CA2144835A1 - Heat-sealable, oriented, multilayer polyolefin film, process for the production thereof, and the use thereof - Google Patents
Heat-sealable, oriented, multilayer polyolefin film, process for the production thereof, and the use thereofInfo
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- CA2144835A1 CA2144835A1 CA002144835A CA2144835A CA2144835A1 CA 2144835 A1 CA2144835 A1 CA 2144835A1 CA 002144835 A CA002144835 A CA 002144835A CA 2144835 A CA2144835 A CA 2144835A CA 2144835 A1 CA2144835 A1 CA 2144835A1
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- 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
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- 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
- B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
- B32B27/20—Layered products comprising a layer of synthetic resin characterised by the use of special additives using fillers, pigments, thixotroping agents
-
- 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
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- 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
- B32B38/00—Ancillary operations in connection with laminating processes
- B32B38/0012—Mechanical treatment, e.g. roughening, deforming, stretching
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K7/00—Use of ingredients characterised by shape
- C08K7/16—Solid spheres
- C08K7/18—Solid spheres inorganic
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- 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
- B32B38/00—Ancillary operations in connection with laminating processes
- B32B38/0012—Mechanical treatment, e.g. roughening, deforming, stretching
- B32B2038/0028—Stretching, elongating
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- 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
- B32B2307/00—Properties of the layers or laminate
- B32B2307/30—Properties of the layers or laminate having particular thermal properties
- B32B2307/31—Heat sealable
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- 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
- B32B2307/00—Properties of the layers or laminate
- B32B2307/50—Properties of the layers or laminate having particular mechanical properties
- B32B2307/514—Oriented
- B32B2307/518—Oriented bi-axially
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- 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
- B32B2307/00—Properties of the layers or laminate
- B32B2307/70—Other properties
- B32B2307/718—Weight, e.g. weight per square meter
-
- 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
- B32B2309/00—Parameters for the laminating or treatment process; Apparatus details
- B32B2309/02—Temperature
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- 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
- B32B2309/00—Parameters for the laminating or treatment process; Apparatus details
- B32B2309/08—Dimensions, e.g. volume
- B32B2309/10—Dimensions, e.g. volume linear, e.g. length, distance, width
- B32B2309/105—Thickness
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- 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
- B32B2553/00—Packaging equipment or accessories not otherwise provided for
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Laminated Bodies (AREA)
Abstract
The invention relates to an oriented, multilayer poly-olefin film which comprises a polyolefinic base layer and at least one heat-sealable outer layer, which contains from 0.01 to 1% by weight, based on the weight of the outer layer, of approximately spherical ceramic particles.
The invention also relates to a process for the production of the film and to its use.
The invention also relates to a process for the production of the film and to its use.
Description
-Heat-sealable, oriented, multilayer polyolefin film, process for the production thereof, and the use thereof The invention relates to an oriented, multilayer poly-olefin film comprising a polyolefinic base layer and at least one heat-sealable outer layer. The films are distinguished by low haze, high gloss and a low coeffi-cient of friction.
The prior art describes transparent films having lowcoefficients of friction. The d~m~n~ on the processing properties of the films and their smooth running through automatic machines have constantly increased over the years. For this reason, ever-lower coefficients of friction are required, with the term "low" friction values today covering an order of magnitude of from 0.3 to 0.1, while a friction of from 0.4 to 0.5 was regarded as extremely low a few years ago.
DE-A-20 01 032 describes films made from various thermoplastics whose surface-slip characteristics have been improved by addition of carboxamides and anti-blocking agents. Since it is not possible for a suffi-cient amount of lubricant to be incorporated into the outer layers alone, the additional incorporation of the amides into the base layer is recommended. These films have a coefficient of friction in the range from 0.4 to 0.8 and thus no ~onger meet today's quality requirements.
US-A-4,117,193 describes multilayer films comprising a polypropylene base layer containing a lubricant, an antiblocking agent and an antistatic. The outer layer of these films comprises a polymer blend and additionally contain a lubricant and an antiblocking agent. The polymer blend comprises an ethylene-butylene copolymer - 2 _ 214~835 and a polyolefinic resin such as HDPE or LDPE. It is stated that the poor surface-slip characteristics of the films cannot be sufficiently improved by the addition of lubricants and antiblocking agents alone. For this reason, the outer layer is modified by addition of HDPE
or LDPE in combination with a lubricant and antiblocking agent. According to the examples and comparative examples, the reduction in the coefficient of friction is essentially due to the addition of HDPE. Pure copolymeric outer layers with the same additive composition have coefficients of friction of from 0.7 to 0.8. The films combine excellent coefficients of friction with good printability, but are highly unsatisfactory in haze and gloss owing to the addition of the friction-reducing polyolefinic resin.
EP-A-0 402 100 describes polypropylene films which contain from 0.01 to 0.5% by weight of a spherical SiO2 and from 0.3 to 5% by weight of a hydroxyfatty acid glyceride. This invention relates to single-layer and multilayer films. Multilayer embodiments contain the combination of SiO2 and glyceride both in the outer layer and in the base layer. It is stated that the selected amounts of SiO2 and glyceride are essential for the advantageous properties of the films and deviations from these ranges no longer give the desired result. The films are distinguished by good transparency, surface-slip characteristics and adhesion to metal. However, they have a coating on the surface after an extended storage time which impairs the appearance of the films. This effect is also known as blooming and is caused by migration of certain additives, in particular the glycerides, to the surface of the films.
EP-A-0 182 463 describes a multilayer film which contains from 0.05 to 0.2% by weight of tertiary aliphatic amine in the base layer and a combination of silicone oil and SiO2 in the heat-sealable outer layer. According to the description, the surprising interaction of SiO2, silicone 21~8~
oil and amine in combination with a selected outer layer thickness of less than 0.8 ~m gives films having coefficients of friction of 0.3 or less. In spite of this excellent coefficient of friction, the processing proper-ties of the film are poor. In particular, it is notprintable and is therefore unsuitable for many applications.
EP-A-0 143 130 discloses films which contain a carbox-amide in the base layer and likewise the co-mbination of silicone oil and SiO2 in the outer layer. Like in the abovementioned EP-A-0 182 463, a synergistic action of the three selected components on the coefficient of friction is described. These films likewise have poor processing properties in spite of their advantageous surface-slip characteristics. Again, they lack the important property of printability.
EP-A-0 242 055 describes the use of an infusible, organo-siloxane resin powder having a three-~;men~ional network structure as antiblocking agent in films. Both the silicone resin and the propylene polymer are employed in the form of a powder comprising particles having a virtually spherical shape, this particle shape being characterized by an appropriate equation for the actual degree of sphericalness. The films are said to be improved compared with the prior art with respect to their transparency, antiblocking properties, surface-slip characteristics and appearance. The propylene/antiblock-ing agent mixture can also be employed as outer-layer material for coextruded multilayer films. However, these coextruded multilayer films are still unsatisfactory with respect to their transparency and their gloss values, in particular when the outer layers are applied in conven-tional layer thicknesses of greater than 0.5 ~m. In addition, this antiblocking agent is very much more expensive than conventional antiblocking agents.
German Patent Application P 43 06 154.0 describes the use ~v of an organically coated SiO2 as antiblocking agent in heat-sealable films. The coefficient of friction and the processing properties of the film are improved. This publication makes no mention of the spatial shape of the antiblocking particles.
EP-A-0 353 368 describes the use of the siloxane resin powder described in EP-A-0 242 055, in combination with a hydroxyfatty acid glyceride. These films are particu-larly suitable for vacuum vapor deposition, but are very poor with respect to their gloss and transparency.
By applying the known teaching, it has been found that some known antiblocking agents have adverse effects on certain film properties. The antiblocking agent impairs the transparency and the gloss of the film. The improve-ment in friction is generally accompanied by an increasein surface roughness. During production of the films, SiO2 as antiblocking agent causes deposits on the die lip and abrasion on the rolls. This means that the die lip and the rolls must be cleaned frequently, since the film otherwise runs poorly during production and the deposits on the die lip result in streaking on the film. In addition, problems occur during corona treatment. The corona treatment breaks through in the areas of the roll where SiO2 abrasion has occurred and results in the undesired phenomenon known as the reverse-side effect.
This causes unacceptable flaws during further processing of the film, such as, for example, printing or metallization.
The object of the present invention was to avoid the 3Q disadvantages of the films previously described in the prior art, in particular, the aim is to provide a multi-layer film which is distinguished by a combination of the following properties:
high gloss low haze a low coefficient of friction 21~q835 low surface roughness.
The object of the invention is achieved by a multilayer film of the generic type mentioned at the outset, wherein the heat-sealable outer layer contains from 0.01 to 1% by weight, based on the weight of the outer layer, of approximately spherical ceramic particles.
The base layer of the novel multilayer film essentially comprises a polyolefin, preferably a propylene polymer, and, if desired, further additives, in effective amounts in each case. In general, the base layer comprises at least 50% by weight, preferably from 75 to 100% by weight, in particular from 90 to 100% by weight, of the propylene polymer.
The propylene polymer generally comprises from 90 to 100%
by weight, preferably from 95 to 100% by weight, in particular from 98 to 100% by weight, of propylene and generally has a melting point of 120C or above, prefer-ably from 150 to 170C, and generally has a melt flow index from 0.5 g/10 min to 8 g/10 min, preferably from 2 g/10 min to 5 g/10 min, at 230C and a force of 21.6 N
(DIN 53 735). Isotactic propylene homopolymer having an atactic content of 15% by weight or less, copolymers of ethylene and propylene having an ethylene content of 10%
by weight or less, copolymers of propylene with C4-C8-~-olefins having an ~-olefin content of 10% by weight or less, terpolymers of propylene, ethylene and butylene having an ethylene content of 10% by weight or less and a butylene content of 15% by weight or less are preferred propylene polymers ~or the core layer, particular preference being given to isotactic propylene homopolymer. The percentages by weight stated are based on the particular polymer.
In addition, a mixture of said propylene homopolymers and/or copolymers and/or terpolymers and other poly-olefins, in particular comprising monomers having 2 to 6 carbon atoms, is suitable, where the mixture contains atleast 50% by weight, in particular at least 75% by weight, of propylene polymer. Other suitable polyolefins in the polymer mixture are polyethylenes, in particular HDPE, LDPE and LLDPE, where the content of these polyolefins is in each case not greater than 15% by weight, based on the polymer mixture.
In general, the base layer can contain lubricants, anti-statics, stabilizers and/or neutralizers, in effective amounts in each case, and, if desired, hydrocarbon resin.
In a white or opaque or white/opaque embodiment, the base layer additionally contains pigments or vacuole-inducing particles or a combination thereof. Such films have a light transparency measured in accordance with ASTM-D
1033-77 of at most 50%, preferably at most 70%.
Pigments include particles which result in essentially no vacuole formation on stretching. The coloring action of the pigments is caused by the particles themselves. The term "pigment" is generally associated with a particle size of from 0.01 to a maximum of 1 ~m and covers both so-called "white pigments", which color the films white, and "colored pigments" which give the film a colored or black color. In general, the mean particle diameter of the pigments is in the range from 0.01 to 1 ~m, preferably from 0.01 to 0.7 ~m, in particular from 0.01 to 0.4 ~m. The base layer generally contains pigments in an amount of from 1 to 25% by weight, in particular from 2 to 20% by weight, preferably from 5 to 15% by weight, in each case based on the base layer.
Conventional pigments are materials such as, for example, aluminum oxide, aluminum sulfate, barium sulfate, calcium carbonate, magnesium carbonate, silicates, such as aluminum silicate (kaolin clay) and magnesium silicate (talc), silicon dioxide and titanium dioxide, of which white pigments, such as calcium carbonate, silicon 214 183~
dioxide, titanium dioxide and barium sulfate are pre-ferred.
The titanium dioxide particles comprise at least 95% by weight of rutile and are preferably employed with a coating of inorganic oxides, as usually used as a coating for TiO2 white pigment in papers or paints in order to improve the light fastness. Particularly suitable inorganic oxides include the oxides of aluminum, silicon, zinc and magnesium or mixtures of two or more of these compounds. They are precipitated from water-soluble compounds, for example alkali metal aluminate, in par-ticular sodium aluminate, aluminum hydroxide, aluminum sulfate, aluminum nitrate, sodium silicate or silicic acid, in aqueous suspension. Coated Tio2 particles are described, for example, in EP-A-0 078 633 and EP-A-0 044 515.
The coating may also contain organic compounds containing polar and nonpolar groups. Preferred organic compounds are alkanols and fatty acids having 8 to 30 carbon atoms in the alkyl group, in particular fatty acids and primary n-alkanols having 12 to 24 carbon atoms, and polydi-organosiloxanes and/or polyorganohydrosiloxanes, such as polydimethylsiloxane and polymethylhydrosiloxane.
The coating on the Tio2 particles usually comprises from 1 to 12 g, in particular from 2 to 6 g, of inorganic oxides, if desired additionally from 0.5 to 3 g, in particular from 0.7 to 1.5 g, of organic compounds, in each case based on 100 g of TiO2 particles. It has proven particularly advantageous for the TiO2 particles to be coated with Al2O3 or with Al2O3 and polydimethylsiloxane.
Opaque embodiments of the films contain vacuole-inducing particles which are incompatible with the polymer matrix and result in the formation of vacuole-like cavities when the film is stretched, the size, type and number of the vacuoles being dependent on the material and on the size 214~83~
of the solid particles and the stretching conditions, such as stretching ratio and stretching temperature. The vacuoles give the films a characteristic pearl-like opaque appearance, caused by light scattering at the vacuole-polymer matrix interfaces. In general, the mean particle diameter of the vacuole-inducing particles is from 1 to 6 ~m, preferably from 1.5 to 5 ~m. The base layer generally contains vacuole-inducing particles in an amount of from 1 to 25% by weight.
Conventional vacuole-inducing particles in the base layer are inorganic and/or organic, polypropylene-incompatible materials, such as alu~inum oxide, aluminum sulfate, barium sulfate, calcium carbonate, magnesium carbonate, silicates, such as aluminum silicate (kaolin clay) and magnesium silicate (talc), silicon dioxide and titanium dioxide, of which calcium carbonate, silicon dioxide and titanium dioxide are preferred. Suitable organic fillers are the conventional polymers which are incompatible with the polymers of the base layer, in particular those such as HDPE, polyesters, polystyrenes, polyamides and halo-genated organic polymers, preference being given to polyesters, such as, for example polybutylene tere-phthalates or polyethylene terephthalates. For the purposes of the present invention, "incompatible materials or incompatible polymers" is taken to mean that the material or polymer is in the form of a separate particle or a separate phase in the film.
White/opaque films provided with vacuole-inducing part-icles and with pigment contain the vacuole-inducing particles in an amount of from 1 to 10% by weight, preferably from 1 to 5% by weight, and pigment in an amount of from 1 to 7% by weight, preferably from 1 to 5%
by weight.
The density of the opaque or white films can vary within broad limits and depends on the type and amount of fillers. The density is generally in the range from 0.4 g to 1.1 g/cm3. Pigmented films have a density in the order of 0.9 g/cm3 or above, preferably in the range from 0.9 to 1.1 g/cm3. Films containing only vacuole-inducing particles have a density of less than 0.9 g/cm3. For packaging films having a content of vacuole-inducing particles of from 2 to 5% by weight, the density is in the range from 0.6 to 0.85 g/cm3. For films having a content of vacuole-inducing particles of from 5 to 14% by weight, the density is in the range from 0.4 to 0.8 g/cm3. Films containing pigments and vacuole-inducing particles have a density in the range from 0.5 to 0.85 g/cm3, depending on the ratio between the pigment content and the content of vacuole-inducing particles.
The novel multilayer film can, if desired, contain (a) further interlayer(s) between the base and outer layers.
This (these) interlayer(s) which may be present essentially comprise(s) propylene polymers or polypropylene mixtures as described above for the base layer. In principle, the base layer and the interlayer(s) can be made of the same or different propylene polymers or mixtures. The melt flow indices of the polymers for the core layer and the interlayer(s) should, as far as possible, be the same. If desired, the MFI of the inter-layer(s) can be somewhat greater, but the difference should not exceed 20%. If desired, additives in effective amounts in each case can be added to the interlayers.
In a preferred embodiment of the novel film, the propylene polymer of the base layer and/or of the inter-layer is peroxidically degraded.
A measure of the degree of degradation of the polymer is the degradation factor A, which gives the relative change in the melt flow index, measured in accordance with DIN 53 735, of the polypropylene, based on the starting polymer.
A =
MFIl 214483s MFI1 = melt flow index of the propylene polymer before addition of the organic peroxide.
MFI2 = melt flow index of the peroxidically degraded propylene polymer.
In general, the degradation factor A of the propylene polymer employed is in the range from 3 to 15, preferably from 6 to 10.
Particularly preferred organic peroxides are dialkyl peroxides, where the term alkyl radical is taken to mean a conventional saturated, straight-chain or branched lower alkyl radical having up to six carbon atoms.
Particular preference is given to 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and di-t-butyl peroxide.
The novel polyolefin film furthermore contains at least one heat-sealable outer layer. This outer layer essentially comprises heat-sealable polymers of ~-olefins having 2 to 10 carbon atoms and approximately spherical ceramic particles and, if desired, further additives in effective amounts in each case. In general, the outer layer comprises from 75 to approximately 100% by weight, in particular from 90 to 99.5% by weight, of the heat-sealable ~-olefinic polymer.
Examples of such heat-sealable ~-olefinic polymers are a copolymer of ethylene and propylene or ethylene and 1-butylene or propylene and 1-butylene or a terpolymer of ethylene and propylene and 1-butylene or a mixture of two or more of said homopolymers, copolymers and terpolymers or a blend of two or more of said homopolymers, copolymers and terpolymers, if desired mixed with one or more of said homopolymers, copolymers and terpolymers, 219983~
particular preference being given to random ethylene-propylene copolymers having an ethylene content of from 1 to 10% by weight, preferably from 2.5 to 8% by weight or random propylene-1-butylene copolymers having a butylene content of from 2 to 25% by weight, preferably from 4 to 20% by weight, in each case based on the total weight of the copolymer, or random ethylene-propylene-1-butylene terpolymers having an ethylene content of from 1 to 10% by weight, preferably from 2 to 6% by weight, and a 1-butylene content of from 2 to 20% by weight, preferably from 4 to 20% by weight, in each case based on the total weight of the terpolymer, or a blend of an ethylene-propylene-1-butylene ter-polymer and a propylene-1-butylene copolymer having an ethylene content of from 0.1 to 7% by weight and a propylene content of from 50 to 90% by weight and a 1-butylene content of from 10 to 40% by weight, in each case based on the total weight of the polymer blend.
The above-described copolymers and terpolymers generally have a melt flow index of from 1.5 to 30 g/10 min, preferably from 3 to 15 g/10 min and generally have a melting point in the range from 120 to 140C. The above-described blend of copolymers and terpolymers generally has a melt flow index of from 5 to 9 g/10 min and a melting point of from 120 to 150C. All the melt flow indices given above are measured at 230C and a force of 21.6 N (DIN 53 735).
If desired all the outer layer polymers described above 2I 4483~
can be peroxidically degraded in the same way as described above for the base layer, basically the same peroxides being used. The degradation factor for the outer layer polymers is generally in the range from 3 to 15, preferably from 6 to 10.
According to the invention, the outer layer contains approximately spherical particles which essentially comprise a ceramic material and, if desired, have a coating of an organic and/or inorganic substance. For the purposes of the present invention, approximately spherical particles are particles which satisfy the following condition:
f = ~A/(~/4)/Dmax in which f is greater than 0.7, preferably from 0.8 to 1, in particular from 0.9 to 1, A is the cross-sectional area in mm2, and DmaX is the m~;mllm diameter of the cross-sectional area in mm. The factor f is a measure of the degree of sphericalness of the particles. The closer f is to 1, the closer the shape of the particles is to the ideal spherical shape.
The ceramic material is preferably sodium silicate, aluminum silicate or corresponding mixed silicates. The mean particle diameter is generally in the range from 0.5 to 10 ~m, preferably from 1 to 5 ~m. The antiblocking agent particles are essentially free from siloxane resin compounds. If desired, the spherical particles have an organic and/or inorganic coating, which is also essen-tially free from siloxane.
Particularly suitable inorganic coatings include the oxides of aluminum, silicon, zinc or magnesium or mixtures of two or more of these compounds. They are precipitated from water-soluble compounds, for example alkali metal aluminates, in particular sodium aluminate, aluminum hydroxide, aluminum sulfate, aluminum nitrate, sodium silicate or silicic acid, in aqueous suspension.
If desired, the coating can also comprise or contain 214~835 organic compounds containing polar and nonpolar groups.
Preferred organic compounds are alkanols and fatty acids having 8 to 30 carbon atoms in the alkyl group, in particular fatty acids and primary n-alkanols having 12 to 24 carbon atoms, and maleic anhydride, polypropylene wax and polyethylene wax.
Surprisingly, there is an interaction of structure and substance of the antiblocking agent particles in the spherical ceramic particles used in accordance with the invention. It has been found that films containing known spherical particles of silicone resin in the outer layer have worse haze and worse gloss. Compared with known antiblocking agent particles having an organic coating, an entirely unexpected improvement in gloss, haze, friction and surface roughness of the film has been found in the novel film. Opaque e-mbodiments of the film like-wise exhibit improved gloss and low friction and low surface roughness. Haze is of course unimportant in opa~ue films.
The novel multilayer film comprises the above-described base layer and at least one outer layer and, if desired, further layers. Preference is given to three-layer embodiments containing outer layers on both sides of the base layer; these outer layers can have the same or different thicknesses and compositions. Preference is also given to five-layer embodiments containing a base layer, interlayers applied to both sides of the base layer, and outer layers on both sides.
The overall thickness of the multilayer polyolefin film according to the invention can vary within broad limits and depends on the intended application. It is preferably from 5 to 70 ~m, in particular from 10 to 50 ~m, the base layer mAk;ng up from about 50 to 90% of the overall film thickness.
The thickness of the outer layer(s) is generally greater 214~83~
than 0.2 ~m and is preferably in the range from 0.3 to 2 ~m, in particular from ~ 0.5 to 1 ~m, where outer layers on both sides may have the same or different thicknesses.
The thickness of any interlayer(s) present is generally, in each case independently of any others, from 1 to 12 ~m, preferably from 2 to 8 ~m, in particular from 3 to 6 ~m. The values indicated are in each case based on one interlayer.
In addition to this selected outer layer additive, the multilayer film according to the invention may addi-tionally contain neutralizers, stabilizers, lubricants, hydrocarbon resins and/or antistatics, in one or more layers. The percentages by weight given below relate to the weight of the respective layer to which the additive has been added.
Neutralizers are preferably dihydrotalcite, calcium stearate and/or calcium carbonate having a mean particle size of at most 0.7 ~m, an absolute particle size of less than 10 ~m and a specific surface area of at least 40 m2/g. In general, the neutralizer is added in an amount of from 0.02 to 0.1% by weight.
Stabilizers which can be added are the conventional stabilizing compounds for polymers of ethylene, propylene and other ~-olefins. The amount in which they are added is between 0.05 and 2% by weight. Particularly suitable are phenolic stabilizers, alkali/alkaline earth metal stearates and/or alkali/alkaline earth metal carbonates.
Phenolic stabilizers are preferred in an amount of from 0.1 to 0.6% by weight, in particular from 0.15 to 0.3% by weight, and having a molecular weight of greater than 500 g/mol.Pentaerythrityltetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene are particularly advantageous.
, Lubricants are higher aliphatic acid amides, higher aliphatic acid esters, waxes and metal soaps, and poly-dimethylsiloxanes. The effective amount of lubricant is in the range from 0.1 to 3% by weight. The addition of higher aliphatic acid amides in the range from 0.15 to 0.25% by weight to the base layer and/or the outer layers is particularly suitable. A particularly suitable ali-phatic acid amide is erucamide.
Hydrocarbon resins are low-molecular-weight polymers whose molecular weight is generally in the range from 300 to 8000, preferably from 400 to 5000, in particular from 500 to 2000. The molecular weight of the resins is thus significantly lower than that of the propylene polymers forming the main component of the individual film layers, which generally have a molecular weight of greater than 100,000. The hydrocarbon resins are preferably added to the base layer and/or the interlayer(s). The effective amount of low-molecular-weight resin is from 1 to 20% by weight, preferably from 2 to 10% by weight, based on the layer.
The low-molecular-weight resin recommended is a natural or synthetic resin having a softening point of from 60 to 180C, preferably from 80 to 150C, determined in accor-dance with ASTM E-28. Of the numerous low-molecular-weight resins, preference is given to hydrocarbon resins, specifically in the form of petroleum resins, styrene resins, cyclopentadiene resins and terpene resins (these resins are described in Ullmanns Encyklopadie der technischen Chemie [Ullmann's Encyclopedia of Industrial 30 Chemistry], 4th Edition, Volume 12, pages 525 to 555).
Suitable petroleum resins are described in numerous specifications, such as, for example, EP-A-0 180 087, to which reference is expressly made here.
Preferred antistatics are alkali metal alkanesulfonates, polyether-modified, i.e. ethoxylated and/or propoxylated, polydiorganosiloxanes (polydialkylsiloxanes, _ - 16 -polyalkylphenylsiloxanes and the like) and/or the essen-tially straight-chain and saturated, aliphatic, tertiary amines containing an aliphatic radical having 10 to 20 carbon atoms which are substituted by ~-hydroxy-(Cl-C4)-alkyl groups, N,N-bis(2-hydroxyethyl)alkylamines having 10 to 20 carbon atoms, preferably 12 to 18 carbon atoms, in the alkyl radical being particularly suitable. The effective amount of antistatic is in the range from O.OS
to 3% by weight. A further preferred antistatic is glycerol monostearate.
The invention furthermore relates to a process for the production of the multilayer film according to the invention by the coextrusion process known per se, in which, as usual in the coextrusion process, the polymer or polymer mixture of individual layers is compressed and liquefied in an extruder, it being possible for any additives already to be present in the polymer or in the polymer mixture or can be added via the masterbatch method. The melts corresponding to the individual layers of the film are then simultaneously coextruded through a flat-film die, and the extruded multilayer film is taken off over one or more take-off rolls, during which it cools and solidifies.
The resultant film is then stretched longitudinally and transversely to the extrusion direction, which results in orientation of the molecular ch~;næ. The stretching is preferably from 4:1 to 7:1 in the longitudinal direction and from 7:1 to 11:1 in the transverse direction. The longitudinal stretching is expediently carried out with the aid of two rolls rotating at different speeds corres-ponding to the desired stretching ratio, and the trans-verse stretching is carried out with the aid of an appropriate tenter frame.
The biaxial stretching of the film is followed by ~eat setting, during which the film is kept at a temperature of from 100 to 160C for from about 0.5 to 10 seconds.
The film is subsequently wound up in the conventional manner using a wind-up unit.
It has proven particularly favorable to keep the take-off roll or rolls, which also cool and solidify the extruded film, at a temperature of from 20 to 90C.
The temperatures at which longitudinal and transverse stretching are carried out can vary. In general, the longitudinal stretching is preferably carried out at from 100 to 150C and the transverse stretching at from 155 to 10 190 C .
As mentioned above, one or both surfaces of the film can, if desired, be corona- or flame-treated by one of the known methods after the biaxial stretching.
In the case of corona treatment, it is expedient to pass the film between two conductor elements serving as electrodes, with such high voltage, usually an alterna-ting voltage (from about 10 to 20 kV and 20 to 40 kHz) being applied between the electrodes so that spray or corona discharges can occur. The spray or corona discharge ionizes the air above the film surface, causing it to react with the molecules of the film surface, so that polar inclusions are formed in the essentially nonpolar polymer matrix.
For flame treatment with a polarized flame (cf.
US-A-4,622,237), a direct electrical voltage is applied between a burner (negative pole) and a chill roll. The level of the applied voltage is between 500 and 3000 V, preferably in the range from 1500 to 2000 V. Owing to the applied voltage, the ionized atoms accelerate and hit the polymer surface with greater kinetic energy. The chemical bonds within the polymer molecule are easier to break, and free-radical formation proceeds more quickly. The thermal load on the poly~er during this is significantly less than in the case of standard flame treatment, and ` - 18 _ 21 4 483 5 films can be obtained in which the heat-sealing proper-ties of the treated side are even better than those of the untreated side.
The novel film has improved gloss and haze compared with known films having a low coefficient of friction and is also distinguished by a very low coefficient of friction and by low surface roughness. In addition, the film has a low ~;n;mllm heat-sealing temperature. The coefficient of sliding friction of lubricant-free embodiments of the films is generally in the range from 0.3 to 0.7, prefer-ably from 0.3 to 0.5. Films which additionally contain a lubricant, such as, for example, a fatty acid amide, in particular erucamide, have an even further reduced coefficient of sliding friction. In the case of films containing erucamide in the base layer, this is generally in the range from 0.05 to 0.3, preferably from 0.1 to 0.2. The gloss of the novel film is in the range from 90 to 130, preferably from 105 to 130. The haze of trans-parent embodiments is in the range from 0.9 to 3.0, preferably in the range from 0.9 to 2Ø
The invention is now described in greater detail with reference to working examples.
Example 1 A three-layer film having an overall thickness of 20 ~m and an ABA layer structure, i.e. the base layer B was surrounded by two identical outer layers A, was produced by coextrusion and subsequent stepwise orientation in the longitudinal and transverse directions.
The film was subjected to corona treatment on one side (the roll side) before rolling up. The roll side is the side of the film in contact with the first take-off roll.
The surface tension on this side as a consequence of this treatment was from 39 to 40 mN/m. All layers contained 0.13~ by weight of pentaerythrityl tetrakis[4-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate](~Irganox 1010) as 214483~
stabilizer and 0.06% by weight of calcium stearate as neutralizer.
The base layer B essentially comprised a polypropylene homopolymer having an n-heptane-soluble content of 4% by weight and a melting range of from 160 to 162C. The melt flow index of the polypropylene homopolymer was 3.4 g/10 min at 230C and a load of 21.6 N (DIN 53 735).
The base layer contained 0.12% by weight of erucamide having a melting range of from 78 to 82C and 0.12% by weight of N,N-bisethoxyalkylamine (~Armostat 300).
The polyolefinic outer layers essentially comprised an ethylene-propylene-1-butene terpolymer having a content of 3.5% by weight of ethylene, 88.5% by weight of propylene and 8% by weight of 1-butene. The outer layers contained 0.33% by weight of a ceramic, spherical anti-blocking agent having a mean particle diameter of 2 ~m.
Each of the outer layers had a thickness of 0.8 ~m.
Comparative Example 1 Example 1 was repeated, but the antiblocking agent used was 0.33% by weight of a crosslinked silicone resin powder having a mean particle diameter of 2 ~m (~Tospearl 20 from Toshiba Silicone Co., Ltd.).
C~ _=rative Example 2 Example 1 was repeated, but the antiblocking agent used was 0.33% by weight of an organically coated silicon dioxide having a mean particle diameter of 2 ~m (~Sylobloc 44 from Grace).
Example 2 Example 1 was repeated, but the base layer contained no erucamide.
~ative Example 3 Comparative Example 1 was repeated, but the base layer contained no erucamide.
Comparative Example 4 Comparative Example 2 was repeated, but the base layer contained no erucamide.
The properties of the films of the examples and comparative examples are shown in the table below.
The raw materials and films were characterized using the following measurement methods:
Melt flow index The melt flow index was measured in accordance with DIN 53 735 at a load of 21.6 N and at 230C.
Meltinq Point DSC measurement, m~;mllm of the melting curve, heating rate 20C/min.
Determination of the m;n;mllm heat-sealinq temperature Heat-sealed samples (seal seam 20 mm x 100 mm) are produced using a Brugger HSG/ET sealing unit by sealing a film at various temperatures with the aid of two heated sealing jaws at a pressure of 10 N/cm2 for 0.5 s. Test strips 15 mm in width are cut out of the sealed samples.
The T-seal seam strength, i.e. the force necessary to separate the test strips, is determined on a tensile testing machine at a peel rate of 200 mm/min, the seal seam plane forming a right angle with the direction of tension. The m;n;mllm heat-sealing temperature is the temperature at which a seal seam strength of at least 0.5 N/15 mm is achieved.
Seal seam strenqth For the determination, two 15 mm wide film strips were laid one on top of the other and heat-sealed for 0.5 seconds at 130C and a pressure of 1.5 N/mm2 (Brugger NDS instrument, sealing jaws heated on one side). The seal seam strength was determined by the T-peel method.
21~4835 .
Friction The friction was determined in accordance with DIN 53 375. The coefficient of sliding friction was measured 14 days after production.
Surface tension The surface tension was determined by the ink method (DIN 53 364).
Rouqhness The roughness was determined in accordance with DIN 4768 at a cut-off of 0.25 mm.
Haze The haze of the film was measured in accordance with ASTM-D 1003-52. The Holz haze measurement was also carried out in accordance with ASTM-D 1003-52, but, in order to utilize the optimum measuring range, the measurement was carried out on four film layers lying one on top of the other and a 1 slit diaphragm was employed instead of a 4 pinhole diaphragm.
Gloss 20 The gloss was determined in accordance with DIN 67 530.
The reflector value was measured as an optical parameter for the surface of a film. In accordance with the ASTM-D 523-78 and ISO 2813 standards, the angle of incidence was set at 20 or 60. A light beam hits the planar test surface at the set angle of incidence and is reflected or scattered thereby. The light rays hitting the photoelectronic receiver are indicated as a proportional electrical quantity. The measurement value is ~;mensionless and must be given together with the angle of incidence.
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The prior art describes transparent films having lowcoefficients of friction. The d~m~n~ on the processing properties of the films and their smooth running through automatic machines have constantly increased over the years. For this reason, ever-lower coefficients of friction are required, with the term "low" friction values today covering an order of magnitude of from 0.3 to 0.1, while a friction of from 0.4 to 0.5 was regarded as extremely low a few years ago.
DE-A-20 01 032 describes films made from various thermoplastics whose surface-slip characteristics have been improved by addition of carboxamides and anti-blocking agents. Since it is not possible for a suffi-cient amount of lubricant to be incorporated into the outer layers alone, the additional incorporation of the amides into the base layer is recommended. These films have a coefficient of friction in the range from 0.4 to 0.8 and thus no ~onger meet today's quality requirements.
US-A-4,117,193 describes multilayer films comprising a polypropylene base layer containing a lubricant, an antiblocking agent and an antistatic. The outer layer of these films comprises a polymer blend and additionally contain a lubricant and an antiblocking agent. The polymer blend comprises an ethylene-butylene copolymer - 2 _ 214~835 and a polyolefinic resin such as HDPE or LDPE. It is stated that the poor surface-slip characteristics of the films cannot be sufficiently improved by the addition of lubricants and antiblocking agents alone. For this reason, the outer layer is modified by addition of HDPE
or LDPE in combination with a lubricant and antiblocking agent. According to the examples and comparative examples, the reduction in the coefficient of friction is essentially due to the addition of HDPE. Pure copolymeric outer layers with the same additive composition have coefficients of friction of from 0.7 to 0.8. The films combine excellent coefficients of friction with good printability, but are highly unsatisfactory in haze and gloss owing to the addition of the friction-reducing polyolefinic resin.
EP-A-0 402 100 describes polypropylene films which contain from 0.01 to 0.5% by weight of a spherical SiO2 and from 0.3 to 5% by weight of a hydroxyfatty acid glyceride. This invention relates to single-layer and multilayer films. Multilayer embodiments contain the combination of SiO2 and glyceride both in the outer layer and in the base layer. It is stated that the selected amounts of SiO2 and glyceride are essential for the advantageous properties of the films and deviations from these ranges no longer give the desired result. The films are distinguished by good transparency, surface-slip characteristics and adhesion to metal. However, they have a coating on the surface after an extended storage time which impairs the appearance of the films. This effect is also known as blooming and is caused by migration of certain additives, in particular the glycerides, to the surface of the films.
EP-A-0 182 463 describes a multilayer film which contains from 0.05 to 0.2% by weight of tertiary aliphatic amine in the base layer and a combination of silicone oil and SiO2 in the heat-sealable outer layer. According to the description, the surprising interaction of SiO2, silicone 21~8~
oil and amine in combination with a selected outer layer thickness of less than 0.8 ~m gives films having coefficients of friction of 0.3 or less. In spite of this excellent coefficient of friction, the processing proper-ties of the film are poor. In particular, it is notprintable and is therefore unsuitable for many applications.
EP-A-0 143 130 discloses films which contain a carbox-amide in the base layer and likewise the co-mbination of silicone oil and SiO2 in the outer layer. Like in the abovementioned EP-A-0 182 463, a synergistic action of the three selected components on the coefficient of friction is described. These films likewise have poor processing properties in spite of their advantageous surface-slip characteristics. Again, they lack the important property of printability.
EP-A-0 242 055 describes the use of an infusible, organo-siloxane resin powder having a three-~;men~ional network structure as antiblocking agent in films. Both the silicone resin and the propylene polymer are employed in the form of a powder comprising particles having a virtually spherical shape, this particle shape being characterized by an appropriate equation for the actual degree of sphericalness. The films are said to be improved compared with the prior art with respect to their transparency, antiblocking properties, surface-slip characteristics and appearance. The propylene/antiblock-ing agent mixture can also be employed as outer-layer material for coextruded multilayer films. However, these coextruded multilayer films are still unsatisfactory with respect to their transparency and their gloss values, in particular when the outer layers are applied in conven-tional layer thicknesses of greater than 0.5 ~m. In addition, this antiblocking agent is very much more expensive than conventional antiblocking agents.
German Patent Application P 43 06 154.0 describes the use ~v of an organically coated SiO2 as antiblocking agent in heat-sealable films. The coefficient of friction and the processing properties of the film are improved. This publication makes no mention of the spatial shape of the antiblocking particles.
EP-A-0 353 368 describes the use of the siloxane resin powder described in EP-A-0 242 055, in combination with a hydroxyfatty acid glyceride. These films are particu-larly suitable for vacuum vapor deposition, but are very poor with respect to their gloss and transparency.
By applying the known teaching, it has been found that some known antiblocking agents have adverse effects on certain film properties. The antiblocking agent impairs the transparency and the gloss of the film. The improve-ment in friction is generally accompanied by an increasein surface roughness. During production of the films, SiO2 as antiblocking agent causes deposits on the die lip and abrasion on the rolls. This means that the die lip and the rolls must be cleaned frequently, since the film otherwise runs poorly during production and the deposits on the die lip result in streaking on the film. In addition, problems occur during corona treatment. The corona treatment breaks through in the areas of the roll where SiO2 abrasion has occurred and results in the undesired phenomenon known as the reverse-side effect.
This causes unacceptable flaws during further processing of the film, such as, for example, printing or metallization.
The object of the present invention was to avoid the 3Q disadvantages of the films previously described in the prior art, in particular, the aim is to provide a multi-layer film which is distinguished by a combination of the following properties:
high gloss low haze a low coefficient of friction 21~q835 low surface roughness.
The object of the invention is achieved by a multilayer film of the generic type mentioned at the outset, wherein the heat-sealable outer layer contains from 0.01 to 1% by weight, based on the weight of the outer layer, of approximately spherical ceramic particles.
The base layer of the novel multilayer film essentially comprises a polyolefin, preferably a propylene polymer, and, if desired, further additives, in effective amounts in each case. In general, the base layer comprises at least 50% by weight, preferably from 75 to 100% by weight, in particular from 90 to 100% by weight, of the propylene polymer.
The propylene polymer generally comprises from 90 to 100%
by weight, preferably from 95 to 100% by weight, in particular from 98 to 100% by weight, of propylene and generally has a melting point of 120C or above, prefer-ably from 150 to 170C, and generally has a melt flow index from 0.5 g/10 min to 8 g/10 min, preferably from 2 g/10 min to 5 g/10 min, at 230C and a force of 21.6 N
(DIN 53 735). Isotactic propylene homopolymer having an atactic content of 15% by weight or less, copolymers of ethylene and propylene having an ethylene content of 10%
by weight or less, copolymers of propylene with C4-C8-~-olefins having an ~-olefin content of 10% by weight or less, terpolymers of propylene, ethylene and butylene having an ethylene content of 10% by weight or less and a butylene content of 15% by weight or less are preferred propylene polymers ~or the core layer, particular preference being given to isotactic propylene homopolymer. The percentages by weight stated are based on the particular polymer.
In addition, a mixture of said propylene homopolymers and/or copolymers and/or terpolymers and other poly-olefins, in particular comprising monomers having 2 to 6 carbon atoms, is suitable, where the mixture contains atleast 50% by weight, in particular at least 75% by weight, of propylene polymer. Other suitable polyolefins in the polymer mixture are polyethylenes, in particular HDPE, LDPE and LLDPE, where the content of these polyolefins is in each case not greater than 15% by weight, based on the polymer mixture.
In general, the base layer can contain lubricants, anti-statics, stabilizers and/or neutralizers, in effective amounts in each case, and, if desired, hydrocarbon resin.
In a white or opaque or white/opaque embodiment, the base layer additionally contains pigments or vacuole-inducing particles or a combination thereof. Such films have a light transparency measured in accordance with ASTM-D
1033-77 of at most 50%, preferably at most 70%.
Pigments include particles which result in essentially no vacuole formation on stretching. The coloring action of the pigments is caused by the particles themselves. The term "pigment" is generally associated with a particle size of from 0.01 to a maximum of 1 ~m and covers both so-called "white pigments", which color the films white, and "colored pigments" which give the film a colored or black color. In general, the mean particle diameter of the pigments is in the range from 0.01 to 1 ~m, preferably from 0.01 to 0.7 ~m, in particular from 0.01 to 0.4 ~m. The base layer generally contains pigments in an amount of from 1 to 25% by weight, in particular from 2 to 20% by weight, preferably from 5 to 15% by weight, in each case based on the base layer.
Conventional pigments are materials such as, for example, aluminum oxide, aluminum sulfate, barium sulfate, calcium carbonate, magnesium carbonate, silicates, such as aluminum silicate (kaolin clay) and magnesium silicate (talc), silicon dioxide and titanium dioxide, of which white pigments, such as calcium carbonate, silicon 214 183~
dioxide, titanium dioxide and barium sulfate are pre-ferred.
The titanium dioxide particles comprise at least 95% by weight of rutile and are preferably employed with a coating of inorganic oxides, as usually used as a coating for TiO2 white pigment in papers or paints in order to improve the light fastness. Particularly suitable inorganic oxides include the oxides of aluminum, silicon, zinc and magnesium or mixtures of two or more of these compounds. They are precipitated from water-soluble compounds, for example alkali metal aluminate, in par-ticular sodium aluminate, aluminum hydroxide, aluminum sulfate, aluminum nitrate, sodium silicate or silicic acid, in aqueous suspension. Coated Tio2 particles are described, for example, in EP-A-0 078 633 and EP-A-0 044 515.
The coating may also contain organic compounds containing polar and nonpolar groups. Preferred organic compounds are alkanols and fatty acids having 8 to 30 carbon atoms in the alkyl group, in particular fatty acids and primary n-alkanols having 12 to 24 carbon atoms, and polydi-organosiloxanes and/or polyorganohydrosiloxanes, such as polydimethylsiloxane and polymethylhydrosiloxane.
The coating on the Tio2 particles usually comprises from 1 to 12 g, in particular from 2 to 6 g, of inorganic oxides, if desired additionally from 0.5 to 3 g, in particular from 0.7 to 1.5 g, of organic compounds, in each case based on 100 g of TiO2 particles. It has proven particularly advantageous for the TiO2 particles to be coated with Al2O3 or with Al2O3 and polydimethylsiloxane.
Opaque embodiments of the films contain vacuole-inducing particles which are incompatible with the polymer matrix and result in the formation of vacuole-like cavities when the film is stretched, the size, type and number of the vacuoles being dependent on the material and on the size 214~83~
of the solid particles and the stretching conditions, such as stretching ratio and stretching temperature. The vacuoles give the films a characteristic pearl-like opaque appearance, caused by light scattering at the vacuole-polymer matrix interfaces. In general, the mean particle diameter of the vacuole-inducing particles is from 1 to 6 ~m, preferably from 1.5 to 5 ~m. The base layer generally contains vacuole-inducing particles in an amount of from 1 to 25% by weight.
Conventional vacuole-inducing particles in the base layer are inorganic and/or organic, polypropylene-incompatible materials, such as alu~inum oxide, aluminum sulfate, barium sulfate, calcium carbonate, magnesium carbonate, silicates, such as aluminum silicate (kaolin clay) and magnesium silicate (talc), silicon dioxide and titanium dioxide, of which calcium carbonate, silicon dioxide and titanium dioxide are preferred. Suitable organic fillers are the conventional polymers which are incompatible with the polymers of the base layer, in particular those such as HDPE, polyesters, polystyrenes, polyamides and halo-genated organic polymers, preference being given to polyesters, such as, for example polybutylene tere-phthalates or polyethylene terephthalates. For the purposes of the present invention, "incompatible materials or incompatible polymers" is taken to mean that the material or polymer is in the form of a separate particle or a separate phase in the film.
White/opaque films provided with vacuole-inducing part-icles and with pigment contain the vacuole-inducing particles in an amount of from 1 to 10% by weight, preferably from 1 to 5% by weight, and pigment in an amount of from 1 to 7% by weight, preferably from 1 to 5%
by weight.
The density of the opaque or white films can vary within broad limits and depends on the type and amount of fillers. The density is generally in the range from 0.4 g to 1.1 g/cm3. Pigmented films have a density in the order of 0.9 g/cm3 or above, preferably in the range from 0.9 to 1.1 g/cm3. Films containing only vacuole-inducing particles have a density of less than 0.9 g/cm3. For packaging films having a content of vacuole-inducing particles of from 2 to 5% by weight, the density is in the range from 0.6 to 0.85 g/cm3. For films having a content of vacuole-inducing particles of from 5 to 14% by weight, the density is in the range from 0.4 to 0.8 g/cm3. Films containing pigments and vacuole-inducing particles have a density in the range from 0.5 to 0.85 g/cm3, depending on the ratio between the pigment content and the content of vacuole-inducing particles.
The novel multilayer film can, if desired, contain (a) further interlayer(s) between the base and outer layers.
This (these) interlayer(s) which may be present essentially comprise(s) propylene polymers or polypropylene mixtures as described above for the base layer. In principle, the base layer and the interlayer(s) can be made of the same or different propylene polymers or mixtures. The melt flow indices of the polymers for the core layer and the interlayer(s) should, as far as possible, be the same. If desired, the MFI of the inter-layer(s) can be somewhat greater, but the difference should not exceed 20%. If desired, additives in effective amounts in each case can be added to the interlayers.
In a preferred embodiment of the novel film, the propylene polymer of the base layer and/or of the inter-layer is peroxidically degraded.
A measure of the degree of degradation of the polymer is the degradation factor A, which gives the relative change in the melt flow index, measured in accordance with DIN 53 735, of the polypropylene, based on the starting polymer.
A =
MFIl 214483s MFI1 = melt flow index of the propylene polymer before addition of the organic peroxide.
MFI2 = melt flow index of the peroxidically degraded propylene polymer.
In general, the degradation factor A of the propylene polymer employed is in the range from 3 to 15, preferably from 6 to 10.
Particularly preferred organic peroxides are dialkyl peroxides, where the term alkyl radical is taken to mean a conventional saturated, straight-chain or branched lower alkyl radical having up to six carbon atoms.
Particular preference is given to 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and di-t-butyl peroxide.
The novel polyolefin film furthermore contains at least one heat-sealable outer layer. This outer layer essentially comprises heat-sealable polymers of ~-olefins having 2 to 10 carbon atoms and approximately spherical ceramic particles and, if desired, further additives in effective amounts in each case. In general, the outer layer comprises from 75 to approximately 100% by weight, in particular from 90 to 99.5% by weight, of the heat-sealable ~-olefinic polymer.
Examples of such heat-sealable ~-olefinic polymers are a copolymer of ethylene and propylene or ethylene and 1-butylene or propylene and 1-butylene or a terpolymer of ethylene and propylene and 1-butylene or a mixture of two or more of said homopolymers, copolymers and terpolymers or a blend of two or more of said homopolymers, copolymers and terpolymers, if desired mixed with one or more of said homopolymers, copolymers and terpolymers, 219983~
particular preference being given to random ethylene-propylene copolymers having an ethylene content of from 1 to 10% by weight, preferably from 2.5 to 8% by weight or random propylene-1-butylene copolymers having a butylene content of from 2 to 25% by weight, preferably from 4 to 20% by weight, in each case based on the total weight of the copolymer, or random ethylene-propylene-1-butylene terpolymers having an ethylene content of from 1 to 10% by weight, preferably from 2 to 6% by weight, and a 1-butylene content of from 2 to 20% by weight, preferably from 4 to 20% by weight, in each case based on the total weight of the terpolymer, or a blend of an ethylene-propylene-1-butylene ter-polymer and a propylene-1-butylene copolymer having an ethylene content of from 0.1 to 7% by weight and a propylene content of from 50 to 90% by weight and a 1-butylene content of from 10 to 40% by weight, in each case based on the total weight of the polymer blend.
The above-described copolymers and terpolymers generally have a melt flow index of from 1.5 to 30 g/10 min, preferably from 3 to 15 g/10 min and generally have a melting point in the range from 120 to 140C. The above-described blend of copolymers and terpolymers generally has a melt flow index of from 5 to 9 g/10 min and a melting point of from 120 to 150C. All the melt flow indices given above are measured at 230C and a force of 21.6 N (DIN 53 735).
If desired all the outer layer polymers described above 2I 4483~
can be peroxidically degraded in the same way as described above for the base layer, basically the same peroxides being used. The degradation factor for the outer layer polymers is generally in the range from 3 to 15, preferably from 6 to 10.
According to the invention, the outer layer contains approximately spherical particles which essentially comprise a ceramic material and, if desired, have a coating of an organic and/or inorganic substance. For the purposes of the present invention, approximately spherical particles are particles which satisfy the following condition:
f = ~A/(~/4)/Dmax in which f is greater than 0.7, preferably from 0.8 to 1, in particular from 0.9 to 1, A is the cross-sectional area in mm2, and DmaX is the m~;mllm diameter of the cross-sectional area in mm. The factor f is a measure of the degree of sphericalness of the particles. The closer f is to 1, the closer the shape of the particles is to the ideal spherical shape.
The ceramic material is preferably sodium silicate, aluminum silicate or corresponding mixed silicates. The mean particle diameter is generally in the range from 0.5 to 10 ~m, preferably from 1 to 5 ~m. The antiblocking agent particles are essentially free from siloxane resin compounds. If desired, the spherical particles have an organic and/or inorganic coating, which is also essen-tially free from siloxane.
Particularly suitable inorganic coatings include the oxides of aluminum, silicon, zinc or magnesium or mixtures of two or more of these compounds. They are precipitated from water-soluble compounds, for example alkali metal aluminates, in particular sodium aluminate, aluminum hydroxide, aluminum sulfate, aluminum nitrate, sodium silicate or silicic acid, in aqueous suspension.
If desired, the coating can also comprise or contain 214~835 organic compounds containing polar and nonpolar groups.
Preferred organic compounds are alkanols and fatty acids having 8 to 30 carbon atoms in the alkyl group, in particular fatty acids and primary n-alkanols having 12 to 24 carbon atoms, and maleic anhydride, polypropylene wax and polyethylene wax.
Surprisingly, there is an interaction of structure and substance of the antiblocking agent particles in the spherical ceramic particles used in accordance with the invention. It has been found that films containing known spherical particles of silicone resin in the outer layer have worse haze and worse gloss. Compared with known antiblocking agent particles having an organic coating, an entirely unexpected improvement in gloss, haze, friction and surface roughness of the film has been found in the novel film. Opaque e-mbodiments of the film like-wise exhibit improved gloss and low friction and low surface roughness. Haze is of course unimportant in opa~ue films.
The novel multilayer film comprises the above-described base layer and at least one outer layer and, if desired, further layers. Preference is given to three-layer embodiments containing outer layers on both sides of the base layer; these outer layers can have the same or different thicknesses and compositions. Preference is also given to five-layer embodiments containing a base layer, interlayers applied to both sides of the base layer, and outer layers on both sides.
The overall thickness of the multilayer polyolefin film according to the invention can vary within broad limits and depends on the intended application. It is preferably from 5 to 70 ~m, in particular from 10 to 50 ~m, the base layer mAk;ng up from about 50 to 90% of the overall film thickness.
The thickness of the outer layer(s) is generally greater 214~83~
than 0.2 ~m and is preferably in the range from 0.3 to 2 ~m, in particular from ~ 0.5 to 1 ~m, where outer layers on both sides may have the same or different thicknesses.
The thickness of any interlayer(s) present is generally, in each case independently of any others, from 1 to 12 ~m, preferably from 2 to 8 ~m, in particular from 3 to 6 ~m. The values indicated are in each case based on one interlayer.
In addition to this selected outer layer additive, the multilayer film according to the invention may addi-tionally contain neutralizers, stabilizers, lubricants, hydrocarbon resins and/or antistatics, in one or more layers. The percentages by weight given below relate to the weight of the respective layer to which the additive has been added.
Neutralizers are preferably dihydrotalcite, calcium stearate and/or calcium carbonate having a mean particle size of at most 0.7 ~m, an absolute particle size of less than 10 ~m and a specific surface area of at least 40 m2/g. In general, the neutralizer is added in an amount of from 0.02 to 0.1% by weight.
Stabilizers which can be added are the conventional stabilizing compounds for polymers of ethylene, propylene and other ~-olefins. The amount in which they are added is between 0.05 and 2% by weight. Particularly suitable are phenolic stabilizers, alkali/alkaline earth metal stearates and/or alkali/alkaline earth metal carbonates.
Phenolic stabilizers are preferred in an amount of from 0.1 to 0.6% by weight, in particular from 0.15 to 0.3% by weight, and having a molecular weight of greater than 500 g/mol.Pentaerythrityltetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene are particularly advantageous.
, Lubricants are higher aliphatic acid amides, higher aliphatic acid esters, waxes and metal soaps, and poly-dimethylsiloxanes. The effective amount of lubricant is in the range from 0.1 to 3% by weight. The addition of higher aliphatic acid amides in the range from 0.15 to 0.25% by weight to the base layer and/or the outer layers is particularly suitable. A particularly suitable ali-phatic acid amide is erucamide.
Hydrocarbon resins are low-molecular-weight polymers whose molecular weight is generally in the range from 300 to 8000, preferably from 400 to 5000, in particular from 500 to 2000. The molecular weight of the resins is thus significantly lower than that of the propylene polymers forming the main component of the individual film layers, which generally have a molecular weight of greater than 100,000. The hydrocarbon resins are preferably added to the base layer and/or the interlayer(s). The effective amount of low-molecular-weight resin is from 1 to 20% by weight, preferably from 2 to 10% by weight, based on the layer.
The low-molecular-weight resin recommended is a natural or synthetic resin having a softening point of from 60 to 180C, preferably from 80 to 150C, determined in accor-dance with ASTM E-28. Of the numerous low-molecular-weight resins, preference is given to hydrocarbon resins, specifically in the form of petroleum resins, styrene resins, cyclopentadiene resins and terpene resins (these resins are described in Ullmanns Encyklopadie der technischen Chemie [Ullmann's Encyclopedia of Industrial 30 Chemistry], 4th Edition, Volume 12, pages 525 to 555).
Suitable petroleum resins are described in numerous specifications, such as, for example, EP-A-0 180 087, to which reference is expressly made here.
Preferred antistatics are alkali metal alkanesulfonates, polyether-modified, i.e. ethoxylated and/or propoxylated, polydiorganosiloxanes (polydialkylsiloxanes, _ - 16 -polyalkylphenylsiloxanes and the like) and/or the essen-tially straight-chain and saturated, aliphatic, tertiary amines containing an aliphatic radical having 10 to 20 carbon atoms which are substituted by ~-hydroxy-(Cl-C4)-alkyl groups, N,N-bis(2-hydroxyethyl)alkylamines having 10 to 20 carbon atoms, preferably 12 to 18 carbon atoms, in the alkyl radical being particularly suitable. The effective amount of antistatic is in the range from O.OS
to 3% by weight. A further preferred antistatic is glycerol monostearate.
The invention furthermore relates to a process for the production of the multilayer film according to the invention by the coextrusion process known per se, in which, as usual in the coextrusion process, the polymer or polymer mixture of individual layers is compressed and liquefied in an extruder, it being possible for any additives already to be present in the polymer or in the polymer mixture or can be added via the masterbatch method. The melts corresponding to the individual layers of the film are then simultaneously coextruded through a flat-film die, and the extruded multilayer film is taken off over one or more take-off rolls, during which it cools and solidifies.
The resultant film is then stretched longitudinally and transversely to the extrusion direction, which results in orientation of the molecular ch~;næ. The stretching is preferably from 4:1 to 7:1 in the longitudinal direction and from 7:1 to 11:1 in the transverse direction. The longitudinal stretching is expediently carried out with the aid of two rolls rotating at different speeds corres-ponding to the desired stretching ratio, and the trans-verse stretching is carried out with the aid of an appropriate tenter frame.
The biaxial stretching of the film is followed by ~eat setting, during which the film is kept at a temperature of from 100 to 160C for from about 0.5 to 10 seconds.
The film is subsequently wound up in the conventional manner using a wind-up unit.
It has proven particularly favorable to keep the take-off roll or rolls, which also cool and solidify the extruded film, at a temperature of from 20 to 90C.
The temperatures at which longitudinal and transverse stretching are carried out can vary. In general, the longitudinal stretching is preferably carried out at from 100 to 150C and the transverse stretching at from 155 to 10 190 C .
As mentioned above, one or both surfaces of the film can, if desired, be corona- or flame-treated by one of the known methods after the biaxial stretching.
In the case of corona treatment, it is expedient to pass the film between two conductor elements serving as electrodes, with such high voltage, usually an alterna-ting voltage (from about 10 to 20 kV and 20 to 40 kHz) being applied between the electrodes so that spray or corona discharges can occur. The spray or corona discharge ionizes the air above the film surface, causing it to react with the molecules of the film surface, so that polar inclusions are formed in the essentially nonpolar polymer matrix.
For flame treatment with a polarized flame (cf.
US-A-4,622,237), a direct electrical voltage is applied between a burner (negative pole) and a chill roll. The level of the applied voltage is between 500 and 3000 V, preferably in the range from 1500 to 2000 V. Owing to the applied voltage, the ionized atoms accelerate and hit the polymer surface with greater kinetic energy. The chemical bonds within the polymer molecule are easier to break, and free-radical formation proceeds more quickly. The thermal load on the poly~er during this is significantly less than in the case of standard flame treatment, and ` - 18 _ 21 4 483 5 films can be obtained in which the heat-sealing proper-ties of the treated side are even better than those of the untreated side.
The novel film has improved gloss and haze compared with known films having a low coefficient of friction and is also distinguished by a very low coefficient of friction and by low surface roughness. In addition, the film has a low ~;n;mllm heat-sealing temperature. The coefficient of sliding friction of lubricant-free embodiments of the films is generally in the range from 0.3 to 0.7, prefer-ably from 0.3 to 0.5. Films which additionally contain a lubricant, such as, for example, a fatty acid amide, in particular erucamide, have an even further reduced coefficient of sliding friction. In the case of films containing erucamide in the base layer, this is generally in the range from 0.05 to 0.3, preferably from 0.1 to 0.2. The gloss of the novel film is in the range from 90 to 130, preferably from 105 to 130. The haze of trans-parent embodiments is in the range from 0.9 to 3.0, preferably in the range from 0.9 to 2Ø
The invention is now described in greater detail with reference to working examples.
Example 1 A three-layer film having an overall thickness of 20 ~m and an ABA layer structure, i.e. the base layer B was surrounded by two identical outer layers A, was produced by coextrusion and subsequent stepwise orientation in the longitudinal and transverse directions.
The film was subjected to corona treatment on one side (the roll side) before rolling up. The roll side is the side of the film in contact with the first take-off roll.
The surface tension on this side as a consequence of this treatment was from 39 to 40 mN/m. All layers contained 0.13~ by weight of pentaerythrityl tetrakis[4-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate](~Irganox 1010) as 214483~
stabilizer and 0.06% by weight of calcium stearate as neutralizer.
The base layer B essentially comprised a polypropylene homopolymer having an n-heptane-soluble content of 4% by weight and a melting range of from 160 to 162C. The melt flow index of the polypropylene homopolymer was 3.4 g/10 min at 230C and a load of 21.6 N (DIN 53 735).
The base layer contained 0.12% by weight of erucamide having a melting range of from 78 to 82C and 0.12% by weight of N,N-bisethoxyalkylamine (~Armostat 300).
The polyolefinic outer layers essentially comprised an ethylene-propylene-1-butene terpolymer having a content of 3.5% by weight of ethylene, 88.5% by weight of propylene and 8% by weight of 1-butene. The outer layers contained 0.33% by weight of a ceramic, spherical anti-blocking agent having a mean particle diameter of 2 ~m.
Each of the outer layers had a thickness of 0.8 ~m.
Comparative Example 1 Example 1 was repeated, but the antiblocking agent used was 0.33% by weight of a crosslinked silicone resin powder having a mean particle diameter of 2 ~m (~Tospearl 20 from Toshiba Silicone Co., Ltd.).
C~ _=rative Example 2 Example 1 was repeated, but the antiblocking agent used was 0.33% by weight of an organically coated silicon dioxide having a mean particle diameter of 2 ~m (~Sylobloc 44 from Grace).
Example 2 Example 1 was repeated, but the base layer contained no erucamide.
~ative Example 3 Comparative Example 1 was repeated, but the base layer contained no erucamide.
Comparative Example 4 Comparative Example 2 was repeated, but the base layer contained no erucamide.
The properties of the films of the examples and comparative examples are shown in the table below.
The raw materials and films were characterized using the following measurement methods:
Melt flow index The melt flow index was measured in accordance with DIN 53 735 at a load of 21.6 N and at 230C.
Meltinq Point DSC measurement, m~;mllm of the melting curve, heating rate 20C/min.
Determination of the m;n;mllm heat-sealinq temperature Heat-sealed samples (seal seam 20 mm x 100 mm) are produced using a Brugger HSG/ET sealing unit by sealing a film at various temperatures with the aid of two heated sealing jaws at a pressure of 10 N/cm2 for 0.5 s. Test strips 15 mm in width are cut out of the sealed samples.
The T-seal seam strength, i.e. the force necessary to separate the test strips, is determined on a tensile testing machine at a peel rate of 200 mm/min, the seal seam plane forming a right angle with the direction of tension. The m;n;mllm heat-sealing temperature is the temperature at which a seal seam strength of at least 0.5 N/15 mm is achieved.
Seal seam strenqth For the determination, two 15 mm wide film strips were laid one on top of the other and heat-sealed for 0.5 seconds at 130C and a pressure of 1.5 N/mm2 (Brugger NDS instrument, sealing jaws heated on one side). The seal seam strength was determined by the T-peel method.
21~4835 .
Friction The friction was determined in accordance with DIN 53 375. The coefficient of sliding friction was measured 14 days after production.
Surface tension The surface tension was determined by the ink method (DIN 53 364).
Rouqhness The roughness was determined in accordance with DIN 4768 at a cut-off of 0.25 mm.
Haze The haze of the film was measured in accordance with ASTM-D 1003-52. The Holz haze measurement was also carried out in accordance with ASTM-D 1003-52, but, in order to utilize the optimum measuring range, the measurement was carried out on four film layers lying one on top of the other and a 1 slit diaphragm was employed instead of a 4 pinhole diaphragm.
Gloss 20 The gloss was determined in accordance with DIN 67 530.
The reflector value was measured as an optical parameter for the surface of a film. In accordance with the ASTM-D 523-78 and ISO 2813 standards, the angle of incidence was set at 20 or 60. A light beam hits the planar test surface at the set angle of incidence and is reflected or scattered thereby. The light rays hitting the photoelectronic receiver are indicated as a proportional electrical quantity. The measurement value is ~;mensionless and must be given together with the angle of incidence.
214~835 , m ,, oq O O ~ O O ~1 ,, u~ o a~ u~ o o~
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f~ O O ~1 0 0 ri -4~
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~ ~ m c" ~ o ~ o ~
-~,¢ oooooo ., , ,~
O m c~, o o c~ o o ; E~
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~ ~I r~~Ir~ r~ ~1 r I O . r~~ir~ ~I r~ ~1 a ~ . . . . . .
~u x ,, N U~
r~ ~ ~ ~ ~1 ~ ~ r~
:0 _~ ~ ~ ~ X
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w u ~ w w li3 r~ m
Claims (12)
1. An oriented, multilayer polyolefin film comprising a polyolefinic base layer and at least one heat-sealable outer layer, wherein the heat-sealable outer layer contains from 0.01 to 1% by weight, based on the weight of the outer layer, of approxi-mately spherical ceramic particles.
2. A multilayer polyolefin film as claimed in claim 1, wherein the spherical ceramic particles have an organic and/or inorganic coating.
3. A multilayer polyolefin film as claimed in claims 1 and/or 2, wherein the spherical ceramic particles have a mean particle diameter of from 0.5 to 10 µm, preferably from 1 to 5 µm.
4. A multilayer polyolefin film as claimed in any of claims 1 to 3, wherein the spherical ceramic particles essentially comprise sodium silicate, aluminum silicate or corresponding mixed silicates.
5. A multilayer polyolefin film as claimed in any of claims 1 to 4, wherein the spherical ceramic particles contain essentially no crosslinked silicone resin.
6. A multilayer polyolefin film as claimed in any of claims 1 to 5, wherein the spherical ceramic particles satisfy the following conditions:
f = ?A/(.pi./4)/Dmax in which f is greater than 0.7, preferably from 0.8 to 1, in particular from 0.9 to 1, A is the cross-sectional area in mm2, and Dmax is the maximum diameter of the cross-sectional area in mm.
f = ?A/(.pi./4)/Dmax in which f is greater than 0.7, preferably from 0.8 to 1, in particular from 0.9 to 1, A is the cross-sectional area in mm2, and Dmax is the maximum diameter of the cross-sectional area in mm.
7. A multilayer polyolefin film as claimed in any of claims 1 to 6, wherein the outer layers have a thickness of from 0.2 to 2 µm.
8. A multilayer polyolefin film as claimed in any of claims 1 to 7, wherein the multilayer film has a light transparency, measured in accordance with ASTM-D 1039-77, of at most 50%.
9. A process for the production of a multilayer poly-olefin film as claimed in claim 1, in which the melts corresponding to the individual layers of the film are coextruded through a flat-film die, the coextruded film is taken off over a take-off roll whose temperature is from 20 to 90°C, the film is biaxially stretched at a longitudinal stretching ratio of from 4:1 to 7:1 and a transverse stretching ratio of from 7:1 to 11:1, and the biaxially stretched film is heat-set, if desired corona-treated and subsequently wound up.
10. The use of a multilayer polyolefin film as claimed in one or more of claims 1 to 8 as a packaging film.
11. The use of a multilayer polyolefin film as claimed in one or more of claims 1 to 8 for printing and lamination.
12. A laminate comprising a multilayer polyolefin film as claimed in one or more of claims 1 to 8 and paper or board or a further thermoplastic film.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4409119.2 | 1994-03-17 | ||
| DE4409119A DE4409119A1 (en) | 1994-03-17 | 1994-03-17 | Sealable oriented polyolefin multilayer film, process for its production and its use |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2144835A1 true CA2144835A1 (en) | 1995-09-18 |
Family
ID=6513065
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002144835A Abandoned CA2144835A1 (en) | 1994-03-17 | 1995-03-16 | Heat-sealable, oriented, multilayer polyolefin film, process for the production thereof, and the use thereof |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0672522B1 (en) |
| CA (1) | CA2144835A1 (en) |
| DE (2) | DE4409119A1 (en) |
| ES (1) | ES2227532T3 (en) |
| FI (1) | FI951208A (en) |
| ZA (1) | ZA952153B (en) |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62215646A (en) * | 1986-03-17 | 1987-09-22 | Mitsubishi Petrochem Co Ltd | Propylene polymer composition |
| JPS63182212A (en) * | 1987-01-20 | 1988-07-27 | Mizusawa Ind Chem Ltd | Spherical particle of amorphous silica or silica-alumina and their production |
| JP2515884B2 (en) * | 1989-06-06 | 1996-07-10 | 東レ株式会社 | Propylene polymer film |
| EP0430472A3 (en) * | 1989-11-30 | 1992-02-26 | Imperial Chemical Industries Plc | Multiple-layer polyolefin films |
| ES2140472T3 (en) * | 1993-01-25 | 2000-03-01 | Hoechst Trespaphan Gmbh | BIAXIAL-ORIENTED POLYPROPYLENE MULTILAYER FILM, PREPARATION PROCESS AND USE OF THE SAME. |
| DE4306153A1 (en) * | 1993-02-27 | 1994-09-01 | Hoechst Ag | Sealable oriented polyolefin multilayer film, process for its production and its use |
| DE4306154A1 (en) * | 1993-02-27 | 1994-09-01 | Hoechst Ag | Sealable oriented polyolefin multilayer film, process for its production and its use |
| DE4315006A1 (en) * | 1993-05-06 | 1994-11-10 | Hoechst Ag | Sealable, opaque, biaxially oriented polypropylene multilayer film, process for its preparation and its use |
-
1994
- 1994-03-17 DE DE4409119A patent/DE4409119A1/en not_active Withdrawn
-
1995
- 1995-03-09 EP EP95103398A patent/EP0672522B1/en not_active Expired - Lifetime
- 1995-03-09 DE DE59510920T patent/DE59510920D1/en not_active Expired - Fee Related
- 1995-03-09 ES ES95103398T patent/ES2227532T3/en not_active Expired - Lifetime
- 1995-03-15 FI FI951208A patent/FI951208A/en not_active Application Discontinuation
- 1995-03-16 CA CA002144835A patent/CA2144835A1/en not_active Abandoned
- 1995-03-16 ZA ZA952153A patent/ZA952153B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| EP0672522B1 (en) | 2004-07-14 |
| FI951208A0 (en) | 1995-03-15 |
| FI951208A (en) | 1995-09-18 |
| EP0672522A1 (en) | 1995-09-20 |
| DE4409119A1 (en) | 1995-09-21 |
| ZA952153B (en) | 1995-09-18 |
| ES2227532T3 (en) | 2005-04-01 |
| DE59510920D1 (en) | 2004-08-19 |
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| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |