CA1119368A - Polypropylene endless loop and the method therefor - Google Patents
Polypropylene endless loop and the method thereforInfo
- Publication number
- CA1119368A CA1119368A CA000311359A CA311359A CA1119368A CA 1119368 A CA1119368 A CA 1119368A CA 000311359 A CA000311359 A CA 000311359A CA 311359 A CA311359 A CA 311359A CA 1119368 A CA1119368 A CA 1119368A
- Authority
- CA
- Canada
- Prior art keywords
- endless
- polypropylene
- loops
- sheet
- draw ratio
- 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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- Manufacture Of Macromolecular Shaped Articles (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
A polypropylene endless loop is produced by blow-moulding polypropylene raw material into a tubular sheet, transversely drawing the sheet with a draw ratio of at least 4, before or after the drawing step, cutting or slitting the sheet to form individual endless sheet, and twisting the sheet after drawing to form an endless loop. The invention enebles one to produce a polypropylene endless loop having a transverse length of 7.5 to 35 cm with a tensile load of at least 6 kgs.
A polypropylene endless loop is produced by blow-moulding polypropylene raw material into a tubular sheet, transversely drawing the sheet with a draw ratio of at least 4, before or after the drawing step, cutting or slitting the sheet to form individual endless sheet, and twisting the sheet after drawing to form an endless loop. The invention enebles one to produce a polypropylene endless loop having a transverse length of 7.5 to 35 cm with a tensile load of at least 6 kgs.
Description
1~93~;8 This invention relates to a method of preparing a polypropylene endless loop and to the product obtained thereby.
Polypropylene ropes, cords, stands and the like have been widely used for packaging purposes, but there has been no previous disclosure or use of polypropylene endless loops for packaging purposes; i.e. securing or tying packages. The twisted endless loop of the present invention may, for example, be used to tie off the opening of a bag and facilitate its hanging or trans-portation; e.g. the loop is positioned to surround the mouth of the bag opening and one end of the loop is passed through the aper-ture formed at the other end thereof such that pulling of said one end causes the loop to tighten around the opening.
The present invention in one aspect provides a poly-propylene endless loop having a transverse length of from 7.5 to 35 cm exhibiting a tensile strength of at least 6 kgs.
The present invention also provides a polypropylene endless twisted loop having a transverse length of from about 7.5 to 35 cm and exhibiting a tensile strength of at least 6 kgs obtained by cutting a polypropylene tubular sheet of from about 0.03 to 0.1 mm in thickness and 15 to 50 mm in transverse length into longitudinal lengths of from about 10 to 60 mm, transversely drawing the same at a draw ratio of at least 4 to provide a resul-ting transverse length of from about 7.5 to 35 cm, then twisting the same to form an endless twisted loop.
The present invention further provides a polypropylene endless twisted loop having a transverse length of from about 7.5 to 35 cm and exhibiting a tensile strength of at least 6 kgs obtained by transversely drawing a polypropylene tubular sheet of from 0.03 to 0.1 mm in thickness and 15 to 50 mm in transverse length at a draw ratio of at least 4 to a resulting transverse length of 7.5 to 35 cm, then cutting the same in longitudinal lengths of from about 10 to 60 mm and finally twisting said cut - 1 - ~
length to form an endless twisted loop.
The present i~vention, in accordance with another aspect thereof, provides a method for preparing a polypropylene endless twisted loop suitable for packaging purposes comprising the steps of (a) blow moulding polypropylene into a tubular sheet, having dimensions of from about 15 to 50 mm in transverse 1ength and from about 0.03 - la to 0.1 mm in thickness, (b) either (i) cutting said sheet to form individual endless loops having a longitudinal length of from about 10 to 60 mm and drawing said loops transversely with respect to the longitudinal axis thereof at a draw ratio of at least 4 or (ii) drawing said tubular shee-t transversely with respect to the longitudinal axis thereof at a draw ratio of at least 4 and cutting said drawn tubular sheet to form individual endless loops having a longi-tudinal length of about 10 to 60 mm, and then (c) twisting said loops to form an endless twisted loop.
In the drawing which illustrates an embodiment of the invention and which sets forth the appearance of the poly-propylene at different stages, Fig. 1 shows a continuous tube of blow moulded poly-propylene which is then flattened and cut;
Fig. 2 shows cut portions of the tube of Fig. 1, to form individual loops;
Fig. 3 shows an individual cut loop after subjected to drawing transversely to the longitudinal axis of the tube of Fig. l; and Fig. 4 shows the drawn loop of Fig. 3 after it has been twisted to form an endless twisted loop.
As suggested above, one embodiment of the present method, comprises the steps of blow-moulding the polypropylene , 11~9368 raw materials in~ atubular sheet, cutting said sheet in suitable lengths to form individual loops, drawing said loops transversely with respect to the axis of the molded tube at a draw ratio of at least 4, then twisting said drawn loops to form the desired endless loop.
Furthermore, according to another embodiment, the present method comprises the steps of blow-moulding the poly-propylene raw materialsinto atubular sheet, subsequently drawing transversely said sheet at a draw ratio of at least 4, then cutting or slitting at suitable distance to form individual loops, and then twisting said loops to form the desired endless loop.
The blow-moulding of the polypropylene is carried out by a known technique with a conventional blow-moulding machine, but the moulded polypropylene tubular sheet, for providing the desired finished loop should, as indicated above, have dimensions of 15 to 50 mm, more preferably 20 to 30 mm, in transverse length, and 0.03 to 0.1 mm, more preferably 0.05 to 0.06 mm in thickness.
The term transverse length-- used herein is defined as the length measured transversely, i.e. along the radial direction of the tubular sheet, at one side after the tubular sheet has been folded to become a flat sheet material having two superimposed layers in close contact with each other.
When the cutting step is carried out before the drawing step, the tubular sheet is cut at a longitudinal distance of from 10 to 60mm, more preferably 25 to 35 mm, to form individual loops ~ccordingly, said longitudinal distance becomes the width of the resulting endless loop, and upon transverse drawing this width will be slightly decreased.
Upon transverse drawing, a force is applied to a tubular endless sheet or an endless loop a]ong the transverse direction which is perpendicular to the longitudinal direction 11193~B
with respect to the original tubular sheet, with a draw ratio at least 4, and preferably from 5 to 7. The term -draw ratio-used herein denotes the ratio~of the transverse length of the sheet or the loop after drawing to the same before drawing.
When the draw ratio is less than 4, the resulting endless sheet or loop has an insufficient tensile strength, while too great a draw ratio results in the sheet or loop being broken due to drawing beyond its limit.
After drawing, the transverse length of the endless sheet or loop will be from 7.5 to 35 cm, preferably ~rom 10 to 20 cm.
The transverse drawing may be carried out at ambient temperature or at a temperature which is preferably up to 40C.
The drawn endless loop so obtained is further twisted inany convenient manner to become the desired endless twisted loop.
In general, a polypropylene endless loop of the present invention when used for packaging should exhibit a tensile strength of at least about 1 to 5 kilograms, and the tests carried out in the following examples show that the tensile load at break of said endless loop is greater than 8 kgs.
The invention will therefore be further described with reference to the following illustrative Examples.
A blow-moulded polypropylene tubular sheet 25 mm in transverse length and 0.055 mm in thickness was cut into an loops of 35 mm in the longitudinal direction. After drawing to suitable extent, the transverse length was measured as shown in Table 1.
The width of the individual loops after drawing was in the range of 25 to 26 mm. Finally, the endless loops were twisted to form an endless twisted loop and subjected to - ` 111~36~3 tensile testing, the tensile load obtained being given in Table 1.
R n ~ Transverse length Draw ratio by Tensile load u . after drawing, mm calculation at break, kgs.
1 170 6.80 12
Polypropylene ropes, cords, stands and the like have been widely used for packaging purposes, but there has been no previous disclosure or use of polypropylene endless loops for packaging purposes; i.e. securing or tying packages. The twisted endless loop of the present invention may, for example, be used to tie off the opening of a bag and facilitate its hanging or trans-portation; e.g. the loop is positioned to surround the mouth of the bag opening and one end of the loop is passed through the aper-ture formed at the other end thereof such that pulling of said one end causes the loop to tighten around the opening.
The present invention in one aspect provides a poly-propylene endless loop having a transverse length of from 7.5 to 35 cm exhibiting a tensile strength of at least 6 kgs.
The present invention also provides a polypropylene endless twisted loop having a transverse length of from about 7.5 to 35 cm and exhibiting a tensile strength of at least 6 kgs obtained by cutting a polypropylene tubular sheet of from about 0.03 to 0.1 mm in thickness and 15 to 50 mm in transverse length into longitudinal lengths of from about 10 to 60 mm, transversely drawing the same at a draw ratio of at least 4 to provide a resul-ting transverse length of from about 7.5 to 35 cm, then twisting the same to form an endless twisted loop.
The present invention further provides a polypropylene endless twisted loop having a transverse length of from about 7.5 to 35 cm and exhibiting a tensile strength of at least 6 kgs obtained by transversely drawing a polypropylene tubular sheet of from 0.03 to 0.1 mm in thickness and 15 to 50 mm in transverse length at a draw ratio of at least 4 to a resulting transverse length of 7.5 to 35 cm, then cutting the same in longitudinal lengths of from about 10 to 60 mm and finally twisting said cut - 1 - ~
length to form an endless twisted loop.
The present i~vention, in accordance with another aspect thereof, provides a method for preparing a polypropylene endless twisted loop suitable for packaging purposes comprising the steps of (a) blow moulding polypropylene into a tubular sheet, having dimensions of from about 15 to 50 mm in transverse 1ength and from about 0.03 - la to 0.1 mm in thickness, (b) either (i) cutting said sheet to form individual endless loops having a longitudinal length of from about 10 to 60 mm and drawing said loops transversely with respect to the longitudinal axis thereof at a draw ratio of at least 4 or (ii) drawing said tubular shee-t transversely with respect to the longitudinal axis thereof at a draw ratio of at least 4 and cutting said drawn tubular sheet to form individual endless loops having a longi-tudinal length of about 10 to 60 mm, and then (c) twisting said loops to form an endless twisted loop.
In the drawing which illustrates an embodiment of the invention and which sets forth the appearance of the poly-propylene at different stages, Fig. 1 shows a continuous tube of blow moulded poly-propylene which is then flattened and cut;
Fig. 2 shows cut portions of the tube of Fig. 1, to form individual loops;
Fig. 3 shows an individual cut loop after subjected to drawing transversely to the longitudinal axis of the tube of Fig. l; and Fig. 4 shows the drawn loop of Fig. 3 after it has been twisted to form an endless twisted loop.
As suggested above, one embodiment of the present method, comprises the steps of blow-moulding the polypropylene , 11~9368 raw materials in~ atubular sheet, cutting said sheet in suitable lengths to form individual loops, drawing said loops transversely with respect to the axis of the molded tube at a draw ratio of at least 4, then twisting said drawn loops to form the desired endless loop.
Furthermore, according to another embodiment, the present method comprises the steps of blow-moulding the poly-propylene raw materialsinto atubular sheet, subsequently drawing transversely said sheet at a draw ratio of at least 4, then cutting or slitting at suitable distance to form individual loops, and then twisting said loops to form the desired endless loop.
The blow-moulding of the polypropylene is carried out by a known technique with a conventional blow-moulding machine, but the moulded polypropylene tubular sheet, for providing the desired finished loop should, as indicated above, have dimensions of 15 to 50 mm, more preferably 20 to 30 mm, in transverse length, and 0.03 to 0.1 mm, more preferably 0.05 to 0.06 mm in thickness.
The term transverse length-- used herein is defined as the length measured transversely, i.e. along the radial direction of the tubular sheet, at one side after the tubular sheet has been folded to become a flat sheet material having two superimposed layers in close contact with each other.
When the cutting step is carried out before the drawing step, the tubular sheet is cut at a longitudinal distance of from 10 to 60mm, more preferably 25 to 35 mm, to form individual loops ~ccordingly, said longitudinal distance becomes the width of the resulting endless loop, and upon transverse drawing this width will be slightly decreased.
Upon transverse drawing, a force is applied to a tubular endless sheet or an endless loop a]ong the transverse direction which is perpendicular to the longitudinal direction 11193~B
with respect to the original tubular sheet, with a draw ratio at least 4, and preferably from 5 to 7. The term -draw ratio-used herein denotes the ratio~of the transverse length of the sheet or the loop after drawing to the same before drawing.
When the draw ratio is less than 4, the resulting endless sheet or loop has an insufficient tensile strength, while too great a draw ratio results in the sheet or loop being broken due to drawing beyond its limit.
After drawing, the transverse length of the endless sheet or loop will be from 7.5 to 35 cm, preferably ~rom 10 to 20 cm.
The transverse drawing may be carried out at ambient temperature or at a temperature which is preferably up to 40C.
The drawn endless loop so obtained is further twisted inany convenient manner to become the desired endless twisted loop.
In general, a polypropylene endless loop of the present invention when used for packaging should exhibit a tensile strength of at least about 1 to 5 kilograms, and the tests carried out in the following examples show that the tensile load at break of said endless loop is greater than 8 kgs.
The invention will therefore be further described with reference to the following illustrative Examples.
A blow-moulded polypropylene tubular sheet 25 mm in transverse length and 0.055 mm in thickness was cut into an loops of 35 mm in the longitudinal direction. After drawing to suitable extent, the transverse length was measured as shown in Table 1.
The width of the individual loops after drawing was in the range of 25 to 26 mm. Finally, the endless loops were twisted to form an endless twisted loop and subjected to - ` 111~36~3 tensile testing, the tensile load obtained being given in Table 1.
R n ~ Transverse length Draw ratio by Tensile load u . after drawing, mm calculation at break, kgs.
1 170 6.80 12
2 150 6.00 10
3 158 6.32 10
4 161 6.44 14 152 6.08 14 6 144 5.76 14 . 7 154 6.16 15 8 158 6.32 14 9 157 6.28 14 156 6.24 13 _ The procedure of Example 1 was repeated, except that the endless sheet was cut into len~ths of 30 mm. The result~ are shown in Table 2.
Run N Transverse length Draw Ratio by Textile load . after drawing, mm calculation at break, kgs, 11 172 6.88 13 12 159 6.36 13 13 165 6.6~ 10 14 166 6.64 11 154 6.16 13 16 155 6.20 10 17 157 6.28 14 1~3 157 6.28 12 19 160 6.40 12 150 _ 6.00 13 .
:
, . ~ .. ~ .. :
The procedure of Example 1 was repeated, except that the endless sheet was cut into lengths of 25 mm. The results are shown in Table 3.
R N 'Transverse length I Draw ratio by Tensile load I
un after drawing,mm. ! calculation at break, kgs.
_ , l _ 21 1 150 6.00 10 22 151 6.04 8 23 151 6.04 8 24 151 6.04 11 150 6.00 9 26 152 6.08 11 27 150 6.00 10 28 150 6.00 10 29 154 6.16 9 151 6.04 It is apparent from Table 3 that when a sheet with a thickness of 0.055 mm is cut into leng-ths of 25 mm, i.e.
to obtain individual endless loops with a width of 25 mm, then the tensile strength after drawing is less satisfactory.
Therefore, it is preferable to employ thicker polypropylene tubular sheet or a wider endless sheet to give a more satis-factory tensile load.
,
Run N Transverse length Draw Ratio by Textile load . after drawing, mm calculation at break, kgs, 11 172 6.88 13 12 159 6.36 13 13 165 6.6~ 10 14 166 6.64 11 154 6.16 13 16 155 6.20 10 17 157 6.28 14 1~3 157 6.28 12 19 160 6.40 12 150 _ 6.00 13 .
:
, . ~ .. ~ .. :
The procedure of Example 1 was repeated, except that the endless sheet was cut into lengths of 25 mm. The results are shown in Table 3.
R N 'Transverse length I Draw ratio by Tensile load I
un after drawing,mm. ! calculation at break, kgs.
_ , l _ 21 1 150 6.00 10 22 151 6.04 8 23 151 6.04 8 24 151 6.04 11 150 6.00 9 26 152 6.08 11 27 150 6.00 10 28 150 6.00 10 29 154 6.16 9 151 6.04 It is apparent from Table 3 that when a sheet with a thickness of 0.055 mm is cut into leng-ths of 25 mm, i.e.
to obtain individual endless loops with a width of 25 mm, then the tensile strength after drawing is less satisfactory.
Therefore, it is preferable to employ thicker polypropylene tubular sheet or a wider endless sheet to give a more satis-factory tensile load.
,
Claims (10)
1. A method for preparing a polypropylene endless twisted loop suitable for packaging purposes comprising the steps of (a) blow moulding polypropylene into a tubular sheet, having dimensions of from about 15 to 50 mm in transverse length and from about 0.03 to 0.1 mm in thickness, (b) either (i) cutting said sheet to form individual endless loops having a longitudinal length of from about 10 to 60 mm and drawing said loops transversely with respect to the longitudinal axis thereof at a draw ratio of at least 4 or (ii) drawing said tubular sheet transversely with respect to the longitudinal axis thereof at a draw ratio of at least 4 and cutting said drawn tubular sheet to form individual endless loops having a longi-tudinal length of about 10 to 60 mm, and then (c) twisting said loops to form an endless twisted loop.
2. A method for preparing a polypropylene endless twisted loop suitable for packaging purposes comprising the steps of blow-moulding polypropylene into a tubular sheet, having dimensions of from about 15 to 50 mm in transverse length and from about 0.03 to 0.1 mm in thickness, cutting said sheet to form individual endless loops having a longitudinal length of from about 10 to 60 mm, drawing said loops transversely with respect to the longitudinal axis thereof at a draw ratio of at least 4, and then twisting said drawn loops to form an endless twisted loop.
3. A method as set forth in claim 2, wherein the transverse drawing is carried out at a temperature in the range from ambient temperature up to 40°C.
4. A method as set forth in claim 2, wherein the draw ratio is in the range from 5 to 7.
5. A method for preparing a polypropylene endless twisted loop suitable for packaging purposes comprising the steps of blow-moulding polypropylene into a tubular sheet, having dimensions of from about 15 to 50 mm in transverse length and from about 0.03 to 0.1 mm in thickness, drawing said tubular sheet transversely with respect to the longitudinal axis thereof at a draw ratio of at least 4, then cutting said drawn tubular sheet to form individual endless loops having a longitudinal length of from about 10 to 60 mm, and twisting said loops to form an endless twisted loop.
6. A method as set forth in claim 5, wherein the transverse drawing is carried out at a temperature in the range from ambient temperature up to 40°C.
7. A method as set forth in claim 5, wherein the draw ratio is in the range from 5 to 7.
8. A polypropylene endless loop having the transverse length of 7.5 to 35 cm with tensile load of at least 6 kgs.
9. A polypropylene endless twisted loop having a transverse length of from about 7.5 to 35 cm and exhibiting a tensile strength of at least 6 kgs obtained by cutting a poly-propylene tubular sheet of from about 0.03 to 0.1 mm in thickness and 15 to 50 mm in transverse length into longitudinal lengths of from about 10 to 60 mm, transversely drawing the same at a draw ratio of at least 4 to provide a resulting transverse length of from about 7.5 to 35 cm, then twisting the same to form an endless twisted loop.
10. A polypropylene endless twisted loop having a transverse length of from about 7.5 to 35 cm and exhibiting a tensile strength of at least 6 kgs obtained by transversely drawing a polypropylene tubular sheet of from about 0.03 to 0.1 mm in thickness and 15 to 50 mm in transverse length at a draw ratio of at least 4 to a resulting transverse length of 7.5 to 35 cm, then cutting the same in longitudinal lengths of from about 10 to 60 mm and finally twisting said cut length to form an endless twisted loop.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000311359A CA1119368A (en) | 1978-09-14 | 1978-09-14 | Polypropylene endless loop and the method therefor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000311359A CA1119368A (en) | 1978-09-14 | 1978-09-14 | Polypropylene endless loop and the method therefor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1119368A true CA1119368A (en) | 1982-03-09 |
Family
ID=4112358
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000311359A Expired CA1119368A (en) | 1978-09-14 | 1978-09-14 | Polypropylene endless loop and the method therefor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1119368A (en) |
-
1978
- 1978-09-14 CA CA000311359A patent/CA1119368A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |