Method and Gasket for Producing a Polymethyl Methacrylate Plate

Abstract

The invention relates to a method for producing a polymethyl methacrylate plate, comprising the steps of providing a mould comprising at least one gasket which is enclosed between two substantially parallel mould parts, introducing liquid comprising methyl methacrylate prepolymer and/or methyl methacrylate monomer in the mould and enabling polymerization of the liquid methyl methacrylate. The invention also relates to a gasket for use in a mould for producing a polymethyl methacrylate plate.

Claims

1. Method for producing a polymethyl methacrylate plate, comprising the steps of: A) providing a mould comprising at least two mould parts, each mould part having at least one substantially flat mould surface facing an substantially flat mould surface of an opposing mould part, and wherein said mould comprises at least one gasket, which gasket comprises polymethyl methacrylate, and which gasket is clamped in between said substantially flat mould surfaces of opposing mould parts, such that a mould cavity is defined by said mould parts and said gasket, B) at least partially filling the mould cavity by introducing liquid comprising methyl methacrylate prepolymer and/or methyl methacrylate monomer into the mould cavity, C) polymerization of the methyl methacrylate prepolymer and/or methyl methacrylate monomer introduced in the mould cavity, such that a polymethyl methacrylate plate, enclosed by said gasket, is formed within said mould cavity, and D) removal of the assembly of the gasket and said polymethyl methacrylate plate enclosed by said gasket from the mould parts.

2. Method according to claim 1, wherein at least part of the gasket comprises extruded polymethyl methacrylate, and wherein the gasket is preferably substantially fully made of extruded polymethyl methacrylate.

3. Method according to claim 2, wherein the gasket comprises at least one additive configured to impede dissolution of polymethyl methacrylate of the gasket into the liquid comprising methyl methacrylate prepolymer and/or methyl methacrylate monomer during step B and/or step C).

4. Method according to claim 1, wherein the gasket has an elongated, preferably oval or rectangular, cross-section.

5. Method according to claim 1, wherein at least part of the gasket is hollow.

6. Method according to claim 1, wherein the gasket is an annular gasket.

7. Method according to claim 1, wherein at least part of the outer surface of the gasket is profiled.

8. Method according to claim 1, wherein the width-to-depth ratio of the gasket when clamped in between two substantially flat mould part surfaces is at least 1.5, preferably at least 2, more preferably at least 2.5.

9. Method according to claim 1, wherein the gasket comprises recycled polymethyl methacrylate.

10. Method according to claim 1, wherein at least one sleeve encloses the gasket.

11. Method according to claim 1, wherein opposing mould surfaces of the mould have a substantially parallel orientation, at least during step C).

12. Method according to claim 1, wherein during step C) the gasket is bound to the polymethyl methacrylate plate.

13. Method according to claim 12, further comprising step E), which comprises the step of cutting at least one and preferably each edge part of the polymethyl methacrylate plate such that at least the gasket is removed from the plate.

14. Method according to claim 13, wherein during step E) at least one and preferably each edge part of the polymethyl methacrylate plate such that both the gasket and a peripheral portion of the polymethyl methacrylate plate, bound to said gasket, are removed.

15. Polymethyl methacrylate plate produced via the method of claim 1.

16. Gasket for use in a mould for producing a polymethyl methacrylate plate via the method of claim 1, wherein the gasket comprises polymethyl methacrylate.

17. Assembly of at least part of a gasket according to claim 16 and at least part of a polymethyl methacrylate plate bound to said gasket.

18. Mould for use in a method for producing a polymethyl methacrylate plate, according to claim 1, comprising at least two mould parts, each mould part having at least one substantially flat mould surface facing an substantially flat mould surface of an opposing mould part, and wherein said mould comprises at least one gasket, which gasket comprises polymethyl methacrylate, and which gasket is clamped or clampable in between said substantially flat mould surfaces of opposing mould parts, such that a mould cavity is defined by said mould parts and said gasket.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] The invention will be elucidated on the basis of non-limitative exemplary embodiments shown in the following figures.

[0026] FIGS. 1a and 1b show a schematic representation of a mould 100 for producing a polymethyl methacrylate plate (not shown) according to the present invention for use in the method according to the present invention. FIG. 1a shows a side view of the mould 100, where FIG. 1b shows a top view. The mould 100 comprises two substantially parallel mould parts, in particular panels 102a, 102b preferably glass panels 102, and gasket 101. The substantially annular gasket 101 is enclosed between two substantially parallel panels 102a, 102b. The gasket 101 is clamped between the panels 102a, 102b via multiple clamping elements 104. Introduction of liquid comprising methyl methacrylate prepolymer and/or methyl methacrylate monomer into the mould 100 can be done via conventional methods. The liquid can for example be introduced into the receiving space 105 defined by the mould 100 before the panels 102a, 102b and the gasket 101 are fully clampingly connected via the clamping elements 104. The gasket 101 according to the present invention comprises (extruded) polymethyl methacrylate.

[0027] FIGS. 2a-2c show schematic representations of cross sections of possible embodiments of gaskets 201a, 201b, 201c according to the present invention. Each gasket 201a, 201b, 201c are enclosed between two parallel (glass) panels 202a, 202b.

[0028] FIG. 2a shows a gasket 201a being made of extruded PMMA wherein the gasket is hollow. Hence the gasket 201a shown is a substantially tubular gasket 201a. The wall of the gasket 201a encloses a hollow space 203a. The wall thickness D of the gasket 201a is substantially constant over the entire gasket 201a. It is however, also conceivable that the wall thickness locally varies, for example over the length and/or width of the gasket 201a. The width-to-depth ratio of the gasket is about 2, hence the width w of the gasket 201a is about twice the length of the depth d of the gasket 201a in the shown position wherein the gasket 201a is enclosed between the panels 202a, 202b.

[0029] FIG. 2b shows a PMMA gasket 201b wherein the outer surface of the gasket 201b is profiled. The outer surface of the gasket 201b comprises a (regular) pattern of little protrusions.

[0030] FIG. 2c shows a further embodiment of a hollow gasket 201c having an outer surface which is partially profiled. The profiling is present at the areas of the gasket 201c which are in contact with the panels 202a, 202b. The gasket 201c comprises two hollow spaces 203b, 203c. The wall thickness D1 of the wall facing inwardly is larger than the wall thickness D2 of the wall facing towards the parallel panels 202a, 202b. Swelling, or expanding of the gasket 201c may cause the area of the hollow spaces 203b, 203c to reduce.

[0031] FIG. 3a show a PMMA plate 300 produced via a method according to the present invention. The panels of the mould are removed in the shown embodiment, such that a PMMA plate 310 which is enclosed by the gasket 301 remains. In order to provide a PMMA plate 310 which is usable for varies applications it is desired that the circumferential sides or edges of the plate 310 are removed. The cutting lines in the figure indicate where the plate 310 for example can be trimmed. The removed gasket 301 and part of the PMMA plate 310 form PMMA scrap.

[0032] FIG. 3b shows a detailed view of an edge part of the PMMA plate 310 shown in FIG. 3a. Hence, FIG. 3b show part of the scrap or residue formed after trimming. The gasket 301 comprises extruded PMMA. The figure shows that the MMA monomer or MMA prepolymer before polymerization has caused part of the PMMA of the gasket 301 to dissolve in the MMA liquid. Hence, after polymerization a region M comprising a mixture of cast PMMA (C) of the plate 310 and extruded PMMA (E) of the gasket 301 is obtained. The It is also conceivable that depolymerization of the mixed fraction of hard and soft PMMA is performed.

[0033] Hence, the above-described inventive concepts are illustrated by several illustrative embodiments. It is conceivable that individual inventive concepts may be applied without, in so doing, also applying other details of the described example. It is not necessary to elaborate on examples of all conceivable combinations of the above-described inventive concepts, as a person skilled in the art will understand numerous inventive concepts can be (re)combined in order to arrive at a specific application.

[0034] It will be apparent that the invention is not limited to the working examples shown and described herein, but that numerous variants are possible within the scope of the attached claims that will be obvious to a person skilled in the art.

[0035] The verb “comprise” and conjugations thereof used in this patent publication are understood to mean not only “comprise”, but are also understood to mean the phrases “contain”, “substantially consist of”, “formed by” and conjugations thereof.