Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2000-01-31
2002-08-06
Gallagher, John J. (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C264S045400, C442S370000, C526S317100, C526S318200
Reexamination Certificate
active
06428652
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a process for laminating textile sheet materials onto moldable particle foam or onto foamed moldings, using a polymer composition as an adhesive.
2. Background Art
The trend toward increasingly lightweight components for use in motor vehicles and aircraft, and also in products for sport and leisure, has led to the development of foamed moldings with high mechanical stability and the greatest possible reduction in weight. To produce these foamed moldings, successful use has been made of materials such as expandable polystyrene (EPS) or expandable compositions based on EPS and polyphenylene oxide (PPO). The latter is available, for example, with the trade name Noryl® EF (registered trademark of General Electric Co. USA).
These compositions, such as EPS, EPE (expandable polyethylene) and EPP (expandable polypropylene) can be foamed with steam in suitable molds to give the desired moldings. This process known per se permits convenient production of moldings for interior automotive trim, for example door paneling, side-impact cushioning, knee cushioning, cores for headrests, sun visors and parcel shelves, and also for external applications, such as bumpers. Examples of applications unrelated to motor vehicle construction are sports products, such as surfboards.
However, some of the applications listed above cannot be exploited using the foamed parts by themselves. High requirements—for example for visual quality or for a high minimum level of dimensional stability and also low thermal expansion—mean that the foamed moldings have to be coated with an outer skin.
The usual flexible films are used here, with or without a foam backing, and in particular textiles or fiber webs. The latter are permeable to water vapor and are placed into the appropriate molding tool prior to B the actual foaming-on procedure. A process of this type is termed in-mold skinning and is described, for example, in the GE Plastics brochure Noryl® EF Profile (page 19). To provide adhesion here between the foam and the fiber web, use is made of hot-melt adhesives, the activation temperature of which must not be higher than the glass transition temperature of the foam material. Using these adhesives it is not, of course, possible to obtain high heat resistance in the laminates, in particular above 80° C. (since the adhesives soften).
EP-A 623491 has disclosed a material for automotive bodywork paneling components, composed of a foam core enclosed in a tube. The tube here is adhesive-bonded to the foam core or secured to it using heat.
Another in-mold skinning process for a door-paneling support is described in EP-A 710578. Here, a glass-fiber mat is placed into the molding tool prior to the actual foaming process, and the expanding foam is foamed onto a glass web without the need for any binder. However, this process, too, gives unsatisfactory strength of the glass-web/foam bond at temperatures above 80° C.
SUMMARY OF THE INVENTION
Since the automotive industry typically requires resistance to temperatures of 80° C. and above for support systems of this type and for self-supporting moldings, the object on which this invention is based was to provide a process which can bond textile sheet materials, preferably glass webs, durably, and with good heat-resistance, to moldable foam and to the resultant foamed moldings. To avoid unnecessary operations and the costs associated with these, application of the binder system to the glass web to be laminated should preferably precede in-mold skinning, but the system should not be activated until the foaming procedure takes place.
The invention provides a process for laminating textile sheet materials onto moldable particle foam or onto foamed moldings, using, as an adhesive, a polymer composition based on copolymers of one or more monomers selected from the group comprising vinyl esters, acrylates, methacrylates, vinylaromatics and vinyl chloride and from 0.01 to 25% by weight, based on the total weight of the copolymer, of one or more ethylenically unsaturated monomers containing carboxyl groups.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Suitable copolymers containing carboxyl groups are those based on one or more monomers selected from the group comprising vinyl esters of unbranched or branched alkylcarboxylic acids having from 1 to 15 carbon atoms, methacrylates and acrylates of alcohols having from 1 to 10 carbon atoms, vinylaromatics, such as styrene, and vinyl chloride. Preferred vinyl esters are vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl laurate, 1-methylvinyl acetate, vinyl pivalate and vinyl esters of alpha-branched mono-carboxylic acids having from 5 to 11 carbon atoms, for example VeoVa5® (Shell Company) and VeoVa9®. Preferred methacrylates and acrylates are methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, n-butyl acrylate, n-butyl methacrylate and 2-ethylhexyl acrylate.
Preferred copolymers containing carboxyl groups are those of vinyl acetate, if desired with other vinyl esters, such as VeoVa9®; of vinyl chloride, if desired with vinyl acetate; copolymers of vinyl acetate with methacrylates or with acrylates; copolymers of methacrylates and/or acrylates; and particularly preferably copolymers of styrene and the acrylates mentioned, in each case containing from 0.01 to 25% by weight of monomer units containing carboxyl groups.
Suitable ethylenically unsaturated monomers containing carboxyl groups are ethylenically unsaturated mono- or dicarboxylic acids, such as acrylic acid, methacrylic acid, maleic acid, fumaric acid and itaconic acid. The content of comonomer units containing carboxyl groups is preferably from 0.01 to 15% by weight, based on the total weight of the copolymer.
If desired, the copolymers may also contain from 0.01 to 10.0% by weight, based on the total weight of the copolymer, of comonomers selected from the group consisting of ethylenically unsaturated carboxamides, preferably acrylamide, selected from the group consisting of ethylenically unsaturated sulfonic acids and salts of these, preferably vinylsulfonic acid, selected from the group consisting of comonomers with more than one ethylenic unsaturation, for example divinyl adipate, diallyl maleate, allyl methacrylate or triallyl cyanurate, and/or selected from the group consisting of N-methylol(meth)acrylamides and ethers of these, such as isobutoxy or n-butoxy ethers.
In a particularly preferred embodiment, the copolymers contain in each case from 0.01 to 10% by weight of acrylic acid and/or methacrylic acid, if desired, combined with from 0.01 to 2% by weight of acrylamide.
The composition of the copolymer is preferably selected to give a glass transition temperature Tg or a melting point of above 30° C., preferably from 55 to 150° C. The glass transition temperature Tg and the melting point of the polymers may be determined in a known manner using differential scanning calorimetry (DSC). The Tg may also be approximated using the Fox equation. According to T. G. Fox, Bull. Am. Physics Soc. 1, 3, page 123 (1956): 1/Tg=x
1
/Tg
1
+x
2
/Tg
2
+ . . . +x
n
/Tg
n
, where x
n
is the fraction by weight (% by weight/100) of the monomer n and Tg
n
is the glass transition temperature in degrees Kelvin of the homopolymer of the monomer n. Tg values for homopolymers are listed in Polymer Handbook 2 nd Edition, J. Wiley & Sons, New York (1975).
The weight-average molecular weight Mw is preferably from 10,000 to 400,000, particularly preferably from 60,000 to 300,000. The molecular weight and the molecular weight distribution may be adjusted in a known manner during the polymerization, for example, by using chain transfer agents and via the temperature of polymerization, and can be measured using gel permeation chromatography (GPC).
The copolymers are prepared in a manner known per se, preferably by emulsion polymerization, as described, for example, in WO-A 94/20661, the relevant disclosure of which is inco
Bauer Doris
Hashemzadeh Abdulmajid
Kolhammer Klaus
Schmidt Claudia
Brooks & Kushman P.C.
Gallagher John J.
Wacker Polymer Systems GmbH & Co. KG
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