JP2004322502A - Foamed resin core built-in frp and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the penetration of an injected resin into a core made of a foamed resin and to improve appearance and the creak sound caused by the bending of a molded object, in foamed resin core-built-in lightweight FRP. <P>SOLUTION: The foamed resin core built-in FRP is characterized in that the surface of the core made of the foamed resin is covered with a heat-shrinkable film and a fiber base material impregnated with a thermosetting resin is laminated on the core through the film. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an FRP with a built-in core of a foamed resin molded product which is lightweight and can be applied to, for example, a body part of an automobile, a bumper, a spoiler, and the like, and has excellent flexibility.
[0002]
[Prior art]
Conventionally, weight reduction of metal molding materials, especially various parts such as automobile bodies, bumpers, spoilers, etc., has been studied, but recently, resin moldings having both weight reduction and toughness have been developed. . For example, a core made of a foamed resin molded product made of polystyrene or the like is coated with a fiber base material such as a glass fiber or a carbon fiber, and then impregnated with a resin and cured to make a fiber reinforced plastic (hereinafter, referred to as FRP). After applying a thermosetting resin-based paint such as an unsaturated polyester resin, an epoxy resin, or a polyurethane, or a thermoplastic resin such as an acrylic resin to a surface of a bumper (Patent Document 1) or a foamed polyurethane core, and then drying and curing. A method of manufacturing an FRP product with a built-in foamed polyurethane core in which a thin resin layer formed is set in a mold together with a fiber base material, and a resin liquid for FRP is injected and cured (Patent Document 2).
[0003]
[Patent Document 1]
JP-A-2-215519 (Claim 1, FIGS. 1 to 4)
[0004]
[Patent Document 2]
JP-A-5-147048 (Claim 1, FIG. 1)
[0005]
[Problems to be solved by the invention]
However, the following problems have been encountered in the FRP having a core of a molded article made of a foamed resin proposed in Patent Documents 1 and 2 described above.
[0006]
That is, in Patent Literature 1, as described above, a foamed resin molded product is used as a core, and after covering the fiber base on the outside, the resin is impregnated and cured, but from the surface of the foamed resin core to the inside. Because the resin penetrates, the weight reduction is impaired, the surface of the product appears discolored due to permeation spots, and in extreme cases, unevenness is generated and the quality and gloss are significantly reduced, resulting in extremely high productivity. It was bad.
[0007]
On the other hand, in Patent Document 2, the disadvantage is improved, that is, a resin is applied to the surface of the foamed polyurethane core to prevent the resin injected through the fiber base material from penetrating into the polyurethane core. Certainly, the penetration into the interior may be prevented to some extent by selecting the resin layer forming material, but the layer formed by the coating film is insufficient in strength, and the resin injection of about 0.2 to 2 MPa is usually required. It is partially destroyed by pressure at the time and the like, and there is a possibility that the injected resin permeates the core. Further, when the injected resin and the thin resin layer covering the polyurethane core are not sufficiently bonded, when the product is subjected to gravity to bend, there is a problem that a squeak sound is generated.
[0008]
The present invention solves the above-mentioned problems of the prior art, prevents discoloration due to permeation into the core during resin impregnation and permeation spots, and suppresses the generation of squeak noise of the FRP molded body, thereby reducing the weight and improving the durability. It is an object of the present invention to provide a foamed resin core-incorporated FRP having both excellent flexibility and a method of manufacturing the same.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the foamed resin core-incorporated FRP of the present invention is a fiber substrate in which the surface of a foamed resin core is covered with a heat-shrinkable film, and the thermosetting resin is impregnated through the film. Are laminated.
[0010]
Further, in order to solve the above problems, the method for producing a foamed resin core-embedded FRP of the present invention comprises covering the surface of a foamed resin core with a heat-shrinkable film via a heat bonding layer, and subjecting the coated material to a reduced pressure. The film is covered with a fiber substrate, and then set in a cavity of a molding machine, and a thermosetting resin is injected and cured.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail.
[0012]
The foamed resin core used in the FRP of the present invention is a molded article made of a foamed resin forming the core of the FRP of the present invention, and the molded article is a foam made of polyurethane, polystyrene, polyolefin, or the like, It is manufactured by a general manufacturing method and has closed or open cells. The expansion ratio is not particularly limited, but is preferably as high as possible for the purpose of weight reduction. In consideration of the balance with the strength of the molded body, the expansion ratio is preferably about 5 to 20 times.
[0013]
The method of foam molding is not particularly limited, and it can be molded by a conventionally known method. For example, in addition to carbon dioxide, freon, methylene dichloride, pentane, air, and the like, a thermal decomposition type organic foaming agent and the like can be applied. In particular, a method of manufacturing by encapsulating carbon dioxide gas by-produced by the reaction between a polyol such as polyurethane and an isocyanate is preferable in that simple and uniform foaming is possible. As such a molding method, a one-shot method and a prepolymer method are generally known. The core used in the present invention is preferably a semi-rigid or rigid foam.
[0014]
By the way, as described above, the FRP with a built-in core of the present invention is characterized in that the surface of the foamed resin core is covered with a heat-shrinkable film.
[0015]
As such a heat-shrinkable film, for example, a polyester film, a polypropylene film, a polyethylene film, a polystyrene film, a vinyl chloride film, a nylon film, and the like can be selected, and the nylon film is flexible, tough, and heat-resistant. Is particularly preferred.
[0016]
Hereinafter, a nylon film will be described as a preferable representative example of the heat-shrinkable film of the present invention, but it is needless to say that the present invention is not limited to this.
[0017]
The nylon film is not particularly limited, but any one of nylon 6, nylon 12, nylon 11, 6-6 nylon, 6-10 nylon, and the like can be used. There may be. The melting point needs to withstand the curing temperature during the impregnation of the thermosetting resin, and is usually preferably 150 ° C. or higher.
[0018]
As the heat-shrinkable nylon film, any film of uniaxial stretching and biaxial stretching (including sequential or simultaneous biaxial stretching) can be used. For example, a typical example is Unilon S300 (manufactured by Idemitsu Unitech Co., Ltd.). ), Emblem NK (produced by Unitika Ltd.), Boneal SW (produced by Kojin Co., Ltd.), Super Neal SP-R.SH (produced by Mitsubishi Plastics Corp.), and the like. The heat shrinkable film has a shrinkage ratio of 5 to 40%, preferably 10% to 30%, and more preferably 15% to 25% when immersed in 95 ° C. hot water for 30 minutes. If it is less than 5%, the fit to the core may be poor depending on the shape of the core, and if it exceeds 40%, the core may be deformed by shrinkage stress. The thickness of the heat-shrinkable film is preferably 3 μm or more and 75 μm or less. If it is less than 3 μm, the strength may be insufficient, and it may be broken by the coating process or the pressure at the time of injection of the thermosetting resin described later. If it exceeds 75 μm, it may not follow the core well and the surface condition of the product may be deteriorated. is there. The surface of the heat-shrinkable film is preferably subjected to a corona treatment in air, nitrogen, carbon dioxide, or the like, from the viewpoint of adhesion to a thermosetting resin to be injected. The treatment may be on one side or on both sides, but it is preferable that the side in contact with the thermosetting resin is a corona-treated surface from the viewpoint of adhesiveness. By performing such a treatment, higher adhesiveness between the heat-shrinkable film and the thermosetting resin can be exhibited, and squeak noise when gravity is applied from above the FRP can be suppressed. . The adhesive strength between the heat-shrinkable film and the thermosetting resin-impregnated fiber base material is desirably 100 g / cm or more, preferably 200 g / cm or more at 180-degree peeling. A high adhesive strength can be exhibited. When coating the surface of the foamed resin core with the heat-shrinkable film, the purpose of the coating is to prevent the penetration of the thermosetting resin into the foamed resin molded article, and a coating for preventing the penetration is required.
[0019]
Such a coating method is not particularly limited, but it is preferable that the core material is adhered to the core material in a process until the core material is coated with the fiber base material and the thermosetting resin. It is possible to apply a method of performing a surface treatment and coating the heat-shrinkable film, a method of coating the adhesive film on at least one surface of the heat-shrinkable film with the adhesive side of the composite film in which the adhesive is laminated on the core side, and the like. it can. In particular, if an adhesive layer which is non-adhesive at room temperature and expresses adhesiveness by heat is provided, when the core is simply coated with a film, the films do not stick to each other, but are heated and shrunk to fit the core. This is a preferred form because it adheres to the substrate. As such an adhesive, a hot-melt type adhesive is preferable, and for example, polyester-based, acrylic-based, polyamide-based, polyolefin-based and copolymers thereof, modified products, ionomers and the like can be used. Those having a softening point are preferred. When the heat-shrinkable film is a nylon film, it is laminated with a copolyamide film (for example, a film type for heat bonding CF8000: manufactured by Toray Gosei Co., Ltd.), and Admar NF series, HB series, and LF which are modified polyolefin-based adhesive polymers. What laminated | stacked with the nylon film by lamination | stacking with series, LB series, VF series (made by Mitsui Chemicals, Inc.) etc. can be used preferably. The thickness of the adhesive layer is not particularly limited, but is preferably 1 μm or more and 50 μm or less, preferably 3 μm or more and 30 μm or less, more preferably 5 μm or more and 20 μm or less from the viewpoint of fitting to the core material and maintaining the adhesiveness with the core material. desirable. In addition, it is necessary to prevent the thermosetting resin from penetrating through the gap of the heat-shrinkable film when the thermosetting resin is injected, and it is necessary to apply a method such as repairing the film bonding portion with an adhesive or an adhesive tape. preferable.
[0020]
Considering the heat generated by the curing of the thermosetting resin, the base material of the adhesive tape is preferably a film having a melting point of 170 ° C. or higher, and polyester, nylon, and the like are preferable. The pressure-sensitive adhesive layer is preferably a heat-resistant material such as an acrylic or silicone material. The simple coating may be performed by a usual method such as winding. However, a method in which the simply coated core is placed in a plastic film bag and the inside is evacuated to fit the core is particularly preferable. The core coated with the heat-shrinkable film is heated at 80 ° C. to 130 ° C. to adhere the heat-shrinkable film to the core and at the same time to fit the shape of the core by shrinkage. When the shape of the core is complicated, heat treatment is performed in a state where the concave portion is held by a jig, so that the shape can be fitted according to the shape.
[0021]
The foamed resin molded article covered with a heat shrinkable film is covered thereon with a thermosetting resin-impregnated fiber base material. The fiber base material used for this is not particularly limited, and heat-resistant high-strength fibers such as glass fiber, carbon fiber, aramid fiber, ceramic fiber, and metal fiber are preferable. It can be used preferably from the balance.
[0022]
The thermosetting resin is not particularly limited, but an epoxy resin, a melamine resin, a urea resin, an unsaturated polyester resin, a phenol resin and the like can be used. Particularly, an epoxy resin is preferable from the viewpoint of moldability, curability, adhesion to a coating film, and the like. In order to thermally cure the epoxy resin, it is preferable to use a curing agent in combination. Acid anhydrides such as hydrophthalic anhydride, dodecenyl succinic anhydride, chlorendic anhydride and methyl nadic anhydride are preferred, and acid anhydrides are particularly preferred in view of heat resistance and the like.
[0023]
The coating with the fiber base material may be a single layer, or may be two or more layers depending on the purpose and application. The strength of the FRP can be improved by increasing the number of layers.
[0024]
Next, a method for manufacturing the FRP with a built-in foamed resin core of the present invention will be described.
[0025]
First, using the foamed resin molded product (core), the heat-shrinkable film, and the fiber base material, a composite laminate having a stacking order of “foamed resin core / heat-shrinkable film / fiber base material” is prepared. . Although a specific method of forming the laminate is as described above, the description is omitted. In the step of coating the foamed resin core with a heat-shrinkable film, the core surface is coated with a heat-shrinkable film via an adhesive. The simply coated coating is heat shrunk under reduced pressure. Specifically, the coating is placed in a bag made of polyethylene, polypropylene, polyester, nylon, or the like, the inside of the bag is depressurized, and a heat-shrinkable film is fitted to the surface of the core. The degree of the pressure reduction may be determined in a state where the heat-shrinkable film fits the core, but it is usually sufficient to heat the film at a temperature of 80 to 130 ° C. in a reduced pressure atmosphere of about 100 to 30,000 Pa. Due to the shrinkage of the film, the fit to the core and the adhesion to the core are improved, and the effect of improving the appearance and the squeaking sound in FRP is produced.
[0026]
Next, a composite molded article is prepared in which the fiber base is coated on the film surface of the coated molded article taken out of the bag.
[0027]
When the composite molded body is obtained, in order to perform injection curing of the thermosetting resin, the composite molded body is set in a cavity of a predetermined mold, and the above-described thermosetting resin is injected from an end. The injection pressure needs to be such that the resin uniformly spreads over the entire mold, and can be arbitrarily set depending on the viscosity of the resin and the shape of the composite laminate, but is usually 0.2 to 2 MPa, preferably 0 to 2 MPa. It is preferably in the range of 0.3 to 1 MPa, more preferably 0.3 to 0.7 MPa. In this case, the temperature of the mold is preliminarily heated, but the specific temperature is preferably set according to the type of the thermosetting resin to be used. For example, in the case of an epoxy resin, 80 ° C. to 150 ° C. It is preferable that the temperature be as low as possible in view of the heat-resistant dimensional stability of the foamed resin molded product.
[0028]
Next, heating is performed for an appropriate time for thermal curing of the injected resin. The heating time can be arbitrarily set depending on the type of the thermosetting resin, but is usually preferably in a range of 3 minutes to 60 minutes. After curing is completed, the molded product is removed from the mold to obtain a completed FRP product with a built-in foamed resin core of the present invention.
[0029]
The foamed resin core built-in FRP thus obtained can prevent the thermosetting resin embedded in the outside from penetrating into the core, and has excellent adhesion between the thermosetting resin and the heat-shrinkable film. It is excellent in both the weight reduction and the durability of the FRP, which are the original functions of the foam. For example, it should be lightweight and excellent in bending resistance applicable to automobile body parts, bumpers, spoilers, etc. it can.
[0030]
【Example】
The present invention will be described below with reference to examples, but is not necessarily limited thereto. First, the method for measuring the characteristics and the method for evaluating the effect of the core built-in FRP of the present invention were as follows.
[0031]
[Method of measuring characteristics and evaluating effect]
(1) Decompose FRP after completion of adhesive force molding between thermosetting resin-impregnated fiber base material and nylon film, take out thermosetting resin-impregnated fiber and nylon film composite part, and peel 180 degrees with Tensilon type tensile tester Was measured. The pulling speed was 200 mm / min.
[0032]
(2) Fitting of Film to Foam Core The occurrence of wrinkles on the flat portion in the state of film coating on the foam molded article was visually observed.
[0033]
(3) Inspection of appearance of FRP molded body The appearance of FRP after completion of molding was visually observed to evaluate spots of color and surface shape.
[0034]
(4) Inspection of Penetration of Thermosetting Resin into Foamed Molded Body The cross section of the FRP after completion of molding was cut out, and the state of penetration into the foamed portion on the surface of the foamed body was observed with a 100-fold optical microscope.
[0035]
(5) The amount of deformation at which squeak noise was generated when the molded article was flexed was evaluated. The amount of deformation was defined as 0 when no load was applied to the center of the molded body, and the pressing depth at which a squeak sound was generated when the molded body was gradually deformed by applying a load was measured.
[0036]
"Example 1"
Using a polyurethane molded core (width 250 mm × length 700 mm × thickness 30 mm) foamed about 10 times, spray glue 55 (manufactured by Sumitomo 3M Ltd.) is sprayed on the surface of the core, and the room temperature is maintained at room temperature for 2 minutes. Let dry. Next, a non-corona-treated surface was affixed to the surface of the core using a biaxially stretched heat-shrinkable nylon film (Emblem NK: manufactured by Unitika Ltd.) having a thickness of 15 μm and having one surface subjected to corona treatment. The end was wrapped with the above nylon film so that the core was not exposed, and an adhesive tape made of polyester was attached. This was put into a 15 μm-thick polyethylene bag, and the inside of the bag was depressurized by a vacuum pump so that the inside of the bag became a reduced pressure atmosphere of about 4000 Pa from the end. This simple coating was immersed in hot water at 90 ° C. for 3 minutes. Thereafter, the inside of the bag was returned to normal pressure, and the molded body covered with the nylon film was taken out of the polyethylene bag. Although wrinkles were observed at the ends of the molded product, the nylon film fit the core at the flat portions, and had a clean surface free of wrinkles. The molded product was wrapped with a carbon fiber base cloth on a nylon film, and then set in a mold of a resin injection molding machine heated to 80 ° C. A mixture of an epoxy resin and phthalic anhydride was injected at an injection pressure of 0.5 MPa from the end, and then heated to 120 ° C. and cured for 30 minutes. Then, it cooled to about 40 degreeC, opened the molding machine, and took out the molded product from the metal mold | die. This molded product had a very beautiful appearance, had no permeation of epoxy resin into the core portion, and had high adhesiveness (1 kg / cm or more). In addition, no squeak sound was generated even in the case of the bending deformation of 20 mm.
[0037]
"Comparative Example 1"
Next, a molded body made of FRP was prepared in the same manner except that the nylon film of Example 1 was not used. In this molded article, spots were observed in the color of the appearance, and dents were partially observed. In addition, permeation of the epoxy resin into the inside of the foam was observed by cross-sectional observation.
[0038]
"Comparative Example 2"
Instead of the nylon film of Example 1, toluene / ethyl acetate (70%) was obtained by adding 25 parts by weight of a polyisocyanate (Coronate L: manufactured by Nippon Polyurethane Co., Ltd.) to 100 parts by weight of a polyester resin (Vylon 200: manufactured by Toyobo Co., Ltd.). / 30% by weight), and applied to the surface of the urethane foam core so that the thickness after drying was about 15 μm. Drying was performed at 120 ° C. for 10 minutes. Except for this, a molded body was prepared in the same manner as in Example 1.
[0039]
From the cross-section observation of this molded product, the epoxy resin penetrated into the foam was observed, and the appearance of color spots and concave defects on the surface were observed.
[0040]
"Example 2"
A molded body was produced in the same manner as in Example 1 except that a heat-shrinkable polyester film was used instead of a heat-shrinkable polyester film, and a space-clean SC-B (manufactured by Toyobo Co., Ltd.) was used. Created. As in Example 1, this molded article was excellent in fit to the core after heat shrinkage, and also excellent in appearance, adhesiveness, and deflection resistance of the molded article.
[0041]
"Example 3"
Admer LF300 (manufactured by Mitsui Chemicals, Inc.) was laminated as an adhesive polyolefin to a thickness of 12 μm on one surface of the nylon film of Example 1 by an extrusion lamination method. The film was coated so that the laminated surface of the film was on the core side, and then a 12 μm-thick Lumirror P60 (manufactured by Toray Industries, Inc.) was used as a decompression treatment bag. At 120 ° C. for 5 minutes. Thereafter, a molded body was prepared in the same manner as in Example 1.
[0042]
This molded product was excellent in the fit to the core, the appearance of the molded product, and the adhesiveness, and had no squeaking noise even with a deformation amount of 30 mm. Also, the adhesion between the foam core and the nylon film was excellent.
[0043]
"Comparative Example 3"
Example 2 Example 2 was repeated except that the heat-shrinkable polyester film of Example 2 was replaced with a polyester film having a heat shrinkage of 2% or less at 150 ° C. for 30 minutes (Lumirror P60 having a thickness of 12 μm, manufactured by Toray Industries, Inc.). A molded body was prepared in the same manner as in the above. This molded product had insufficient fit during the film coating process and had many wrinkles on the surface.
[0044]
The appearance of the molded body was good, but a squeak sound was generated due to the deformation of 10 mm.
[0045]
【The invention's effect】
According to the present invention, in the FRP with a built-in foamed resin core, the core surface is covered with the heat-shrinkable film, so that the injected resin does not penetrate into the inner foamed core, so that discoloration does not occur. In addition, since the adhesiveness between the injected resin and the heat-shrinkable film is high and the fit between the core and the film is excellent, the FRP with a built-in foam resin core that is lightweight, has excellent appearance, and does not generate squeak noise due to bending is used. Obtainable.

Claims (6)

An FRP with a built-in foamed resin core, wherein a surface of a foamed resin core is covered with a heat-shrinkable film, and a fiber base material impregnated with a thermosetting resin is laminated via the film. 2. The foamed resin core-incorporated FRP according to claim 1, wherein the 180-degree peel adhesion between the heat-shrinkable film and the fiber base material impregnated with the thermosetting resin is 100 g / cm or more. The FRP with a built-in resin core according to claim 1 or 2, wherein the heat-shrinkable film is a nylon film. The foamed resin core-incorporated FRP according to any one of claims 1 to 3, wherein the heat-shrinkable film has a shrinkage rate of 1% per minute in 95 ° C hot water of 5% or more and 50% or less. The foamed resin core-incorporated FRP according to any one of claims 1 to 4, wherein an adhesive layer exhibiting adhesiveness by heating is laminated on at least one surface of the heat-shrinkable film. The surface of the foamed resin core is coated with a heat-shrinkable film via a heat-adhesive layer, and the coated material is heat-shrinked under reduced pressure. A thermosetting resin is injected and hardened, and the FRP with a built-in core made of foamed resin is manufactured.