Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1998-04-30
2000-04-18
Seidleck, James J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525107, 522120, 522134, 522135, 522143, 522102, C08K 504
Patent
active
060516526
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a composition suitable for preparing a reactive hot melt composition, and the reactive hot melt composition made therefrom. Advantageously, the reactive hot melt composition can be used as a hot melt adhesive, in particular, a film-form adhesive having a determined thickness. The hot melt adhesive is useful for adhering electronic parts such as integrated circuit (IC) chips to a substrate as well as for producing multilayer electronic interconnect circuits. Suitable substrates include ceramics, metals, plastics, and the like, and the reactive hot melt compositions of the present invention have good adhesion to these surfaces.
2. Description of the Related Art
A hot melt adhesive gives high speed adhesion because adhesion is obtained through a physical change in the adhesive. A thermoplastic resin composition that is solid at room temperature is melted, applied to an adherend, and then cooled until it solidifies. By utilizing this property, manufacturing productivity can be increased. Hot melt adhesives have been mainly used in packaging and woodworking applications, with wide use in the electric and electronic fields more recently.
However, conventional hot melt adhesives have poor adhesion at temperatures above their melting points and low heat resistance, which limits the use of the hot melt adhesives in the electric and electronic applications. For example, adhesives used for fixing a lead pin to a lead frame of an IC chip are heat laminated and then placed in a high temperature environment of 230 to 260.degree. C., which is higher than the temperature for soldering. Since conventional hot melt adhesives cannot maintain sufficient adhesion at these temperatures, they cannot be used in these applications.
Reactive hot melt adhesives, which crosslink after bonding, are known for having improved heat resistance. Examples of known reactive hot melt adhesives include the following: isocyanate group (see U.S. Pat. No. 5,418,288 corresponding to JP-A-6-158017, etc.); which has a silyl group (see JP-A-5-320608, etc.); which has an acryloyl group (see JP-A-63230781, etc.); glycidyl group, and a phenol resin (see JP-A-6172731, etc.); and application of the adhesive (see JP-A-6-306346, etc.).
However, the reactive hot melt adhesives disclosed in these references still have the following drawbacks: curing is necessary (for example, in the case of (1) and (2) above); for the crosslinking reaction, and are not suitable for use in environments where the adhesive has limited exposure to air during curing (for example, in the case of (1) above); adverse effects, such as the deterioration of adhesion with time, particularly for bonding electronic parts. (for example, in the case of (2) above); and the residual solvent may have adverse effects (for example, in the case of (1) to (4) above); adhesives are stored at room temperature (about 25.degree. C.), and the adhesives have poor shelf stability (for example, in the case of (1), (2) and (3) above); and adherends that do not readily permit or tolerate radiation exposure (in the case of (5) above).
It would be desirable to have a composition that can yield a reactive hot melt adhesive that does not suffer from these drawbacks, as well as the resulting reactive hot melt composition, especially if it can be provided in film form.
SUMMARY OF THE INVENTION
The present invention provides a reactive hot melt composition comprising: (a) a thermoplastic polymer which comprises a polyolefin having an epoxy group; and (b) a copolymer which is obtained by radiation polymerizing an aliphatic alkyl (meth)acrylate, and an acrylic compound having a functional group reactive with an epoxy group. (Herein, "(meth)acrylate" collectively means an acrylate and/or a methacrylate.)
The reactive hot melt composition (hereinafter sometimes referred to as the "hot melt composition") is a solid at room temperature (about 25.degree. C.) (hereinafter "room temperature" means "about 25.degree. C.). It melts at a
REFERENCES:
patent: 4996132 (1991-02-01), Tazawa et al.
patent: 5339604 (1994-08-01), Sano et al.
patent: 5418288 (1995-05-01), Kawasaki et al.
Ishii Shigeyoshi
Kawate Kohichiro
3M Innovative Properties Company
Fortkort John A.
McClendon Sanza
Seidleck James J.
Skolnick Steven E.
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