JPH01108254A - Curable epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain the title homogeneous composition excellent in impact resistance and moisture resistance and suitable as, e.g., a semiconductor sealing material, by mixing a curable epoxy resin with a curable silicone rubber composition with the aid of a compatibilizer comprising a polyethermodified organopolysiloxane. CONSTITUTION:A curable epoxy resin (A) comprising an epoxy resin having at least two epoxy groups in the molecule, such as a bisphenol A glycidyl ether, a curing agent such as an amine or a phenol novolac resin and a cure accelerator such as imidazole is mixed with a moisture-curable silicone rubber composition (B) comprising a diorganopolysiloxane terminated with OH groups, an organosilane, fumed silica and a curing catalyst with the aid of a compatibilizer (C) comprising 0.1-10wt.%, based on the epoxy resin, polyether-modified organopolysiloxane which is a polydimethylsiloxane modified with a functional group having a strong affinity for the epoxy resin.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to curable epoxy resin compositions, and particularly to curable epoxy resin compositions modified with moisture-curable silicone rubber.

(Prior art) Epoxy resin compositions have not only electrical properties such as dielectric properties, volume resistivity, and dielectric breakdown strength, but also bending strength, compressive strength,
Due to its excellent mechanical properties such as impact strength, heat resistance, and adhesive properties, it is prized not only for adhesives and various composite materials, but also as an insulating material for various electrical and electronic parts.

However, recently, as electronic components have become thinner and smaller, and semiconductor chips have become larger due to increased semiconductor integration, cracks in package materials, silicon chip cracks, package tank cracks, wiring movement, and epoxy resin Problems such as cracks in the product itself, gaps between electrical/electronic parts and epoxy resin, and breakdowns caused by moisture infiltration through the gaps are becoming more and more serious.

Conventionally, as a method to improve such defects, (1) a method of adding a resin that imparts flexibility to an epoxy resin (for example, JP-A-54-81360, JP-A-57
-56954) (2) A method of blending a large amount of inorganic filler such as silica or alumina with a small coefficient of thermal expansion, (3)
Add and mix curable silicone rubber and carbon funk natural silane to curable epoxy resin,
A method has been adopted in which the crack resistance of a cured epoxy resin is improved by curing at the same time (Japanese Unexamined Patent Publication No. 55-3412).

However, although the first method is effective as a method for preventing the occurrence of cracks in the epoxy resin itself, it lowers the hardness and glass transition temperature when heated, which are the excellent properties of epoxy resin, and the high temperature of the epoxy resin. It had the disadvantage of impairing its characteristics. On the other hand, with the second method, although a cured product with a coefficient of thermal expansion close to the desired one can be obtained, the fluidity of the epoxy resin composition is significantly reduced. In addition, since the Young's modulus of the epoxy resin increases, it is difficult to expect much reduction in internal stress due to a reduction in the coefficient of thermal expansion.

In addition, in the third method, the curable silicone rubber is cured after being dispersed in the curable epoxy resin, so the curing reaction does not proceed completely and unreacted materials remain. There are disadvantages in that mold stains sometimes occur, printing performance on cured products deteriorates, and overcoating cannot be performed. These drawbacks are due to the fact that the thermosetting silicone resin composition is gelled in the form of dispersed particles under stirring while the gelation of the thermosetting resin composition is suppressed.
By subsequently curing the thermosetting resin composition, significant improvements can be made (Japanese Patent Application Laid-Open No. 56-14556
Although this method is excellent in that it can finely disperse the silicone resin in the thermosetting resin,
Since the thermosetting resin and the silicone resin have poor compatibility, the latter gradually floats to the surface, which naturally limits the uniformity of the cured product as a whole. These drawbacks are due to the fact that the epoxy resin and curing agent as well as the pre-cured linear organopolysiloxane blocks are
A thermosetting epoxy resin composition (Japanese Patent Application Laid-Open No. 58-219218) consisting of a cured polymer containing at least % by weight also exists.

Furthermore, in this case, the particulate dispersion to be dispersed must be obtained by pulverizing the cured product into particles, which is not only complicated but also difficult to narrow the particle size distribution. In that sense, the homogeneity of the cured product of the thermosetting epoxy resin made from the above composition is not necessarily sufficient, and in order to improve the compatibility with the epoxy resin, it is necessary to prepare a linear organopolysiloxane block. There is also a drawback that there is a limit to the modification of epoxy resin compositions because the degree of polymerization and content must be limited.

(Problems to be Solved by the Invention) Therefore, as a result of intensive studies to solve these conventional drawbacks, the present inventors found that polyether-modified organopolysiloxane is extremely effective as a compatibilizer for silicone rubber and epoxy resin. By using this, silicone rubber can be easily finely dispersed in epoxy resin, and a homogeneous and dense seabird structure can be realized without floating of silicone rubber. We have discovered what can be done and arrived at the present invention.

Therefore, an object of the present invention is to provide a homogeneous curable epoxy resin composition with improved impact resistance and moisture resistance.

(Means for Solving the Problems) The above objects of the present invention have been achieved by a curable epoxy resin composition containing a curable epoxy resin, a curable silicone rubber composition, and a polyether-modified organopolysiloxane as main ingredients.

The curable epoxy resin as the first component used in the present invention is a curable epoxy resin composed of an epoxy resin having two or more epoxy groups in one molecule and various curing agents. As long as it can be cured with various curing agents as described below, there are no particular restrictions on the molecular structure, molecular weight, etc., and it can be used by appropriately selecting from various conventionally known epoxy resins. . Examples of such materials include diglycidyl ether of bisphenol A, Ebibis type epoxy resin which is a polymer thereof, bisphenol F type epoxy resin, resorcinol type epoxy resin, tetrahydroxyphenylethane type epoxy resin, Talesol novolac. Examples include type epoxy resins, polyolefin type epoxy resins, alicyclic type epoxy resins, and halogenated products thereof.

In addition, when using the above-mentioned first component, there is no problem in using a monoepoxy compound in combination as appropriate, and examples of this monoepoxy compound include styrene oxide, cyclohexene oxide, propylene oxide, methyl glycidyl ether, ethyl glycidyl ether, phenyl glycidyl ether, Examples include allyl glycidyl ether, octylene oxide, and dodecene oxide. The first component is not necessarily limited to only one type, but may be used in combination of two or more types.

Examples of curing agents for epoxy resins include amine-based curing agents such as diaminodiphenylmethane, diaminodiphenylsulfone, metaphenylenediamine, phthalic anhydride,
Examples include acid anhydride curing agents such as pyromellitic anhydride and benzophenonetetracarboxylic anhydride, and phenol novolac curing agents having two or more hydroxyl groups in one molecule such as phenol novolac and talesol novolac. Even when used alone, these curing agents
More than one species may be used at the same time, but in any case, a sufficient amount is used to cure the epoxy resin.

In the present invention, various curing accelerators such as imidazole or its derivatives, tertiary amine derivatives,
Phosphine derivatives, cycloamidine derivatives, etc. can be used in combination.

The curable silicone rubber composition used in the present invention can be appropriately selected from known ones, but the curing of the silicone rubber and the epoxy resin can be controlled independently, and the epoxy resin In order to avoid the influence of the resin curing accelerator as a catalyst poison, it is particularly preferable to use moisture-curable silicone rubber.

The moisture-curable silicone rubber composition used in the present invention is
For example, molecules represented by (where R1 and R1 are the same or different unsubstituted or substituted monovalent hydrocarbon groups, and m is an integer of 5 or more) can be used by appropriately selecting from known ones. 100 parts by weight of diorganopolysiloxane with both chain ends capped with hydroxyl groups, B) - Formula R"a-as i X@ (where R3
is an unsubstituted or substituted monovalent hydrocarbon group, X is a hydrolyzable group, a is a positive number of 2<a<4) or 0.5 to 30 parts by weight of a partial hydrolyzate thereof ) 0 to 100 parts by weight of hiemed silica, and D) 0 to 10 parts by weight of a curing catalyst.

The diorganopolysiloxane as the component A) is conventionally known as a raw material for silicone rubber in which both ends of the molecular chain are blocked with hydroxyl groups. is an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, an alkenyl group such as a vinyl group or an allyl group, an aryl group such as a phenyl group,
The same or different unsubstituted or substituted monovalent carbons selected from cycloalkyl groups such as cyclohexyl groups, or groups in which part or all of the hydrogen atoms bonded to the carbon atoms of these groups are substituted with halogen atoms, cyano groups, etc. The hydrogen group m is an integer of 5 or more. With the diorganopolysiloxane represented by the above formula, if the clay content is less than 100 cS, a cured elastic body with excellent physical strength cannot be obtained; Since the clay is too high and the workability during use is poor, the clay preferably has a range of 100 to 1,000.000 cs, particularly preferably a range of 3,000 to 50,000 cs.

Further, although this diorganopolysiloxane has a substantially linear structure, a siloxane having a three-dimensional structure may be introduced in a small amount.

Next, the component B) constituting the composition of the present invention is the above-mentioned A
) is a known curing agent that reacts with diorganopolysiloxane as a component at room temperature to cure it, and as described above, this curing agent has the formula R'4-as i
R3 is the same unsubstituted or substituted monovalent hydrocarbon group as R1 and R1, and X is an acyloxy group, an alkoxy group, a ketoxime group, an alkenyloxy group, an amino group, an aminooxy group, an amide group, and a hydrolyzable group selected from the group, a is a positive number of 2 × 4, an organosilane or a partially hydrolyzed product thereof;

This organosilane must have two or more hydrolyzable groups in its molecule.

Such organosilanes include, for example, CHZ
-CH3i (OCOCH3)s, CH3S i
(OCOCH3)x, CH, oxCH3i(0CH3)s CHs S t(OCH:l)s, CH3S
i (ON (Cg Hs) t) s
, and partial hydrolysates thereof. If the amount of component B) added is less than 0.5 parts by weight per 100 parts by weight of component A), the curing and crosslinking reaction of this composition in the presence of moisture will be insufficient, and 3
If the amount is more than 0 parts by weight, the cured product will become too hard.
．． It is necessary to range from 5 to 30 parts by weight, and a particularly preferred range is from 2 to 15 parts by weight.

Further, fumed silica as component C) in the composition of the present invention is conventionally known as a raw material for silicone rubber. Although this material is an optional component, since it serves as a reinforcing material to impart mechanical strength to the cured product obtained from the composition of the present invention, it is preferable that its specific surface area is at least 50 nf/g. . Moreover, this material may be surface-treated with dimethylpolysiloxane, tetramethyldisilazane, dimethylchlorosilane, or the like. The amount of fumed silica to be added should be 3 to 100 parts by weight, as if it is less than 3 parts by weight, the reinforcement will be insufficient, and if it is more than 100 parts by weight, the cured product will become too hard. Parts by weight are particularly preferably in the range from 3 to 25 parts by weight.

In addition, component D) is a catalyst that promotes the reaction between component A) and component B), such as lead-2-ethyl octoate, dibutyltin diacetate, dibutyltin dilaurate, and other organic carboxylic acids. Metal salt; tetrabutyl titanate, tetra-2-ethylhexyl titanate,
Organic titanate esters such as organosiloxy titanium, organic titanium compounds such as β-carbonyl titanium, N-
(Trimethoxysilylpropyl) Aminoalkyl group-substituted alkoxysilanes such as ethylenediamine, amine compounds such as hexylamine, and their salts Dialkylhydroxylamines such as dimethylhydroxyamine and diethylhydroxylamine; tetramethylguanidylpropyltrimethoxysilane, etc. Guanidine compounds can be mentioned.

In the present invention, the above component D) is not an essential component,
If necessary, it may be added in an amount of 10 parts by weight or less per 100 parts by weight of component A).

The composition of the present invention can be obtained by mixing predetermined amounts of the above-mentioned components A) to D) under anhydrous conditions, and if necessary, various plasticizers, colorants such as pigments, etc. Heat or cold resistance improver, flame retardant imparting agent, fungicide,
Known additives such as decolorizing agents, silane coupling agents, adhesion improvers, etc. can be blended.

The above-mentioned epoxy resin and silicone rubber composition have a so-called water-oil relationship, and it is extremely difficult to blend them, and this difficulty becomes especially severe as the hydrocarbon moiety contained in the above-mentioned silicone rubber is small. Even if the epoxy resin is forcibly blended, separation between the two cannot be avoided until the epoxy resin is cured.

Therefore, in the present invention, a special surfactant having a strong interfacial tension lowering ability is used as a compatibilizer to prevent the separation of the two. Such a special surfactant is polydimethylsiloxane modified with a functional group that has a strong affinity with epoxy resins, but in the present invention, among these, polyether-modified organopolysiloxane is particularly preferred. is preferred. Such modified organosiloxanes include monocatalytic, R' b R' S i O1, 1> [wherein R4 is *CHt )104Ct Ha 0)-k(C3Ha
Oat Rゝ, where RS is an atom or group selected from a hydrogen atom, a lower alkyl group, an acyl group, k and l
are respectively O or a positive integer, a group represented by k+f≠0, or -(CH, ts (N HCHz CHz ) -N
Hz (where m is O or 1), R
' is the same as R1 used in the section of component A), and b and C are positive numbers (however, Q<b+c<4). It is preferable to use an organopolysiloxane represented by the following.

Among these, R4 is (CHz)s0(CzHaO)-m4Cx
HhO, R5 is particularly preferred in that it can also improve the impact resistance after curing.

(Function) These compatibilizers can be used alone or in combination of two or more types, but in any case, by adding a certain amount or more of these compatibilizers, the epoxy resin and The affinity of the silicone rubber composition can be increased. This is thought to be because the polyether part has a strong affinity with the epoxy resin, while the polydimethylsiloxane part is compatible with the silicone rubber composition.

Although this concept itself is not different from the conventional one, the effect is surprising in the present invention using the above-mentioned compatibilizing agent, as will be clearly shown in the examples below.

The amount of the compatibilizer used can be adjusted appropriately depending on the type of compatibilizer, but for the epoxy resin,
Add 0.1% to 10% by weight. If it is less than 0.1% by weight, the effect as a compatibilizer will be insufficient, and 10% by weight.
If the amount is more than 0.5% by weight, the compatibilizer may ooze out after curing or the physical properties of the cured product may deteriorate, which is undesirable.A particularly preferable addition amount is 0.5% to 5% by weight.

There is no particular restriction on the method of mixing the curable epoxy resin, the curable silicone rubber composition, and the compatibilizing agent. The curing agent for the epoxy resin, which is preferably added to the silicone rubber composition and the catalyst for curing, is preferably added after uniform dispersion of the curable silicone rubber is substantially completed.

In particular, when moisture-curable silicone rubber is used as the curable silicone rubber, energy costs can be reduced during manufacturing, and the curing of the silicone rubber and the curing of the epoxy resin can be controlled completely independently. This has the advantage that the curing accelerator of the epoxy resin does not hinder the curing of the silicone rubber. Therefore, it is a preferred practice of the present invention to use a moisture-curable silicone rubber as the curable silicone rubber. Furthermore, in this case, the curing of the silicone rubber composition can be completed without proceeding with curing of the epoxy resin. Therefore, not only is the manufacturing process simple, but the particle size of the silicone rubber particles can be made uniform and small.

The silicone rubber-containing cured epoxy product produced as described above has improved impact resistance and moisture resistance compared to conventional products, and is therefore particularly useful as a semiconductor encapsulation material.

(Effects of the Invention) According to the present invention, the silicone rubber contained in the obtained cured product has sufficiently fine particles evenly distributed, and the affinity between the silicone rubber and the epoxy resin is good. As a result, impact resistance and moisture resistance can be significantly improved.

(Examples) The present invention will be described in more detail below with reference to Examples, but the present invention is not limited thereto.

In Example 1, Epikote 828 was used as the curable epoxy resin and silicone oil KF96 (manufactured by Shin-Etsu Chemical) was used.
The ability of various modified polydimethylsiloxanes to reduce interfacial tension was investigated.

Figure 1 shows the interfacial tension γ of the epoxy resin/modified organopolysiloxane mixed system with respect to silicone oil. In Figure 0, which is a graph showing the relationship between epoxy-modified organopolysiloxane X-60X-6O-164 (EP) and modified organopolysiloxane concentration, ■ is polyether modified organopolysiloxane KFO351 (
ETMPS) (all modified organopolysiloxanes are manufactured by Shin-Etsu Chemical Co., Ltd.).

As is clear from the results in Figure 1, for all modified organopolysiloxanes, 7rt decreases with the addition concentration, but there are large differences in the amount of each reduction, especially in the case of polyether-modified organopolysiloxanes. It is clear that this is significant.

Further, the relationship between the interfacial tension γ18 and the concentration C is expressed as TIz, or+z, tt-γ+1@-γ+tltis.

Here γ1. . represents r +t-, r tt at C-0, and tMIM7. ! , and K is the surfactant coefficient.

The values of K obtained by plotting the logarithm of the left side of the above equation against the concentration were as shown in Table 1.

From the results shown in Table 1, it was found that the ether-modified organopolysiloxane with the maximum K was the most effective as a compatibilizer.

Next, in order to see how the action of the compatibilizer changes depending on the type of polyether-modified organopolysiloxane used as the compatibilizer, a moisture-curable silicone rubber composition ( Shin-Etsu Chemical K
E10B) was used to evaluate three types of polyether silicones (all manufactured by Shin-Etsu Chemical Co., Ltd.) in the same manner as above. The results are shown in FIG. 2 and Table 2.

As is clear from Table 2, Figures 1 and 2, the γ18 of pure epoxy resin is 8.99d at the silicone oil interface.
It decreased from yn/am to 6.48 dyn/cm, but
This is thought to be because the crosslinking agent contained in RTV silicone as a base for vulcanization increases its affinity with the epoxy resin. In addition, KF351 and KF355, in which the polyether block is only polyethylene oxide, have TI! It was also found that KF615 containing polypropylene oxide in the polyether block exhibited strong surface activity.

KF615A, which was found to have the greatest compatibilizing effect through the above evaluation, was used as the compatibilizer, Epicoat 828 was used as the curable epoxy resin, and bis-p-aminocyclohexylmethane (PACM) was used as the curing agent. , 4.4"-
A blend was prepared using diaminodiphenylmethane (DDM) and KEloB as the silicone rubber as follows.

Add 5 g (1% by weight) of the above KF615AO as a compatibilizer to 49.5 g of curable epoxy resin (Epicoat 82B).
was added, thoroughly stirred to defoam, heated to 50°C, stirred vigorously with a stirrer, and added a catalyst-containing curable silicone rubber (KEloB). The rubber particles were dispersed and a milky white color was formed. It became a viscous liquid. After defoaming the obtained liquid, an equivalent amount of 4.4'-diaminodiphenylmethane (DDM) as a hardening agent was added, and the mixture was further stirred and defoamed, poured into a mold, and heated at 165°C for 2 hours to cure.

From the obtained cured product, according to JISK'7110,
Cut out a test piece of 2.7 x 12.7 x 63.6 mm,
A notch with a depth of 2.54 mm was made in the center, and an Izot impact test was conducted.

FIG. 3 shows the relationship between the impact fracture energy (E) and the amount of RTV silicone rubber added (phr).

This result demonstrates that the impact resistance of the cured epoxy product was significantly improved by the present invention.

In addition, 5 phr of RTV silicone rubber was added, and PACM
When the fractured surface of the system cured using (P-aminocyclohexylmethane) was observed by SEM, it was confirmed that rubber particles of 1 to 20 μm were dispersed over the entire surface. It was confirmed that syn was sufficiently effective as a compatibilizer. Furthermore, since small pieces of epoxy resin were observed to be attached to the surface of the rubber particles, it was possible to infer that there was considerable bonding force at the interface between the epoxy resin and the silicone rubber particles.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the interfacial tension of an epoxy resin/modified organopolysiloxane mixed system to silicone oil and the modified organopolysiloxane concentration. FIG. 2 is a graph showing the relationship between the interfacial tension of an epoxy resin/polyether-modified organopolysiloxane mixed system for RTV silicone rubber and the polyether-modified organopolysiloxane concentration. FIG. 3 is a graph showing the relationship between impact fracture energy and the amount of RTV silicone rubber added. Patent applicant Shin-Etsu Chemical Co., Ltd.

Claims (1)

[Scope of Claims] 1) A curable epoxy resin composition whose main ingredients are a curable epoxy resin, a curable silicone rubber composition, and a polyether-modified organopolysiloxane. 2) The curable epoxy resin composition according to claim 1, wherein the curable silicone rubber composition is a moisture-curable silicone rubber composition.