CA1139650A - Stiff woven polyethylene fabric - Google Patents
Stiff woven polyethylene fabricInfo
- Publication number
- CA1139650A CA1139650A CA000339654A CA339654A CA1139650A CA 1139650 A CA1139650 A CA 1139650A CA 000339654 A CA000339654 A CA 000339654A CA 339654 A CA339654 A CA 339654A CA 1139650 A CA1139650 A CA 1139650A
- Authority
- CA
- Canada
- Prior art keywords
- polyethylene
- scrim
- film
- fabric
- tapes
- 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
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- Laminated Bodies (AREA)
Abstract
ABSTRACT
A stiff woven polyethylene fabric is disclosed, which comprises a scrim of woven oriented polyethylene tapes laminated to an oriented polyethylene film with an adhesive layer of polyethylene. The polyethylene film may be monoaxially or biaxially oriented or blown film.
The fabric is useful for making sacks which may be filled in automatic packaging operations.
A stiff woven polyethylene fabric is disclosed, which comprises a scrim of woven oriented polyethylene tapes laminated to an oriented polyethylene film with an adhesive layer of polyethylene. The polyethylene film may be monoaxially or biaxially oriented or blown film.
The fabric is useful for making sacks which may be filled in automatic packaging operations.
Description
~i3~sl) STIFF WOVEN POLYETHYLENE FABRIC
The present invention relates to a fabric, made from woven polyethylene tapes, which is useful for making industrial sacks.
It is known to make industrial sacks from fabrics, made from woven polyethylene tapes, which have been extrusion coated with a layer of polyethylene.
When used in some automatic sack making and filling methods many such commercial fabrics suffer from the disadvantage of being relatively limp. For example in one step in an automatic sack filling process a filled open-mouthed sack is advanced, open mouth upwards, towards a sewing station where the mouth of the sack is sewn closed. In such a sewing step it is desirable that the open mouth of the sack be stiff enough to prevent sag~ing of the walls of the mouth, which leads to mal-formation of the sewn mouth or to an incompletely sewn mouth. In the extreme the problem of an insufficiently stiff sack mouth may lead to jamming of the apparatus used to prepare the mouth for sewing ancl/or the sewing apparatus Known methods of stiffening the fabric include using tapes of a higher denier, e.g. using thicker tapes, tightening the weave of the tapes, or applying a thicker coating to the woven tape structure. These methods tend to make the fabric more expensive however.
Another fabric made from polypropylene tapes, coated with polypropylene possesses sufficient stiff-3~
.
113~?~iSO
ness to be used in some automatic sack filling methods.
A disadvantage of the polypropylene fabric however is that seams in the fabric must be joined either by sew-ing, or by a hotmelt seaming method, which tends to be costly.
A polyethylene fabric which tends to be sub-stantially stiffer than fabrics made from woven poly-ethylene tapes of similar weight per area has now been found. An advantage of the fabric is that seams may be made by heat sealing methods such as for example that disclosed by R.N. ~oole in U.S. patent 3 951 050, which issued 1976 April 20.
The present invention provides a fabric com-prising a scrim of woven oriented polyethylene tapes, said scrim being coated on one side with polyethylene, and an oriented polyethylene film laminated to the coating of the scrim.
In a preferred embodiment the polyethylene film is a monoaxially oriented polyethylene film made from polyethylene having a density between 0.940 and 0.970 g/cm3 and the direction of orientation of the polyethylene film follows the direction of either the warp or weft tapes, preferably the warp tapes of the woven scrim.
In another embodiment the polyethylene film is a biaxially oriented polyethylene film made from polyethylene having a density between 0.940 and 0.970 g/cm3.
In yet another embodiment the scrim is made from monoaxially oriented tapes of polyethylene having a density between 0.940 and 0.970 g/cm3 and the coating is made from polyethylene having a density between 0.910 and 0.955 g/cm3.
In a further embodiment the polyethylene film is blown film made from polyethylene having a density between 0.940 and 0.970 g/cm3.
The present invention also provides a sack made from the fabric of the present invention.
The fabric of the present invention may be made by a) weaving a scrim from warp and weft tapes of oriented polyethylene, b) extrusion coatin~ the scrim with a thin layer of polyethylene and c) laminat-ing the coated scrim to an oriented polyethylene film.
Each of the three steps may be carried out using known methods. For example the oriented poly-ethylene film and the polyethylene coating may be applied simultaneously to the woven scrim so that the polyethylene coating acts as a bonding agent to both the scrim and the film.
The method of simultaneously extrusion coat-ing the layer of polyethylene and laminating the film may be illustrated by Figure 1, which shows the method diagramatically.
A web of scrim 10, made from woven polyethy-lene tapes, is transported from supply roll 11 to take-up roll 12 passing over idler rollers 13, 15 and 16 and chill roll 14. A thin layer of polyethylene 17 is extruded onto scrim 10 from a slot die :L8 of extruder 19, at a position close to or at chill roll 14. Thin layer 17 is extruded onto the side of scrim 10 which is furthest away from chill roll 14. Simultaneously, ori-ented polyethylene film 20 is fed from supply roll 21 and around nip roll 23 onto thin layer 17. Nip roll 22 presses against chill roll 14, thus nipping the three-layer fabric therebetween. The chill roll causes sol-idification of this layer 17 and hence bonding of thin layer 17 to both scrim 10 and oriented film 20. The thus-laminated fabric 23 is wound up on take-up roll 12.
It is to be understood that the monoaxially oriented polyethylene ilm may be co-oriented laminated film. Co-orientation lamination refers to a process involving essentially simultaneous orientation and lamination, and may be accomplished by bringing two polyethylene films into face-to-face contact and orient-ing the two contacting films longitudinally at a temp-erature below the melting point of the polymer of the film having the higher melting point. The polyethylene films may be the same, or different, and may be homo-polymers or copolymers of ethylene, provided that the homopolymers or copolymers have a density between 0.940 and 0.970 g/cm3.
One method for carrying out the co-orienta-tion lamination involves passing the two contacting films over a first heated roll and subse~uently over a second heated roll. The temperature of the first roll is kept higher than that of the second roll, and the surface speed of the second roll is at least 1.5 times the surface speed of the first roll, e.g. between 3.0 and 8.0 times the surface speed of the first roll.
It is usual ~or the gap between the first and second rolls to be in the range of 1.2 to 5.0 mm, measured between their surfaces in a line ~oining the rotational centres o~ the rolls.
A preferred method for co-orientation lamin-ation in which the two polyethylene films are the sameinvolves taking tubular polyethylene film made by the blown film process, collapsing the film and subsequently co-orientation laminating as hereinbefore described.
The oriented film may also be blown film made from polyethylene having a density in the range of 0.g40 to 0.970 g/cm3. Such film may be made by a pro-cess such as, for example, that disclosed in Canadian patent 460 963 which issued 1949 November 8 to E.D.
Fuller. The blown film so formed is flattened and slit at the edges, thus forming two sheets, one of which may ti5f) then be used as the oriented ilm of the present fabric.
Such blown film process is operated preferably at a blow-up ratio of between about 1.1 to 1 and 4.0 to 1.
The term "blow-up ratio" as used herein means the ratio of the diameter of the expanded film tubing to the diameter of the circular die through which the tubing is extruded.
Biaxially oriented film, useful as the orient-ed film used in the present invention may be made by techni~ues known in the art.
It is preferred that the oriented film has a thickness in the range of 15-50 ~m, most preferably in the range of 20-30 ~m.
It is to be further understood that the mono-axially oriented polyethylene tapes used to make the scrim portion of the present fabric may be made by first extruding polyethylene film e.g. by the blown film process or the cast flat film process, slitting the film longitudinally to form a plurality of tapes and subsequently orienting the tapes individually in the machine i.e. longitudinal direction. Alternatively the monoaxially oriented tapes may be made by forming monoaxially oriented film e.g. by co-orientation lami-nation, and thereafter slitting said film into tapes, as disclosed for example in Canadian patent 1 041 005 to M.J. Wolstencroft, which issued 1978 October 10. The tapes are then woven into scrim in a known manner.
It is preferred that the polyethylene tapes used in the scrim have a tape width in the range o 1.2-6 mm, most preferably in the range of 1.5-3.5 mm. It is also preferred that the tapes have a linear density in the range of 550-2200 dtex, most preferably in the range of 650-1450 dtex.
The selection of the polyethylene used for 113~ti5~
-the extrusion coating step is not critical, although as is known to those skIlled in the art certain poly-ethylenes may be easier to extrude than others.
It is usual that the weavinq step is done separately from the extrusion coating and lamlnating ~teps, primarily because the rate of weaving is much slower than the rate of extrusion coating and laminat-ing. The last two steps i.e. extrusion coating and laminating are most conveniently done simultaneously as hereinbefore described in relation to the descrip-tion of the drawing. Lamination may however be carried out separately, using known techniques.
The fabric of the present invention is use-ful ~or making sacks, particularly those intended to be filled using automatic sack filling apparatus.
Sacks may be made by folding the fabric longitudinally, bringing the edges together in abutting relationship and applying a joining strip over the abutt;ng edges.
A method and apparatus for accomplishing this is dis-closed by R.N. Poole in U.S. patent 3 951 050. The tube thus formed is cut into lengths appropriate for the sacks to be made therefrom. The tube is then flat-tened and one end of the flattened tube is sealed using a so-called "tape-over" seal. Essentially, this type of seal is formed by applying a wide polyethylene strip or strip of polyethylene-coated tape scrim over the end of the tube, using a hot melt adhesive.
The sack, when filled may be sealed by sew-ing, or by the use of an adhesive or hot air sealing.
Sewing tends to make the seal weaker than the other seals. A tape-over seal is preferred.
The improved stiffness of the present fabric gives a decided advantage in automatic sack filling operations. The fabric may however be easier to split under high stress and sacks made therefrom may be .~
i5 unsuitable for some applications where the filled sack is subjected to extreme stress, e.g. when a filled 45 kg sack is dropped from a height of about 5 m. It is suitable however for many other applications.
The following examples serve to illustrate the present invention:
In Example 1 which illustrates the prior art, a scrim was woven from 2.54 mm wide and 1000 dtex warp tapes and 3.43 mm wide and 1083 dtex weft tapes. Each of the tapes was made from oriented polyethylene having a density of 0.960 g/cm3. The scrim structure had 3.55 ends/cm and 2.75 picksJcm. The scrim was extrusion coated with a 25 ~m thick layer of polyethylene having a density of 0.923 g/cm3.
In Example 2, which also illustrates the prior art, a scrim having 3.55 ends/cm and 3.55 picks/cm was woven from a 2.54 mm wide and 1089 dtex warp tapes and 3.43 mm wide and 1211 dtex weft tapes. The tapes were made from the same polyethylene as in Example 1. The scrim was extrusion coated with a 35 ~m thick layer of polyethylene having a density of 0.923 g/cm3.
In Example 3, which illustrates one embodi-ment of the present invention, a scrim havinq 3.55 ends/
cm and 2.28 picks/cm, was woven from 2.54 mm wide and 667 dtex warp tapes and 4.45 mm wide and 1167 dtex weft tapes. The tapes were made from the same polyethy-lene as in Example 1. The scrim was extrusion coated with a 25 ~m layer of polyethylene having a density of 0.923 g/cm3 and a 25 ~m monoaxially co-oriented lami-nated film of polyethylene having a density of 0.960 g/cm3 was laminated to the coating of the coated scrim.
The direction of orientation of the film was parallel to the warp tapes.
In Example 4 a coated scrim similar to that of Example 1, except that the number of weft tapes was ii391~;50 reduced to 1.58 picks/cm and the coated scrim was lami-nated as in Example 3, to a 20 ~m layer of blown poly-ethylene film having a density of about 0.955 g/cm3.
Samples from Examples 1 to 4 were analyzed for Modified Clark Stiffness and the results are shown in the table below:
Fabric Weight Modified Clark Stiffness Values Example(g/m ) Warp Weft 1 91.5 65 50
The present invention relates to a fabric, made from woven polyethylene tapes, which is useful for making industrial sacks.
It is known to make industrial sacks from fabrics, made from woven polyethylene tapes, which have been extrusion coated with a layer of polyethylene.
When used in some automatic sack making and filling methods many such commercial fabrics suffer from the disadvantage of being relatively limp. For example in one step in an automatic sack filling process a filled open-mouthed sack is advanced, open mouth upwards, towards a sewing station where the mouth of the sack is sewn closed. In such a sewing step it is desirable that the open mouth of the sack be stiff enough to prevent sag~ing of the walls of the mouth, which leads to mal-formation of the sewn mouth or to an incompletely sewn mouth. In the extreme the problem of an insufficiently stiff sack mouth may lead to jamming of the apparatus used to prepare the mouth for sewing ancl/or the sewing apparatus Known methods of stiffening the fabric include using tapes of a higher denier, e.g. using thicker tapes, tightening the weave of the tapes, or applying a thicker coating to the woven tape structure. These methods tend to make the fabric more expensive however.
Another fabric made from polypropylene tapes, coated with polypropylene possesses sufficient stiff-3~
.
113~?~iSO
ness to be used in some automatic sack filling methods.
A disadvantage of the polypropylene fabric however is that seams in the fabric must be joined either by sew-ing, or by a hotmelt seaming method, which tends to be costly.
A polyethylene fabric which tends to be sub-stantially stiffer than fabrics made from woven poly-ethylene tapes of similar weight per area has now been found. An advantage of the fabric is that seams may be made by heat sealing methods such as for example that disclosed by R.N. ~oole in U.S. patent 3 951 050, which issued 1976 April 20.
The present invention provides a fabric com-prising a scrim of woven oriented polyethylene tapes, said scrim being coated on one side with polyethylene, and an oriented polyethylene film laminated to the coating of the scrim.
In a preferred embodiment the polyethylene film is a monoaxially oriented polyethylene film made from polyethylene having a density between 0.940 and 0.970 g/cm3 and the direction of orientation of the polyethylene film follows the direction of either the warp or weft tapes, preferably the warp tapes of the woven scrim.
In another embodiment the polyethylene film is a biaxially oriented polyethylene film made from polyethylene having a density between 0.940 and 0.970 g/cm3.
In yet another embodiment the scrim is made from monoaxially oriented tapes of polyethylene having a density between 0.940 and 0.970 g/cm3 and the coating is made from polyethylene having a density between 0.910 and 0.955 g/cm3.
In a further embodiment the polyethylene film is blown film made from polyethylene having a density between 0.940 and 0.970 g/cm3.
The present invention also provides a sack made from the fabric of the present invention.
The fabric of the present invention may be made by a) weaving a scrim from warp and weft tapes of oriented polyethylene, b) extrusion coatin~ the scrim with a thin layer of polyethylene and c) laminat-ing the coated scrim to an oriented polyethylene film.
Each of the three steps may be carried out using known methods. For example the oriented poly-ethylene film and the polyethylene coating may be applied simultaneously to the woven scrim so that the polyethylene coating acts as a bonding agent to both the scrim and the film.
The method of simultaneously extrusion coat-ing the layer of polyethylene and laminating the film may be illustrated by Figure 1, which shows the method diagramatically.
A web of scrim 10, made from woven polyethy-lene tapes, is transported from supply roll 11 to take-up roll 12 passing over idler rollers 13, 15 and 16 and chill roll 14. A thin layer of polyethylene 17 is extruded onto scrim 10 from a slot die :L8 of extruder 19, at a position close to or at chill roll 14. Thin layer 17 is extruded onto the side of scrim 10 which is furthest away from chill roll 14. Simultaneously, ori-ented polyethylene film 20 is fed from supply roll 21 and around nip roll 23 onto thin layer 17. Nip roll 22 presses against chill roll 14, thus nipping the three-layer fabric therebetween. The chill roll causes sol-idification of this layer 17 and hence bonding of thin layer 17 to both scrim 10 and oriented film 20. The thus-laminated fabric 23 is wound up on take-up roll 12.
It is to be understood that the monoaxially oriented polyethylene ilm may be co-oriented laminated film. Co-orientation lamination refers to a process involving essentially simultaneous orientation and lamination, and may be accomplished by bringing two polyethylene films into face-to-face contact and orient-ing the two contacting films longitudinally at a temp-erature below the melting point of the polymer of the film having the higher melting point. The polyethylene films may be the same, or different, and may be homo-polymers or copolymers of ethylene, provided that the homopolymers or copolymers have a density between 0.940 and 0.970 g/cm3.
One method for carrying out the co-orienta-tion lamination involves passing the two contacting films over a first heated roll and subse~uently over a second heated roll. The temperature of the first roll is kept higher than that of the second roll, and the surface speed of the second roll is at least 1.5 times the surface speed of the first roll, e.g. between 3.0 and 8.0 times the surface speed of the first roll.
It is usual ~or the gap between the first and second rolls to be in the range of 1.2 to 5.0 mm, measured between their surfaces in a line ~oining the rotational centres o~ the rolls.
A preferred method for co-orientation lamin-ation in which the two polyethylene films are the sameinvolves taking tubular polyethylene film made by the blown film process, collapsing the film and subsequently co-orientation laminating as hereinbefore described.
The oriented film may also be blown film made from polyethylene having a density in the range of 0.g40 to 0.970 g/cm3. Such film may be made by a pro-cess such as, for example, that disclosed in Canadian patent 460 963 which issued 1949 November 8 to E.D.
Fuller. The blown film so formed is flattened and slit at the edges, thus forming two sheets, one of which may ti5f) then be used as the oriented ilm of the present fabric.
Such blown film process is operated preferably at a blow-up ratio of between about 1.1 to 1 and 4.0 to 1.
The term "blow-up ratio" as used herein means the ratio of the diameter of the expanded film tubing to the diameter of the circular die through which the tubing is extruded.
Biaxially oriented film, useful as the orient-ed film used in the present invention may be made by techni~ues known in the art.
It is preferred that the oriented film has a thickness in the range of 15-50 ~m, most preferably in the range of 20-30 ~m.
It is to be further understood that the mono-axially oriented polyethylene tapes used to make the scrim portion of the present fabric may be made by first extruding polyethylene film e.g. by the blown film process or the cast flat film process, slitting the film longitudinally to form a plurality of tapes and subsequently orienting the tapes individually in the machine i.e. longitudinal direction. Alternatively the monoaxially oriented tapes may be made by forming monoaxially oriented film e.g. by co-orientation lami-nation, and thereafter slitting said film into tapes, as disclosed for example in Canadian patent 1 041 005 to M.J. Wolstencroft, which issued 1978 October 10. The tapes are then woven into scrim in a known manner.
It is preferred that the polyethylene tapes used in the scrim have a tape width in the range o 1.2-6 mm, most preferably in the range of 1.5-3.5 mm. It is also preferred that the tapes have a linear density in the range of 550-2200 dtex, most preferably in the range of 650-1450 dtex.
The selection of the polyethylene used for 113~ti5~
-the extrusion coating step is not critical, although as is known to those skIlled in the art certain poly-ethylenes may be easier to extrude than others.
It is usual that the weavinq step is done separately from the extrusion coating and lamlnating ~teps, primarily because the rate of weaving is much slower than the rate of extrusion coating and laminat-ing. The last two steps i.e. extrusion coating and laminating are most conveniently done simultaneously as hereinbefore described in relation to the descrip-tion of the drawing. Lamination may however be carried out separately, using known techniques.
The fabric of the present invention is use-ful ~or making sacks, particularly those intended to be filled using automatic sack filling apparatus.
Sacks may be made by folding the fabric longitudinally, bringing the edges together in abutting relationship and applying a joining strip over the abutt;ng edges.
A method and apparatus for accomplishing this is dis-closed by R.N. Poole in U.S. patent 3 951 050. The tube thus formed is cut into lengths appropriate for the sacks to be made therefrom. The tube is then flat-tened and one end of the flattened tube is sealed using a so-called "tape-over" seal. Essentially, this type of seal is formed by applying a wide polyethylene strip or strip of polyethylene-coated tape scrim over the end of the tube, using a hot melt adhesive.
The sack, when filled may be sealed by sew-ing, or by the use of an adhesive or hot air sealing.
Sewing tends to make the seal weaker than the other seals. A tape-over seal is preferred.
The improved stiffness of the present fabric gives a decided advantage in automatic sack filling operations. The fabric may however be easier to split under high stress and sacks made therefrom may be .~
i5 unsuitable for some applications where the filled sack is subjected to extreme stress, e.g. when a filled 45 kg sack is dropped from a height of about 5 m. It is suitable however for many other applications.
The following examples serve to illustrate the present invention:
In Example 1 which illustrates the prior art, a scrim was woven from 2.54 mm wide and 1000 dtex warp tapes and 3.43 mm wide and 1083 dtex weft tapes. Each of the tapes was made from oriented polyethylene having a density of 0.960 g/cm3. The scrim structure had 3.55 ends/cm and 2.75 picksJcm. The scrim was extrusion coated with a 25 ~m thick layer of polyethylene having a density of 0.923 g/cm3.
In Example 2, which also illustrates the prior art, a scrim having 3.55 ends/cm and 3.55 picks/cm was woven from a 2.54 mm wide and 1089 dtex warp tapes and 3.43 mm wide and 1211 dtex weft tapes. The tapes were made from the same polyethylene as in Example 1. The scrim was extrusion coated with a 35 ~m thick layer of polyethylene having a density of 0.923 g/cm3.
In Example 3, which illustrates one embodi-ment of the present invention, a scrim havinq 3.55 ends/
cm and 2.28 picks/cm, was woven from 2.54 mm wide and 667 dtex warp tapes and 4.45 mm wide and 1167 dtex weft tapes. The tapes were made from the same polyethy-lene as in Example 1. The scrim was extrusion coated with a 25 ~m layer of polyethylene having a density of 0.923 g/cm3 and a 25 ~m monoaxially co-oriented lami-nated film of polyethylene having a density of 0.960 g/cm3 was laminated to the coating of the coated scrim.
The direction of orientation of the film was parallel to the warp tapes.
In Example 4 a coated scrim similar to that of Example 1, except that the number of weft tapes was ii391~;50 reduced to 1.58 picks/cm and the coated scrim was lami-nated as in Example 3, to a 20 ~m layer of blown poly-ethylene film having a density of about 0.955 g/cm3.
Samples from Examples 1 to 4 were analyzed for Modified Clark Stiffness and the results are shown in the table below:
Fabric Weight Modified Clark Stiffness Values Example(g/m ) Warp Weft 1 91.5 65 50
2 115.3 83 96
3 94.9 144 188
4 98.3 136 75 Modified Clark Stiffness was measured using the Technical Association of Pulp and Paper Industries Standard T-451-m45, with the exception that two pieces of the sample were glued together in face-to-face re-lationship to minimize the effect of curl of the sample.
A comparison of Examples 1 and 2 show that the combination of increasing the weave density, the thickness of the tapes and of the coating gives only marginal improvement. A comparison of Examples 1 and 3, however, shows that a fabric of the present inven-tion having about the same fabric weight per square metre as one of the prior art has a greatly increased level of Clark Stiffness.
Indeed, the fabric of Example 3 is superior in respect of Clark Stiffness to a fabric of poly-propylene comprising a scrim having 4.73 ends/cm and 2.76 picks/cm woven from 2.54 mm and 1111 dtex warp and weft tapes, coated with a 36 ~m layer of poly-propylene copolymer.
A comparison of Examples 1 and 2 show that the combination of increasing the weave density, the thickness of the tapes and of the coating gives only marginal improvement. A comparison of Examples 1 and 3, however, shows that a fabric of the present inven-tion having about the same fabric weight per square metre as one of the prior art has a greatly increased level of Clark Stiffness.
Indeed, the fabric of Example 3 is superior in respect of Clark Stiffness to a fabric of poly-propylene comprising a scrim having 4.73 ends/cm and 2.76 picks/cm woven from 2.54 mm and 1111 dtex warp and weft tapes, coated with a 36 ~m layer of poly-propylene copolymer.
Claims (15)
1. A fabric comprising a scrim of woven oriented polyethylene tapes, said scrim being coated on one side with polyethylene, and an oriented polyethylene film laminated to the coating of the scrim.
2. A fabric according to Claim 1 in which the polyethylene film is a monoaxially oriented polyethylene film made from polyethylene having a density between 0.940 and 0.970 g/cm3 and the direction of orientation of the polyethylene film follows the direction of the warp or weft tapes of the woven scrim.
3. A fabric according to Claim 2 in which the orientation of the polyethylene film follows the direction of the warp tapes of the woven scrim.
4. A fabric according to Claims 1,2 or 3 in which the polyethylene film is a co-oriented laminated film made from polyethylene having a density between 0.940 and 0.970 g/cm3.
5. A fabric according to Claim 1 in which the polyethylene film is a biaxially oriented polyethylene film made from polyethylene having a density between 0.940 and 0.970 g/cm3 and the coating is made from polyethylene having a density between 0.910 and 0.955 g/cm3.
6. A fabric according to Claim 1 in which the polyethylene film is a blown film made from polyethylene having a density between 0.940 and 0.970 g/cm3.
7. A fabric according to Claim 1 in which the polyethylene film has a thickness in the range of 15 -50 µm.
8. A fabric according to Claim 7 in which the polyethylene film has a thickness in the range of 20 -30 µm.
9. A fabric according to Claim 2, 5 or 6 in which the polyethylene film has a thickness in the range of 15 - 50 µm.
10. A fabric according to Claims 2, 5 or 6 in which the scrim has warp and weft tapes having a width in the range of 1.2 - 6 mm.
11. A fabric according to Claims 2, 5 or 6 in which the scrim has warp and weft tapes having a width in the range of 1.5 - 3.5 mm.
12. A fabric according to Claims 2.5 or 6 in which the scrim has warp and weft tapes having a linear density in the range of 550 - 2200 dtex.
13. A fabric according to Claims 2, 5 or 6 in which the scrim has warp and weft tapes having a linear density in the range of 650 - 1450 dtex.
14. A sack made from the fabric of Claim 1.
15. A sack made from the fabric of Claims 2, 5 or 6.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7845992 | 1978-11-24 | ||
| GB78/045992 | 1978-12-24 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1139650A true CA1139650A (en) | 1983-01-18 |
Family
ID=10501307
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000339654A Expired CA1139650A (en) | 1978-11-24 | 1979-11-13 | Stiff woven polyethylene fabric |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1139650A (en) |
-
1979
- 1979-11-13 CA CA000339654A patent/CA1139650A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |