JP2666213B2 - Thermosetting phenolic resin composition - Google Patents

Description

The present invention relates to a thermosetting phenolic resin composition excellent in adhesiveness and processability as well as flexibility, and more particularly, flame-retardant, Also, the present invention relates to a thermosetting phenolic resin composition suitable for producing structural materials having good smoke emission characteristics during combustion, in particular, interior materials for aircraft, vehicles, ships and the like.

(Prior Art) In recent years, since honeycomb sandwich panels are lightweight, and have excellent strength and rigidity, they are often used mainly for structural materials of aircraft.

The honeycomb sandwich panel is a molded body made by laminating surface materials on both sides of the honeycomb and applying heat and pressure. Generally, the honeycomb core is made of aluminum or Nomex (Nomex Dupont, aromatic polyamide nonwoven fabric). Aluminum and fiber reinforced plastic are used as the surface material.

In particular, aircraft interior panels are often made of Nomex honeycomb and plastic surface materials reinforced with glass fiber, Kepler and carbon fiber.

Conventionally, a prepreg is formed by impregnating an epoxy resin as a matrix resin into a woven fabric of such a reinforcing material, and the honeycomb is pressed and heated to obtain a honeycomb sandwich panel. However, the use of flame-retardant and low-smoke materials has recently been regulated by law to ensure passenger safety in the event of fire, and materials with good smoke-generating properties during combustion have been introduced. Is required.

Phenolic resins are one of the leading candidates for this material. However, the phenol resin has flame retardancy and low smoke emission, but has a drawback that peel strength is low when used as a surface material of a honeycomb panel.

Also, ordinary phenolic resins, that is, resol resins, contain a large amount of unreacted monomer, free phenol,
In addition, since it has a low molecular weight, storage stability is poor, and there are many problems in operation, such as generation of a bad smell in a prepreg manufacturing process, necessity of a high concentration varnish, and the like.

(Problems to be Solved by the Invention) In view of the above-mentioned problems of the prior art, the present inventors have conducted intensive research and have found that certain thermosetting phenolic resins, epoxy resins and acrylonitrile-butadiene rubber (hereinafter referred to as NBR) Is known to improve the adhesiveness compared to the case where epoxy resin and NBR are blended with ordinary thermosetting phenolic resin, and it is possible to produce a flexible prepreg with good smoke emission characteristics. To complete the present invention.

An object of the present invention is to provide a thermosetting phenolic resin composition for producing a honeycomb sandwich panel having good peel strength and low smoke emission.

Still another object of the present invention is to provide a thermosetting phenolic resin composition for producing a flexible prepreg suitable for use in a honeycomb sandwich panel.

Still another object of the present invention is to provide a thermosetting phenolic resin composition having good workability during prepreg production.

Still other objects and advantages will be apparent from the following description.

(Means for Solving the Problems) The object of the present invention is to provide (A) a GPC (gel permeation chromatography) having a weight average molecular weight in terms of polystyrene of 1000 or more, and a value measured by liquid chromatography. Thermosetting phenolic resin (a) having a free phenol content of 500 ppm or less, polyglycol-type epoxy resin (b), and acrylonitrile-butadiene rubber (hereinafter referred to as "NBR") having a tertiary copolymer having a carboxylic component. (C) and an organic solvent (D), and (B) the composition ratio is (B) / [(B) +
(C)] = 50 / 50-95 / 5, ((a) + (b) + (c)) /
(D) = 5 / 95-80 / 20, (b) / (c) = 50 / 50-90 / 10, (C) excellent adhesion with flexibility and low smoke generation Thermosetting phenolic resin composition. Achieved by

The thermosetting phenolic resin used in the present invention is produced from formalin and phenols, and the present inventors have already disclosed JP-B-62-30210 and JP-B-62-3.
Preference is given to granular or powdery resins (hereinafter referred to as “granular phenolic resins”) composed of condensates of phenols and formaldehyde proposed in, for example, JP-A-0211.

The above-mentioned “granular phenol resin” is produced by the following method.

(1) The following composition, (a) Hydrochloric acid (HCl) concentration is 5 to 28% by weight, (b) Formaldehyde (HCHO) concentration is 3 to 25% by weight
And (c) using a hydrochloric acid-formaldehyde bath having a total concentration of hydrochloric acid and formaldehyde of 15 to 40% by weight, and (2) the following formula (A): The phenols are brought into contact with the hydrochloric acid-formaldehyde bath while maintaining the bath ratio represented by at least 8 or more, preferably 10.

As for the composition of the hydrochloric acid-formaldehyde bath of the above (1), in addition to the above three conditions (a), (b) and (c), furthermore, as a condition (d), Is preferably at least 2 or more, especially 2.5 or more, especially 3 or more. The upper limit of the molar ratio of the above condition (d) is not particularly limited, but is preferably 20 or less, particularly preferably 15 or less, and it is not economically advantageous to increase the molar ratio further. If the ratio is 2.5 or less, especially 2 or less, the reaction rate decreases, and it becomes difficult to obtain uniform and fine granular or powdery resin. A particularly preferred range for the above molar ratio is from 4 to 15. The above molar ratio is 2 or more, especially 2.5
The above is particularly effective when the bath ratio of (2) is relatively low, for example, when the bath ratio is 8 to 10.

The hydrochloric acid-formaldehyde bath having the bath composition of the above (1) has a bath ratio of 8 or more, preferably 10 to the weight of phenols.
While maintaining the above, phenols are brought into contact with the bath. An important feature is that a hydrochloric acid-formaldehyde aqueous solution having a considerably high concentration of hydrochloric acid (HCl) and containing excess formaldehyde relative to phenols has a bath ratio of 8 or more, preferably 10 or more. It consists in contacting the phenols with a large proportion. As described above, the reaction conditions for such phenols / formaldehyde are fundamentally different from the reaction conditions for the production of novolak resins and resol resins known in the art.

Hydrochloric acid-hydrochloric acid (HCl) concentration in formaldehyde bath is 10-2
5% by weight, in particular 15 to 22% by weight, is suitable and the formaldehyde (HCHO) concentration of the bath is 5 to 20% by weight, in particular 7 to 15% by weight.
% By weight, and the total concentration of hydrochloric acid and formaldehyde in the bath is preferably 20 to 35% by weight, particularly preferably 25 to 32% by weight.

When the hydrochloric acid-formaldehyde bath and the phenol are brought into contact, the bath ratio represented by the above formula (A) is 10 or more, especially
It is preferably 15 to 40.

The phenols are brought into contact with the above-mentioned hydrochloric acid-formaldehyde bath, and this contact is carried out. After the phenols come into contact with the bath, cloudiness is formed, and thereafter, at least a pink granular or powdery solid is formed. Do as you do. During the contact, the temperature in the reaction system is maintained at a temperature of 45 ° C. or less. The contacting of the hydrochloric acid-formaldehyde bath with phenols may be accomplished by adding phenols to the hydrochloric acid-formaldehyde bath to first form a clear solution and then produce a cloudiness, followed by at least a pink particulate or powder. It is preferable to carry out such that a solid in the form of a solid is formed.
At this time, in a stage before phenols are added to the bath to generate cloudiness, the bath is stirred to form a transparent solution as uniform as possible between the added phenols and the bath. It is preferable not to apply a mechanical shearing force such as stirring to the bath (reaction liquid) during a period from the point when the compound is formed to the time when a pale pink solid is formed.

The phenols to be added may be phenols themselves, but it is preferable to dilute the phenols with formalin, aqueous hydrochloric acid, water or the like. It is particularly preferable to dilute with water before use.

In particular, phenols are diluted with a formalin solution having a formaldehyde concentration of 8 to 44% by weight, preferably 20 to 40% by weight, and the phenol concentration is 50 to 95% by weight, especially 70 to 90% by weight.
It is preferable to use a solution prepared by preparing a diluted solution of phenols by weight in a hydrochloric acid-formaldehyde bath.
(B), (c), preferably (b), (b),
It is necessary to control so as to satisfy the conditions (c) and (d).

The temperature of the hydrochloric acid-formaldehyde bath at the time of adding phenols (or a diluted solution thereof) is 40 ° C or lower, preferably 5 to 35 ° C, particularly preferably 10 to 30 ° C. When the temperature of the bath exceeds 40 ° C., the reaction rate between phenols and formaldehyde becomes large. Therefore, the “particulate phenol resin” used in the present invention, which has a high methanol reactivity of 20% by weight or more as defined later, is used. Manufacturing becomes difficult.

As the phenols used, phenol is most preferred, but o-cresol and m-phenol may be used as long as they contain at least 80% by weight, especially at least 85% by weight of phenol.
Cresol, p-cresol, bis-phenol A, o
-, m-or p-C ₂ ~C ₄ alkyl phenol, p- phenylphenol, xylenols, or may be a mixture of one or more of resorcinol such known phenol derivatives.

The solids of "granular phenolic resin" formed in the bath as described above and having the desired reaction completed are separated from the hydrochloric acid-formaldehyde bath, washed with water, and preferably, the adhered hydrochloric acid is removed with an aqueous alkali solution. And then purified by washing with water.

As the alkali aqueous solution, for example, an aqueous solution of an alkali metal, particularly, an aqueous solution of ammonia is preferable. A suitable concentration of ammonia is 0.1 to 5% by weight, especially 0.8 to 8% by weight. The neutralization with the alkaline aqueous solution is advantageously performed at a temperature of 50 ° C. or less, preferably 10 to 40 ° C.

The above-mentioned water-washing treatment or further neutralization, the water-washed `` granular phenolic resin '' solid is dewatered and may be used as it is for final use, or it may be used at a temperature lower than the heat fusion temperature according to a conventional method, for example. After drying at 40-50 ° C, it can be used for end use. Before or after drying, the product may be lightly pulverized with an arbitrary pulverizer to obtain a product.

"Granular phenolic resin" obtained by the above method
Has a free phenol content of less than 500 ppm as measured by liquid chromatography, and preferred products have a free phenol content of less than 400 ppm, especially less than 300 ppm. The reason that the free phenol content is thus small is also as described in the above-mentioned production method, after adding phenols or a diluted solution thereof in a hydrochloric acid-formaldehyde bath to form at least a partially homogeneous solution, In order to produce an extremely smiling cloudiness and grow it into stable pink smiling particles, substantially all of the added phenols, especially those involved in the formation of the product of the present invention, are substantially all formaldehyde. It is thought to react.

The "particulate phenolic resin" products suitable for use in the present invention have a low free phenol content, which is a significant advantage for such granular or powdery products.

Further, the resin constituting the “particulate phenol resin” suitable for use in the present invention has the following characteristics in the infrared absorption spectrum: D _999-1015 / D ₁₆₀₀ = 0.2 to 9.0, D ₈₉₀ / D ₁₆₀₀ = 0.09 to 1.0. Have.

Further, those suitable for use in the present invention have a D ₉₉₀ -D ₁₀₁₅ / D ₁₆₀₀ of 0.2 to 5.0, particularly 0.3 to 4.0, and a D ₈₉₀ / D ₁₆₀₀ of 1.0 to 0.9, particularly 0.12 to 0.8. Have.

In the infrared absorption spectrum shows the absorption peak of D ₁₆₀₀ is attributed to the benzene nucleus, indicates the supply peak of D _999-1,015 is attributable to methylol group, further the peak of D ₈₉₀ is attributable to the hydrogen atom of an isolated benzene nucleus It is already widely known for phenol-formaldehyde resins to exhibit absorption.

A product suitable for use in the present invention is D _990-1015 / D ₁₆₀₀ = 0.2
Having a characteristic value of ~ 9.0 indicates that a product suitable for use in the present invention contains at least some amount of methylol groups, and that the methylol group content can be adjusted considerably. I have. Especially D ₉₉₀ -D ₁₀₁₅ / D ₁₆₀₀ = 0.2-5.
Products suitable for use in the present invention of 0, especially 0.3-0.4, contain moderate concentrations of methylol groups and are more stable.

Further, it is stated that the preferred product using the present invention has a characteristic of D ₈₉₀ / D ₁₆₀₀ = 0.09 to 1.0 in the infrared absorption spectrum of the product, and the more preferred product has the characteristic of D ₈₉₀ / D ₁₆₀₀ = 0.1 to 0.9, especially 0.12 to 0.8. The fact indicates that the products suitable for use in the present invention have the fact that the reactive sites (ortho and para positions) of the phenol molecules involved in the reaction are reasonably blocked by methylol groups.

Cured products of conventionally known resol resins are generally D
_990-1015 / D ₁₆₀₀ and D ₈₉₀ / D one both or either ₁₆₀₀ is lower than the lower limit of the characteristic values of the preferred product using the present invention, also cured by the novolak resin hexamine also D ₈₉₀ / The characteristic value of D ₁₆₀₀ is generally below the lower limit of 0.09 for products suitable for use in the present invention.

Further, the "particulate phenolic resin" product suitable for use in the present invention preferably has a methanol solubility of 20% by weight or more, and a preferable one thereof has a methanol solubility of 30% by weight or more, particularly 40% by weight or more. doing. This property indicates that the product suitable for use in the present invention contains a large amount of a condensate having a relatively high molecular weight that is soluble in methanol.However, as a value measured by GPC, a polystyrene equivalent of a conventional resol resin or novolak resin is used. The weight-average molecular weight is usually as small as 100 to 600 and contains a large amount of free phenol. However, when the above granular or powdery resin is as large as 1000 or more, favorable results can be obtained when applied to the present invention.

The polyglycol-type epoxy resin used in the present invention has a polyalkylene oxide component and is epoxidized at both ends, and for example, those represented by the following general formula are preferred.

The viscosity of the epoxy resin represented by the above general formula increases as n increases, and those having n = 2 to 10 are usually used. In the present invention, the polyglycol type epoxy resin represented by the above general formula is 50% A preferable result is obtained by using the ones contained above. However, when a bisphenol A type is used instead of the polyglycol type, for example, the adhesiveness and smoking characteristics are sufficiently exhibited or the prepreg has insufficient flexibility.

The tertiary copolymer NBR having a carboxylic component used in the present invention means an ordinary NBR rubber further copolymerized with (meth) acrylic acid or the like. Although the ratio of the carboxylic component is not particularly limited, it is usually 0.01 to 0.1 e.
The one of p / g is used.

The organic solvent applied to the present invention is preferably a thermosetting phenolic resin and a polyglycol-type epoxy resin, and a polar solvent that dissolves the three components of the NBR component, but is not limited thereto. Insoluble solvents may be mixed.

Examples of the polar solvent applied to the present invention include alcohols, ethers, esters, ketones, amides or a mixed solvent of two or more thereof, preferably methanol, ethanol, propanol, butanol, acetone, Methyl ethyl ketone, methyl isobutyl ketone, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, ethyl carbitol, butyl carbitol, ethyl acetate, acetate of ethyl carbitol,
Butyl carbitol acetate, DMF, DMSO or a mixed solvent of two or more thereof is suitable. Particularly, in terms of handleability and solubility, acetic acid esters of methanol, ethanol, acetone, methyl ethyl ketone, tetrahydrofuran, methyl cellosolve and ethyl carbitol are usually used.

An important point in the present invention is the compounding ratio of the composition of the present invention.

The greater the proportion of the phenolic resin, the better the smoke emission characteristics but the worse the adhesiveness and flexibility. Therefore, the composition ratio is generally 50/50 to 95/5, preferably 70/30 to 90/10, by weight, of the phenolic resin / polyglycol type epoxy resin and NBR component.

The composition ratio of the polyglycol-type epoxy resin to the NBR component is 50/50 to 90/10, particularly preferably 60/40 to 80/20, by weight.

The more the NBR component is added, the better the adhesiveness, but the smoke emission characteristics are worse, and the impregnation process of the composition into glass cloth or the like increases the amount of impregnation, making it impossible to obtain a uniform prepreg. The present inventors have reached the present invention by finding the optimum composition ratio of the composition.

When the amount of the organic solvent component in the composition of the present invention is too large, the amount of the resin adhered in the impregnation step is reduced. By repeating the impregnation, a product having the desired adhesion amount can be obtained, but it is complicated and not economical. Further, if the amount of the organic solvent component is small, there is a problem that impregnation in the impregnation step becomes difficult. Therefore, usually, resin component / organic solvent = 5/95 to 80/20, preferably 20/80 to 60
/ 40.

The composition of the present invention can be produced by blending components constituting the composition.

That is, the resin constituting the composition is dissolved in the organic solvent. The dissolution may be performed with or without heating, but is performed at about room temperature without heating to maintain the stability of the composition. Also, homodispers,
You may stir with a pomodifier etc. The dissolution may be performed simultaneously with each component or with each component alone.

When "granular phenolic resin" is used as the phenolic resin constituting the composition, there is a component which is not dissolved in the solvent, but whether to use it by filtration or without filtration may be selected as necessary.

Carboxylic NBR, which is a terpolymer of a rubber component constituting the composition, reacts with an epoxy resin, which is another component of the composition, and has a stronger adhesive action.

The composition of the present invention may be blended immediately before using the composition, for example, immediately before the production of a prepreg to be impregnated into a glass cloth, or may be blended and stored in advance. In particular, when a “granular phenol resin” is used as the thermosetting phenol resin of the present invention, the storage stability is good, which is advantageous for compounding the composition.

After impregnating the glass cloth with the composition of the present invention, it can be dried to obtain a prepreg.

This prepreg is bonded to, for example, a Nomex honeycomb core, and then heated under pressure to form a honeycomb sandwich panel. In particular, since the gel time of the prepreg is long and the prepreg has flexibility even with a small amount of volatile components, the merits such as easiness of the molding operation are great.

The drum peel strength of this honeycomb sandwich panel is several steps better than the panel made of phenol resin alone. It is also quite superior to ordinary phenolic resin / epoxy resin / NBR compound products.

In addition, the flame-retardant properties are not inferior to those of phenol resin alone, and are low-smoke emitting panels.

(Effect of the Invention) When the thermosetting phenolic resin composition obtained in the present invention is impregnated into a glass cloth or the like to form a prepreg, a flexible prepreg can be formed even with a low volatile content. Therefore, when press-molding by bonding to a honeycomb core, workability such as loading into a molding machine and degassing is easy, and a honeycomb panel having excellent self-extinguishing properties, low smoke generation and adhesive strength is obtained.

Such honeycomb sandwich panels are used not only as interior materials for aircraft, but also as interior materials for transportation equipment such as ships and vehicles and buildings.

In addition, this composition can be used as a varnish having good workability in applications other than the above, such as a laminate, and is very useful.

 Hereinafter, an embodiment will be described.

 In addition, the measurement in an Example was performed by the following method.

1. Polystyrene-equivalent weight average molecular weight Prepare a 0.1 wt% solids THF (tetravidrofuran) solution and filter with a 0.45μ membrane filter.
It was measured by GPC (gel permeation chromatography) and determined by conversion from a calibration curve of polystyrene.

2. Measure the viscosity of the solution sample adjusted to 25 ° C using a B-type viscometer.

3. Gel time Measured by the HP method at a temperature of 150 ° C.

4. Amount passing through 100 Tyler mesh sieve After the dried sample is lightly disintegrated by hand, if necessary, about 10 g is precisely weighed, and a 100 Tyler mesh sieve shaker (size of sieve: 200 mmφ) is weighed little by little in 5 minutes. , Shaking conditions: 200 RPM), and shake for another 10 minutes after the sample is charged. The amount of 100 Tyler mesh passing is calculated by the following formula.

ω ₀ : input amount (g) ω ₁ : amount remaining on the sieve without passing through the 100 Tyler mesh sieve 5. Quantification of free phenol content About 10 g of a sample passing through the 100 Tyler mesh was precisely weighed, and 100
Heat to reflux in 190 g of 30% methanol for 30 minutes.
The filtrate filtered through a glass filter (No. 3) is subjected to high performance liquid chromatography (6000A, Waters, USA)
Then, the phenol content in the filtrate was quantified, and the free phenol content in the sample was determined from a separately prepared calibration curve.

The operating conditions of the high performance liquid chromatography are as follows.

Apparatus: Waters 6000A, USA Column carrier: μ-Bondapak C ₁₈ column: 1/4 inch diameter x 1 foot length Column temperature: room temperature Eluent: methanol / water (3/7, volume ratio) Flow rate: 0.5 ml / Detector: UV (254 nm), Range 0.01 (1 mV) The phenol content in the filtrate was determined from a calibration curve prepared in advance (the relationship between the phenol content and the peak height based on phenol).

6. Measurement of infrared absorption spectrum and determination of absorption intensity Infrared spectrophotometer (225 type) manufactured by Hitachi, Ltd.
Was used to measure the infrared absorption spectrum of the measurement sample prepared by the ordinary KBr tablet method.

The absorption intensity at a specific wavelength was determined as follows.
A baseline is drawn at the peak for which the absorption intensity is to be determined in the measured infrared absorption spectrum. When the transmittance at the top of the peak is represented by tp and the transmittance of the baseline at that wavelength is represented by tb, the absorption intensity D at the specific wavelength is given by the following equation.

Thus, for example, the peak absorption intensity of 890 cm ^-1 and 1600 cm ^-1
Is given as the ratio (D ₈₉₀ / D ₁₆₀₀ ) of the respective absorption intensities determined by the above equation.

7.Heat-fusing property at 100 ° C Approximately 5 g of a sample passed through a 100 Tyler mesh is inserted between two 0.2 mm thick stainless steel plates.
It was pressed with an initial pressure of 50 kg for 5 minutes using a heat press machine (a single-acting compression molding machine manufactured by Shinto Metal Industry Co., Ltd.) heated to 100 ° C. After releasing the press, the hot pressed sample was removed from between the two stainless steel plates. If the removed sample is clearly adhered by melting or fusion to form a flat plate, the sample is judged to have fusibility, and if there is little difference between before and after hot pressing, It was determined to have infusibility.

8. Methanol Solubility (S) was accurately weighed sample of about 10g (to the precisely weighed weight and W _0), substantially heat treatment under reflux for 30 minutes in methanol about 500ml of anhydrous. Filtered through a glass filter (No3), further a filter residue sample was washed with methanol to about 100ml on the filter, then the filter was dried for 5 hours the remaining samples at a temperature of 40 ° C. (for the precisely weighed weight and W ₁ ). The methanol solubility was determined by the following equation.

9. Adhesive peel strength: Drum peel method (MIL-STD-401B)
Method).

10. Smoke emission: Measured by NBS method (ASTM-E-662 non-flame method).

11. Self-digestibility: Those digested within 15 seconds after ignition were regarded as self-digestible.

12.NBS Ds value: When the light transmittance in the chamber is T% 13. Flexibility: A prepreg piece of 240 × 20 nm is placed on a horizontal table, and the other end is held down while the other end is dropped on a 45 ° inclined surface from the end of the horizontal table.

14. Volatile content: weight difference before and after heating and weight ratio before heating when prepreg is heated at 150 ° C. for 15 minutes Example 1 and Comparative Examples 1 to 3 The following “granular phenol” having a molecular weight of 3,200 and a free phenol content of 32 ppm Resin ", polyglycol type epoxy resin DER-736 [Dow Chemical's epoxy equivalent 198n = 3]
And nitrile rubber nipol 1072J [27% carboxyl group-containing terpolymer having an acronitrile value of 27%, manufactured by Zeon Corporation] in a composition ratio (weight ratio) of phenol resin / epoxy resin / NBR =
On 8/2/1, it was dissolved in methyl ethyl ketone at room temperature using a homodisper to obtain a varnish.

Use this varnish as a glass cloth (KS181 / A-1100 made by Kanebo)
And then dried at 70 ° C with a drier,
A 39% prepreg was made.

As a comparative example, a bisphenol-type epoxy resin epototo YD128 (manufactured by Toto Kasei Co., Ltd.) was used as the epoxy resin (Comparative Examples 1 and 3), and Nipol 1042, a nitrile rubber containing no carboxyl group, was used as the NBR component [Japan (Zeon Co., Ltd.)] (Comparative Examples 2 and 3), prepregs having the same composition were prepared.

Next, these prepregs were converted to Nomex honeycomb SA
Laminated on both sides of H1 / 8-3.0 (Showa Aircraft Industry)
It was formed at a temperature of 1500 ° C. and a pressure of 2.8 kg / cm ² for 1 hour using a hot press machine to prepare a honeycomb sandwich panel.

Drum peel strength of these panels, Ds by NBR method
Table 1 shows the flammability and the volatile content and flexibility of the prepreg.

It can be seen that, by blending the specific epoxy component and the NBR component, a flexible prepreg can be obtained even with a small amount of volatile components, and the adhesive strength can be greatly improved.

 The “granular phenol resin” was produced as follows.

"Production of Granular Phenolic Resin" A 10 l separable flask was charged with 10 kg of a mixed aqueous solution containing 18% by weight of hydrochloric acid and 7% by weight of formaldehyde. Although the room temperature was 20 ° C., the temperature of the mixed aqueous solution was kept at 18 ° C. (Run No. 1) by adjusting the temperature. While stirring this, a diluent obtained by diluting 315 g of phenol with 35 g of water was added at a time. The stirring was stopped for 45 seconds after adding the diluent and stopped, but the mixture rapidly turned cloudy 68 seconds after stopping the stirring, milky products were observed, and these milky products gradually turned pink. did. The liquid temperature is above 18 ℃ (Run
It gradually rose from No. 1), reached a peak at 32 ° C. in 15 minutes after the diluent was charged, and fell again. After the diluent was charged and left for 60 minutes, the mixed aqueous solution in which the contents were formed was again stirred for 5 minutes. The contents separated into solid and liquid by using a glass filter are washed with water, treated in a 0.5% by weight aqueous ammonia 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 was 0.3% by weight, and the yield was 377 g (Run No. 1).

Most of the above-mentioned contents were observed by optical microscopic observation.
~ 15 microns spherical or granular fine powder, 99% by weight
The above passed through a 100 Tyler mesh sieve.

Examples 2 to 6 and Comparative Examples 4 and 5 "Particulate phenol resin" having a molecular weight of 3,200 and a free phenol content of 32 ppm, and a polyglycol type epoxy resin Dow. Epoxy resin DER736 and nitrile rubber nipol 1072J were dissolved in methyl ethyl ketone with changing the ratio (weight ratio) of the phenol resin component to obtain a varnish.

These varnishes were coated with the resin in the same manner as in Example 1.
A 39% prepreg was made and molded into Nomex honeycomb and sandwich panels.

Drum peel strength of these panels, Ds by NBR method
The values, flammability and volatile content and flexibility of the prepreg are shown in Table 2.

As the epoxy resin and NBR components increase, the drum peel strength improves but the Ds value tends to increase.

Examples 7 to 10 and Comparative Examples 6 and 7 In the same manner as in Example 1, "granular phenol resin", polyglycol type epoxy resin Dow / epoxy resin DER736 and nitrile rubber Nipol 1072J were changed by changing the ratio (weight ratio) of rubber components. A varnish was dissolved in methyl ethyl ketone, and impregnated in a glass cloth to prepare a prepreg.

The prepreg and the Nomex honeycomb were used to form a honeycomb sandwich panel.

Table 3 shows the strength of these drum peels, the Ds value according to the NBS method, the flammability, and the volatile content and flexibility of the prepreg.

As the blending of the rubber component increases, the drum peel strength improves, but the Ds value tends to increase.

Example 11 A honeycomb panel was prepared in exactly the same manner as in Example 1 except that another polyglycol type epoxy resin DER732 (manufactured by Dow Chemical Company) was used instead of the epoxy resin, and the drum peel strength, Ds value, and flammability were measured. Table 4 shows the results of evaluating the volatile content and flexibility of the prepreg.

Even if the type of polyglycol type epoxy resin was different, almost the same effect was obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location C08L 9:02)

Claims (1)

(57) [Claims] (A) The weight average molecular weight in terms of polystyrene is 1000 or more as measured by GPC (gel permeation chromatography) and the free phenol content is 500 p as measured by liquid chromatography.
pm or less thermosetting phenolic resin (a), polyglycol-type epoxy resin (b), acrylonitrile-butadiene rubber of terpolymer having carboxylic component (c), and organic solvent (d) (B) The composition ratio is (a) / [(b) + (c)] = 50/50 to 95/5, [(a) + (b) + (c)] / (D) = 5 / 95-80 / 20, (b) / (c) = 50 / 50-90 / 10, (C) Excellent adhesiveness with flexibility and low smoke generation Thermosetting phenolic resin composition.