FIELD OF THE INVENTION
The present invention relates to an improved process for producing rainwear and more
particularly to produce light weight comfortable rainwear with the feature of moisture vapour
permeability.
BACKGROUND OF THE INVENTION
In the market rainwear made from rubberized fabrics are available. Those rubberized
fabrics are manufactured from natural and conventional synthetic polymers and fabrics. The
rubber coatings are not permeable to water vapour due to lack of chain flexibility and
micropores. PVC Rainwear is non- hygienic and becomes brittle and plasticizers leaches out
after some days of use.
The disadvantages of available rainwear in the market are as follows:-
(i) I leavy Weight
(ii) Non - permeable, as a result heavy sweating takes place when worn.
(iii) Poor Colour fastness
(iv) Poor ageing resistance
(v) Non - Hygienic
(vi) Poor Flexibility particularly at low temperature (Below 0°C)
According to the present invention the rainwear obtained by the process
of the present invention has the following advantages: -
a) light weight waterproof fabric
b) breathable
c) dry and comfortable feeling
d) hygienic polymer coating
e) free from dermatological effects
f) water repellent
g) excellent ageing resistance
h) very good flexibility at low temperature (at -40°C)
SUMMARY OF THE INVENTION
According to the present invention an improved process for producing
improved rainwear is provided which comprises:
(i) mixing toluene with liquid silicone rubber whosie chemical composition
is Polydimethylsiloxane with functional group in toluene, followed by mixing
with acetic: acid in presence of catalysts consisting of Organo Tin Compound
(known as Catalyst 128A manufactured and marketed by Wacker Silicone
under the name "METROARK 128A CATALYST") and Organo Silicone
Compound (Catalyst 128B manufactured and marketed by Wacker Silicone
under the name "METROARK 128B CATALYST" );
(ii) coating the above mixture on untreated fabric such as herein described
by spreading and passing through Hot Air Sterner at slow speed by putting off
the first and second blowers and by putting on ihe rest of the blower(s) at slow
speed as required; and
(iii) coating the second coating of mixture of step (i) in a similar manner
given in step (ii).
During the process the catalyst Organo Tin Compound is Catalyst 128A
which is manufactured and marketed by Wacker Silicone under the name
"METRO ARK 128A CATALYST".
During the process the catalyst Organo Silicone compound is Catalyst
128B which is manufactured and marketed by Wacker Silicone under the name
"METROARK 128B CATALYST".
Moreover, during the process coating is effected with the angle of V-
shaped steel floating knife over Steel Roller.
Ingredients of step (i) are taken as under
DETAIL DESCRIPTION OF THE INVENTION
Material
1) Silicone Rubber —liquid
2) Catalyst 128 A - Organo Tin Compound (manufactured and marketed
by Wacker Silicone under the name "METROARK 128A CATALYST5)
3) Catalyst 128 B - Organo silicone compound (manufactured and
marketed by Wacker Silicone under the name "METRO ARK 128B
CATALYST)
4) Acetic Acid - To maintain PH
5) Toluene as solvent
Machinery
1) High Speed Stirrer
2) Coating Head with Steel Roller
3) Hot air Stenter
4) Testing Equipment for Moisture Vapour Transmission testing
Composition
1) Liquid Silicone rubber (Polydimethylsiloxane)
2) Catalyst 128A - Organo Tin Compound (manufactured and marketed by
Wacker Silicone under the name "METROARK 128A CATALYST")
3) Acetic add
4) Catalyst 128B — Organo silicone compound (manufactured and marketed by
Wacker Silicone under the name "METROARK 128B CATALYST)
5) Toluene
PROCEDURE
A. Mixing
Take silicone rubber in a clean plastic bucket Add toluene to it and mix.
Then take the required amount of acetic acid in a measuring cylinder and mix it
properly with the silicon rubber and stir. Take the required amount of Catalyst
128A in the same measuring cylinder, mix properiy with the silicone rubber and
stir. Take the required amount of catalyst 128B in another measuring cylinder;
add this to the silicone rubber and stir.
B. Spreading
Spread the above mixture on bright yarn fabric (untreated fabric) and
then pass through the Hot Air Sterner after putting off the first and second
blowers and by putting on the rest of the blower (s) at slow speed as required.
No. of Coating: Two
Composition of 1st Coating: Same as above
Composition of 2nd. Coating: Similar to 1st Coating
Process Parameters
Speed of spreading -10 meter, /min
Type of Knife -Floating, V shaped, with angle (8° from vertical plane)
Curing temperature - 140 -170°C (coating should not be done if temperature is
below 140°C),
WE CLAIM :
1. An improved process for producing rainwear, which comprises:
(i) mixing toluene with liquid silicone rubber whose chemical composition
is Polydimethylsiloxane with functional group in toluene, followed by mixing
with acetic acid in presence of catalysts consisting of Organo Tin Compound
(known as Catalyst 128A manufactured and marketed by Wacker Silicone
under the name "METROARK 128A CATALYST") and Organo Silicone
Compound (Catalyst 128B manufactured and marketed by Wacker Silicone
under the name "METROARK 128B CATALYST" );
(ii) coating the above mixture on untreated fabric such as herein described
by spreading and passing through Hot Air Stenter at slow speed by putting off
the first and second blowers and by putting on the rest of the blower(s) at slow
speed as required; and
(in) coating the second coating of mixture of step (i) in a similar manner
given in step (ii).
2. The process as claimed in claim 1, wherein the catalyst Organo Tin
Compound is Catalyst 128A which is manufactured and marketed by Wacker
Silicone under the name "METROARK 128A CATALYST".
3. The process as claimed in claims 1 or 2, wherein the catalyst Organo
Silicone compound is Catalyst 128B, which is manufactured and marketed by
Wacker Silicone under the name "METROARK 128B CATALYST".
4. The process as claimed in any one of claims 1 to 3, wherein coating is
effected with the angle of V-shaped steel floating knife over Steel Roller.
5 The process as claimed in any of claims 1 to 4, wherein ingredients of
step (i) are taken as under:

The present invention relates to an improved process for producing rainwear and more
particularly to produce light weight comfortable rainwear with the feature of moisture vapour
permeability. The said process comprises the steps of: (i) mixing toluene with silicone rubber
followed by mixing with acetic acid in presence of catalysts consisting of Organo Tin
Compound and Organo Silicone Compound or Functional Silane; (ii) coating the above mixture
on untreated fabric by spreading and passing through Hot Air Stenter at slow speed by putting
off the first and second blowers and by putting on the rest of the blower(s) at slow speed as
required; and (iii) coating the second coating of mixture of step (i) in a similar manner given in
step (ii).