4821 4825.output

* GB785228 (A)
Description: GB785228 (A) ? 1957-10-23
Improvements relating to shell moulds and the casting of metal therein
Description of GB785228 (A)
PATENT SPEC 1 FICATION 71
Date of Application and filing Complete Specification:
Jan 28, 1955 No 2623155.
h' Application made in United States of America on Feb 18, 1954.
I Complete Specification Published: Oct 23, 1957.
Index at Acceptance:-Classes 83 ( 1), F( 8 U: 11: 11 X:13 BX); and 87
( 2), Al R( 143: 22 X: 64: 66: 73: 102).
International Classification:-B 22 c B 28 b B 29 d, h, j.
COMPLETE SPECIFICATION.
Improvements relating to Shell Moulds and the Casting of Metal
therein.
We, GENERAL MOTORS CORPORATION, a Company incorporated under the laws
of the State of Delaware in the United States of America, of Grand
Boulevard in the City of Detroit, State of Michigan, in the United
Status of America (Assignees of ROBERT FRANCIS THOMSON, RAYMOND
STEWART AMALA and CHARLES MATTHEW EBERHARDT), do hereby declare the
invention, for which we pray that a patent may be granted to us, and
the method by which it is to be perlormed, to be particularly
described in and by the following statement: -
This invention relates to casting metals in a shell mold; that is, a
thin-walled mold formed from a mixture comprising sand and a synthetic
resin binder, by first applying this mixture to a heated metal pattern
so as to fuse the resin and thus bond together the sand, and then
"curing" the mixture by further heating.
By the invention a shell mold may be sufficiently well supported
during metalpouring as to permit a reduction in the thickness of the
mold-wall, resulting in economy in the manufacture of the molds, by
the use of less material.
The invention is applicable above all to shell molds which have been
made thinner by the exertion of pressure on the layer of raw mixture

after it has been applied to the metal pattern.
The scope of the invention is defined by the appended claims.
How the invention may be carried out will now be particularly
described with reference to the accompanying drawings, in which:Figure
1 is a somewhat diagrammatic view showing in cross section apparatus
for applyPr;'ce ing a mixture of sand and resin to a heated pattern.
Figure 2 is an elevational view showing a pattern and adhering layer
of sand and resin, and a pressure member above the pattern.
Figure 3 is a view similar to Figure 2, but with the layer of sand and
resin compacted by the pressure member.
Figure 4 is a fragmentary perspective view of a formed shell, forming
one-half of a complete mold, stripped from the pattern.
Figure 5 is a cross-sectional view of two mold halves as shown in
Figure 4, assembled to form a complete mold.
In the drawings, 10 is a pattern plate having a surface 11 in the
shape of one-half of a cylinder The pattern may be heated by an
internal heating element 12 of the electric resistance type Above the
pattern plate is a member 14 having peripheral portions 16 resting on
the pattern plate and having a cut-out portion 18 conforming generally
to the shape of the pattern plate but spaced therefrom, thus forming
with the pattern a generally closed cavity 19 for receiving sand and
resin Above the member 14 is a blowhead 20 containing a supply of
sand-resin mixture indicated by 22 Openings 24 extend through member
14 from the blow-head to the mold cavity A pipe 26 is provided for
applying air pressure to the top, of the supply of sand-resin mixture
to force sand and resin through the openings 24 to completely fill the
mold cavity formed by heated pattern plate 10 and member 14 In the
form shown in Figure 1 the mold cavity is such that the shell of sand
and resin is thicker at the portions 27 and 28 to give added strength
at these portions The pattern plate is heated, a typical temperature
being 500 F and by 35,22 $ 785,22 '8 this heat the resin in the
sand-resin mixture in the mold cavity is fused and binds the sand
grains together to form a partially cured relatively porous layer or
shell adhering to the heated pattern The pattern plate and partially
cured layer or shell of sand and resin 29 adhering to the pattern are
then removed and placed under the die 30 of a press, having an
accurately contoured surface 32 conforming generally to the shape of
the back of the adhering layer of sand and resin The dimensions of the
die may be such as to squeeze or press portions of the shell more than
others For example, it may be desirable in some cases to apply greater
pressure to the portion of the shell more remote from the mold cavity,
to give greater strength at such portion An electric resistance heater
34 is provided for heating the die 30 The pressure die is lowered to
contact and then press or squeeze the layer of sand-resin adhering to

the heated pattern plate and reduce its thickness, preferably about 20
%-25 % By means of heat applied both to the pattern and pressure head
the squeezed layer of sand and resin is rapidly cured At a temperature
of 500 F, for example, a shell of '/32 " thickness is cured in about
15-20 seconds The formed and cured shell 38 is then stripped from the
pattern.
Two of the mold halves 38, either with or without gluing together, are
then placed between a pair of refractory back-up members 40, with the
mold parts nesting in the closely fitting refractory back-ups.
The back-up members 40 are made on a suitable pattern, which may
itself be a shell mold formed on the contoured die 30 and to which a
water-resistant coating such as shellac or varnish has been applied A
second and preferred method of making a pattern for the back-up
members is to cast a non-shrinking material, metallic or nonmetallic,
such as type metal, cast synthetic resin material, or cold-formed
rubber, into the impression 32 of the contoured die or press head 30
The most desirable characteristics of this pattern material are moderN
ate strength to permit the production of more than one cast back-up
member, resistance to deformation due to the weight of the cast
refractory material, or due to externally applied pressure after
casting the refractory material The pattern material is then stripped
from the press head and is ready for use after suitable curing.
The pattern, whatever its nature is then used to form the refractory
back-up member The material for forming the back-up member is an
aqueous slurry comprising refractory cement and refractory oxides The
slurry may be made by making, at room temperature a mixture of ten
parts of castable fj 5 refractory cement composed essentially of
calcium aluminate cement, a grog consisting of refractory oxides such
as silica, alumina and magnesia; and two parts water This is mixed to
a uniform consistency either manually or mechanically 70 The
previously prepared pattern for the back-up member is suitably mounted
and a retainer is placed around the pattern This retainer may be a
simple sheet metal frame.
The refractory slurry is cast on to the pattern 75 and levelled at the
edges of the retainer.
The latter is preferably of accurate dimension and such shape as to
permit withdrawing refractory material either before or after curing
and inserting said refractory into So matching frames mounted on the
device for holding the shell mold.
The cast refractory material is then suitably cured to produce a dry
rigid mass, which may be done by air drying for a 85 suitable period
(e g 24 hours at room temperature followed by a 4005 F treatment for
two hours) It may be desirable to cure for a short time (e g 6-8
hours) at an elevated temperature (e-g 300 F) to hasten and 90 insure

evaporation of uncombined water.
Figure 5 shows the mold halves 38 in nesting relation forming a mold
cavity 39 for receiving molten metal The refractory back-up members
40, however formed, 95 closely fit the contour of the back of the
shell mold halves The back-up members 40 are mounted in frames 42 and
the frames and refractory material may be held or clamped together by
mounting plates 44 Any other 100 suitable means may be provided to
hold the back-ups and shell mold halves For examnple, one of the
refractory back-up inembers may be mounted on a spring loaded plate
with the other on a cross head movable 105 by means of a piston in an
air cylinder The shell mold part and back-up carried by the cross head
are movable to open and close the mold The spring loading equalizes
the pressure on the mold parts when the mold is 110 closed.
Each of the refractory back-up members is separate from the shell mold
part and may be used in forming a multiplicity of castings, whereas
each shell mold is des 115 troyed in making a single casting.
In one typical example a resin coated sand of about 140 American
Foundrymen's Society Number containing 3 % phenol formaldehyde resin
and one-half c c of a 120 liquidizer per pound of coated core sand mix
for improving the green strength was placed in a mold blowing machine
An electrically heated pattern (temperature 500 F) was raised into the
'blow" -osition 125 (Figure 1), the pattern with adhering sand was
retracted, and the partially cured shell on the pattern was placed in
contact with an electrically heated press head ( 500 ' F) for about 20
seconds duerine thich time the 133 o the back-up members being made of
an aqueous slurry comprising refractory oxides and refractory cement.
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* 5.8.23.4; 93p
* GB785229 (A)
Description: GB785229 (A) ? 1957-10-23
Improvements in and relating to the production of alkylene oxide polymers

A high quality text as facsimile in your desired language may be available
amongst the following family members:
BE544935 (A) DE1109901 (B) FR1146098 (A) US2870099 (A)
US2870100 (A)
BE544935 (A) DE1109901 (B) FR1146098 (A) US2870099 (A)
US2870100 (A) less
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The EPO does not accept any responsibility for the accuracy of data
and information originating from other authorities than the EPO; in
particular, the EPO does not guarantee that they are complete,
up-to-date or fit for specific purposes.
PATENT SPECIFICATION
Inventors: DAVID GORDONSTEWART, DHAFIR YUSEF WADDAN and b^ ^s EDWARD
TEGGIN BURROWS Date of filing Complete Specification: Dec 30, 19
Application Date: Feb4, 1955 No 3 ' Complete Specification Published:
Oct 23, 1957.
155.
454/55.
Index at acceptance:-Classes 2 ( 3), B 4 (B: H: J); and 2 ( 5), R 27 K
2 F.
International Classification:-CO 7 d C 08 g.
COMPLETE SPECIFICATION
Improvements in and relating to the Production of Alkylene Oxide
Polymers We, PETROCHEMICALS LIMITED, a British Company, of 170,
Piccadilly, London, WA, do hereby declare the invention, for which we
pray that a patent may be granted to us, and the method by which it is
to be performed, to be particularly described in and by the following
statement: -
The present invention relates to the prodution of alkylene oxide
polymers, and to the resulting polymers The present' invention is
concerned particularly, but in no way exclusively, with the production
of polymers of ethylene oxide and 1,2-propylene oxide.
According to the present invention a process for the production of a
polymeric material from an alkylene oxide comprises bringing an
alkylene oxide into contact with a catalyst of the general formula:

Me RR 1 wherein Me is a metal selected from Groups II and III of the
Periodic Table, R is a hydrocarbon radical, R ' are x members selected
from hydrogen, the halogens, hydrocarbon radicals, alkoxy radicals and
secondary amino radicals, and x is the valency of the metal Me minus
one.
The hydrocarbon radical or radicals present in the catalyst used in
the process of the present invention is or are preferably straight or
branched chain alkyl radicals containing up to 10 carbon atoms The
secondary amino radical or radicals, when present, is or are attached
to the metal (Me) through the nitrogen atom which may form part of a
ring, as for example in the case of the piperidyl radical.
The preferred catalysts are organic compounds of aluminium, zinc and
magnesium of the above general formula, the aluminium compounds being
particularly preferred.
Particularly good results have been obtained with the following
catalysts:
Tri-ethyl aluminium, tri-isobutyl aluminium, tri-octyl aluminium,
di-isobutyl aluminium hydride, di-ethyl aluminium ethoxide, di-ethyl
aluminium chloride, ethyl aluminium dibutoxide, di-ethyl piperidyl
aluminium, diethyl zinc, ethyl zinc butoxide, di-ethyl magnesium.
The reaction mixture at the end of the reaction will usually contain,
as the polymeric material, mainly the higher molecular weight polymers
In practice mixtures of such higher molecular weight polymers are
obtained, the average molecular weight of which will depend on the
reaction conditions employed However, when ethylene oxide is reacted
in accordance with the invention, lower molecular weight polymers
thereof can often be obtained as well These low molecular weight
polymers include cyclic polymers of ethylene oxide such as dioxane and
the hitherto unknown cyclic tetramer which has the structure C 1 L-CH
1-O-CH,-CH, O< > O CH 2-CH,-O-CH2-CH.
Such cyclic polymers are valuable as high boiling neutral solvents and
they can be separated from the higher molecular weight ethylene oxide
polymers, for example, by selective solvent extraction as will be
described later.
A further feature of the present invention accordingly consists in
contacting ethylene oxide with the catalyst defined above, separating
the resulting polymeric material into a higher molecular weight and a
lower molecular weight polymer fraction and recovering dioxane and/or
the cyclic tetramer of ethylene oxide (if present) from the lower
molecular weight polymer fraction Preferably the catalyst used in the
production of low molecular weight cyclic polymers is a tri-alkyl
aluminium compound and in particular triethyl aluminium and
tri-isobutyl aluminium.
The process of the present invention may be carried out in the

presence of a solvent, e g, an aromatic or an aliphatic hydrocarbon, a
chlorinated hydrocarbon or an ether, or without a solvent In general
the presence of a solvent is desirable when the cyclic polymers of
ethylene oxide are required in addition to the higher -molecular
weight polymers, and in general higher dilutions of the reaction mixIs
ture with solvent favour the formation of these cyclic polymers in
relation to the amount of higher molecular weight polymers formed.
The reaction time may be between a few hours and several days
depending on the temperature employed In general higher temperatures
reduce the time needed for the reaction to take place The temperature
at which the reaction can be carried out can be between 00 C and 2000
C or higher, and in general when using ethylene oxide as starting
material, the lower reaction temperatures, e g, up to about 1000 C are
often to be preferred when the cyclic polymers of ethylene oxide are
also required.
The reaction can be carried out under atmospheric pressure or under
pressures up to atmospheres or higher The choice of catalyst and
temperature at which the reaction is carried out are an effective
means of controlling the viscosity of the resulting higher molecular
weight polymers.
In carrying out the process of the present invention the alkylene
oxide or a solution thereof is generally added to the catalyst or more
conveniently to a solution of the catalyst in e g, benzene or diethyl
ether, but the addition may be in the reverse order if desired.
The resulting mixture is then allowed to reach, or if necessary is
heated to, the desired reaction temperature at which it is maintained
for the required time, usually with constant or intermittent stirring
In some cases external cooling may be necessary to remove excess heat
of reaction in the initial stages The reaction is exothermic, but the
reaction mixture can, if necessary, be heated to ensure completion
Preferably the reaction is carried out under pressure in an autoclave.
At the end of the reaction, the excess alkylene oxide is recovered by
distillation and the polymeric product is at least partially freed
from catalyst for example by dissolving the reaction product in water,
filtering off the resulting precipitated metal hydroxide and
evaporating the solution If the reaction product is insoluble in
water, it can be freed from catalyst by extraction with dilute mineral
acid or by dissolving the polymer in a solvent, extracting the
resulting solution with water and removing metal hydroxide by
filtration.
The resulting polymeric product is then washed with a solvent (e g, an
aliphatic hydrocarbon) in which the higher molecular weight polymers
are insoluble, thereby extracting any lower molecular weight oils
(including low 70 molecular weight cyclic polymers when formed) which

are produced at the same time as the higher molecular weight polymers.
Alternatively all the polymeric product is dissolved in a solvent and
the higher molecular 75 weight polymers are precipitated by adding a
liquid which is a non-solvent for the high molecular weight polymers
but which is miscible with the original solvent Concentration of the
filtrate obtained by removing the 80 precipitated polymer often yields
lower molecular weight oils (comprising, in the case of ethylene oxide
as starting material, mainly cyclic polymers) in amount depending on
reaction conditions and catalyst employed 85 Anbther method of working
up the polymeric reaction product is to dissolve it in water and to
extract any -lower molecular weight oils (including cyclic polymers
when formed) with a water-immiscible solvent such as diethyl 90 ether
The resulting aqueous extract is then worked up to yield the higher
molecular weight polymers.
The cyclic polymers of ethylene oxide are conveniently fractionated to
yield dioxane and 95 the cyclic tetramer The higher molecular weight
polymers of alkylene oxides are not usually separated into individual
polymers but are used as mixtures The higher molecular weight polymers
can, if necessary, be further 100 treated by aqueous or acid
extraction in order to reduce still further the quantity of catalyst
which may remain therein.
The higher molecular weight polymers have molecular weight above
20,000 and are 105 valuable as thickening agents and those obtained
from ethylene oxide can be processed into thin water-soluble films.
The cyclic tetramer of ethylene oxide which is a novel compound is a
clear, colourless, 110 mobile liquid which boils at 118-119 C.
under a pressure of 15 mm of mercury and crystallises at 19 750 C Its
refractive index was found to be: n D 2 o= 1 4606, n D 2 '0 = 1 4628:
and its density d 2525 = 1 109 The molecular 115 weight as determined
by the cryoscopic method using benzene and naphthalene as solvents is
176 2 The Molar Refraction was found to be 43.57 as compared with a
calculated value of 43.52 It is miscible with water and most 120
organic solvents and its infra-red spectrum is similar to -that of
dioxane.
In the following examples which illustrate the process of the present
invention, Examples 1-14 refer mainly to the production of high 125
molecular weight polymers of alkylene oxides and Examples 15-18 refer
mainly to the production of lower molecular weight cyclic polymers of
ethylene oxide The parts are parts by weight unless otherwise stated:
130 785,229 785,229 3 EXAMPLE 1.
Gaseous ethylene oxide ( 88 7 parts) was passed into a solution of
triethyl aluminium ( 1 part) in benzene ( 88 parts) During the
addition cooling was applied and when the addition had been completed
the mixture was cooled to O O C After maintaining the reaction mixture

at this temperature for five days, the excess ethylene oxide was
distilled off and a clear viscous benzene solution of the polymeric
product was obtained This was added slowly to petroleum ether ( 100
parts) with stirring A colourless fibrous solid ( 12 5 parts) was
precipitated and was filtered off and dried The relative viscosity
(fir) of this product in 0 1 % trichlorethylene solution was 1 210 The
solid product ( 5 parts) was dissolved in water ( 500 parts,
containing 1 part of concentrated ammonia) and refluxed for two hours
A white precipitate of inorganic material was obtained, which was
filtered off The polymer, which was recovered from the aqueous
solution by distilling off the water, was dissolved in benzene ( 250
parts) to give a clear viscous solution which was filtered and
precipitated with very dilute aqueous ammonia as described above In
this manner the aluminium content of the solid polymer was reduced
from 1.25 % to 0 05 % The intrinsic viscosity of the polymer was 1
007.
EXAMPLE 2.
Liquid ethylene oxide ( 88 7 parts) was rapidly run into a cooled
solution of triethyl aluminium ( 0 5 parts) in benzene ( 8 8 parts in
an autoclave which was then heated at 160 C for five hours The product
was diluted with benzene ( 100 parts), excess ethylene oxide distilled
off and the resulting solution precipitated with petroleum ether as
described in Example 1 A colourless solid ( 47 parts), of anr= 1 027,
was obtained and concentration of the filtrate yielded an oily residue
( 16 4 parts).
EXAMPLE 3.
Following the procedure described in Example 2, a mixture of ethylene
oxide ( 88 7 parts), benzene ( 8 8 parts) and tri-isobutyl aluminium (
0 5 parts) was heated at 1000 C.
for 65 hours A colourless polymer ( 28 0 parts), of sir= 1 163, and a
small oily residue ( 1 2 parts) were obtained.
EXAMPLE 4.
oxide ( 88 7 parts) benzene ( 8 8 parts) and diisobutyl aluminium
hydride ( 0 5 parts) was heated at 1000 C for 16 hours A colourless
polymer ( 13 2 parts), of or= 1 0945, and an oily residue ( 0 6 parts)
were obtained.
EXAMPLE 5 -
oxide ( 887 parts) benzene ( 8 8 parts) and trioctyl aluminium ( 0 5
parts) was heated at 1500 C for 40 hours A colourless polymer ( 42
parts) of Or= 1 0993, and an oily residue ( 2 2 parts' were obtained.
EXAMPLE 6.

oxide ( 88 7 parts) benzene ( 8 8 parts) and diethyl magnesium ( 0 31
parts) was heated at 1100 C.
for 65 hours A colourless polymer ( 40 parts) andean oily residue ( 1
part) were obtained.
EXAMPLE 7.
oxide ( 88 7 parts), benzene ( 8 8 parts) and ethyl aluminium
dichloride ( 0 5 parts) was heated at 1070 C.
for 65 hours A colourless polymer ( 30 9 parts), of Oir= 1 345, and an
oily residue ( 1 9 parts) were obtained.
EXAMPLE 8.
Following the procedure described in Example 2, ethylene oxide ( 88 7
parts) benzene ( 8 8 parts) and diethyl aluminium ethoxide ( 0 5
parts) were heated at 900 C for 18 hours A colourless polymer ( 8 1
parts), of r= 1 0571, and an oily residue ( 3 02 parts) were obtained.
EXAMPLE 9 90
parts) and ethyl zinc tert -butoxide ( 0 5 parts) were heated at 1400
C for 16 hours A colourless polymer ( 79 5 parts), of qr= 1 076, and
an 95 oily residue ( 1 part) were obtained.
EXAMPLE 10.
1,2-propylene oxide ( 29 parts) in hexane ( 30 parts) was added
dropwise to a stirred solution of triethyl aluminium ( 0 5 parts) in
100 hexane ( 50 parts) at 200 C After stirring at this temperature for
24 hours, the solvent was removed and the water insoluble polymer
extracted with hot dilute hydrochloric acid.
After drying a colourless waxy polymer ( 15 2 105 parts) was obtained
which was soluble in most organic solvents but was insoluble in water.
Ex AMPLE 11.
A solution of diethyl aluminium chloride 110 ( 0.5 parts) in benzene (
20 parts) was added dropwise to a stirred solution of 1,2-propylene
oxide ( 30 parts) in benzene ( 30 parts) After refluxing the mixture
for 24 hours, the product was treated as described in Example 10 115 A
colourless polymer ( 10 7 parts) was obtained.
Ex AMPLE 12.
A mixture of 1,2-propylene oxide ( 80 parts), benzene ( 8 8 parts) and
triethyl aluminium ( 0.5 parts) was heated in an autoclave at 1000 C
for 8 hours After treating the product as 120 described in Example 10
a hard colourless polymer ( 20 parts) was obtained.
EXAMPLE 13.
A mixture of 1,2-propylene oxide ( 80 parts) 125 benzene ( 8 8 parts)
and diethyl zinc ( 0 6 parts) was heated at 1300 C for 18 hours After
treating the product as described in Example 10, a colourless polymer
( 31 2 parts), of Or= 1.0605, was obtained.

The polymers produced in the above 130 785,229 examples had molecular
weights of abovi 20,000 as determined by the intrinsic viscosities of
solutions thereof A sample of knowi molecular weight of 20,000 having
an intrinsic viscosity in solution of 0 5 was used as a basic for
comparison.
EXAMPLE 14.
parts), benzene ( 8 8 parts) and diethyl piperidyl aluminium ( 0 5
parts) were heated at 100 C.
for 65 hours A colourless polymer ( 4 1 parts), of ejr= 1 124, and an
oily residue ( 0 4 parts) were obtained.
EXAMPLE 15.
Liquid ethylene oxide ( 121 8 parts) was added to a solution of
triethyl aluminium ( 1 7 parts) in benzene ( 14 1 parts) at O C in an
autoclave, which was then sealed and the contents allowed to come to
room temperature slowly After half an hour the internal temperature
increases to 350 C and a pressure of pounds per square inch (gauge)
was recorded on the gauge After allowing the reaction mixture to stand
for 18 hours at room temperature, the unreacted ethylene oxide was
distilled off and the reaction product washed with petroleum ether (b
p 40-60 C) The non-cyclic polymer which was precipitated was filtered
off and dried Yield of polymer= 19 4 parts The filtrate from the
polymer was distilled using a fractionating column and after the
petroleum ether and benzene had been removed, dioxan ( 18 0 parts) of
b p.
100 5-101 5 C: crystallising point= 11 40 C.: and refractive index n
D'5 = 1 4196 and the cyclic tetramer of ethylene oxide (b p 118119 C:
13 0 parts) were obtained, leaving a viscous, low-melting oil ( 7 3
parts) as bottoms.
EXAMPLE 16.
Liquid ethylene oxide ( 869 7 parts) was added -in portions (each of
173 9 parts) at hourly intervals to a stirred solution of triethyl
aluminium ( 39 17 parts) in anhydrous ether ( 719 parts), the
temperature during the addition being kept below 160 C by cooling with
ice water When the addition was complete, the mixture was slowly
warmed to room temperature and stirred for a further 72 hours.
After distilling off the unreacted ethylene oxide, petroleum ether
(bp< 400 C) was added to the residue and the non-cyclic polymer which
was precipitated was filtered off and dried Yield of polymer= 13 1
parts.
The solvents were removed from the filtrate by distillation and
fractionation of the residue gave dioxan ( 215 5 parts: b p 100 5-102
C.), the cyclic tetramer of ethylene oxide ( 65 76 parts: b p 118-120
C at 15 mm) and an oily residue ( 89 83 parts).

EXAMPLE 17.
A solution of ethylene oxide ( 30 parts) in diethyl ether ( 71 9
parts) was added dropwise with stirring to a solution of triethyl
aluminium ( 22 8 parts) in diethyl ether ( 179 75 parts).
The temperature was maintained at 20 C by cooling with ice water When
the addition was complete, the mixture was stirred at 20 C for 4 hours
and then allowed to come to room temperature After stirring for a
further 24 hours, distilled water ( 300 parts) was added carefully and
then sufficient concentrated hydrochloric acid to dissolve the
precipitated inorganic material: the aqueous layer was separated from
the organic layer and extracted continuously for 48 hours with diethyl
ether The combined ethereal solutions were dried with magnesium
sulphate, filtered and distilled using a fractionating column In this
way dioxan ( 8 2 parts) and the cyclic tetramer of ethylene oxide ( 4
2 parts) were obtained.
EXAMPLE 18.
Liquid ethylene oxide ( 870 parts) was added rapidly to a solution of
tri-iso-butyl aluminium 85 ( 5 parts) in benzene ( 88 parts) in an
autoclave which was then heated at 1005 C for 5 hours.
The product was diluted with benzene ( 1000 parts), unreacted oxide
distilled off, and the resulting solution added slowly to petroleum 90
ether ( 1500 parts) The polymer which was precipitated ( 65 parts of
relative viscosity ijr= 1 055 in 0 1 %' trichlorethylene solution) was
filtered off and dried After removing the solvents and dioxan, the
residue ( 34 parts) was 95 distilled using a fractionating column and
the cyclic tetramer of ethylene oxide ( 20 parts) obtained, leaving an
oily residue ( 13 5 parts) as bottoms.
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* 5.8.23.4; 93p
* GB785230 (A)
Description: GB785230 (A) ? 1957-10-23

Improvements in or relating to electric analogue calculating instruments
A high quality text as facsimile in your desired language may be available
amongst the following family members:
FR1144759 (A)
FR1144759 (A) less
Improvements in or relating to Electric Analogue Calculating
Instruments
We, MARCONI'S WIRELESS TELEGRAPH
COMPANY LIMITED, a company organised under the laws of Great Britain,
of Marconi
House, Strand, London, W.C.2, do hereby declare the invention, for
which we pray that a patent may be granted to us, and the method by
which it is to be performed, to be particularly described in and by
the following statement:
This invention relates to calculating instruments and has for its
object to provide improved and relatively simple instruments which can
be designed to multiply two quantities or to divide. one by the other,
or to extract the square or the square root of a quantity or to find
the square root of the sum of two quantities.
There are numerous cases in which one or other of the foregoing
calculations is required to be made. For example in radar systems with
P.P.I. display it is well known to provide in association with the
display tube a marker which can be moved, under the control of a
handle, to coincide with some particular target displayed, the
movements of the handle from a datum position being arranged to
produce two voltages each representative of one or other of two
mutually perpendicular co-ordinate components into which said
movements can be resolved. It would be convenient to be able to derive
from these co-ordinate voltages a current or voltage representative

directly of the range of the target marked i.e. of the distance of the
marker from the centre of the tube screen. This obviously involves
awing together the squares of the co-ordinate voltages and extracting
the square root of the sum, i.e.
solving a right angled triangle to find the length of the hypotenuse.
As will be seen later the invention can be employed (among other
purposes) to provide an instrument which will solve right angled
triangles.
In all cases the input quantities, i.e. the quantities which are to be
multiplied, divided or so on, are represented by electric currents
proportional to those quantities and the answer to the calculation is
given by the instrument either in the form of a deflection of a
calibrated current meter or in the form of a current proportional to
that answer and available for control or other purposes at a pair of
terminals.
The invention Is illustrated in, and explained in connection with, the
drawings accompanying the provisional specification in which Figure 1
is a diagrammatic representation of a known type of what is herein
termed a "watt-meter element" such as may be employed in carrying out
the invention, and
Figures 2, 3, 4 and 5 are diagrams of embodiments of this invention.
In carrying out this invention use is made of what are herein termed
"watt-meter" elements, that is to say torque developing elements
having two coils and adapted to produce a torque proportional to the
product of the currents through those coils. The ordinary watt meter
has an element of this nature and is why the term "watt-meter element"
is employed herein. The typical watt-meter element shown in Figure 1
has a stator coil S and a rotor coil R, the latter being normally at
right angles to the axis of the former and being arranged for rotation
about a diametrical axis typified in Figure 1 by a suspending shaft A.
In the arrangement of
Figure 1 the stator coil S is divided into two spaced halves so as to
produce a uniform axial field threading the rotor coil. A spring (not
shown) is provided to bias the rotor coil to a normal position at
right angles to the axial field. As is well known if a current I1 is
passed through one coil and a current I2 is passed through the other,
the torque developed by the rotor will be proportional to I x 12 and
it will deflect against its bias spring to a position determined by
that torque.
According to this invention a calculating instrument comprises at
least three watt-meter elements each having a stator winding and a
rotor winding, means mechanically coupling the rotor windings
together, means for applying one input current to a winding of one
watt-meter element to produce a torque in

that element proportional to that current, means for applying a second
input current to at least one winding of a second wattmeter element to
produce a torque in that element proportional to that current, means
for applying an alternating voltage of sub stan- tially constant
amplitude across one winding of the third watt-meter element, means
for producing a direct current output in dependance upon the
alternating current induced in the other winding of the third
watt-meter element, means for applying said direct current to a
winding of one of the first two watt-meter elements and means for
indicating or utilising said direct current
In a multiplying instrument in accordance with the invention there are
three watt-meter elements with one of the two currents to be
multiplied applied to one and the other applied to the other of the
nvo windings of the first element. A constant adjustable direct
current is applied to one winding of the second element. An
alternating voltage is applied to one winding of the third element and
the output from the other winding of that element is, after such
amplification as may be necessary, passed through a phase sensitive
detector to which a phase reference voltage is also applied. The
direct current output from the phase sensitive detector is fed through
the remaining winding of the second element, this direct current being
the current which is indicated and/or utilised. This form of
instrument may be used as a squaring device by passing the same
current proportional to the quantity to be squared through each of the
two windings of the first element
In a dividing instrument in accordance with this invention one input
current is passed through one winding of the first element and the
other is passed through one winding of the second, the other winding
of the second element receiving a fixed input as before. The third
element is arranged as before but the direct current output of the
phase sensitive detector is fed to the remaining winding of the first
element
In a square rooting instrument in accordance with the invention the
two windings of the first element are connected in series and the
input quantity to be square rooted is applied to one winding of the
second element, the remaining winding thereof having a fixed input as
before. The third element is energised as in the previous embodiments
but the output thereof is simply directly rectified by any convenient
unilaterally conductive device and the rectified current passed
through the series connected windings of the first element.
In an instrument in accordance with this invention for extracting the
square root of the sum of the squares of two quantities, there are
four elements of which the first three have
their windings (in each individiual case) con

nected in series. One input current is passed
through the windings of the first element and
the other is passed through the windings of
the second element. One wmding of the fourth
element is fed with A.C. and the output from
the other winding thereof is simply rectified
and applied through the series connected
windings of the third element.
Referring now to Figure 2 which shows a
multiplying instrument, there are three watt
meter elements generally designated 1, 2 and
3 having stator windings S1, S2 or S3 and
rotor windings R1, R2 or R3. The rotors are
mechanically ganged to move together by any
convenient means represented conventionally
by the chain line. One current Il representing
one of the quantities to be multiplied is passed as indicated through
the rotor R1 and
the other current 12 representing the second
quantity is passed throuogh the winding S1.
A constant direct current which may be
adjusted and is represented as derived from a potentiometer supply P
is passed through the
rotor coil R2. A.C. input from any con
venient source, such as the mains, is applied to the winding S3 and
the induced voltage in the winding R3 is amplified by a balanced
amplifier BA, such as the push-pull amplifier shown, and then
rectified by a phase sensitive detector PD. This detector is of well
known form and produces a direct current output
dependent on the phase relationship between the input from the
amplifier BA and a reference phase input which is shown as applied
over lead RP from one of the mains terminals.
The direct current output, smoothed by a Suitable smoothing circuit
SM, is passed through a calibrated current meter M and thence through
the stator S2 of the second element 2.
A pair of terminals are shown across the instrument M to indicate that
the instrument may be replaced by any utilisation or responsive
circuit through which the direct current may be caused to pass and
which may be connected at the terminals T if desired.
The torques developed by the elements 1 and 2 are arranaged to oppose
one another and any difference between the two torques will cause
rotation of the rotor R3 from its rest position in which the coils S3
and R3 are uncoupled. Such rotation will produce in the wiilding R3 a
current dependent upon the extent of the rotation and this current,

after amplification at BA and detection by the phase detector PD, is
smoothed and fed to the coil
S2 to change the torque of the element 2 until it equals that of the
element 1. When this occurs the rotor R3 will be returned very close
to its rest position and there will be practically zero output from
the phase detector. This condition will obviously only be established
when the torque of the element 2 is proportional to Ii X I and since
one current input that to the rotor R2-is fixed, the reading of the
current through the stator S2 will be indicative of the product 1112.
Obviously if I1 and
I2 are made the same (l) the reading of the instrument will be
proportioslal to I12.
In the dividing instrument shown in
Figure 3 the current Il is passed through the stator S2 and the
smoothed direct current output from the phase detector PD is passed
through the rotor RI of the first element In other respects the
arrangement is the same as
Figure 2 and it will be seen that the reading of the meter M will be
representative of 12/Il.
In Figure 4, which shows a square rooting instrument, the rotor and
stator windings of the element 1 are connected in series, the current
representative of the quantity al) to be square rooted is passed
through the stator S2 ot the element 2 and the constant adjustable
current input is applied to the rotor Px2 of that element. The third
element 3 is arranged as before but the output from the rotor thereof
is amplified by any convenient form of amplifier
A (not necessarily a balanced amplifier) rectified by a crystal or
other rectifier K, smoothed, and fed through the series connected
windings of the first element. With this arrangement it may be shown
that the current through the first element and indicated by the meter
M is proportional to
Figure 5 shows an embodiment which will extract the square root of the
sum of the squares of two currents 1112 representative of two
quantities. In this embodiment there are four elements 1, 2, 3 and 4
with their rotors ganged together. The stator and rotor windings S9,
R1, S2, R2, S3, R3 are connected in series in each case and one of the
two currents I1 is passed through the series windings of element 1
while the other current I2 is passed through the series windings of
the element 2.
A.C. input is applied to the stator winding S4 of the element 4 and
the output from the rotor winding R4 thereof is amplified by any
convenient amplifier A, rectified by a rectifier K, smoothed by a
smoothing unit SAl, and then passed through the measuring meter M and
the windings S3, R3 of the third element. It may be shown that with

this arrangement the rearing of the meter M will be proportional to
vIl2+I22.
What we claim is :
1. A calculating instrument comprising at least three watt-meter
elements each having a stator winding and a rotor winding, means
mechanically coupling the rotor windings together, means for applying
one input current to a winding of one watt-meter element to produce a
torque in that element proportional to that current, means for
applying a second input current to at least one winding of a second
watt-meter element to produce a torque in that element proportional to
that current, means for applying an alternating voltage Of
substantially constant amplitude across one winding of the third
watt-meter element, means for producing a direct current output in
dependence upon the alternating current induced in the other winding
of the third watt-meter element, means for applying said direct
current to a winding of one of the first two watt-meter elements and
means for indicating or utilising said direct current
2. A multiplying instrument in accordance with Claim 1 and comprising
three watt-meter elements with one of the two currents to be
multiplied applied to one and the other applied to the other of the
two windings of the first element; means for passing a constant direct
current through one winding of the second element; means for applying
an alternating voltage to one winding of the third element, a phase
sensitive detector; means to apply a voltage of reference phase to
said detector; means for applying a voltage derived from the other
winding of said element to said phase sensitive detector; means for
applying the direct current output from said phase sensitive detector
to the remaining winding of said second element; and utilisation or
indication means responsive to said direct current output.
3. A squaring instrument in accordance with Claim 1 and comprising
three watt-meter elements with the current to be squared applied to
both windings of the first element; means for passing a constant
direct current through one winding of the second element; means for
applying an alternating voltage to one winding or tile third element;
a phase sensitive detector; means to apply a voltage of reference
phase to said detector; means for applying a voltage derived from the
other winoing of said element to said phase sensitive detector; means
for applying the direct current output from said phase sensitive
detector to the remaining windmg of said second element; and
utilisation or indicating means responsive to said direct current
output.
4. A dividing instrument in accordance with
Claim 1 and comprising three watt-meter elements with one of the two
currents to be divided, one by the other, passing through one winding

of the first element; means for passing the other of said two currents
through one winding of the second element; means for passing a
constant direct current through the other winding of said second
element; means for applying an alternating voltage to one winding of
the third element; a phase sensitive detector; means for applying a
voltage of reference phase to said detector; means for applying a
voltage derived from the other winding ol said element to said phase
sensitive detector; means for applying the direct current output from
said phase sensitive detector to the remaining winding of the first
element; and utilisation or indicating means responsive to said direct
current output.
5. A square rooting instrument in accord
* GB785231 (A)
Description: GB785231 (A) ? 1957-10-23
Improvements in or relating to extensible loft ladders
Date of filing Complete Specificationi: May 22 1956.
A pplicatio? Date: Feb 22, 1955 l No 5207/55 Complete Specification
Piiblis,7 hed: Oct 23 19 J 7.
Index at Acceptance:-Class 20 ( 2), L 2 B( 4 A: 9 A).
International Classification:-A 64 b, c.
COMPLETE SPECIFICATION.
Improvements in or relating to Extensible Loft Ladders.
I, ERNEST BENSON, a British Subject, of "Greenleigh," Greensway,
Garforth, Nr.
Leeds, in the County of York, do hereby declare the invention for
which I pray that a patent may be granted to me and the method by
which it is to be performed, to be particularly described in and by
the following statement:-
This invention relates to extensible loft ladders for giving access to
the lofts of houses, and of the kind in which the ladders are arranged
to collapse, telescope or fold up and to be stowed in the loft above

the usual trap door or movable cover.
The chief object of the present invention is to provide a new or
improved construction of such a ladder which will be cheap to
manufacture and simple to fix and operate.
A ladder according to the invention comprises two sections slidably
guided, one within the other, the upper section being slidably guided
both upon the upper surface of a hinged trap door and within the lower
section, both sections being arranged to be projected sufficiently far
into the loft to allow the trap door to be closed solely, or by the
aid of the overbalancing weight of the said upwardly projecting
portions of the ladder The trap door may form part of the ladder and
the ladder sections may be maintained in alignment by flanged brackets
or other guides.
The trap door may be hinged permanently to its frame or may be pivoted
so as to be removable easily if required, and the ladder and trap door
may be made from any suitable materials Stops may be provided where
desired to limit the movement of the ladder sections.
In order that the invention may be more clearly understood and readily
carried into effect, the same will now be more fully described with
reference to and by the aid of the accompanying drawings:Figure 1 is a
perspective view of a ladder 45 constructed in accordance with the
invention shown in its extended and down position.
Figure 2 is a sectional elevation showing the ladder in its raised and
out-of-way position 50 Figure 3 is a diagrammatic side elevation
showing the method of operation of the ladder.
Referring to the drawings, the trap door 1 is hinged at 2 to the frame
3 of the ceiling 4 55 and loft floor 5 Secured to the upper face of
the door 1 are two hardwood slides 6 with blocks 7 which act as stops
for the top of the ladder, and these slides 6 support and guide an
upper ladder section 8 A lower 60 ladder section 9 slides in front of
and upon the upper section 8, having plastic or metal flanged guide
brackets 10 which slide over the sidepieces 11 of the upper section 8
and keep the two sections in alignment even 6 a when the ladders are
extended and bearing a weight.
Due to this construction and the weight of the door 1 and ladders and
the length of the latter being suitably arranged when the 70 lower
section 9 is pushed up over the upper one and both are projected at an
inclination up into the loft to the position shown in dotted lines in
Figure 3, far enough for the door 1 to be shut, their combined over 75
balancing weight is sufficient to cause the door to rise and hold it
closed A suitable catch 12 can be provided to hold the two sections
closed upon one another by engaging in holes 13 in the lower section 9
and to hold 80 them extended by engaging in the hole 14 in the lower
section 9, but otherwise no mechanical device is required, so that

operation is simple and safe Whilst the ladder sections are shown
mounted on a x 5 7855231 785,231 panel 15 with the slides 6 attached
thereto and secured to the door 1 as a unit, preferably, the ladder
sections will be mounted directly on to the door 1.
The improved ladder may be constructed to suit any size of trap door,
but is particularly suitable for small openings where other loft
ladders would not have room to operate.
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* 5.8.23.4; 93p
* GB785232 (A)
Description: GB785232 (A) ? 1957-10-23
Recovery of waste textile fibres
785,232 Date of Application and filing Complete Specification Feb 28,
1955.
No.5936/55.
l:; E E 1 Application made in United States of America on March 1,
1954.
Complete Specification Published Oct 23, 1957.

Index at acceptance:-Classes 2 ( 2), W 3 (A 2 A: B 2); and 15 ( 2),
GA( 2: 5), GB 2 (A 2: BX), WC(MH 1 B: 2 C 9: 2 Cll).
International Classification: -DO 6 m D 21 c.
Recovery of Waste Textile Fibres We, CHICOPEE MANUFACTURING
CORPORATION, a corporation organised under the laws of the State of
Massachusetts, United States of America, of 501 George Street, New
Brunswick, New Jersey, United States of America, do hereby declare the
invention, for which we pray that a patent may be granted to us, and
the method by which it is to be performed, to be particularly
described in and by the following statement:-
This invention relates to the recovery of waste textile fibres which
have been treated with a resin to improve the properties of the
fabric, and particularly to improve its strength where the textile
fabric is of a non-woven type.
More particularly, the invention relates to the recovery of waste
cellulosic textile fibres impregnated with a copolymer of vinyl
chloride and methyl acrylate.
One of the conventional methods of making nonwoven fabrics is to apply
a bonding agent to a layer of card webs The bonding agent is applied
as an emulsion and the fabric is then dried At the end of the
operation, the fabric is trimmed to a constant and predetermined width
and although the percentage of fabric trimmed from the edges is
relatively small, the total weight of the trim, when combined with
production rejects, is appreciable The trim cannot be re-used unless
the bonding agent is removed, and it has previously not been feasible
to remove a bonding agent such as a copolymer of vinyl chloride and
methyl acrylate because removal is accomplished only by heating the
waste material in a caustic solution at an elevated temperature for a
period of at least ten hours Treatment of cellulosic fibres, natural
or regenerated, under these conditions weakens and degrades the fibres
to such an extent that they cannot be re-used in the production of
non-woven or other fabrics.
It is the object of the present invention to provide a process for the
removal of the copolymers of vinyl chloride and methyl acrylate (in
which the proportion of vinyl chloride is at least seventy per cent by
weight) from lPrice 3 s 6 d 1 cellulosic textile fibres, especially
from trim and production rejects resulting from the manufacture of
cellulosic non-woven fabrics by by applying the copolymer in emulsion
form to a layer of card webs.
According to the invention this object is achieved by heating the
fibres in a dilute aqueous caustic alkali solution containing a
dissolved aliphatic ketone or alcohol at a temperature above the
boiling point of the solution and for a period of not more than five

hours.
The presence of the dissolved alcohol or ketone in the treating
solution markedly accelerates the removal of the copolymer from the
cellulosic fibres Any aliphatic ketone or alcohol which is soluble in
the dilute aqueous alkali under the conditions of the treatment may be
used; ketones found particularly suitable include: Methyl ethyl ketone
and Methyl isobutyl ketone.
Alcohols which have been found particularly suitable include: Methyl
alcohol Ethyl alcohol Isopropyl alcohol Iso-octyl alcohol Normal
propyl alcohol Normal hexyl alcohol Tertiary butyl alcohol Isobutyl
alcohol Secondary butyl alcohol Normal butyl alcohol Isoamyl alcohol.
Dihydroxy alcohols such as ethylene glycol and propylene glycol have
also been found suitable.
It is necessary that the water-soluble aliphatic ketone or alcohol be
present in the treating solution in a concentration of at least two
per cent by weight At a concentration of less than two per cent by
weight the rate of removal of the copolymer is lessened substantially
and at a concentration above about two and onehalf to three per cent
there is no appreciable or advantageous increase in the rate of
removal of the copolymer from the cellulosic textile fibres It is
preferred that the concentration of water-soluble aliphatic ketone or
alcohol be about two and one-half per cent by weight of the treating
solution A concentration of alcohol of as high as ten per cent by
weight may be used, since an increase in the concentration of alcohol
above the preferred concentration increases the reaction rate but the
rate increase is not in proportion, economy-wise, to the increase in
cost resulting from the higher concentration of alcohol in the
treating solution.
The treating solution is made strongly alkaline with an alkali metal
hydroxide such as sodium hydroxide or potassium hydroxide in a
concentration of at least one and three quarters per cent by weight of
the treating solution As much as five per cent by weight of the alkali
in the treating solution may be used but at a higher concentration
some fibre degradation takes place If the fibres consist of
regenerated cellulose, such as rayon, a concentration by weight of
alkali above three per cent in the treating solution results in fibre
degradation If the concentration of alkali in the treating solution is
less than about one and three quarters per cent by weight, the rate of
removal of the copolymer is undesirably slow and removal may not be
complete in five hours During the course of the removal of the
copolymer from the fibres some of the caustic alkali reacts with the
copolymer and is converted to sodium chloride.
The rate of the reaction has been found to depend on the concentration
of alkali as well as on the concentration of alcohol or ketone in the

treating solution The concentration in the treating solution of alkali
or alcohol or ketone or of both alkali and alcohol or ketone may be
varied substantially without any great effect on the ability of the
process to remove the copolymer from cellulosic fibres.
The amount of waste material bonded with the copolymer introduced into
the treating solution should be such that the ratio of the treating
solution to the waste material, by weight, is at least seven to one At
the ratio of seven to one the volume of the treating solution is such
that the fibrous material is completely saturated and the solution may
be circulated.
It is prefererd that the treating liquid and the fibrous mass in
association theerwith be packed in a vessel such as a kier and that
the vessel be closed so that the temperature during the treating
operation is elevated above the boiling point of the treating solution
It is also preferred that during the treating period the solution be
circulated in order that the copolymer may be more efficiently and
completely removed from the fibrous mass.
A treating temperature of from about 2400 to 2600 F is preferred At a
treating temperature substantially below 2250 F the rate of removal of
the copolymer from the fibrous mass is undesirably slow, and at a
temperature substantially above 275 F some degradation takes place and
the fibres are re-used only with difficulty in the manufacture of
nonwoven and 70 other textiles Heating of the fibrous mass immersed in
the treating solution according to the above conditions and for a
period of from three to five hours completely removes the copoloymer
of vinyl chloride and methyl acryl 75 ate and the recovered fibres,
after they have been removed from the treating solution, washed
thoroughly with water and dried, may be mixed with fresh fibres and
used in the formation of card webs or used in any 80 other textile
process in which cellulosic fibres are employed.
The manner in which the aliphatic ketone or alcohol contributes to the
removal of the copolymer from the fibres by markedly 85 increasing the
rate of removal is not completely understood but the presence of the
aliphatic ketone or alcohol in the alkali treating solution enables
the copolymer to be completely removed by the caustic alkali during a
90 period of time sufficiently short and at a temtemperature
sufficiently low that the cellulosic fibres undergo no degradation, or
a degradation of such a low degree that no difficulty is encountered
in using the fibres in conven 95 tional textile processs by which
nonwoven or woven fabrics are produced.
At the completion of the process the copoloymer of vinyl chloride and
methyl acrylate is alkali soluble and can be precipit 100 ated from an
alkaline solution by acidification.
It is believed that saponification of the methyl acrylate component

and dehydrochlorination of the vinyl chloride component of the
copolymer occurs during the process 105 The following examples are
given for the purpose of illustrating the invention, the parts
mentioned being parts by weight where not otherwise stated:EXAMPLE 1
110 (Given for comparison purposes) grams of rayon trim waste produced
in the course of the manufacture of a nonwoven fabric comprising a
layer of card webs and containing as a bonding agent twenty per cent
115 of a copoloymer of vinyl chloride and methyl acrylate in which
seventy per cent of the copolymer is vinyl chloride, were introduced
into a vessel containing 700 grams of water and 14 grams of sodium
hydroxide The 120 vessel was closed and rapidly brought to a
temperature of 250 F After heating for a period of six hours at 2500
F, a portion of the rayon trim waste was removed, washed and dried The
waste still contained an amount 125 of the copolymer impregnated on
the fibres such that the fibres were tacky and adhered together
Heating was continued for an additional four hours at a temperature of
250 F, 785,232 785,232 the rayon trim waste was removed, cooled and
washed with water and dried The copolymer was substantially completely
removed from the rayon trim waste but the fibres were degraded to such
an extent that they were weak and brittle and were not suitable for
use in the production of nonwoven or woven textile materials.
EXAMPLE 2
The procedure of Example 1 was repeated except that 14 grams of
ethylene glycol were present in the treating solution After heating
for a period of five hours at a temperature of 250 F, the fibrous mass
was removed from the solution, washed and dried The fibres were
substantially free from the copolymer and were not tacky Degradation
of the fibres was of such a low order that their usefulness in textile
processes for the production of nonwoven or woven fabrics was not
impaired.
EXAMPLE 3
The procedure of Example 1 was repeated except that 14 grams of
isopropyl alcohol were present in the treating solution After heating
for a period of three and one-half hours at a temperature of 250 F,
the fibrous mass was removed from the solution, washed and dried The
fibres were substantially free from the copolymer and were not tacky
Degradation of the fibres was of such a low order that their
usefulness in textile processes for the production of nonwoven or
woven fabrics was not impaired.
EXAMPLE 4
The procedure of Example 1 was repeated except that 14 grams of normal
butyl alcohol were present in the treating solution After heating for
a period of three hours at a temperature of 2500 F, the fibrous mass
was removed from the solution, washed and dried.

The fibres were substantially free from the copolymer and were not
tacky Degradation of the fibres was of such a low order that their
usefulness in textile processes for the production of nonwoven or
woven fabrics was not 45 impaired.
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