CA1159320A - Method for producing soft sheet - Google Patents
Method for producing soft sheetInfo
- Publication number
- CA1159320A CA1159320A CA000373849A CA373849A CA1159320A CA 1159320 A CA1159320 A CA 1159320A CA 000373849 A CA000373849 A CA 000373849A CA 373849 A CA373849 A CA 373849A CA 1159320 A CA1159320 A CA 1159320A
- Authority
- CA
- Canada
- Prior art keywords
- fibers
- filaments
- thinnable
- viscoelastic substance
- sheet material
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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- Synthetic Leather, Interior Materials Or Flexible Sheet Materials (AREA)
Abstract
Abstract of the Disclosure In a method for producing a soft sheet material containing thinned fibers or filaments and a viscoelastic substance, the improvement comprising:
(A) applying a mixture of a viscoelastic substance and a temporary filler to a sheet Material containing thinnable fibers or filaments;
(B) thinning the thinnable fibers or filaments forming said sheet material;
(B') applying temporary filler to said sheet material or relocating said temporary filler applied previously at step (A) within said sheet material, whenever necessary;
(C) applying a viscoelastic substance;
(D) removing said temporary filler; and (E) napping the sheet, whenever necessary, to thereby obtain a leather-like sheet Material which, though soft, has good mechanical properties such as high abrasion resistance and high tear strength. A leather-like sheet material is produced which is free from deficiencies such as low abrasion re-sistance and tear strength even where the thickness is further reduced.
(A) applying a mixture of a viscoelastic substance and a temporary filler to a sheet Material containing thinnable fibers or filaments;
(B) thinning the thinnable fibers or filaments forming said sheet material;
(B') applying temporary filler to said sheet material or relocating said temporary filler applied previously at step (A) within said sheet material, whenever necessary;
(C) applying a viscoelastic substance;
(D) removing said temporary filler; and (E) napping the sheet, whenever necessary, to thereby obtain a leather-like sheet Material which, though soft, has good mechanical properties such as high abrasion resistance and high tear strength. A leather-like sheet material is produced which is free from deficiencies such as low abrasion re-sistance and tear strength even where the thickness is further reduced.
Description
3~
This invention relates to a composite fibrous sheet, especially ~o a napped compos~te fibrous sheet wh~ch has good mechanical properties while also having the desired so-ftness.
The use of "artificial leather" produced by applying a viscoelastic substance to a fibrous sheet has been ever-increasing in recent years.
Uses include not only shoes, bags, upholstery and the like but also clothing. Typical requirements for artificial leather are that it must be soft and, at the same time, must have good mechanical properties such as high abrasion resistance and high tear strength. ~t must also have the desired surface appearance.
Various attempts have been made to satisfy these requirements, as exemplified by the following methods. British Patent No. 1,300,268 discloses a typical method which comprises applying a rubber-like viscoelastic substance to a fibrous sheet consisting of specific flbers, such as "islands-in-a-sea"
type fibers or filaments, and then removing part of the specific fibers such as the sea component in order to obtain a sheet material having a soft and pli-dble hand.
The method typified by United States Patent 3,706,613 comprises applying first a soluble binder such as polyvinyl alcohol to a sheet consisting o specific ~lbers such as "islands-in-a-sea" type composite fibers or ~ilaments, ~hen removing part of the specific fibers such as, for example, the sea com-ponent to generate superfine fibers, applying a viscoelastic substance such as polyurethane or the like and thereafter removing the soluble binder. Various lubriGants or soEteners may be added to the binder or to thc product to soeten the product.
Those methods have mcrit, but they alsc have the followin~ critical probl~ms. rrhe sheet obtainecl by eirst applyLng a rubber~ e viscoelastic : : :
:, ..: 1 ~ . -:, - ~ :
..-.
~ ~ 5t3~Z~
substance and then remo~lng one component of the speci~ic fibers, as typified by the abovementioned Rritish Patent No. 1,300,268, produces a sheet having a soft hand. ~lowever, the sheet has low tensile strength due to gaps generated between the superfine fibers and the rwbber-like viscoelastic substance. When the sheet is raised to produce a napped surface effect, the nap easily peels off, which is a serious drawback. Further, since the solvent for the vlsco-elastic substance is, in most cases, also a solvent for khe fiber-forming components, applicatlon of the viscoelastic substance becomes extremely un-stable and continuous production of uniform product is difficult.
~n the method exemplif:led by United States Patent No. 3,706,613, there is a high probability of the superfine fibers and the rubber-like viscoelastic substance being bonded directly to one another. This produces a product with a secure nap) but the bonded parts between the superfine fibers and the rubber-like viscoelastic substance are relatively large yielding a product with a rubber-like hand which is undesirable in clothing.
Attempts have been made to improve the mechanical properties and hand of the sheet material by carrying out the following steps:
(a) forming a thinnable fiber aggregated sheet;
(b) applying a dispersion and/or solution of elastic polymer ~A) -to the fiber aggregated sheet before or after the fibers o e the fiber aggregated sheet are temporarily fixed, and then coagulating the polymer (A);
~c) temporarily fixing the fibers if they are impregnated with the polymer ~A) before they are temporarily fixed or if temporary eixing is not su ~:ei c:lcn~;
~d) smoothin~ the sur~Elce Oe the she~t eibers using a press or a cal~ndor *oll if ~he sureace is not suEeiciently elat;
~e) impregna~.ing the ~iber aggregaked she~t wLth a dispcrsion ancl/~*
:, . , ':
33~
solution of a polymer (B) consisting princ~pally of an elastic polymer and coagulating the polymer (B~;
(f) removing the temporar~ fixing paste when the temporary fixing paste is used for temporary fixing;
(g) dissolving or decomposing and removing part or the whole of the matrix components of the fibers, thereby changing the fibers into bundles con-sisting of a number of thin fibers o~ small denier;
(h) raising one or both suraces of the dried sheet to form napped surface or surfaces; and (i~ applying other necessary finish treatments such as dying, softening and the like.
This method is not completely satisfactory. Due to a lack of bonding betNeen the rubber-like viscoelastic substance and the fibers forming the sheet, the tensile strength is not improved and the nap easily peels off the napped sheet. When a lubricant is added to the binder or applied to the product, partic-ulary in apparel applications, a so~tening effect ls achieved. However, this lubricant easily bleeds out and is removed during cleaning, leaving an uncomfortable garment with a harsh hand.
The present invention is therefore directed to providing a method of producing a sheet material which method eliminates or reduces the above-mentloned drawbacks of the conventional methods.
~t is an object of the present invention to provide a method of producing a composite fibrous sheet material having a very soft hand and good nechanical properties simultaneously and if desired a bea~lti~ully napped sur-Ge.
It ls mother object of the present lnventlon to provide a lligh-grade, artl~:lclnl leiather-lilce napped sheet whlch, cven though th:lnner than the .
, conventlonal leather-like arti~ic~al sheets~ has strength substantlally equal to or larger than that of the conventional sheets and also has a very soft hand.
Tn producing a soft sheet by applying a viscoelastic substance to thinnable fibers or filaments, the first method of producing a soft sheet material in accordance with the present inVentiO11 comprlses:
(A) applying a mixture of viscoelastic substance and a temporary filler to a sheet material containing thinnable fibers or filaments;
(B) thinning the thinnable fibers or 11aments forming the sheet material;
(C) applying the viscoelastic substance to the sheet material;
(D~ removing the temporary filler; and (E) napping the sheet material if necessary.
The method of producing a soft sheet material in accordance with the present invention also comprises:
CA) applying a mixture of a viscoelastic substance and a temporary filler to a sheet material consisting of thinnable fibers or filaments;
(B) thinning the thinnable fibers or filaments forming the sheet material;
(B') applying additional temporary filler to the sheet material or re-locating the temporary filler applied at step (A) within the sheet material;
(C) applying viscoelastic material;
(D) removing the temporary flller; and (E) napping the sheet, whenever necessary.
~he term "thlnnable fibers or filaments" used in this invention re~
fers to those fibers which become thinner by chemical~ mechanical or thermal ~rea~men~ or by a combination o~ these treatm~nts. A ~ypical exanple Oe such ~1~ers or eIlaments is the "Islands-:ln a-sea" typc disclosed in Brltish Patent .~pecle1~a~ion Nos. 1,171,~3 and 1,300,~8. ln addition to th~ "islands-in-a-sea" type compos1te f-ibers or ~llame11ts disclosed in these patent specifications, .' ~ ' " :. ,~,.
.
3~
the "islands-in-a-sea" type fibers or ~ilaments further include so-called "polymer blend fibers'~ or filaments. As polymer blend fibers or filaments both those types which generate long fibers upon the thinning treatment and those types which generate short fibers can be used in the present invention.
In the conventional methods, when the polymer blend fibers or filaments of the short fibril type are used, the resulting sheet-like material tends to have poor properties; the method of the present invention can eliminate this problem and yield a product with good properties.
The abovementioned "islands-in-a-sea" type fibers or filaments may be defined as multi-component type fibers OT filaments which generate a number of thinner fibers or filaments when at least one component ~generally the sea component) is removed from the multi-component type fiber or filament.
In such "islands-in-a-sea" type fibers or filaments, the number of island components dispersed in the sea co~ponent is usually at least 4 and preferably 8 or more in the fiber cross-section.
In the abovemen~ioned "thinnable fibers or filaments" are included "split type" fibers or filaments which can be divided into a number of thinner fibers or filaments by mechanical, chemical or thermal treatment or by a com-b~nation of these treatments. Such split type ~ibers or filaments are dis-closed, ~or example, in United States Patents 4,109,038, 4,051,287, ~,073,988 and 4,165,556.
Further, the "thinnable fi~bers" or filaments in the present invention ~nclude ~imetal composite fibers or filaments and those sheath-and-core type eibers or fil~ments whlch ~enerate ~h~nner fibers when clivided or when a~ least one component thereoe is removed. The "islancls-in-a-sca" ~ype eibeTs or fila-ments are especialLy pre~erred, The s:L~e Oe the supereine fibers or fLlaments ~enerated as a reslllt , ~
: ~ .
-3~
o~ thinnlng the thinnable fibers or filaments is less than 1 denier, pre~erably below 0.8 denier, and more preferably below 0.3 denier.
The term "fibrous sheet" used herein includes non-woven fabric, knitted fabric, woven fabric, combinations thereof and such fabric treated with various binders. Particularly when non-woven fabric is used, the advantages of the present invention are readily apparent. These fibrous sheets may con-taln the thinnable fibers or filaments as the fibrous component within a range such that the objects of the present invention are achieved.
The fibrous sheet in the present invention may consist solely of the thinnable fibers or filaments especially in the case of making more soft sheet. In the case of a knitted or woven fabric, the thinnable fibers or filaments can be effectively used as part of the warp and weft forming the fabric. The quantity of thinnable fihers or filaments in the fabric to achieve the objects of the present invention is dete~nined by such parameters as the structure of a knitted or woven fabric, the density of a non-woven fabric and other such variables. A napped product is produced most effectively from a standpoint of production cost, aesthetics and other product properties when thinnable fibers are used for at least the nap-forming fibers.
Next, a mixture of temporary filler and viscoelastic suhstance i5 appliod to the abo~ementioned fibrous sheet.
~s the vlscoelastic substance, various types of polyurethane, various rubber-like substances such as NBR and various substances which exhibit visco-~lastieity such as silicone rubber and -~luororubber can be used. In other words, the woll-knowll viscoelastic substances which are used eor conventional artl~ieicll leather can be used in this inventlon. Two or more viscoelastie substances Inay be used in eolnblnation, The pre~orred vLscoelastic substances nre ~poly~meric substancos having elongation at break of at least 300% and stross ., . ',:
3~
at 100% elongation of up to 200 kg/cm2. The measurement is made by testing a fIlm-like sample ~maximum thickness - 2mm~ which is ~ree of structural defects such as having stress concentration or lacking orientation in a specific direction. The test method involves cutting a sample 5 mm-wide and 2 cm long and pulling the sample at a rate of 10 cm/min. at 20C. ~ 2C. and R~l 65% + 2%.
As the viscoelastic substance, polyurethane is particularly preferred.
Many types of polyurethane are known, and the various types of polyurethane used foT artificial leather may be used in the present invention.
Polyurethane is a reaction product between a high-molecular weight polyol, an organic diisocyanate and a chain-extending agent. Examples of high-molecular weight polyol are polyether polyol, polyester polyol and the copolymer of polyether and polyester polyol. Typical examples of polyol are polycaprolac-tone diol, polyte~ramethylene ether glycol andthe copolymer of polycaprolactone diol and polytetra~nethylene ether glycol, polyethylene adipate, polydiethylena adipate, polypropylene ether glycol and the like. A molecular weight of 800 to 4,000 is preferred.
Examples of suitable organic diisocyanates are aromatic diisocyanates such as diphenylmethane-4,~'-diiocyarlate, tolylene diisocyanate, naphthylene diisocyanate, diphenyl diisocyanate and xylylene diisocyanate, and aliphatic diisocyanates such as hexamethylene diisocyanate, lysine diisocyanate and dicyclohexylmethane-4,4'-diisocyanate. Aromatic diisocyanates are especially e~ective where heat resistance is required. Aliphatic diisocyanates are especially ef~ectlve where light~astness is required.
~s the cllain~e~endirlg ageTIks, dlamines or di or trl-~unc~ion~
alcohols ne low molec~llclr wcights may be used. ~xamples of sllitable diamines :~nclLIde al:lphatic diamines such as hydrazine, ethylenedlamine, propylellediamine, -krlmethylenediamine~ tetramethylened~amine, pentamethylclledlamllle, hexamethy~
,~
" , : .:
~s~
lenediamine, l,~-diaminopiperazine and ~,4'-diaminodicyclohexylmethane, and aromatic diamines such as phenylenediamine, tolylenediamine, p,p'-diaminodiphen-ylmethane and the like.
Examples of di- or tri-functional alcohols of low molecular weights are ethylene glycol, propylene glycol, butanediol, neopentyl glycol, 1~6-hexane-diol, diethylene glycol, glycerin, trimethylolpropane and the like. They may be used ln various combinations.
Preferred types of polyurethane are illustrated as follows:
~1) a polyurethane composition obtained ~y dissolv~ng in a water-miscible organic solvent a substantially linear block polyether-polyester type polyure-thane in which polytetramethylene ether glycol of a molecular weight o~ at least about 800 and polycaprolactone diol of a molecular weight of at least about 800 are bonded to the organic diisocyanate residues and to the diamine residues by urethane bonds and by urea ~onds, and the weight ratio between the polytetramethylene glycol and the polycaprolactone dlol is in the range of about 50/50 to about 90/lO ~as disclosed in Japanese Patent Publication No.
~0143/1975, Okazaki et al); and
This invention relates to a composite fibrous sheet, especially ~o a napped compos~te fibrous sheet wh~ch has good mechanical properties while also having the desired so-ftness.
The use of "artificial leather" produced by applying a viscoelastic substance to a fibrous sheet has been ever-increasing in recent years.
Uses include not only shoes, bags, upholstery and the like but also clothing. Typical requirements for artificial leather are that it must be soft and, at the same time, must have good mechanical properties such as high abrasion resistance and high tear strength. ~t must also have the desired surface appearance.
Various attempts have been made to satisfy these requirements, as exemplified by the following methods. British Patent No. 1,300,268 discloses a typical method which comprises applying a rubber-like viscoelastic substance to a fibrous sheet consisting of specific flbers, such as "islands-in-a-sea"
type fibers or filaments, and then removing part of the specific fibers such as the sea component in order to obtain a sheet material having a soft and pli-dble hand.
The method typified by United States Patent 3,706,613 comprises applying first a soluble binder such as polyvinyl alcohol to a sheet consisting o specific ~lbers such as "islands-in-a-sea" type composite fibers or ~ilaments, ~hen removing part of the specific fibers such as, for example, the sea com-ponent to generate superfine fibers, applying a viscoelastic substance such as polyurethane or the like and thereafter removing the soluble binder. Various lubriGants or soEteners may be added to the binder or to thc product to soeten the product.
Those methods have mcrit, but they alsc have the followin~ critical probl~ms. rrhe sheet obtainecl by eirst applyLng a rubber~ e viscoelastic : : :
:, ..: 1 ~ . -:, - ~ :
..-.
~ ~ 5t3~Z~
substance and then remo~lng one component of the speci~ic fibers, as typified by the abovementioned Rritish Patent No. 1,300,268, produces a sheet having a soft hand. ~lowever, the sheet has low tensile strength due to gaps generated between the superfine fibers and the rwbber-like viscoelastic substance. When the sheet is raised to produce a napped surface effect, the nap easily peels off, which is a serious drawback. Further, since the solvent for the vlsco-elastic substance is, in most cases, also a solvent for khe fiber-forming components, applicatlon of the viscoelastic substance becomes extremely un-stable and continuous production of uniform product is difficult.
~n the method exemplif:led by United States Patent No. 3,706,613, there is a high probability of the superfine fibers and the rubber-like viscoelastic substance being bonded directly to one another. This produces a product with a secure nap) but the bonded parts between the superfine fibers and the rubber-like viscoelastic substance are relatively large yielding a product with a rubber-like hand which is undesirable in clothing.
Attempts have been made to improve the mechanical properties and hand of the sheet material by carrying out the following steps:
(a) forming a thinnable fiber aggregated sheet;
(b) applying a dispersion and/or solution of elastic polymer ~A) -to the fiber aggregated sheet before or after the fibers o e the fiber aggregated sheet are temporarily fixed, and then coagulating the polymer (A);
~c) temporarily fixing the fibers if they are impregnated with the polymer ~A) before they are temporarily fixed or if temporary eixing is not su ~:ei c:lcn~;
~d) smoothin~ the sur~Elce Oe the she~t eibers using a press or a cal~ndor *oll if ~he sureace is not suEeiciently elat;
~e) impregna~.ing the ~iber aggregaked she~t wLth a dispcrsion ancl/~*
:, . , ':
33~
solution of a polymer (B) consisting princ~pally of an elastic polymer and coagulating the polymer (B~;
(f) removing the temporar~ fixing paste when the temporary fixing paste is used for temporary fixing;
(g) dissolving or decomposing and removing part or the whole of the matrix components of the fibers, thereby changing the fibers into bundles con-sisting of a number of thin fibers o~ small denier;
(h) raising one or both suraces of the dried sheet to form napped surface or surfaces; and (i~ applying other necessary finish treatments such as dying, softening and the like.
This method is not completely satisfactory. Due to a lack of bonding betNeen the rubber-like viscoelastic substance and the fibers forming the sheet, the tensile strength is not improved and the nap easily peels off the napped sheet. When a lubricant is added to the binder or applied to the product, partic-ulary in apparel applications, a so~tening effect ls achieved. However, this lubricant easily bleeds out and is removed during cleaning, leaving an uncomfortable garment with a harsh hand.
The present invention is therefore directed to providing a method of producing a sheet material which method eliminates or reduces the above-mentloned drawbacks of the conventional methods.
~t is an object of the present invention to provide a method of producing a composite fibrous sheet material having a very soft hand and good nechanical properties simultaneously and if desired a bea~lti~ully napped sur-Ge.
It ls mother object of the present lnventlon to provide a lligh-grade, artl~:lclnl leiather-lilce napped sheet whlch, cven though th:lnner than the .
, conventlonal leather-like arti~ic~al sheets~ has strength substantlally equal to or larger than that of the conventional sheets and also has a very soft hand.
Tn producing a soft sheet by applying a viscoelastic substance to thinnable fibers or filaments, the first method of producing a soft sheet material in accordance with the present inVentiO11 comprlses:
(A) applying a mixture of viscoelastic substance and a temporary filler to a sheet material containing thinnable fibers or filaments;
(B) thinning the thinnable fibers or 11aments forming the sheet material;
(C) applying the viscoelastic substance to the sheet material;
(D~ removing the temporary filler; and (E) napping the sheet material if necessary.
The method of producing a soft sheet material in accordance with the present invention also comprises:
CA) applying a mixture of a viscoelastic substance and a temporary filler to a sheet material consisting of thinnable fibers or filaments;
(B) thinning the thinnable fibers or filaments forming the sheet material;
(B') applying additional temporary filler to the sheet material or re-locating the temporary filler applied at step (A) within the sheet material;
(C) applying viscoelastic material;
(D) removing the temporary flller; and (E) napping the sheet, whenever necessary.
~he term "thlnnable fibers or filaments" used in this invention re~
fers to those fibers which become thinner by chemical~ mechanical or thermal ~rea~men~ or by a combination o~ these treatm~nts. A ~ypical exanple Oe such ~1~ers or eIlaments is the "Islands-:ln a-sea" typc disclosed in Brltish Patent .~pecle1~a~ion Nos. 1,171,~3 and 1,300,~8. ln addition to th~ "islands-in-a-sea" type compos1te f-ibers or ~llame11ts disclosed in these patent specifications, .' ~ ' " :. ,~,.
.
3~
the "islands-in-a-sea" type fibers or ~ilaments further include so-called "polymer blend fibers'~ or filaments. As polymer blend fibers or filaments both those types which generate long fibers upon the thinning treatment and those types which generate short fibers can be used in the present invention.
In the conventional methods, when the polymer blend fibers or filaments of the short fibril type are used, the resulting sheet-like material tends to have poor properties; the method of the present invention can eliminate this problem and yield a product with good properties.
The abovementioned "islands-in-a-sea" type fibers or filaments may be defined as multi-component type fibers OT filaments which generate a number of thinner fibers or filaments when at least one component ~generally the sea component) is removed from the multi-component type fiber or filament.
In such "islands-in-a-sea" type fibers or filaments, the number of island components dispersed in the sea co~ponent is usually at least 4 and preferably 8 or more in the fiber cross-section.
In the abovemen~ioned "thinnable fibers or filaments" are included "split type" fibers or filaments which can be divided into a number of thinner fibers or filaments by mechanical, chemical or thermal treatment or by a com-b~nation of these treatments. Such split type ~ibers or filaments are dis-closed, ~or example, in United States Patents 4,109,038, 4,051,287, ~,073,988 and 4,165,556.
Further, the "thinnable fi~bers" or filaments in the present invention ~nclude ~imetal composite fibers or filaments and those sheath-and-core type eibers or fil~ments whlch ~enerate ~h~nner fibers when clivided or when a~ least one component thereoe is removed. The "islancls-in-a-sca" ~ype eibeTs or fila-ments are especialLy pre~erred, The s:L~e Oe the supereine fibers or fLlaments ~enerated as a reslllt , ~
: ~ .
-3~
o~ thinnlng the thinnable fibers or filaments is less than 1 denier, pre~erably below 0.8 denier, and more preferably below 0.3 denier.
The term "fibrous sheet" used herein includes non-woven fabric, knitted fabric, woven fabric, combinations thereof and such fabric treated with various binders. Particularly when non-woven fabric is used, the advantages of the present invention are readily apparent. These fibrous sheets may con-taln the thinnable fibers or filaments as the fibrous component within a range such that the objects of the present invention are achieved.
The fibrous sheet in the present invention may consist solely of the thinnable fibers or filaments especially in the case of making more soft sheet. In the case of a knitted or woven fabric, the thinnable fibers or filaments can be effectively used as part of the warp and weft forming the fabric. The quantity of thinnable fihers or filaments in the fabric to achieve the objects of the present invention is dete~nined by such parameters as the structure of a knitted or woven fabric, the density of a non-woven fabric and other such variables. A napped product is produced most effectively from a standpoint of production cost, aesthetics and other product properties when thinnable fibers are used for at least the nap-forming fibers.
Next, a mixture of temporary filler and viscoelastic suhstance i5 appliod to the abo~ementioned fibrous sheet.
~s the vlscoelastic substance, various types of polyurethane, various rubber-like substances such as NBR and various substances which exhibit visco-~lastieity such as silicone rubber and -~luororubber can be used. In other words, the woll-knowll viscoelastic substances which are used eor conventional artl~ieicll leather can be used in this inventlon. Two or more viscoelastie substances Inay be used in eolnblnation, The pre~orred vLscoelastic substances nre ~poly~meric substancos having elongation at break of at least 300% and stross ., . ',:
3~
at 100% elongation of up to 200 kg/cm2. The measurement is made by testing a fIlm-like sample ~maximum thickness - 2mm~ which is ~ree of structural defects such as having stress concentration or lacking orientation in a specific direction. The test method involves cutting a sample 5 mm-wide and 2 cm long and pulling the sample at a rate of 10 cm/min. at 20C. ~ 2C. and R~l 65% + 2%.
As the viscoelastic substance, polyurethane is particularly preferred.
Many types of polyurethane are known, and the various types of polyurethane used foT artificial leather may be used in the present invention.
Polyurethane is a reaction product between a high-molecular weight polyol, an organic diisocyanate and a chain-extending agent. Examples of high-molecular weight polyol are polyether polyol, polyester polyol and the copolymer of polyether and polyester polyol. Typical examples of polyol are polycaprolac-tone diol, polyte~ramethylene ether glycol andthe copolymer of polycaprolactone diol and polytetra~nethylene ether glycol, polyethylene adipate, polydiethylena adipate, polypropylene ether glycol and the like. A molecular weight of 800 to 4,000 is preferred.
Examples of suitable organic diisocyanates are aromatic diisocyanates such as diphenylmethane-4,~'-diiocyarlate, tolylene diisocyanate, naphthylene diisocyanate, diphenyl diisocyanate and xylylene diisocyanate, and aliphatic diisocyanates such as hexamethylene diisocyanate, lysine diisocyanate and dicyclohexylmethane-4,4'-diisocyanate. Aromatic diisocyanates are especially e~ective where heat resistance is required. Aliphatic diisocyanates are especially ef~ectlve where light~astness is required.
~s the cllain~e~endirlg ageTIks, dlamines or di or trl-~unc~ion~
alcohols ne low molec~llclr wcights may be used. ~xamples of sllitable diamines :~nclLIde al:lphatic diamines such as hydrazine, ethylenedlamine, propylellediamine, -krlmethylenediamine~ tetramethylened~amine, pentamethylclledlamllle, hexamethy~
,~
" , : .:
~s~
lenediamine, l,~-diaminopiperazine and ~,4'-diaminodicyclohexylmethane, and aromatic diamines such as phenylenediamine, tolylenediamine, p,p'-diaminodiphen-ylmethane and the like.
Examples of di- or tri-functional alcohols of low molecular weights are ethylene glycol, propylene glycol, butanediol, neopentyl glycol, 1~6-hexane-diol, diethylene glycol, glycerin, trimethylolpropane and the like. They may be used ln various combinations.
Preferred types of polyurethane are illustrated as follows:
~1) a polyurethane composition obtained ~y dissolv~ng in a water-miscible organic solvent a substantially linear block polyether-polyester type polyure-thane in which polytetramethylene ether glycol of a molecular weight o~ at least about 800 and polycaprolactone diol of a molecular weight of at least about 800 are bonded to the organic diisocyanate residues and to the diamine residues by urethane bonds and by urea ~onds, and the weight ratio between the polytetramethylene glycol and the polycaprolactone dlol is in the range of about 50/50 to about 90/lO ~as disclosed in Japanese Patent Publication No.
~0143/1975, Okazaki et al); and
(2) a polyurethane emulsLon consisting o~ water and polyurethane ob-tained by reacting an NCO group-excessive prepolymer between a polyo:L and a polyisocyanate with a chain-extending agent in the presence of water whereby the polyol consists o~ (A) polyes-ter polyol o~ a molecular weight o~ 500 to
3,000, (B) polyoxyalkylene (C2 - C3) polyol of a molecular weight of 200 to 5,000 and, ~ necessaryJ ~C) polyol of a low molecular weight, the average mixed molecular weight of the mixture (A) ~ (B) -~ (C) is 1,000 -to 3,000 and the weight ra~io (A/B~C) Ls -~rom 10 -~o 0.5 ~as disclosed in Jap,mese Patent l,aid-Open No. lSSfi27/1977, ~ugLmoto et al).
'rhese polyuretha~es are employed as a solution or as an emulsion.
.: :
.
:, :.
As descr~bed previously, in the present inventionl the viscoelastic substance is used at steps ~A) and (C). As the viscoelastic substance used at step (A), it is preferable to use a three-dimensional crosslinked polymer.
The term"three-dimensional crosslinked polymer" herein used refers to a polymer that is three-dimensionally crosslinked in advance as well as a polymer that can be three-dimensionally crosslinked after it is applied. In addition, the vlscoelastic substance to be used at step ~A) is preferably of the emulsion type. This broadens the selection range of treating agents for dissolving and removing at least one component o the thinnable fibers or filaments, or for treating these fibers or filaments as to make them easily divisible by use of a swelllng agent. Furthermore, excessive swelling of the viscoelastic substance can also be restricted.
As the viscoelastic substance to be used, particularly at step ~A), it is advisable to use those which can be dry-coagulated. An emulsion-type viscoelastic substance is preferred. As the ~iscoelastic substance to be used at step (C)l it is advisable to use those which can be wet-coagulated. HereJ
a solution-type viscoelastic substance is preferred. Such a combination makes it possible to markedly improve the strength of the resulting sheet, while the sheet remains soft.
'l'hough not fully clariiedl the mechanism through which both softness and good abrasion resistance and tear strength are achieved is suspected to be as follows. ~irstl if a dry coagulation-type viscoelastic substance is employed at step (A)l the substance migrates and tends to concentrate on the points o~
Intersectiorl o~ the fibers or between tho ~ibers at the time o~ dry coagulation -tllus produclng a shee~ with hLgh strengthl capable o~ ~iths~anding large de-~oTma~lon stress. Next, i~ a wet coagula-tion-typc viscoelastic substance is employed at step ~C)I migra~ion o~ ~he viscoelas~ic substance does not ~ccur _ 9 _ .
. .
3~
at the time of wet coagulatlon and the vIscoelastic substance is applied to sheets more uniformlythan in the case of the dry coagulation~ This yields a sheet capable of withstanding even small deformation stress. By the inter-action of these mechanisms~ the strength of the sheet is presumably increased flS a whole. However, the present invention ~s not restricted to this partic-ular combination. The objects of the present invention can be accomplished by combinations of dry coagulation-dr~ coagulation, wet coagulation-wet coagulation and wet coagulation-dry coagulation. It is assumed, further, that the softness of the sheet is developed by the use of a mixture of visco-elastic substance and temporary filler at step ~A), reapplication o~ the tem-porary ~iller or its relocation at step (B') and removal of the temporary filler at step ~D).
As the temporary filler in the present invention, any material may be used as long as it can be selectively removed without dissolving and -removing the viscoelastic substance and it is in solld form at room temperature.The temporary filler material should be a m$terial which does not have a sol-vent in common ~ith the viscoelastic material or if it does, it should remain solid at room temperature and not have a solvent common with the viscoelastic substance at that temperature~ Such solvents may include:
ta~ wat~r, ~b) alcohols o~ up to 15 carbon atoms, (c) esters o~ up to 15 carbon atoms, (d) ethers of up to 15 carbon atoms, ~e) amines o~ up to lS carbon atoms, tf) amides of up to 15 carbon atoms, (g) acetic acid and chloracetic acid, (h) chlorinated hydrocarbon of up to 10 carbon atoms, and ~heir mlxtures.
Specif:lc examples of temporary e~ller materlal lnclude celluloslc ma~erl.lls such flS starch, me~hylcellulose, or carboxymethylcellulose and polyvinyl alcohol and its copolymer with vlnyl aeetflte. Also included are ' , .
3~
inorganic salts such as calcium carbonate. Cenerally, water-soluble materials are preferred because they can be extracted or subjected to the relocation treatment using water. Of them, water-soluble materials such as polyvinyl alcohol, carboxymethylcellulose and starch are preferred.
The mixture of the temporary filler and the viscoelastic substance to be employed at step (A) may be either a mixture in an aqueous system or a mixture in an organic solvent system. The temporary filler and the visco-elastic substance may be dissolved or dispersed in the liquid.
Whether or not the viscoe;astic substance and the temporary filler have a common solvent, it is preferable that the mixture be homogeneous.
The mixing ratio of the temporary filler and the viscoelastic substance is not specifically restrictive but a preferred range for the visco-elastic substance is from 3 to 95% by weight and a specifically preferred range is from 5 to 93% by weight. If the content of the viscoelastic sub-stance is below 3% by weight, the resulting product is of poor quality. Where the temporary filler is further applied after the thinnable fibers or fila~
ments are thinned, this reduction in quality is intensified. For this reason, it is preferred that the content of the viscoelastic substance be more than 5% by weigh-t.
lf the amount of temporary filler in the mixture with the viscoela~
stic substance is small, the softness of the resulting sheet-like material be-comes insufficient. For this reason, at least 5% by weight, more preferably 7% by weight, o- the temporary filler should be used. I~ the content o the temporary eLllor is too great, thc quality of the resulting shect-llke Inaterial would be lowercd. Ilence, the upper limit should be 97% by welght.
The deposition amount of the rnlxture o~ the temporary f-iller and the viscoelastlc substance to the shcet ~aries markedly depending UpOII the ;. ,.
' , -, . .
. . . , ~ ~: .
:, .. , ;';' . . .
~ ~33~
ki~nd of sheet, but generally, ~rom 0,5~ by~w~ight up to 70% by ~eight of the mixture based on the weight of the t~l`nnaale ~ eTs or ~ilaments that ~orm the sheet IS applied. Below 0.5% by weight, properties of the product such as abrasion resistance would be lowered. Especially when fibers or Eilaments which are thinned by removing at least one o$ the components by chemical treat-ment or the like are employed in great quantities as the sheet-forming Eibers or ilaments, the deposition amount is preferably at least 1% by weight.
Generally, the upper limit of the deposition amount is 50% by weight to ob-tain the desired hand. It is also advisable to use a greater deposition amount for non-woven abric and a smaller deposition amount for knitted or woven fabric. For non woven fabric, the advisable deposition amount is 10-50%
by weight; for woven or knitted fabric the advisable deposition amount is 1-30% by weight. Various heretofore known methods ma~ be used Eor deposttion of the mixture, such as impregnation, spraying, coating, combinations of these methods and the like.
Next, the sheet-forming fibers or filaments are thinned. The term "thinning" in this specification means to make the fibers thinner by chemical~
thermal or mechanical treatment or the combination of these treatments, or to "fibrillate" the fiber. At times, the fibers or filaments need not all be thinned in the axial direction. Nor is it necessary that the fibers or fila-ments be divided so that they can be seen clearly with the naked eye. Hence, the term "thinning" also includes such a preparatory state from which the fib-ers or Eilaments can be divided by a subsequent simple treatment.
Various hercto-~ore known thinning methods may be uscd as the thinnln~ mathod in the present invention. In -the so cAlled "is1ands-ln~a-sea"
-type ~iber5 or ~ilamen-~s such as ~he "islands ~n~a-sea" type composite fibers or Eilarnents or the polymer blend ~ibers o~ ;eilaments or "shea-th and core~' -.
. .
' ~.
z~
type composite ilaments or fibers treatment o~ the fibers or filaments with a solvent or a decomposition reagent to remove the sea component or the sheath component is most effective. By this method, superfine fibers or filaments are easily produced. As a result, the method is especially effecti~e for producing an extremely soft sheet product. IE -the fibers or filaments are composite fibers or filaments consisting of at least two polymers, each having different swellability to water, to a swelling agent, to other liquids or to heat, separation between the plural components by a swelling treatment or the like by utilizing the difference of swellability is also an effective method.
Adding a foaming agent or the like to the fibers or filaments and foaming them is also recommended so that the fibers or filaments are thinned in the fibril-lated form. The fiber size after thinning is preferably up to 0.8 denier and especially preferably up to 0.3 denier to achieve the desired hand with plia-bility, drapeab~lity and suppleness.
The mode of thinning may be classified into the following two types. rn the first type, a pluralit~ of thinner fibers or filaments are generated by the thinning of the fibers or filaments such as when the "islands-in-a-sea" type composite fibers or filaments, the polymer blend fibers or filaments or the peel-split type fibers or filaments are used or when the bimetal-type composite fibers or filaments are split. In the second type, the flbers or filaments are not divided into a plurality of fibers or filaments even after thinning such as when one component is dissolved or decomposed and r~moved from the sheath and core type composLte fibcrs or filannen-ts or the blm~tal-type Ei~ers or Eilaments. ~enQrally, the ~ormer type is pre~erred.
The vLscoelastic substance is ~hen applied to the -thillned sheet.
The vlco~lastic suhstance may be the same as, o~ di~eererl~ eronl~ the one pre-v:~ollsly applled. As describecl already, howe~er, 1~ the viscoelastic substance ., , ,. .. :
. ;, . ~' .
:. :
- ' . : , ':: ~ -~ 3~3'Z~
used at step (A) is a dry-coagulation type, the viscoelastic substance to be used at step (C) is pre~erabl~ of a wet-coagulat~on type. In either case, it is pre~erred that the viscoelastic substance be dissolved or dispersed in a liquid system which does not easily dissolve the temporary filler. The de-position amount varies markedly depending upon the type of the sheet, bu~ the total deposition amount in steps (A) and (C) is preferably 1-100% of visco-elastic substance by weight based on the weight o the thinnable fiber sheet, more preferably at least 3% by weight. I~ the amount is below the lower limit, tha sheet has low strength and creases occur on the sheet. In the case of a non-woven fabric sheet where the thinnable fibers or filaments occupy the major proportions of the fibers or ~ilaments forming the non-woven fabric, it is preferred that about 15-80% by weight of the viscoelastic substance be applied.
~hen the viscoelastic substance is of the emulsion type and in the usual case, it is useul to use heat-setting ~or making good mechanical pro-perties, heat-setting may be practised in a suitable manner. When the visco-elastic substance is of the wet-coagulation type, it is possible to use known methods which sufficiently coagulate the viscoelastic substance, for example, d~pping into a coagulation bath or the like. All types of known dry-coagulation methods or wet-coagulation methods may be used.
Subsequently, the temporary filler is removed. There are various methods of removing the filler,but the dissolving method is the most common.
A sheet obtained in this manner has extremely good mechanical properties and has a soet hand. I further softening of the sheet is desired, temporary ~iller may be reapplied to the sheet or the tomporary filler may be relocated ~n the sheet, a~ter steps ~A) and ~B~. rrhis is the ~'second method", especially s~ep ~B~ the temporary ~iller is again applied, ik may be the same as, or dieeeren~ erom, -the one applied prev.lously. I~ relocation Oe the temporary , . - 1~ -': ~
,' "
. ' ,. ~:
~4~ 2 ~
filler is chosen, the relocat~on o~ the te~pora~ ller can be efeected by passing the sheet in the solvent o~ the tem~orary~ ~illeT, or by applying mechanical stress to the sheet, such as by pressing the sheet through a mangle or by applying vibration to the sheet while the sheet is being passed through the solvent of the temporary filler. The term "relocation" hereby means that the relative position of the temporary filler to the viscoelastic substance and to the fibers or filaments in the sheet is changed. The mechanism of the ~ncrease in softness in the product due to the relocation of the temporary ~iller has not yet been fully clarified. It is assumed, however, that part of the temporary filler migrates and covers at least part of the viscoelastic substance or at least part of the surface o~ the thinned fibers or filaments.
Where the temporary filler is reapplied, it is not necessary that the filler be applied separatel~. Hence, a mixture of the temporary filler and the viscoelastic material may be applied. At times, the deposition amount need not be increased as described in the case of the relocation of the temporary filler. When greater softness is required, at least 3% by weight, based on the weight o the thinnable fibers or filaments of the sheet, of the temporary filler must be applied at this time. Generally, this de-position amount ls up to about 80% by weight.
Subsequently, the viscoelastic substance is applied. F,xalmples Oe the viscoelastic substance applied at this point are the same as those illus-trated above and the deposition amount is also substantially the same. The total deposition amount Oe the viscoelastic substance is selected from the rang~ ne from I to 100% by weight based on th~ wcight o-~ the thinnabLq Pibers or ei Laments o~ thc sheet. When the viscoelastic substance is of the emulsion type and heat-set~ing is nece~sary Por coagulating the substance in the same way as in th~ ~rst method, heat-settlng may bq practised using standard methods.
. ,5 _ :' , . ~ .
. ' : ~ '. ' :~ ., ,. ~:
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When the viscoelastic substance ~s o~ the ~et-coagulation type, su~ficient coagulation ma~ be achieved for example by dipping in a coagulation bath or the like.
Thereafter, the temporary :Elller is removed. The m~thod o~ removing the filler is the same as tha~ illustrated in the first method where the filler is dissolved or decomposed for removal. The sheet obtained in this manner is extremely soft and has good mechanical properties. Morover, the sheet surface is uniform.
The resulting sheet material may be further treated by raising to produce a napped sheet surface whenever necessary. The napping method is not particularly restrictive. Various heretofore known methods such as needle raising and buffing with emery paper, sandpaper or emery cloth may be used.
Where the napping treatment is used, an artificial leather which has good hand and pliant, beautiful surface and is similar to various natural raised leathers such as suede-like raised leather and a vicuna-like raised leather can be produced. The napping treatment also improves the softness.
~t is also possible, whether or not the napping treatment is used, to obtain a grained artificial leather by making a grained surface on at least one sur-eace of the composite sheet.
In accordance with the method o~ the present invention, it becomes poss~ble to produce a composite fibrous viscoelastic material impregnated with a viscoelastic substance which material, though soft, has good mechanical pro-perties such as high abrasion resistance and high tensile strength and which c~n be used ee~cct:Lvely eor produclng clotl~s~shoes, bags, upholstery and s~
~orth~ Tn colnparison with the conventional hlgh-grade shee-t materials, khere-foreJ the sheet maker~al Oe the presenk invontion can be n~ade addlkionally thlnner while mainkaining lts charac~er~ The presellt lnvention ls capable of - 16 _ ' 3~
eliminatIng the problems with the con~entional sheet materials in that their strength is markedly reduced and practical utility is lost when the thickness of the sheet material is reduced. The method of the present invention makes it possible to put a thinner sheet material into practical application Though several examples o~ the present invention will be illustrated in the following paragraphs, the present invention is in no way restricted by these exa~tples.
The following polyurethanes were used in Examples l through 3 and Comparati~e Example l.
(A) E s ~ e (1) high-molecular weight polyol component: conjoint use of polyoxy-propylene glycol ~molecular weight approx. 1,000) and polyoxypropylenetriol Cmolecular weight approx. 1,000~ in a weight ratio of 75:25.
~2) organic diisocyanate component: 2,4-tolylene diisocyanate ~3) chain-extending agent: 4,4'-diaminodicyclohexylmethane ~B) Solution type polyurethane ~1~ high-molecular weight polyol component: conjoint use of polycaprol-actone diol ~molecular weight approx. 2,000) and polytetramethylene ether glycol ~molecular weight approx. 2,000) in a weight ratio of 30:70.
~xample 1 A web was ~o:rmed from "islands-in-a-sea" type composite l'~bers cetnsistlng of polyethylene terephthalate as the island component and poly-styrene containing 20 mol % of 2-ethylhexyl-acrylate copolymerized therewith as the sea component and having a weight ratio of 50:50 between the island colnpctnctnt and ~hc sefl component and slze Oe 4.5d ~the number of islands ~ 16, ~he size Oe each islancl component ~ 0.14d~ and was needle-punchecl to yield a non-woven ~abric. Thereaeter, ~he non-wo~en eabric was trea~cld w;th hot water ;
, .. ; ., 2~
at 80C reducing thc sur~ace area by 23%. The weight o~ this non-woven fa~ric was 630 g/m2. The non-woven fabric was then impregnated with a mixed solution of 5% by weight of polyvinyl alcohol as tlle ternporary filler and 5% by weight of a polyurethane emulsion as the viscoelast~c substance and 90% by weight of water, and was dry-coagulated at 100C for 10 minutes. The deposition amount o~ the mixture ~as 11% by weight on the basis Oe the "island-in-a-sea"
type composite ibe~s. Thereafter, the sea component was removed using trich-loroethylene, thereby thinning the fibers. The removal ratio was 98.5% by weight. After heat treatment at 150C for 10 minutes, a 7 wt. % polyurethane solution ~solvent = dimethylformamide) was ~urther applied and the ~ibers were wet-coagulated in water at room temperature, then dipped into hot water at 80C and passed through a mangle to remove the polyvinyl alcohol. This procedure of dipping into hot water and passing through a mangle was repeated 15 times.
The total deposition amount of the polyurethane thus applied was ~1% h~ weight calculated as the solid content on the basis of the thinned f~bers. The resulting sheet was sliced into two thinner sheets. Each sheet was buffed to form a napped surface and then dyed to produce an artificial leather. The resulting products were rich in softness, had dense nap and good mechanical properties. The abrasion resistance was 577 c~cles and the tear strength was l.Okg in the transverse direction and 1.2kg in the longitudinal direction. The abrasion resistance was measured by causing wear on the surface of the sheet using a rotary nylon brush and counting the number of rotations roqulred to break the shee~, The tear strength was rneasured in accordance Wi~]l meth~d C s~lp-llated ln ~rs L-1079.
Con3~arat:lve~
__ The shrunlc fabric as in Example 1 was treated with a 10% polyvinyl '' alcohol solutlon (PVA solution), and dried. Then the sea component of the fiber was removed with trichloroeth~lene as in Example 1. A polyurethane solution (15% concentration) using dimethylformam~de CDMF) as the solvent was then applied. We~ coagulation of the polyurethane and removal of the PVA were carried out as in Example 1. The deposltion amount of the polyurethane was 48% by weight on the basis of the thinned fibers. Slicing~ buffing and dyeing were then carried out. The product ~as relatIvely soft ~63 mm in ~he long-itudinal direction and 45 mm in the transverse direction as measured in accor-dance with Clark method stipulated by JrS L-1079). However, the properties of product were low as the abrasion resistance was 225 cycles and the tear strength was 0.5kg in the transverse direction and 0.7kg in the longitudinal direction.
Example 2 A web was formed from "islands-in-a-sea" type composite fibers con-sisting of n~lon 6 as the island component and polystyrene containing 18 mol %
of 2-ethylhexyl-acrylate copolymerized there~ith as the sea component and having an island-to-sea ratio of 55t~5 ~by weight), size of 5.5d, the number o~ islands of 36 and a size Oe 0.08d for each island component, and was needle-punched to ~leld a non-woven fabric. The resulting non-woven fabric was treated wi.th hot water at 80C. reducing the sureace area by 29.5%. The weight o~ this felt was 595 g/m2. The felt was then impregnated with a mixed solution consisting oE 7% by welght of polyvinyl alcohol ~PVA~, 7% by weight of a polyurethane emulsion and 86% by weight water. It was then dry-coagulated at 100C for 10 minutes. Tlle total depos3tion amount as the sum Oe PV~ and polyure-thane was 15% by weight on the basis Oe the welghk oE tlle thinnable fibers.
Nex~ tlle sea component was removed with trichlorc)ethylerle to thln th~ $1bers. The removal ra-tio was 98,7% b~ ~elgllt. A~ter heat-settln~ at 150C
:
33~
for 10 minutes, the sheet was impregnated with a dimeth~lformamide solution (DMF solut~on) of polyurethane (12 wt. % concent~atlon). The polyurethane was then wet-coagulated with the water at room temperature and the PVA was removed as in Example 1. The total deposition amount of the polyurethane emulsion and the polyurethane solution was 38.5% by weight calculated as the solid content on the basis of the thinned fibers. The sheet was sliced into two thinner sheets and the surface of each sheet was buffed, napped and then dyed to produce a suede-like artiflcial leather. The product was very soft (as soft as 58 mm in the longitudinal direction and 45 mm in the tTansverse direction in accor-dance with Clark method stipulated by JlS L-1079) and had an excellent nap. In addition, the product had enhanced properties such as abrasion resistance of 1,235 cycles and tear strength of 2.4kg in the longitudinal direction and 1.5kg in the transverse direct~on.
Example 3 The thinned fiber fabric of Example 2 treated wlth PVA and emulsion polyure~hane was passed through water at 60C for about one minute and then was passed through a mangle. This procedure of passing through the water and the mangle was repeated twice to relocate the PVA. Thereafter, the felt was dried.
The PVA decreased 3% by weight.
The ~elt was further :Lmpregnated with a 16 wt. % DMP solution of polyurethane and wet-coagulated with water at room temperature and the PVA was removed in the same way as in ~ample 1. The total deposition amount of the emulsion-type polyurethane and the solutlon-type polyurethane was 41% by weight calculated flS khe solid content on the basis o~ the thinned fibers. The sheet WflS sllcecl ln-to two th:lnner sheets, blleee(l and dyed to produce suede-llke ar-ki~:Lclfll Ieather. 'rhe product was ri.ch ln so:etness (as soet as 38 mm :In -the longitudinal cl~rectlon and 28 mnl ln the transverse dlrectlon ln aecord~mce wlth "
, ~, :' , 3 ~
the metllod st.ipulated by JIS-1079) and had a ~ne, beauti~ul n~p and good mechanical properties. The abrasion resis~nce was 1,033 cycles and the tear strength was 2.6kg in the longi~udinal direction and 1.9kg in ~he transverse direction.
'rhese polyuretha~es are employed as a solution or as an emulsion.
.: :
.
:, :.
As descr~bed previously, in the present inventionl the viscoelastic substance is used at steps ~A) and (C). As the viscoelastic substance used at step (A), it is preferable to use a three-dimensional crosslinked polymer.
The term"three-dimensional crosslinked polymer" herein used refers to a polymer that is three-dimensionally crosslinked in advance as well as a polymer that can be three-dimensionally crosslinked after it is applied. In addition, the vlscoelastic substance to be used at step ~A) is preferably of the emulsion type. This broadens the selection range of treating agents for dissolving and removing at least one component o the thinnable fibers or filaments, or for treating these fibers or filaments as to make them easily divisible by use of a swelllng agent. Furthermore, excessive swelling of the viscoelastic substance can also be restricted.
As the viscoelastic substance to be used, particularly at step ~A), it is advisable to use those which can be dry-coagulated. An emulsion-type viscoelastic substance is preferred. As the ~iscoelastic substance to be used at step (C)l it is advisable to use those which can be wet-coagulated. HereJ
a solution-type viscoelastic substance is preferred. Such a combination makes it possible to markedly improve the strength of the resulting sheet, while the sheet remains soft.
'l'hough not fully clariiedl the mechanism through which both softness and good abrasion resistance and tear strength are achieved is suspected to be as follows. ~irstl if a dry coagulation-type viscoelastic substance is employed at step (A)l the substance migrates and tends to concentrate on the points o~
Intersectiorl o~ the fibers or between tho ~ibers at the time o~ dry coagulation -tllus produclng a shee~ with hLgh strengthl capable o~ ~iths~anding large de-~oTma~lon stress. Next, i~ a wet coagula-tion-typc viscoelastic substance is employed at step ~C)I migra~ion o~ ~he viscoelas~ic substance does not ~ccur _ 9 _ .
. .
3~
at the time of wet coagulatlon and the vIscoelastic substance is applied to sheets more uniformlythan in the case of the dry coagulation~ This yields a sheet capable of withstanding even small deformation stress. By the inter-action of these mechanisms~ the strength of the sheet is presumably increased flS a whole. However, the present invention ~s not restricted to this partic-ular combination. The objects of the present invention can be accomplished by combinations of dry coagulation-dr~ coagulation, wet coagulation-wet coagulation and wet coagulation-dry coagulation. It is assumed, further, that the softness of the sheet is developed by the use of a mixture of visco-elastic substance and temporary filler at step ~A), reapplication o~ the tem-porary ~iller or its relocation at step (B') and removal of the temporary filler at step ~D).
As the temporary filler in the present invention, any material may be used as long as it can be selectively removed without dissolving and -removing the viscoelastic substance and it is in solld form at room temperature.The temporary filler material should be a m$terial which does not have a sol-vent in common ~ith the viscoelastic material or if it does, it should remain solid at room temperature and not have a solvent common with the viscoelastic substance at that temperature~ Such solvents may include:
ta~ wat~r, ~b) alcohols o~ up to 15 carbon atoms, (c) esters o~ up to 15 carbon atoms, (d) ethers of up to 15 carbon atoms, ~e) amines o~ up to lS carbon atoms, tf) amides of up to 15 carbon atoms, (g) acetic acid and chloracetic acid, (h) chlorinated hydrocarbon of up to 10 carbon atoms, and ~heir mlxtures.
Specif:lc examples of temporary e~ller materlal lnclude celluloslc ma~erl.lls such flS starch, me~hylcellulose, or carboxymethylcellulose and polyvinyl alcohol and its copolymer with vlnyl aeetflte. Also included are ' , .
3~
inorganic salts such as calcium carbonate. Cenerally, water-soluble materials are preferred because they can be extracted or subjected to the relocation treatment using water. Of them, water-soluble materials such as polyvinyl alcohol, carboxymethylcellulose and starch are preferred.
The mixture of the temporary filler and the viscoelastic substance to be employed at step (A) may be either a mixture in an aqueous system or a mixture in an organic solvent system. The temporary filler and the visco-elastic substance may be dissolved or dispersed in the liquid.
Whether or not the viscoe;astic substance and the temporary filler have a common solvent, it is preferable that the mixture be homogeneous.
The mixing ratio of the temporary filler and the viscoelastic substance is not specifically restrictive but a preferred range for the visco-elastic substance is from 3 to 95% by weight and a specifically preferred range is from 5 to 93% by weight. If the content of the viscoelastic sub-stance is below 3% by weight, the resulting product is of poor quality. Where the temporary filler is further applied after the thinnable fibers or fila~
ments are thinned, this reduction in quality is intensified. For this reason, it is preferred that the content of the viscoelastic substance be more than 5% by weigh-t.
lf the amount of temporary filler in the mixture with the viscoela~
stic substance is small, the softness of the resulting sheet-like material be-comes insufficient. For this reason, at least 5% by weight, more preferably 7% by weight, o- the temporary filler should be used. I~ the content o the temporary eLllor is too great, thc quality of the resulting shect-llke Inaterial would be lowercd. Ilence, the upper limit should be 97% by welght.
The deposition amount of the rnlxture o~ the temporary f-iller and the viscoelastlc substance to the shcet ~aries markedly depending UpOII the ;. ,.
' , -, . .
. . . , ~ ~: .
:, .. , ;';' . . .
~ ~33~
ki~nd of sheet, but generally, ~rom 0,5~ by~w~ight up to 70% by ~eight of the mixture based on the weight of the t~l`nnaale ~ eTs or ~ilaments that ~orm the sheet IS applied. Below 0.5% by weight, properties of the product such as abrasion resistance would be lowered. Especially when fibers or Eilaments which are thinned by removing at least one o$ the components by chemical treat-ment or the like are employed in great quantities as the sheet-forming Eibers or ilaments, the deposition amount is preferably at least 1% by weight.
Generally, the upper limit of the deposition amount is 50% by weight to ob-tain the desired hand. It is also advisable to use a greater deposition amount for non-woven abric and a smaller deposition amount for knitted or woven fabric. For non woven fabric, the advisable deposition amount is 10-50%
by weight; for woven or knitted fabric the advisable deposition amount is 1-30% by weight. Various heretofore known methods ma~ be used Eor deposttion of the mixture, such as impregnation, spraying, coating, combinations of these methods and the like.
Next, the sheet-forming fibers or filaments are thinned. The term "thinning" in this specification means to make the fibers thinner by chemical~
thermal or mechanical treatment or the combination of these treatments, or to "fibrillate" the fiber. At times, the fibers or filaments need not all be thinned in the axial direction. Nor is it necessary that the fibers or fila-ments be divided so that they can be seen clearly with the naked eye. Hence, the term "thinning" also includes such a preparatory state from which the fib-ers or Eilaments can be divided by a subsequent simple treatment.
Various hercto-~ore known thinning methods may be uscd as the thinnln~ mathod in the present invention. In -the so cAlled "is1ands-ln~a-sea"
-type ~iber5 or ~ilamen-~s such as ~he "islands ~n~a-sea" type composite fibers or Eilarnents or the polymer blend ~ibers o~ ;eilaments or "shea-th and core~' -.
. .
' ~.
z~
type composite ilaments or fibers treatment o~ the fibers or filaments with a solvent or a decomposition reagent to remove the sea component or the sheath component is most effective. By this method, superfine fibers or filaments are easily produced. As a result, the method is especially effecti~e for producing an extremely soft sheet product. IE -the fibers or filaments are composite fibers or filaments consisting of at least two polymers, each having different swellability to water, to a swelling agent, to other liquids or to heat, separation between the plural components by a swelling treatment or the like by utilizing the difference of swellability is also an effective method.
Adding a foaming agent or the like to the fibers or filaments and foaming them is also recommended so that the fibers or filaments are thinned in the fibril-lated form. The fiber size after thinning is preferably up to 0.8 denier and especially preferably up to 0.3 denier to achieve the desired hand with plia-bility, drapeab~lity and suppleness.
The mode of thinning may be classified into the following two types. rn the first type, a pluralit~ of thinner fibers or filaments are generated by the thinning of the fibers or filaments such as when the "islands-in-a-sea" type composite fibers or filaments, the polymer blend fibers or filaments or the peel-split type fibers or filaments are used or when the bimetal-type composite fibers or filaments are split. In the second type, the flbers or filaments are not divided into a plurality of fibers or filaments even after thinning such as when one component is dissolved or decomposed and r~moved from the sheath and core type composLte fibcrs or filannen-ts or the blm~tal-type Ei~ers or Eilaments. ~enQrally, the ~ormer type is pre~erred.
The vLscoelastic substance is ~hen applied to the -thillned sheet.
The vlco~lastic suhstance may be the same as, o~ di~eererl~ eronl~ the one pre-v:~ollsly applled. As describecl already, howe~er, 1~ the viscoelastic substance ., , ,. .. :
. ;, . ~' .
:. :
- ' . : , ':: ~ -~ 3~3'Z~
used at step (A) is a dry-coagulation type, the viscoelastic substance to be used at step (C) is pre~erabl~ of a wet-coagulat~on type. In either case, it is pre~erred that the viscoelastic substance be dissolved or dispersed in a liquid system which does not easily dissolve the temporary filler. The de-position amount varies markedly depending upon the type of the sheet, bu~ the total deposition amount in steps (A) and (C) is preferably 1-100% of visco-elastic substance by weight based on the weight o the thinnable fiber sheet, more preferably at least 3% by weight. I~ the amount is below the lower limit, tha sheet has low strength and creases occur on the sheet. In the case of a non-woven fabric sheet where the thinnable fibers or filaments occupy the major proportions of the fibers or ~ilaments forming the non-woven fabric, it is preferred that about 15-80% by weight of the viscoelastic substance be applied.
~hen the viscoelastic substance is of the emulsion type and in the usual case, it is useul to use heat-setting ~or making good mechanical pro-perties, heat-setting may be practised in a suitable manner. When the visco-elastic substance is of the wet-coagulation type, it is possible to use known methods which sufficiently coagulate the viscoelastic substance, for example, d~pping into a coagulation bath or the like. All types of known dry-coagulation methods or wet-coagulation methods may be used.
Subsequently, the temporary filler is removed. There are various methods of removing the filler,but the dissolving method is the most common.
A sheet obtained in this manner has extremely good mechanical properties and has a soet hand. I further softening of the sheet is desired, temporary ~iller may be reapplied to the sheet or the tomporary filler may be relocated ~n the sheet, a~ter steps ~A) and ~B~. rrhis is the ~'second method", especially s~ep ~B~ the temporary ~iller is again applied, ik may be the same as, or dieeeren~ erom, -the one applied prev.lously. I~ relocation Oe the temporary , . - 1~ -': ~
,' "
. ' ,. ~:
~4~ 2 ~
filler is chosen, the relocat~on o~ the te~pora~ ller can be efeected by passing the sheet in the solvent o~ the tem~orary~ ~illeT, or by applying mechanical stress to the sheet, such as by pressing the sheet through a mangle or by applying vibration to the sheet while the sheet is being passed through the solvent of the temporary filler. The term "relocation" hereby means that the relative position of the temporary filler to the viscoelastic substance and to the fibers or filaments in the sheet is changed. The mechanism of the ~ncrease in softness in the product due to the relocation of the temporary ~iller has not yet been fully clarified. It is assumed, however, that part of the temporary filler migrates and covers at least part of the viscoelastic substance or at least part of the surface o~ the thinned fibers or filaments.
Where the temporary filler is reapplied, it is not necessary that the filler be applied separatel~. Hence, a mixture of the temporary filler and the viscoelastic material may be applied. At times, the deposition amount need not be increased as described in the case of the relocation of the temporary filler. When greater softness is required, at least 3% by weight, based on the weight o the thinnable fibers or filaments of the sheet, of the temporary filler must be applied at this time. Generally, this de-position amount ls up to about 80% by weight.
Subsequently, the viscoelastic substance is applied. F,xalmples Oe the viscoelastic substance applied at this point are the same as those illus-trated above and the deposition amount is also substantially the same. The total deposition amount Oe the viscoelastic substance is selected from the rang~ ne from I to 100% by weight based on th~ wcight o-~ the thinnabLq Pibers or ei Laments o~ thc sheet. When the viscoelastic substance is of the emulsion type and heat-set~ing is nece~sary Por coagulating the substance in the same way as in th~ ~rst method, heat-settlng may bq practised using standard methods.
. ,5 _ :' , . ~ .
. ' : ~ '. ' :~ ., ,. ~:
3~
When the viscoelastic substance ~s o~ the ~et-coagulation type, su~ficient coagulation ma~ be achieved for example by dipping in a coagulation bath or the like.
Thereafter, the temporary :Elller is removed. The m~thod o~ removing the filler is the same as tha~ illustrated in the first method where the filler is dissolved or decomposed for removal. The sheet obtained in this manner is extremely soft and has good mechanical properties. Morover, the sheet surface is uniform.
The resulting sheet material may be further treated by raising to produce a napped sheet surface whenever necessary. The napping method is not particularly restrictive. Various heretofore known methods such as needle raising and buffing with emery paper, sandpaper or emery cloth may be used.
Where the napping treatment is used, an artificial leather which has good hand and pliant, beautiful surface and is similar to various natural raised leathers such as suede-like raised leather and a vicuna-like raised leather can be produced. The napping treatment also improves the softness.
~t is also possible, whether or not the napping treatment is used, to obtain a grained artificial leather by making a grained surface on at least one sur-eace of the composite sheet.
In accordance with the method o~ the present invention, it becomes poss~ble to produce a composite fibrous viscoelastic material impregnated with a viscoelastic substance which material, though soft, has good mechanical pro-perties such as high abrasion resistance and high tensile strength and which c~n be used ee~cct:Lvely eor produclng clotl~s~shoes, bags, upholstery and s~
~orth~ Tn colnparison with the conventional hlgh-grade shee-t materials, khere-foreJ the sheet maker~al Oe the presenk invontion can be n~ade addlkionally thlnner while mainkaining lts charac~er~ The presellt lnvention ls capable of - 16 _ ' 3~
eliminatIng the problems with the con~entional sheet materials in that their strength is markedly reduced and practical utility is lost when the thickness of the sheet material is reduced. The method of the present invention makes it possible to put a thinner sheet material into practical application Though several examples o~ the present invention will be illustrated in the following paragraphs, the present invention is in no way restricted by these exa~tples.
The following polyurethanes were used in Examples l through 3 and Comparati~e Example l.
(A) E s ~ e (1) high-molecular weight polyol component: conjoint use of polyoxy-propylene glycol ~molecular weight approx. 1,000) and polyoxypropylenetriol Cmolecular weight approx. 1,000~ in a weight ratio of 75:25.
~2) organic diisocyanate component: 2,4-tolylene diisocyanate ~3) chain-extending agent: 4,4'-diaminodicyclohexylmethane ~B) Solution type polyurethane ~1~ high-molecular weight polyol component: conjoint use of polycaprol-actone diol ~molecular weight approx. 2,000) and polytetramethylene ether glycol ~molecular weight approx. 2,000) in a weight ratio of 30:70.
~xample 1 A web was ~o:rmed from "islands-in-a-sea" type composite l'~bers cetnsistlng of polyethylene terephthalate as the island component and poly-styrene containing 20 mol % of 2-ethylhexyl-acrylate copolymerized therewith as the sea component and having a weight ratio of 50:50 between the island colnpctnctnt and ~hc sefl component and slze Oe 4.5d ~the number of islands ~ 16, ~he size Oe each islancl component ~ 0.14d~ and was needle-punchecl to yield a non-woven ~abric. Thereaeter, ~he non-wo~en eabric was trea~cld w;th hot water ;
, .. ; ., 2~
at 80C reducing thc sur~ace area by 23%. The weight o~ this non-woven fa~ric was 630 g/m2. The non-woven fabric was then impregnated with a mixed solution of 5% by weight of polyvinyl alcohol as tlle ternporary filler and 5% by weight of a polyurethane emulsion as the viscoelast~c substance and 90% by weight of water, and was dry-coagulated at 100C for 10 minutes. The deposition amount o~ the mixture ~as 11% by weight on the basis Oe the "island-in-a-sea"
type composite ibe~s. Thereafter, the sea component was removed using trich-loroethylene, thereby thinning the fibers. The removal ratio was 98.5% by weight. After heat treatment at 150C for 10 minutes, a 7 wt. % polyurethane solution ~solvent = dimethylformamide) was ~urther applied and the ~ibers were wet-coagulated in water at room temperature, then dipped into hot water at 80C and passed through a mangle to remove the polyvinyl alcohol. This procedure of dipping into hot water and passing through a mangle was repeated 15 times.
The total deposition amount of the polyurethane thus applied was ~1% h~ weight calculated as the solid content on the basis of the thinned f~bers. The resulting sheet was sliced into two thinner sheets. Each sheet was buffed to form a napped surface and then dyed to produce an artificial leather. The resulting products were rich in softness, had dense nap and good mechanical properties. The abrasion resistance was 577 c~cles and the tear strength was l.Okg in the transverse direction and 1.2kg in the longitudinal direction. The abrasion resistance was measured by causing wear on the surface of the sheet using a rotary nylon brush and counting the number of rotations roqulred to break the shee~, The tear strength was rneasured in accordance Wi~]l meth~d C s~lp-llated ln ~rs L-1079.
Con3~arat:lve~
__ The shrunlc fabric as in Example 1 was treated with a 10% polyvinyl '' alcohol solutlon (PVA solution), and dried. Then the sea component of the fiber was removed with trichloroeth~lene as in Example 1. A polyurethane solution (15% concentration) using dimethylformam~de CDMF) as the solvent was then applied. We~ coagulation of the polyurethane and removal of the PVA were carried out as in Example 1. The deposltion amount of the polyurethane was 48% by weight on the basis of the thinned fibers. Slicing~ buffing and dyeing were then carried out. The product ~as relatIvely soft ~63 mm in ~he long-itudinal direction and 45 mm in the transverse direction as measured in accor-dance with Clark method stipulated by JrS L-1079). However, the properties of product were low as the abrasion resistance was 225 cycles and the tear strength was 0.5kg in the transverse direction and 0.7kg in the longitudinal direction.
Example 2 A web was formed from "islands-in-a-sea" type composite fibers con-sisting of n~lon 6 as the island component and polystyrene containing 18 mol %
of 2-ethylhexyl-acrylate copolymerized there~ith as the sea component and having an island-to-sea ratio of 55t~5 ~by weight), size of 5.5d, the number o~ islands of 36 and a size Oe 0.08d for each island component, and was needle-punched to ~leld a non-woven fabric. The resulting non-woven fabric was treated wi.th hot water at 80C. reducing the sureace area by 29.5%. The weight o~ this felt was 595 g/m2. The felt was then impregnated with a mixed solution consisting oE 7% by welght of polyvinyl alcohol ~PVA~, 7% by weight of a polyurethane emulsion and 86% by weight water. It was then dry-coagulated at 100C for 10 minutes. Tlle total depos3tion amount as the sum Oe PV~ and polyure-thane was 15% by weight on the basis Oe the welghk oE tlle thinnable fibers.
Nex~ tlle sea component was removed with trichlorc)ethylerle to thln th~ $1bers. The removal ra-tio was 98,7% b~ ~elgllt. A~ter heat-settln~ at 150C
:
33~
for 10 minutes, the sheet was impregnated with a dimeth~lformamide solution (DMF solut~on) of polyurethane (12 wt. % concent~atlon). The polyurethane was then wet-coagulated with the water at room temperature and the PVA was removed as in Example 1. The total deposition amount of the polyurethane emulsion and the polyurethane solution was 38.5% by weight calculated as the solid content on the basis of the thinned fibers. The sheet was sliced into two thinner sheets and the surface of each sheet was buffed, napped and then dyed to produce a suede-like artiflcial leather. The product was very soft (as soft as 58 mm in the longitudinal direction and 45 mm in the tTansverse direction in accor-dance with Clark method stipulated by JlS L-1079) and had an excellent nap. In addition, the product had enhanced properties such as abrasion resistance of 1,235 cycles and tear strength of 2.4kg in the longitudinal direction and 1.5kg in the transverse direct~on.
Example 3 The thinned fiber fabric of Example 2 treated wlth PVA and emulsion polyure~hane was passed through water at 60C for about one minute and then was passed through a mangle. This procedure of passing through the water and the mangle was repeated twice to relocate the PVA. Thereafter, the felt was dried.
The PVA decreased 3% by weight.
The ~elt was further :Lmpregnated with a 16 wt. % DMP solution of polyurethane and wet-coagulated with water at room temperature and the PVA was removed in the same way as in ~ample 1. The total deposition amount of the emulsion-type polyurethane and the solutlon-type polyurethane was 41% by weight calculated flS khe solid content on the basis o~ the thinned fibers. The sheet WflS sllcecl ln-to two th:lnner sheets, blleee(l and dyed to produce suede-llke ar-ki~:Lclfll Ieather. 'rhe product was ri.ch ln so:etness (as soet as 38 mm :In -the longitudinal cl~rectlon and 28 mnl ln the transverse dlrectlon ln aecord~mce wlth "
, ~, :' , 3 ~
the metllod st.ipulated by JIS-1079) and had a ~ne, beauti~ul n~p and good mechanical properties. The abrasion resis~nce was 1,033 cycles and the tear strength was 2.6kg in the longi~udinal direction and 1.9kg in ~he transverse direction.
Claims (30)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of producing a soft sheet material containing thinned fibers or filaments and a viscoelastic substance, which method comprises:
(A) applying a mixture of a viscoelastic substance and a temporary filler to a sheet material containing thinnable fibers or filaments;
(B) thinning the thinnable fibers or filaments of said sheet material;
(C) applying a viscoelastic substance; and (D) removing said temporary filler.
(A) applying a mixture of a viscoelastic substance and a temporary filler to a sheet material containing thinnable fibers or filaments;
(B) thinning the thinnable fibers or filaments of said sheet material;
(C) applying a viscoelastic substance; and (D) removing said temporary filler.
2. A method of producing a soft sheet material containing thinned fibers or filaments and a viscoelastic substance, which method comprises:
(A) applying a mixture of a viscoelastic substance and a temporary filler to a sheet material containing thinnable fibers or filaments;
(B) thinning the thinnable fibers or filaments forming said sheet material;
(B') applying temporary filler to said sheet material;
(C) applying a viscoelastic substance; and (D) removing said temporary filler.
(A) applying a mixture of a viscoelastic substance and a temporary filler to a sheet material containing thinnable fibers or filaments;
(B) thinning the thinnable fibers or filaments forming said sheet material;
(B') applying temporary filler to said sheet material;
(C) applying a viscoelastic substance; and (D) removing said temporary filler.
3. A method of producing a soft sheet material containing thinned fibers or filaments and a viscoelastic substance, which method comprises:
(A) applying a mixture of a viscoelastic substance and a temporary filler to a sheet material containing thinnable fibers or filaments;
(B) thinning the thinnable fibers or filaments forming said sheet material;
(B') relocating said temporary filler applied at stop (A) within said sheet material;
(C) applying a viscoelastic substance; and (D) removing said temporary filler.
(A) applying a mixture of a viscoelastic substance and a temporary filler to a sheet material containing thinnable fibers or filaments;
(B) thinning the thinnable fibers or filaments forming said sheet material;
(B') relocating said temporary filler applied at stop (A) within said sheet material;
(C) applying a viscoelastic substance; and (D) removing said temporary filler.
4. The method according to Claim 1, 2 or 3 wherein a napping treat-ment is effected after said step (D).
5. The method according to Claim 1, 2 or 3 wherein said thinnable fibers or filaments are "islands-in-a sea" type fibers or filaments having at least four island components of up to 0.8d.
6. The method according to Claim 1, 2 or 3 wherein said thinnable fibers are "islands-in-a-sea" type composite fibers or filaments containing at least 8 island components of up to 0.3d.
7. The method according to Claim 1, 2 or 3 wherein said thinnable fibers or filaments are sheath and core type composite fibers or filaments.
8. The method according to Claim 1, 2 or 3 wherein said thinnable fibers or filaments are split-type composite fibers or filaments.
9. The method according to Claim 1, 2 or 3 wherein said sheet material containing said thinnable fibers of filaments is a fabric selected from the group consisting of a non-woven fabric, a woven fabric, a knitted fabric and a combination sheet thereof.
10. The method according to Claim 1, 2 or 3 wherein said sheet material containing said thinnable fibers or filaments is a non-woven fabric.
11. The method according to Claim 1, 2 or 3 wherein said viscoelastic substance is a polymer substance having elongation at break of at least 300%
and stress at 100% elongation of not greater than 200 kg/cm2.
and stress at 100% elongation of not greater than 200 kg/cm2.
12, The method according to Claim 1, 2 or 3 wherein said viscoelastic substance Is polyurethane.
13. The method according to Claim 1, 2 or 3 wherein said viscoelastic substance is a polyurethane solution formed by dissolving in a water-miscible organic solvent a substantially linear block polyether-polyester type polyure-thane in which polytetramethylene ether glycol of a molecular weight of at least about 800 and polycaprolactone diol of a molecular weight of at least about 800 are bonded to the organic diisocyanate residues and to the diamine residues by urethane bonds and by urea bonds and the weight ratio between the polytetra-methylene ether glycol and polycaprolactone diol is in the range of about 50/50 to about 90/10.
14. The method according to Claim 1, 2 or 3 wherein said viscoelastic substance is a polyurethane emulsion consisting of water and polyurethane ob-tained by reacting an NCO group-excessive prepolymer between a polyol and a polyisocyanate with a chain-extending agent in the presence of water whereby the polyol consists of (A) polyester polyol of a molecular weight of 500 to 3,000, (B) polyoxyalkylene (C2 - C3) polyol of a molecular weight of 200 to 5,000 and, if necessary, (C) polyol of a low molecular weight, the average mixed molecular weight of the mixture (A)+(B)+(C) is 1,000 to 3,000 and the weight ratio (A/B+C) is from 10 to 0.5.
15. The method according to Claim 1, 2 or 3 wherein said viscoelastic substance to be employed at said step (A) is a three-dimensional crosslinked polymer.
16. The method according to Claim 1, 2 or 3 wherein said viscoelastic substance to be employed at said step (A) is a viscoelastic substance capable of being dry coagulated.
17. The method according to Claim 1, 2 or 3 wherein said viscoelastic substance to be employed at said step (C) is a viscoelastic substance capable of being wet-coagulated.
18. The method according to Claim 1, 2 or 3 wherein said temporary filler is a water-soluble polymer compound.
19. The method according to Claim 1, 2 or 3 wherein said temporary filler is at least one temporary filler selected from the group consisting of poly-vinyl alcohol, carboxymethylcellulose and starch.
20. The method according to Claim 1, 2 or 3 wherein the mixing ratio of said viscoelastic substance in said mixture of said viscoelastic substance and said temporary filler is from about 3 to 95% by weight on the basis of the weight of said mixture.
21. The method according to Claim 1, 2 or 3 wherein the mixing ratio of said viscoelastic substance in said mixture of said viscoelastic substance and said temporary filler is from about 5 to 93% by weight on the basis of the weight of said mixture.
22. The method according to Claim 1, 2 or 3 wherein the deposition a-mount of said mixture of said viscoelastic substance and said temporary filler is such that said viscoelastic substance is about 0.5% to 70% by weight on the basis of the weight of said thinnable fibers or filaments forming said sheet material.
23. The method according to Claim 1, 2 or 3 wherein the deposition a-mount of said mixture of said viscoelastic substance and said temporary filler is such that said viscoelastic substance is from about 1% to 50% by weight on the basis of the weight of said thinnable fibers or filaments forming said sheet material.
24. The method according to Claim 1, 2 or 3 wherein the total deposition amount of said viscoelastic substance is in the range of from about 1% by weight to 100% by weight on the basis of the weight of said thinnable fibers or fila-ments forming said sheet material.
25. The method according to Claim 1, 2 or 3 wherein said thinnable fibers or filaments are "islands-in-a-sea" type fibers or filaments and thinning of said thinnable fibers or filaments is effected by treating said "islands-in-a-sea" type fibers or filaments with a solvent decomposition agent for said sea component and removing said sea component.
26. The method according to Claim 1, 2 or 3 wherein said thinnable fibers or filaments are sheath and core type fibers or filaments and thinning of said thinnable fibers or filaments is effected by treating said sheath and core type fibers or filaments with a solvent decomposition agent for said sheath and removing said sheath.
27. The method according to Claim 1, 2 or 3 wherein said thinnable fibers or filaments are split-type composite fibers or filaments and thinning of said thinnable fibers or filaments is effected by splitting said split-type composite fibers or filaments by treatment with a swelling agent.
28. The method according to Claim 2 wherein the deposition amount of said temporary filler which is applied further at step (B') is from about 3%
by weight to 80% by weight on the basis of the weight of said thinnable fibers or filaments forming said sheet material.
by weight to 80% by weight on the basis of the weight of said thinnable fibers or filaments forming said sheet material.
29. The method according to Claim 3 wherein the relocation of said tem-porary filler is effected by applying a solvent for said temporary filler to said sheet material and then applying mechanical stress to said sheet.
30. The method according to Claim 1, 2 or 3 wherein the removal of said temporary filler is effected by dissolving said temporary filler with a solvent thereof.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000373849A CA1159320A (en) | 1981-03-25 | 1981-03-25 | Method for producing soft sheet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000373849A CA1159320A (en) | 1981-03-25 | 1981-03-25 | Method for producing soft sheet |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1159320A true CA1159320A (en) | 1983-12-27 |
Family
ID=4119542
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000373849A Expired CA1159320A (en) | 1981-03-25 | 1981-03-25 | Method for producing soft sheet |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1159320A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113549186A (en) * | 2021-08-31 | 2021-10-26 | 宁波赫革丽高分子科技有限公司 | Hydrolysis-resistant microfiber facing fabric polyurethane resin |
-
1981
- 1981-03-25 CA CA000373849A patent/CA1159320A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113549186A (en) * | 2021-08-31 | 2021-10-26 | 宁波赫革丽高分子科技有限公司 | Hydrolysis-resistant microfiber facing fabric polyurethane resin |
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