JP2017186401A - Foam and method for producing foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foam having high strength while having low density and low thermal conductivity, and a method for producing such a foam.SOLUTION: A foam contains a filler dispersed in a cured body of thermosetting resin, the foam having a heat conductivity of 0.45 W/mK or less and a specific flexural strength representing a flexural strength per density of 100 MPa/(g/cm) or more and 300 MPa/(g/cm) or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a foam and a method for producing the foam.

  As a heat insulating material used for a building material, an electronic device, an in-vehicle component, etc., a material having a predetermined strength and a heat insulating property has been developed. As a material having heat insulation, for example, there is a composite molded article described in Patent Document 1. According to this document, it is described that a composite molded product including a heat radiating portion and a heat insulating portion is obtained by integrating a resin molded portion and a metal molded portion.

JP 2014-156100 A

  However, the present inventor needs to increase the density of the composite molded body described in the above-mentioned literature in order to impart strength and heat insulating properties. It has been found that there is room for improvement in terms of points.

  The present invention provides a foam having high strength while having low density and low thermal conductivity, and a method for producing such a foam.

According to the present invention, a foam in which a filler is dispersed in a cured body of a thermosetting resin having a thermal conductivity of 0.45 W / mK or less and a specific bending strength indicating a bending strength per density, A foam that is 100 MPa / (g / cm ³ ) or more and 300 MPa / (g / cm ³ ) or less is provided.

  According to the present invention, there is provided a foam production method for producing the above foam, wherein a slurry in which a thermosetting resin, a filler, and a thermally expandable microcapsule are mixed is prepared, and the slurry is made. A step of obtaining a foamable paper product, disposing the foamable paper product in a part of a mold, and expanding the thermally expandable microcapsule to expand the foam to the whole inside of the mold. And a step of obtaining a foam composed of a molded body of the foamable papermaking body by expanding the papermaking body.

  ADVANTAGE OF THE INVENTION According to this invention, the foam excellent in the balance of heat conductivity, lightness, and intensity | strength is provided. Moreover, according to this invention, the manufacturing method of such a foam is provided.

It is a perspective schematic diagram which shows an example of the foamable papermaking concerning this embodiment. It is a cross-sectional schematic diagram which shows an example of the manufacturing method of the foamable papermaking concerning this embodiment. It is a cross-sectional schematic diagram which shows an example of the manufacturing method of the foam which concerns on this embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.

The foam according to the present embodiment is a foam in which a filler is dispersed in a cured body of a thermosetting resin, and has a thermal conductivity of 0.45 W / mK or less and a specific bending that shows a bending strength per density. The strength is 100 MPa / (g / cm ³ ) or more and 300 MPa / (g / cm ³ ) or less. The foam of this embodiment consists of a cured body of a thermosetting resin in which a filler is dispersed, and has the above-described thermal conductivity and specific strength. Such foams have excellent mechanical properties and heat resistance while having low density and low thermal conductivity. In other words, the balance of density, thermal conductivity and strength is excellent. Such a foam is useful as a heat insulating material.

  In one embodiment, the foam is composed of a foamed paper product. The molded body of the foamable papermaking body refers to a molded body obtained by thermoforming a papermaking body containing a thermosetting resin, a filler, and a foaming agent. By using a molded body as a foam, a foam having a good balance between density and strength can be obtained.

  In one embodiment, the foam includes a fiber filler. In a preferred embodiment, the foam comprises a foamed paper product comprising a fiber filler. By using the fiber filler, the mechanical strength and heat resistance of the obtained foam can be improved, and the thermal conductivity of the foam can be controlled by the thermal conductivity of the fiber filler.

In one embodiment, the foam has a specific tensile strength (tensile strength per density) at room temperature of 10 MPa / (g / cm ³ ) or more and 300 MPa / (g / cm ³ ) or less. Preferably, the specific tensile strength of the foam is from 20 MPa / (g / cm ³ ) to 250 MPa / (g / cm ³ ), more preferably from 40 MPa / (g / cm ³ ) to 200 MPa / (g / cm ³ ) or less. The foam having the above values is useful as a heat insulating material. This tensile strength can be measured by, for example, a tensile tester (Tensilon Universal Material Tester, manufactured by A & D).

In one embodiment, the specific flexural modulus at room temperature (flexural modulus per density) of the foam is 1 GPa / (g / cm ³ ) or more and 20 GPa / (g / cm ³ ) or less. Preferably, the specific flexural modulus of the foam is 2 GPa / (g / cm ³ ) or more and 18 GPa / (g / cm ³ ) or less, more preferably 4 GPa / (g / cm ³ ) or more and 16 GPa / (g / Cm ³ ) or less. A foam having a specific bending elastic modulus within the above range is useful as a heat insulating material. This bending elastic modulus can be measured according to JIS K-7171.

In one embodiment, the density of the foam is 0.1 g / cm ³ or more and 1.6 g / cm ³ or less. Preferably, the lower limit of the density of the foam is 0.2 g / cm ³ or more, and more preferably 0.3 g / cm ³ or more. The upper limit of the density of the foam, preferably at most 1.55 g / cm ³ or less, more preferably 1.50 g / cm ³ or less. A foam having a density within the above range is useful as a heat insulating material because it is lightweight and has excellent mechanical strength. The density can be obtained by a method based on the JIS K-7112 A method.

  In one embodiment, the volume porosity of the foam is 5% or more and 90% or less. Preferably, the lower limit value of the volume porosity is 10% or more, and more preferably 15% or more. Further, the upper limit value of the volume porosity is preferably 80% or less, and more preferably 70% or less. A foam having a volume porosity within the above range is useful as a heat insulating material because of its excellent balance of thermal conductivity, strength and lightness.

  The volume porosity of the foam can be calculated by, for example, an image analysis method. Specifically, first, the vicinity of the center of the foam is cut out, the image of the cross section of the cut out foam is binarized, and the area of the matrix phase made of thermosetting resin and the area of the bubble phase made of bubbles are measured. . Thereafter, the ratio of the measured areas is calculated as the volume porosity.

  In one embodiment, the foam has a closed cell structure or an open cell structure. In a preferred embodiment, the foam has only a closed cell structure or a mixed structure of closed cell structure and open cell structure. A foam having such a cell structure is excellent in balance between lightness and thermal conductivity.

  In the present embodiment, the closed cell structure means a structure having a plurality of spaces (bubbles) isolated from the outside by a cured product of a thermosetting resin. In such a closed cell structure, since gas is suppressed from passing between adjacent spaces, a structure excellent in airtightness can be realized.

  When the foam has a closed cell structure, the lower limit of the bubble size may be, for example, 5 μm or more, or 10 μm or more. On the other hand, the upper limit value of the bubble size is not particularly limited, but may be, for example, 500 μm or less, or 400 μm or less.

  In one embodiment, the lower limit value of the glass transition temperature (Tg) of the foam may be, for example, 100 ° C. or higher, preferably 120 ° C. or higher, and more preferably 150 ° C. or higher. Thereby, the heat resistance of a foam can be improved. The foam having such a glass transition temperature can be used, for example, in a place where a heat history such as a heat generating member occurs or in an environment exposed to a high temperature. On the other hand, the upper limit value of the glass transition temperature (Tg) of the foam can be, for example, 350 ° C. or lower. The glass transition temperature (Tg) can be measured by, for example, a differential scanning calorimeter (DSC-2920, manufactured by TA Instruments).

  In addition, the characteristic of said foam can be suitably adjusted by changing the kind and compounding quantity of the thermosetting resin to be used, a filler, and a foaming agent.

  In a preferred embodiment, the foam is a molded body obtained by thermoforming a foamable paper-making body including a thermosetting resin, a fiber filler, and a thermally expandable microcapsule that is a foaming agent. Such a foam is lightweight but has low thermal conductivity and excellent strength. Therefore, it is useful as a heat insulating material.

  Hereinafter, the foam of the present invention will be described by taking as an example an embodiment in which the foam is made of a formed body of a papermaking product containing a fiber filler.

<Foaming paper 10>
FIG. 1 is a schematic perspective view showing an example of a foamable papermaking product 10 in the present embodiment.
As shown in FIG. 1, the foamable papermaking product 10 includes a thermosetting resin A, a fiber filler B, and a thermally expandable microcapsule C.

  Here, the “papermaking” used in this specification will be described. The papermaking body is obtained by a papermaking method from a material slurry containing a fiber filler and a resin. The papermaking method refers to a wet papermaking method, that is, a papermaking technique which is one of papermaking techniques.

  The terms “papermaking method” and “papermaking body” are obtained by using a method of papermaking a fiber material as described in, for example, Patent Publication 1 (Patent No. 4675276) and Patent Publication 2 (Patent No. 5426399). Generally used as a technical term to indicate the state of a given object. According to this document, a papermaking product refers to a wet solid content remaining on a filter after a raw material slurry in which raw materials such as fibers and resins are dispersed in a dispersion medium is passed through a filter, and the liquid is removed. , And is described. The wet state here means an uncured state of the resin before the heat treatment, that is, an uncured state before post-curing.

  In the present embodiment, the foamable paper-making body 10 may be a sheet shape or a three-dimensional shape processed into a shape imitating a desired molded product shape (that is, a shape of an element). And the molded object (foaming molded object 50) which is a hardening body of the foamable papermaking object 10 can be obtained by performing foam molding by heat processing etc. with respect to this expandable papermaking object 10. FIG.

The foamable papermaking body 10 according to the present embodiment is obtained by a papermaking method.
As shown in FIG. 1, the foamable papermaking body 10 obtained by the papermaking method has structural features 1 to 3 in the following points.
(Feature 1) The fiber filler B and the thermally expandable microcapsule C are randomly oriented in a plan view of the surface of the foamable papermaking body 10.
(Characteristic 2) In the cross-sectional view in the thickness direction of the foamable papermaking product 10, the orientation state of the fiber filler B is highly controlled, and the fiber filler B is oriented in a specific direction. In other words, the fiber filler B is in a laminated state in the thickness direction of the foamable papermaking product 10.
(Feature 3) The fiber fillers B are bound together by the thermosetting resin A.
As described above, in the foamable papermaking product 10 shown in FIG. 1, the thermosetting resin A, the fiber filler B, and the thermally expandable microcapsule C are randomly entangled in the surface direction, and such a surface structure is in the thickness direction. It has a papermaking structure that overlaps

Moreover, the foamable papermaking body 10 can be formed into a desired shape by foaming and curing by heat treatment.
The thermosetting resin A in the foamable papermaking product 10 is not completely cured, for example, in a B stage state. Therefore, the foamable papermaking product 10 can be deformed into another shape. More specifically, the foamable paper product 10 is heated at the curing temperature of the thermosetting resin A to completely cure the thermosetting resin A, and the thermally expandable microcapsule C contained in the foamable paper product is used. By foaming, it is possible to obtain a foamed molded body 50 in which bubbles are dispersed.

Subsequently, the component which comprises the foamable papermaking body 10 is demonstrated.
(Thermosetting resin A)
The thermosetting resin A is a resin that can be cured by heat treatment and become a foam. Moreover, the thermosetting resin A contained in the foamable papermaking body 10 functions as a binder (binder resin) that connects between the fiber fillers B.

Examples of such thermosetting resins include phenol resins, epoxy resins, unsaturated polyester resins, melamine resins, polyurethanes, and the like. These resins can be appropriately selected and used as necessary, and one kind may be used alone, or two or more kinds may be used in combination.
From the viewpoint of mechanical properties and heat resistance of the foamed molded product 50 obtained by curing the foamable papermaking product 10, it is preferable to use a phenol resin or an epoxy resin. Moreover, it is preferable to use a phenol resin from a viewpoint of the heat conductivity and intensity | strength of the foaming molding obtained.

  The thermosetting resin A may be in the form of particles or powder. Thereby, the intensity | strength of the foaming molding 50 obtained by foaming and hardening the foamable papermaking body 10 can be improved effectively. The reason for this is not clear, but when the foamable papermaking product 10 is heated and pressurized to be foamed, the thermosetting resin A has a granular or powdery form, so that the fiber filler B can be impregnated during melting. It is estimated that the interface between the fiber filler B and the thermosetting resin A is well formed.

  As the thermosetting resin A, for example, it is preferable to use a resin that has an average particle diameter of 500 μm or less and is in a solid state at room temperature. Thereby, in the manufacturing process of the foamable papermaking body 10, the thermosetting resin A tends to aggregate. Moreover, in the manufacturing process of the foamable papermaking body 10, from the viewpoint of obtaining a varnish-like material composition, the average particle size of the thermosetting resin A is more preferably 1 nm or more and 300 μm or less.

The thermosetting resin A having such an average particle diameter can be obtained, for example, by pulverizing an untreated thermosetting resin using an atomizer pulverizer.
In addition, the average particle diameter of the thermosetting resin A is obtained, for example, by using a laser diffraction particle size distribution measuring apparatus such as SALD-7000 manufactured by Shimadzu Corporation as a mass-based 50% particle diameter. be able to.

  The thermosetting resin A contained in the foamable papermaking product 10 is preferably in a semi-cured state. The semi-cured thermosetting resin A is completely cured in the foaming and molding process of the foamable papermaking product 10 by heating and pressing. Thereby, the foaming molding 50 excellent in the balance of intensity | strength, lightness, and heat conductivity is obtained.

(Fiber filler B)
The fiber filler B used for the foam of the present invention is a fiber yarn having a predetermined fiber length. In the present invention, strength can be imparted to the foam by using the fiber filler B. Furthermore, the thermal conductivity and density of the obtained foam can be controlled by the thermal conductivity and density of the fiber filler B used.

  From the viewpoint of obtaining a papermaking structure, the average fiber length of the fiber filler B is preferably 0.1 mm or more, more preferably 2 mm or more, from the viewpoint of obtaining the mechanical strength of the resulting papermaking body or molded body. More preferably, it is 2.5 mm or more, and particularly preferably 4 mm or more. On the other hand, from the viewpoint of obtaining good dispersibility in the papermaking body, it is preferably 20 mm or less, more preferably 15 mm or less, and further preferably 12 mm or less.

  Examples of the fiber filler B that can be used in the foam of the present invention include aramid fiber, glass fiber, carbon fiber, ceramic fiber, wholly aromatic polyester fiber, wholly aromatic polyester amide fiber, wholly aromatic polyether fiber, Wholly aromatic polycarbonate fiber, wholly aromatic polyazomethine fiber, polyphenylene sulfide (PPS) fiber, poly (para-phenylenebenzobisthiazole) (PBZT) fiber, polybenzimidazole (PBI) fiber, polyether ether ketone (PEEK) fiber , Polyamideimide (PAI) fiber, polyimide fiber, polytetrafluoroethylene (PTFE) fiber, poly (para-phenylene-2,6-benzobisoxazole) (PBO) fiber. These fiber fillers B may be used alone or in combination of two or more.

  Furthermore, from the viewpoint of improving the balance between the lightness and strength of the foam, inorganic fibers may be used, and glass fibers are more preferably used. Moreover, when using glass fiber, you may use what gave the aminosilane process. The aminosilane treatment is performed by impregnating glass fibers with an amino group-containing silane coupling agent solution, or by applying an amino group-containing silane coupling agent solution to glass fibers.

  Examples of amino group-containing silane coupling agents include N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, and γ-aminopropyl. Methyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, N- (β An amino group-containing alkoxysilane such as (aminoethyl) -γ-aminopropylmethyldiethoxysilane, and hydrolysates thereof. These amino group-containing silane coupling agents may be used alone or in combination of two or more.

  From the viewpoint of increasing strength, the content of the fiber filler B may be, for example, 10% by weight or more, or 20% by weight or more with respect to the thermosetting resin A. Further, from the viewpoint of improving the balance of strength, lightness and thermal conductivity, the content of the fiber filler B may be, for example, 80% by weight or less, or 75% by weight or less with respect to the thermosetting resin A. Alternatively, it may be 70% by weight or less, or 50% by weight or less.

(Thermal expansion microcapsule C)
The thermally expandable microcapsule C is a particle obtained by microencapsulating a volatile liquid foaming agent with a thermoplastic shell polymer having a gas barrier property. The thermally expandable microcapsule C functions as a foaming agent by the following mechanism. That is, while the outer shell of the capsule is softened by heating, the liquid foaming agent contained in the capsule is vaporized and the pressure is increased. As a result, the particles expand to form hollow spherical particles (foamed particles of the thermally expandable microcapsule C), thereby forming bubbles in the resin.

Examples of the liquid blowing agent include low boiling point hydrocarbons such as isopentane, isobutane, and isopropane.
Examples of the thermoplastic shell polymer include polyacrylonitrile, vinylidene chloride-acrylonitrile copolymer, vinylidene chloride-methyl methacrylate copolymer, vinylidene chloride-ethyl methacrylate, acrylonitrile-methyl methacrylate copolymer, acrylonitrile-ethyl methacrylate, and the like. Can be mentioned. These may be used alone or in combination of two or more.

  Examples of the thermally expandable microcapsule C include Expancel (manufactured by Nippon Philite), Microsphere F50, Microsphere F60 (manufactured by Matsumoto Yushi Seiyaku Co., Ltd.), Advancel EM (manufactured by Sekisui Chemical Co., Ltd.), and the like. Commercial products can be used.

  From the viewpoint of reducing the density of the foamed molded product 50 without reducing the strength of the foam 50 and reducing the thermal conductivity, the content of the thermally expandable microcapsule C is relative to the thermosetting resin A. It may be 0.05% by weight or more, or 0.1% by weight or more. Further, from the viewpoint of imparting an appropriate strength to the foamed molded product 50, it may be 10% by weight or less or 5% by weight or less with respect to the thermosetting resin A.

  In addition, the foamable papermaking product 10 according to the present embodiment may include other components such as pulp, aggregating agent, and various additives in addition to the above components as necessary.

(pulp)
The foamable papermaking body 10 of the present embodiment may include pulp. Pulp is a fiber having a fibril structure and refers to a fiber different from the fiber filler B. Pulp can be obtained, for example, by mechanically or chemically fibrillating the fiber material.
In the step of obtaining the foamable papermaking product 10 by the papermaking method, the thermosetting resin A, the fiber filler B, and the thermally expandable microcapsule C can be more effectively aggregated by using pulp. Therefore, it becomes possible to realize more stable production of the foamable papermaking product 10.

  Examples of the pulp include cellulose fibers such as linter pulp and wood pulp, natural fibers such as kenaf, jute and bamboo, para-type wholly aromatic polyamide fibers (aramid fibers) and copolymers thereof, aromatic polyester fibers, poly Examples include fibrillated organic fibers such as benzazole fibers, meta-type aramid fibers and copolymers thereof, acrylic fibers, acrylonitrile fibers, polyimide fibers, and polyamide fibers. Pulp may be used individually by 1 type and may use 2 or more types together.

  The content of the pulp may be 0.5% by weight or more, 1% by weight or more, or 2% by weight or more with respect to the thermosetting resin A. This makes it easier to aggregate the materials in the paper making process. On the other hand, the pulp content may be 10% by weight or less, 8% by weight or less, or 5% by weight or less with respect to the thermosetting resin A. Thereby, the target foaming molding 50 can be obtained, without impairing mechanical characteristics, such as intensity | strength.

(Flocculant)
The foamable papermaking body 10 of the present embodiment may include a flocculant. The aggregating agent has a function of aggregating the thermosetting resin A, the fiber filler B, and the thermally expandable microcapsule C in the form of a floc during the production of the foamable papermaking product 10. For this reason, manufacture of the more stable foamable papermaking body 10 is realizable.

  Examples of the flocculant include a cationic polymer flocculant, an anionic polymer flocculant, a nonionic polymer flocculant, and an amphoteric polymer flocculant. More specifically, for example, cationic polyacrylamide, anionic polyacrylamide, Hoffman polyacrylamide, mannic polyacrylamide, amphoteric copolymerized polyacrylamide, cationized starch, amphoteric starch, polyethylene oxide and the like can be mentioned. These flocculants may be used individually by 1 type, and may use 2 or more types together. In the flocculant, the polymer structure and molecular weight, the amount of functional groups such as hydroxyl groups and ionic groups, and the like can be adjusted according to the required characteristics.

  The content of the flocculant may be 0.01% by weight or more, 0.05% by weight or more, or 0.1% by weight or more with respect to the thermosetting resin A. Thereby, in manufacture of the foamable papermaking body 10, the improvement of a yield can be aimed at. On the other hand, the content of the flocculant may be 1.5% by weight or less, 1% by weight or less, or 0.5% by weight or less with respect to the thermosetting resin A. Thereby, in manufacture of the foamable papermaking body 10 using a papermaking method, a dehydration process etc. can be performed more easily.

  The foamable papermaking product 10 may contain other additives depending on the production conditions and desired properties. Examples of additives include thermoplastic resins, inorganic powders for improving properties, metal powders, stabilizers such as antioxidants and ultraviolet absorbers, flame retardants, mold release agents, plasticizers, resin curing catalysts, Curing accelerators, pigments, paper strength improvers such as dry paper strength improvers, wet paper strength improvers, yield improvers, drainage improvers, size fixers, rosin sizing agents for acidic papermaking, rosins for neutral papermaking Examples include sizing agents such as sizing agents, alkyl ketene dimer sizing agents, alkenyl succinic anhydride sizing agents, and specially modified rosin sizing agents, and coagulants such as sulfate bands, aluminum chloride, and polyaluminum chloride.

  Especially, it is preferable that the foamable papermaking body 10 contains an aramid microfiber as an additive. By using the aramid microfibers, it is possible to improve the handling properties of the papermaking body obtained by drying the foamable papermaking body 10.

<Method for Producing Foamable Paper 10>
FIG. 2 is a schematic cross-sectional view showing the manufacturing process of the foamable papermaking product 10.
The method for producing the foamable paper product 10 of the present embodiment comprises mixing the thermosetting resin A, the fiber filler B, and the thermally expandable microcapsule C, and then papermaking the mixture by a papermaking method. 10 is obtained.

  Hereinafter, with reference to FIG. 2, the manufacturing method of the foamable papermaking body 10 by a wet papermaking method is explained in full detail.

  First, as shown to Fig.2 (a), the thermosetting resin A, the fiber filler B, and the thermally expansible microcapsule C are added to a solvent, and it stirs, mixes, and disperses. At this time, of the above-described components, other components excluding the flocculant are added to the solvent. The varnish-like material composition (slurry) for forming the foamable papermaking body 10 can be obtained according to the said process.

  Examples of a method for dispersing each component in a solvent include a method of stirring using a disperser.

  As a solvent for preparing the material slurry, it is difficult to volatilize in the process of dispersing the above materials, it is easy to remove the solvent in order to reduce the residual in the papermaking, and the increase in energy due to the solvent removal can be suppressed. In view of the above, a solvent having a boiling point of 50 ° C. or higher and 200 ° C. or lower is preferable. Examples of such solvents include water; alcohols such as ethanol, 1-propanol, 1-butanol, and ethylene glycol; ketones such as acetone, methyl ethyl ketone, 2-heptanone, and cyclohexanone; ethyl acetate, butyl acetate, and methyl acetoacetate. And esters such as methyl acetoacetate; ethers such as tetrahydrofuran, isopropyl ether, dioxane and furfural. These solvents may be used alone or in combination of two or more. Among these, it is particularly preferable to use water because the supply amount is abundant, the cost is low, the environmental load is low, the safety is high, and the handling is easy.

  Subsequently, the above-mentioned flocculant is added to the obtained slurry. Thereby, the thermosetting resin A, the fiber filler B, and the thermally expandable microcapsule C in the solvent can be more easily aggregated in a floc form to obtain the aggregate F (FIG. 2B). ).

  Then, the foamable papermaking body 10 is obtained by making the slurry which mixed the thermosetting resin A, the fiber filler B, the thermally expansible microcapsule C, etc. with a filter.

Specifically, as shown in FIG. 2B, the above slurry is introduced into a container having a sheet-like mesh 30 (filter) on the bottom surface. Then, the solvent in the slurry is passed through the mesh 30 and discharged out of the container, and the aggregate F in the slurry is left on the mesh 30 (filter). Thereby, the aggregate F and the solvent can be separated from each other.
Here, it is possible to adjust the shape of the foamable papermaking body 10 obtained by selecting the shape of the mesh 30 suitably.
Thereafter, the agglomerate F obtained on the filter (mesh 30) may be subjected to a drying treatment, for example, in a drying furnace to further remove the solvent remaining in the agglomerate F.
As described above, the foamable papermaking product 10 shown in FIG. 2C is manufactured.

By using a papermaking method as shown in FIG. 2 (b), the foamable papermaking body 10 is formed along the surface of the filter. Such a foamable papermaking body 10 has a structure in which fiber fillers B entangled randomly in the plane direction are laminated in the thickness direction. By having a structure in which the fiber fillers B are entangled, it is possible to obtain a foamable papermaking product 10 that is lightweight but has excellent strength.
Moreover, the dispersibility of the thermally expandable microcapsule C in the foamable papermaking product 10 can be improved by using the papermaking method.

<Foamed molded product 50>
The foamed molded product 50 of the present embodiment is a molded product of the foamable papermaking product 10 and has a cell structure in which bubbles D formed by foaming the thermally expandable microcapsules C are dispersed in the molded product.

<Method for Manufacturing Foam Molded Body 50>
The manufacturing method of the foaming molding 50 of this embodiment prepares the slurry which mixed the thermosetting resin A, the filler (fiber filler B), and the thermally expansible microcapsule C, and foams by making this slurry into paper. Obtaining the papermaking body 10;
The foamable papermaking body 10 is disposed in a part of the inside of the molds 40 and 41, the thermally expandable microcapsule C is expanded, and the foamable papermaking body 10 is expanded to the whole inside of the molds 40 and 41. The process of obtaining the foam (foaming molding 50) which consists of a molding of the foamable papermaking body 10 by this can be included.

FIG. 3 is a schematic cross-sectional view showing an example of a method for producing a foam according to the present embodiment.
Hereinafter, with reference to FIG. 3, the manufacturing method of the foaming molding 50 is explained in full detail.

  First, as shown to Fig.3 (a), the foamable papermaking body 10 is arrange | positioned inside the metal mold | die 40,41 (metal mold cavity). At this time, the volume of the mold cavity including the mold 40 and the mold 41 is assumed to be larger than the volume of the foamable papermaking product 10. Thereby, the foamable papermaking body 10 which is a raw material can be arrange | positioned in the state which the inside of metal mold | die 40,41 is not completely filled, ie, what is called a short shot.

  Next, foam molding is performed on the foamable papermaking product 10. For example, as shown in FIG. 3B, the heat-expandable microcapsule C is expanded by the heat treatment, and the foamable papermaking product 10 is expanded. The expanded foamed paper product 10 is filled in the entire mold cavity. At this time, the foamable papermaking product 10 is formed by the internal pressure (stress from the molds 40 and 41) due to the foaming of the thermally expandable microcapsule C, and the foamed molded product 50 is obtained. Thereby, it can shape | mold to the foaming molding 50 which has a predetermined shape.

In the foam molding step described above, the curing reaction of the thermosetting resin A proceeds, and a cured resin body having a three-dimensional network structure is formed in the foam molded body 50. Further, the thermally expandable microcapsule C expands by the above heat treatment, and bubbles D (hollow spherical particles) are formed.
Thus, the foaming molding 50 of this embodiment can be manufactured by the short shot method. By using the short shot method, the foamable papermaking product 10 can be formed using the foaming pressure generated by the expansion of the bubbles of the thermally expandable microcapsule C.

  Although the said heat processing is not specifically limited, For example, it is good also as about 160-250 degreeC and about 10 to 30 minutes. In the manufacturing method of the foam molded body 50 of the present embodiment, the molding pressure is not applied from the outside, but the internal pressure in the molds 40 and 41 is, for example, about 1.5 to 5 MPa.

Here, as a method of applying molding pressure from the outside, there is an injection molding method or the like. However, in the injection molding method, the thermally expandable microcapsule does not foam or the bubbles are destroyed due to the filling pressure or holding pressure.
On the other hand, in the manufacturing method of the foamed molded product 50 of this embodiment, since no molding pressure is applied from the outside, unexpanded of the thermally expandable microcapsule C and destruction of the bubbles D can be sufficiently suppressed. .

  The thermal conductivity, density, and mechanical properties of the foam of this embodiment can be changed by changing the type and amount of components such as the thermosetting resin A, filler, and thermally expandable microcapsule used for the foamable papermaking product 10. Or it can adjust to a desired value by changing the manufacturing conditions of the foamable papermaking body 10 and the foaming molding 50. Among these, for example, glass fiber is used as the fiber filler B, the dispersibility of the fiber filler B and the thermally expandable microcapsule C is improved by a papermaking method, and the magnification and size of the bubbles are appropriately set by the short shot method. The control method is an effective method for keeping the above characteristics within a desired range.

  The foam of this embodiment can be used as a heat insulating material used for, for example, building materials, electronic devices, vehicle-mounted components, and the like.

  As mentioned above, although embodiment of this invention was described with reference to drawings, these are the illustrations of this invention, Various structures other than the above are also employable.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail with reference to an Example, this invention is not limited to description of these Examples at all.

The materials used in Examples and Comparative Examples are as follows.
(Thermosetting resin)
Thermosetting resin 1: phenol resin (phenol resin “PR51723”, manufactured by Sumitomo Bakelite Co., Ltd.)
(Filler)
Fiber filler 1: Glass fiber (chopped strand “CS3J 891”, manufactured by Nittobo Co., Ltd.)
Fiber filler 2: Carbon fiber (Tenax “HT C110”, manufactured by Toho Tenax Co., Ltd.)
Fiber filler 3: Aramid fiber (Technora “T32PNW”, manufactured by Teijin Limited)
(Foaming agent)
Foaming agent 1: Thermally expandable microcapsule ("Advancel (registered trademark) EM-304", manufactured by Sekisui Chemical Co., Ltd.)
(Other additives)
Aramid microfiber 1: Aramid microfiber ("Tiara", manufactured by Daicel FineChem Co., Ltd.)

<Examples 1-5>
(Manufacture of foamable paper products)
In Examples 1 to 5, foamable paper products were produced in the following manner at the blending ratios shown in Table 1 (raw material volume fraction [Vol%] after foam molding).
First, a thermosetting resin, a filler, a foaming agent and an additive pulverized to an average particle size of 100 μm (50% particle size based on mass) with an atomizer pulverizer are added to water, and the mixture is stirred for 30 minutes with a disperser. Got. Here, it added to 10000 weight part of water with respect to a total of 100 weight part of the constituent material which consists of a thermosetting resin, a filler, a foaming agent, and an additive.
Next, a flocculant (synthetic smectite: smecton (manufactured by Kunimine Kogyo Co., Ltd.)) dissolved in water in advance was added in an amount of 0.2% by weight based on the total of the constituent materials described above, and the constituent materials were aggregated in a floc form. .
Subsequently, the obtained agglomerates were separated from water with a 30 mesh metal net. Thereafter, the agglomerates remaining on the metal net were subjected to dehydration pressing, and further placed in a drier at 70 ° C. for 3 hours for drying to obtain a foamable paper product. The yield was 97%.

(Manufacture of foam)
The obtained foamable papermaking product was placed in a 4 mm-thick mold and subjected to heat treatment at 180 ° C. for 10 minutes to produce a foamed product made of a foamed molded product. At this time, the internal pressure in the mold was 2 MPa. Examples 1-4 performed foam molding by the short shot method. The following evaluation was performed about the obtained foam. The results are shown in Table 1. In addition, the raw material volume fraction after foam molding of the foaming agent in Table 1 indicates the volume porosity of the foam.

<Comparative Examples 1-2>
In Comparative Examples 1 and 2, a papermaking product was produced in the following manner at the blending ratio shown in Table 1 (raw material volume fraction after compression molding [Vol%]).
First, a thermosetting resin pulverized to an average particle size of 100 μm (50% particle size based on mass) with an atomizer pulverizer, a filler, and an additive are added to water, and the mixture is stirred for 30 minutes with a disperser. Got. Here, it added to 10000 weight part of water with respect to a total of 100 weight part of the constituent material which consists of a thermosetting resin, a filler, and an additive.

Next, a flocculant (synthetic smectite: smecton (manufactured by Kunimine Kogyo Co., Ltd.)) dissolved in water in advance was added in an amount of 0.2% by weight based on the total of the constituent materials described above, and the constituent materials were aggregated in a floc form. .
Subsequently, the obtained agglomerates were separated from water with a 30 mesh metal net. Thereafter, the agglomerates remaining on the metal net were subjected to dehydration pressing, and further placed in a drier at 70 ° C. for 3 hours for drying to obtain a papermaking product. The yield was 97%.

(Manufacture of non-foamed products)
In Comparative Example 1, the obtained papermaking product was placed in a 4 mm-thick mold, subjected to heat treatment at 180 ° C. for 10 minutes, and a non-foamed product made of the papermaking product was produced by compression molding. At this time, the molding pressure in the mold was 10 MPa. The following evaluation was performed about the obtained non-foamed body. The results are shown in Table 1.

＊...測定不能

* ... measurable

(Evaluation)
Density: measured by a method based on JIS K-7112 A method.
-Thermal conductivity: It measured by the method based on JISR-1611.
-Bending strength: It measured by the method based on JISK-7171.
Specific bending strength: Calculated by dividing the bending strength by the density.
Flexural modulus: measured by a method based on JIS K-7171.
Specific flexural modulus: Calculated by dividing the flexural modulus by the density.
-Tensile strength: Measured by a method based on JIS K-7162 using a tensile tester (Tensilon Universal Material Tester, manufactured by A & D).
Specific tensile strength: Calculated by dividing the tensile strength by density.
The above measurement was performed at room temperature (25 ° C.).

  It turned out that the foam of Examples 1-5 is excellent in thermal conductivity, intensity | strength, and the balance of lightweight. Moreover, as a result of performing cross-sectional observation of the foams of Examples 1 to 5, it was found that the foams had a closed cell structure. On the other hand, the non-foamed body of Comparative Example 1 had a high density and thermal conductivity, and the non-foamed body of Comparative Example 2 had a high thermal conductivity.

  As described above, the present invention has been described more specifically based on the embodiments. However, these are exemplifications of the present invention, and various configurations other than the above can be adopted.

DESCRIPTION OF SYMBOLS 10 Expandable paper-making body 30 Mesh 40 Mold 41 Mold 50 Foam molded body A Thermosetting resin B Fiber filler C Thermal expansion microcapsule D Bubble F Aggregate

Claims (11)

A foam in which a filler is dispersed in a cured body of a thermosetting resin,
The thermal conductivity is 0.45 W / mK or less,
Specific flexural strength shows the bending strength per ^{density, 100MPa / (g / cm 3} ) or more 300MPa / (g / cm ³⁾ or less, foam. The foam according to claim 1,
A foam comprising a foamed paper product. The foam according to claim 1 or 2,
A foam in which the filler comprises a fiber filler. The foam according to any one of claims 1 to 3,
Specific tensile strength indicates tensile strength per density at room ^{temperature, 10MPa / (g / cm 3} ) or more 300MPa / (g / cm ³⁾ or less, foam. The foam according to any one of claims 1 to 4,
Specific flexural modulus indicating a flexural modulus per density at room ^{temperature, 1GPa / (g / cm 3} ) or more 20GPa / (g / cm ³⁾ or less, foam. The foam according to any one of claims 1 to 5,
A foam having a density of 0.1 g / cm ³ or more and 1.6 g / cm ³ or less. The foam according to any one of claims 1 to 6,
A foam having a volume porosity of 5% or more and 90% or less. The foam according to any one of claims 1 to 7,
A foam having a closed cell structure. The foam according to any one of claims 3 to 8,
The fiber filler is aramid fiber, glass fiber, carbon fiber, metal fiber, ceramic fiber, wholly aromatic polyester fiber, wholly aromatic polyester amide fiber, wholly aromatic polyether fiber, wholly aromatic polycarbonate fiber, wholly aromatic poly Azomethine fiber, polyphenylene sulfide (PPS) fiber, poly (para-phenylenebenzobisthiazole) (PBZT) fiber, polybenzimidazole (PBI) fiber, polyetheretherketone (PEEK) fiber, polyamideimide (PAI) fiber, polyimide, A foam comprising at least one selected from the group consisting of polytetrafluoroethylene (PTFE) fibers and poly (para-phenylene-2,6-benzobisoxazole) (PBO) fibers. The foam according to any one of claims 1 to 9,
A foam in which the thermosetting resin contains an epoxy resin or a phenol resin. A method for producing a foam for producing the foam according to any one of claims 1 to 10,
Preparing a slurry in which the thermosetting resin, the filler, and the thermally expandable microcapsule are mixed, and obtaining the foamable paper product by paper making the slurry; and
By disposing the foamable paper product in a part of the mold, expanding the thermally expandable microcapsule, and expanding the foamable paper product to the entire interior of the mold, thereby expanding the foam. And a step of obtaining a foam composed of a molded product of the characteristic papermaking body.

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