JP2009019084A - Vehicle interior material and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle interior material of simple configuration in which measures are taken to cope with a side impact. <P>SOLUTION: The vehicle interior material includes a substrate made of a thermoplastic resin, wherein the substrate (11) partially has an easily deformable part (13) in which the gel fraction of the thermoplastic resin is ≤10% in a main part (12) having a crosslinked structure in which the gel fraction of the thermoplastic resin is 45-90%. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an interior material for a vehicle and a method for manufacturing the same, and more particularly to an interior material for a vehicle such as a door trim configured to promote breakage and deformation when a collision occurs to reduce an impact load on an occupant.

  In a vehicle such as an automobile, a resin interior material (trim) is attached to the surface of a metal panel constituting the vehicle body at a portion facing the passenger compartment. In addition to being excellent in appearance from the viewpoint of improving appearance, this type of interior material has strength and heat resistance, and is also required to be light in weight to reduce fuel consumption. Furthermore, in order to protect a passenger | crew at the time of a collision accident etc., having an impact absorption function is calculated | required.

  Thus, for example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 10-24775), a concave groove is formed on the back surface of a base material of an interior part in order to absorb an impact on an occupant during a vehicle collision, and the base material starts from the groove. I am trying to transform.

  Further, in Patent Document 2 (Japanese Patent Application Laid-Open No. 63-175041), the foam center with respect to the gel fraction of the surface layer of the foam and the apparent density of 0.2 to 0.020 g / cc, the thickness of at least 4 mm A radiation-crosslinked thick polypropylene resin foam having a gel fraction ratio of 1.5 or less has been proposed, and the foam can also be used as a door trim.

Japanese Patent Laid-Open No. 10-24775 JP 63-175041 A

  The interior parts corresponding to the side collision described in Patent Document 1 reduce the impact load on the occupant in the event of a collision while ensuring the rigidity of the base material. difficult. Moreover, since the concave groove is formed in the base material, the shape of the molding die is complicated.

Although the said patent document 2 is related with the technique of using the bridge structure by radiation for control of foaming, it is disclosed that it is used for a door trim, it does not consider passenger protection when an impact is applied from the side. No measures are taken against this.
In addition, the polypropylene resin foam of Patent Document 2 is subjected to large deformations such as foaming and molding after the polypropylene resin is cross-linked by radiation. Therefore, as exemplified in Patent Document 2, the gel fraction is about 30%. It is possible to deform by foaming or molding. As described above, the foam of Patent Document 2 does not form a strong cross-linked structure by radiation irradiation, and it is difficult to obtain an interior material that requires more than the required rigidity as a whole.

  The present invention has been made in view of the above problems, and has an overall rigidity and an easily deformable portion that easily deforms or breaks when an excessive impact is applied at the time of collision. It is an object of the present invention to provide an interior material for a vehicle that can reduce the load and protect an occupant and a method for manufacturing the same.

In order to solve the above problems, the present invention is a vehicle interior material provided with a thermoplastic resin base material,
The base material has a cross-linked structure having a gel fraction of 45% or more and 90% or less of the thermoplastic resin, and partially has a portion where the gel fraction of the thermoplastic resin is 10% or less. The vehicle interior materials are provided.

As described above, the base material of the vehicle interior material of the present invention includes a portion having a crosslinked structure (hereinafter referred to as a main body portion) having a gel fraction of 45% or more and 90% or less of a thermoplastic resin, and a thermoplastic resin. A portion having a gel fraction of 10% or less and substantially not forming a crosslinked structure (hereinafter referred to as an easily deformable portion) coexists in one molded body.
That is, according to the present invention, the base material to be integrally molded has a cross-linked structure and an excellent impact resistance strength, and when an impact exceeding a predetermined level is applied from the outside, a partially deformable portion is provided. This makes it easy to deform or break and reduce the impact on the occupant.

In the present invention, the strength is improved by making the thermoplastic resin into a crosslinked structure, and in order to obtain a vehicle interior material having the intended strength of the present invention, the degree of crosslinking applied to the molded product is It becomes important. The gel fraction indicates the degree of crosslinking, and in order to ensure the strength improvement effect by crosslinking of the thermoplastic resin, as described above, the gel fraction of the main body needs to be 45% or more, preferably 60% or more. On the other hand, the reason why the gel fraction of the main body is 90% or less is that the gel fraction hardly exceeds the strength even if it exceeds 90%.
On the other hand, the reason why the gel fraction of the thermoplastic resin in the easily deformable portion is 10% or less is that if it exceeds 10%, the thermoplastic resin molecules are crosslinked and are not easily deformed or broken.

The method for measuring the gel fraction is as follows.
A predetermined amount of sample is wrapped in a 200-mesh stainless steel wire mesh and boiled in xylene solution for 48 hours, and then the sol dissolved in xylene is removed to obtain the remaining gel. Dry at 50 ° C. for 24 hours to remove chloroform in the gel, measure the dry weight of the gel, and calculate the gel fraction by the following formula.
(Gel fraction (%)) = (Dry weight of gel) / (Original dry weight) × 100

The easily deformable portion of the portion having a gel fraction of 10% or less preferably has a thickness of 1 mm to 70 mm.
Further, only one easily deformable portion may be provided on the base material, or may be provided at a plurality of locations. In the case where a plurality of locations are provided, they are unevenly distributed or uniformly distributed. The thickness of the main body excluding the easily deformable portion is equal to that of the easily deformable portion.

The interior material of the present invention may be any part that faces the passenger compartment and can be attached to a place where an occupant may come into contact with a vehicle when it collides. For example, it is used as a trim or garnish for a door, roof, pillar, etc. It is done. Among these, it is suitably used as a door trim for a side door.
When the door trim of the side door is used, the front passenger trim installed on the front seat side and the rear door trim installed on the rear seat side are usually positioned more than the center of the door trim in the vehicle front-rear direction. Since the seat is seated on the rear side, the easily deformable portion is preferably provided on the rear side of the central portion of the base material in the vehicle front-rear direction.
Furthermore, it is preferable that the easily deformable portion is provided at a position corresponding to the chest or / and the waist of the occupant in the vertical direction of the vehicle.

Since the vehicle interior material of the present invention is made of a thermoplastic resin, it has the advantage of being excellent in corrosion resistance and light weight as compared with a metallic material.
The thermoplastic resin used in the present invention is not particularly limited as long as it can introduce a crosslinked structure. For example, it can be used in various polypropylenes such as high-density and low-density polyethylene, isotactic and syndiotactic, polystyrene, polyethylene terephthalate and polybutylene terephthalate. General-purpose resins such as acrylic resins such as various polyesters, polyvinyl chloride, polycarbonate, polypropylene oxide, polyethylene oxide, polysulfone and polymethyl methacrylate, nylon, polyamide, polyether ether ketone, polyether imide, polyphenylene sulfide Engineering plastics such as acrylonitrile butadiene styrene, natural polysaccharides such as cellulose, starch, chitin, chitosan, alginic acid and so on. Polysaccharides including derivatives obtained by acetylating, esterifying, etc., ε-caprolactone, polybutylene succinate, polyethylene succinate, polyethylene succinate adipate, polybutylene succinate lactide, polybutylene succinate adipate lactide, L-form and D Examples thereof include aliphatic polyesters typified by polylactic acid, and copolymers of aliphatic polyesters and aromatic polyesters typified by polybutylene adipate terephthalate into which aromatics such as terephthalic acid are introduced.
Among these, polypropylene and a copolymer containing polypropylene are preferably used because they are particularly inexpensive and lightweight, and can be easily subjected to foam molding effective for weight reduction.

When the polypropylene is used, it may be a pure polypropylene having an isotactic structure, a syndiotactic structure, etc., but a block containing a linear component such as polyethylene or a rubber component such as EPDM from the viewpoint of easy introduction of a crosslinked structure. Copolymers and copolymers can be suitably used. These can be used alone or in combination of two or more.
In particular, EPDM is preferably used because the more EPDM component is more easily crosslinked.

The present invention, as a manufacturing method of the vehicle interior material, to prepare a kneaded product by mixing a polyfunctional monomer with a molten thermoplastic resin,
Molding the kneaded product into a required shape to produce a molded product,
A vehicle interior material characterized in that the molded product is partially masked with a radiation shielding material and irradiated with ionizing radiation, and the non-masking portion has a crosslinked structure having a higher gel fraction than the masking portion. A manufacturing method is provided.

  As described above, after molding a thermoplastic resin kneaded with a polyfunctional monomer, it is molded into the shape of an interior material such as a door trim, and when the molded product is irradiated with ionizing radiation, the thermoplastic resin molecules are crosslinked. As described above, it is possible to form the main body with improved impact strength by setting the gel fraction to 45% or more and 90% or less. Further, when the ionizing radiation is irradiated, by partially masking and blocking the radiation, an easily deformable portion having a relatively low rigidity and a gel fraction of 10% or less can be provided without being crosslinked.

  A polyfunctional monomer is mixed with a thermoplastic resin to form a crosslinked structure with the gel fraction. The polyfunctional monomer is preferably at least one selected from the group consisting of allyl monomers, methacrylic monomers, and acrylic monomers.

  Examples of the acrylic or methacrylic polyfunctional monomer include 1,6-hexanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, ethylene oxide-modified tri Methylolpropane tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, ethylene oxide modified bisphenol A di (meth) acrylate, diethylene glycol di (meth) acrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate , Caprolactone-modified dipentaerythritol hexaacrylate, pentaerythritol tri (meth) acrylate, pentaerythritol Rutetora (meth) acrylate, polyethylene glycol di (meth) acrylate, tris (acryloyloxyethyl) isocyanurate, tris (methacryloxyethyl) isocyanurate.

  Examples of the allylic polyfunctional monomer include triallyl isocyanurate, trimethallyl isocyanurate, triallyl cyanurate, trimethallyl cyanurate, diallylamine, triallylamine, diacrylic chlorate, allyl acetate, allyl benzoate, allyl. Dipropiocyanocyanate, allyl octyl oxalate, allyl propyl phthalate, bityl allyl malate, diallyl adipate, diallyl carbonate, diallyl dimethyl ammonium chloride, diallyl fumarate, diallyl isophthalate, diallyl malonate, diallyl oxalate, diallyl phthalate , Diallylpropyl isocyanurate, diallyl sebacate, diallyl succinate, diallyl terephthalate, diallyl tartrate, di Chill diallyl phthalate, ethyl allyl malate, methyl allyl fumarate, methyl meta-allyl maleate, diallyl monoglycidyl isocyanurate.

  As the polyfunctional monomer used in the present invention, an acrylic or methacrylic polyfunctional monomer is preferable because a high degree of crosslinking can be obtained at a relatively low concentration. Among these, trimethylolpropane tri (meth) acrylate (hereinafter referred to as TMPTA and TMPTMA) is particularly preferable because of its high crosslinking effect on polypropylene.

The polyfunctional monomer is preferably blended at a ratio of 0.5 parts by mass or more and 8 parts by mass with respect to 100 parts by mass of the thermoplastic resin.
In the polyfunctional monomer, cross-linking is recognized at 0.05 parts by mass or more with respect to 100 parts by mass of the thermoplastic resin. Is required to be 0.5 parts by mass or more with respect to 100 parts by mass of the thermoplastic resin. On the other hand, when the amount exceeds 8 parts by mass, it becomes difficult to surely uniformly mix the whole amount with polypropylene, and there is substantially no significant difference in effect. In the manufacturing process, polyfunctional monomers are very easy to evaporate at the molding temperature of polypropylene, and it is desirable to reduce the mixing amount as much as possible considering safety control problems. It is most suitable to mix | blend in the ratio of 0.5-6 mass parts with respect to 100 mass parts of resin, and also 1-3 mass parts.

A foaming agent may be mixed for the purpose of reducing the weight of foamed polypropylene.
In the present invention, radiation is not irradiated for controlling foaming as in Patent Document 2, but after forming the foam, radiation is irradiated to form a crosslinked structure. Higher gel fraction and excellent impact strength.

Furthermore, you may mix a hydrolysis inhibitor and a flame retardant for the purpose of improving durability and flame retardance of thermoplastic resins, such as a polypropylene.
In particular, the interior material for a vehicle is required to have flame retardancy, so it is preferable to add a flame retardant. Further, for the purpose of reinforcement, fillers such as minerals and carbon fibers may be mixed. Examples of the filler include glass fiber, glass beads, metal powder, talc, mica, clay, and silica.

Furthermore, other components may be added as long as the object of the present invention is not adversely affected.
For example, a thermoplastic resin other than the thermoplastic resins listed above may be blended. Furthermore, additives such as curable oligomers, various stabilizers, antistatic agents, crystal accelerating nucleating agents, antifungal agents or viscosity imparting agents, and coloring agents such as dyes or pigments may be added to the composition. it can.

  The manufacturing process of the interior material will be described in detail. First, a thermoplastic resin of the type described above, a polyfunctional monomer, and other components as required are mixed to prepare a kneaded product. The kneaded product is in the form of pellets or a sheet connected to the pellets for the purpose of facilitating the molding described later.

  Next, the kneaded product obtained by the above process is heated to a temperature equal to or higher than the melting point or softening point of the thermoplastic resin to be molded into a desired shape. The molding method is not particularly limited, and a known method may be used. For example, known molding machines such as a compression molding machine, a blow molding machine, a T-die molding machine, an injection molding machine, and an inflation molding machine are used.

Masking having a radiation shielding function is applied to a required portion of the molded product obtained by the above process. The part to be masked is a part to be the easily deformable part.
The masking material for masking is a single metal or a resin molded product containing heavy metal. The resin may contain a metal having a radiation shielding ability and should be stable to some extent against radiation.
Since the radiation shielding ability is simply proportional to the specific gravity, the metal having a larger atomic number is more effective, and precious metals such as gold, silver, and mercury, lead, thallium, and tungsten are preferably used.
Among them, lead is preferable because it is soft and easily conforms to the shape of the irradiated object, so that masking is reliable and relatively inexpensive.

After the masking, ionizing radiation is irradiated.
By irradiating with this ionizing radiation, the uncrosslinked functional groups of the polyfunctional monomer are bonded to the molecules of the thermoplastic resin in a network form, and are in a crosslinked state so that the shape can be maintained even when heated.

As ionizing radiation, γ-rays, X-rays, β-rays or α-rays can be used. However, for industrial production, γ-ray irradiation with cobalt-60 or electron beam irradiation with an electron beam accelerator is preferable.
The irradiation with ionizing radiation is preferably performed in an inert atmosphere or air except for air. This is because the active species generated by irradiation with ionizing radiation is inactivated by binding to oxygen in the air and the crosslinking effect is lowered.

  The irradiation dose of the ionizing radiation varies depending on the type of thermoplastic resin and the type of the polyfunctional monomer, and the irradiation dose that does not impair the thermal fluidity of the mixture above the dose that can suppress the vaporization and transpiration of the polyfunctional monomer. It is preferable to check and adjust the following conditions in advance. Crosslinking is observed even when the irradiation dose is several kGy, but 5 kGy is necessary for crosslinking of about 100% of molecules, and preferably 10 kGy or more, in the present invention. In addition, since polypropylene used as a thermoplastic resin has the property of collapsing radiation by itself, irradiation of the necessary surroundings causes decomposition to proceed contrary to crosslinking. Therefore, the irradiation dose is 600 kGy or less, further 300 kGy or less, more preferably 200 kGy or less.

  As described above, the base material of the vehicle interior material of the present invention has a crosslinked structure in which the gel fraction of the thermoplastic resin is 45% or more and 90% or less, and partially the gel content of the thermoplastic resin. An easily deformable portion having a ratio of 10% or less and a gel fraction of 10% is integrally provided in a base material having strength. Therefore, it is not necessary to form an easily deformable portion including a recess or a groove on the base material, and the mold shape for molding the interior material can be simplified. In addition, unlike Patent Document 1, it is not necessary to provide a concave groove on the back surface of the base material, and while the rigidity of the interior material is ensured, when an impact is applied, it is easily deformed or broken at an uncrosslinked portion, so The interior material can be relaxed.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a door trim 10 for a side door according to an embodiment of the present invention.
The door trim 10 is attached to the indoor side surface of a door inner panel (not shown), and a base material 11 made of a resin molded product is formed into the shape shown in FIG. Necessary parts (not shown) are attached to the side.

  The base material 11 is made of polypropylene, and the gel fraction of the polypropylene is 10% or less as shown in FIG. 2 in the main body portion 12 having a crosslinked structure in which the gel fraction is 45% or more and 90% or less. A part of the easily deformable portion 13 is included. A polypropylene copolymer may be used.

The average thickness of the main body portion 12 of the substrate 11 is 1 mm to 4 mm, and the average thickness of the easily deformable portion 13 is 1 mm to 4 mm. One easily deformable portion 13 is provided from the center to the vicinity of the rear end in the front-rear vehicle direction, and at a substantially intermediate position in the vertical direction between the upper end located at the lower end of the window frame and the lower end from the floor side. . The length L in the vehicle front-rear direction of the easily deformable portion 13 is 5 mm to 800 mm, and the width in the vertical height direction is 5 mm to 10 mm.
The easily deformable portion 13 is not limited to the one described above, and may be formed by extending in the vertical direction, or a plurality of easily deformable portions having a surface area smaller than that of the easily deformable portion 13 are arranged in a distributed manner. May be.

  The bending elastic modulus of the main body 12 of the base material 11 without irradiation masking is 16800 to 17630. On the other hand, the bending elastic modulus in the irradiation masking part which becomes the easily deformable part 13 is 14230-15730. The maximum bending load (N) is 42 to 44, and the bending elastic gradient (n / 10 mm) is 123 to 137.

A method for manufacturing the base material 11 of the door trim 10 will be described below.
First, 3 to 6 parts by mass of a polyfunctional monomer is blended with 100 parts by mass of heat-melted polypropylene to prepare a kneaded product. In this embodiment, 3 parts by mass of TMPTMA, which is a kind of methacrylic crosslinkable monomer, is blended.

The kneaded product is supplied to a mold cavity and injection molded to obtain a molded product shown in FIG.
Next, the molded product is attached to the portion where the easily deformable portion 13 is provided with a maskink material. The masking material is made of lead having radiation shielding performance.
Subsequently, ionizing radiation is irradiated to the molding. The irradiation amount is set to 5 kGy or more and 600 kGy or less.

  Examples of the present invention and comparative examples will be described below. Both the examples and comparative examples were prepared as test pieces in which the shape of the substrate 11 was a flat plate shape, and the physical properties thereof were evaluated.

(Example 1 to Example 3)
As the thermoplastic resin, polypropylene (FX200S (trade name) manufactured by Prime Polymer Co., Ltd.) was used. Prepare TMPTMA (TD1500 manufactured by Dainippon Ink Co., Ltd.), which is a kind of methacrylic crosslinkable monomer, and melt the thermoplastic resin at a cylinder temperature of 190 ° C using an extruder (PCM30 model manufactured by Ikekai Tekko Co., Ltd.). When extruding, TMPTMA was added to the thermoplastic resin by dropping TMPTMA at a constant speed with a peristaltic pump into the pellet supply section of the extruder. At that time, TAIC was added so that the blending amount of TMPTMA became a mass part shown in Table 1 with respect to 100 parts by mass of the thermoplastic resin. The extruded product was cooled with water and pelletized with a pelletizer to obtain a pellet-like kneaded product of a thermoplastic resin and a crosslinkable monomer.

This kneaded material was put into an injection molding machine, poured into a mold in a molten state at 200 ° C., and molded, and then a base material 20 having a thickness of 3.8 mm, a vertical dimension of 110 mm, and a horizontal dimension of 9.9 mm was produced. . As shown in FIG. 3, four base materials 20 were laminated, and a lead masking material 21 having a thickness of 6 mm was externally fitted. The masking material 12 has two widths 10 mm and 20 mm.
After masking with the masking material having the width shown in Table 1, an electron beam is irradiated with an electron accelerator (acceleration voltage: 10 MeV current amount: 12 mA) at an irradiation amount shown in Table 1 in an inert atmosphere excluding air, and a crosslinked polypropylene product A substrate consisting of The masked portion becomes the easily deformable portion, and the non-masking portion becomes the main body portion.

(Comparative Examples 1 and 2)
In Comparative Examples 1 and 2, as shown in Table 1, the amount of TAIC (crosslinking agent) added was 3% and 6%, and the electron beam irradiation amount was 120 kGy. The whole was irradiated without masking.

With respect to Examples 1 to 3 and Comparative Examples 1 and 2, the elastic modulus, the maximum bending load, and the maximum elastic gradient in the normal state and when heated at 80 ° C. were measured. The elastic modulus, maximum bending load, and maximum elastic gradient were measured according to JISK7171. The results are shown in Table 1.

Moreover, in Examples 1-3, the gel fraction of a masking part and a non-masking part was measured.
(Measurement of gel fraction)
First, as shown in FIG. 4, the lead masking portion S1 and the non-masking portion S2 have the lead masking edge as the boundary position 0, and the surface of the masking portion S1 and the non-masking portion S2 is 1 mm with the boundary position as a fulcrum. Divided into units and divided into 4 sections. Furthermore, the block was divided every 2 mm in the thickness direction from the surface, and 40 blocks having a width of 1 mm and a thickness (depth) of 2 mm were cut and obtained.
Each of the 40 blocks was wrapped in a 200 mesh stainless steel wire and boiled in xylene for 48 hours, and then the sol dissolved in xylene was removed to obtain the remaining gel. Dry at 50 ° C. for 24 hours to remove chloroform in the gel, measure the dry weight of the gel, and calculate the gel fraction by the following formula.
(Gel fraction (%)) = (Dry weight of gel) / (Original dry weight) × 100

In the sample shown in FIG. 4, 6% of TAIC was added, the electron beam irradiation amount was 120 kGy, and the thickness of the sample was 10 mm. The thickness of the lead masking was 6 mm.
The cross-linking rate in each of the 40 blocks is shown in each block in FIG.
In the sample of FIG. 4, in the region of the lead masking portion S1, the gel fraction is 0 to 33% as the sample thickness increases in the block in the range of the lead mask boundary position 0 to 1 mm. Although it gradually increased, it was confirmed that the gel fraction was 0% and not crosslinked at a position 1 mm or more away from the boundary position.
The cross-linking in the range of the boundary position of 0 to 1 mm is that the boundary between electron beam irradiation and non-irradiation is blurred at a position away from lead masking (position away from the thickness direction of the sample). It is recognized that they have received it.
On the other hand, the gel fraction in each of the 20 blocks of the non-masking portion S2 was 48% to 61%.

  The measurement results of the gel fractions of Examples 1 to 3 measured by the method shown in FIG. 4 are as shown in Table 2 below. The gel fraction of the non-masking portion and the masking portion is the average gel fraction of the blocks divided as described above.

As shown in Table 1, when the physical property values of Example 1 with masking and Comparative Example 1 without masking with the same TAIC addition amount and electron beam irradiation amount are compared, both in the normal state and in the hot state Example 1 was lower than Comparative Example 1 in terms of bending elastic modulus, maximum bending load, and bending elastic gradient, and it was confirmed that deformation or breakage was easily obtained by providing a portion that was not cross-linked by masking.
Further, even if the physical property values of the masked Examples 2 and 3 and the comparative example 2 without masking in which the TAIC addition amount and the electron beam irradiation amount are the same are compared, the flexural elasticity is obtained both in the normal state and in the hot state. Examples 2, 3 were lower than Comparative Example 2 in terms of rate, maximum bending load, and bending elastic gradient, and it was confirmed that they were easily deformed or broken by providing a portion that was not cross-linked by masking.

  As is clear from the above experimental examples and comparative examples, when a portion that is not masked and irradiated with an electron beam is provided, the portion becomes an easily deformable portion, and the easily deformable portion is a starting point, and a collision load is applied. Sometimes the door trim is likely to be deformed or broken, so that the damage received when the occupant collides with the door trim can be reduced, and the occupant can be protected.

The vehicle interior material of the present invention is not limited to the above-described embodiment and examples, and should be interpreted based on the claims.
Needless to say, the vehicle interior material of the present invention may be provided with other members such as a skin material and a cushion pad in addition to the base material.

It is a perspective view which shows the trim of the side door for vehicles of 1st Embodiment. It is the schematic of the board | substrate of the said trim. It is drawing which shows the state which has attached the masking material to the test piece of an Example. It is drawing which shows the measuring method of a gel fraction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Door trim 11 Base material 12 Main part 13 Easily deformable part

Claims (8)

A vehicle interior material provided with a thermoplastic resin base material,
The base material has a cross-linked structure having a gel fraction of 45% or more and 90% or less of the thermoplastic resin, and partially has a portion where the gel fraction of the thermoplastic resin is 10% or less. Vehicle interior materials.   The vehicle interior material according to claim 1, wherein the thermoplastic resin includes polypropylene or a copolymer of polypropylene.   The portion having a gel fraction of 10% or less has a thickness of 1 mm or more and 70 mm or less, and is provided at one or a plurality of locations on the base material, and when provided at a plurality of locations, it is unevenly distributed or uniformly dispersed. The vehicle interior material according to claim 1 or 2.   The vehicle interior material according to any one of claims 1 to 3, wherein the base material is a door trim, and a portion having the gel fraction of 10% or less is unevenly distributed rearward from a central portion in a vehicle front-rear direction. . It is a manufacturing method of the interior material for vehicles given in any 1 paragraph of Claims 1 thru / or 4, Comprising:
A kneaded product is prepared by mixing a polyfunctional monomer with a molten thermoplastic resin,
Molding the kneaded product into a required shape to produce a molded product,
A vehicle interior material characterized in that the molded product is partially masked with a radiation shielding material and irradiated with ionizing radiation, and the non-masking portion has a crosslinked structure having a higher gel fraction than the masking portion. Production method.   The vehicle interior according to claim 5, wherein polypropylene is used as the thermoplastic resin, and the multifunctional monomer is at least one selected from the group consisting of allyl monomers, methacrylic monomers, and acrylic monomers. A method of manufacturing the material.   The method for producing a vehicle interior material according to claim 5 or 6, wherein the polyfunctional monomer is blended at a ratio of 0.5 parts by mass or more and 8 parts by mass with respect to 100 parts by mass of the thermoplastic resin. .   The method for manufacturing an interior material for a vehicle according to any one of claims 5 to 7, wherein an irradiation amount of the ionizing radiation is 5 kGy or more and 600 kGy or less.

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