Note: Descriptions are shown in the official language in which they were submitted.
s);~
TITLE
HEAT AND PRESSURE CONSOLIDATED LAMINATE
The present invention relates to a heat and
pressure consolidated decorative laminate having a plurality
of core sheets impregnated with a polyester resin.
Heat and pressure consolidated decorative laminates
are generally produced utilizing a core material comprising a
plurality of phenolic resin impregnated kraft paper sheets, a
face sheet impregnated with a melamine-formaldehyde resin and
optionally a melamine resin impregnated overlay sheet. These
high pressure laminates, examples of which are described in
the Grosheim et al U.S. Patent No. 3,418,189, the Casey et al
U.S. Patent No. 4,311,748, and the Jaisle et al U.S. Patent
No. 4,473,613, have found world-wide acceptance as
construction materials, i.e., wall panels, countertops, etc.
in the home and office. They can be prepared so as to
function in a variet~ of service applications and can be
produced with surfaces such as high gloss, a matte finish or
an embossed finish.
Recently, decorative laminates having melamine-
formaldehyde impregnated core sheets have been proposed in
order that the core has a color matching that of the face or
decor sheet such that the dark edge line that is perceptible
when conventional laminates are cut or worked is eliminated.
However, it has been found that this achievement of color
match of the core and decor sheet is achieved at the expense
of flexibility. In this respect, U.S. Patent No. 4,448,849
3d to Keeling et a~ shows the use of a melamine-formaldehyde
resin cor.taining a hydroxylmelamine for impregnating core
sheets and/or the decor sheet and/or the overlay sheet to
provide a laminate with a solid color edge matching that of
the core surface, the laminate being post-formable but not as
flexible as desired.
,
.
-:., : .
. :
0~7
It is an ob ject of the present inven-tion to
provide a heat and pressllre consoli~lated decorative
laminate that has increased f lexibility and a core color
that matches the desor ~heet.
~i It is another objeçt of the present .invention to
provide a more flexible high pre~:sure decorative laminate
compri~:ing a thermoset~ing melamine/formaldehyde reaction
product impregnated face sheet and a çore made from a
plurality of core sheets impregnated with an unsatllrated
polyester having an acid numher no greater than abQIlt ~0
for providing flexibility to the consolidated laminate as
well as enahling the core to possess a çlose colçr match
for the face sheet and/or the back sheet of the laminate.
According to c: ne apect of the present
invention, there is provided a high pressure decorative
1 amina t e compr i s ing ( a ~ a thermosett ing
melamine/formaldehyde reaction product impregnated face
sheet, ( b ~ one or more core sheets impregnated wi th a
çore sheet treating çomposition comprislng an unsaturated
polyester hav.lng an acid number no greater than about ~0
for providing flexibility to the consolida-ted laminate,
and ( c ~ an optional melamine/formaldehyde reaction
produ.ct impregnated back sheet; the face sheet (a~, the
çore sheets (b~ and the optional baçk sheet (ç~ be.ing
çonsolidated by heat and pressure to provide a laminate
having improved flexibility as well as being resistant to
chipping, being easily fabriçated and having a ccllor in
the çore sheets that çlosely matçhes that of the face and
back shee t s .
Another aspect of the invention provides a hiçh
pressure decorative laminate comprising: (a~ a polyester
resin impregnated face sheet, (b) a plurality of core
shee ts impregnated with a composition comprising an
unsaturated polyester having an acid number no greater
than al~out ~0 for providing flexibility to the
consolidated laminate, and a solvent :eor the polye~:ter,
~nd ~ c ~ an optional melamine/formaldehyde reactîon
~roduct or pol~rester impregnated back sheet; the face
0'~7
~ 2a -
sheet (a), the core sheet.s (h) and the optional baçk sheet
(c) belng çonsoliclated by exerting thereon a pres.sure in
the range of from abou-t ~00 to 1400 psi at temperatures
from about 240~ to about ~5Q~F to provide a laminate
having improved flexibility as well as being resis-tant to
çhipping, heing easily fabrisated ancl having a çolor in
the core sheets that çlo~ely matçhes that of the façe and
back sheets.
Also, aççording to this invention, therç is
provided a method of produçing a high pressure deçorative
laminate whiçh compri~es forming a laminate assemhly of,
in superimposed relation~ship, a plurality of resin
impregnated paper çore .sh&ets, a resin impregnated façe
~heet and, optionally, a resin impregnated baçk ~heet,
wherein the impregnant in the çore
~'
~L;2~0~
s.heets and, optionally, in either or both the face and back
sheets, is an unsaturated polyester having an acid number no
greater than about 90 for providing flexibility to the
consolidated laminate.
The present invention. preferably provides a heat
and pressure consolidated laminate comprising (a) a
thermosetting melamine/formaldehyde reaction product
impregnated face sheet; (b) two or more colored core sheets,
each core sheet impregnated with a solution comprising an
unsaturated polyester having an acid number no greater than
90, and a catalyst for further polymerizing and thermosetting
of the polyester, the impregnated core sheet treated to
obtain about 20 to 70 weight percent resin and the
impregnated core sheet dried to a volatile content of about 1
to 5 weight percent, and (c) an optlonal thermosetting
melamine/formaldehyde reaction product impregnated back
sheet; the resulting consolidated laminate having improved
flexibility as evidenced by a wrap test conducted at ambient
or room temperature in which the resulting laminate wraps
around a 3 to 5 inch radius compared to a current commercially
available laminate with core sheets impregnated with a
melamine/~ormaldehyde reaction product which wraps around a 5
to 6 inch radius.
The present invention also provides, in another
embodiment, a heat ana pressure consolidated laminate
comprising: (a) a polyester resin impregnated face sheet;
(b~ a plurality of core sheets impregnated with a composition
comprising an unsaturated polyester having an acid number no
greater than about 90 for providing flexibility to the
consolidated lamlnate and a solvent for the polyester; and
Ic) an optional melamine/formaldehyde reaction product
impregnated back sheet; the face sheet (a), the core sheets
(b) and the optional back sheet (c) being consolidated by
. . :
. .
: ;
~x~
heat and pressure to provide a laminate having improved
flexihllity as well as being resistant to chipping, being
easily Eabricated and having a color in the core sheets that
matches that of the face and back sheets.
In qeneral, in accordance with the invention, the
core sheets are made by impregnating a cellulosic paper
pigmented in color to conform with the color of the face
sheet, and the face and back sheets produced by impregnating
an alpha cellulose paper optionally containing a pigment or a
print, pattern or design~ Typically, a paper of about a 60
to about a 160 pound basis weight per 3000 square foot ream
is employed for the core sheets while the alpha cellulose
sheet used in the face layer generally runs from about 40 to
about 120 pound basis weight per 3000 square foot ream. The
core sheets may be comprised of any of several saturating
grade papers, such as alpha cellulose, bleached kraft or
cotton linters paper, which are capable of being colored to a
close match to the decor or face sheets.
The unsaturated polyester for the core sheets that
provides flexibility to the laminate generally is a reaction
product of a polyhydric alcohol, a saturated dicarboxylic
acid and an unsaturated dicarboxylic acid. The unsaturated
polyester is preferably prepared from propylene glycol,
isophthalic acid, and maleic anhydride. As is known the acid
component ~enerally is used in about 1.0 to 1.05 moles per
mole of glycol
The unsaturated polyester for use in accordance
with the invention does not affect the color of the pigmented
core sheets as do the dark brown to blac~ phenolic resins.
It is also color stable o~er substantially longer periods of
time than the phenolics.
The unsaturated polyester can also be prepared by
reacting propylene glycol, maleic anhydride and reclaimed
polyethylene terephthalate (PET) resin from, for instance,
carbonated beverage bottles. As is known, a Gatalyst is used
-
, ' ' '
'
,,"
27
for further polymerization of the polyester in preparing the
core sheet impregnate, the catalyst being able to generate
free radical polymerization initiators; i.e., organic peroxides,
inorganic persulfates, the preferred catalyst being t-butyl
perbenzoate. In the treating solution for impregnating the
core sheets with the unsa~urated polyester, a crosslinking
monomer that is a vinyl, acrylic or allylic monomer can be
used, such as styrene, methyl methacrylate, and
diallylphthalate.
The acid number of the unsaturated polyester is
generally no greater than about 90, preferably about 10 or 15
to about 50 or 60 and more preferably about 18 or 20 to about
23 or 25. Excellent results have been obtained with an acid
number of about 20, particularly for the polyester prepared
from propylene glycol, isophthalic acid and maleic a~id, such
preferred polyester also having an SPI Gel test at 80C of
about 4.5 to 6.5 minutes and a Brookfield Viscosity (25C) of
about 14 to 17 poises (60/40 in styrene).
In general, for the polyester the SPI Gel test runs
about 2.5 or 3 minutes up to 7 or 8 minutes and the Brookfield
Viscosity runs about 10 or 11 poises up to 20 or 25 poises.
In general, the reacting composition for
impregnating each of the core layers contains about 30 to 60
parts by weight of the polyester, about 30 to 60 parts by
weight of acetone or other solvent for the polyester, about 1
or 2 up to 8 or 10 percent by weight of t-butyl perbenzoate
or another catalyst for further polymerization of the
polyester and, optionally about 1 to 70 percent by weight of
a crosslinking monomer such as styrene. Preferably, the
treating solution is about equal parts by weight of acetone
and polyester, about 4 weight percent of t-butyl perbenzoate
based on the weight of the polyester, and when used, about 5
to 15 percent by weight of the crosslinking monomer based on
the weight of the polyester.
-
;' ~ ,
, . . .
~6~2~
The unsaturated polyester impregnated core sheets
provi~es the resultant consolidated laminate with greatly
improved flexibility, the laminate being flexible enough at
ambient temperature to wrap around a 3 to 5 inch radius
without brea}~ing compared to a laminate with melamine/
formaldehyde impregnated core sheets that can wrap only
around a 5 to 6 inch radius.
The polyester treating composition generally is a
solution of about 20 to 80 percent by weight solids, the
preferred amount being about 40 to 60 percent by weight, and
the optimum amount being about 45 or 50 percent by weight.
In impregnating the face sheet, as is known in the
art, a thermosettlng melamine/formaldehyde reaction product
is used that is a precondensate prepared from generally about
1.0 to 2.7 moles and preferably about 1.75 to 2.25 moles of
formaldehyde per mole of melamine. Optionally, small amounts,
e.g., about l to 20 weight percent based on the weight of the
reaction product, of modifiers can be used, such modifiers
including dicyandiamide, ortho-para-toluenesulfonamide,
sucrose, and glycols such as diethylene glycol.
As previously indicated, the face sheet can be
impregnated by a polyester resin, preferably the same
unsaturated polyester resin used in impregnating the core
sheets.
In some cases although not preferred, a resin
system for impregnating the face sheet or even the core
sheets can be used that is a blend of melamine (about 15 to
25 weight percent) and a polyester resin (about 75 to 85
weight percent) as described in the Richardson U.S. Patent
30 No. 2,809.911. The Richardson patent does not describe a
melamine/formaldehyde print face sheet and there are
dissimilarities between the Richardson patent structure and
the laminate in accordance with the present invention
including the nature and structure of the polyester molecule
-
used, the resin content of the core, the treating methods and
drying time, the laminating pressures and the laminate
construction.
In preparing the multiple resin system decorative
laminates of the invention, excellent results have been
obtained with about 5 to 9 and preferably 6 or 7 core sheets
impregnated with the unsaturated polyester treating solution
at a resin content of about 38 to 42 weight percent, and
dried at about 180F to 220~F to a volatile content of
generally about 1.5 to 4 percent by weight and preferably
jl about 2 or 3.5 percent by weight.
The resulting laminates are generally about 0.05 to
0.07 inches in thickness, have improved flexibility as well
; as good color match, and possess the desirable properties of
resistance to chipping, punchability, ease of handling and
fabrication as well as retaining the normal expectations on
. stain resistance, scratch resistance, surface wear, etc.
A preferred process for manufacturing a laminate of
, the present invention comprises stacking the impregnated
~, 20 sheets, after at least partial drying, in the desired number
and configuration and placing the stack between stainless
steel press plates. An optional texturizing sheet may be
used and placed between the face sheet and one of the plates
to provide gloss and texture to the face sheet, the
texturizing sheet being removed after pressing. Thereafter,
a pressure of from about 800 to 1400 psi at temperatures from
about 240F to 350~F is exerted on the press plates for
periods of from 20 minutes to 90 minutes to effect the cure
and thereby provide the high pressure decorative laminate.
The following example is intended to illustrate the
invention but not to limit it in any way.
.
. : :
;' .'- .
' ;~ . :
- , .
~L2g~i40~7
EXAMPLE
A print or face sheet was prepared by treating a
roll of pigmented alpha-cellulose decorative paper with a
melamine~ormaldehyde reaction product, the paper being one
with a basis weight of approximately 69 pounds per 3000 FT2.
The melamine/formaldehyde ~eac-ti~n product was prepared by
reacting 2.0 moles of formaldehyde per m~le of melamine and
adding 2 percent by welght o dicyandiamide as a n~odifier.
The web of paper was carried through a resin filled
dip pan, over sky rolls for better penetration, and through
squeeze rolls to obtain a resin content of 55 percent. The
web was dried in a treater oven to a volatile content of
5 percent and the proper sheet lengths were cut from the web.
The unsaturated polyester impregnated core sheet
was prepared by treating a roll of pigmented alpha-cellulose
decorative paper with a basis weight of 97 pounds per 3000 FT2
in a polyester resin. The resin was prepared by reacting
propylene glycol, isophthalic acid and maleic acid to provide
a polyester having an acid number of 20. The polyester resin
was diluted to a 50 percent solids solution usiny acetone as
the solvent and 4 percent tertiary butyl perbenzoate was
added to catalyze the polyester. The unsaturated polyester
resin solution was as follow:
25Polyester Resin Solution
100 pounds Polyester
100 pounds Acetone
4 pounds Tertiary Butyl Perbenzoate
30The web of alpha-cellulose paper was carried
through the polyester resin filled dip pan and through mayer
rods to obtain the desired resin ~ontent of 40 percent. The
web was dried to a ~olatile content of 2 percent and cut to a
sheet length comparable to the print sheet.
. ~
: ~ , :
~ - , .'
~26~)27
The solid color laminate was constructed as by
assembling the component sheets as illustrated below.
1 Texturizing Paper (clay filled alpha-cellulose
paper)
1 Melamine Treated Print Sheet (Face Sheet)
6 Polyester Treated Core Sheets
1 Melamine Treated Print Sheet (Back Sheet)
The sheets were consolidated in a hydraulic press
under 1200 psi of pressure and at a temperature of 285F for
a total cure cycle of one(1) hour. After pressing, the
texturizing paper was removed and the laminate was trimmed
and sanded.
The resultant consolidated laminate met the re~uired
NEMA standards. The resultant laminate was resistant to
chipping, easily fabricated and had a color in the core
sheets that matches the face and back sheets. The laminate
was flexible as evidenced by a room temperature wrap test in
which the laminate wraps around a 3 to 5 inch radius.
.
' : `
