CA2316393A1 - Opaque oriented polypropylene film - Google Patents
Opaque oriented polypropylene film Download PDFInfo
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- CA2316393A1 CA2316393A1 CA 2316393 CA2316393A CA2316393A1 CA 2316393 A1 CA2316393 A1 CA 2316393A1 CA 2316393 CA2316393 CA 2316393 CA 2316393 A CA2316393 A CA 2316393A CA 2316393 A1 CA2316393 A1 CA 2316393A1
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- film
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- polymer
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- 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
-
- 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
- B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
- B32B5/18—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by features of a layer of foamed material
-
- 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
- C08J2323/12—Polypropene
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S428/00—Stock material or miscellaneous articles
- Y10S428/91—Product with molecular orientation
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/249921—Web or sheet containing structurally defined element or component
- Y10T428/249953—Composite having voids in a component [e.g., porous, cellular, etc.]
- Y10T428/249978—Voids specified as micro
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/249921—Web or sheet containing structurally defined element or component
- Y10T428/249953—Composite having voids in a component [e.g., porous, cellular, etc.]
- Y10T428/249978—Voids specified as micro
- Y10T428/24998—Composite has more than two layers
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/249921—Web or sheet containing structurally defined element or component
- Y10T428/249953—Composite having voids in a component [e.g., porous, cellular, etc.]
- Y10T428/249986—Void-containing component contains also a solid fiber or solid particle
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/249921—Web or sheet containing structurally defined element or component
- Y10T428/249953—Composite having voids in a component [e.g., porous, cellular, etc.]
- Y10T428/249987—With nonvoid component of specified composition
- Y10T428/249988—Of about the same composition as, and adjacent to, the void-containing component
- Y10T428/249989—Integrally formed skin
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/25—Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
- Y10T428/254—Polymeric or resinous material
Abstract
The present invention relates to an opaque, biaxially oriented polymeric film having a thermoplastic polymer matrix material within which is located a stratum of voids. The voids are formed during orientation by a cavitating agent which is a particle of a cyclic olefinic copolymer. The solid particle is phase-distinct and incompatible with the matrix material.
Description
OPAOUE ORIENTED POLYPROPYLENE FILM
The present invention relates to polypropylene films of high opacity and low light transmission, and particular to oriented films containing voids prepared from a film-forming polymer and particles of cyclic olefinic copolymers (COC) dispersed therein.
In the packaging of certain types of foods, such as snack foods like potato chips, cookies and the like, it is common practice to employ a multilayer film. A
desirable property in such a packaging film is an opacity which protects the packaged product from deterioration 1o caused by exposure to light. In particular, it has been found that certain wavelengths of light, up to 450 nm cause increased spoilage in such packaged products. Even when a degas of opacity is present in the film, spoilage occurs if the film allows passage of some light. One way of increasing opacity in a multilayer film is by providing a layer or stratum of voids which hinders passage of light.
It is known to provide a layer of voids in thermoplastic films by loading cavitating agents in thermoplastic polymer which is cast into a film, and thereafter stretching to form oriented thermoplastic films. Different cavitating agents can be employed under particular processing conditions to obtain desired opaque, oriented polymeric films.
Attempts to vary the types of cavitating agents have been made to improve opacity and machinability of oriented polymeric films. For example, U.S. Patent Nos.
4,758,462, and 5,176,954, disclose the use of organic polymers such as polybutylene terephthalates as cavitating agents in oriented polypropylene matrix materials. U. S. Patent No.
4,758,462 to Park et al., relates to polymeric films of enhanced opacity and methods of making the same.
The films of the '462 patent are made with a thermoplastic polymer matrix material within which is located a stratum of voids. The voids can be created by polybutylene terephthalate cavitating agents. _ U. S. Patent No. 5,176,954 to Keller et al., is directed to a non-symmetrically layered, 3o highly opaque, biaxially oriented polymer film having a core layer which contains polybutylene terephthalate cavitating agents, as well as iron oxide, aluminum and titanium dioxide.
The polybutylene terephthalates described in the above patents, are good cavitating agents that can be processed at high temperatures (i.e., temperatures higher than the melting point of the matrix material). Polybutylene terephthalates, however, are sensitive to hydrolytic breakdown, and thus can degrade into lower molecular weight materials. These low molecular weight materials have been known to migrate to surfaces of processing apparatus, e.g., melt pipes, filters, dies, etc. These materials build up and can then eventually slough offthe metal surfaces and pass into the films as sizable deposits of hard, eggshell-type impurities which cause the film to split.
to Nylon cavitating agents, on the other hand, are not as likely to undergo hydrolytic breakdown and dispersion. However, nylon cavitating agents cannot generally be used at high temperatures. For example, U.S. Patent No. 4,377,616 discloses that when nylons are used as cavitating agents in a polymeric matrix, the drawing temperature of the film can be quite close to the melting point of the polymeric matrix material.
Attempts have also been made to use other cavitating agents with a polymeric matrix to produce opaque, oriented films. In U. S. Patent Nos. 5,134,173 and 5,188,777 to Joesten et al., cross-linked polystyrenes are used as cavitating agents to make opaque, biaxially oriented polymeric films.
The present invention overcomes shortcomings of the prior art and improves the manufacturing capability for making biaxially oriented polymeric films which are provided with opacity by use of cavitating agents.
The present invention is an opaque, biaxially oriented polymeric film having a thermoplastic polymer matrix material within which is located a stratum of voids. The voids are formed during orientation by a cavitating agent which is a particle of a cyclic olefinic copolymer. The solid particle is phase-distinct and incompatible with the matrix material.
3o The thermoplastic matrix polymer, of which the opaque film of this invention is composed, can be any thermoplastic polymer which is incompatible with cavitating agents of WO 99/33647 PCT/US98/~6010 cyclic olefinic polymers. Preferably, the polymeric matrix material is a polyolefin such as polyethylene, polypropylene, polybutylene, etc. The most preferred polyolefin is polypropylene.
The cavitating agent of the present invention is a cyclic olefinic copolymer formed by copolymerizing a cyclic olefin with an aliphatic olefin in the presence of metallocene or Ziegler-Natta catalysts. The cyclic olefinic copolymer of the present invention has a transition temperature identified as Heat Deflection Temperature (HDT) of 75°C -220°C, more preferably, 130°C to I80°C. Typical grades ofsuch cyclic olefin copolymers are Topaz resins 6015 and 6017, obtained from Ticona, the technical polymers business of Hoechst.
to Examples of the cyclic olefin monomers that can be used in the copolymers include, but are not limited to, C4 to C~Z cyclic olefins, including substituted norbornenes.
Examples of the aliphatic comonomers include, but are not limited to ethylene, 15 propylene, and butylene, preferably ethylene.
The polymeric film of the present invention can optionally have at least one void-free thermoplastic skin layer on at least one of its surfaces.
2o As a result, the present invention advantageously provides an opaque, bisxially oriented polymeric film containing cavitating agents of cyclic olefinic copolymer which do not undergo hydrolytic breakdown during manufacture. This reduces deposition of unwanted low molecular weight materials, thereby improving processability, reducing manufacturing costs and improving film quality. Additionally, the film of the present invention can advantageously be processed at 25 high temperatures without undergoing hydrolytic breakdown.
For a better understanding of the present invention, together with other and further objects, reference is made to the following description and its scope will be pointed out in the appended claims.
The present invention relates to an opaque, biaxially oriented polymeric film having a thermoplastic polymer matrix material within which is located a stratum of voids. The voids are formed during orientation by a cavitating agent which is a particle of a cyclic olefinic copolymer. The solid particle is phase-distinct and incompatible with the matrix material.
The film of the present invention has been described above as having a thermoplastic polymer matrix material within which is located a stratum of voids. From this it is to be understood that the voids are a dispersed phase in the matrix configuration.
The term "stratum"
is intended to convey the understanding that there are many dispersed voids in the matrix and to the voids themselves are oriented so that the two major dimensions are aligned in correspondence with the directions of orientation of the polymeric film structure.
Cavitating agents are void initiating particles that are incompatible with, or have very low compatibility with, the polymer that constitutes the essentially continuous phase of the matrix. The void initiating particles constitute a dispersed phase that will, ultimately, upon orientation, form a stratum of voids in the polymeric matrix.
After each void has been formed through the cavitation caused by the described particle, the particle generally contributes little else to the system. This is because its refractive index can 2o be close enough to the refractive index of the polymer that constitutes the essentially continuous phase of the matrix that it makes no contribution to opacity. When this is the case, the opacity is principally a function of the light scattering effect which occurs because of the existence of the voids in the system.
The typical void of the resultant film is defined as having major dimensions X
and Y, and minor dimension Z, where dimension X is aligned with machine direction orientation, dimension Y is aligned with transverse direction orientation, and dimension Z is aligned in the thickness direction of the film and approximately corresponds to the cross-sectional dimension of the spherical particle which initiated the void.
It is a necessary part of the present invention that the orientation conditions be such that the X and Y dimensions of the voids of the film be major dimensions in comparison to the Z
dimension. Thus, while the Z dimension generally approximates the cross-sectional dimension of the spherical particle initiating the void, X and Y dimensions will be significantly greater.
s The thermoplastic polymer that constitutes the essentially continuous phase of the matrix, of which the greater portion of the opaque film of this invention is comprised, can be any thermoplastic polymer which is °incompatible" with cavitating agents of cyclic olefinic copolymers. The term incompatible means that the two materials ( i.e., thermoplastic polymer to material and cavitating agent} will maintain their identities after they have been mixed above the melting point of the thermoplastic polymer matrix material.
Examples of such thermoplastic polymer matrix material include polyolefins, e.g., polyethylene, polypropylene, polybutylene, etc. Distinct species of these materials are ~s copolymers of ethylene with alpha-olefins, e.g., butene, hexene, etc., random copolymers of propylene with another olefin, e.g., ethylene, butene, hexene, etc., and any blends or mixtures of the same. Particularly preferred as the matrix polymer is isotactic polypropylene. Typical polypropylene homopolymers used commercially include PP4612E2, obtained from Exxon Corp. and 10-6371, obtained from Amoco Chemical Co.
The cavitating agent of the present invention is a cyclic olefinic copolymer formed by copolymerizing a cyclic olefin with an aliphatic olefin in the presence of metatlocene or Ziegler-Natta catalysts. Typical grades of such cyclic olefin copolymers are Topaz resins 6015 and b017, obtained from Ticona, the technical polymers business of Hoechst.
2s The copolymerization of the cyclic olefin and the aliphatic olefin can be prepared by appropriate means known in the art.
Typically, the polymerization is conducted in a reaction medium conducive to interaction of a metallocene catalyst and the desired monomers. Thus, a slurry of a metallocene catalyst in liquid aliphatic olefin may serve as the reaction medium. Similarly, a solution process using typical hydrocarbon solvents will be suitable, preferably the solvent is one of aromatic or cycloaliphatic hydrocarbon compounds, but linear or branched aliphatic compounds will also be suitable. Suitable solvents include conventional solvents known in the art, such as benzene, toluene, xylene, ethylbenzene, cyclopentane, cyclohexane, methylcyclohexane, pentane, hexane, heptane, octane, mineral oil, blends of solvents, etc.
The aliphatic olefin of the present invention is the primary monomer. Examples of the primary monomer include ethylene, propylene, and butylene, preferably ethylene.
to The resultant cyclic oIefinic copolymer has a transition temperature, typically described as a Heat Deflection Temperature (HDT) suitably close to the melting point of the thermoplastic polymer that constitutes the essentially continuous phase of the matrix to allow solidification from the melt into a separate phase of small particles dispersed in the continuous polymeric matrix. The HDT ofthe cyclic olefinic copolymer is 75°C to 220°C, preferably 15 130°C to 180°C, more preferably, 150°C to 170°C.
The resultant cyclic olefinic copolymers produced can be reasonably easily dispersed in the polymer matrix, and are reasonably incompatible with the polymer that constitutes the essentially continuous phase of the matrix so that the forces pulling on the polymers during the 20 orientation steps will create a rupture at the interface between the two polymers. The cyclic olefinic copolymers can be reclaimed back into production, and do not degrade into unwanted by-products at the conditions of the process.
Because of the film core cavitation resulting from the cyclic olefinic copolymer, the 25 present invention provides a light transmission of less than 40% and an opacity of at least 10%.
More preferably light transmission will be less than 25% and opacity will be at least 75%.
The film of the present invention has very high opacity and very low light transmission.
A distinction must be made between opacity and light transmission for the purposes of this 3o invention. Opacity is the opposite of transparency and is a function of the scattering and reflection of light transmitted through the film. Opacity of a film is the ability, for example, to block out writing underneath the film. Light transmission is a function of light passing more directly through the film. Accordingly, a highly reflective film may provide high opacity while allowing light transmission. This is because percent light transmission is not the obverse of percent opacity.
Light transmission is the amount of light passing directly through the film.
To prevent food spoilage, decreased light transmission is desirable. Prevention of light transmission in shorter UV wavelengths up to 400 nm and the blue-violet range of from 400 to 450 nm is particularly desirable for this purpose.
to The film of the present invention can be prepared by any manner well known in the art, preferably by coextrusion. The polymer that constitutes the essentially continuous phase of the matrix and the cyclic olefinic copolymer that are to be extruded into a film may be prepared by thoroughly mixing the constituent materials at a temperature above the melting point of the 15 matrix polymer. Such mixing may be conveniently accomplished on the extn.~der utilized to form the initial film which is subsequently biaxially oriented.
The cyclic olefinic copolymer can be present in the resultant film, for example, in up to 30% by weight of the cavitated layers of the film, preferably from 3 to 15% by weight, more 2o preferably from S to 12% by weight.
In forming the thermoplastic polymer matrix, as in U.S. Patent No. 4,377,616, the disclosure of which is incorporated herein by reference in its entirety, a master batch technique can be employed in creating the void initiating particles in situ. After the formation of a master 25 batch, appropriate dilution of the system can be made by adding additional thermoplastic matrix material until the desired proportions are obtained. However, the components may also be directly mixed and extruded instead of utilizing a master batch method.
When a master batch precursor composition is made for ultimate dilution with more 3o polymer that constitutes the essentially continuous phase of the matrix to produce the final film, the master batch can contain as much cyclic olefinic copolymer as can practically be dispersed in the thermoplastic matrix polymer in spherical subdivided particles of a size ranging from 0.1 to microns. With little difficulty, up to 30% by weight of the cyclic olefin copolymer can be dispersed, in this size range, in the matrix.
5 The general method of forming the opaque oriented film of the present invention is accomplished by slot extruding a film consisting of the polymer that constitutes the essentially continuous phase of the matrix and cyclic olefinic copolymer mixed together, and thereafter sequentially biaxially orienting the film. During the orientation a stratum of voids is formed in the matrix. As indicated above, the polymer that constitutes the essentially continuous phase of to the matrix and the void initiating particle must be incompatible, or have very low compatibility, and this term is used in the sense that the materials maintain two distinct phases. The void initiating particles constitute a dispersed phase throughout the lower melting polymer which polymer will, ultimately, upon orientation, become void-filled with the spherical particles positioned somewhere in the voids.
Since the cyclic olefinic copolymer particles are incompatible with the polymer that constitutes the essentially continuous phase of the matrix material, during machine direction-orientation each sphere tends to create a streamlined void. During subsequent transverse orientation, the transverse dimension of this void is correspondingly increased. These steps 2o cause the film to generate a bright white, pearlescent, opaque appearance.
In many instances, for improved process operability and in order to minimize the formation of an irregular surface as a result of the spheres and the cavitated condition of the film, a coextruded skin layer can be formed on one or both surfaces of the cavitated layer. This coextruded skin layer can be transparent or pigmented and of the same or different material as the polymer matrix. The different material may be chosen for particular characteristics, for example, film strength and integrity, heat sealability, printability, machinability, etc. Further coextruded layers can be produced on one or both surfaces of the multi-layer films. The material for these layers may again be chosen for particular characteristics, such as film strength 3o and integrity, heat sealability, printability, machinability, etc.
When employing a surface or skin layer or layers, it is preferred that the core thickness be from 30% to 95% of the overall structure. Conversely, it is preferred that the combined skin thickness be 5 to 70% of the overall film thickness. When desired or necessary, the skin layers can be sufficiently thick so that the outer surfaces thereof do not manifest any irregularities or surface projections of the core material The film of the present invention has a thickness ranging from 12.7 microns to 102.8 microns, preferably from 17.7 microns to 76.2 microns, and more preferably from 20.3 microns to 63.5 microns.
to As a result of the biaxial orientation of the film structure herein, in addition to opacifying the core layer of the structure, the orientation improves other physical properties of the composite layers such as flex-crack resistance, Elmendortf tear strength, modulus, elongation, tensile strength, impact strength, etc. The resulting film can have, in addition to a rich high quality appearance and excellent opacifying characteristics, low water vapor transmission rate characteristics and low oxygen transmission rate characteristics. This makes the film ideally suited for packaging food products including liquids.
It is believed that the voids are closed cells. This means that there is virtually no path open from one side of the core to the other through which liquid or gas can traverse.
EXAMPLES
The following examples illustrate the present invention. Example 1 below is a comparative example illustrating the light transmission of the prior art films. Examples 2 and 3 illustrate the properties exhibited by the films of the present invention.
COMPARATIVE EXAMPLE
A white film with a cavitated core was tested for light transmission. The film had a cavitated isotactic polypropylene (PP) core with 5% polybutylene telephthalate (PBT) filler and 5 skins of PP homopolymer, in a thickness of 5 microns, on each side. Total cavitated film thickness was 40.6 microns.
The film had a light transmission of 25.8%. Opacity was 85.1%.
lp EXAMPLE 2 A white film with a cavitated core was produced, using 8% of a COC having a 170°C
I~T dispersed in an isolactic polypropylene homopolymer matrix. All other conditions were essentially the same as in Example 1. The cavitated film thickness was 3 8.1 microns. The light transmission was 20.9% and the opacity was 87.9%.
A white film with a cavitated core was produced, using 20% of a COC having a 150°C
I-iDT dispersed in an isotactic polypropylene homopolymer matrix. All other conditions were essentially the same as in Example 1. The cavitated film thickness was 40.6 microns. The light 2o transmission was 20% and the opacity was 87.9%.
While there have been described what are presently believed to be the preferred embodiments of the invention, those skilled in the art will realize that various changes and modifications may be made to the invention without departing from the spirit of such invention.
All such changes and modifications which fall within the scope of the invention are therefore intended to be claimed.
The present invention relates to polypropylene films of high opacity and low light transmission, and particular to oriented films containing voids prepared from a film-forming polymer and particles of cyclic olefinic copolymers (COC) dispersed therein.
In the packaging of certain types of foods, such as snack foods like potato chips, cookies and the like, it is common practice to employ a multilayer film. A
desirable property in such a packaging film is an opacity which protects the packaged product from deterioration 1o caused by exposure to light. In particular, it has been found that certain wavelengths of light, up to 450 nm cause increased spoilage in such packaged products. Even when a degas of opacity is present in the film, spoilage occurs if the film allows passage of some light. One way of increasing opacity in a multilayer film is by providing a layer or stratum of voids which hinders passage of light.
It is known to provide a layer of voids in thermoplastic films by loading cavitating agents in thermoplastic polymer which is cast into a film, and thereafter stretching to form oriented thermoplastic films. Different cavitating agents can be employed under particular processing conditions to obtain desired opaque, oriented polymeric films.
Attempts to vary the types of cavitating agents have been made to improve opacity and machinability of oriented polymeric films. For example, U.S. Patent Nos.
4,758,462, and 5,176,954, disclose the use of organic polymers such as polybutylene terephthalates as cavitating agents in oriented polypropylene matrix materials. U. S. Patent No.
4,758,462 to Park et al., relates to polymeric films of enhanced opacity and methods of making the same.
The films of the '462 patent are made with a thermoplastic polymer matrix material within which is located a stratum of voids. The voids can be created by polybutylene terephthalate cavitating agents. _ U. S. Patent No. 5,176,954 to Keller et al., is directed to a non-symmetrically layered, 3o highly opaque, biaxially oriented polymer film having a core layer which contains polybutylene terephthalate cavitating agents, as well as iron oxide, aluminum and titanium dioxide.
The polybutylene terephthalates described in the above patents, are good cavitating agents that can be processed at high temperatures (i.e., temperatures higher than the melting point of the matrix material). Polybutylene terephthalates, however, are sensitive to hydrolytic breakdown, and thus can degrade into lower molecular weight materials. These low molecular weight materials have been known to migrate to surfaces of processing apparatus, e.g., melt pipes, filters, dies, etc. These materials build up and can then eventually slough offthe metal surfaces and pass into the films as sizable deposits of hard, eggshell-type impurities which cause the film to split.
to Nylon cavitating agents, on the other hand, are not as likely to undergo hydrolytic breakdown and dispersion. However, nylon cavitating agents cannot generally be used at high temperatures. For example, U.S. Patent No. 4,377,616 discloses that when nylons are used as cavitating agents in a polymeric matrix, the drawing temperature of the film can be quite close to the melting point of the polymeric matrix material.
Attempts have also been made to use other cavitating agents with a polymeric matrix to produce opaque, oriented films. In U. S. Patent Nos. 5,134,173 and 5,188,777 to Joesten et al., cross-linked polystyrenes are used as cavitating agents to make opaque, biaxially oriented polymeric films.
The present invention overcomes shortcomings of the prior art and improves the manufacturing capability for making biaxially oriented polymeric films which are provided with opacity by use of cavitating agents.
The present invention is an opaque, biaxially oriented polymeric film having a thermoplastic polymer matrix material within which is located a stratum of voids. The voids are formed during orientation by a cavitating agent which is a particle of a cyclic olefinic copolymer. The solid particle is phase-distinct and incompatible with the matrix material.
3o The thermoplastic matrix polymer, of which the opaque film of this invention is composed, can be any thermoplastic polymer which is incompatible with cavitating agents of WO 99/33647 PCT/US98/~6010 cyclic olefinic polymers. Preferably, the polymeric matrix material is a polyolefin such as polyethylene, polypropylene, polybutylene, etc. The most preferred polyolefin is polypropylene.
The cavitating agent of the present invention is a cyclic olefinic copolymer formed by copolymerizing a cyclic olefin with an aliphatic olefin in the presence of metallocene or Ziegler-Natta catalysts. The cyclic olefinic copolymer of the present invention has a transition temperature identified as Heat Deflection Temperature (HDT) of 75°C -220°C, more preferably, 130°C to I80°C. Typical grades ofsuch cyclic olefin copolymers are Topaz resins 6015 and 6017, obtained from Ticona, the technical polymers business of Hoechst.
to Examples of the cyclic olefin monomers that can be used in the copolymers include, but are not limited to, C4 to C~Z cyclic olefins, including substituted norbornenes.
Examples of the aliphatic comonomers include, but are not limited to ethylene, 15 propylene, and butylene, preferably ethylene.
The polymeric film of the present invention can optionally have at least one void-free thermoplastic skin layer on at least one of its surfaces.
2o As a result, the present invention advantageously provides an opaque, bisxially oriented polymeric film containing cavitating agents of cyclic olefinic copolymer which do not undergo hydrolytic breakdown during manufacture. This reduces deposition of unwanted low molecular weight materials, thereby improving processability, reducing manufacturing costs and improving film quality. Additionally, the film of the present invention can advantageously be processed at 25 high temperatures without undergoing hydrolytic breakdown.
For a better understanding of the present invention, together with other and further objects, reference is made to the following description and its scope will be pointed out in the appended claims.
The present invention relates to an opaque, biaxially oriented polymeric film having a thermoplastic polymer matrix material within which is located a stratum of voids. The voids are formed during orientation by a cavitating agent which is a particle of a cyclic olefinic copolymer. The solid particle is phase-distinct and incompatible with the matrix material.
The film of the present invention has been described above as having a thermoplastic polymer matrix material within which is located a stratum of voids. From this it is to be understood that the voids are a dispersed phase in the matrix configuration.
The term "stratum"
is intended to convey the understanding that there are many dispersed voids in the matrix and to the voids themselves are oriented so that the two major dimensions are aligned in correspondence with the directions of orientation of the polymeric film structure.
Cavitating agents are void initiating particles that are incompatible with, or have very low compatibility with, the polymer that constitutes the essentially continuous phase of the matrix. The void initiating particles constitute a dispersed phase that will, ultimately, upon orientation, form a stratum of voids in the polymeric matrix.
After each void has been formed through the cavitation caused by the described particle, the particle generally contributes little else to the system. This is because its refractive index can 2o be close enough to the refractive index of the polymer that constitutes the essentially continuous phase of the matrix that it makes no contribution to opacity. When this is the case, the opacity is principally a function of the light scattering effect which occurs because of the existence of the voids in the system.
The typical void of the resultant film is defined as having major dimensions X
and Y, and minor dimension Z, where dimension X is aligned with machine direction orientation, dimension Y is aligned with transverse direction orientation, and dimension Z is aligned in the thickness direction of the film and approximately corresponds to the cross-sectional dimension of the spherical particle which initiated the void.
It is a necessary part of the present invention that the orientation conditions be such that the X and Y dimensions of the voids of the film be major dimensions in comparison to the Z
dimension. Thus, while the Z dimension generally approximates the cross-sectional dimension of the spherical particle initiating the void, X and Y dimensions will be significantly greater.
s The thermoplastic polymer that constitutes the essentially continuous phase of the matrix, of which the greater portion of the opaque film of this invention is comprised, can be any thermoplastic polymer which is °incompatible" with cavitating agents of cyclic olefinic copolymers. The term incompatible means that the two materials ( i.e., thermoplastic polymer to material and cavitating agent} will maintain their identities after they have been mixed above the melting point of the thermoplastic polymer matrix material.
Examples of such thermoplastic polymer matrix material include polyolefins, e.g., polyethylene, polypropylene, polybutylene, etc. Distinct species of these materials are ~s copolymers of ethylene with alpha-olefins, e.g., butene, hexene, etc., random copolymers of propylene with another olefin, e.g., ethylene, butene, hexene, etc., and any blends or mixtures of the same. Particularly preferred as the matrix polymer is isotactic polypropylene. Typical polypropylene homopolymers used commercially include PP4612E2, obtained from Exxon Corp. and 10-6371, obtained from Amoco Chemical Co.
The cavitating agent of the present invention is a cyclic olefinic copolymer formed by copolymerizing a cyclic olefin with an aliphatic olefin in the presence of metatlocene or Ziegler-Natta catalysts. Typical grades of such cyclic olefin copolymers are Topaz resins 6015 and b017, obtained from Ticona, the technical polymers business of Hoechst.
2s The copolymerization of the cyclic olefin and the aliphatic olefin can be prepared by appropriate means known in the art.
Typically, the polymerization is conducted in a reaction medium conducive to interaction of a metallocene catalyst and the desired monomers. Thus, a slurry of a metallocene catalyst in liquid aliphatic olefin may serve as the reaction medium. Similarly, a solution process using typical hydrocarbon solvents will be suitable, preferably the solvent is one of aromatic or cycloaliphatic hydrocarbon compounds, but linear or branched aliphatic compounds will also be suitable. Suitable solvents include conventional solvents known in the art, such as benzene, toluene, xylene, ethylbenzene, cyclopentane, cyclohexane, methylcyclohexane, pentane, hexane, heptane, octane, mineral oil, blends of solvents, etc.
The aliphatic olefin of the present invention is the primary monomer. Examples of the primary monomer include ethylene, propylene, and butylene, preferably ethylene.
to The resultant cyclic oIefinic copolymer has a transition temperature, typically described as a Heat Deflection Temperature (HDT) suitably close to the melting point of the thermoplastic polymer that constitutes the essentially continuous phase of the matrix to allow solidification from the melt into a separate phase of small particles dispersed in the continuous polymeric matrix. The HDT ofthe cyclic olefinic copolymer is 75°C to 220°C, preferably 15 130°C to 180°C, more preferably, 150°C to 170°C.
The resultant cyclic olefinic copolymers produced can be reasonably easily dispersed in the polymer matrix, and are reasonably incompatible with the polymer that constitutes the essentially continuous phase of the matrix so that the forces pulling on the polymers during the 20 orientation steps will create a rupture at the interface between the two polymers. The cyclic olefinic copolymers can be reclaimed back into production, and do not degrade into unwanted by-products at the conditions of the process.
Because of the film core cavitation resulting from the cyclic olefinic copolymer, the 25 present invention provides a light transmission of less than 40% and an opacity of at least 10%.
More preferably light transmission will be less than 25% and opacity will be at least 75%.
The film of the present invention has very high opacity and very low light transmission.
A distinction must be made between opacity and light transmission for the purposes of this 3o invention. Opacity is the opposite of transparency and is a function of the scattering and reflection of light transmitted through the film. Opacity of a film is the ability, for example, to block out writing underneath the film. Light transmission is a function of light passing more directly through the film. Accordingly, a highly reflective film may provide high opacity while allowing light transmission. This is because percent light transmission is not the obverse of percent opacity.
Light transmission is the amount of light passing directly through the film.
To prevent food spoilage, decreased light transmission is desirable. Prevention of light transmission in shorter UV wavelengths up to 400 nm and the blue-violet range of from 400 to 450 nm is particularly desirable for this purpose.
to The film of the present invention can be prepared by any manner well known in the art, preferably by coextrusion. The polymer that constitutes the essentially continuous phase of the matrix and the cyclic olefinic copolymer that are to be extruded into a film may be prepared by thoroughly mixing the constituent materials at a temperature above the melting point of the 15 matrix polymer. Such mixing may be conveniently accomplished on the extn.~der utilized to form the initial film which is subsequently biaxially oriented.
The cyclic olefinic copolymer can be present in the resultant film, for example, in up to 30% by weight of the cavitated layers of the film, preferably from 3 to 15% by weight, more 2o preferably from S to 12% by weight.
In forming the thermoplastic polymer matrix, as in U.S. Patent No. 4,377,616, the disclosure of which is incorporated herein by reference in its entirety, a master batch technique can be employed in creating the void initiating particles in situ. After the formation of a master 25 batch, appropriate dilution of the system can be made by adding additional thermoplastic matrix material until the desired proportions are obtained. However, the components may also be directly mixed and extruded instead of utilizing a master batch method.
When a master batch precursor composition is made for ultimate dilution with more 3o polymer that constitutes the essentially continuous phase of the matrix to produce the final film, the master batch can contain as much cyclic olefinic copolymer as can practically be dispersed in the thermoplastic matrix polymer in spherical subdivided particles of a size ranging from 0.1 to microns. With little difficulty, up to 30% by weight of the cyclic olefin copolymer can be dispersed, in this size range, in the matrix.
5 The general method of forming the opaque oriented film of the present invention is accomplished by slot extruding a film consisting of the polymer that constitutes the essentially continuous phase of the matrix and cyclic olefinic copolymer mixed together, and thereafter sequentially biaxially orienting the film. During the orientation a stratum of voids is formed in the matrix. As indicated above, the polymer that constitutes the essentially continuous phase of to the matrix and the void initiating particle must be incompatible, or have very low compatibility, and this term is used in the sense that the materials maintain two distinct phases. The void initiating particles constitute a dispersed phase throughout the lower melting polymer which polymer will, ultimately, upon orientation, become void-filled with the spherical particles positioned somewhere in the voids.
Since the cyclic olefinic copolymer particles are incompatible with the polymer that constitutes the essentially continuous phase of the matrix material, during machine direction-orientation each sphere tends to create a streamlined void. During subsequent transverse orientation, the transverse dimension of this void is correspondingly increased. These steps 2o cause the film to generate a bright white, pearlescent, opaque appearance.
In many instances, for improved process operability and in order to minimize the formation of an irregular surface as a result of the spheres and the cavitated condition of the film, a coextruded skin layer can be formed on one or both surfaces of the cavitated layer. This coextruded skin layer can be transparent or pigmented and of the same or different material as the polymer matrix. The different material may be chosen for particular characteristics, for example, film strength and integrity, heat sealability, printability, machinability, etc. Further coextruded layers can be produced on one or both surfaces of the multi-layer films. The material for these layers may again be chosen for particular characteristics, such as film strength 3o and integrity, heat sealability, printability, machinability, etc.
When employing a surface or skin layer or layers, it is preferred that the core thickness be from 30% to 95% of the overall structure. Conversely, it is preferred that the combined skin thickness be 5 to 70% of the overall film thickness. When desired or necessary, the skin layers can be sufficiently thick so that the outer surfaces thereof do not manifest any irregularities or surface projections of the core material The film of the present invention has a thickness ranging from 12.7 microns to 102.8 microns, preferably from 17.7 microns to 76.2 microns, and more preferably from 20.3 microns to 63.5 microns.
to As a result of the biaxial orientation of the film structure herein, in addition to opacifying the core layer of the structure, the orientation improves other physical properties of the composite layers such as flex-crack resistance, Elmendortf tear strength, modulus, elongation, tensile strength, impact strength, etc. The resulting film can have, in addition to a rich high quality appearance and excellent opacifying characteristics, low water vapor transmission rate characteristics and low oxygen transmission rate characteristics. This makes the film ideally suited for packaging food products including liquids.
It is believed that the voids are closed cells. This means that there is virtually no path open from one side of the core to the other through which liquid or gas can traverse.
EXAMPLES
The following examples illustrate the present invention. Example 1 below is a comparative example illustrating the light transmission of the prior art films. Examples 2 and 3 illustrate the properties exhibited by the films of the present invention.
COMPARATIVE EXAMPLE
A white film with a cavitated core was tested for light transmission. The film had a cavitated isotactic polypropylene (PP) core with 5% polybutylene telephthalate (PBT) filler and 5 skins of PP homopolymer, in a thickness of 5 microns, on each side. Total cavitated film thickness was 40.6 microns.
The film had a light transmission of 25.8%. Opacity was 85.1%.
lp EXAMPLE 2 A white film with a cavitated core was produced, using 8% of a COC having a 170°C
I~T dispersed in an isolactic polypropylene homopolymer matrix. All other conditions were essentially the same as in Example 1. The cavitated film thickness was 3 8.1 microns. The light transmission was 20.9% and the opacity was 87.9%.
A white film with a cavitated core was produced, using 20% of a COC having a 150°C
I-iDT dispersed in an isotactic polypropylene homopolymer matrix. All other conditions were essentially the same as in Example 1. The cavitated film thickness was 40.6 microns. The light 2o transmission was 20% and the opacity was 87.9%.
While there have been described what are presently believed to be the preferred embodiments of the invention, those skilled in the art will realize that various changes and modifications may be made to the invention without departing from the spirit of such invention.
All such changes and modifications which fall within the scope of the invention are therefore intended to be claimed.
Claims (8)
1. An opaque, biaxially oriented polymeric film comprising:
a thermoplastic polymer which constitutes an essentially continuous phase of a matrix within which is located a stratum of voids, said voids formed during orientation by a cavitating agent, said agent comprising solid cyclic olefinic copolymer particles which are phase-distinct and essentially incompatible with said matrix.
a thermoplastic polymer which constitutes an essentially continuous phase of a matrix within which is located a stratum of voids, said voids formed during orientation by a cavitating agent, said agent comprising solid cyclic olefinic copolymer particles which are phase-distinct and essentially incompatible with said matrix.
2. The film of Claim 1, wherein said polymer which constitutes said essentially continuous phase of the matrix is polypropylene.
3. The film of Claim 1, wherein said cyclic olefinic copolymer is a cyclic olefin copolymerized with an aliphatic olefin in the presence of metallocene catalysts.
4. The film of Claim 1, wherein said copolymer has a Heat Deflection Temperature of 75°to 220°C.
5. The film of Claim 3, wherein said cyclic olefin is selected from the group consisting of C4 to C12 olefins.
6. The film of Claim3, wherein the aliphatic olefin monomer is ethylene.
7. The film of Claim 3, wherein said aliphatic olefin monomer is selected from the group consisting of ethylene, propylene, and butylene.
8. The film of Claim 1 having on at least one surface thereof a void-free thermoplastic skin layer.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/998,149 US6048608A (en) | 1997-12-24 | 1997-12-24 | Opaque oriented polypropylene film |
| US08/998,149 | 1997-12-24 | ||
| PCT/US1998/026010 WO1999033647A1 (en) | 1997-12-24 | 1998-12-08 | Opaque oriented polypropylene film |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2316393A1 true CA2316393A1 (en) | 1999-07-08 |
Family
ID=25544835
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2316393 Abandoned CA2316393A1 (en) | 1997-12-24 | 1998-12-08 | Opaque oriented polypropylene film |
Country Status (10)
| Country | Link |
|---|---|
| US (1) | US6048608A (en) |
| EP (1) | EP1042118A4 (en) |
| JP (1) | JP2001526982A (en) |
| CN (1) | CN1284025A (en) |
| AR (1) | AR014154A1 (en) |
| AU (1) | AU743697B2 (en) |
| BR (1) | BR9814477A (en) |
| CA (1) | CA2316393A1 (en) |
| TW (1) | TW409135B (en) |
| WO (1) | WO1999033647A1 (en) |
Families Citing this family (24)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1157068A1 (en) * | 1999-05-12 | 2001-11-28 | Exxonmobil Oil Corporation | Method for producing improved opaque polymeric films |
| US6461724B1 (en) | 1999-08-30 | 2002-10-08 | 3M Innovative Properties Company | Microporous material resistant to capillary collapse |
| CN101554932A (en) * | 2000-11-04 | 2009-10-14 | 国家淀粉及化学投资控股公司 | Packaging of low application hot melt adhesive formulations |
| US6706371B2 (en) * | 2000-12-11 | 2004-03-16 | Exxonmobil Oil Corporation | Film with edge trim |
| US6623866B2 (en) | 2001-04-04 | 2003-09-23 | Exxonmobil Oil Corporation | Multilayer films including anti-block |
| US20020182400A1 (en) * | 2001-04-04 | 2002-12-05 | Pang-Chia Lu | Controlled opacity film for viewing in reflected and transmitted light |
| US6641914B2 (en) | 2001-05-29 | 2003-11-04 | Exxonmobil Oil Corporation | HDPE label film |
| EP1295908A1 (en) * | 2001-09-25 | 2003-03-26 | Transpac N.V. | Polymer film with controllable tear behaviour |
| US20030173716A1 (en) * | 2002-02-13 | 2003-09-18 | Pang-Chia Lu | Digital printing system for printing colored polyolefin films |
| US7288304B2 (en) * | 2002-03-15 | 2007-10-30 | Exxonmobil Oil Corporation | Metallized patch labels |
| US20030211309A1 (en) * | 2002-05-08 | 2003-11-13 | Vifan Usa, Inc. | Polypropylene films |
| US6787217B2 (en) | 2002-10-29 | 2004-09-07 | Exxonmobil Oil Corporation | Thermoplastic film label composite with a printable, untreated, cavitated surface |
| US6939602B2 (en) * | 2002-12-31 | 2005-09-06 | Exxonmobil Oil Corporation | Coating for the adhesive-receiving surface of polymeric labels |
| US20060046005A1 (en) * | 2004-08-24 | 2006-03-02 | Mcgee Dennis E | Coating for polymeric labels |
| US20060046006A1 (en) * | 2004-08-31 | 2006-03-02 | Bastion Bradley J | Multilayer polymeric barrier film, flexible packaging made therewith, and methods |
| EP1819510B1 (en) * | 2004-11-29 | 2012-07-04 | Avery Dennison Corporation | Coextruded multilayer colored films |
| US20060121259A1 (en) * | 2004-12-02 | 2006-06-08 | Williams David R | White polymeric film with improved machinability and reduced dusting |
| DE202006001454U1 (en) | 2005-08-04 | 2006-04-20 | Polysack Plastic Industries Ltd. | Stretched polymer foil, useful for e.g. wrapping as label/packing around articles (e.g. bonbon), comprises cyclic olefinic copolymers and/or cyclic olefinic polymers |
| MX2009008216A (en) * | 2007-01-31 | 2009-10-12 | Toray Industries | White polyester film and reflective sheet. |
| US8557919B2 (en) | 2008-11-24 | 2013-10-15 | Exxonmobil Oil Corporation | Polymeric films and method of making same |
| WO2010059448A1 (en) * | 2008-11-24 | 2010-05-27 | Exxonmobil Oil Corporation | Cavitated polymeric films |
| US20130209758A1 (en) | 2010-04-12 | 2013-08-15 | Anne P. CAMPEAU | Coating for Polymeric Labels |
| AU2015214333B2 (en) | 2014-02-10 | 2017-02-23 | Jindal Films Europe Virton Sprl | Multilayer film structures |
| WO2024070916A1 (en) * | 2022-09-26 | 2024-04-04 | 東レ株式会社 | Biaxially-oriented polyolefin film |
Family Cites Families (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4377616A (en) * | 1981-12-30 | 1983-03-22 | Mobil Oil Corporation | Lustrous satin appearing, opaque film compositions and method of preparing same |
| US4758462A (en) * | 1986-08-29 | 1988-07-19 | Mobil Oil Corporation | Opaque film composites and method of preparing same |
| US4720416A (en) * | 1987-03-09 | 1988-01-19 | Mobil Oil Corporation | Pressure sensitive label stock material possessing a wrinkle-resistant lustrous, opaque laminate film facing |
| US5176954A (en) * | 1989-03-16 | 1993-01-05 | Mobil Oil Corporation | High opacity film and method thereof |
| US5082900A (en) * | 1989-03-29 | 1992-01-21 | Chisso Corporation | Opacified molded product |
| CA2012729C (en) * | 1989-04-07 | 1997-05-20 | Takashi Kuroda | Dulled stretched molding and process for producing the same |
| US4965123A (en) * | 1989-12-29 | 1990-10-23 | Mobil Oil Corporation | Opaque oriented polymeric film structure and method of preparing same |
| DE69129405T3 (en) * | 1990-10-05 | 2001-10-04 | Idemitsu Kosan Co | METHOD FOR PRODUCING CYCLOOLEFIN POLYMERS AND CYCLOOLEFIN COPOLYMERS |
| JP3131466B2 (en) * | 1991-07-02 | 2001-01-31 | ユニチカ株式会社 | Lightweight polyester film and method for producing the same |
| US5223346A (en) * | 1991-10-23 | 1993-06-29 | Mobil Oil Corporation | Hdpe/polypropylene film laminates |
| US5188777A (en) * | 1991-11-05 | 1993-02-23 | Mobil Oil Corporation | Opaque film and method for its preparation |
| US5134173A (en) * | 1991-11-05 | 1992-07-28 | Mobil Oil Corporation | Opaque film and method for its preparation |
| JPH05140349A (en) * | 1991-11-15 | 1993-06-08 | Unitika Ltd | Light-weight polyester film and its production |
| JPH05262898A (en) * | 1992-03-23 | 1993-10-12 | Mitsui Petrochem Ind Ltd | Biaxially stretched polyolefin film |
| JP2514549B2 (en) * | 1992-09-16 | 1996-07-10 | チッソ株式会社 | Laminated polypropylene sheet |
| EP0691366B1 (en) * | 1994-07-08 | 1999-03-10 | Tokuyama Corporation | Stretched polypropylene film |
| DE4427377A1 (en) * | 1994-08-03 | 1996-02-08 | Hoechst Ag | Oriented film made of thermoplastic polymer with particulate hollow bodies, process for their production and their use |
| JPH0873618A (en) * | 1994-09-07 | 1996-03-19 | Tousero Kk | Opaque polyolefin film |
| DE19536043A1 (en) * | 1995-09-28 | 1997-04-10 | Hoechst Ag | Polyolefin film with cycloolefin polymer, process for its production and its use |
| JPH10204199A (en) * | 1996-11-19 | 1998-08-04 | Mitsubishi Chem Corp | Porous molding |
-
1997
- 1997-12-24 US US08/998,149 patent/US6048608A/en not_active Expired - Fee Related
-
1998
- 1998-12-08 CN CN98813312A patent/CN1284025A/en active Pending
- 1998-12-08 EP EP98960808A patent/EP1042118A4/en not_active Withdrawn
- 1998-12-08 WO PCT/US1998/026010 patent/WO1999033647A1/en not_active Application Discontinuation
- 1998-12-08 BR BR9814477A patent/BR9814477A/en not_active Application Discontinuation
- 1998-12-08 AU AU16315/99A patent/AU743697B2/en not_active Ceased
- 1998-12-08 JP JP2000526359A patent/JP2001526982A/en not_active Withdrawn
- 1998-12-08 CA CA 2316393 patent/CA2316393A1/en not_active Abandoned
- 1998-12-22 AR ARP980106624 patent/AR014154A1/en unknown
- 1998-12-24 TW TW87121677A patent/TW409135B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| BR9814477A (en) | 2001-10-23 |
| AU743697B2 (en) | 2002-01-31 |
| US6048608A (en) | 2000-04-11 |
| EP1042118A4 (en) | 2001-01-03 |
| WO1999033647A1 (en) | 1999-07-08 |
| CN1284025A (en) | 2001-02-14 |
| AR014154A1 (en) | 2001-02-07 |
| JP2001526982A (en) | 2001-12-25 |
| TW409135B (en) | 2000-10-21 |
| EP1042118A1 (en) | 2000-10-11 |
| AU1631599A (en) | 1999-07-19 |
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