CA1045321A - Process for producing acrylic composite fibers having woolly crimp characteristics - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A process for producing acrylic composite fibers having woolly crimp characteristics by compositely wet-spinning two kinds of acrylonitrilic polymers each of which contains not less than 88% by weight acrylonitrile and which are different from each other in acrylonitrile content by not less than 0.5%, initially heat relaxing the obtained swollen gelly fibers containing at least 40% water in hot water or steam in a non-tensioned state without drying them so as to form them into composite fibers in which the irreversible swelling degree of the component higher in acrylonitrile content is higher than that of the other component by not less than 0.05 and said component higher in irreversible swelling degree forms the inside component of the coily crimp, then drying the composite fibers, re-stretching them, mechanically crimping them and then re-heat-relaxing the thus prepared composite fibers in steam.

Description

S3Z~
;~ This invention relates to a process for producing novel acrylic composite fibers having woolly crimp charac-teristics, and more particularly to a process for producin~
acrylic composite fibers having improved crimping per-, formance characterized by restretching, mechanically crimping and re-heat-relaxing acrylic composite fibers in which the component higher in acrylonitrile content is formed as the inside component of the coily crimp by utilizing the difference in irreversible swelling degree ~i between both components.
As a technique for imparting a woolly elasticity and hand (or feel) to synthetic fibers, there is known Japan-,~ ., .
.~ ese Patent Publication No. 19214/1961 dated October :t~i~
. ~
i!;.,~,1961 and No. 1024~1963 dated February 14, 1963. However, ~, the composite fibers obtained by such technique are based ;ii on the principle disclosed in V.S. Patent No. 2,439,815 ,i~ issued to Wayne A Sisson, April 20, 19~8 in which coily :`j crimps are developed by utilizing the thermo-shrinkage -, difference between two kinds of acrylic polymer co~ponents forming composite fibers (which hereinafter will be called ~' briefly ~the Sisson type"), or on the principle wherein ~-~
- ~ t water-reversibility of crimps i5 imparted by providing . ,. ,j .
a difference in the ionizable group content as suggested by Breen in Japanese Patent Publication No. 1024/1963 ; -,~, . j., 'l (whlch hereinafter will be called briefly "the Breen type") ;~ or on the principle wherein the fibers have the features ;

of both the Sisson and the Breen types-. These acrylic `' composite fibers have crimp characteristics and hands :''j :' , ~ closer to those of wool than those of conventional mono-~, ~ , ,,:: .
~` component acrylic synthetic fibers, but have a great draw-;'' back in themselves. More specifically, as the most fatal ., ~j , .
` defects in practice there are enumerated the facts that their dimensional stability in a hot wet state is very .
low and their crimp characteristics and shrin~ing ::;~ - 1 -,~,"~ ~ .
,,, .,' ', i32~
:
force are not as satisfactory as in wool fibers. Even ; a length variation of 2 to 3%, which can be substan-tially ; ~ neglected in the case of mono-component fibers, may be a ; fatal defect in the case of acrylic composite fibees.

Thus, even when a slight length difference is produced . .
i ~ between the two components, as is easily presumed from the above mentioned principle of the generation of crimps, the coily crimps will increase or decrease so re~
"~, .
markably as to have a great influence on the hand and on the dimensinnal stability of the product. In observing ~:.
in detail the reason wh~- such dimensional stability is ,. ~,t. .
.`~ not sufficient, it can be enumerated that, in both Sisson and Breen type acrylic composite fibers, the -acrylonitrile content in the high shrinkage component, :, , ;i that is, in the inside forming componen-t of the coily :; crimp, is lower than the acrylonitrile content in the ~ low shrinkage component, that is, in the outside forming :: ~
` component of the coily crimp.

We have discovered a process for producing novel ~ acrylic composite fibers remarkably improved in dimen- -; sional stability and in crimp elasticity by overcoming :~ the above described disadvantages of the conventional . ^,; . ~
~' techniques. Also, as a result of repeated experiments to elucidate the crimp developing behavior of acrylic composite fibers, we have reached the present invention by discovering a process for producing novel acrylic -~ composite fibers remarkably improved in crimp reproduct-' ivity and in crimp developing force upon heating by ~` utili~ing a difference in the irreversib~e swelling degree between the fiber forming components.
, . .
Thus we have found -that acrylic composite fibers which are high in dimensional stability andinlP.which the component higher in acrylonitrile content forms the in- -- side component of the coily crimp ~
-- .
~ 2 -;::

53Z~
:,`
can be reproduced by selecting two kinds of acrylonitrilic polymers different from each other in the irreversible swelling degree as components forming acrylic composite fibers and taking the steps of primarily heat-relaxing ~o swollen gelly fibers, re-stretching and mechanically crimping the fibers and re-heat-relaxing them under , specific temperature conditions.
'`~ A principal object of` the present invention is to ~ . ., provide a process for producing acrylic composite fibers ,~ in which the higher shrinkage componen-t forming the inside component of the coily crimp has an initial Young's modulus (at a -temperature above the glass transition temperature) higher than that of, or as high as that of, q", the lower shrinkage component forming the outside compon-,' ent of the coily crimp.
i Another object of the present invention is to provide `;:
. ~ , :, a process for producing acrylic composite fibers stable in dimensional stability and coily crimps at the -time of dyeing or washing them.
A further object of the present invention is to '!. :
provide a method for imparting wooly crimp characteristics-to composite fibers obtained by compositely wet-spinning ~,! two kinds of acrylonitrilic polymers different from ~' each other in the irreversible swelling degree by re-.1, stretching mechanically crimping and re-heat-relaxing them.
~,~ These objects of the present invention are effect-ively accomplished by compositely wet-spinning two kinds of acrylonitrilic polymers each of which contains not less than 88% by weight acrylonitrile and which are different ' from each other in acrylonitrile con-tent by not less than ', 0.5%, initially heat-relaxing the obtained swollen gelly fibers containing at least 40% water in hot water -,~`.~, , .:
,~ - 3 - ,;
:, , , / : , ~ ~.

i: ~
; or steam at 60 to 130C. in a non-tensioned state without . ,:--~ drying them so as to form them into composite fibers in . .
~ whilch the irreversible swelling degree of the component Ar hlgher ln acrylonltrlle content lS hlgher than that of the other component by not less than 0.05, and said component .5~', higher in irreversible swelling degree forms the inside ; ;. ,:
component of the coily crimp, then drying the composite fibers at a temperature of 50 to 150 C., restretching them -~ at a stretching ratio of 1.0 to 1.4 times, mechanically crimping them and then re-heat-relaxing the thus prepared -composite fibers in steam at 100 to 140 C.
The present invention is based on a discovery th~, i~ when swollen gelly fibers obtained by water-washing and ?~ -wet-heat-stretching wet-spun acrylic composite fibers are directly primarily we-t-heat-relaxed in a non-tensioned .
i~ state without being dried, the shrinkage will be different . 1 i;~ depending on the difference in swelling degree, the volume ~-:','~,'.' ' ~;'! shrinkage when they are subsequently dried will be , ....................................................................... . .
~-~ different depending on the swe]ling difference of the original swollen gelly fibers and the swellability and the volumetric shrinkability of the component higher in acry-~J!, lonitrile content will be higher than those of the compon-ent lower in acrylonitrile content. The swellability of ., ~
~;~ swollen gelly fibers is so irreversible as to return no longer to the original state even if the fibers are wet once they have been dried. We call this phenomenon "irreversible swellability" and we use as a scalethereof the irreversible swelling degree represented by the fol-~ . , lowing formula: -: WG
Irreversible swelling degree = W

wherein WG ~s the weight o-f a swollen gel fiber which has ~' been hot-stretched, and WD represents the weight of the ri, same gel fiber after being dried.
.'.';~ .
- 4 _ '`:...................................................................... ..
.:,

2~
`i;, The initial Young's modulus above the g].ass transition temperature of acrylic synthetic fibers becomes higher with an increase of the acryl~nitrile content in the polymer. Therefore, .:.
when acrylic pol~mers different from each okher in acrylonitrile content are selected as two components for forming composite fibers and the component higher in acrylonitrile content is made higher than the compDnent lower in acrylonitrile content in the irrever-sible swelling degree by at least o.05 and thereby is made an ~; inside component of the coily crimp as a higher shrinkage component, ~;
.. , .~ .
as a result, acrylic composite fibers in which the initial Young's -~ modulus above the glass transition temperature is higher in the `` inside component than in the outside component of the coily crimps will be able to be obtained. In order to make the initial Young's ;~
; modulus at a temperature above the glass transition temperature of the higher shrinkage component (that is, the inside component -of the coily crimp) higher than or as high as the initial ~oung's ~ modulus of the lower shrinkage component (that is, the outside ; component of the coily crimp), it is necessary to make the acrylo-~ nitrile content in the polymer used as the higher shrinkage com-,:
ponent higher by at least 0.5 ~ by weight than the acrylonitrile content in the polymer used as the lower shrinkage component. Thus, the higher the acrylonitrile content in the higher shrinkage component over the acrylonitrile content in the lower shrinkage component, the higher the initial Young's modulus of the inside ~ component of the coily crimp in a temperature range above the ..
glass transition point over that of the outside component. How-~; ever, when the dif~erence between the acrylonitrile contents in ~ ...................................................................... . .
both components exceeds 10 ~0 by weight, the irreversible swelling ;j degree difference will be more than 3, the development of coily . , ` ~
~ 5 ~

,'. 1`~ .:.

0~53Z~L ~
. .
~-- crimps will increase in excess, the crimp form will become ,.': ;. , too fine and the spinnability or hand of the resulting fibers will be impaired. Therefore, it is preferabl~ to ;
, ~ maintain the difference between the acrylonitrile contents . ~ j .
~ ~ in the two components to be not more than 10%.
Y,~
n the acrylic polymer in which the acrylonitrile content is not less than 88% by weight, the irreversible swelling degree will become higher with an increase of the acrylonitrile content in the polymer. However, in order to make the irreversible swelling degree difference not ~ less than 0.05 with only the difference between the acry-;, lonitrile contents in the two components, it is necessary . j~ . .
~' to make the difference between the acryloni-trile contents ;',. ~ .
'";`, in the two components not less that 2%.
The present inven-tion will be explained in more de-tail as follows.

. ~ .! ' As acrylonitrile polymers to be used as composite fiber forming components in the present invention, there p'`~ can be enumerated an acrylonitrile homopolymer and an ~' , acrylonitrilic copolymer which contain at least 88% by ~,~,- weight acrylonitrile and in which at least one monomer ,' copolymerizable with and other than acrylonitrile is copolymerized as the other polymer forming componant.
~, So long as the acrylonitrile contents in both components .,. '-,4~ ` are different from each other by not less than 0.5%, ~
r these polymers and copolymers may be obtained by any polymerization process.
The acrylic composite fibers of the present inven-tion are obtained only by a wet-spinning process. As solvents which can be used to prepare the spinning solu-~;~ tion, there can be enumerated well known solvents used .......
' -j in wet-spinning, such as a concentrated 'I
,';.~' :
. ...

~`~
'~
;
53;~:~
~,`,` aqueous solution of an inorganic salt such as the thio-.
`~ cyanate of an alkali metal, e.g. lithium thiocyanate, ,.;, ~ .
potassium thiocyanate or sodium thiocyana-te or ammonium ~; thiocyanate, zinc chloride or perchlorate, a concentrated ;
., . . ~ .
~ aqueous solution of an inorganic acid such as sulfuric ~
; , acid or nitric acid and an organic solvent such as dime ; -thyl formamide, dimethyl acetamide or dimethyl sulfoxide.
, ~ :
~ In preparing the spinning solution, acrylic polymers ~ f :~ different from each other in acrylonitrile contact as ~ mentioned above are selected as two components of compo-. . :
' site fibers, and the acrylic polymers and the polymer .: ,:
concentration in the spinning solutions are adjusted so that the irreversible swelling degree of the component higher in acrylonitrile content is lower than that of the component lower in acrylonitrile content. `
In spinning the composite fibers, for example the apparatus shown in Japenese Patent Publication No. 24301/
1964, dated October 30, 1964 or any other known wet-spinning apparatus for forming composite fibers can be used.
For the coagulating bath, there can be used water or a dilute aqueous solution of the solvent used to prepare the spinning solution.
The swollen gelly composite fibers leaving the~coagu~
lating bath are water-washed and then stretched and are .. : , . .
~ primarily relaxed by heating with hot water or steam '~ ":, : ` ' ; in a non-tensioned state so that the elongation and the ,r~
`~ knot-strength are improved and a part of coily crimps is developed by the shrinkage difference based on the irrever-~` sible swelling degrffx~difference. It is necessary that the swollen gelly composite fibers -to be primarily heat-relaxed ~ should not be dried at all before said heat-relaxing treat ,~ ment.
~ - 7 -., - .: .
~'''.'' ,... .

: ~ :
53;~
~, and should containat least 40% water on the dry weight of ,~ ~
~ the fibers (which hereinaf'ter will be called the "water .~,. . .
content"). When the water content in the swollen gelly ~` composite fibers is less than 40%, the plasticization with !~ ' water will decrease, the apparent glass transition temp-erature will rise, and it will be difficult to well deve-lop the effect in the primary heat-relaxing treatment, ` and coily crimps will not well develop even in the sub-~ sequent compacting drying treatment, and further the ,, compacting will not take place so completely and there will be a tendency toward the devitrification of the ~`~, final fibers.
~!';'''' The primary heat-relaxing treatment is carried out ..
~ in hot water or steam. As the temperature condition J a t~
; range of 60 to 130 C. is preferable. If the primary heat-relaxing temperature is less than 60C., it will be ' impossible to give a sufficient relaxing effect to the fibers to develop coily crimps and therefore acrylic :; .
; composite fibers favorable in the knot-strength, elong-ation and coily crimps will not be able to be obtained.
- Furthermore, if the primary heat-relaxing temperat~re ,~: exceeds 130 C., the swollen gelly composite fibers will be colored. Also, the dyeing velocity of the fibers de-, pends on the primary heat-relaxing tempera-ture so much . '. ! ~
~, that, if' the heat-relaxing temperature is made too high, ,1~; `1 .
the dyeing velocity will increase to be so high as to impair the level dyability.

The swollen geIly fibers having had coily crimps ~:!
partly developed by the primary heat-relaxing treatment are then dried in an ordinary manner in a non-tensioned ,~ state. It is desirable to carry out the drying treatment .'~;.' ,`,, under the controlled humidity conditions of a dry-bulb ,~ temperature of 90 to 135C. and a -j~ b'~ 104532~
~ wet bulb temperature of 65 to 90C. By such drying treat-,~ ment, due to the shrinkage difference based on the irrever-~ ~ .
,~ sible swelling degree difference between the two compon-,~ ....................................................................... . .
`` ents, the coily crimps of -the acrylic composite fibers will be completely developed and at the same time the fiber ~: :
`~ structure will be compacted.
3j ~` .
:~ The acrylic composite fibers having had the coily ( ;~
crimps developed due to the irreversible swelling degree difference between the composite fiber forming components by the primary wet-heat-relaxing treatment with hot water ~.';'. :
or steam and the fiber structure compacting drying treatment are then re-stretched at a stretching ratio ... .
~ ~ of 1.0 to 1.4 times at a temperature of 50 to 150C. so .: .
that coily crimps may be latent, are further mechanically crimped and then are re-heat-relaxed in steam at 100 to 1~0C~
By -the combination of such re-stretching, mechanical ` crimping and re-heat-relaxing steps, there is attained i. " ~ .:
, an advantage that, even though the acrylic composite . ~ -, -, fibers are wet at a high temperature under a high humidity ` ~ under the action of tension in a subsequent dyeing step i:~ i :
~ or the like, they can maintain the level of a favorable " ~. , .
; ~ crimp reproductivity and crimp developing force. There-~ fore, the hand and the elastic crimps of the final product ,` ,;.,., '~
; are remarkably improved and a soft product which is ;~ excellent in dimensional stability can be obtained.
:*: ,~i .,-, . .
i; The re-stretching ratio in the present invention is represented by a quotient obtained by dividing the length of stretched composite fibers by the standard length of .~,j, , .
fibers in the case where coily crimps rendered percept-' ible by the primary heat-relaxing and drying are substàn-~l tially straightened by stretching. In the case where the ^;

;~ re-stretching ratio exceeds 1.4 -times, , .
,....................................................................... ..
. . ,-; ' ',:'. - 9 ~ '~''' . ~, .
!,: ` . .

the shrinkage of the component lower in acrylonitrile content will exceed the shrinkage of the component higher in acrylonitrile content and, therefore, in the re-heat-relaxing treatment, the inside and the outside layers of the coily crimp will be inverted relative to each other and the crimp developing force and the crimp elasticity of the final fibers will be remarkably reduced. Further, in the case where the re-stre-tching ratio is less than :.:
1.0, a part of the coily crimps rendered perceptible in ~ the primary heat-relaxing step and in the drying step - will not be made latent and theref~re the hand of the ~ final product will diminish remarkably. On the other .,i. . . .
,! ~
hand, if the re-stretching is applied by setting the re-stretching temperature in a temperature range lower than 50 C., the fibers will break so often as to ,~ ,:j . . f ' greatly reduce the fiber property. Furthermore, when -~

;;' the re-stretching temperature exceeds 150 C., the fibers :"~:
~,` will be colored.
As regards the re-stretching temperature conditions, ; i such critical temperature range as is described above is recognized but there is no particular restric-tion in the kind of heating medium and therefore not only a usual ' wet heat medium such as hot water, steam or a mixture of ,,: .,~ :
steam and air but also a dry heat medium such as a hot .l plate or dry hot air current can be used.

., The acrylic composite fibers having had the coily crimps rendered latent by the re-stretching are then `
~``' mechanically crimped with a known crimping apparatus such as a stuffer box. The mechanical crimps are influenced so much by the total deniers of the fed acrylic composite :. ~
fibers and by the charging pressure into the compressing chamber that it is difficult to positively define the ,, ~,.
~ 4~ lo ,':' , crimping state. However, in consideration of the heat history in the re-heat-relaxing step, it is preferable ~ to maintain the .. , ' : ' :

., ~. ;' .
- s, , ~: , ' . ~ ' :

,:';;` ~ -;,, '~
: , ..
. ........................................................................ .
i~: :, :
, . . .

'; .~ .':

:,.,: l ., .: .
,...
.'~','. ~,.
Y~
",; ' . .:

.,, :

., , . ~j ;, . . .
,; ' '- . .
;........................................................................ , .
,:.!, ~, ;',1 '' . "
:. - lOa ,........................................................................ : .
, ;

' '' ' ; ~' ' ' ' ; ' ' " ;

9L532~
~!~", number of crimps in a range of 7 to 13 per 25 mm. The , ........................................................................ .
mechanically crimped acrylic composite fibers can be formed into acrylic composite fibers having had the coily crimps rendered perceptible by being then re-heat-re-: . .laxed.
In working the process of the present i~vention where the fibers are not mechanically crimped before they are re-heat-relaxed, even if the fibers are subse-quently re-heat-relaxed in the form of fibers, spun -yarns or knit or woven fabrics, coily crimps will not develop well and it will be difficult to improve the dimensional stability and the initial Young's modulus ,., ~ ,~
~. of the final product. 1~
., .
On -the other hand, where the re-heat-relaxing temp~ ;
erature does not reach lOO C., subsequent after-treatment such as a dyeing treatment or a crimp developing treat-.,:'. .' -:
i~ ment will be carried out usually in a heating medium at about lOO C. and therefore the heat-relaxing effect will be substantially lost in said after-treating step. Thus it is not desirable.
~ Furthermore, where the re-heat-relaxing temperature ,~ is higher than l~O C., the finally ob-tained fibers will ;~ be colored. Therefore, it is not desirable.
Thus, in the present invention, by the combination of the particular treating conditions as defined herein-before, the crimp characteristic of acrylic composite ., . ! fibers are made very similar to those of wool fibers and ~"1 ::
not only the dimensional stability and the initial Young's - modulus but also the level dyeability of the final pro-duct can be improved.
Incidentally, in the present invention, the molecular weight of the polymer, fundamental crimp frequency, crimp ., .
product, elastic recovery of cromps, crimp reproductivity by heat and -- 11~ _ :....
'' :

~.~4532~ ~:
crimp developing force are measured respec-tively by the --below mentioned methods:
(1) Molecular weight of the polymer:
The intrinsic viscosity (~) of the polymer is determined in a dimethyl formamide solution at 30 C. and this ( n ) affects the molecular weight of the polymer.
(2) Crimp product Ci:
The length a of the crimped fiber subjected to an initial load (2 mg. per unit denier of the crimped fiber r ~ ;
; to be measured) is measured~ and then the length _ when a load of 100 mg. per unit denier is applied is measured, ahd-th~ecrimp product is determined by -the following - formula:
: ~ :
Crimp product Ci = b b- a X 100 ; (3) Fundamental crimp frequency Cf: ;

A load of 2 mg. per unit denier is applied to the ;~ sample to be measured, the number of crimps per length of ~, 25 mm. of each of 20 samples is counted, and -the average ~, value is made the number of crimps Cn of the fibers.

; The fundamental crimp frequency Cf is determined by the following formula from -the number of crimps Cn and ~, the crimp product Ci is determined by the method mentioned in paragraph (2) above:
: ." ;:.
Cf - Cn (1 - Ci) ,.,': ' :'~
(4) elatic recovery of crimps:

First of all, the crimp product Ci is determined by the above mentioned crimp product measuring method, then ,~ the length b' of the sample when left for 60 minutes while ~ a load o-f 100 mg. per unit denier is applied is measured, ;~ then the load :. . :
~, - 12 - ~
~ ,:; -`', ' `

. . .

: ~a4s3zl is removed and the length a' of the sample is measured while a load of 2 mgO per unit denier is appliedO Then, after the load of 2 mg. per unit denier has benn applied for 60 minutes, the length a" of the sample is measured Further, the length b" of the sample when a load of lO0 mg: per unit denier is applied is measured. The elastic recovery of the crimps is calculated by the following ,........................................................................ :
formulae from the obtained measured values:

Ci' = b' - a' X lO0 b~
:. .
Ci" = b'' - a" X lO0 ; ~ b"

~~ Elastic recovery of instan- _ C ' X lO0 ~, taneously recovered crimps Ci Elastic recovery of delayed recovered crimps = Ci" X lO0 ci ... .. .
, (5) Crimp reproductivity by heat:

~:~ The sample to be measured is treated with hot water , . . .
~l at 98 C. for 15 minutes and is dried at 80C. for 30 .~.. " ~, ~l minutes to develop latent crimps of the sample composite '~.:' I
fiber, then the length a of the sample is measured while ~i~ an initial load of 2 mg. per unit denier is applied and ::!
further the length b is measured while a load of lO0 mg.
per uni-t denier is applied to said sample. Th~ said ~;; sample is wou~d on a metallic bobbin of a diameter of 90 .. i .
mm. under tension by applying a tension of 100 mg. per unit denier, is fixed at both ends on the bobbin wi-th ad-.: ~
.~ hesive tapes and is dipped in boiling water to be wet- ~-. ; l ! eated for 60 minutes. The the sample is unwound from the ~,,:,j metallic bobbin, is treated as non-tensioned with hot water at 98 C. for 15 minutes and is dried at 80 C. for 30 minutes to redevelop crimps, then a load of Z mg. per ,~ .. . ~
.~ unit.

",, . :, , .,. ~.
.
:,l 4~3~
~, ., denier is again applied to it and the length c of the sample is measured. The crimp reproductivity (~) by heat after the boiling . . '.
; water treatment under tension is calculated by the following . . :
formula fr~m the thus obtained measured values:

by hePat P Y = b -_c X 100 (~

.~ "
~ (6~ Crimp developing force:

- The sample to be measured (o~ total deniers of about -~
: ' 'I , .
. . . .
100 deniers) is treated with hot water at 98C. for 15 minutes and . .. . . .
is dried at 80C. for 30 minutes to develop latent crimps of the sample composite fiber, then the crimps are stretched by applying ~ -~ a load of 400 mg. per unit denier to said sample and the sample is .~ fixed ~or a fixed length at both ends in this state and is thermoset ; l for 10 seconds under the action of dry heat at 120C. Then the ~ sample is set on an electron tube automatically balancing type ., strain measuring apparatus (manufactured by Toyo Measuring Appa- ~

ratus C~.) and i5 dipped in hot water at 95C. while a load o~ ;
; , ': .

3 mg. per denier is applied. At the same time, the strain generated ; in the sample is recorded by operating the above mentioned strain ,......................................................................... . . .
~; 20 measuring apparatus. In 5 minutes, the thermal stress of the sample is calculated. This value is made the crimp developing force ~-(in mg./d.) of the sample.
(7) Initial Young's modulus ~5 in hot water at 95C.~
~` A thermostatic tank containing hot water at 95C.
is ~itted to a constant velocity tension tester (Tensilon type III
( a trade mark) manu~actured by Toyo Measuring Apparatus Co.), a tensile load is applied at a tension velocity at 30 mm./min. while a sample 30 mm. long is dipped in the thermostatic tank, the ; load detected with a resistance wire strain meter Load Cell ,. . ~
'',`,~ ' ':
~ 14 - ~`
.,: ' , ,..

3~
(manufactured by Toyo Measuring Apparatus Co.) is selE-recorded to describe a load-tension curve and the initial Young's modulus E95 in hot water at 95C. pe~ denier is determined from the initial gradient of said load~tension curve.
; The invention will be illustrated in the following Examples. However, the scope of the present invention is not : ., limited by them. In the Examples, the parts and the percentages ; are by weight unless otherwise specified.
., .,.. :~ .
Example ~' 10 An acrylonitrilic polymer having a viscosity ( ~ ) of ';; 1.5 was prepared by copolymerizing a slight amount of sodium . ~, methallylsulfonate with 97 parts of acrylonitrile and 3 parts of methyl acryla e as an inside component (which hereinafter will be briefly called "the component A") of the coily crlmp. On the other hand, an acrylonitrilic polymer having a viscosity ( ~ ~ of 105 was prepared by copolymerizing a slight amount of sodium methallyl- ;~
sulfonate with 91 parts of acrylonitrile and 9 parts of methyl acrylate as an outside component (which hereinafter will be briefly called "the component B") of the coily crimp.
.;
The thus ~btained two kinds of acrylonitrilic polymers were dissolved respectively in concentrated aqueous solutions of sodium thiocyanate, the copolymer concentration in the spinning solution was adjusted to be 11 % in the component A and 13 % in ; 1 the component B. Then equal amounts of both components A and B
`;1 were wet-spun into an aqueous solution of sodium thiocyanate at a ~ low temperature by using a composite spinning apparatus mentioned , :, in Japanese Patent Publication ~o. 24301/19~ and the obtained fibers were water-washed and were then thermo-stretched 10 times their length in hot water. Then they were primarily heat-relaxed . "~ , .

i l~
53;~
.
for 5 minutes in boiling water in a non-tensioned state.

The obtained fiber filaments were dried to be compac-ted `~ in a non-tensioned state~in an atmosphere in which the -~ humidity was adjusted to a dry-bulb temperature of 110 C.
,':
. and a wet-bulb temperature of 70 C. to make 8 kinds of - of sample fibers of a mono-filament fineness of 3 deniers .: ..
.~-; indicated as Sample Nos. 1 to 8 in Table 1. Incidentally, the fiber indicated by Sample No.-l is the control fiber.
-~ Then the sample fibers indicated by Samples Nos. 2 to 8 were re-stretched under -the condition mentioned in Table ;~
; 1 but the sample fiber indicated by Sample NoO 8 could not be re-stretched in the experiment because the re-~' stretching temperature was below the preferable -tempera ture range of the present invention. The sample fibers . , , having had the coily crimps made latent by re-stretching were then put into a push-in -type crimping apparatus -to ;i~ be mechanically crimped in an ordinary manner.
i The thus obtained sample fibers were then spun in an ordinary manner, were then set on a filing knitter of ~;
18 gauges to be formed into a knit fabric and were re~
heat-relaxed in a wet heat medium of the temperature -, conditions mentioned in Table 1. The physical properties :~
', of the acrylic composite fibers in the thus obtained ,` final products are also indicat~d in Table 1.
It will be noted from Table 1 -thatthe acrylic com-posite fibers produced by the process of the present ~ -' ! .
S` invention and indicated by Sample Nos. 2,3,4 and 5 are -~

~ remarkably improved as to crimp reproductivity by heat ` ! :
and in crimp elastic modulus after the boiling water treat-;~ ment under tension and retain the number of crimps, and the crimps produced are suitable to result in a hand , `l very similar to that of wool fibers. On the other hand ~i it is evident that the number of orimps and crimp ,~ .

~ - 16 -: ;~

`~
~"~ " . ' ~; produc-t of the control fiber are so large that the hand ~:'~ :,. . .
~'... - of the final product is essentially different from that : : of the wool fiber product.
Furthermore, as the re-stretching conditions or re-X heat-relaxing conditlons of the smaple fibers indlcated by Samples Nos. 6 and 7 deviate from the preferably range ,,:.~: . .
~ proposed lnthe present invention, their hands and crimp ,.~.. ~ ,.
characteristics are remarkably lower than those of the acrylic composite fibers made by the process of the pre-. sent invention or wool fibers and naturally the commodity values of the final products are also greatly impaired.
: i , . ~.
i ;
1'.~ ~ , -::... :, :
'. ''~' . .~
. .; ,...

, .........
;; ~
.~ ", , .

!,.~'.,, `

. ', . 1'~

,.''.' '`i i~,'!

. ., .~
.,... ;, ~
....
". ~,. . .
17 `
',' ' ~ ' :` . .
- ;.ii: .
,;~; :
. ~ . ,~, : `

32~
,: .
;,, ,,,.,, ~ ~ ~ ~ ~ ~ o ~, ~ ~ U~
O ~ U~
. ~o ~ ~ ~ . .
u a si Q
U ~ It~ ~ ., ~
. ~ h ~-1 ~ ~ ~ O
. '- Ii~ O O U (!~ C`J C'J N C\J C'~l ~1 ~) .:;
H ~ ...
,, :-`.-" .,, , . . :
~,.; ..
1 u ~ ~1 o o o , ~ o oQ o ~ ~ tr) ~ r ' "' U ~ ~1 . "'` ' -' ~, .. ~ rl ~, U ~ ~ CU U~ J ~ ~) ~) cO
u ~ R ~ 1~ 1~
- O ' ~
U~ ~1 0 0 c~
i ~'rl O U ~rl Cl) t`D O O ~ ~ ~) N
:',,~, ~ .
~'`.; .,' '::
... ~ O

.j~, ~~ 4~ ~ 0 C7~ o~ O~i ~ U CU
'"' '' E4 ~ 4-1 !~.,j :

rl S-l O O O O O L~ O :' U N C~l CU CNC~

r~ 3 L~ ) oo o co C~l Q ~
~ ~ ù
,.,;1 ~ ~ - o ~ , i I ~ 3 ~ H
-;
t ;;! h ~
I I a) ~' U (IJ ~5 ~
`"'~,' ~ U ~ ~ ~ oU ~0 0 oO~ O O COo ::;1 1 ^:
a ns_ ;.
tn-rl ~
o ~- 0 ~1 0 H CU t f3 JU~ ~D ~ co O

:.,, ;-;` - 18 -, . ,. ,~
~ii, :.

~453z~
;, On the other hand, acrylic synthetic fibers consis~ing ~' of a mono-component were made under the same step condi- -, - tions as in Example 1 except that the above mentioned com-ponents . ......... . .
~,:,. . A and B were respectively singly spun, and the ::
':........ irreversible swelling degrees and the initial Young's ''~ moduli in hot water at 95C. of the acryloni-trile polymers .~ :.
. in this example and the irreversible swelling degrees and the initial Young's moduli in hot water at 95 C. of said' fi:bers were~measured. .As,a.result, the~ irrev.ersi~e :.......... .
- ~s.wel-l'ing~degree;s of both comp.onents A and B were recorded : t~,be 2.61,and 1.5,5,respecti-vely-, and th,e initial Young'~s ~: moduli~ in.hQt:~water-:a.t 95 C.:of the-respecti-ve components . ' :
; ~.were.as,.shown,-in,~Table 2 b,elo:w.
:, ,.:. .. .
, .~ ., . ~, ~.,. TA _E 2 ,. ) ., , ,",'. Component E95 Sam~le forming the W
.':-' inside of the .':,. coily crimp Component A Component B
1.76 0.73 ~ 2 A 1.73 0.73 i",:,~ 3 A 1.79 0.71 ,.; 4 A 1.74 0,~.
,.: 5 A 1.79 0.71 :''' 6 A 1.25 0.61 '.~ 7 B 1.69 0.71 , i,,, . ..
,'' It will be noted from Table 2 that, in the acrylic ', : ,'?
i:;' composite fibers indicated by Sample Nos. 2,3,4 and 5 -' .. :~ and made by the process of the present invention, the :, component A higher in the intial Young~s modulus Ew5 in ~^, .ho-t water at 95C. forms the inside compnnent of the coily .,, crimp.
,'`l On the other hand, in the acrylic composite fiber ~ ,.
": ;
,~ Which -19-~ . ?t ~''~ ."'.',:

:~`
: i ~J

~:
is indicated by Sample No. 7 and whose re-stretching temperature and re-stretching magnification deviate from the preferable manner of working of the present invention, by the re-heat-rela~ing , treatment, the inside and the outside layers of the coily crimp are inverted relative to each other, the component B lower in the initial Young's modulus ~5 in hot water at 95C. forms the inside component of the coily crimp and therefore the crimp developing force and the elastic recovery of cr.imp of the final , ,,~ , .~
~ product both are lower.
;~.
. .
; ....................................................................... .
, . .
.'"'" ,~
.... ..

: .

!::
.,' ~, .~;,,, ' ' ' ~' .. . .

~ . , .
. ;!~: !
.i`l :
.. .. ..
. ,"~
',' ' .

~'~;, l :'' : ~ :
, ., ..
~1 . ~", ,; `.1 '~

,: ~ . .
;j - 20 -. ~ .
.~ : :. ;
.

Claims (3)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for producing acrylic composite fibers having woolly crimp characteristics by compositely wet-spinning two kinds of acrylonitrilic polymers each of which contains not less than 88% be weight acrylonitrile and which are different from each other in acrylonitrile content by not less than, 2% and not more than 10%, initially heat-relaxing at a temperature of 60-130 C. the obtained swollen gelly fibers containing at least 40%
water in hot water or steam in a non-tensioned state without drying them so as to form them into composite fibers in which the irreversible swelling degree of the component higher in acrylonitrile content is higher than that of the other component by not less than 0.05 and said component higher in irreversible swelling degree forms the inside component of the coily crimp, then drying the composite fibers at a temperature of 50 - 150°C ., restretching them at a stretching ratio of 1.0 to 1.4 times, mechanically crimping them and the re-heat-relaxing the thus prepared composite fibers in steam at 100 - 140°C.

2. A process as claimed in Claim 1 where in the mech-anical crimping is conducted to such a degree that the number of crimps becomes 7 to 13 per 25.mm. of the fiber

3. A process as claimed in Claim 1 wherein the drying is conducted at a controlled atmosphere wherein the dry-bulb temperature is 90-135 C. and wet-bulb temperature is 65 - 90°C.