U.S. patent application number 12/350782 was filed with the patent office on 2009-06-11 for double-sided pressure-sensitive adhesive tape or sheet and process of producing the same.
This patent application is currently assigned to NITTO DENKO CORPORATION. Invention is credited to Naoyuki Nishiyama, Yoshikazu Soeda, Hironori Tamai, Hiroshi Wada, Kazuyuki Yagura, Hiroshi Yamamoto.
Application Number | 20090148645 12/350782 |
Document ID | / |
Family ID | 34309114 |
Filed Date | 2009-06-11 |
United States Patent
Application |
20090148645 |
Kind Code |
A1 |
Nishiyama; Naoyuki ; et
al. |
June 11, 2009 |
DOUBLE-SIDED PRESSURE-SENSITIVE ADHESIVE TAPE OR SHEET AND PROCESS
OF PRODUCING THE SAME
Abstract
The double-sided pressure-sensitive adhesive tape or sheet is a
double-sided pressure-sensitive adhesive tape or sheet containing a
support having a pressure-sensitive adhesive layer on the both
surfaces thereof, characterized in that the double-sided
pressure-sensitive adhesive tape or sheet has a total thickness
including the thickness of the support and the two
pressure-sensitive adhesive layers formed on the both surfaces of
the support of 0.003 mm or more and less than 0.03 mm and a
breaking strength of from 2 to 26 MPa/10 mm-width. The support
preferably has a thickness of from 0.002 to 0.012 mm. As the
support, plastic films (especially, a polyethylene terephthalate
film) are suitable. The double-sided pressure-sensitive adhesive
tape or sheet may have a length of 5 m or more and have a
roll-wound form.
Inventors: |
Nishiyama; Naoyuki;
(Ibaraki-shi, JP) ; Soeda; Yoshikazu;
(Ibaraki-shi, JP) ; Tamai; Hironori; (Ibaraki-shi,
JP) ; Wada; Hiroshi; (Ibaraki-shi, JP) ;
Yagura; Kazuyuki; (Ibaraki-shi, JP) ; Yamamoto;
Hiroshi; (Ibaraki-shi, JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W., SUITE 800
WASHINGTON
DC
20037
US
|
Assignee: |
NITTO DENKO CORPORATION
|
Family ID: |
34309114 |
Appl. No.: |
12/350782 |
Filed: |
January 8, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11430942 |
May 10, 2006 |
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12350782 |
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|
10947236 |
Sep 23, 2004 |
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11430942 |
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Current U.S.
Class: |
428/41.8 ;
428/214 |
Current CPC
Class: |
Y10T 428/1476 20150115;
C09J 7/20 20180101; C09J 2433/00 20130101; Y10T 428/2848 20150115;
Y10T 428/28 20150115; C09J 7/38 20180101; C09J 2301/312 20200801;
C09J 7/22 20180101; Y10T 428/24959 20150115; C09J 2301/124
20200801; G02F 2202/28 20130101 |
Class at
Publication: |
428/41.8 ;
428/214 |
International
Class: |
B32B 7/02 20060101
B32B007/02; B32B 33/00 20060101 B32B033/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 1, 2003 |
JP |
P2003-343533 |
Claims
1-11. (canceled)
12. A double-sided pressure-sensitive adhesive tape or sheet
comprising a support having a pressure-sensitive adhesive layer on
the both surfaces thereof, the pressure-sensitive adhesive layer
comprising an acrylic polymer containing C.sub.1-20 alkyl
(meth)acrylate as a monomer major component, wherein the
double-sided pressure-sensitive adhesive tape or sheet has a total
thickness including the thickness of the support and the two
pressure-sensitive adhesive layers formed on the both surfaces of
the support of 0.003 mm or more and less than 0.03 mm, and wherein
the two pressure-sensitive adhesive layers each have a thickness of
0.0005 to 0.0275 mm.
13. The double-sided pressure-sensitive adhesive tape or sheet
according to claim 12, wherein the support has a thickness of from
0.002 to 0.012 mm.
14. The double-sided pressure-sensitive adhesive tape or sheet
according to claim 12, wherein the support is a plastic film.
15. The double-sided pressure-sensitive adhesive tape or sheet
according to claim 14, wherein the support is a polyethylene
terephthalate film.
16. The double-sided pressure-sensitive adhesive tape or sheet
according to claim 12, wherein the double-sided pressure-sensitive
adhesive tape or sheet has a length of 5 m or more and has a
roll-wound form.
17. The double-sided pressure-sensitive adhesive tape according to
claim 12, further comprising a release liner on at least one of the
pressure-sensitive adhesive layers at a side of the
pressure-sensitive adhesive layer opposite to the support.
18. The double-sided pressure-sensitive adhesive tape or sheet
according to claim 12, wherein the thickness of the two
pressure-sensitive adhesive layers are the same.
19. The double-sided pressure-sensitive adhesive tape or sheet
according to claim 12, wherein the thickness of the two
pressure-sensitive adhesive layer are different.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of application Ser. No.
11/430,942 filed May 10, 2006, which is a divisional of application
Ser. No. 10/947,236 filed Sep. 23, 2004. The entire disclosures of
the prior applications, application Ser. No. 10/947,236 and
application Ser. No. 11/430,942 are hereby incorporated by
reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a double-sided
pressure-sensitive adhesive tape or sheet and to a process of
producing the same. In particular, the invention relates to a
double-sided pressure-sensitive adhesive tape or sheet which is
suitably used in a junction of a case or part at the time of
manufacture (fabrication) of various OA instruments and electronic
parts and to a process of producing the same.
BACKGROUND OF THE INVENTION
[0003] In recent years, in OA instruments and electronic parts (in
particular, mobile instruments) such as personal computers,
printers, cellular telephones, PDA, digital cameras, and digital
video cameras, their productions increase with their diffusion, and
size reduction and thinning are being designed in parallel to
realization of high function. For example, in cellular telephones
which are a representative instrument of mobile instruments, for
the sake of enlarging the display screen and improving
portableness, the major parts to be constructed tend to become
thin. In general, a display portion is mainly composed of an LCD
module and a backlight unit, and a variety of parts in the sheet
form are frequently used (laminated) for the purpose of revealing
functions such as light emission, reflection, light shielding, and
light guiding. In the fabrication (junction) of these parts,
double-sided pressure-sensitive adhesive tapes or sheets, screws,
adhesives, and the like are usually used (see JP-A-2002-249741)
(The term "JP-A" as used herein means an "unexamined published
Japanese patent application").
[0004] In the fabrication (junction) of parts, for example, in the
case where a double-sided pressure-sensitive adhesive tape or sheet
is used, because of restrictions in the thickness of products or
parts, double-sided pressure-sensitive adhesive tapes or sheets
having a relatively thin thickness tend to be used among
commercially available double-sided pressure-sensitive adhesive
tapes or sheets. However, in many cases, double-sided
pressure-sensitive adhesive tapes or sheets merely composed of a
pressure-sensitive adhesive layer only (so-called "substrate-less
double-sided pressure-sensitive adhesive tapes or sheets") are used
as conventional double-sided pressure-sensitive adhesive tapes or
sheets having a thin thickness. As the thickness is decreased, the
strength of a double-sided pressure-sensitive adhesive tape or
sheet is lowered so that the double-sided pressure-sensitive
adhesive tape or sheet is cut during the adhesion works, or it is
actually difficult to again release a double-sided
pressure-sensitive adhesive tape or sheet which has been stuck
once, resulting in a lowering of the workability.
[0005] On the other hand, in sites where a further ultra-thin layer
structure is required, conventional double-sided pressure-sensitive
adhesive tapes or sheets become difficult for use because of
restrictions in the clearance. For this reason, the object is
achieved by coating a liquid adhesive in place of the double-sided
pressure-sensitive adhesive tape or sheet.
[0006] However, since an adhesive is liquid with respect to its
properties, it is difficult to make the coating thickness uniform.
Also, since its fluidity is high, an inconvenience following the
adhesion into other portions than the necessary site is liable to
occur. Further, in general, it takes a time to complete curing, an
aspect of which becomes a factor of lowering the productivity of
fabrication works, and therefore, such is inferior in economy.
SUMMARY OF THE INVENTION
[0007] Accordingly, an object of the invention is to provide a
double-sided pressure-sensitive adhesive tape or sheet having an
excellent strength even though its thickness is thin and a process
of producing the same.
[0008] Another object of the invention is to provide a double-sided
pressure-sensitive adhesive tape or sheet not only having a
necessary thin thickness but also holding a good strength without
causing cutting at the time of or during its use and a process of
producing the same.
[0009] A further object of the invention is to provide a
double-sided pressure-sensitive adhesive tape or sheet which can be
stably produced in the longitudinal and roll-wound form
nevertheless its thickness is very thin and which can be easily
rewound with excellent workability and a process of producing the
same.
[0010] Even another object of the invention is to provide a
double-sided pressure-sensitive adhesive tape or sheet which can be
utilized even though a space between junction parts is in a thin
region that has not been employed so far in a junction measure
utilizing a double-sided pressure-sensitive adhesive tape or sheet
and a process of producing the same.
[0011] For the sake of achieving the foregoing objects, the present
inventors made extensive and intensive investigations. As a result,
it has been found that by employing a support (substrate) having a
thickness in a very thin thickness region that has not been used as
a support (substrate) of a double-sided pressure-sensitive adhesive
tape or sheet so far, defining the total thickness including the
support and the pressure-sensitive adhesive layer to be less than
0.030 mm and defining the breaking strength to be a specified
value, it is possible to obtain a double-sided pressure-sensitive
adhesive tape or sheet having an excellent strength even though its
thickness is thin, leading to accomplishment of the invention.
[0012] Specifically, the invention provides a double-sided
pressure-sensitive adhesive tape or sheet comprising a support
having a pressure-sensitive adhesive layer on the both surfaces
thereof, wherein the double-sided pressure-sensitive adhesive tape
or sheet has a total thickness including the thickness of the
support and the two pressure-sensitive adhesive layers formed on
the both surfaces of the support of 0.003 mm or more and less than
0.03 mm and a breaking strength of from 2 to 26 MPa/10
mm-width.
[0013] The foregoing support preferably has a thickness of from
0.002 to 0.012 mm. The support is preferably a plastic film, and
especially preferably a polyethylene terephthalate film.
[0014] The double-sided pressure-sensitive adhesive tape or sheet
of the invention may have a length of 5 m or more and have a
roll-wound form.
[0015] Also, the invention provides a process of producing a
double-sided pressure-sensitive adhesive tape or sheet including
the following steps (A) to (C), wherein in the step (B), in
laminating the pressure-sensitive adhesive layer formed on the
release liner on one surface of the support, a tension to be
applied to the support is less than 2 N.
[0016] Step (A): A step of coating a pressure-sensitive adhesive on
a release treatment surface of a release liner to form a
pressure-sensitive adhesive layer on the release liner.
[0017] Step (B): A step of laminating the pressure-sensitive
adhesive layer formed on the release liner on one surface of a
support to form a first pressure-sensitive adhesive layer on the
support.
[0018] Step (C): A step of coating a pressure-sensitive adhesive on
the other surface of the support to form a second
pressure-sensitive adhesive layer on the support.
[0019] It is preferable that the support to be used in the
foregoing step (B) is a roll-wound longitudinal support and that in
feeding the roll-wound longitudinal support to laminate the
pressure-sensitive adhesive layer formed on the release liner on
one surface of the support, a tension to be applied to the support
is less than 2 N.
[0020] It is suitable that the process of producing a double-sided
pressure-sensitive adhesive tape or sheet according to the
invention further includes the following step (D).
[0021] Step (D): A step of roll winding in such a manner that the
second pressure-sensitive adhesive layer is superimposed on the
release treatment surface of the other surface of the release
liner, to obtain a roll-wound double-sided pressure-sensitive
adhesive tape or sheet.
[0022] The foregoing support preferably has a thickness of from
0.002 to 0.012 mm. Also, the double-sided pressure-sensitive
adhesive tape or sheet may have a total thickness including the
thickness of the support and the two pressure-sensitive adhesive
layers formed on the both surfaces of the support of 0.003 mm or
more and less than 0.03 mm. Further, the double-sided
pressure-sensitive adhesive tape or sheet preferably has a breaking
strength of from 2 to 26 MPa/10 mm-width.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a schematic view showing one embodiment of the
double-sided pressure-sensitive adhesive tape or sheet of the
invention.
[0024] FIG. 2 is a schematic step view showing one embodiment of
the process of producing the double-sided pressure-sensitive
adhesive tape or sheet of the invention.
DESCRIPTION OF THE REFERENCE NUMERALS AND SIGNS
[0025] 1: Double-sided pressure-sensitive adhesive tape or sheet
[0026] 1a: Support [0027] 1b: Pressure-sensitive adhesive layer
(first pressure-sensitive adhesive layer) [0028] 1c:
Pressure-sensitive adhesive layer (second pressure-sensitive
adhesive layer) [0029] 1d: Release liner [0030] 2: Release liner
[0031] 3: Pressure-sensitive adhesive coating unit [0032] 4: Drying
or ultraviolet irradiation zone [0033] 5: Support [0034] 6:
Lamination site [0035] 7: Pressure-sensitive adhesive coating unit
[0036] 8: Drying or ultraviolet irradiation zone [0037] 9:
Double-sided pressure-sensitive adhesive tape or sheet
DETAILED DESCRIPTION OF THE INVENTION
Double-Sided Pressure-Sensitive Adhesive Tape or Sheet
[0038] As illustrated in FIG. 1, the double-sided
pressure-sensitive adhesive tape or sheet of the invention is a
substrate-provided double-sided pressure-sensitive adhesive tape or
sheet having a pressure-sensitive adhesive layer on the both
surfaces of a support and has a total thickness including the
thickness of the support and the two pressure-sensitive adhesive
layers formed on the both surfaces of the support of 0.003 mm or
more and less than 0.03 mm and a breaking strength of from 2 to 26
MPa/10 mm-width. In this way, nevertheless the double-sided
pressure-sensitive adhesive tape or sheet of the invention is a
substrate-provided double-sided pressure-sensitive adhesive tape or
sheet, its thickness is thin as less than 30 .mu.m, and its
breaking strength is excellent as from 2 to 26 MPa. For this
reason, it not only has a necessary thin thickness but also holds a
good strength without causing cutting at the time of or during its
use. Accordingly, nevertheless the double-sided pressure-sensitive
adhesive tape or sheet of the invention has a very thin thickness,
it can be stably produced in the longitudinal and roll-wound form
and easily rewound with excellent workability. For this reason, the
double-sided pressure-sensitive adhesive tape or sheet of the
invention is excellent with respect to the productivity in carrying
out continuous punching processing or automatic sticking.
[0039] On the other hand, the thickness of conventional
substrate-provided double-sided pressure-sensitive adhesive tapes
or sheets (support-incorporated double-sided pressure-sensitive
adhesive tapes or sheets) was substantially from 80 to 300 .mu.m,
and even in the case of substrate-less double-sided
pressure-sensitive adhesive tapes or sheets (support-free
double-sided pressure-sensitive adhesive tapes or sheets), the
thickness was substantially from 30 to 60 .mu.m. In this way,
substrate-provided double-sided pressure-sensitive adhesive tapes
or sheets, the thickness of which is substantially thick and is
less than 30 .mu.m, have not been provided so far.
[0040] Accordingly, by using the double-sided pressure-sensitive
adhesive tape or sheet of the invention, it becomes possible to
make it cope with a region wherein the thickness of a junction site
(a clearance between junction parts) has not been employed so far
in a junction measure utilizing a double-sided pressure-sensitive
adhesive tape or sheet (for example, in the case where a tolerable
clearance of a junction part is less than 0.03 mm), whereby uniform
adhesion works using a double-sided pressure-sensitive adhesive
tape or sheet can be carried out. That is, even though a space
between junction parts is in a thin region that has not been
employed so far in a junction measure utilizing a double-sided
pressure-sensitive adhesive tape or sheet, by using the
double-sided pressure-sensitive adhesive tape or sheet of the
invention, it becomes possible to achieve a uniform junction
measure using a double-sided pressure-sensitive adhesive tape or
sheet.
[0041] FIG. 1 is a schematic view showing one embodiment of the
double-sided pressure-sensitive adhesive tape or sheet of the
invention. In FIG. 1, 1 stands for a double-sided
pressure-sensitive adhesive tape or sheet; 1a stands for a support;
1b stands for a pressure-sensitive adhesive layer (first
pressure-sensitive adhesive layer); 1c stands for a
pressure-sensitive adhesive layer (second pressure-sensitive
adhesive layer); and 1d stands for a release liner. The
double-sided pressure-sensitive adhesive tape or sheet 1 has a
construction in which the pressure-sensitive adhesive layer 1b is
formed on one surface of the support 1a, and the pressure-sensitive
adhesive layer 1c is formed on the other surface of the support 1a.
Further, the double-sided pressure-sensitive adhesive tape or sheet
1 has a roll-wound form where the pressure-sensitive adhesive layer
1b is protected by the release liner 1d, and the pressure-sensitive
adhesive layer 1c is superimposed on the other surface of the
release liner 1d (the surface in the opposite side to the
pressure-sensitive adhesive layer 1b) such that the both are
brought into contact with each other.
[0042] The total thickness (tape thickness) of the double-sided
pressure-sensitive adhesive tape or sheet of the invention is not
particularly limited so far as it is 0.003 mm or more and less than
0.03 mm. For example, it is selected within the range of from 0.003
to 0.029 mm (preferably from 0.003 to 0.026 mm, more preferably
from 0.003 to 0.02 mm, and especially preferably from 0.003 to
0.015 mm).
[0043] Incidentally, the total thickness (tape thickness) of the
double-sided pressure-sensitive adhesive tape or sheet as referred
to herein means the thickness of a portion which is utilized in
sticking. That is, the total thickness of the double-sided
pressure-sensitive adhesive tape or sheet means the thickness
(total thickness) from one pressure-sensitive adhesive surface to
the other pressure-sensitive adhesive surface. Concretely, since
the double-sided pressure-sensitive adhesive tape or sheet of the
invention is a substrate-provided double-sided pressure-sensitive
adhesive tape or sheet, the total thickness of the double-sided
pressure-sensitive adhesive tape or sheet means the thickness
including the thickness of the support and the two
pressure-sensitive adhesive layers formed on the both surfaces of
the support, but the thickness of the release liner (separator) for
protecting the pressure-sensitive adhesive surface is not
included.
[0044] Also, the breaking strength of the double-sided
pressure-sensitive adhesive tape or sheet of the invention is not
particularly limited so far as it is from 2 to 26 MPa/10 mm-width.
It is preferably from 2 to 14 MPa/10 mm-width, and more preferably
from 4 to 10 MPa/10 mm-width. By setting up the breaking strength
of the double-sided pressure-sensitive adhesive tape or sheet so as
to fall within the foregoing range, it becomes possible to make
various members (junction parts) adhere to each other in a stable
dimensional shape without causing stretching or cutting of a
double-sided pressure-sensitive adhesive tape or sheet as seen in
substrate-less double-sided pressure-sensitive adhesive tapes or
sheets at the time of processing or sticking works or in handling.
Incidentally, in the invention, the breaking strength of the
double-sided pressure-sensitive adhesive tape or sheet is a value
measured by the following method. That is, a double-sided
pressure-sensitive adhesive tape or sheet is cut into a width of 10
mm, and the surface thereof is given gauge marks at intervals of 50
mm to prepare a specimen (10 mm in width); and the specimen is
stretched under conditions at room temperature (23.degree. C.) and
at 65% RH and under conditions at a chuck distance of the specimen
of 50 mm and at a tensile rate of 200 mm/min using a tensile
tester, and a load (stress) at the time when the specimen breaks
(at the time when a crack is generated from at least a part
thereof) is measured and defined as the breaking strength
(MPa).
<Support>
[0045] The support is not particularly limited with respect to its
material quality and thickness so far as it is possible to make the
total thickness of the double-sided pressure-sensitive adhesive
tape or sheet fall within the range of 0.003 mm or more and less
than 0.03 mm and to make the breaking strength of the double-sided
pressure-sensitive adhesive tape or sheet fall within the range of
from 2 to 26 MPa/10 mm-width. Examples of material qualities of the
support include plastic materials, paper materials, fiber materials
(for example, woven fabrics and non-woven fabrics), and metal
materials. As the material quality of the support, plastic
materials are suitable. That is, plastic films can be suitably used
as the support.
[0046] As such plastic materials (material qualities of plastic
films), a variety of engineering plastic materials can be suitably
used. Specific examples of plastic materials include polyesters
[for example, polyethylene terephthalate (PET), polyethylene
naphthalate (PEN), and polybutylene terephthalate (PBT)], olefin
based resins [for example, olefin based resins containing, as a
monomer component, an .alpha.-olefin such as polyethylene (PE),
polypropylene (PP), ethylene-propylene copolymers, and
ethylene-vinyl acetate copolymers (EVA)], polyethersulfones (PES),
polysulfones, polyvinyl chloride (PVC), polyphenylene sulfides
(PPS), amide based resins [for example, polyamides (nylons) and
wholly aromatic polyamides (aramids)], polyimides (PI),
polyamideimides, polyetherimides (PEI), polyesterimides,
methacrylate based resins [for example, polymethyl methacrylate
(PMMA)], styrene based resins [for example, polystyrenes,
acrylonitrile-styrene copolymers (AS resins), and
acrylonitrile-butadiene-styrene copolymers (ABS resins)],
polycarbonates (PC), polyacetals, polyarylene ethers (for example,
polyphenylene ethers), polyphenylene sulfides, polyarylates,
polyaryls, polyurethanes, polyether ketones [for example,
polyetheretherketones (PEEK) and polyether-ketoneketones],
polyacrylic esters (for example, polybutyl acrylate and polyethyl
acrylate), and epoxy based resins. These materials (plastic
materials) can be used singly or in combinations of two or more
thereof.
[0047] As the plastic material, in particular, polyesters
(especially, polyethylene terephthalate) can be suitably used from
the viewpoints of thickness accuracy, economy (cost performance),
tensile strength, processability, etc. That is, as the support, in
particular, polyester films (especially, polyethylene terephthalate
films) can be suitably used.
[0048] Incidentally, the support may have any form of a single
layer or a laminated layer and is not structurally restricted.
[0049] The thickness of the support is properly selected within the
range where the total thickness of the double-sided
pressure-sensitive adhesive tape or sheet can be made to fall
within the range of 0.003 mm or more and less than 0.03 mm, and the
breaking strength of the double-sided pressure-sensitive adhesive
tape or sheet can be made to fall within the range of from 2 to 26
MPa/10 mm-width. For example, it can be selected within the range
of from 0.002 to 0.012 mm (preferably from 0.002 to 0.009 mm, and
more preferably from 0.002 to 0.004 mm). The support having such a
thickness range (for example, from 0.002 to 0.012 mm) (in
particular, in the case where the support is a plastic film) is a
support having a thickness range falling within a region that has
not been employed as a support in the double-sided
pressure-sensitive adhesive tape or sheet (in particular, in the
case where the support is a plastic film) so far.
[0050] Incidentally, for the sake of enhancing the adhesion to the
pressure-sensitive adhesive layer and the like to be formed on the
support, the surface of the support (in particular, the support
made of a plastic material) may be subjected to a customary surface
treatment such as chemical or physical oxidation treatments
including chromic acid treatment, ozone exposure, flame exposure,
high voltage electric shock exposure, and ionized radiation
treatment or may be subjected to a coating treatment with an
undercoating agent.
<Pressure-Sensitive Adhesive Layer>
[0051] The pressure-sensitive adhesive that forms the
pressure-sensitive adhesive layer is not particularly limited and
can be properly selected and used from known pressure-sensitive
adhesives such as acrylic pressure-sensitive adhesives, rubber
based pressure-sensitive adhesives, silicone based
pressure-sensitive adhesives, urethane based pressure-sensitive
adhesives, polyester based pressure-sensitive adhesives,
styrene-butadiene block copolymer based pressure-sensitive
adhesives, vinylalkyl ether based pressure-sensitive adhesives,
polyamide based pressure-sensitive adhesives, fluorine based
pressure-sensitive adhesives, creep characteristic improvement type
pressure-sensitive adhesives, and radiation curing type
pressure-sensitive adhesives. The pressure-sensitive adhesives can
be used singly or in combinations of two or more thereof.
[0052] In particular, acrylic pressure-sensitive adhesives can be
suitably used as the pressure-sensitive adhesive from the viewpoint
of adhesion reliability. The acrylic pressure-sensitive adhesives
contain an acrylic polymer as a pressure-sensitive adhesive
component (base polymer) or as a principal agent and further
contain proper additives such as a crosslinking agent, a tackifier,
a softening agent, a plasticizer, a filler, an antioxidant, and a
coloring agent, if desired. The foregoing acrylic polymer is
prepared by using an alkyl (meth)acrylate as the monomer major
component and further using a monomer copolymerizable with the
foregoing alkyl (meth)acrylate (copolymerizable monomer), if
desired. Examples of the foregoing alkyl (meth)acrylate include
C.sub.1-20-alkyl (meth)acrylates [preferably, C.sub.4-18-alkyl
(linear or branched alkyl) (meth)acrylates] such as methyl
(meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate,
isopropyl (meth)-acrylate, butyl (meth)acrylate, isobutyl
(meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate,
pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate,
octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl
(meth)acrylate, nonyl (meth)acrylate, isononyl (meth)-acrylate,
decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl
(meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate,
tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl
(meth)acrylate, heptadecyl (meth)acrylate, octadecyl
(meth)acrylate, nonadecyl (meth)-acrylate, and eucosyl
(meth)acrylate. The alkyl (meth)acrylate can be properly selected
depending upon the desired adhesiveness. The alkyl (meth)acrylate
can be used singly or in combinations of two or more thereof.
[0053] Also, examples of the foregoing copolymerizable monomer
include carboxyl group-containing monomers or anhydrides thereof
such as (meth)acrylic acid, itaconic acid, maleic acid, fumaric
acid, crotonic acid, and isocrotonic acid; sulfonic acid
group-containing monomers such as sodium vinylsulfonate; aromatic
vinyl compounds such as styrene and substituted styrenes; cyano
group-containing monomers such as acrylonitrile; olefins such as
ethylene, propylene, and butadiene; vinyl esters such as vinyl
acetate; vinyl chloride; amide group-containing monomers such as
acrylamide, methacrylamide, N-vinylpyrrolidone, and N,N-dimethyl
(meth)acrylamide; hydroxyl group-containing monomers such as
hydroxyalkyl (meth)acrylamides and glycerin dimethacrylate; amino
group-containing monomers such as aminoethyl (meth)acrylate and
(meth)acryloylmorpholine; imido group-containing monomers such as
cyclohexylmaleimide and isopropylmaleimide; epoxy group-containing
monomers such as glycidyl (meth)acrylate and methylglycidyl
(meth)acrylate; and isocyanate group-containing monomers such as
2-methacryloyloxyethyl isocyanate. Besides, polyfunctional
copolymerizable monomers (polyfunctional monomers) such as
triethylene glycol di(meth)acrylate, diethylene glycol
di(meth)acrylate, ethylene glycol di(meth)acrylate, tetraethylene
glycol di-(meth)acrylate, neopentyl glycol di(meth)acrylate,
1,6-hexanediol di(meth)acrylate, trimethylolpropane
tri-(meth)acrylate, pentaerythritol tri(meth)acrylate,
dipentaerythritol hexa(meth)acrylate, and divinylbenzene are
enumerated. The copolymerizable monomers can be used singly or in
combinations of two or more thereof. Monomers for modification
containing a functional group such as a carboxyl group can be
suitably used as the copolymerizable monomer.
[0054] The acrylic polymer can be prepared by a customary
polymerization method such as a solution polymerization method, an
emulsion polymerization method, and an ultraviolet irradiation
polymerization method.
[0055] The thickness of each of the pressure-sensitive adhesive
layers can be properly selected while taking into consideration the
adhesive characteristic and the total thickness of the double-sided
pressure-sensitive adhesive tape or sheet. For example, the
thickness of each of the pressure-sensitive adhesive layers can be
selected within the range of from 0.0005 to 0.0275 mm (preferably
from 0.004 to 0.014 mm, and more preferably from 0.004 to 0.01 mm).
Incidentally, in the two pressure-sensitive adhesive layers to be
formed on the both surfaces of the support, the thickness of each
of the pressure-sensitive adhesive layers (the pressure-sensitive
adhesive layer in the front surface side and the pressure-sensitive
adhesive layer in the back surface side) is not particularly
defined and can be properly selected depending upon the
application. Also, the thickness of the two pressure-sensitive
adhesive layers to be formed on the both surfaces of the support
may be the same of different, but in many cases, the same thickness
or substantially the same thickness is selected.
<Release Liner>
[0056] The double-sided pressure-sensitive adhesive tape or sheet
of the invention can be provided with a release liner for the
purpose of protecting the pressure-sensitive adhesive surface of
the pressure-sensitive adhesive layer. Such a release liner is not
particularly defined and can be properly selected and used from
known release liners. Specifically, for example, the release liner
may be made of a plastic film having itself high release property
[for example, polyolefin based films made of polyolefin based
resins (for example, polyethylene (such as low-density polyethylene
and linear low-density polyethylene), polypropylene,
ethylene-.alpha.-olefin copolymers (block copolymers or random
copolymers) such as ethylene-propylene copolymers, or a mixture
thereof); and films made of Teflon (a registered trademark)].
However, release liners having a construction wherein a release
treatment layer is formed on the surface (one surface or both
surfaces) of a varied support (substrate) can be suitably used.
[0057] As a substrate of the release liner, plastic films are
suitably used, but papers (for example, Japan paper, machine-made
paper, and glassine paper), non-woven fabrics or cloths, expanded
bodies, metal foils, and composite substrates composed of a variety
of substrates (for example, metal vapor deposited plastic films)
may be employed. The thickness of the substrate can be properly
selected depending upon the application and is in general from
about 10 to 500 .mu.m. Incidentally, examples of the material of
the plastic film of the substrate of the foregoing release liner
include thermoplastic resins such as polyesters (for example,
polyethylene terephthalate), polyolefins (for example,
polypropylene, polyethylene, and ethylene-propylene copolymers),
polyvinyl chloride, polyimides, and polycarbonates. The plastic
film may be any of a non-stretched film or a stretched (uniaxially
stretched or biaxially stretched) film.
[0058] Also, the release treatment layer can be formed by using a
known or customary release treating agent (for example, silicone
based release treating agents, fluorine based release treating
agents, and long-chain alkyl based release treating agents) as a
release treating agent capable of forming the release treatment
layer in the release liner. Incidentally, the release treatment
layer may be formed by laminating or coating a polyolefin based
film made of a polyolefin based resin (for example, polyethylene,
polypropylene, and ethylene-.alpha.-olefin copolymers such as
ethylene-propylene copolymers) or a film made of Teflon (a
registered trademark) on the foregoing support. In the release
liner, the release treatment layer can be provided on one surface
or both surfaces of the substrate as described previously.
[0059] The release liner can control or prevent the deformation of
the double-sided pressure-sensitive adhesive tape or sheet at the
time of adhesion works (release works of the release liner) by
adjusting a release strength to the pressure-sensitive adhesive
layer at not more than 1 N/50 mm to improve the workability. The
release liner and release strength can be properly selected or
adjusted depending upon the application and are not particularly
limited.
[0060] The double-sided pressure-sensitive adhesive tape or sheet
of the invention may have a form of a laminate resulting lamination
of sheet-form materials or may have a form of a roll-wound rolled
body. For example, one sheet of a release liner in the longitudinal
stripe form, the both surfaces of which are a release treatment
surface, is used as the release liner; the one-sided release
treatment surface of the release liner is superimposed and
laminated on the pressure-sensitive adhesive surface of the
one-sided pressure-sensitive adhesive layer in the double-sided
pressure-sensitive adhesive tape or sheet in the longitudinal
stripe form; and the laminate is wound in the rolled state in such
a manner that the other release treatment surface of the foregoing
release liner is superimposed on the pressure-sensitive adhesive
surface of the other pressure-sensitive adhesive layer, whereby a
double-sided pressure-sensitive adhesive tape or sheet having a
roll-wound form can be prepared. Also, two sheets of a release
liner in the longitudinal stripe form in which only one surface
thereof is a release treatment surface is used as the release
liner; and the two sheets are wound in the rolled state in such a
state that the pressure-sensitive adhesive surface of the one-sided
pressure-sensitive adhesive layer in the double-sided
pressure-sensitive adhesive tape or sheet in the longitudinal
stripe form is protected by the one-sided release liner and that
the pressure-sensitive adhesive surface of the other
pressure-sensitive adhesive layer is protected by the other release
liner, whereby a double-sided pressure-sensitive adhesive tape or
sheet having a roll-wound form can be prepared.
[0061] The length of the double-sided pressure-sensitive adhesive
tape or sheet having such a roll-wound form is not particularly
limited so far as it is a length in the longitudinal stripe form.
However, in general, it is 5 m or more (preferably 10 m or more,
and more preferably 20 m or more).
[0062] Incidentally, in the invention, the thickness of the
double-sided pressure-sensitive adhesive tape or sheet is very thin
as less than 0.03 mm, and a thin support in a level that has not
been employed so far is used. Accordingly, in winding in the rolled
state, wrinkles are liable to be formed in the double-sided
pressure-sensitive adhesive tape or sheet or in the support.
However, by adjusting the tension (tensile tension) of the support
at the time of production as described below, a double-sided
pressure-sensitive adhesive tape or sheet in the roll-wound form
can be stably produced in a good state.
[0063] There may be the case where the double-sided
pressure-sensitive adhesive tape or sheet is previously subjected
to cutting processing (pre-processing) into a part shape.
Incidentally, examples of such pre-processing include sealing
processing and press processing. For this reason, it is preferable
from the viewpoints of workability and economy, etc. that the form
of the double-sided pressure-sensitive adhesive tape or sheet
before the pre-processing is a rolled shape and longitudinal
product. Accordingly, nevertheless the double-sided
pressure-sensitive adhesive tape or sheet of the invention is thin
with respect to the total thickness or the thickness of the
support, it has a tensile strength necessary for the processing or
sticking works. Also, the double-sided pressure-sensitive adhesive
tape or sheet of the invention can be processed into a rolled shape
and longitudinal product, a varied pre-processing can be easily and
continuously carried out so that excellent workability and economy
can be revealed.
[0064] As a matter of course, even in the case where the
pre-processing is carried out, the double-sided pressure-sensitive
adhesive tape or sheet may have a single plate (sheet-like) form.
In this case, since the pre-pressing is not in a continuous mode
but a batch work, it is not so preferable from the viewpoint of
economy (cost performance).
[0065] Accordingly, the double-sided pressure-sensitive adhesive
tape or sheet of the invention can be suitably used for supplying a
junction member that is required to become a thin layer, especially
a junction member that is required to become a thin layer such that
a space between junction parts (a clearance between junction parts)
is in a thin region that has not been employed so far in a junction
measure utilizing a double-sided pressure-sensitive adhesive tape
or sheet (for example, a region wherein a tolerable clearance of a
junction part is less than 0.03 mm). Such a junction member is not
particularly limited so far as it is required to become a thin
layer. Examples thereof include members constructing OA instruments
and electronic parts [for example, personal computers (for example,
desktop type personal computers and notebook type personal
computers), printers, cellular telephones, PDA, digital cameras,
and digital video cameras (in particular, mobile instruments such
as notebook type personal computers, cellular telephones, and
PDA)], including LCD modules, backlight units, and parts in the
sheet form for revealing various functions such as light emission,
reflection, light shielding, and light guiding.
<Production Process>
[0066] The production process of the double-sided
pressure-sensitive adhesive tape or sheet of the invention is not
particularly limited and can be properly selected from known
production processes. Examples thereof include a process of
producing a double-sided pressure-sensitive adhesive tape or sheet
including a step of coating a pressure-sensitive adhesive on one
surface of a support to form a first pressure-sensitive adhesive
layer and a step of, after or simultaneously with the formation of
the first pressure-sensitive adhesive layer, coating a
pressure-sensitive adhesive on the other surface of the support to
form a second pressure-sensitive adhesive layer; and a process of
producing a double-sided pressure-sensitive adhesive tape or sheet
including the following steps (A) to (C).
[0067] Step (A): A step of coating a pressure-sensitive adhesive on
a release treatment surface of a release liner to form a
pressure-sensitive adhesive layer on the release liner.
[0068] Step (B): A step of laminating the pressure-sensitive
adhesive layer formed on the release liner on one surface of a
support to form a first pressure-sensitive adhesive layer on the
support.
[0069] Step (C): A step of coating a pressure-sensitive adhesive on
the other surface of the support to form a second
pressure-sensitive adhesive layer on the support.
[0070] In particular, in the invention, it is preferable that in
the foregoing step (B), in laminating the pressure-sensitive
adhesive layer formed on the release liner on one surface of the
support, a tension to be applied to the support is less than 2 N.
That is, the step (B) is preferably the following step (B1).
[0071] Step (B1): A step of laminating the pressure-sensitive
adhesive layer formed on the release liner on one surface of the
support in the state that the tension to be applied to the support
is less than 2 N, to form a first pressure-sensitive adhesive layer
on the support.
[0072] In this way, in laminating the pressure-sensitive adhesive
layer formed on the release liner on one surface of the support to
form a first pressure-sensitive adhesive layer on the support, by
adjusting the tension to be applied to the support at a level as
low as possible, even though the thickness of the support is very
thin, it is possible to produce a double-sided pressure-sensitive
adhesive tape or sheet in a good state without generating wrinkles
and so on.
[0073] Accordingly, the double-sided pressure-sensitive adhesive
tape or sheet of the invention can be suitably prepared by a
production process including a step (A), a step (B1) and a step (C)
as illustrated in FIG. 2. In particular, in producing a
double-sided pressure-sensitive adhesive tape or sheet in the
roll-wound form as the double-sided pressure-sensitive adhesive
tape or sheet, by employing a production process including the step
(A), the step (B1) and the step (C), it is possible to stably
produce a double-sided pressure-sensitive adhesive tape or sheet in
the roll-wound form without generating wrinkles and so on.
[0074] More concretely, in producing a double-sided
pressure-sensitive adhesive tape or sheet in the roll-wound form, a
roll-wound longitudinal support is used as the support.
Accordingly, it is preferable that the support to be used in the
step (B) or step (B1) is a roll-wound longitudinal support and that
in feeding the roll-wound longitudinal support and laminating the
pressure-sensitive adhesive layer formed on the release liner on
one surface of the support, a tension to be applied to the support
is less than 2 N. That is, the step (B) or step (B1) is preferably
the following step (B2).
[0075] Step (B2): A step of feeding the roll-wound longitudinal
support in the state that a tension to be applied to the support is
less than 2 N and laminating the pressure-sensitive adhesive layer
formed on the release liner on one surface of the support to form a
first pressure-sensitive adhesive layer on the support.
[0076] Incidentally, in producing a double-sided pressure-sensitive
adhesive tape or sheet in the roll-wound form, it is important that
the process includes not only the foregoing step (A), step (B2) and
step (C) but also the following step (D).
[0077] Step (D): A step of roll winding the laminate in such a
manner that the second pressure-sensitive adhesive layer is
superimposed on the release treatment surface of the other surface
of the release liner, to obtain a roll-wound double-sided
pressure-sensitive adhesive tape or sheet.
[0078] FIG. 2 is a schematic step view showing one embodiment of
the process of producing the double-sided pressure-sensitive
adhesive tape or sheet of the invention. In FIG. 2, 2 stands for a
release liner; 3 stands for a pressure-sensitive adhesive coating
unit; 4 stands for a drying or ultraviolet irradiation zone; 5
stands for a support; 6 stands for a lamination site; 7 stands for
a pressure-sensitive adhesive coating unit; 8 stands for a drying
or ultraviolet irradiation zone; and 9 stands for a double-sided
pressure-sensitive adhesive tape or sheet. The double-sided
pressure-sensitive adhesive tape or sheet 9 has a roll-wound form.
In the release liner 2, the both surfaces thereof are a release
treatment surface, and the release liner 2 has a roll-wound form.
The support 5 has a roll-wound form. Also, the pressure-sensitive
adhesive coating unit 3 is a coating unit for coating a
pressure-sensitive adhesive for forming the first
pressure-sensitive adhesive layer; and the pressure-sensitive
adhesive coating unit 7 is a coating unit for coating a
pressure-sensitive adhesive for forming the second
pressure-sensitive adhesive layer.
[0079] In the step view of the production process illustrated in
FIG. 2, in the step (A), the release liner 2 in the roll-wound form
is fed; a pressure-sensitive adhesive is coated on one surface of
the release liner 2 by the pressure-sensitive adhesive coating unit
3; and the pressure-sensitive adhesive is dried by the drying or
ultraviolet irradiation zone 4 to form a pressure-sensitive
adhesive layer which will become the first pressure-sensitive
adhesive layer on one surface of the release liner 2.
[0080] Also, in the step (B1) [or the step (B2)], the support 5 in
the roll-wound form is fed in the state that a tension (a feeding
tension) is less than 2 N so that a tension is not substantially
applied or not applied at all; and the pressure-sensitive adhesive
layer formed on the release liner 2 is laminated on one surface
(the surface in the lower side in FIG. 2) of the support 5 to form
the first pressure-sensitive adhesive layer on the support 5.
[0081] Further, in the step (C), a pressure-sensitive adhesive is
coated on the other surface of the support (the surface in the
upper side in FIG. 2) by the pressure-sensitive adhesive coating
unit 7; and the pressure-sensitive adhesive is dried by the drying
or ultraviolet irradiation zone 8 to form the second
pressure-sensitive adhesive layer on the support 5.
[0082] Moreover, in the step (D), the resulting material is wound
up in the rolled state in such a manner that the second
pressure-sensitive adhesive layer is superimposed on the release
treatment surface of the other surface of the release liner 2, to
obtain the roll-wound double-sided pressure-sensitive adhesive tape
or sheet 9.
[0083] Incidentally, in producing the double-sided
pressure-sensitive adhesive tape or sheet in the roll-wound form,
the double-sided pressure-sensitive adhesive tape or sheet can be
produced in the same production line as illustrated in FIG. 2. As a
matter of course, the step (A), the step (B1) [or the step (B2)],
the step (C), and the step (D) may be carried out partly in the
same production line. Alternatively, all of these steps may be
carried out using different production lines.
[0084] In the foregoing production process, the tension to be
applied to the support (in particular, the feeding tension to be
applied to the support in feeding the support in the roll-wound
form) can be adjusted by detecting a tension to be imparted to the
support by a tension detector and controlling a torque of a powder
brake via an automatic tension controller in such a manner that the
tension becomes a tension described later.
[0085] In this way, in laminating the pressure-sensitive adhesive
layer formed on the release liner on one surface of the support to
form the first pressure-sensitive adhesive layer on the support, by
adjusting a tension such as the tensile tension to be applied to
the support (in particular, the feeding tension in feeding the
roll-wound longitudinal support) at a level as low as possible, it
is possible to wind up the resulting material in the rolled state
in a cleaned state without generating wrinkles and so on, thereby
stably producing the double-sided pressure-sensitive adhesive tape
or sheet in the roll-wound form. Such a tension to be applied to
the support is not particularly limited so far as it is less than 2
N. For example, the tension can be selected within the range of
from 0 to 1.9 N, preferably not more than 1 N (for example, from 0
to 1 N), more preferably not more than 0.5 N (for example, from 0
to 0.5 N), and especially preferably not more than 0.3 N (for
example, from 0 to 0.3 N).
[0086] As a matter of course, after the step (B) [including the
step (B1) or step (B2)], the support becomes in the state that the
first pressure-sensitive adhesive layer and the release liner are
laminated in that order on one surface thereof, and in general, a
tension is not applied at all or not substantially applied to the
support, whereby the support becomes in the non-stretched state.
However, after the step (B) [including the step (B1) or step (B2)],
the tension to be applied to the support may become less than 2 N
or may become 2 N or more.
[0087] Incidentally, in the production of a pressure-sensitive
adhesive tape or sheet, in laminating a pressure-sensitive adhesive
layer formed on a release liner on one surface of a support (in
particular, on one surface of a support in feeding a roll-wound
longitudinal support) to form a pressure-sensitive adhesive layer
on the support, in general, a tension (in particular, a feeding
tension) of from about 2 to 10 N is applied to the support. For
this reason, in such case, if the thickness of the support is thin,
the support becomes in the stretched state by the foregoing
tension. If the tension applied to the support is released in the
subsequent step, the support is shrunk (contracted) from the
stretched state into the original state, whereby wrinkles and so on
are generated in the pressure-sensitive adhesive tape or sheet.
[0088] The double-sided pressure-sensitive adhesive tape or sheet
of the invention has an excellent strength even though its
thickness is thin. Also, it not only has a necessary thin thickness
but also holds a good strength without causing cutting at the time
of or during its use. Further, the double-sided pressure-sensitive
adhesive tape or sheet of the invention can be stably produced in
the longitudinal and roll-wound form nevertheless its thickness is
very thin and can be easily rewound with excellent workability.
Accordingly, the double-sided pressure-sensitive adhesive tape or
sheet of the invention can be provided in the longitudinal and
roll-wound form. For this reason, the double-sided
pressure-sensitive adhesive tape or sheet of the invention is
excellent with respect to the productivity in carrying out
continuous punching processing or automatic sticking.
[0089] Accordingly, the double-sided pressure-sensitive adhesive
tape or sheet of the invention can be utilized even though a space
between junction parts is in a thin region that has not been
employed so far in a junction measure utilizing a double-sided
pressure-sensitive adhesive tape or sheet.
[0090] The invention will be more specifically described below with
reference to the following Examples. Incidentally, in the following
Examples, the terms "parts" and "%" mean parts by weight and % by
weight, respectively.
Preparation Example 1 of Pressure-Sensitive Adhesive
[0091] 97 parts of n-butyl acrylate, 3 parts of acrylic acid, and
0.1 part of 2-hydroxyethyl acrylate were subjected to solution
polymerization for 6 hours in a mixed solution of toluene and ethyl
acetate [toluene/ethyl acetate (weight ratio)=1/1] using 0.2 part
of azobisisobutyronitrile as a polymerization initiator, to obtain
an acrylic polymer having a weight average molecular weight of
500,000. To 100 parts of the acrylic polymer, 30 parts of a
terpene-phenol based resin (a trade name: YS POLYSTER T130,
manufactured by Yasuhara Chemical Co., Ltd., softening point:
130.degree. C.) and 2 parts of an isocyanate based crosslinking
agent (a trade name: CORONATE L, manufactured by Nippon
Polyurethane Industry Co., Ltd.) were added and uniformly mixed
with stirring to prepare a pressure-sensitive adhesive (a
pressure-sensitive adhesive composition, which will be sometimes
referred to as "pressure-sensitive adhesive A").
EXAMPLE 1
[0092] Using the foregoing pressure-sensitive adhesive A, a
pressure-sensitive adhesive layer having a thickness of 0.004 mm
was formed on the both surfaces of a polyester film (a trade name:
C660-2.0W, manufactured by Mitsubishi Polyester Film Corp.,
thickness: 0.002 mm) as a support and wound up in the rolled state
to prepare a roll-wound double-sided pressure-sensitive adhesive
tape (total thickness: 0.010 mm, winding length: 50 m).
Specifically, in accordance with the production steps illustrated
in FIG. 2, the roll-wound double-sided pressure-sensitive adhesive
tape was prepared in the same production line in the following
manner.
[0093] First of all, a roll-wound release liner, the both surfaces
of which are a release treatment surface, was fed, and the
foregoing pressure-sensitive adhesive A was coated on the one-sided
release treatment surface of the release liner using a roll coater
and then dried at 100.degree. C. to form a pressure-sensitive
adhesive layer (a pressure-sensitive adhesive layer which will
become a first pressure-sensitive adhesive layer) having a
thickness of 0.004 mm.
[0094] Next, a roll-wound polyester film (a trade name: C660-2.0W,
manufactured by Mitsubishi Polyester Film Corp., thickness: 0.002
mm) as a support was fed at a feeding tension of 0.1 N, and the
pressure-sensitive adhesive layer formed on the foregoing release
liner was laminated on one surface of the polyester film in a
lamination portion, to form a first pressure-sensitive adhesive
layer on one surface of the polyester film as the support.
[0095] Subsequently, the foregoing pressure-sensitive adhesive A
was coated on the other surface of the foregoing polyester film
(the surface opposite to the surface on which the first
pressure-sensitive adhesive layer was formed) using a roll coater
and then dried at 100.degree. C. to form a second
pressure-sensitive adhesive layer (thickness: 0.004 mm).
[0096] Further, the resulting material was wound up in the rolled
state in such a manner that the second pressure-sensitive adhesive
layer came into contact with the other surface of the release liner
(the surface opposite to the surface on which the first
pressure-sensitive adhesive layer was formed), to prepare a
roll-wound double-sided pressure-sensitive adhesive tape (total
thickness: 0.010 mm, winding length: 50 m). Incidentally, the
tension in the winding portion in winding up the double-sided
pressure-sensitive adhesive tape was set up at 40 N.
EXAMPLE 2
[0097] A double-sided pressure-sensitive adhesive tape (total
thickness: 0.024 mm) was prepared in the same manner as in Example
1, except for using a polyester film (a trade name: K880-4.5W,
manufactured by Mitsubishi Polyester Film Corp., thickness: 0.004
mm) as the support, setting up the thickness of each of the
pressure-sensitive adhesive layers to be formed on the both
surfaces of the support at 0.010 mm, and setting up the winding
length of the double-sided pressure-sensitive adhesive tape at 200
m. Accordingly, the feeding tension in feeding the support is 0.1 N
the same as in Example 1. Also, the tension in the winding portion
in winding up the double-sided pressure-sensitive adhesive tape is
40 N the same as in Example 1.
EXAMPLE 3
[0098] A double-sided pressure-sensitive adhesive tape (total
thickness: 0.026 mm) was prepared in the same manner as in Example
1, except for using a polyester film (a trade name: K230-6E,
manufactured by Mitsubishi Polyester Film Corp., thickness: 0.006
mm) as the support, setting up the thickness of each of the
pressure-sensitive adhesive layers to be formed on the both
surfaces of the support at 0.010 mm, and setting up the winding
length of the double-sided pressure-sensitive adhesive tape at 200
m. Accordingly, the feeding tension in feeding the support is 0.1 N
the same as in Example 1. Also, the tension in the winding portion
in winding up the double-sided pressure-sensitive adhesive tape is
40 N the same as in Example 1.
COMPARATIVE EXAMPLE 1
[0099] A roll-wound release liner, the both surfaces of which are a
release treatment surface, was fed, and the foregoing
pressure-sensitive adhesive A was coated on the one-sided release
treatment surface of the release liner using a roll coater and then
dried at 100.degree. C. to form a pressure-sensitive adhesive layer
having a thickness of 0.010 mm. Thereafter, the resulting material
was wound up in the rolled state in such a manner that the
pressure-sensitive adhesive layer came into contact with the other
surface of the release liner (the surface opposite to the surface
on which the pressure-sensitive adhesive layer was formed), to
prepare a roll-wound double-sided pressure-sensitive adhesive tape
(total thickness: 0.010 mm, winding length: 200 m). Incidentally,
this double-sided pressure-sensitive adhesive tape is a
substrate-less double-sided pressure-sensitive adhesive tape.
COMPARATIVE EXAMPLE 2
[0100] A polyester film (a trade name: Lumirror #12, manufactured
by Toray Industries, Inc., thickness: 0.012 mm) as a support was
fed at a feeding tension of 50 N, and the foregoing
pressure-sensitive adhesive A was coated on the both surfaces of
the support using a roll coater and then dried at 100.degree. C. to
form pressure-sensitive adhesive layers (thickness of each
pressure-sensitive adhesive layer: 0.009 mm). Thereafter, one
release treatment surface of a release liner, the both surfaces of
which are a release treatment surface, was superimposed on the
one-sided pressure-sensitive adhesive layer, and the resulting
material was wound up in the rolled state in such a manner that the
other pressure-sensitive adhesive layer came into contact with the
other surface of the release liner, to prepare a roll-wound
double-sided pressure-sensitive adhesive tape (total thickness:
0.030 mm, winding length: 200 m). Incidentally, the tension in the
winding portion in winding up the double-sided pressure-sensitive
adhesive tape was set up at 40 N.
(Evaluation)
[0101] With respect to the double-sided pressure-sensitive adhesive
tapes according to Examples 1 to 3 and Comparative Examples 1 to 2,
the propriety of preparation of a rolled body, the adaptability of
a clearance, the adhesive strength, the breaking strength, and the
processability were respectively measured or evaluated in the
following measurement methods or evaluation methods. The evaluation
results are shown in Table 1.
(Evaluation Method of the Propriety of Preparation of a Rolled
Body)
[0102] In Examples 1 to 3 and Comparative Examples 1 to 2, whether
or not a roll-wound double-sided pressure-sensitive adhesive tape
could be prepared in a good state was judged. The case where the
preparation was possible was evaluated as ".largecircle.", and the
case where the preparation was impossible was evaluated as "X",
respectively. The evaluation results are shown in the row of
"Propriety of preparation of rolled body" in Table 1.
(Evaluation Method of Adaptability of a Clearance)
[0103] Each of the double-sided pressure-sensitive adhesive tapes
obtained in Examples 1 to 3 and Comparative Examples 1 to 2 was
applied to a portion having a clearance of not more than 0.03 mm
between parts and judged on whether or not it could be adapted to
the clearance. The case where the double-sided pressure-sensitive
adhesive tape could be adapted was evaluated as ".largecircle.",
and the case where it could not be adapted was evaluated as "X",
respectively. The evaluation results are shown in the row of
"Adaptability of clearance" in Table 1.
(Measurement Method of Adhesive Strength)
[0104] Each of the double-sided pressure-sensitive adhesive tapes
obtained in Examples 1 to 3 and Comparative Examples 1 to 2 was cut
into a width of 20 mm to prepare a specimen. With respect to the
specimen (20 mm in width), a peel adhesive strength (release angle:
180.degree., tensile rate: 300 mm/min, 23.degree. C..times.65% RH,
adherend: stainless steel plate) was measured using a tensilon
tensile tester according to JIS Z-0237. The measurement results are
shown in the row of "Adhesive strength (N/20 mm)" in Table 1.
(Measurement Method of Breaking Strength)
[0105] Each of the double-sided pressure-sensitive adhesive tapes
obtained in Examples 1 to 3 and Comparative Examples 1 to 2 was cut
into a width of 10 mm, and the surface thereof was given gauge
marks at intervals of 50 mm to prepare a specimen (10 mm in width).
The specimen was stretched under conditions at room temperature
(23.degree. C.) and at 65% RH and under conditions at a chuck
distance of the specimen of 50 mm and at a tensile rate of 200
mm/min using a tensile tester, and a load (stress) at the time when
the specimen broke (at the time when a crack was generated from at
least a part thereof) was measured and defined as the breaking
strength (MPa). The measurement results are shown in the row of
"Breaking strength (MPa)" in Table 1.
[0106] Incidentally, since the double-sided pressure-sensitive
adhesive tape according to Comparative Example 1 is of a
substrate-less type, the breaking strength thereof was extremely
small, i.e., it was a small value such that it could not be
substantially measured.
(Processability)
[0107] Each of the double-sided pressure-sensitive adhesive tapes
obtained in Examples 1 to 3 and Comparative Examples 1 to 2 was
subjected to sealing processing with a prescribed dimension and
evaluated with respect to the release workability and blocking
property after processing. The case where the release workability
was good at the time of processing, and the cut section did not
adhere was evaluated as ".largecircle.", and the case where the
release workability was poor at the time of processing, or the cut
section adhered was evaluated as "X", respectively. The evaluation
results are shown in the row of "Processability" in Table 1.
TABLE-US-00001 TABLE 1 Comparative Example Example 1 2 3 1 2 Total
thickness (mm) 0.010 0.024 0.026 0.010 0.030 Propriety of
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. preparation of rolled body Adaptability of
.largecircle. .largecircle. .largecircle. .largecircle. X clearance
Adhesive strength 6.0 7.0 7.5 4.5 7.5 (N/20 mm) Breaking strength
4.4 8.8 13.1 Impossible 26.3 (MPa) for measurement Processability
.largecircle. .largecircle. .largecircle. X .largecircle.
[0108] As is clear from Table 1, nevertheless the double-sided
pressure-sensitive adhesive tapes according to the Examples are
extremely thin as less than 0.03 mm, they can be wound up in a good
state into a rolled body and adapted to a portion where a clearance
between parts becomes not more than 0.03 mm. Also, the double-sided
pressure-sensitive adhesive tapes according to the Examples are
good with respect to the adhesive strength and breaking strength
and excellent with respect to the processability. Accordingly, it
has been confirmed that when the double-sided pressure-sensitive
adhesive tapes according to the Examples are used, there give rise
to remarkable effects such that not only they can cope with a
requirement for realization of a thin layer in a junction site by a
double-sided pressure-sensitive adhesive tape, but also they can
achieve the both of workability and economy (cost performance) at
excellent levels.
[0109] While the invention has been described in detail and with
reference to specific embodiments thereof, it will be apparent to
one skilled in the art that various changes and modifications can
be made therein without departing from the spirit and scope
thereof.
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