JP3294481B2 - Manufacturing method of carbon honeycomb structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a carbon honeycomb structure.

2. Description of the Related Art A honeycomb structure is composed of a planar assembly of hollow columnar cells, and a heat-resistant honeycomb structure is used for a sandwich panel in a high-temperature portion such as around an engine for an aircraft or the pressure of an aircraft / space equipment. Structural members to be heated,
It is used in others and has heat resistance over time in an environment and normal temperature of about 260 ° C. Conventionally, aluminum foil, kraft paper, and the like have been used as a base material of a honeycomb structure that is lightweight, has high mechanical strength, and has excellent mechanical strength. Examples of materials having heat resistance include stainless steel and titanium. A metal foil made of honeycomb and brazed, glass fiber, carbon fiber, etc. as a base material, to which heat-resistant resin such as resol phenol resin is adhered, heat-resistant aromatic polyamide synthetic paper And a heat-resistant resin such as a resole phenol resin adhered thereto.

However, the following problems have been pointed out in the conventional heat-resistant honeycomb structure. A metal foil made of stainless steel, titanium or the like, which has been formed into a honeycomb shape and brazed, can be used at an extremely high ordinary temperature of about 1000 ° C., but the manufacturing method is complicated, mass production is difficult, and very expensive. is there. Glass fiber, carbon fiber, etc. as the base material,
A resin to which a heat-resistant resin such as resol phenol resin is attached can be used at a normal temperature of about 120 ° C.
Since prepreg is used as a material, the bonding process between the substrates is complicated, mass production is difficult, and it is very expensive. In addition, the use of heat-resistant aromatic polyamide synthetic paper as a base material, which is impregnated with a heat-resistant resin such as resol phenol resin, is reduced in strength due to moisture absorption under high humidity conditions. You. In addition, carbon fiber base cloth impregnated and cured with polyimide resin generates gas when the resin is cured, generates voids, cannot increase the concentration of the impregnating liquid, increases the number of times of impregnation, and causes burrs when cutting the honeycomb structure. When the impregnation is repeatedly performed, the impregnating liquid from the second time onward is easily repelled, so that the effect of improving the strength by the impregnation is low, and the material cost is high.

[0003]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to reduce the strength under a high-temperature environment of about 120 ° C. and under high humidity conditions, to be able to be used regularly, to be mass-produced, and to be inexpensive. An object of the present invention is to provide a method for manufacturing a honeycomb structure.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a corrugated sheet obtained by corrugating a carbon fiber base fabric impregnated with an epoxy resin prepolymer and then curing the same, and curing a carbon fiber base fabric impregnated with an epoxy resin prepolymer. A large number of the flat sheet sheets were alternately laminated via a strip adhesive, and the laminate was impregnated with a phenol resin prepolymer. After the solvent was evaporated, the phenol resin prepolymer was cured, and the impregnation was performed. -A method for producing a carbon honeycomb structure by a so-called corrugation method, wherein a predetermined amount of a phenol resin is impregnated by repeating an evaporation-curing step and then cut into a predetermined thickness. Further, the present invention provides a corrugated sheet of carbon fiber base cloth impregnated with an epoxy resin prepolymer, and then sets and hardens the corrugated sheet with a laminar adhesive. After the body is impregnated with the phenolic resin prepolymer and the solvent is evaporated, the phenolic resin prepolymer is cured, and this impregnation-evaporation-curing step is repeated to impregnate the phenolic resin in a predetermined amount, and then cut into a predetermined thickness. This is a second method for producing a carbon honeycomb structure, characterized in that:

[0005] The present invention also relates to a method of coating a carbon fiber base fabric impregnated with an epoxy resin prepolymer, applying a strip adhesive, laminating a large number of sheets, curing the adhesive, and then expanding and heating the laminate. The epoxy resin prepolymer is cured to form a honeycomb structure, the phenol resin prepolymer is further impregnated, the solvent is evaporated, the phenol resin prepolymer is cured, and this impregnation-evaporation-curing step is repeated. This is a method for producing a carbon honeycomb structure by a so-called stretching method, which comprises impregnating a fixed amount of a phenol resin and then cutting the same to a predetermined thickness.

Hereinafter, the present invention will be described in detail. The carbon fiber base fabric used in the present invention is, for example, a woven fabric, a knitted fabric, a nonwoven fabric, or the like made of polyacrylonitrile-based carbon fiber, and includes, for example, a 1K plain weave carbon fiber woven fabric. The thickness is usually about 0.1 to 0.5 mm and the width is 250 to 35
About 0 mm is appropriate. This carbon fiber base fabric is impregnated with an epoxy resin prepolymer. Impregnation amount is 30 to 4 in solid content
0% by weight is suitable. Epoxy resin prepolymer is
For example, those represented by the following formula (1) are preferable.

[0007]

Embedded image

In the formula, n is a number from 1 to 2.

First, the first production method of the corrugation method will be described. The carbon fiber base fabric impregnated with the epoxy resin prepolymer is corrugated by a conventional method using a corrugated roll. The height and width of the corrugated wave are preferably 2-3 mm, and the pitch of the wave is suitably 8-9 mm. The base fabric thus formed is cured at, for example, about 170 to 220 ° C. for about 60 to 120 minutes to obtain a corrugated sheet. Separately, a flat sheet is prepared by curing a carbon fiber base cloth impregnated with an epoxy resin prepolymer. Next, a line adhesive is applied to the wave peak portion of the corrugated sheet, about 120 to 200 g / m ^2, and a flat sheet (not corrugated) are alternately formed.
A large number of sheets (for example, about 150 to 400 sheets each) are stacked, and a surface pressure of about 0.5 to ² kg / cm ² is applied.
Heat-treat at about 0 to 280 ° C. for about 1 to 3 hours to cure. N-methyl-2-pyrrolidone, dimethylformamide and the like are preferred as the solvent for the striation adhesive.

Next, the second production method of the corrugation method will be described. The carbon fiber base fabric impregnated with the epoxy resin prepolymer is corrugated by a conventional method using a corrugated roll. The height and width of the corrugated wave are preferably 2-3 mm, and the pitch of the wave is suitably 8-9 mm. The base fabric thus formed is cured at, for example, about 170 to 220 ° C. for about 60 to 120 minutes to obtain a corrugated sheet. Next, a large number of sheets (for example, about 150 to 400 sheets) obtained by applying about 120 to 200 g / m ² of the line adhesive to the crests of the corrugated sheet are superimposed on about 0.5 to ² kg / cm ² . Heat treatment at about 220 to 280 ° C. for about 1 to 3 hours while applying surface pressure to cure. N-Methyl-2-
Pyrrolidone, dimethylformamide and the like are preferred.

The cured product is impregnated with a phenol resin prepolymer solution, the solvent is evaporated, and the phenol resin prepolymer is cured. As the solvent for the phenol resin prepolymer, acetone, methyl ethyl ketone and the like are preferable. In this impregnation / evaporation / curing treatment, the impregnation amount of the phenolic resin prepolymer is 30 to 120 as a solid content.
repeated until approximately kg / m ^3. Solvent evaporation 60-1
About 10 to 60 minutes at 00 ° C.
About 30 to 60 minutes at 0 to 200 ° C. is sufficient. Because the impregnating liquid of the above phenolic resin prepolymer has low viscosity,
The concentration at the time of impregnation can be relatively high, and the number of times of impregnation, evaporation and curing of the conventionally used prepolymer (15 to
20 times) can be reduced to about 5 to 10 times. Then, the honeycomb structure is cut into a desired thickness, for example, 0.5 to 3 inches (12 to 38 mm) to obtain the honeycomb structure of the present invention.

Next, the expansion method will be described. A carbon fiber base cloth impregnated with an epoxy resin prepolymer is coated with a strip adhesive, for example, a cold-curable epoxy resin or a cold-curable resorcinol / formaldehyde resin-based adhesive, and then a large number (for example, 300 to 400 sheets). After laminating and curing the adhesive, and then expanding and heating this laminate to cure the epoxy resin prepolymer to form a honeycomb structure, impregnating with the phenolic resin prepolymer and evaporating the solvent, The phenolic resin prepolymer is cured, and the impregnation-evaporation-curing step is repeated to impregnate a predetermined amount of the phenolic resin, and then cut to a predetermined thickness to produce a carbon honeycomb structure.

[0013]

According to the present invention, a carbon fiber base cloth impregnated with a polyimide prepolymer is used because a carbon fiber base cloth impregnated with an epoxy resin prepolymer is used and a phenol resin prepolymer is used as an impregnating component. Although the heat resistance is slightly inferior to that obtained by the heat treatment, the material cost is low, the strength, particularly the strength under a high humidity condition, is small, and the thermoformability is excellent. Further, the concentration of the impregnating liquid can be increased, and as a result, the number of times of impregnation can be greatly reduced. Further, there is no phenomenon that the impregnating liquid is repelled even if the impregnation is repeated. Furthermore, when cutting after the final curing treatment, the occurrence of burrs is small. Although the honeycomb structure of the present invention cannot be bent at all at room temperature, it is about 3 times.
By heating to 20 ° C., the resin is softened and a curved surface can be formed.

[0014]

Example 1 A carbon fiber woven fabric having a width of 325 mm and a length of 1700 mm (plain woven 1K, density (number of shots):
m, thickness 0.16 mm) with 35% by weight of an epoxy resin prepolymer (liquid) represented by the formula (1). The carbon fiber base fabric impregnated with the epoxy resin prepolymer was corrugated by a conventional method using a corrugated roll. Wave height and width are 3mm, wave pitch is 9mm
And The sheet thus formed was cured at 200 ° C. for 60 minutes to prepare a corrugated sheet. Separately, the same carbon fiber base fabric (width 325 mm, length 1240 mm) was impregnated with the same epoxy resin prepolymer in the same manner, and then cured similarly to form a flat sheet. Next, a polyimide prepolymer-based line adhesive was applied to the corrugated portion of the corrugated sheet,
g / m ² coated and flat sheet (not corrugated) were alternately superposed on 350 sheets each and heat-treated at 250 ° C. for 2 hours while applying a surface pressure of 1 kg / cm ^2. Cured.

A phenol resin prepolymer (40% by weight acetone solution) (37 cps: 25 ° C.)
) Was impregnated at room temperature, heated at 90 ° C. for 30 minutes to evaporate the solvent, and heat-cured at 180 ° C. for 45 minutes. This impregnation / evaporation / curing step was repeated eight times, and the prepolymer was impregnated with 70 kg / m ³ of solid content. As the phenol resin prepolymer, "Phenolite 5900" (trade name, manufactured by Dainippon Ink and Chemicals, Inc.) was used.
This was cut to a thickness of 12.7 mm to obtain a honeycomb structure of the present invention.

[0016]

Example 2 Carbon fiber woven fabric having a width of 325 mm and a length of 1700 mm (plain weave 1K, density (number of shots): 906
m, thickness 0.16 mm) was impregnated with an epoxy resin prepolymer (liquid) represented by the formula (1) so as to be 35% by weight. The carbon fiber base fabric impregnated with the epoxy resin prepolymer (liquid) was corrugated by a conventional method using a corrugated roll. The height and width of the wave were 3 mm, and the pitch of the wave was 9 mm. The sheet formed in this way is heated at 200 ° C. for 6 hours.
After curing for 0 minutes, a corrugated sheet was prepared. Next, 200 g / m ² of a polyimide prepolymer-based adhesive is applied to the corrugated portion of the corrugated sheet, and the corrugated portion of the corrugated sheet adjacent to the corrugated sheet is shifted by a half pitch for each sheet. 350 sheets are overlapped so as to be joined to the valley, and 1kg /
The composition was cured by heat treatment at 250 ° C. for 2 hours while applying a surface pressure of ² cm ² .

A phenol resin prepolymer (40% by weight acetone solution) (37 cps: 25 ° C.)
) Was impregnated at room temperature, heated at 90 ° C. for 30 minutes to evaporate the solvent, and heat-cured at 180 ° C. for 45 minutes. This impregnation / evaporation / curing step was repeated eight times, and the prepolymer was impregnated with 70 kg / m ³ of solid content. As the phenol resin prepolymer, "Phenolite 5900" (trade name, manufactured by Dainippon Ink and Chemicals, Inc.) was used.
This was cut to a thickness of 12.7 mm to obtain a honeycomb structure of the present invention.

[0018]

Comparative Example In Example 1, instead of the components used for the strip adhesive and the impregnating liquid (phenol resin prepolymer; trade name "Phenolite 5900" manufactured by Dainippon Ink and Chemicals, Inc.), the following formula ( A honeycomb structure was prepared in the same manner except that a polyimide prepolymer obtained from the aromatic carboxylic anhydride represented by 2) and the diamine represented by the following formula (3) was used.

[0019]

Embedded image

The honeycomb structures of Example 1 and Comparative Example were as follows:
Compared with conventional aluminum and Nomex (aromatic polyamide blend paper) honeycomb structures (1/8 inch regular hexagonal honeycomb structure), corrosion resistance (weight change in salt spray test), compressive strength and bending strength (60
(Strength after standing at 85 ° C. and 85% RH for 30 days). Further, the honeycomb structure of Example 1 is superior in the compressive strength and the bending strength as compared with those of the comparative example. The results are summarized in the following table.

[0021]

[Table 1] Corrosion resistance Compressive strength Bending strength Example 1 A A A Comparative example A B B Made of aluminum C B B Made of Nomex B C C A: Excellent B: Normal C: Poor

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-173772 (JP, A) JP-A-5-208465 (JP, A) JP-A-5-124138 (JP, A) JP-A-4- 294136 (JP, A) JP-A-5-50538 (JP, A) JP-A-63-260432 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 1/00-35 / 00

Claims (12)

(57) [Claims] 1. A corrugated sheet obtained by corrugating a carbon fiber base cloth impregnated with an epoxy resin prepolymer and then hardening, and a flat sheet obtained by hardening a carbon fiber base cloth impregnated with an epoxy resin prepolymer. A large number of sheets are alternately laminated via a line adhesive, the adhesive is cured, the laminate is impregnated with a phenol resin prepolymer, and after the solvent is evaporated, the phenol resin prepolymer is cured and the impregnation is performed. A method for producing a carbon honeycomb structure, wherein a predetermined amount of a phenol resin is impregnated by repeating an evaporation-curing step, and then cut into a predetermined thickness. 2. The method according to claim 1, wherein the carbon fiber base fabric is a polyacrylonitrile-based carbon fiber base fabric. 3. The method according to claim 1, wherein the carbon fiber base fabric is a woven fabric. 4. The epoxy resin prepolymer of the following formula (1)
A repeating unit represented by the formula (1) or (2) or (3).
Production method as described. Embedded image In the formula, n is a number of 1-2. 5. A corrugated sheet obtained by corrugating a carbon fiber base cloth impregnated with an epoxy resin prepolymer, and then curing the laminated sheet via a strip adhesive, curing the adhesive, and further curing the laminate. Impregnated with a phenolic resin prepolymer, evaporating the solvent, curing the phenolic resin prepolymer, repeating this impregnation-evaporation-curing step to impregnate a predetermined amount of phenolic resin, and then cutting to a predetermined thickness. A method for producing a carbon honeycomb structure, comprising: 6. The method according to claim 5, wherein the carbon fiber base fabric is a polyacrylonitrile-based carbon fiber base fabric. 7. The method according to claim 5, wherein the carbon fiber base fabric is a woven fabric. 8. The method according to claim 5, wherein the epoxy resin prepolymer has a repeating unit represented by the formula (1). 9. A carbon fiber base cloth impregnated with an epoxy resin prepolymer is coated with a line adhesive, and then a large number of sheets are laminated.
The adhesive is cured, and then the laminate is stretched and heated to cure the epoxy resin prepolymer to form a honeycomb structure. Further, the phenol resin prepolymer is impregnated, and the solvent is evaporated. A method for producing a carbon honeycomb structure, comprising curing a polymer, repeating the impregnation-evaporation-curing step to impregnate a predetermined amount of a phenol resin, and then cutting the polymer to a predetermined thickness. 10. The method according to claim 9, wherein the carbon fiber base fabric is a polyacrylonitrile-based carbon fiber base fabric. 11. The method according to claim 9, wherein the carbon fiber base fabric is a woven fabric. 12. An epoxy resin prepolymer having a repeating unit represented by the formula (1).
1. The production method according to 1.