U.S. patent application number 11/397403 was filed with the patent office on 2007-05-03 for thin films and fabrication method therefor.
This patent application is currently assigned to DAXON TECHNOLOGY INC.. Invention is credited to Chung Neng Fu, Chun Hung Lin, Cheng Hsin Tsai.
Application Number | 20070096367 11/397403 |
Document ID | / |
Family ID | 37995222 |
Filed Date | 2007-05-03 |
United States Patent
Application |
20070096367 |
Kind Code |
A1 |
Tsai; Cheng Hsin ; et
al. |
May 3, 2007 |
Thin films and fabrication method therefor
Abstract
A thin film. The thin film is fabricated by placing a thin film
having a hydroxyl groups-containing surface in a water tank
containing dicarboxylic acid and stretching the thin film.
Inventors: |
Tsai; Cheng Hsin; (Taoyuan
City, TW) ; Fu; Chung Neng; (Taoyuan County, TW)
; Lin; Chun Hung; (Taipei County, TW) |
Correspondence
Address: |
QUINTERO LAW OFFICE, PC
2210 MAIN STREET, SUITE 200
SANTA MONICA
CA
90405
US
|
Assignee: |
DAXON TECHNOLOGY INC.
TAOYUAN
TW
|
Family ID: |
37995222 |
Appl. No.: |
11/397403 |
Filed: |
April 4, 2006 |
Current U.S.
Class: |
264/289.6 ;
264/340 |
Current CPC
Class: |
B29C 55/06 20130101;
B29K 2029/04 20130101 |
Class at
Publication: |
264/289.6 ;
264/340 |
International
Class: |
D02J 1/22 20060101
D02J001/22 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 27, 2005 |
TW |
TW94137663 |
Claims
1. A method for fabricating a thin film, comprising: placing a thin
film having a hydroxyl groups-containing surface in a water tank
containing dicarboxylic acid; and stretching the thin film.
2. The method for fabricating a thin film as claimed in claim 1,
further comprising swelling the thin film.
3. The method for fabricating a thin film as claimed in claim 1,
further comprising dying the thin film with an iodine solution.
4. The method for fabricating a thin film as claimed in claim 3,
wherein the iodine solution comprises molecular iodine and iodide
ions.
5. The method for fabricating a thin film as claimed in claim 1,
wherein the dicarboxylic acid has 4.about.6 carbons.
6. The method for fabricating a thin film as claimed in claim 1,
wherein the dicarboxylic acid is adipic acid.
7. The method for fabricating a thin film as claimed in claim 1,
wherein the dicarboxylic acid has a weight percentage of about
1.about.10%.
8. The method for fabricating a thin film as claimed in claim 1,
wherein the dicarboxylic acid has a weight ercentage of about
2.about.5%.
9. The method for fabricating a thin film as claimed in claim 1,
further comprising adding transition metal ions, hydrochloric acid,
sulfuric acid, or boric acid to the water tank.
10. The method for fabricating a thin film as claimed in claim 9,
wherein the transition metal ions comprise zinc ions.
11. The method for fabricating a thin film as claimed in claim 9,
wherein the transition metal ions have a weight percentage of about
0.1.about.3%.
12. The method for fabricating a thin film as claimed in claim 9,
wherein the boric acid has a weight percentage of about
1.about.3%.
13. The method for fabricating a thin film as claimed in claim 1,
wherein the water tank has an operating temperature of about
40.about.60.degree. C.
14. The method for fabricating a thin film as claimed in claim 1,
further comprising laminating at least one protective film on the
thin film.
15. The method for fabricating a thin film as claimed in claim 14,
wherein the protective film comprises triacetyl cellulose (TAC),
polyethylene terephthalate (PET), or polynorbornene.
16. The method for fabricating a thin film as claimed in claim 1,
wherein the thin film has a stretching ratio of about
6.about.9.
17. The method for fabricating a thin film as claimed in claim 1,
wherein the thin film has a thickness of about 10.about.20
.mu.m.
18. The method for fabricating a thin film as claimed in claim 1,
wherein the thin film has a thickness ratio (original/stretched) of
about 4.about.8.
19. The method for fabricating a thin film as claimed in claim 1,
wherein the thin film has a width ratio (original/stretched) of
about 1.5.about.2.
20. The method for fabricating a thin film as claimed in claim 1,
wherein the thin film is a polyvinyl alcohol polarization film.
21. A thin film formed by the fabrication method as claimed in
claim 1.
Description
BACKGROUND
[0001] The invention relates to a thin film, and more specifically
to a thin polarization film and a method of fabricating the
same.
[0002] In recent years, there has been an increasing demand for
polarization films because of wide use of liquid crystal displays
(LCD) in various apparatuses such as word processors, monitors,
cell phones, and liquid crystal televisions. Specifically, larger
LCD TVs show a growing trend due to increasing popularity of family
entertainment systems. Thus, it is necessary to develop thin and
wide polarization films to meet the market requirements.
[0003] Polyvinyl alcohol (PVA) polarization films are generally
categorized into iodine-type films where iodine is adsorbed on a
properly oriented PVA film, dye-type films where a dichroic dye is
adsorbed rather than iodine, and polyene-type films obtained by
partial dehydration.
[0004] Among these, iodine-type film is most widely used due to
ease of manufacture and excellent optical performance. A polarizer
generally comprises a central stretched PVA film and at least one
protective layer, typically of triacetyl cellulose (TAC). The
stretched and dried PVA film is a main polarizing element, with a
thickness commonly around 20.about.35 .mu.m and a stretching ratio
of about 5.about.6, most often 5.8. The conventional abovesaid PVA
polarization film, however, is thick, narrow, and has a
low-stretching-ratio, resulting in low utilization yield thereof,
even with an extremely high width ratio (original/stretched) of
2.about.2.5, fully unsatisfied to the requirement of large-sized
panels.
[0005] U.S. Pat. No. 6,760,156 and 6,855,276 provide methods for
increasing optical properties and uniformity of films by dry
processes. A stretching ratio of 5.about.7 can be achieved. Few
efforts, however, are put to increase the stretching ratio/width
and decrease the thickness of the resulted polarizing element.
Thus, a thin and high stretching ratio/width stretched PVA film is
desired to achieve the maximum material utilization yield.
SUMMARY
[0006] The invention provides a method for fabricating a thin film,
in which a thin film having a hydroxyl groups-containing surface is
placed and stretched in a water tank containing dicarboxylic
acid.
[0007] The invention also provides a thin film fabricated by the
disclosed method.
[0008] A detailed description is given in the following embodiments
with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The invention can be more fully understood by reading the
subsequent detailed description and examples with references made
to the accompanying drawings, wherein:
[0010] FIG. 1 shows chemical bonding between dicarboxylic acid and
boric acid and a polyvinyl alcohol film surface.
[0011] FIG. 2 shows a result of thermal mechanical analysis (TMA)
of the polarizer fabricated by example 4 of the invention.
[0012] FIG. 3 shows an extending path of a polarization film in an
extending tank of the invention.
[0013] FIG. 4 shows another extending path of a polarization film
in an extending tank of the invention.
DETAILED DESCRIPTION
[0014] The invention provides a method for fabricating a thin film,
in which a thin film having a hydroxyl groups-containing surface is
placed and stretched in a water tank containing dicarboxylic
acid.
[0015] The thin film having a hydroxyl groups-containing surface
may be a polyvinyl alcohol film.
[0016] The thin film may further be swollen and dyed with an iodine
solution containing molecular iodine and iodide ions. The molecular
iodine has a weight percentage of about 0.01.about.0.1% and the
iodide ions a weight percentage of about 0.1.about.10%.
[0017] The dicarboxylic acid may have 4.about.6 carbons, such as an
adipic acid. The dicarboxylic acid has a weight percentage of about
1.about.10%, preferably 2.about.5%. In addition to dicarboxylic
acid, transition metal ions such as zinc, hydrochloric acid,
sulfuric acid, or boric acid, are further added to the water tank
(extending tank). The transition metal ion has a weight percentage
of about 0.1.about.3% and the boric acid has a weight percentage of
about 1.about.3%. The extending tank has an operating temperature
of about 40.about.60.degree. C.
[0018] In the invention, traditional boric acid bonded to the
polyvinyl alcohol film surface is replaced by the dicarboxylic
acid, as shown in FIG. 1. The hydrophilic carboxyl groups of the
dicarboxylic acid easily bond to the hydroxyl groups of the
polyvinyl alcohol film surface to form ester bonds therebetween.
Compared to the rigid boric acid, the long-chain dicarboxylic acid
having 4.about.6 carbons is flexible, thus increasing tenacity and
extensibility of the thin polarization film, without breakage
during stretching. Also, to improve chemical reactivity and
properties of the film stretched and avoid discoloration, additives
such as transition metal ions, hydrochloric acid, sulfuric acid, or
boric acid are added to the extending tank.
[0019] A thin, wide, and high-stretching-ratio polarization film is
formed by adjusting various stretching parameters such as operating
temperature, extending path, rotation rate of nip roller, and
concentrations of dicarboxylic acid and additives.
[0020] After the polarization film is formed, at least one
protective film (optical film), such as triacetyl cellulose (TAC),
polyethylene terephthalate(PET), or polynorbornene, is laminated
thereto.
[0021] The invention also provides a thin film fabricated by the
disclosed method. The thin film is suitable for use in a variety of
liquid crystal displays, for example, GPS system screens mounted in
cars.
[0022] The stretched polarization film has a stretching ratio of
about 6.about.9, a thickness of about 10.about.20 .mu.m, a
thickness ratio (original/stretched) of about 4.about.8, and a
width ratio (original/stretched)-of-about 1.5.about.2.
EXAMPLE 1
[0023] A polyvinyl alcohol film with 650 mm width and 75 .mu.m
thickness was swollen in a water tank. Next, the polyvinyl alcohol
film was dyed with an iodine solution. Next, referring to FIG. 3,
the polyvinyl alcohol film 30 was stretched in an extending tank 10
containing 3% adipic acid, 1% boric acid, and 0.15% zinc ion to
form an extended polyvinyl alcohol polarization film. The rotation
rates of the nip rollers 20 were 1:1.5:1.55, respectively, and the
extending path was shown in FIG. 3. The operating temperature was
53.degree. C. Finally, a polarization film with a stretching ratio
of 7.24, a thickness of 12 .mu.m, and a width of 380 mm was
obtained after being stretched and dried.
EXAMPLE 2
[0024] A polyvinyl alcohol film with 650 mm width and 75 .mu.m
thickness was swollen in a water tank. Next, the polyvinyl alcohol
film was dyed with an iodine solution. Next, referring to FIG. 3,
the polyvinyl alcohol film 30 was stretched in an extending tank 10
containing 3% adipic acid, 1% boric acid, and 0.15% zinc ion to
form an extended polyvinyl alcohol polarization film. The rotation
rates of the nip rollers 20 were 1:1.45:1.5, respectively, and the
extending path was shown in FIG. 3. The operating temperature was
53.degree. C. Finally, a polarization film with a stretching ratio
of 6.77, a thickness of 17 .mu.m, and a width of 342 mm was
obtained after being stretched and dried.
EXAMPLE 3
[0025] A polyvinyl alcohol film with 650 mm width and 75 .mu.m
thickness was swollen in a water tank. Next, the polyvinyl alcohol
film was dyed with an iodine solution. Next, referring to FIG. 4,
the polyvinyl alcohol film 60 was stretched in an extending tank 40
containing 3% adipic acid, 1% boric acid, and 0.15% zinc ion to
form an extended polyvinyl alcohol polarization film. The rotation
rates of the nip rollers 50 were 1:1.5:1.5, respectively, and the
extending path was shown in FIG. 4. The operating temperature was
53.degree. C. Finally, a polarization film with a stretching ratio
of 7.00, a thickness of 11.5 .mu.m, and a width of 418 mm was
obtained after being stretched and dried.
EXAMPLE 4
[0026] A polyvinyl alcohol film with 650 mm width and 75 .mu.m
thickness was swollen in a water tank. Next, the polyvinyl alcohol
film was dyed with an iodine solution. Next, referring to FIG. 4,
the polyvinyl alcohol film 60 was stretched in an extending tank 40
containing 3% adipic acid, 1% boric acid, and 0.15% zinc ion to
form an extended polyvinyl alcohol polarization film. The rotation
rates of the nip rollers 50 were 1:1.45:1.5, respectively, and the
extending path was shown in FIG. 4. The operating temperature was
53.degree. C. Finally, a polarization film with a stretching ratio
of 6.77, a thickness of 14.5 .mu.m, and a width of 385 mm was
obtained after being stretched and dried.
[0027] The polarization film was then laminated with two TAC films
(pre-etched with strong base) and dried at 70.degree. C. to form a
polarizer. Next, the polarizer was subjected to thermal mechanical
analysis (TMA) at 80.degree. C. for 30 min. Compared to similar
samples on market (90.about.110 .mu.m), the contraction quantity
thereof was 47.93 .mu.m, as shown in FIG. 2.
COMPARATIVE EXAMPLE 1
[0028] A polyvinyl alcohol film with 650 mm width and 75 .mu.m
thickness was swollen in a water tank. Next, the polyvinyl alcohol
film was dyed with an iodine solution. Next, the polyvinyl alcohol
film was stretched in an extending tank containing 5% boric acid to
form an extended polyvinyl alcohol polarization film. The rotation
rates of the nip rollers were 1:1.4:1.33, respectively. The
operating temperature was 53.degree. C. Finally, a polarization
film with a stretching ratio of 5.8, a thickness of 24 .mu.m, and a
width of 340 mm was obtained after being stretched and dried.
[0029] Stretching ratios, thicknesses, widths, thickness ratios
(original/stretched), and width ratios (original/stretched) of
various polarization films formed by examples 1.about.4 and
comparative example 1 are compared in Table 1. TABLE-US-00001 TABLE
1 Stretching Thickness ratio (.mu.m) Width (mm) R.sub.T R.sub.W
Example 1 7.24 12.0 380 6.25 1.72 Example 2 6.77 17.0 342 4.41 1.89
Example 3 7.00 11.5 418 6.52 1.56 Example 4 6.77 14.5 385 5.17 1.69
Comparative 5.80 24.0 340 3.13 1.91 Example 1 R.sub.T = thickness
ratio (original/stretched) R.sub.W = width ratio
(original/stretched)
[0030] The results indicate that the polarization film provided by
the invention has a higher stretching ratio, thickness of only
around 10.about.20 .mu.m, and increased width after being
stretched, thus significantly improving material utilization
yield.
[0031] While the invention has been described by way of examples
and in terms of preferred embodiment, it is to be understood that
the invention is not limited thereto. To the contrary, it is
intended to cover various modifications and similar arrangements
(as would be apparent to those skilled in the art). Therefore, the
scope of the appended claims should be accorded the broadest
interpretation so as to encompass all such modifications and
similar arrangements.
* * * * *