JPH0362734B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a flame-retardant phenolic resin prepreg with excellent adhesiveness and processability, and more specifically, it has low calorific value and smoke emission upon combustion, and is suitable for use in aircraft, vehicles, ships, and buildings. The present invention relates to a flame-retardant phenolic resin prepreg suitable for manufacturing structural materials and interior materials such as. (Conventional technology) In recent years, honeycomb sandwich panels have become lightweight,
Because of its excellent strength and rigidity, it is often used in structural materials such as aircraft, sporting goods, ships, and buildings. A honeycomb sandwich panel is a molded body made by layering surface materials on both sides of a honeycomb and applying heat and pressure.Generally, the honeycomb core is made of aluminum or Nomex (manufactured by Nomex DuPont, aromatic polyamide nonwoven fabric). However, aluminum and fiber-reinforced plastic are used as surface materials. In particular, aircraft interior panels often use Nomex honeycomb and plastic surface materials reinforced with glass fiber, Kepler fiber, and carbon fiber. Furthermore, in order to ensure the safety of passengers in the event of a fire, interior materials for modern aircraft are required to be flame retardant, and have low smoke and heat generation properties when burned. Conventionally, fabrics of these reinforcing materials were impregnated with epoxy resin or phenolic resin as a matrix resin to form a prepreg, and the honeycomb was pressurized and heated to form a honeycomb sandwich panel. However, although epoxy resin has good adhesive properties, it is undesirable because it generates a large amount of heat and smoke when burned, and phenolic resin is flame retardant and has low smoke emission, but it cannot be used as a surface material for honeycomb panels. In some cases, the disadvantage was that the adhesive peel strength was low. In addition, ordinary phenolic resins, that is, resol resins, contain a large amount of free phenol, which is an unreacted monomer, and have a low molecular weight. There are many problems in terms of work, such as the need for concentrated varnish. (Problems to be Solved by the Invention) In view of the above-mentioned problems, the present inventors have conducted intensive research and have discovered a product that is a mixture of thermosetting phenolic resin, epoxy resin, acrylonitrile-butadiene rubber, and alumina hydrate. , has excellent adhesion and flame retardancy, especially low heat generation during combustion,
They discovered that it has low smoke generation properties and completed the present invention. An object of the present invention is to provide a flame-retardant phenolic resin prepreg for manufacturing honeycomb sandwich panels, which has a high adhesive peel strength, produces low heat generation and smoke when burned. Further objects and advantages will become apparent from the description below. (Means for Solving the Problems) The above object of the present invention is to provide thermosetting phenolic resin, epoxy resin,
This is achieved by a flame-retardant phenolic resin prepreg characterized by using acrylonitrile-butadiene rubber and a matrix resin whose main components are alumina hydrate. The thermosetting phenolic resin used in the present invention is produced from formalin and phenols, and includes, for example, resol resin and novolac resin, and is further disclosed in Japanese Patent Publication No. 62-30210 and Japanese Patent Publication No. 62-30211. Powdered resins (hereinafter referred to as "granular phenolic resins") proposed in the above publications are preferably used, but the resin is not limited thereto. "Granular phenolic resin" has a larger molecular weight and less free phenol than resol resins and novolac resins, so there is almost no phenol odor during operation, it is easy to obtain high viscosity varnish, and it has excellent stability and storage stability. It is extremely suitable for use because it is less sticky and the sheet forming operation is easy. In the present invention, epoxy resins include, for example, bisphenol A type, cresol volak type, phenol volak type, polyglycol type, cycloaliphatic type, long chain aliphatic type, brominated bisphenol type, hydantoin type, and isocyanate type. Examples include, but are not limited to, the following. Preferably, bisphenol A type, cresol novolak type, phenol novolak type, and polyglycol type are used, and polyglycol type is particularly preferred from the viewpoint of increasing the flexibility of the prepreg. Further, the epoxy resin may be either liquid or solid as long as it becomes a solution as a composition. In the present invention, acrylonitrile-butadiene rubber (hereinafter referred to as NBR) refers to a copolymer rubber whose main components are acrylonitrile and butadiene, but also includes terpolymer rubber whose main components are acrylic acid and methacrylic acid. . In particular, terpolymer copolymers containing carboxylic components are preferred, as they provide strong adhesive strength. The alumina hydrate of the present invention has the chemical formula Al ₂ O ₃ .
It is a fine powder represented by nH ₂ O or Al(OH) ₃ , such as gypsite, bayerite, etc. Among them, gypsite, which is a trihydrate powder crystal, is preferably used. Further, from the viewpoint of dispersibility and flame retardancy, the particle size is preferably 50 μm or less, more preferably 20 μm or less, and even more preferably 5 μm or less. If the particle size is larger than 50μ, when used as the matrix resin of the present invention, the dispersion of alumina hydrate tends to be uneven, and impregnation spots may occur during the process of impregnating the base material with the resulting matrix resin. There is a tendency for insufficient concentration to occur. In the matrix resin of the present invention, alumina hydrate has good dispersibility and effectively reduces the amount of heat generated during combustion. In the matrix resin of the present invention, the greater the blending ratio of phenolic resin, the better the smoke generation properties will be, but the adhesiveness will tend to be worse. Epoxy resin + NBR component) = 50/50 ~
The ratio is 95/5, more preferably 70/30 to 90/10. In addition, the composition ratio of epoxy resin and NBR component is
The weight ratio is preferably epoxy resin/NBR component = 50/50 to 90/10, more preferably 60/40 to
It's 80/20. If the proportion of the NBR component is too small, the adhesion tends to deteriorate, and if the proportion of the NBR component is too large, the smoke generation properties will deteriorate, and in the process of impregnating the composition into glass cloth etc., impregnation spots will increase. It tends to be difficult to obtain uniform prepreg. In the matrix resin of the present invention, flame retardancy improves as the amount of alumina hydrate increases,
In addition, the amount of heat generated and the amount of smoke generated during combustion are reduced, but if the amount is too large, the viscosity of the solution increases and impregnation into the base material becomes poor. In the present invention, the alumina hydrate is preferably used in an amount of 5 to 100% by weight, more preferably 10 to 70% by weight, based on the resin component. Examples of the base material used in the present invention include, but are not limited to, various glass fibers, carbon fibers, aramid fibers, graphite fibers, silicon carbide fibers, and the like. Further, the form of the base material is not limited to the fiber itself, but may be in the form of a fibrous structure such as a satin weave, plain weave, twill weave fabric, or unidirectional weave, for example. These base materials can be freely selected depending on the required strength, rigidity, weight, and economical efficiency. Next, a general method for producing the flame-retardant phenolic resin prepreg of the present invention will be explained. First, the thermosetting phenolic resin, epoxy resin, and NBR are dissolved in an organic solvent to form a solution. Examples of organic solvents include methanol, propanol, butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, ethyl carbitol, butyl carbitol,
Ethyl acetate, ethyl carbitol acetate, butyl carbitol acetate, DMF,
DMSO or a mixed solvent of two or more thereof is suitable, and acetone and methyl ethyl ketone are particularly suitable in terms of ease of handling and solubility. Next, the matrix resin of the present invention can be produced by adding the alumina hydrate to the solution while stirring. The matrix resin of the present invention may contain other additives, colorants, stabilizers, etc. in addition to the above-mentioned essential components. Next, the matrix resin for impregnation obtained by the above method is impregnated into the base material by, for example, dipping, spraying, or a hot melt method.
The flame-retardant phenolic resin prepreg of the present invention can be obtained by drying if necessary. Furthermore, a honeycomb sandwich panel can be obtained by laminating the prepreg of the present invention on both sides of a honeycomb core made of Nomex paper, for example, and then pressurizing and heat-forming it in a heat press machine, autoclave, etc. . The present invention will be explained in detail with reference to Examples below. Before that, methods for measuring various characteristic values and methods for producing "granular phenolic resin" in this specification will be described. (1) Adhesive peel strength (drum peel strength): Measured on honeycomb sandwich panels by drum peel method (MIL-STD-401B method). (2) Smoke generation property (NBS Ds value): Measured on honeycomb sandwich panels by NBS method (ASTM-E-662, non-flame method). When the light transmittance inside the chamber is T%, Ds = 131log100/T (3) Calorific value: Take the matrix resin component in the prepreg in an aluminum foil cup and heat it in a hot oven for 150%.
After heating and curing at ℃×1 hour, it was cooled. The cooled material was crushed and crushed with TG-DTA (manufactured by Rigaku Denki) for 10 minutes.
The temperature was raised to 700°C at a rate of °C/min, and the exothermic peak area was determined. (4) Volatile content: Ratio between the weight difference before and after heating when prepreg is heated at 150℃ for 15 minutes and the weight before heating. Moreover, the "granular phenolic resin" of this example was manufactured as follows. "Method for producing granular phenolic resin" 10 kg of a mixed aqueous solution containing 18% by weight hydrochloric acid and 7% by weight formaldehyde was placed in 10 separable flasks. Although the room temperature was 20°C, the temperature of the mixed aqueous solution was maintained at 18°C by temperature adjustment. While stirring this, a diluted solution prepared by diluting 315 g of phenol with 35 g of water was added at once. Stirring was stopped 45 seconds after the diluent was added and the mixture stood still, but the mixture suddenly became cloudy 68 seconds after stopping stirring, and a milky white product was observed, and this milky white product gradually turned pink. did. The liquid temperature gradually rose from the above 18°C, reached a peak of 32°C 15 minutes after adding the diluent, and then dropped again. After adding the diluted solution and leaving it for 60 minutes, the mixed aqueous solution of the contents was stirred again for 5 minutes. The contents separated into solid and liquid using a glass filter were washed with water, treated in a 0.5% by weight ammonia aqueous solution at a temperature of 30 to 32°C for 2 hours, washed with water, then dehydrated, and dried at a temperature of 35°C for 8 hours. did. The moisture content after drying is 0.3% by weight, and the yield is
It was 377g. When observed under an optical microscope, most of the above contents were found to be spherical or granular fine powder with a particle size of 1 to 15 microns. Furthermore, the weight average molecular weight in terms of polystyrene by GPO method was 3200, and the free phenol content was 32 ppm as measured by HPLC method. Example 1 "Granular phenolic resin", polyglycol epoxy resin DER736 [manufactured by Dow Chemical, epoxy equivalent: 193, n=3] and acrylonitrile-butadiene rubber (NBR) Nipole 1072J [manufactured by Nippon Zeon, acrylonitrile value 27%, carboxyl group] A varnish was obtained by dissolving the composition (weight ratio) of phenolic resin/epoxy resin/NBR in methyl ethyl ketone using a homodisper at room temperature. The solid content concentration of this varnish was 49.1%. Next, 50% by weight of alumina hydrate Hygilite H-43M (manufactured by Showa Denko, average particle size 0.6 μm) was added to the varnish resin component to prepare a matrix resin. This matrix resin is applied to glass cloth KS181/
After impregnating with A-1100 [manufactured by Kanebo], it is dried in a dryer.
Dry at 70℃ for 9 minutes, resin adhesion amount is 40%, volatile content
A 4.5% prepreg was made. The dispersion state of Hygilite H-43M in the matrix resin was good, and there were no impregnation spots in the obtained prepreg. Furthermore, there was no phenol odor characteristic of phenolic resins, and workability was good. Next, the obtained prepreg was pasted on both sides of Nomex honeycomb SAH1/8-3.0 [manufactured by Showa Aircraft Industry Co., Ltd.], and the temperature and pressure were 150°C and
A honeycomb sandwich panel was produced by molding at 3.5 kg/cm ² for 1 hour. Adhesive peel strength and heat generation property during combustion of the obtained prepreg and honeycomb sandwich panels,
The smoke generation properties were as shown in Table 1. As shown in Table 1, the amount of heat generated by combustion was small, the amount of smoke emitted was also small, and the adhesive peel strength was high, indicating good characteristic effects. Examples 2 to 4 The blending amount of alumina hydrate Hygilite H-43M in Example 1 was not 50% by weight based on the resin component of the varnish, but was adjusted in the range of 10 to 70% by weight.
The ingredients were mixed as shown in the table. Other methods are Example 1
In the same manner as above, prepreg and honeycomb sandwich panels were respectively produced. Table 1 shows the amount of heat generated during combustion, amount of smoke, and adhesive peel strength of the obtained prepreg and honeycomb sandwich panels. As the amount of alumina hydrate increased, the amount of heat generation and smoke generation tended to decrease, but the adhesive peel strength also tended to decrease. Comparative Example 1 A prepreg and a honeycomb sandwich panel were produced in the same manner as in Example 1, except that alumina hydrate was not blended. Various properties of the obtained prepreg and honeycomb sandwich panels are shown in Table 1. As shown in Table 1, the adhesive peel strength was large and good, but
The amount of heat generated was large, which was not desirable. Comparative Example 2 A prepreg and a honeycomb sandwich panel were produced in the same manner as in Example 1 except that only "granular phenolic resin" was used as the matrix resin component. Various properties of the obtained prepreg and honeycomb sandwich panels are shown in Table 1. As shown in Table 1, the adhesive peel strength was low and the calorific value was high, which was not preferable.

【table】

[Table] Examples 5 to 7 Matrix resins and prepregs were prepared in the same manner as in Example 1, except that alumina hydrates having the average particle diameters shown in Table 2 were used.
The smaller the average particle size, the better the dispersion state of alumina hydrate in the matrix resin, and the particles of Hygilite H-10C with an average particle size of 100μ tend to be unevenly distributed due to sedimentation. The appearance of the prepreg was unfavorable as the surface was rough and defective. Subsequently, a honeycomb sandwich panel was produced in the same manner as in Example 1. Table 2 shows the results of various characteristics. As shown in Table 2, the smaller the average particle diameter, the higher the adhesive peel strength, and the smaller the amount of heat generated and smoke emitted.

[Table] Example 8 A prepreg and a honeycomb sandwich panel were prepared in the same manner as in Example 1, except that the resol resin Shonol CKS343 (manufactured by Showa Kobunshi) was used in place of the "granular phenolic resin". Table 3 shows various properties of the obtained prepreg and honeycomb sandwich panels. As shown in Table 3, even when resol resin was used as the phenolic resin, the adhesive peel strength, heat generation property, and smoke generation property were good as in the case of granular phenol.

[Table] Example 9 Prepreg, I created a honeycomb sandwich panel. Table 4 shows various properties of the obtained prepreg and honeycomb sandwich panels. Various properties were good. Comparative Example 3 A prepreg and honeycomb sandwich panel was produced in the same manner as in Example 1, except that NBR was not used as the matrix resin component. Table 4 shows various properties of the obtained prepreg and honeycomb sandwich panels. If NBR was not used in the matrix resin component, the adhesive peel strength would be low, which was not desirable.

[Table] Examples 10 to 13 Prepreg and honeycomb sandwich panels were prepared in the same manner as in Example 1, except that the epoxy resin shown in Table 5 was used as the epoxy resin in the matrix resin component. Table 5 shows the combustion heat generation properties, smoke generation properties, and adhesive peel strengths of the obtained prepreg and honeycomb sandwich panels. All epoxy resins had good properties.

[Table] Examples 14 to 19 The same polyglycol type epoxy resin DER736 and NBR Nipole 1072J used in Example 1 were used in a composition ratio of epoxy resin/NBR component = 3/1, and the composition ratio of granular phenolic resin was After blending in the proportions shown in Table 6 and dissolving it in methyl ethyl ketone, alumina hydrate Hygilite H is added in an amount of 50 to 80% by weight based on the combined weight of the resin component and NBR component.
-43M was added to create a matrix resin. Next, prepreg and honeycomb sandwich panels were produced in the same manner as in Example 1. Various properties of the obtained prepreg and honeycomb sandwich panels are shown in Table 6. The adhesive peel strength tended to improve as the epoxy resin and NBR components increased.

[Table] Examples 20 to 25 Granular phenolic resin/(epoxy resin +
Prepreg and honeycomb were prepared in the same manner as in Example 1, except that the mixing ratio of NBR)/alumina hydrate was 80/20/50, and the mixing ratio of epoxy resin and NBR was as shown in Table 7. I created a sandwich panel. Table 7 shows various properties of the obtained prepreg and honeycomb sandwich panels. As the proportion of NBR components increased, the adhesive peel strength increased, but the amount of smoke emission also tended to increase.

[Table] Examples 26-27 Instead of glass cloth KS181/A-1100 as a base material, Kepler cloth K285/KE420 [manufactured by Kanebo],
Example 1 was used except that carbon cloth CF3101 [manufactured by Kanebo] was used, the resin content was 58% for Kepler cloth and 49% for carbon cloth, and the matrix weight per unit area was the same as for glass cloth. Prepreg and honeycomb sandwich panels were made using the same method and various properties were investigated. The results are shown in Table 8. As shown in Table 8, the same effects were obtained even when the types of substrates were different. The details of the base materials used in the above examples are shown in Table 9.

【table】

[Table] (Effects of the Invention) The flame-retardant phenolic resin prepreg of the present invention has excellent adhesive properties and is useful for applications such as honeycomb sandwich panels, laminates, and FRP. Honeycomb sandwich panels made using the prepreg of the present invention are flame retardant, emitting low smoke and generating low heat even when burned, and are used as interior materials for aircraft, as well as for interior interiors of ships, vehicles, and buildings. It is also suitable as a material.

Claims (1)

[Claims] 1. A flame-retardant phenolic resin prepreg characterized in that the resin prepreg uses a matrix resin whose main components are a thermosetting phenolic resin, an epoxy resin, acrylonitrile-butadiene rubber, and alumina hydrate.