Patent Application
20100247935
The present disclosure relates generally to polymer films. More particularly, the present disclosure relates to non-PVC polymer films comprising novel peel seal and/or barrier layers.
Multilayer coextruded films are widely used throughout a variety of industries, for example, including use in containers for food or medical solution packaging. One of the desired properties of a multilayer extruded in film is its toughness or ability to resist damage in use or transport. Another desired property is the ability to make both a peel seal at the desired strength to suit the application as well as a permanent seal to permanently enclose a container. An additional desired property is to provide a barrier to gases such as oxygen, carbon dioxide or water vapor in order to maintain the stability of contained solutions.
Traditional flexible polyvinyl chloride materials have also typically been used to fabricate medical grade containers. Polyvinyl chloride (“PVC”) is a cost effective material for constructing such devices. However, PVC may generate objectionable amounts of hydrogen chloride (or hydrochloric acid when contacted with water) upon incineration. PVC sometimes contains plasticizers that may leach into drugs or biological fluids or tissues that come in contact with PVC formulations.
The present disclosure generally relates to films having peel seal layers and/or barrier layers. In a general embodiment, the present disclosure provides a film comprising a peel seal layer comprising a blend of a polypropylene (PP) random copolymer having a melting temperature greater than 140° C., a styrene-ethylene-butylene-styrene block copolymer (SEBS) and a linear low-density polyethylene (LLDPE) having a melting temperature greater than 115° C.
In an embodiment, the blend comprises about 60% to about 80% by weight of a polypropylene random copolymer having a melting temperature greater than 140° C., about 15% to about 30% by weight of a styrene-ethylene-butylene-styrene block copolymer, and about 2.5% to about 20% by weight of an LLDPE having a melting temperature greater than 115° C.
In another embodiment, the blend comprises about 70% by weight of a polypropylene random copolymer having a melting temperature greater than 145° C., about 22.5% by weight of a styrene-ethylene-butylene-styrene block copolymer, and about 7.5% by weight of an LLDPE having a melting temperature greater than 120° C. The LLDPE can be ethylene-octene-1 copolymer, ethylene-hexene-1 copolymer, or a combination thereof.
In an embodiment, the film comprises a skin layer and a barrier layer. For example, the skin layer and the peel seal layer can be attached to the barrier layer on opposing sides of the barrier layer. The skin layer can comprise a random copolymer polypropylene, homo-polymer polypropylene, polypropylene based TPO, nylon, styrene-ethylene-butylene-styrene block copolymer, copolyester ether, or a combination thereof. The barrier layer can comprise polyamide (nylon), for example polyamide 6,6/6,10 copolymer, polyamide 6, amorphous polyamide, rubber modified Nylon, or a combination thereof.
In an embodiment, the film comprises at least one tie layer that attaches at least one of the skin layer and the peel seal layer to the barrier layer. The tie layer can comprise maleated LLDPE, maleated polypropylene homo-polymer, maleated polypropylene copolymer, maleated TPO, or a combination thereof.
In another embodiment, the present disclosure provides a film comprising a peel seal layer comprising a blend of a polypropylene random copolymer having a melting temperature greater than 140° C. and an ethylene-propylene rubber modified polypropylene elastomer. The blend can comprise about 20% to about 40% by weight of the polypropylene random copolymer and about 60% to about 80% by weight of the ethylene-propylene rubber modified polypropylene elastomer.
In an embodiment, the film can comprise a skin layer, seal layer, and a barrier layer. The skin layer and the peel seal layer can be attached to the barrier layer on opposing sides of the barrier layer. The skin layer can comprise polypropylene homopolymer, polypropylene random copolymer, polypropylene based TPO, polyamide (nylon), styrene-ethylene-butylene-styrene block copolymer, copolyester ether copolymer, or a combination thereof. The barrier layer can comprise one or more polyamides (nylon), such as polyamide 6, polyamide 6,6/6,10 copolymer, amorphous polyamide, rubber modified, or a combination thereof. The film can further comprise at least one tie layer that attaches at least one of the skin layer and the peel seal layer to the barrier layer.
In an alternative embodiment, the present disclosure provides a film comprising a barrier layer comprising a caprolactam-free nylon compound. The caprolactam-free nylon compound can comprise a blend of about 75% to about 95% by weight of a polyamide 6,6/6,10 copolymer and about 5% to about 25% by weight of amorphous polyamide. In another embodiment, the caprolactam-free nylon compound comprises a blend of about 87.5% by weight of a polyamide 6,6/6,10 copolymer and about 12.5% by weight of amorphous polyamide.
In an embodiment, the film having the caprolactam-free nylon barrier layer can comprise a skin layer and a peel seal layer. The skin layer and the peel seal layer can be attached to the barrier layer on opposing sides of the barrier layer. The skin layer can comprise polypropylene homopolymer, polypropylene random copolymer, polypropylene based TPO, polyamide (nylon), styrene-ethylene-butylene-styrene block copolymer, copolyester ether block copolymer, or a combination thereof. The peel seal layer can comprise a blend of a polypropylene random copolymer having a melting temperature greater than 140° C., a styrene-ethylene-butylene-styrene block copolymer and an LLDPE having a melting temperature greater than 120° C. The film can further comprise at least one tie layer that attaches at least one of the skin layer and the peel seal layer to the barrier layer.
In an embodiment, the film may include a core layer positioned between the skin layer and the peel seal layer, for example between the skin layer and the barrier layer or between the peel seal layer and the barrier layer. The core layer may contain propylene-ethylene copolymer, syndiotactic propylene-ethylene copolymer, polypropylene elastomer, polypropylene homopolymer, propylene based elastomer, ethylene based elastomer, styrene-ethylene-butylene-styrene block copolymer, ethylene-propylene rubber modified polypropylene, or a combination thereof.
In another embodiment, the film can be used to make any suitable container, for example, used to hold a substance such as a pharmaceutical or a medical compound or solution. The present disclosure provides a container comprising a first sidewall and a second sidewall sealed together along at least one peripheral edge to define a fluid chamber. At least one of the first and second sidewall of the container is a film comprising at least one of 1) a peel seal layer comprising a blend of a polypropylene random copolymer having a melting temperature greater than 140° C., a styrene-ethylene-butylene-styrene block copolymer and an LLDPE having a melting temperature greater than 115° C.; 2) a peel seal layer comprising a blend of a polypropylene random copolymer having a melting temperature greater than 140° C. and an ethylene-propylene rubber modified polypropylene elastomer; and 3) a barrier layer comprising a caprolactam-free nylon compound.
In an alternative embodiment, the present disclosure provides a multiple chamber container comprising a body defined by a film. The body can include two or more chambers separated by a peelable seal. The film can comprise at least one of 1) a peel seal layer comprising a blend of a polypropylene random copolymer having a melting temperature greater than 140° C., a styrene-ethylene-butylene-styrene block copolymer and an LLDPE having a melting temperature greater than 115° C.; 2) a peel seal layer comprising a blend of a polypropylene random copolymer having a melting temperature greater than 140° C. and an ethylene-propylene rubber modified polypropylene elastomer; and 3) a barrier layer comprising a caprolactam-free nylon compound.
An advantage of the present disclosure is to provide improved non-PVC films.
Another advantage of the present disclosure is to provide improved peel seal layers for polymer films.
Yet another advantage of the present disclosure is to provide improved barrier layers for polymer films.
Still another advantage of the present disclosure is to provide improved methods of making non-PVC films.
Another advantage of the present disclosure is to provide improved containers comprising non-PVC films.
Additional features and advantages are described herein, and will be apparent from the following Detailed Description and the figures.
a)-(c) are cross-sectional views of multiple layer films in an embodiment of the present disclosure.
The present disclosure generally relates to non-PVC films having peel seal layers and/or barriers layers. The disclosure provides monolayer films as well as multilayer films useful for packaging applications.
The films in embodiments of the present disclosure have improved toughness and peel seal capability while maintaining good gas barrier properties. This can be accomplished through compounding materials to provide appropriate seal layers that provide the appropriate peel seal range as well as toughness along with choosing skin layers that improve the toughness of the film. In an embodiment, the peel seal layer and barrier layer films can have properties such as toughness or ability to absorb impact energy, sterilizability at 121° C., low haze, barrier to gases, peel sealability using heat sealing machinery and affordability.
In a general embodiment illustrated in
In an embodiment, the peel seal layer blend contains about 60% to about 80% by weight of a random copolymer polypropylene having a melting temperature greater than 145° C., about 15% to about 30% by weight of a styrene-ethylene-butylene-styrene block copolymer and about 2.5% to about 20% by weight of an LLDPE having a melting temperature greater than 120° C. In another embodiment, the blend contains about 70% by weight of a random copolymer polypropylene having a melting temperature greater than 145° C., about 22.5% by weight of a styrene-ethylene-butylene-styrene block copolymer and about 7.5% by weight of an LLDPE having a melting temperature greater than 120° C. The LLDPE can be ethylene-octene-1 copolymer, ethylene-hexene-1 copolymer, or a combination thereof.
In an embodiment illustrated in
In an embodiment shown in
In another embodiment, the present disclosure provides a film including a peel seal layer containing a blend of a polypropylene random copolymer having a melting temperature greater than 145° C. and an ethylene-propylene rubber modified polypropylene elastomer. The blend may contain about 20% to about 40% by weight of a random copolymer polypropylene having a melting temperature greater than 140° C. and about 60% to about 80% by weight of an ethylene-propylene rubber modified polypropylene elastomer.
In an embodiment, the aforementioned film may further include a skin layer and a barrier layer. The skin layer and the peel seal layer can be attached to the barrier layer on opposing sides of the barrier layer. The skin layer may contain polypropylene homopolymer, polypropylene random copolymer, polypropylene based elastomer, polyamide (nylon), styrene-ethylene-butylene-styrene block copolymer, copolyester ether block copolymer, or a combination thereof. The barrier layer can include one or more polyamides (nylon), for example polyamide 6, polyamide 6,6/6,10 copolymer, amorphous polyamide, or a combination thereof. The film can further include at least one tie layer that attaches at least one of the skin layer and the peel seal layer to the barrier layer.
Films including a barrier layer in embodiments of the present disclosure may contain a caprolactam-free nylon barrier material with good gas barrier resistance and adequate toughness for use in multilayer films for medical solution container applications. Traditionally, nylon-6 (polyamide-6) or nylon-6 based blends have provided a good combination of gas barrier and impact resistance. However, nylon-6 cannot be used for plastic solution container applications in certain countries such as Japan, Korea, and China due to their pharmacopoeia requirements. The pharmacopoeia requirements in these countries include limitations on the UV/visible light wavelengths of compounds extracted into solution from the container film materials; these limitations severely limit the permissible amount of caprolactam in the container film. Because polyamide-6 is synthesized from caprolactam, its presence will cause the container film to fail the criteria when used at a thickness that provides useful barrier properties.
In an alternative embodiment, the present disclosure provides a film including a barrier layer containing a caprolactam-free nylon (i.e. polyamide or PA) compound. The caprolactam-free nylon compound can comprise a blend of about 75% to about 95% by weight of a polyamide 6,6/6,10 copolymer and about 5% to about 25% by weight of amorphous polyamide. In another embodiment, the caprolactam-free nylon compound comprises a blend of about 87.5% by weight of a polyamide 6,6/6,10 copolymer and about 12.5% by weight of amorphous polyamide. Suitable amorphous polyamides include, without limitation, polyamide 6I/6T and polyamide MXD6/MXDI copolymer.
In an embodiment illustrated in
As shown in
The films in embodiments of the present disclosure can be used to make any suitable containers, for example, used to hold a substance such as a pharmaceutical or a medical compounds or solution. In an embodiment shown in
In an embodiment, the first sidewall and/or second sidewall is a film having at least one of 1) a peel seal layer comprising a blend of a random copolymer polypropylene having a melting temperature greater than 140° C., a styrene-ethylene-butylene-styrene block copolymer and an LLDPE having a melting temperature greater than 115° C.; 2) a peel seal layer comprising a blend of a random copolymer polypropylene having a melting temperature greater than 140° C. and an ethylene-propylene rubber modified polypropylene elastomer; and 3) a barrier layer comprising a caprolactam-free nylon compound.
In an alternative embodiment shown in
In the illustrated embodiment, any portion of the container 70 is made from a film having at least one of 1) a peel seal layer comprising a blend of a polypropylene random copolymer having a melting temperature greater than 140° C., a styrene-ethylene-butylene-styrene block copolymer and an LLDPE having a melting temperature greater than 115° C., 2) a peel seal layer comprising a blend of a polypropylene random copolymer having a melting temperature greater than 140° C. and an ethylene-propylene rubber modified polypropylene elastomer and 3) a barrier layer comprising a caprolactam-free nylon compound.
The container 70 may be made from two sheets of the film that are, for example, heat sealed along their edges (80, 82, 84, and 86) to form permanent seals. In the illustrated embodiment, two sheets of film are used. The sheets are sealed about the periphery of the container 70 at edges 80, 82, 84, and 86. Alternatively the container may be formed from an extruded tubular film sealed at its open ends. In this case, only two opposing edges of the container (for example edges 82 and 86) need to be sealed. A peelable seal 88 is provided between the sheets of film to form the chambers 74 and 76. Of course, if additional chambers are provided, additional peelable seals can be provided.
The container 70 and the peelable seal 88 can be constructed from films having a peel seal layer in accordance with embodiments of the present disclosure. The peel seal layer can allow both a peelable and permanent seal to be created. Thus, the permanent side seals 80, 82, 84, and 86 as well as the peelable seal 88 can be created from the same layer of film.
As illustrated in
Depending on the methods employed to manufacture the containers, fill ports may not be necessary at all. For example, if the containers are to be manufactured from a continuous roll of plastic film, the film could be folded lengthwise, a first permanent seal created, the first compartment filled with solution, then a peelable seal created, a second compartment filled, a permanent seal created, and so on.
By way of example and not limitation, the following examples are illustrative of various embodiments of the present disclosure.
Blends containing co-polypropylene, SEBS block copolymer and LLDPE were extruded as monolayer films. The seal performance of the post-autoclaved films was evaluated along with some other properties such as clarity (haze), tensile and autoclavability (via the observation on the surface appearance). Comparative testing of films that include a commercial product (CAWITON® PR4581A—comparative-1) and two films having a composition of 60%/25%/15% of co-polypropylene/SEBS/LLDPE (comparative-2 and comparative-3) was performed along with the formulated blends of the present disclosure. In addition, some of the peel seal layer blends of the present disclosure were coextruded with other layers to make multilayered films on which the peel seal performance was evaluated.
As shown in Tables 1 and 2, the peel seal blend formulations 31-19, 34-9, 34-10, 36, 8, 36-9, 36-10 and 36-11 were shown to have:
II. Multilayer Films with No Gas Barrier Layer
Formula 36-9 used as the peel seal layer in a coextruded film, VistaPeel-2 (see Table 4). In contrast, the peel seal layers for Zcore-1 and Vista-1 are Comparative-2 and Comparative-3, respectively.
The peel seal performance for the multiple layer films is summarized in Table 5 and
Table 5 and
III. Multilayer Films with Gas Barrier Layer
Formula 36-9 was applied as the peel seal layer in a coextruded film: NylonPeel-2 (see Table 6). In contrast, the peel seal layers for Symredad and NB-1 are Comparative-1 and Comparative-3, respectively.
The peel seal performance for the multiple layer films is summarized in Table 7 and
Table 7 and
Example 1 provides evidence that formulations comprising a blend of copolymer polypropylene/SEBS/LLDPE provide improved peel seal layers capable of being used in many applications. This study focused on improving the toughness of these films while maintaining peel seal characteristics by compounding elastomeric materials and/or lower melting polyolefins into appropriate layers of a multiple layer film. For example, the present formulations included materials that were compounded into the peel and/or skin layers of various multilayer coextruded films. In addition, PCCE (poly(cyclohexylene dimethylene cyclohexanedicarboxylate), glycol and acid comonomer) was also used as a tough skin layer in combination with newly compounded peel seal layers. The resulting structures were then tested for peel seal, haze, toughness using ASTM D3763, “High Speed Puncture Properties of Plastics Using Load and Displacement Sensors” and/or functional container drop testing.
In the current example, four different peel seal approaches were attempted and compared to the Cawiton baseline. Typical formulations for these peel seal layer approaches are given below.
These peel seal layers were extruded in several multilayer structures with almost identical peel seal curve results. Typical peel seal curves for the different sample formulations are given in
Alternative embodiments of three different iterations of films containing a nylon barrier layer and Sample 3, Sample 4 and Sample 5 peel seal layers were manufactured and tested. The first film iteration included structures with a Sample 3 peel layer and/or a PCCE skin layer and are shown in alternative embodiments of a five layer structures as illustrated in
Alternative embodiments of the second film iteration included structures with a Sample 3 or Sample 4 peel layer and, in two of the structures, a PP/SEBS skin layer. The second iteration film structures include maleic anhydride modified homopolymer (ADMER® QF300E and QB510A) and copolymer (ADMER® 551A) tie layers. All embodiments of these film structures were five layer structures as illustrated in
Alternative embodiments of the third iteration film structures included Sample 3, Sample 4 or Sample 5 blended seal layers along with PCCE or PP/SEBS skin layers. Also, PT-4 includes a maleic anhydride modified homopolymer PP blended with SEBS to further toughen the structure. All the third iteration film structures were five layer structures as illustrated in
The results of impact testing and haze are shown in Table 11. The results showed the films containing the embodiments of Iteration #2 and #3 with the standard EMS FG40NL nylon (TP-4 and N-1 thru N-5) have improved impact toughness over a commercial Maestro film. The results also showed the film containing a PCCE skin layer and the standard EMS FG40NL nylon also have improved impact toughness over the Maestro film.
Based on the material compounds created and the film structures produced and results measured, novel peel seal compounds as well as multilayer films were developed. Examples of these peel seal compounds and film structures are given as follows:
In alternative embodiments, the peel seal layer film is capable of producing a seal by heated dies in multilayer extruded films that can be peeled apart without producing residual debris. By varying the temperature a peel force between 3N/15 mm and 30N/15 mm should be able to be created on the same peel layer compound in a variety of film structures and thicknesses. Peel seals should be created at temperatures greater than 122° C. The seal layer should be capable of sterilization at 121° C. without adversely affecting the peel force. One example of such a material is 60% PP random copolymer having a melting temperature greater than 145° C., 25% SEBS and 15% LLDPE having a melting temperature greater than 120° C. A second example is a blend of 60%-80% PP based TPO such as Zelas 7023 with 20%-40% random copolymer PP having a melting temperature greater than 130° C. A third example is a blend of 70% PP random copolymer having a melting temperature greater than 145° C., 22.5% SEBS and 7.5% LLDPE having a melting temperature greater than 120° C.
The previously described embodiments are directed to a tough and clear multilayer film containing a peel seal layer. The dart impact resistance of the film was shown to give a good correlation to container damage resistance in products. In one embodiment, the desired dart impact resistance is greater than 7 J/mm for the multilayer film. In addition it is desirable to maintain haze less than 20% for the film wetted on one surface. Finally, it is desired to have a CO2 permeability for such a film to be less than 200 cm3/m2 day atm. Examples of such films are TP-4, N-1, N-3, N-4, N-5, PT-1 PT-3, and FGN-2.
A caprolactam-free nylon-6,6/6,10 copolymer (BM20SBG from EMS-Grivory) has been found to be a good candidate from an extrusion standpoint for multilayer barrier films. However, films based on this structure show significantly inferior drop resistance, dart impact properties, and gas (O2 and CO2) permeability than current films containing nylon-6 based barrier layers. Amorphous nylon inherently has significantly improved gas barrier properties. (A minimum blend level to provide adequate gas barrier resistance can be calculated for a given grade using permeability data and a rule of mixtures.) Accordingly, the approach of this study was to blend amorphous nylon at appropriate levels with nylon-6,6/6,10 copolymer to improve the impact resistance and gas barrier resistance while maintaining acceptable clarity, as well as UV absorbance that is acceptable with global medical regulatory requirements.
Amorphous nylon was blended with the nylon-6,6/6,10 copolymer and extruded as monolayers to find the best balance of impact resistance, clarity and permeability. Promising blends were identified and incorporated into one or more of the following film structures shown in
Small-scale process blending trials were conducted of available grades of amorphous nylon, which included EMS GRIVORY® G21 (nylon 6I/6T), EMS GRIVORY® HB5299 (nylon MXD6/MXDI copolymer), EMS GRIVORY®B HB7103 (same), and Dupont SELAR PA (nylon 6I/6T). EMS GRIVORY® HB7103 amorphous nylon was found to have the best combination of clarity, permeability resistance and mechanical properties. Monolayer films were then made using a 50%:50% and 85%:15% blend of EMS GRILON® BM20SBG nylon-6,6/6,10 copolymer and EMS GRIVORY® HB7103 amorphous nylon. The haze, dart impact and predicted permeability of these monolayers were then compared to the baseline EMS FG40NL, which is based on nylon-6, and BM20SBG. The results of this comparison are given in Table 12 below. In Table 12, permeability was calculated at different relative humidity conditions based on a rule of mixtures using available supplier data or measured Baxter data as available. Past industrial experience has also shown that the permeability for CO2 is approximately 4 times higher than O2.
The results in Table 12 show that the best blend was the 85%:15% blend of BM20SBG and HB7103. This blend had approximately twice the dart impact resistance of pure BM20SBG and predicted permeability almost equivalent to the FG40NL nylon currently used in Baxter's Maestro film. The haze of the 85%:15% blend was higher than either pure compound but still acceptable for use in multilayer films. When the blend ratio was changed to 50%:50%, there was no improvement in dart impact properties and an unacceptable increase in haze, as the monolayer film then appears cloudy. Optimization of the blend ratio was possible but given the monolayer properties the 85%:15% blend is satisfactory for current applications. Further testing revealed that adjusting the ratio to 87.5% BM20SBG/12.5% HB7103 provided somewhat better performance.
b= data from EMS-Grivory data sheets and public presentation
A study was completed comparing the 85%:15% blended nylon to pure BM20SBG or FG40NL in a five-layer coextruded film structure. The structures of the studied films are five-layer structures as illustrated in
Results of haze and impact testing are given in Table 14. The haze and impact of the CF-1 & CF-2 films, which contain the 85%:15% nylon blend, were better than NB-1, which contains pure BM20SBG in a similar structure. The impact resistance of CF-2 was better than CF-1 because it contains a polypropylene homopolymer-based tie layer rather than a copolymer-based tie layer, consistent with the trend that has been observed in previous work. The haze of CF-3 was also significantly better than the commercially available Maestro, which contains FG40NL, and the impact is almost equivalent. Both the haze and impact of PT-3, which contains FG40NL in a similar structure, were better than CF-3.
The six-layer structures shown in
Based on the material compounds created, film structures produced, and results measured, novel five and six layer or more nylon barrier film structures can be made incorporating a caprolactam-free nylon blend that meet desired container properties. In an embodiment, the desired dart impact resistance is greater than 4.5 J/mm for the nylon barrier material to be used in a multilayer film. At the same time the nylon barrier layer should have good heat resistance to heat seal temperatures greater than 130° C. and haze less than 15% when wetted on both sides. Finally, the O2 permeability should be less than 80 cm3/m2 day 25 um bar at approximately 85% r.h. (relative humidity).
Descriptions of multiple layer films in alternative embodiments incorporating a caprolactam-free nylon barrier layer and their desired properties are as follows:
In an embodiment, the multiple layer film is a five-layer film as shown in
In another embodiment, the multiple layer film is a six-layer film as shown in
The multiple layer films can also comprise raw materials that do not contain substances (e.g. calcium or magnesium stearate, erucamide, other fatty acids, etc.) that can be leached from the film and/or precipitate to cause particulate matter in a solution having a between a pH ranging from 2 and 10.
It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present subject matter and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.
