# US 5,705,596 A · Epoxy resin and process for producing the same

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- Number: US 5,705,596 A
- Document ID: US5705596A
- Status: Granted
- Kind: A
- Application number: 08/657,363
- Filed: 1996-06-03
- Granted: 1998-01-06
- Earliest claimed: 1995-06-02
- Assignees: Sumitomo Chemical Company, Limited
- Inventors: Akira Yokota; Yasuhiro Hirano; Masatsugu Akiba; Hiroshi Nakamura; Shigeki Naitoh
- Web page: https://patentgrep.com/patent/US5705596A

## CPC

- C08G 59/063: {with epihalohydrins}
- C07D 303/24: with polyhydroxy compounds
- C08G 59/245: {aromatic}
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C07D: HETEROCYCLIC COMPOUNDS (macromolecular compounds C08)

## Abstract

The invention provides a cis-stilbene type epoxy resin having lower melting point and lower viscosity than the trans-stilbene type epoxy resin hitherto known. The stilbene type epoxy resin has a cis-isomer content of essentially 100%, or in the alternative, at least about 10% with the rest being the trans-isomer, and is based on the following general formula (1): ##STR1## wherein R.sub.1 to R.sub.8 are independently an acyclic or cyclic alkyl group, a hydrogen atom, or a halogen atom. Production processes for these epoxy resins are also disclosed.

## Claims

### Claim 1

A composition comprising an epoxy resin containing between about 0.1 to about 20 wt. % stilbene linkages, wherein said stilbene linkages are characterized by a cis-isomer content which is at least about 10%, wherein said cis-isomer content is a value equal to ((mol cis-isomer)/(mol cis-isomer+mol trans-isomer)).times.100%, and said epoxy resin has a melting point less than about 150 degrees Celsius and viscosity of less than about 0.2 poise at 150 degrees Celsius.

### Claim 2

A composition comprising an epoxy resin which is uncured and contains the structural unit having epoxy functional groups represented by formula (1): ##STR6## or alternatively if said epoxy resin is partially cured or cured, at least some of said epoxy functional groups represented by formula (1) are reacted by said cure, wherein R.sub.1 to R.sub.8 independently represent an acyclic or cyclic alkyl group, a hydrogen atom, or a halogen atom, wherein said epoxy resin has a cis-isomer content of at least 10%, said cis-isomer content being calculated as ((mol cis-isomer)/(mol cis-isomer plus mol trans-isomer)).times.100%, and said epoxy resin has a melting point less than about 150 degrees Celsius and viscosity of less than about 0.2 poise at 150 degrees Celsius.

### Claim 3 (depends on 1)

A composition according to claim 1, wherein said cis-isomer content is at least about 20%.

### Claim 4 (depends on 1)

A composition according to claim 1, wherein said cis-isomer content is at least about 40%.

### Claim 5 (depends on 1)

A composition according to claim 1, wherein said cis-isomer content is about 100%.

### Claim 6 (depends on 1)

A composition according to claim 1, wherein said R.sub.1 through R.sub.8 are independently a hydrogen atom, a bromine atom, a chlorine atom, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, or a hexyl group.

### Claim 7 (depends on 1)

A composition according to claim 1, wherein said R.sub.1 through R.sub.8 are independently a hydrogen atom, a halogen atom, a methyl group, an ethyl group, a propyl group, or a butyl group.

### Claim 8 (depends on 1)

A composition according to claim 1, wherein said epoxy resin has been irradiated with ultraviolet light to generate at least some photoisomerization of said stilbene linkages and increase said cis-isomer content.

### Claim 9 (depends on 1)

An article encapsulated with a composition according to claim 1.

### Claim 10 (depends on 9)

An article according to claim 9, wherein said article is an electronic device.

### Claim 11

A composition comprising a stilbene epoxy resin having a cis-isomer content of at least about 10%, calculated as 100%.times.((mol cis-isomer)/(mol cis-isomer+mol trans-isomer)), said cis-isomer of said stilbene epoxy resin being represented by the general formula (1) ##STR7## wherein R.sub.1 to R.sub.8 independently represent an acyclic or cyclic alkyl group, a hydrogen atom or a halogen atom, and said epoxy resin has a melting point less than about 150 degrees Celsius and viscosity of less than about 0.2 poise at 150 degrees Celsius.

### Claim 12 (depends on 2)

A composition according to claim 2 wherein the cis-isomer content is in a range of about 27 to about 50 percent.

### Claim 13 (depends on 2)

A composition according to claim 2 wherein the structural units are based on 4,4'-bis(2,3-epoxypropoxy)-3,3'-5,5' tetramethylstilbene.

### Claim 14 (depends on 13)

A composition according to claim 13 wherein the cis-isomer content is in a range of about 27 to 50 percent.