U.S. patent application number 13/977507 was filed with the patent office on 2013-10-10 for eco-friendly foaming sheet.
This patent application is currently assigned to LG Hausys, Ltd.. The applicant listed for this patent is Gun Soo Chung, Si Young Lee, Youn Woo Nam. Invention is credited to Gun Soo Chung, Si Young Lee, Youn Woo Nam.
Application Number | 20130266767 13/977507 |
Document ID | / |
Family ID | 46383655 |
Filed Date | 2013-10-10 |
United States Patent
Application |
20130266767 |
Kind Code |
A1 |
Chung; Gun Soo ; et
al. |
October 10, 2013 |
ECO-FRIENDLY FOAMING SHEET
Abstract
The present invention provides an eco-friendly foaming sheet.
More particularly, the eco-friendly foaming sheet is fabricated
using a biodegradable resin composition on a substrate, wherein the
biodegradable resin composition is applied to the substrate sheet,
a print layer is formed thereon, and the treated sheet is subjected
to foaming. According to the present invention, without processes
of preparing a sheet and foaming using a biodegradable resin, the
biodegradable resin layer is directly applied to a substrate sheet
as a subject to be used and foamed while forming a print layer, in
addition, a chemical foaming agent and an eco-friendly plasticizer
used together with the biodegradable resin are specifically defined
to ensure desired flexibility, thereby fabricating an eco-friendly
foaming sheet with high productivity.
Inventors: |
Chung; Gun Soo;
(Cheongju-si, KR) ; Nam; Youn Woo; (Cheongju-si,
KR) ; Lee; Si Young; (Cheongju-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Chung; Gun Soo
Nam; Youn Woo
Lee; Si Young |
Cheongju-si
Cheongju-si
Cheongju-si |
|
KR
KR
KR |
|
|
Assignee: |
LG Hausys, Ltd.
Seoul
KR
|
Family ID: |
46383655 |
Appl. No.: |
13/977507 |
Filed: |
December 23, 2011 |
PCT Filed: |
December 23, 2011 |
PCT NO: |
PCT/KR11/10032 |
371 Date: |
June 28, 2013 |
Current U.S.
Class: |
428/159 ;
428/195.1; 428/196; 428/211.1 |
Current CPC
Class: |
C08J 9/0023 20130101;
B32B 5/022 20130101; B32B 27/10 20130101; B29K 2995/006 20130101;
B32B 27/065 20130101; B32B 2266/0214 20130101; B32B 5/18 20130101;
B32B 29/007 20130101; B32B 2307/75 20130101; B32B 2607/02 20130101;
B32B 5/245 20130101; B32B 2367/00 20130101; B32B 3/30 20130101;
Y10T 428/24504 20150115; B32B 27/12 20130101; B29K 2067/046
20130101; B29C 44/14 20130101; B32B 2266/0264 20130101; Y10T
428/2481 20150115; E04F 13/002 20130101; B29C 39/18 20130101; B32B
27/36 20130101; Y10T 428/24802 20150115; Y10T 428/24934 20150115;
C08J 9/06 20130101; C08J 2300/16 20130101; B32B 2307/7163
20130101 |
Class at
Publication: |
428/159 ;
428/195.1; 428/196; 428/211.1 |
International
Class: |
E04F 13/00 20060101
E04F013/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 30, 2010 |
KR |
10-2010-0138391 |
Claims
1. An eco-friendly foaming sheet fabricated using a biodegradable
resin composition on a substrate sheet, wherein the biodegradable
resin composition is applied to the substrate sheet to form a resin
layer, a print layer is provided on the formed resin layer, and the
treated sheet is subjected to foaming.
2. The foaming sheet according to claim 1, wherein the resin layer
is formed by T-die extrusion coating of the biodegradable resin
composition on the substrate sheet.
3. The foaming sheet according to claim 2, wherein the resin layer
is formed to satisfy a thickness ranging from 0.01 to 50 mm.
4. The foaming sheet according to claim 1, wherein the
biodegradable resin composition includes a biodegradable resin, a
chemical foaming agent and an eco-friendly plasticizer.
5. The foaming sheet according to claim 1, wherein the substrate
sheet is a vellum paper or non-woven fabric having an average
weight of 80 to 200 g/m.sup.2 and a thickness of 0.1 to 0.5 mm.
6. The foaming sheet according to claim 4, wherein the
biodegradable resin is at least one selected from a group
consisting of; polylactic acid, polycondensed aliphatic
biodegradable polyester, polycondensed copolymer aromatic
biodegradable polyester, lactone resins, biodegradable cellulose
ester, polypeptides, polyvinylalcohol, starches, cellulose,
chitin/chitosan and natural linear polyester resins.
7. The foaming sheet according to claim 6, wherein the
biodegradable resin is a composite resin containing polylactic acid
as a first resin, as well as at least one resin selected from a
group consisting of poly(butylene succinate), polybutylene
succinate/adipate copolymers, polybutylene adipate/terephthalate
copolymers and ethylvinyl acetate, as a second resin.
8. The foaming sheet according to claim 7, wherein the composite
resin includes at least one second resin selected from a group
consisting of polybutylene succinate, polybutylene
succinate/adipate copolymers, polybutylene adipate/terephthalate
copolymers and ethylvinyl acetate in an amount of 120 to 500 parts
by weight, relative to 100 parts by weight of the first resin.
9. The foaming sheet according to claim 4, wherein a biodegradable
component including the biodegradable resin is 70% or more,
relative to a total weight of the biodegradable resin
composition.
10. The foaming sheet according to claim 4, wherein the chemical
foaming agent is at least one selected from azo-dicarboxylamide,
benzenesulfonyl hydrazide, dinitroso pentamethylene tetramine,
toluenesulfonyl hydrazide, azo-bis isobutyronitrile, barium
azo-dicarboxylate and sodium bicarbonate, and is used in an amount
of 1 to 10 parts by weight, relative to 100 parts by weight of the
biodegradable resin composition.
11. The foaming sheet according to claim 4, wherein the
eco-friendly plasticizer is a citrate or sugar alcohol-based
plasticizer and is used in an amount of 10 to 80 parts by weight,
relative to 100 parts by weight of the biodegradable resin
composition.
12. The foaming sheet according to claim 1, wherein the foaming is
executed in a chemical foaming mode at a temperature ranging from
120 to 250.degree. C.
13. The foaming sheet according to claim 1, further comprising an
embossed layer over the print layer.
14. The foaming sheet according to claim 1, wherein the print layer
is prepared using the biodegradable resin by gravure printing,
transfer printing, digital printing or rotary printing, and formed
along unevenness of the resin layer in the foaming sheet.
Description
TECHNICAL FIELD
[0001] The present invention relates to an eco-friendly foaming
sheet, more particularly, to an eco-friendly foaming sheet having
flexibility fabricated by directly applying a biodegradable resin
to a substrate sheet, foaming the sheet while forming a resin
layer, and using a specific chemical foaming agent and/or
eco-friendly plasticizer compatible with the biodegradable
resin.
BACKGROUND ART
[0002] Conventionally, a resin foaming material (`foam`) such as a
polyolefin resin foam, a polyurethane resin foam, etc. exhibits
excellent insulation, formability, shock-absorption, etc. as well
as lightweight, thus having been widely used in industrial fields.
However, although such resin foam is light in weight, a volume
thereof is increased and causes difficulties in re-use thereof when
upon being discarded. In particular, cross-linked foam formed by
cross-linking the resin is substantially unable to be reused. Also,
since the resin foam almost permanently remains even when it is
buried in the ground (that is, high non-biodegradable), it is
difficult to ensure a waste disposal space through incineration
and/or landfill, in turn quite often polluting the environment and
damaging the natural landscape.
[0003] Accordingly, biodegradable resins degraded by microorganisms
in natural environments have been researched, developed, and
manufactured into films and/or fibers as commercial products. In
addition, extruded foams of such biodegradable resins have also
been developed. For instance, non cross-linked foam using an
aliphatic polyester resin has been known. However, it has been
difficult to polymerize such aliphatic polyester resin through side
reaction such as hydrolysis using water generated during
poly-condensation. Therefore, a melt viscosity sufficient to
maintain bubbles during extrusion foaming cannot be obtained, thus
entailing problems in preparing foams having favorable foaming
status and/or surface state.
[0004] In order to solve the above problems, for example, Korean
Patent No. 2655796 proposed a method of cross-linking a resin via
ionizing radiation. However, if a subject to be irradiated has a
thickness of more than 1 mm, radiation does not reach the inside of
the subject, which in turn causes formation of coarse and irregular
bubbles in the subject during foaming. Moreover, since
cross-linking requiring irradiation under a N.sub.2 atmosphere, in
order to prevent deterioration of the resin has been required, it
was very difficult to prepare foams having different thicknesses
and satisfactory mechanical properties by a simple preparation
method generally used in the art.
[0005] Meanwhile, according to Japanese Patent Publication No. SHO
46-38716, a continuous preparation method of polypropylene foam
using a propylene/ethylene random copolymer was proposed. In
addition, it was disclosed that using a cross-linking promoter is
preferable to enable smooth and effective cross-linking reaction.
Further, Japanese Laid-Open Patent Publication No. SHO 60-28852
proposed cross-linking and foaming of a mixture of a
propylene/ethylene random copolymer and polyethylene by adding a
cross-linking promoter. However, a polypropylene foam prepared
according to the foregoing method cannot be reused after
cross-linking. Of course, the foam is not biodegradable, in turn
having difficulties in waste disposal. Moreover, other problems
such as high calories for combustion, adverse effects on the
environment, etc. may be entailed.
[0006] Meanwhile, a typical silk wallpaper is also called a
polyvinyl chloride (PVC) wallpaper which is, at present, most
preferably employed and prepared by applying PVC resin to paper, so
as to impart a soft and silk-like surface feel thereto.
[0007] However, since any existing silk wallpaper is fabricated
using PVC resin which is made from a raw material, petroleum, cost
is continuously raised due to exhaustion of petroleum resources, a
large amount of energy is consumed in the manufacture thereof, and
greenhouse gases such as CO.sub.2 are discharged in large
quantities. In addition, for landfill disposal, a long time of 500
years or more is required for biodegradation. On the other hand,
incineration disposal may generate a number of harmful materials
including hormone analogs and/or toxic gases, thus causing
significant environmental contamination.
DISCLOSURE OF INVENTION
Technical Problem
[0008] Accordingly, in order to solve the above problems, the
present invention is directed to provision of an eco-friendly
foaming sheet which has increased flexibility and does not generate
harmful materials such as hormone analogs and/or toxic gases upon
disposal, while reducing the number of production processes to
improve productivity.
Solution to Problem
[0009] In order to accomplish the above object of the present
invention, there is provided an eco-friendly foaming sheet
fabricated using a biodegradable resin composition on a substrate
sheet, wherein the biodegradable resin composition is applied to
the substrate sheet, a printed layer is provided thereon, and the
prepared sheet is subjected to foaming.
[0010] Hereinafter, the eco-friendly foaming sheet according to the
present invention will be described in detail.
[0011] The eco-friendly foaming sheet according to the present
invention may include a substrate sheet, and a biodegradable
resin-containing resin layer which is provided on the substrate
sheet and foamed to have unevenness thereon.
[0012] In this regard, the substrate sheet may be any one generally
known and used in the art without particular limitation thereto.
For instance, a substrate sheet for wallpaper employed in the
manufacture of existing silk paper may be used for the wallpaper.
Examples of the substrate sheet for wallpaper may include vellum
paper and/or non-woven paper (e.g., polyester/pulp composite
non-woven paper), without being particularly limited thereto. The
substrate sheet for a wallpaper described above may have an average
weight of 80 to 200 g/m.sup.2. If the average weight of the
substrate sheet for wallpaper is less than the above range, the
wallpaper may tear or other damage may occur during use or
construction. On the contrary, when the average weight exceeds the
above range, some problems in construction such as heavy weight,
gap, curling, or the like may be encountered.
[0013] In fact, a thickness of the substrate sheet described above
may be defined depending upon applications thereof without being
particularly limited thereto and, in general, may range from 0.1 mm
to 0.5 mm.
[0014] With regard to the present invention, types (or kinds) of
the biodegradable resin included in the print layer as well as the
resin layer may include; polylactic acid, biodegradable
poly-condensed aliphatic polyester, biodegradable poly-condensed
copolymer aromatic polyester, lactone resins, biodegradable
cellulose ester, polypeptide, polyvinylalcohol, starches,
cellulose, chitin/chitosan, natural linear polyester resin, and so
forth. More particularly, synthetic polymers including aliphatic
polyesters obtained by poly-condensation of diols and dicarboxylic
acid or derivatives thereof, for example; polylactic acid;
polyethylene succinate obtained by poly-condensation of ethylene
glycol and succinic acid or derivates thereof; polybutylene
succinate obtained by poly-condensation of butanediol and succinic
acid or derivatives thereof; polybutylene succinate/adipate
obtained from butanediol and dicarboxylic acids, in particular,
succinic acid and adipic acid or derivatives thereof; polybutylene
succinate/carbonate obtained by poly-condensation of bntanediol and
succinic acid and chain extension of the polycondensed material
using a carbonate compound such as diethyl carbonate, may be
used.
[0015] Examples of lactone resins may include a variety of
methylated lactone such as; .epsilon.-caprolactone,
.beta.-propiolactone, .gamma.-butyrolactone, .delta.-valerolactone,
enantolactone or 4-methyl caprolactone, 2,2,4-trimethyl
caprolactone, 3,3,5-trimethyl caprolactone, etc. Biodegradable
aromatic copolymer polyester may include, for example: a
polyethylene terephthalate/succinate copolymer; a polyethylene
terephthalate/adipate copolymer; a polyethylene
terephthalate/sebacate copolymer; a polyethylene
terephthalate/dodecadionate copolymer; a polybutylene
terephthalate/succinate copolymer; a polybutylene
terephthalate/adipate copolymer; a polybutylene
terephthalate/sebacate copolymer; a polybutylene
terephthalate/dodecadionate copolymer; a polyhexylene
terephthalate/succinate copolymer; a polyhexylene
terephthalate/adipate copolymer; a polyhexylene
terephthalate/sebacate copolymer; a polyhexylene
terephthalate/dodecadionate copolymer, or the like. Further,
biodegradable cellulose ester such as cellulose acetate, cellulose
butyrate, cellulose propionate, cellulose nitrate, cellulose
sulfate, cellulose acetate butyrate, cellulose nitrate acetate,
etc. may be used. Additionally, alternative examples of the
synthetic polymer may include polypeptides such as polyglutamic
acid, polyasparaginic acid, polyleucine, etc., or polyvinyl
alcohols.
[0016] As natural polymers, for example, alpha starch such as corn
starch, wheat starch, rice starch, etc.; and/or processed starch
such as acetic esterified starch acetate, methyletherified starch,
etc., may be used. Also, natural polymers, for example, natural
linear polyester resins such as cellulose, carrageenan,
chitin/chitosan, polyhydroxyl butyrate/valerate, or the like may be
used.
[0017] Copolymers of components for the biodegradable resin
described above may also be used. The biodegradable resin may be
used alone or as a combination of two or more thereof. Such
biodegradable resins may include, for example: polylactic acid; an
aliphatic polyester obtained by poly-condensation of diol and
dicarboxylic acid and derivates thereof; a biodegradable copolymer
aromatic polyester obtained by poly-condensation of a dicarboxylic
acid component, which includes an aromatic dicarboxylic acid and a
derivative thereof as well as an aliphatic dicarboxylic acid and a
derivative thereof, and a diol component including an aliphatic
diol; lactone resins, or the like.
[0018] More preferably, the resin layer may include, as a first
resin, the above poly(lactic acid) (PLA) and a second resin, that
is, at least one selected from a group consisting of poly(butylene
succinate) (PBS), a butylene succinate/adipate copolymer (PBSA) and
a butylene adipate/terephthalate copolymer (PBAT), in a combined
form thereof. Compared to use of poly(lactic acid) (PLA) or
specific biodegradable resins, respectively, biodegradability and
flexibility of a wallpaper may be easily controlled, thus realizing
beneficial effects. In the present invention, if the resin layer
comprises a composite resin, at least one selected from a group
consisting of PBS, PBSA and PBAT, as a second resin, may be
included in an amount of 10 to 500 parts by weight, preferably, 15
to 500 parts by weight and, more preferably, 20 to 500 parts by
weight, in relation to 100 parts by weight of a first resin, i.e.,
poly(lactic acid) (PLA). If a content of the second resin is less
than 10 parts by weight, the resin layer becomes too hard, in turn
causing curling before or after wallpapering. On the other hand, if
the content of the second resin exceeds 500 parts by weight, heat
resistance of the resin layer may be deteriorated causing
difficulties in processing the same.
[0019] Although a ratio of the biodegradable resin to overall resin
components among a resin composition is not particularly limited,
at least 50%, preferably, 70% or more is preferable. When an amount
of the biodegradable resin is increased, degradation becomes rapid
(that is, a degradation rate is high) and shape collapsibility
after degradation is increased.
[0020] Further, a thermally degradable foaming agent to execute
exothermic reaction may include, for example, azo-dicarbonamide,
azo-dicarboxylamide, benzenesulfonyl hydrazide,
dinitrosopentamethylene tetramine, toluenesulfonyl hydrazide,
azo-bis-isobutyronitrile, barium azo-dicarboxylate, bicarbonates
such as sodium bi-carbonate, or the like. These components may be
singly or compatibly used, and included in a ratio of 1 to 50 parts
by weight and, more preferably, 4 to 25 parts by weight, relative
to 100 parts by weight of the resin composition. If an added amount
of such a foaming agent is too small, foaming properties of the
resin composition are reduced. On the contrary, if the amount is
too large, strength and/or heat resistance of a foamed resin layer
tend to decrease.
[0021] With decrease in a particle diameter of the foaming agent, a
thermal degradation rate of the foaming agent rises, thus
increasing bubble size. On the contrary, when the particle diameter
of the foaming agent is increased, thermal degradation decreases,
in turn reducing the bubble size. Therefore, in order to obtain
bubbles having a uniform diameter, an average particle diameter may
range from 3 to 30 .mu.m, more preferably, 5 to 28 .mu.m.
[0022] In the case where a temperature difference between a
degradation temperature of the foaming agent and a melting point of
the biodegradable resin is large, it is preferable to use a
degradation accelerator for the foaming agent. Such a degradation
accelerator is not particularly limited but, however, may include
commonly known compounds, for example; zinc oxide, magnesium oxide,
calcium stearate, glycerin, urea, etc.
[0023] Further, as the eco-friendly plasticizer, citrates such as
triethyl citrate, acetyl triethyl citrate, tributyl citrate, acetyl
tributyl citrate, trioctyl citrate, acetyl trioxyl citrate,
trihexyl citrate, acetyl trihexyl citrate, butyryl trihexyl
citrate, trimethyl citrate, etc., or sugar alcohols may be used in
an amount of 10 to 80 parts by weight, relative to 100 parts by
weight of the resin composition, in order to attain suitable
flexibility and to prevent bleeding of the plasticizer.
[0024] In this regard, the biodegradable resin-containing
composition may further include an antioxidant, a lubricant, an
inorganic filler, etc. as an additive. The antioxidant is purposed
to protect against oxidation occurring during processing or in
final products, and may be used in an amount of 0.5 to 5 parts by
weight, relative to 100 parts by weight of the biodegradable
resin-containing composition.
[0025] Also, the lubricant is used to improve workability and may
be used in an amount of 0.2 to 3 parts by weight, relative to 100
parts by weight of the biodegradable resin-containing
composition.
[0026] Alternatively, the inorganic filler is used to improve
physical properties and may have an average size of 1.0 to 100
.mu.m. In addition, the above filler may be at least one selected
from talc, mica and calcium carbonate, and may be used in an amount
of 30 to 300 parts by weight, relative to 100 parts by weight of
the biodegradable resin-containing composition.
[0027] With regard to the eco-friendly foaming wallpaper, a method
of forming a biodegradable resin layer may include; mixing a resin
composition which includes a biodegradable resin, a thermally
degradable foaming agent and a cross-linking promoter, using any
mixing device such as a single-screw extruder, a twin-screw
extruder, a Banbury mixer, a kneader mixer, a mixing roll, etc., at
a degradation temperature of a thermally degradable foaming agent.
In this case, a melt-mixing temperature is preferably at least
10.degree. C. lower than a degradation initiating temperature of
the foaming agent. If the mixing temperature is too high, the
thermally degradable foaming agent is degraded during mixing, thus
not providing favorable foam. Preferable addition of the
cross-linking promoter may include, for example: adding the
promoter and mixing the same using a Henschel mixer, a Banbury
mixer or a kneader mixer, prior to melt-mixing; introducing the
promoter from a raw material inlet of an extruder; introducing the
promoter from a vent inlet of an extruder having the vent, and so
forth.
[0028] The biodegradable resin mixture obtained by mixing may be
extruded on a T-die through a single-screw extruder or a twin-screw
extruder, and discharged in a sheet form over a wallpaper substrate
sheet, in turn being adhered thereto. During application, applying
a predetermined amount of tension to the supplied substrate sheet
for the wallpaper may maintain even and flat surface conditions,
thereby enabling more effective application. In this regard, a
method of applying tension to the substrate sheet is not
particularly limited, and an apparatus such as an edge point
control (`EPC`) unit may be used.
[0029] Meanwhile, a thickness of the resin layer may range from
0.01 mm to 50 mm, more preferably, from 0.02 mm to 40 mm and, most
preferably, from 0.05 mm to 30 mm. If the thickness of the resin
layer is less than 0.01 mm, gas leakage from the surface of the
resin layer in expansion molding is significant and causes
difficulties in forming uniform foam. On the contrary, if the
thickness exceeds 50 mm, the resin layer exhibits high rigidity
and, occasionally, may adversely influence winding properties in
continuous manufacture.
[0030] By extruding such a resin layer via T-die processing to
manufacture a product as described, an alternative adhesive for
adhering the resin layer to the resin applied to the surface of the
substrate is not needed and uniform difference in thickness and
planarity may be obtained, thus being preferable.
[0031] Next, a print layer may be provide on the resin layer and,
using the chemical foaming agent described above, chemical foaming
may be executed to form unevenness, so as to improve surface
planarity and allow easy embossing, thus being preferable. In this
case, an embossing patterned layer may be further provided above
the print layer since the print layer has flexibility. As a result,
an eco-friendly foaming sheet may be fabricated.
[0032] Here, a method of forming the embossing patterned layer is
not particularly limited but may include, for example: rolling the
print layer using a patterned roller; or, after adding a foaming
agent to the print layer, foaming and gelling according to
conventional methods.
[0033] The foregoing embossing method is not particularly limited
but may be any conventional method including, for example, a
rolling process using an embossing patterned roll.
[0034] In the case where a roll is used to form embossing patterns,
the roll may be a press roller or a steel roller. Uniformly
controlling pressure in right and left sides of the roller during
rolling may be important to minimize deviation (or difference) in
right and left thicknesses of a product, however, the present
invention is not particularly restricted thereto.
[0035] Briefly, a method for fabrication of an eco-friendly foaming
sheet having the structure described above may include: first,
applying a resin composition containing a biodegradable resin to a
substrate sheet as a subject to be used, to form a resin layer;
then, providing a print layer thereon; and foaming the prepared
sheet, thereby fabricating the eco-friendly foaming sheet.
[0036] As described above, the resin composition containing the
biodegradable resin may comprise a biodegradable resin, a chemical
foaming agent and an eco-friendly plasticizer.
[0037] Additionally, the resin layer may be applied in a T-die mode
and a method for forming a print layer is not particularly limited.
For instance, the printing layer may be formed by any conventional
printing method such as gravure printing, transfer printing,
digital printing or rotary printing.
[0038] According to the present invention, foaming may be performed
by chemical foaming and, more particularly, exothermic reaction
occurs using a chemical foaming agent at a foaming temperature of
120 to 250.degree. C., to form foam cells having a foaming ratio of
100 to 200% while generating nitrogen, carbon dioxide, etc.,
thereby attaining flexibility. Moreover, the foaming resin layer of
the present invention may have an average bubble diameter of more
than 50 .mu.m.
[0039] Meanwhile, with regard to foaming, the foaming method may
include use of CO.sub.2, foaming using UV irradiation, a foaming
method wherein a foaming agent is added to a resin, followed by
gelling the resin, or the like. In the present invention,
considering workability of the print layer and heat resistance of a
wallpaper, chemical foaming is preferably used.
Advantageous Effects of Invention
[0040] According to the present invention described above, without
processes of preparing a sheet and foaming using a biodegradable
resin, the biodegradable resin layer is directly applied to a
substrate sheet as a subject to be used and foamed while forming a
print layer, in addition, a chemical foaming agent and an
eco-friendly plasticizer used together with the biodegradable resin
are specifically defined to ensure desired flexibility, thereby
fabricating an eco-friendly foaming sheet with high
productivity.
BEST MODE FOR CARRYING OUT THE INVENTION
[0041] Preferred embodiments of the present invention will be
described in detail with reference to the following examples,
however, the scope of which the present invention is not
particularly limited to such examples.
Mode for the Invention
Example 1
[0042] 4 parts by weight of azo-dicaroboxylamide as a foaming
agent, 2 parts by weight of methacryl as a cross-linking promoter,
10 parts by weight of citrate, i.e., acetyltributyl citrate (ATBC)
as an eco-friendly plasticizer, 100 parts by weight of an organic
filler (Talc) and 2 parts by weight of a cross-linking promoter,
relative to 100 parts by weight of polylactic acid (PLA) were mixed
using a mixer to prepare a composition, and the composition was
applied to a substrate sheet for a wallpaper having an average
weight of 100 g/m.sup.2 by T-die extrusion to form a resin layer,
thus preparing an eco-friendly foaming sheet.
[0043] Next, a print layer was formed on the eco-friendly foaming
sheet using PLA resin through gravure printing, followed by foaming
in an oven and forming an embossed layer using an embossing roll,
thereby fabricating a biodegradable wallpaper having workability
and heat resistance.
Comparative Example 1
[0044] Using a composition including; 100 parts by weight of a
composite resin containing poly(lactic acid) (PLA) and poybutylene
adipate/terephthalate copolymer (PBAT) (ratio by weight;
PLA:PBAT=9:1), 10 parts by weight of nano-mineral, and other
additives such as a stabilizer, a resin layer was prepared by T-die
extrusion. Then, the prepared resin layer was combined with a
substrate sheet for a wallpaper having an average weight of 100
g/m.sup.2, using an adhesive, thus forming an eco-friendly foaming
sheet.
[0045] Next, a print layer was formed on the eco-friendly foaming
sheet using PLA resin through gravure printing, followed by forming
an embossed layer using an embossing roll while pre-heating,
thereby fabricating a biodegradable wallpaper having workability
and heat resistance.
Comparative Example 2
[0046] The same experiment as described in Example 1 was repeated
except that a resin layer was not foamed.
Example 2
[0047] The same experiment as described in Example 1 was repeated
to prepare an eco-friendly foaming sheet and fabricate a
biodegradable wallpaper except that a composite resin comprising
poly(lactic acid) (PLA) and polybutylene adipate/terephthalate
copolymer (PBAT) in a relative ratio by weight of 7:3 (PLA:PBAT)
was used.
[0048] Items for Measurement of Physical Properties
[0049] Stiffness (assessment of flexibility): after preparing a
specimen having a size of 100.times.600 mm, the specimen was bent
to allow both ends thereof to contact each other. Here, splitting
or bending extent of the specimen was measured.
[0050] Excellent .circleincircle.--smoothly bent without
splitting
[0051] Moderate .largecircle.--forcibly bent without splitting
[0052] Poor x--splitting of the resin layer at a bent site
[0053] Lamination: when a sheet and a paper are detached (or
delaminated) from each other, interlayer adhesion was measured
based on attachment extent of the paper to the sheet.
[0054] Excellent .circleincircle.--delamination between a paper and
another paper.
[0055] Moderate .largecircle.--partial delamination between a sheet
and a paper.
[0056] Poor x--delamination between a sheet and a paper.
[0057] Embossing property: depth of roll emboss and restoration
thereof were measured.
[0058] Embossing .circleincircle.--possible emboss depth of up to
0.8 mm without restoration.
[0059] Embossing .largecircle.--possible emboss depth of up to 0.5
mm with partial restoration.
[0060] Embossing x--almost restored after embossing.
[0061] Heat resistance: after clearly cutting a foamed resin layer
to an angle of 15 cm, the cut piece was left in an oven at
80.degree. C. for 60 minutes. After 60 minutes, the test piece was
removed from the oven and cooled to room temperature for about 30
to 60 minutes. Dimensions of the obtained sample were measured and
a variation in dimensions was calculated as a percentage by an
equation below. Afterwards, results thereof were assessed according
to the following determination standards.
[0062] Heat resistance .circleincircle.--variation in dimensions
within 3%.
[0063] Heat resistance .largecircle.--variation in dimensions
within 5%.
[0064] Heat resistance x--variation in dimensions exceeding 5%.
Variation in heating dimension (%)=[a length of a sample before
placing it in an oven a length of the sample after taking the same
out of the oven/the length of the sample before placing it in the
oven].times.100
[0065] Foaming ratio: By observing a cross-section of a product
using a microscope, thicknesses before and after foaming were
measured, respectively.
[0066] Foaming ratio .circleincircle.--the thickness after foaming
is 200% or more, compared to the thickness before foaming.
[0067] Foaming ratio .largecircle.--the thickness after foaming
ranges from 100 to 200%, compared to the thickness before
foaming.
[0068] Foaming ratio x--the thickness is not varied after
foaming.
Variation in heating dimension (%)=[a length of a sample before
placing it in an oven a length of the sample after taking the same
out of the oven/the length of the sample before placing it in the
oven].times.100
[0069] Average bubble diameter: By observing a cross-section of a
product using a microscope, bubble diameter was measured.
[0070] Average bubble diameter .circleincircle.--50 .mu.m or
more
[0071] Average bubble diameter .largecircle.--30 to 50 .mu.m
[0072] Average bubble diameter x--less than 30 .mu.m
TABLE-US-00001 TABLE 1 Comparative Comparative Items Example 1
Example 2 Example 1 Example 2 Stiffness .circleincircle.
.largecircle. X .circleincircle. Lamination .circleincircle.
.largecircle. X .circleincircle. Embossing .circleincircle.
.largecircle. .largecircle. .largecircle. properties Heat
resistance .largecircle. .largecircle. X .largecircle. Foaming
ratio .largecircle. .largecircle. .largecircle. X Average bubble
.circleincircle. .largecircle. .largecircle. X diameter
[0073] As shown in TABLE 1, it can be seen that the inventive
examples 1 and 2 exhibit flexibility ensured while foaming.
However, comparative examples 1 and 2 demonstrate deteriorated
flexibility and surface fracture in the embossing process.
[0074] Although a few exemplary and preferred embodiments of the
present invention have been shown and described, it would be
appreciated by those skilled in the art that various changes and
modifications may be made in these embodiments without departing
from the principles and spirit of the invention, the scope of which
is defined in the claims and their equivalents.
* * * * *