Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2000-06-13
2002-12-17
Chen, Vivian (Department: 1773)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S297000, C156S299000, C156S306900, C156S308200, C156S244110, C156S244270, C156S245000
Reexamination Certificate
active
06494982
ABSTRACT:
The present invention relates to a layered composite material comprising a backing made from a thermoplastic polymer, an intermediate layer arranged thereupon, and a heat-cured layer applied to the intermediate layer, where the bonding material of the intermediate layer is a thermoplastic. The present invention further relates to a process for producing this layered composite material and to its use for producing furniture, floorcoverings, wall paneling, household equipment or moldings in the electrical, construction or automotive industry.
The layered composite materials known hitherto are used in particular in the furniture industry and in the household equipment industry and essentially consist of a backing layer made from wood or from wood fibers or from individual sheets of paper press-molded with addition of resin, to which decorative layers, and also other heat-cured layers, known as overlays, are applied using heat and pressure. The decorative layers used here frequently have a woodgrain, metallic or marble pattern. In many cases the decorative layers are used together with the heat-cured layers applied thereto, in the form of laminates.
However, a disadvantage of layered composite materials of this type is that they are to some extent susceptible to moisture penetrating into the core layer from the edges, since both wood and wood fibers, and also individual sheets of paper, tend to swell when exposed to moisture. In addition, layered composite materials of this type are relatively difficult to shape.
For a wide variety of industrial applications, for example in the automotive or electrical industry, there is a need for surface materials which, on the one hand, have high compressive strength and, on the other hand, have comparatively high heat resistance, and which moreover can readily be produced with decorative effects.
Surface materials used for a long time in furniture production have two or more layers, including a backing layer, a decorative layer and a heat-cured layer lying thereupon. These layers, with the aid of other bonded layers, for example made from paper or from adhesive films, give a decorative layered composite material. However, a layered composite material of this type is very complicated to produce, frequently has a high formaldehyde content, and has disadvantageous swelling behavior.
DE-A 1 97 22 339 discloses a layered composite material which comprises a backing layer made from polypropylene, a decorative layer arranged thereupon and a heat-cured layer applied to the decorative layer. The earlier application DE-A 19 858 173 moreover describes a layered composite material made from a backing layer of various other thermoplastic polymers, for example certain styrene copolymers or polyoxymethylene or, respectively, polybutylene terephthalate, and also a decorative layer applied thereto and a heat-cured layer lying thereupon. Examples of features of layered composite materials of this type with a backing layer made from thermoplastic polymers are, when compared with conventional layered composite materials with backing layers made from wood, wood fibers or paper: high heat and moisture resistance, better mechanical strength and easier processing. However, a degree of stiffness and brittleness in the individual polymeric layers means that the layered composite materials known from DE-A 19 722 339 and DE-A 19 858 173 still have certain disadvantages in processing and shaping, in particular in three-dimensional shaping to give components for the automotive sector, the household sector or the electrical sector. In addition, layered composite materials of this type are sometimes also found to have unsatisfactory mechanical stability, attributable to a slight deficiency in adhesion between the backing layer and the decorative layer or, respectively, the heat-cured layer.
It is an object of the present invention to overcome the disadvantages described and to provide an improved layered composite material which, inter alia, can very easily be shaped in two or three dimensions and, due to high adhesion between the individual layers, has very high mechanical stability. This layered composite material should also be very easy to pigment.
We have found that this object is achieved by developing an improved layered composite material comprising a backing made from a thermoplastic polymer, an intermediate layer arranged thereupon, and a heat-cured layer applied to the intermediate layer, where the bonding material of the intermediate layer is a thermoplastic.
In one modification of the novel layered composite material, this may also comprise a decorative layer applied to the intermediate layer between the intermediate layer and the heat-cured layer. In the novel layered composite material it is also possible for an appropriate intermediate layer, a decorative layer arranged thereupon, if desired, and a heat-cured layer applied either to the intermediate layer or else to the decorative layer to be present on both sides of the backing made from the thermoplastic polymer, giving a sandwich structure with the backing layer in the middle.
The material of the backing may comprise based on the total weight of the backing, from 1 to 60% by weight, preferably from 5 to 50% by weight, particularly preferably from 10 to 40% by weight, of reinforcing fillers, such as barium sulfate, magnesium hydroxide or talc with an average particle size of from 0.1 to 10 &mgr;m, measured to DIN 66 115, wood, flax, chalk, glass fibers, coated glass fibers, long or short glass fibers, glass beads or mixtures of these. The material of the backing may also comprise the usual additives, such as stabilizers to protect against the action of light, UV radiation or heat, pigments, carbon blacks, lubricants, flame retardants, blowing agents and the like, in the amounts which are usual and required.
Examples of thermoplastic polymers which form the backing are polypropylene, polyethylene, polyvinyl chloride, polysulfones, polyether ketones, polyesters, polycycloolefins, polyacrylates and polymethacrylates, polyamides, polycarbonate, polyurethanes, polyacetals, such as polyoxymethylene, polybutylene terephthalates and polystyrenes. Both homopolymers and copolymers of these thermoplastic polymers may be used here. The backing layer preferably also comprises, besides the reinforcing fillers, polypropylene, polyoxymethylene, polybutylene terephthalate or polystyrene, in particular styrene copolymers with subordinate proportions of one or more comonomers, such as butadiene, &agr;-methylstyrene, acrylonitrile, vinylcarbazole, or else esters of acrylic, methacrylic or itaconic acid. The backing of the novel layered composite material may also comprise recycled materials made from these thermoplastic polymers.
For the purposes of the present invention, polyoxymethylenes are homo- or copolymers of aldehydes, for example of formaldehyde, or of cyclic acetals, containing recurring carbon-oxygen bonds in the molecule and having a melt flow rate (MFR) to ISO 1133 of from 5 to 40 g/10 min, in particular from 5 to 30 g/10 min, at 230° C. with a load of 2.16 kg.
The polybutylene terephthalate preferably used is a higher-molecular-weight esterification product of terephthalic acid and butylene glycol with a melt flow rate (MFR) to ISO 1133 of from 5 to 50 g/10 min, in particular from 5 to 30 g/10 min, at 230° C. with a load of 2.16 kg.
Possible styrene copolymers are in particular copolymers having up to 45% by weight, preferably up to 20% by weight, of copolymerized acrylonitrile. Copolymers of this type made from styrene and acrylonitrile (SAN) have a melt flow rate (MFR) to ISO 1133 of from 1 to 25 g/10 min, in particular from 4 to 20 g/10 min, at 230° C. with a load of 2.16 kg.
Other styrene copolymers whose use is likewise preferred contain up to 35% by weight, in particular up to 20% by weight, of copolymerized acrylonitrile and up to 35% by weight, in particular up to 30% by weight, of copolymerized butadiene. The melt flow rate of copolymers of this type made from styrene, acrylonitrile and butadiene (ABS)
Klemm Klaus
Müller Klaus
Chen Vivian
Targor GmbH
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