Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACKGROUND OF T~IE INVENTION
The present invention relates to the manufacture of a decorative
panel, more specifically, of a decorative panel impressed with a permanently
embossed pattern.
Known is the manufacture of a so-called moulded panel which is
used as a decorative means for luxurious furniture, doors, cabinets,side-
boards, book-shelves, etc., by applying to the surface of the material
machine tools such as three-face or four-face automatic planningmachines,
single-spindle or double-spindle chamfering machines or milling machines,
together with handicraft work, according to the desired scheme. However
in applying such conventional machining techniquesto produce an embossed
pattern in accordance with a desired scheme, not only are the kinds of wood
used restricted, but also the value of the machined wood may be deprecia-
ted by the finishing which follows the machining, depending upon the kinds
of wood used. Moreover, when an intricate embossed pattern is to be
created by shaping the amount of handicraft in the job increases and since
¦ this demands a high degree of skill, the work becomes extremely inefficient.
The present invention therefore provides a technically easy, and
economical process of manufacturing a decorative panel bearing a sedate,
tasteful, intricate embossed pattern such as seen on conventional panel,
by the simple means of pressing under a pattern mould, instead of
resorting to the conventional complicated handicraft which calls for high
skill thereby, eliminating the difficulty and inconvenience of conventional
machining.
mus the present invention provides
a process for manufacturing a decorative panel having a
permanently embossed pattern on a surface comprising the steps of:
providing a mount of fibrous material having a water content of 8-13%
by weight with a rough, fibrous textured surface and selected from
particle board, composite wood, hard fibre board, non-woven cloth and
compressed felting; impregnating said surface to a depth of 1-3 mm with
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a solution of a thermosetting high molecular weight substance; forming
a provisional lamination of a thin decorative layer comprising a slice
of cooked wood having a water content of 8-50% by weight with a grain
pattern on said rougll impregnated surface using an adhesive therebetween
applied at a rate of 80-200 g/m2 and having a solids content of 40-50%,
the adhesive being selected from polyvinyl acetate emulsion, vinyl
acetate copolymer emulsion and polymeric acetate emulsion compound with
the decorative side out; and heat-pressing said provisional lamination
with the decorative side in contact with a mould surface bearing the
required embossed pattern, before said impregnating material and said
adhesive harden.
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¦ According to another aspect of the present invention, the pro-
cess for manufacturing a decorative panel impressed with a permanently
embossed pattern as described above with respect to the one aspect of
the invention, further comprises a step of treating the decorative sur-
face with a surface-treating agent prior to the step of heat-pressing the
provisional lamination.
According to still another aspect of the present invention,
-the process for manufacturing a decorative panel impressed with a perma-
nently embossed pattern as described above with respect to the first
aspect of the invention, further comprises a step of enveloping at least
the whole surface of the provisional lamination in a thermoplastic film
prior to the step of heat-pressing the provisional lamination.
The foregoing as well as the characteristic
features of the present invention will become more apparent and more
readily understandable from the following description and the appended
claims.
The process for manufacturing a decorative panel impressed
with a permanently embossed pattern according to the present invention
is proposed in an effort to overcome the difficulty and inconvenience
of conventional shaping practices. In this proposed process, a decorative
veneer or a decorative impregnated paper overlaid on a fibrous mount is
utilized without losing the beauty of the natural wood of the veneer or
without losing the intricate, beautiful pattern of the decorative im-
pregnated paper, and only by heat-pressing under a pattern mould can an
embossed pattern of a desired scheme be exactly reproduced to thereby
successfully offer a novel decorative panel.
In one embodiment of the present invention, a rough fibrous
texture is presented on a surface of a fibrous mount, the surface is im-
pregnated with a solution or an emulsion of a thermosetting high-molecular
weight substance, and only the solvent in the solution or emulsion is
substantiaily evaporated without allowing the thermosetting high-molecular
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weight substance to harden, then a decorative thin veneer or a decorative
impregnated paper is overlaid on the thermosetting high-molecular weight
i substance impregnated surface, with an adhesive inserted therebetween,
and this laminated product with its decorative side in contact with a
pattern mould bearing an embossed pattern is heat-pressed under the
mould, prior to hardening of the impregnation and the adhesive.
The mount whlch forms the material of the decorative panel,
upon which the embossed pattern is to be reproduced, is mainly selected
from boards such as particle board,
composite wood or from fibrous moulded products such as hard fibreboard,
non woven cloth and compressed felting. There is no limitation on the
thickness, but generally speaking, 10 - 20 mm would be preferable, be-
cause it would facilitate the subsequent step of heat-pressing and would
widen the scope of applicability for the final product.
The fibrous mount to be used has its surface coarsened, in
other words, short, fine fibres are frmed on the surface. Thus the
fibrous moulded products described above by way of example, which are
originally rough on the surface, may be employed as they are, but the
less coarse boards tescribed by way of example prior to the fibrous moulded
products, would have to be submitted to a coarsening process to expose
short, fine fibres, such as by scraping the relatively smooth surface. Even
the fibrous moulded products might need such a treatment if the surface has
to be coarser.
The moisture ln such a mount is a factor governing the value of
the decorative panel of the invention and it is preferably adjusted to
8 - 13 ~ by weight.
According to the present invention, the surface layer of the
mount is preliminarily impregnated with a solution or an emulsion of a
thermosetting high-molecular weight substance.
As an example urea-formaldehyde resin, melamine-formaldehyde
resin, thermosetting acrylic resin, phenolic resin, epoxy resin, diallylphth-
alate resin, natural rubber, styrene-butadiene rubber, and butadiene-acryloni-
trile rubber can be used singly or in combinations as the high molecular
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weight substance.
Impregnatlon with a solution or an emulsion of such a high-
molecular weight substance is done by brushing, spraying, or by means of
a roll-coater, a spreader,etc.
Special technical attention should be paid in this impregnation
to the tepth of impregnation into the surface layer. Such is dependent
on the depth and profile of the embossment of the pattern on the metal
mould bearing the embossed pattern and to be used for subsequent heat-pres-
sing, but generally impregnation has to be done carefully so that the
impregnated substance may be evenly distributed over only the surface
layer in a depth of 1 - 3 mm.
Still more important, the solution or emulsion of the thermoset-
ting high-molecular weight substance thus impregnated into the surface layer
of the mount should, without immediately thermosetting, be allowed to
stay as is for 30 minutes to 48 hours at a temperature within the range
of room temperature up to 50C so that the solvent or water in the solution
or emulsion may be substsntially evaporated.
According to the present invention, thereafter, a decorative
veneer of a decorative impregnated paper is provisionally adhered by
means of an adhesive, to the mount with its surface layer impregnated
with a non-cured high-molecular weight substance. Then the provisionally
adhered assembly is left as it is at an ambient temperature for 20 minutes
to three hours, during which it becomes dry to the finger touch.
The adhesive may be, for example, polyvinyl acetate emulsion
or a composition obtained by mixing polyvinyl acetate emulsion with sty- -
rene-butadiene latex, synthetic rubber, such as chloroprene, epoxy resin, an
emulsion of a melamine-formaldehyde pre-condensate or a urea-formaldehyde
pre-condensate and a composition obtained by mixing a homo-polymer emulsion
of vinyl acetate or a copolymer emulsion of vinyl acetate with ethylene or
acrylic ester and so on with the second component having functional groups
such as unsaturated carboxylic acid, for example, maleic acid or acrylic
acid, alkyl ester of unsaturated carboxylic acid or amide of unsaturated
carboxylic acid, the amount of adhesive applied b~lng desirab~ 80 - 200
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gr/m2 ln terms of 40 - 50 % solids.
The decorative veneer mentioned in the present invention refers
preferably to thin sllces about 0.2 - 0.7 mm or preferably 0.25 - 0.35
mm thick, with quarter sawn grain, flat sawn grain or mixed grain or
knurls, of wood such as "nara (a type of oak)", "Nire (a type of elm)",
"Sakura (cherry)", "shio~i ~Fraxinus Spaethiana)" or of imported wood
such as teak walnut, rosewood, zebrawood, mahogany. The allowable
water content of the decorative veneer depends on the type of impregna-
tion of the mount and on the type of athesive applied to the mount. When
the impregnation is by epoxy resin, the value of allowable water content
is about 50% and when it is diallylphthalate, the value should be set
at about 10 %. Generally speaking, a low water content in the range of
8 - 50 % is deemed one of the factors assuring good and fa~thful repro-
duction of a pattern on the veneer.
The decorative impregnated paper which may be substituted
for the decorative veneer may be a patterned paper with a wood grain or a
pattern printed thereon, which consists of a base of sulphite pulp or rayon
pulp impregnated with a thermosetting synthetic resin or a composition of
a thermosetting synthetic resin and a thermoplastic synthetic resin; one
which is commercially available with a fat content of 45 - 70 % and thick-
ness of 2 - 5 mills may be employed.
It is known that phenolic resin, diallylphthalate resin, mel-
amine resin, unsaturated polyester resin, epoxy resin, guanamine
resin, thermosetting acrylic resin, methacrylic acid ester, etc. are
available for impregnation in the commercial production of the decora-
tive impregnated paper. If i* is necessary to faithfully reproduce an
intricate embossed pattern in the subsequent step of heat-pressing
under a metal mould bearing an embossed pattern, the ob~ect will be attained
successfully by adopting a base impregnated with diallylphthalate resin
8S compounded with a thermosetting acrylic resin (a copolymer of methylol
methacrylic amide or methylol amide which gives a functional side chain
to styrene, methacrylic acid ester, acrylic acid ester or acrylonitrile)
such that the fat content may be 75 - 80 %.
The provisionally adhered laminatlon of the mount and the decor-
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atlve impregnated paper is placed, prior to the hardening of the impreg-
nating material and the adhesive, upon a metal mould bearing a deslrable
embossed pattern, with the decorative side directly in contact with the
mould, and then the lamination is heat-pressed against the mould.
The conditions of heat-pressing depend on the type of impreg-
nated substance, but the common standard conditions are: 90 - 170C, 70 -
250 kg/cm2, 1 - S minutes.
By such heat-pressing, a decorative panel with a permanently
embossed pattern according to the present invention can be obtained
successfully, with the embossed pattern faithfully reproduced on the
decorative veneer or decorative impregnated paper.
The following is one embodiment of the present invention.
A particle board 15 mm thick with a water content of 12 % was used as
the mount. The surface of the mount was scraped to expose rough clusters
of short, fine fibres. The surface layer of the mount to a depth of ~ mm
was repeatedly impregnated with the following resin compounds by means of
a spreader:
Impregnated resin compound ~Example 1~
~ Diallylphthalate prepolymer ......... 100 parts by weight
Diallylphthalate monomer ............ 10 parts by weight
Benzoyl peroxide .................... 3 parts by weight
Tricholoroethylene .................. 50 parts by weight
Impregnated resin compound ~Example 2)
Bisphenol A-type epoxy resin......... 100 parts by weight
Amine type hardening agent .......... 8 parts by weight
Methyl ethyl ketone ................. 35 parts by weight
Toluene ............................. 15 parts by weight
Following the impregnation, the mount was left for about 30
minutes to allow the solvent to evaporate, after which an adhesive com-
posed of polyvinyl acetate emulsion, 100 parts by weight; urea resin,10 parts by weight; and wheat flour, 5 parts by weight; was applied to
the surface of the mount at a rate of 150 gr/m in terms of solids by
means of a glue spreader or a hand roller and the water content was allowed
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to evaporate. Next the mount with an overlay of a decorative veneer
0.3 mm thick shaved from a mahogany wood with water content adjusted to
13 % was left, provisionaly adhered together with the first mount at room
temperature for three hours. Instead of leaving at room temperature, a
hot press may be used for 40 seconds at 130C and 10 kg/cm for the
purpose of provisional adhering.
The provisional lamination of the mount and the decorative
veneer was placed in a hot press, with the decorative side in direct
contact with a metal mould bearing a desired embossed pattern provided
on the hot press, and then heat-pressed under the conditions of 130C,
100 kg/cm , for 3 minutes, thereby producing a decorative panel with a
permanently embossed pattern reproduced thereon, characterized by excel-
lence in resistance to water, humitity, weather, heat, wear and chemicals.
A second embodiment of the present invention is generally
the same as the first one except for the following point. Namely, the
surface of the provisional lamination of the mount and the decorative
veneer of impregnated paper is coated with a surface-treating agent
mainly composed of polyethylene glycol or a copolymer of ethylene and
vinyl acetate.
The surface-treating agent applied for this purpose is a
compound mainly composed of polyethylene glycol or a coplymer of ethylene
and vinyl acetate which is applied by means of a spreader or by brushing.
The effect of this coating in the case of a decorative veneer is that the
agent whlch penetrates the fibre voids and capillaries softens the ve~
neer itself, helps the slipping and sticking of fibres and facilitates
demoulding in heat-pressing, thereby assuring uniform finishing of the pro-
ducts. In the case of a decorative paper the effect is similar to the above,
the slipping and sticking of the paper surface being improved.
The desirable amount of application ls in the case of a copoly-
mer of ethylene and vinyl acetate 50 - 150 gr/m2 in terms of i2% solids.
In the same way as in the first embodiment the provisional
lamination of the mount and the decorative veneer or impregnated paper
thus surface-treated is placed and heat-pressed in the hot press, with
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the decorative side in direct contact with the metal mould bearing an
embossed pattern.
The surface-treating agent may be applied as above after pro-
visional lamination, as the veneer or paper to which the agent has been
preliminarily applied may be overlaid on the member and then provision-
ally adhered together.
Except for the step of applying the surface-treating agent,
the second embodiment comprises the same steps as the first one. In
the second embodiment the provisional lamination is obtained in the same
manner as in the first one. Thereafter ethylene-vinyl acetate emulsion
12 % solids is brushed on the surface of the decorative veneer at a
rate of 120 gr/m . Next, in a way similar to the first embodiment, the
provisional lamination of the mount and the decoratlve veneer or paper
to which has been applied the surface-treating agent, is placed in a
hot press, with the decorative side in direct contact with the metal
mould bearing the desired embossed pattern; and then heat-pressPd under
the conditions of 130C, 100 kg/m and 3 minutes, thereby producing a
decorative panel with a permanently embossed pattern reproduced thereon,
characterized by excellence in resistance to water, humidity, weather,
heat, wear and chemicals.
A third embodiment of the present invention follows generally
the same process as the first one except for the following step. Namely
the step i~ added of enveloping at least the whole surface of the provi-
sional lamination of the mount and the decorative veneer or impregnated
paper obtained in the manufacturing process of the first embodiment in a
thermoplastic substance which can form a film in the subsequent step of
heat-pressing. The added step has the effect of giving a moulded product
a high fidelity of reproducing a ~pecific pattern of the mould as well as
improving the cushioning, slipping and demouldability of the lamination
against the metal mould, and facilitating the step of heat-pressing. The
envelopment of the lamination in the thermoplastic film may be done by
means of an adhesive.
Thereafter the lamination is placed and heat-pressed in a
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hot preas, with the decorative side in direct contact with the metal
mould bearing an embossed pattern.
Except for the step of applying the thermoplastic film, the
third embodiment is the s8me as the irst one.
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In this case the provlsional lamination obtained in the same
way as in the first embodiment is enveloped in a coat of adhesive in a
polyethylene ilm; placed in a hot press, with the decorative side in
direct contact with the metal mould bearing the desired embossed pattern;
andthen heat-pressed under the conditions of 130C, 100 kg/m2, for 3
minutes, thereby producing a decorative panel with a permanently em-
bossed pattern reproduced thereon, characteri~ed by excellence in resis- ~:
tance to water, humidity, weather, heat, wear and chemicals.
