U.S. patent application number 15/557490 was filed with the patent office on 2018-03-01 for self-adsorbing foam sheet.
This patent application is currently assigned to ZEON CORPORATION. The applicant listed for this patent is ZEON CORPORATION. Invention is credited to Shinsuke ASHIDA, Atsushi SONE.
Application Number | 20180056625 15/557490 |
Document ID | / |
Family ID | 56920223 |
Filed Date | 2018-03-01 |
United States Patent
Application |
20180056625 |
Kind Code |
A1 |
ASHIDA; Shinsuke ; et
al. |
March 1, 2018 |
SELF-ADSORBING FOAM SHEET
Abstract
Provided is a self-adsorbing foam sheet and a self-adsorbing
laminated foam sheet which form almost no formaldehyde, have proper
self adsorption strengths, and are excellent in smoothness; the
self-adsorbing foam sheet being produced by the process comprising
shaping foam that is obtained by foaming a resin composition for a
self-adsorbing foam sheet, the resin composition comprising 100
parts by mass of a (meth)acrylic acid ester copolymer resin which
includes an N-methylol group and whose glass transition temperature
is -10.degree. C. or less, and 1 to 20 parts by mass of a
carbodiimide crosslinking agent, into a sheet, and after said
shaping, carrying out crosslinking reaction on the (meth)acrylic
acid ester copolymer resin; the self-adsorbing laminated foam sheet
comprising an adsorbing layer consisting of the self-adsorbing foam
sheet, and a supporting layer consisting of a base material.
Inventors: |
ASHIDA; Shinsuke;
(Chiyoda-ku, Tokyo, JP) ; SONE; Atsushi;
(Chiyoda-ku, Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ZEON CORPORATION |
Chiyoda-ku, Tokyo |
|
JP |
|
|
Assignee: |
ZEON CORPORATION
Chiyoda-ku, Tokyo
JP
|
Family ID: |
56920223 |
Appl. No.: |
15/557490 |
Filed: |
January 7, 2016 |
PCT Filed: |
January 7, 2016 |
PCT NO: |
PCT/JP2016/050314 |
371 Date: |
September 12, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08J 3/24 20130101; C08K
5/29 20130101; C08J 9/30 20130101; B32B 27/30 20130101; C08L 33/04
20130101; B32B 2307/50 20130101; C09J 7/10 20180101; C09J 11/06
20130101; C08F 220/18 20130101; C09J 7/20 20180101; C08J 2201/026
20130101; C08J 2203/22 20130101; B32B 5/18 20130101; C08J 9/0028
20130101; C09J 133/04 20130101; C08J 9/32 20130101; C08J 2333/08
20130101 |
International
Class: |
B32B 5/18 20060101
B32B005/18; B32B 27/30 20060101 B32B027/30; C08J 3/24 20060101
C08J003/24; C08J 9/30 20060101 C08J009/30 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 17, 2015 |
JP |
2015-052998 |
Claims
1. A resin composition for a self-adsorbing foam sheet, the resin
composition comprising: 100 parts by mass of a (meth)acrylic acid
ester copolymer resin which includes an N-methylol group, and whose
glass transition temperature is -10.degree. C. or less; and 1 to 20
parts by mass of a carbodiimide crosslinking agent.
2. The resin composition according to claim 1, wherein gel fraction
of the (meth)acrylic acid ester copolymer resin is 70% or less.
3. A self-adsorbing foam sheet produced by the process comprising:
shaping foam that is obtained by foaming the resin composition
according to claim 1, into a sheet; and after said shaping,
carrying out crosslinking reaction on the (meth)acrylic acid ester
copolymer resin.
4. A self-adsorbing laminated foam sheet comprising: an adsorbing
layer consisting of the self-adsorbing foam sheet according to
claim 3; and a supporting layer consisting of a base material.
5. The self-adsorbing laminated foam sheet according to claim 4,
wherein the base material is a resin film.
6. A method for producing a self-adsorbing foam sheet, the method
comprising: making a resin composition for a self-adsorbing foam
sheet, the resin composition including: 100 parts by mass of a
(meth)acrylic acid ester copolymer resin which includes an
N-methylol group, and whose glass transition temperature is
-10.degree. C. or less; and 1 to 20 parts by mass of a carbodiimide
crosslinking agent; foaming the resin composition, to obtain foam
of the resin composition; and shaping the foam into a sheet and
after that, carrying out crosslinking reaction on the (meth)acrylic
acid ester copolymer resin.
7. The method according to claim 6, wherein gel fraction of the
(meth)acrylic acid ester copolymer resin is 70% or less.
8. A method for producing a self-adsorbing laminated foam sheet
that includes an adsorbing layer consisting of a self-adsorbing
foam sheet and a supporting layer consisting of a base material,
the method comprising: making a resin composition for a
self-adsorbing foam sheet, the resin composition including: 100
parts by mass of a (meth)acrylic acid ester copolymer resin which
includes an N-methylol group, and whose glass transition
temperature is -10.degree. C. or less; and 1 to 20 parts by mass of
a carbodiimide crosslinking agent; foaming the resin composition,
to obtain foam of the resin composition; and shaping the foam into
a sheet on the base material, and after that, carrying out
crosslinking reaction on the (meth)acrylic acid ester copolymer
resin, to laminate the adsorbing layer to the supporting layer.
9. The method according to claim 8, wherein gel fraction of the
(meth)acrylic acid ester copolymer resin is 70% or less.
10. The method according to claim 9, wherein the base material is a
resin film.
Description
TECHNICAL FIELD
[0001] The present invention relates to self-adsorbing foam sheets
and self-adsorbing laminated foam sheets, methods for producing the
same, and resin compositions used for obtaining the same.
BACKGROUND ART
[0002] In recent years, self-adsorbing sheet members that are
constituted by a foam material having a plurality of microcavities
(hereinafter referred to as "self-adsorbing foam sheets") are
utilized as adsorbing sheets that are used by being stuck to smooth
adsorbed matters such as window glass. Because not pasted but
adsorbing to adsorbed matters using microcavities, self-adsorbing
foam sheets are easy to be restuck without any remaining glue, and
are preferably employed in various uses for building decoration
material represented by interior decorative materials such as
wallpaper, sticking materials for advertising such as posters and
stickers, etc. Generally, base materials such as resin films are
laminated to self-adsorbing foam sheets in order to employ the
sheets in these uses, and these base materials are decorated by
printing, etc. Hereinafter laminated sheets having adsorbing layers
consisting of self-adsorbing foam sheets, and supporting layers
constituted by base materials will be referred to as
"self-adsorbing laminated foam sheet".
[0003] Conventionally, resin is used for a foam material composing
self-adsorbing foam sheets. Especially, acrylic acid ester
copolymers are preferably used in view of being excellent in
various mechanical strengths and weatherability. However, acrylic
acid ester copolymers including N-methylol groups are often used
especially for the purpose of improving strength in wetting, and a
melamine crosslinking agent is often used together for the purpose
of further improving strength. In a case where acrylic acid ester
copolymers including N-methylol groups are used together with a
melamine crosslinking agent, formaldehyde is formed a lot in
crosslinking, and remains in self-adsorbing foam sheets as well,
which causes the appearance of formaldehyde when self-adsorbing
foam sheets or self-adsorbing laminated foam sheet are used.
Formaldehyde is known as a causative agent of what is called sick
house syndromes, and the amount of emission thereof is strongly
demanded to be reduced by setting environmental standards, etc.
Therefore, it is problematic to use self-adsorbing foam sheets or
self-adsorbing laminated foam sheet as described above for
wallpaper and the like.
[0004] As a technique of reducing the amount of formaldehyde
emitted from self-adsorbing foam sheets, for example, Patent
Literature 1 discloses making a self-adsorption foamed sheet which
does not generate at all or hardly generates formaldehyde, using a
resin composition constituted by containing a (meth)acrylate
copolymer resin not containing an N-methylol group in the molecule,
but containing an oxazoline crosslinking agent.
CITATION LIST
Patent Literature
[0005] Patent Literature 1: JP 2006-176693A
SUMMARY OF INVENTION
Technical Problem
[0006] In Patent Literature 1, however, the gel fraction of the
(meth)acrylate copolymer resin has to be increased in order to
obtain a proper self adsorption strength because the (meth)acrylate
copolymer resin containing a carboxyl group is used instead of the
(meth)acrylate copolymer resin containing an N-methylol group that
is conventionally used. As a result, the smoothness of the
self-adsorbing foam sheet is sometimes lacked, and both an self
adsorption strength and smoothness of the sheet are hard to be
compatible.
[0007] An object of the present invention is to provide a
self-adsorbing foam sheet and a self-adsorbing laminated foam sheet
which form almost no formaldehyde, have proper self adsorption
strengths, and are excellent in smoothness; methods for producing
the same; and a resin compound used for obtaining the same.
Solution to Problem
[0008] As a result of inventors' deliberate research in view of the
above described problems, they found that properties demanded above
can be achieved by combining a predetermined (meth)acrylic acid
ester copolymer resin and a carbodiimide crosslinking agent.
[0009] That is, a first aspect of the present invention is a resin
composition for a self-adsorbing foam sheet, the resin composition
comprising: 100 parts by mass of a (meth)acrylic acid ester
copolymer resin which includes an N-methylol group, and whose glass
transition temperature is -10.degree. C. or less; and 1 to 20 parts
by mass of a carbodiimide crosslinking agent.
[0010] In this description, "(meth)acrylic" means "acrylic and/or
methacrylic".
[0011] A second aspect of the present invention is a self-adsorbing
foam sheet produced by the process comprising: shaping foam that is
obtained by foaming the resin composition according to the above
first aspect of the present invention, into a sheet; and after said
shaping, carrying out crosslinking reaction on the (meth)acrylic
acid ester copolymer resin.
[0012] A third aspect of the present invention is a self-adsorbing
laminated foam sheet comprising: an adsorbing layer consisting of
the self-adsorbing foam sheet according to the above second aspect
of the present invention; and a supporting layer consisting of a
base material.
[0013] A fourth aspect of the present invention is a method for
producing a self-adsorbing foam sheet, the method comprising:
making a resin composition for a self-adsorbing foam sheet, the
resin composition including: 100 parts by mass of a (meth)acrylic
acid ester copolymer resin which includes an N-methylol group, and
whose glass transition temperature is -10.degree. C. or less; and 1
to 20 parts by mass of a carbodiimide crosslinking agent; foaming
the resin composition, to obtain foam of the resin composition; and
shaping the foam into a sheet and after that, carrying out
crosslinking reaction on the (meth)acrylic acid ester copolymer
resin.
[0014] A fifth aspect of the present invention is a method for
producing a self-adsorbing laminated foam sheet that includes an
adsorbing layer consisting of a self-adsorbing foam sheet and a
supporting layer consisting of a base material, the method
comprising: making a resin composition for a self-adsorbing foam
sheet, the resin composition including: 100 parts by mass of a
(meth)acrylic acid ester copolymer resin which includes an
N-methylol group, and whose glass transition temperature is
-10.degree. C. or less; and 1 to 20 parts by mass of a carbodiimide
crosslinking agent; foaming the resin composition, to obtain foam
of the resin composition; and shaping the foam into a sheet on the
base material, and after that, carrying out crosslinking reaction
on the (meth)acrylic acid ester copolymer resin, to laminate the
adsorbing layer to the supporting layer.
[0015] In the first, fourth and fifth aspects of the present
invention, preferably, gel fraction of the (meth)acrylic acid ester
copolymer resin is 70% or less.
[0016] In the third and fifth aspects of the present invention,
preferably, the base material is a resin film.
Advantageous Effects of Invention
[0017] The present invention can provide a self-adsorbing foam
sheet and a self-adsorbing laminated foam sheet which form almost
no formaldehyde, have proper self adsorption strengths, and are
excellent in smoothness; methods for producing the same; and a
resin compound used for obtaining the same.
BRIEF DESCRIPTION OF DRAWINGS
[0018] FIG. 1 is an exemplary flowchart of one embodiment of the
method for producing a self-adsorbing foam sheet according to the
present invention.
DESCRIPTION OF EMBODIMENTS
[0019] Hereinafter, embodiments of the present invention will be
described. The embodiments described below are exemplifications of
the present invention, and the present invention is not limited
thereto. In the present invention, the term "film" includes "sheet"
and the term "sheet" includes "film" as well.
[0020] 1. Resin Composition for Self-Adsorbing Foam Sheet
[0021] The resin composition for a self-adsorbing foam sheet of the
present invention includes 100 parts by mass of a (meth)acrylic
acid ester copolymer resin which includes an N-methylol group and
whose glass transition temperature is -10.degree. C. or less, and 1
to 20 parts by mass of a carbodiimide crosslinking agent.
[0022] <(Meth)Acrylic Acid Ester Copolymer Resin>
[0023] Hereinafter, the (meth)acrylic acid ester copolymer resin
used in the present invention will be described. The (meth)acrylic
acid ester copolymer resin includes an N-methylol group, and glass
transition temperature thereof is -10.degree. C. or less.
[0024] The glass transition temperature of the (meth)acrylic acid
ester copolymer resin is -10.degree. C. or less, and preferably
-13.degree. C. or less. The glass transition temperature of the
(meth)acrylic acid ester copolymer resin is the above described
upper limit or less, so that the gel fraction of the (meth)acrylic
acid ester copolymer resin described below easily becomes a
predetermined upper limit or less. As a result, it is easy to make
a self-adsorbing foam sheet and a self-adsorbing laminated foam
sheet having proper self adsorption strengths and excellent
smoothness. While not specifically provided, the lower limit is
preferably -40.degree. C. or more.
[0025] The (meth)acrylic acid ester copolymer resin consists of no
less than 50% by mass of monomeric units derived from (meth)acrylic
acid ester monomers and no more than 50% by mass of monomeric units
derived from monomers copolymerizable with the (meth)acrylic acid
ester monomers; preferably, no less than 70% by mass of monomeric
units derived from (meth)acrylic acid ester monomers and no more
than 30% by mass of monomeric units derived from monomers
copolymerizable with the (meth)acrylic acid ester monomers; more
preferably, no less than 80% by mass of monomeric units derived
from (meth)acrylic acid ester monomers and no more than 20% by mass
of monomeric units derived from monomers copolymerizable with the
(meth)acrylic acid ester monomers; and further preferably, no less
than 85% by mass of monomeric units derived from (meth)acrylic acid
ester monomers and no more than 15% by mass of monomeric units
derived from monomers copolymerizable with the (meth)acrylic acid
ester monomers. The content of monomeric units derived from
(meth)acrylic acid ester monomers within the above described range
makes it possible for the resin to acquire a proper adhesive
property.
[0026] In the present invention, an N-methylol group that the
(meth)acrylic acid ester copolymer resin includes is included in a
monomeric unit copolymerizable with (meth)acrylic acid ester
monomers, and may be included in a monomeric unit of (meth)acrylic
acid ester as well.
[0027] (Meth)acrylic acid ester monomers applicable to the present
invention are not limited, and preferably, units of (meth)acrylic
acid ester monomers composing homopolymers of -20.degree. C. or
below in glass transition temperature are contained in view of
easily making the glass transition temperature of the (meth)acrylic
acid ester copolymer resin -10.degree. C. or below.
[0028] Non-limiting examples of the above described (meth)acrylic
acid ester monomers composing homopolymers of -20.degree. C. or
below in glass transition temperature include alkyl (meth)acrylates
composing homopolymers of -20.degree. C. or below in glass
transition temperature such as: ethyl acrylate (homopolymers
therefrom are -24.degree. C. in glass transition temperature.
Hereinafter the same will be indicated in parentheses), n-propyl
acrylate (-37.degree. C.), n-butyl acrylate (-54.degree. C.),
sec-butyl acrylate (-22.degree. C.), n-heptyl acrylate (-60.degree.
C.), n-hexyl acrylate (-61.degree. C.), n-octyl acrylate
(-65.degree. C.), 2-ethylhexyl acrylate (-50.degree. C.), n-octyl
methacrylate (-25.degree. C.), n-decyl methacrylate (-49.degree.
C.), and alkoxyalkyl (meth)acrylates composing homopolymers of
-20.degree. C. or below in glass transition temperature such as:
2-methoxyethyl acrylate (-50.degree. C.), 3-methoxypropyl acrylate
(-75.degree. C.), 3-methoxybutyl acrylate (-56.degree. C.), and
ethoxymethyl acrylate (-50.degree. C.). Among them, alkyl
(meth)acrylates composing homopolymers of -20.degree. C. or below
in glass transition temperature and alkoxyalkyl (meth)acrylates
composing homopolymers of -20.degree. C. or below in glass
transition temperature are preferable, and alkyl (meth)acrylates
composing homopolymers of -20.degree. C. or below in glass
transition temperature are more preferable.
[0029] If glass transition temperature of the (meth)acrylic acid
ester copolymer resin can be regulated to -10.degree. C. or below,
methyl acrylate (homopolymers are 10.degree. C. in glass transition
temperature. Hereinafter the same will be indicated in
parentheses), methyl methacrylate (105.degree. C.), ethyl
methacrylate (63.degree. C.), n-propyl methacrylate (25.degree.
C.), n-butyl methacrylate (20.degree. C.) or the like may be
used.
[0030] Only one kind of the above described (meth)acrylic acid
ester monomers may be used. Alternatively, two or more kinds
thereof may be used together.
[0031] It is necessary to use a monomer including an N-methylol
group such as N-methylolacrylamide and N-methylolmethacrylamide as
each monomer copolymerizable with (meth)acrylic acid ester monomers
(hereinafter referred to as "a monomer for copolymerization"). Use
of a monomer including an N-methylol group easily makes the gel
fraction, which will be described later, a predetermined upper
limit or below, and as a result, makes it easy to produce the
self-adsorbing foam sheet and the self-adsorbing laminated foam
sheet having proper self adsorption strengths, and excellent
smoothness. In the above described view, the proportion of the use
of monomers including N-methylol groups is as follows: monomeric
units derived from monomers including N-methylol groups are
preferably 0.1% to 10% by mass, and more preferably 0.5% to 5% by
mass when the (meth)acrylic acid ester copolymer resin is 100% by
mass.
[0032] In addition to the above described monomer including an
N-methylol group, another kind of a monomer may be used together as
a monomer for copolymerization. Such another kind of a monomer is
not limited as allowing glass transition temperature of the
(meth)acrylic acid ester copolymer resin to be -10.degree. C. or
below. Specific examples thereof include
.alpha.,.beta.-ethylenically unsaturated polyvalent carboxylic acid
complete esters, alkenyl aromatic monomers, vinyl cyanide monomers,
esters of carboxylic acids and unsaturated alcohols, olefinic
monomers, and other monomers including functional groups. Only one
kind of these monomers may be used, or two or more kinds thereof
may be used together.
[0033] Specific examples of .alpha.,.beta.-ethylenically
unsaturated polyvalent carboxylic acid complete esters include
dimethyl fumarate, diethyl fumarate, dimethyl maleate, diethyl
maleate, and dimethyl itaconate.
[0034] Specific examples of alkenyl aromatic monomers include
styrene, .alpha.-methylstyrene, methyl .alpha.-methylstyrene, and
vinyltoluene.
[0035] Specific examples of vinyl cyanide monomers include
acrylonitrile, methacrylonitrile, .alpha.-chloroacrylonitrile, and
.alpha.-ethylacrylonitrile.
[0036] Specific examples of esters of carboxylic acids and
unsaturated alcohols include vinyl acetate.
[0037] Specific examples of olefinic monomers include ethylene,
propylene, butene, and pentene.
[0038] Monomers including functional groups may be used as monomers
for copolymerization for the purpose of efficient crosslinking
inside or between copolymers.
[0039] Examples of a functional group mentioned herein include an
organic acid group, a hydroxyl group, an amino group, an amide
group, a mercapto group, and an epoxy group.
[0040] Monomers including organic acid groups are not limited, and
representative examples thereof include monomers including organic
acid groups such as carboxyl groups, acid anhydride groups, and
sulfonic acid groups. Other than them, monomers containing sulfenic
acid groups, sulfinic acid groups, and phosphoric acid groups can
be used as well.
[0041] Specific examples of monomer including carboxyl groups
include .alpha.,.beta.-ethylenically unsaturated monocarboxylic
acids such as acrylic acid, methacrylic acid, and crotonic acid;
.alpha.,.beta.-ethylenically unsaturated polyvalent carboxylic
acids such as itaconic acid, maleic acid, and fumaric acid; and in
addition, .alpha.,.beta.-ethylenically unsaturated polyvalent
carboxylic acid partial esters such as monomethyl itaconate,
monobutyl maleate, and monopropyl fumarate. Monomer including
groups from which carboxyl groups can be derived by hydrolysis
etc., such as maleic anhydride, and itaconic anhydride, can be used
as well.
[0042] Specific examples of monomers including sulfonic acid groups
include .alpha.,.beta.-unsaturated sulfonic acids such as
allylsulfonic acid, methallylsulfonic acid, vinylsulfonic acid,
styrenesulfonic acid, and acrylamido-2-methylpropane sulfonic acid;
and salts thereof.
[0043] In a case where monomers including organic acid groups are
used, these monomers are subjected to polymerization so that the
amount of monomeric units derived therefrom is preferably 0.1% to
20% by mass, and more preferably 0.5% to 15% by mass when the
(meth)acrylic acid ester copolymer resin is 100% by mass. The
amount of the use of the monomers including organic acid groups
within the above described range makes it easy to keep the
viscosity of polymerization systems in polymerization within a
proper range, and to prevent self-adsorption of the self-adsorbing
foam sheet and the self-adsorbing laminated foam sheet from being
lost due to excessive progress of crosslinking of copolymers.
[0044] Monomeric units including organic acid groups are easy and
preferable to be introduced into the (meth)acrylic acid ester
copolymer resin according to polymerization of monomers including
organic acid groups. Organic acid groups may be introduced
according to a known polymer reaction after the (meth)acrylic acid
ester copolymer resin is made.
[0045] Examples of monomers including hydroxyl groups include
hydroxy alkyl(meth)acrylic acid esters such as 2-hydroxyethyl
(meth)acrylate, and 3-hydroxypropyl (meth)acrylate.
[0046] Examples of monomers including amino groups include
N,N-dimethylaminomethyl (meth)acrylate, N,N-dimethylaminoethyl
(meth)acrylate, and aminostyrene.
[0047] Examples of monomers including amide groups include
.alpha.,.beta.-ethylenically unsaturated carboxylic acid amide
monomers such as acrylamide, methacrylamide, and N,N-dimethyl
acrylamide.
[0048] Examples of monomers including epoxy groups include
glycidyl(meth)acrylate, and allyl glycidyl ether.
[0049] In a case where these monomers including functional groups
other than organic acid groups are used, these monomers are
preferably used for polymerization so that the amount of monomeric
units derived therefrom is no more than 10% by mass when the
(meth)acrylic acid ester copolymer resin is 100%/o by mass. The
amount of the use of monomers including functional groups other
than organic acid groups is no more than 10% by mass, so that the
viscosity of polymerization systems in polymerization can be easily
kept within a proper range, and a self-adsorbing property of the
self-adsorbing foam sheet and the self-adsorbing laminated foam
sheet can be easily prevented from being lost due to excessive
progress of crosslinking of copolymers.
[0050] A polyfunctional monomer having a plurality of polymerizable
unsaturated bonds may be used together as a monomer for
copolymerization. An unsaturated bond-terminated polyfunctional
monomer is preferable. Using such a polyfunctional monomer makes it
possible to introduce intramolecular and/or intermolecular
crosslinking into the (meth)acrylic acid ester copolymer resin, to
improve a cohesive force.
[0051] Examples of the above described polyfunctional monomer
include polyfunctional (meth)acrylates such as: 1,6-hexanediol
di(meth)acrylate, 1,2-ethylene glycol di(meth)acrylate,
1,12-dodecanediol di(meth)acrylate, polyethylene glycol
di(meth)acrylate, polypropyleneglycol di(meth)acrylate,
neopentylglycol di(meth)acrylate, pentaerythritol di(meth)acrylate,
trimethylolpropane tri(meth)acrylate, pentaerythritol
tri(meth)acrylate, ditrimethylolpropane tri(meth)acrylate,
pentaerythritol tetra(meth)acrylate, and dipentaerythritol
hexa(meth)acrylate; substituted triazines such as
2,4-bis(trichloromethyl)-6-p-methoxystyrene-5-triazine; and in
addition, mono-ethylenically unsaturated aromatic ketones such as
4-acryloxybenzophenone. Polyfunctional (meth)acrylates are
preferable, and pentaerythritol di(meth)acrylate, pentaerythritol
tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate are more
preferable. Only one kind of these polyfunctional monomers may be
used, or two or more kinds thereof may be used together.
[0052] The (meth)acrylic acid ester copolymer resin can be obtained
by copolymerization of (meth)acrylic acid ester monomers and
monomers for copolymerization. Any of polymerization methods such
as solution polymerization, emulsion polymerization, suspension
polymerization, bulk polymerization, and any other methods may be
used when the (meth)acrylic acid ester copolymer resin is obtained.
Types and amounts of a polymerization initiator, an emulsifying
agent, a dispersing agent and the like that are used for
polymerization are not limited as well. A method of adding
monomers, a polymerization initiator, an emulsifying agent, a
dispersing agent and the like upon polymerization are not limited
as well. Also, there is no limitation on polymerization
temperature, pressure, stirring conditions and the like.
[0053] The (meth)acrylic acid ester copolymer resin may be either
solid or a dispersion. If an emulsion or dispersion obtained from
emulsion polymerization or dispersion polymerization is used as it
is, operation is easy in mixing with a crosslinking agent and
conductive compounds, and it is convenient to foam the obtained
emulsion or dispersion.
[0054] The gel fraction of the (meth)acrylic acid ester copolymer
resin is preferably 70/o or less, and more preferably 65% or less.
The gel fraction within the above range makes it easy to produce
the self-adsorbing foam sheet and the self-adsorbing laminated foam
sheet of proper self adsorption strengths, and excellent
smoothness.
[0055] The gel fraction in the present invention is a value
obtained from the following formula after: in 100 ml of ethyl
acetate, 500 mg of a sample of an acrylic acid ester copolymer
resin is immersed at normal temperature for 3 days; after that
insoluble matters are filtered through woven metal of 200 mesh, and
air-dried at normal temperature for 15 hours; after that the
resulting matters are dried at 100.degree. C. for 2 hours, and a
dry mass of the resulting insoluble content is measured.
Gel fraction (% by mass)=((a dry mass of the insoluble content
after the immersion in ethyl acetate)/(a mass of the sample before
the immersion in ethyl acetate)).times.100
[0056] <Carbodiimide Crosslinking Agent>
[0057] The carbodiimide crosslinking agent used in the present
invention is not restricted. A compound where two or more
carbodiimide groups are included in one molecule is preferably
used. A known carbodiimide compound can be used as such a
compound.
[0058] Either synthesized or commercially available carbodiimide
compound may be used as a known carbodiimide compound described
above. Examples of a commercially available carbodiimide compound
include "DICNAL HX" from DIC Corporation, and "CARBODILITE" from
Nisshinbo Chemical Inc. When a carbodiimide compound is
synthesized, for example, a polycarbodiimide compound that is a
carbodiimidized polyisocyanate by decarboxylative condensation
reaction in the presence of a carbodiimidization catalyst can be
used.
[0059] Examples of a raw material that is a polyisocyanate include
hexamethylene diisocyanate (HDI), hydrogenated xylylene
diisocyanate (H6XDI), xylylene diisocyanate (XDI),
2,2,4-trimethylhexamethylene diisocyanate (TMHDI),
1,12-diisocyanatedecane (DDI), norbornane diisocyanate (NBDI), and
2,4-bis-(8-isocyanateoctyl)-1,3-dioctylcyclobutane (OCDI),
4,4'-dicyclohexylmethane diisocyanate (HMDI), tetramethylxylylene
diisocyanate (TMXDI), isophorone diisocyanate (IPDI),
2,4,6-triisopropylphenyldiisocyanate (TIDI), 4,4'-diphenylmethane
diisocyanate (MDI), tolylene diisocyanate (TDI), and hydrogenated
tolylene diisocyanate (HTDI). A carbodiimide compound can be
synthesized by: stirring and mixing a polyisocyanate within the
range of 0 to 200.degree. C. for any length of time in the presence
of an air flow or bubbling of an inert gas; after that adding the
resultant along with a carbodiimidization catalyst, and stirring
and mixing them.
[0060] Here, preferably, carbodiimidization catalyst described
above is an organophosphorus compound. Specifically, phospholene
oxides are preferable in view of activity. Specific examples
thereof include 3-methyl-1-phenyl-2-phospholene-1-oxide,
3-methyl-1-ethyl-2-phospholene-1-oxide,
1,3-dimethyl-2-phospholene-1-oxide, 1-ethyl-2-phospholene-1-oxide,
I-methyl-2-phospholene-1-oxide and double bond isomers thereof.
[0061] The carbodiimide crosslinking agent forms an intramolecular
or intermolecular crosslinking structure of the (meth)acrylic acid
ester copolymer resin according to reaction of carbodiimide groups
thereof with N-methylol groups in the (meth)acrylic acid ester
copolymer resin. The carbodiimide crosslinking agent is excellent
especially in a crosslinking effect at low temperature. The
carbodiimide crosslinking agent is preferable because being able to
form the self-adsorbing foam sheet excellent in strength and a
self-adsorbing property.
[0062] Both the carbodiimide crosslinking agent and a crosslinking
agent other than the carbodiimide crosslinking agent (examples
thereof include: epoxy resins such as poly(ethylene glycol)
diglycidyl ether, glycerin polyglycidyl ether, sorbitol
polyglycidyl ether, and bisphenol A polyglycidyl ether; aziridines
such as ethylenimine derivatives including aldehyde and acrolein;
multifunctional isocyanate crosslinking agents such as tolylene
diisocyanate, trimethylolpropane tolylene diisocyanate, and
diphenylmethane triisocyanate; oxazoline crosslinking agents; metal
salt-based crosslinking agents; metal chelate-based crosslinking
agents; and peroxide-based crosslinking agents) can be used
together. Preferably, crosslinking agents that cause formaldehyde
to form, such as aldehyde resins including melamine-formaldehyde
resins, urea-formaldehyde resins, and phenolformaldehyde resins are
not used.
[0063] The amount of the use of the carbodiimide crosslinking agent
is preferably 0.5 to 20 parts by mass, and more preferably 2 to 15
parts by mass as a solid, to 100 parts by mass of the (meth)acrylic
acid ester copolymer resin. The amount of the use of the
carbodiimide crosslinking agent is within the above described range
so that the resin is allowed to have a proper self adsorption
strength, and strength of the resin after crosslinking can be
improved.
[0064] (Other Additives)
[0065] The resin composition for a self-adsorbing foam sheet of the
present invention can makes it possible to make the amount of
emission of formaldehyde extremely low without containing any
formaldehyde scavengers. However, this resin composition may
further contain a formaldehyde scavenger.
[0066] A formaldehyde scavenger that can be used for the present
invention is not limited as long as being a compound that
physically adsorbs formaldehyde or that can chemically react with
formaldehyde. This formaldehyde scavenger may be either inorganic
compound or organic compound that includes even polymers.
[0067] Specific examples of a formaldehyde scavenger include
nitrogen-containing compounds such as: hydroxylamine sulfate,
hydroxylamine hydrochloride, ammonium acetate, urea, ethyleneurea,
dicyandiamide, polyamide resins, triazine compounds, and hydrazide
compounds; halogen oxides such as stabilized chlorine dioxide; and
metallic salts such as disodium hydrogen phosphate, zinc sulfate,
calcium chloride, and magnesium sulfate. Among them,
nitrogen-containing compounds are preferable and hydroxylamine
sulfate is more preferable in view of easy availability,
operability and scavenging of formaldehyde. These formaldehyde
scavengers may be used individually or may be used in
combination.
[0068] The resin composition for a self-adsorbing foam sheet of the
present invention may contain various additives if necessary in
order to improve processability in the processes of producing the
self-adsorbing foam sheet and the Self-adsorbing Laminated Foam
Sheet, and to improve properties of the self-adsorbing foam sheet
and self-adsorbing laminated foam sheet to be obtained.
[0069] Examples of additives include foam stabilizers, auxiliary
blowing agents, thickeners, fillers, antiseptics, fungicides,
gelatinizers, flame retardants, anti-aging agents, antioxidants,
pigments, dyes, tackifiers, and conductive compounds.
[0070] As foam stabilizers, the following can be used: ammonium
salts of fatty acids such as ammonium stearate, sulfonic acid-type
anionic surfactants such as alkyl sulfosuccinates, quaternary
alkylammonium chlorides, amphoteric compounds of alkyl betaines,
and alkanolamine salts of fatty acids.
[0071] As auxiliary blowing agents, the following can be used:
sodium lauryl sulfate, sodium alkyl diphenyl ether disulphonate,
and sodium polyoxyethylene alkylphenol ether sulfate.
[0072] As thickeners, the following can be used: acrylic polymer
particles, inorganic compounds particulates such as fine silica
particles, and reactive inorganic compounds such as magnesium
oxide.
[0073] As fillers, the following can be used: calcium carbonate,
magnesium carbonate, aluminum hydroxide, magnesium hydroxide,
barium hydroxide, clay, kaolin, and glass powder.
[0074] Examples of antiseptics and fungicides include dihydroxy
dichlorophenylmethane, sodium pentachlorophenate,
2,3,4,6-tetrachloro-4-(methylsulfonyl)pyridine,
2,3,5,6-tetrachloro-4-(methylsulfonyl)pyridine, bis(tributyltin)
oxide, hexahydro-1,3,5-triethyl-s-triazine, silver complexes, and
zinc complexes.
[0075] As gelatinizers, the following can be used: ammonium salts
such as ammonium acetate, ammonium chloride, and ammonium
carbonate; alkylphenol alkylene oxide addition products,
polyvinylmethyl ether, polypropylene glycol, polyether polyformal,
methylcellulose, hydroxyethyl cellulose, and silicone heat
sensitizers.
[0076] As flame retardants, the following can be used: phosphoric
acid ester compounds, halogen phosphoric acid ester compounds,
ammonium polyphosphate, antimony trioxide, zinc borate, barium
metaborate, ammonium hydroxide, magnesium hydroxide, tin compounds,
organophosphorous compounds, red phosphorus compounds, and silicone
flame retardants.
[0077] Antioxidants based on polyphenol, hydroquinone, hindered
amine, and the like can be used.
[0078] Examples of pigments and dyes include titan oxide, carbon
black, iron oxide red, and quinacridone.
[0079] As tackifiers, any compounds selected from the following can
be used: rosin resins such as gum rosins, tall oil rosins, wood
rosins, hydrogenated rosins, disproportionated rosins, polymerized
rosins, maleated rosins, rosin glycerol esters, and hydrogenated
rosin glycerol esters; terpene based resins such as terpene resins,
terpene phenol resins, and aromatic modified terpene resins;
petroleum resins such as aliphatic petroleum resins, alicyclic
petroleum resins, and aromatic petroleum resins; coumarone-indene
resins; terpene phenol-based resins; phenol resins; hydrogenated
rosin esters; disproportionated rosin esters; and xylene
resins.
[0080] 2. Self-Adsorbing Foam Sheet and Self-Adsorbing Laminated
Foam Sheet
[0081] The self-adsorbing foam sheet of the present invention is
produced by shaping foam that is obtained by foaming the resin
composition of the present invention, into a sheet, and after said
shaping, carrying out crosslinking reaction on the (meth)acrylic
acid ester copolymer resin.
[0082] The self-adsorbing laminated foam sheet of the present
invention has an adsorbing layer consisting of the self-adsorbing
foam sheet of the present invention; and a supporting layer
consisting of a base material.
[0083] Specific examples of the base material used for the
self-adsorbing laminated foam sheet include paper bases, synthetic
paper, and plastic sheets.
[0084] Here, examples of paper bases include woodfree paper, art
paper, coated paper, kraft paper, and laminated paper obtained by
laminating a thermoplastic resin such as polyethylene to paper
bases. Synthetic paper is obtained by combining a thermoplastic
resin with an inorganic filler, to form its outermost layer to be
paper.
[0085] In contrast, examples of plastic sheets include polyester
resins such as polyethylene terephthalate, and polyethylene
naphthalate; polystyrene resins; polyvinyl chloride resins; acrylic
resins; polycarbonate resins; polyamide resins; fluorocarbon
polymers such as polytetrafluoroethylene; and sheets composed of
mixtures or laminates thereof.
[0086] Thickness of the supporting layer consisting of the base
material is not limited. Normally, the thickness thereof is 10
.mu.m to 200 .mu.m.
[0087] If the base material having releasability is employed, the
base material can be released after the adsorbing layer consisting
of the self-adsorbing foam sheet is formed on the base material as
described later, to be used as the self-adsorbing foam sheet.
[0088] 3. Producing Method
[0089] Hereinafter the method for producing the self-adsorbing foam
sheet and the self-adsorbing laminated foam sheet will be
described.
[0090] FIG. 1 is an exemplary flowchart of the self-adsorbing foam
sheet producing method S10 of the present invention (hereinafter
may be abbreviated as "this producing method S10"). As shown in
FIG. 1, this producing method S10 includes a resin composition
making step S1, a foaming step S2 and a sheet forming step S3 in
this order. Hereinafter each step will be described.
[0091] (Resin Composition Making Step S1)
[0092] The resin composition making step S1 is a step of making a
resin composition for a self-adsorbing foam sheet, the resin
composition including: 100 parts by mass of a (meth)acrylic acid
ester copolymer resin which includes an N-methylol group, and whose
glass transition temperature is -10.degree. C. or less; and 1 to 20
parts by mass of a carbodiimide crosslinking agent.
[0093] In the resin composition making step S1, the resin
composition for the self-adsorbing foam sheet can be made by
mixing: (meth)acrylic acid ester copolymer resin including
N-methylol groups, which are essential component, of -10.degree. C.
or below in glass transition temperature; a carbodiimide
crosslinking agent; and other components used if desired, according
to some method. Each substance used in this step, the proportion of
the use thereof, etc. are as described above, and thus the
description thereof is omitted here.
[0094] In case of being an emulsion or a dispersion, the
(meth)acrylic acid ester copolymer resin can be easily mixed with
the carbodiimide crosslinking agent and the other components only
by adding them to the resin in a state of an aqueous dispersion, a
water solution, or the like during stirring.
[0095] In a case where the (meth)acrylic acid ester copolymer resin
is a solid, a way of mixing is not restricted as well. For example,
mixing may be carried out with rolls, Henschel mixers, or kneaders.
Either batch mixing or continuous mixing may be carried out.
[0096] Examples of batch mixers include kneaders and stirrers for
high viscosity materials such as: mortar machines, kneaders,
internal mixers, and planetary mixers. Examples of continuous
mixers include Farrel continuous mixers that are combinations of
rotors and screws, and kneaders of special structures like screw
type kneaders. Single-screw extruders and twin-screw extruders that
are used for extruding are also included. These extruders and
kneaders may be used in combination, or a plurality of machine of
the same type may be coupled to be used.
[0097] A form of the resin composition for a self-adsorbing foam
sheet of the present invention is not limited. The resin
composition in the form of either emulsion or dispersion makes it
convenient to obtain the self-adsorbing foam sheet.
[0098] The viscosity of this emulsion or dispersion is preferably
2000 to 10000 mPas, and more preferably 3500 to 5500 mPas.
[0099] (Foaming Step S2)
[0100] The foaming step S2 is a step of foaming the resin
composition, to obtain foam of the resin composition.
[0101] In the foaming step 2, the resin composition for a
self-adsorbing foam sheet, which is made in the resin composition
making step S1, is foamed, which makes it possible to obtain foam
in an unsolidified state. In a case where the resin composition for
a self-adsorbing foam sheet is in the form of an emulsion or
dispersion, a foamed emulsion or foamed dispersion is obtained.
[0102] Generally, mechanical foaming is employed as a foaming
method. Foaming magnification may be properly adjusted, is
generally 1.2 to 5 times, and is preferably 1.5 to 4 times. A
method of mechanical foaming is not restricted. This mechanical
foaming can be carried out by mixing a certain amount of air with
an emulsion of the resin composition, and stirring the mixture with
a continuous or batch type Oakes mixer, whipper, or the like. A
foamed emulsion obtained according to this way is creamy.
[0103] Instead of the above described mechanical foaming, the
foaming resin composition can be also prepared with, for example,
the method of using a proper synthetic resin such as vinylidene
chloride copolymers as a shell wall, and adding thermally
expandable microcapsules that encompass hydrocarbon compounds of
low boiling points to an acrylic resin emulsion or butadiene
synthetic rubber emulsion.
[0104] (Sheet Forming Step S3)
[0105] The sheet forming step S3 is a step of shaping the foam into
a sheet and after that, carrying out crosslinking reaction on the
(meth)acrylic acid ester copolymer resin.
[0106] In the sheet forming step S3, a method of shaping the foam
into a sheet is not restricted, and preferred examples thereof
include: the method of coating, with the foam, process paper such
as a polyester film on which a releasing process is carried out, to
shape the foam into a sheet.
[0107] The following coating devices, which are generally known,
can be used for a method of coating process paper with the foam:
roll coaters, reverse roll coaters, screen coaters, doctor knife
coaters, comma knife coaters, etc. Specifically, uniform coating
thickness can be obtained using doctor knife coaters.
[0108] The self-adsorbing foam sheet that is made by solidification
of the sheet foam can be formed over process paper by crosslinking
reaction of the (meth)acrylic acid ester copolymer resin after the
foam is shaped into a sheet as described above. At this time, if
process paper having releasability is used, the self-adsorbing foam
sheet can be easily separated from this process paper.
[0109] When the self-adsorbing laminated foam sheet is produced,
the self-adsorbing laminated foam sheet can be formed over the base
material in the sheet forming step S3 by using the above described
base material as process paper, and the self-adsorbing laminated
foam sheet including the adsorbing layer consisting of the
self-adsorbing foam sheet, and the supporting layer consisting of
the base material can be produced.
[0110] In the sheet forming step S3, preferably heating and drying
is carried out when the (meth)acrylic acid ester copolymer resin is
subjected to crosslinking reaction. A method of heating and drying
is not restricted as long as the foamed emulsion with which process
paper is coated can be dried and crosslinked. Ordinary ovens with
hot air circulation, hot air chambers with hot oil circulators, far
infrared ray heater chambers, etc. can be used for this method.
Drying temperature is properly 60.degree. C. to 180.degree. C.
Drying conditions can be properly selected according to the
properties of the emulsion, the coating amount, the coating
thickness, etc. Preferably, multi-stage drying is carried out such
that: drying is carried out from the inside at lower temperature at
the early stage, to the entire at higher temperature at the later
stage, but not carried out at fixed temperature at all the
stages.
[0111] Density, thickness, hardness, etc. of the obtained
self-adsorbing foam sheet are adjusted according to the mixing
ratio of air bubbles, the formation of the resin composition for a
self-adsorbing foam sheet, the solid concentration, conditions of
solidifying by heating and drying, etc. The thickness of the
self-adsorbing foam sheet is preferably 0.03 to 3 mm, more
preferably 0.05 to 1 mm, and especially preferably 0.05 to 0.5 mm.
If the thickness is thinner than 0.03 mm, the impact absorbency is
poor, and retention of items, and functions of protecting surfaces
of items are not enough, in a case where the self-adsorbing foam
sheet of the present invention is used as an item retention
material or an item surface protection material. If the thickness
is thicker than 3 mm, the strength of the self-adsorbing foam sheet
is poor, which is not preferable as well. The density of the
self-adsorbing foam sheet is not restricted, and is preferably 0.1
to 1.0 g/cm.sup.3 in view of impact absorbency.
[0112] The self-adsorbing foam sheet or the self-adsorbing
laminated foam sheet obtained in the sheet forming step S3 is
usually wound by a winder after a separator film is stuck on its
surface having a self-adsorbing property, and cut by press cutting,
with a slitter, etc., to be processed to a usable size.
[0113] 4. Uses
[0114] Examples of printing that is able to be carried out on the
surface of the base material of the self-adsorbing laminated foam
sheet of the present invention include: offset printing, seal
printing, flexographic printing, silkscreening, gravure printing,
and printing with laser printers, thermal transfer printers, ink
jet printers, or the like. The self-adsorbing laminated foam sheet
on the surface of the base material on which printing is carried
out can be used as building decoration material, sticking materials
for advertising, stationary, or materials for toys. Examples of the
uses include cards for sales promotion, what is called POP cards
(posters, stickers, and displays), underlays (place mats, table
mats and pencil boards), menus for fast food restaurants serving
hamburgers, sushi, and yakisoba, catalogues, panels, plates
(substitutions for metal plates), bromides, price lists for in-shop
display, information boards, (store directories, direction and/or
destination directories, sweets and/or groceries), POPs for
gardening (plant labels), road signs (for funerals and/or housing
display parks), display boards (displaying "keep out", operation on
forestry roads, etc.), calendars (with images), simple whiteboards,
mouse pads, coasters, printed matters that are substitutions for
those made with label printers, and adhesive labels.
[0115] The self-adsorbing foam sheet and the self-adsorbing
laminated foam sheet of the present invention are excellent in
releasability. Thus, part of the sheet does not remain in the side
of a protected item after released. Therefore, the sheet can be
preferably used as an item surface protection material or an item
retention material that is directed to various optical components,
precision components, etc.
[0116] The self-adsorbing foam sheet and the self-adsorbing
laminated foam sheet of the present invention emits extremely a
small amount of formaldehyde even if emitting it. The amount of
emission of formaldehyde can be even less than the detection limit
(for example, less than 0.1 ppm) by proper setting of the formation
of the resin composition for a self-adsorbing foam sheet. Thus, the
sheet of the present invention is preferably employed for places
and uses where generation of formaldehyde is inhibited or not
preferable. That is, the self-adsorbing foam sheet and
self-adsorbing laminated foam sheet of the present invention are
preferably used as building interior decoration material,
stationary, or materials for toys.
EXAMPLES
[0117] The present invention will be described in more detail
below. The present invention is not restricted to Examples. "Parts"
and "%" used below will be by mass unless otherwise specified.
[0118] [Material Properties]
[0119] <Measurement of Glass Transition Temperature (Tg) of
Acrylic Acid Ester Copolymer Resin>
[0120] The glass transition temperature (Tg) of acrylic acid ester
copolymer resin that is used for a material of a self-adsorbing
laminated foam sheet described below was measured with the
following method: 50 m of a polyethylene terephthalate film in
thickness was coated with the acrylic acid ester copolymer resin
with a 250 .mu.m applicator, and was dried at normal temperature
for 24 hours, to obtain a resin film; and using this film as a
sample, the glass transition temperature (.degree. C.) was measured
at -50.degree. C. to 160.degree. C. in measurement temperature at
10.degree. C./min in heating rate with a differential scanning
calorimeter (DSC6220 from SII NanoTechnology Inc.), conforming to
JIS (Japanese Industrial Standards) K7121. The results are shown in
Table 1.
[0121] <Measurement of Gel Fraction of Acrylic Acid Ester
Copolymer Resin>
[0122] The gel fraction of the acrylic acid ester copolymer resin
used for a self-adsorbing laminated foam sheet that was made as
described later was measured with the following method: 50 m of a
polyethylene terephthalate film in thickness was coated with the
acrylic acid ester copolymer resin with a 250 .mu.m applicator, and
dried at normal temperature for 24 hours, to obtain a resin film; a
certain amount (X) (approximately 500 mg) of this film as a sample
was precisely weighed, and was immersed in 100 ml of ethyl acetate
at normal temperature for 3 days; after that insoluble was filtered
through a woven metal of 200 mesh, and air-dried at normal
temperature for 15 hours; after that the insoluble matters were
dried at 100.degree. C. for 2 hours, and cooled at normal
temperature; and after that, the mass of the sample (Y) was
measured. The gel fraction was calculated by substitution of the
values of X and Y into the following formula. The results are shown
in Table 1.
Gel Fraction (%)=(Y)/(X).times.100
[0123] [Evaluation Categories]
[0124] <Self Adsorption Strength>
[0125] After the self-adsorbing laminated foam sheet was made as
described later, a test piece that was cut out into a size of 125
mm.times.25 mm was prepared. An adsorbing face of the test piece
was stuck onto a glass board of a smooth surface, and the test
piece was contact-bonded with a 2 kgf loading roller, and allowed
to stand at 23.degree. C. and 50% RH for 1 hour. After that, an end
of the test piece was fixed to an upper chuck of an Autograph
(AG-IS from Shimadzu Corporation), the glass board was fixed to a
lower chuck thereof, and a 180.degree. peeling test was carried out
at 300 mm/min in speed at 23.degree. C. at 50% RH. Test strength at
this time was defined as an self adsorption strength (N/cm). The
results are shown in Table 1. In a case where the result according
to this evaluation was 0.01 to 1 N/cm, it could be said to have a
proper self adsorption strength.
[0126] <Formaldehyde Dissipation Evaluation>
[0127] After the self-adsorbing laminated foam sheet was made as
described later and further a separator film was stuck onto the
surface of the adsorbing layer, a test piece that was cut out into
a size of 200 mm.times.200 mm was prepared. The test piece was put
into a tedlar bag of 5 L in volume, and the bag was hermetically
sealed. Air of 2 L was encapsulated in the bag, and allowed to
stand for 6 hours in a constant temperature oven at 23.degree. C.
at 50% RH, and after that, the concentration of formaldehyde in the
bag was measured with a detector tube (No. 91L from Gastec
Corporation). The results are shown in Table 1, where a case where
the concentration of formaldehyde was 0.2 ppm or below is indicated
by ".largecircle.", and a case where the concentration of
formaldehyde was beyond 0.2 ppm is indicated by "x".
[0128] <Glossiness (at 60.degree.)>
[0129] Glossiness of the surface of the adsorbing layer was
measured using a gloss meter (GP-60A from Tokyo Denshoku. Co.,
Ltd.), conforming to JIS Z 8741. The results are shown in Table 1.
In a case where the result according to this evaluation was 35 or
more, it could be said that the surface of the sheet was excellent
in smoothness.
[0130] [Making Self-Adsorbing Laminated Foam Sheet]
Example 1
[0131] Into a mixing vessel, 100 parts of an n-methylol group
containing acrylic acid ester copolymer resin (I) in terms of solid
content, 3.6 parts of a carbodiimide crosslinking agent (DICNAL HX
from DIC Corporation) in terms of solid content, and 4.2 parts of a
titanium oxide water dispersant (DISPERSE WHITE HG-701 from DIC
Corporation) in terms of solid content were added, and stirred with
a disperser (composition of (I) was: 46.9 of a copolymer resin of
ethyl acrylate/45.8 of butyl acrylate/5.9 of acrylonitrile/1.4 of
N-methylolacrylamide; its glass transition temperature was
-25.9.degree. C.; and its gel fraction was 43.1%). Next, while
continuing to be stirred, 2 parts of a thickener (carboxylic
acid-modified acrylic acid ester polymers. ARON B-300K from
Toagosei Co., Ltd.) in terms of solid content and 4.1 parts of a
foam stabilizer [a 1/1 mixture of: a mixture of amphoteric
compounds of alkyl betaines and fatty acid alkanolamides (DICNAL
M-20 from DIC Corporation)/sulfonic acid-type anionic surfactants
(DICNAL M-40 from DIC Corporation)] in terms of solid content were
added thereto in this order, and filtered through 150 mesh. Lastly,
ammonia was added thereto, to adjust the viscosity to 4500 mPas,
and a foamed resin composition was obtained.
[0132] This foamed resin composition was stirred with a beater, to
be whipped so that foaming magnification was twice. Further,
stirring was continued for 5 minutes at a lower stirring speed.
[0133] The obtained foamed mixture was applied onto a base material
(a polyethylene terephthalate film of 50 .mu.m in thickness) using
a 0.3 mm applicator. The resultant was put into a drying oven, and
kept at 80.degree. C. for 1.33 minutes; at 120.degree. C. for 1.33
minutes; and at 140.degree. C. for 1.33 minutes, to be subjected to
dry crosslinking. An adsorbing layer (a self-adsorbing foam sheet)
was laminated to the base material, and the self-adsorbing
laminated foam sheet according to Example 1 was obtained.
Example 2
[0134] A sheet according to Example 2 was made in the same manner
as in Example 1 except using a carbodiimide crosslinking agent
(CARBODILITE (registered trademark) E-02 from Nisshinbo Chemical
Inc.) instead of the carbodiimide crosslinking agent (DICNALHX from
DIC Corporation) used in Example 1.
Example 3
[0135] A sheet according to Example 3 was made in the same manner
as in Example 1 except using an N-methylol group containing acrylic
acid ester copolymer resin (II) whose composition was modified from
that of the N-methylol group containing acrylic acid ester
copolymer resin (I), so as to have glass transition temperature of
-17.6.degree. C. and gel fraction of 28.0%.
Example 4
[0136] A sheet according to Example 4 was made in the same manner
as in Example 1 except using an N-methylol group containing acrylic
acid ester copolymer resin (HI) whose composition was modified from
that of the N-methylol group containing acrylic acid ester
copolymer resin (I), so as to have glass transition temperature of
-10.1.degree. C. and gel fraction of 42.2%.
Example 5
[0137] A sheet according to Example 5 was made in the same manner
as in Example 1 except using an N-methylol group containing acrylic
acid ester copolymer resin (IV) whose composition was modified from
that of the N-methylol group containing acrylic acid ester
copolymer resin (I), so as to have glass transition temperature of
-15.3.degree. C. and gel fraction of 41.5%.
Example 6
[0138] A sheet according to Example 6 was made in the same manner
as in Example 1 except using an N-methylol group containing acrylic
acid ester copolymer resin (V) whose composition was modified from
that of the N-methylol group containing acrylic acid ester
copolymer resin (I), so as to have glass transition temperature of
-22.8.degree. C. and gel fraction of 60.5%.
Comparative Example 1
[0139] A sheet according to Comparative Example 1 was made in the
same manner as in Example 1 except using a melamine crosslinking
agent (BECKAMINE M3 from DIC Corporation) and a crosslinking
promoter (CATALYST ACX from DIC Corporation) instead of the
carbodiimide crosslinking agent (DICNAL HX from DIC Corporation)
used in Example 1.
Comparative Example 2
[0140] A sheet according to Comparative Example 2 was made in the
same manner as in Example 1 except using carboxylic group
containing acrylic acid ester copolymer resin (I') (composition:
49.0 of ethyl acrylate/42.1 of butyl acrylate/6.9 of
acrylonitrile/2.0 of acrylic acid; glass transition temperature:
-20.9.degree. C., gel fraction: 89.6%) instead of the N-methylol
group containing acrylic acid ester copolymer resin (I) used in
Example 1.
Comparative Example 3
[0141] A sheet according to Comparative Example 3 was made in the
same manner as in Example 1 except using a carboxylic group
containing acrylic acid ester copolymer resin (II') whose
composition was modified from that of the carboxylic group
containing acrylic acid ester copolymer resin (I') used in
Comparative Example 1, so as to have glass transition temperature
of 6.2.degree. C. and gel fraction of 65.4%, instead of the
N-methylol group containing acrylic acid ester copolymer resin (I)
used in Example 1.
TABLE-US-00001 TABLE 1 Example 1 Example 2 Example 3 Example 4
Example 5 (Meth)acrylic Acid (I) 100 100 Ester Copolymer Resin (II)
100 (III) 100 (IV) 100 (V) (I') (II') Crosslinking Agent DICNAL HX
3.6 3.6 3.6 3.6 CARBODILITE E-02 6.5 BECKAMINE M-3 Crosslinking
Promoter CATALYST ACX Dye DISPERSE WHITE HG-701 4.2 4.2 4.2 4.2 4.2
Thickener ARON B-300K 2.0 2.0 2.0 2.0 2.0 Foam Stabilizer DICNAL
M-20 2.2 2.2 2.2 2.2 2.2 DICNAL M-40 1.9 1.9 1.9 1.9 1.9 Material
Properties Group Crosslinked to Resin N-Methylol N-Methylol
N-Methylol N-Methylol N-Methylol Group Group Group Group Group Type
of Crosslinking Agent Carbodiimide Carbodiimide Carbodiimide
Carbodiimide Carbodiimide Resin Tg (DSC) -25.9.degree. C.
-25.9.degree. C. -17.6.degree. C. -10.1.degree. C. -15.3.degree. C.
Gel Fraction of Resin 43.1% 43.1% 28.0% 42.2% 41.5% (Insoluble of
Ethyl Acetate) Evaluation Categories Self Adsorption Strength 0.15
0.14 0.23 0.22 0.31 (to Glass) Formaldehyde Dissipation
.smallcircle. .smallcircle. .smallcircle. .smallcircle.
.smallcircle. Evaluation (.smallcircle.: 0.2 ppm or below)
Glossiness (at 60.degree.) 44.2 38.6 39.9 36.3 38.5 Excellent when
35 or over Comparative Comparative Comparative Example 6 Example 1
Example 2 Example 3 (Meth)acrylic Acid (I) 100 Ester Copolymer
Resin (II) (III) (IV) (V) 100 (I') 100 (II') 100 Crosslinking Agent
DICNAL HX 3.6 3.6 3.6 CARBODILITE E-02 BECKAMINE M-3 7.3
Crosslinking Promoter CATALYST ACX 0.3 Dye DISPERSE WHITE HG-701
4.2 4.2 4.2 4.2 Thickener ARON B-300K 2.0 1.6 2.0 2.0 Foam
Stabilizer DICNAL M-20 2.2 2.2 2.2 2.2 DICNAL M-40 1.9 1.9 1.9 1.9
Material Properties Group Crosslinked to Resin N-Methylol
N-Methylol Carboxyl Carboxyl Group Group Group Group Type of
Crosslinking Agent Carbodiimide Melamine Carbodiimide Carbodiimide
Resin Tg (DSC) -22.8.degree. C. -25.9.degree. C. -20.9.degree. C.
6.2.degree. C. Gel Fraction of Resin 60.5% 43.1% 89.6% 65.4%
(Insoluble of Ethyl Acetate) Evaluation Categories Self Adsorption
Strength 0.08 0.07 0.11 not Stuck (to Glass) Formaldehyde
Dissipation .smallcircle. x .smallcircle. .smallcircle. Evaluation
(.smallcircle.: 0.2 ppm or below) Glossiness (at 60.degree.) 46.1
45.6 32.7 30.9 Excellent when 35 or over
[0142] As shown in Table 1, all the sheets according to Examples 1
to 6 had low dissipation of formaldehyde, proper self adsorption
strengths, and excellent smoothness. On the other hand, the sheet
according Comparative Example 1 using a melamine crosslinking agent
had a poor result of formaldehyde dissipation evaluation. The sheet
according to Comparative Example 2, not containing a N-methylol
group but containing a carboxyl group, and using the acrylic acid
ester copolymer resin having high gel fraction was poor in
smoothness. The sheet according to Comparative Example 3, using
carboxyl group containing acrylic acid ester copolymer resin of
high glass transition temperature did not adhere to a glass board
in the self adsorption strength measurement test, and was poor in
smoothness as well.
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