JP2024005403A - Method for producing sandwich panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique that can improve the production efficiency of a sandwich panel.

SOLUTION: A method for producing a sandwich panel 100 includes the steps of preparing a plurality of resin sheets a, a plurality of sheet-like substrates b, and a sheet-like core layer c having a honeycomb structure; disposing, on each side of the core layer c, a resin sheet a1, a sheet-like substrate b, and a resin sheet a2 in this order; and combining all of the core layer c, the resin sheets a, and the sheet-like substrates b into a laminate through heat and pressure treatment.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a method of manufacturing a sandwich panel.

A sandwich panel is composed of a hollow honeycomb core with walls having a hexagonal cross section, and a pair of skin materials such as prepregs bonded to both sides of the honeycomb core. Sandwich panels, which are lightweight and highly rigid, are used, for example, as structural members for aircraft.

Various methods have been disclosed as methods for manufacturing sandwich panels. As a general method, for example, there is a technique described in Patent Document 1. According to this document, as a secondary adhesive formation process, prepregs are laminated, placed in a vacuum bag state, and the binder resin in the prepregs is cured using an autoclave. discloses a method of assembling composite prepregs and applying pressure at high temperatures to cure a film adhesive.

JP 2020-1268 Publication

In recent years, with the increasing development of sandwich panels, it has been desired to further increase production efficiency.

As a result of intensive studies to improve the productivity of sandwich panels, the inventors of the present invention have developed a sheet-like core layer having a honeycomb structure by using both a sheet-like base material constituting a conventional prepreg and a resin sheet. We found a way to stack them all at once.

According to the present invention, the following sandwich panel manufacturing method is provided.

[1] A step of preparing a plurality of resin sheets (a), a sheet-like base material (b), and a sheet-like core layer (c) having a honeycomb structure, respectively;
On each surface of the core layer (c), one resin sheet (a1) of the plurality of resin sheets (a), the sheet-like base material (b), and one of the plurality of resin sheets (a) are disposed. a step of arranging the other resin sheets (a2) in order;
laminating the core layer (c), the resin sheet (a), and the sheet-like base material (b) all at once by heating and pressurizing treatment;
A method of manufacturing a sandwich panel, including:
[2] A method for manufacturing the sandwich panel according to [1], comprising:
A method for producing a sandwich panel, wherein in the step of laminating, the pressure in the heating and pressurizing treatment is 0.3 to 1.0 MPa.
[3] A method for manufacturing a sandwich panel according to [1] or [2], comprising:
A method for producing a sandwich panel, wherein in the step of laminating, the heating temperature in the heating and pressure treatment is 110 to 140°C.
[4] A method for manufacturing a sandwich panel according to any one of [1] to [3], comprising:
The method for manufacturing a sandwich panel, wherein the resin sheet (a) is formed from a resin composition containing one or two selected from epoxy resins and phenol resins.
[5] A method for manufacturing the sandwich panel according to [4], comprising:
A method for manufacturing a sandwich panel, wherein the phenolic resin includes one or two selected from resol-type phenolic resins and novolac-type phenolic resins.
[6] The method for manufacturing the sandwich panel according to [4] or [5], comprising:
The method for manufacturing a sandwich panel, wherein the resin composition contains polyvinyl butyral.
[7] The method for manufacturing a sandwich panel according to any one of [1] to [6],
The method for manufacturing a sandwich panel, wherein the resin sheet (a) is in a B-stage state.
[8] A method for manufacturing a sandwich panel according to any one of [1] to [7], comprising:
A method for manufacturing a sandwich panel, wherein the resin sheet (a) has a minimum melt viscosity of 5000 Pa·s or less.
[9] A method for manufacturing a sandwich panel according to any one of [1] to [8], comprising:
A method for manufacturing a sandwich panel, wherein the residual carbon percentage of the resin sheet (a) measured according to JIS K 6910 is 30% by mass or more.
[10] The method for manufacturing a sandwich panel according to any one of [1] to [9],
In the step of laminating,
A method for manufacturing a sandwich panel, wherein a part of the resin composition constituting the resin sheet (a) is impregnated into the sheet-like base material (b).
[11] The method for manufacturing a sandwich panel according to any one of [1] to [10],
The sheet-like base material (b) is one or more selected from aramid fibers, polyester fibers, polyphenylene sulfide fibers, carbon fibers, graphite fibers, glass fibers, and silicon carbide fibers. Production method.
[12] A method for manufacturing a sandwich panel according to any one of [1] to [11], comprising:
The method for manufacturing a sandwich panel, wherein the core layer (c) contains aramid fiber.
[13] The method for manufacturing a sandwich panel according to any one of [1] to [12],
A method for manufacturing a sandwich panel, wherein the sandwich panel is used for an aircraft panel.

According to the present invention, a technique that improves the production efficiency of sandwich panels can be provided.

FIG. 1 is a schematic cross-sectional view showing a sandwich panel according to the present embodiment. FIG. 3 is a process cross-sectional view showing an example of a method for manufacturing a sandwich panel according to the present embodiment.

In the present specification, the notation "a to b" in the explanation of numerical ranges represents a range from a to b, unless otherwise specified. For example, "1 to 5% by mass" means "1 to 5% by mass".
Embodiments of the present invention will be described below with reference to the drawings. Note that in all the drawings, similar components are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate.

<Sandwich panel>
As shown in FIG. 1, the sandwich panel 100 according to the present embodiment includes a core layer C having a honeycomb structure, a plurality of cured material layers A and a plurality of base material layers B provided on both sides of the core layer C, Equipped with Specifically, on both surfaces of the core layer C, a cured material layer A1, a base material layer B1, a cured material layer A2, a base material layer B2, and a cured material layer A3 are laminated in this order. The cured material layer A consists of a resin sheet a, and the base material layer B consists of a sheet-like base material b.
Each configuration will be explained below.

[Core layer]
The core layer C is a sheet-like plate member having a structure having high strength and light weight, and has a honeycomb structure. The honeycomb structure is a well-known structure, and is intended to be a structure in which a plurality of substantially regular hexagonal through holes penetrating from the upper surface to the lower surface are formed.

Examples of the base material constituting the honeycomb structure of the core layer C include aramid fibers, paper, balsa wood, plastic, aluminum, titanium, glass, alloys thereof, and the like formed into a honeycomb shape by a known method. Among these, from the viewpoint of heat resistance and weight reduction, it is preferable that the base material constituting the honeycomb structure of the core layer C contains aramid fibers.

The base material of the core layer C is preferably a woven fiber cloth. This improves the workability into a honeycomb structure, and also makes it possible to reduce the weight of the sandwich panel 100.
Further, when the core layer C is a fiber cloth, it is preferable to use a sheet-like member obtained by impregnating a core layer base material with a honeycomb structure with a binder resin, for example. This makes it possible to further increase strength and lightness. The binder resin is not particularly limited, and known binder resins can be used.
When the core layer C includes a fiber cloth on a woven fabric, the areas where the fibers cross are difficult to apply pressure during the manufacturing process, and voids tend to remain. However, in the sandwich panel 100 of this embodiment, the manufacturing process described below By this method, high adhesion can be obtained and the generation of voids can be suppressed.

The thickness of the core layer C is not particularly limited, but may be, for example, 1 mm or more and 50 mm or less, 3 mm or more and 40 mm or less, or 5 mm or more and 30 mm or less.

The size of each core cell in the core layer C is not particularly limited, but may be, for example, 1 mm or more and 10 mm or less on one side.

The area of the surface (upper surface, lower surface) of the core layer C is not limited, but for example, it may have the surface area of one sandwich panel 100, or it may have the total surface area of multiple sandwich panels. good. This makes it possible to separate one sandwich panel 100 into individual pieces and cut out a plurality of panels, thereby improving productivity. For example, the area of the surface (upper surface, lower surface) of the core layer C may be large, for example, 1 m ² or more.

Further, the core layer C may be subjected to various surface treatments internally and/or externally from the viewpoint of improving corrosion resistance and heat resistance.

[Cured material layer]
The cured material layer A of this embodiment is made of a cured material of the resin sheet a. The cured material layer A can become the outer surface of the sandwich panel 100 while being integrated with the core layer C and the sheet-like base material b and firmly adhering to the core layer C and the sheet-like base material b. In FIG. 1, three cured material layers A are used on one surface of the core layer C, but the number of cured material layers A is not limited to this number.

[Base material layer]
The base material layer B of this embodiment is obtained by integrating the sheet-like base material b with the resin sheet a. That is, the base material layer B of this embodiment is obtained by curing a part of the resin sheet a while being impregnated with the sheet-like base material b in the integration step.

As the sheet-like base material b, any material known as a prepreg base material can be used without particular limitation, and examples thereof include fiber base materials.
As the fiber base material, aramid fiber, polyester fiber, polyphenylene sulfide fiber, carbon fiber, graphite fiber, glass fiber, silicon carbide fiber, etc. can be used. From the viewpoint of high heat resistance, the fiber base material preferably contains glass fiber.

Moreover, by containing the fiber base material, the heat resistance of the sandwich panel 100 can be further improved. Furthermore, since the difference in linear expansion coefficient with the core layer C can be reduced, warping of the sandwich panel 100 can be suppressed.

[Application]
The sandwich panel 100 of the present embodiment has excellent lightness and mechanical strength, and can have various performances such as heat resistance and flame resistance in a well-balanced manner, so that it can be suitably used as an aircraft panel. For example, the sandwich panel 100 can be used for the interior of an aircraft, such as a toilet or a partition, or for equipment inside an aircraft, such as a wagon casing.

<Method for manufacturing sandwich panels>
The method for manufacturing a sandwich panel of this embodiment includes the following steps.
Preparation step: A step of preparing a plurality of resin sheets a, a sheet-like base material b, and a sheet-like core layer c having a honeycomb structure.
Arranging step: A step of sequentially arranging a plurality of resin sheets a and sheet-like base materials b on each surface of the core layer c.
Lamination step: A step in which the core layer c, the resin sheet a, and the sheet-like base material b are laminated all at once by heat and pressure treatment.
Each step will be explained below.

1. Preparation Step First, a resin sheet a, a sheet-like base material b, and a core layer c are each prepared.

The resin sheet a of this embodiment is preferably in a B-stage state. Thereby, it can be firmly integrated with the sheet-like base material b and the core layer c in the lamination process described later.
In addition, conventional prepregs in which a fiber base material is impregnated with a matrix resin are susceptible to shrinkage due to drying of the matrix resin when a unidirectional fiber base material is used, resulting in dimensional deformation in the width direction of the prepreg. There was a problem in that it was easy for this to occur. In contrast, in this embodiment, a predetermined resin sheet a is used and is integrated with the sheet-like base material b, so that the occurrence of dimensional deformation can be effectively suppressed.

B-stage state means that the reaction rate calculated from the measurement results of DSC (differential scanning calorimeter) for the resin constituting the resin sheet a is more than 0% and less than 60%, preferably more than 0.5%. It means 55% or less, more preferably 1% or more and 50% or less.

The thickness of the resin sheet a is preferably 5 μm or more and 200 μm or less. The resin sheet a can be in the form of a tape with a width of 10 mm or more and 100 mm or less, or a sheet with a width of 10 cm or more and 200 cm or less.

The minimum melt viscosity of the resin sheet a of the present embodiment is, for example, 5000 Pa·s or less, preferably 4000 Pa·s or less, and more preferably 3000 Pa·s or less. The minimum melt viscosity can be adjusted by adjusting the type of thermosetting resin used and the blending amount of polyvinyl butyral within the above-mentioned ranges. The lower limit of the lowest melt viscosity of the resin sheet a is, for example, 200 Pa·s or more. When the minimum melt viscosity is within the above range, it is possible to easily impregnate the inside of the fiber base material, and it is possible to achieve impregnating properties comparable to those obtained when using a liquid impregnating resin composition at room temperature.

Here, the minimum melt viscosity of the resin sheet a refers to the lowest viscosity that the resin composition exhibits when the resin sheet a is melted by heating. In detail, when the resin sheet a is heated at a constant temperature increase rate to melt the resin, the melt viscosity decreases as the temperature rises in the initial stage, and then, after a certain point, the melt viscosity increases as the temperature rises. . The minimum melt viscosity refers to the melt viscosity at such a minimum point. The minimum melt viscosity of the resin composition layer can be measured by a dynamic viscoelasticity method.

The resin sheet a of the present embodiment has a residual carbon percentage of 30% by mass or more, preferably 35% by mass or more, and more preferably 40% by mass or more. Thereby, the adhesion between the prepreg and the sandwich panel can be improved.
The upper limit of the residual carbon percentage of the resin sheet a is not particularly limited, but is, for example, 80% by mass or less.

The residual carbon percentage of the resin sheet a is the residual carbon percentage at a temperature of 800° C., which is measured according to JIS K6910.
The residual carbon content of the resin sheet a can be controlled by including a thermosetting resin and polyvinyl butyral, which will be described later, in specific amounts.

Moreover, it is preferable that the resin sheet a of this embodiment is formed using a resin composition containing a thermosetting resin. Thereby, a sandwich panel 100 with excellent heat resistance and strength can be obtained.

Examples of the thermosetting resin include one or two selected from epoxy resins and phenol resins.

(phenolic resin)
As the phenol resin, it is preferable to use a resol type phenol resin. A resol type phenol resin is a phenol resin obtained by reacting a phenol resin and an aldehyde in the presence of a basic catalyst.

Phenols used for the synthesis of resol type phenolic resins include phenol; cresols such as o-cresol, m-cresol, and p-cresol; o-ethylphenol, m-ethylphenol, p-ethylphenol, etc. Ethylphenols; butylphenols such as isopropylphenol, butylphenol, p-tert-butylphenol; alkylphenols such as p-tert-amylphenol, p-octylphenol, p-nonylphenol, p-cumylphenol; fluorophenol, chlorophenol , bromophenol, iodophenol, etc. Monohydric phenol substitutes such as p-phenylphenol, aminophenol, nitrophenol, dinitrophenol, trinitrophenol, etc. Monohydric phenols such as 1-naphthol, 2-naphthol, etc. and polyhydric phenols such as resorcinol, alkylresorcinol, pyrogallol, catechol, alkylcatechol, hydroquinone, alkylhydroquinone, phloroglucin, bisphenol A, bisphenol F, bisphenol S, and dihydroxynaphthalene. These can be used alone or in combination of two or more.

The aldehydes used for the synthesis of resol type phenolic resins include formaldehyde, paraformaldehyde, trioxane, acetaldehyde, propionaldehyde, polyoxymethylene, chloral, hexamethylenetetramine, furfural, glyoxal, n-butyraldehyde, and caproaldehyde. Examples include aldehyde, allylaldehyde, benzaldehyde, crotonaldehyde, acrolein, tetraoxymethylene, phenylacetaldehyde, o-tolualdehyde, and salicylaldehyde. These may be used alone or in combination of two or more. Further, precursors of these aldehydes or solutions of these aldehydes can also be used. Among these, from the viewpoint of manufacturing cost, it is preferable to use formaldehyde aqueous solution.

Basic catalysts used for the synthesis of resol type phenolic resins include, for example, alkali metal or alkaline earth metal hydroxides such as sodium hydroxide, potassium hydroxide, calcium hydroxide; sodium carbonate, calcium carbonate; carbonates such as; oxides such as lime; sulfites such as sodium sulfite; phosphates such as sodium phosphate; ammonia, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, hexamethylenetetramine, pyridine, etc. Examples include amines.

Water is generally used as a reaction solvent for the synthesis of resol type phenolic resins, but organic solvents may also be used. Specific examples of such organic solvents include alcohols, ketones, aromatics, and the like. Further, specific examples of alcohols include methanol, ethanol, propyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, glycerin, and the like. Specific examples of ketones include acetone, methyl ethyl ketone, and the like. Specific examples of aromatics include toluene, xylene, and the like.

(Epoxy resin)
As the epoxy resin, it is preferable to use an epoxy resin having two or more epoxy groups in one molecule, in other words, a bifunctional or more functional epoxy resin. By using such an epoxy resin, a highly heat resistant resin composition can be obtained.

Examples of epoxy resins having two or more functions include biphenylaralkyl epoxy resins, phenylaralkyl epoxy resins, biphenyl epoxy resins, naphthalene epoxy resins, phenolaralkyl epoxy resins, dicyclopentadiene epoxy resins, and silicone-modified epoxy resins. Rubber-modified epoxy resins such as ε-caprolactone-modified epoxy resins, bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol AD epoxy resins; phenol novolac epoxy resins such as о-cresol novolac types; Resin: Cycloaliphatic polyfunctional epoxy resin, glycidyl ester type polyfunctional epoxy resin, glycidylamine type polyfunctional epoxy resin, heterocyclic polyfunctional epoxy resin, bisphenol modified novolac type epoxy resin, polyfunctional modified novolac type epoxy resin, phenol Examples thereof include, but are not limited to, condensate type epoxy resins of aromatic aldehydes having a phenolic hydroxyl group, epoxy resins containing a fluorene skeleton, and epoxy resins having an adamantane skeleton introduced therein. These epoxy resins may be used alone or in combination of two or more.

In the resin sheet a of the present embodiment, the content of the thermosetting resin is, for example, 50% by mass or more and 95% by mass or less, preferably 60% by mass or more and 95% by mass, based on the entire resin sheet a. or less, and more preferably 70% by mass or more and 90% by mass or less. By controlling the content of the thermosetting resin to be less than or equal to the above upper limit value, the viscosity of the resulting resin sheet a when melted can be suppressed to a low level, and therefore the impregnating property with respect to the fiber base material can be improved.
On the other hand, by setting the content of the thermosetting resin to the above lower limit or more, the resulting resin sheet a has high heat resistance and durability.

When using a combination of a phenol resin and an epoxy resin as the thermosetting resin, the mixing ratio of these resins can be set to any value. Among these, the thermosetting resin is preferably a phenol resin. This suppresses shrinkage of the resin sheet a and provides good dimensional stability, resulting in improved adhesion.

Further, the resin composition constituting the resin sheet a of this embodiment may further contain polyvinyl butyral.

(Polyvinyl butyral)
The polyvinyl butyral used in the resin sheet a of this embodiment has the effect of solidifying the liquid thermosetting resin and functions as a sheet forming material. Further, by using polyvinyl butyral, flexibility can be imparted to the resulting resin sheet a. Therefore, the resin sheet a of this embodiment can be cut into desired dimensions or punched into a desired shape depending on the intended use. Polyvinyl butyral is a resin obtained by butyralizing polyvinyl alcohol with an aldehyde in the presence of an acid catalyst.

The weight average molecular weight of polyvinyl butyral is preferably 1.0×10 ⁴ to 1.0×10 ⁶ , more preferably 2.0×10 ⁴ to 5.0×10 ⁵ from the viewpoint of handleability etc. It is more preferably 3.0×10 ⁴ to 2.0×10 ⁵ . Note that the weight average molecular weight is measured by gel permeation chromatography (GPC) in terms of polystyrene.

The degree of polymerization of polyvinyl butyral is preferably in the range of 200 to 3,000. By setting the degree of polymerization to 200 or more, the mechanical strength of the obtained resin sheet a can be ensured, and by setting the degree of polymerization to 3000 or less, the obtained resin sheet a has appropriate flexibility. , it can be easily handled.

The content of polyvinyl butyral is, for example, 2% by mass or more and 50% by mass or less, preferably 5% by mass or more and 40% by mass or less, more preferably 10% by mass or more and 30% by mass or less, based on the entire resin sheet a. % by mass or less. By setting the content of polyvinyl butyral to the above lower limit value or more, the resulting resin sheet a has sufficient strength and flexibility to maintain the shape of the sheet, and can be placed on the fiber base material during use. Excellent handling properties.
On the other hand, by controlling the content of polyvinyl butyral to the above upper limit or less, the viscosity of the resulting resin sheet a when melted can be suppressed to a low level, and thus the impregnating property with respect to the fiber base material can be improved. Moreover, by controlling the content of polyvinyl butyral to be below the above upper limit, the resulting resin sheet a has high heat resistance and durability.

(Other ingredients)
The resin sheet a of this embodiment may further contain resorcinols. By including resorcinols, the curing speed of the resin sheet a can be improved. Specific examples of resorcins include resorcinol, 2-methylresorcinol, 5-methylresorcinol, methylresorcinols such as 2,5-dimethylresorcinol, 4-ethylresorcinol, 4-chlororesorcinol, 2-nitroresorcinol, 4-bromoresorcinol, etc. Examples include resorcinol and 4-n-hexylresorcinol. These may be used alone or in combination of two or more. Among these, it is preferable to use resorcinol or methylresorcinol from the viewpoint of manufacturing cost and sheet formability.

In addition to the above-mentioned components, the resin sheet a of the present embodiment includes elastomers such as nitrile butadiene rubber and styrene butadiene rubber, surfactants, flame retardants, antioxidants, colorants, and silane, within a range that does not impair the effects of the present invention. It may also contain additives such as coupling agents.

The resin sheet a can be produced as follows.
The resin sheet a of this embodiment is produced by applying a liquid or varnish-like resin composition obtained by dissolving the above components in an organic solvent onto a base sheet, etc., and removing the organic solvent by heat treatment to form a sheet. It is produced by molding and then heat-treating it to a B-stage state (semi-cured state).

Examples of organic solvents used in varnish-like resin compositions include alcohol-based organic solvents such as methanol, ethanol, isopropanol, and butanol, ketone-based organic solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, and aromatic carbonized solvents such as toluene and ethylbenzene. Mention may be made of hydrogen solvents and mixtures thereof. Among them, methanol is preferably used.

The varnish-like resin composition is prepared by kneading the above components in an organic solvent. The kneading can be carried out using an appropriate combination of a conventional stirrer, a three-roll mill, a ball mill, or other dispersing machine.

The process of forming a varnish-like resin composition into a sheet is performed by applying the varnish-like resin composition to a base sheet, heating and drying it to remove the organic solvent, and forming a resin composition layer. be exposed. The conditions for heat drying may be such that the organic solvent used is volatilized, and is carried out, for example, at a temperature of 50° C. to 150° C. for a time of 1 minute to 90 minutes.

The resin composition layer obtained as described above is brought into a semi-cured (B stage) state by further performing a heat treatment. The heat treatment for semi-curing can be performed at a temperature of 100 to 200° C. and for a period of 1 minute to 60 minutes.

The base sheet is not particularly limited as long as it can withstand the heat drying conditions described above, and examples include polyester films, polypropylene films, polyimide films, polyamide films, polysulfone films, and polyetherketone films. etc. are used. The surface of these base sheets may be treated with a mold release agent. The base sheet may be removed after the resin composition layer is formed. Moreover, the resin sheet a obtained in this way may be provided as a resin sheet a with a release film, in which a release film is provided on the surface opposite to the surface facing the base sheet. As the release film, the same material as the base sheet can be used.

The core layer c mentioned above can be used, but when the core layer c is a fiber cloth, for example, it is a sheet-like member made by impregnating a core layer base material with a honeycomb structure with a binder resin. It is preferable that In this case, the binder resin may be used before or after curing.

As the sheet-like base material b, those mentioned above can be used.

2. Arrangement Step Next, as shown in FIG. 2, a plurality of resin sheets a and sheet-like base materials b are arranged in order on each surface of the core layer c. Specifically, resin sheet a, sheet-like base material b1, resin sheet a2, sheet-like base material b2, and resin sheet a3 are laminated in this order on both surfaces of core layer c, respectively.
That is, while arranging the resin sheet a so as to be in contact with the surface of the core layer c, the resin sheet a and the sheet-like base material b1 are alternately laminated so that the uppermost surface becomes the resin sheet a. Thereby, the thermosetting resin and the like contained in the resin sheet a are impregnated into the core layer c and the sheet-like base material b, and interlayer adhesion can be dramatically improved.

3. Lamination step Subsequently, the core layer c, the resin sheet a, and the sheet-like base material b are laminated all at once by heating and pressurizing treatment.
As shown in FIG. 2, the resin sheets a3 disposed on the outermost surface are sandwiched from above and below, and are laminated together by heating and pressurizing. At this time, by placing a flat pressing plate 50 on the resin sheet a3 via a release film and heating and pressing it, it is possible to heat and press it more uniformly.

The heat treatment is preferably performed at a temperature of 110 to 140°C, more preferably 120 to 135°C.
The pressure treatment is preferably 0.3 to 1.0 MPa, more preferably 1.5 to 2.5 MPa.
By setting the temperature and pressure of the heating and pressurizing treatment to the above lower limit or higher, the core layer c, the resin sheet a, and the sheet-like base material b can be firmly integrated.
On the other hand, by controlling the temperature and pressure of the heating and pressurizing treatment to be below the above-mentioned upper limit values, it is possible to appropriately integrate the sheet-like base material b and the like while suppressing damage.
The heating and pressurizing treatment can be performed in the atmosphere without requiring gas replacement. Therefore, productivity can be improved.

As the pressing plate 50, a known one can be used, and examples thereof include metal plates such as a SUS plate, a tin plate, an aluminum plate, and a magnesium plate.
Further, the thickness of the pressing plate 50 is not particularly limited, but may be, for example, 0.5 mm or more and 10 mm or less, 0.8 mm or more and 5 mm or less, or 1.0 mm or more and 2.0 mm or less. By setting it within such a range, a balance between rigidity and thermal conductivity can be achieved.

As the release film of this embodiment, known ones can be used, and for example, polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), polytrimethylene terephthalate resin (PTT), polyhexamethylene terephthalate resin One or more selected from polyalkylene terephthalate resins such as resin (PHT), poly4-methyl-1-pentene resins (TPX), syndiotactic polystyrene resins (SPS), and polypropylene resins (PP). Preferably, it includes.
The thickness of the release film is not particularly limited, but is preferably 50 μm or more and 150 μm or less, more preferably 75 μm or more and 140 μm or less, and still more preferably 90 μm or more and 130 μm or less.

According to the method for manufacturing a sandwich panel of the present embodiment, by appropriately overlapping the resin sheet a and the sheet-like base material b, they can be laminated all at once, and production efficiency can be improved.

Although the embodiments of the present invention have been described above with reference to the drawings, these are merely examples of the present invention, and various configurations other than those described above may also be adopted.

In the above embodiment, an example using a release film has been described, but the release film may not be used.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the description of these Examples.

<Example 1>
(1) Preparation process The following resin sheet a, sheet-like base material b, and honeycomb core were prepared.
-Resin sheet a: Produced by the following procedure.
Phenol (100 parts by weight), 37% formalin aqueous solution (151 parts by weight) (F/P molar ratio = 1.7), and 5 parts by weight of triethylamine were added to a reaction apparatus equipped with a stirring device, a reflux condenser, and a thermometer. The mixture was reacted for 40 minutes under reflux conditions. Thereafter, while dehydrating under reduced pressure conditions of 91 kPa, when the temperature in the system reached 70°C, methanol (40 parts by weight) was added and the mixture was reacted at 80°C for 2 hours to obtain a resol type phenol resin.
To this, methanol (120 parts by weight) and polyvinyl butyral resin (calculated molecular weight 40,000, Sekisui Chemical Co., Ltd., S-LEC BM-1) (30 parts by weight) were added, dissolved and mixed to create a polyvinyl butyral modified phenolic resin varnish. I got it. After applying this varnish to a wet film thickness of 100 μm using a bar coater and drying it for 15 minutes in a dryer at 80°C, a phenolic resin containing 75% by mass of resol type phenolic resin and 20% by mass of polyvinyl butyral was applied. A composition sheet a1 was obtained.
The minimum melt viscosity of the resin sheet a1 was 800 Pa·s, and the residual carbon percentage was 43%.

In addition, the physical properties of the resin sheet a1 were measured by the following method. The results are shown in Table 1.
(Minimum melt viscosity)
The complex viscosity of the resin sheet a1 was measured using an ARE-G2 rheometer while increasing the temperature from 30° C. to 200° C. at 10° C./min, and the lowest viscosity was taken as the lowest melt viscosity.
(Remaining coal rate)
The residual carbon percentage of the resin sheet a1 was measured according to JIS K 6910.

・Sheet-like base material b: Rolled glass cloth (#7781, manufactured by HEXCEL)
・Honeycomb core: aramid fiber, thickness: 10mm, HRH-10-1/8-3.0 (manufactured by HEXCEL), area: 1m x 3m

(2) Preparation of sandwich panel Resin sheet a1, sheet-like base material b, and resin sheet a1 are arranged in this order on each surface of the honeycomb core, and SUS plates (thickness: 1.5 mm, Rz: 1 .0 μm) was pressed, and using a mechanical press, heat and pressure treatment was performed at 0.4 MPa, 127° C., and 60 minutes to laminate them all at once to obtain a honeycomb sandwich panel.

<Example 2>
Same as Example 1 except that a release film (polymethylpentene: TPX (registered trademark) film) was inserted between the resin sheet a1 placed in the outermost layer and the SUS plate, and the above heating and pressure treatment was performed. And got a sandwich panel.

<Comparative example 1>
A phenol resin (resol type phenol resin, "34370" manufactured by Durez) was blended and impregnated into glass fiber (#7781, manufactured by HEXCEL) to obtain a sheet-like prepreg (thickness: 250 μm). The prepreg was in a B-stage state.
Next, a sandwich panel was manufactured using the obtained sheet-like prepreg.
The above prepreg was placed on both sides of a honeycomb core (aramid fiber, thickness: 10 mm, HRH-10-1/8-3.0 (manufactured by HEXCEL), area: 1 m x 3 m) to obtain a laminate.
Subsequently, SUS plates (thickness: 1.5 mm, Rz: 1.0 μm) were pressed on both sides of the obtained laminate, and heated and pressed using a mechanical press at 0.3 MPa and 127° C. for 60 minutes. Got a sandwich panel.

(Evaluation results)
In the sandwich panels obtained in each example, the core layer and the prepreg layer were in good contact with each other, and the strength and appearance were also good.
Moreover, since the sandwich panel of the comparative example was made by impregnating glass fiber with phenol resin and then drying it to form a B stage, shrinkage due to drying was observed. Therefore, the adhesion of the sandwich panel was inferior to that of the example.

50 Pressing plate 100 Sandwich panel A Cured material layer A1 Cured material layer A2 Cured material layer A3 Cured material layer a Resin sheet a1 Resin sheet a2 Resin sheet a3 Resin sheet B Base material layer B1 Base material layer b Sheet-like base material b1 Sheet shaped base material c core layer

Claims (13)

A step of preparing a plurality of resin sheets (a), a sheet-like base material (b), and a sheet-like core layer (c) having a honeycomb structure, respectively;
On each surface of the core layer (c), one resin sheet (a1) of the plurality of resin sheets (a), the sheet-like base material (b), and one of the plurality of resin sheets (a) are disposed. a step of arranging the other resin sheets (a2) in order;
laminating the core layer (c), the resin sheet (a), and the sheet-like base material (b) all at once by heating and pressurizing treatment;
A method of manufacturing a sandwich panel, including: A method for manufacturing a sandwich panel according to claim 1, comprising:
A method for producing a sandwich panel, wherein in the step of laminating, the pressure in the heating and pressurizing treatment is 0.3 to 1.0 MPa. A method for manufacturing a sandwich panel according to claim 1 or 2, comprising:
A method for producing a sandwich panel, wherein in the step of laminating, the heating temperature in the heating and pressure treatment is 110 to 140°C. A method for manufacturing a sandwich panel according to claim 1 or 2, comprising:
The method for manufacturing a sandwich panel, wherein the resin sheet (a) is formed from a resin composition containing one or two selected from epoxy resins and phenol resins. A method for manufacturing a sandwich panel according to claim 4, comprising:
A method for manufacturing a sandwich panel, wherein the phenolic resin includes one or two selected from resol-type phenolic resins and novolac-type phenolic resins. A method for manufacturing a sandwich panel according to claim 4, comprising:
The method for manufacturing a sandwich panel, wherein the resin composition contains polyvinyl butyral. A method for manufacturing a sandwich panel according to claim 1 or 2, comprising:
The method for manufacturing a sandwich panel, wherein the resin sheet (a) is in a B-stage state. A method for manufacturing a sandwich panel according to claim 1 or 2, comprising:
A method for manufacturing a sandwich panel, wherein the resin sheet (a) has a minimum melt viscosity of 5000 Pa·s or less. A method for manufacturing a sandwich panel according to claim 1 or 2, comprising:
A method for manufacturing a sandwich panel, wherein the residual carbon percentage of the resin sheet (a) measured according to JIS K 6910 is 30% by mass or more. A method for manufacturing a sandwich panel according to claim 1 or 2, comprising:
In the step of laminating,
A method for manufacturing a sandwich panel, wherein a part of the resin composition constituting the resin sheet (a) is impregnated into the sheet-like base material (b). A method for manufacturing a sandwich panel according to claim 1 or 2, comprising:
The sheet-like base material (b) is one or more selected from aramid fibers, polyester fibers, polyphenylene sulfide fibers, carbon fibers, graphite fibers, glass fibers, and silicon carbide fibers. Production method. A method for manufacturing a sandwich panel according to claim 1 or 2, comprising:
The method for manufacturing a sandwich panel, wherein the core layer (c) contains aramid fiber. A method for manufacturing a sandwich panel according to claim 1 or 2, comprising:
A method for manufacturing a sandwich panel, wherein the sandwich panel is used for an aircraft panel.

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