polymerizing maleic anhydride in a solution state, or can be coated in a molten state. At this time, the amount of the unsaturated carboxylic acid or its derivative grafted onto the polypropylene is 0.01 to 10% by weight, preferably 0.1 to 5% by weight, based on the weight of the modified polypropylene. Further, the modified polypropylene may be a modified polypropylene obtained by highly graft-polymerizing an unsaturated carboxylic acid or a derivative thereof, which is diluted with unmodified polypropylene so as to fall within the above-mentioned graft amount range.

The glass fiber (B) and the propylene resin (A) which have been subjected to such surface treatment have a weight ratio [(B) /
(A)] is preferably mixed in the range of 60/40 to 80/20 to prepare a masterbatch. Especially length 1
A masterbatch having a shape of 0 mm and a diameter of about 3 mm is preferable in terms of mixing with other components when forming the foamable sheet.

[Radical Generator (C)] In the present invention, the radical generator (C) is used to bring the expandable polypropylene resin composition into a crosslinked state. Examples of the radical generator (C) include organic peroxides,
Organic peroxyesters are mainly used, and the decomposition temperature at which the half-life of this radical generator shows 1 minute (min) is preferably higher than the melting point of the propylene resin (A). The half-life of the radical generator (C) is 1
It is practically preferable that the decomposition temperature showing 00 hours (hr) is 40 ° C. or higher.

Specific examples of these organic peroxides and organic peroxyesters include 3,5,5-trimethylhexanoyl peroxide (1), octanoyl peroxide (2), decanoyl peroxide (3) and lauroyl peroxide (4). ), Succinic acid peroxide (5), acetyl peroxide (6), t-butylperoxy (2-ethylhexanoate) (7), m-toluoyl peroxide (8), benzoyl peroxide (9), t-butylperoxy Isobutyrate (10),
1,1-bis (t-butylperoxy) -3,5,5-trimethylcyclohexane (11), 1,1-bis (t-butylperoxy) cyclohexane (12), t-butylperoxymaleic acid (13), t-Butyl peroxylaurate (1
4), t-butylperoxy-3,5,5-trimethylcyclohexanoate (15), cyclohexanone peroxide (16), t-butylperoxyisopropyl carbonate (17), 2,5-dimethyl-2,5-di (Benzoylperoxy) hexane (18), t-butylperoxyacetate (19), 2,2-bis (t-butylperoxy) butane (20), t-butylperoxybenzoate (21),
n-butyl-4,4-bis (t-butylperoxy) valerate (22), di-t-butylperoxyisophthalate (23), methyl ethyl ketone peroxide (24),
α, α'-bis (t-butylperoxyisopropyl) benzene (25), dicumyl peroxide (26), 2,5-dimethyl-2,5-di (t-butylperoxy) hexane (2
7), t-butyl cumyl peroxide (28), diisopropylbenzene hydroperoxide (29), di-t-butyl peroxide (30), p-menthane hydroperoxide (31), 2,5-dimethyl-2,5- Di (t-butylperoxy) hexyne-3 (32), 1,1,3,3-tetramethylbutylhydroperoxide (33), 2,5-dimethylhexane-2,5-dihydroperoxide (34), cumene hydro Examples thereof include peroxide (35) and t-butyl hydroperoxide (36). Of these, the compounds (12) to (36) are particularly preferable.

In the expandable polypropylene resin composition according to the present invention, the radical generator (C) is 0 when the total amount of the polypropylene resin (A) and the glass fiber (B) is 100 parts by weight. It is used in a proportion of 0.01 to 0.1 part by weight. When the amount of the radical generator (C) is within the above range, an appropriate increase in melt viscoelasticity of the propylene resin (A) is achieved, and a foam-molded article having good closed cells is obtained.

[Crosslinking aid (D)] In the present invention, as the crosslinking aid (D) for crosslinking the above-mentioned propylene resin (A), polymethylol polyalkane poly (meth) acrylates and And / or polymethylol alcohol / poly (meth) acrylates are used. Specific examples of the polymethylol polyalkane / poly (meth) acrylates include trimethylolethane trimethacrylate, trimethylolethane triacrylate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, and trimethylolbutane. -Trimethacrylate, trimethylol butane triacrylate, trimethylol ethanol trimethylol butane trimethacrylate, trimethylol ethanol trimethylol butane triacrylate, etc. are mentioned.

Specific examples of the polymethylol alcohol / poly (meth) acrylates include trimethylolmethanol / trimethacrylate, trimethylolmethanol / triacrylate, trimethylolethanol / trimethacrylate, and trimethylolethanol / triacrylate. , Trimethylol propanol / trimethacrylate, trimethylol propanol /
Examples thereof include triacrylate, trimethylol acryloxyethanol / trimethacrylate, and trimethylol acryloxyethanol / triacrylate.

A uniform and mild crosslinking reaction can be expected with the above-mentioned crosslinking aid (D). Furthermore, it is possible to obtain a foamable polypropylene resin composition capable of producing a molded ceiling material for automobiles having excellent fogging resistance. The crosslinking aid (D) is 0.1 to 5 parts by weight, preferably 0.3 to 2 parts by weight, based on 100 parts by weight of the total amount of the polypropylene resin (A) and the glass fiber (B). Used in proportion. When this crosslinking aid (D) is used in the above proportion, the crosslinking reaction of the propylene resin (A) proceeds favorably, the desired degree of crosslinking is obtained, the melt viscoelasticity is sufficiently improved, and the melt tension becomes appropriate. It is preferable because it becomes higher and proper foaming is performed.

[Foaming Agent (E)] The foaming agent (E) used in the present invention is a chemical substance which is a liquid or a solid at room temperature and decomposes by heating to generate a gas, and is a propylene resin (A). There is no particular limitation as long as it has a decomposition temperature equal to or higher than the melting point of As such a foaming agent (E), specifically, azodicarbonamide (ADCA),
Barium azodicarboxylate, N, N'-dinitrosopentamethylenetetramine, 4,4-oxybis (benzenesulfonylhydrazide), diphenylsulfone-3,3-disulfonylhydrazide, p-toluenesulfonyl semicarbazide,
Examples thereof include trihydrazinotriazine, biurea and zinc carbonate. Among these, azodicarbonamide (ADC) which has a large amount of gas generation and whose gas generation end temperature is sufficiently lower than the thermal deterioration start temperature of the propylene resin (A).
A), N, N-dinitrosopentamethylenetetramine and trihydrazinotriazine are particularly preferred.

The blowing agent (E) is 100 in total of the above-mentioned polypropylene resin (A) and glass fiber (B).
It is used in a proportion of 2 to 5 parts by weight with respect to parts by weight. When the amount of the foaming agent (E) used is in the above range, the amount of the generated gas is appropriate, so that it is possible to expand 5 to 10 times in the thickness direction, and the bubbles have a uniform size. , And evenly dispersed. If the degree of cross-linking is increased and the degree of foaming is increased too much, the sheet foams in the three-dimensional direction and cannot be used as a foaming base material for a ceiling.

[Other Components] In the expandable polypropylene resin composition according to the present invention, the propylene resin (A),
In addition to the glass fiber (B), the radical generator (C), the crosslinking aid (D) and the foaming agent, if necessary, additives such as a heat resistance stabilizer and a colorant do not impair the object of the present invention. It can be blended in a range.

For example, when kneading the glass fiber (B), the radical generator (C), the crosslinking aid (D) and the foaming agent (E) together with the propylene resin (A), a phenol having 30 or more carbon atoms is used. When the heat-resistant stabilizer is added to the expandable polypropylene resin composition in an amount of 0.05 to 1% by weight, preferably 0.1 to 0.5% by weight, the generation concentration of polymer radicals is controlled to increase the crosslinking efficiency. Along with the above composition, it is possible to prevent oxidative deterioration during foaming by heating the composition and during thermal processing of the foam, and to enhance the heat aging resistance of the product in use, so a phenolic heat stabilizer. Is preferably used.

Examples of such phenolic heat stabilizers include n-octadecyl-3- (4'-hydroxy-3 ',
5'-di-t-butylphenyl) propionate, 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl)
Butane, 1,3,5-tris (4-t-butyl-3-hydroxy-2,6
-Dimethylbenzyl) -s-triazine-2,4,6- (1H, 3H, 5
H) trione, 1,3,5-trimethyl-2,4,6-tris (3,5-di
-t-Butyl-4-hydroxyphenyl) benzylbenzene, 1,3,5-tris (3,5-di-t-butyl-4'-hydroxybenzyl) -s-triazine-2,4,6- (1H , 3H, 5H) Trion,
Tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane or a mixture of two or more thereof is used.

If the foaming agent (E) is mixed with an additive having a function of preventing secondary aggregation of the foaming agent in advance, the foaming agent (E) is dispersed in the foamable polypropylene resin composition. It is possible to obtain a good foam having improved properties and free of coarse cells. Such additives include metal soaps and surfactants. Specifically, substances that are solid at the kneading temperature, such as metal stearates such as calcium stearate and stearyl monoglyceride, are preferred.

Molded Ceiling Material for Automobiles The molded ceiling material for automobiles according to the present invention is a ceiling material obtained by the production method described below, and one side of a foamable sheet obtained from the foamable polypropylene resin composition as described above. Since the foaming sheet and the backing material are integrated with each other by lining the backing material with the backing material, the backing material exists on one surface of the backing material.

A preferred backing material is, for example, wooly nylon or polyester such as polyethylene terephthalate (PET), syrup, glass cloth and the like, and has a basis weight of 15 to 100 g / m ² , preferably 20 to 80 g / m ² . Examples thereof include breathable non-woven fabrics and woven fabrics, which do not melt when the foaming agent (E) is decomposed.

Further, as the backing material, in order to follow the shape of the mold by a forming process such as drawing, it is preferable to use a material having a large vertical and horizontal elongation and a well-balanced vertical and horizontal stretchability. Further, in the molded ceiling material for automobiles according to the present invention, the skin material is laminated on the surface of the foamed sheet on the opposite side backed by the backing material.

Specific examples of the skin material used in the present invention include non-woven fabrics of polyester, nylon, polypropylene and the like; woven fabrics of polyester, nylon, polypropylene and the like; woven fabrics of natural fibers.
Generally, a polyester non-woven fabric is used. The basis weight of these skin materials is usually 100 to 300 g / m ² .

A composite material obtained by laminating a foam such as polyurethane foam, polyethylene foam or polypropylene foam on these materials can also be used as the skin material. In addition, leather made of vinyl chloride resin, thermoplastic elastomer, etc. is lined with woven fabric, and composite materials made by laminating such leather with foam such as polyurethane foam, polyethylene foam, polypropylene foam, etc. It can be used as a material.

The above-mentioned foamable sheet is in a molten state in a foamed state, is bonded to a woven cloth, a nonwoven cloth, and an open-cell foam by an anchor effect, and is heat-sealed with a polypropylene resin (A). An adhesive is not always necessary, because they are bonded together. Method of manufacturing an automotive molded ceiling material Next, a method for manufacturing an automotive molded roof material according to the present invention.

First, the above-mentioned expandable polypropylene resin composition is molded into a sheet. As a sheet forming method,
Specifically, the above-mentioned, after kneading the expandable polypropylene resin composition according to the present invention with a Brabender or the like, a method of molding into a sheet with a calender roll, a method of forming into a sheet with a press molding machine, and an extruder. A method in which the expandable polypropylene resin composition is kneaded and then formed into a sheet through a T die or an annular die can be employed. Among these, the last method, that is, the method of kneading the composition and then extruding from the T die at a temperature lower than the decomposition temperature of the foaming agent (E) to mold the composition is low in energy consumption and time, The flatness of the sheet and the extruded surface are also favorable, which is preferable.

When the foamable polypropylene resin composition is formed into a sheet, it must be carried out at a temperature at which the foaming agent (E) is not decomposed as described above. Specifically, as the foaming agent (E), azo is used. When using dicarbonamide (ADCA), it is about 160 to 190 ° C, preferably 165-1.
It is preferable to form the expandable polypropylene resin composition into a sheet at 80 ° C.

The unfoamed foamable sheet obtained as described above has a thickness of about 0.5 to 1 mm. Next, on one side of the foamable sheet obtained as described above,
The backing material described above is lined and integrated by a conventionally known method. For example, in the present invention, the expandable polypropylene resin composition is extruded into a sheet shape and passed through a pair of seating rolls immediately after that, and a backing material is passed through the pair of seating rolls, thereby forming a foamable sheet and a backing material. Can be integrated by pressing with a sheeting roll, and such an integration method is preferable because an adhesive is not particularly required.

By backing the backing material on the foamable sheet in this manner, drawdown due to heating and softening of the sheet can be prevented, and the polypropylene resin (A) forming the foamable sheet is used. It is possible to mainly foam in the thickness direction of the sheet, and to obtain a molded product having a foaming ratio of 3 times or more (thickness direction), particularly a molded product having a high foaming ratio of 5 to 10 times (thickness direction).

Next, the foaming sheet, which is lined with the backing material and integrated, is irradiated with ionizing radiation to crosslink the propylene resin (A). As the ionizing radiation, α rays, β rays, γ rays, X rays, electron rays, neutron rays and the like are used. Of these, cobalt-60 gamma rays and electron rays are preferably used. The dose of this ionizing radiation is about 2 to 10 KGy, preferably 3 to 7 KGy.
It is desirable that the irradiation amount is such that the gel fraction, which is an index of the degree of crosslinking of the propylene resin (A), is in the range of 1 to 10% by weight, preferably 3 to 7% by weight. When the dose of ionizing radiation is within the above range, the degree of crosslinking of the propylene-based resin (A) is appropriate, a desired degree of foaming can be obtained, and moreover, the foaming sheet mainly foams in the thickness direction, which is preferable. Further, the trimming waste of the foamed sheet having such a degree of crosslinking can be recycled. For example, this trimming waste can be effectively used by mixing it with an unused resin for automobile molding ceiling material.

Here, the gel fraction, which is an index of the degree of crosslinking of the propylene resin (A), is determined as follows.
That is, 3 samples were placed in a # 100 mesh screen basket.
g, this sample was subjected to extraction treatment with p-xylene for 3 hours using a Soxhlet extractor, the extraction residual rate (xylene insoluble content) was determined, and this xylene insoluble content was taken as the gel fraction.

A polypropylene-based foam molded article is obtained by heating the crosslinkable foamable sheet as described above and molding it into a desired shape. In this case, it is naturally necessary to heat above the decomposition temperature of the foaming agent (E). The following methods are available for heating the foamable sheet to foam it. (1) A method of utilizing radiant heat from a heating element. (2) A method of heating by high frequency induction. (3) A method of heating using an oven. (4) Method of heating with hot air.

Although the foamable sheet mainly foams in the thickness direction, it tends to contract due to heating, and it is necessary to clamp the periphery of the sheet. The foamable sheet is molded when foaming is occurring, or while foaming is nearly complete but the sheet is still plastic. A press molding method is used as a processing method. Next, after foaming the foamable sheet as described above, while the obtained foamed sheet is not cooled and solidified, that is, while in a plastic state, a skin material is placed on the upper surface of the foamed sheet, and The combined ceiling mold is closed, both are laminated and shaped, and shaped.

The mold is provided with a cooling water groove and cooled using a chiller or the like. The clearance between the upper and lower molds is 1 to 2 mm based on the total thickness of the foamed sheet and the skin material.
Smaller size is suitable. By minimizing the clearance at the end of the foamed sheet, the foamed resin is crushed to facilitate trimming. According to the method for producing a molded ceiling material for an automobile according to the present invention, since the skin material is not heated by the heater, there is no change in thickness and appearance,
In particular, even when a fluffy sheet, a velvet-raised sheet or a flocked sheet is used as the skin material, the hair does not fall over and a skin surface having an excellent texture can be obtained.

The molded ceiling material for an automobile according to the present invention, which is obtained as described above and in which the skin material, the foamed sheet and the backing material are laminated in this order, is lightweight and has high rigidity, and the surface condition of the skin material is good. It has excellent texture on the surface of the skin.

[0064]

EFFECTS OF THE INVENTION According to the method for producing a molded ceiling material for an automobile according to the present invention, a propylene resin (A), a glass fiber (B), a radical generator (C), a crosslinking aid (D) and a foaming agent. By using a specific compound as the crosslinking aid (D) in the expandable polypropylene resin composition containing (E), a molded ceiling material for automobiles having excellent fogging resistance can be provided.

That is, the expandable polypropylene resin composition according to the present invention can provide a molded ceiling material for automobiles which is excellent in fogging resistance. Further, according to the method for producing a molded ceiling material for automobiles according to the present invention, the polypropylene-based foam having uniform closed cells and fine closed cells is obtained by heating the foamable sheet after crosslinking the propylene-based resin (A). A molded ceiling material for automobiles, which is a molded product, can be obtained. Moreover, since it is mainly foamed in the thickness direction and the expansion ratio thereof is 5 to 10 times, a lightweight, high-rigidity molded ceiling can be obtained. Furthermore, this molded ceiling material
It is excellent in dimensional stability, acoustic characteristics, molding environment, design, texture of the skin, workability in mounting and recyclability, and it has flexibility in molding and is inexpensive.

Therefore, the molded ceiling material for automobiles according to the present invention is lightweight and has high rigidity, and is excellent in dimensional stability, acoustic characteristics, molding environment property, designability, installation workability, recyclability and texture of the skin surface. Moreover, there is flexibility in molding and it is inexpensive. That is, the expandable polypropylene resin composition according to the present invention can provide a molded ceiling material for automobiles that exhibits such effects.

[0067]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0068]

Example 1 Propylene / ethylene block copolymer (MFR (ASTM D-1238, L, 230 ° C., 2.16 kg load):
2.0 g / 10 minutes, ethylene content: 20 mol%, ethylene / propylene copolymer segment: 10% by weight, crystalline polypropylene segment (crystalline polypropylene:
86.7% by weight, crystalline polyethylene: 13.3% by weight) 90% by weight, intrinsic viscosity [η] of ethylene / propylene copolymer segment measured in decalin at 135 ° C .:
45 parts by weight of 3 dl / g) and MFR (ASTM D-1238, L,
Maleic anhydride was graft-polymerized to 35 parts by weight of a propylene homopolymer having a length of 230 g and a load of 2.16 kg of 11 g / 10 minutes, and a glass fiber (70% by weight) having a length of 10 mm and an average fiber diameter of 13 μm. 20 parts by weight of a glass fiber masterbatch obtained by extrusion-coating the obtained modified polypropylene (the graft amount of maleic anhydride is 0.6% by weight based on the weight of the modified polypropylene) (30% by weight),
Based on 100 parts by weight of the total amount of the above block copolymer, propylene homopolymer, and modified polypropylene-coated glass fiber masterbatch, 2,5-dimethyl-2,5-di (t -Butylperoxy) hexyne-3 0.05 part by weight and trimethylolpropane trimethacrylate (TMP) as a crosslinking aid
TMA) 0.7 part by weight and tetrakis as an antioxidant
-[Methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane [Product name Irganox 1010, manufactured by Nippon Ciba-Geigy Co., Ltd.]
0.1 part by weight, 0.1 part by weight of calcium stearate, and azodicarbonamide (ADCA) as a foaming agent
3.0 parts by weight and a high speed mixer (Henschel mixer)
Were mixed with.

Next, this mixture was screwed to 90 mm.
1 using a T-die sheet molding machine with a diameter of 1800 mm
It was formed into an unfoamed expandable sheet having a thickness of 0.9 mm at a temperature of 75 ° C. And, the basis weight 3 on one side of this foamable sheet
A backing material made of a polyester non-woven fabric (PET non-woven fabric) of 0 g / m ² was lined. Next, the foamable sheet was irradiated with γ-ray (Co-60) at 4.0 KGy to perform cross-linking.

The foamable sheet after the cross-linking is MFR (AS
TM D-1238, L, 230 ℃, 2.16kg load) is 3.0g / 10
The gel fraction (xylene insoluble fraction) obtained after treatment with boiling p-xylene for 3 hours was 5.7%. Next, this foamable sheet is sized 1500 mm.
The foamable sheet was heated with a far-infrared heater in a state where it was cut into × 1300 mm and the four sides were clamped and the backing material was the lower surface. Regarding the temperature condition of the heater, the set temperature of the upper heater is 400 ° C, and the set temperature of the lower heater on the opposite side, that is, the backing material side is 300 ° C.
When it was heated to, it foamed in 85 seconds. The obtained foamed sheet had a thickness of 5.6 mm and a foaming ratio of 6.2.

Next, while the obtained foamed sheet has not yet been solidified by cooling, a polyester non-woven fabric having a basis weight of 250 g / m ² is laid on the upper surface of the foamed sheet as a ceiling skin material, and press-molded with the upper and lower aluminum ceiling molds. did. This mold is cooled by passing water. The molded ceiling material in which the foamed sheet and the skin material were integrated was cooled and solidified in 1 minute. After 1 minute, the mold was opened and the molded ceiling material was taken out.

The molded ceiling material thus obtained was mounted on the ceiling of an automobile and subjected to a humidity and heat test under the following conditions. As a result, the ceiling droop was 10 mm or less, and there was no deformation or appearance. It was clear. (1) As shown in FIG. 1, a φ80 mm test piece 1 cut out from a foam molded article (molded ceiling) to which a fogging-resistant skin material is pasted is placed in a beaker 2 and the mouth peripheral portion of the beaker 2 is placed. On the packing 3 preset on the glass plate 4, 21 ° C
The cooling plate 5 in which the cooling water is circulated is placed in this order to shut off the inside of the beaker 2 from the atmosphere,
It was immersed in an oil bath 6 at ℃. After immersing in the oil bath 6 for 5 hours, the haze value of the glass plate 4 is AS
It was measured according to TM D1003, and the haze value was used to evaluate the fogging resistance. A haze value of 15% or less was accepted. (2) Foamed Sheet Thickness and Foaming Ratio The thickness of the foamed sheet in a free foaming state and its foaming ratio are
I asked for it as follows.

That is, after the four sides of the foamable sheet were clamped, the foamable sheet was heated and foamed by the upper and lower heaters. Then, the obtained foamed sheet was forcedly cooled by an air fan to be solidified. Then, the average thickness of the center portion of the foamed sheet after solidification was defined as "the thickness of the foamed sheet in the free foaming state". The value obtained by dividing the thickness of the foamed sheet by the thickness of the sheet before foaming (foamable sheet) was defined as the "foaming ratio of the foamed sheet in the free foaming state". (3) Before the foam-retaining foam sheet solidifies, the skin material was placed on the foam sheet, press-molded using a ceiling mold, and cooled and solidified. The mold clearance at the time of pressing was set to 4 mm.
The thickness of only the foamed sheet from which the skin material of the obtained foamed molded product (molded ceiling) was peeled off was measured, and the thickness of the flat surface portion (t ₁ m
m) and the thickness of the corner portion (t ₂ mm), the foam retention was evaluated according to the following criteria.

<Evaluation Criteria for Foam Retention> ⊚: Thickness t ₁ (mm) of the flat portion is 3.5 <t ₁ ≤ 4.
0, and the thickness t ₂ (mm) of the corner portion is 2.
Those with 5 <t ₂ . ◯: The thickness t ₁ (mm) of the flat portion is 3.0 <t ₁ ≦ 3.
5 and the corner portion thickness t ₂ (mm) is 2.
0 <t ₂ ≦ 2.5.

Δ: The thickness t ₁ (mm) of the plane portion is 2.5 <
t ₁ ≤ 3.0 and the thickness t ₂ (m
m) is 1.5 <t ₂ ≦ 2.0. ×: The thickness t ₁ (mm) of the flat surface portion is 2.5 ≧ t ₁ and the thickness t ₂ (mm) of the corner portion is 1.5 ≧ t
What is ₂ . (4) Micro-foaming The foam diameter of the foam cells in the flat portion of the sample used for the evaluation of the foam retention was measured, and the average value r (μm) was used to evaluate the micro-foaming according to the following criteria.

<Evaluation criteria for fine foaming> ⊚: r ≦ 250 (μm) A: 250 <r ≤ 300 (μm) △: 300 <r ≤ 350 (μm) X: r> 350 (μm) The results are shown in Table 1.

[0077]

Example 2 Example 1 was repeated except that the amount of TMPTMA was changed to 1.5 parts by weight. The results are shown in Table 1.

[0078]

Comparative Example 1 In Example 1, triallyl isocyanurate (TAI) was used instead of 0.7 parts by weight of TMPTMA.
C) The procedure of Example 1 was repeated except that 0.7 part by weight was used. The results are shown in Table 1.

[0079]

[Comparative Example 2] In Example 1, except that 0.3 parts by weight of TAIC was used instead of 0.7 parts by weight of TMPTMA.
The same procedure as in Example 1 was performed. The results are shown in Table 1.

[0080]

[Table 1]

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining a method for testing fogging resistance performed in Examples and the like.

[Explanation of symbols]

1 ... Test piece 2 ... Beaker 3 ... Packing 4 ... Glass plate 5 ... Cooling plate 6 ... Oil bath

Front page continuation (51) Int.Cl. ⁷ identification code FI theme code (reference) C08K 5/103 C08K 5/103 7/14 7/14 C08L 23/12 C08L 23/12 23/16 23/16 F term (reference) 3D023 BA00 BA01 BB03 BD01 BE06 BE31 4F074 AA24 AA25 AA98 AB05 AC34 AE04 AF02 AG01 BA13 BB02 BB28 CA29 CC04Y CC05Z CC06X CC10X CC10Z CE02 DA02 DA04 DA08 DA20 DA24 DA35 4F100 AG00A AK07A AK25A AK66A AS00C AT00B BA03 BA10B BA10C CA01A CA23A CA30A DG01A DG15 EJ022 EJ051 EJ202 EJ422 EJ531 GB33 JA06A YY00A 4J002 BB11W BB12W BB12X BB14W BB15W BP02W DE249 DL006 EH078 EK017 EK027 EK037 EK026 FD047 FD047 FD047 FD047 WF047 EF0 1470 EF0 147 009 EF047 EK047 EK047 EK047 EF0 147

Claims (10)

[Claims] 1. A propylene-based resin (A) 75 to 95 parts by weight and a glass fiber (B) 5 to 25 parts by weight [components (A) and (B)].
Is 100 parts by weight], and the total amount of the propylene resin (A) and the glass fiber (B) is 1
0.01 to 0.1 parts by weight of the radical generator (C), 0.1 to 5 parts by weight of the crosslinking aid (D), and 2 to 5 parts by weight of the foaming agent (E) with respect to 00 parts by weight. In the composition for forming a foamable sheet, the cross-linking aid (D) is polymethylolalkane / poly (meth) acrylates and / or polymethylolalcohol / poly (meth) acrylates. Expandable polypropylene resin composition. 2. The propylene resin (A) is a propylene / α-olefin block copolymer (F) 15 to 85.
The expandable polypropylene resin composition according to claim 1, wherein the expandable polypropylene resin composition is a resin composition comprising 50% by weight and propylene homopolymer (G) of 85 to 15% by weight. 3. The propylene / α-olefin block copolymer (F) contains an ethylene / propylene copolymer segment in an amount of 2% by weight or more and less than 20% by weight and 80% by weight of a crystalline polypropylene segment. More than 98% by weight and contains ethylene content of 2 mol%
The propylene / ethylene block copolymer (F) having an intrinsic viscosity [η] of 20% by mole or more and less than 20 mol% and an ethylene / propylene copolymer segment measured in decalin at 135 ° C. is in the range of 2 to 8 dl / g. -1), The expandable polypropylene resin composition according to claim 2. 4. The propylene resin (A) has a melt flow rate (ASTM D-1238, L, 230 ° C., 2.16 kg load) of 0.
It is 5-20g / 10min, It is characterized by the above-mentioned.
The expandable polypropylene resin composition according to any one of 3 above. 5. The glass fiber (B) has an average fiber diameter of 5
The foamable polypropylene resin composition according to claim 1, which has a fiber length of 0.1 to 20 mm and a fiber length of 0.1 to 20 mm. 6. The expandable polypropylene resin according to claim 1, wherein the glass fiber (B) is a glass fiber coated with a modified polypropylene obtained by graft-polymerizing an unsaturated carboxylic acid or a derivative thereof. Composition. 7. A propylene resin (A), a glass fiber (B), a radical generator (C), a cross-linking aid (D) and a foaming agent (E) according to any one of claims 1 to 6. The expandable polypropylene resin composition contained is molded into a sheet at a temperature at which the foaming agent (E) is not decomposed, and one side of the obtained expandable sheet is lined with a backing material to be integrated. After the foamable sheet is irradiated with ionizing radiation to crosslink the propylene-based resin (A), and then the foamable sheet is heated to foam, the surface of the foamed sheet is not cooled and solidified. In a method for producing a molded ceiling material for an automobile, which comprises a step of placing a skin material on a substrate and press-molding the same, polymethylolalkane / poly (meth) acrylates and / or polymethylolalcohol as the crosslinking aid (D). Method of manufacturing an automotive molded roof material which comprises using the Le poly (meth) acrylates. 8. The dose of the ionizing radiation is 2 to 10 KG.
It is y, The manufacturing method of the molded ceiling material for motor vehicles of Claim 7 characterized by the above-mentioned. 9. The gel fraction of the foamable sheet after irradiation with the ionizing radiation is 1 to the weight of the propylene resin (A).
The method for producing a molded ceiling material for an automobile according to claim 7, wherein the content is 10% by weight. 10. A molded ceiling material for automobiles, which is obtained by the manufacturing method according to any one of claims 7 to 9.