JP2011230341A - Method for manufacturing composite molded object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently manufacturing a template which is almost free from warpage or torsion, at a low cost, with regard to the template to be used when a housing cladding material of a ceramics system bearing an uneven pattern as a design on the surface is manufactured.SOLUTION: This method is for manufacturing the composite molded object of foam core sandwich structure, which is integrally formed of a surface layer part constituted of a fiber-reinforced resin layer containing a reinforcement fiber material 9, a core part of an expanded particle-containing resin layer which contains an expanded particle and a separation layer 11 existing between the surface layer part and the core part. In addition, the surface layer part with an uneven pattern which is formed on the surface layer part of two upper/lower layers, includes arranged non-inflatable expanded particles 8. Thus, the composite molded object can inhibit the generation of warpage or torsion, and exhibits such excellent durable physical strength that the formed uneven pattern is not susceptible to deformation and also, is highly wear-resistant. Besides, the composite molded object shows an inhibitory effect on the development of voids or pinholes.

Description

The present invention relates to a method for producing a composite molded product having a core part made of a foamed particle-containing resin layer between surface layer parts made of a fiber reinforced resin layer (FRP) and integrated as a whole.
More specifically, it is integrally molded so that a core part composed of a foamed particle-containing resin layer in which countless foamed particles are closely packed between two dense upper and lower surface layer parts formed of a fiber reinforced resin layer (FRP). A lightweight and strong foam core sandwich structure plate-like composite molded product, which is used as a template to give a pattern of uneven design as a design to the surface of ceramic housing exterior materials. The present invention relates to an efficient and low-cost manufacturing method.

Lightweight foam core / sandwich composite products with a surface layer part made of fiber reinforced resin layer (FRP) and a core part made of foamed particle-containing resin layer are excellent in light weight and toughness. There are wide applications such as transportation equipment members such as ships, various structural materials, construction members, interior and exterior members, substrates and housings for medical equipment and telecommunications equipment, sports equipment, and panels for containers.

As a method for producing a composite molded article having such a foam core / sandwich structure, expandable particles are obtained by using expandable expanded particles (or a mixture of the particles and non-expandable expanded particles) and a liquid molded resin as a core forming material. A method has been proposed in which a composite molded article composed of a core portion made of a resin composition and a surface layer portion of a fiber reinforced resin (FRP) is molded all at once (Japanese Patent No. 1981141).
In this method, a reinforcing fiber sheet and a separation membrane are installed in a mold for molding, and a mixture of expandable foam particles and liquid molding resin is supplied in a layer form on the reinforcing fiber sheet, and further on the separation membrane. And after covering with a reinforcing fiber sheet and closing the mold, the expandable foam particles are expanded by heating the mold, and the liquid molding resin is used for reinforcing the upper and lower sides by utilizing the pressure generated in the mold. This is a method for producing a composite molded article having a foam core / sandwich structure by infiltrating a fibrous sheet and then curing.

According to this method, a lightweight and tough material having a core part made of a foamed particle-containing resin composition containing countless foamed particles between dense surface layer parts made of fiber reinforced resin (FRP) and integrated as a whole. Efficient composite molded articles are produced efficiently.

Japanese Patent No. 1981141 Japanese Patent No. 2996788 Japanese Patent Laid-Open No. 08-276524

The conventional method of molding using expandable expanded particles has the advantage that a composite molded article having a foam core / sandwich structure can be molded in one step.
On the other hand, when manufacturing a template used for producing ceramic-type housing exterior materials with a concavo-convex pattern as a design on the surface from a composite molded product having a foam core / sandwich structure by a conventional method, Immediately after manufacturing or during the long-term use of this template, there has been a problem that defects such as warping and twisting occur in the template.
On the molding surface of the above template, there is a need to faithfully reproduce an uneven pattern as a complex design rich in design such as a stone pattern on the surface of a housing exterior material. On the other hand, the back surface of the template corresponding to the back side of the molding surface is required to be a substantially smooth surface. That is, the surface shape is different between the molding surface on which the concavo-convex pattern is formed and the substantially smooth back surface.
The above stencil is made of a material that can withstand the harsh conditions required when manufacturing ceramic-type housing exterior materials, that is, an alkaline high-humidity atmosphere and a molding pressure exceeding 50 kg / cm 2. There is also a small dimensional accuracy, little dimensional change due to temperature and humidity changes, sharpness of uneven patterns, and defects formed by bubbles when molding templates such as voids and pinholes In addition, various types of performance are required for the templates used for ceramic housing exterior materials, such as durability and wear resistance that can withstand long-term use including pattern collapse. Therefore, there has been a demand for a manufacturing method for efficiently and inexpensively producing a template with less warping and twisting after satisfying these required performances.

Therefore, a first object of the present invention is to provide a method for industrially advantageously molding a composite molded article having a foam core / sandwich structure in which the occurrence of warpage and twisting is suppressed. In particular, an object of the present invention is to provide a method for producing a composite molded article having a foam core / sandwich structure which is suitably used for a template of a ceramic exterior housing material.

The second object of the present invention is a template for producing a housing exterior material, which can faithfully reproduce a complicated uneven pattern rich in design such as a stone pattern formed on the design surface of the housing exterior material. Even though the ruggedness pattern is formed, even if the environmental conditions are severe, it is a composite molding of foam core / sandwich structure with ruggedness pattern that has excellent physical strength and durability without deformation. It is an object of the present invention to provide a manufacturing method for industrially molding a product.

A third object of the present invention is to provide a method for producing a composite molded article having a foam core / sandwich structure having a concavo-convex pattern having no voids or pinholes.

The present invention was invented as a production method suitable for a composite molded article having a foam core / sandwich structure used for a ceramics housing exterior material template, but the present invention is applied to a ceramics housing exterior material template. Regardless of field, the surface has a concavo-convex pattern on the surface, but the back surface has no concavo-convex pattern, and is a smooth and flat plate-shaped composite that is lightweight and rigid. It is an invention that provides a method for efficiently producing a molded article.

The present invention exists in a surface layer portion comprising a fiber reinforced resin layer containing a reinforcing fiber material, a core portion comprising a foamed particle-containing resin layer containing foam particles, and between the surface layer portion and the core portion. A method for producing a composite molded article having an integrated foam core / sandwich structure comprising a separating layer,
In particular, in the two upper and lower surface layer portions, the surface of one surface layer portion has a concavo-convex pattern, the surface of the other surface layer portion has a substantially smooth surface, and the concavo-convex pattern is further formed. The surface layer portion is characterized by containing non-expandable expanded particles.

As described above, in the method of the present invention, the thermosetting liquid molding resin that has passed through the separation layer from the core portion is used as the resin composition of the surface layer portion having a concavo-convex pattern formed on the surface, and further the conventional reinforcement. Since the fiber reinforced resin layer is formed using non-expandable foam particles in addition to the fiber material, the non-expandable foam particles also enter the narrow part of the surface layer where the uneven pattern is formed when pressure is applied during molding The
As a result, in addition to compensating for volume shrinkage in the curing process of the liquid molding resin, the bearing effect of the non-expandable foam particles can provide a molded product in which a good uneven pattern without voids or pinholes is formed, Further, it becomes possible to mold the molding material in a state of being pressed against the inner wall surface of the molding die by the repulsive force of the expandable foam particles in the core portion, and a molded product having more excellent surface properties can be obtained.
Furthermore, by adding non-expandable foam particles to the surface layer portion on which the concavo-convex pattern is formed, the shrinkage rate imbalance due to the difference in surface shape from the surface layer portion on which the substantially smooth surface is formed is eliminated. Therefore, it is possible to obtain a high-quality molded body free from warping, twisting and cracking.

Thus, the foam core / sandwich structure composite molded article formed by the method of the present invention and having a surface with a concavo-convex pattern formed thereon and a substantially smooth back surface is lightweight and tough, yet has voids, pinholes, etc. We offer a manufacturing method that can suppress the occurrence of warpage, which has been a problem in the past, because it has excellent surface appearance and high surface hardness. The above effect is suitable as a template for ceramic exterior housing materials, but the surface on which the concavo-convex pattern was formed and the substantially smooth back surface were formed even if it was not a ceramic exterior housing template. The composite molded product having a plate-like foam core / sandwich structure can be widely used in various applications where the occurrence of warpage is suppressed and a light-weight and rigid composite molded product is required.

The schematic diagram of the laminated body before an expandable expanded particle foams. FIG. 3 is a schematic view of a laminate in which expandable foam particles are expanded, and a liquid molding resin passes through a separation membrane and permeates around the reinforcing fiber material and non-expandable foam particles in the surface layer portion.

BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out the present invention will be specifically described below, but these are for explaining the present invention, and the present invention is not limited by these examples.

First, the main molding material used in the method of the present invention, that is, the reinforcing fiber material, the separation membrane used for the separation layer, expandable foam particles, non-expandable foam particles, liquid molding resin, release sheet, and as necessary Various materials and molds used in an auxiliary manner will be described.

[Molding mold]
In the method of the present invention, a mold for molding is first prepared. This mold is appropriately selected from a mold, a wooden mold, a resin mold and the like according to the molding temperature. This mold usually consists of a combination of an upper mold and a lower mold, and the upper mold has a smooth surface, whereas the lower mold forms a design surface with an uneven pattern on the surface of a housing exterior material. The cavity is formed.
Since the molding surface of the upper die only needs to be a substantially smooth surface, the upper platen may be used as the upper die if the portion corresponding to the molding surface of the upper platen of the press is smooth. Alternatively, an upper mold having a substantially smooth surface may be fixed to the upper surface plate.

[Reinforcing fiber materials]
The reinforcing fiber material used as one of the main molding materials in the method of the present invention includes a reinforcing fiber sheet made of reinforcing fibers. Examples of the reinforcing fiber include glass fiber, carbon fiber, silicon carbide fiber, metal fiber, aramid fiber, polyarylate fiber, high-strength polyolefin fiber, and a mixed fiber of two or more of these. In addition to these fibers, polyester fibers, polyamide fibers, polyvinyl alcohol fibers, rayon fibers, natural fibers, and the like can also be used. Among them, it is preferable to use a high-strength, high-modulus fiber such as glass fiber, carbon fiber or para-aramid fiber.

As the form of the reinforcing fiber sheet, the above-mentioned fibers are made of woven fabric (plain weave, twill weave, suede weave, etc.), knitted fabric, non-woven fabric, mat, paper, roving, etc. gathered in a unidirectional alignment layer. The one in the form of is used. These may be used alone or in combination of two or more. In addition, this fibrous sheet can also be supplied as a prepreg impregnated with a liquid molding resin in advance.

[Separation membrane]
In the method of the present invention, as will be described later, from the liquid molding resin and expanded particles (expanded expanded particles alone or mixed particles of expanded expanded particles and non-expanded expanded particles) present in the core portion by pressing during molding. The liquid molding resin is squeezed out of the foamed particle-containing resin layer, and penetrates into the upper and lower reinforcing fiber sheets, and a part thereof reaches the upper and lower surfaces. At this time, the movement of the particles is prevented so that the foamed particles do not enter the reinforcing fiber sheet, and only the resin is selectively moved to the upper and lower surface portions to form a dense and good surface portion. This is necessary above and this part is called the separation layer. This separation layer not only does not pass the foam particles in the core part to the surface layer part, but also moves the non-expandable foam particles in the surface layer part to the core part.

For this reason, as a separation layer, the membrane (this book) which has a separation function which does not let a foam molding particle pass, but lets a liquid molding resin pass to the surface (core part side) which touches a foam particle content resin layer in the upper and lower reinforcing fiber sheets, respectively. In the invention, they are arranged so as to be attached.

As the separation membrane interposed between the upper and lower reinforcing fibrous sheets and the foamed particle-containing resin layer, a thin fibrous sheet and / or a porous sheet having a small mesh size are used. Specific examples of such a fibrous sheet include woven fabrics, knitted fabrics, non-woven fabrics, braids, papers, and the like made of various natural fibers, synthetic fibers, inorganic fibers, and the like. Specific examples of the porous sheet include continuous air holes. A porous film or the like obtained by stretching and extracting a foam sheet such as polyurethane, polystyrene, or polypropylene, or a sheet such as polyethylene, polypropylene, or polysulfone is used.

The opening of the separation membrane is appropriately selected according to the type and size of the expanded particles. Further, as a material for the separation membrane, a material having stretchability can be selected so that it can be easily matched to the shape of the molded product. A part of the separation membrane may be made of a material that does not allow liquid molding resin to pass through. For example, a part made of a material having a separating function and a part made of a material having a different function are joined together, and a part of a sheet-like material having a separating function is sealed with a resin or the like in advance. Treated, the fibrous sheet is a polypropylene fiber sheet, and the part that can be fused is partially fused by heat treatment to crush some openings, and part of the material having a separation function What stuck the non-porous film etc. may be used.

As the separation membrane, a fibrous sheet having a small mesh opening made of glass fiber, carbon fiber, aramid fiber or the like, which itself has a function as a reinforcing material, can also be used. In this case, this fibrous sheet can be used both as a reinforcing fibrous sheet and a separation membrane. However, if the reinforcing fiber sheet and the separation membrane are separately arranged, the opening of the reinforcing fiber sheet can be freely selected. For example, a unidirectional fiber array prepreg or a three-dimensional knitted fabric knitted fabric can be selected. Reforms and the like can also be used as the reinforcing fiber sheet, and a material according to the appearance and characteristics required for the surface of the molded product can be arbitrarily selected, which is preferable.

For example, a thin long-fiber nonwoven fabric with a small mesh marketed under a trade name such as “Unicel” is excellent in many aspects such as separation function and handleability, and is particularly suitable as a separation membrane.

[Foamed particles]
As the expanded particles, non-expandable expanded particles and expandable expanded particles are used.
Non-expandable foam particles are used as the foam particles used for the surface layer portion that forms the uneven pattern portion.
As the expanded particles used for the core, expandable expanded particles alone or a mixture of expandable expanded particles and non-expandable expanded particles is used.

[Expandable expanded particles]
The expandable foam particles used here have a volume that increases by at least 2 times, preferably 3 to 6 times, more preferably 6 times or more due to foaming, and does not dissolve in the liquid moldable resin used for molding. Is. Further, a foamed foam is used so that the liquid resin does not enter the foaming space.

Examples of such expandable foam particles include curable foams such as polyurethane, phenol, polyurea, melamine, polyimide, and precursors thereof, polyvinyl chloride, polyvinylidene chloride, polyacrylonitrile, polystyrene, polyethylene, polypropylene, PPO, polyamide, Examples thereof include thermoplastic resins such as polycarbonate, PBT, and polyimide.

Particularly preferred as expandable expanded particles are thermally expandable resin particles containing a thermally expandable or expandable substance known by trade names such as “microsphere”, “expanscel”, and “eslen beads”. .

[Non-expandable foam particles]
The non-expandable foamed particles are light-weight particles that do not substantially change in shape or size in a series of processes of the method for producing a composite molded article of the present invention and that contain hollow or bubbles.
Specific examples of such non-expandable expanded particles include inorganic hollow particles called “glass balloon”, “silica balloon”, “shirasu balloon” and the like, and hollow resin particles obtained by pre-expanding expandable expanded particles. It is done.
The hollow resin particles obtained by pre-expanding the expandable foam particles are different from the inorganic hollow particles having the property of rigidity in that they are compressed and deformed by the pressure applied during molding.

As the non-expandable foamed particles used for the surface layer portion having the concavo-convex pattern surface, inorganic hollow particles are preferably used. Among them, hollow glass beads made of glass hollow bodies have the characteristics described below. It is a non-expandable expanded particle suitable for forming an uneven pattern on the surface of a composite molded product.
(1) The hollow glass beads have a low specific gravity of 0.25 to 0.8, and by adding the hollow glass beads to the fiber reinforced resin layer of the surface layer portion having the concavo-convex pattern surface, the surface layer portion having the concavo-convex pattern surface Can be reduced in weight. Furthermore, the elastic modulus of the fiber reinforced resin layer is increased to give rigidity.
(2) Hollow glass beads with high roundness have good fluidity due to the bearing effect, and flow resistance is very small compared to fibrous fillers such as glass chopped strands. However, without impairing the fluidity of the resin, the fluidity of the liquid molding resin passing through the separation layer from the core and entering the surface layer is ensured, and the self-leveling effect is enhanced to improve the moldability.
(3) Since spherical fillers with high roundness such as hollow glass beads have no directionality, due to residual strain, such as fibrous fillers such as glass chopped strands in which tensile stress remains in the longitudinal direction of the filler. Deformation, warpage and cracking are unlikely to occur. Furthermore, since it is a spherical isotropic filler, deformation, warpage, and cracks due to anisotropic shrinkage can be prevented.
(4) By adding hollow glass beads to the surface layer portion, rigidity is imparted to the resin layer of the surface layer portion. As a result, deformation of the uneven pattern is prevented, and wear resistance is also improved.

[Liquid molding resin]
On the other hand, the liquid molding resin mixed with the foamed particles may be a thermosetting resin used in normal molding, for example, an epoxy resin, a polyurethane resin, an unsaturated polyester resin, a polyvinyl ester resin, an acrylic urethane resin, a phenol resin, Acrylic resin, poly (dicyclopentadiene) resin, petroleum resin, or the like can be used. Among these, epoxy resins, unsaturated polyester resins, vinyl ester resins, phenol resins and the like are preferable thermosetting resins. These thermosetting resins are usually used as a curable resin composition together with necessary curing agents or initiators, curing accelerators, diluents and the like.

The blending ratio of the expanded particles and the liquid molding resin in the method of the present invention varies depending on the density and toughness of the molded product to be obtained, ease of molding, etc., but generally ranges from 1/100 to 10/100 in terms of weight ratio. Is preferred.

In the method of the present invention, carbon, silicon carbide, titanic acid is used as a material that can be used as an auxiliary material for forming the porous core portion together with the foamed particles and the liquid molding resin in order to improve the mechanical properties of the molded product. Short fibers such as potash, boron and aramid, and fibers shorter than 6 mm such as whiskers can be added.

[Release sheet]
Further, the surface between the surface layer portion having a substantially smooth surface and the upper die, and the surface not contacting the separation membrane in the reinforcing fiber sheet disposed on the surface layer portion side having the substantially smooth surface (that is, the molded product) By disposing the release sheet along the outer side and performing pressure molding, it is possible to improve the surface property of the substantially smooth surface of the composite molded product and the mold release property between the composite molded product and the upper mold.

As the releasable sheet, a flexible film of a type that can be easily peeled off from the smooth surface of the surface layer portion having a substantially smooth surface after molding is suitable, and the releasable sheet is removed from the composite molded product after molding. As a result, it is possible to improve moldability and surface properties and further improve productivity.
Examples of the release sheet used here include flexible films such as polypropylene, nylon, and fluororesin.

By using the release sheet, the upper surface plate of the press can be molded as a substitute for the upper die without using the upper die.

In the method of the present invention, for the purpose of improving the mechanical properties of the composite molded article, particularly the rigidity against bending load and further preventing warpage and twisting, reinforcing materials may be installed locally at appropriate intervals in the surface layer portion, This is often preferred depending on the form and use of the composite molded product. Examples of reinforcing materials that are partially installed in the surface layer include braids, ropes, blades, rods, corrugated materials, honeycombs, etc., and the materials used are glass, aramid, polyester, nylon, cellulose, etc. However, a glass fiber braid is particularly preferable. Further, if glass fibers such as powder, chopped strands, and fibers are arranged on the surface layer portion having a substantially smooth surface, it is effective in preventing warpage and twisting.

[Molding Method] According to the method of the present invention, each of the above molding materials is prepared, and the following steps (a) to (f) are sequentially performed to obtain a composite molded article having a desired foam core / sandwich structure. Manufacturing.
(A) A foamed particle-containing resin preparation step of preparing a foamed particle-containing resin composition comprising a liquid molding resin and foamed particles, wherein the foamed particles are expandable foam particles alone, or expandable foam particles and non-expandable foam particles Either of the mixed particles are used,
(B) a non-expandable foam particle adjustment step in which non-expandable foam particles are arranged on the molding surface of the lower mold forming the uneven pattern;
(C) Non-expandable expanded particle / reinforced fiber material / separation membrane / laminated body comprising expanded particle-containing resin composition / separated membrane / reinforced fiber material / release sheet prepared in the expanded particle-containing resin preparation step (a) A laminate preparation process for preparing
(D) The laminate is pressed from above and below, and the liquid molding resin in the layer of the foamed particle-containing resin composition is put into the reinforcing fiber material constituting the upper and lower surface layer portions via the separation membrane. A liquid molding resin impregnation step of infiltrating the liquid molding resin so as to cover each of the non-expandable foam particles of the surface layer portion on which the uneven pattern is formed while infiltrating,
(E) a curing step in which the obtained impregnated laminate is heated in a mold heated to a predetermined temperature to expand the expandable foamed particles and further cure and mold the liquid molding resin;
(F) A demolding step of opening the mold and taking out the obtained composite molded product,
By sequentially carrying out the above, a composite molded product in which the core part made of the expanded particle-containing resin exists between the surface layer parts made of the fiber reinforced resin and the whole is integrated is manufactured.

The important thing here is
(Ii) disposing non-expandable foam particles on the surface layer portion where the concavo-convex pattern surface is formed,
(B) using expandable foam particles or a mixture of expandable foam particles and non-expandable foam particles as the foam particles of the core,
(Ha) forming a laminated body in which a separation membrane and a reinforcing fiber material are arranged above and below the foamed particle-containing resin composition layer, and (ii) carrying out heating and pressure treatment on the laminated body of (ha) As a result, the layer of the foamed particle-containing resin composition in the laminate is effectively and uniformly formed, and the liquid molding resin is uniformly permeated into the reinforcing fiber material of the upper and lower surface layers, and the uneven pattern portion is formed. The liquid molding resin is infiltrated so as to cover each of the non-expandable foam particles in the surface layer portion.

In the press used in the liquid molding resin impregnation step and the curing step in the molding method of the present invention, the upper die having a substantially smooth surface is fixed to the upper surface plate of the press, or the upper die having a substantially smooth surface If the upper platen is used as a substitute for the upper die without using the upper plate, the pressing operation can be performed without fixing the lower die on which the uneven pattern is formed to the lower platen of the press.
Since the lower mold on which the concavo-convex pattern is formed is not fixed to the lower platen of the press, it is possible to carry out the laminate adjustment process by taking the lower mold on which the concavo-convex pattern is formed out of the press.
(D) The liquid molding resin impregnation step and (e) the curing step are carried out in the mold for molding, but the steps (a) to (c) preceding it can be carried out either inside the mold or outside the mold. .

The mold for molding is appropriately selected from a mold, a wooden mold, and a resin mold depending on the molding temperature and pressure. Further, without using a pair of upper and lower molds, only a lower mold having a concavo-convex pattern is used as a molding mold, and a substantially smooth surface is formed with the upper surface plate of the press without using an upper mold. If it molds using a release sheet between surface layers, it can produce efficiently.

In the non-expandable foam particle adjusting step, the non-expandable foam particles may be disposed on the entire surface of the concavo-convex pattern portion of the composite molded product, or may be disposed in a large amount on the convex portion of the composite molded product. The amount of the non-expandable foam particles to be arranged is determined optimally depending on the shape of the concavo-convex pattern of the composite molded product, the composition ratio of the fiber reinforced resin layer and the foamed particle-containing resin layer, and the constituent materials.

In the laminate preparation step, the expanded particle-containing resin composition comprising the reinforcing fiber material, the separation membrane, the liquid molding resin, and the expanded particles is formed on the lower mold on which the non-expandable expanded particles are disposed. A laminated body arranged in the order of reinforcing fiber material / separation membrane / foamed particle-containing resin composition / separation membrane / reinforcing fiber material / release sheet is set, and the mold is closed and thermoformed.

In addition, although the setting operation | work of the said laminated body may be implemented in a press, it is preferable to form in a lower mold | type beforehand out of a press from a viewpoint of production efficiency. In addition, when a part of the laminate is laminated outside the lower mold, the production efficiency is further improved.

In addition, when the above-mentioned surface layer reinforcing material (glass braid or the like) is placed in the mold and molded, it follows the reinforcing direction to obtain the required bending rigidity with respect to the required bending direction of the molded product. The reinforcing material is disposed so as to be inscribed in the reinforcing fiber material of the surface layer portion.

When forming the laminate, if a gas (bubbles) is contained in the foamed particle-containing resin composition, voids and pinholes are likely to occur on the concavo-convex pattern surface of the molded product, the fiber reinforced resin layer, etc. It is preferable to take care that no gas enters during the preparation of the foamed particle-containing resin composition. If necessary, the foamed particle-containing resin composition can be defoamed by vacuum treatment or the like after preparation.

In the method of the present invention, after placing the laminate in a molding die, the laminate is pressed (pressed) in the vertical direction, and the liquid molding resin in the composition is squeezed out from the inside of the separation membrane, and A layer that should be called a porous core layer precursor, in which foam particles are tightly packed inside the separation membrane, is sufficiently penetrated into the reinforcing fiber sheet, and gas (bubbles) that has entered the laminate is also formed. Remove.

The amount of the foamed particle-containing resin composition to be packed in the core in the mold for molding should be appropriately selected in consideration of the blending ratio of the foamed particles and the volume expansion ratio when the expandable foamed particles are heated.
Next, the mold is heated from the outside, or the temperature is raised by curing heat generation of the liquid resin or both, and the expandable foam particles of the foamed particle-containing resin layer are volume-expanded by foaming or the like.

At this time, the volume expansion of the expandable foam particles is caused in a state in which the liquid molding resin maintains fluidity, so that the reinforcing fiber material for forming the surface layer portion and the separation layer are formed under the expansion pressure of the expandable foam particles. Are pressed against the substantially smooth surface of the upper mold to form an outer shape along the uneven pattern surface of the lower mold, and at the same time, a liquid resin is extruded, and a part of the liquid molded resin is separated into the separation layer. And penetrates into the reinforcing fiber material for forming the surface layer portion.
Furthermore, after pressing the non-expandable foam particles placed on the concave / convex pattern surface of the lower mold, the liquid molding resin reaches the outermost layer of the surface layer portion that forms the concave / convex pattern surface so as to cover the non-expandable foam particles. The liquid molding resin is leveled to form a smooth surface of the composite molded product. Then, the excess resin is collected in the reservoir of the mold or removed from the vent, and the resin in the mold is cured to obtain a desired composite molded product.

Curing is usually performed by heating a predetermined part of the mold to a temperature equal to or higher than the curing temperature of the liquid molding resin. The composite molded article thus molded is taken out as a product by opening the mold. Further, depending on the type of the liquid molding resin, it may be further post-cured.

At the time of molding, the upper mold is preferably heated in advance. It is appropriate that the upper mold preheating temperature is equal to or higher than the curing start temperature of the liquid molding resin.

In the method of the present invention, the laminate is set in a mold and the mold is closed, and then the liquid molding resin is cured and molded. The mold is generally heated by an electric heater or a jacket through a heat medium, but induction heating, dielectric heating, etc. can also be employed, and heat generated by curing of the resin may be used.

A molded product obtained by curing the liquid molding resin by heating is taken out to obtain a composite molded product having a desired foam core / sandwich structure.

[Characteristics of composite molded products]
In the composite molded product produced by the above-described method, a uniform porous core layer in which particles are tightly packed at a density close to fine packing is sandwiched between dense surface layer portions formed of fiber reinforced resin and integrated. It is a composite molded product formed into a foam core sandwich structure that is lightweight and tough as a whole. In addition, it is a composite molded article that is substantially free of voids and pinholes, has excellent surface characteristics, and has excellent quality.
Furthermore, it is a composite molded product containing non-expandable foam particles in the surface layer portion where the design surface of the concavo-convex pattern is formed, and having no warping or twisting.

Thus, the composite molded product according to the method of the present invention is a plate-like lightweight and tough molded product, and the average thickness thereof is 1 to 100 mm, preferably 1.5 to 50 mm. Further, the surface layer portion made of fiber reinforced resin (FRP) has a three-layer structure in which a lightweight porous core layer exists between the upper and lower layers, and is cut in a direction perpendicular to the surface direction of the composite molded product. When the cross section is observed, the surface layer portion and the porous core layer have a clear boundary surface through the separation membrane. The ratio of the thickness of the surface layer part (total of the upper and lower layers) / the thickness of the porous core layer is preferably in the range of 2: 1 to 1:50, and preferably in the range of 2: 1 to 1:30. The ratio and thickness are not necessarily uniform for the entire molded product, and are partially changed by the uneven pattern surface forming the surface.

As described above, the method of the present invention uses the pressure of the volume expansion of the expandable foam particles to press the reinforcing fiber material as the surface layer forming material and the separation layer against the inner constraining surface of the mold, and liquid molding the surface layer portion. By infiltrating and curing the resin, the resin is mixed with the non-expandable foam particles in the surface layer portion to form a mixture of the non-expandable foam particles and the liquid molding resin to form an outer shape having an uneven pattern. Part of the liquid molding resin forms the FRP of the surface layer part, the outer surface having the uneven pattern of the molded product on the lower mold side, and a substantially smooth surface on the upper mold side, and the rest is the foamed part The basic feature is that the foamed portion and the surface layer portion are integrated by combining with the foamed particles.
The separation layer has a separation function that allows the liquid molding resin to pass through without passing through the expandable expanded particles after thermal expansion, and the non-expandable expanded particles in the surface layer do not flow back to the core. .

Further, as long as the effects of the present invention are not impaired, the core portion includes non-expandable foam particles, short fibers, pigments, etc. that cannot be expected to have volume expansion as the fourth component in addition to the expandable foam particles and the liquid molding resin. Can also be added.

As a result, a foamed particle is filled with a high density, and a surface layer composed of a dense fiber reinforced resin layer having excellent surface properties and appearance without having a strong core and pinholes without voids is formed. In addition, a composite molded product in which the core portion and the surface layer portion are firmly bonded and integrated is formed.

Examples of the present invention will be described in detail below. However, the examples are for helping understanding of the present invention, and the scope of the present invention is not limited by these examples. In the examples, “part” or “%” is a value based on weight unless otherwise specified.

[Example]
After mixing 70 parts of an epoxy resin (Adeka Resin EP-4300, manufactured by Adeka Co., Ltd.) and 14 parts of a curing agent (“1.3-bisaminomethylcyclohexane, manufactured by Mitsubishi Gas Chemical Co., Ltd.) at room temperature, it is expandable. 3 parts of expanded particles (“Matsumoto Microsphere F82” manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) and 15 parts of non-expandable expanded particles (“Glass Bubbles K37” manufactured by Sumitomo 3M Co., Ltd.) are added and mixed, and foamed. A particle-containing resin composition was prepared.
This resin composition containing expanded particles, Teijin Unicel Co., Ltd. “RT-0109” as the separation membrane, Nittobo Co., Ltd. “Glass mat MC380A, Glass MC450A” as the reinforcing fiber material, Oji Special Paper Co., Ltd. as the release sheet ) "Oji Alphan SS121 # 20", a laminate using 8 parts of Mizuno Ceramics Co., Ltd. "Rex 500" as non-expandable foam particles on the surface layer forming the concavo-convex pattern surface, warping and twisting As a result, there was obtained a composite molded product having a foam core / sandwich structure in which the uneven pattern as a design was faithfully reproduced without cracks.

DESCRIPTION OF SYMBOLS 1 Upper surface plate of press 2 Lower surface plate of press 3 Lower mold in which uneven surface is formed 4 Expanded particle containing resin composition 5 Expandable expanded particle 6 before foaming Liquid molding resin 7 Expandable expanded particle 8 after firing Expandable foamed particles 9 Reinforcing fiber material 10 Reinforcing fiber material 11 Separation membrane 12 Release sheet
13 Clamping direction of heat press treatment 14 Clamping direction of heat press processing 15 Path through which liquid molding resin enters the surface layer through the separation membrane

Claims (3)

Two surface layer parts comprising a fiber reinforced resin layer containing a reinforcing fiber material, a core part comprising a foamed particle-containing resin layer containing foam particles sandwiched between the two surface layer parts, and the surface layer part and the core part In a composite molded product integrated into a plate shape composed of a separation layer existing between the two, a surface of one surface layer portion of the composite molded product has a concavo-convex pattern and a surface of the other surface layer portion is substantially smooth. The surface layer part on which the uneven surface is formed and the uneven pattern is formed contains a non-expandable foamed particle, and is a method for producing a composite molded article,
Place the mold with the concavo-convex pattern on the lower platen of the molding press with the concavo-convex pattern facing up,
Arranging non-expandable foam particles on the molding surface of the mold on which the uneven pattern is formed,
A reinforcing fiber material is disposed on the non-expandable foam particles, and a separation membrane is disposed on the reinforcing fiber material so that the expanded foam particles after expansion do not pass but the liquid molding resin passes.
On the separation membrane, a mixture of expandable foam particles and liquid molding resin is disposed as the foam particles of the core,
A separation membrane and a reinforcing fiber material are arranged in this order on the mixture of the expandable foam particles and the liquid molding resin, the mold is closed, and the expandable foam particles are foamed to cause volume expansion. And the reinforcing fiber material is pressed against the inner wall surface of the mold, part of the liquid molding resin is permeated through the separation membrane and permeated into the reinforcing fiber material of the surface layer part, and A method for producing a composite molded article, comprising: injecting a liquid molding resin around the non-expandable foam particles; curing the liquid molding resin in that state; and removing the obtained composite molded article from the mold. The method for producing a composite molded article according to claim 1, wherein the foamed particles in the core are mixed particles of expandable foamed particles and non-expandable foamed particles. The method for producing a composite molded article according to any one of claims 1 to 2, wherein the non-expandable foamed particles in the surface layer portion on which the uneven pattern is formed are inorganic hollow particles.

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