Stock material or miscellaneous articles – Composite – Of epoxy ether
Reexamination Certificate
1999-07-19
2001-05-08
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Composite
Of epoxy ether
C523S460000, C361S748000, C361S750000
Reexamination Certificate
active
06228500
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an adhesive composition comprising, as a base, a resin component containing a phenoxy resin, an epoxy resin and a curing agent, and an adhesive composition precursor as a raw material of such a composition.
BACKGROUND OF THE INVENTION
As a material of an adhesive film for FPC (flexible printed circuit board) protective film, various adhesive compositions obtained by combination of thermoplastic resins and epoxy resins as thermosetting resins have hitherto been known (see, for example, Japanese Unexamined Patent Publication (Kokai) Nos. 9-132710, 9-125037, 5-5085, 3-6280, 2-145676, 62-274690, 60-130666, 1-135844 and 61-43550).
Among adhesive films disclosed in the above-described patent publications, an adhesive film formed from a composition containing a phenoxy resin, an epoxy resin and a curing agent is comparatively superior in performances such as heat resistance, adhesion to metal parts, etc. and, therefore, the adhesive film has hitherto been considered to be useful. It is also disclosed to use a polyester resin or various elastomers in place of a phenoxy resin, as the thermoplastic resin. Furthermore, dicyanamide is often used, comparatively, because it is particularly superior in potentiality.
However, the above-described adhesive composition containing a phenoxy resin, an epoxy resin and dicyandiamide as a curing agent, as a main component, has a drawback in that a dimensional change caused by a stress produced during the thermal curing process is comparatively large. Reduction in such a dimensional change, i.e. improvement of the dimensional stability, is further required in the usage of the adhesive for FPC protective film. In the above-described conventional composition, however, it was very difficult to respond to such a requirement.
On the other hand, it has been known as a conventional technique to improve the nonflammability of the resin composition by adding a combination of a brominated epoxy resin and antimony pentaoxide in the general field of the resin composition. This technique is normally characterized by mixing antimony pentaoxide powder with a resin component to form a nonflammable composition. Since the antimony pentaoxide powder is comparatively inexpensive, its utilization value is high. However, since an average particle diameter of the antimony pentaoxide powder is normally not less than 0.5 &mgr;m, sedimentation of the powder is liable to arise due to gravity and it was difficult to obtain a composition in the state where the respective components are uniformly dispersed. That is, in case of forming an adhesive composition containing the antimony pentaoxide powder, sedimentation of the antimony pentaoxide powder is liable to arise in a mixed solution of an active amount of the antimony pentaoxide, a resin component and a solvent. Therefore, it was difficult to realize the state (structure) where the respective components are uniformly mixed. Such a nonuniform structure causes deterioration of the adhesion, which results in drastic deterioration of the performance as the adhesive for FPC protective film.
SUMMARY OF THE INVENTION
The object of the present invention is, therefore, to solve the above-described problems of the prior art and to provide an adhesive composition comprising a phenoxy resin, an epoxy resin and a curing agent, which is superior in performance as an adhesive for FPC protective film, particularly dimensional stability and adhesion.
A further object of the present invention is to provide an adhesive composition precursor suited to provide such an adhesive composition.
DETAILED DESCRIPTION OF THE INVENTION
According to one aspect of the present invention, there is provided an adhesive composition comprising a resin component containing a phenoxy resin, an epoxy resin and a curing agent, characterized in that said resin component further contains a polyester polyol and further comprises an inorganic colloid dispersed in said resin component.
According to another aspect of the present invention, there is provided an adhesive composition precursor capable of affording said adhesive composition after drying, characterized in that said precursor comprises:
(i) said resin component, and
(ii) an inorganic particle sol containing a dispersion medium and said inorganic colloid dispersed in said dispersion medium.
Subsequently, the present invention will be described with reference to the preferred embodiments thereof. For further understanding of the present invention, the present invention will be described first by way of the operation aspect as follows.
The adhesive composition of the present invention is a composition comprising, as a base, a resin component containing a phenoxy resin, an epoxy resin and a curing agent, characterized in that said resin component further contains a polyester polyol (hereinafter, sometimes, referred to as a “polyol”) and an inorganic colloid in a predetermined ratio. According to the adhesive composition of the present invention, by using the resin component having such a specific composition, the dimensional stability, particularly dimensional stability after a heat treatment (for the purpose of completion of curing) performed furthermore after heat bonding can be efficiently enhanced. In fact, according to the present invention, such a dimensional stability (represented by a dimensional change (%), a measuring method of which is described hereinafter) can be reduced to 0.1% or less. In case of using such an adhesive composition in adhesion between a metal such as copper foil, etc. and a polymer such as polyimide, etc., it is also possible to efficiently increase the adhesive force. For example, a peel adhesive force (which means a “180° peel adhesive force” hereinafter unless otherwise stated) can be increased to 700 g/cm or more.
The operation of the above polyol to be contained in the resin component lies in improvement in interfacial adhesive force between the adhesive composition and adherend, first, because the polyol has two or more hydroxyl groups in the molecule. When a cured article of the adhesive composition contains a polyol, the flexibility of the cured article is improved and the peel adhesive force is increased. Furthermore, since the polyol can efficiently increase the crosslink density of the cured article without deteriorating the flexibility of the cured article, it also contributes to the improvement in dimensional stability.
The content of the above polyol is not specifically limited as far as the effect of the present invention is not adversely affected, but is normally within the range from 0.5 to 20% by weight based on the total amount of the adhesive composition. When the content of the polyol is less than 0.5% by weight, the peel adhesive force and dimensional stability are likely to be lowered. On the other hand when the content exceeds 20% by weight, other performances of the adhesive composition (e.g. nonflammability described hereinafter) are likely to be lowered. From such a point of view, the preferable content of the polyol is within the range from 1 to 15% by weight based on the total amount of the adhesive composition.
The term “polyol”, i.e. “polyester polyol” used herein means a compound which contains one or more ester bonds and two or more hydroxyl groups in the molecule and has a number-average molecular weight of 100 to 18,000, suitably 200 to 10,000, particularly suitably 300 to 6,000. The number-average molecular weight less than 100 causes a problem that, after heat treatment (thermal curing), an effectively increased dimensional stability may not be obtained, and the molecular weight above 18,000 may cause a reduction of the adhesive force. As the polyol, for example, caprolactonepolyol is suitable because of its good compatibility with other resin components such as phenoxy resin, epoxy resin, etc. It is preferable that the kind and addition amount of the polyol are selected to impart high dynamic bending resistance to the cured article of the adhesive composition without reducing the elasticity at
Hiroshige Yuji
Kawate Kohichiro
3M Innovative Properties Company
Aylward D.
Dawson Robert
LandOfFree
Adhesive composition and precursor thereof does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Adhesive composition and precursor thereof, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Adhesive composition and precursor thereof will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2543148