JP2003206390A - Thermosetting resin composition and its cured item - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermosetting resin composition which contains a thermosetting resin having dihydrobenzoxazine rings, has a curability improved without degrading mechanical properties, and is used as a raw material for a highly functional molding material, a coating material, an adhesive, a sealing agent, a prepreg for a printed circuit board, a metal-clad laminate, an FRP, a carbon product, etc., excellent in heat resistance, flame retardance, etc. <P>SOLUTION: This thermosetting resin composition comprises 5-30 wt.% thermosetting resin having dihydrobenzoxazine rings and 70-95 wt.% novolak phenol resin. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a high-performance molding material excellent in heat resistance, flame retardancy, etc., paint, coating material, adhesive, sealing material, prepreg for printed wiring board, metal-clad laminate,
The present invention relates to a thermosetting resin composition used as a raw material for FRP and carbon products, and a cured product thereof.

[0002]

2. Description of the Related Art Thermosetting resins such as phenolic resins, melamine resins, epoxy resins, unsaturated polyester resins, and bismaleimide resins are used in many industrial fields because of their heat resistance and reliability due to their thermosetting properties. It is used. However, phenolic resins and melamine resins generate volatile by-products during curing, epoxy resins and unsaturated polyester resins have poor heat resistance, and bismaleimide resins are very expensive. However, in reality, it was necessary to appropriately compromise the problems depending on the application. Therefore, the development of a new thermosetting resin that does not have these problems has been promoted.

One of them is a dihydrobenzoxazine compound (JP-A-49-47387, 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.

Further, as a study on the curability and reactivity of these resins, J. Am. Chem. Soc. Three
Burke et al., 424 (1965), Poly.
m. Sci. Technol. 27 (1985) R
There is a document by Jess et al. In addition, JP-A-7-18836
JP-A No. 4-2004 describes a dihydrobenzoxazine compound in which curability is improved by leaving a phenolic hydroxyl group in a specific ratio without cyclization when the phenolic hydroxyl group in the molecule is dihydrobenzoxazinated. Has been done.

[0005]

Problems to be Solved by the Invention JP-A-49-4738
The cured product of the dihydrobenzoxazine compound utilizing the ring-opening polymerization reaction described in JP-A No. 7 has good heat resistance and high strength as compared with conventionally known thermosetting resins. However, the curing by the ring-opening polymerization reaction has a drawback that it takes a longer time than the curing by the ordinary curing reaction of a phenol resin, and there is also a problem that industrial applications are limited in terms of productivity. There is.

Further, as described in JP-A No. 7-188364, when a phenolic hydroxyl group is left in the molecule at a certain ratio during dihydrobenzoxazine formation, the dihydrobenzoxazine compound obtained is It has been confirmed that the curability can be improved, but there is a problem that it is difficult to perform stable synthesis because the ring-opening reaction proceeds due to heating during the synthesis of this compound.

Further, Burke and Riess et al. Describe an example of study of curability when a monofunctional phenol compound is used, but the curability is not sufficiently improved and the heat resistance due to a decrease in crosslink density is described. , A decrease in mechanical strength is observed.

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. .

[0009]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that a novolac type phenol resin is blended with a thermosetting resin having a dihydrobenzoxazine ring as a curing agent. It was found that the curability of a thermosetting resin having a dihydrobenzoxazine ring can be improved without deteriorating various properties such as mechanical properties, and dihydrobenzoxazine ring is used as a curing agent for a novolac type phenol resin. By blending a thermosetting resin having as a curing agent, it is found that a thermosetting resin composition that is cured with almost no generation of volatile components and that has good properties such as mechanical properties can be obtained. The present invention has been completed based on the findings.

A thermosetting resin composition comprising 60 to 97% by weight of a thermosetting resin having a dihydrobenzoxazine ring and 3 to 40% by weight of a novolac type phenol resin (hereinafter referred to as a thermosetting resin composition). (Sometimes referred to as (a)).

The present invention comprises a thermosetting resin composition having 5 to 30% by weight of a thermosetting resin having a dihydrobenzoxazine ring and 70 to 95% by weight of a novolac type phenolic resin (hereinafter referred to as a thermosetting resin. The resin composition (b) may be referred to as "active resin composition (b)".

The present invention also provides a cured product obtained by curing the thermosetting resin composition (b) of the present invention.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The thermosetting resin having a dihydrobenzoxazine ring used in the present invention is particularly preferably a resin having a dihydrobenzoxazine ring and which is cured by a ring-opening polymerization reaction of the dihydrobenzoxazine ring. The compound is not limited, but is synthesized from a compound having a phenolic hydroxyl group, a primary amine, and formalin as shown in the following formula.

[0014]

[Chemical 1] (In the formula, R ¹ is a methyl group, a phenyl group or at least 1
It is a phenyl group substituted with one alkyl group having 1 to 3 carbon atoms or an alkoxyl group, and has a hydrogen atom bonded to at least one of the ortho positions of the hydroxyl group of the hydroxyphenylene group. Examples of the compound having a phenolic hydroxyl group include polyfunctional phenols, biphenols, bisphenol compounds, trisphenol compounds, tetraphenol compounds and phenol resins. Examples of polyfunctional phenols include catechol, hydroquinone, and resorcinol. Examples of the bisphenol compound include bisphenol A, bisphenol F and positional isomers thereof, bisphenol S, tetrafluorobisphenol A and the like. Examples of the phenol resin include phenol novolac resin, resole resin, phenol-modified xylene resin, alkylphenol resin, melamine phenol resin, and phenol-modified polybutadiene.

Specific examples of primary amines include substituted anilines such as methylamine, aniline, toluidine and anisidine. When it is an aliphatic amine, the obtained thermosetting resin cures quickly but is inferior in heat resistance. When it is an aromatic amine such as aniline, the heat resistance of the cured product obtained by curing the obtained thermosetting resin is good, but the curing is slow.

The thermosetting resin having the above-mentioned dihydrobenzoxazine ring is a compound having two or more hydroxyphenylene groups in which at least one ortho-position of the hydroxyl group is hydrogen in one molecule (hereinafter, a reactive hydroxyphenylene group). And a primary amine are added to formaldehyde such as formalin heated to 70 ° C. or higher, and the mixture is heated at 70 to 110 ° C., preferably 90 to 100 ° C. for 20 minutes or more. Let react for 2 hours,
Then, it is obtained by drying under reduced pressure at a temperature of 120 ° C. or lower.

In the above reaction, usually 0.5 to 1 of primary amine is added to 1 mol of all phenolic hydroxyl groups of the compound having a reactive hydroxyphenylene group.
The reaction is carried out at a ratio of 2 mol or more of formaldehyde to 1.0 mol, preferably 0.6 to 1.0 mol, and 1 mol of primary amine. If the amount of the primary amine is less than 0.5 mol, the crosslink density may be lowered and the heat resistance may be insufficient.

The thermosetting resin having a dihydrobenzoxazine ring used in the present invention may be used in combination of two or more kinds. Further, by pre-treating these thermosetting resins at 80 to 180 ° C., preferably 120 to 160 ° C., a part of them can be prepolymerized to control the curing speed and melt viscosity during molding.

In the present invention, examples of the novolac type phenol resin to be blended with the thermosetting resin include phenol novolac resin, bisphenol novolac resin, phenol-modified xylene resin and alkylphenol resin.

In the present invention, it is preferable to use a so-called high ortho novolak resin having an ortho ratio of 50% or more as the above novolak type phenol resin. By using such a high ortho novolac resin, curability can be improved without lowering mechanical properties.

The thermosetting resin composition (a) comprises thermosetting resins 60 to 9 having the above-mentioned dihydrobenzoxazine ring.
7% by weight, preferably 70-95% by weight, and novolac type phenolic resin 3-40% by weight, preferably 5-3.
It is composed of 0% by weight. The thermosetting resin having a dihydrobenzoxazine ring is self-curing, but the curing reaction is slow. Therefore, novolac type phenolic resin 3 ~
By blending 40% by weight, it was possible to obtain a thermosetting resin composition having improved curability and no deterioration in mechanical properties. When the thermosetting resin having a dihydrobenzoxazine ring exceeds 97% by weight, the effect of improving curability may be reduced.

Further, a cured product of a resin having a dihydrobenzoxazine structure is characterized in that it has a lower water absorption rate than a cured product of a conventional thermosetting resin such as an epoxy resin or a phenol resin. This phenomenon is considered to be because the phenolic hydroxyl group is immobilized by the interaction with the nitrogen atom. In order to maintain this characteristic, as in the thermosetting resin composition (a), a thermosetting resin having a dihydrobenzoxazine ring is used as a main component, and a thermosetting resin having a dihydrobenzoxazine ring is used. And the ratio of the number of phenolic hydroxyl groups to the number of nitrogen atoms in the novolac type phenol resin, the number of phenolic hydroxyl groups / the number of nitrogen atoms are 1.5 or less, preferably 0.3 to 1.5, and particularly preferably 0.5 to It is desirable that the composition be 1.10.

The thermosetting resin composition (b) of the present invention contains 5 to 30% by weight, preferably 15 to 30% by weight, of the above-mentioned thermosetting resin having a dihydrobenzoxazine ring, and novolac type phenolic resins 70 to 95. %, Preferably 70 to 85% by weight. When 70 to 95% by weight of the novolac type phenol resin is blended in this way, the thermosetting resin having a dihydrobenzoxazine ring acts as a curing agent. Therefore, since hexamethylenetetramine, which has been conventionally used as a curing agent for novolac resins, is not used, volatile components such as ammonia are not generated during curing, and workability can be improved. Further, the obtained cured product is also excellent in mechanical strength.

The novolac resin exceeds 40% by weight,
If it is less than 70% by weight, the curability is improved but the mechanical properties may be deteriorated.

In addition, the thermosetting resin composition (a) and the thermosetting resin composition (b) of the present invention may be used as a curing agent for a phenolic resin in the field of application requiring further rapid curability. A small amount of a curing agent such as hexamethylenetetramine conventionally used as may be added. Even if such a conventional curing agent is used in combination, the amount of volatile matter such as ammonia can be suppressed to a low level by reducing the amount thereof.
When such an ordinary curing agent is used in combination, the amount thereof is usually a thermosetting resin having a dihydrobenzoxazine ring for both the thermosetting resin composition (a) and the thermosetting resin composition (b). It is desirable that the amount is 1 to 5% by weight based on the total amount of the resin and the novolac type phenol resin.

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 a method of melting and mixing with a heating roll or the like, or dissolving in a solvent A method of mixing is preferable.

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

The thermosetting resin composition of the present invention is kneaded with a heating roll or the like, and thereafter, the temperature is 180 to 220 ° C. and the molding pressure is 2
Hardens by compression molding or transfer molding at 0 to 70 kgf / cm ² for 15 to 30 minutes, and has better curability than a thermosetting resin having a dihydrobenzoxazine ring alone, and also has good mechanical properties and flame retardancy. You can get things.

The cured product is further heated at 180 to 220 ° C.
By post-curing for 5 to 120 minutes, a cured product having better characteristics can be obtained.

The thermosetting resin composition (a) and the thermosetting resin composition (b) of the present invention are, for example,
In applications such as metal-clad laminates, molding materials, encapsulants, and resin materials for FRP, epoxy resin and its curing agent may be added.

The epoxy resin used as an additive component is not particularly limited, and epoxidized novolak resins of phenols and aldehydes such as phenol novolac type epoxy resin and orthocresol novolac type epoxy resin, bisphenol A. , Bisphenol B, bisphenol F, bisphenol S, and other polybasic acids, glycidyl ester type epoxy resins obtained by the reaction of epichlorohydrin, diaminodiphenylmethane, isocyanuric acid and other polyamines, and glycidylamine type epoxy resins obtained by the reaction of epichlorohydrin, olefin bonds There are linear aliphatic epoxy resins and alicyclic epoxy resins obtained by oxidizing peroxyacetic acid with peracetic acid, brominated epoxy resins, and the like. It may be used in combination of two or more thereof. The curing agent for the epoxy resin is not particularly limited, but those that do not generate volatile components during curing are preferable, and in particular, polyaddition type curing agents such as novolac type phenol resin, dicyandiamide, imidazoles, and triphenylphosphine are preferable. is there. When a novolac type phenolic resin is used as a curing agent for the epoxy resin, in addition to the blending amount of the novolac type phenolic resin described for the thermosetting resin compositions (a) and (b), the epoxy resin It is preferable to add the novolac type phenol resin in an amount such that the hydroxyl group of the novolac type phenol resin is usually 0.5 to 1.5 mol with respect to 1 mol of the epoxy group.

The thermosetting resin composition of the present invention (thermosetting resin composition (b)) is a high-performance molding material, paint, coating material, adhesive having excellent heat resistance, flame retardancy and molding workability. , Encapsulant, prepreg for printed wiring board, metal-clad laminate,
It is preferably used as a resin material for FRP and carbon products.

For example, the thermosetting resin composition of the present invention is used as it is, or if necessary, a filler, a reinforcing fiber, a release agent,
By adding a colorant or the like, it can be used as various molding materials, sealing materials for sealing semiconductor elements, and the like. Further, by impregnating a base material such as a glass cloth with a varnish containing a thermosetting resin composition of the present invention and a filler and the like as necessary, and heating and drying the prepreg to be used for manufacturing a printed wiring board. Obtainable. By stacking a plurality of these prepregs and further disposing a metal foil such as a copper foil on one surface or both surfaces of the prepreg and heating and pressurizing the same, a metal-clad laminate can be obtained. The printed wiring board produced by using the prepreg or the metal-clad laminate thus obtained is excellent in heat resistance and flame retardancy, and thus is suitably used in various electric and electronic fields.

[0034]

The present invention will be described in more detail below with reference to examples of the present invention and comparative examples thereof, but the present invention is not limited to these examples.

Examples 1 to 13 (Examples 4, 5, 7, 9,
10, 12 and 13 are reference examples), Comparative examples 1 to 10 [1] 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-polynuclear body / 2 binuclear body ratio of 89/11 (peak area ratio by gel permeation chromatography).

(2) Introduction of dihydrobenzoxazine ring Phenol novolac resin 1.7k synthesized above
g (corresponding to 16 mol of hydroxyl group) to aniline 1.4
It was mixed with 9 kg (corresponding to 16 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 addition was completed, the mixture was kept at a reflux temperature for 30 minutes, and after that, condensed water was removed by reducing the pressure to 6666.1 Pa or less at 100 ° C. for 2 hours, and thermosetting in which 95% of reactive hydroxyl groups were dihydrobenzoxazinized. A resin was obtained.

[2] Synthesis of thermosetting resin having dihydrobenzoxazine ring (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 thermosetting resin having a dihydrobenzoxazine ring. The obtained resin has a softening point of 84 ° C. (ring and ball method),
The ratio was 3 to polynuclear body / 2 binuclear body ratio 82/18 (peak area ratio by gel permeation chromatography).

(2) Introduction of dihydrobenzoxazine ring Hereinafter, a dihydrobenzoxazine ring was introduced in the same manner as in the synthesis (I) of thermosetting resin having a dihydrobenzoxazine ring. The resulting thermosetting resin was a phenol novolac resin in which a dihydrobenzoxazine ring was introduced into 90% of the reactive hydroxyl groups.

[3] Synthesis of Thermosetting Resin Having Dihydrobenzoxazine Ring (III) Bisphenol A 0.76 kg (hydroxyl group 10 m
ol), 0.93 kg (10 mol) of aniline, and 1.62 kg of formalin (37% aqueous solution) and reacted in the same manner as in the above synthetic method, and thermosetting in which dihydrobenzoxazine ring was introduced into 94% of hydroxyl groups. Resin was synthesized.

[4] Synthesis of novolac type phenolic resin (A) 2.4 kg of phenol, formalin (37% aqueous solution)
0.02 kg, paraformaldehyde 0.6 kg, zinc acetate 0.02 kg, benzoic acid 0.06 kg, water 0.05
5 kg was 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 has a softening point of 75 to 83 ° C. (ring and ball method) and an ortho ratio of 70.
% (NMR).

[5] Synthesis of novolac type phenolic resin (B) 1.9 kg of phenol, formalin (37% aqueous solution)
1.3 kg and 15 g of oxalic acid were charged into a 5 liter flask and reacted at reflux temperature for 6 hours. 6 inside
The pressure was reduced to 666.1 Pa or less to remove unreacted phenol and water. The obtained resin had a softening point of 84 ° C. (ring and ball method) and an ortho rate of 40% (NMR).

[6] Preparation of Resin Composition In Examples 1 to 13 and Comparative Examples 6 and 8 to 10, the novolac type phenol resin obtained above was charged into a flask and heated to 110 to 120 ° C. to prepare the resin. After being dissolved, a thermosetting resin having a dihydrobenzoxazine ring was added thereto, and the mixture was stirred for 5 minutes until it became uniform to obtain a resin composition. In Comparative Examples 1 to 3, only the thermosetting resin having the dihydrobenzoxazine ring was used. In Comparative Examples 4 and 5,
A novolac-type phenol resin and hexamethylenetetramine were pulverized and then mixed in a mixer for 3 minutes to prepare a resin composition. In Comparative Example 7, a thermosetting resin having a dihydrobenzoxazine ring was dissolved in molten phenol and stirred for 5 minutes until it became uniform to prepare a resin composition.

[7] Curing The resin composition obtained above was crushed to give an inner diameter of 120 ×
Filled in a 80 × 4 mm mold, 180 ° C, 1.96MP
A cured product was produced by heating and pressurizing at a for 15 minutes.

Regarding the characteristics of the resin composition, the gel time was such that 0.3 g of the resin composition was agitated once per second on a gel timer heated to 180 ° C. and the time until stringing disappeared.

Among the properties of the cured product, the bending strength and bending elastic modulus are in accordance with JIS K 6911 at 23 ° C. and bending speed of 2
Evaluation was made in mm / min.

Flame retardance is in accordance with UL-94, 3.
Evaluation was made with a thickness of 6 mm.

The water absorption rate was 50 × 50 × 3 mm and a PCT (pressure cooker
It processed in the tester (121 degreeC, 2 atmospheres) for 10 hours, and calculated from the weight difference before and after processing. Example 4 (phenolic OH / N = 1.10) and Comparative Example 6 (phenolic OH / N)
N = 1.93), the water absorption is 1.6% and 3.
2%, which is a large difference.

Tables 1 to 9 show the compounding compositions and the measurement results in each Example and Comparative Example. The blending compositions are all shown in parts by weight.

[0049]

[Table 1]

[0050]

[Table 2]

[0051]

[Table 3]

[0052]

[Table 4]

[0053]

[Table 5]

[0054]

[Table 6]

[0055]

[Table 7]

[0056]

[Table 8]

[0057]

[Table 9]

[0058]

The thermosetting resin composition of the present invention is fast curable, and the cured product has good mechanical properties and flame retardancy. Therefore, the thermosetting resin composition of the present invention is useful as a raw material for high-performance molding materials, paints, coating agents, adhesives, sealants, laminates, FRP, carbon products and the like.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasuyuki Hirai             Hitachi Chemical, 1500 Ogawa, Shimodate City, Ibaraki Prefecture             Shimodate Factory of Industrial Co., Ltd. (72) Inventor Aihiko Sato             Hitachi Chemical, 1500 Ogawa, Shimodate City, Ibaraki Prefecture             Shimodate Factory of Industrial Co., Ltd. F-term (reference) 4J002 AA072 CC031 CC061 CC071                       CC271 CC272 GF00 GH00                       GH01 GJ01 GJ02 GQ00                 4M109 AA01 CA21 EA01

Claims (5)

[Claims] 1. A thermosetting resin composition comprising 5 to 30% by weight of a thermosetting resin having a dihydrobenzoxazine ring and 70 to 95% by weight of a novolac type phenolic resin. 2. The thermosetting resin composition according to claim 1, wherein the novolac type phenolic resin is a novolac type phenolic resin having an ortho rate of 50% or more. 3. A thermosetting resin having a dihydrobenzoxazine ring has a hydroxyphenylene group having hydrogen bonded to at least one of ortho positions of a hydroxyl group.
A compound having two or more molecules in the molecule, a primary amine and formaldehyde, and a phenolic hydroxyl group of the compound 1
The thermosetting composition according to claim 1 or 2, which is synthesized by reacting 0.5 to 1.0 mol of a primary amine per mol and formaldehyde at a ratio of 2 mol or more per mol of the primary amine. Resin composition. 4. A hydroxyphenylene group having hydrogen bonded to at least one of the ortho positions of a hydroxyl group is 1
The thermosetting resin composition according to claim 3, wherein the compound having two or more in the molecule is phenol novolac resin or bisphenol A. 5. A cured product obtained by curing the thermosetting resin composition according to claim 1.