[0001] This invention relates to an article (especially a piece of furniture or sanitary
ware) having a polymethyl methacrylate surface region reinforced by another member.
[0002] Hitherto, so-called 'Perspex' baths have comprised a polymethyl methacrylate surface
region reinforced by spraying curable polyester resin onto the back of the surface
region and curing the resin to form a rigid backing which adheres to and reinforces
the surface region. Such backings must be sprayed and cured in situ on the bath and
cannot be pre-formed economically.
[0003] This invention provides an article having a polymethyl methacrylate surface region
reinforced by a thermoplastics member having a surface shaped to conform to the shape
of polymethyl methacrylate surface region. The surface region may be flat or it may
be contoured and in register with a correspondingly shaped surface on the thermoplastics
member. Examples of articles having flat surface regions include table tops and panels
for cabinets or the fronts of drawers and examples of articles having contoured surface
regions include baths, washbasins (especially vanity units) and chair shells and some
or all of these articles may be designed to form a matching bathroom suite. The thermoplastics
member can be preformed by mass production techniques such as melt-shaping and more
particularly injection moulding, vacuum forming or rotational moulding. Additionally,
thermoplastics members can easily be made with other features such as accommodation
for cupboards and drawers.
[0004] An article according to the invention may be made by a method in which the polymethyl
methacrylate surface region is applied to the thermoplastics member which has been
pre-formed by a melt-shaping process which provides the member with a surface shaped
to conform to the shape of surface region of the finished article. The polymethyl
methacrylate surface region may be assembled on the conforming surface of the pre-formed
thermoplastics member and held in place by bolts, rivets or clamps preferably positioned
around the perimeter of the surface region or by adhesives. Contoured surfaces may
be sufficiently intimately in register as to avoid the need for additional holding
means especially if the surface region and thermoplastics member are resilient and
the contour is shaped to define a snap-action fit between them.
[0005] Alternatively, the polymethyl methacrylate surface region may be applied to the conforming
surface of the thermoplastics support by using the conforming surface as one part
of a mould which defines the surface region, filling the mould with a syrup of methyl
methacrylate monomer and polymerising the monomer in contact with the conforming surface
so as to produce a polymethyl methacrylate surface region which is in intimate contact
with the conforming surface.
[0006] A further advantage of the use of a pre-formed thermoplastics reinforcing member
is that they readily permit decorative interlayers to be sandwiched between the pre-formed
member and a transparent or translucent polymethyl methacrylate surface region through
which the decorative interlayer is visible. Examples of interlayers include optionally
printed metal foil, thermoplastics film, paper or cloth. Many interlayers can be made
integral with the thermoplastics member by melt-shaping the member against the interlayer.
Similarly the surface region may be made integral with many interlayers by polymerising
methyl methacrylate in contact with the interlayer which may optionally already be
integral with the thermoplastics member.
[0007] A preferred cloth interlayer comprises a so-called melded cloth, that is to say a
cloth composed of contiguous thermoplastics fibres welded together at various points
throughout the cloth. Normally the cloth comprises conjugate fibres formed from at
least two chemically different thermoplastics. Preferred conjugate fibres comprise
two chemically different nylons or polyethylene and polypropylene. Melded cloths have
the advantage that many thermoplastics can be injection moulded onto them without
penetrating through the cloth and destroying its textile appearance.
[0008] The thermoplastics members are preferably made from crystalline polyolefins such
as low or high density polyethylenes or preferably homopolymers of propylene or the
so-called sequential copolymers of propylene made by injecting from 2 to 15% by weight
of ethylene into the latter stages of an otherwise propylene homopolymerisation process.
The polyolefins preferably have melt flow indices of from 0.5 to 25 g/10 minutes (especially
1 to 4 g/10 minutes) as measured according to British Standard 2782:Part 1/105C/1976
using a 2.16 Kg load and performed at 230°C for propylene polymers and at 190°C for
polyethylenes.
[0009] The thermoplastics members may be solid or they may comprise a structural foam, that
is to say a skin of thermoplastics material enclosing a foamed core of for example
foamed polyolefin or foamed polyurethane.
[0010] The polymethyl methacrylate used in the performance of this invention may be a homopolymer
of methyl methacrylate or a copolymer with up to 10% by weight of copolymerisable
monomers such as alkyl acrylates (especially ethyl acrylate) or styrene.
[0011] The invention is further illustrated by the following specific embodiments described
with reference to the drawings in which:
Figure I shows a section of a bath.
Figure 2 shows on a larger scale in partial section a modification to the bath shown
in Figure 1.
Figure 3 shows in partial section a further modification to the bath shown in Figure
1.
Figure 4 shows in partial section a third modification to the bath shown in Figure
1.
Figure 5 shows in section an end portion of the modified bath of Figure 2.
Figure 6 shows in section a chair shell.
Figure 7 shows in perspective the chair shell of Figure 6.
[0012] Figure 1 shows a bath 1 consisting of a vacuum-formed contoured transparent polymethyl
methacrylate surface region 2 in register with a correspondingly contoured surface
3 of a polypropylene reinforcing member 4 which reinforces surface region 2. Surface
region 2 is held in place by rivets 5.
[0013] Figure 2 shows a modification to bath 1 effected by sandwiching a decorative sheet
6 of melded cloth between transparent surface region 2 and surface 3. Sheet 6 is visible
through surface region 2.
[0014] Figure 3 shows a further modification to bath 1 in which sheet 6a of melded cloth
is integral with surface 3a of member 4a.
[0015] Figure 4 shows a third modification to bath 1 in which sheet 6b of melded cloth is
integral with surface region 2a.
[0016] Figure 5 shows an end portion for a bath 1 modified as in Figure 2, the end portion
consisting of a sheet 26 of melded cloth sandwiched between surface region 22 and
surface 23. Surface region 22 has a down-turned end 28 into which a groove 29 has
been cut. End 27 of member 24 is chamfered and makes a close fit in groove 29. Down-turned
end 28 and member 24 are resilient so that on placing surface region 22 over member
24, groove 28 and chamfered end 27 engage with a snap action and hold surface region
22 in place on member 24.
[0017] Figure 6 shows a chair shell 31 consisting of a contoured transparent polymethyl
methacrylate surface region 32 in register with a correspondingly contoured surface
33 of a polypropylene reinforcing member 34 which reinforces surface region 32 and
a sheet 36 of melded cloth integral with surface 33 and sandwiched between surface
33 and surface region 32. The edges 35 of member 34 are turned over and embrace the
edges of surface region 32 and sheet 36 holding them in place and forming a trim 38
(as shown in Figure 7) around surface region 32. Edges 35 are resilient so that on
assembling surface region 32 on member 34, edges engage surface region 32 with a snap
fit.
[0018] Figure 8 shows a check pattern 40 provided on sheet 36 and visible through transparent
surface region 32.
[0019] In a modification of this invention, the surface region may be made from an alternative
organic thermoplastics material, preferably a transparent material instead of polymethyl
methacrylate. Examples of possible transparent materials include transparent polystyrene,
polyvinyl chloride, polycarbonates and cellulosic materials such as cellulose acetates
and butyrates.
1. An article having a polymethyl methacrylate surface region reinforced by a thermoplastics
member having a surface shaped to conform to the shape of polymethyl methacrylate
surface region.
2. An article according to claim 1 wherein the polymethyl methacrylate surface region
is contoured and is in register with a correspondingly shaped surface on the thermoplastics
member.
3. An article according to claim 1 or claim 2 wherein the surface region and the thermoplastics
member make a snap-action fit.
4. An article according to any one of the preceding claims wherein a decorative interlayer
is sandwiched between the surface region and the conforming surface of the thermoplastics
member.
5. An article according to claim 4 wherein the decorative interlayer comprises a melded
cloth integral with the thermoplastics member.
6. An article according to any one of claims 1 to 5 wherein the thermoplastics member
comprises a structural foam.
7. A method for making an article as claimed in claim 1 wherein the polymethyl methacrylate
surface region may be applied to a preformed conforming surface of the thermoplastics
member by using the conforming surface as one part of a mould which defines the shape
of the surface region, filling the mould with a syrup of methyl methacrylate monomer
and polymerising the monomer in contact with the conforming surface so as to produce
a polymethyl methacrylate surface region which is in intimate contact with the conforming
surface.
8. A method according to claim 7 wherein the thermoplastics member is preformed by
injection moulding onto a melded cloth so as to have a conforming surface integral
with the melded cloth.