JPH0238123B2 - EHOKISHIJUSHISOSEIBUTSU - Google Patents

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to an epoxy resin composition used for epoxy resin laminates for electronic devices, epoxy resin molding materials, and the like. [Background Art] Epoxy resins are used in a wide variety of applications, such as laminates, molded products, and sealing materials for electronic devices.
As electronic devices become more reliable, smaller, lighter, and lower in cost, epoxy resin compositions used for electronic devices are becoming more heat resistant, more adhesive, less toxic, and less expensive. There is a strong desire for this to become a reality. The selection of a curing agent is an important factor in achieving the above-mentioned properties in epoxy resins, and conventionally, in epoxy resin compositions for use in electronic devices, dicyandiamide, dicyandiamide,
Nitrogen compounds such as dihalogenated diaminodiphenylmethane or phenol formaldehyde resins are used industrially. However, when dicyandiamide is used, there is a problem of poor heat resistance, such as a low thermal decomposition temperature of the cured product and low heat resistance after moisture absorption, and dihalogenated diaminodiphenylmethane is highly toxic and has low reaction activity. Since the epoxy resin is low, there is a problem that the reactivity of the epoxy resin is slow. Furthermore, although phenol formaldehyde resin has the advantage of being low in cost, when the conventionally used phenol formaldehyde resin is used as a curing agent, there is a problem that the adhesiveness of the epoxy resin decreases, as will be explained later. It had the following characteristics. [Object of the Invention] The present invention has been made in view of the above points, and provides an epoxy resin composition that has good heat resistance, adhesiveness, and fast curing properties, has low toxicity, and is inexpensive. The purpose is to provide the following. [Disclosure of the Invention] However, the epoxy resin composition according to the present invention,
Epoxy resin contains tetrahalogenated diaminodiphenylmethane as a curing agent and the general formula is (In the formula, X is CH ₂ or C(CH ₃ ) ₂ , and Y is H
or CH ₃ and all four Y's may be the same or different. ) The present invention will be described in detail below. The epoxy resin used in the present invention is not particularly limited as long as it has an average of two or more epoxy groups per molecule. For example, diglycidyl ether type epoxy resin of bisphenol A, diglycidyl ether type epoxy resin of halogenated bisphenol A, polyglycidyl ether of butadiene diepoxide/phenol novolac, polyglycidyl ether of halogenated phenol novolac, etc. Can be done. A curing agent is added to this epoxy resin, and novolak resin is known as a typical phenol formaldehyde resin that has been advantageously used as a curing agent for epoxy resins due to its low cost. Novolak resin has a molar ratio of phenols to formaldehyde of, for example, 1:1.
It is produced by reacting phenols and formaldehyde (formalin) with an acid catalyst such as oxalic acid under conditions of an excess of phenol of 0.7 to 0.9. The inventors investigated and found that the phenol novolac resin obtained in this way inevitably contains about 8 to 20% by weight or more of a low molecular weight compound having two or less benzene nuclei. In order to increase the crosslinking density of epoxy resin using phenol novolak resin as a curing agent and ensure properties at high temperatures, a large amount of polyfunctional epoxy resin having three or more epoxy groups per molecule is used as the epoxy resin. I have no choice but to use it. However, it has been found that although this makes it possible to ensure properties at high temperatures, a new problem arises in that adhesiveness deteriorates. Therefore, it is thought that if a phenol novolak resin with a reduced content of low molecular weight compounds having two or less benzene nuclei is used as a curing agent for epoxy resin, the epoxy resin composition will have excellent performance. By the way. Therefore, in the present invention, as a phenol novolak type curing agent, a curing agent whose main component is a polyhydric phenol whose general formula is represented by the following formula [A] is used. (In the formula, X is CH ₂ or C(CH ₃ ) ₂ , and Y is H
or CH ₃ and all four Y's may be the same or different. ) The curing agent containing polyhydric phenols as a main component represented by formula [A] is prepared as follows.
First, using bisphenol A or bisphenol F as a bisphenol, this bisphenol and formaldehyde are reacted under conditions of excess formaldehyde and in the presence of a metal hydroxide catalyst to obtain a tetramethylol compound of bisphenol. A reactant containing as the main component is prepared. After removing the formaldehyde remaining in this reaction product, the tetramethylol of bisphenols and phenol or cresol as the phenol are reacted in the presence of an acidic catalyst, and the remaining unreacted components are removed. It is possible to obtain a polyhydric phenol-based curing agent which contains the compound of formula [A] as a main component and has a low content of low molecular weight compounds having 2 or less benzene nuclei. To explain this preparation method in more detail, first, in the first step, bisphenol A or bisphenol F as a bisphenol is reacted with formaldehyde in the presence of a catalyst. Alkali metal hydroxides are generally used as catalysts,
For example, sodium hydroxide, calcium hydroxide,
Magnesium hydroxide, etc., and these are used as highly concentrated aqueous solutions. In the reaction operation of the first step, first, an aqueous solution of an alkali metal hydroxide is added to bisphenols. At this time, the amount of alkali metal hydroxide is 0.5 to 1.2 times by mole (preferably 1.0 to 1.1 times by mole) relative to -OH of bisphenols.
It is best to set it to 10 for alkali metal hydroxides.
Preferably, it is used as a ~30% by weight aqueous solution. After the bisphenols are dissolved in the alkali metal hydroxide, formaldehyde is gradually added. The amount of formaldehyde used is 4 to 8 times the mole of bisphenols (preferably 4.0 to 4.5 times).
mole times). Also, the temperature required for the reaction is 30 to 70℃.
℃ (preferably 40-50℃), the time required for the reaction is 1-3 hours. The reaction of formaldehyde with bisphenols produces tetramethylolated bisphenols. After the reaction of this first step is completed, the product is precipitated by neutralization with phosphoric acid, hydrochloric acid, sulfuric acid, etc., and this product is dissolved in an organic solvent. The organic solvent must be one that does not dissolve water but can dissolve tetramethylol compounds of bisphenols, and methyl isobutyl ketone (MIBK) is used. the product
When dissolved in MIBK, the product is separated into an organic component mainly consisting of 4-methylolated bisphenols that dissolves in MIBK, and water produced as condensation water in the first step reaction that does not dissolve in MIBK. Ru. After removing this water, the organic components are washed 3 to 6 times with pure water. Unreacted formaldehyde that did not contribute to the reaction in the first step is removed while being dissolved in the separated water, and is further dissolved and removed by washing with this pure water, so that almost all unreacted formaldehyde remains in the organic components. It will not be included. Further, impurity ions are also removed and no longer contained. After cleaning,
MIBK was removed under reduced pressure and the bisphenols were
An organic component mainly composed of methylolated products is obtained in pure form. The second step is carried out by reacting the tetramethylolated bisphenols thus obtained with phenol or cresol as the phenol in the presence of a catalyst. Further, oxalic acid is generally used as a catalyst. The amount of phenols is preferably 8.0 to 12.0 moles per 4-methylol of bisphenols, and the amount of oxalic acid as a catalyst is 4 times the amount of 4-methylol of bisphenols.
The amount is preferably 0.1 to 0.01 times the mole of the methylol compound. The temperature required for the reaction is 80 to 120°C, and the time required for the reaction is 10 to 12 hours. After the reaction is completed, 165
Decompose the oxalic acid by increasing the temperature to about 80℃.
Perform vacuum distillation at ~120°C to remove water and unreacted phenols. In this way, a curing agent containing polyhydric phenols represented by the structural formula [A] as a main component can be obtained by reacting a phenol with a tetramethylol compound of bisphenols. If the reactants in the first step are not washed, the reaction in the second step is carried out with unreacted formaldehyde remaining, and the formaldehyde reacts with the phenols, producing low-molecular compounds as by-products. Although it is produced in large quantities and has a high content of low-molecular compounds, it can be obtained as a curing agent for polyhydric phenols with a low content of low-molecular compounds by washing the reactant in the first step as described above. It becomes possible. The curing agent for polyhydric phenols thus obtained contains bisphenol A, which is disclosed as a curing agent for epoxy resins in JP-A-59-8719 and JP-A-57-83521, in its skeleton. It has been found that epoxy resin compositions obtained by using this curing agent have excellent heat resistance, adhesive properties, and fast curing properties. It was given to me. In this polyhydric phenol curing agent, it is desirable that the content of a low molecular weight component having two or less benzene nuclei is 7% by weight or less. By having such a low content of low molecular weight components, the above-mentioned properties of the polyhydric phenol curing agent can be further improved. The present inventors further investigated the use of this polyhydric phenol curing agent in combination with other curing agents, and found that it is possible to use a specific amine curing agent that has an electron-withdrawing group in the molecule. The inventors have now discovered that they can provide an epoxy resin composition with even more excellent rapid curing properties and adhesive properties without deteriorating its properties. Such amine curing agents include dihalogenated diaminodiphenylmethane, diaminodiphenyl sulfone, 1,3-propanediol-di-paraaminobenzoate, dicyandiamide,
Examples include tetrahalogenated diaminodiphenylmethane. However, when these amine-based curing agents were investigated, it was found that industrially usable dichlorodiaminodiphenylmethane has a problem of toxicity; Other methods have the problem of being very expensive and not practical due to cost considerations. Diaminodiphenyl sulfone also has the problem of poor processability of epoxy resin compositions. Furthermore, 1,3-propanediol-di-para-aminobenzoate is very expensive and contains only a small amount of nitrogen, so when trying to make an epoxy resin composition flame retardant, it is necessary to add a large amount of flame retardant. However, when such a large amount of flame retardant is used, a new problem arises in that the heat resistance of the epoxy resin composition decreases. In the case of dicyandiamide, increasing the proportion used in combination will result in a decrease in heat resistance, so the proportion used in combination must be reduced, and the effect of combined use will be lower than that of other amine curing agents with other electron-withdrawing groups. The problem is that it is smaller in comparison. On the other hand, tetrahalogenated diaminodiphenylmethane has low toxicity and does not deteriorate various properties even if the proportion used in combination is increased, and since it has a halogen component in addition to nitrogen, it is less toxic than epoxy. This also has the advantage that only a small amount of flame retardant can be used when making the resin flame retardant. Moreover, it is not expensive, and in the present invention, this tetrahalogenated diaminodiphenylmethane is selected and used as an amine-based curing agent to be used in combination with the polyhydric phenol curing agent of formula [A]. A specific example of the tetrahalogenated diaminodiphenylmethane is tetrachlordiaminodiphenylmethane. Of course, in addition to using the polyhydric phenol curing agent and this tetrahalogenated diaminodiphenylmethane in combination, it is possible in the present invention to further use other curing agents or curing accelerators. The total amount of the polyhydric phenol curing agent and the tetrahalogenated diaminodiphenylmethane used is preferably in the range of 0.5 to 1.5 equivalents per equivalent of the epoxy resin. Outside this range, the properties of the cured product tend to deteriorate. Further, the ratio of the polyhydric phenol curing agent to the tetrahalogenated diaminodiphenylmethane is preferably such that the equivalent ratio of hydroxyl group to active hydrogen group is 1:9 to 7:3. If the hydroxyl equivalent is less than this ratio, the effect of imparting quick curing properties will not be significant, and if the hydroxyl equivalent is greater than this ratio, the effect of improving adhesion will not be significant. Therefore, a curing agent containing polyhydric phenols of formula [A] as the main component and a low content of low molecular weight compounds having 2 or less benzene nuclei, and tetrahalogenated diaminodiphenylmethane are each added to the epoxy resin. By doing so, the epoxy resin composition of the present invention can be obtained, but if necessary, a solvent, a curing accelerator, a filler, a base material, a mold release agent, a surface treatment agent, a flame retardant, etc. may be further added. can do.
As the solvent, acetone, methyl ethyl ketone, methyl cellosolve, methyl isobutyl ketone, dimethyl formamide, etc. can be used, and as the curing accelerator, tertiary amines, imidazoles, phosphines, DBU and its derivatives, etc. can be used. can. In the epoxy resin composition thus obtained, the curing agent mainly composed of polyhydric phenols of the formula [A] is prepared with a small content of low molecular weight components, and moreover, the curing agent contains tetravalent phenols. Since halogenated diaminodiphenylmethane is used in combination, it has low toxicity, good heat resistance and adhesion, and excellent fast curing properties, and can be obtained at low cost. Next, the present invention will be explained in more detail with reference to Examples. Example An aqueous solution prepared by dissolving 4.8 parts by weight of sodium hydroxide in 20 parts by weight of water was added to 27 parts by weight of Bisphenol A and stirred. After bisphenol A had dissolved to some extent, 39 parts by weight of 37% formalin was gradually added. After reacting for 2 hours at a reaction temperature of 40°C,
It was cooled and neutralized using dilute hydrochloric acid. The precipitated product was dissolved in 100 parts by weight of MIBK and separated into an aqueous layer and an organic layer. Furthermore, the separated organic layer was washed four times with 100 parts by weight of pure water, and then MIBK was removed by vacuum distillation. When the structure of the product thus obtained was analyzed by NMR, it was found to be a tetramethylol compound of bisphenol A.
The obtained 4-methylolated product of bisphenol A was
20 parts by weight, 54 parts by weight of phenol, oxalic acid
0.07 parts by weight and 50 parts by weight of water were used to react at 80°C for 10 hours. After the reaction was completed, the temperature was raised to 165°C and maintained at this temperature for 1 hour, followed by vacuum distillation at 120°C to remove water and unreacted phenol. When the structure of the obtained product was analyzed by GPC and NMR, it was found that the main product was a compound having the above structure [A] (X=CH ₂ , Y=H in formula [A]), It was found that the low molecular weight component having 2 or less benzene nuclei was contained in an amount of 5% by weight or less. The polyhydric phenol curing agent obtained in this way and tetrachlordiaminodiphenylmethane (TCDAM) having the following structural formula [B] as a tetrahalogenated diaminodiphenylmethane curing agent
An epoxy resin varnish was prepared by blending the following. The formulation of the epoxy resin varnish is shown below. (Parts by weight) ● Brominated bisphenol A type epoxy resin (epoxy equivalent: 515) ...85 ● Cresol novolak type epoxy resin (epoxy equivalent: 215) ...15 ● Polyhydric phenol curing agent obtained above (OH equivalent
112) …13 ●TCDAM (H equivalent: 84) …10 ●2-ethyl-4-methylimidazole …0.05 ●Methyl cellosolve …20 ●Methyl ethyl ketone …80 The gel time of this epoxy resin varnish at 160°C is 7 minutes 0 seconds. Ta. Then, a glass cloth with a unit weight of 103g/ ^m2 was impregnated with this epoxy resin varnish.
A prepreg with 50% resin content was obtained by drying for 6 minutes in a dryer at 155°C. Layer 4 sheets of this prepreg, and add thickness above and below.
A copper-clad laminate was produced by stacking 0.018 mm copper foils, placing them between a hot platen at 180° C., and heating and pressing them at 40 Kg/cm ² for 90 minutes. Comparative Example 1 An epoxy resin varnish was prepared using the polyhydric phenol curing agent obtained in Example as a curing agent and without using tetrahalogenated diaminodiphenylmethane in the following formulation. (Parts by weight) ● Brominated bisphenol A type epoxy resin (epoxy equivalent: 515) …85 ● Cresol novolak type epoxy resin (epoxy equivalent: 215) …15 ● Polyhydric phenol curing agent (OH equivalent: 112) …26 ●2 -Ethyl-4-methylimidazole...0.05 ●Methyl cellosolve...20 ●Methyl ethyl ketone...80 The gel time of this epoxy resin varnish at 160°C was 9 minutes 0 seconds. Then, a glass cloth with a unit weight of 103g/m ² was impregnated with this epoxy resin varnish.
A prepreg with 50% resin content was obtained by drying for 8 minutes in a dryer at 155°C. A copper-clad laminate was produced in the same manner as in the example below. Comparative example 2 94 parts by weight of phenol, 24 parts by weight of paraformaldehyde
Part by weight and 1 part by weight of oxalic acid were heated at 120°C for 4 hours, and then heated to 165°C.
It was held at 165°C for 1 hour. Next, water and phenol were removed under reduced pressure while maintaining the temperature at 125°C, and unreacted phenol was further removed by steam distillation to obtain a phenol novolak resin. The hydroxyl equivalent of this phenol novolac resin is 108,
The content of low molecular weight compounds having two or less benzene nuclei was 12 to 14% by weight. An epoxy resin varnish was prepared in the same manner as in Comparative Example 1, except that 25.1 parts by weight of this phenol novolak resin was blended as a curing agent instead of ``26 parts by weight of polyhydric phenol curing agent'' in Comparative Example 1. Further, a copper-clad laminate was prepared in the same manner as in Comparative Example 1. Comparative Example 3 An epoxy resin varnish was prepared in the same manner as in Comparative Example 1, except that 20 parts by weight of TCDAM was used in place of "26 parts by weight of polyhydric phenol curing agent" in Comparative Example 1, and then in the same manner as in Comparative Example 1. A copper-clad laminate was created. However, in this case, the gel time of the epoxy resin varnish at 160°C was 55 minutes, but the prepreg was created by drying it in a dryer at 155°C for 50 minutes. Comparative Example 4 An epoxy resin varnish was prepared in the same manner as in Comparative Example 1, except that 2.5 parts by weight of dicyandiamide was used in place of "26 parts by weight of polyhydric phenol curing agent" in Comparative Example 1, and then in the same manner as in Comparative Example 1. A copper-clad laminate was created using the following steps. However, in this case, the gel time of the epoxy resin varnish at 160℃ is 10 minutes.
Since the drying time was 30 seconds, the prepreg was prepared by drying for 9 minutes in a dryer at 155°C. Furthermore, methyl cellosolve and methyl ethyl ketone, which were the solvents used to prepare the epoxy resin varnish, were used as a mixed solution of 38 parts by weight and 62 parts by weight. Comparative Example 5 "Polyvalent phenol curing agent 26" in Comparative Example 1
An epoxy resin varnish was prepared in the same manner as in Comparative Example 1, except that 22 parts by weight of the polyhydric phenol curing agent prepared in Example 1 and 4 parts by weight of bisphenol A were blended as curing agents instead of "parts by weight". ,
Furthermore, a copper-clad laminate was produced in the same manner as in Comparative Example 1. The following table shows the results of measuring the fast curing properties of the epoxy resin varnishes of the above Examples and Comparative Examples 1 to 5 and the characteristics of copper-clad laminates obtained using these epoxy resin varnishes. The method for measuring each characteristic in the table below is shown below. (1) Fast curing property This was achieved by heating an epoxy resin varnish to 160°C and measuring the time until gelation occurred. (2) Thermal decomposition onset temperature A test piece was prepared by removing the copper foil from a copper-clad laminate by etching and grinding it into powder using a file. This was done by measuring the temperature at which thermal decomposition begins in a nitrogen atmosphere. (3) Moisture absorption and solder heat resistance A test piece was prepared by removing the copper foil from a copper-clad laminate by etching, and the test piece was immersed in water at 100°C for 8 hours, and then placed in a solder bath at 260°C. The test was conducted by dipping the glass cloth for 20 seconds, and the case where no lifting of the glass cloth or interlayer peeling occurred was considered to be a pass. (4) Glass transition temperature (Tg) Measurement was carried out using a copper-clad laminate with the copper foil removed by etching as a test piece using a solid viscoelasticity measuring device manufactured by Iwamoto Seisakusho. . (5) Copper foil peel strength The peel strength of a 0.018 mm thick copper foil on a copper-clad laminate was measured in accordance with JIS-C-6481.

【table】

〔Effect of the invention〕

As described above, the present invention uses an epoxy resin containing tetrahalogenated diaminodiphenylmethane as a curing agent and a general formula of (In the formula, X is CH ₂ or C(CH ₃ ) ₂ , and Y is H
or CH ₃ and all four Y's may be the same or different. ), the curing agent containing polyhydric phenols as the main component is prepared with a low content of low-molecular components. There is no deterioration in properties due to low molecular weight components.
Furthermore, by using tetrahalogenated diaminodiphenylmethane as a curing agent, the toxicity is low.
The epoxy resin composition can be made into an inexpensive epoxy resin composition that has good heat resistance and adhesion as well as excellent fast curing properties.

Claims (1)

[Claims] 1. An epoxy resin containing tetrahalogenated diaminodiphenylmethane as a curing agent and a general formula of (In the formula, X is CH ₂ or C(CH ₃ ) ₂ , and Y is H
or CH ₃ , and all four Y's may be the same or different. ) A curing agent compound whose main component is a polyhydric phenol represented by: 2 The curing agent whose main component is polyhydric phenols is
The content of low molecular weight components with 2 or less benzene nuclei is 7.
% or less by weight of the epoxy resin composition according to claim 1.