CA2232358A1 - Process for making a mineral filled acrylic sheet having a matte finish with improved stain resistance - Google Patents
Process for making a mineral filled acrylic sheet having a matte finish with improved stain resistance Download PDFInfo
- Publication number
- CA2232358A1 CA2232358A1 CA002232358A CA2232358A CA2232358A1 CA 2232358 A1 CA2232358 A1 CA 2232358A1 CA 002232358 A CA002232358 A CA 002232358A CA 2232358 A CA2232358 A CA 2232358A CA 2232358 A1 CA2232358 A1 CA 2232358A1
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- Prior art keywords
- film
- sheet
- mineral
- syrup
- sheets
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 title claims abstract description 19
- 238000000034 method Methods 0.000 title claims abstract description 17
- 229910052500 inorganic mineral Inorganic materials 0.000 title claims description 17
- 239000011707 mineral Substances 0.000 title claims description 17
- 239000002245 particle Substances 0.000 claims description 10
- 239000000203 mixture Substances 0.000 claims description 9
- 238000003856 thermoforming Methods 0.000 claims description 5
- VVQNEPGJFQJSBK-UHFFFAOYSA-N Methyl methacrylate Chemical compound COC(=O)C(C)=C VVQNEPGJFQJSBK-UHFFFAOYSA-N 0.000 claims description 2
- 239000011148 porous material Substances 0.000 claims description 2
- 239000006188 syrup Substances 0.000 claims 6
- 235000020357 syrup Nutrition 0.000 claims 6
- 229920000139 polyethylene terephthalate Polymers 0.000 claims 1
- 230000000379 polymerizing effect Effects 0.000 claims 1
- 229920002554 vinyl polymer Polymers 0.000 claims 1
- 239000012764 mineral filler Substances 0.000 abstract description 7
- 239000010408 film Substances 0.000 description 21
- 239000000047 product Substances 0.000 description 6
- 239000011159 matrix material Substances 0.000 description 4
- 238000005266 casting Methods 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 239000010410 layer Substances 0.000 description 2
- 239000004033 plastic Substances 0.000 description 2
- 229920003023 plastic Polymers 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 229920003002 synthetic resin Polymers 0.000 description 2
- 239000000057 synthetic resin Substances 0.000 description 2
- 239000010409 thin film Substances 0.000 description 2
- 150000004684 trihydrates Chemical class 0.000 description 2
- 230000037303 wrinkles Effects 0.000 description 2
- 101150050192 PIGM gene Proteins 0.000 description 1
- 239000004635 Polyester fiberglass Substances 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000001464 adherent effect Effects 0.000 description 1
- 238000004026 adhesive bonding Methods 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 238000001746 injection moulding Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- GWUSZQUVEVMBPI-UHFFFAOYSA-N nimetazepam Chemical compound N=1CC(=O)N(C)C2=CC=C([N+]([O-])=O)C=C2C=1C1=CC=CC=C1 GWUSZQUVEVMBPI-UHFFFAOYSA-N 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 239000002985 plastic film Substances 0.000 description 1
- 229920006255 plastic film Polymers 0.000 description 1
- -1 polyethylene Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 238000010186 staining Methods 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/18—Manufacture of films or sheets
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C39/00—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor
- B29C39/14—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor for making articles of indefinite length
- B29C39/148—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor for making articles of indefinite length characterised by the shape of the surface
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C51/00—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor
- B29C51/002—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor characterised by the choice of material
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/01—Use of inorganic substances as compounding ingredients characterized by their specific function
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2033/00—Use of polymers of unsaturated acids or derivatives thereof as moulding material
- B29K2033/04—Polymers of esters
- B29K2033/12—Polymers of methacrylic acid esters, e.g. PMMA, i.e. polymethylmethacrylate
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
- B29K2105/06—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts
- B29K2105/16—Fillers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
- B29K2995/0018—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds having particular optical properties, e.g. fluorescent or phosphorescent
- B29K2995/0024—Matt surface
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2333/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers
- C08J2333/04—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers esters
- C08J2333/06—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers esters of esters containing only carbon, hydrogen, and oxygen, the oxygen atom being present only as part of the carboxyl radical
- C08J2333/10—Homopolymers or copolymers of methacrylic acid esters
- C08J2333/12—Homopolymers or copolymers of methyl methacrylate
Abstract
A process for making acrylic sheets which contain mineral fillers and which can be thermoformed into integral top vanity tops or sinks. The sheets and thermoformed products thereof have a matte finish surface and appearance that does not require additional finishing steps such as sanding to create a uniform appearance. The sheets and thermoformed products possess good stain resistance, as measured by existing industry standards.
Description
W O 98/17713 PCTrUS97/062~0 PROCESS FOR l\LAKING A MINERAL FTT,T,F.O ACRYLIC ~
~IAVING A MATTE FINISH WITH IMPROVED STAIN RESISTANCE
Technical Field This invention relates to the m~mlf~ctllring of slab or sheets of poly (methyl methacrylate~ (PMMA) which contain mineral fillers and which can be thermoformed into such articles as vanity tops or sinks. In particular, this invention describes how to produce sheets or slabs with a matte finish surface and appearance that does not require additional finiching steps and provides good stain recict~n~e7 as measured by ~xi.cting industry standards.
Background of the Invention Sheets and slabs of synthetic mineral appearing m~teri~l are now commonly used as kitchen counter tops and interior and exterior decorative coverings of all kinds for buildings such as banks, air termin~l~, stores, and the like. Such applications frequently require that the material be fabricated to fit custom designed areas.
The fabrication process requires extensive time and specially trained craftsmen to be completed succçssfully, since special tools and procedures are necessary. Until recently, if a shaped, one piece part of continuous monolithic m~t~ri~l is desired, such a part could only be produced by casting it in a closed mold cavity under special conditions.
the silicone forms a release layer.
In Oshima et al., U. S. Patent No. 4,041,120 discloses an abrasion resistant surface layer for synthetic resin articles. However, that layer is firmly adherent to the base resin. Similarly, Toyooka et al., U. S. Patent No. 4,254,074 discloses synthetic resin sheets having a film, possibly bearing printing, ~lh~ring thereto.
CA 022323~8 l998-04-22 W 098/17713 PCTrUS97/OG200 Daff et al., in U. S. Patent No. 5,308,425 discloses a protective film placed on acrylic sheet. However, the present differs in that the film here is non-colnr~tihle with a mineral filled acrylic sheet. The non-compatibility must be to a degree such that the surface characteristics of the mineral filled sheet are not subst~nt~lly ch~n~ç~l Additionally, the r~sllltinf~ sheet will have a matte finish. Neither of these cha~ ;stics are present in Daff et al.
In U.S. Patent No. ~,521,243 ~inghetti et al., disclose the composition of a mineral appearing material which may be cast or otherwise formed into the shape of a sheet. These sheets are capable of being thermoformed into a vanity top or sink. As with prior art mineral appearing sheets, the post-polymerized sheet will have a glossy appearance. However, this glossy appearance becomes matte in areas of deep draw upon thermoforming. Thus, the final product will have a non-uniform appearance.
The same problem is experienced with non-thermoformed acrylic compositions such as those described by Ross et al., in U. S. Patent Nos. 4,961,995 and 5,032,625. In addition to the high costs associated with installation of the acrylic parts (placing the sheets into place, fitting, glueing, and the like) the intersection of adjacent sheets will necessarily be sanded to give a smooth fit. This s~n(1ing process will similarly remove the glossy appearance in that area, giving a non-uniform appearance.
To combat the difficulties listed above, mineral appearing sheets are often sanded in their entirety. This gives a uniform matte finish before and after the above applications are accomplished. However, the uniform ~nrlin~ process has its own distinct drawbacks.
Vi~n~li7in~ the contents of a mineral appearing acrylic sheet, mineral filler particles such as alumina trihydrate (ATH) will be dispersed throughout the acrylic matrix. Some of these particles will be very near the surface of the sheet. These particles near the surface will have a very thin film of acrylic covering them. When the surface of the sheet is subsequently sanded this thin film of acrylic is nnint~ntionally removed. The filler particles near the surface are then W O g8/17713 PCT~US97/062~0 exposed and some of them will have been cut in half (or more-or-less) by the s~n~ling One of the qualities possessed by acrylic sheets is stain reei~t~n~e. The acrylic surface resists absorption of foreign m~tçri~le commonly associated with the above-mentioned uses for mineral appearing products. When the mineral filler material such as ATH is exposed by s~n~ling, staining sllbst~n-.es will more easily penetrate the surface, by being absorbed directly by the ATH or by penetrating at the interf~ce of the ATH particles with the polymer matrix. This results in a poor aesthetic quality in the product.
The present invention overcomes this dra~,vback in the prior art. The mineral appearing sheets and products thermoformed therefrom of the present invention have a matte appearance.
There is no need for subsequent sanding procedures. The mineral filler particles near the surface are, for the most part, not exposed. Most, if not all, retain the acrylic film sepalaLirlg the particles from the outside enviromnent. The products of the present invention also have improved stain resistance when compared to typical matte surfaces in the prior art.
Summary of the Invention Acrylic sheets such as those described in U.S. Patent No. 5,521,243 can be produced with dif~~ l surface fini.eh~s which will change after lhermoforming and the appearance being unacceptable. When the hot sheet is sketched into a mold, there is a significant loss of gloss, which is variable and proportional to amount of stretching of any given unit of surface. If, for example, a bathroom vanity top is thermoformed fTom a sheet with a smooth finish, the resulting part will show:
- a minor change in gloss (slight decrease) in the flat area surround the bowl area, - a more noticeable change of gloss (moderate decrease) in the rim area around the bowl, W O98/17713 PCTnUS97/06200 - a very noticeable change of gloss (~ign;ffc~nt decrease to a dull finish) in the bottom or drain area of the bowl.
All this occurs because the polymer matrix stretches out and away from the solid particles of the mineral filler. This is a well known l~h~;nomc~on in the thermoforming of high gloss sheets where, at times, a small amount of pigm~ntc or solid powders (1-2% by weight) may be sufficient to cause the problem. In compositions cont~nnplzlted by the present învention, the amount of mineral filler may be more than an order of magnitude (30-50% by weight) and the loss of gloss problem is unavoidable and very noticeable.
Sanding the surface of these sheets before or after the thermoforming step could provide a solution to the problem of loss of gloss, since the sanded finish does not change, or more exactly, the eye of an observer does not appreciate a visible change of the surface finish among the different areas of the fini~h~rl part. However, the sanding process cuts grooves into the surface, and this allows a st~ining agent to penetrate more easily below the surface. These stains may be resistant to a rinsing liquid, such as a soapy solution or similar clç~n~ing products.
This performance is measured, for example, by the ANSI Z. 124.3 :American National Standard for Plastic Lavatories. In it, st~ining agents are used to create stains which are then cleaned with specific procedures. An overall rating of the stain resict~n~e of the surface is obtained and a rating of 50 is required to pass the test.
When the solid surface sheet is produced against an ay~ uliate matte finish, like a plastic film or paper, the geometry of the surface of the sheet will have the same thin and llniforrn film of plastic matrix, but it is not flat and it has peaks and valleys which provide a matte look. The stain rçsi~t~nce will remain about the same as that of a smooth finish.
Another hll~ol L~ll factor affects the performance of the fini~h~-rl part, and that is the type of mold used. Our work has shown that the stain resistance dccreases after the sheet is formed W O98117713 PCT~US97/06200 into a female mold, while it may increase or stay the same if a male mold is used. In a female mold forrnin~, the finiche~l surface is stretched, and it is reasonable to assume that the pores at its surface will grow larger and/or new ones may be formed, thus favoring the penetration of st~ining agents. In a male mold configuration, the finieh~cl surface is not stretched to any ~:ipnifir~nt degree and it is pressed against the mold surface.
The male type mold is also preferable for achieving a more uniform and thicker wall in the finiehecl part. In a female mold, the thermoformed sheet significantly decrease in thickness in some areas. In an average vanity top bowl, the thickness in the drain area may drop to 1/3 or 1/4 of its original value. If the same shape is produced in a male mold, the thickness in the drain area may be only 10-20% less than the original thickness. Consequently, if the original thickness is high enough, the thermoformed part from a male mold may be strong enough to be used as such, without the need of any type of back side reinforcement, such as polyester-fiberglass.
Detailed Description of the Invention Several types of film were tested. They are listed in Table 1. These films or papers were used to cover a casting s~ ce, so that the liquid composition would contact them and polymerize against them.
Cell casting experiments were performed in which the film or paper covered the surface of one of the two cell cast plates. The space between them was then filled with the liquid composition of choice, which would then be polymeri7~1 in a water bath and/or oven, following the known art methods.
Although the present invention is not limited to any one particular sheet m~n~lf~cturing process (e.g. continuous cast, injection molding, cell cast, end the like), in the ple~.,~d embodiment of the invention the continuous casting process, such as is described in U.S. Patent No. 3,376,371 by Opel et al., and Hellsund's U. S. Patent No. 52,271,383 are followed using an W O 98/17713 PCT~US97/06200 alumina trihydrate filled acrylic composition such as those described in U. S. Patent No.
5,521,243. A roll of the selectecl m~t~n~l was mounted on an air brake support and ~ ekin~
system, to provide some tension to elim;n~te wrinkles. The film would then go over a curved Mt. Hope type roller, also useful to elimin~te wrinkles. The leading edge of the film or paper was taped across the bottom belt, which would then pull the film from the feed roll.
The polymer- 7:ing composition was dropped onto the film which covered the bottom belt.
The film or paper in question could be covering the top belt (or both belts) depending on operational choices and the available equipment configuration.
If the sheet is made from a thermoformable composition, the film or paper can be left on the sheet until the thermoforming operation is initiated. The film may have to be removed if it does restrain or negatively affects the surface ~uality of the finished part.
Examples The types of film used for mineral filled thermoformable acrylic sheets and thermoformed bowls therefrom are given in Table 1. The sheets were prepared as is set forth in U. S. Patent 5,521,243 (in turn referencing '371 and '383 patents). The evaluations ofthe Stain i.ct~n~.e per ANSI Z. 124.3 are given in Table. 2.
W O 9811M13 PCT~US97/06200 TABT F I
Melinex 377: 1 mil thick, a polyethylene terepht ~l~te film sold by ICI Corporation.
M-1000: 2.5 mil, a polyvinyl alcohol film sold by Chris Craft Industrial Products.
~tipkote Papers: 5 mil, paper base with clays and surface treatment coatings sold by S.D.
Warren Company.
Type of Stripkote Tested Results TK-ETL-Velvet ~ood release - good ~pea~ ce SK-ETL-Matte Good release - good a~pe~a~ce , W O98/17713 PCTrUS97/06200 T~iBT,F,2 (Stain R~ t~nc~e ratings per ANSI Z.124.3 - 1986) Flat Surface Thermoforlned Bowl Film orPaper S~n~le ID ~ Sanded Flat Surface ~Q~l Melinex 377 85-2484 52 54 44 61(F) Melinex 377 85-2485 57 54 59 68(F~
Melinex 377 85-6548 48 25(M) M-1000 85-3341 33 34 39(F) 85-4480 39 56 28(M) Stripkote 85-6236 57 TK-ETL
Stripkote Cell cast 39 SK-ETL
Notes:
- S~nfle~l used 60 micron s~n~lr~rer.
- Thermoformed bowl: "bowl" results were obtained in the drain area of the bowl.
- (F) and (M) = F denotes a female mold configuration; M denotes a male mold configuration; both molds produced a part with the same dimensions.
The best stain resistance ratings were obtained with M-1000 film, 33 and 39 for the surface "as WO 98/17713 PCT~US97/06200 is." The same film provided the best results when using a female mold (39). With Melinex 377, the perform~nre of ~e surface "as is" was borderline acceptable (52, 57, 48), and it becarne unacceptable after ~er nofcl,.,illg in a female mold (61). However, ~e use of a male mold significantly irnproved the stain resistance (25).
~IAVING A MATTE FINISH WITH IMPROVED STAIN RESISTANCE
Technical Field This invention relates to the m~mlf~ctllring of slab or sheets of poly (methyl methacrylate~ (PMMA) which contain mineral fillers and which can be thermoformed into such articles as vanity tops or sinks. In particular, this invention describes how to produce sheets or slabs with a matte finish surface and appearance that does not require additional finiching steps and provides good stain recict~n~e7 as measured by ~xi.cting industry standards.
Background of the Invention Sheets and slabs of synthetic mineral appearing m~teri~l are now commonly used as kitchen counter tops and interior and exterior decorative coverings of all kinds for buildings such as banks, air termin~l~, stores, and the like. Such applications frequently require that the material be fabricated to fit custom designed areas.
The fabrication process requires extensive time and specially trained craftsmen to be completed succçssfully, since special tools and procedures are necessary. Until recently, if a shaped, one piece part of continuous monolithic m~t~ri~l is desired, such a part could only be produced by casting it in a closed mold cavity under special conditions.
the silicone forms a release layer.
In Oshima et al., U. S. Patent No. 4,041,120 discloses an abrasion resistant surface layer for synthetic resin articles. However, that layer is firmly adherent to the base resin. Similarly, Toyooka et al., U. S. Patent No. 4,254,074 discloses synthetic resin sheets having a film, possibly bearing printing, ~lh~ring thereto.
CA 022323~8 l998-04-22 W 098/17713 PCTrUS97/OG200 Daff et al., in U. S. Patent No. 5,308,425 discloses a protective film placed on acrylic sheet. However, the present differs in that the film here is non-colnr~tihle with a mineral filled acrylic sheet. The non-compatibility must be to a degree such that the surface characteristics of the mineral filled sheet are not subst~nt~lly ch~n~ç~l Additionally, the r~sllltinf~ sheet will have a matte finish. Neither of these cha~ ;stics are present in Daff et al.
In U.S. Patent No. ~,521,243 ~inghetti et al., disclose the composition of a mineral appearing material which may be cast or otherwise formed into the shape of a sheet. These sheets are capable of being thermoformed into a vanity top or sink. As with prior art mineral appearing sheets, the post-polymerized sheet will have a glossy appearance. However, this glossy appearance becomes matte in areas of deep draw upon thermoforming. Thus, the final product will have a non-uniform appearance.
The same problem is experienced with non-thermoformed acrylic compositions such as those described by Ross et al., in U. S. Patent Nos. 4,961,995 and 5,032,625. In addition to the high costs associated with installation of the acrylic parts (placing the sheets into place, fitting, glueing, and the like) the intersection of adjacent sheets will necessarily be sanded to give a smooth fit. This s~n(1ing process will similarly remove the glossy appearance in that area, giving a non-uniform appearance.
To combat the difficulties listed above, mineral appearing sheets are often sanded in their entirety. This gives a uniform matte finish before and after the above applications are accomplished. However, the uniform ~nrlin~ process has its own distinct drawbacks.
Vi~n~li7in~ the contents of a mineral appearing acrylic sheet, mineral filler particles such as alumina trihydrate (ATH) will be dispersed throughout the acrylic matrix. Some of these particles will be very near the surface of the sheet. These particles near the surface will have a very thin film of acrylic covering them. When the surface of the sheet is subsequently sanded this thin film of acrylic is nnint~ntionally removed. The filler particles near the surface are then W O g8/17713 PCT~US97/062~0 exposed and some of them will have been cut in half (or more-or-less) by the s~n~ling One of the qualities possessed by acrylic sheets is stain reei~t~n~e. The acrylic surface resists absorption of foreign m~tçri~le commonly associated with the above-mentioned uses for mineral appearing products. When the mineral filler material such as ATH is exposed by s~n~ling, staining sllbst~n-.es will more easily penetrate the surface, by being absorbed directly by the ATH or by penetrating at the interf~ce of the ATH particles with the polymer matrix. This results in a poor aesthetic quality in the product.
The present invention overcomes this dra~,vback in the prior art. The mineral appearing sheets and products thermoformed therefrom of the present invention have a matte appearance.
There is no need for subsequent sanding procedures. The mineral filler particles near the surface are, for the most part, not exposed. Most, if not all, retain the acrylic film sepalaLirlg the particles from the outside enviromnent. The products of the present invention also have improved stain resistance when compared to typical matte surfaces in the prior art.
Summary of the Invention Acrylic sheets such as those described in U.S. Patent No. 5,521,243 can be produced with dif~~ l surface fini.eh~s which will change after lhermoforming and the appearance being unacceptable. When the hot sheet is sketched into a mold, there is a significant loss of gloss, which is variable and proportional to amount of stretching of any given unit of surface. If, for example, a bathroom vanity top is thermoformed fTom a sheet with a smooth finish, the resulting part will show:
- a minor change in gloss (slight decrease) in the flat area surround the bowl area, - a more noticeable change of gloss (moderate decrease) in the rim area around the bowl, W O98/17713 PCTnUS97/06200 - a very noticeable change of gloss (~ign;ffc~nt decrease to a dull finish) in the bottom or drain area of the bowl.
All this occurs because the polymer matrix stretches out and away from the solid particles of the mineral filler. This is a well known l~h~;nomc~on in the thermoforming of high gloss sheets where, at times, a small amount of pigm~ntc or solid powders (1-2% by weight) may be sufficient to cause the problem. In compositions cont~nnplzlted by the present învention, the amount of mineral filler may be more than an order of magnitude (30-50% by weight) and the loss of gloss problem is unavoidable and very noticeable.
Sanding the surface of these sheets before or after the thermoforming step could provide a solution to the problem of loss of gloss, since the sanded finish does not change, or more exactly, the eye of an observer does not appreciate a visible change of the surface finish among the different areas of the fini~h~rl part. However, the sanding process cuts grooves into the surface, and this allows a st~ining agent to penetrate more easily below the surface. These stains may be resistant to a rinsing liquid, such as a soapy solution or similar clç~n~ing products.
This performance is measured, for example, by the ANSI Z. 124.3 :American National Standard for Plastic Lavatories. In it, st~ining agents are used to create stains which are then cleaned with specific procedures. An overall rating of the stain resict~n~e of the surface is obtained and a rating of 50 is required to pass the test.
When the solid surface sheet is produced against an ay~ uliate matte finish, like a plastic film or paper, the geometry of the surface of the sheet will have the same thin and llniforrn film of plastic matrix, but it is not flat and it has peaks and valleys which provide a matte look. The stain rçsi~t~nce will remain about the same as that of a smooth finish.
Another hll~ol L~ll factor affects the performance of the fini~h~-rl part, and that is the type of mold used. Our work has shown that the stain resistance dccreases after the sheet is formed W O98117713 PCT~US97/06200 into a female mold, while it may increase or stay the same if a male mold is used. In a female mold forrnin~, the finiche~l surface is stretched, and it is reasonable to assume that the pores at its surface will grow larger and/or new ones may be formed, thus favoring the penetration of st~ining agents. In a male mold configuration, the finieh~cl surface is not stretched to any ~:ipnifir~nt degree and it is pressed against the mold surface.
The male type mold is also preferable for achieving a more uniform and thicker wall in the finiehecl part. In a female mold, the thermoformed sheet significantly decrease in thickness in some areas. In an average vanity top bowl, the thickness in the drain area may drop to 1/3 or 1/4 of its original value. If the same shape is produced in a male mold, the thickness in the drain area may be only 10-20% less than the original thickness. Consequently, if the original thickness is high enough, the thermoformed part from a male mold may be strong enough to be used as such, without the need of any type of back side reinforcement, such as polyester-fiberglass.
Detailed Description of the Invention Several types of film were tested. They are listed in Table 1. These films or papers were used to cover a casting s~ ce, so that the liquid composition would contact them and polymerize against them.
Cell casting experiments were performed in which the film or paper covered the surface of one of the two cell cast plates. The space between them was then filled with the liquid composition of choice, which would then be polymeri7~1 in a water bath and/or oven, following the known art methods.
Although the present invention is not limited to any one particular sheet m~n~lf~cturing process (e.g. continuous cast, injection molding, cell cast, end the like), in the ple~.,~d embodiment of the invention the continuous casting process, such as is described in U.S. Patent No. 3,376,371 by Opel et al., and Hellsund's U. S. Patent No. 52,271,383 are followed using an W O 98/17713 PCT~US97/06200 alumina trihydrate filled acrylic composition such as those described in U. S. Patent No.
5,521,243. A roll of the selectecl m~t~n~l was mounted on an air brake support and ~ ekin~
system, to provide some tension to elim;n~te wrinkles. The film would then go over a curved Mt. Hope type roller, also useful to elimin~te wrinkles. The leading edge of the film or paper was taped across the bottom belt, which would then pull the film from the feed roll.
The polymer- 7:ing composition was dropped onto the film which covered the bottom belt.
The film or paper in question could be covering the top belt (or both belts) depending on operational choices and the available equipment configuration.
If the sheet is made from a thermoformable composition, the film or paper can be left on the sheet until the thermoforming operation is initiated. The film may have to be removed if it does restrain or negatively affects the surface ~uality of the finished part.
Examples The types of film used for mineral filled thermoformable acrylic sheets and thermoformed bowls therefrom are given in Table 1. The sheets were prepared as is set forth in U. S. Patent 5,521,243 (in turn referencing '371 and '383 patents). The evaluations ofthe Stain i.ct~n~.e per ANSI Z. 124.3 are given in Table. 2.
W O 9811M13 PCT~US97/06200 TABT F I
Melinex 377: 1 mil thick, a polyethylene terepht ~l~te film sold by ICI Corporation.
M-1000: 2.5 mil, a polyvinyl alcohol film sold by Chris Craft Industrial Products.
~tipkote Papers: 5 mil, paper base with clays and surface treatment coatings sold by S.D.
Warren Company.
Type of Stripkote Tested Results TK-ETL-Velvet ~ood release - good ~pea~ ce SK-ETL-Matte Good release - good a~pe~a~ce , W O98/17713 PCTrUS97/06200 T~iBT,F,2 (Stain R~ t~nc~e ratings per ANSI Z.124.3 - 1986) Flat Surface Thermoforlned Bowl Film orPaper S~n~le ID ~ Sanded Flat Surface ~Q~l Melinex 377 85-2484 52 54 44 61(F) Melinex 377 85-2485 57 54 59 68(F~
Melinex 377 85-6548 48 25(M) M-1000 85-3341 33 34 39(F) 85-4480 39 56 28(M) Stripkote 85-6236 57 TK-ETL
Stripkote Cell cast 39 SK-ETL
Notes:
- S~nfle~l used 60 micron s~n~lr~rer.
- Thermoformed bowl: "bowl" results were obtained in the drain area of the bowl.
- (F) and (M) = F denotes a female mold configuration; M denotes a male mold configuration; both molds produced a part with the same dimensions.
The best stain resistance ratings were obtained with M-1000 film, 33 and 39 for the surface "as WO 98/17713 PCT~US97/06200 is." The same film provided the best results when using a female mold (39). With Melinex 377, the perform~nre of ~e surface "as is" was borderline acceptable (52, 57, 48), and it becarne unacceptable after ~er nofcl,.,illg in a female mold (61). However, ~e use of a male mold significantly irnproved the stain resistance (25).
Claims (6)
1. A process for making a mineral filled acrylic sheet having a matte finish comprising the steps of:
(a) making a prepolymerized syrup comprising methyl methacrylate and having mineral particles dispersed therein;
(b) polymerizing said syrup between at least two surfaces, said surfaces defining a space in the shape of a sheet, and wherein at least one of said surfaces is contacted by a film, said film being non-compatible with said syrup, and said film having a plurality of pores causing said sheet to have a matte finish after said syrup is polymerized, and wherein said film is removable from said sheet, wherein said removal does not cause significant exposure of said mineral particles to an outside environment; and (c) removing said polymerized syrup from said surfaces.
(a) making a prepolymerized syrup comprising methyl methacrylate and having mineral particles dispersed therein;
(b) polymerizing said syrup between at least two surfaces, said surfaces defining a space in the shape of a sheet, and wherein at least one of said surfaces is contacted by a film, said film being non-compatible with said syrup, and said film having a plurality of pores causing said sheet to have a matte finish after said syrup is polymerized, and wherein said film is removable from said sheet, wherein said removal does not cause significant exposure of said mineral particles to an outside environment; and (c) removing said polymerized syrup from said surfaces.
2. A method according to claim 1 wherein said film comprises a polyvinyl alcoholfilm.
3. A method according to claim 1 wherein said film comprises a polyethylene terephtalate film.
4. A mineral appearing acrylic sheet having a matte appearance made by the method of claim 1.
5. A mineral appearing acrylic sheet according to claim 4 wherein said prepolymerized syrup comprises a thermoformable composition.
6. A thermoformed article made by thermoforming the sheet of claim 4.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US73431796A | 1996-10-21 | 1996-10-21 | |
| US08/734,317 | 1996-10-21 | ||
| PCT/US1997/006200 WO1998017713A1 (en) | 1996-10-21 | 1997-04-14 | Process for making a mineral filled acrylic sheet having a matte finish with improved stain resistance |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2232358A1 true CA2232358A1 (en) | 1998-04-30 |
Family
ID=24951178
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002232358A Abandoned CA2232358A1 (en) | 1996-10-21 | 1997-04-14 | Process for making a mineral filled acrylic sheet having a matte finish with improved stain resistance |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JP2000502403A (en) |
| CA (1) | CA2232358A1 (en) |
| WO (1) | WO1998017713A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8858850B2 (en) * | 2009-07-02 | 2014-10-14 | E I Du Pont De Nemours And Company | Process for preparing decorative surface appearance in acrylic material employing anisotropic particles |
| EP4271549A1 (en) * | 2020-12-30 | 2023-11-08 | Trinseo Europe GmbH | Methods for producing highly thermoformable acrylic solid surface |
| WO2023034893A1 (en) * | 2021-09-01 | 2023-03-09 | Trinseo Europe Gmbh | Articles of manufacture produced from highly thermoformable acrylic solid surface with matte surface |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB998802A (en) * | 1961-01-13 | 1965-07-21 | British Cellophane Ltd | Improvements in or relating to moulding resin sheets |
| US3371383A (en) * | 1965-09-28 | 1968-03-05 | Swedlow Inc | Continuous casting apparatus |
| US3376371A (en) * | 1965-09-28 | 1968-04-02 | Swedlow Inc | Continuous casting process |
| US4584231A (en) * | 1983-12-02 | 1986-04-22 | Vcf Packaging Films, Inc. | Solvent cast acrylic film |
| JPH04364907A (en) * | 1991-06-12 | 1992-12-17 | Kurisuron:Kk | Manufacture of artificial marble or the like |
| JP2807149B2 (en) * | 1993-08-13 | 1998-10-08 | 帝人株式会社 | Release film |
| US5521243A (en) * | 1993-11-26 | 1996-05-28 | Aristech Chemical Corporation | Acrylic sheet having uniform distribution of coloring and mineral filler before and after thermoforming |
-
1997
- 1997-04-14 JP JP10519323A patent/JP2000502403A/en active Pending
- 1997-04-14 WO PCT/US1997/006200 patent/WO1998017713A1/en active Application Filing
- 1997-04-14 CA CA002232358A patent/CA2232358A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| WO1998017713A1 (en) | 1998-04-30 |
| JP2000502403A (en) | 2000-02-29 |
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