TRANSPARENT FILM

• US 20120058320A1
• Filed: 03/09/2010
• Published: 03/08/2012
• Est. Priority Date: 03/09/2009
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Electric Works Company Limited (Panasonic Holdings Corporation)
• Inventors: Hashimoto, Shinji, Kishimoto, Hirotsugu
• Granted Patent: US 8,987,364 B2
• Time in Patent Office: Days
• US Class Current: 428/212
• CPC Class Codes: C08G 59/3218 Carbocyclic compounds
• CPC Class Codes: C08L 63/00 Compositions of epoxy resins; Compositions of derivatives of epoxy resins
• CPC Class Codes: G02B 1/04 made of organic materials, e.g. plastics G02B1/08 takes precedence
• CPC Class Codes: G02F 1/133302 Rigid substrates, e.g. inorganic substrates
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/249924 Noninterengaged fiber-containing paper-free web or sheet which is not of specified porosity

Abstract

A transparent film is capable of suppressing discoloration caused by heat, while retaining high transparency and high glass transition temperature. The transparent film includes a glass fiber substrate made of glass fibers and impregnated with a resin composition in which a high refractive resin (a transparent resin) having refractive index higher than the glass fiber is mixed with a low refractive resin (a second transparent resin) having a refractive index lower than the glass fiber to have a resultant refractive index approximate to that of the glass fiber when cured. The high refractive resin has a 3 or more-functional epoxy resin expressed by the following formula:

• • wherein R1 is a hydrogen atom or methyl group, R2 is a 2-valent organic group, and R3 to R10 are respectively ones selected from a group consisting of a hydrogen atom, a substituent group, and a molecular chain containing epoxy group.

Claims

1. A transparent film comprising:

a glass fiber substrate made of glass fibers and impregnated with a transparent resin composition made of a transparent resin,

wherein said transparent resin comprises a 3 or more-functional epoxy resin expressed by the following formula;

2. A transparent film as set forth in claim 1, wherein

said transparent resin comprises a 3-functional epoxy resin expressed by the following formula:

3. A transparent film as set forth in claim 1, wherein

said transparent resin includes a cyanate-ester resin.

4. A transparent film as set forth in claim 1, wherein

said transparent resin composition has a glass transition temperature of 220°

C. or more after being cured.

5. A transparent film as set forth in claim 1, wherein

said transparent resin composition includes a curing initiator of zinc octanoate.

6. A transparent film as set forth in claim 1, wherein

said transparent resin composition is prepared by mixing said transparent resin with a second transparent resin,

said glass fiber substrate has refractive index of 1.55 to 1.57,

said transparent resin has refractive index of 1.58 to 1.63 after being cured, and

said second transparent resin has refractive index of 1.47 to 1.53 after being cured.

7. A transparent film as set forth in claim 1, wherein

said transparent resin composition is prepared by mixing said transparent resin with a second transparent resin,

said glass fiber substrate has refractive index of 1.50 to 1.53,

said transparent resin has refractive index of 1.54 to 1.63 after being cured, and

said second transparent resin has refractive index of 1.47 to the refractive index of said glass fiber substrate after being cured.