EP0914362A1

EP0914362A1 - Modified epoxysiloxane condensate, process for producing the same and its use as low-stress casting resins in the electronic and electrotechnical industry

Info

Publication number: EP0914362A1
Application number: EP97932704A
Authority: EP
Inventors: Klaus Höhn; Ernst Wipfelder
Original assignee: Siemens AG
Current assignee: Ams Osram International GmbH
Priority date: 1996-07-26
Filing date: 1997-06-23
Publication date: 1999-05-12
Also published as: WO1998004609A1; DE19630319C1; CN1226263A; US6248854B1; JP3266275B2; JP2000500811A; TW494112B

Abstract

An epoxysiloxane condensate is modified by an in-situ reaction with an organic, optionally di-or multifunctional compounds. The disclosed process makes it possible to vary in an easy and economic manner the properties of epoxysiloxane condensates, epoxide resins mixtures and formulations, and of the moulded bodies produced therewith.

Description

description

Modified epoxy siloxane condensate, process for its production and its use as a low-stress casting resin for electronics and electrical engineering

The invention relates to an epoxysiloxane condensate which is modified by an in-situ reaction with an organic compound, preferably a difunctional or multifunctional compound.

P 43 28 465 discloses a process for the preparation of epoxysiloxane condensates, in which epoxysiloxanes are obtained by condensation of epoxy-functional alkoxysiloxanes with silanols. These epoxysiloxane condensates can either be used directly as casting resins or for mixing with epoxy resins for electronics applications. The cast resin systems with epoxy-containing siloxanes are also suitable for the production of temperature-stable and thermomechanically resilient molded materials. The epoxysiloxane condensates have a general structure which can be derived from the epoxyalkoxysilanes used and the silanols used and from chemical analyzes. In order to further adapt the epoxysiloxane condensates to the specific fields of application, it is desirable to be able to vary the electronic and steric conditions and also the polarity of the resins within wide limits. The chemical modification of the condensates makes tailor-made casting resins available that can be flexibly adapted to the technical requirements during processing and later operation.

The object of the present invention is therefore to provide a method for modifying epoxysiloxane condensates and modified epoxysiloxane condensates in which the chemical-functional structure of the products can be adjusted within wide limits. General knowledge of the invention is that in the alkoxy-silanol condensation the ratio of reactive silanol groups to the alkoxy groups of the epoxy-functional siloxane can be adjusted within wide limits such that not all alkoxy groups are consumed by silanols.

These alkoxy groups, which are still free after the reaction with the silanols, can be reacted with organic compounds which are as multifunctional as possible in a further condensation step. The physico-chemical properties of the casting resins can be influenced in a targeted manner by incorporating various organic compounds. The possibly contained further functionalities of the organic compounds (also called modifiers) serve as additional connecting points for the siloxane casting resins obtained in the epoxy resin crosslinking. The epoxysiloxanes can be built into the epoxy resin network even more firmly.

The invention relates to a modified epoxysiloxane condensate, obtainable by the following condensation steps

a) condensation of an epoxyalkoxysiloxane of the general structure 1 with a silanol of the general structure 2

in which

R ^{1 represents} an alkyl radical with 1 to 22 C atoms or an aryl radical,

R ^{2 is} a glycidyloxyalkyl, epoxyalkyl or an epoxycycloalkyl radical, the two radicals

R ³ independently of one another represent OR or R or a further alkyl or aryl radical, R ^{4 represents} alkyl or aryl, the radicals

R ^{5 are} independently OH or R ⁴ and n is an integer greater than 1

and

b) condensation of the alkoxy group-containing thus obtained

Epoxysiloxane condensate with a stoichiometric amount of an organic compound with a linear, branched or cyclic, optionally aromatic, carbon backbone of 1 to 24 carbon atoms and at least one condensable functional group.

The present invention furthermore relates to a process for modifying epoxysiloxanes, in which in a first condensation step a) an epoxysiloxane 1 is condensed with a silanol 2, 1 and 2 being the compounds indicated above, and after reaction of the silanol 2 in a further condensation step

b) the alkoxy group-containing epoxysiloxane condenser thus obtained is condensed in situ with an organic compound having a linear, branched or cyclic and optionally aromatic carbon backbone of 1 to 24 carbon atoms.

Finally, the present invention also relates to the use of the epoxysiloxane condensate modified according to the invention for blending with common epoxy resins. The point in time at which the mixing with the epoxy resin takes place can be arbitrarily within, before and after the reaction sequence, a) condensation of 1 with 2, then b) condensation of the alkoxy group-containing epoxysiloxane condensate obtained with an organic, optionally di- or multifunctional, Connection.

Advantageous embodiments of the invention result from the subclaims and subclaims, as well as from the description and the examples.

The process according to the invention can be carried out in a simple one-pot reaction under normal conditions with regard to atmosphere and pressure and therefore with a minimal outlay on the process in a short time. The first product obtained is a mixture of different siloxanes, which are the condensate of epoxyalkoxysilane 1 with silanol 2. In this first condensation reaction, an Si-O-Si bond is formed from the alkoxy group of the epoxysilane and the OH group of the silanol with elimination of the corresponding alkyl alcohol. The compound containing this Si-O-Si bond is called an epoxysiloxane condensate. Since not all available alkoxy groups of 1 in the first condensation step are used, they serve as reaction centers for the second condensation step.

According to the invention, the second reaction step is carried out in situ in the one-pot reaction from 1 and 2 with a condensable, optionally di- or polyfunctional, organic compound with a linear, branched or cyclic and optionally aromatic carbon backbone of 1 to 24 carbon atoms and as a functional one Groups hydroxyl, epoxy, ester, lactone, lactam, halogen and / or pseudohalogen functions and / or unsaturated CC bonds as well as spiro and / or bicycloorthoester and / or spirocarbonate groups are reacted. This is preferred second process step is only carried out when the silanol used for the first process step has been used up as completely as possible. For this purpose it can be advantageous to use the silanol in a deficit for the first condensation step.

The epoxyalkoxysilane 1 used as the starting compound carries 1 to 3 condensable alkoxy groups (OR and R ³ ). The radical R ¹ is arbitrary, but is preferably an alkyl radical having 1 to 8 carbon atoms, since the reactivity of the group to be split off during the condensation decreases with increasing chain length of the alkyl radical. The most reactive starting compounds are therefore the epoxymethoxysilanes. Because of the toxicological harmlessness of the split-off ethyl alcohol, ethyl can also be preferred as the alkyl group. Since the alcohols or low-molecular cleavage products released during the condensation are preferably removed from the reaction mixture, the shorter-chain alkyl radicals in which the alcohols or cleavage products resulting therefrom have a relatively lower boiling point and are therefore easier to separate off are preferred.

Because of the easier availability, monomeric epoxyalkoxysilanes 1 are preferred, but the reaction is in principle also possible with correspondingly longer-chain, higher molecular alkoxysiloxanes.

Correspondingly longer-chain silanols 2 are more readily available which have OH groups in the α-position, α- and τu-position or in the chain as reactive groups. The further organic group R ⁴ bound via SiC is not critical with regard to its selection and can be any alkyl or aryl radical.

The index "n", which determines the number of siloxane units in the silanol 2, can represent any number greater than 1, preferably between 1 and 100. With increasing n, for reasons of incompatibility, homogeneous reactions cannot be carried out and the reaction rate increases even with increased Temperatures clearly decrease, so that advantageously n is chosen between 1 and 12. Depending on the remaining radicals, however, with increasing chain length there can be an increasing incompatibility of the condensation products with epoxy resins, which later require their use as a resin component in a mixture with these

Can make epoxy resins difficult or impossible.

The radical R of the starting compound 1 containing epoxy or glycidyloxyalkyl groups is bonded to silicon via a carbon atom and is otherwise freely selectable. Depending on the availability of the corresponding epoxyalkoxysilane, R can be a glycidyloxyalkyl, an epoxyalkyl, glycidyloxyaryl, epoxyaryl or an epoxycycloalkyl group. The corresponding glycidyloxy compounds which are obtained by condensation of correspondingly reactive compounds with epichlorohydrin are readily available.

Depending on the reactivity of the starting materials, which can be electronically and sterically hindered, a condensation catalyst may be required to support the condensation. With regard to the condensation itself, there are no restrictions for the catalyst, so that any biger condensation catalyst is suitable. Taking into account the preferred or intended use of the product as a resin component for reactive resins, however, the catalyst is selected so that the epoxy group is preserved as much as possible during the condensation. A catalyst that is ideal in this regard therefore reacts neither very basic nor very acidic, ideally neutral.

For the second condensation following the first condensation, the optionally difunctional or multifunctional organic compound is added in a stoichiometric amount with respect to the alkoxy functions still present. After a short time, the liberation of a generally volatile alkoxy alcohol, in the case of a methoxy compound, for example methanol, can be observed.

The condensation of the starting materials with the epoxysiloxane condensate can take place as a solution in suitable solvents, for example in hydrocarbons and / or in aromatic hydrocarbons and ethers or the like. To the

However, the epoxy resins intended for mixing can also be diluted. It is also possible to carry out the condensation as a bulk reaction without solvent. In order to obtain only clear and transparent products, the condensation is catalyzed and carried out as a bulk reaction.

The condensation can take place in an open reaction vessel and is carried out with an increase in temperature. Preferred condensation temperatures are between 80 and 150 ° C.

Volatile reaction products are preferably driven off, for example by blowing in or passing an inert gas (for example nitrogen). This increases the shelf life and stability of the product itself or its mixing with reactive resins. The composition of the modified epoxysiloxane condensate obtainable by the process depends first of all on the reaction conditions and on the stochiometry of the batches. For the alkoxy-silanol condensation, the silanol functions are added in a deficit, so that it is ensured that, after the first condensation step, free alkoxy functions are available for the second condensation step. The deficit is to be dimensioned such that at least one alkoxy function of the epoxysilane 1 is consumed in the condensation step.

The condensation product formed in the first stage is, as is known from the prior art, a colorless, transparent oil. The organic, optionally di- or multifunctional compound is now added stoichiometrically, i. H. for each remaining alkoxy function on the expoxysiloxane condensate, exactly one condensable function of the organic compound is expected. A transesterification then takes place, so that the organic compound is bound to the epoxysiloxane condensate via the oxygen and possibly also has a further free functional group.

An excess of organic compound can be removed after the reaction in the heat in vacuo. No further functional groups are initially reacted in the resin production. The modified epoxy-siloxane condensate according to the invention therefore has further functional groups and can be described as “more functional”. The still free functional groups serve primarily for mixing the product to achieve a more intensive chemical fixation of the condensate in the epoxy resin network during crosslinking with further, common reaction resins and to influence later properties of the molding material in a targeted manner. These functional groups can, so to speak, serve as "anchors" of the modified siloxane condensate in the epoxy resin and the "low stress""Improve the behavior of the corresponding molded materials or bodies "Anchored" siloxane condensates result in molded epoxy resin materials which have a lower evaporation behavior and lower water absorption compared to the previously known materials with the conventional epoxysiloxane condensates. The mixtures according to the invention from the condensates and epoxy resins are preferred to form corresponding epoxy resin moldings or bodies The above-mentioned property profile can thus be imparted to these molding materials and molding materials with low-stress properties can thus be formed.

Basically, the epoxysiloxane condensates preferably described can be mixed with practically any common reaction resin or epoxy resin in almost any mixing ratio.

Correspondingly, new reaction resin mixtures can be obtained with aliphatic and aromatic glycidyl ethers, in particular based on bisphenol A and F, with corresponding glycidyl esters, aliphatic and cycloaliphatic epoxides, or with any other epoxides obtained, for example, by epoxidation of unsaturated compounds. The storage stability of the reaction resin mixture with the new epoxysiloxane can be further increased by heating the epoxysilanes in an applied vacuum.

The structure and the chemical-physical behavior of the epoxy resins obtained can be adjusted within wide limits by the choice of the organic, possibly difunctional or multifunctional, compound. Likewise, the phase separation behavior during curing by the organic compound with unchanged siloxane content or unchanged siloxane component can be adjusted. With that, the

Morphology, the modulus of elasticity, the coefficient of thermal expansion α and the mechanical relaxation behavior of the end influence molding materials or bodies obtained in the production chain.

The morphology determines the mechanical behavior of a molding material and is the determining factor for the low

Stress properties of a material. Morphology here means the microstructure formed during curing from an epoxy resin matrix and embedded, chemically fixed, εiloxane-rich domains. In addition to finely divided siloxane domains, the siloxanes can separate out as a second phase, resulting in multi-phase, cloudy moldings.

The "epoxysiloxane condensate" or "epoxysiloxanes" are the epoxysiloxanes of the prior art known to date, in particular those disclosed in P 43 28 465.5, which corresponds to US Pat. No. 5,492,981, an alkyl alcohol being free in the condensation reaction The disclosure content of the above-mentioned patent US Pat. No. 5,492,981 is hereby incorporated by reference and is made the subject of the present description.

As a "transesterification product" or "modified epoxysiloxane condensate", the product is obtainable by the two process steps, namely firstly condensation of the epoxyalkoxysilanes (= alkoxy compound) with the silanol and subsequent condensation of the remaining alkoxy function on the epoxysiloxane condensate the freely selectable organic, if necessary bifunctional or multifunctional compound.

"Condensable" and / or "di or multifunctional" compounds are used as the organic compound with which the condensation is carried out in the second process step b). "Condensable" means that the compound is a hydroxy or halogen group for condensation or

Has transesterification with alkoxy groups. “Di- or multifunctional” here means that in addition to this / these hydroxy or halogen functions with which the modified epoxysiloxane condensate is formed, the organic compounds still have other reactive groups, such as, for example, hydroxy, epoxy, ester, lactone, Lactam, halogen and / or pseudohalogen functions and / or unsaturated CC bonds as well as spiro and / or bicycloorthoester and / or spirocarbonate groups for further functionalization of the resulting condensation product.

"Condensation" here means any reaction in which the alcohol, on which the "alkoxy" is based, can be released from an alkoxy group, such as R-X (with X = halogen and R = alkyl radical of the alkoxy group), such as R-X.

In a common epoxy resin formulation - consisting of epoxy resin, hardener, accelerator, various additives and an epoxysiloxane condensate - the modified siloxane condensate described here is chemically incorporated into the epoxy resin network via additional functionalities. This fixes the siloxane even more firmly in the duromer matrix and improves the hydrolysis behavior, water absorption, thermal behavior and the evaporation behavior of the For substances. The mechanical behavior (modulus of elasticity, glass transition temperature) with regard to the low-stress problem can be favorably adapted to the technical requirements via the additionally inserted organic intermediate elements.

The epoxysiloxane molding materials obtained have increased bond strength on carrier substances such as V2A steel.

The invention is explained in more detail below on the basis of a few exemplary embodiments. For reasons of clarity, model reactions with A-187 (3-glycidyloxypropyltrimethoxysilane, Hüls) and diphenylsilanediol were used for the alkoxy-silanol condensation

(ABCR GmbHSCo) in a molar ratio of 1: 1 based on the alkoxy and silanol groups. The diol compounds were 1,4-butanediol (Merck), 1,6-hexanediol (Merck), 1,4-bis (dimenthanol) cyclohexane (Merck), TCD alcohol DM

(Octahydro-4, 7-methano-1H-indene-1 (2), 5 (6) -dimethanol, Hoechst) and bis (4-hydroxyphenyl) sulfone (Merck) used as received.

The condensates were further processed to give a 1: 1 casting resin using cycloaliphatic CY17 (3, 4-epoxy-cyclo-hexylmethyl-3 ', 4' -epoxy-cyclo-hexane carboxylate, Ciba-Geigy).

qilane concentration and condensation with heavy, volatile niol pri vates:

23.6 g (0.1 ol) of A-187 and 0.1 g of IPT (tetra-ortho-isopropyl titanate, Hüls) were mixed in portions with 21.6 g (0.1 mol) of diphenylsilanediol at 120 ° C. in the course of 10 min. With MeOH development, a reaction solution formed, into which the diol (see Table 1) was added after 1 h and kept at 120 ° C. for a further 2 h. The volatile components were removed at about 50 to 60 ° C. and 0.5 torr within 30 minutes. In the case of 1,4-butanediol, 47.2 g (theory:

44.7 g) of a light yellow medium viscosity oil. The transparent condensate dissolves well in acetone, methylene chloride and toluene. Cyclic ^Pn D3 / ^pl D4 homoproducts formed by ring formation from diphensylsilanediol could not be detected in any of the condensates in the DC experiments.

Table 1 Diols used, yield and consistency of the condensates

1) 0.1 g of dibutyltin dilaurate was used as the condensation catalyst.

Further processing with CY179:

The siloxane condensates were processed to a homogeneous 1: 1 casting resin at 120 ° C. For this purpose, the resins were degassed at 0.5 torr for 10 min and annealed at 120 ° C. for 30 min (Table 2).

Table 2 Selected parameters of the 1: 1 casting resins with CY179.

1) EEW = epoxy value [mol / lOOg]

Shape h ^ steT lunσ:

30, 0 gl: l cast resin were approx. 50 ° C with 0.95 equivalents of melted HT907 / 4 09

(Hexahydrophthalic anhydride, Ciba Geigy) and 0.3 g of 2,4-EMI (2-ethyl-4-methylimidazole, BASF) degassed at 0.5 torr for 30 minutes and thermally crosslinked: 1 hour at 80 ° C., 1 hour at 120 ° C. and 2 h 160 ° C.

The condensation synthesis concept with subsequent transesterification offers a broad development potential. When mixed with commercial epoxy casting resins, the physico-chemical properties, the morphology and the stress behavior of the molding materials obtained can be varied within wide limits.

Claims

claims

1. Modified epoxysiloxane condensate, obtainable by the following process steps

in which

R ^{1 represents} an alkyl radical having 1 to 22 C atoms or an aryl radical, R ^{2 is} a glycidyloxyalkyl, epoxyalkyl or an epoxycycloalkyl radical, the two radicals R ³ independently of one another are OR ¹ or R ² or another Are alkyl or aryl, R ^{4 is} alkyl or aryl, the radicals

R ^{5 are} independently OH or R ⁴ and n is an integer greater than 1

and

b) condensation of the thus obtained alkoxy group-containing epoxysiloxane condensate with a stoichiometric amount of an organic compound with a linear, branched or cyclic, optionally aromatic, carbon backbone of 1 to 24 carbon atoms and at least one condensable functional group.

2. Modified epoxysiloxane condensate according to claim 1, in which the organic compound used in the condensation step b) additionally comprises, in addition to the at least one condensable functional group, further reactive groups.

3. Modified epoxysiloxane condensate according to claim 2, in which the additional reactive groups are selected arbitrarily and independently of one another from the series of hydroxy,

Epoxy, ester, lactone, lactam, halogen and / or pseudohalogen functions and / or the group of unsaturated C-C bonds and / or the spiro and / or bicycloorthoester and / or spirocarbonate groups.

4. Process for modifying epoxysiloxanes, in which in a first process step

a) an epoxysiloxane 1 is condensed with a silanol 2, 1 and 2 being the compounds specified in claim 1, and after reaction of the silanol 2 in a further process step

b) the alkoxy group-containing epoxysiloxane condenser thus obtained is reacted in situ with an organic compound having a linear, branched or cyclic and optionally aromatic carbon backbone of 1 to 24 carbon atoms and at least one condensable functional group.

5. The method according to claim 4, wherein the organic compound used in process step b) in addition to the at least one condensable functional group additionally comprises further reactive groups.

6. The method according to claim 5, in which the additional reactive groups are arbitrarily and independently selected from the series of hydroxy, epoxy, ester, lactone, Lactam, halogen and / or pseudohalogen functions and / or the group of unsaturated CC bonds and / or the spiro and / or bicycloorthoester and / or spirocarbonate groups.

7. The method according to any one of the preceding claims 4 to 6, wherein the condensations are preferably carried out between pH 5 to 8 in the presence of a condensation catalyst.

8. The method according to any one of the preceding claims 4 to 7, in which the condensations are carried out as a bulk reaction.

9. The method according to any one of the preceding claims 4 to 8, in which the condensations are carried out at a temperature of 80 ° C to 150 ° C.

10. The method according to any one of claims 4 to 9, in which the condensations of the epoxyalkoxysilane 1 are carried out with a stoichiometric deficit of silanol 2.

11. The method according to any one of claims 4 to 10, wherein the volatile components are blown during the condensation in the inert gas stream.

12. The method according to any one of claims 4 to 11, in which the condensation products are isolated after different reaction times of 2 to 24 h, preferably 6 to 8 h.

13. The method according to any one of claims 4 to 12, wherein the reaction product obtained by the condensation is subjected to a thermal treatment in a vacuum after the condensation in order to increase the storage stability.

14. Use of the modified epoxysiloxane condensate according to one of claims 1 to 3 as a resin component for mixing O 98/04609

with common epoxy resins, it being possible to add the epoxy resins before or after the first condensation step a) or after the second condensation step b).

15. Use of the mixture from claim 14, for the production of formulations for the formation of moldings or moldings.