ARTICLE MOULE PAR EXTRUSION FABRIQUE A PARTIR DE RESINE POLYMERE-BOIS, ET PROCEDE DE FABRICATION ASSOCIE

EXTRUSION MOLDING ARTICLE FROM WOOD-POLYMER RESIN AND METHOD FOR PRODUCING THE SAME

Abrégé français

L'invention concerne la production d'un article moulé par extrusion ayant un aspect ressemblant à celui du bois naturel, ainsi qu'un procédé permettant de produire ledit article. On produit l'article moulé constitué de résines par un procédé de moulage par extrusion de la manière suivante: on produit la partie lustrée, présentant au moins une face lustrée, à partir d'un matériau à base de résine contenant de la poudre de bois, dans lequel la résine est mélangée à la poudre de bois. Le matériau à base de résine contenant de la poudre de bois renferme entre 20 et 40 parties de poudre de bois ayant un calibre de 20 mesh ou moins, et entre 0,5 et 4 parties d'un agent d'expansion pour 100 parties de résine thermoplastique. On forme la face lustrée en enlevant les couches de peaux formées durant le moulage par extrusion.

Abrégé anglais

The object of the present invention is to provide an extrusion molding article
having an appearance resembling to natural timbers, and a method for producing
the same. The molded article of resins by an extrusion molding is produced as
follows: The glazed portion comprising at least a glazed face is produced with
a resin material containing wood powder in which the resin is blended with the
wood powder. The resin material containing wood powder comprises 20 to 40
parts of the wood powder having a particle size of 20 meshes or less and 0.5
to 4 parts of a blowing agent in 100 parts of a thermoplastic resin. The
glazed face is formed by removing skin layers formed during the extrusion
molding.

Revendications

CLAIMS
1. A molded article formed by an extrusion molding of
resins, characterized in that a glazed portion that forms at
least a glazed face is composed of a resin material
containing a wood powder in which the resin is mixed with the
wood powder:
the resin containing the wood powder being composed
of 20 to 40 parts of the wood powder having a particle size
of 20 meshes or less and 0.5 to 4 parts of a blowing agent
in 100 parts of a thermoplastic resin; and
the glazed race being formed by removing skin layers
formed during the extrusion molding.
2. An extrusion molding articles of resins according to
Claim 1, wherein the glazed portion is formed by a
monolithic extrusion molding with the other portions of the
resin.
3. An extrusion molding article of resins according to
Claim 1 or claim 2, wherein the glazed portion and the other
portions are composed of a resin material containing wood
powder that forms the glazed portion.
4. An extrusion molding resin according to Claim 1,
Claim 2 or Claim 3, wherein the wood powder in the resin
containing wood powder that comprises the glazed portion is
produced by grinding the crushed powder obtained by crushing
a cellulose material; and by adhering surface grains having
a smaller particle size and higher hardness than those of
the crushed powder on the peripheral surface of the crushed
powder.
5. A method for producing a molded article formed by an
extrusion molding of resins comprising the steps of:
preparing a resin material containing wood powder
composed of 20 to 40 parts or the wood powder having a
particle size of 20 meshes or less and 0.5 to 4 parts of a
blowing agent in 100 parts of a thermoplastic resin;
extrusion molding a glazed portion that forms at
least a glazed face by using a resin material containing
wood powder ; and
removing the skin layers formed during the extrusion
molding step.

Description

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DESCRIPTlON
EXTRUSION MOLDING A~TICLE FROM WOOD-POLYMER R~SIN AN~ METHOO FOR PROOUCIN6
T~E SAME
Technical Field
~ he present inventlon relate~ to an art ~or
produclng an extrusion molding article Or resins. In ~ore
detail, the ln~entlon is characterlzed by blending wood
powder and a small amount o~ a blowing agent in a res1n
material ~or extrusion, ~ollowed by removing skln layers
~ormed on the suriace Or the ~o}ded article.
Background Art
~ ome building components, in which e~trusion molding
articles o~ resln materials cont~intng wood powder are
~requently used, are described below as a related art.
~ xtrusion molding articles of synthetic resins have
been ~requentlY used ~or highly processed building
components like a door sash instead o~ wooden components
made o~ natural timbers. The ~aterials ~or these extrusion
molding ~rticles o~ synthetic resins are, ~or example, a
hard ~inyl chloride resin with which several tens percentage
o~ wood powder is blended. T~e e~trusion molding article
comprising the aforementioned materials can be previously
formed into a desired shape ~hile the natural timbers
require several times of pl ~ning steps. Thereiore,
processing steps a~ter the molding can be larsely reduced in
addition to enabling the article to be cut with a sa~ or to
be ~ixed with nails, which makes the construction 90 easy.
However, the new article according to the art
described above yet involves se~eral problems that its
speci~ic gra~ity is so large cumpared with that of timbers
and its sur~ace becomes so hard by ~orming skin layers on
the surface that an wood-like touch is lost. Moreover,
since its compatibility wlth vinyl acetate based adheslves
or paints that are commonly used ~or the wooden components
is low, sdhesion or painting with the resin was di~ficult.
Therefore, the uses o~ this new article were limited.
Disclosure of Invention -
Accor~nFly, the ob~ect o~ the present invention ~s
to provide an art for producing sn e~trusion molding article
havin~ properties more resembllng to natural ti~bers.
The deficiencies o~ the e~trusion molding article o~
resins Cont~n1nF wood -powder have been solved -by the

CA 02255859 1998-11-23
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present 1nvention characte~ized by ~aking the degree of
foaming of the molded article low and removing the skin
layers rormed on the s~r~ace oi the molded article. Foaming
yields wood like properties in the article by reducing its
specific gravity. Moreover, the skin layers rormed on the
sur~ace becomes so thln that they can easily be removed by
brn~h~ n F
(E~planation Or Claim 1)
The present lnventlon according to Claim 1 provides
a molded article for~ed by an e~trusion molding o~ resins,
characterized in that a glazed portion that ~orms at least a
glazed ~ace is composed o~ a resin materlal containing wood
powder in which the resin is mi~ed wlth the wood powder: the
resln conta~nlng wood powder ~eing composed o~ 20 to 40
parts o~ the wood powder having a particle size o~ 20 meshes
or less and 0.5 to 4 parts of a blowlng agent in 100 parts
o~ a thermoplastic resin; and the glazed face being rormed
by removlng skin layers formed during the extrusion molding.
The foregoing "glazed portion" denotes a visible
portlon when molded articles o~ resins formed by the
extrusion molding o~ resins according to the present
lnvention are brought in a circumstance where their inherent
~unctions can be exhibited.
(Explanation of Claim 2)
The present invention according to Claim 2 is
provided ror technically limiting the invention according to
claim 1, wherein the glazed portlon ls rormed by a
monolithic extrusion molding with the other portions of the
resin.
When the glazed portion and the other portion are
composed o~ di~erent materials with each other, both
portions are rormed by a monolithic extrusion.
~ E~planation of Claim 3)
The present invention according to Claim 3 is
provided ror technically,limiting the invention according to
Claim 1 or Claim 2, whereln the glazed portlon and the ~ther
portions are composed o~ a resin material cont~ln~ng wood
powder that ~or~s the glazed portion.
In this case, the Klazed portlon and the other
portion are composed o~ an identical material, the whole
being produced by using the material comprislng the glazed
portion.
(Explanation o~ Claim 4)
The present invention acc~rding to Claim 4 is
characterized in that the wood powder ln the resln
cont~ n 1 ng wood powder that cumprises the glazed portion is

produced by grinding the crushed powder obtained by crushing
a cellulose material; and by adhering surface grains having
a smaller particle size and higher hardness than those of
the crushed powder on the peripheral surface of the crushed
powder.
The "cellulose material" described herein denotes
natural woods as well as such materials including sawdust,
rice straws and bagasse.
The "resin" includes hard resins, for example, such
as polyvinyl chloride resin, foamed polyvinyl chloride
resin, polyethylene resin, polypropylene resin, phenol
resin, urethane resin, polyurethane resin, ABS resin and
polystylene resin. Soft type resin may be also used
depending on the molded articles required.
The "surface grains" correspond to titanium oxide,
aluminum, nickel, silver, ferrites, thermoplastic resins or
ceramics.
The proportion of the wood powder to be blended with
the resin to the total molded article is adjusted not to
exceed 30% by weight since molding processes may be
interfered with a low fluidity during the molding.
"Pigments" denote colored pigments, examples of them
being inorganic pigments such as iron oxide, cadmium yellow
and carbon black.
(Explanation of Claim 5)
The present invention according to Claim 5 provides
a method for producing a molded article formed by an
extrusion molding of resins comprising the steps of:
preparing a resin material containing wood powder composed
of 20 to 40 parts of the wood powder having a particle size
of 20 meshes or less and 0.5 to 4 parts of a blowing agent
in 100 parts of a thermoplastic resin; extrusion molding a
glazed portion that forms at least a glazed face by using a
resin material containing wood powder; and removing the
skin layers formed during the extrusion molding step.
While the extrusion molding article in which a hard
vinyl chloride resin with a low degree of foaming is used as
a resin contains independently dispersed air bubbles, the
air bubbles in the molded article according to the present
invention appear to be continuous because wood powder is
blended with the resin to connect the air cells with the
wood powder. Therefore, the surface of the molded article
resembles that of the wooden articles both in its touch
sense and visual appearance because capillary like pores are
exposed on the surface of the molded article after removing
skin layers. When paints or adhesives are coated on this

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surrace, the coating rilm tightly adheres on the sur~ace
because a part Or the coating ~ilm penetrates deep into the
pore.
Best Mode ~or Carrying Out the In~ention
Blended in a ml~er are 100 parts o~ hard vinyl
chloride, 30 parts o~ wood powder having a partlcle size o~
meshes or less, 1 part of a blowing agent
(azodlcarboxyllc acid amide~ and each 5 parts Or a
stabilizer, lubricant and reinrorcer. The mixture is heated
by a conventional method and, arter coollng, is placed in an
e~truder, thereby ~orming a ~olded artlcle of hard vinyl
chloride resin having a desired shape wlth a low degree o~
roamlng. Skin layers rormed on the suriace Or the mo~ded
article was then removed by a wire brush to obtain a rinal
product.
This product has an appearance similar to natural
timbers since it has a speci~ic gravity within 0.5 to 1Ø
The sur~ace Or the molded article resembles that of the
wooden articles both in its touch sense and ~isual
appearance because continuous capillary llke pores are
exposed on the sur~ace o~ the molded article aiter removing
skin layers. When paints or adhesives are coated on th1s
sur~ace, the adheslve strength ~g~n~t the surface was
enhanced because a~ wedge e~rect ~as e2hibited by partly
penetrating the layer of the adhesive or paint deep into the
pore.
The product produced as described above has a he~t
eYr~n~ion coeriicient 1/2 to lJ3 times that of the
conventional products. Thererore, the molded article
according to the present invention ls widely applicable
because peeling of~ by temperature changes is not likely to
occur when the molded article is adhered on timbers or
metals.
Through the ~oint parts Or the inter~or pack~ing Or
the building has been liable to generate gaps by a heat
e~p~n~ion when conventional resin products are used an~ a
construction method similar with that o~ natural timbers
were impossible, the products according to the present
inve~tion enables a con~truction wlth a good ~ppearance
without creating any gaps.
Industrial Applicability
Accor~ingly, the present invention provides a
e2trusion moldlng artic~e havlng an appearance resembling to
natural tim~ers and a method rOr producing the same. -