Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
1999-12-29
2001-11-13
Lam, Cathy (Department: 1775)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S378000, C428S389000, C174S096000, C174S098000, C174S118000
Reexamination Certificate
active
06316104
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the technical field of flat cables, particularly to flat cables using an adhesive based on a polyester resin.
PRIOR ART
In order to connect electronic devices using a number of wirings, a flat cable as shown by
110
in
FIG. 2
has often been used.
This flat cable
110
comprises a copper wiring
105
formed of copper wires, for example, inserted between two adhesive films
102
1
,
102
2
. The adhesive films
102
1
,
102
2
consist of resin films
103
1
,
103
2
and adhesive layers
104
1
,
104
2
on their surfaces, so that the copper wiring
105
is adhered to the resin films
103
1
,
103
2
via the adhesive layers
104
1
,
104
2
. In such a flat cable
110
, the copper wirings
105
are insulated from each other at high resistance with the adhesive layers
104
1
,
104
2
filled between the copper wirings
105
.
However, the flat cable
110
has the problem that insulation between the copper wirings
105
is lowered with time resulting in failure.
Another problem is that adhesive strength between the adhesive films
102
1
,
102
2
or between the adhesive films
102
1
,
102
2
and the copper wiring
105
is lowered with time resulting in lowered mechanical strength.
Such loss in insulation and adhesive strength has been attributed to corrosion of the copper wiring. Thus, the prior art took a measure to protect the copper wiring against corrosion by plating it, for example.
However, plating incurs high costs but has a little effect to prevent insulation loss. Thus, more suitable measures have been demanded.
An object of the present invention is to provide a flat cable with reduced loss of adhesive strength and insulation in order to solve the above disadvantages of the prior art.
Disclosure of the Invention
We initially attributed insulation loss to corrosion of the copper wiring by halogen ions liberated from a flame retardant added with a flame retardant aid such as aluminium hydroxide in the adhesive layers
104
1
,
104
2
of such a flat cable
110
.
Considering that flat cables prepared with an adhesive based on a polyester resin show significant loss in adhesive strength and insulation in an environment of high temperature or high temperature and high humidity, we prepared a flat cable with the adhesive containing an anion scavenger (an anion exchanger). However, its effect of prevention of insulation loss was less.
Then, we thought that loss in insulation and adhesive strength is not caused by halogen ions liberated from the flame retardant but copper ions dissoluting in the adhesive from the copper wiring to affect the resin film or adhesive components in the adhesive.
A possible measure against this is to prevent dissolution of copper ions from the copper wiring, but it is difficult. A more convenient and effective means presumably consists in including a cation scavenger in the adhesive to scavenge free copper ions in the adhesive.
Experiments revealed that loss in adhesive strength and insulation with time is reduced when a flat cable is prepared by laminating resin films with a polyester resin-based adhesive containing a cation scavenger.
The present invention is based on the above finding and relates to an adhesive based on a polyester resin characterized in that it contains a cation scavenger.
Said adhesive may contain a flame retardant and a flame-retardant aid to provide flame retardancy. The flame retardant may be a halogen compound such as decabromodiphenyl ether, for example. The flame-retardant aid may be a compound such as antimony trioxide or aluminium hydroxide. In addition to the flame retardant and flame-retardant aid, the adhesive may contain an antioxidant, coupling agent, colorant, thickener, anti-blocking agent, crosslinking agent, filler, etc.
If the flame retardant and flame-retardant aid are not added, the cation scavenger is preferably contained in an amount of 0.1 part by weight or more based on 100 parts by weight of the polyester resin.
If the flame retardant and flame-retardant aid are added, the total amount of the polyester resin, flame retardant and flame-retardant aid account for a great majority of the amount of the entire adhesive. In this case, the cation scavenger is also preferably contained in an amount of 0.1 part by weight or more based on 100 parts by weight of the total amount of the polyester resin, flame retardant and flame-retardant aid.
The above adhesive can be used to form an adhesive layer on a resin film to give an adhesive film. The adhesive layer can be formed by application of the adhesive.
The above adhesive can be used to laminate two resin films to each other to form a circuit material comprising a metallic wiring inserted between the two resin films.
Adhesive films having an adhesive layer formed from the above adhesive on a resin film can be laminated to each other to form a circuit material with a metallic wiring inserted between the two adhesive films.
REFERENCES:
patent: 3692924 (1972-09-01), Nye
patent: 4075420 (1978-02-01), Walton
patent: 4177181 (1979-12-01), Tsurumi et al.
patent: 4185046 (1980-01-01), Pengilly et al.
patent: 4381420 (1983-04-01), Elliot et al.
patent: 5253318 (1993-10-01), Sayegh et al.
patent: 5962129 (1999-10-01), Halloran et al.
patent: 63-20354 (1988-01-01), None
Lam Cathy
Oliff & Berridg,e PLC
Sony Chemicals Corporation
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