Note: Descriptions are shown in the official language in which they were submitted.
1327727
Technical Field
The present invention relates to a mesh fabric useful
for a printing screen which consists essentially of conjugate
filaments.
Back~round of the Invention
In the past, as fabrics for printing screens, silk or
stainless-steel mesh fabrics have been broadly used. However,
the silk mesh fabrics were deficient in the strength and the
dimensional stability for a printing screen. As regards the
stainless steel mesh fabrics, severe problems were found in the
elastic recovery and the instantaneous repelling force when a
squeegee was applied. Further, silk and stainless are expensive.
Recently, for the above reasons, polyester or nylon
mesh fabrics have been more used for printing screens. Particularly,
the polyester mesh fabrics have been more preferred from the
viewpoint of the high dimensional stability. However, the
polyester mesh fabrics have the following disadvantages:
a) White-powdery scum is generated during the weaving,
which will cause many troubles.
" 1327727
b) The emulsion-coating properties is low.
C) For forming a coating film at a constant thickness,
skillful techniques and several overlap coatings are
required.
d) The production efficiency is low.
e) The adhesion of the meshes to an emulsion resin is
insufficient. The printing durability is low.
In attempt to solve the above problems, various ways
utilizing chemical treatment with acids or alkalies or the like,
flame treatment, corona-discharge treatment, and so forth have
been examined. However, various troubles such as reduction in
the strength of the material and so forth have arised. The test
results of the screens prepared in such ways have been unsatis-
factory for practical application.
On the other hand, with diversification in the printing
fields, high printing precision and high printing durability have
been more required. Particularly, it is needed to develop a
screen which has a high dimensional stability comparable to
that of a stainless-steel screen, a high adhesion to an emulsion
resin comparable to that of a nylon screen, and a high elastic
recovery property comparable to that of a polyester screen.
Japanese Laid-Open Patent Publication No. 142,688 of
1984 discloses an anti-static mesh fabric made rom conjugate
filaments. The anti-static mesh fabric is characteristic in
that it is made from a thermoplastic synthetic polymer added with
electro-conductive carbon black. An ob;ect of that lies in an
., ~ . , .
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1327727
improvement in the antistatic property of a screen mesh
fabric. However, there is not taught any way for
improvement of printing precision and printing durability
which have been much desired as described above.
Accordingly, an object of this invention is to
provide a mesh fabric useful for a printing screen having
high dimensional stability, adhesion to an emulsion resin
and elastic recovery property, that is, having high
printing precision and printing durability.
Disclosure of the Invention
According to the present invention, there is
provided a mesh fabric for a printing screen coated with an
emulsion resin, comprising a plurality of conjugate
filaments each having a core and a sheath formed around the
core. The material of the sheath has a high adhesion for
the emulsion resin and the material of the core has a high
dimensional stability and elastic recovery. The mesh
fabric has a breaking elongation in the range of 15 to 40%
and a breaking strength of not less than 25 kgf. A
correlation between the strength Y(kgf) and the elongation
X(%) in the elongation range of not less than 5~, in a
stress-strain curve by a labelled strip method at a
specimen width of 5 cm and a grip interval of 20 cm,
satisfies the following formula:
Y = (X + 1) x 5 / 3.
The desired end of this invention can be achieved
by using different synthetic fibre materials as a conjugate
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filament to act usefully whereby the composite filament can
be provided only the good properties of each materials.
As the material of the core, polyesters, polyolefins
or the like having a high dimensional stability and an elastic
recovery property are used to afford screens having high
dimensional stability. As the material of the sheath,
polyamides, low ~iscosity type polyesters or the like having
a high adhesive property to resins are used to present
generating white-powdery scum as often found during the
weaving of conventional polyester screens and to afford
screens having high strength and emulsion-coating properties
and ink-squeezing properties.
Accordingly, the mesh fabric of the invention can
always be produced with high efficiency and can be used to
produce printing screens having high printing precision and
printing durability.
As understood from the preceding, the present mesh
fabric is so designed as to have the strength and the elonga-
tion within the above-described range, typically by selecting
materials for the conjugate filament and heat-setting the
mesh fabric, whereby the workability of the mesh fabric during
the stretching stage for producing a screen, the dimensional
stability of the screen, and the high-tension printing
durability of the screen during the printing stage are~remarkably
enhanced, which enables the present mesh fabric to be applied
for high precision printing.
_ 4 _
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132772~
One of the characteristics of the present mesh
fabric lies in that it has such an appropriate breaking
elongation for a printing screen as is unobtainable with
conventional stainless-steel mesh fabrics, and the breaking
strength considerably higher than that of conventional
synthetic fibre mesh fabrics, and has such a low elongation
and a high strength ~hat the stress-strain curve satisfies the
formula y 2 (X + 1) x 5 / 3 where Y designates the strength
(kg-f) and X the elongation (%), in the range of the elonga-
tion of not less than 5%. Accordingly, the present mesh
fabric is applicable for producing a printing screen having
a small elongation at a high tension. Typically, the present
mesh fabric affords to produce a high-tension printing
screen having a tension of not more than 0.6 by measurement
with a Type 75 B tension gauge (made by Sun Giken), which is
unobtainable with conventional synthetic fibre mesh iabrics,
with high workability.
Polyester or polyolefin which constitutes the core
of the conjugate filament used in the invention must be a
material of which the viscosity at a spinning temperature
depending of the typ~ of the material is appropriate for
the spinning.
As the polyester, there may be used polyalkylene-
terephthalate, polyalkylene-telephthalate copolymer, poly[l,4-
cyclohexanediol-terephthalate] and the like. From the
viewpoint of the high dimensional stability of the mesh
fabric needed for the heat-setting in the processing stage
-- 5 --
132772~
after the weaving, polyethyleneterephthalate, polybutylene-
terephthalate, and poly [1,4-cyclohexanediol terephthalate]
are preferable. Polyethyleneterephthalate is most preferred
from the economical viewpoint.
As the polyolefins, there may be used polyethylene,
polypropylene, polybutene-l and the like.
Polyethylene and polypropylen are preferable,
because of the high stability during the spinning and the
easy handling. Polypropylene, which is effective in a
relatively wide range of the spinning temperature, is most
preferable.
On the other hand, as the polyamides constituting
the sheath of the conjugate filament, there may be used
aliphatic polyamides such as 6-nylon, 6,6-nylon, 6,10-nylon,
12-nylon 12, condensation polyamides of para-aminocyclohexyl-
methane and dodecanedioic acid; and aromatic polyamides such
as polyxylyleneadipamide, polyhexyamethylenephthalamide and
the like. 6-nylon and 6,10-nylon are preferably used from
the economical viewpoint and for the easy spinning.
As regards the constitution of the conjugate filament,
it is important that the sheath is continuously present in the
whole periphery of the con~ugate filament without the core
exposed to the surface. The conjugate filament may be circular
in the section. Particular restrictions are not imposed on
the arrangement and shape of the core. The core may be
single- or multi-core, circular or profile in the section,
and concentric or eccentri.c. From the viewpoint of the
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dimensional stability, it is preferred that the filament
contains concentrically a single-core with a circular section,
or contains a type of multi-cores each having a circular section,
since such arrangement and shape prevents effectively an applied
stress from being distributed in the filament.
Preferably, the volume ratio of core to sheath is in
the range of from 1 : 5 to 3 : 1, and more preferably in the
range from 1 : 2 to 2 : 1. If the volume ratio of core to
sheath is inadequately high, the sheath film is relatively thin,
so that irregularities in the thickness of the film will occur
during the spinning and cause breakage of the film, which leads
to breakage of the film when it undergoes an external stress
during the weaving, the mesh fabric stretching on frame, or
the printing. If the volume ratio of the core to the sheathis
inadequately small, the conjugate filament will have an
insufficient resistance to tensile stress, which brings a
deficiency in the dimensional stability to the screen.
The conjugate filament is applicable in form of a
monofilament or a multi-filament in this invention. For the
purpose of obtaining a screen having high printing precision,
the conjugate filament in form of a monofilament is generally
preferred. The size of the filament is preferably not less
than 1 denier, and more preferably in the range of from 5 to
50 deniers. The preferable diameter of the filament is not
more than lOO~um.
For weaving, the conjugate filament is generally
used as a drawn yarn. For ensuring the dimensional stability
1327727
of the screen, the drawing ratio and the heat set temperature
is set so that the strength of the drawn filament is not
less than 5.5 g/d, and the residual elongation is in the
range of from 30% to 50%, and the heat shrinkage is not more
than 10%. Preferably, the drawn yarn has a strength of not
less than 6 g/d, the residual elongation of from 35% to
45%, and a boiling water shrinkage of not more than 9~.
In general, the density of the mesh fabric is in
the range of from 10 to 600 per inch (that is, 100 - 600
mesh plain weave). Depending on the nature of the screen,
that is, the supply amount of printing ink, the line width of
pattern and so forth, an adequate density needs to be selected.
A preferred density is in the range of from 100 to 350 per inch.
The raw fabric obtained by weaving the conjugate
filaments is washed with an aqueous solution of a nonionic or
anionic surface active agent, and heat-set at a temperature
of from 100C to 190C with a tension of from 100 to250 kg to
obtain the desired thickness and mesh number.
After the heat-setting, the mesh fabric is cleaned
in the surface, dried and subjected to the stretching stage
for fixing the mesh fabric to the frame of a screen. The
present mesh fabric may be applied for any frame of aluminum,
iron, wood and re8in.
The mesh fabric of the invention, obtained from
the above-mentioned conjugate filaments, undergoes substantially
no changes in the quality with the lapse of time. Accordingly,
the mesh fabric is applicable to the following coating stage
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using a photosensitive or heat-sensitive resin emulsion
after being left for 24 hours from being fixed on the frame
as mentioned above. Using the mesh fabric, the workability
for producing a screen stencil can be remarkably improved.
On the other hand, the conventional nylon mesh fabrics,
when stretched on the frame of a screen, suffer significant
changes in the quality with the lapse of time, and are
unsuitable for precision screen printing. Also, conventional
polyester mesh fabrics need to be left as they are for more
than 72 hours from the stretching stage, because of the large
change in the quality with the lapse of time.
For producing a screen stencil, commercially available
photosensitive or heat sensitive resin emulsions are applicable
to the mesh fabric of the invëntion. As the photosensitive
agent, dichromates such as ammonium dichromate and the like,
diazo compounds are applicable. As the emulsion resin, gelatin,
gum arabic, vinylalcohol, vinylacetate, acrylic resin and
mixtures thereof are applicable. Additives such as an
emulsifier, an anti-static agent and the like may be added in
the emulsion.
Although the coating thickness of an emulsion applied
to the mesh fabric will be varied, depending on the desired
nature of the screen, the mesh fabric according to the invention,
the surface of which is covered with apolyamide having high
adhesive property to the emulsion to be applied, is significantly
improved in the emulsion coating property, as compared with
conventional polyester mesh fabrics, so that a resin layer
uniform in the thickness can be easilly formed thereon.
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In the ordinary way, an emulsion is applied to the
mesh fabric to a predetermined thickness, dried and then
exposed to light or heated for obtaining a screen stencil.
For curing the resin in a pattern, generally, high voltage
mercury lamps, xenon lamps (about 4 kw) are used as the light
source. The distance between the light source and the screen
is in the range of from 1 to 1.5 m, and the exposure time is in
the range of from 2 to 5 minutes. The integrated quantity of
light is in the range of from 300 to 500 milli-jules/cm2.
The screen stencil obtained with the mesh fabric of
the invention as described above is improved in the dimensional
stability and the elastic recovery property, and has high
printing precision and printing durability. For preventing
blurring or fogging of the pattern formed on the screen which
is caused by halation when the screen is exposed to light
according to the process, it is preferred that the conjugate
filament i8 treated in such a manner that at least the surface
of the core of the conjugate filament is rendered light-
absorptive to the exposure light during the process.
The above-mentioned light-absorptive property may
be given by dyeing the mesh fabric after the weaving by dope-
coloring the sheath material of the conjugated filament with
pigments or dyes or by incorporating a ultra-violet ray
absorbing agent in the sheath material of the conjugate
filament.
The mesh fabrics obtained from conventional polyester
filaments need to be high-pressure dyed for the dyeing,
accompanied with low production efficiency. Further, the mesh
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1327727
fabrics are ready to undergo heat shrinking during the high-
pressure dyeing and have foreign matters adhere to the surface
thereof. Accordingly, the conventional mesh fabrics are
unsuitable for producing a printing screen having a fine
pattern with high efficiency.
However, according to the invention, since the
conjugate filament in which the sheath is a polyamide having
a good dyeing property can be used, the filament can be dyed
under the ordinary pressure. Accordingly, the mesh fabric
according to the invention can be rendered halation-preventive
to the exposure light in the photometrical process, without
substantial shrinking of the fabric and without substantial
foreign materials adhered to the surface during the dyeing
process.
Further, in the invention, a pigment or an ultraviolet
ray absorbing agent may be incorporated in the sheath material
of the conjugate filament to obtain the mesh fabric having a
stable halation-preventive property without dyeing. In this
case, since the desired effect can be obtained by incorporating
the pigment or the like only in the sheath material of the
conjugate filament, there can be very economically produced a
screen stencil having good halation-preventive property without
heat-shrinking of the mesh fabric and without foreign materials
adhered to the surface of the filament. Accordingly, screen
stencils having fine patterns with high density can be precisely
produced.
Generally, the wavelength of the light employed in
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1327727
the photometrical process has a peak within the range of 280
to 450 nm. It is preferred that the conjugate filament is
treated in such a manner as to have a light absorptive
property to the light within the weavelength range of 280
to 450 nm, depending on the light employed in the photometrical
process.
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Brief Description of the Drawin~s
Fig. 1 illustrates, in graphical comparison, the
stress-strain curves of a mesh fabric with the mesh size of
150 made of conjugate monofilaments (fibre diameter 48~um)
according to the invention and a mesh fabric with the mesh
size of 150 made of polyester filaments (fibre diameter:
48Jum).
Fig. 2 illustrates, in graphical comparison, the
stress-strain curves of a mesh fabric with the mesh size of
200 made of conjugate monofilaments (fibre diameter: 48Jum)
according to the invention and a mesh fabric with the mesh
size of 200 made of polyester filaments (fibre diameter:
48Jum).
Fig. 3 illustrates, in graphical comparison, the
stress-strain curves of a mesh fabric with the mesh size of
250 made of conjugate monofilaments (fibre diameter: 40~um)
according to the invention and a mesh fabric with the mesh
size of 250 made of polyester filaments (fibre diameter:
40Jum).
Fig. 4 illustrates, in graphical comparison, the
stress-strain curves of a mesh fabric with the mesh size of
270 made of conjugate monofilaments ~ibre diameter: 34~um)
according to the invention and a mesh fabric with the mesh
size of 270 made of polyester filaments (fibre diameter:
34~um)
Fig. 5 illustrates, in graphical comparison, the
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stress-strain curves of a mesh fabric with the mesh size of
300 made of conjugate monofilaments (fibre diameter: 34 ~m)
according to the invention and a mesh fabric with the mesh
size of 300 made of polyester filaments (fibre diameter:
34~um).
Fig. 6 illustrates graphically a correlation between
the load and the deformation of the fibres.
Fig. 7 shows a microscope photograph (magnification:
500) of a mesh fabric with the mesh size of 250 made of dope-
dyed conjugate monofilaments.
Fig. 8 shows a microscope photograph (magnification:
500) of a dyed mesh fabric with the mesh size of 250 made of
conjugate monofilaments.
Fig. 9 shows a microscope photograph (magnification:
500) of a dyed mesh fabric with the mesh size of 250 made of
polyester monofilaments.
Fig. 10 shows a microscope photograph (magnification:
500) of a printing screen produced by processing a mesh fabric
with the mesh Rize of 300 made of dope-dyed conjugate mono-
filament 8 .
Fig. 11 shows a microscope photograph (magnification:
500) of a printing screen produced by processing a dyed mesh
fabric with the mesh size of 300 made of conjugate monofilaments.
Fig. 12 shows a microscope photograph (magnification:
500) of a printing screen produced by processing a dyed mesh
fabric with the mesh size of 300 made of polyester monofilaments.
Fig. 13 shows a microscope photograph (magnification:
500) of a printing screen produced by processing an uncolored
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mesh fabric with the mesh size of 300 made of conjugate
monofilaments.
Fig. 14 shows a microscope photograph (magnification:
500) of a printing screen produced by processing an uncolored
mesh fabric with the mesh si~e of 300 made of conjugate
monofilaments.
Detailed Description of the Preferred Embodiments
The invention will be illustrated by way of the
following examples which are for the purpose of illustrat'ion
only and are in no way to be considered as limiting.
Example 1
Circular-sec~ion concentric conjugate filaments
comprising a 6 nylon sheath and a polyethyleneterephthalate
core in the volume ratio of sheath to core of 1 : 1 were
prepared at the spinning temperature of 285C and the winding
speed of 1,000 m/min., and drawn to the draw ratio of 3.90
at the drawing temperature of 84C and the orientation set
temperature of 180C, so that three types of conjugate
filaments with the fibre diameter of 48~um, 40 ~m and 34Jum
were obtained.
Five types of mesh fabrics as listed in Table 1 were
prepared from the conjugate filaments. After heat-setting the
fabrics, the strength and elongation were measured. Table 1
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lists the measurement results in comparison with the measurements
of polyester mesh fabrics having the same fibre diameter and mesh
size as those of the mesh fabrics of the composite filaments,
respectively.
Table 1
Types of fabrics Average Average
strength elonga-
. (kgf) tion
No Mesh Fibre materials (%)
Al 150 conjugate monofilament 48~um 40.0 31.7
Bl 150 polyester monofilament 48Jum 28.0 ~
A2 200 conjugate monofilament 48~um 51.0 33.7
B2 200 polyester monofilament 48 ~m 38.0 Z9 0
A3 250 conjugate monofilament 40 ~m 43.8 33.6
B3 250 polyester monofilament 40 ~m 33.8 28.0
A4 270 conjugate monofilament 34 ~m 37.9 34.3
B4 270 polyester monofilament 34Jum 28.3 Z8 5
A5 300 conjugate monofilament 34 ~m 40.4 35.9
BS 300 polyester monofilament 34 /um 29.2 2Y,2 .
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Test Method: according to the labelled strip method of
JIS L 1068 (1964)
Testing Machine: constant-speed tension tester (prepared
by Shimadzu Corporation, Type-500)
Test Conditions: 20C, 65% R.H. environments
specimen width of 5 cm, specimen grip-
distance of 20 cm,
tension speed of 10 cm/min.
Number of Experimental Times: 50
Figures 1 to 5 show the stress-strain curves of the
mesh fabrics Al to A5 and Bl to B5 as listed in Table 1, and
conventional nylon mesh fabrics Cl to C5. The test conditions
were the same as above-described. The materials and the mesh
size of the mesh fabrics Cl to C5 were as follows:
Cl: 150 mesh fabric made of nylon monofilaments of 50 ~m
fibre diameter
C2: 200 mesh fabric made of nylon monofilaments of 50 ~m
fibre diameter.
C3: 250 mesh fabric made of nylon monofilaments of 39 Jum
fibre diameter
C~: 270 mesh fabric made of nylon monofilaments of 39 ~um
fibre diameter
C5: 300 mesh fabric made of nylon monofilaments of 39 ~um
fibre diameter
As understood from Table 1, and Figures 1 to 5, the
mesh fabrics Al to A5 have a moderate elongation and a very
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1327727
high strength as compared with that of the conventional screen
materials Bl to B5 and Cl to C5. Also, the mesh fabrics Al to
A5 according to the invention satisfy the formula y 2 (X ~ 1) x
5 / 3 when the elongation Y (%)is not lessthan 5%, with respect
to the stress-strain curve. On the contrary, the conventional
screen materials Bl to B5 and Cl to C5 exhibit a stress-strain
curve where the gradient is relatively small, and the elongation
is far from satisfying the above formula.
Table 2 tabulates the generation state of white-powdery
scum of the fabrics A2, B2, A3, B3, A5 and B5, as listed in
Table lj during the weaving.
The fabrics A2 and B2 were 200 mesh fabrics woven with
18,800 warps at the weft filling rate of 230 timestmin.
The fabrics A3 and B3 were 250 mesh fabrics woven with
23,500 warps at the weft filling rate of 230 times/min.
The fabrics A5 and B5 were 300 mesh fabrics woven with
28,200 warps at the weft filling speed of 210 times/min.
All the fabrics were woven by means of a Sulzer weaving
machine. During weaving, when the scum was considerably generated,
air was sprayed on the reed with an airgun to remove the scum.
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Table 2
White-powdery
Type of fabrics tion scum
No. Fibre materials rate ~ ~ ~ Evalua-
A2 conjugate monofilament - 96 5,000 ~
B2 polyester monofilament 91 300 O
A3 conjugate monofilament 97 4,500
B3 polyester monofilament 92 180
.
A5 conjugate monofilament 98 3,000 ~
B5 polyester monofilament 90 140 X .
Evaluation:
: White-powdery scum is scarcely generated.
O : The remaining ratio of white-powdery scum is
up to 20%.
: The remaining ratio of white-powdery scum is
more than 20% up to 50%.
X : The remaining ratio of white-powdery scum is
more than 50~.
The test results of Table 2 indicate that the
fabrics A2, A3 and A5 according to the invention could be
so woven as to superior qualities substantially without
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generation of white-powdery scum.
Example 2
The mesh fabrics as described in Example 1 were
heat-set, and fixed to an aluminum frame with a screen
stretching machine. During the procedure, the compressor
pressure of the screen stretching machine was measured with
changing the tension of the mesh fabrics. At the same time,
the elongation of the mesh fabrics was examined by marking
at a 50 cm distance in the center of the mesh fabrics in both
of warp and weft directions and measuring the changes of the
distance.
Table 3 shows the relation of the tension of the
mesh fabrics to the compressor pressure of the screen stretching
machine and further the elongation of the mesh fabrics. Table 4
shows the changes of the tension of the mesh fabrics with the
lapse of time. The symbols A2, A3, A5, B2, B3 and B5 designate
the same mesh fabrics as described in Example 1, respectively.
The used test apparatus were as follows:
Screen stretching 3 S Air Stretcher manufactured by
machine:
Mino Group
Aluminum frame: 880 mm x 880 mm
frame width of 40 m~, frame thickness of
25mm
Tension meter: Type 75 B Tension Gauge manufactured by
Sun Giken
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Table 3
.
Compressor pressure Elongation (%)
Tension tkg/cm2)
(mm) conjugate conjugate
monofilament polyester monofilament polyester
fabrics fabrics fabrics fabrics
_
A2 B2 A2 B2
1.00 6.2 6.5 3.4 6.1
0.90 ~ 6.8 7.3 4.4 7.6
0.80 7.2 8.0 5.2 9.6
0.70 8.5 9.5 6.2 11.8
0.60 .9.0rupture 6.6 rupture
A3 B3 A3 B3
1.00 6.0 6.5 4.6 7.3
0.90 6.8 7.0 5.2 9.6
0.80 7.3 8.3 6.2 10.4
0.70 8.3 ' 9.0 7.6 12.7
0.60 9.0 rupture 8.8 rupture
A5 B5 A5 B5
1.00 6.2 6.8 5.0 8.3
0.90 7.0 8.0 5.8 10.5 .
0.80 8.0 8.6 7.2 12.5
0.70 8.5 rupture 8.4 rupture
0.60 9.5 _ 9.0
,
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Table 4
.'
Changes of tension (mm)
Time
(h r) conjugate polyester nylon
. monofilament :
. fabrics (A2) fabrics (B2,) fabrics (C2)
O 1Ø0 ' 1.00 1.00
. 6 . ~.02 1.03 1.Q412 1 . 03 1 . 05 1 . 07
.24 1 . 03 1 . 06 1. 09
. 48 1 . 03' 1 . 07 1 . 11
. 72 ~.03 1.07 1.1296 1 . 03 1 . 08 1 . 13
120 1. 03 1. 07 1. 14
; 144 1. 03 1. 08 1 . 15
168 1 1-03~ 16
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The test results in Tables 3 and 4 indica~e that
the mesh fabrics A2, A3 and A5 can be stretched to form a
screen by application of a high tension with high workability
and stability. On the contrary, in the case of the conventional
polyester mesh fabrics B2, B3 and B5, the elongation is
acceralately increased as the tension becomes higher. The
conventional mesh fabrics are difficult to be stretched with
stability for formation of the screen. The conventional mesh
fabrics have limitations to the application of tension. As to
the change of the tension after stretching, the conventional
mesh fabrics of polyester (B2) and nylon (C2) exhibit significant
changes. Particularly, the tension of the nylon mesh fabric C2
exhibits no constant value one week after stretching.
Example 3
The tribo-electrification voltage, the half-life, and
the leak resistance of the present mesh fabrics were measured,
and compared with those of a conventional polyester mesh fabric,
a low-temperature plasma-treated pol~ester mesh fabric, and an
anti-static trested polyester mesh fabric. Table 5 shows the
measurement results.
The test method i8 as follows:
Tribo-electrification voltage: measured by Kyodai
Kaken Type Rotary Stick Tester(manufactured by
Koa Syokai).
Cloth to be rubbed against the mesh fabrics - cotton
shirting Number 3
revolution speed - 450 rpm
load - 500 g
friction time - 60 sec.
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Leak resistance: measured by SM-5 ultra-insulation
resistance tester ~Enufactured by ToaDenpa Kogyo) at
the temperature of 20C and the RH of 40% according to
JIS G-1026.
Table 5
,
tribo-electri- leak
type of fabricsfication half-life resist-
voltage (V) (sec) ance (Q)
conjugate monofilaments 9
fabric 480 2 2 X 10
untreated polyester 5,200 60< 2 X 1013
pflbsma-treated polyester6,200 60~ 2 X 1013
anti-static treated 540 2 3 X 101
polyester fabric .
The test results indicate that the fabric according to
the invention causes no troubles by static electricity in
printing process, and i8 useful as a printing screen.
Example 4
The mesh fabrics as listed in Table 1 of Example 1 were
washed with a 0.2Z neutral detergent aqueous solution, and dried.
On each mesh fabric, a PVA-vinylacetate type photosensitive
emulsion NK-l (manufactured by Carley Co., Ltd., West Germany)
was coated and dried to form a photosensitive coating film of
10 to 12 ~m. Then, the photosensitive coating film was printed
in the following cross stripes patterns which had different sizes
regularly varied in ten steps.
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No. size of cross stripes row line number of crosses
1 0.1 mm x 0.1 mm 20 10 200
2 0.2 mm x 0.2 mm 20 10 200
3 0.3 mm x 0.3 mm 20 10 200
4 0.4 mm x 0.4 mm 20 10 200
0.5 mm x 0.5 mm 20 10 200
6 0.6 mm x 0.6 mm 20 10 200
7 0.7 mm x 0.7 mm 10 10 100
8 0.8 mm x 0.8 mm 10 10 100
9 0.9 mm x 0.9 mm 10 10 100
1.0 mm x 1.0 mm 10 10 100
The printing was carried out by using a 4 kw rated
high voltage mercury lamp. The distance between the coating
film and the mercury lamp was 1.5 meters, and the exposition time
interval was 3 minutes. The integrated quantity of light was
400 milli jules I cm2.
Followingly, the mesh fabrics having the coating film
was dipped in water for 3 min., and was sprayed with water so
that the unexposed part of the coating film was removed.
Each mesh fabric having the different cross patterns
was sub~ected to a tape peeling test for measurement of the
bonding strength of the cured cross patterns of the photosensitive
resin.
Method for Tape Peelin~ Test
Filament tape ~ 810 made by Sumitomo 3 M Co., Ltd.
- 25 -
.
1327727
was adhered on the cross patterns formed on each mesh fabric.
Thereafter, the tape was peeled off from the mesh fabric. The
procedure was repeated three times for the same surface. The
number of patterns adhered to the tape were counted.
Table 6 shows the test results. In the table, the
numerical values in the column with the heading "first" represent
the number of patterns peeled from the mesh fabric by the first
tape adhesion. The numerical values in the columns with the
headings "second" and "third" represent the total number of
peeled patterns after the second and the third tape adhesion,
respectively.
- 26 -
1~27727
Tabie 6
.
number 1 2 3 4 5 6 7 8 9 10
_
first .
A2 4 0 0 0 0 0 0 0 0 0
B 2 16 4 2 2 1 0 0 0 0 0
second
A 2 4 1 0 0 0 0 0 0 0 0
. B 2 26 4 4 2 2 1 0 0 0 0
.. . third .
A 2 4 2 0 0 0 0 0 0 0 0
B 2 48 20 8 6 6 4 1 0 0 0
first
A 3 2 0 1 0 0 0 0 0 0 0
B 3 14 8 2 4 1 0 0 0 0 0
second
A 3 2 0 1 0 0 0 0 0 0 0
B 3 22 15 8 4 2 1 0 0 0 0
third
A 3 2 1 1 0 0 0 0 0 0 0
B 3 40 17 10 6 4 2 0 0 0 0
first
A4 2 0 0 0 0 0 0 0 0 0
oB 4 15 ~8 2 2 0 l 0 0 0 0
~3 second
. A 4 2 0 0 0 0 0 0 0 0 0
B 4 24 9. 7 5 0 1 l 0 0 0
third
A 4 2 0 1 0 0 0 0 0 0 0
, B 4 30 17 7 5 l l l 0 0 0
.
first
A 5 4 0 0 0 0 0 0 0 0 0
, B 5 16 9 10 2 0 0 0 0 0 0
second
.A 5 4 0 0 0 0 0 0 0 0 0
B 5 18 11 10 2 l 0 0 0 0 0
third .
A 5 4 1 0 0 0 0 0 0 0 0
B 5 33 ll lO 2 2 l 0 0 0 0
... .
. The symbols A2 to A5 and B2 to B5 designate the same
mesh fabrics as listed in Table 1 of Example 1, respectively.
1327727
Example 5
After heat-setting of the mesh fabrics as listed in
Table 1 of Example 1, E.P.C. and the tensile modulus of elasticity
of the fabrics were measured, and compared with those of
conventional polyester mesh fabrics. The results are shown in
Table 7 and Table 8.
.
E.P.C.
It represents the physical properties of fibres as
Elastic Performance Coefficients, which involve the recovery properties
of the fibres after the subjection to mechanical action.
The correlations between the load and deformation of
a fibre at the first and the n-th cycle of the load and
deformation test are illustrated in such a manner as shown
in Fig. 6.
In the figure, the symbols represent the following:
Lo: load and deformation curve of a fibre at the first
cycle of the test,
L~: load and deformation curve of the fibre at the
conditioning,
Ro recovery curve of the fibre at the first cycle of
the test,
R~: recovery curve of the fibre at the conditioning,
~ aO: teformation of the fibre by loading at the first
3 cyrcle, and
! a~: deformation of the fibre by loading at the conditioning.
- 28 -
.'~
.
.
1327727
The symbol A such as A in ALo and so forth designates
an energy value required for the deformation or the recovery
of the fibre.
The ratio of ARo to Al~ indicates the degree of
recovery-performance of the fibre at the conditioning, and
is a linear function of the tension speed.
aO 2 /AL~ indicates the degree of energy absorption
to the deformation generated at the first cycle.
a~2/AL~ indicates the degree of energy absorption
to the deformation energy at the conditioning.
Accordingly, E.P.C. is expressed by the following
equation using these ratios and the correction item ARo/AL~.
a~ AR~
AL~ AL~
E.P.C. -
aO 2
AL~
In case that the fibre can be recovered: ARo = AL~, aO = a~ ,
ALo= AL~, AR~ = AR~, E.P.C. = 1
In case that the fibre cannot be recovered: AR = 0, AR~ = AL~,
a~ ~ aO, E.P.C. = 0
Tensile Moudulus of Elasticity
This test method i9 in accordance with JIS L 1096.An automatic recorder equipped, constant speed
tensile tester i9 used. The distance between the grips for
a specimen is 20 cm. The tension speed is a rate of 10% of the
grip distance per 1 minutes. The specimen is stretched till
- 29 -
~327727
a predetermined load is obtained. Successively, the specimen
is unloaded at the same speed as that at loading. Then, the
specimen is stretched at the same speed till the predetermined
load is obtained. The residual elongation is measured from
the recorded load-elongation curves. The tensile modulus of
elasticity is calculated from the following equation:
L - Ll
tensile modulus of elasticity = x 100
where L is an elongation (mm) at a predetermined load, and
Ll is a residual elongation (mm) at the predetermined load.
E.P.C. and the tensile modulus of elasticity were
measured under the following conditions:
Test Method: according to the labelled strip method of
JIS L 1068 (1968)
Testing Machine: Constant-Speed Stretching Type tester
(made by Shimadzu Corporation, Type S-500)
Test Conditions: temperature 20C, R.H. 65%
specimen width 5 cm, grip distance 20 cm
tenslon speed 10 cm/min.
cycle number 20
Experiment Times: 50
- 30 -
1327727
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1327727
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- 32 -
1327727
The test results in Table 7 and Table 8 indicate
that the mesh fabrics Al, A2, A3, A4 and A5 according to the
present invention are excellent in the recovery property and
undergo a less change at a higher load applied as compared
with the conventional polyester fabrics Bl, B2, B3, B4 and
B5, and further have a high elastic recovery ratio and a
high recoverability after subjected to mechanical action.
Accordingly, the present mesh fabrics have a
durability remarkably improved as a printing screen and also
high printing performances, which are attributed to the
enhancement in the recovery property.
Example 6
The mesh fabrics as listed in Table 1 of Example 1
were heat-set, and fixed to an aluminum frame with a screen
stretching machine, respectively. The stretched mesh fabrics
were washed with water and dried. To each of the stretched
mesh fabrics, a PVA-vinylacetate type photosensitive resin
emulsion NK-14 manufactured by Carley Co., Ltd. was applied
by lap-coating method, and dried. The thickness of the coating
film was 12~um. The photosensitive coating
film formed on the mesh fabric was cured by esposure to light
so as to have the following two patterns;
(1) a lattice-form pattern in which thin lines are
crossed at a 150 mm interval to each other in the warp and
the weft directlon, and
(2) a pattern in which two groups of five thin
lines of each of 50 ,um, 60 ~m, 80Jum, lOO~um, 125Jum, 150~um,
200~um, 250~um and 300Jum wide in parallel at an equal
- 33 -
1327727
distance are arranged.
The printing discrepancy is measured by using
the pattern (1) at the number of printing times of 1,000
and 3,000. The reproducibility of thin line was measured
by using the pattern (2).
The curing was conducted by means of a 3 kw rated
metal halide lamp. The distance between the metal halide
lamp and the coating film on the mesh fabric was 80 cm.
The exposure time was 2 minutes. After the exposure, the
mesh fabric was dipped in water for 3 minutes, and injected
with water, so that the unexposed part of the coating film
was removed.
As described above, the printing discrepancy and
the thin line reproducibility of the mesh fabrics each
having the cured pattern (1) or (2) were measured for
evaluation of the printing precision of the mesh fabrics.
Tables9, 10 tabulate the test results.
Conditions for Producing Screen Stencil:
Screen stretching machine: 3S Air Stretcher (made
by Mino Group, normal stretching type)
Tension: 1.00 mm (at completion of the stretching)
Emulsion: NK-14 (made by Carley Co., Ltd., West
Germany)
Thickness of coating film: 12 ,um
Frame: 880 mm x 880 mm (made of aluminum)
Printing image: 300 mm x 300 mm
- 34 -
1327727
Conditions of Squeegee:
- Material: polyurethane
Hardness: 70
Angle: 7~
Width: 405 cm
Printing Conditions:
Gap: 3.0 mm
Impression: 1.5 mm
Ink: UV ink 5104-T6 (made by Mitsui Toatsu Chemicals,
Inc.)
Viscosity of ink: 200 PS
- 35 -
-
1~27727
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- 36 -
1327727
Table 10 Thin Line Printing Resolution Properties
conjugate polyester
monofilament fabric
fabric (A2) (B2)
100 ~m 150 ,um
conjugate polyester
monofilament fabric
fabric (A3) (B3)
80 ~m 150 ~m
conjugate polyester
monofilament fabric
fabric (AS) (BS)
.
60 ~um ` 125 ,um
As shown in Table 9 and Table 10, the mesh fabrics
A2, A3 and A5 according to the invention have high printing
precision and thin-line printing resolution property, and
are advantageously applicable for high-density, high-precision
printing.
On the contrary, the conventional polyester mesh
fabrics B2, B3 and B5 were inferior in the thin-line printing
resolution property. As the number of printing times was
increased, the printing precision was remarkably reduced.
1327~27
Example 7
E.P.C. and the tensile modulus of elasticity of
the mesh fabrics after the 3,000 times screen printing as
shown in Table 9 of Example 6 were measured, and compared
with those of the conventional polyester fabrics. The test
results are shown in Table 11 and Table 12. The test method
was the same as described in Example 5.
- 38 -
1327727
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- 39 -
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1327727
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- 40 -
.
1327727
The test results in Table 11 and Table 12 indicate
that the present mesh fabrics A2, A3 and A5 have high after-
printing E.P.C. and tensile modulus of elasticity which
enhance the printing precision and printing durability of
the fabrics. Accordingly, the present mesh fabrics are
advantageously applicable for high-density, high precision
screen printing.
On the contrary, in the case of the conventional
polyester monofilament fabrics B2, B3 and B5, as the number
of the printing times was increased, the printing durability
of the fabrics was reduced. Conventional nylon monofilament
fabrics, of which the test results are not presented herein,
are inferior to the polyester monofilament mesh fabrics in
the tensile modulus of elasticity. Accordingly, the
conventional nylon monofilament mesh fabrics are unsuitable
for application to high-density, high-precision screen
printing.
Example 8
By following substantially the procedure described
in Example l with respect to the mesh fabrics Al to A5 and by
adding yellow pigment (PID yellow No. 83, made by Repino
Colour Kogyo Co., Ltd.) to the material of the sheath of
the conjugate filaments, mesh fabrics Xl to X5 were obtained
from the con~ugate filaments each comprising the dope yellow-
coloured sheath.
- 41 -
1327727
On the other hand, the mesh fabrics Al to A5 as
described in Example 1 were dyed in yellow colour, so that
the mesh fabrics Yl to Y5 made of the conjugate filaments
each comprising the dyed sheath were obtained. Further, for
comparison, the mesh fabrics Bl to B5 as described in
Example 1 were dyed in yellow colour in the conditions as
described in Table 13, so that the yellow-coloured polyester
mesh fabrics Zl to Z5 were obtained.
All the mesh fabrics exhibited a halation resisting
property when exposed to light for the photomechanical process.
As understood from Table 13, the mesh fabrics Xl to
X5 made of the conjugate filaments each comprising the dope-
coloured sheath had no heat shrinking, and could be processed
for forming a screen stencil with keeping the high qualities
of the fabrics, whatever pattern may be formed on the screen.
This is attributed to the unnecessity of ~he mesh fabrics Xl
to X5 to be subjected to a dyeing process with low workability.
The present mesh fabrics Yl to Y5 could be rendered
halation preventive relatively easily. As the mesh fabrics
Yl to Y5 are unnecessary to be subjected tosevere conditions
for the dyeing, the deformation of the fabrics are relatively
small. The mesh fabrics Yl to Y5 are advantageously
applicable for the process of a screen stencil having a finer
pattern with high process stability.
On the contrary, the conventional polyester mesh
fabrics Zl to Z5 require severe conditions for the dyeing,
- 42 -
1327727
and are heat shrinked to large extent. Accordingly, the
mesh fabrics Zl to Z5 are unsuitable for the process of a
screen stencil having a fine pattern.
- 43 -
1327727
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- 44 -
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1327727
Example 9
Electron micrographs of the mesh fabrics Xl to X5,
Yl to Y5 and Zl to Z5 were taken to examine the surface
state, and compared with each other. Table 14 shows the test
results.
Table 14
_ _ -~ surrace state
No mesh materials of fabric
dope-coloured conjugate no foreign
Xl 150 monofilaments 48 ~ m matters clean
X2 200 " 48 ~r"'
X3 250 . " 40 ~ m"
X4 270 " . 34 ~ m"
X5 300 " 34 ~ m"
Yl 200 ~nonodfilaments . 48 ~ matters .
Y3 250 " 40 ~ m"
Y4 270 ~ 34 ~ m"
Y5 300 ~ 34 ~ m"
_ ~ Iyed polyester a lot of
Z2 200 nonofilaments 48 ~ m foreign"matters
Z3 250 " ' 40 ~ m "
Z4 270 . " 34 ~ m "
Z5 300 ~ 34 ~ m
Figures 7 to 9 represent the microphotographs (magnification:
500) of the mesh fabrics X3, Y3 and Z3, respectively. As
understood from Table 14 and Figures 7 to 9, the present
mesh fabrics Xl to X5 made from the dope-coloured conjugate
- 45 -
1327727
monofilaments had a very clean surface. The present mesh
fabrics Yl to YS made of the dyed conjugate monofilaments
were high-quality products which had less foreign matters
adhered thereto, as compared with the conventional mesh
fabrics Zl to Z5 made from the polyester monofilaments.
Example 10
The mesh fabrics Xl to X5, Yl to Y5, and Zl to Z5
as described in Example 8, and the undyed mesh fabrics Al
to A5 and Bl to B5 as described in Example 1 were washed
with a 0.2% neutral detergent aqueous solution, and dried.
To each of the mesh fabrics, a PVA-vinylacetate type
photosensitive resin emulsion NK-14 (made by Hoechst Co., Ltd.)
were applied by lap-coating, and dried. The thickness of
the coating films formed on the mesh fabrics was in the
range of lO~um to 12 ~um. Each mesh fabric having the
photosensitive coating film was cured by exposure to light
so as to have a fine pattern thereon.
The mesh fabrics each having the fine pattern were
observed by use of an electron microscope. Table 15 shows
the observation results.
Table 15
type of fabricshalat10n state total
prevention of evalua-
No materials effect pattern tion
. Xl ~ X5 dopefcolloured conjugate ~ A
Yl ~ YS monofilaments O
Zl ~ Z5 dyed polyester O x D
monofilaments
Al ~ A5 undyed conjugate ~ O C
Bl ~ B5 monofilaments X D
- 46 -
1327727
The marks indicate the following, respectively:
(the halation prevention effect)
superior in halation prevention effect
O good in prevention effect
~ prior in halation prevention effect
X producing a halation
(state of pattern)
high bonding strength, very clear in the whole pattern
O high bonding strength, clear in the pattern edges
low bonding strength, poor in the pattern edges
X substantially no bonding strength, incapable of
forming a pattern
(total evaluation)
A superior in both of halation prevention effect and
bonding strength
B good in both of halation prevention effect and
bonding strength
C poor in either one of halation prevention effect
or bonding strength
D poor in both of halation prevention effect and
bonding strength
Figures 10 to 14 show the microphotographs
(magnification: 500) of the mesh fabrics X5, Y5, Z5 and A5,
and B5 each having the fine pattern formed thereon as
described above. As these results and Table 14 indicate
clearly, the present mesh fabrics, whether they are dyed
- 47 -
1327727
or dope-coloured, had high halation prevention effect, and
could be precisely provided with a pattern thereon as a
screen stencil (see Figures 10 and 11, and the columns of
Xl to X5 and Yl to Y5 in Table 14). On the contrary, the
conventional polyester monofilament mesh fabrics, though
they could be rendered halation resistant by the dyeing,
the fibrous surfaces of the conventional mesh fabrics became
irregular, as shown in Figures 9 and 12, and the bonding
strength was reduced by the dyeing. Accordingly, the
conventional polyester monofilament fabrics could not be provided
with a definite pattern thereon (see the columns of Zl to Z5
in Table 14).
The mesh fabrics of the invention, which are not
dyed, can be provided with a pattern thereon (see Figure 13
and the columns of Al to A5 in Table 14). In the case of
the conventional polyester filament mesh fabrics, a definite
pattern cannot be formed thereon, because of occurring of
blurs and fogs on the pattern (see the columns of Bl to B5
in Table 14).
Industrial ApplicabilitY of the Invention
A mesh fabric of the invention has high dimensional
stability, mechanical strength and bonding strength to a resin,
which enables a precision printing screen to be processed
with high production efficiency. Further, the present mesh
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fabric has high anti-static property, and provides a high
workability during the use as a printing screen.
The present mesh fabric makes it possible to
process a screen which has high ink squeezing properties
and undergoes extremely less changes in the quality with
the lapse of time and substantially no-discrepancy in the
printings.
Accordingly, the mesh fabric of the invention is
suitable for mass-production of screens to be applied to
precision printing of electronic parts such as printed
circuits, multiply boards, IC circuits, and so forth, with
inexpensiveness and high production efficiency.
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