Backed sanitaryware and process for the production thereof

Details Backed sanitaryware and process for the production thereof Backed sanitaryware and process for the production thereof

2000-01-19

2003-01-21

Kelly, Cynthia H. (Department: 1774)

Stock material or miscellaneous articles

Structurally defined web or sheet

Including components having same physical characteristic in...

C604S387000, C604S389000

Reexamination Certificate

active

06509086

ABSTRACT:

DESCRIPTION
This process relates to backed sanitaryware and to a process for the production of such sanitaryware.
In particular, the invention relates to baths or shower trays and basins which preferably comprise a thermoformed acrylic polymer moulding, the reverse of which is reinforced with a polymer material containing neither glass fibre nor asbestos and preferably of a thickness of 1.5 to 10 mm, which material is firmly bonded to the acrylic polymer moulding, in particular without additional coupling agents, wherein this reinforcement is obtainable by polymerising a (meth)acrylate system.
The following publications are cited as close prior art:
D
1
=EP-A-0 693 503;
D
2
=WO 98/45375=PCT/EP98/01881; and
D
3
=DE 197 14 399 A1.
Reinforced sanitaryware which comprises a thermoformed acrylic polymer moulding, the reverse of which is reinforced with a layer of a polymer material containing fibres, which material is firmly bonded to the acrylic polymer molding without additional coupling agents, is known from EP-A-0 693 503 (=D1).
Such backed sanitaryware is characterised in that the reinforcing layer is 1 to 5 mm thick and is obtainable by curing a polymerisable, cold-curing, reactive (meth)acrylate system sprayed onto the reverse of the acrylic polymer moulding. Essential constituents of the (meth)acrylate system in this case comprise, in addition to the polymerisable constituents, a redox system, finely divided fillers and 10-50 wt. % of chopped glass fibre for reinforcement.
D1 also discloses a process for the production of backed sanitaryware, in which a reactive resin system is sprayed onto the reverse of an acrylic polymer moulding, wherein the resin system cures in contact with the acrylic polymer moulding, so bonding to the acrylic polymer moulding, wherein a resin system predominantly based on (meth)acrylates is used, which cures to form a polymer having a glass transition temperature Tg of >70° C. and, relative to 1 part by weight of the resin system, may comprise up to 2.33 parts by weight of such fillers which are inert under the depolymerisation conditions of the acrylic polymer moulding. The wording of the process claim according to D1 indicates that the presence of chopped glass fibre is not absolutely essential. However, chopped glass fibre is used as a reinforcing material in all the Examples.
One advantage of the known backed sanitaryware should apparently be that it should be straightforwardly possible to reprocess it by depolymerisation (providing that appropriate finely divided fillers have been selected). While this is indeed entirely true with regard to the finely divided fillers disclosed in D1, the chopped glass fibre required in large quantities for reinforcement do present problems during depolymerisation, as has unfortunately been confirmed by extensive practical experience. While it is indeed theoretically possible to assume that the chopped fibre from the used parts will collect on the surface of the metal bath required for depolymerisation and it will be possible to skim them off with a vane or blade, it has been found that a non-negligible quantity of chopped fibre remains in the metal bath and cannot straightforwardly be removed. Moreover, in principle, similar occupational hygiene concerns apply to chopped glass fibre as apply to asbestos fibres. It is not straightforwardly possible to avoid exposing operating personnel to the health hazard posed by chopped glass fibre, some of which is in fine particulate form, during depolymerisation. Dispensing with such fibrous fillers is thus, in itself, highly desirable.
Furthermore, at least some of the methacrylate systems on which prior art reinforcing layers are based have a tendency towards curing problems, such as entrapped air etc.. The chopped glass fibre used for reinforcement stands out, i.e. once sprayed on, the fibres, which are some centimetres in length, do not lie flat on the reverse of the moulding, but instead, due to tangling within the reinforcing material, protrude to a greater or lesser extent from the plane of the moulding. Rolling is accordingly essential in order to prevent curing problems and to press the fibre reinforcement into the surface. This manual secondary finishing (i.e. performed by hand) is elaborate and increases the cost of the product.
Solutions containing no chopped glass fibre are known from D2. Backed sanitaryware is disclosed which comprises an acrylic polymer moulding, the reverse of which is reinforced with a polymer material containing neither glass fibre nor asbestos and of a thickness of 1.5 to 10 mm, which material is firmly bonded to the acrylic polymer moulding without additional coupling agents, wherein the reinforcing material or reinforcement is obtainable by curing a polymerisable, cold-curing reactive (meth)acrylate system sprayed onto the reverse of the acrylic polymer moulding, which system is characterised in that it comprises, as an essential filler, hollow microparticles filled with inert gas in a quantity of 0.1 to 50 wt. %, relative to the entire weight of the (meth)acrylate system. Using gas-filled, expanded hollow plastics microspheres preferably coated with calcium carbonate as a filler in the (meth)acrylate system results in an improvement of the mechanical properties of the backing layer, in particular with regard to impact strength, tensile bond strength and flexural strength, and with regard to testing to DIN EN 198 (alternating hot water test and falling ball test).
D2 furthermore discloses sanitaryware having two-layer backing layers. Preferably, a first backing layer provides the necessary impact strength while a second (outer) backing layer imparts the rigidity required for practical service to the sanitaryware. The (meth)acrylate system which provides the first layer preferably has a relatively high content of relatively long-chain (meth)acrylates, which have ester residues having five or more carbon atoms, while the content of such monomers in the (meth)acrylate system of the second layer is 0 to less than 10 wt. %. The (pre)polymers which are essentially present in the particular resin system may also differ. The (pre)polymer of the first reinforcing layer may accordingly have a comonomer content of between 30 and 80 wt. %, while the comonomer content in the (pre)polymer of the second backing layer is preferably between 0 and <30 wt. %.
Although the sanitaryware according to D2 performs excellently in practice, the industrial production of two backing layers is complex. Processors must accordingly hold stocks of and process two resin systems. There is a drying step between the two application steps.
It should be noted with regard to the hollow microsphere fillers that, due to the elevated compressibility thereof, they are not readily sprayed using conventional spraying equipment. This entails the development of new spray processing equipment.
Moreover, the mechanical properties of the sanitaryware backed using hollow microspheres merit further improvement.
Single-layer solutions are moreover known from D
3
, in which a thermoformed acrylic polymer moulding, the reverse of which is reinforced with polymer material containing neither glass fibre nor asbestos, which material is firmly bonded to the acrylic polymer moulding without additional coupling agents, is distinguished in that the reinforcing material is 1.5 to 10 mm thick and is obtainable by curing a polymerisable, cold-curing, reactive (meth)acrylate system sprayed onto the reverse of the acrylic polymer moulding, which system contains
A)
(meth)acrylate
30-100
wt. %
methyl (meth)acrylate
0-100
wt. %
C
2
-C
4
(meth)acrylate
0-100
wt. %
≧C
5
(meth)acrylate
0-50
wt. %
polyfunctional
0-50
wt. %
(meth)acrylates
comonomers
0-50
wt. %
vinyl aromatics
0-30
wt. %
vinyl esters
0-30
wt. %
B) per 1 part by weight of A), 0.05-5 parts by weight of a (pre)polymer soluble or swellable in A)
C) a redox system containing an accelerator and a peroxide catalyst or initiator in a quantity sufficient for cold-curing component A), which system is to b

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