JPH08183855A - Thermosetting resin composition and cured material thereof - Google Patents

Abstract

PURPOSE: To obtain a thermosetting resin composition excellent in heat resistance and flame retardancy by using a thermosetting resin having dihydrobenzoxazine rings and a phenolic resin. CONSTITUTION: This composition consists of a thermosetting resin having dihydrobenzoxazine rings, preferably in an amount of 30-97wt.%, and a phenolic resin preferably in an amount of 3-70wt.%. The thermosetting resin has structural units of formula I and those of formula II (wherein R<1> is methyl or phenyl) at a molar ratio of (1:0.25) to (1:9), wherein the structural units are bound to one another directly or through an organic group. It is more desirable that the phenolic resin comprises a novolak or resol phenolic resin. The hydrogen atoms directly bound to the aromatic rings of the structural units of formula I and those of formula II may be substituted by any substituent.

Description

Detailed Description of the Invention

[0001]

[Industrial field of application] The present invention is a highly functional molding material, paint, coating material, adhesive, which has excellent heat resistance and flame retardancy.
The present invention relates to a dihydrobenzoxazine-based thermosetting resin composition used as a sealing material, a laminated plate, an FRP and a raw material for carbon products.

[0002]

Thermosetting resins such as phenolic resins, melamine resins, epoxy resins, unsaturated polyester resins and bismaleimide resins are used in many industrial fields due to their heat resistance and reliability due to their thermosetting properties. Has been. However, phenolic resins and melamine resins generate volatile by-products during curing, epoxy resins and unsaturated polyester resins have poor flame retardancy, and bismaleimide resins are very expensive. However, in reality, it is appropriately compromised depending on the application. Therefore,
The development of new thermosetting resins that do not have these drawbacks has been progressing from the past.

One of them is a dihydrobenzoxazine compound (see JP-A-49-47387 and US Pat. No. 5,152,939). Since the curing of this compound utilizes the ring-opening polymerization reaction of the dihydrobenzoxazine ring, it is thermally cured with almost no generation of volatile components.

[0004]

This ring-opening polymerization reaction has the drawback that it takes a longer time to cure than the ordinary phenol resin curing reaction, and its industrial use is limited in terms of productivity. The problem is also known. Attempts have been made to add a curing agent to solve this problem, but they have not been put to practical use such as deterioration of mechanical properties and generation of volatile components due to decomposition of the residual curing agent.

An object of the present invention is to provide a thermosetting resin composition having a dihydrobenzoxazine ring having improved curability without deteriorating various properties such as deterioration of mechanical properties, and a cured product thereof. .

[0006]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that a thermosetting resin having a dihydrobenzoxazine ring can be used as a curing agent by using a phenol resin as a curing agent. The inventors have found that the curability can be improved without deteriorating various characteristics such as characteristics, and have completed the present invention.

That is, the present invention provides a thermosetting resin composition comprising a thermosetting resin having a dihydrobenzoxazine ring and a phenol resin.

The mixing ratio of the thermosetting resin having a dihydrobenzoxazine ring and the phenol resin is preferably 30 to 97% by weight of the thermosetting resin having a dihydrobenzoxazine ring and 3 to 70% by weight of the phenol resin.

The thermosetting resin having a dihydrobenzoxazine ring is a structural unit A represented by the following formula (A).
And a structural unit B represented by the following formula (B), and the molar ratio (A / B) of the structural unit A and the structural unit B is 1 / 0.25 to
It is 1/9, and a resin in which each structural unit is bonded directly or via an organic group is preferably used.

[0010]

Embedded image (However, R ¹ is a methyl group, a cyclohexyl group, a phenyl group or a substituted phenyl group such as a methyl-substituted alkyl-substituted methoxy group, a structural unit A and a structural unit B
The hydrogen of the aromatic ring of may be substituted with any substituent except one of the ortho positions of the hydroxyl group of the structural unit A. The number of each structural unit is not particularly limited, but the number of structural units (A) contained in one molecule is m, and the number of structural units (B) is n.
Then, m ≧ 1, n ≧ 1, and 10 ≧ m + n ≧ 2 are preferable, and 10 ≧ m + n ≧ 3 is more preferable.

The reason for this is that if a suitable chain length is previously formed between the structural units (A) and (B) by a stable bond, the properties of the cured product will be good.

Each structural unit may be directly bonded or may be bonded via an organic group. Examples of the organic group include an alkylene group and a xylylene group, and examples of the alkylene group include a group represented by the following formula (C) and a long-chain alkylene group having 5 or more carbon atoms.

[0013]

[Chemical 4] (However, R ² represents hydrogen, a methyl group, an ethyl group, a propyl group, an isopropyl group, a phenyl group or a substituted phenyl group such as a methyl-substituted alkyl-substituted methoxy group.) The thermosetting resin composition of the present invention The thermosetting resin having a dihydrobenzoxazine ring is a compound having two or more hydroxyphenylene groups in which at least one ortho-position of a hydroxyl group is hydrogen in one molecule, a primary amine and formaldehydes. Reaction of primary amine in an amount of 0.2 to 0.9 mol, and formaldehydes in a molar ratio of at least twice as much as the primary amine, relative to 1 mol of a hydroxyl group in which at least one of the ortho positions of the hydroxyphenylene group is hydrogen. It is manufactured by

Specifically, a compound having two or more hydroxyphenylene groups in which at least one ortho-position of a hydroxyl group is hydrogen in one molecule (hereinafter, referred to as a compound having a reactive hydroxyphenylene group) and 1
The mixture with the primary amine is added to formaldehydes heated to 70 ° C. or higher, and the reaction is performed at 70 to 110 ° C., preferably 90 to 100 ° C. for 20 minutes to 2 hours, and then the temperature is 120 ° C. or lower. The desired thermosetting resin is obtained by drying under reduced pressure.

The primary amine is reacted in an amount of 0.2 to 0.9 mol, and the formaldehydes are reacted in a ratio of at least twice the molar amount of the primary amine, relative to 1 mol of the hydroxyl group of the compound having a reactive hydroxyphenylene group. It is essential to let them do it. When the amount of the primary amine is less than 0.2 mol, the number of dihydrobenzoxazine rings will be small, so that when the obtained thermosetting resin is cured, only a cured product having a low crosslink density and a low strength can be obtained. . Further, if it exceeds 0.9 mol, the behavior becomes similar to the conventionally known dihydrobenzoxazine compound, which is not preferable.

The blending amount of the primary amine with respect to the compound having a reactive hydroxyphenylene group can be determined as follows. That is, 1 mol of the same molar amount as the total hydroxyl amount of the compound having a hydroxyphenylene group
The amount of the reacted hydroxyl group, that is, the amount of the reactable hydroxyl group in the compound having a hydroxyphenylene group is estimated from the weight of the product actually obtained by reacting the primary amine, and calculated as the above molar ratio. To do.

As the compound having two or more reactive hydroxyphenylene groups in one molecule, various compounds partially having a phenol nucleus can be used. Specifically, phenol novolac resin, resol resin, phenol-modified xylene resin, alkylphenol resin,
Examples include melamine phenol resin and phenol-modified polybutadiene. These are not particularly limited, but those in which the ortho position of the hydroxyl group serving as a crosslinking point is unsubstituted are desirable in terms of curing characteristics. Therefore, for example, in the case of phenol novolac resin, the ortho ratio is small and the ortho position is relatively low. It is preferred to use small so-called random novolacs.

The above-mentioned resin is a set of compounds having different numbers of hydroxyphenylene groups capable of reacting in one molecule, and a part of the thermosetting compound produced during the production is polymerized with each other. Therefore, the obtained thermosetting compound of the present invention is
It is an aggregate of compounds in which m and n are different. Isolation of compounds with different m and n is currently not possible.

Specific examples of primary amines include substituted anilines such as methylamine, cyclohexylamine, aniline, toluidine and anisidine.

When the aliphatic amine is used, the resulting thermosetting resin having a dihydrobenzoxazine ring cures quickly, but the heat resistance of the cured product is slightly inferior, and when it is an aromatic amine such as aniline, it is obtained. The heat resistance of the cured product obtained by curing the thermosetting compound is good, but the curing is slow.

The thermosetting resin having a dihydrobenzoxazine ring is 150 ° C. or higher, preferably 170 to
By heating to 220 ° C., curing is performed without using a catalyst or a curing agent and without producing a by-product.

Two or more of these thermosetting resins having a dihydrobenzoxazine ring can be used in combination. Further, a thermosetting resin having these polyfunctional dihydrobenzoxazine rings is previously added to 80 to 180
It is also possible to pre-polymerize a part of the mixture by treating at a temperature of 120 ° C., preferably 120 to 160 ° C. to control the curing rate and melt viscosity during molding.

As the phenol resin, novolac resin and resol resin can be used. Examples of novolac resins include phenol novolac resins, bisphenol novolac resins, phenol-modified xylene resins, and alkylphenol resins. Examples of the resole resin include liquid, solid resole, dimethylene ether type resole, and methylol type resole.

When a novolac resin is used, mechanical properties may be deteriorated as compared with the case of using a thermosetting resin having a dihydrobenzoxazine ring alone. Therefore, it is preferable to use a resole resin. By using a solid dimethylene ether type resole resin among the resole resins, curability can be improved without lowering mechanical properties.

If the amount of the phenol resin such as dimethylene ether type resole resin added is less than 3% by weight, it becomes difficult to improve the curability. If it exceeds 70% by weight, the curability is difficult to improve and the mechanical properties may deteriorate.
By setting the addition amount of the phenol resin to 3 to 70% by weight, curability can be improved without deteriorating various characteristics such as mechanical characteristics.

If desired, a curing agent for phenol resin such as hexamethylenetetramine or calcium hydroxide can be used.

The thermosetting resin having a dihydrobenzoxazine ring and the phenol resin may be finely pulverized with a mixer or the like and then powder-mixed, but it is preferable to melt-mix with a heating roll or the like.

If desired, a filler, a reinforcing fiber, a coloring agent, an adhesive agent, etc. may be added to the above composition.

[0029]

The present invention provides the above resin composition and a cured product thereof. By using a resin composition of a thermosetting resin having a dihydrobenzoxazine ring and a phenol resin, the curability is improved as compared with a thermosetting resin having a dihydrobenzoxazine ring alone, and the mechanical properties and flame retardancy are good. A cured product can be obtained. These are 180 to 220 after kneading the above resin composition by a heating roll or the like.
It is obtained by pressure molding or transfer molding for 3 to 10 minutes at a molding temperature of 20 to 70 kgf / cm ² at 180 ° C.
By curing at 220 ° C. for 5 to 120 minutes, a cured product having better properties can be obtained.

[0030]

EXAMPLES Specific examples of the present invention are shown below, but the present invention is not limited thereto.

Examples 1 to 11 and Comparative Examples 1 to 5 Synthesis of thermosetting resin having dihydrobenzoxazine ring (I) (1) Synthesis of phenol novolac resin 1.9 kg of phenol, formalin (37% aqueous solution)
1.15 kg and 4 g of oxalic acid were charged in a 5 liter flask and reacted at reflux temperature for 6 hours. Subsequently, the inside pressure was reduced to 6666.1 Pa or less to remove unreacted phenol and water. The obtained resin had a softening point of 89 ° C. (ring and ball method) and a 3-polyhedron / 2 nucleus ratio of 89/11 (peak area ratio by gel permeation chromatography).

(2) Introduction of dihydrobenzoxazine ring Phenol novolac resin 1.7k synthesized above
aniline 0.9 g (corresponding to 16 mol of hydroxyl group)
The mixture was mixed with 3 kg (corresponding to 10 mol) and stirred at 80 ° C. for 5 hours to prepare a uniform mixed solution. Into a 5 liter flask, charge 1.62 kg of formalin and heat to 90 ° C.
The novolak / aniline mixed solution was added little by little over 30 minutes. After the completion of the addition, the reflux temperature was maintained for 30 minutes, and then the water of condensation was removed by reducing the pressure to 6666.1 Pa or less at 100 ° C. for 2 hours to remove 75% of the reactive hydroxyl groups. A thermosetting resin having an oxazine ring was obtained.

Synthesis of dihydrobenzoxazine compound (II) (1) Synthesis of phenol novolac resin 1.9 kg of phenol, formalin (37% aqueous solution)
1.10 kg and 4 g of oxalic acid were charged into a 5 liter flask, and a phenol novolac resin was synthesized in the same manner as in the synthesis (I) of dihydrobenzoxazine compound. The obtained resin had a softening point of 84 ° C. (ring and ball method) and a ratio of 3 to polynuclear bodies / 2 binuclear bodies of 82/18 (peak area ratio by gel permeation chromatography). (2) Introduction of dihydrobenzoxazine ring A dihydrobenzoxazine ring was introduced in the same manner as in Synthesis (I) of thermosetting resin having a dihydrobenzoxazine ring. The resulting thermosetting resin composition has 71% of the reactive hydroxyl groups of the phenol novolac resin.
% Of which a dihydrobenzoxazine ring was introduced.

Synthesis of Thermosetting Resin Having Dihydrobenzoxazine Ring (III) 1.70 kg of xylylene-modified phenolic resin (trade name Milex XL-225-3L manufactured by Mitsui Toatsu Chemicals, Inc.)
(Equivalent to hydroxyl group 10 mol), aniline 0.52
kg (5.6 mol), formalin (37% aqueous solution)
A thermosetting resin having a dihydrobenzoxazine ring introduced into 71% of hydroxyl groups capable of reacting in the same manner as in the above-mentioned synthetic method was synthesized with a composition of 0.91 kg.

Synthesis of dimethylene ether type resole resin 2 kg phenol, formalin (37% aqueous solution) 0.3
8 kg and 0.78 kg of paraformaldehyde were charged into a 5 liter flask and reacted at a reflux temperature for 6 hours. Subsequently, the inside pressure was reduced to 6666.1 Pa or less, and unreacted phenol and water were removed by steam distillation. The obtained resin had a softening point of 77 ° C.

Synthesis of phenol novolac resin 1.9 kg phenol, formalin (37% aqueous solution)
1.15 kg and 4 g of oxalic acid were charged in a 5 liter flask and reacted at reflux temperature for 6 hours. Subsequently, the inside pressure was reduced to 6666.1 Pa or less to remove unreacted phenol and water. The obtained resin had a softening point of 84 ° C. (ring and ball method) and a ratio of 3 to polynuclear bodies / 2 binuclear bodies of 82/18 (peak area ratio by gel permeation chromatography).

Phenol resin was charged into a flask, and 11
The resin was dissolved by heating to 0 to 120 ° C., a thermosetting resin having a dihydrobenzoxazine ring was added thereto, and the mixture was stirred for 10 minutes until it became uniform.

A resin composition prepared by mixing the above resins in the ratios shown in Tables 1 and 2 was crushed, filled in a mold having an inner diameter of 120 × 80 × 4 mm, and heated and pressed at 180 ° C. and 1.96 MPa for 10 minutes. A cured product was produced. Regarding the characteristics of the resin composition, the gel time was the time until the stringing disappeared by continuously stirring 0.3 g of the resin composition on the gel timer heated at 180 ° C. once / second.

The characteristics of the cured product are bending strength and bending elastic modulus according to JIS K6911, 23 ° C., bending speed 2 mm /
Evaluated in minutes. Flame retardance is based on UL-94,
Evaluation was made with a thickness of 3.6 mm.

The results are shown in 3-6 below.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

[Table 3]

[0044]

[Table 4]

[0045]

[Table 5]

[0046]

[Table 6]

[0047]

The thermosetting resin composition of the present invention is fast-curing, and the cured product has good mechanical properties and flame retardancy. Therefore, the thermosetting resin composition of the present invention is a highly functional molding material, paint, coating material, adhesive, sealing material,
It is useful as a laminated plate, FRP, and raw material for carbon products.

Claims (10)

[Claims] 1. A thermosetting resin composition comprising a thermosetting resin having a dihydrobenzoxazine ring and a phenol resin. 2. A thermosetting resin having a dihydrobenzoxazine ring in an amount of 30 to 97% by weight and a phenol resin in an amount of 3%.
The thermosetting resin composition according to claim 1, which comprises ˜70% by weight. 3. A thermosetting resin having a dihydrobenzoxazine ring has a structural unit A represented by the following formula (A) and a structural unit B represented by the following formula (B). The molar ratio (A / B) of the unit B is 1 / 0.25 to 1/9
The thermosetting resin composition according to claim 1 or 2, wherein each structural unit is a resin bonded directly or via an organic group, and the phenol resin is a novolac type or resol type phenol resin. Embedded image (However, R ¹ is a methyl group, a cyclohexyl group, a phenyl group or a substituted phenyl group, and hydrogen of the aromatic ring of the structural unit A and the structural unit B excludes one of the ortho positions of the hydroxyl group of the structural unit A. , May be substituted with any substituent.) 4. The thermosetting resin having a dihydrobenzoxazine ring according to claim 3, wherein m ≧ 1, n ≧ 1 and 10 ≧ m, where m is the number of structural units A and n is the number of structural units B.
The thermosetting resin composition according to claim 3, wherein + n ≧ 2. 5. Structural unit A and structural unit B of thermosetting resin
The thermosetting resin composition according to claim 3, wherein is bonded via an alkylene group. 6. A thermosetting resin structural unit A and structural unit B
The thermosetting resin composition according to claim 3, wherein is bonded via a group represented by the following formula (C). Embedded image (However, R ² represents hydrogen, a methyl group, an ethyl group, a propyl group, an isopropyl group, a phenyl group or a substituted phenyl group.) 7. A thermosetting resin structural unit A and structural unit B
The thermosetting resin composition according to claim 3, wherein is bonded via a xylylene group. 8. The thermosetting resin composition according to claim 1, wherein the phenol resin is a resol type phenol resin. 9. The thermosetting resin composition according to claim 1, wherein the resol type phenol resin is a dimethylene ether type resol resin. 10. A cured product obtained by curing the thermosetting resin composition according to claim 1.