Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – Shaping against forming surface
Patent
1997-06-23
1998-07-07
Szekely, Peter A.
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
Shaping against forming surface
26433119, 528 66, 528 80, 528 83, 528 84, 528 85, B29G 4514, C08G 1810, C08G 1842, C08G 1848
Patent
active
057764069
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to the use of moisture-curing PU hotmelt adhesives for the production of moldings.
Moldings of hotmelt adhesives are known. Thus, EP 0 193 746 describes a process for the production of moldings, bonds and coatings from melts of thermoplastic poly(amide-urethane) block copolymers which have been obtained by reaction of on dimerized fatty acids and aliphatic or cycloaliphatic diamines with reaction products thereof with 2,3-epoxypropanol, specific examples of moldings of these thermoplastic poly(amide-urethane) block copolymers are described in DE 43 21 044. This earlier, but hitherto unpublished patent application relates to cable harnesses with holding elements in the form of injection moldings surrounding at least the outer circumference of the cable group at the fixing points. The injection moldings may assume the form of, for example, feed-through or insertion bushes. The hotmelt adhesive used should preferably crosslink, more particularly with atmospheric moisture. In addition, it should be rubbery, flame-resistant and partly crystalline. The moldings are produced by 0 to 30 bar and, more particularly, 5 to 30 bar and best keeping it under that pressure for a certain time,
Moldings of the hotmelt adhesive "Macromelt" are described in the technical information pamphlet entitled "Macromelt Moulding" published by Henkel KGaA in Mar., 1994. The process described therein is suitable for the encapsulation of plastic inserts by injection molding. By virtue of the high adhesion of Macromelt, extremely effective sealing and strength values are obtained with the encapsulated molding. On account of the relatively low viscosity of the hotmelt adhesive "Macromelt", it can be pumped under low pressure into the injection mold where even intricate moldings are gently enveloped and thus sealed and protected. Macromelt shows very good adhesion to polar plastic surfaces (for example PVC, PA 6.6, PUR) and to non-polar plastic surfaces (for example PP). To produce the moldings, the Macromelt is converted into a low-viscosity melt solely by application of heat. The melt is pumped into a cold mold in which the heat is removed again. This process normally lasts only a few seconds, depending on the melt (the amount of heat). The molding can then be removed from the mold. Processing takes place in special processing machines which automatically and thus safely control the flow of material from melting up to the mold. The pamphlet does not provide exact details showing that the thermoplastic molding material is based on a hotmelt. However, products based on polyamides are commercially available.
U.S. Pat. No. 5,250,607 describes a moisture-curing extrudable thermoplastic sealing compound consisting essentially of two components, namely: molecule which react with one another in the presence of ambient moisture and inter alia for the encapsulation of electrical connectors. In addition, films, tapes or tubes can be extruded from this polymer blend.
The problem addressed by the present invention was to provide molding compounds and a suitable molding process which would be distinguished not only by good processing properties, such as rapid demoldability, but also by favorable performance properties, such as heat resistance, resistance to chemicals, low porosity and firm adhesion to cable insulations, more particularly based on PVC.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
Not applicable
DETAILED DESCRIPTION OF THE INVENTION
The solution to this problem as provided by the invention is defined in the claims. It is essentially characterized in that moisture-curing polyurethane hotmelt adhesives with a melt viscosity of less than 100 Pa.multidot.s at their processing temperature are used as molding compounds for the production of moldings. The melt viscosity of the hotmelt adhesives is preferably below 50 Pa.multidot.s and, more preferably, below 20 Pa.multidot.s.
In the context of the present invention, a "moisture-curing polyurethane hotmelt adhesive" is understood
REFERENCES:
patent: 4957979 (1990-09-01), Albini et al.
patent: 5019638 (1991-05-01), Muller et al.
patent: 5250607 (1993-10-01), Comert et al.
patent: 5455309 (1995-10-01), Albini et al.
patent: 5599895 (1997-02-01), Heider
"Macromelt Moulding", Henkel KgaA, Mar. 1994.
Heider Roland
Jonscher Karin
Krebs Michael
Schubert Georg
Henkel Dommanditgesellschaft auf Aktien
Jaeschke Wayne C.
Meder Martin G.
Szekely Peter A.
Szoke Ernest G.
LandOfFree
Moldings of polyurethane hotmelt adhesives does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Moldings of polyurethane hotmelt adhesives, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Moldings of polyurethane hotmelt adhesives will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1202203