JPH10195178A - Flame-retardant epoxy resin composition, prepreg, laminate and copper-clad printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition which shows excellent flame retardancy in spite of being halogen-free and is excellent in tracking resistance, heat resistance, humidity resistance, etc., and a prepreg, a laminate, a copper- clad laminate and a printed circuit board prepared by using the same. SOLUTION: This composition is a halogen-free flame-retardant one comprising a bisphenol A epoxy resin, a novolac epoxy resin, a phenolic resin curing agent, a cure accelerator and an inorganic filler. The above curing agent is a nitrogenous phenolic resin being a resin obtained by the cocondensation of a phenol compound with a melamine compound and an aldehyde compound, a cocondensation resin prepared by reacting the above compounds with a reactive phosphoric ester or the above cocondensation resin combined with a reactive phosphoric ester.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a halogen-free flame-retardant epoxy resin composition, and a prepreg, a laminate, a copper-clad laminate and a printed wiring board containing the same.

[0002]

2. Description of the Related Art In recent years, there has been an increasing interest in global environmental issues and safety for the human body, and in addition to flame retardancy, demands for less harmful and higher safety have been placed on electric and electronic products. Is growing. That is, electrical and electronic products are required not only to be difficult to burn but also to generate less harmful gas and smoke. Conventionally,
A printed wiring board on which electric / electronic parts are mounted usually has a substrate made of glass epoxy, and the epoxy resin used therein is a brominated epoxy containing bromine which acts as a flame retardant, particularly tetrabromobisphenol. A type epoxy resin is generally used.

[0003]

Although such a brominated epoxy resin has good flame retardancy, it emits harmful hydrogen halide (hydrogen bromide) gas during combustion.
Its use is being suppressed. Therefore, a composition in which a non-halogen flame retardant such as a normal epoxy resin, for example, a nitrogen compound, a phosphorus compound, an inorganic compound has been developed has been developed (for example, British Patent No. 1,112,139, JP-A No.
2-269730). However, these flame-retardant additives have problems such as adversely affecting the curing of the epoxy resin, reducing the moisture resistance of the cured composition, or decreasing the impregnation of the composition into glass cloth. .

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned disadvantages, and has an epoxy resin composition which exhibits good flame retardancy without halogen and has excellent tracking resistance, heat resistance and moisture resistance. It is another object of the present invention to provide a product, a prepreg impregnated with such an epoxy resin composition, and a laminate, a copper-clad laminate, and a printed wiring board manufactured using the prepreg.

[0005]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that the composition described below achieves the above-mentioned object, and completed the present invention. It is.

That is, the present invention provides, in a first aspect,
In order to impart flame retardancy to a composition obtained by mixing (A) a bisphenol A type epoxy resin, (B) a novolak type epoxy resin, (D) a curing accelerator and (E) an inorganic filler, It is a halogen-free flame-retardant epoxy resin composition containing a nitrogen atom-containing phenol resin which is a co-condensation resin of a phenol compound, a melamine compound and an aldehyde compound as a curing agent.

In a second aspect, the present invention provides a composition comprising a mixture of (A) a bisphenol A type epoxy resin, (B) a novolak type epoxy resin, (D) a curing accelerator, and (E) an inorganic filler. In order to impart flame retardancy to the composition, a (C) phenol compound containing a phosphorus compound and a nitrogen atom, which is composed of a reaction product of a phenol compound, a melamine compound, an aldehyde compound and a reactive phosphate ester, is added as a curing agent. And a halogen-free flame-retardant epoxy resin composition.

[0008] In the third aspect, the present invention relates to a third aspect, wherein (A) a bisphenol A type epoxy resin, (B) a novolak type epoxy resin, (C-1) a reactive phosphate ester,
2) A halogen-free flame-retardant epoxy resin composition containing a co-condensation resin of a phenol compound, a melamine compound and an aldehyde compound, (D) a curing accelerator and (E) an inorganic filler.

The present invention further provides a prepreg impregnated with the halogen-free flame-retardant epoxy resin composition of the present invention, and a laminate manufactured using the prepreg.
A copper-clad laminate and a printed wiring board.

Hereinafter, the present invention will be described in detail.

The epoxy resin composition of the present invention contains a bisphenol A type epoxy resin as the component (A). The bisphenol A type epoxy resin is a reaction product of bisphenol A and epichlorohydrin and the like, as is well known in the art. The bisphenol A type epoxy resin used in the present invention is usually 170
It has an epoxy equivalent of ~ 1000. Epoxy equivalent is 1000
If it exceeds, the impregnating property of the obtained composition into the glass cloth is undesirably reduced. Such a bisphenol A type epoxy resin is commercially available, for example, it is available from Yuka Shell Co. as Epicoat series and from Ciba-Geigy Co. as Araldite series. The bisphenol A type epoxy resins can be used alone or in combination of two or more.

Component (B) of the epoxy resin composition of the present invention
Is a novolak type epoxy resin. As is well known in the art, a novolak type epoxy resin is an epoxy resin obtained by reacting epichlorohydrin with a novolak resin, and a novolak resin is obtained by condensing phenols and formaldehyde with an acidic catalyst. Resin. As phenols that form a novolak resin by reaction with formaldehyde, phenol, cresol, bisphenol A and the like can be used. The novolak type epoxy resin used in the present invention preferably has a softening point of 70 ° C to 130 ° C, more preferably 80 ° C to 100 ° C. Such novolac type epoxy resin is commercially available from, for example, Toto Kasei Co. or Dainippon Ink and Chemicals. The novolak type epoxy resins can be used alone or in combination of two or more.

The epoxy resin composition of the present invention contains (C) a phenol resin containing a nitrogen atom in the molecule as a curing agent in order to impart flame retardancy to the composition. Needless to say, the phenolic resin is a condensation product of phenols and aldehyde such as formaldehyde. Nitrogen contained in the nitrogen atom-containing phenol resin may be present in any of the phenol resins. In a preferred embodiment of the present invention, the nitrogen atom-containing phenol resin is a co-condensation resin of a phenol compound, a melamine compound and an aldehyde compound.

Such a co-condensation resin can be produced by reacting a phenol compound, an aldehyde compound and a melamine compound in the presence of an acid catalyst (eg, oxalic acid, p-toluenesulfonic acid). In that case, the molar ratio of the aldehyde compound to the phenol compound is less than 1.0, preferably 0.5 to less than 1.0, and the primary amino group (--NH2) 1 of the melamine compound is 1
It is preferable to use 1 mol of the aldehyde compound (for example, 3 mol of formaldehyde to 1 mol of melamine). Examples of the phenol compound to be used include phenol, resorcin, and alkylphenol (cresol, xylenol, etc.). Formaldehyde is particularly preferred as the aldehyde compound.

The melamine compound has the formula

[0016]

Embedded image (Where R represents an alkyl group such as an amino group, a phenyl group, or a methyl group). Examples of the melamine compound include melamine, phenylmelamine, butylmelamine and the like. The melamine compounds can be used alone or in combination of two or more.

When the nitrogen atom-containing phenol resin is used as a curing agent, a sufficient effect can be obtained in terms of flame retardancy due to interaction with a filler described later. However, in the case of producing a glass epoxy copper clad laminate using the epoxy resin composition of the present invention, and thus a printed wiring board, in order to further improve its tracking resistance,
As the curing agent, it is preferable to use a phenol resin containing a nitrogen atom and a phosphorus atom in the molecule. A phenol resin containing such a phosphorus atom and a nitrogen atom can be produced from the above-mentioned phenol compound, melamine compound, aldehyde compound and reactive phosphate ester.

In this reaction, a phenol compound, a melamine compound, and an aldehyde compound are used in the same ratio as when the above-mentioned co-condensation resin is prepared, and the reactive phosphate ester is
Preferably, it is used in such a ratio that 2 moles of aldehyde are obtained for each free hydroxyl group.

For example, a phosphorus atom- and nitrogen atom-containing phenol resin can be obtained in one step by reacting a phenol compound, a melamine compound, an aldehyde compound and a reactive phosphoric acid ester. Alternatively, the phosphorus atom- and nitrogen atom-containing phenol resin can also be obtained by preparing a co-condensation resin of a phenol compound, a melamine compound and an aldehyde compound in advance, and reacting this with an aldehyde compound and a reactive phosphate ester. it can. In any case, the phenolic compound, melamine compound, aldehyde compound and reactive phosphate ester are used in the above proportions. Therefore, when the above-mentioned co-condensation resin is manufactured in advance, the sum of the amount of the aldehyde compound used at that time and the amount of the aldehyde compound to be subsequently reacted with the co-condensation resin is set to be the above ratio.

The reactive phosphate ester used is obtained by reacting three molecules of a phenol compound with one molecule of phosphorus oxytrichloride, and at least one of the three molecules of the phenol compound is at least two. Having a hydroxyl group. Examples of such a phenol compound having two or more hydroxyl groups include resorcinol and pyrogallol.

This reactive phosphate ester has the formula

[0022]

Embedded image (Where a + b + c = 3, a is 1, 2 or 3, and b is
0, 1 or 2, c is 0, 1 or 2, n is 1 or 2, R1
, R2, R3, R4 and R5 are each a hydrogen atom or an alkyl group, at least one of which is an alkyl group. Among such reactive phosphoric acid esters, for example, resorcyl diphenyl phosphate is commercially available from Ajinomoto Co., Inc. under the trade name of RDP.

The phenol compound / melamine compound / aldehyde compound co-condensation resin and the reactive phosphoric acid ester may be blended into the epoxy resin as separate components, instead of preliminarily reacting and blending into the epoxy resin. it can. In that case, the reaction type phosphoric acid ester (component C-1) and the phenol compound / melamine compound / aldehyde compound co-condensation resin (C-2) are the above-mentioned phenol compound / melamine compound / aldehyde compound co-condensation resin.
Reactive phosphate ester 5 to 70 to 95 parts by weight
Used at a rate of 30 parts by weight. If the amount of the latter is less than 5 parts by weight, sufficient tracking resistance cannot be obtained, while if it exceeds 30 parts by weight, the moisture resistance tends to decrease.

The curing accelerator (D) contained in the epoxy resin composition of the present invention is usually used as a curing accelerator for epoxy resins, and includes 2-ethyl-4-methylimidazole and 1-benzyl-. An imidazole compound such as 2-methylimidazole is included. These curing accelerators can be used alone or in combination of two or more. The curing accelerator is used in a small enough amount to accelerate the curing of the epoxy resin.

The inorganic filler (component (E)) contained in the epoxy resin composition of the present invention is for imparting an additional flame retardant, heat resistance and moisture resistance to the epoxy resin composition. These fillers include talc, silica, alumina, aluminum hydroxide, magnesium hydroxide and the like, and can be used alone or in combination of two or more. In the halogen-free flame-retardant epoxy resin composition of the present invention, the inorganic filler as the component (E) is blended in an amount of 5 to 50 parts by weight based on the total weight of the components (A) to (E). Is preferred. When the amount of the component (E) is less than 5 parts by weight, sufficient flame retardancy, heat resistance and moisture resistance cannot be obtained,
On the other hand, when the amount of the component (E) exceeds 50 parts by weight, the viscosity of the composition increases, and uneven coating is likely to occur on a substrate such as a glass non-woven fabric or a glass woven fabric, resulting in voids and the resulting laminate. Tend to cause uneven thickness.

In the epoxy resin composition of the present invention, the resin solid content (component (A) + (B) + (C) + (D) is 50 to 95 of the total weight of component (A) to component (E)). It is preferable to use it in a weight percentage of the component (D).
Is small as described above, for example, about 0.01 to 1% by weight is sufficient.

Epoxy resin component (component (A) + (B))
And phenol resin component (C) (component (C-1) + (C-
The same applies to the case of 2)) means that the epoxy equivalent is 0.8 to 1.2, preferably 0.9 per 1 hydroxyl group equivalent in the entire composition.
It is preferable to mix them so as to be 5 to 1.05.
In this case, the epoxy resin component is preferably blended at a ratio of about 51 to 90% by weight of the resin component of the composition.

Preferably, the component (A) is blended in a proportion of 60 to 95% by weight based on the total weight of the components (A) and (B).

In the present invention, 1 to 10% by weight, preferably 4% by weight, of a nitrogen atom is contained in the entire epoxy resin composition.
Component (C) or components (C-1) and (C-2) are blended so that the phosphorus atom is contained in an amount of 0.5 to 3% by weight, preferably 0.8 to 1.5% by weight. It is particularly preferable to obtain excellent flame retardancy and tracking resistance.

The epoxy resin composition of the present invention described above is diluted with a suitable organic solvent such as propylene glycol monomethyl ether to form a varnish, which is then made into a porous glass substrate such as a glass nonwoven fabric or a glass woven fabric. A prepreg can be manufactured by a usual method of coating, impregnating, and heating. Also, a plurality of the prepregs may be laminated, and a copper foil may be laminated on one or both sides of the laminated structure, and then heated and pressed under a normal condition to obtain a glass epoxy copper clad laminate. At this time, if no copper foil is used, a laminate can be obtained. In the multilayer board, a circuit is formed on a copper-clad laminate (inner board), and then the copper foil is subjected to an etching treatment. Then, a prepreg and a copper foil are laminated on at least one side of the inner board.
It can be produced by the usual method of heating and pressurizing at a pressure of cm @ 2 for 90 minutes. Further, the printed wiring board can be manufactured by a usual method of forming a through hole in a copper-clad laminate or a multilayer board, performing through-hole plating, and then forming a predetermined circuit.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described specifically with reference to examples.

Preparation Example A 0.1 part by weight of oxalic acid was added to a mixture consisting of 60 parts by weight of phenylmelamine, 300 parts by weight of 37% aqueous formalin solution and 367 parts by weight of phenol. 80 of the resulting mixture
After reacting at 2 ° C. for 2 hours, dehydration was performed under reduced pressure. Methyl ethyl ketone was added to the obtained reaction product to adjust the resin solid content (phenol / phenylmelamine / formaldehyde co-condensation resin) to 70% by weight. The resulting co-condensed resin contained 5% by weight nitrogen.

Production Example B 18 parts by weight of melamine, 30 parts by weight of phenylmelamine and
A mixture consisting of 50 parts by weight of a 37% formalin aqueous solution is heated to 80 ° C.
For 30 minutes. To this reaction mixture was added 367 parts by weight of phenol and 250 parts by weight of 37% aqueous formalin solution, followed by 0.1 part by weight of oxalic acid. The obtained reaction mixture was reacted at 80 ° C. for 2 hours, and then dehydrated under reduced pressure. Methyl ethyl ketone was added to the obtained reaction product to prepare a resin solid content (phenol / melamine / phenylmelamine / formaldehyde cocondensation resin) at 70% by weight. The resulting co-condensed resin contained 5% by weight nitrogen.

Production Example C 54 parts by weight of phenylmelamine, 214 parts by weight of a 37% aqueous formalin solution, 248 parts by weight of phenol and 36 parts by weight of R
0.1 part by weight of oxalic acid was added to a mixture of DP (Resorcyl diphenyl phosphate manufactured by Ajinomoto Co., Inc.).
The reaction mixture was reacted at 80 ° C. for 2 hours, and then dehydrated under reduced pressure. Methyl ethyl ketone was added to the obtained reaction product to adjust the resin solid content (phenylmelamine phosphate / phenol / formaldehyde co-condensation resin) to 70% by weight. The resulting resin contained 5% by weight of nitrogen and 1% by weight of phosphorus.

Preparation Example D A mixture consisting of 100 parts by weight of phenylmelamine, 218 parts by weight of a 37% formalin aqueous solution, 212 parts by weight of phenol and 115 parts by weight of RDP (described above) is reacted under the same conditions as in Preparation Example C. Thus, a desired phenol resin containing a phosphorus atom and a nitrogen atom was obtained. This resin contains 10 wt% nitrogen and 2 wt%
It contained phosphorus.

Example 1 260 parts by weight of bisphenol A type epoxy resin Epicoat 1001 (manufactured by Yuka Shell Co., epoxy equivalent 456, resin solid content 70% by weight), 65 parts by weight of cresol novolac epoxy resin YDCN-704P (Tohto Kasei Co., Ltd.) Production example C with epoxy equivalent 210, solid content 70% by weight), 128 parts by weight
A nitrogen-containing and phosphorus-containing phenolic resin obtained in 1.
Propylene glycol monomethyl ether (hereinafter referred to as PG) as a solvent in a mixture consisting of 1 part by weight of aluminum hydroxide and 0.1 part by weight of 2-ethyl-4-methylimidazole.
M) was added to prepare an epoxy resin varnish having a resin solid content of 65% by weight.

Example 2 260 parts by weight of bisphenol A type epoxy resin Epicoat 1001 (supra), 65 parts by weight of cresol novolac epoxy resin YDCN-704P (supra), 184 parts by weight of the nitrogen atom obtained in Preparation Example D and P to a mixture consisting of a phosphorus atom-containing phenolic resin, 150 parts by weight of aluminum hydroxide, and 0.1 parts by weight of 2-ethyl-4-methylimidazole.
GM was added to prepare an epoxy resin varnish having a resin solid content of 65% by weight.

Example 3 260 parts by weight of bisphenol A type epoxy resin Epicoat 1001 (supra), 65 parts by weight of cresol novolac epoxy resin YCDN-704P (supra), 206 parts by weight of nitrogen atom obtained in Preparation Example C PGM was added to a mixture of a phenolic resin containing phosphorus and a phosphorus atom, 150 parts by weight of aluminum hydroxide, and 0.1 part by weight of 2-ethyl-4-methylimidazole to prepare an epoxy resin varnish having a resin solid content of 65% by weight.

Example 4 260 parts by weight of bisphenol A type epoxy resin Epicoat 1001 (supra), 65 parts by weight of cresol novolac epoxy resin YCDN-704P (supra), 105 parts by weight of the cocondensation prepared in Preparation Example A. PGM was added to a mixture of resin, 200 parts by weight of aluminum hydroxide, and 0.1 parts by weight of 2-ethyl-4-methylimidazole to prepare an epoxy resin varnish having a resin solid content of 65% by weight.

Example 5 260 parts by weight of bisphenol A epoxy resin epicoat 1001 (supra), 65 parts by weight of cresol novolak epoxy resin YCDN-704P (supra), 105 parts by weight of co-condensation obtained in Preparation A Epoxy resin having a resin solid content of 65% by adding PGM to a mixture of resin, 30 parts by weight of RDP (supra), 175 parts by weight of aluminum hydroxide, and 0.1 parts by weight of 2-ethyl-4-methylimidazole. A varnish was prepared.

Comparative Example 1 283 parts by weight of brominated epoxy resin (Dainippon Ink and Chemicals, Inc., epoxy equivalent 490, solid content 75% by weight), 34 parts by weight of cresol novolac epoxy resin YCDN-70.
4P (supra), 92 parts by weight of bisphenol A type novolak resin (manufactured by Dainippon Ink and Chemicals, hydroxyl value 118, solid content 70% by weight), 130 parts by weight of aluminum hydroxide, and 0.1 part by weight of 2- PGM was added to a mixture consisting of ethyl-4-methylimidazole to prepare an epoxy resin varnish having a resin solid content of 65% by weight.

Comparative Example 2 360 parts by weight of the brominated epoxy resin used in the comparative example, 43 parts by weight of the cresol novolak epoxy resin YCDN-7
04P (supra), 7.5 parts by weight of dicyandiamide, 130
Dimethylformamide was added to a mixture consisting of parts by weight of aluminum hydroxide and 0.1 parts by weight of 2-ethyl-4-methylimidazole to prepare an epoxy resin varnish having a resin solid content of 65% by weight.

Each of the epoxy resin varnishes obtained in Examples 1 to 5 and Comparative Examples 1 and 2 was continuously applied and impregnated on a glass nonwoven fabric or a glass woven fabric, and dried at a temperature of 160 ° C. to produce a prepreg. Prepreg obtained in this way
Eight sheets are stacked and copper foil with a thickness of 18 μm is stacked on both sides of this laminated body and heated and pressed at a temperature of 170 ° C. and a pressure of 40 kg / cm 2 for 90 minutes, and a 1.6 mm thick glass epoxy copper clad laminate is laminated. I got a board.

The obtained copper-clad laminate was measured for flame retardancy, tracking resistance, insulation resistance, peeling strength of copper foil at initial and after a long time, heat resistance and moisture resistance. Table 1 shows the results.

[0045]

[Table 1] * 1: Measured according to UL94 flame retardancy test. * 2: Measured according to IEC-PB112. * 3: Measured according to JIS-C-6481. * 4: Measured according to JIS-C-6481. * 5: Each sample shown in the table was floated on a solder bath at 260 ° C, and the presence or absence of swelling was observed and evaluated according to the following criteria. ◎: no swelling, ○: some swelling, Δ: most swelling, ×: swelling all over. * 6: After swelling the sample under condition A (boiling for 6 hours) or condition B (120 ° C, 2 atm pressure in water vapor for 7 hours), dip it in a solder bath at 260 ° C for 30 seconds, and then check for swelling. Was observed and evaluated according to the following criteria. ◎: No swelling, ○: Partially swelling, △: Mostly swelling, X: Swelling on the entire surface.

Example 6 A glass woven fabric or a glass woven fabric was continuously coated with and impregnated with the epoxy resin varnish obtained in Example 2 and dried at a temperature of 160 ° C. to prepare a prepreg. Eight prepregs thus obtained were stacked, and the temperature was 170 ° C and 40 kg / cm.
The mixture was heated and pressed at a pressure of 2 for 90 minutes to obtain a glass epoxy laminate. The flame retardancy, tracking resistance, insulation resistance, and moisture resistance of this glass epoxy laminate were measured by the above measuring methods. The results are shown below.

Flame retardancy: V-0, tracking resistance: 600
V, insulation resistance: 2.0Ω, moisture resistance Condition A: ◎ No blister,
Condition B: ◎ No swelling.

Example 7 A prepreg was produced in the same manner as in Example 6. This prepreg was laminated, and a copper foil having a thickness of 35 μm was laminated on both sides thereof, and heated and pressed in the same manner to produce an inner layer plate having a thickness of 0.8 mm. The above prepregs were laminated on both sides of this inner layer plate, and a copper foil having a thickness of 18 μm was laminated on each of them and heated and pressed in the same manner to manufacture a multilayer plate having a plate thickness of 1.6 mm. When the moisture resistance of this multilayer board after being treated under the condition A was measured by the above measuring method, no swelling was observed.

[0049]

As described above, according to the present invention, a glass epoxy copper clad laminate which does not contain halogen, exhibits excellent flame retardancy, and is excellent in heat resistance, moisture resistance and tracking resistance is obtained. An epoxy resin is provided. By using such a glass epoxy copper clad laminate, a printed wiring board excellent in various properties can be manufactured.

Continuation of front page (51) Int.Cl. ⁶ Identification code FI C08L 61/34 C08L 61/34 H05K 1/03 610 H05K 1/03 610L

Claims (11)

[Claims] 1. A nitrogen atom-containing phenol which is a co-condensation resin of a phenol compound, a melamine compound and an aldehyde compound as (A) bisphenol A type epoxy resin, (B) novolac type epoxy resin, and (C) curing agent. A flame-retardant epoxy resin composition comprising a resin, (D) a curing accelerator and (E) an inorganic filler, and containing no halogen atom. 2. A bisphenol A type epoxy resin comprising:
The composition of claim 1 having an epoxy equivalent of 0 to 1000. 3. A bisphenol A type epoxy resin, (B) a novolak type epoxy resin, and (C) phosphorus as a curing agent, which is a reaction product of a reactive phosphoric ester, a phenol compound, a melamine compound and an aldehyde compound. A flame-retardant epoxy resin composition comprising a phenolic resin containing an atom and a nitrogen atom, (D) a curing accelerator and (E) an inorganic filler, and containing no halogen atom. 4. The reactive phosphate ester of the formula: (Where a + b + c = 3, a is 1, 2 or 3, and b is
0, 1 or 2, c is 0, 1 or 2, n is 1 or 2, R1
, R2, R3, R4 and R5 are each a hydrogen atom or an alkyl group, at least one of which is an alkyl group). 5. A co-condensation of (A) a bisphenol A type epoxy resin, (B) a novolak type epoxy resin, (C-1) a reactive phosphoric acid ester, and (C-2) a phenol resin with a melamine compound and an aldehyde compound. A flame-retardant epoxy resin composition comprising a resin, (D) a curing accelerator and (E) an inorganic filler and containing no halogen atom. 6. The reactive phosphoric ester (C-1) has the formula: (Where a + b + c = 3, a is 1, 2 or 3, b is
0, 1 or 2, c is 0, 1 or 2, n is 1 or 2, R1
, R2, R3, R4 and R5 are each a hydrogen atom or an alkyl group, and at least one of them is an alkyl group). 7. A prepreg in which a glass substrate is impregnated with the epoxy resin composition according to any one of claims 1 to 6. 8. The epoxy resin composition is cured,
A laminate comprising a plurality of the prepregs according to claim 7 superposed. 9. A copper clad laminate comprising a substrate made of the prepreg according to claim 7 in which the epoxy resin composition is cured, and a copper foil bonded to at least one surface of the substrate. 10. A printed wiring board comprising a substrate made of the prepreg according to claim 7 in which the epoxy resin composition is cured, and a wiring layer formed on at least one surface of the substrate. 11. A printed wiring board comprising a substrate comprising the prepreg according to claim 9 in which the epoxy resin composition is cured, and a wiring layer formed on at least one surface of the substrate.