JP5525852B2 - Thermosetting resin composition and cured product thereof - Google Patents

Description

  The present invention relates to a thermosetting resin composition containing benzoxazine and a cured product thereof.

  Benzoxazine is a compound obtained by reaction of amines, phenols and aldehydes. Since such benzoxazine is cured without generating a volatile by-product, it is attracting attention as a molding material in place of a phenol resin or an epoxy resin, particularly in the field of electronic / electric equipment materials.

In addition, a cured product of benzoxazine is useful as a building material or a structural material because it is excellent in heat resistance and flame retardancy.
For example, Patent Document 1 discloses a composition containing a benzoxazine component, a curing agent, and the like as being suitable for a building material.
Here, paragraph [0022] of Patent Document 1 shows aliphatic dicarboxylic acids such as adipic acid, sebacic acid, maleic acid, succinic acid, and fumaric acid, aromatic dicarboxylic acids such as benzoic acid, and the like as curing agents. Has been.

JP-A-11-279310

By the way, the curing rate of benzoxazine is not always satisfactory as compared with conventional phenol resins and epoxy resins. For this reason, when the present inventor studied by applying the curing agent disclosed in Patent Document 1 to benzoxazine, it was found that the curing rate was still insufficient.
Then, an object of this invention is to provide the thermosetting resin composition containing the benzoxazine excellent in the cure rate.

As a result of intensive studies to solve the above problems, the present inventor has found that the composition containing benzoxazine, a phenol resin, and biphenyltetracarboxylic acids and / or anhydrides thereof has an excellent curing rate. The headline and the present invention were completed.
That is, the present invention provides the following (1) to (3).

( 1 ) benzoxazine (A), phenol resin (B), and biphenyltetracarbo
Acids and / or anhydrides thereof (C),
The mass ratio (A / B) between the benzoxazine (A) and the phenol resin (B) is 5/95 to 95/5, and the total of the benzoxazine (A) and the phenol resin (B) per 100 parts by mass, the biphenyltetracarboxylic acids and / or anhydrides (C) a thermosetting resin composition you containing 0.1-10 parts by weight.

( 2 ) A cured product obtained by curing the thermosetting resin composition according to (1) above.

  ADVANTAGE OF THE INVENTION According to this invention, the thermosetting resin composition containing the benzoxazine excellent in the cure rate can be provided.

It is a graph which shows the relationship between hardening time and a hardening rate.

<Thermosetting resin composition>
The thermosetting resin composition of the present invention (hereinafter also referred to as “the composition of the present invention”) includes benzoxazine (A), a phenol resin (B), biphenyltetracarboxylic acids and / or anhydrides thereof ( C) and a thermosetting resin composition.
Below, each component contained in the composition of this invention is explained in full detail.

(Benzoxazine (A))
The benzoxazine (A) is a compound having at least one benzoxazine ring in one molecule.
The benzoxazine (A) has a benzoxazine ring at least in one molecule because the molecular weight of the cured product obtained by curing the composition of the present invention tends to be high, and the mechanical strength and heat resistance are improved. It is preferable to have two. Examples of the benzoxazine (A) having at least two benzoxazine rings in one molecule include compounds represented by the following formula (A1) and the following formula (A2).

  In the above formula (A1), X represents an alkylene group, an aralkylene group, a phenylene group, a cyclohexylene group, a phenylene group having an alkyl group or an alkoxy group as a substituent, an alkylene group having a substituent, or the following formula (X- The group represented by 1) is shown.

In the above formula (X-1), Y represents oxygen, an alkylene group, or an alkylene group having a substituent.
Examples of the benzoxazine (A) represented by the above formula (A1) and wherein X in the above formula (A1) is represented by the above formula (X-1) include, for example, the following formula (A1-1), Examples thereof include compounds represented by (A1-2) and (A1-3).

In the above formula (A2), R represents an alkyl group; an aralkyl group; a phenyl group; a cyclohexyl group; a phenyl group having an alkyl group, an alkoxy group, or an alkenyl group as a substituent; or an alkyl group having a substituent; Among them, from the viewpoint of high heat resistance, a phenyl group having a substituent and an alkyl group having a substituent are preferable.
In the above formula (A2), Z represents a single bond, oxygen, an alkylene group, an alkylene group having a substituent, or a sulfonyl group.
Examples of the benzoxazine (A) represented by the formula (A2) include compounds exemplified in paragraph [0016] of Patent Document 1, and specific examples thereof include the following formula (A2-1), The compound etc. which are represented by (A2-2) are mentioned.

  The method for producing the benzoxazine (A) is not particularly limited, and examples thereof include a method of reacting a diamine compound, a phenol, and an aldehyde, a method of reacting a bisphenol, a primary amine, and an aldehyde. It is done.

Examples of the diamine compound used in the production of the benzoxazine (A) include 4,4′-oxydianiline; 4,4′-methylenedianiline; paradiaminobenzene; alkyl group, alkoxy group, halogen, and aromatic. These compounds substituted with a hydrocarbon group or the like;
Among these, 4,4′-oxydianiline is preferable because the cured product obtained by curing the composition of the present invention is excellent in heat resistance and flame retardancy.

Examples of the phenols used in the production of the benzoxazine (A) include phenol; cresols such as ortho-cresol; xylenols; naphthols; alkyl groups, alkoxy groups, halogens, aromatic hydrocarbon groups and the like. These compounds may be used, and these may be used alone or in combination of two or more.
Of these, phenol and cresol are preferred because they are inexpensive and have low viscosity and excellent moldability.

Examples of aldehydes used in the production of the benzoxazine (A) include paraformaldehyde, formalin (formaldehyde aqueous solution) and the like. These may be used alone or in combination of two or more. Good.
Of these, paraformaldehyde is preferred because of its high reactivity.

Examples of the bisphenols used in the production of the benzoxazine (A) include bisphenol A, bisphenol F, bisphenol S, etc., and these may be used alone or in combination of two or more. Good.
Of these, bisphenol A is preferred because it is inexpensive and has excellent heat resistance.

Examples of the primary amine used in the production of the benzoxazine (A) include aniline, aniline substituted with an alkyl group, alkoxy group, halogen, etc., and these may be used alone. In addition, two or more kinds may be used in combination.
Of these, aniline is preferred because it is inexpensive.

(Phenolic resin (B))
The phenol resin (B) is a thermosetting resin obtained by condensing phenols and aldehydes.
When the composition of the present invention contains the phenol resin (B), the curing rate is improved. This is because the hydroxyl group in the phenol resin functions as a curing catalyst.
In the composition of the present invention, the phenol resin (B) may be present as a compound in combination with the benzoxazine (A).

Examples of the phenols used in obtaining the phenol resin (B) include phenols used in the production of the benzoxazine (A), and these may be used alone or in combination of two or more. May be.
Of these, phenol and cresols are preferable because of excellent molding processability.

Examples of aldehydes used in obtaining the phenol resin (B) include aldehydes used in the production of the benzoxazine (A), and these may be used alone or in combination of two or more. May be.
Of these, paraformaldehyde is preferred because of its high reactivity.

(Biphenyltetracarboxylic acids and / or anhydrides thereof (C))
The said biphenyl tetracarboxylic acid and / or its anhydride (C) are the concept containing any one or both of biphenyl tetracarboxylic acid and its anhydride.
The composition of this invention containing the said benzoxazine (A) is excellent in a cure rate by containing the said biphenyl tetracarboxylic acid and / or its anhydride (C). This is because the catalytic effect of the hydroxyl group and acid anhydride group contained is high.

Biphenyltetracarboxylic acids and anhydrides thereof are classified into a symmetric type and an asymmetric type, and either one may be used alone, or a mixture of both may be used.
Specific examples of the symmetric type include 3,3 ′, 4,4′-biphenyltetracarboxylic acid represented by the following formula (c-1); 3,3 ′, represented by the following formula (c-3). 4,4′-biphenyltetracarboxylic dianhydride; these compounds substituted with an alkyl group, an alkoxy group, halogen, or the like;
Specific examples of the asymmetric type include 2,3,3 ′, 4′-biphenyltetracarboxylic acid represented by the following formula (c-2); 2,3,3 represented by the following formula (c-4) ', 4'-biphenyltetracarboxylic dianhydride; these compounds substituted with an alkyl group, an alkoxy group, halogen, and the like; and the like.

(Content)
The content of each component in the composition of the present invention is not particularly limited, but the mass ratio (A / B) of the benzoxazine (A) to the phenol resin (B) is 5/95 to 95/5. It is preferable that the ratio is 10/90 to 90/10.
Moreover, it is 0.1-10 mass parts of said biphenyl tetracarboxylic acids and / or its anhydride (C) with respect to a total of 100 mass parts of said benzoxazine (A) and said phenol resin (B). Preferably, the content is 0.2 to 5.0 parts by mass.
When the content of each component is within this range, the curing rate of the composition of the present invention is more excellent, and the heat resistance and flame retardancy of the cured product obtained by curing the composition of the present invention are excellent.

(Other additives)
The composition of the present invention can contain other additives as long as the object of the present invention is not impaired. Examples of other additives include foaming agents, surfactants, fillers, antioxidants, heat stabilizers, antistatic agents, plasticizers, pigments, dyes, colorants, flame retardants, and coupling agents.
Examples of the blowing agent include hydrocarbons such as n-pentane and isopentane; chlorinated hydrocarbons such as chloroform and methylene chloride; trichlorofluoromethane, 1,1,2-trichloro-1,2,2-trifluoroethane and the like. And the like, and the like.
Examples of the surfactant include nonionic surfactants, fatty acid esters, silicone compounds, polyalcohols, and the like.
Examples of fillers include metal hydroxides such as aluminum hydroxide, carbonates such as calcium carbonate, silicates such as calcium silicate, carbon black, silica, alumina, barium titanate, talc, mica, clay, and glass beads. , Glass hollow sphere, glass fiber, carbon fiber and the like.

(Production method)
The method for producing the composition of the present invention is not particularly limited. For example, a predetermined amount of a diamine compound, a phenol, an aldehyde, and the biphenyltetracarboxylic acid and / or its anhydride (C) are not used. Examples include a method of reacting at 100 to 150 ° C. in an active solvent and further heating to distill the solvent. Use of this production method is preferable because the phenol resin (B) is produced together with the benzoxazine (A).

<Hardened product of thermosetting resin composition>
The cured product of the thermosetting resin composition of the present invention (hereinafter also referred to as “cured product of the present invention”) is a cured product obtained by curing the above-described composition of the present invention.
150-350 degreeC is preferable and the curing temperature at the time of hardening the composition of this invention has more preferable 180-300 degreeC. Further, the curing time at that time is preferably 10 minutes to 5 hours, and more preferably 30 minutes to 2 hours.
When the curing temperature and the curing time are within this range, the cured product of the present invention is more excellent in heat resistance and flame retardancy.

  The composition of the present invention and the cured product of the present invention are suitably used for applications such as building materials, structural materials, automotive parts, mechanical parts, and electronic / electric equipment materials.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

<Examples 1-7, Comparative Examples 1-3>
Example 1
105 g of 4,4′-oxydianiline, 69 g of paraformaldehyde, 2.73 g of symmetric 3,3 ′, 4,4′-biphenyltetracarboxylic acid, and 100 g of toluene as a solvent were separated into 2 liters of separable liquid. Added to flask and heated to 90 ° C. After the heating, 99 g of phenol heated to 90 ° C. in advance was added, and further heated to 110 ° C. for 3 hours. Thereafter, the temperature was raised to 170 ° C. and toluene as a solvent was distilled under reduced pressure to obtain 220 g of a thermosetting resin composition (hereinafter also simply referred to as “composition”).
The obtained composition was cured by heating at 200 ° C. for 1 hour, and further cured by heating at 250 ° C. for 1 hour to obtain a cured product having a thickness of about 1 mm.

(Example 2)
The same as Example 1 except that an asymmetrical 2,3,3 ′, 4′-biphenyltetracarboxylic acid was used instead of the symmetric 3,3 ′, 4,4′-biphenyltetracarboxylic acid. Thus, a composition and a cured product were obtained.
(Example 3)
Except for using 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride instead of symmetric 3,3 ′, 4,4′-biphenyltetracarboxylic acid A composition and a cured product were obtained in the same manner as in Example 1.
Example 4
Examples were used except that an asymmetrical 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride was used instead of the symmetrical 3,3 ′, 4,4′-biphenyltetracarboxylic acid. In the same manner as in No. 1, a composition and a cured product were obtained.
(Example 5)
A composition and a cured product were obtained in the same manner as in Example 1 except that 4,4′-methylenedianiline was used instead of 4,4′-oxydianiline.
(Example 6)
A composition and a cured product were obtained in the same manner as in Example 1 except that ortho-cresol was used instead of phenol.

(Example 7)
A composition and a cured product were obtained in the same manner as in Example 1 except that 5.3 g of phenol was used instead of 99 g of phenol.

(Comparative Example 1)
A composition and a cured product were obtained in the same manner as in Example 1 except that 3,3 ′, 4,4′-biphenyltetracarboxylic acid was not used.
(Comparative Example 2)
A composition and a cured product were obtained in the same manner as in Example 1 except that benzoic acid was used instead of 3,3 ′, 4,4′-biphenyltetracarboxylic acid.
(Comparative Example 3)
A composition and a cured product were obtained in the same manner as in Example 1 except that maleic anhydride was used in place of 3,3 ′, 4,4′-biphenyltetracarboxylic acid.

<Measurement of physical properties>
(Content)
About the obtained composition, content [mass%] of the benzoxazine (A) and the phenol resin (B) was calculated | required from the peak area of RI detector using GPC (gel permeation chromatography). The results are shown in Table 1.
(Remaining charcoal rate)
About the obtained composition, the residual carbon ratio [%] at the time of heating up from room temperature to 800 degreeC in the air was calculated | required from the TGA (thermal weight loss) curve. The higher the residual carbon ratio, the better the flame retardancy. The results are shown in Table 1.
(Glass-transition temperature)
The obtained sheet-like cured product was cut into a size of 5 mm × 30 mm and then subjected to TMA (thermomechanical analysis), and the glass transition temperature [° C.] was determined from the inflection point of the linear expansion coefficient. The higher the glass transition temperature, the better the heat resistance. The results are shown in Table 1.
(Curing rate)
About the obtained composition (uncured sample), the curing temperature was set to 250 ° C., and a cured sample (cured sample) was prepared by changing the curing time in various ways, and DSC measurement was performed to generate heat from the area of the exothermic peak. The amount was measured. The curing rate [%] at a predetermined curing time was calculated from the following formula. The relationship between the curing time and the curing rate is shown in FIG.
Curing rate [%] = {(calorific value of uncured sample−calorific value of cured sample) / calorific value of uncured sample} × 100

From the graph of FIG. 1, it was found that the curing rates of the compositions of Examples 1 to 7 were significantly faster than the curing rates of the compositions of Comparative Examples 1 to 3.
In addition, from the results shown in Table 1, Examples 1 to 7 have a high residual carbon ratio and excellent flame retardancy as compared with Comparative Examples 1 to 3, and also have a high glass transition temperature and excellent heat resistance. I found out.

  Furthermore, it turned out that Examples 1-6 are more excellent in the cure rate of a composition compared with Example 7, and are also excellent in the heat resistance and flame retardance of hardened | cured material.

Claims (2)

Benzoxazine (A),
Phenolic resin (B),
Biphenyltetracarboxylic acids and / or anhydrides thereof (C);
Containing
The mass ratio (A / B) of the benzoxazine (A) and the phenol resin (B) is 5/95 to 95/5,
Per 100 parts by weight of the benzoxazine (A) and the phenolic resin (B), wherein the biphenyltetracarboxylic acid and / or anhydride thereof (C) a thermosetting you contain 0.1 to 10 parts by weight Resin composition. A cured product obtained by curing the thermosetting resin composition according to claim 1 .