JP2014193539A - Method of producing composite molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing a composite molding which is light and high in compression strength and bending strength.SOLUTION: A method of producing (f) a composite molding 10 composed of a foam small-piece molding 2 molded from a resin foam small piece 1 and a thermosetting resin hardened product 3 and includes (a) a step of arranging the foam small-piece molding 2 having pores 6 of a porosity of 3-30 vol.% in a mode 5 capable of forming a sealable internal space 4 of a specified shape, a step of (b) sealing the internal space 4 and reducing the pressure and (c) introducing a thermosetting resin liquid raw material 3' into the pressure-reduced internal space 4, (d) a step of impregnating the pores 6 of the foam small-piece molding 2 with the liquid raw material 3' and (e) a step of hardening the liquid raw material 3'.

Description

  The present invention relates to a method for producing a composite molded body of a foamed small piece molded from a resin foam small piece and a thermosetting resin cured product.

  Each country's efforts to the global environment have been accelerating in recent years, and concrete efforts to regulate carbon dioxide emissions have become important issues in each industrial field. In the automobile industry, in countries such as Europe, it has been agreed to deal with legally binding actions in the carbon dioxide emission regulations of automobiles (hereinafter sometimes referred to as “cars”). Efforts in electric vehicles and hybrid vehicles are a topic for responding to carbon dioxide emission regulations, but it is actually expensive from an economic perspective, and it is predicted that it will take time to promote widespread use Has been. As described above, in a moving medium having an internal combustion engine, reduction measures by direct improvement of the internal combustion engine such as an engine and a mission have been studied. To achieve the target reduction amount, the weight of the moving medium is reduced. Is essential.

  Metal materials are highly reliable as materials for various moving media such as cars, railways, ships, airplanes, and structural materials for buildings. Specifically, high-strength steel sheets and the like can be mentioned. However, in order to achieve an essential weight reduction, development of a lighter material having a higher specific strength has been required.

  On the other hand, as a plastic material, a thermosetting resin is positioned as a relatively high rigidity among all resin materials. Furthermore, FRP (fiber reinforced plastic), which can obtain higher specific strength by using glass fiber or carbon fiber in combination, can be cited as a plastic material. In particular, glass fiber reinforced plastic (GFRP), which is a composite of unsaturated polyester resin and glass fiber, has been adopted as an exterior member for automobiles and ships, and has been evaluated as a practical lightweight material. However, due to the non-uniformity of the glass fiber dispersion and the limitation of the glass fiber length, there is a tendency that it is difficult to obtain a physically uniform molded product. In order to compensate for this, it was necessary to design the product with a product thickness exceeding the physical property tolerance for the required physical properties, and it was often difficult to obtain the expected weight reduction. It was. In order to solve these problems, in recent years, carbon fiber reinforced plastic (CFRP) tends to be employed. However, this CFRP is also a technology that has a problem that even if the performance is good, it is difficult to use it from the viewpoint of cost.

Moreover, a sandwich panel structure can be cited as a technique for finding a balance between cost and material strength.
As a typical example, a panel structure in which the upper and lower surfaces of a hard vinyl chloride foam plate used for shipbuilding is sandwiched with GFRP is known. These sandwich panel structures can improve the section modulus and the second moment of section in structural mechanics. Specifically, the specific strength can be improved by using a foam, lightweight wood or paper, or a honeycomb material using aluminum as the sandwich core. However, the number of parts that depend on manual work in the manufacturing process tends to increase, and as a result, there is a problem that even if the performance is good, it is difficult to use it from the viewpoint of cost.

  On the other hand, it is well known that the resin foam material is a relatively inexpensive material. In addition, although it is a material suitable for weight reduction due to its structure, for example, when direct replacement with a metal material is considered, replacement of some parts is limited due to insufficient strength and insufficient reliability. The trend was strong.

  For example, the resin foam material includes a thermosetting resin foam. However, it is not applicable to all thermosetting resins, and even thermosetting resin foams such as polyurethane foam, phenol foam, urea resin foam, etc., which can be foamed exceptionally, can be further used as FRP-based materials. The fact is that there is no way to replace metallic materials other than compounding. Various physical properties such as bending strength can be achieved with the same weight, but high strength can be achieved with the same weight, but the thickness is too thick to be processed into a practical size, the surface hardness is too poor, and the surface is smooth. Because of the lack of product value due to lack of quality, it was not possible to substitute for metallic materials.

  In recent years, a lightweight composite material in which a thermosetting resin material and foamed particles are combined has been proposed. Patent Document 1 proposes a composite material of expanded particles and a thermosetting resin material. The composite material is obtained by mixing foamed particles and a thermosetting resin material and then curing the thermosetting resin material. In the composite material obtained by the manufacturing method having such a mixing step, it is difficult to uniformly disperse the expanded particles, and air may be involved in the cured product.

  Patent Document 2 proposes a composite lightweight body in which a plurality of foamed particles are integrated with an unsaturated polyester resin cured product. However, similar to Patent Document 1, a mixing process is required. There was concern about the uniformity of physical properties of the composite lightweight body.

  Furthermore, in Patent Document 3, a base material composed of a foamed resin molded body formed by foaming a foamed resin raw material is immersed in a thermosetting resin in a fluid state, and between the foamed cells constituting the base material. A foamed resin composite structure obtained by accommodating the thermosetting resin in the formed void, taking out the base material from the thermosetting resin, and curing the thermosetting resin accommodated in the void. A manufacturing method is disclosed. However, in the composite structure, the pressure on the other surface of the base material is lower than the pressure on the one surface in the gap communicating with one surface of the base material and the other surface. In this method, a pressure difference is generated between the one surface and the other surface to accommodate the fluidized thermosetting resin. As described above, when the thermosetting resin is expropriated due to the pressure difference in the open system, the arrangement of the thermosetting resin with respect to the thickness direction of the base material is biased, leaving a problem in the uniformity of the physical properties of the composite structure. It was.

JP 2000-319440 A JP-A-6-39936 WO 2008/120295

  In view of the above problems, an object of the present invention is to provide a method for producing a composite molded body that is lightweight, has high compressive strength and bending strength, and is excellent in uniformity of physical properties.

As a result of earnest research, the present inventor has uniformly cured a thermosetting resin in a resin foam small piece molded body, and integrated the thermosetting resin and the resin foam small piece molded body. As a result, the present invention has been completed.
That is, the present invention is [1] a method for producing a composite molded body of a foamed small piece formed by molding a thermoplastic resin foam small piece and a thermosetting resin cured product,
Disposing a foamed small piece molded body having a continuous void and a porosity of 3 to 30% by volume in a mold having an internal space of a predetermined shape that can be sealed;
Sealing and depressurizing the internal space, introducing a thermosetting resin liquid raw material into the depressurized internal space, and impregnating the liquid raw material into the voids of the foamed piece molded body; and Curing,
The manufacturing method of the composite molded object characterized by including this.
[2] Before introducing the liquid material into the internal space, the internal space is decompressed to −0.01 to −0.1 MPa (G). Production method.
[3] The method for producing a composite molded article according to [1] or [2], wherein the liquid raw material has a viscosity of 100 to 10,000 mPa · s.
[4] The liquid raw material is impregnated in the voids of the foam piece compact, and the liquid raw material covers the periphery of the foam piece compact, [1] to [3] A method for producing a composite molded article.
[5] The cured thermosetting resin is at least one selected from unsaturated polyester resins, epoxy resins, dicyclopentadiene resins, urethane resins, and polyimide resins [1] -The manufacturing method of the composite molded object in any one of [4].
[6] The base resin of the resin foam piece is at least one selected from polyethylene resins, polypropylene resins, polystyrene resins, polyester resins, and polyvinyl chloride resins [1] -The manufacturing method of the composite molded object in any one of [5].
[7] The method for producing a composite molded body according to any one of [1] to [6], wherein the foamed small piece molded body has a bulk density of 15 to 250 g / L.
[8] The method for producing a composite molded article according to [6], wherein the base resin of the resin foam piece contains a polylactic acid resin.

According to the method for producing a composite molded body of the present invention, it becomes possible to uniformly impregnate a thermosetting liquid raw material into a void portion of a foamed small side molded body having a void portion with a porosity of 3 to 30% by volume. When the thermosetting resin liquid raw material is cured, it becomes possible to provide a composite molded body that is lightweight and has excellent physical property uniformity.
The method for producing a composite molded body of the present invention can produce a composite molded body with good reproducibility, and can stably produce a composite molded body having highly reliable physical properties.

It is explanatory drawing which shows typically each process of the manufacturing method of the composite molded object of this invention. (A) a step of disposing a foamed small piece molded body in the mold, (b) to (d) a step of depressurizing the mold, introducing a thermosetting resin liquid raw material, and impregnating the void, (e) thermosetting It is a schematic diagram which shows the state which hardened | cured the adhesive resin, and the state which obtained the composite molded object by (f) mold release. It is explanatory drawing which shows typically the principal part of the process of making a space | gap part impregnate a thermosetting resin liquid raw material.

First, the manufacturing method of the composite molded object of this invention is demonstrated.
The method for producing a composite molded body of the present invention includes a step of disposing a foamed small piece molded body having a void portion with a porosity of 3 to 30% by volume in a mold capable of forming an internal space of a predetermined shape that can be sealed, the internal space Reducing the pressure, introducing a thermosetting resin liquid raw material into the reduced internal space, impregnating the liquid raw material into the voids of the foamed piece compact, and curing the liquid raw material. It is characterized by including.

  In the method for producing a composite molded body according to the present invention, a foamed small piece formed by molding a thermoplastic resin foam small piece and a thermosetting resin liquid raw material are used.

  The base resin constituting the resin foam piece is preferably a thermoplastic resin, for example, a polyester resin such as polystyrene resin, polyethylene resin, polypropylene resin, polybutylene succinate, polyethylene terephthalate, polylactic acid, etc. And polycarbonate resins and polyvinyl chloride resins.

  Since the resin foam piece determines the network structure of the thermosetting resin cured product (hereinafter, sometimes referred to as “network structure of thermosetting resin composite molded body”), the resin foam is small. It is preferable that the ratio of the dimension in the longitudinal direction of the small piece to the dimension in the lateral direction (longitudinal dimension / dimension in the lateral direction, hereinafter sometimes referred to as “aspect ratio”) is 1-2. If it is within the above range, voids formed between the resin foam small pieces are easily formed uniformly in the resin foam small pieces, and the voids are filled with the thermosetting resin raw material liquid to make the voids more uniform and strong. A network structure of the thermosetting resin cured product is formed.

  Examples of the shape of the resin foam piece include foamed particles, foamed strands, foamed molded products, and pulverized products of extruded foams, among which foamed particles are preferable.

  Moreover, 1.0-3.5 mm is preferable and, as for the particle diameter of the resin foam small piece, 1.5-3.2 mm is more preferable. If it is in the said range, it will become a suitable thing for the improvement of the intensity | strength of the said composite molded object. In addition, when the particle diameter of the resin foam small pieces is small, since the opening surface of the gap between the resin foam small pieces tends to be small, the porosity of the foam small piece molded body is increased to increase the thermosetting resin liquid raw material. It is preferable to facilitate the impregnation. The particle diameter of the resin foam piece is an average value of values measured as the maximum external dimensions of at least 100 resin foam pieces.

  Furthermore, the resin foam pieces used in the production method of the present invention are usually insoluble in the liquid thermosetting resin raw material to be used, and particularly described in JP-A-2004-0668016. It is preferable to use foamed particles having such a sheath-core structure. A stronger composite molded body can be formed by selecting the base resin forming the sheath layer in consideration of the affinity with the thermosetting resin raw material using the foamed particles having the sheath core structure.

In the sheath-core type polylactic acid-based resin expanded particles, it is preferable to use an amorphous polylactic acid resin for the sheath layer. Since the amorphous polylactic acid resin has the property of being easily dissolved or swollen in the thermosetting resin, the affinity with the thermosetting resin liquid raw material is increased. Therefore, when used in the production method of the present invention, when the foamed particles and the thermosetting resin liquid raw material are in contact with each other in the mold, the thermosetting resin liquid raw material is a gap between the foamed particles using the sheath layer as a flow path. The three-dimensional network structure of the thermosetting resin cured product is more easily formed. Further, the volume of the thermosetting resin cured product configured as a composite molded body tends to be larger by the amount of the resin layer than the theoretical volume required from the thermosetting resin liquid raw material.
On the other hand, it is preferable to use a crystalline polylactic acid resin for the core layer. The crystalline polylactic acid-based resin is hardly dissolved or swollen with respect to the thermosetting resin liquid raw material, and the shape of the expanded particles is easily maintained.
The polylactic acid-based resin expanded particles as described above can be prepared, for example, by the method described in JP2012-025869A.

  The bulk density of the foamed pieces used in the production of the composite molded body of the present invention is preferably 15 g / L to 250 g / L, and more preferably 15 to 100 g / L. If it is in the said range, since the weight reduction effect is high and the network structure of the thermosetting resin cured product having higher strength is easily formed, it is suitable for the composite molded body.

  Examples of the foamed particles include commercially available foamed particles, those having a bulk density of 15 to 90 g / L in the trade name “PiBlock (registered trademark)” which is a polypropylene resin foam of JS Corporation, Among the brand name “L-block (registered trademark)” which is a polyethylene resin foam of the company, those having a bulk density of 15 to 80 g / L, foamable polystyrene resin particles of JSP Co., Ltd., trade name “Styrodia (Registered) Examples thereof include polystyrene resin foamed particles obtained by foaming “trademark” to a predetermined bulk density with a pre-foaming machine. Further, foamed particles can be obtained with reference to Japanese Patent Publication No. 53-1313, WO2012 / 086305, Japanese Patent Application Laid-Open No. 2012-025869, and the like.

  The foamed piece compact has a continuous void, and the porosity is 3 to 30% by volume. If the porosity is less than 3% by volume, the amount of thermosetting resin that can be impregnated is small, and the contribution of strength development by the cured thermosetting resin may be reduced. On the other hand, when it exceeds 30 volume%, there exists a possibility that the effect of weight reduction may become difficult to be acquired. From the above viewpoint, the content is preferably 5 to 25% by volume.

The porosity of the foamed small piece compact is determined by the following method.
A rectangular parallelepiped sample is cut out from the molded foam piece that has been allowed to stand for 24 hours or more in an environment of a temperature of 23 ° C. and a relative humidity of 50%, and the bulk volume Va [cm ³ ] is obtained from the external dimensions of the sample. Next, the sample is submerged in a graduated cylinder containing ethanol at a temperature of 23 ° C. using a tool such as a wire mesh, and air existing in the voids in the molded body is degassed by applying a light vibration or the like. Then, the true volume Vb [cm ³ ] of the sample read from the rise in the water level is measured in consideration of the volume of a tool such as a wire mesh. From the obtained bulk volume Va [cm ³ ] and the true volume Vb [cm ³ ], the porosity Y [%] is obtained by the following formula.
Porosity Y [%] = [(Va−Vb) / Va] × 100 (1)

The foamed small piece molded body is preferably a foamed particle molded body having a bulk density of 15 to 250 g / L. If it is in the said range, the weight reduction of a composite molded object will be attained more. From the above viewpoint, the bulk density of the foamed small piece molded body is preferably 20 to 230 g / L. The bulk density can be obtained by dividing the weight of the foamed small piece molded product by the volume obtained from the external dimensions of the foamed small piece shaped product and further converting the unit to [kg / m ³ ].

  In addition, the foamed small piece molded body having such a porosity is obtained by resin foaming by a method described in, for example, Japanese Utility Model Publication No. 63-7607, Japanese Patent Application Laid-Open No. Hei 2-299822, Japanese Patent Application Laid-Open No. Hei 5-147120. It can be obtained by molding a small piece in a mold.

  Examples of the thermosetting resin used in the method for producing a composite molded body of the present invention include an epoxy resin, an unsaturated polyester resin, a dicyclopentadiene resin, a polyurethane resin, a silicon resin, a phenol resin, and a melamine. Resin, polyimide resin, urea resin, diallyl phthalate resin, and modified resins thereof. In addition, the said thermosetting resin is used in the state of the liquid raw material mixed with the crosslinking monomer, the hardening accelerator, the additive, etc.

  Among these, an epoxy resin is preferably used from the viewpoint of handleability. The epoxy resin preferably contains two or more epoxy groups per molecule, such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD (acetaldehyde) type epoxy resin, glycidyl ester type epoxy resin, An alicyclic epoxy resin etc. are mentioned, These can be used individually or in mixture of 2 or more types.

Corresponding to such a thermosetting resin, it is preferable to add a curing agent that can react with the thermosetting resin to produce a cured product. The curing agent is not particularly limited as long as it can react with a thermosetting resin to form a cured product. For example, as a curing agent for an epoxy resin, an acid anhydride such as methylhexahydrophthalic anhydride. Products, phenolic resins such as novolac type phenolic resins and cresol novolac type epoxy resins, phthalic anhydride derivatives, dicyandiamide, imidazole compounds, aluminum chelates, amine complexes of Lewis acids such as BF ₃ , etc. Two or more kinds can be mixed and used.

  Although the addition amount of the curing agent varies depending on the type of the thermosetting resin, the type of the curing agent, and the like, for example, the epoxy resin varies depending on the epoxy equivalent, but is usually 2 mass per 100 mass parts of the epoxy resin. It is preferable to add at least 150 parts by weight.

As described above, the curing method of the thermosetting resin liquid raw material is not particularly defined. Further, even when a one-component curing agent is used, a curing agent of a mixture of two or more liquids is used. It may be used. In addition, the curing means is not particularly defined as long as the desired cured product is obtained, and it can be cured in a form accompanied by a general chemical reaction such as radical reaction, polycondensation reaction, metathesis reaction and the like. it can.
In addition, as for the said thermosetting resin hardened | cured material, it is desirable that the surface hardness is 20 or more in Barcol hardness. The Barcol hardness can be measured according to JIS K7060 (1995).

The apparent viscosity of the thermosetting resin liquid raw material before curing is preferably 100 to 10,000 mPa · s. If it is in the said range, the liquid raw material can be uniformly and easily impregnated in the space between the resin foam pieces. From the above viewpoint, it is more preferably 200 to 8000 mPa · s. In the present specification, the viscosity is a value measured based on the Brookfield viscometer method of JIS K6901 (2008).

In addition, in order to adjust a viscosity, what makes viscosity high, such as a thixotropic agent, and what makes viscosity low, such as a viscosity reducing agent, can be added as needed. In this case, the viscosity of the liquid resin material after viscosity adjustment is measured.

  In the thermosetting resin liquid raw material, additives for improving physical properties can be blended. Examples of inorganic additives include inorganic pigments, glass fibers, glass powder, talc, magnesium carbonate, magnesium oxide, and the like. On the other hand, phenolic antioxidants, HALS, organic pigments and the like are generally used as organic additives. The addition amount of the organic additive can be added within a range that does not affect the cured product. The addition amount of the additive is preferably 10 parts by mass or less with respect to 100 parts by mass of the thermosetting resin liquid raw material.

  The thermosetting resin liquid raw material preferably has a composition that does not contain a solvent. This is because the solvent may cause bubbles in the network wall of the cured thermosetting resin.

Embodiments of the present invention will be further described with reference to the drawings. FIG. 1 is an explanatory view schematically showing each step of the method for producing a composite molded body of the present invention.
FIG. 1A shows a state in which the step of housing the resin foam small piece molded body 2 in which the resin foam small pieces 1 are fixed and integrated in a mold 5 having a rectangular parallelepiped internal space 4 and forming a sealed space is completed. Is schematically shown.

  The resin foam piece 2 has a gap 6 in the gap between the resin foam pieces 1, and the void ratio is 3 to 30 from the viewpoint of effectively impregnating the thermosetting resin liquid raw material. The resin foam small piece molding 2 which is volume% is used.

  Next, the inside of the mold 5 is depressurized. In FIG. 1A, a vacuum suction valve (not shown) is opened, and the internal space 4 is depressurized by a vacuum pump or the like. At least when the thermosetting resin liquid raw material is introduced, the degree of reduced pressure needs to be uniform in the internal space in the sealed container. When the sealed internal space has a uniform reduced pressure, the thermosetting resin liquid raw material is uniformly impregnated, and a good composite molded body is obtained. From the above viewpoint, the reduced pressure is preferably in the range of -0.01 to -0.1 MPa (G), and more preferably in the range of -0.02 to -0.08 MPa (G). In addition, (G) means a gauge pressure. However, when the inside of the mold is reduced in pressure, the boiling point of the thermosetting resin before curing is lowered, and bubbles may be mixed in due to the boiling phenomenon. There is.

  In this invention, it is preferable that the said pressure reduction process is performed before adding a thermosetting resin liquid raw material. Before the thermosetting resin liquid raw material is introduced in advance, the entire interior of the mold is subjected to a pressure reducing process so that the thermosetting resin liquid raw material 3 ′ to be introduced into the mold is formed in the void portion of the resin foam small piece molded body 2. In addition, it is possible to fill (impregnate) more evenly and without wrinkles.

  In the step of introducing the thermosetting resin liquid raw material into the decompressed internal space, as shown schematically in FIG. 2 by enlarging FIG. 1B, a decompression device connected to the decompression suction pipe 8 is used. The thermosetting resin liquid raw material 3 is stored outside the mold (not shown) from the introduction hole 7 provided between the lower mold 5b and the upper mold 5a by controlling and balancing the degree of decompression in the mold 5. It is desirable to introduce 'into the mold.

  Furthermore, the introduction of the thermosetting resin liquid raw material is preferably performed quasi-statically. In the introduction, the quasi-static state is preferably a laminar state defined by the Reynolds number, and a turbulent state is not preferable. The introduction in the laminar flow state not only helps to prevent entrainment of bubbles and the like, but also can prevent the loss of the network structure. Therefore, it is preferable to maintain the laminar flow state during the introduction.

  In the step of introducing the thermosetting resin material, a method of applying pressure to the resin at the introduction port may be used in combination. For the pressurization of the resin, mechanical compression by a piston plunger or the like is generally employed, but a method of pressurizing the tank with gas or the like may be used. However, when there is a risk of denaturation or deactivation of the thermosetting resin due to contact with air or a water vapor component, introduction using a plunger is preferably employed. The pressure applied during the introduction is preferably 0.5 MPa (G) or less.

  In the initial stage of introducing the thermosetting resin liquid raw material into the mold as shown in FIG. 1 (b), the foamed small piece molded body 2 is in a lifted state, and the resin is introduced from the bottom of the mold in such a state. Furthermore, it is preferable that the liquid raw material is subjected to a step of impregnating the void portion of the foamed piece compact.

The voids 6 of the foam piece compact 2 are formed in a mesh shape in the foam piece compact. The void portion 6 is impregnated with a thermosetting resin liquid raw material and cured to form a three-dimensional network structure of a thermosetting resin cured product, and the strength of the composite molded body is dramatically improved.
Therefore, the formation of the network structure of the thermosetting resin cured product is related to the reduced pressure state of the mold, the viscosity of the thermosetting resin liquid raw material, the introduction pressure, the impregnation speed and the curing speed. It is preferable that the liquid material is impregnated in the voids before curing.

  In the step of impregnating the gap 6 with the thermosetting resin liquid raw material, it is preferable that the pressure in the sealed internal space is uniform. Furthermore, as shown in FIG.1 (d), the thermosetting resin liquid raw material is filled into the space | gap part of a foaming small piece molded object. Further, it is preferable that the void portion 6 is impregnated with a thermosetting resin liquid raw material and the liquid raw material covers the periphery of the foamed small piece molded body. The reason why such a state is formed is that, unlike the conventional case, a mold that can form an internal space of a predetermined shape that can be sealed is used, and molding is performed while leaving a gap between the mold and the foamed small piece molded body. This is because the thermosetting resin liquid raw material wraps around the entire periphery of the small foam molded body in the mold, and the cured product layer of the composite molded body is easily formed uniformly on the outer periphery.

  In the production method of the present invention, when the thermosetting resin liquid material is cured, the thermosetting resin liquid material inside the mold is cured at a temperature corresponding to the curing characteristics of the thermosetting resin liquid material. The introduction step, the impregnation step, and the curing step may be performed concurrently, such as impregnation with the introduction, or the curing proceeds with the impregnation.

  After the curing is completed, the mold 5 is removed (released) as shown in FIG. In the obtained composite molded body 10, the thermosetting resin cured product 3 is filled in the voids of the foam small piece molded body 2, and the entire outer periphery of the foam small piece molded body 2 is covered with the thermosetting resin cured product 3. ing.

The composite molded body obtained by the production method of the present invention is composed of a thermosetting resin and a small foam molded body.
Inside the composite molded body, the thermosetting resin cured product is cured in close contact with the space between the resin foam pieces of the foam piece molded from the resin foam pieces so as to wrap the individual resin foam pieces. ing. Inside the composite molded body, that is, the thermosetting resin cured product forms a so-called three-dimensional network structure. By forming this network structure, the strength of the composite molded body is exhibited. The network structure can be changed as appropriate by changing the individual shape of the resin foam pieces arranged in the mold and the porosity of the foamed piece compact.

  Although it does not restrict | limit especially according to the objectives, such as a use of the composite molding to be obtained, it is preferable that the resin foam piece and the thermosetting resin are firmly bonded. For example, when the composite molded body is broken by a material destruction test or the like, it is preferable that the resin foam piece and the thermosetting resin cured product are bonded to such an extent that the resin foam piece breaks down. From the above viewpoint, when an epoxy resin is used as the thermosetting resin, a polylactic acid resin or a polypropylene resin is preferably used as the base resin of the resin foam piece.

  It is desirable that pores are not present as much as possible inside the network wall constituting the network structure of the thermosetting resin cured product. The structure as described above is achieved for the first time by the production method of the present invention, and since the thermosetting resin cured product is uniformly present in the composite molded article, local strength reduction does not occur, A composite molded body can be produced stably.

  Since the external appearance of the composite molded body is surrounded by the mold and molded, the shape of the mold is transferred. In the production method of the present invention, when molding is performed leaving a gap between the mold and the foam piece molded body, the thermosetting resin liquid raw material wraps around the entire periphery of the foam piece molded body, and the thermosetting resin A cured product layer (hereinafter, simply referred to as “thermosetting resin layer” or “cured product layer”) is formed. From the above viewpoint, the gap between the mold and the foamed small piece molded body is preferably molded as 0.1 mm to 5 mm, and particularly preferably molded as 0.2 mm to 3 mm.

  In addition, the cured product layer has surface smoothness and paintability, the surface hardness can be maintained at a practical level, and the outer wall design can be achieved by inserting a sheet of paper printed material for surface decoration into the panel. It can also be used as an indoor design panel.

  The density of the obtained composite molded body is preferably 100 to 400 g / L, more preferably 150 to 350 g / L. If it is in the said range, while becoming excellent in lightweight property, it becomes a molded object excellent also in intensity | strength.

  Further, the coefficient of variation, which is a value obtained by dividing the standard deviation of the density (inner layer density) of the test pieces randomly cut out from at least five locations from the composite molded body by the arithmetic average of the inner layer density, is expressed as a percentage. % Is preferably within a range. Within this range, mechanical strength such as compressive strength and bending strength becomes stable. The inner layer density is defined as the density excluding the cured product layer portion of the surface layer. From the above viewpoint, the coefficient of variation is more preferably 5% or less.

  Since the composite molded body includes the foamed small piece molded body, the composite molded body has heat insulating performance. The thermal conductivity of the composite molded body is preferably 0.06 W / (m · K) or less, and more preferably 0.05 W / (m · K).

  Furthermore, since the thermosetting resin cured product portion has the ability to transmit light, the obtained composite molded body has translucency. Therefore, it can be used as an inner / outer wall combined heat insulation panel or the like that allows the light to be visually recognized from the outside by turning on room lighting at night.

  The inner layer density is determined by measuring the weight and three-dimensional dimensions of a sample cut out from the composite molded body into an arbitrary rectangular parallelepiped shape and calculating the inner layer density (g / L). If it is difficult to cut into a rectangular parallelepiped shape, cut it into an arbitrary shape, measure the weight, submerge the sample in a graduated cylinder filled with water, measure the volume from the change in the marked line, and calculate the density. can do. In addition, in the case of the said measurement, a hardened | cured material layer shall not be included.

Further, the composite molded body obtained by the production method of the present invention heats a composite molded body composed of a foam small piece molded body and a thermosetting resin cured product, and melts, decomposes, dissolves, or reduces the volume of the foam small piece molded body. By doing so, it is also possible to provide a molded product having a form in which only the network structure of the thermosetting resin cured product remains in appearance.
The molded product in a form in which only the network structure of the thermosetting resin cured product remains is a composite molded product obtained by the production method of the present invention at a temperature lower than the decomposition temperature of the thermosetting resin cured product and a resin foam. The resin foam small piece molded product is volatilized or reduced by heat treatment above the melt decomposition temperature or volume reduction temperature of the small piece molded product, and the portion occupied by the resin foam small piece molded product is made hollow. Achieved by: It is desirable to perform the melt decomposition operation or volume reduction operation in an inert gas atmosphere such as nitrogen gas from the viewpoint of preventing oxidative deterioration of the cured thermosetting resin forming the network structure.
In order to obtain a molded product having a network structure, it is necessary to select a thermosetting resin having high heat resistance.

  It is preferable that the bubbles formed in the network structure of the thermosetting resin cured product have a closed cell structure. In the case of having such a network structure, a composite molded body having excellent strength is obtained.

  Moreover, it is preferable that the bubble diameter (average diameter of the foamed small piece part in the cross section of a composite molded object) of the mesh formed with the network structure of a thermosetting resin hardened | cured material is 1-5 mm. If it is in the said range, a local strength fall will not produce easily and a composite molded object can be manufactured stably.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.

Example 1
(Manufacture of foamed small pieces)
The sheath layer is a non-foamed layer of amorphous polylactic acid, grade name: “Ingeo 4060D” manufactured by Nature Works, and the core layer is a sheathed core type polylactic acid made of the company's crystalline polylactic acid, grade name: “Ingeo 2003D”. Expanded particles were used as resin foam pieces. The weight ratio of the sheath layer to the core layer was 5/95, and the high temperature peak of the expanded particles measured by DSC was a calorific value of 5 J / g. The foamed particles were molded in-mold to obtain a foamed small piece compact. Molding is performed using a mold that can be opened and closed [effective dimensions: length (l) 300 × width (w) 300 × depth (t) 50 (mm)], and the inside of the mold is zero with air. After filling the mold held at 1 MPa (G) with foamed particles, the air pressure in the mold is returned to 0.0 MPa (G), and then the original pressure is 0 with the exhaust valve attached to the mold open. After conducting 3 MPa (G) steam for 5 seconds, close the exhaust valve, introduce 0.02 MPa (G) steam into the mold and hold it for 5 seconds, then cool with water for 15 seconds and open the mold Then, a flat foamed small piece molded with a mold was taken out. The molded body was dried in an oven at 40 ° C. for 24 hours, then transferred to an oven at 70 ° C., and subjected to heat treatment for 24 hours. The dimensions of the foamed compact after the heat treatment are length (l) 295 × width (w) 295 × thickness (t) 48 (mm), and have a bulk density of 84 g / L. A foamed small piece made of lactic acid was obtained. Hereinafter, in the dimension notation, the length (l) is “l”, the width (w) is “w”, the depth (t) of the mold or the thickness (t) of the molded body is “t”, It will be described later. The molded product was cut into 295 l × 295 w × 28 t (mm) to form a flat plate.

(Manufacture of composite moldings)
A pair of upper and lower parts having an effective inner dimension of 300 l × 300 w × 30 t (mm) and having a resin mold (FRP type) having an inlet and an outlet for a thermosetting resin as an upper mold and a 2 mm-thick SUS plate as a lower mold. The foamed molded piece made of polylactic acid was placed inside a mold that can form a sealed space (placement step). Next, after closing the inlet of the liquid raw material provided at the boundary with the lower die and sealing the inside of the die, the pressure was reduced by -0.04 MPa (G) from the outlet provided at the central top of the upper die ( Decompression step). After confirming that the inside of the mold became −0.04 MPa (G), an epoxy-based thermosetting resin liquid raw material prepared in advance was introduced into the mold by opening the inlet. As the epoxy resin, a thermosetting resin liquid raw material composed of 100 parts by mass of jER807 manufactured by Mitsubishi Chemical Corporation and 11 parts by mass of TETA manufactured by Mitsubishi Chemical Corporation was used. The viscosity of this thermosetting resin liquid raw material is shown in Table 1.
The thermosetting resin liquid raw material (hereinafter, also referred to as “liquid resin”) was introduced through a 10 mmφ simplex tube connected to the introduction port while suctioning the mold in a reduced pressure state as a driving force. In addition, -0.04 MPa (G) was maintained over the time of introduction. The amount of liquid resin at the time of introduction was controlled while being controlled between 30 g / min and 200 g / min, and continued until the liquid resin was finally discharged from the upper mold outlet (introduction step). The time required for introducing the liquid resin was 10 minutes. When the introduction is completed, the inlet is closed, and the mold is kept stationary for 24 hours while keeping the pressure reduced from the outlet (the room temperature is 23 ° C. and the humidity is 60% RH). After 24 hours, the mold was opened and the composite molded article was taken out and left in an oven heated to 80 ° C. for 3 hours to complete the curing (impregnation / curing step).

The composite molded product having been completely cured was a 300 l × 300 w × 30 t (mm) plate-shaped composite molded product (in addition, a manifold portion for maintaining a stable supply of liquid resin (part corresponding to an injection molding runner) And burrs are cut off).
Table 2 shows the physical properties and the like of the obtained composite molded article.

Example 2
(Manufacture of foamed small pieces)
Foamed particles in which the base resin was a mixed resin of polypropylene resin and polylactic acid resin (mixing ratio, PP: PLA = 7: 3) were used as the resin foam pieces. The high temperature peak of the expanded particles measured by DSC was a heat quantity of 5 J / g. The foamed particles were molded in-mold to obtain a foamed small piece compact. Molding is performed using a mold that can be opened and closed (effective dimensions: 300 l × 300 w × 50 t (mm)), and after filling the expanded beads into a mold in which the mold is held at 0.1 MPaG with air, The air pressure in the mold is returned to 0.0 MPa (G), and then the exhaust valve attached to the mold is opened and steam with an original pressure of 0.3 MPa (G) is conducted for 5 seconds, and then the exhaust valve is closed. Then, 0.02 MPa (G) steam was introduced into the mold and held for 5 seconds, followed by water-cooling cooling for 15 seconds, the mold was opened, and a flat foamed small piece compact was taken out. The molded body was dried in an oven at 40 ° C. for 24 hours, then transferred to an oven at 70 ° C., and subjected to heat treatment for 24 hours. The size of the foamed small piece compact after the heat treatment was 295 l × 295 w × 48 t (mm), and the foam small piece compact shown in Table 1 was obtained. The molded product was cut to a thickness of 28 mm to form a flat plate.

(Manufacture of composite moldings)
A pair of upper and lower parts having an effective inner dimension of 300 l × 300 w × 30 t (mm) and having a resin mold (FRP type) having an inlet and an outlet for a thermosetting resin as an upper mold and a 2 mm-thick SUS plate as a lower mold. The foamed small piece molded body was placed inside the mold (placement step). Next, after closing the inlet of the liquid material provided at the boundary with the lower mold, the pressure was reduced by -0.04 MPa (G) from the outlet provided at the center top of the upper mold (decompression process). After confirming that the inside of the mold became −0.04 MPa (G), the following unsaturated polyester thermosetting resin liquid raw material prepared in advance was introduced into the mold by opening the inlet ( Introduction process). As the unsaturated polyester resin, a thermosetting resin liquid raw material comprising 100 parts by mass of 4007A manufactured by Nippon Iupika, 0.5 parts by weight of cobalt naphthenate, and 1 part by weight of methyl ethyl ketone peroxide (MEKPO) was used. The viscosity of this thermosetting resin liquid raw material is shown in Table 1.
The thermosetting resin liquid raw material (hereinafter, also referred to as “liquid resin”) was introduced through a 10 mmφ simplex tube connected to the introduction port while suctioning the mold in a reduced pressure state as a driving force. The amount of liquid resin at the time of introduction was introduced while being controlled between 30 g / min and 200 g / min. This was continued until the liquid resin was finally discharged from the upper mold outlet. The pressure at the time of introduction was maintained at −0.04 MPa (G). The time required for introducing the liquid resin was 10 minutes. When the introduction is completed, the inlet is closed, and the mold is kept stationary for 24 hours while keeping the pressure reduced from the outlet (the room temperature is 23 ° C. and the humidity is 60% RH). After 24 hours, the mold was opened and the composite molded product was taken out (impregnation / curing step).

The composite molded product having been completely cured was a plate-shaped composite molded product of 300 w × 300 l × 30 t (mm) (in addition, a manifold part for maintaining a stable supply of liquid resin (part corresponding to injection molding runner) ) And burr sites were cut and deleted).
Table 2 shows the physical properties of the obtained composite molded article.

Comparative Example 1
In a mold having an opening of 300 w × 75 t (mm), the polylactic acid-based resin foam piece (dimensions 295 w × 295 l × 28 t (mm)) obtained in Example 1 and a bulk of 84 g / L A foamed small piece made of polylactic acid having a porosity of 7% having a density) was inserted. The mold frame is a structure that is in close contact with the lower mold, and by setting the lower mold in a reduced pressure state, a differential pressure is formed from the upper surface of the foam piece molded body to the lower surface via the foam piece molded body (the upper surface is Open). As the epoxy resin, a thermosetting resin liquid raw material composed of 100 parts by mass of jER807 manufactured by Mitsubishi Chemical Corporation and 11 parts by mass of TETA manufactured by Mitsubishi Chemical Corporation was used. A thermosetting resin liquid raw material was poured from the upper surface so as to cover the upper surface of the foamed small piece molded body. The reduced pressure during the introduction was set to -0.04 MPa (G). After confirming that the liquid raw material was sucked into the foamed small piece compact, it was removed from the mold and left for 24 hours. Subsequently, it was left in an oven heated to 80 ° C. for 3 hours to complete the curing, and a plate-like composite molded product of 300 w × 300 l × 30 t (mm) was obtained. Table 1 shows the conditions of the production process of the composite molded body of Comparative Example 1, and Table 2 shows the configuration and evaluation results of the obtained composite molded body.

Comparative Example 2
Using the expanded particles (weight 81 g) described in Example 2, 100 parts by weight of liquid unsaturated polyester resin (Nippon Iupika 4007A), 3 parts by weight of magnesium oxide, and 2 parts by weight of BPO (benzoyl peroxide) as a curing agent are cured. Premixed below the temperature at which the agent substantially decomposes. Subsequently, the preliminary mixture and the expanded particles were put in a container, and a mixing operation was performed so that the entire surface of the surface portion of the expanded particles was covered with the preliminary mixture. Next, a resin mold having inner dimensions of 295 mm in length, 295 mm in width, and 45 mm in depth is prepared. A large-sized polyethylene sheet is placed along the inner wall surface of the mold, and from above, the thickness of the container contents is increased. It was put in a mold so as to have a thickness of about 45 mm, further covered with a polyethylene sheet, and left in a 35 ° C. atmosphere for 3 days. The aggregate of uncured synthetic resin foam granules taken out from the mold is thickened to 295 mm in length, 295 mm in width, and 45 mm in thickness as a result of the unsaturated polyester resin being thickened into a solid or semi-solid state at room temperature. It was a thing. Next, the inside was put in an aluminum female mold heated to 110 ° C. whose surface was treated with polytetrafluoroethylene resin, and heated to 110 ° C. of the same material having a press mechanism corresponding to the female mold. Press with a male die (pressing pressure is 10 kgf / cm ² ) and hold it at that temperature for 40 minutes, then cool both dies to 60 ° C or lower, take out the light-weight molded product, 23 ° C, 50% RH For 48 hours. The lightweight molded body had a length of 295 mm, a width of 295 mm, and a thickness of 28 mm. Table 1 shows the conditions of the production process of the composite molded body of Comparative Example 2, and Table 2 shows the configuration and evaluation results of the obtained composite molded body.

  In addition, about the raw material used for the manufacturing method of the composite molded object of this invention, the physical property of the obtained composite molded object, etc., it measured and evaluated as follows.

(Bulk density of resin foam pieces)
The bulk density of the foamed resin pieces is selected by randomly extracting the foamed resin pieces, and in a 1 L graduated cylinder at a temperature of 23 ° C. and a relative humidity of 50%, the static density is removed while being naturally deposited. Thus, many foam pieces were accommodated to the scale of 1L, and it calculated | required by measuring the weight of the accommodated foam pieces next.

(Composite molded body density)
The density of the composite molded body was determined as being obtained by dividing the weight (g) of the composite molded body by the volume (cm ³ ) of the composite molded body determined by the submerging method. In addition, this density means the density of the whole composite molded object containing a hardened | cured material layer.

(Measurement of the average diameter of the foamed small piece portion in the cross section of the composite molded body, ie, the bubble diameter of the mesh)
The method for measuring the bubble diameter of the mesh was as follows. The obtained composite molded body was divided into two in the thickness direction, and an enlarged photograph of the cut surface was taken. Next, a straight line reaching the opposite surface from the surface of the composite molded body through the center was drawn on the photograph. Count the number of resin foam pieces that are crossed with.
Then, the length of the straight line (actual length) is divided by the resin foam piece to obtain the cell bubble diameter, and this operation is similarly performed for the five places of the composite molded body, and the average value of the obtained measurement values and did.

(Adhesive evaluation)
As a method for confirming the adhesiveness between the resin foam small piece molded body constituting the composite molded body and the network wall of the thermosetting resin, it can be confirmed by bending fracture. More specifically, in accordance with JIS K7221, a three-point bending test set to 100 mm between fulcrums (span) is usually performed after cutting into a test piece having a width of 20 mm, a thickness of 10 mm, and a length of 200 mm. A bending load was applied to the central part of the test piece at 5 mm / second, and the test was conducted until it broke and then the fracture surface was verified. It can be evaluated that the larger the number of resin foam pieces that have broken the material on the fracture surface, the higher the adhesiveness. However, the number of foam pieces that have been destroyed (Nb) and the number of foam pieces that have not been destroyed (Nn) In comparison, if the ratio Nb / Nn is not 1 or more, it cannot be evaluated that there is adhesiveness. That is, in the method for confirming the adhesiveness of a composite molded article obtained by the production method of the present invention, the value of the ratio of Nb / Nn is preferably 1 or more. When the value of Nb / Nn is 1 or less, there is a possibility that the mechanical strength such as bending, tension, shearing and the like may not be sufficiently exhibited, which is not preferable.

(Measurement of flexural modulus)
In the present invention, the measurement of the flexural modulus of the composite molded body is based on JIS K7203 (1982), and a test piece having a length of 150 mm × width 25 mm × thickness (product thickness) is cut out from the composite molded body and used. The measurement was performed under the conditions of R = 5 mm at the fulcrum tip, R = 5 mm at the indenter tip, the distance between the fulcrums of 50 mm, and the bending speed of 10 mm / min. In addition, about the test piece, ten test pieces were measured, the average value was calculated | required, and it was set as the bending elastic modulus.

(Measurement of thermal conductivity)
The measurement method of thermal conductivity measured the thermal conductivity of the composite molded body according to JIS A 1412-2 heat flow meter method (HFM method). The composite molded body was cut out into a test body having a size of 200 l × 200 w × 25 t (mm) (not including the cured product layer), and sandwiched between a heating plate and a cooling hot plate of the measuring device, and the temperature difference of the test body was 30 ° C. The measurement was performed at a temperature of 20 ° C.

In addition, about the obtained composite molded object, when the variation coefficient of the inner layer density of the thermosetting resin cured material of the test piece cut out from arbitrary five places was measured, although it was 5% in Example 1, it was a comparative example The value of 1 was 23%, which was an extremely large value compared to the example. Further, Comparative Example 1 tends to have an extremely low flexural modulus as compared with Example 1. This is because the cured product of the thermosetting resin formed by nonuniform resin impregnation is unevenly distributed in the thickness direction. Further, in Comparative Example 1, a thick cured layer is formed on the upper surface into which the thermosetting resin liquid raw material is poured, but since the cured layer is hardly formed on the lower surface side, the bending elastic modulus is extremely low. Conceivable.
Since the comparative example 2 stirred without making it pressure reduction in the process which impregnates a foam small piece molded object with a thermosetting resin, and obtained the composite molded object (light weight molded object) by the method different from Example 2, thermosetting The bending elastic modulus was lower than that of Example 2 because of the variation of the functional resin.

The method for producing a composite molded body of the present invention is obtained by impregnating and curing a thermosetting liquid raw material in a void portion of a foamed small piece molded body having a void portion with a porosity of 3 to 30% by volume, and curing it. It can be used as a method for producing a composite molded body that is lightweight and has excellent strength uniformity.
Since the composite molded body obtained by the production method of the present invention has strength that can be used as a substitute for a metal outer panel of a moving medium such as an automobile, a railway, a ship, and an airplane, weight reduction of these members is achieved. It is a composite molded article suitable for a core material that can be used as a structural material in various fields.
In addition, the composite molded body according to the manufacturing method of the present invention can increase the thickness with an effective shape in the thickness direction, improve the section modulus, and reduce the weight per projection surface, so it can be replaced with metal parts At the same time, it is possible to provide a method for manufacturing a composite molded body that can reduce the weight of the component and can maintain the cost at a social demand level.

1. 1. Resin foam pieces 2. Foam small piece compact 3. Thermosetting resin cured product 3 'Thermosetting resin liquid raw material 4. Internal space Type 5a. Upper mold 5b. Lower mold 6. Cavity part 7. Introduction hole 8. Vacuum suction pipe 10. Composite molded body

Claims (8)

A method for producing a composite molded body of a foamed small piece formed by molding a thermoplastic resin foam small piece and a thermosetting resin cured product,
Disposing a foamed small piece molded body having a continuous void and a porosity of 3 to 30% by volume in a mold having an internal space of a predetermined shape that can be sealed;
Sealing and depressurizing the internal space, introducing a thermosetting resin liquid raw material into the depressurized internal space, and impregnating the liquid raw material into the voids of the foamed piece molded body; and Curing,
The manufacturing method of the composite molded object characterized by including this.   The method for producing a composite molded body according to claim 1, wherein the internal space is decompressed to -0.01 to -0.1 MPa (G) before introducing the liquid raw material into the internal space.   The method for producing a composite molded article according to claim 1 or 2, wherein the liquid raw material has a viscosity of 100 to 10,000 mPa · s.   4. The composite molded body according to claim 1, wherein the liquid raw material is impregnated in a void portion of the foamed small piece molded body, and the periphery of the foamed small piece molded body is covered with the liquid raw material. Production method.   The thermosetting resin cured product is at least one selected from unsaturated polyester resins, epoxy resins, dicyclopentadiene resins, urethane resins, and polyimide resins. The manufacturing method of the composite molded object in any one.   The base resin of the resin foam piece is at least one selected from polyethylene resin, polypropylene resin, polystyrene resin, polyester resin, and polyvinyl chloride resin. The manufacturing method of the composite molded object in any one.   The method for producing a composite molded body according to any one of claims 1 to 6, wherein the foamed small piece molded body has a bulk density of 15 to 250 g / L.   The method for producing a composite molded body according to claim 6, wherein the base resin of the resin foam piece contains a polylactic acid resin.