WO1992021719A1 - Film d'emballage ameliore - Google Patents
Film d'emballage ameliore Download PDFInfo
- Publication number
- WO1992021719A1 WO1992021719A1 PCT/US1992/003779 US9203779W WO9221719A1 WO 1992021719 A1 WO1992021719 A1 WO 1992021719A1 US 9203779 W US9203779 W US 9203779W WO 9221719 A1 WO9221719 A1 WO 9221719A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- film
- wax
- slip
- additive
- composition
- Prior art date
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
- C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L23/10—Homopolymers or copolymers of propene
- C08L23/14—Copolymers of propene
- C08L23/142—Copolymers of propene at least partially crystalline copolymers of propene with other olefins
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/18—Manufacture of films or sheets
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
- C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L23/04—Homopolymers or copolymers of ethene
- C08L23/08—Copolymers of ethene
- C08L23/0807—Copolymers of ethene with unsaturated hydrocarbons only containing more than three carbon atoms
- C08L23/0815—Copolymers of ethene with aliphatic 1-olefins
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
- C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
- C08J2323/10—Homopolymers or copolymers of propene
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2205/00—Polymer mixtures characterised by other features
- C08L2205/03—Polymer mixtures characterised by other features containing three or more polymers in a blend
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
- C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L23/04—Homopolymers or copolymers of ethene
- C08L23/06—Polyethene
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L91/00—Compositions of oils, fats or waxes; Compositions of derivatives thereof
- C08L91/06—Waxes
Definitions
- This invention relates to propylene polymer composition which can be made into a film for packaging articles at elevated temperatures without the packaged articles sticking to one another after exposure to such elevated temperatures.
- U. S. patent 2,499,486 discloses the incorporation of di-2 ethyl hexyl phthalate and carnauba wax into polyethylene in order to obtain polyethylene film of improved clarity.
- the amount of these additives used is one-half to two and three parts, respectively, per 100 parts of polyethylene.
- U. S. patent 2,525,671 discloses the use of 0.1 to 3.0% of an ester wax, such as carnauba wax, as a slip additive for vinylidene chloride/acrylonitrile copoly er film.
- U. S. patent 2,711,996 discloses an additive system to film of vinylidene chloride copolymer which provides both slip and freedom from hot stick, so that the film can be used in heat sealing machines.
- the additive system is 0.2 to 1.0 weight percent of a long chain aliphatic polar compound, such as stearic acid, stearyl stearamide, and ontan wax, 0.2 to 1.0 weight percent of ester wax, natural or synthetic, such as carnauba wax and stearyl stearate, and 0.05 to 2.0 weight percent calcium carbonate.
- U. S. patent 4,590,125 discloses a multilayer film of a base layer of polypropylene of high stereoregularity surrounded by heat sealable skins of polyolefin of low stereoregularity, examples of such polyolefin being propylene polymers such as propylene/ethylene copolymer and propylene/ethylene/l- butene copolymer.
- the base layer contains a slip additive which "blooms" through the heat sealing layers, and the heat sealing layer contains 5 to 15 weight percent of microcrystalline wax and 0.05 to 0.5 weight percent of anti-blocking additive.
- the resultant film is disclosed to be useful in high speed packaging machines wherein heat sealing is used. ⁇ . S.
- patent 4,325,859 discloses an improvement to polyolefin film, wherein combination of an anti-block agent, a slip agent and a plasticizing oil exhibits a synergistic effect in enabling the anti-block agent and the slip agent to be used without adversely affecting the optical characteristics of the film
- propylene polymer can either be used as heat shrinkable film or as the outer layer of a multilayer heat shrinkable film.
- the propylene polymer can contain slip and anti-blocking additives such as eruca ide and finely divided silica, respectively.
- the anti-blocking additive enables the film to be unrolled after it has been rolled-up for storage and handling.
- the slip additive enables the film to be handled in the packaging operation so as not to stick to itself when wrapped around the article to be packaged and not to stick to machinery surfaces. After wrapping the film around the article, the wrapped package is subjected to heat to shrink the film onto the package. While the
- the present invention substantially solves the problem described above.
- This solution is applied in the context of packaging articles at an elevated temperature with film of propylene polymer which contains slip and anti-blocking additive, wherein the packaged articles nevertheless tend to stick together while at the elevated temperature.
- the solution to this problem is the improvement to this packaging process which comprises incorporating into the film a small amount of wax. This small amount of wax will be less than about 0.5% based on the weight of the film. At this low concentration, if the slip additive were omitted from the film, the amount of wax would not be effective as a slip additive. This small amount of wax, however, tends to keep the wrapped articles from sticking to one another during the period of cool down from the exposure to elevated temperature.
- the amount of wax used at the low level indicated is an effective amount to provide this non-stick tendency during this cool down period. This effect is described in terms of non-stick tendency because wax provides the non-stick surface very quickly but not necessarily instantaneously as the wrapped articled begins its cool-down and the non-stick behavior exists during the remainder of the cool-down.
- Another embodiment of the present invention resides in the composition for accomplishing this improvement. .
- composition of the present invention contains propylene copolymer, slip additive, anti ⁇ blocking additive, and wax. These are the essential components of the composition.
- the propylene polymer component is propylene homopolymer or copolymer thereof with a minor amount, e.g. , less that about 20 weight percent, of at least one other ethylenically unsaturated copolymerizable monomer.
- a preferred copolymer is propylene/ethylene wherein about 2 to 6 weight percent, and more preferably about 3 to 5 weight percent, of the copolymer is ethylene.
- the propylene copolymer will have sufficiently high molecular weight to form a film which has toughness so that it can be used in the packaging context. Typically the melt flow index of the propylene polymer will be about 1.5 to 10 g/10 min.
- the slip additive can be selected from a wide variety of additives known for producing this effect in propylene copolymer.
- One group of such additives is the amides of a a carboxylic acid having from 8 to 24 carbon atoms and the bisamides thereof.
- the typical such amides will be water insoluble and except in the case of bisamides, amides of onocarboxylic acids. Examples of such amides are erucamide, olea ide, stearamide, behenamide, and N,N'-ethylene bis-stearamide.
- Additional examples of slip additive include sorbitol monostearate and glycerol monostea ' rate.
- the amount of slip additive in the composition will generally be about 0.02 to 0.3% based on the weight of the composition. Greater amounts of the slip additive tend to detract from the properties or appearance of the film made from the composition.
- the anti-blocking additive is any finely divided inert inorganic material, preferably having a mean particle size of about 0.5 to 5 microns.
- examples of such additives include silica, glasses, and clay.
- the amount of this additive in the composition will generally be about 0.05 to 0.5 weight percent.
- the formation of the composition of propylene copolymer and slip and anti-blocking additives can be done by conventional means, such as by melt blending these components in the extruder which forms the film used for the packaging. Prior to melt blending these components, they may be dry blended.
- the film can be formed from the molten composition by conventional means, such as the "trapped bubble" technique, wherein the film is extruded in the form of a tube, followed by expanding the tube radially to orient the film in the transverse direction and winding up the expanded film at a faster rate than the extrusion rate to orient the film in the machine direction. The drawing of the film in the transverse and machine directions is done at a temperature at which orientation occurs.
- the film is drawn at least 3X in both the transverse and the machine directions.
- the film is wound up in the drawn state (after the expanded tubing is longitudinally slit so as to yield flat film) so that it is shrinkable upon heating.
- the film is wrapped around the article and the resultant package is passed through a "shrink tunnel", wherein heating is applied to shrink the film tightly around the article.
- the temperature within the shrink tunnel will be about 170 to 190°C applied for a period of about 1 to 3 seconds, and the cool-down period for the film wrapping after exiting the shrink tunnel is about 2 to 20 seconds to reach the condition when the film will no longer stick to itself.
- the film can shrink at least about 20% in both the transverse and machine directions.
- the film can be a monolayer film, i.e., unsupported prior to wrapping around the article, or the film can be supported, i.e., the outer layer(s) of a multilayer film, with the inner layer(s) contributing to the heat shrinkage property and such other properties as oxygen or moisture barrier of the overall film.
- the film of the composition of the present invention will have a thickness of about 0.1 to 2 mils, and any multilayer film in which this film is present will have an overall thickness of about 0.5 to 4 mils.
- the multilayer film can be made by the same extrusion process described above wherein, however, the layers forming the multilayer film are coextruded together.
- the slip additive can be melt blended with the propylene polymer, especially if it will be a monolayer film, or to an interior layer of a multilayer film wherein the propylene polymer will form the surface layer(s) .
- some of the slip additive will "bloom" into and through the propylene polymer layer and be present at its outer surface to provide the slip behavior.
- the polymer present in the interior layer will already contain both slip and anti-blocking additive so that such polymer is capable of forming into a monolayer film.
- small amounts of these additives may be present in or added to the propylene polymer so as to complement the amount of these additives which bloom from the interior layer to the outer surface of the propylene polymer layer. In either case, the total amount of these additives present in the overall film is small so as not to adversely affect the properties thereof, and the amount of these additives actually present in the propylene polymer layer(s) will generally fall within the compositional ranges set forth above. 7
- the wrapped articles during the short period of cool- down after exiting the heat shrinkage tunnel tend to stick together if these packages come into contact with one another unless the wax component is present in the film in accordance with the present invention.
- the slip and anti-blocking additives work fine to prevent the film from sticking to itself up to the time of heat shrinking. During cool-down from heat shrinking, if the packages come into contact with one another, they tend to stick together, film-to-film, interfering with the. smooth operation of the packaging operation.
- the cool-down period includes the time for the heated film to reach room temperature and also any residence time at room temperature before the slip additive begins functioning as such again.
- the slip additive having lost its ability to confer slip behavior to the film during exposure to heat shrinking temperature returns to provide this behavior shortly after exposure to such temperature, e.g., generally within 20 seconds.
- the wax additive functions in accordance with the present invention to confer slip behavior to the film during this cool-down period.
- the slip effect of the wax becomes evident almost immediately after the cool-down begins, e.g., within one-half to eight seconds.
- delay for the film to exhibit slip behavior is greatly reduced by using the wax additive in accordance with the present invention. How fast this reduction will occur will depend on such factors as the particular propylene polymer being used and identity and amount of wax additive. In any event, the reduction in this delay is usually at least 50%, meaning that packaging equipment can be operated faster and more 21719 8
- wax is incorporated into the propylene copolymer film along with the slip and anti-blocking additives (or the slip additive will become present in the film by blooming from an interior layer of a multilayer film) .
- the wax can be incorporated into an interior layer of a multilayer film and the wax will become incorporated in the outer propylene polymer layer by migration (blooming) from the interior layer to the outer layer.
- the amount of wax used in either case is very small, viz. less than about 0.5 weight percent. At least about 0.001 weight percent is required for appreciable non-stick effect.
- the amount of wax will depend on the particular wax used and will be an amount within this range which is effective to reduce the tendency of the articles wrapped with the film from sticking together at elevated temperatures used.
- the heat shrinking of the film will generally be carried out at about 160 to 190°C and more often about 170 to 180°C. It is during the cool-down from these temperatures and this heat shrinking operation that the movement of the wrapped articles can cause them to contact one another.
- the danger of the wrapped articles contacting one another arises after the wrapped articles exit the heat shrinking zone (tunnel) and the cool-down period has begun.
- the improvement of the present invention will tend to prevent them from sticking together during the remainder of the cool-down period. How soon the "slip" time occurs for a given composition.
- wax examples include the natural and synthetic waxes, preferably those which have a melting point of at least about 45°C and more preferably at least about 65°C and in which most of any acid groups present in the wax are esterified, typically called ester waxes.
- ester waxes include carnauba and candelilla waxes and mineral waxes such as montan wax, petroleum waxes such as paraffin and macrocrystalline waxes, and Fischer-Tropsch waxes.
- the amount of wax that will be effective will be about 0.002 to 0.05 weight percent.
- the amount of wax used will generally be insufficient to provide the needed slip property of the film prior to reaching the shrink tunnel.
- the wax component can be incorporated into the propylene copolymer composition by grinding up the wax and dry mixing it with the copolymer which will generally be in molding granule form.
- the wax can be melted and thereby mixed as a liquid with the copolymer and other additives, which upon cooling. produces a dry blend to be fed to the extruder. Within the extruder further mixing and dispersion of the wax within the melt occurs.
- the wax should be sufficiently thermally stable that it does not decompose to cause spots or discoloration of the film.
- a heat shrinkable film was made by the "trapped bubble" technique.
- the film was a monolayer film of ethylene/propylene copolymer in which the ethylene content was 3.5 weight percent and the melt flow index (at 230°C) of the copolymer was 4 g/10 min.
- Melt blended with the copolymer layer was 0.15 weight percent erucamide slip additive, 0.25 weight percent finely divided silica anti-blocking additive, and 0.005 weight percent of carnauba wax.
- the resultant film was 1 mil (0.025 mm) thick and had in excess of 20% heat shrinkage in the machine and transverse directions.
- the following example is of a multilayer heat shrinkable film:
- the film was a symmetrical five-layer film.
- the core layer consisted of (a) 10 weight percent of ethylene propylene copolymer having 3.5 weight percent ethylene and melt flow index at 230°C of 3.5,
- Two tie layers were present, one on each side of the core layer, and each tie layer consisted of the same polymers as the core layer but in the following concentrations: 47 weight percent of the ethylene/propylene copolymer, 40 weight percent of the ULDPE, and 13 weight percent of the LDPE.
- Two outer layers were present, one on each surface of the film and adhered to the core layer by a tie layer. Each outer layer was comprised of the ethylene/propylene copolymer present in the core layer.
- Each outer layer constituted 15% of the overall thickness (0.015 mm) of the film.
- Each tie layer constituted 11% of the thickness, and the core layer constituted 48% of the overall film thickness.
- One multilayer film as just described had 0.02 weight percent of candelilla wax and 0.02 weight percent carnauba wax added to each in each outer layer composition (film A) , while another multilayer film as just described had no wax additive to the outer layers (film B) .
- Each of these films contain ⁇ 0.21 weight percent of erucamide and 0.13 weight percent of silica distributed (initially) between the core, tie, and outer 12
- the weight percent of slip, anti-blocking and wax additives described herein is based on the total weight of the layer (or monolayer film) composition, i.e., weight of the copolymer plus additive.
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Crystallography & Structural Chemistry (AREA)
- Laminated Bodies (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US70685491A | 1991-05-29 | 1991-05-29 | |
US706,854 | 1991-05-29 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1992021719A1 true WO1992021719A1 (fr) | 1992-12-10 |
Family
ID=24839341
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1992/003779 WO1992021719A1 (fr) | 1991-05-29 | 1992-05-12 | Film d'emballage ameliore |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0586610A1 (fr) |
CA (1) | CA2103057A1 (fr) |
WO (1) | WO1992021719A1 (fr) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0906731A3 (fr) * | 1997-10-01 | 2000-12-20 | Johnson & Johnson Medical Mfg. SDN. BHD. | Gant médical sans poudre et son procédé de fabrication |
US10731016B2 (en) | 2016-07-18 | 2020-08-04 | Conopco, Inc. | Method of modifying the dispensing properties of a container |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2055688A (en) * | 1979-07-13 | 1981-03-11 | Toyo Boseki | Packaging product and the production thereof |
US4325850A (en) * | 1979-05-21 | 1982-04-20 | W. R. Grace & Co. | Processing and product enhancement additives for polyolefin film |
EP0189242A2 (fr) * | 1985-01-24 | 1986-07-30 | Mobil Oil Corporation | Film multicouche soudable à chaud et son procédé de fabrication |
EP0201798A2 (fr) * | 1985-05-11 | 1986-11-20 | Wolff Walsrode Aktiengesellschaft | Feuilles multicouches à base de polyoléfines |
-
1992
- 1992-05-12 WO PCT/US1992/003779 patent/WO1992021719A1/fr not_active Application Discontinuation
- 1992-05-12 CA CA002103057A patent/CA2103057A1/fr not_active Abandoned
- 1992-05-12 EP EP19920917363 patent/EP0586610A1/fr not_active Withdrawn
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4325850A (en) * | 1979-05-21 | 1982-04-20 | W. R. Grace & Co. | Processing and product enhancement additives for polyolefin film |
GB2055688A (en) * | 1979-07-13 | 1981-03-11 | Toyo Boseki | Packaging product and the production thereof |
EP0189242A2 (fr) * | 1985-01-24 | 1986-07-30 | Mobil Oil Corporation | Film multicouche soudable à chaud et son procédé de fabrication |
EP0201798A2 (fr) * | 1985-05-11 | 1986-11-20 | Wolff Walsrode Aktiengesellschaft | Feuilles multicouches à base de polyoléfines |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0906731A3 (fr) * | 1997-10-01 | 2000-12-20 | Johnson & Johnson Medical Mfg. SDN. BHD. | Gant médical sans poudre et son procédé de fabrication |
US10731016B2 (en) | 2016-07-18 | 2020-08-04 | Conopco, Inc. | Method of modifying the dispensing properties of a container |
Also Published As
Publication number | Publication date |
---|---|
CA2103057A1 (fr) | 1992-11-30 |
EP0586610A1 (fr) | 1994-03-16 |
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