JP6907980B2 - How to manufacture interior parts for vehicles - Google Patents

Description

The present invention relates to a method for manufacturing an interior part for a vehicle.

Conventionally, in a resin molded product used for an interior part of a vehicle, a design expression such as a pattern is given to the outer surface of the resin molded product at the same time as the resin is molded. A resin molded product is molded by injecting resin into a cavity (also referred to as film insert molding) in which a film (or sheet) having a design expression such as a pattern is arranged.

For example, in Patent Document 1, a film that has been heat-softened and vacuum-formed is brought into close contact with the cavity surface of a mold, then the mold is molded, and the film is heated and melted in the cavity formed by the mold after molding. A manufacturing method is disclosed in which a resin is injected, cooled and solidified, and a film is laminated on the surface of a molded product at the same time as molding and painted.

Japanese Unexamined Patent Publication No. 10-278069

However, in the manufacturing method in which the cavity is filled with resin and molded while the film is in close contact with the cavity surface of the molding die, if the holding pressure is held at a low pressure, the film surface of the manufactured interior parts is φ0. It was found that a dent having a size of about 1 to 5 mm and a depth of about 1 to 1000 μm was generated. That is, it has been found that the interior parts manufactured by such a manufacturing method have a problem that dents are generated on the surface thereof.

The present invention has been made in view of the above circumstances, and even if the cavity is filled with resin in a state where the film is in close contact with the cavity surface and the pressure is held at a low pressure, the film does not dent. An object is to provide a method for manufacturing parts.

The method for manufacturing an interior component for a vehicle of the present invention, which solves the above problems, is for a vehicle in which a resin is filled in a cavity and molded with the surface of the film in close contact with the cavity surface of the molding die, and the pressure is held at 60 MPa or less. It is a method for manufacturing an interior component, wherein one surface of a film surface and a cavity surface has a surface friction coefficient of 1.0 or less, and the other surface is a mirror surface.
The manufacturing method of the present invention is a manufacturing method in which a resin is filled in a cavity with the surface of the film in close contact with the cavity surface and pressure is retained at a low pressure, but an interior component for a vehicle in which the film is not dented is provided. Can be manufactured.

In the present invention, the surface friction coefficient is measured as follows.
First, as shown in FIG. 1, the object 1 to be measured, which is the surface or cavity surface of the film, is placed on the smooth surface Ga of the glass G. At this time, the entire surface 1a of the object 1 to be measured, which is the surface of the film or the cavity surface, is placed in close contact with the surface Ga of the glass G. The object to be measured 1 has a square plate shape having a predetermined mass (50 g in the present invention), and the surface 1a forms a horizontal plane. The area of the surface 1a of the object 1 to be measured is 12000 mm ² . The surface Ga of the glass G forms a horizontal plane. Then, a weight W having a predetermined mass (300 g in the present invention) is placed on the object to be measured 1. A load of the total mass of the mass of the object 1 to be measured and the mass of the weight W is applied to the surface Ga of the glass G. In this state, the glass G is pulled in the horizontal direction (the direction perpendicular to the load direction, the right direction in FIG. 1), and the static friction force when the object 1 to be measured starts to slide relatively on the surface 1a of the glass G is measured. Measure with the jig 2. The measuring jig 2 has a fixing portion 20 fixed to the weight W, a measuring portion 21 connected to the fixing portion 20 to measure the force, and a connecting portion 22 connecting the fixing portion 20 and the measuring portion 21. ..
Then, the measured static friction force is divided by a predetermined load to calculate the surface friction coefficient. That is, it is calculated using the formula (surface friction coefficient) = (static friction force) / (predetermined load).

It is a schematic diagram which shows the measuring method of the surface friction coefficient. It is sectional drawing which shows the state of the manufacturing method of Embodiment 2 schematically. It is sectional drawing which shows the state of the manufacturing method of Embodiment 2 schematically.

Hereinafter, a method for manufacturing an interior component for a vehicle of the present invention will be specifically described using an embodiment. It should be noted that the embodiment shows one embodiment for specifically explaining the present invention, and the present invention is not limited to the following embodiments.

[Embodiment 1]
In the method for manufacturing interior parts for vehicles of this embodiment, first, a film having a surface friction coefficient of 1.0 or less is brought into close contact with the cavity surface of the molding die. Subsequently, in this state, the molten resin is filled in the cavity, and the resin is cooled and solidified while holding the pressure at 60 MPa or less for molding. According to the manufacturing method of this embodiment, it is possible to manufacture an interior component in which a film is integrally formed on the surface of a resin.

In the manufacturing method of this embodiment, first, a film having a surface friction coefficient of 1.0 or less is brought into close contact with the cavity surface of the molding die. The surface of the film is in close contact with the cavity surface of the molding die. The coefficient of friction of the surface of the film can be measured by the method described above. When the surface friction coefficient of the film is 1.0 or less, the film is easily displaced (moved) along the cavity surface in a state where the surface of the film is in close contact with the cavity surface of the molding die. The smaller the surface friction coefficient of the film, the more preferable. The surface friction coefficient of the film is more preferably 0.78 or less.

The surface roughness (Rz) of the film is preferably 0.01 μm or more, and more preferably 0.05 μm or more. The surface roughness (Rz) is defined in JIS B 0601: 2001 and can be measured using a surface roughness measuring instrument. The surface roughness (Rz) indicates the maximum height of fine irregularities on the film surface, and has a correlation with the surface friction coefficient. When the surface roughness (Rz) becomes a predetermined value or more, the surface friction coefficient becomes more reliably within a predetermined range. The surface roughness (Rz) of the film is more preferably 1.9 μm or more, and further preferably 2.5 μm or more.
In the present embodiment, in the film, the surface on which the surface friction coefficient and the surface roughness (Rz) are adjusted adheres to the cavity surface. The surface friction coefficient and surface roughness (Rz) on the back surface of the film are not limited.
The film is not limited except that the surface friction coefficient is not more than a predetermined value. For example, the thickness of the film is not limited.
As the film, as long as the surface friction coefficient is not more than a predetermined value, the film used for forming the surface in the conventional vehicle interior parts may be used.

As the film, a film made of a thermoplastic resin that can be adhered to the cavity surface of the molding die and has moldability can be used.

Examples of the thermoplastic resin constituting the film include vinyl polymers such as polyvinyl chloride, polyvinylidene chloride, vinyl acetate-vinyl chloride copolymer, polyvinyl butyral, polystyrene, acrylic-styrene copolymer, and acrylonitrile-butadiene-. Polystyrene resin such as styrene copolymer (ABS), polymethyl methacrylate (PMMA), polyethyl methacrylate, methyl methacrylate-butyl methacrylate copolymer, acrylic resin such as polyacrylonitrile, nylon 6, nylon 66 Polypolymer resin such as polyethylene, polypropylene, polymethylpentene, polyolefin resin such as olefin thermoplastic elastomer, cellulose acetate, cellulose resin such as nitrocellulose, polyethylene terephthalate, polybutylene terephthalate, ethylene terephthalate-isophthalate copolymer , Polypolylate and other polyester resins, butadiene rubber, chloroprene rubber, silicone rubber and other rubber resins, polyvinylidene fluoride, polyvinyl fluoride and other fluororesins, urethane-based thermoplastic elastomers, olefin-based thermoplastic elastomers and other thermoplastics Examples thereof include resins such as elastomers and polycarbonates. As the film, a single layer of these resins or a laminated body in which a plurality of layers are laminated can be used.

The surface friction coefficient and surface roughness (Rz) of the film can be adjusted by including inorganic particles in the resin (that is, the thermoplastic resin). When the resin contains inorganic particles, fine irregularities can be formed on the surface of the resin (thermoplastic resin). By adjusting the content of the inorganic particles, fine irregularities on the surface can be controlled, and the surface friction coefficient and surface roughness (Rz) of the film can be adjusted to a predetermined value or less. The average particle size (D50) and the content ratio of the inorganic particles to be contained can be appropriately selected depending on the target surface friction coefficient and surface roughness (Rz). The material of the inorganic particles is not limited, and particles used as an inorganic filler in a conventional resin film can be used. Examples of the inorganic particles include particles such as silica particles, alumina particles, calcium carbonate particles, and barium sulfate particles. The inorganic particles are preferably silica particles.

The film may have a surface friction coefficient of a predetermined value or less by subjecting the film to a process for adjusting the surface friction coefficient and the surface roughness (Rz). Examples of the process for adjusting the surface friction coefficient and the surface roughness (Rz) include a process of pressing a processing jig against the film surface to form irregularities and a process of blasting the film surface. Examples of the processing jig include a mold for surface molding having an uneven surface.
In this embodiment, a commercially available film having a predetermined surface friction coefficient and surface roughness (Rz) was used. This commercially available film is made of a thermoplastic resin containing inorganic particles.

Since the film forms the surface of the interior parts, it may be decorated.
Examples of the decorative treatment applied to the film include coloring of the film itself by kneading a pigment or dye, formation of a decorative layer composed of a pattern or a metal thin film layer, and formation of an uneven pattern. Further, when giving a transparent coating feeling to the molded product as a decorative effect, a colorless or colored transparent resin film alone may be used as the film.

Examples of the decoration by kneading the pigment or the like into the film include a decoration treatment of coloring transparent, coloring opaque, colorless opaque, or the like. Examples of the pigment include inorganic pigments such as titanium white, carbon black, ultramarine blue, red iron oxide, and chrome yellow, and organic pigments such as quinacridone, isoindolenone, phthalocyanine blue, and aniline black. Moreover, you may use a dye instead of a pigment. Further, if necessary, the above-mentioned inorganic particles (that is, the inorganic particles used for adjusting the surface friction coefficient) may be appropriately added.

Examples of the printing method for forming a decorative layer by pattern printing include ordinary printing means such as gravure printing, offset printing, letterpress printing, and silk screen printing. Further, it may be a drawing. The pattern of the pattern can be arbitrarily selected from, for example, a wood grain pattern, a stone grain pattern, a geometric pattern such as characters and figures, and the like. As the decorative layer (ink layer) by pattern printing, a form formed on the front surface side or the back surface side of the film, a form formed between two layers of film, or the like can be applied. The ink used for pattern printing can be formed by adding a colorant such as a pigment or a dye to a resin binder. As the resin binder, known ones such as an acrylic resin, a polyester resin, and a vinyl chloride-vinyl acetate copolymer can be used. Further, as the pigment or dye, known pigments listed for kneading into a film are used.

In order to form the decorative layer as a metal thin film layer, a process such as vacuum deposition of a metal such as aluminum or chromium may be performed. The metal thin film layer may be formed on the entire surface of the film, or may be formed in a pattern so as to obtain the above-mentioned pattern. In order to form a pattern, a removal layer is provided on an unnecessary portion of the metal thin film layer with a water-soluble ink in a desired pattern, a metal thin film layer is vapor-deposited on the entire surface of the film, and then washed with water to be formed together with the removal layer. A known method such as removing the metal thin film layer directly above can be used.

The film has a corona discharge treatment, an easy-adhesion treatment such as various known primer coatings, or a heat-sensitive adhesive layer formed on the back surface thereof in order to improve the adhesiveness with the molded product. It may be. A resin such as a thermoplastic resin, a thermosetting resin, or an ionomer can be used to form the adhesive layer. Specifically, cellulose derivatives such as ethyl cellulose, cellulose nitrate, cellulose acetate, ethyl hydroxyethyl cellulose, cellulose acetate propionate, styrene resins such as polystyrene and poly α-methylthretin, styrene copolymers, and methyl poly (meth) acrylate. , Acrylic resins such as ethyl poly (meth) acrylate, butyl poly (meth) acrylate, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyvinyl butyral, etc. Vinyl polymer, rosin, rosin-modified maleic acid resin, rosin-modified phenol resin, rosin ester resin such as polymerized rosin, polyisoprene rubber, polyisobutyl rubber, styrene butadiene rubber, rubber-based resin such as butadiene acrylonitrile rubber, kumaron resin, vinyl Examples thereof include one or a mixture of two or more kinds of natural or synthetic resins such as toluene resin, polyamide and polychlorinated olefin, and various ionomers.

The mold to which the film adheres has a cavity having a predetermined shape (that is, the shape of an interior part). Then, the film (the surface of the film) is brought into close contact with the cavity surface (hereinafter, appropriately referred to as the cavity surface for design surface molding) for molding the design surface of the molding die, for example, the interior part. As the molding die, a conventional metal (specifically, steel) molding die can be used. The molding die may be formed so as to be divisible into a plurality of parts.

In this embodiment, in the molding die, the cavity surface for forming the design surface is a mirror surface. The fact that the cavity surface for forming the design surface forms a mirror surface means that the cavity surface for forming the design surface is mirror-polished and smoothed like a mirror. That is, the molding die is subjected to a process of mirror polishing the cavity surface for design surface molding. The cavity surface for design surface molding has, for example, a surface friction coefficient of 1.0 or more and a surface roughness (Rz) of 0.05 μm or less.

The method of bringing the film into close contact with the cavity surface for forming the design surface of the molding die is not limited. The same method as before can be used. For example, a method of forming a shape that can be adhered to the cavity surface for design surface molding in advance and arranging it on the cavity surface for design surface molding to make it adhere to the cavity surface, or a method of heating and softening the film and setting it in a molding die before cooling and solidifying. Then, a method of forming the final shape with vacuum pressure or compressed air and arranging it on the cavity surface for design surface forming to bring it into close contact can be mentioned. In the method of bringing the film into close contact with the cavity surface for forming the design surface of the molding die, a step of trimming is performed as necessary.

After the surface of the film is brought into close contact with the cavity surface for design surface molding, the molding die is molded. A cavity is formed on the back surface side of the film in the molding die after molding.
Then, the molten resin is filled in this cavity, and the pressure is retained at 60 MPa or less for molding. That is, in a state where the film is in close contact with the cavity surface for design surface molding of the molding die, the cavity is filled with resin and molded (injection molding). Then, a molded product (that is, an interior part for a vehicle) in which the film and the resin are integrated can be manufactured.

The specific type of resin filled in the cavity is not limited. It can be appropriately selected depending on the physical characteristics and cost required for the manufactured interior parts. For example, thermoplastic resins such as acrylonitrile-butadiene-styrene copolymer (ABS), polystyrene, acrylonitrile-styrene copolymer (AS resin), vinyl chloride resin, polypropylene, polyethylene, polycarbonate, acrylic resin, and their thermoplastics. Examples thereof include a resin such as a polymer alloy formed by mixing a resin with another resin. As the polymer alloy, PC / ABS alloy in which ABS resin and polycarbonate (PC) are mixed, PBT / ABS alloy in which ABS resin and polybutylene terephthalate (PBT) are mixed, and ABS resin and polyamide (PA) are mixed. Examples include PA / ABS alloy, PC / PS alloy in which polystyrene (PS) and polycarbonate (PC) are mixed. In addition, polyurethane (PUR), polystyrene (PS), polyolefin (polyethylene (PE), polypropylene (PP)), phenol resin (PF), polyvinyl chloride (PVC), urea resin (UF), silicone (SI), polyimide Examples thereof include resins such as (PI) and melamine resin (MF), and foamed resins obtained by foaming a polymer alloy.
The resin is filled in the cavity. The method of filling the cavity with the resin is not limited, and the resin can be injected into the cavity and filled. Filling (injection) of the resin is performed in a state where the resin is heated and melted.

The resin is preferably filled in the cavity at a temperature equal to or higher than the softening temperature of the film. Even if the resin fills the cavity at a temperature equal to or higher than the softening temperature of the film and the heat of the resin is transferred to the surface side of the film, the heat is transferred to the cavity surface for design surface molding in which the surface of the film is in close contact. That is, since heat is transferred to the molding die and heat is dissipated, the surface side of the film (the surface side which is the design surface of the vehicle interior parts) does not melt, and the form of the film is maintained. The mold is preferably at a temperature lower than the softening temperature of the film. Then, only the back surface side of the film is partially melted. Specifically, the resin filled at a temperature equal to or higher than the softening temperature of the film partially softens (or melts) the back surface of the film when it comes into contact with the back surface of the film. Then, the pressure at the time of filling (at the time of injection) forms an interface in which the resin and the back surface of the film are entangled, and in this state, the resin and the film are firmly bonded by solidification (curing). Alternatively, the film and the resin react. As a result, it is possible to manufacture vehicle interior parts in which the film and the resin are firmly bonded. Since the film and resin are firmly bonded, when used as a vehicle interior part, even if the occupant pushes the surface of the vehicle interior part and dents it, peeling does not occur at the joint interface between the two. ..

The temperature of the resin is, for example, when the film is made of PMMA and the resin is made of ABS resin (specifically, ABS or PC / ABS alloy), the softening temperature of the film is about 90 ° C. That is, the molding temperature and the temperature at the time of injection) can be 240 to 260 ° C. The temperature of the resin can be a set temperature of the cylinder of the injection molding machine. Other injection conditions (for example, conditions such as injection speed and injection pressure) when the resin is filled by injection molding are not limited and can be appropriately selected.

After the resin is filled in the cavity, the pressure is retained at 60 MPa or less. The holding pressure indicates the pressure applied after the entire cavity is filled with the resin until the gate is sealed (solidified by the gate) at a constant pressure so that the resin does not flow back from the gate. When the holding pressure becomes equal to or lower than a predetermined pressure, no force is applied to the resin filled in the cavity, and the interior parts become soft resin. That is, the vehicle interior parts manufactured by the manufacturing method of this embodiment have flexibility and are excellent in tactile sensation. In particular, when the resin is a foamed resin, when the holding pressure is equal to or lower than a predetermined pressure, the resin is not restricted from foaming and expanding in volume, and a foamed resin having a desired porosity can be produced. That is, it is possible to manufacture vehicle interior parts having a more excellent tactile sensation.

The pressure holding pressure performed after the resin is filled in the cavity is preferably 60 MPa or less, for example, when the resin is ABS resin. When the resin is PP, it is preferably 60 MPa or less.
When the resin filled in the cavity is sufficiently cured (solidified), the molded product is taken out from the molding mold.
As described above, the interior parts for vehicles can be manufactured by the manufacturing method of this embodiment.

(Effect of this form)
In the manufacturing method of this embodiment, the surface of the film having a surface friction coefficient of a predetermined value or less is brought into close contact with the cavity surface for design surface molding of the molding die. The cavity surface for design surface molding is a mirror surface. Then, in this state, the cavity is filled with resin, and pressure is retained under predetermined conditions for molding.

In the manufacturing method of this embodiment, the surface of the film and the cavity surface for forming the design surface are in close contact with each other, and the surface of the film, which is one of both sides, has a surface friction coefficient of a predetermined value or less. The cavity surface for design surface molding, which is the other of both sides, is a mirror surface. According to this configuration, it is possible to manufacture a vehicle interior part in which the film (that is, the surface of the vehicle interior part) is not dented.

Specifically, the surface friction coefficient of the film is equal to or less than a predetermined value. Since the surface friction coefficient is small, the film can move along the design surface forming cavity surface even when the film surface is in close contact with the design surface forming cavity surface. Then, when the film is thermally expanded by the heat of the resin filled in the cavity, the film can be stretched (slidingly stretched) along the cavity surface for design surface molding. As a result, dents (buckling) of the film do not occur during thermal expansion. Then, even if the resin filled in the cavity is cured (solidified) and shrunk, the film shrinks (moves along the design surface forming cavity surface), so that the film does not dent.

Since the design surface forming cavity surface has a mirror surface (that is, a smooth surface) in this embodiment, the above-mentioned film extends (slidingly extends) along the design surface forming cavity surface. ) Sometimes, the frictional force between the surface of the film and the cavity surface for design surface molding is small. Since the frictional force is small, when the film is stretched, the stretching force is larger than the small frictional force (the frictional force cannot suppress the stretching). Therefore, the movement of the film along the cavity surface for forming the design surface is more reliably generated, and the occurrence of dents in the film is more reliably suppressed.
Further, when the surface roughness (Rz) of the film exceeds a predetermined range, when the film stretches (slides) along the design surface forming cavity surface, the film surface and the design surface forming cavity surface The frictional force between them becomes smaller. This also occurs when the resin filled in the cavity is cooled and cured to cause volume shrinkage. That is, when the film is stretched or shrunk due to heating or cooling, the deformation of the film is less regulated, and the occurrence of dents in the film is more reliably suppressed.

On the other hand, when the surface friction coefficient of the film becomes larger than a predetermined value, dents occur in the film when the resin is filled. That is, molding defects occur.
Specifically, when the surface friction coefficient of the surface of the film is large, a large frictional force is generated between the surface of the film and the cavity surface for forming the design surface. Then, the frictional force generated between the two surfaces regulates the film from moving along the design surface forming cavity surface. Then, when the film is thermally expanded by the heat of the resin filled in the cavity, the film is restricted from stretching along the design surface forming cavity surface, and the film is partially separated from the design surface forming cavity surface. Transforms into. That is, dents (buckling of the film) occur in the film.

More specifically, when the film is in close contact with the cavity surface for forming the design surface, it is fixed at a plurality of points on the interface by frictional force. When the film thermally expands in this state, the film located between the fixed portions cannot absorb the elongation and bends in a direction away from the design surface forming cavity surface. That is, the film is deformed (dented, buckled).

When the film is dented during thermal expansion, the dents formed in the film grow further when the resin filled in the cavity is cured (solidified) and contracted. As a result, in the conventional manufacturing method in which the surface friction coefficient of the film exceeds a predetermined value, the film (that is, the surface) is dented.
As described above, according to the manufacturing method of the present embodiment, it is possible to manufacture an interior component for a vehicle in which the film (that is, the surface) does not have a dent.
This effect is exhibited when the holding pressure after filling the cavity with the resin is low, especially when the foamed resin is filled.

In the manufacturing method of this embodiment, the heat of the resin filled in the cavity is quickly conducted to the molding die through the film and dissipated. Due to this heat dissipation, the film is exposed to the high heat of the resin for a short time, and the film does not soften as a whole. Therefore, the state of the surface of the film (the state where the surface friction coefficient is equal to or less than a predetermined value) of the manufactured vehicle interior parts is sufficiently maintained.

[Modified form of embodiment 1]
In the first embodiment, the surface friction coefficient of the film is smaller than a predetermined value, and the cavity surface for forming the design surface of the molding die is a mirror surface, but the opposite form may be used.

That is, the surface friction coefficient of the cavity surface for forming the design surface of the molding die may be a predetermined value or less, and the surface of the film may be a mirror surface. Even with this configuration, the film easily stretches along the design surface forming cavity surface during thermal expansion, and exhibits the same effect as that of the first embodiment.

[Embodiment 2]
This embodiment is the same manufacturing method as that of the first embodiment except that the structure of the molding die is different.
As shown in the cross-sectional view of FIG. 2, the molding die 3 in the present embodiment includes a mold main body portion 30 made of metal and a surface portion 31 made of glass provided on the design surface molding cavity surface side of the mold main body portion 30. Has.
The mold body 30 is made of the same metal as the molding mold of the first embodiment.

The surface portion 31 is made of plate-shaped glass provided on the surface of the mold main body portion 30. The surface 31a of the surface portion 31 (the surface to which the film 4 is in close contact, corresponding to the cavity surface for forming the design surface) has a mirror surface. The glass forming the surface portion 31 has a lower thermal conductivity than the metal (specifically, steel) forming the mold body portion 30. For example, the thermal conductivity of steel is 403 W / (m · K), and the thermal conductivity of glass is 0.65 W / (m · K).
In this embodiment, the mold main body portion 30 and the surface portion 31 are formed so as to be integrated in a state of being in close contact with each other on the entire surface. The mold body portion 30 and the surface portion 31 are integrated by adhesion.

(Effect of this form)
According to the present embodiment, similarly to the first embodiment, it is possible to manufacture a vehicle interior part in which the surface 4a of the film 4 (that is, the surface of the vehicle interior part) is not dented.
Further, in the vehicle interior parts manufactured by this embodiment, the surface 4a of the film 4 has a smooth surface corresponding to the surface 31a of the surface portion 31.

Specifically, in the present embodiment, the surface portion 31 forming the design surface molding cavity surface 31a of the molding die 3 is formed of glass having a low thermal conductivity (that is, heat is difficult to transfer). According to this configuration, when the resin 5 is filled in the cavity, the time until the resin 5 is cured (solidified) is longer than that in the case of the first embodiment. More specifically, the heat of the resin 5 filled in the cavity is conducted to the molding die 3 through the film 4. In this embodiment, since the thermal conductivity of the surface portion 31 of the molding die 3 is low, it is difficult to dissipate heat. Then, the time that the film 4 is exposed to the high heat of the resin 5 becomes long, and the film 4 softens as a whole. Then, as shown in FIG. 3, the film 4 is pressed against the surface 31a, which is the cavity surface for design surface molding, by the pressure of the resin 5 filled in the cavity. As a result, the surface 4a of the film 4 becomes a smooth surface corresponding to the mirror surface of the surface 31a, which is the cavity surface for design surface molding.

[Modified form of embodiment 2]
In the second embodiment, the surface portion is formed of glass, but the present invention is not limited to glass. For example, the surface portion 31 may be formed of an inorganic material such as a ceramic film (thermal conductivity: 150 W / (m · K)). As the surface portion 31, not only a single layer of glass or these inorganic materials, but also a laminated body in which a plurality of layers are laminated may be used.

[Other variants]
In each of the above forms, a film having a surface friction coefficient of a predetermined value is arranged in close contact with the cavity surface of the molding die, but the present invention is not limited to this configuration.
For example, the film may be arranged in close contact with the cavity surface of the molding die, and the film and the cavity surface may be brought into close contact with each other by reducing the pressure. Specifically, a method in which the film is brought into close contact with the cavity surface and the air between the film and the cavity surface is sucked (vacuum drawn) to bring the film into close contact with the film, or the air between the film and the cavity surface is introduced to the cavity surface. A method of sucking (vacuum drawing) through a suction port opened in the film to bring the film into close contact with the film can be mentioned.

In this case, the air between the film and the cavity surface may be continuously sucked, or the suction may be stopped when the molten resin is filled in the cavity.
According to this configuration, it is possible to suppress film dents due to air entrapment between the film and the molding die (cavity surface).

Hereinafter, the present invention will be described in more detail with reference to Examples.
[Example 1]
This example is an example in which the first embodiment is concretely implemented.
The film was made of an acrylic resin, and a resin film having a surface friction coefficient of 0.60, a surface roughness (Rz) of 5.1 μm, a thickness of 0.125 mm, and a softening temperature of 90 ° C. was used.
The mold is made of high carbon steel. In the molding die, the cavity surface for forming the design surface is a mirror surface. That is, the cavity surface for design surface molding is a smooth surface.
As the resin, ABS resin was used. This resin was filled in the cavity under the conditions of the temperature at the time of injection (set temperature): 240 ° C., the injection speed: 70 mm / s, and the holding pressure after filling: 51.6 MPa.

[Comparative Example 1]
This example is the same as that of the first embodiment except that the surface friction coefficient of the film is different.
The film of this example has a surface friction coefficient of 7.99 and a surface roughness (Rz) of 0.05 μm.

[Comparative Example 2]
This example is the same as that of the first embodiment except that the surface friction coefficient of the film is different.
The film of this example has a surface friction coefficient of 2.0 and a surface roughness (Rz) of 2.4 μm.
[evaluation]
The surface (film surface) of the vehicle interior parts manufactured in Example 1 and Comparative Examples 1 and 2 was confirmed. The evaluation results are shown in Table 1.

As shown in Table 1, no dents were observed on the surface of the vehicle interior parts manufactured in Example 1. On the other hand, in the vehicle interior parts manufactured in Comparative Examples 1 and 2, dents were confirmed on the surface. That is, in Example 1 in which the surface friction coefficient is smaller than a predetermined value, it was possible to manufacture an interior component for a vehicle in which the film (that is, the surface) does not have dents. On the other hand, in Comparative Examples 1 and 2 in which the surface friction coefficient was larger than a predetermined value, a dent was generated in the film (that is, the surface). From this, when the surface friction coefficient of the film is 2.00 or more, the film (the surface of the interior parts) is dented, and when it is less than the predetermined value (0.60), the film (the surface of the interior parts) is dented. It was found that it is possible to manufacture interior parts for vehicles that do not occur.

[Example 2]
This example is an example in which the second embodiment is concretely implemented. The same film and resin as in Example 1 were used.
As the molding die 3, a mold having a mold main body portion 30 made of high carbon steel and a surface portion 31 made of glass was used. The glass of the surface portion 31 is made of a plate-shaped (specifically, 2.0 mm) silica glass having a uniform thickness formed so as to cover the surface of the mold body portion 30. The glass surface 31a (cavity surface for design surface molding) of the surface portion 31 has a mirror surface. That is, the cavity surface for design surface molding is a smooth surface.
In the molding die 3, the thermal conductivity of the mold body 30 is 37 W / (m · K), and the thermal conductivity of the surface portion 31 is 0.65 W / (m · K).
As the resin, ABS resin was used. This resin was filled in the cavity under the conditions of an injection temperature: 240 ° C., an injection speed: 70 mm / s, and a holding pressure after filling: 15.5 MPa.

[evaluation]
The surface (film surface) of the vehicle interior parts manufactured in Examples 1 and 2 was observed. Moreover, the surface roughness (Rz) was measured. The evaluation results are shown in Table 2.

As shown in Table 2, in the vehicle interior parts manufactured in Examples 1 and 2, no dent was observed on the surface in any of the examples.

Further, it was confirmed that the surface of the interior component of Example 1 had a matte shape in which fine irregularities on the surface of the film remained. When the surface roughness (Rz) of the interior parts of Example 1 was measured, it was Rz 3.3 μm. As described above, the interior component manufactured in Example 1 has a mat-like surface (a matte state with reduced gloss) in which fine irregularities remain on the surface.

On the other hand, it was confirmed that the surface of the interior component of Example 2 was a smooth surface in which the fine irregularities on the surface of the film disappeared. When the surface roughness (Rz) of the interior parts of Example 2 was measured, it was Rz 0.05 μm. As described above, the interior parts manufactured in Example 2 have a smooth surface (a state in which the surface has a gloss).
As described above, according to the manufacturing method of the second embodiment, it is possible to manufacture a vehicle interior part having a smoother surface.

1: Measurement object 2: Measuring jig 3: Molding mold 30: Mold body 31: Surface 31a: Surface 4: Film 5: Resin G: Glass

Claims (4)

This is a method for manufacturing interior parts for vehicles, in which the surface of the film is in close contact with the cavity surface of the molding die, the cavity is filled with resin, and the film is molded to hold the pressure at 60 MPa or less.
The surface friction coefficient of the surface of the film is 1.0 or less, and the surface of the cavity surface is a mirror surface.
A method for manufacturing an interior component for a vehicle , wherein the surface of the film has a surface roughness (Rz) of 0.01 μm or more. The molding mold has a mold main body portion and a surface portion forming the cavity surface formed on the surface of the mold main body portion.
The method for manufacturing an interior component for a vehicle according to claim 1 , wherein the thermal conductivity of the surface portion is lower than the thermal conductivity of the mold main body portion. The method for manufacturing an interior component for a vehicle according to any one of claims 1 to 2 , wherein the resin is filled in the cavity at a temperature equal to or higher than the softening temperature of the film. The method for manufacturing an interior part for a vehicle according to any one of claims 1 to 3 , wherein the resin is a foamed resin.

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