Note: Descriptions are shown in the official language in which they were submitted.
BACKGROUND OF THE INVENTION
This invention relates to a belt for use on heat transfer pri~-
ing machines, and more partiCularly to a heat resistant belt with
smooth surface, higher dimensional stability, higher tensil stre~t..
higher wear registance, higher elasticity and air or gas permeabili~y
suitable for heat transfer printing.
Heat transfer printing is a re~olutionary method of printing
synthetic fabrics and other materials, designs are transfered fro~
pre printed paper to clothes, duri~g the operation the ink subli~e,
and transfer directly to the fabrics with sharpness of detail and
registration that is superior to that with traditional printing met~od.
The pattern of solid color is permanent:Ly bonded to the fabric dry
and finished. The process is fast accurately and economical for ~o,-
short and long run.
In this heat transfer printing, it is the usual practice to use an
endless belt Eor guiding and pressing a Yabric web against the cir-
cumference of a heating c~linder in overlapped relation with a tra~sfer
sheet like pre-printed paper as described hereinlater. Such belt is
required to have heat resistance, elasticity, suitable air or gas
permeability (an air or a gas permeability range of 5 to 30 ccjsec~^~3)
and smoothness, dimensional stability, tensil strength, wear regist3~ce.
Espec~ially, a belt which has an air or a gas permeability graater tn~n
the upper critical value suffers from uneven prints due to excessi~e
dispersion or accelerated transfer of a dye which sublimes when t~e
transfer sheet and fabric web are heated under pressure, while a oe t
which is inferior in surface smoothness causes contacting failures
L~a~2
and contamination of the belt.
SU~MARY_OF THE INVENTION
It is an object of the present invention to pro-
vide a heat resistant belt for use in heat transfer print-
ing, which has excellent elasticity, dimensional stability,
tensile strength, wear resistance and surface smoothness
along with suitable air or gas permeability.
In accordance with a particular embodiment of the
invention, there is provided a heat resistant belt for use
in heat transfer printing which has an air or gas perme-
ability of 5-30 cc/sec/cm2. The belt includes an endless
foundation fabric formed from an aromatic polyamide fibre.
The b~elt also includes a lap comprising a second aromatic
polyamide fibre occupying 50 to 100 wt % of the total amount
of fibre in the lap and felted on the endless foundation
fabric by needle punching. The second aromatic polyamide
fibre is heat treated at 25~C - 300C to give a shrinkage
of 5 to 30%.
The above and other objects, features and ad-
vantages of the invention will become apparent from the
following description and appended claims, taken in con-
junction with the accompanying drawings which show by way
of example a preferred embodiment of the present invention.
BRIEF DESCRIPTIO~ OF ~ ~ NGS
In the accompanying drawings:
Fig. 1 is a diagrammatic sectional view of a
heat resistant belt according to the present invention' and
Fig. 2 is a diagrammatic view of a heat transfer
printing machine having the belt of Fig. 1 fitted in posi-
tion.
43~a2
PARTICU~AR DESCRIPTION OF THE INVENTION
Referrlng to Fig~ 1, the heat resistant belt according to the
invention is essentially provided with an endless foundation fabr~e
1 which consists of an aromatic polyamide fibre, and a lap 2 ~hic-
mainly consists of a heat-shrinkable aromatic polyamide fibre 2a
and which is felted on each side of the foundat.ion fabric 1 by
needle punching, the heat-shrinkable polyamide fibre 2a being shri~ked
by a heat treatment.
As mentioned above~ the foundation fabric 1 and lap 2 consists
of an aromatic polyamide fibre with high heat resistance, the re2re-
sentative examples of which include polymethaphenylene isophthala~ide
fibre and polyparaphenylene terephthalamide fibre, preferably poly-
methephenylene isophthalamide fibre. The foundation fabric 1 is in
the form of a thin coarse fabric or mesh ~hich is obtained by ~eavi~g
yarns of the heat resistant fibre in an endless form or by conrecti~g
opposite ends of a woven flat strip. Though various weave patterns
may be used, a plain weave is desirable for surface smoothness of ~:~e
belt.
The lap 2 which is laid on each side of the foundation fabric 1
consists of the above-mentioned aromatic polyamide fibre, mainly the
heat shrinkable type 2a of aromatic polyamide fibre which underg3es
5 to 30% of contraction at a dry heat of 250 to 300 C. The mixi~b
ratio of the heat-shrinkable fibre is 50 to 100 wt%, preferably~
greater than 70 ~t% of the total amount of fibre in the lapO
In this range, the felt lap is compacted by the shrinkage of the
fibre in a suitable degree for the permeability. It is possible
3~3,~
to blend into the polyamide fibre other heat-shrinkable fibre, for
example, heat-shrinkable polyester fibre. I'he thickness of the fibre
which constitutes the lap 2 is suitably 2 to 10 deniers, preferably,
2 to 5 deniers. It is recommended to mix fibre of different thicknesses
of this range in a suitable ratio. ~le air or gas permeability of the
felt belt 3 can be arbitrarily adjusted to the above-mentioned ran~e
of 5 to 30 cc/sec/cm3 by way of the percentage of shrinkage of the
heat-shrinkable fibre, blending ratio, lapping amount and the number
of needle punching. The lap 2 is integrally connected wi'h the
foundation fabric 1 by the needle punching, forming felt with the
individual fibre intermingled with each other and with the fibre of
the foundation fabric.
The heat treatment may be conducted at a temperature in the
range of 250 to 300 C by heating the felt belt with hot air or
theremally pressing the same while stretchin~ the felt belt to shrink
and heat-set the fibres constituting the felt belt. By such a heat
treatment, the heat-shrinkable fibres 2a shrink and the foundation
fabric 1 is simultaneously heat-set, thereby stabilizing the dimen-
sions such as length, ~idth and improving the surface smoothness and
controling the permeability, of the felt belt. The thus-treated felt
belt 3 has a basis weight of 1,oOOg/m2-2,200g/m2, a thickness of 5.0
mm-8.0mm, an apparent density of 0.28g/m3-0.40g/cm3, an air or a gas
permeability of 5 cc/sec/cm3 - 30 cc/sec/cm3 and exhibits high
smoothness and elasticity.
As clear from the foregoing description, according to the
~resent invention, a lap of heat-shrinkable, heat resistant fibre
,
3~
is felted by needle punching on each side of a foundation fabric Or
heat resistant fibre and compacted by a heat treatment to provice a
felt belt which has high heat resistance, resiliency, dimensional
stability tensil strength, wear resistance and smoothness along ~ith
a suitable degree of air or gas ~ermeability of 5 to 30 cc/sec/c~3
due to the synergistic effects of the heat resisting property of the
fibre material, the intermingling effects of the needle punching and
the heat shrinking.
The invention is illustrated more particularly by the follo~ing
example.
EXAMPLE
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On each sïde of an endless fabric (400 g/m2) havin6 ~arp and
weft yarns of polymethaphenylene isophthalamide fibre, ~arps of 1200
denier multi-filament yarns and Nefts of the yarn number count 4
spun yarns, there was formed a :Lap having 8 overlapped felt layers by
needle punching and overlapping each layer containing 100 g/m2 o~ mixture
fibre consisting of 30~ of 5 denier polymethaphenylene isophthalamide
fibre and 7~/o of 5 denier heat-shrink~ble polymethaphenylene is~phtha-
lamide fibre, thereby for~ing an endless felt belt.
The felt belt thus obtained was heat-treated at 280C while
stretching the same, obtaining a heat resistant belt of 2200 gJm2
~ith a thickness of 5 mm, an apparent density of 0.37 g/cm3 and ~n,
air or a gas permeability of 5 cc/sec/cm3.
The endless heat resistant belt was used on a heat transfer
printing machine as shown in ~ig. 2, the belt 3 guiding along a~d
-- 5 --
3~
pressing aæainst the circumference of a hot cylinder 4 a fabric web
in overlapped relation with a transfer sheet 5. The web 6 was
printed with sharpness and good finish, coupled with other advantages
that the loss of dye was reduced and the service life of the belt was
prolonged with less conta~ination.
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