CA1083799A - Process for the manufacture of non-woven structures - Google Patents
Process for the manufacture of non-woven structuresInfo
- Publication number
- CA1083799A CA1083799A CA297,260A CA297260A CA1083799A CA 1083799 A CA1083799 A CA 1083799A CA 297260 A CA297260 A CA 297260A CA 1083799 A CA1083799 A CA 1083799A
- Authority
- CA
- Canada
- Prior art keywords
- web
- border
- zone
- folded
- woven
- 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
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21F—WORKING OR PROCESSING OF METAL WIRE
- B21F45/00—Wire-working in the manufacture of other particular articles
- B21F45/16—Wire-working in the manufacture of other particular articles of devices for fastening or securing purposes
- B21F45/18—Wire-working in the manufacture of other particular articles of devices for fastening or securing purposes of slide fastener elements
-
- A—HUMAN NECESSITIES
- A44—HABERDASHERY; JEWELLERY
- A44B—BUTTONS, PINS, BUCKLES, SLIDE FASTENERS, OR THE LIKE
- A44B19/00—Slide fasteners
- A44B19/42—Making by processes not fully provided for in one other class, e.g. B21D53/50, B21F45/18, B22D17/16, B29D5/00
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D53/00—Making other particular articles
- B21D53/46—Making other particular articles haberdashery, e.g. buckles, combs; pronged fasteners, e.g. staples
- B21D53/50—Making other particular articles haberdashery, e.g. buckles, combs; pronged fasteners, e.g. staples metal slide-fastener parts
- B21D53/52—Making other particular articles haberdashery, e.g. buckles, combs; pronged fasteners, e.g. staples metal slide-fastener parts fastener elements; Attaching such elements so far as this procedure is combined with the process for making the elements
Abstract
PROCESS FOR THE MANUFACTURE OF NON-WOVEN STRUCTURES
Abstract of the disclosure:
In the manufacture of non-woven fabrics waste material is avoided by determining the distribution of the weight per square unit of both border zones of a non-woven and by folding there-after a part of the thinner border zone toward the inner part so that the resulting non-woven has a uniform distribution of weight per square unit. Especially in the case of non-woven fabrics made from little extensile material or having border zones which shall not be stretched, the web is guided at an angle about in the middle of the folding zone, the angle being inclined towards that level towards which the border zone is folded.
There are obtained non-woven fabrics with very uniform di-stribution of weight per square unit.
Abstract of the disclosure:
In the manufacture of non-woven fabrics waste material is avoided by determining the distribution of the weight per square unit of both border zones of a non-woven and by folding there-after a part of the thinner border zone toward the inner part so that the resulting non-woven has a uniform distribution of weight per square unit. Especially in the case of non-woven fabrics made from little extensile material or having border zones which shall not be stretched, the web is guided at an angle about in the middle of the folding zone, the angle being inclined towards that level towards which the border zone is folded.
There are obtained non-woven fabrics with very uniform di-stribution of weight per square unit.
Description
~837g~
The present invention is an improvement in a process for the manufacture of non-woven structures in which a part of the border zones of the non-woven is folded toward the inner part after a slight pre-consolidation and prior to the main consoli dation of the sheet. This process is applicable especially to the manufacture of non-woven fabrics made from filaments and spunbonded fabrics. It makes it possible for the manufac-turer to avoid waste material as a consequence of trim~.ing the border zones of non-woven fabrics.
lQ In the manufacture of spunbond fabrics, for example, fresh-ly spun filaments are first suhmitted to draw~ng with gas jet, and are thereafter spread across a moving surface by means of electrostatic charge or of stationary or movable deflectors of of other devices to form a non-woven fabric~ Processes of this kind are disclosed, for example in German Offenlegungs-schrift No. 24 60 755.
In order to obtain the desired width of a non-wo~en ab~ic, several non-woven websorstrips issueing from the individual deposlt-ing units are laid down in parallel manner in overlapping posi-tion. ~n this kind of laydown there are formed border zones with reduced weight per square unit in comparison with the cen-tral zones, if no measures are undertaken to influence those parts which form the border zones in a different manner than those which form the central part.
German Auslegeschrift No. 16 35 585 disclosesa process ~or the preparation of non-woven webs o continuous f~laments, whI:ch comprises forwarding a number of untwisted strands o~ colitinuous filaments by an adequate number of stationary jets, spreadin~
2q the filaments by electrosta.ic chaxge and deposIt~ng them ~ n a ,, ~837~9 moving collec~ing surface in the form of overlapping ribbons to ' form a wide non-wo~en structure. This publication also teaches that adjacent strips must generally overlap by 50 %1 67 ~, 75 %
or 80 % in order to form a uniform non-woven structure. This publication moreover mentions that for removing both border zones with low weight per square unit, the non-woven webs must be trimmed the more the larger the degree of o~erlapping. For webs of rectangular cross-secti.on and a degree of overlapping of 50 %, the total quantity or both border zones which must be cut 1~ off in order to leave a uniform utiiizable web, corresponds to the output of one jet. With a degree of overlapping of 67 %, the quantity to be cut off corresponds to the output of two jets, with a degree of overlapping of 75 %Jto the output of three jets and with a degree of overlapping of 80 %,to the output of four ~ets.
Furthermore, the smaller the width of a non-woven web, the higher the percentage of material to be cut off.
The waste material obtained as a consequence of cutting the border zones of the non-woven web is uneconomic.
20Possibilities of reducing the ~uantity of material to be .
cut off, consist in influencing the ~ilaments to be deposited in the depositing positions near the border by means of guide plates, pegs or air nozzles or by predetermined direct7~oning of the suctionining air at the perforated laydown belt in a manner to make them arrange uniformly also in the border zones so that there is obtained the Same weight pex sq-uare unit in These zones as in the central.zones. This method, however, ~ives ~ise to strUctures in the de~osited non-~oVen web in the border 29 zone which diffex fxo~ that in the central part ~hich has not :- 3 . ' : '; ' - :, . .
.
. ~ :
` 1~83799 - been influenced. It is quite natural that the quality of the web is deteriorated by this measure since the properties of the web in the border zones are different from those in the central part. Furthermore, these measures insure no sufficiently rec-tilinear borders and even in this case it cannot be avoided to cut off a certain part of the border zone.
The object of the present invention was, consequently, to provide a process which does not show these disadvantage~- and which makes it possible to transfer completely the filamentary 1 a material employed into utilizable non-woven web of hi~h quali-ty.
This problem could be solved by the present invention by determining the basis weight distribution I which is a measure of weight per unit area and ordinarily expressed in terms of grams per square metertof the border zones and thereatex fold-ing a part of the border zone toward the central part such that the resulting web has a uniform basis weight diatribution.
Optionally the web is slightly consolidated prior to folding the borders to the center for example by calendering.
The width of the part of the border zone which is folded inside depends on the mass distribution in this zone. In order to determine the width, the basis weight distribution in the border zone must be measured and thereafter a part o the border zones it folded towards the center such that the result-ing web has a uniform basis weight distribution.
If in the ideal case the basis weight in the border zones diminishes in linear manner to the edges, the width of the part of the bo~der zone to be folded to ~he center corresponds 29 to half the width of the border zone.
_ 4 _ ' ~
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~ ~37~
In practice this ideal case is not given very often. How-ever, it has become apparent surprisingly that even in those cases where the basic weight distribution in the border zone deviates from this ideal distribution, very good results can still be obtained, that is to say that the basis weight uni-formity which is usually given in the central part of non-woven fabrics, can be achieved with the process of the inven-tion also in the border zones.
By folding the border zone of the web to the center, not only the basis weight of this zone approaches that of the to-tal web, but moreover the edges of the web are straightened surprisingly.
Furthermore it was found surprisingly that frequently a second consolidation of the folded web by calendering suffices ~5 to counteract a subse~uent delamination of the ~olded border zone.
The border zones are preferably folded towards the center continuously while the non-woven web moves in the direction of its longitudinal axis.
When the web to be folded in its border zone consists of little extensile materlal or when the border zone should not or must not be stretched during the folding process , the web is guided, according to the invention, about in the middle o the zone, where the folding process takes place,in deviation from the linear direction~at an angle, this angle being inclin-ed towards that level towards which the folding of the border zones towards the center takes place, that is to say since the border zones of the web are in most cases folded upwards in 29 practice, the total web is inclined upwards.
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. . : .
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The angle by which the guidance of the web through the fold-ing zone deviates from the linear direction is
The present invention is an improvement in a process for the manufacture of non-woven structures in which a part of the border zones of the non-woven is folded toward the inner part after a slight pre-consolidation and prior to the main consoli dation of the sheet. This process is applicable especially to the manufacture of non-woven fabrics made from filaments and spunbonded fabrics. It makes it possible for the manufac-turer to avoid waste material as a consequence of trim~.ing the border zones of non-woven fabrics.
lQ In the manufacture of spunbond fabrics, for example, fresh-ly spun filaments are first suhmitted to draw~ng with gas jet, and are thereafter spread across a moving surface by means of electrostatic charge or of stationary or movable deflectors of of other devices to form a non-woven fabric~ Processes of this kind are disclosed, for example in German Offenlegungs-schrift No. 24 60 755.
In order to obtain the desired width of a non-wo~en ab~ic, several non-woven websorstrips issueing from the individual deposlt-ing units are laid down in parallel manner in overlapping posi-tion. ~n this kind of laydown there are formed border zones with reduced weight per square unit in comparison with the cen-tral zones, if no measures are undertaken to influence those parts which form the border zones in a different manner than those which form the central part.
German Auslegeschrift No. 16 35 585 disclosesa process ~or the preparation of non-woven webs o continuous f~laments, whI:ch comprises forwarding a number of untwisted strands o~ colitinuous filaments by an adequate number of stationary jets, spreadin~
2q the filaments by electrosta.ic chaxge and deposIt~ng them ~ n a ,, ~837~9 moving collec~ing surface in the form of overlapping ribbons to ' form a wide non-wo~en structure. This publication also teaches that adjacent strips must generally overlap by 50 %1 67 ~, 75 %
or 80 % in order to form a uniform non-woven structure. This publication moreover mentions that for removing both border zones with low weight per square unit, the non-woven webs must be trimmed the more the larger the degree of o~erlapping. For webs of rectangular cross-secti.on and a degree of overlapping of 50 %, the total quantity or both border zones which must be cut 1~ off in order to leave a uniform utiiizable web, corresponds to the output of one jet. With a degree of overlapping of 67 %, the quantity to be cut off corresponds to the output of two jets, with a degree of overlapping of 75 %Jto the output of three jets and with a degree of overlapping of 80 %,to the output of four ~ets.
Furthermore, the smaller the width of a non-woven web, the higher the percentage of material to be cut off.
The waste material obtained as a consequence of cutting the border zones of the non-woven web is uneconomic.
20Possibilities of reducing the ~uantity of material to be .
cut off, consist in influencing the ~ilaments to be deposited in the depositing positions near the border by means of guide plates, pegs or air nozzles or by predetermined direct7~oning of the suctionining air at the perforated laydown belt in a manner to make them arrange uniformly also in the border zones so that there is obtained the Same weight pex sq-uare unit in These zones as in the central.zones. This method, however, ~ives ~ise to strUctures in the de~osited non-~oVen web in the border 29 zone which diffex fxo~ that in the central part ~hich has not :- 3 . ' : '; ' - :, . .
.
. ~ :
` 1~83799 - been influenced. It is quite natural that the quality of the web is deteriorated by this measure since the properties of the web in the border zones are different from those in the central part. Furthermore, these measures insure no sufficiently rec-tilinear borders and even in this case it cannot be avoided to cut off a certain part of the border zone.
The object of the present invention was, consequently, to provide a process which does not show these disadvantage~- and which makes it possible to transfer completely the filamentary 1 a material employed into utilizable non-woven web of hi~h quali-ty.
This problem could be solved by the present invention by determining the basis weight distribution I which is a measure of weight per unit area and ordinarily expressed in terms of grams per square metertof the border zones and thereatex fold-ing a part of the border zone toward the central part such that the resulting web has a uniform basis weight diatribution.
Optionally the web is slightly consolidated prior to folding the borders to the center for example by calendering.
The width of the part of the border zone which is folded inside depends on the mass distribution in this zone. In order to determine the width, the basis weight distribution in the border zone must be measured and thereafter a part o the border zones it folded towards the center such that the result-ing web has a uniform basis weight distribution.
If in the ideal case the basis weight in the border zones diminishes in linear manner to the edges, the width of the part of the bo~der zone to be folded to ~he center corresponds 29 to half the width of the border zone.
_ 4 _ ' ~
:, ~ . , , ;: .
~ ~37~
In practice this ideal case is not given very often. How-ever, it has become apparent surprisingly that even in those cases where the basic weight distribution in the border zone deviates from this ideal distribution, very good results can still be obtained, that is to say that the basis weight uni-formity which is usually given in the central part of non-woven fabrics, can be achieved with the process of the inven-tion also in the border zones.
By folding the border zone of the web to the center, not only the basis weight of this zone approaches that of the to-tal web, but moreover the edges of the web are straightened surprisingly.
Furthermore it was found surprisingly that frequently a second consolidation of the folded web by calendering suffices ~5 to counteract a subse~uent delamination of the ~olded border zone.
The border zones are preferably folded towards the center continuously while the non-woven web moves in the direction of its longitudinal axis.
When the web to be folded in its border zone consists of little extensile materlal or when the border zone should not or must not be stretched during the folding process , the web is guided, according to the invention, about in the middle o the zone, where the folding process takes place,in deviation from the linear direction~at an angle, this angle being inclin-ed towards that level towards which the folding of the border zones towards the center takes place, that is to say since the border zones of the web are in most cases folded upwards in 29 practice, the total web is inclined upwards.
-.. ~ . . ~: . :
~-. ~: .. `' ' :
. . : .
~,~ . . , 379~ :
The angle by which the guidance of the web through the fold-ing zone deviates from the linear direction is
- 2 arc sin BR
L
BR denoting the width of the individual border zones of the web and L the length of the web within the :Eolding zone. As a gene-ral rule the angle will not exceed 70 to 90 C, an angle parti- : -cularly preferred corresponding to the formula a ~ 2 arc sin R
When the material of the web is very elastic and when the border zones of the web are very narrow, it may be operated at smaller angles or a guidance of the web at an angle.in the folding zone may even be dispensed with.
After having folded the border zones of the non-wo~en web, the latter is consolidated. For the final consolidat.ion of the web, further methods may be employed, in addition to calender-ing, for example the consolidation by means of binding agents or by needling.
The web prepared according to the invention shows a very good uniformity until the edge of the border zone and unobjec-tionably rectilinear edges. For these reasons, trimming of the border zones may be dispensed with and there is no waste material.
The invention will be illustrated, by way of example, in the accompanying d.rawings and in the description referring to the drawings.
In the drawings 29 Figure 1 represents a ~chematic cross section in vertical direc-~ ' . ' ' ; , ' ~ ' :
,, ',:
~0~379g tion to the longitudinal axis of a single web of a single depositing unit of a plant for the manufacture of spunbond fabrics, which web has been deposited on a collecting surface (not shown);
Figure 2 is in four parts, i.e. a, b, c, and d, to show cross-sections of non-woven fabrics which are composed of several webs deposited one beside another as well as in an overlapping position;
Figure 3 represents a cross-section of a web prepared initially like that shown in Figure 2b and with the border zones folded towards the center;
Figure 4 represents steps a, b, c, d, and e of a process of folding a border zone of a web using schematic cross-sections in vertical direction to the longitudinal axis of the web;
Figure 5 is a flow scheme in elevation of the process of fold-ing the border zones;
Figure 6 is a diagrammatic representation of the basis weight distribution of the web with the borders not being folded, transversely to the direction of run of the web;
Figure 7 is a diagrammatic representation of the basis weight distribution of the web with the borders folded accord-ing to the invention;
Figure 8 is a diagrammatic representation of the basis weight distribution in the border zone of a further web with the border zone not being folded; and Figure 9 is a diagrammatic representation of the web with the border zones b~ing folded according to -the invention.
~ 7 _ .
.
379g R~ference is first made to Figure 1, which shows a cross-section transversely to the longitudinal axis of a web 1 issuing from a single depositing unit.
` \ . , - .
, ~: ' ' " , . .
. . - .
.
,, . :, ' ` . ' '' , . :
, ., .: .:
, 1~83799 Several webs or strips of non-woven fabrics issuing from single depositing units must be deposited one beside the other overlappingly, for the preparation of wide non-woven structures. Possibilities of arranging strips of this type within the structure of non-woven fabrics of relatively great width are shown in Figure 2, parts a to d. In these repre-sentations the adjacent strips within the structure of the non-woven fabric touch only at their surface. However, as it has been mentioned particularly in German Offenlegungsschrift No.
24 60 755, the strips arranged one upon the other may also penetrate each other by their layers of individual filaments or of filament bundles. Those zones of the non-woven fabrics which are located outside of both dotted vertical lines 2 constitute the border zones of the fabrics. They have a lower basis weight than the central zones of the non-woven fabrics of uniform basis weight or their basis weight is reduced to the border. The arrows visible in Figure 2c at regular inter-vals mean to say that the basis weight decreases from the center to the border in linear manner. -Non-woven fabrics of different structure, the basis weight of which likewise decreases to the border, are further-more known or imaginable. Fabrics of this kind may also be used for the process of the invention.
-~ Figure 3 represents the non-woven fabric of Figure 2b with the border zones being folded.
Figure ~ is a cross-sectional view in vertical direction with respect to the longitudinal axis of the non-woven fabric of the individual stages of the process of folding the border zones. Figure 4a shows the fabric 3 with the border zones not . . ~ . . ~ .
. .
,. . ." ' ` , ' ' '" ':
.': . , ' ' ' - `, , .,, '', ~. ~' . .
.. . . . . . :: . .:. ; . .. .
- \
1~D8379~3 being folded and with the calender rolls ~ and 5. The border zone of the fabric to be folded is forwarded to the first bar 6, which lifts the border zone 7 of ~he fabric.
Further bars are arranged at equal distances (Figure 4c, d), which further lift the border,zone and press it inwards and downwards or fold it. The fabric with the border zone being folded is thereafter drawn off by the pair of rolls 8 and 9 or is calendered as it is illustrated in Figure 4e.' Figure 5 is a side ~iew of the folding process~ The un folded non-woven fabric 3 is forwarded in the direction of the arrow to the folding zone by the calender rolls 4 and 5. The numerals 6 denote the folding bars, 7 the border to be folded and 10 a deflection bar. The length of this de~lection bar corresponds approximately to the desired width of the non-w,,oyen fabric with the border zones being folded. The deflection b~r is located approximately in the middle of the ~olding zone, the latter being limited by two draw-off rolls 8 and 9 of the calen-der. In the course of the folding process the web is deviated by the angle a around the bar 1~. Thus the foldlng process is facilitated. The web wi~h the borders being folded 3 is then drawn-off and calendered by the rolls 8 a,nd 9, passed through a needlin~ device 11 and wound u~ on a devicewhich is not shown.
The method of folding the borders and the device employed in the present invention are given by way o~ example only.
The following example illustrate tne invention:
E X ~ M P L E 1: ' ~ilaments were ~roduced f,rom molten polyethylene terephtha-late by two spinn~rets each having seventy holes, the filaments 29 were collected to ~orm two bundles and stretched by air n~zzles.
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. .
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1~83799 The titer of the individual filaments was about 8 dtex.
Either filament bundle accelerated down by the air nozzles was forwarded to a rotating deflection device, by which they were deposited upon a collection sufrace moving with constant velocity~to form a strip. Both overlapping strips formed a non-woven fabric which was thereafter pre-consolidated by ca-lendering at 140 C. At an arbitrarily selected point of the web, the basis weight gradient shown in Figure 6 was measured photometrically in transverse direction with respect to the direction of movement of the web. In the diagram D denotes the weight per square meter, X denotes the coordinate trans- -versely with respect to the direction oE run of the web. As it can be seen from the curve in Figure 6~the weight per square meter D of the web ranges between 0 g at the border of the web and 150 g near the center of ~le web.The total width of the web was 72 cm. By the devices shown in Figures ~ and 5 14.~ cm of . .
the left border zone and 12.6 cm of the right one of the web were folded into the center. Thereafter the web was submitted to a second consolidation process by calendering at 140 ~.
The basis weight of the web with the borders being folded, de-termined at the same position, was in the range of from 100 g per square meter and 162 g per square meter, the average basis weight being about 137 g per square meter (cf. Figure 7). The web thus formed had a uniform structure and linear edges which had not to be trimmed and thus there was no waste material.
E X A M P L E 2:
.
Figure ~ shows the basis weight gradient of the border of a further non-woven fabric. After having folded the border 29 zone according to the invention and after having consolidated .. , : . ., . . .
.
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the non-woven fabric a second time, the basis weight gxadient shown in Figure 9 was measured. In this case, the basis weight was measured at two positions of the non-woven fabric.
This non-woven fabric had also a uniform appearance and a smooth border so that trimming of the borders could be dispens-ed with.
.. , . : . .. . . .......................................... .. .
., , , . , : :-, , .. . , ~ ~, :. . ,: .
L
BR denoting the width of the individual border zones of the web and L the length of the web within the :Eolding zone. As a gene-ral rule the angle will not exceed 70 to 90 C, an angle parti- : -cularly preferred corresponding to the formula a ~ 2 arc sin R
When the material of the web is very elastic and when the border zones of the web are very narrow, it may be operated at smaller angles or a guidance of the web at an angle.in the folding zone may even be dispensed with.
After having folded the border zones of the non-wo~en web, the latter is consolidated. For the final consolidat.ion of the web, further methods may be employed, in addition to calender-ing, for example the consolidation by means of binding agents or by needling.
The web prepared according to the invention shows a very good uniformity until the edge of the border zone and unobjec-tionably rectilinear edges. For these reasons, trimming of the border zones may be dispensed with and there is no waste material.
The invention will be illustrated, by way of example, in the accompanying d.rawings and in the description referring to the drawings.
In the drawings 29 Figure 1 represents a ~chematic cross section in vertical direc-~ ' . ' ' ; , ' ~ ' :
,, ',:
~0~379g tion to the longitudinal axis of a single web of a single depositing unit of a plant for the manufacture of spunbond fabrics, which web has been deposited on a collecting surface (not shown);
Figure 2 is in four parts, i.e. a, b, c, and d, to show cross-sections of non-woven fabrics which are composed of several webs deposited one beside another as well as in an overlapping position;
Figure 3 represents a cross-section of a web prepared initially like that shown in Figure 2b and with the border zones folded towards the center;
Figure 4 represents steps a, b, c, d, and e of a process of folding a border zone of a web using schematic cross-sections in vertical direction to the longitudinal axis of the web;
Figure 5 is a flow scheme in elevation of the process of fold-ing the border zones;
Figure 6 is a diagrammatic representation of the basis weight distribution of the web with the borders not being folded, transversely to the direction of run of the web;
Figure 7 is a diagrammatic representation of the basis weight distribution of the web with the borders folded accord-ing to the invention;
Figure 8 is a diagrammatic representation of the basis weight distribution in the border zone of a further web with the border zone not being folded; and Figure 9 is a diagrammatic representation of the web with the border zones b~ing folded according to -the invention.
~ 7 _ .
.
379g R~ference is first made to Figure 1, which shows a cross-section transversely to the longitudinal axis of a web 1 issuing from a single depositing unit.
` \ . , - .
, ~: ' ' " , . .
. . - .
.
,, . :, ' ` . ' '' , . :
, ., .: .:
, 1~83799 Several webs or strips of non-woven fabrics issuing from single depositing units must be deposited one beside the other overlappingly, for the preparation of wide non-woven structures. Possibilities of arranging strips of this type within the structure of non-woven fabrics of relatively great width are shown in Figure 2, parts a to d. In these repre-sentations the adjacent strips within the structure of the non-woven fabric touch only at their surface. However, as it has been mentioned particularly in German Offenlegungsschrift No.
24 60 755, the strips arranged one upon the other may also penetrate each other by their layers of individual filaments or of filament bundles. Those zones of the non-woven fabrics which are located outside of both dotted vertical lines 2 constitute the border zones of the fabrics. They have a lower basis weight than the central zones of the non-woven fabrics of uniform basis weight or their basis weight is reduced to the border. The arrows visible in Figure 2c at regular inter-vals mean to say that the basis weight decreases from the center to the border in linear manner. -Non-woven fabrics of different structure, the basis weight of which likewise decreases to the border, are further-more known or imaginable. Fabrics of this kind may also be used for the process of the invention.
-~ Figure 3 represents the non-woven fabric of Figure 2b with the border zones being folded.
Figure ~ is a cross-sectional view in vertical direction with respect to the longitudinal axis of the non-woven fabric of the individual stages of the process of folding the border zones. Figure 4a shows the fabric 3 with the border zones not . . ~ . . ~ .
. .
,. . ." ' ` , ' ' '" ':
.': . , ' ' ' - `, , .,, '', ~. ~' . .
.. . . . . . :: . .:. ; . .. .
- \
1~D8379~3 being folded and with the calender rolls ~ and 5. The border zone of the fabric to be folded is forwarded to the first bar 6, which lifts the border zone 7 of ~he fabric.
Further bars are arranged at equal distances (Figure 4c, d), which further lift the border,zone and press it inwards and downwards or fold it. The fabric with the border zone being folded is thereafter drawn off by the pair of rolls 8 and 9 or is calendered as it is illustrated in Figure 4e.' Figure 5 is a side ~iew of the folding process~ The un folded non-woven fabric 3 is forwarded in the direction of the arrow to the folding zone by the calender rolls 4 and 5. The numerals 6 denote the folding bars, 7 the border to be folded and 10 a deflection bar. The length of this de~lection bar corresponds approximately to the desired width of the non-w,,oyen fabric with the border zones being folded. The deflection b~r is located approximately in the middle of the ~olding zone, the latter being limited by two draw-off rolls 8 and 9 of the calen-der. In the course of the folding process the web is deviated by the angle a around the bar 1~. Thus the foldlng process is facilitated. The web wi~h the borders being folded 3 is then drawn-off and calendered by the rolls 8 a,nd 9, passed through a needlin~ device 11 and wound u~ on a devicewhich is not shown.
The method of folding the borders and the device employed in the present invention are given by way o~ example only.
The following example illustrate tne invention:
E X ~ M P L E 1: ' ~ilaments were ~roduced f,rom molten polyethylene terephtha-late by two spinn~rets each having seventy holes, the filaments 29 were collected to ~orm two bundles and stretched by air n~zzles.
, --. g --.
. .
:. .. . , ~ . .
1~83799 The titer of the individual filaments was about 8 dtex.
Either filament bundle accelerated down by the air nozzles was forwarded to a rotating deflection device, by which they were deposited upon a collection sufrace moving with constant velocity~to form a strip. Both overlapping strips formed a non-woven fabric which was thereafter pre-consolidated by ca-lendering at 140 C. At an arbitrarily selected point of the web, the basis weight gradient shown in Figure 6 was measured photometrically in transverse direction with respect to the direction of movement of the web. In the diagram D denotes the weight per square meter, X denotes the coordinate trans- -versely with respect to the direction oE run of the web. As it can be seen from the curve in Figure 6~the weight per square meter D of the web ranges between 0 g at the border of the web and 150 g near the center of ~le web.The total width of the web was 72 cm. By the devices shown in Figures ~ and 5 14.~ cm of . .
the left border zone and 12.6 cm of the right one of the web were folded into the center. Thereafter the web was submitted to a second consolidation process by calendering at 140 ~.
The basis weight of the web with the borders being folded, de-termined at the same position, was in the range of from 100 g per square meter and 162 g per square meter, the average basis weight being about 137 g per square meter (cf. Figure 7). The web thus formed had a uniform structure and linear edges which had not to be trimmed and thus there was no waste material.
E X A M P L E 2:
.
Figure ~ shows the basis weight gradient of the border of a further non-woven fabric. After having folded the border 29 zone according to the invention and after having consolidated .. , : . ., . . .
.
.. , , :. ~ ., . . . , :, ' .. :: :
. . :.
~, . . .
~379~
the non-woven fabric a second time, the basis weight gxadient shown in Figure 9 was measured. In this case, the basis weight was measured at two positions of the non-woven fabric.
This non-woven fabric had also a uniform appearance and a smooth border so that trimming of the borders could be dispens-ed with.
.. , . : . .. . . .......................................... .. .
., , , . , : :-, , .. . , ~ ~, :. . ,: .
Claims
THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
In a process for avoiding waste material in manufacture of non-woven fabric, in which, prior to the main consolidation of a web, a part of each of the border zones for a web is folded towards the center, the improvement comprising directing the non-woven fabric in the folding zone about a bending zone, at an angle which is inclined towards that level towards which the border zone is folded, said angle being taken between an imaginary projection of an inclined plane of the web and the plane forward of the bending zone about which said web is guided said angle being defined as .alpha.?2 arc Sin ? wherein BR is the width of individual border zones of said web, L is the length of the web within said folding zone, said angle not to exceed about 90°, said width of both folded border zones being less than the ultimate entire width of said web, and said individual border zones being folded onto the same web surface.
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
In a process for avoiding waste material in manufacture of non-woven fabric, in which, prior to the main consolidation of a web, a part of each of the border zones for a web is folded towards the center, the improvement comprising directing the non-woven fabric in the folding zone about a bending zone, at an angle which is inclined towards that level towards which the border zone is folded, said angle being taken between an imaginary projection of an inclined plane of the web and the plane forward of the bending zone about which said web is guided said angle being defined as .alpha.?2 arc Sin ? wherein BR is the width of individual border zones of said web, L is the length of the web within said folding zone, said angle not to exceed about 90°, said width of both folded border zones being less than the ultimate entire width of said web, and said individual border zones being folded onto the same web surface.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19772706967 DE2706967C2 (en) | 1977-02-18 | 1977-02-18 | Wire feed device for zipper machines |
| DEP2706967.7 | 1977-02-18 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1083799A true CA1083799A (en) | 1980-08-19 |
Family
ID=6001550
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA297,260A Expired CA1083799A (en) | 1977-02-18 | 1978-02-17 | Process for the manufacture of non-woven structures |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1083799A (en) |
| DE (1) | DE2706967C2 (en) |
-
1977
- 1977-02-18 DE DE19772706967 patent/DE2706967C2/en not_active Expired
-
1978
- 1978-02-17 CA CA297,260A patent/CA1083799A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE2706967C2 (en) | 1979-01-25 |
| DE2706967B1 (en) | 1978-05-24 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |