Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Adhesive outermost layer
Reexamination Certificate
1999-02-05
2001-09-25
Berman, Susan W. (Department: 1711)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Adhesive outermost layer
C428S411100, C428S500000, C522S182000, C526S328000, C526S328500, C053S1110RC, C206S813000
Reexamination Certificate
active
06294249
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to making viscoelastic compositions.
Methods of making packaged viscoelastic compositions such as hot melt adhesives and the resulting packaged compositions are known. German Patent No. 36 25 358 describes a hot melt adhesive block in a thermoplastic film. The film is melted and mixed with the adhesive in an extrusion process.
U.S. Pat. No. 5,257,491 describes a method of packaging a thermoplastic or thermosetting hot melt adhesive in which a portion of an adhesive composition is surrounded with a plastic packaging material. The plastic packaging material does not substantially adversely affect the adhesive characteristics of a molten mixture of the adhesive and the plastic packaging material.
PCT International Publication No. WO 93/23224 describes a method for packaging hot melt adhesive compositions in which molten hot melt adhesive is poured into a mold lined with a plastic film. The plastic film is meltable with the adhesive composition and blendable into the molten adhesive composition.
A method for producing thermoplastic mold materials useful for producing molded articles is described in German Pat. Disclosure 1 694 837, published Jul. 29, 1971. In the described method, the polymerization material is allowed to polymerize in a hollow profile that functions as a polymerization vessel. The hollow profile may be made of the same polymer produced in the polymerization process.
Methods of producing hot melt adhesives in sealed reaction vessels are known. U.S. Pat. No. 4,810,523 describes a method for producing hot melt adhesives in which a polymerizable monomer composition is introduced into a sealable reaction vessel and polymerized by ionizing radiation. The adhesive is then removed from the reaction vessel before hot melt application. The reaction vessel may be a lined cylindrical pressure vessel or a multilayer bag. See column 8, line 58, to column 9, line 8, of U.S. Pat. No. 4,810,523.
Although methods of producing viscoelastic compositions such as hot melt adhesives and methods of packaging such compositions are known, there is a need for a simplified process for making such compositions.
SUMMARY OF THE INVENTION
In a first aspect, the invention features a method of forming a hot melt adhesive composition that includes the steps of
(a) combining (i) a pre-adhesive composition which upon exposure to transmissive energy polymerizes to form a hot melt adhesive composition and (ii) a packaging material to form a packaged pre-adhesive composition,
the packaging material being selected such that it does not substantially adversely affect the adhesive properties of the hot melt adhesive composition when the hot melt adhesive composition and the packaging material are melted and mixed together; and
(b) exposing the packaged pre-adhesive composition to transmissive energy to polymerize the pre-adhesive composition to form a packaged hot melt adhesive composition. The packaged hot melt adhesive composition may then be melted if desired.
In some preferred embodiments, the pre-adhesive composition is combined with the packaging material by substantially or completely surrounding the pre-adhesive composition with the packaging material. In other preferred embodiments, the pre-adhesive composition is combined with the packaging material by disposing the pre-adhesive composition on the surface of a sheet, or between a pair of sheets; in the latter case, at least one of the sheets is selected such that it does not substantially adversely affect the adhesive properties of the hot melt adhesive composition when the hot melt adhesive composition and the sheet are melted and mixed together. In yet another preferred embodiment, the packaging material is in the form of a hollow profile in which the ratio of the length to the square root of the cross-sectional area of the profile is at least about 30:1.
The pre-adhesive composition may be contacted with a heat exchange medium (e.g., water) while exposing the packaged pre-adhesive composition to transmissive energy to polymerize the pre-adhesive composition. Examples of preferred sources of transmissive energy include ultraviolet radiation and thermal conduction. The polymerization reaction may progress to fill (or nearly full) conversion. Preferably, the degree of conversion is at least 80%, and more preferably at least 90%.
The pre-adhesive composition preferably has a viscosity less than about 50,000 centipoise at 25° C., and more preferably less than about 50 centipoise at 25° C. The melting point of the pre-adhesive composition preferably is no greater than about 40° C., more preferably no greater than about 25° C., and even more preferably no greater than about 0° C. One example of a preferred pre-adhesive composition includes the following materials:
(a) 50 to 100 parts by weight of a polymerizable component that includes at least one acrylic or methacrylic ester of a non-tertiary alkyl alcohol in which the alkyl group contains 1 to 20 carbon atoms;
(b) 0 to 50 parts by weight of a polymerizable component that includes at least one modifying monomer, other than the acrylic or methacrylic ester, copolymerizable with component (a), the sum of (a) and (b) amounting to 100 parts by weight;
(c) an effective amount of a polymerization initiator; and
(d) an effective amount of a chain transfer agent.
The pre-adhesive composition may also include a cross-linking agent.
The invention also features a packaged pre-adhesive composition that includes (i) a pre-adhesive composition which upon exposure to transmissive energy polymerizes to form a hot melt adhesive composition and (ii) a packaging material, in which the packaging material is selected such that it does not substantially adversely affect the adhesive properties of the hot melt adhesive composition when the hot melt adhesive composition and the packaging material are melted and mixed together.
In a second aspect, the invention features a method of forming a viscoelastic composition that includes the steps of:
(a) combining (i) a pre-viscoelastic composition which upon exposure to transmissive energy polymerizes to form a viscoelastic composition and (ii) a packaging material to form a packaged pre-viscoelastic composition,
the packaging material being selected such that it does not substantially adversely affect the viscoelastic properties of said viscoelastic composition when the viscoelastic composition and the packaging material are melted and mixed together; and
(b) exposing the packaged pre-viscoelastic composition to transmissive energy to polymerize the pre-viscoelastic composition to form a packaged viscoelastic composition. An example of a preferred viscoelastic composition is a hot melt adhesive composition which is prepared by polymerizing a pre-adhesive composition upon exposure to transmissive energy.
In a third aspect, the invention features a method of forming an adhesive composition that includes the steps of:
(a) combining (i) a pre-adhesive composition which upon exposure to ultraviolet radiation, thermal conduction, or a combination thereof polymerizes to form an adhesive composition and (ii) a packaging material to form a packaged pre-adhesive composition by substantially surrounding the pre-adhesive composition with the packaging material; and
(b) exposing the packaged pre-adhesive composition to ultraviolet radiation, thermal conduction, or a combination thereof to polymerize the pre-adhesive composition to form a packaged adhesive composition. The packaged composition may then be melted if desired.
An example of a preferred adhesive composition is a hot melt adhesive composition. Another example of a preferred adhesive composition is a pressure sensitive adhesive composition (which may or may not be a hot melt adhesive as well).
In one preferred embodiment, the pre-adhesive composition is combined with the packaging material by completely surrounding the pre-adhesive composition with the packaging material. The packaging material is preferably selected such that it does not substantially adversely affect th
Hamer Craig E.
Kotnour Thomas A.
Moon John D.
3M Innovative Properties Company
Berman Susan W.
Patchett David B.
LandOfFree
Packaged pre-adhesive composition does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Packaged pre-adhesive composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Packaged pre-adhesive composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2545751