Note: Descriptions are shown in the official language in which they were submitted.
3 1~4~384
This invention relates to a process for finishing
sheet materials.
More specifically, the invention relates to the
finishing of textile sheets, which are irradiated and exposed
to a grafting reaction to improve the dyeability, moisture
absorbancy, antistatic characteristics, soil repellency, resis-
tivity against rot, and/or the hydrophobic character of the
textile are changed in a positive sense, and whereby at the
same time textured ornamental patterns and dye patterns are
-10 obtained.
It is known that monomers can be grafted on~o poly-
meric materials to modify the characteristics of the polymers.
The grafting of monomeric compounds can be achieved, e.g., by
radiation induced chemical reactions. In order to effect such
reactions, the polymeric material is either irradiated first,
for example, with electron beams from a Van der Graaff generator,
~ s~
and thereafter brought in contact with the monomer, which may
be a liquid (pre-irradiation method), or the polymeric material
is brought in contact first with the monomer, whereby the latter
penetrates the polymeric material, and thereafter the polymeric
material loaded with the monomer is irradiated (simultaneous
,~
method). The latter method has the disadvantage that as well
as the desired grafting reaction unwanted homopolymerization of
the monomer frequently occurs.
-~ Various modifications of the characteristics of the
;~ polymeric material can be obtained depending on the monomeric
compounds selected for grafting. When, for example, a textile
product in sheet form made from polyamide fibres of the basic
structure.
, ~
1~42384
O H H H H H
- C - N - C - C - C - C - C -
H H H H H H
_ _ n
is exposed to ionizing radiation, preferably to the action of
electron beams, macroradicals are formed of the type
O H H H H
- C - N - ~ - C - C - C - C -
H H H H H H
n
which are capable of initiating the polymerization of a monomeric
compound such as acrylamide, CH2 =CHCONH2. The monomeric com-
pound B is grafted onto the polymeric material -A-A-A-A-A- form-
ing a side chain as shown schematically hereinafter:
~` irradiation
- A - A - A - A - A -~ - A - A - A - A - A
macromoleculemacroradical
, grafting
- A - A - A - A - A - + n B ~ - A - A - A - A - A -
(B)
macroradical monomer grafted macromolecule
There is obtained a fabric with enhanced moisture ab-
sorbancy, i.e., a fabric that has improved comfort factors andphysiological properties, when a fabric made from polyamide
;` fibres as the polymeric material is processed in combination
with acrylamide as the monomeric compound. When a textile sheet
material is produced from polyester fibres and acrylic acid
(CH2=CH~OOH) as the monomeric compound, a material deyable with
basic dyes is obtained.
All of the known ionizing radiation systems can be
used in radiation initiated chemical grafting procedures (homo-
geneous modification) especially electron beams, gamma-rays and
X-rays.
~5~Ç4Z384
One disadvantage of known procedures for grafting
- monomeric compounds onto polymeric materials and specifically
onto textiles in sheet form is that the character, i.e., the
appearance of the textilesheets does not change.
A procedure is also known whereby the contractions
which occur during the grafting reaction, i.e., the shrinkage
of sheet materials, are used to produce a textured finish. In
order to obtain such a finish, the free radicals required to
initiate the grafting reaction are unevenly distributed over
the entire area of the sheet i.e., they are produced only locally.
The radicals can be generated in limited areas only either
by using shielding stencils placed between the source of radi-
ation and the sheet material or the material can be uniformly
irradiated, and thereafter the free radicals over limited areas
of the sheet destroyed, for example, by applying heated profile
rolls around which the material is guided.
Spacial warping of the sheet material creates textured
.~
effects, i.e., ornamental texturing which can be combined with
patterns for dyeing. Likewise, the moisture absorbancy can be
.~
modified in a positive sense.
` A disadvantage of the last mentioned process is that
the so-called "partial modification" procedure does not make it
possible to obtain those effects which require a closed conduct-
ing film, a hydrophobic film which is a prerequisite for anti-
static behaviour, or for water repellency, respectively, which
are only attainable by homogeneous grafting of monomeric
compounds.
The object of the present invention is to improve the
dyeability, the moisture absorbancy, the resistivity to rot, the
water repellency and the antistatic qualities of textile materials
;
--3--
1~t4Z3B4
in sheet form, and at the same time create ornamental texturing
and dyeability pattern effects.
The invention is based on the task of praviding a
finishing process for sheet materials, preferably textiles,
whereby the sheet materials are modified in such a manner that
improvements in comfort factors and physical properties as well
as in texture are obtained.
According to the present invention the problem is
solved by homogeneously irradiating the sheet material, bringing
the sheet material, before during or after the homogeneous ir-
~ - .
radiation, with a monomeric compound in a homogeneous manner,
subjecting the sheet between treatments rinsing and drying,
when required, irradiating the sheet thereafter in restricted
areas with ionizing rays, bringing it into contact in locally
limited areas with a medium capable of destroying the radicals
formed during irradiation, and bringing the sheet into contact
~^` with monomeric compounds in a homogeneous manner.
:
~ The localized grafting polymerization procedure can
. ~
also be applied before the homogeneous grafting polymerization
step. It is advantageous to irradiate with electron beams at
~ energy levels of between 40 keV and 3 MeV. Locally limited
- ionizing radiation can be applied either in the form of homo-
geneous irradiation in combination with shielding stencils, the
; ~
thickness of the shielding stencils being larger or smaller than
the penetration range of the electrons, or in the form of regu-
lated irradiation (regulated with respect to intensity applied
or areas covered). Heated rolls with a structure surface design
or controlled laser beams can be applied as means for destroying
radicals in locally limited areas. It is suitable to apply mono-
~,
~ 30 meric compounds as grafting solutions, preferably vinyl compounds,
:'
'""~' .
-4-
:, ,
1~4Z3B4
especially acrylic acid, acrylamine or stryene in liquid or
vapour form. The sheet material has to be kept under definite
- preset tension. It is a further advantage to treat the sheet
material with hot water, hot air or steam.
The following procedures can be used in the process
of the present invention:
(1) In order to effect homogeneous modification of
the sheet material, when using the pre-irradiation method, the
material is first irradiated in a homogeneous radiation field
with ionizing rays, whereby reactive species form, which subse-
quently will initiate a grafting polymerization reaction when
brought into contact with a grafting solution. After the sheet
material is rinsed and dried, i required, it is exposed to
ionizing radiation in a homogeneous field, and then introduced
into another grafting solution, wherein locally limited grafting
occurs. Grafting in limited areas causes locallized contractions
which induce the formation of an ornamental texturing of the
- material. Finally the material is rinsed, dried and wound on
rolls or prepared for storage in some other appropriate manner.
(2) Homogeneous modification is effected in the manner
set out in (1). The free radicals remaining in the material
after the homogeneous grafting procedure are destroyed in limited
areas, especially by applying a heated profiled roll or by means
of laser beams. The radicals remaining thereafter in limited
sections of the material will initiate locallized grafting of
the monomeric compound in the grafting bath along with locallized
contractions from which textured ornamental patterns result.
After grafting, the sheet material is rinsed, dried and stored.
(3) The procedure of (2) is used, but, in order to
enhance the partial grafting process another irradiation is
--5--
1~42;~B4
effected using ionizing rays in a homogeneous irradiation field
after the homogeneous grafting of the material and before the
locallized destruction of radicals.
t4) The sheet material is first modified homogeneously
using the simultaneous method. The material is introduced into
a grafting solution and impregnated with monomeric compound.
Then the impregnated material is exposed to a homogeneous irrad-
iation field. Thereafter, the material is exposed to ionizing
radiation in an inhomogeneous irradiation field and then passed
to another grafting solution in which locallized grafting occurs.
The locallized grafting induces locallized contractions from
which an ornamental texturing of the material results. Finally,
.,:
the material is rinsed, dried and wound on rolls, or prepared
- for storage in some other appropriate manner.
(5) The sheet material is first homogeneously modi-
fied as described in (4) using the simultaneous method. After
.~:
~ irradiation with ionizing rays in a homogeneous irradiation
.-
field, the free radicals are destroyed in limited areas, by
applying to such areas means for destroying radicals, specifi-
cally heated profiled rolls or laser beams. Free radicals re-
maining in the other areas of the material will initiate grafting
of the monomeric compound onto the material when the sheet is
introduced into the next grafting solution, which causes local-
~; lized contractions from which ornamental texturing results.
Finally, the material is rinsed, dried and stored.
(6) The sheet material is first modified in a partialmanner only by irradiating it with ionizing rays in an inhomo-
geneous irradiation field, preferably using shielding stencils
or by applying beams of ionizing radiation which are regulated
in intensity and/or direction, and then introducing it into a
, ':.
-6-
1~4i~3B4
grafting solution wherein locallized grafting of the monomeric
compound takes place and with it locallized contractions occur,
and thus ornamental texturing results. The material is then
modified homogeneously using the pre-irradiation method, in
which the material is irradiated with ionizing rays in a homo-
geneous irradiation field, and thereafter treated in a grafting
solution. Finally, the sheet is rinsed or washed, dried and
stored.
(7) The procedure set out in (6) is used, except
that the sheet material, after irradiation in a homogeneous
irradiation field, is not again brought into contact with a
~ grafting solution.
- (8) Using the partial modification procedure of (6)
-~` and then the simultaneous method to effect homogeneous modifi-
cation of the sheet material by impregnating it with grafting
solution and then exposing it to ionizing rays in a homogeneous
irradiation field. Finally, the sheet material is rinsed and/
or washed, dried and stored.
(9) The sheet material is modified in a partial man-
ner first by irradiating with ionizing rays in a homogeneousirradiation field, and then limiting the radicals to parts only
of the material using a set-up designed to destroy radicals
in other parts of the material. In the ensuring treatment in
; a grafting solution, locallized grafting of the monomeric
compound occurs, and thus ornamental texturing results. There-
~; after, the sheet is modified in a homogeneous manner using the
pre-irradiation method, irradiating first with ionizing rays
in a homogeneous irradiation field, and then treating the sheet
in another grafting solution. Then, the sheet is rinsed and/or
washed, dried and stored in an appropiate manner.
(10) The procedure of (9) is used, without treating
~4Z3B4
the sheet in a second grafting solution after irradiation in a
homogeneous field.
(11) First the partial modification procedure of (9)
is used, followed by the simultaneous method to achieve homo-
geneous modification, the sheet being impregnated with grafting
solution and then exposed to ionizing rays in a homogeneous
field of irradiation. Finally, the sheet is rinsed and/or
washed, dried and stored.
(12) Irradiation of the sheet material required for
initiating homogeneous as well as partial modification can take
place in one irradiation unit, for example, in an electron
accelerator.
(13) The sheet material is irradiated homogeneously
and brought into contact with a grafting solution. Thereafter,
a heated profiled roll is applied to destroy, in locally limited
areas, the radicals which remain in the material. Then, the
sheet is impregnated with a grafting solution and again irrad-
iated in a homogeneous irradiation field.
(14) The material is first irradiated homogeneously,
and immediately thereafter is irradiated in a partial manner,
~and then brought into contact with a grafting solution.
(15) The sheet is irradiated homogeneously. Radicals
which form are then destroyed in limited areas by applying
; heated profiled rolls which is followed by another homogeneous
irradiation. The material treated in this manner is then
brought into contact with a grafting solution.
. The monomeric compound required for the homogeneous
~; or partial modification procedure can be applied either as
liquid or as vapour.
Known procedures such as rinsing, washing, drying,
~- can be placed in any sequence between the individual processing
-8-
steps. ~4~384
When effecting partial modification of the material
by grafting, the material can be kept loose or flat, under
preset tension.
According to the invention, the effect created by
partial modification of the material, specifically ornamental
texturing, can be enhanced by treating the material with hot
water, steam or hot air.
The invention will now be described in greater detail
by means of a number of examples.
` Example 1
A flat fabric chain kitted from polyamide silk fibres
weighing 100 g/m2 and having a width of 1.80 m is irradiated
under the scanner of an electron accelerator of the insulating
nuclear transformer type with electrons supplied at the energy
level of 300 keV. A radiation dose of 4X106 rads is applied
to the flat chain knitted fabric. After homogeneous irradia-
tion, the fabric is fed continuously into a grafting solution
to initiate homogeneous grafting. The grafting solution consists
of 20~ acrylic acid in water, and is kept at a temperature of
~- 38C. The fabric remains in the grafting solution for 10 min-
utes. During homogeneous grafting of acrylic acid onto the
knitted polyamide silk fabricl the material is kept under pre-
- set tension. Then the fabric is rinsed, washed and dried,
before it is again irradiated under the scanner of an electron
acelerator. In the second irradiation, however, parts of the
irradiation field are shielded using perforated discs fabricated
from 1 mm thick aluminum. The fabric is thus irradiated in
- selected areas only. The pattern of selected areas is determ-
ined by the perforationsin the aluminum disc. The radicals
which form in selected areas of the fabric initiate locallized
~4Z3B4
grafting, when the material is fed into the next grafting
solution, a 30~ solution of acrylamide in water at a temperature
of 45C. Grafting is allowed to proceed for 15 minutes. The
localized grafting of acrylamide onto the fabric causes local-
ized contractions from which ornamental texturing results. The
fabric is then rinsed and treated with sodium ions to trans-
form the homogeneous grafted acrylic acid groups into the sod-
ium salt. Finally the fabric is rinsed again and dried.
Using the above described procedure one obtains a
hydrophilic, easy dyeable, antistatic flat chain knitted fabric
of polyamide silk fibres with a permnament ornamentally tex-
tured finish. The textile material in sheet form has improved
comfort factors and physical properties, and is especially
suited for both outer and inner wear.
Example 2
A polypropylene foil, 60 ~m thick and 1.65 m wide,
is irradiated under the scanner of an electron accelerator.
The electrons are supplied at the energy level of 300 keV. A
radiation dose of 8X106 is thereby absorbed. Irradiation is
followed by treatment in a grafting solution, which contains
~: ,
~ 8% acrylamide and 10% acrylic acid dissolved in water. The
. .
grafting temperature is 35C. The grafting reaction is main-
; tained for 25 minutes. The foil is then rinsed to remove
residual monomeric compounds. Free radicals still remaining
-~ ~ in the material are then destroyed in limited areas only by
means of a heated profiled roll which is followed by treatment
~`` of the foil for lO minutes in a 20% aqueous solution of acrylic
acid kept at its boiling temperature. Localized grafting of
~- acrylic acid onto the polypropylene foil and localized contrac-
tions occur from which ornamental texturing of the foil results.
There is thus obtained a foil which is nonstatic and
~,
--10--
~.~423~34
easy to dye. The textured plastic foil has differential absorb-
ancy for dyes, and can be used for decorative purposes, for
example, for interior decorating.
Example 3
The method of Example 2 is used, but, in order to
; enhance the texturing effect, the foil is exposed, to a second
irradiation step at a dosage of 5X106 rads. The second irradia-
tion step is effected after homogeneous grafting in the aqueous
solution of acrylamide and acrylic acid.
Example 4
A 1.80 m wide knitted fabric containing 50% cotton
and 50% polyamide fibres and weigpihg 250 g/m is irradiated
with electron beams in the homogeneous irradiation field of an
electron accelerator of known construction until 2X106 rads are
absorbed by the fabric. The electron beam is supplied at an
energy level of 450 keV. The knitted fabric is then fed into
an alcoholic solution of styrene containing 50% methyl alcohol
and 50% styrene. The fabric remains in the grafting solution
for lS minutes. The grafting bath is kept at 40C. The knitted
fabric is irradiated a second time until a dose of l.Sx106 rads
. ~
is absorbed. The free radicals formed in the knitted fabric
during the second irradiation are then destroyed locally by
heat generated within the fabric when guided laser beams are
directed onto it. Then, in a second grafting solution, styrene
"
~ can be grafted onto the knitted fabric locally only, which
`1 causes localized contractions from which an ornamental textur-
: i,,
~ ~ ing results.
, ~
` In this manner, a knitted fabric is obtained with a
permanent hydrophobic finish; a knitted fabric which is volumi-
nous and shows a pleasant character. A knitted fabric of this
. type is especially suitable for weather resistant outdoor
, ,
--11--
garments. 1~4~384
Example 5
A 1. 40 m wiae sheet of fabric of 50% polyamide and
50% polyester fibres and weighing 220 g/m2 is immersed for 5
minutes in an aqueous solution of acrylic acid maintained at
20C. The solution contains 25% acrylic acid. The fabric is
then irradiated under the scanner of an electron accelerator
until 2X106 rads are absorbed. The electron beam is supplied
at an energy level of 450 keV. A second irradiation step fol-
lows. A guided electron beam is applied to inscribe 5 mm dia-
meter circles on the fabric at 12 mm centres, restricting the
free radicals. The fabric is then treated for 15 minutes in
an aqueous solution of acrylic acid at 25% acid strength. The
grafting bath is kept at 45C. Localized grafting occurs and
thus localized contractions to effect ornamental texturing of
the fabric. The material is then rinsed and dried.
Thus, a permanently finished fabric is produced from
polyamide/polyester fibres with improved dyeability, and mois-
1~ ture absorbancy properties, and of a voluminous character.
~ 20 This type of fabric can be used for fashion textiles with im-
proved comfort factors and physiological properties.
Example 6
A nonwoven fabric, which contains 50% polyacrylnitrile
and 50% polyamide fibres, and weighing 160 g/m2, is soaked with
monomeric methylmethacrylate, and then wrung to show a weight
.:,
~ ~ gain of 80%. The material is then irradiated in the homogeneous
~ .~
~`i; field of irradiation of an electron accelerator until 3X106 rads
`` have been absorbed. The electron beam energy level is 300 keV.
' During irradiation, on the one hand, monomeric methylmethacry-
late polymerizes and, on the other hand, free radicals form in
the fleece. By the subsequent use of a heated profiled roll,
:
-12-
1~4~:3B4
free radicals are destroyed in limited areas of the fleece.
This localized destruction of radicals in the fleece is followed
by treating the fleece for 15 minutes in an alcoholic solution
of styrene. The solution contains 60% styrene and 40% methyl
alcohol. The solution is kept at 35C. Grafting of styrene
takes place in limited areas of the fleece only. Localized
contractions occur.
The finished nonwoven textured fabric thus obtained
is distinguished by sound resistivity to rot and acids. The
fabric findsapplications specifically as a technical textile
material.
Example 7
A 2.00 m wide sheet of fabric made from 60~ poly-
acrylnitrile and 40% polyester fibres, and weighing 140 g/m
is irradiated under the scanner of an electron accelerator in
limited areas only using a shielding stencil. The radiation
dose absorbea by the fabric is sxlo6 rads at an energy level of
300 keV. The fabric, irradiated in limited areas only, is
treated for 15 minutes in styrene vapour, whereby localized
grafting of styrene onto the material takes place. The localized
grafting causes localized contractions. The contractions are
increased when the material is subsequently treated at 120C
` with hot air. A fabric with ornamental texturing is thus ob-
tained. The fabric is then irradiated again; this time in the
- homogeneous field of irradiation of an electron accelerator,
and treated for 15 minutes in an alcoholic solution of styrene.
-~ The alcoholic solution contains 50% styrene and is kept at 40C.
The solvent and residual monomeric compound are then removed.
A fabric of extreme weather fastness is thus obtained.
Example 8
A fleece containing 70% cotton and 30% polypropylene
-13-
1~94Z384
fibres, and weighing 180 g/m2 is irradiated under the scanner
of an electron accelerator using a screening stencil made from
1 mm thick aluminum with patterned perforations. The electron
beam is supplied at an energy level of 300 keV. A radiation
dose of 1.3x106 rads is absorbed by the material. Immediately
following the irradiation of the fleece in limited areas, it is
treated for 10 minutes in an aqueous solution of acrylic acid.
The solution contains 25% acrylic acid. The temperature of
the solution is kept at its boiling point. Localized grafting
of acrylic acid onto the fleece thus occurs. The fleece is
then irradiated again; this time, however, in the homogeneous
;s field of irradiation of an electron accelerator until 1.8x106
rads are absorbed which is followed by treatment of the fleece
;` for 10 minutes in a boiling solution of acrylic acid in water.
The solution contains 25% acrylic acid. A reinforced fleece
;~ ~ of cotton/polypropylene fibres is thus obtained. The fleece
can be dyed in a bath, and is bulky.
:~ Example 9
..,:,~
A 70 ~m thick foil of polyamide material is irradiated
in an inhomogeneous irradiation field of an electron accelerator
until 6X106 rads are abosrbed using a shielding stencil; the
.
~-i electron beam having an energy level of 25 keV. The foil is
;`~ then treated for 10 minutes in an aqueous solution of acryl-
amide. The solution contains 30% acrylamide and is kept at
60C. The foil is rinsed in water, and then kept for 3 minutes
-~ in an aqueous solution of acrylic acid. The solution contains
15% acrylic acid and is maintained at 25C. The foil is then
irradiated with electron beams in a homogeneous irradiation
field until 3X106 rads are abosrbed.
The finished foil of polyamide material has ornamental
patterns, is easily dyed and can be used for decorative purposes.
-14-
384
Example 10
A floor covering material formed of polyamide fibres
is irradiated in the homogeneous irradiation field of an elec-
tron accelerator until 7X106 rads are absorbed. The electron
beam has an energy level of 1 MeV. Then, radicals which have
formed are destroyed in limited areas by applying a heated pro-
filed roll to the material. After destroying radicals in limited
"^ areas, the floor covering material is treated for 10 minutes in
an aqueous solution of acrylic acid, which is brought to its
boiling temperature. The solution contains 28% acrylic acid.
The floor covering material is then squeezed between two pinch-
,
ing rolls to produce a gain in weight of 120%. Thereafter
the material is again irradiated in the homogeneous irradiation
field of an electron accelerator until 2X106 rads are absorbed.
~; The floor covering material is then washed with water at 50C.
Sodium ions are applied to neutralize the grafted acrylic acid
groups. Finally, the floor covering material is dyed with
basic dyes.
The finished floor covering material is bulky, shows
a distinctive pattern in colour shades and has a permanent
flnish which exhibits soil repellency and antistatic
characteristics.
~ Example 11
--; A fabric of polyester fibres, which weighs 160 g/m2
is irradiated in a homogeneous irradiation field of an electron
accelerator with electron beams until lx107 rads are absorbed.
Then, the reactive species which form (free radicals, peroxides,
hydroperoxides) are destroyed locally by heat applied to lim-
ited areas only using hot profiled rolls. The fabric is then
~ 30 brought into contact for 15 minutes with a boiling solution of
`-~ acrylic acid in water. The solution contains 12% acrylic acid.
:~
-15-
:
:~
1~4Z3B4
The fabric is then thoroughly rinsed with water at 25C, and
then brought in contact for 3 minutes with an aqueous solution
of acrylamide kept at 38C. The solution contai`ns 20~ acryl-
amide. The wet fabric is squeezed between rolls to a weight
;~ increase of 100~, and is then irradiated in the homogeneous
irradiation field of an electron accelerator until 2X106 rads
are absorbed.
A bulky polyester fabric is thus obtained which
is partially dyeable. The finished fabric has good moisture
absorbancy properties and is soil repellent. The fabric is
well suited for the garment industry.
Example 12
A flat sheet of chain knitted fabric formed from poly-
amide silk fibres and weighing 100 g/m2, is irradiated in the
homogeneous irradiation field of an electron accelerator until
2X106 rads are absorbed. The electron beams are supplied at
an energy level of 0.3 MeV. The irradiated fabric is fed con-
tinuously through a solution containing 15% acrylic acid. The
fabric remains in the solution for 10 minutes. In this manner,
homogeneous grafting of acrylic acid onto the polyamide fibres
is effected. The flat chain knitted fabric, which carries
grafted polyacrylic acid groups, is then passed over a heated
profiled roll. Free radicals remaining in the sheet are des-
troyed in limited areas only. The material is brought in con-
tact with a solution of acrylamide and kept in it for 10 minutes.
The solution contains 12~ acrylamide. Acrylamide will be
` grafted only onto those areas of the fabric in which the free
radicals have not been destroyed by contact with the heated
profiled roll. Localized contractions oacur from which a
- 30 texturing results. The texturing effect is then fixed by
~ irradiating the sheet in a homogeneous irradiation field of
.
-16-
3B4
an electron accelerator. Finally, the knitted fabric is washed
in a bath, dried, and wound on rolls.
A textured material in sheet form is thusobtained
which shows improved moisture absorbancy, is antistatic and is
partially dyeable. The permanently textured knitted fabric is
well suited for shirts, blouses and aprons.
Example 13
.'~ .
A material in sheet form containing 50% polyamide and
50~ polyester fibres and weighing 250 g/m2 is irradiated in the
homogeneous irradiation field of an electron accelerator until
a radiation dose of 2X106 rads is abosrbed. The electron
beam is supplied at the energy level of 0.5 MeV. A supplemen-
tary localized irradiation is then applied until a dose of
5X106 rads is absorbed by the material. Aluminum stencils (1
mm thick) are inserted into the irradiation field. The stencils
have circular perforations 8 mm diameter, with centres 16 mm
apart. After passing through the two consecutive irradiation
fields, the sheet is brought into contact for 8 minutes with
a 20% aqueous solution of acrylamide at 25C. After washing
in a bath, a textured hydrophilic textile material in sheet
form is obtained which is suitable for outer wear.
Example 14
`- A material in sheet form which contains 50% polyamide
and 50~ polyester fibres, and which weighs 250 g/m2 is irradiated
~- in a homogeneous irradiation field until 5X106 rads are absorbed.
The electron beam supplied has at an energy level of 0.5 MeV.
Thereafter, the material is brought into contact with a heated
profiled roll. A second irradiation is then effected until a
dose of 2X106 rads is absorbed. After the twofold treatment,
the material is brought into contact with 20% aqueous solution
~ of acrylamide kept at 20C. Contact of the material with the
,~ .
-17-
- `~
1~4'~384
solution is maintained for 8 minutes. The material is then
washed in a bath. A hydrophilic textured material in sheet
form results, suited for outer wear.
The grafting polymerization generated by radiation
induced chemical reactions described in the above examples can
also be induced by known chemical procedures used to initiate
grafting polymerization.
Example 15
A sheet material containing 50% polyamide and 50~
polyester fibres, and weighing 250 g/m2 is irradiated in the
homogeneous irradiation field of an electron accelerator with
electron beams supplied at 1 MeV using a shielding stencil
made from 0.5 mm thick aluminum. Since the thickness of the
shielding stencil is less than the range of the electron beam
applied at 1 MeV, the material is irradiated both homogeneously
and partially in a single operation. The material in sheet
form is then brought into contact with a 20% aqueous solution
of acrylamide. The temperature of the solution is kept at
20C and contact is maintained for 8 minutes. The material is
.
then washed in a bath. A hydrophilic texture material in sheet
.,
form is thus obtained which is suitable for upper garments.
.:
~:
,-
-~.
~,.....
,
~ 30
'`~
"',
-18-
