JP3431826B2 - Phenolic resin foam and method for producing the same - Google Patents

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phenol resin-based foam and a method for producing the same, and the fields in which the phenol resin-based foam obtained by the present invention is used are phenol resin-based foam alone or glass fiber. By combining with mats made of reinforcing fibers such as, and sheet materials, and core materials such as various honeycomb cores, the field of structural members represented by automobile interior materials, buildings, aircraft, vehicles,
Fields such as heat insulating materials and soundproofing materials used in ships and the like will be raised.

2. Description of the Related Art Conventionally, phenol resin foams are excellent in heat resistance and flame retardancy, and by combining with mats made of reinforcing fibers such as glass fibers, sheet-like materials and core materials such as various honeycomb cores, Since a molded product can be easily obtained, it is widely used for various structural members, heat insulating materials, building materials and the like. As a typical method for producing a phenolic resin-based foam, hexanomethylenetetramine as a curing agent and a solid powdery or granular foaming agent are mixed with a novolac-type phenolic resin as a main component at a predetermined ratio, and the mixture is pulverized using a pulverizer. By mixing, a novolac type phenolic resin composition is obtained. Next, this novolac type phenolic resin composition is evenly dispersed on a predetermined mold or a glass fiber mat, and if necessary, combined with a core material such as a honeycomb core, and foamed and cured at an oven, a molding press or the like. A novolac type phenolic resin foam is obtained by heat-treating at the above temperature for a predetermined time. In recent years, due to the growing awareness of environmental issues and the impact of organic compounds on the human body, even for phenolic resin foams, the amount of exhaust gas generated during molding is suppressed, the amount of organic compounds released from molded products, and The degree of pleasure and discomfort based on human sensory evaluation is also becoming more important. Among them, formaldehyde, which is harmful to the human body, is discharged at each factory, and the total amount is being regulated. Therefore, not only formaldehyde but also the emission of organic compounds will be required to be suppressed in the future. It is clear here that in the production of the phenolic resin-based foam, as described above,
Hexamethylenetetramine is generally used as the curing agent, but hexamethylenetetramine decomposes into formaldehyde and ammonia by heat applied during molding. Most of the formaldehyde is incorporated into the resin structure as a cross-linking agent, but some that is not incorporated will be released to the atmosphere or will remain in the foam structure. Also, with respect to ammonia, in the process of thermal decomposition of hexamethylenetetramine, part of it is taken into the resin structure, but most of it is released to the atmosphere, or as ammonia gas, it enters the foam structure. Will remain. Thus, the organic compound remaining in the foam structure is gradually released even at room temperature,
Further, when exposed to a high temperature for some reason, there is a phenomenon that the particles are accelerated and released. Therefore, depending on the location where the phenolic resin foam is used, the released organic compound may cause an unpleasant odor.

The present invention focuses on the above-mentioned problems, and releases formaldehyde and ammonia during molding without impairing the moldability and flame retardancy of the conventional phenol resin foam. It is an object of the present invention to provide a phenolic resin foam capable of reducing the amount and a method for producing the same.

The phenol resin foam of the invention according to claim 1 is a novolac type phenol resin, an epoxy resin, dinitrosopentamethylenetetramine, P, P'-oxybisbenzenesulfonylhydrazone, It is characterized in that it is obtained by heat-treating a resin composition comprising one or more foaming agents of hydrazodicarbonamide, P-toluenesulfonyl hydrazide and azodicarbonamide. In the phenol resin-based foam of the invention according to claim 2, the resin composition according to claim 1 has a novolac-type phenol resin / epoxy resin blending ratio of 85/15 to 20/80 (weight ratio). The blending ratio of the foaming agent is 1 to 10 parts by weight based on 100 parts by weight of the total resin amount of the novolac type phenol resin and the epoxy resin. The phenolic resin-based foam of the invention according to claim 3 is a novolac type phenolic resin, an epoxy resin, dinitrosopentamethylenetetramine, P, P'-.
What is obtained by heat-treating a powdery phenolic resin composition comprising one or more blowing agents of oxybisbenzenesulfonylhydrazone, hydrazodicarbonamide, P-toluenesulfonylhydrazide and azodicarbonamide. It is a feature. In the phenol resin-based foam of the invention according to claim 4, the resin composition according to claim 3 has a blending ratio of novolac type phenol resin / epoxy resin of 85/15 to 20/80.
(Weight ratio), and the blending ratio of the foaming agent is a total resin amount of the novolac-type phenol resin and the epoxy resin 10
It is characterized by being 1 to 10 parts by weight with respect to 0 parts by weight. The method for producing a phenolic resin-based foam of the invention according to claim 5 is a novolac type phenolic resin, an epoxy resin, dinitrosopentamethylenetetramine, P, P'-oxybisbenzenesulfonylhydrazone, hydrazodicarbonamide, P. -Toluenesulfonyl hydrazide, azodicarbonamide, or a resin composition comprising one or more foaming agents. In the method for producing a phenol resin-based foam of the invention according to claim 6, the resin composition according to claim 5 has a novolac-type phenol resin / epoxy resin blending ratio of 85/15 to 20/80 (weight ratio). ), And the blending ratio of the foaming agent is 1 to 10 parts by weight based on 100 parts by weight of the total resin amount of the novolac-type phenol resin and the epoxy resin. The method for producing a phenolic resin-based foam of the invention according to claim 7 is a novolac type phenolic resin, an epoxy resin, dinitrosopentamethylenetetramine, P, P '.
-Powdering a phenol resin composition comprising one or more blowing agents of oxybisbenzenesulfonylhydrazone, hydrazodicarbonamide, P-toluenesulfonylhydrazide, azodicarbonamide, and powdering It further comprises a step of spraying the phenol resin composition on a plane, and a step of heat-treating the phenol resin composition sprayed on the plane. In the method for producing a phenolic resin-based foam of the invention according to claim 8, the resin-based composition according to claim 7 has a novolac-type phenolic resin / epoxy resin blending ratio of 85/15 to 20/80 (weight. The ratio of the foaming agent is 1 to 100 parts by weight of the total resin amount of the novolac type phenol resin and the epoxy resin.
It is characterized by being 10 parts by weight. In order to solve the above-mentioned problems, the present inventors have studied a system in which hexamethylenetetramine is not used as a curing agent for a novolac type phenol resin, but a solid epoxy resin is used instead. Here, since the curing reaction rate of the novolac type phenol resin and the epoxy resin is significantly slower than that using hexamethylenetetramine, it is necessary to use a curing accelerator together. In a system of epoxy resin and novolac type phenolic resin, it is common to add imidazoles, acid anhydrides, etc. as curing accelerators, but even if these curing accelerators are added, the moldability is not sufficient. In comparison with the conventional novolac-type phenol resin-hexamethylenetetramine-based molding time, a longer molding time must be taken, which makes it practically difficult to use when considering production efficiency. There was a problem.
Therefore, the present inventors have paid attention to the organic foaming agent necessary for foam formation, and as a result of the examination, confirmed that the pyrolysis-type nitrogen-containing organic foaming agent has a large curing-accelerating effect, and used it. As a result, it was found that even a novolac-type phenol resin-epoxy resin system can provide moldability comparable to that of the novolac-type phenol resin-hexamethylenetetramine system, thus completing the present invention. The present invention will be described in detail below. As is well known, the novolac type phenol resin used in the present invention is obtained by reacting phenols and aldehydes in the presence of an acidic catalyst. As the phenols, phenol, cresol, xylenol, resorcin, catechol and the like are used, and they can be used alone or in combination of two or more. Formaldehyde, paraformaldehyde, acetaldehyde and the like are used as the aldehydes, and they can be used alone or in combination of two or more. As the acidic catalyst, organic acids such as oxalic acid, p-toluenesulfonic acid and citric acid, and inorganic acids such as hydrochloric acid and sulfuric acid are used. The epoxy resin used in the present invention may be a powdery solid one, for example,
Examples thereof include aromatic epoxy resins such as bisphenol A type epoxy resin, phenol novolac type epoxy resin, orthocresol novolac type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin and the like. Other examples include alicyclic epoxy resins and aliphatic epoxy resins. Among them, the ortho-cresol novolac type epoxy resin is preferable because it is excellent in moldability, flame retardancy when formed into a phenol resin foam, and physical properties. Examples of the foaming agent used in the present invention include organic pyrolyzable foaming agents such as dinitrosopentamethylenetetramine, P,
Any one of P′-oxybisbenzenesulfonyl hydrazone, hydrazodicarbonamide, P-toluenesulfonyl hydrazide and azodicarbonamide can be used alone or in combination of two or more. Among them, dinitrosopentamethylenetetramine is preferable because it has a large effect of promoting the curing reaction between the novolac type phenol resin and the epoxy resin. In addition, if necessary, in order to adjust the state of the foam during foaming, a silicone-based foam stabilizer, a nonionic surfactant, an anionic surfactant, etc., as a foam stabilizer are mixed in advance with the novolac-type phenol resin. You can take a way to keep it. As a method for obtaining a foam, a novolac-type phenol resin, an epoxy resin, and a foaming agent are mixed in a predetermined ratio, and then the mixture is pulverized to obtain a powder having an average particle diameter of about 50 μm. At this time, if necessary, each component is uniformly mixed by using a mixer or the like. The phenol resin composition thus obtained was directly and evenly dispersed in a predetermined mold, or evenly dispersed on a non-woven fabric or a glass fiber mat.
A phenol resin foam can be obtained by heat treatment in an oven maintained at 40 to 240 ° C. or using a molding press or the like until sufficient foaming and curing are obtained.

EXAMPLES Examples will be shown below. The present invention is described in the following examples.
It is not limited to. [Example 1] Phenol and formalin according to a conventional method
Was obtained in the presence of an oxalic acid catalyst.
70 weight of novolak type phenolic resin with softening point of 95 ℃
Parts, orthocresol novolac type epoxy resin EOC
N-103S (Nippon Kayaku Co., Ltd.) 30 parts by weight, foaming
6 parts by weight of dinitrosopentamethylenetetramine as an agent
After mixing, crush with a crusher and mix each component uniformly
By doing so, a phenol resin composition was obtained. this
The particle size at that time was 10 to 70 μm. Then this pheno
Glass resin chopped strand mat
(Basis weight: 600 g / m² Product) spraying amount of 350g / m²
After spraying evenly so that at 120 ℃ ~ 150 ℃
By heat-treating for several seconds, the phenol resin group
The product is fused and fixed on a glass chopped strand mat
And made a prepreg. 2 sheets of this prepreg
The layered product is heated in a molding press with a hot plate temperature of 230 ° C. to 60
Phenol with a thickness of 2.5 mm by heat treatment for seconds
A resin foam was obtained. [Example 2] Phenol obtained in the same manner as in Example 1
Polyester non-woven fabric (resin weight: 80 g /
m²) Spray amount of 350g / m on top²Evenly so that
After that, heat treatment at 120-150 ℃ for several seconds
From a phenolic resin composition onto a polyester non-woven fabric
Was fused and fixed to a prepreg to prepare a prepreg. This pre-pre
Paper honeycomb core (thickness: 15 mm, between two sheets)
Cell size: 14 mm) and heat plate temperature of 230 ℃
By heat treatment for 90 seconds in a molding press, the thickness
A 15 mm phenol resin foam was obtained. [Comparative Example 1] Obtained with the same formulation as shown in Example 1.
Novolac type phenolic resin 100 parts by weight, hexamer
Tylene tetramine 10 parts by weight, dinitroso as a foaming agent
Grind 7 parts by weight of pentamethylenetetramine with a grinder.
Phenol can be obtained by mixing each component evenly.
A resin composition was obtained. The particle size at this time is 10 to 70 μm
there were. Next, using this phenol resin-based composition,
Create a prepreg under the same conditions as in Example 1, and use this prepreg
A stack of two sheets is heated by a molding press with a hot plate temperature of 200 ° C.
The heat treatment for 60 seconds allows the 2.5 mm thick Fe
A nor resin type foam was obtained. Comparative Example 2 Phenol obtained in the same manner as Comparative Example 1
Using the resin composition, the prepreg was prepared in the same manner as in Example 2.
Created. Paper honey between two sheets of this prepreg
Cam core (thickness: 15 mm, cell size: 14 mm)
Scissors, hot plate temperature 200 ℃ for 90 seconds in a molding press
15mm thick phenol resin by heat treatment
A system foam was obtained. [Comparative Example 3] A novolac obtained in the same manner as in Example 1.
70 parts by weight phenolic resin, orthocresol novola
Type epoxy resin EOCN-103S (Nippon Kayaku Co., Ltd.
(Made by the company) 30 parts by weight, 10 parts by weight of 2-methylimidazole
Parts are pulverized with a pulverizer and each component is mixed uniformly.
Thus, a phenol resin composition was obtained. Grain at this time
The degree was 10 to 70 μm. Next, this phenol resin
Glass composition with glass chopped strand mat
Amount: 600g / m²), Spraying amount: 350 g / m²Tona
After spraying evenly, at 120 ℃ -150 ℃ for a few seconds
By carrying out heat treatment during
It is fused and fixed on the glass chopped strand mat and pressed.
I made a prepreg. When two prepregs are laminated
Was heat treated for 60 seconds in a molding press with a hot plate temperature of 230 ° C.
2.5 mm thick phenolic resin based
A foam was obtained. Sumps obtained in each Example and Comparative Example
Moldability, degree of cure, oxygen index, bending strength, immediately after molding
Formaldehyde and ammonia concentrations in the atmosphere
The determined results are shown in Table 1.

[Table 1] Evaluation method (1) Moldability Immediately after molding, the sample (250 mm square flat plate) was removed from the mold and immediately placed on two rods (diameter 10 mm) placed in parallel at 20 cm intervals. After natural cooling, the deflection at the center of the sample: χ is measured. (However, Example 2 and Comparative Example 2 are unmeasured due to the influence of the honeycomb core.) ◯: χ ≦ 0.5 mm ×: 0.5 mm <χ (2) Curing degree Using a Soxhlet extractor with acetone Extraction. It is shown by the ratio of the unextracted component in the resin. (3) Oxygen index According to JIS K 7201-72 flammability test method for polymer materials by oxygen index method. (4) Bending strength According to JIS K 7055 glass fiber reinforced plastic bending test method. (5) Concentration of formaldehyde and ammonia in the atmosphere Using a Kitagawa gas detector tube, before removing the sample immediately after molding from the mold, the central part of the sample (250 mm square flat plate),
Atmosphere gas was suctioned at a position 5 cm above the sample, and measurement was performed.

Industrial Applicability According to the present invention, it is possible to obtain a phenol resin-based foam capable of significantly reducing the emission amounts of formaldehyde and ammonia during molding without impairing the moldability and flame retardancy.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hironobu Koike, 700 Sukudaiji-cho, Takasaki-shi, Gunma Gunei Kagaku Kogyo Kogyo Co., Ltd. (72) Nobumasa Endo 700, Yado-machi, Takasaki-shi, Gunma Guneika Kogyo Co., Ltd. (56) Reference JP-A-10-53664 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08J 9/06 C08L 61 / 04,63 / 00-63 / 10 C08G 14 / 04,59 / 18

Claims (8)

(57) [Claims] 1. A novolac type phenolic resin, an epoxy resin, dinitrosopentamethylenetetramine, P, P'-
Phenolic resin obtained by heat treatment of a resin composition comprising one or more foaming agents of oxybisbenzenesulfonylhydrazone, hydrazodicarbonamide, P-toluenesulfonylhydrazide and azodicarbonamide Foam. 2. A novolac type phenol resin / epoxy resin blending ratio of the resin composition of 85/15 to 20 /
80 (weight ratio), and the blending ratio of the foaming agent is 1 to 10 parts by weight based on 100 parts by weight of the total resin amount of the novolac type phenol resin and the epoxy resin. The phenolic resin-based foam described. 3. A novolac type phenolic resin, an epoxy resin, dinitrosopentamethylenetetramine, P, P'-
What is obtained by heat-treating a powdery phenolic resin composition comprising one or more blowing agents of oxybisbenzenesulfonylhydrazone, hydrazodicarbonamide, P-toluenesulfonylhydrazide and azodicarbonamide. Characteristic phenolic resin foam. 4. The resin composition has a novolac type phenol resin / epoxy resin blending ratio of 85/15 to 20.
/ 80 (weight ratio), and the compounding ratio of the foaming agent is 1 to 10 parts by weight based on 100 parts by weight of the total resin amount of the novolac type phenol resin and the epoxy resin. The phenolic resin-based foam according to item 3. 5. A novolac-type phenol resin, an epoxy resin, dinitrosopentamethylenetetramine, P, P'-
Production of a phenolic resin-based foam characterized by using a resin composition comprising one or more foaming agents of oxybisbenzenesulfonylhydrazone, hydrazodicarbonamide, P-toluenesulfonylhydrazide and azodicarbonamide Method. 6. The novolac-type phenol resin / epoxy resin blending ratio of the resin composition is 85/15 to 20 /
It is 80 (weight ratio), and the compounding ratio of the foaming agent is 1 to 10 parts by weight with respect to 100 parts by weight of the total resin amount of the novolac type phenol resin and the epoxy resin. A method for producing a phenolic resin-based foam as described. 7. A novolac-type phenol resin, an epoxy resin, dinitrosopentamethylenetetramine, P, P'-
Powdering a phenolic resin composition comprising one or more blowing agents of oxybisbenzenesulfonylhydrazone, hydrazodicarbonamide, P-toluenesulfonylhydrazide, azodicarbonamide, and powdering A method for producing a phenol resin-based foam, comprising: a step of spraying the phenol resin-based composition in a planar shape; and a step of heat-treating the phenol resin-based composition sprayed in a planar shape. 8. The resin composition has a novolac type phenol resin / epoxy resin blending ratio of 85/15 to 20.
/ 80 (weight ratio), and the compounding ratio of the foaming agent is 1 to 10 parts by weight based on 100 parts by weight of the total resin amount of the novolac type phenol resin and the epoxy resin. 7. The method for producing a phenolic resin-based foam according to 7.