CA1103140A - Trilaminate film for forming sideweld bags - Google Patents
Trilaminate film for forming sideweld bagsInfo
- Publication number
- CA1103140A CA1103140A CA287,308A CA287308A CA1103140A CA 1103140 A CA1103140 A CA 1103140A CA 287308 A CA287308 A CA 287308A CA 1103140 A CA1103140 A CA 1103140A
- Authority
- CA
- Canada
- Prior art keywords
- film
- thickness
- ethylene
- propylene
- percent
- 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
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
- B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
- B32B27/327—Layered products comprising a layer of synthetic resin comprising polyolefins comprising polyolefins obtained by a metallocene or single-site catalyst
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2305/00—Condition, form or state of the layers or laminate
- B32B2305/70—Scrap or recycled material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2439/00—Containers; Receptacles
- B32B2439/02—Open containers
- B32B2439/06—Bags, sacks, sachets
Abstract
TRILAMINATE FILM FOR
FORMING SIDEWELD BAGS
ABSTRACT OF THE DISCLOSURE
Sideweld bags having strong sidewelds can be made from a trilaminate film comprising a core layer of an ethylene-propylene block copolymer sandwiched between skin layers of polypropylene or an ethylene-propylene random copolymer.
FORMING SIDEWELD BAGS
ABSTRACT OF THE DISCLOSURE
Sideweld bags having strong sidewelds can be made from a trilaminate film comprising a core layer of an ethylene-propylene block copolymer sandwiched between skin layers of polypropylene or an ethylene-propylene random copolymer.
Description
11~13140 Bakery products, such as bread and buns, and textile products, such as shirts and pillow cases, are typica]ly packaged in so-called sideweld bags. The bags are made from film which is passed through a bag-forming machine in which a hot knife cuts through two o~erlying layers of the film and simultaneously welds the overlying edges together.
The film is usually made from a propylene polymer.
This invention provides an improved film for making sideweld bags The film is a trilaminate comprising a core layer of an ethylene-propylene block copolymer sandwiched between skin layers of polypropylene or an ethylene-propylene random copolymer. The ethylene content of the block co-polymer is from about S to 10 mole percent, and of the random copolymer, up to about 4 mole percent. For convenience, the two skin layers are preferably made from the same polymer, but need not be. The random copolymer gives slightly better results as the skin layer, but the homopolymer is less expensive. If desired, the skin layer may be a blend of the random copolymer and the homopolymer.
As used herein, the expression "ethylene-propylene block copolymer`' refers to the homogeneous product resulting from the sequential polymerization of ~1) propylene and ~2) a mixture of propylene and ethylene in the presence of a stereospecific polymerization catalyst. In other words, the product is made by first homopolymerizing propylene and then introducing ethylene into the polymerization zone while some unpolymerized propylene still remains. In theory, this polymerization process is intended to produce a polymer in which one or more segments of propylene homopolymer alternate with one or re segments of a copolymer of propylene and ethylene, such as represented by the formula P
~i~3140 AA~A~-AsAsAs ) n wherein A represents propylene, B represents ethylene, and n is one or more. However, it is not possible to avoid the formation of other polymers, such as homopolymers of pro-pylene and ethylene, so the product is actually an intimate mixture of such other polymers with the intended polymer.
A process for producing the ethylene propylene block copolymer is disclosed in British Patent 970,478.
The core layer accounts for about 30 to 90 percent, preferably 50 to 70 percent, of the thickness of the film.
The thickness of each skin layer is from about 5 to 35 per-cent, preferably 15 to 25 percent, of the thickness of the film. The thicknesses of the skin layers are preferably the same, but need not be. The overall thickness of the ~ilm is preferably from about 1 to 2 mils.
The film of this invention can be made in accordance with conventional coextrusion techniques. As is customary in such techni~ues, the film may include recycled trim. In the practice of this invention the trim, which may be as much as 40 percent of the film, but typically is between 15 and 25 percent, is preferably recycled completely in the core layer.
Thus, in the commercial practice of this invention, the core layer would include a minor amount of the polymer of the skin layers blended with the block copolymer.
Bags made from the film of this invention have unexpectedly stronger sidewelds than bags made from single layer films of either the homopolymer, the block copolymer or the random copolymer, as shown in the following examples.
Examples Sideweld bags were made on a Schjeldahl* bag-forming machine from the following films *trade mark , - 2 -1~3140 (a~ a trilaminate comprising a core layer of an ethylene-propylene block copolymer sandwiched between skin layers of polypropylene. The block copolymer was a block co-polymer having an ethylene content of between 5 and 10 mole percent sold by Hercules, Inc. under the designation 7531.
The polypropylene was sold under the designation 1178 by Amoco Chemicals Corp. The thickness ratio of the layers was 20:60:20.
(b) a trilaminate comprising a core layer of the same block copolymer sandwiched between skin layers of an ethylene-propylene random copolymer. The random copolymer, sold by Hercules under the designation SA-861, had an ethylene content between 2 and 4 mole percent. The thickness ratio of the layers was 20:60:20.
(c) a single layer film of the same block co-polymer.
(d) a single layer film of the same random co-polymer.
(e) a single layer film of the same polypropylene.
All films had a thickness of 1.25 mil. The core layer of the trilaminate films included about 20 percent recycled trim.
The bags were made at a speed of 80 bags per minute. The knife temperature was 710-720F. The strength of the side-welds of the bags was tested on an Eastman* Expansion tester, which is well known in the art for testing the strength of sidewelds. In the test, a band having a width of three inches is placed over two prongs, with a slack of one inch.
The prongs are then caused to move apart rapidly, at a pre-determined force, to take up the slack. If the band does not tear from the force of the prongs, it passes the test.
* trade mark ~i~3~40 Xf the sideweld ruptures, the band fails the test. Ten samples of each construction were tested at three different pressures. The results are reported in the following table.
SIDEWELD STRENGTH
Film 30 P5I 35 PSI 40 PSI
ConstructionPASS FAIL PASS FAIL PASS FAIL
Single Layer 0 10 0 10 0 10 Homopolymer Single Layer 0 10 0 10 0 10 Random Copolymer Single Layer 2 8 0 10 0 10 Block Copolymer Trilaminate with 10 0 10 0 10 0 Skin Layers of Random Co-polymer Trilaminate with 10 0 10 0 8 2 Skin Layers of Homopolymer ~.,
The film is usually made from a propylene polymer.
This invention provides an improved film for making sideweld bags The film is a trilaminate comprising a core layer of an ethylene-propylene block copolymer sandwiched between skin layers of polypropylene or an ethylene-propylene random copolymer. The ethylene content of the block co-polymer is from about S to 10 mole percent, and of the random copolymer, up to about 4 mole percent. For convenience, the two skin layers are preferably made from the same polymer, but need not be. The random copolymer gives slightly better results as the skin layer, but the homopolymer is less expensive. If desired, the skin layer may be a blend of the random copolymer and the homopolymer.
As used herein, the expression "ethylene-propylene block copolymer`' refers to the homogeneous product resulting from the sequential polymerization of ~1) propylene and ~2) a mixture of propylene and ethylene in the presence of a stereospecific polymerization catalyst. In other words, the product is made by first homopolymerizing propylene and then introducing ethylene into the polymerization zone while some unpolymerized propylene still remains. In theory, this polymerization process is intended to produce a polymer in which one or more segments of propylene homopolymer alternate with one or re segments of a copolymer of propylene and ethylene, such as represented by the formula P
~i~3140 AA~A~-AsAsAs ) n wherein A represents propylene, B represents ethylene, and n is one or more. However, it is not possible to avoid the formation of other polymers, such as homopolymers of pro-pylene and ethylene, so the product is actually an intimate mixture of such other polymers with the intended polymer.
A process for producing the ethylene propylene block copolymer is disclosed in British Patent 970,478.
The core layer accounts for about 30 to 90 percent, preferably 50 to 70 percent, of the thickness of the film.
The thickness of each skin layer is from about 5 to 35 per-cent, preferably 15 to 25 percent, of the thickness of the film. The thicknesses of the skin layers are preferably the same, but need not be. The overall thickness of the ~ilm is preferably from about 1 to 2 mils.
The film of this invention can be made in accordance with conventional coextrusion techniques. As is customary in such techni~ues, the film may include recycled trim. In the practice of this invention the trim, which may be as much as 40 percent of the film, but typically is between 15 and 25 percent, is preferably recycled completely in the core layer.
Thus, in the commercial practice of this invention, the core layer would include a minor amount of the polymer of the skin layers blended with the block copolymer.
Bags made from the film of this invention have unexpectedly stronger sidewelds than bags made from single layer films of either the homopolymer, the block copolymer or the random copolymer, as shown in the following examples.
Examples Sideweld bags were made on a Schjeldahl* bag-forming machine from the following films *trade mark , - 2 -1~3140 (a~ a trilaminate comprising a core layer of an ethylene-propylene block copolymer sandwiched between skin layers of polypropylene. The block copolymer was a block co-polymer having an ethylene content of between 5 and 10 mole percent sold by Hercules, Inc. under the designation 7531.
The polypropylene was sold under the designation 1178 by Amoco Chemicals Corp. The thickness ratio of the layers was 20:60:20.
(b) a trilaminate comprising a core layer of the same block copolymer sandwiched between skin layers of an ethylene-propylene random copolymer. The random copolymer, sold by Hercules under the designation SA-861, had an ethylene content between 2 and 4 mole percent. The thickness ratio of the layers was 20:60:20.
(c) a single layer film of the same block co-polymer.
(d) a single layer film of the same random co-polymer.
(e) a single layer film of the same polypropylene.
All films had a thickness of 1.25 mil. The core layer of the trilaminate films included about 20 percent recycled trim.
The bags were made at a speed of 80 bags per minute. The knife temperature was 710-720F. The strength of the side-welds of the bags was tested on an Eastman* Expansion tester, which is well known in the art for testing the strength of sidewelds. In the test, a band having a width of three inches is placed over two prongs, with a slack of one inch.
The prongs are then caused to move apart rapidly, at a pre-determined force, to take up the slack. If the band does not tear from the force of the prongs, it passes the test.
* trade mark ~i~3~40 Xf the sideweld ruptures, the band fails the test. Ten samples of each construction were tested at three different pressures. The results are reported in the following table.
SIDEWELD STRENGTH
Film 30 P5I 35 PSI 40 PSI
ConstructionPASS FAIL PASS FAIL PASS FAIL
Single Layer 0 10 0 10 0 10 Homopolymer Single Layer 0 10 0 10 0 10 Random Copolymer Single Layer 2 8 0 10 0 10 Block Copolymer Trilaminate with 10 0 10 0 10 0 Skin Layers of Random Co-polymer Trilaminate with 10 0 10 0 8 2 Skin Layers of Homopolymer ~.,
Claims (7)
1. A trilaminate film comprising a core layer of an ethylene-propylene block copolymer sandwiched between skin layers of polypropylene or an ethylene-propylene random copolymer having an ethylene content up to about four mole percent, the block copolymer being the homogeneous product resulting from the sequential polymerization of (1) propy-lene and (2) a mixture of propylene and ethylene in the pre-sence of a stereospecific polymerization catalyst, with the ethylene content of the block copolymer being from about five to ten mole percent, the core layer having a thickness of from about 30 to about 90 percent of the thickness of the film, and each skin layer having a thickness of from about 5 to about 35 percent of the thickness of the film.
2. The film of claim 1, having a thickness of from about one to about two mils.
3. The film of claim 2, wherein the core layer has a thickness of from about 50 to 70 percent of the thickness of the film and each skin layer has a thickness of from about 15 to 25 percent of the thickness of the film.
4. The film of claim 3, wherein the thicknesses of the skin layers are the same.
5. The film of claim 4, wherein the core layer includes recycled trim.
6. The film of claim 5, wherein the skin layer is polypropylene.
7. The film of claim 6, wherein the skin layer is an ethylene-propylene copolymer having an ethylene content of up to four mole percent.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US73485376A | 1976-10-22 | 1976-10-22 | |
| US734,853 | 1991-07-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1103140A true CA1103140A (en) | 1981-06-16 |
Family
ID=24953347
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA287,308A Expired CA1103140A (en) | 1976-10-22 | 1977-09-22 | Trilaminate film for forming sideweld bags |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1103140A (en) |
| GB (1) | GB1532180A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5625445A (en) * | 1979-08-09 | 1981-03-11 | Sumitomo Bakelite Co | Polypropylene laminated sheet and its molding |
| US4384024A (en) | 1981-03-19 | 1983-05-17 | Imperial Chemical Industries Limited | Composite heat-sealable films |
| JP3243585B2 (en) * | 1993-06-28 | 2002-01-07 | 住友化学工業株式会社 | Multilayer film for packaging |
-
1977
- 1977-09-22 CA CA287,308A patent/CA1103140A/en not_active Expired
- 1977-09-29 GB GB40570/77A patent/GB1532180A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB1532180A (en) | 1978-11-15 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4276330A (en) | Trilaminate film for forming sideweld bags | |
| US4390385A (en) | Heat sealable, multi-ply polypropylene film | |
| US4303708A (en) | Heat-sealable plastic film, process for its manufacture, and the use of the film | |
| US4643945A (en) | Heat sealable blend of polypropylene terpolymers and linear low density polyethylene | |
| EP0255622B1 (en) | Heatsealable multilayer polyolefine films | |
| EP0760828B1 (en) | Improved propylene copolymer heat seal resin and articles therefrom | |
| GB2110700A (en) | Polymeric films having one-sided cling and compositions useful in their preparation | |
| DE2637978B2 (en) | Heat-sealable plastic film and process for its production | |
| US3536644A (en) | Means for providing biaxially oriented polypropylene films with improved physical properties | |
| CA1103140A (en) | Trilaminate film for forming sideweld bags | |
| JPS6142626B2 (en) | ||
| EP0858395A1 (en) | Heat-shrinkable multi-layer film | |
| US5110686A (en) | Low temperature heat shrinkable film and process for producing the same | |
| US3218224A (en) | Laminates of olefin polymer films | |
| JPS6031672B2 (en) | Polypropylene biaxially stretched composite film | |
| KR100528043B1 (en) | Anisotropic elastic films and webs | |
| IE51291B1 (en) | Heat-sealable multiply polypropylene film | |
| DE3726265A1 (en) | PACKINGS MADE OF STRETCHED SEALABLE MULTILAYER FILMS WITH IMPROVED TRANSPARENCY | |
| KR102209243B1 (en) | Lightweight bread packaging material and manufacturing method thereof | |
| US6191218B1 (en) | Method for improving hot tack in blown polyethylene films | |
| JPS6225102B2 (en) | ||
| JP2006103147A (en) | Laminated film | |
| JPH0911404A (en) | Multilayer sheet and manufacture thereof | |
| JPH06115027A (en) | Laminated stretch shrink film | |
| EP0338048A1 (en) | Polymeric films |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |