JPH0517602A - Prepreg resin composition and prepreg - Google Patents

Abstract

PURPOSE:To obtain a resin composition for use in a prepreg which composition foams little, shows excellent initial bonding strength, and is useful in producing a honeycomb-sandwich panel with excellent appearance and bonding strength without prolonging the production time, and to obtain a prepreg from the composition. CONSTITUTION:This composition comprises a nitrogenous phenolic resin having 0.2wt.% or more nitrogen atoms, poly(vinyl butyral), a flame retardant and a filler, has a gel time of 80-200 sec at 150 deg.C, and gives and DSC curve having an exothermic peak in curing at 190 deg.C or higher. The composition is infiltrated into glass fibers to obtain a prepreg.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for prepreg, which is used for manufacturing a honeycomb sandwich panel and has a low foaming property upon curing and an excellent adhesive force.
The present invention relates to a prepreg using the resin composition.

[0002]

2. Description of the Related Art A honeycomb sandwich panel is a molded product obtained by laminating an aluminum material or a fiber reinforced plastic material on both sides of a honeycomb made of aluminum or Nomex Core phenolic resin prepreg, and is lightweight.
Moreover, since it is excellent in strength and rigidity, it is widely used as a structural material and an interior material for aircraft and the like. And in recent years,
As the demand for weight reduction becomes stronger and stronger, the demand for ensuring safety in the event of a fire has led to the use of phenol resin prepreg, which has features such as flame retardancy and low heat buildup during combustion, low smoke generation, and low harmful gas properties. The demand for honeycomb sandwich panels is increasing.

By the way, a prepreg using a phenol resin as a matrix material generally produces a large amount of gas during molding (when the phenol resin is cured), and tends to cause surface defects due to foaming after molding. In order to improve the surface quality of such a phenol resin prepreg, it is preferable to use, as the matrix material, a phenol resin composition having a slow curing rate and designed to be cured after the volatile components are sufficiently removed. desirable. However, when the curing speed is slow, there is a problem that the curing of the phenol resin in the honeycomb sandwich panel manufacturing cycle becomes insufficient, and sufficient adhesive force and physical properties are not developed within a predetermined manufacturing time.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and is a resin composition for prepreg containing a phenolic resin as a main component, which resin composition is used. In producing a honeycomb sandwich panel by curing a prepreg, a resin composition that forms a prepreg that has a low foaming property and that is cured at an appropriate rate to develop a sufficient initial adhesive force, and the resin composition made of glass. It is intended to provide a prepreg obtained by impregnating a woven cloth.

[0005]

[Means for Solving the Problems] The inventors of the present invention have been keen to achieve both the reduction of the foaming phenomenon at the time of curing of a phenol resin prepreg and the development of an initial adhesive force which is closely related to the curing speed, which have not been compatible with each other. Researched. As a result, they have found that the above object can be achieved by appropriately setting the gelling property and the curing property of the matrix resin composition of the prepreg, and completed the present invention.

That is, the first aspect of the present invention comprises a phenolic resin, a polyvinyl butyral resin, a flame retardant and a filler, and the gelling time at 150 ° C. is 8
A resin composition for prepreg, which has a peak exothermic temperature of curing of 190 ° C. or higher by DSC for 0 to 200 seconds.

A second aspect of the present invention is a prepreg characterized in that a glass woven fabric is impregnated with the resin composition for prepreg of the first aspect of the present invention.

The present invention will be described in detail below. First, each substance constituting the present invention will be described.

The thermosetting phenolic resin which constitutes the present invention is an alkylphenol such as phenol, cresol or xylenol, or a halogenated alkylphenol in which a part of hydrogen atoms of the benzene ring of alkylphenol is substituted with a halogen atom. Various phenols such as formaldehyde, paraformaldehyde,
It is a resin synthesized by addition and condensation reaction with aldehydes such as acetaldehyde and furfural. Phenolic resins are roughly classified into two types according to the catalyst used during the synthesis, one of which is a novolac type phenol resin synthesized by an acidic catalyst, and the other of which is a resol type phenol resin synthesized by a basic catalyst. is there. The novolac phenolic resin is
Although an amine-based curing agent such as hexamethylenetetramine or ammonia is required as a catalyst, the resol-type phenol resin need only be heated.

In the present invention, phenol or cresol is used as the phenols, and formaldehyde, paraformaldehyde, or acetaldehyde is used as the aldehydes, and the aldehydes are 1.0 to 2. A phenolic resin obtained by reacting at a ratio of 5 mol is preferable.

Alternatively, a phenolic resin synthesized by using ammonia as a catalyst and having a nitrogen-containing bond containing 0.2 wt% or more of nitrogen atoms (mainly derived from ammonia) is preferable. The phenolic resin containing such a nitrogen atom has excellent adhesion to the glass fiber constituting the prepreg.

The phenol resin is separated from the reaction mixture after synthesizing the phenol resin by adjusting the pH to 3 by adding an acidic substance such as hydrochloric acid, sulfuric acid, boric acid, acetic acid or lactic acid to the reaction mixture. It is neutralized so as to be ˜8, and after removing the neutralized salt by washing with water or the like, or without removing it, dehydration is performed under reduced pressure, and then a solvent is added if necessary. Further, containing 0.2 wt% or more of nitrogen atoms means that 0.2 wt% or more of the solid content of the product after such dehydration or the one to which the solvent is added is the nitrogen atom.

The polyvinyl butyral resin is a resin synthesized by reacting polyvinyl alcohol with butyraldehyde under an acid catalyst, and as shown in the formula A, a copolymer of vinyl butyral, vinyl acetate and vinyl alcohol. it is conceivable that.

[0014]

[Chemical 1]

The butyralization ratio of the polyvinyl butyral resin applied to the present invention is not particularly limited, but usually 7
It is 0% or more. When the butyralization rate is within this range, it is preferable in terms of the adhesive strength of the prepreg. In the present invention, the butyralization rate indicates the rate at which the hydroxyl groups of polyvinyl alcohol are butyralized in percentage.

The average degree of polymerization (x + y + z) of the polyvinyl butyral resin is not particularly limited, but usually 50.
It is about 0 to 1000. When the average degree of polymerization is within this range, it is preferable in terms of the adhesive strength of the prepreg.

The flame retardant refers to aromatic bromine compounds, phosphorus compounds, antimony trioxide and the like.

The filler refers to silica, calcium carbonate, whiskers and the like.

The glass woven cloth refers to cloth woven of glass fibers in a plain weave or a twill weave.

The resin composition for prepreg of the first aspect of the present invention contains the above-mentioned phenolic resin, polyvinyl butyral resin, flame retardant and filler, and has a gelation time at 150 ° C. of 80 to 200 seconds, And DS
Curing exothermic peak temperature by C (differential scanning calorimetry) is 1
The temperature is 90 ° C or higher.

When the gelling time is less than 80 seconds, when the resin composition for prepreg contains a volatile component (solvent), the volatile component cannot be sufficiently removed, and the volatile component cannot be removed early. Since the matrix resin of the prepreg (resin composition for prepreg) has poor fluidity, foaming causes poor appearance and poor adhesion to the honeycomb, resulting in poor adhesive strength. On the other hand, 200
If it exceeds seconds, the initial adhesive strength will be insufficient because it will not be sufficiently cured within the normal honeycomb sandwich panel manufacturing cycle.

Curing exothermic peak temperature by DSC is 190
If the temperature is lower than 0 ° C., the reaction is likely to proceed even at the initial stage of the curing reaction, and the viscosity of the matrix resin of the prepreg rapidly increases at an early stage.

The essential constituent component of the resin composition for prepreg of the first aspect of the present invention is the above-mentioned phenolic resin,
Polyvinyl butyral resin, flame retardant and filler, the blending ratio is not particularly limited as long as the gelling time of the resin composition for prepreg and the curing exothermic peak temperature by DSC fall within the above range, but the phenolic resin With respect to 100 parts by weight, the polyvinyl butyral resin is preferably 1 to 30 parts by weight, the flame retardant is 1 to 20 parts by weight, and the filler is preferably 0.1 to 10 parts by weight.

The polyvinyl butyral resin is a component that contributes to the adhesive strength of the prepreg, but if it is less than 1 part by weight, the strength becomes insufficient, and if it exceeds 30 parts by weight, the viscosity of the resin composition is high. Therefore, it becomes difficult to impregnate the glass woven fabric with the resin composition during the production of the prepreg.

If the amount of the flame retardant is less than 1 part by weight, a sufficient flame retarding effect cannot be obtained, and if it exceeds 20 parts by weight, the adhesive strength of the prepreg may be insufficient.

If the amount of the filler is less than 0.1 parts by weight or more than 10 parts by weight, the strength of the prepreg after curing is insufficient.

The prepreg resin composition of the first aspect of the present invention may further contain the following components within the range not impairing the gist of the present invention.

That is, a solvent such as methanol, ethanol, or methyl ethyl ketone, or water, various carbon blacks, finely divided silica, calcined clay, basic magnesium silicate, for adjusting the viscosity and facilitating the impregnation into the glass woven cloth, Inorganic powder such as diatomaceous earth powder, alumina, magnesium carbonate, magnesia, kaolin, sericite, inorganic fiber such as ceramic fiber, asbestos, rock wool, glass fiber, slag / wool, carbon fiber, and various synthetic fibers such as polyimide fiber Reinforcing agent, etc.
White pigments such as titanium dioxide for coloring the composition, and color pigments such as yellow lead, carbon black, iron black, molybdenum red, konjac, kunjou, cadmium yellow, cadmium red, and various organic dyes, colloidal silica. ,
Examples include anti-dripping agents such as carbon black, various rubbers, polythiols, polycarboxylic compounds, and flexibility-imparting agents such as urethane prepolymers.

The prepreg of the second aspect of the present invention is obtained by impregnating the glass woven fabric with the resin composition for prepreg of the first aspect of the present invention.

In the prepreg of the second aspect of the present invention, the proportion of the glass woven fabric is preferably 30 to 80% by weight, and the non-volatile content in the resin composition for prepreg is 70 to 20% by weight. Outside this range, it may be unsuitable as a prepreg.

Further, a general method for producing a prepreg is as follows. If necessary, a lower alcohol such as methanol and ethanol, a ketone such as methyl ethyl ketone, or a suitable solvent such as water is contained in the resin for the prepreg according to the first aspect of the present invention. A certain amount of the composition is applied to a glass woven fabric, impregnated with it, and then dried at about 80 to 120 ° C. for about 5 to 20 minutes.

When a honeycomb sandwich panel is manufactured using the prepreg of the second aspect of the present invention, after the honeycomb core and the prepreg are brought into contact with each other, usually 150 to
The matrix resin in the prepreg may be heated and cured in the range of 300 ° C. At that time, it is preferable to perform vacuum forming or to apply pressure, and the pressure is 0.1
It may be appropriately selected within the range of 10 kg / cm ² .

[0033]

EXAMPLES The present invention will be described below with reference to examples. In the following, "parts" and "%" all mean "parts by weight" and "% by weight".

(1) Production of Phenolic Resin (Production Example 1) Phenol 1000 was placed in a reaction vessel equipped with a stirrer.
Part, formalin 1380 parts (formaldehyde / phenol = 1.60 (molar ratio)) were charged, then 40 parts of potassium hydroxide and 30 parts of 28% ammonia water were added, and the temperature was gradually raised until 80 ° C was reached. The reaction was carried out for 3.0 hours. After the reaction was completed, 75 parts of 36% hydrochloric acid was added to adjust the pH to 6
Then, after adding water to wash and removing the catalyst, dehydration reaction was carried out under vacuum, and when the water content reached 8%, 120 parts of methanol was added to the resol-type phenol resin A.
1,200 parts of a methanol solution of This one 135
When dried at 0 ° C. for 1 hour, the residual solid content was 80%. The nitrogen content of this product was 0.6% based on the solid content.

(Production Example 2) 1150 parts of a methanol solution of the resol type phenol resin B was obtained in the same manner as in Production Example 1 except that the reaction time was 2.0 hours. The residual solid content of this product was 79%. The nitrogen content of this product was 0.6% based on the solid content.

(Production Example 3) 1250 parts of a methanol solution of the resol type phenol resin C was obtained in the same manner as in Production Example 1 except that the reaction time was 4.0 hours. The residual solid content of this product was 81%. The nitrogen content of this product was 0.6% based on the solid content.

(Production Example 4) 1400 parts of a methanol solution of the resol-type phenol resin D was obtained in the same manner as in Production Example 1 except that the washing step with water was omitted. The residual solid content of this product was 83%. The nitrogen content of this product was 0.6% based on the solid content.

(Production Example 5) 1200 parts of a methanol solution of the resol type phenol resin E was obtained in the same manner as in Production Example 1 except that the combined use of the ammonia catalyst was omitted. The residual solid content of this product was 80%. The nitrogen content of this product was 0% based on the solid content.

(2) Production of prepreg (Example 1) 20% of polyvinyl butyral resin (# 4000-1) manufactured by Denki Kagaku Kogyo Co., Ltd. was added to 1000 parts of a methanol solution of the phenol resin A obtained in Production Example 1. 400 parts of a methanol solution, 30 parts of a flame retardant (tetrabromobisphenol A), and 10 parts of a filler (aerosil) were added and sufficiently mixed, and then methanol was added to obtain a varnish having a total solid content of 50%. The obtained varnish was impregnated into a glass woven cloth (Glass treated textile style 1581 manufactured by Kanebo Co., Ltd.) and dried in a dryer at 70 ° C. for 10 minutes to obtain a prepreg having a resin adhesion amount of 41% and a volatile content of 1.2%. It was made.

Example 2 Example 1 was repeated, except that 1013 parts of the phenol resin B methanol solution obtained in Production Example 2 was used in place of the phenol resin A methanol solution.
In the same manner as above, a prepreg having a resin adhesion amount of 42% and a volatile content of 1.5% was prepared.

(Example 3) In the same manner as in Example 1 except that 988 parts of the methanol solution of the phenol resin C obtained in Production Example 3 was used in place of the methanol solution of the phenol resin A, the resin adhesion amount of 40 %, And a volatile content of 1.3% was prepared.

(Comparative Example 1) In the same manner as in Example 1 except that 964 parts of the methanol solution of the phenol resin D obtained in Production Example 4 was used in place of the methanol solution of the phenol resin A, the resin adhesion amount 43 %, And a volatile matter of 1.5% was prepared.

Comparative Example 2 Example 1 was repeated, except that 1020 parts of the phenol resin E methanol solution obtained in Production Example 5 was used in place of the phenol resin A methanol solution.
In the same manner as above, a prepreg having a resin adhesion amount of 42% and a volatile content of 1.2% was produced.

(3) Test / Evaluation (a) Production and Evaluation of Honeycomb Sandwich Panel Each prepreg produced in (2) was manufactured by Showa Aircraft Industry Co., Ltd. Nomex Honeycomb (SAH-1 / 8-3.0, 0. Four
63 ”t) on both sides, 130 ° C in a vacuum bag
Then, the mixture was cured and molded for 1 hour to prepare a honeycomb sandwich panel. With respect to this honeycomb sandwich panel, the appearance was visually evaluated, and the case where there were many voids generated by evaporation of residual volatile matter and condensed water was evaluated as x, and the case where almost no voids were observed was evaluated as o. Further, the adhesive force between the honeycomb and the prepreg cured product was measured by the drum peel method. The results are shown in Table 1.

(B) Measurement of gelation time From each of the prepregs prepared in (2), a matrix resin composition was extracted with tetrahydrofuran, and 15
The gel time at 0 ° C was measured. The results are shown in Table 1.

(C) Measurement of Curing Exothermic Peak Temperature A sample was cut out from each prepreg prepared in (2), placed in a pressure vessel, and subjected to DSC measurement at a temperature rising rate of 10 ° C./min. The results are shown in Table 1.

[0047]

[0048]

EFFECTS OF THE INVENTION According to the present invention, a resin composition for prepreg, which has a low foaming property upon curing and is cured at an appropriate rate to exhibit a sufficient initial adhesive strength, and glass fibers are impregnated with the resin composition. Prepreg is provided. By using the prepreg according to the present invention, it is possible to obtain a honeycomb sandwich panel having excellent appearance properties and adhesive strength within a conventional manufacturing cycle.

Claims (3)

[Claims] 1. A phenolic resin, a polyvinyl butyral resin, a flame retardant and a filler are contained at 150 ° C.
Gelation time in 80 to 200 seconds, and D
A resin composition for a prepreg, which has a curing exothermic peak temperature of 190 ° C. or higher by SC. 2. The phenolic resin is 0.2 wt%
The resin composition for prepreg according to claim 1, which is a phenolic resin having a nitrogen-containing bond containing the above nitrogen atoms. 3. A prepreg obtained by impregnating a woven glass cloth with the resin composition for prepreg according to claim 1.