Note: Descriptions are shown in the official language in which they were submitted.
BACXGROUND OF THE INVENTION
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The present invention relates to cured resin products formed
by lamination techniques. In one aspect of the invention a
chemically resistant laminate is formed by consolidating discrete
layers of materials under heat and pressure. Another aspect of
the invention concerns the method and order of laying-up pre-
determined discrete layers for subsequent lamination.
DESCRIPTION OF THE PRIOR ART
Countertops for all types of laboratories, beauty shops,
pharmacies, and other commercial applications must be stain and
chemical resistant in addition to being wear and impact resistant.
Typically such countertops are constructed of slate, marble,
composition stone, or black or gray colored wood surfaces covered
with a varnish. Of course, the slate and marble are heavy,
difficult to install, and expensive. The painted w03d counters
are readily scra~ched or abraded and require frequent maintenance.,
Surfaces coated with a cured polyester resin have exceptional
chemical resistance properties, and are also wear resistant.
However, unless such surfaces are bonded to a high density SUD-
strate or the like, they will lack impact strength and are not
as durable. Melamine/formaldehyde resin laminates provide a
good wear and impact resistant surface which can also be decora-
tive but lack the ability to resist chemical attack.
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An attempt to overcome this problem is shown in U.S. Patent
3,756,901 wherein a fiberglass sheet and a heavy kraft paper are
impregnated with polyester resins to produce a low pressure
laminate. The kraft paper must have a basic weight of greater
than l40 pounds to produce a laminate having adequate impact
resistance.
U.S. Patent 3,929,545 to E.J. Van Dyck et al discloses a
similar low pressure polyester laminate, but this product is
generally suitable for vertical applications where impact and
wear resistance are not factors.
U.S. Patent 3,551,241 discloses a lay-up comprising core-
stock impregnated with phenolic resin, a decorative sheet impreg-
nated with melamine/formaldehyde resin, and a top release sheet
coated with polyester resin. The lay-up is consolidated under
high temperature and pressure conditions. Of course, the final
product is a strong rigid laminate but lacks wear resistance and
suffers delamination defects because of the immiscibility and
resultant lack of good bond between a polyester resin and a
melamine/formaldehyde resin.
SUMMARY OF THE INVENTION
The present invention provides a laminated product and
method therefor which can offer decorati~e patterns and/or
color choices in combination with exceptional chemical and stain
resistance. The product is a high pressure laminate wherein the
desirable properties of transparency, chemical resistance and
wear resistance produced with a polyester resin surface layer
are synergistically combined with the desirable strengthening
features of melamine and phenolic resin impregnated substrate
layers. The immiscibility and delamination defects common in
prior art laminations are overcome with the use of an interme-
diate dry sheet between the polyester resin layers and the
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melamine (melamine/formaldehyde)and/or phenolic resin impregnated
substrate layers. During lamination, each of the respective
resins on opposite sides of the dry sheet penetrate therein a
certain distance. In this manner, the immiscible resins are
integrally bound together with the dry sheet to form a unitary
final product having the combined desirable features of both
resin systems. Alternatively, it is envisaged that a partially
impregnated decorative sheet having a dry surface in contast
with the melamine and/or phenolic resin impregnated substrate
layers would a]so function to bond the immiscible resin layers
together.
Thus, in accordance with the present teachings, a
process is provided for producing a decorative laminate which
comprises applying a polyester resin to a decorative sheet and
curing the resin. An assembly is prepared of superimposed sheets
by placing the decorative sheet upon a dry sheet and placing
beneath the dry sheet a plurality of -thermosetting resin im-
pregnated sheets and consolidating the assembly under heat and
pressure to a unitary laminated structure.
DESCRIPTION OF PREFERRED EMBODIMENTS
In accordance with the present invention, it will
be seen that unique procedures are utilized to produce high
pressure laminates having properties that were hitherto un-
ayailable in a single product. In a first -technique, a release
sheet that has been coated with a "B" staged polyester resin is
placed upon a polyester impregnated decorative sheet. The
decorative sheet is placed upon a dry sheet: For example, a
sheet of paper which has not been subjected to a treating or
coating procedure. This assembly is then consolidated under
heat and pressure with various types of thermosetting resin
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impregnated substrate sheets. At the conclusion of the
consolidation step, the release sheet is removed.
To describe the procedure in more detail, the first
technique calls for the use of a flexible release sheet upon
which is applied a polyester resin film. The release sheet
may be anyone of a plurality of commonly used materials such
as cellophane, polyester film, aluminum foil, or foil-paper
laminates Additionally, papers which have been coated or
treated with polyethylene, polypropylene, polyfluorocarbon
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material~, silicone, or other release materials may be utilized
to enhance the release of the film from the sheet. It will also
be appreciated that the release sheet may be textured so that it
can impart an embossed surface finish to the surface of the
finished laminate.
The polyester resin used for coating the release sheet consists
of about 100% reactive solids. Particular polyester resin
mixtures may be found in U.S. Patent 3,756,901.
Apparatus suitable for use in curing
the resin to a semisolid "B" stage may be found in U.S. Patent
3,929,545 Generally,
the resin contains about 65% polyester resin and 35% styrene
monomer. These components are mixed with photoinitiators or ~.V.
light sensitizers and peroxide and are applied to the release
sheet by conventional reverse roll coating apparatus. The film
thickness is generally controlled between about 5 and 20 mils.
The coated sheet is passed through an ultraviolet light processor
wherein U.V. light operates to cure the resin to a semisolid state.
The speed of the coated sheet through the processor and the number
of U.V. lamps and distance from the sheet are important variables
in achieving the semi-cured non-mobil~film referred to as a "B"
stage cure. As the coated release sheet exits the processor, the
partially cured film is interleafed with a polyethylene film for
temporary storage prior to its use in the aforementioned lay-up.
The decorative sheet used with the present invention is
saturated to contain from 40-63% resin solids and preferably
between about 48 and 52%. To achieve this, a polyester resin
mixture is prepared containing about 85-35% resin and 5-15~
vinyl monomer. To this mixture is added catalysts, inhibitors,
and silica materials to control the melt viscosity and flow
characteristics oE the fluid. A viscosity between 150 and 500
centipoise is produced by adding a solvent such as acetone
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and/or methyl ethyl ketone.
The decorative sheet is fed into a vat containing the solvent
resin system, and the amount of resin applied to the sheet is
controlled by feeding the wetted sheet through metering rolls.
The impregnated sheet is dried in a heated oven to remove a
substantial portion of the volatile solvents. Generally, the
dried sheet should not contain more than between 4 and 6%
volatiles. As the sheet exits from the drying oven~ it is
cooled and interleafed with a plastic film and wound on a
continuous roll for temporary storage until further processing
into a final laminated product.
A final laminate assembly is prepared by arranging in a
stacked relationship a plurality of substrate materials which
have been impregnated with a thermosetting resin. Over the sub-
strate is placed an overlay that has been impregnated with a
thermosetting resin such as melamine. This overlay may be in
fact a barrier sheet depending upon the color and/or type o~
sheet being utilized.
Above the barrier and/or melamine treated overlay is a
dry sheet, and immediately above the dry sheet is the polyester
impregnated decorative sheet. The coated release sheet is
placed upon the impregnated decorative sheet with the "B"
staged polyester coating in direct contact with the decorative
sheet. The entire assembly is placed into a conventional
laminating press and is heat and pressure consolidated to a
final unitary laminated structure. The pressure is generally
from 800-1200 PSI with a temperature range of about 225-325~.
The overall thickness of the final laminate product produced
by the above-described technique can be controlled by the number
of layers of substrates used.
A second techni~ue for producing the chemically resistant
high pressure laminate of the present invention involves the
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direct coating o~ dry decorative paper with a thermosetting
polyester resin. The coated resin is "B" staged to a semisolid
state and subsequently bon~ed to various substrate materials as
described in the first technique. This method has the advantage
of combining the steps of resin coating the release sheet and
"B" staging of the release sheet as well as the impregnation and
drying operation used to produce the previously described
impregnated decorative sheet.
In particular, the second technique involves the reverse
roll coating of a decorative sheet with a heat curable polyester
resin of the type used for coating the release sheet. In this
instance, however, the coating thickness is increased to about
11-30 mils. The coating is cured through the U.V. processor in
the same manner as that described with the release sheet. Upon
exiting the processor, the partially cured polyester film is
interleafed with a plastic sheet and wound into rolls for
temporary storage, or it can be immediately cut into sheets for
use in the lay-up of a final laminate.
It will be appreciated that upon application of the
polyester film to the surface of the decorative sheet7 a
portion of the resin will penetrate the sur-face of ~he sheet.
Generally, the preferred resin content is between 75 and
85% of the total weight of the sheet with a volatile content
of between 2 and 6%. A laminate assembly based upon the
second technique is prepared by placing, in a stacked rela-
tionship, a plurality of resin treated substrate materials
above which is placed a resin treated barrier or overlay
sheet. Over the barrier sheet is placed a dry intermediate
sheet and the polyester coated and impregnated sheet is
placed upon this. The entire assembly is consolidated as
previously described in a conventional high pressure lamina-
ting press.
To achie~e a more complete understanding of the present
invention, the following examples are set forth. It will be
appreciated, however, that these examples are primari-ly for
the purpose of illumination and/or illustration and specific
details contained therein should not be interpreted as a
limitation on the invention~
EXAMPLE 1
An isophthalic polyester resin is prepared containing
88.7~ Ashland Chemical Company's 7200 polyester resin and
11.3% vinyl monomer (diallyl phthalate). To this is added:
1% t-butyl perbenzoate, 1% benzoyl peroxide, 250 PPM (.025%)
BHT inhibitor, and 3.77% Cab-O-Sil M5 (Cabot Corporation)
fumed silica. These ingredients are added to a solvent blend
of acetone and methyl ethyl ketone in a proportion resulting
in a final viscosity between 150-500 centipoise.
A decorative alpha cellulose sheet is fed under tension
into a vat containing the above-described resin and passed
between metering rolls which control the resin content in the
paper. The saturated sheet is then force air dried in a
steam heated oven containing graduated temperature ~ones.
The amount of rolatiles in the exiting sheet is controlled
between 4 and 6%, whereas the resin solids as a portion of
the to~al impregnated sheet is controlled between 48 and 52%.
The exiting sheet is cooled and interleafed with polyethylene
film and wound into a continuous roll.
An aluminum foil release sheet is coated with a polyester
resin consisting of Ashland Chemical Company's 7200 resin in
styrene ~65% alkyd., 35% styrene). To these reactive solids
are added 1% photoinitiator, Triganol 14 (Noury Chemical
Compa~y), 0.75% t-butyl perbenzoate, 800 PPM (.08%) Pluronic
L122 surfactant (BASF Wyandotte Corporation) and 500 PPM
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C.05%) BHT inhibitor. The aluminum foil release sheet is
passed over a reverse direction roll coater. A layer of the
above-described polyester resin controlled at a film thick-
ness of about 12-14 mils ;s applied. The coated release
sheet is then passed through a U.V. processor in which
ultraviolet light is emitted from 200 watts per inch mercury
vapor lamps operating at 1500 volts and 7.5 amps. The line
speed is about 8 feet per minute per lamp with the lamps
about 6 inches above the film. Upon exiting the U.V. processor,
the "B" staged cured polyester film is interleafed with a
polyethylene film and wound into a roll for storage.
Predetermined lengths of the coated release sheet and
decorative laminate are layed-up with resin impregnated substrate
sheets in a conventional laminating press and consolidated
between 800-1200 PSI and 270-312F for about 35 minutes.
The laminate is cooled for about 25 minutes and removed from
the press.
The following order of lay-up produced a unitary laminate
structure which exhibited physical properties in excess of
comparable NEMA standard values with a chemical and stain
resistance which far exceeded conventional melamine-formaldehyde
high pressure laminates:
Polyester coated and U.V. "si~ staged release sheet
Polyester Pre-Preg 50% resin content
Dry overlay
~elamine treated barrier 40-50~ resin content
ll-Phenolic treated kraft paper 35-38~ resin 122# basis wt.
Melamine treated overlay - 70% resin content
EXAMPLE 2
Example 1 is repeated except that the lay-up is:
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Polyester coated and U.V. "B" staged release sheet
Polyester Pre-Preg 50% resin content
Dry overlay
Melamine treated overlay - 70~ resin content
ll-Phenolic treated kraft paper 34-38% resin content 122# basis wt
Melamine treated overlay - 70% resin content
EXAMPLE 3
Example 1 is repeated except that the lay-up is:
Polyester coated and U.V. "B" staged release sheet
Polyester Pre-Preg 50% resin content
Polyester barrier sheet 40-50% resin content
Dry overlay
Melamine treated overlay - 70% resin content
ll-Phenolic treated kraft paper 34-38% resin 122~ basic wt,
Melamine treated overlay - 70~ resin content
EXAMPLE 4
Example 1 is repeated except that the lay-up is:
Polyester coated and U.V. "B" staged release sheet
Polyester Pre-Preg 50% resin content
Dryibarrier
Me~amine treated overlay - 70% resin content
ll-Phenolic treated kraft paper 34-38~ resin 122# basic wt.
Melamine treated overlay - 70% resin content
EXAMPLE 5
- Example 1 is repeated except that the lay-up is:
Polyester coated and U.V~ "B" staged release sheet
Polyester Pre-Preg 50% resin content
Dry overlay
Melamine treated barrier 40-50% resin content
3-Phenolic treated kraft paper 40% resin content 132# basis wt.
Dxy crepe
Dry overlay
EXAMPLE 6
Example 1 is repeated except that the lay-up is:
Polyester coated and U.V. "B" staged release sheet
Polyester Pre-Preg 50% resin content
Dry overlay
Melamine treated overlay - 70% resin content
3-Phenolic treated kraft paper 40% resin content 132# basis wt.
Dry crepe
Dry overlay
EXAMPLE 7
Example 1 is repeated except that the lay-up is:
Polyester coated and U.V. "B" staged release sheet
Polyester Pre-Preg 50% resin content
Polyester barrier sheet 40-50% resin content
Dry overlay
Melamine treated overlay - 70% resin content
3-Phenolic treated kraft paper 40~ resin content 132# basis wt.
Dry crepe
Dry overlay
EXAMPLE B
Example 1 is repeated except that the lay-up is:
Polyester coated and U.V. "B" staged release sheet
Polyester Pre-Preg 50% resin content
Dry barrier
Melamine treated overlay 70% resin content
3-Phenolic treated kraft paper 40% resin content 132# basis wt.
Dry crepe
Dry overlay
EXAMPLE 9
An example of a laminate produced by the second technique
is as follows:
An isophthalic polyester resin solution having a viscosity
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between 1000 and 2000 centipoise is prepared consisting of
Ashland Chemical Company's 7220 resin, 1% triganol 14 ~NOUTY
Chemical Company), 0.75~ t-butyl perbenzoate, 800 PPM (.08~)
pluronic surfactant tBASF Wyandotte Corporation) and 500 PPM
(.05%) BHT inhibitor. A decorative alpha cellulose sheet is
passed over a reverse direction roll coater containing the
above-described resin and wherein a film thickness of
approximately 17-20 mils is applied. The speed of the coater
is controlled so that a small amount of saturation of the resin
in the sheet takes place during the time the sheet travels the
distance between the roll coater and curing source. "B" stage
curing is accomplished with the U.V. processoT described in
Example 1.
The "B" staged decorative sheet may be interleafed with a
polyethylene sheet and rolled for storage or it may be immediately
cut into predetermined lengths and processed into a decorative
laminate.
The procedure is to form an assembly by superimposing ~he
polyester resin impregnated decorative sheet with resin impreg-
nated substrate materials as follows:
W coated pattern paper 75-85% resin content
DTY overlay
Melamine treated barrier 40 50~ resin content
ll-Phenolic treated kraft paper 34-38~ resin content 122#
basis wt.
Melamine treated overlay - 70% resin content
The above lay-up is consolidated into a unitary structure
as described in Example 1. The laminate structure exhibited
physical properties in excess of comparable NEMA standard
values with a chemical and stain resistance which far exceeded
conventional melamine-formaldehyde high pTessure laminates.
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EXAMPLE 10
The technique of Example 9 is repeated except that the
lay-up is:
UV coated pattern paper 75-85% resin content
Polyester barrier sheet 40-50~ resin content
Dry overlay
Melamine treated barrier 40-50% resin content
ll-Phenolic treated kraft paper 34-38% resin content 122# basis
wt.
Melamine treated overlay - 70% resin content
EXAMPLE 11
The techni~ue of Example 9 is repeated except that the
lay-up is:
W coated pattern paper 75-85% resin content
Dry overlay
Melamine treated overlay - 70% resin content
ll-Phenolic treated kraft paper 34-38% resin content 122# basis
wt,
Melamine treated overlay - 70% resin content
EXAMPLE 12
The technique of Example 9 is repeated except that the
lay-up is:
W coated pattern paper 75-85% resin content
Polyester barrier sheet 40-50% resin content
Dry overlay
Melamine treated overlay - 70% resin content
ll-Phenolic treated kraft paper 34-38% resin content 122# basis
wt.
Melamine treated overlay - 70% resin content
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~XAMPLE 13
The technique of Example 9 is repeated except that the
lay-up is:
W coated pattern paper 75-85% resin content
Dry overlay
Melamine treated barrier 40-50% resin con-tent
3-Phenolic treated kraft paper 40% resin content 132# basis wt.
Dry crepe
Dry overlay
EXAMPLE 14
The technique of Example 9 is repeated except that the
lay-up is:
UV coated pattern paper 75-85% resin content
Polyester barrier sheet 40-50% resin content
Dry overlay
Melamine treated barrier 40-50% resin content
3-Phenolic treated kraft paper 40% resin content 132# basis wt.
Dry crepe
Dry overlay
EXAMPLE 15
The technique of Example 9 is repeated except that the
lay-up is:
UV coated pattern paper 75-85~ resin content
Dry overlay
Melamine treated overlay 70% resin content
3-Phenolic treated kraft paper 40% resin content 132# basis wt.
Dry crepe
Dry overlay
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EXAMPLE 16
The technique of Example 9 is repeated excep~ that the
lay-up is.
UV coated pattern paper 75-85~ resin content
Polyester barrier 40-50% resin content
Dry overlay
Melamine treated overlay 70% resin content
3-Phenolic treated krat paper 40% resin content 132# basis wt.
Dry crepe
Dry overlay
A third technique for producing the laminate of the-present
invention concerns the use of a decorative sheet partially
impregnated with polyester resin. The decorative sheet will be
coated on its face side with the polyester resin.
Impregnation will occur with resin penetration into the
sheet a distance less than its full thickness. The sheet will
be layed-up with its back dry side in contact with melamine-
formaldehyde resin impregnated overlay or barrier sheet layers.
During lamination the melamine-formaldehyde resin will migrate
into the dry portion of the decorative sheet thereby forming
a bond with the polyester impregnated portion of the decorative
sheet.
It will be understood that the polyester resin formulations
may be the same as those set forth in Examples l and 9 above.
It is desirable, however, to adjust the viscosity of the
polyester resin to a level above 300 centipoise to inhibit the
complete saturation of the decorative sheet. Preferred viscosity
range adjustments of 300-3000 centipoise are readily affected
by the amount o~ solvents and/or thixotropic agents utilized.
It will also be appreciated that impregnation of the
decorative paper is affected by the basis weight, thickness,
surface finish porosity and/or saturation characteristics
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Lnereof. Additional factors are the speed through the curing
o~en or U.V. processor whereby the slower the speed, the more
time the resin will have to penetrate the paper fibrous
structure. Of course, the melamine-formaldehyde impregnated
sheet will have sufficient resin to flow into the dry portion
of the decorative sheet. A 35-55% resin content range will
usually be sufficient.
EXAMPLE 17
An example of a laminate produced by the third technique
is as follows:
An isophthalic polyester resin is prepared containing
88.7~ Ashland Chemical Company's 7200 polyester resin and
11.3~ vinyl monomer (diallyl phthalate). To this is added:
1~ t-butyl perbenzoate, 1% benzoyl peroxide, 250 PPM (.025%)
BHT inhibitor, and 4.8% Cab-O-~il M5 (Cabot Corporation)
fumed silica. These ingredients are added to a solvent blend
of ~cetone and methyl ethyl ketone in a proportion resulting
in a final viscosity about 1500 centipoises.
A 90~ basis weight decorative alpha cellulose sheet is
coated on its decorative face side with a reverse direction
roll coater containing the above-described resin. The film
applied is then dried in an oven having graduated temperature
zones as described in Example 1. The exiting shee~ has a
resin content between 30% and 60% with volatiles held to less
th~n 5%.
Predetermined lengths of the partially saturated
decorative sheet are layed-up and consolidated with the polyester
coated and U.V. "B" staged release sheet (as set forth in
~xample 1) as folLows:
Polyester coated and U.V. "B" staged release sheet
Polyester Pre-Preg decorative sheet, 37% resin content
Melamine-formaldehyde treated barrier sheet 55% resin content
'~3
ll-Phenolic treated kraft paper sheets 35-40~ resin content
122# basis wt.
EXAMPLE 18
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The procedure of Example 17 was followed with a lay-up
as ~ollows:
Polyester coated and U.V. "B" staged release sheet
Polyester Pre-Preg decorative sheet 42% resin
Melamine-formaldehyde overlay 50~ resin
7-Phenolic treated kraft paper sheets 34-38% resin
Melamine-formaldehyde overlay - 65% resin
EXAM~LE 19
The procedure of Example 17 was followed with a lay-up
as follows:
Polyester coated and U.V. "B" staged release sheet
Polyester Pre-Preg decorative sheet 46% resin
Melamine-formaldehyde overlay 48% resin
9-Phenolic treated kraft paper sheets 35% resin
Dry crepe
Dry o~erlay
EXAMPLE 20
An isophthalic polyester resin solution having a viscosity
between 1000 and 2000 centipoise is prepared consisting of
Ashland Chemical Company's 7220 resin, 1% triganol 14 (Noury
Chemical Company), 0~75% t-butyl perbenzoate, 800 PPM (.08%
pluronic surfactant (BASF Wyandotte Corporation) and 500 PPM
(.05%3 BHT inhibitor.
A 65 lb. basis weight decorative alpha cellulose sheet is
coated on its face surface with the above-described resin
solution to a thickness of about 15-20 mils. "B" stage curing
is ~ccamplished with the U.V. processor described in Example 1.
Predetermined lengths o~ the coated decorative sheet are layed-
up in the following order and consolidated as described in
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Example 1:
Polyester decorative sheet that has been coated with 15-20 mils
of U.V. "B" staged polyester resin.
Melamine-formaldehyde treated overlay - 55% resin content
S-Phenolic treated kraft paper, 42% resin 132# basis wt.
Dry crepe
Dry overlay
EXAMPLE 21
Example 20 is repeated with the following lay-up:
Polyester decorative sheet that has been coated as in Example 20
Melamine-formaldehyde overlay - 50% resin
ll-Phenolic treated kraft paper - 40% resin 122# basis wt.
EXAMPLE 22
Example 20 is repeated with the following lay-up:
Polyester decorative sheet that has been coated as in Example 20
Melamine-formaldehyde barrier sheet 48% resin
3-Phenolic treated kraft paper - 44% resin 132~ basis wt.
Melamine-formaldehyde overlay - 70% resin
Laminates prepared as described in the examples above
had physical properties above NEMA standard values and
displayed stain and chemical resistance in excess of
conventional melamine-formaldehyde high pressure laminates.
