Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2002-01-29
2004-11-16
Szekely, Peter (Department: 1714)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S334000, C428S3550BL
Reexamination Certificate
active
06818093
ABSTRACT:
This invention relates to a low-viscosity hotmelt adhesive based on at least one hydrocarbon resin solid at 20° C. and at least one oil. The invention also relates to the production of this hotmelt adhesive and to its use.
One such hotmelt adhesive is already known. Thus, EP 0 442 045 B1 describes a sprayable hotmelt adhesive based on a poly-&agr;-olefin with no more than 30% by weight of additives, more particularly waxes and/or resins. Paraffinic or aromatic oils may also be used. The Examples contain ethene/propene/1-butene terpolymers and plastic microwaxes and, in some cases, also a hydrocarbon resin. The viscosities are 2700 and 3400 mPas at 190° C.
A number of atactic poly-&agr;-olefin copolymers and terpolymers of the monomers ethylene, propylene and 1-butene are described in the technical information pamphlet entitled “Vestoplast: Klebrohstoff für Hot-Melt-Anwendungen” published by the Hüls company in 1996. Polymers such as these show excellent wetting behavior on non-polar substrates such as, for example, polyethylene and polypropylene. An increase in adhesive strength can be obtained by combination with tackifying resins or plasticizers. Substantially saturated hydrocarbon resins in particular are recommended as resins. Added in a quantity of up to 30%, the resin acts as a plasticizer. Beyond 35%, the mixture assumes the properties of the resin and becomes hard and brittle. In the case of a mixture of poly-&agr;-olefin and resin in a ratio of 70 to 30 parts by weight, tensile strength decreases by at least 20% when the ratio is altered to 50:50 parts by weight at the expense of the poly-&agr;-olefin. The object of adding resins is inter alia to “fine-tune” the viscosity and to reduce stringing. In most cases, polybutenes of relatively low molecular weight are recommended as plasticizers. It is less expensive to use paraffinic or naphthenic mineral oils. The basic formulation for sprayable hotmelt adhesives for sanitary articles contains 70 parts of Vestoplast 704 (a poly-&agr;-olefin), 25 parts of Escorez 5380 (a hydrogenated polycyclopentadiene), 5 parts of Napvis D 10 (a polybutene liquid at room temperature) and 0.4 part of Irganox 1010 (an antioxidant for polyolefins). This known sprayable hotmelt adhesive has a melt viscosity of 2000 mPas at 190° C. and a softening point of 91° C.
Hotmelt adhesives for structural or elastic bonding based on ca. 50 to 60% by weight of hydrocarbon resins, ca. 20 to 30% by weight of styrene block copolymers and ca. 20% of paraffinic or naphthenic mineral oils are also available on the market.
One feature common to these hotmelt adhesives is a relatively high melt viscosity of more than 3300 mPas at 150° C. and a reduction in the adhesion values during storage at body temperature where laminates produced with them contain dermatologically compatible coatings.
These problems arise above all where the sprayable hotmelt adhesives are used for the production of a laminate of at least one nonwoven and/or at least one film. By this is also meant a shaped article which consists of a film and a central layer of cellulose pulp and which is covered by a spun bonded or carded nonwoven. Laminates such as these, which are used in particular in the field of personal hygiene, are generally materials with a limited useful life which are discarded, for example, after being used only once (disposable products). Such products include above all diapers, sanitary napkins or panty liners, etc., of which the function is to absorb bodily fluids such as, for example, urine and blood. These functions have to be performed even after storage at elevated temperature in the presence of dermatologically compatible coatings of the top sheet without the laminate disintegrating into its constituents even under the slightest mechanical stressing.
Accordingly, the problem addressed by the present invention was to improve the adhesion of laminates of nonwovens and/or films to a dermatologically compatible coating of the top sheet after storage at room temperature and at elevated temperature and also to make the hotmelt adhesive easier to process. This includes in particular reducing the melt viscosity of the hotmelt at the application temperature without causing a significant reduction in its softening point.
REFERENCES:
patent: 4046838 (1977-09-01), Feeney
patent: 4072735 (1978-02-01), Ardemagni
patent: 4136699 (1979-01-01), Collins et al.
patent: 4169822 (1979-10-01), Kutch et al.
patent: 4210570 (1980-07-01), Trotter et al.
patent: 4361672 (1982-11-01), Agarwal et al.
patent: 4394915 (1983-07-01), Nelson
patent: 4680333 (1987-07-01), Davis
patent: 4833193 (1989-05-01), Sieverding
patent: 4956207 (1990-09-01), Kauffman et al.
patent: 5021257 (1991-06-01), Foster et al.
patent: 5095059 (1992-03-01), Kitamura et al.
patent: 5149741 (1992-09-01), Alper et al.
patent: 5459193 (1995-10-01), Anderson et al.
patent: 5559165 (1996-09-01), Paul
patent: 5869555 (1999-02-01), Simmons et al.
patent: 5912295 (1999-06-01), Oeltjen et al.
patent: 5916959 (1999-06-01), Lindquist et al.
patent: 5939483 (1999-08-01), Kueppers
patent: 6008148 (1999-12-01), Harris et al.
patent: 6114261 (2000-09-01), Strelow et al.
patent: 6180229 (2001-01-01), Becker et al.
patent: 6184285 (2001-02-01), Hatfield et al.
patent: 6197845 (2001-03-01), Janssen et al.
patent: 34 28 917 (1986-02-01), None
patent: 0 442 045 (1991-08-01), None
patent: WO96/07385 (1996-03-01), None
patent: WO96/16682 (1996-06-01), None
patent: WO97/15636 (1997-05-01), None
patent: WO00/17286 (2000-03-01), None
Degussa-Huls, Klebstoff fur Hot-Melt Anwendungen, Creanova Coating Raw Materials, D-45764 Marl, Vestoplast, pp. 3-35.
Eisfeld Heike
Taal Eduard Franciscus
Voss Ruediger
Harper Stephen D.
Henkel Kommanditgesellschaft auf Aktien
Murphy Glenn E. J.
Szekely Peter
LandOfFree
Hot-melt adhesive of low viscosity does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hot-melt adhesive of low viscosity, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hot-melt adhesive of low viscosity will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3327071