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Title:
COMPOSTABLE FASTENERS
Document Type and Number:
WIPO Patent Application WO/2022/054063
Kind Code:
A1
Abstract:
Provided is a compostable fastener for use with a resealable compostable bag, the fastener comprising first and second opposing profiles, wherein said first profile comprises a first base strip and a first interlocking closure element; and said second profile comprises a second base strip and a second interlocking closure element configured to reversibly engage with said first interlocking closure element, wherein said fastener comprises a mixture of PBAT with PBS and/or PBS A.

Inventors:
LANCRY ELI (IL)
HAVIV AMIT (IL)
RESHEF BOAZ (IL)
DAVID YANIV (IL)
Application Number:
PCT/IL2021/051107
Publication Date:
March 17, 2022
Filing Date:
September 13, 2021
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
TIPA CORP LTD (IL)
International Classes:
B65D65/46; B32B27/08; B32B27/36; B65D30/08; B65D81/34
Foreign References:
CN211106098U2020-07-28
US20200115110A12020-04-16
US20200130896A12020-04-30
JP2007137461A2007-06-07
US20170259976A12017-09-14
US20210237409A12021-08-05
CN212291066U2021-01-05
Other References:
ANONYMOUS: "Explore Compostable Packaging by Reels Applications Segments TIPACLEAR Transparent Films and Laminates", TIPA, 9 August 2020 (2020-08-09), XP055910020, Retrieved from the Internet
ANONYMOUS: "BioBag ® Food Storage Resealable Bags and Sandwich Resealable Bags", BIOBAG, 16 November 2017 (2017-11-16), XP055910023, Retrieved from the Internet
Attorney, Agent or Firm:
PEARL COHEN ZEDEK LATZER BARATZ (IL)
Download PDF:
Claims:
CLAIMS

1. A compostable fastener for use with a resealable compostable bag, the fastener comprising first and second opposing profiles, wherein: a. said first profile comprises a first base strip and a first interlocking closure element; and b. said second profile comprises a second base strip and a second interlocking closure element configured to reversibly engage with said first interlocking closure element. wherein said fastener comprises a mixture of PBAT with PBS and/or PBSA.

2. The compostable fastener according to claim 1, further comprising c. a slider element comprising at least two spaced-apart walls defining a cavity for receiving therein said first and second profiles, wherein said slider element is configured to i. slide along said first and second profiles in a first direction to cause the first and second interlocking closure elements to engage; and ii. slide along said first and second profiles in a direction opposite to said first direction to cause said first and second interlocking closure elements to disengage.

3. The compostable fastener according to claim 1, wherein said first and second interlocking closure elements are configured to engage when manually pressed one against the other and wherein said first and second interlocking closure elements are configured to disengage on being manually pulled apart.

4. The compostable fastener according to any one of claims 1 to 3, wherein said first and second interlocking closure elements each comprise a series of spaced-apart projecting teeth positioned along a longitudinal axis of a respective said base strip, said spaced-apart projecting teeth configured such that each non-terminal tooth of said second base strip reversibly engageable between a pair of adjacent teeth of said first base strip.

5. The compostable fastener according to any one of claim 1 to 3, wherein said first interlocking closure element comprises at least one longitudinally extending projection and said second interlocking closure element comprises at least one longitudinally extending channel, wherein said longitudinally extending projection is configured to reversibly engage within said longitudinally extending channel.

6. The compostable fastener according to claim 1, wherein said mixture comprises PBS at a concentration of 50-70wt% of said composition and PBAT at a concentration of 30-40wt% of said composition.

7. The compostable fastener according to claim 2, wherein said mixture comprises PBS at a concentration of about 60wt% of said composition and PBAT at a concentration of about 40wt% of said composition.

8. The compostable fastener according to claim 1, wherein said mixture comprises PBSA at a concentration of 50-70wt% of said composition and PBAT at a concentration of 30-40wt% of said composition.

9. The compostable fastener according to claim 4, wherein said mixture comprises PBSA at a concentration of about 60wt% of said composition and PBAT at a concentration of about 40wt% of said composition.

10. A compostable resealable bag comprising a body portion having at least first and second opposing bag walls defining an enclosed portion, each of said first and second opposing bag walls having a respective upper edge which when separated form a mouth, thereby providing access to said enclosed portion, and the compostable fastener according to any one of claims 1 to 9 secured to said body portion, wherein said first profile of said fastener is attached to said upper edge of said first bag wall and said second profile of said fastener is attached to said upper edge of said second bag wall.

11. The compostable bag of claim 10, said body portion comprising at least one layer comprising a compostable polymer selected from the group consisting of poly(epsilon- caprolactone) (PCL), a poly hydroxy alkanoate (PHA) and a mixture thereof, and a second hydrophobic polymer selected from the group consisting of polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), poly lactic acid (PLA), polybutylene adipate terphtalate (PBAT), polydioxanone (PDO), polyglycolic acid (PGA) and any mixture thereof.

12. The compostable bag of claim 10 or 11, said body portion comprising at least one layer comprising a mixture of PBSA and PLA.

13. The compostable bag of claim 12, wherein said mixture comprises 70-90wt% PBSA and 10-30wt% PLA.

14. The compostable bag of claim 10 or 11, said body portion comprising at least one layer comprising a mixture of PLA and PCL.

15. The compostable bag of claim 14, wherein said mixture comprises 50-90wt% PLA and 10- 50wt% PCL.

16. The compostable bag of any one of claims 12 to 15, said body portion comprising a three layered sheet wherein said at least one layer is a first outer layer, said sheet further comprising an inner layer and a second outer layer, wherein said inner layer is located between said first outer layer and said second outer layer.

17. The compostable bag of any one of claims 12 to 16, wherein said second outer layer comprises a mixture of PBSA and PLA.

18. The compostable bag of claim 17, wherein said mixture of said second outer layer comprises 70-90wt% PBSA and 10-30wt% PLA.

19. The compostable bag of any one of claims 12 to 16, wherein said first inner layer comprises a mixture of PLA and PCL.

20. The compostable bag of claim 19, wherein said mixture of said first inner layer comprises 50-90wt% PLA and 10-50wt% PCL.

21. The compostable bag of claim 16, wherein said second outer layer comprises 100wt% PBSA.

22. The compostable bag of any one of claims 16 to 21, wherein said inner layer comprises PBAT.

23. The compostable bag of claim 22, wherein said inner layer consists of 100wt% PBAT.

24. The compostable bag of any one of claims 16 to 23, wherein said first outer layer is selected from the group consisting of PBS, PBSA and combinations thereof.

25. The compostable bag of claim 34, wherein said first outer layer comprises 100wt% PBS or 100wt% PBSA.

16

Description:
COMPOSTABLE FASTENERS

FIELD OF THE INVENTION

The present invention, in at least some embodiments, is directed to compostable fasteners and more specifically to compostable fasteners comprising a mixture of PBAT with PBAS and/or PBSA and to compostable bags comprising such fasteners.

BACKGROUND OF THE INVENTION

The use of biodegradable materials had increased over the past years due to the environmentally beneficial properties of such materials. Such materials are now commonly used in the manufacture of a wide range of products, including various types of plastic bags and other forms of packaging.

Examples of such polymers include biopolymers based on polylactic acid (PLA), polyhydroxyalkanoates (PHA), which include polyhydroxybutyrate (PHB), polyhydroxyvalerate (PHV) and polyhydroxybutyrate-hydroxyvalerate copolymer (PHBV), and poly (epsilon-caprolactone) (PCL).

Each of the foregoing biopolymers has unique properties, benefits and weaknesses. For example, PHB and PLA tend to be strong but are also quite rigid or even brittle. This makes them poor candidates when flexible sheets are desired, such as for use in making wraps, bags and other packaging materials requiring good bend and folding capability.

On the other hand, biopolymers such as polybutylene adipate terphtalate (PBAT) are many times more flexible than the biopolymers discussed above and have relatively low melting points so that they tend to be self-adhering and unstable when newly processed and/or exposed to heat.

Further, due to the limited number of biodegradable polymers, it is often difficult, or even impossible, to identify a single polymer or copolymer that meets all, or even most, of the desired performance criteria for a given application.

Some biodegradable polymers are also compostable, i.e. are able to degrade in compost, under either industrial or home composting conditions. Resealable storage bags, such as those produced by Ziploc®, Glad® and Hefty® are known. Such bags are generally produced using non-biodegradable plastics, such as polypropylene.

There is a need for resealable storage bags which are compostable and more preferably home-compostable.

SUMMARY OF THE INVENTION

According to an aspect of some embodiments of the present invention, there is provided a compostable fastener for use with a resealable compostable bag, the fastener comprising first and second opposing profiles, wherein: a. said first profile comprises a first base strip and a first interlocking closure element; and b. said second profile comprises a second base strip and a second interlocking closure element configured to reversibly engage with said first interlocking closure element. wherein said fastener comprises a mixture of PBAT with PBS and/or PBSA.

According to a further aspect of some embodiments of the present invention, there is provided a compostable resealable bag comprising a body portion having at least first and second opposing bag walls defining an enclosed portion, each of said first and second opposing bag walls having a respective upper edge which when separated form a mouth, thereby providing access to said enclosed portion, and the compostable fastener as disclosed herein secured to said body portion, wherein said first profile of said fastener is attached to said upper edge of said first bag wall and said second profile of said fastener is attached to said upper edge of said second bag wall.

BRIEF DESCRIPTION OF THE FIGURES

Some embodiments of the invention are described herein with reference to the accompanying figures. The description, together with the figures, makes apparent to a person having ordinary skill in the art how some embodiments of the invention may be practiced. The figures are for the purpose of illustrative discussion and no attempt is made to show structural details of an embodiment in more detail than is necessary for a fundamental understanding of the invention. For the sake of clarity, some objects depicted in the figures are not to scale.

In the Figures:

Fig. 1A is a schematic representation of the outer surfaces of a compostable fastener comprising first and second interlocking closure elements in accordance with the principles of the present invention;

Fig. IB is a schematic representation of the inner surfaces of the compostable fastener of Fig. 1A;

Fig. 2A is a schematic representation of a slider element for use with the compostable fastener of Figs. 1A, IB;

Fig. 2B is a schematic representation of the compostable fastener of Fig. 1A, IB further comprising the slider element of Fig. 2A;

Fig. 3 is a schematic representation of the structure of a compostable fastener in accordance with an alternative embodiment of the present invention; and

Fig. 4 is a schematic representation of a compostable resealable bag comprising the fastener of Fig. 1.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. In case of conflict, the specification, including definitions, takes precedence.

As used herein, the term “resealable” refers to bags having a fastener which enables the bag to be opened and closed multiple times without causing damage to either the fastener or the bag.

As used herein, the term “bag” is intended to includes pouches, sacks and the like. The term “biodegradable ’ as used herein is to be understood to include a polymer, polymer mixture, or polymer-containing sheet that degrades through the action of living organisms in air, water or any combinations thereof within 1 year. Biodegradable polyester degradation is initially by hydrolysis, to eventually break the polymer into short oligomers, and later by microbial degradation, or microbial digestion. Biodegradable material may break down under a variety of conditions, for example under aerobic or anaerobic conditions, in compost, in soil or in water (such as sea, rivers or other waterways).

Material which may be degraded in compost is referred to as compostable. Hence, as used herein, the term “compostable” refers to a polymer, polymer mixture, or polymer- containing sheet which is degraded by biological processes under aerobic conditions to yield carbon dioxide, water, inorganic compounds and biomass and leaves no visible, distinguishable or toxic residues. Composting of such materials may require a commercial composting facility or the material may be home compostable.

As used herein, the term “home compostable” refers to a polymer, polymer mixture, or polymer-containing sheet which is compostable in a home composting container, i.e. at significantly lower temperatures and in the absence of set conditions as compared to those provided in a commercial composting facility, Home composting is usually carried out in significantly smaller volumes than those used for commercial composting, and do not include an industrial shredding process.

The term “sheet” as used herein is to be understood as having its customary meanings as used in the thermoplastic and packaging arts and includes the term “film”. Such sheets may have any suitable thickness, may be of a single polymer layer or of multiple polymer layers. Such sheets may be manufactured using any suitable method including blown film extrusion and cast film extrusion.

It is to be noted that, as used herein, the singular forms “a”, “an” and “the” include plural forms unless the content clearly dictates otherwise. Where aspects or embodiments are described in terms of Markush groups or other grouping of alternatives, those skilled in the art will recognize that the invention is also thereby described in terms of any individual member or subgroup of members of the group.

As used herein, when a numerical value is preceded by the term "about", the term "about" is intended to indicate +/-10%. As used herein, the terms “comprising “including ' having' and grammatical variants thereof are to be taken as specifying the stated features, integers, steps or components but do not preclude the addition of one or more additional features, integers, steps, components or groups thereof. These terms encompass the terms "consisting of" and "consisting essentially of".

The compostable fasteners disclosed herein can be used with bags useful for containing therein a wide variety of products or substances, such as semi-solid or liquid substances, including ingestible substances such as food substances, drinks and medicines; toiletries and the like, or articles of clothing, textiles and the like.

As known to a person having ordinary skill in the art, some of the polymers discussed herein have one or more names or spelling thereof. For example, poly(epsilon- caprolactone), poly(caprolactone) and polycaprolactone are synonymous and the three terms are used interchangeably. Similarly, polylactic acid and poly(lactic acid) are synonymous.

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the present invention.

Many modifications and variations are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention can be practiced otherwise than as specifically described.

The specific embodiments listed below exemplify aspects of the teachings herein and are not to be construed as limiting.

Citation of any document herein is not intended as an admission that such document is pertinent prior art or considered material to the patentability of any claim of the present disclosure. Any statement as to content or a date of any document is based on the information available to applicant at the time of filing and does not constitute an admission as to the correctness of such a statement.

Referring now to Fig. 1A, there is shown a schematic representation of the outer surfaces of a compostable fastener 10 for use with a resealable compostable bag. Compostable fastener 10 comprises a first profile 12a and a second, opposing profile 12b. First profile 12a comprises a first base strip 14a and a first interlocking closure element 16a. Second profile 12b comprises a second base strip 14b and a second interlocking closure element 16b configured to reversibly engage with first interlocking closure element 16a. Interlocking closure elements 16a and 16b are formed with respective dimensions which enable interlocking closure element 16b to be reversibly engaged with interlocking closure element 16a.

Fastener 10 comprises a mixture of PBAT with PBS and/or PBSA. Hence, in some embodiments, fastener 10 comprises a mixture of PBAT with PBS. In some embodiments, fastener 10 comprises a mixture of PBAT with PBSA. In some embodiments, fastener 10 comprises a mixture of PBAT, PBS and PBSA.

According to some embodiments, wherein fastener 10 comprises a mixture of PBAT with PBS or PBSA, fastener 10 is compostable. According to some embodiments, wherein fastener 10 comprises a mixture of PBAT with PBS, fastener 10 is industrially compostable. According to some embodiments, wherein fastener 10 comprises a mixture of PBAT with PBSA, fastener 10 is industrially compostable or home compostable.

According to some embodiments, the mixture comprises PBS at a concentration of about 50-70wt% of said composition and PBAT at a concentration of about 30-40wt% of said composition, such as about 50wt% PBS with about 50wt% PBAT; about 55wt% PBS with about 45wt% PBAT; about 60wt% PBS with about 40wt% PBAT; about 65wt% PBS with about 35wt% PBAT; or about 70wt% PBS with about 30wt% PBAT of said composition. According to a preferred embodiment, the mixture comprises about 60wt% PBS and about 40wt% PBAT.

According to some embodiments, the mixture comprises PBSA at a concentration of about 50-70wt% of said composition and PBAT at a concentration of about 30-40wt% of said composition, such as about 50wt% PBSA with about 50wt% PBAT; about 55wt% PBSA with about 45wt% PBAT; about 60wt% PBSA with about 40wt% PBAT; about 65wt% PBSA with about 35wt% PBAT; or about 70wt% PBSA with about 30wt% PBAT of said composition. According to a preferred embodiment, the mixture comprises about 60wt% PBSA and about 40wt% PBAT.

According to some embodiments, the fastener is formed from a composition comprising the mixture of PBAT with PBS or PBSA and further comprising at least one selected from the group consisting of an antioxidant (such as Irganox®, BASF), a shp/antiblock agent (such as erucamide slip agent), and a nucleating agent, and combinations thereof.

As shown in the schematic representation of the inner surfaces of fastener 10 as presented in Fig. IB, in some embodiments first interlocking closure element 16a comprises at least one longitudinally extending projection 18 and second interlocking closure element 16b comprises at least one longitudinally extending channel 20 configured to receive therein first longitudinally extending projection 18, such that longitudinally extending projection 18 is configured to reversibly engage within longitudinally extending channel 20. In some embodiments, as shown in Fig. 2A, channel 20 is defined by a first and a second spaced-apart rail 22a, 22b, respectively.

According to some embodiments, first interlocking closure element 16a comprises one, two, three, four or more spaced longitudinally extending projections 18 and second interlocking closure element 16b comprises a corresponding number of longitudinally extending channels 20.

In some embodiments, longitudinally extending channel 20 has a rectilinear crosssection. In some embodiments, longitudinally extending channel 20 has a curved crosssection. A cross section of longitudinally extending projection 18 is determined such that longitudinally extending projection 18 is reversibly engageable within longitudinally extending channel 20.

According to some embodiments, first interlocking closure element 16a is caused to engage with second interlocking closure element 16b by manually pressing longitudinally extending projection 18 of first interlocking closure element 16a into longitudinally extending channel 20 of second interlocking closure element 16b; and first interlocking closure element 16a is caused to disengage from second interlocking closure element 16b by manually pulling longitudinally extending projection 18 out of longitudinally extending channel 20.

According to some embodiments, compostable fastener 10 further comprises a slider element 30 as shown in Fig. 2 A, slider element 30 comprising at least two spaced-apart walls 32a, 32b, respectively, defining a cavity 34 for receiving therein first and second profiles 12a and 12b.

Fig. 2B shows the compostable fastener of Fig. 1A, IB comprising slider element 30 of Fig. 2A. Slider element 30 is configured to slide along first and second profiles 12a, 12b, respectively, in a first direction to cause first and second interlocking closure elements 16a, 16b to engage; and to slide along first and second profiles 12a, 12b in a direction opposite to the first direction, to cause the first and second interlocking closure elements 16a, 16b to disengage.

Referring now to Fig. 3, there is shown an alternative embodiment 40 of the compostable fastener of the present invention wherein first and second interlocking closure elements 16a, 16b each comprise a series of spaced-apart projecting teeth 42a, 42b positioned along a longitudinal axis of a respective base strip 14a, 14b. Spaced-apart projecting teeth 42a, 42b are configured such that each non-terminal tooth of said spaced-apart projecting teeth 42a of first interlocking closure element 16b is reversibly engageable within a space 44 formed between a pair of adjacent projecting teeth 42b of second interlocking closure element 16b.

According to some embodiments, first interlocking closure element 16b is caused to engage with second interlocking closure element 16b by manually pressing spaced-apart projecting teeth 42a of interlocking closure element 16a into space 44; and first interlocking closure element 16a is caused to disengage from second interlocking closure element 16b by manually pulling spaced-apart projecting teeth 42a out of space 44.

According to some embodiments, (not shown), compostable fastener 40 further comprises a slider element 30 comprising at least two spaced-apart walls 32a, 32b, respectively, defining a cavity 34 for receiving therein first and second profiles 12a and 12b.

Slider element 30 is configured to slide along first and second profiles 12a, 12b, respectively, in a first direction , to cause first and second interlocking closure elements 16a, 16b to engage; and to slide along first and second profiles 12a, 12b in a direction opposite to the first direction, to cause the first and second interlocking closure elements 16a, 16b to disengage.

According to an aspect of some embodiments of the present invention, as shown in Fig. 4, there is provided a compostable resealable bag 60 comprising a body portion 62 having at least first and second opposing walls 64a, 64b respectively defining an enclosed region 66, each of first and second opposing bag walls 64a, 64b having a respective upper edge 68a, 68b, respectively, which when separated form a mouth 70, thereby providing access to enclosed region 66, and the compostable fastener 10 as disclosed herein secured to body portion 62. First profile 12a of compostable fastener 10 is attached to first upper edge 68a of first bag wall 64a and second profile 12b of compostable fastener 10 is attached to second upper edge 68b of first bag wall 64b.

According to some embodiments, body portion 62 comprises at least one layer comprising a compostable polymer selected from the group consisting of poly(epsilon- caprolactone) (PCL), a polyhydroxyalkanoate (PHA) and a mixture thereof, and a second hydrophobic polymer selected from the group consisting of polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), poly lactic acid (PLA), polybutylene adipate terphtalate (PBAT), polydioxanone (PDO), polyglycolic acid (PGA) and any mixture thereof.

According to some embodiments, body portion 62 comprises at least one layer comprising a mixture of PBSA and PLA. In some such embodiments, the mixture comprises from about 70wt% to about 90wt% PBSA and from about 10wt% to about 30wt% PLA, such as about 70wt% PBSA with about 30wt% PLA; about 75wt% PBSA with about 25wt% PLA; about 75wt% PBSA with about 25wt% PLA; about 80wt% PBSA with about 20wt% PLA; about 85wt% PBSA with about 15wt% PLA; or about 90wt% PBSA with about 10wt% PLA.

According to some embodiments, body portion 62 comprises at least one layer comprising a mixture of PLA and PCL. In some such embodiments, the mixture comprises from about 50wt% to about 90wt% PLA and from about 10wt% to about 50wt% PCL, such as about 50wt% PLA with about 50wt% PCL; about 55wt% PLA with about 45wt% PCL; about 60wt% PLA with about 40wt% PCL; about 65wt% PLA with about 35wt% PCL; about 70wt% PLA with about 30wt% PCL; about 75wt% PLA with about 25wt% PCL; about 80wt% PLA with about 20wt% PCL; about 85wt% PLA with about 15wt% PCL; or about 90wt% PLA with about 10wt% PCL.

According to some embodiments, body portion 62 comprises a three layered sheet wherein at least one layer is a first outer layer, the sheet further comprises an inner layer and a second outer layer, wherein the inner layer is located between the first outer layer and the second outer layer.

According to some embodiments, the first outer layer comprises a mixture of PBSA and PLA. In some such embodiments, the mixture comprises from about 70wt% to about 90wt% PBSA and from about 10wt% to about 30wt% PLA, such as about 70wt% PBSA with about 30wt% PLA; about 75wt% PBSA with about 25wt% PLA; about 75wt% PBSA with about 25wt% PLA; about 80wt% PBSA with about 20wt% PLA; about 85wt% PBSA with about 15wt% PLA; or about 90wt% PBSA with about 10wt% PLA.

According to some embodiments, the first outer layer is selected from the group consisting of PBS, PBSA and combinations thereof.

According to some embodiments, the first outer layer comprises 100wt% PBS.

According to some embodiments, the first outer layer comprises 100wt% PBSA.

According to some embodiments, the first inner layer comprises a mixture of PLA and PCL. In some such embodiments, the mixture comprises from about 50wt% to about 90wt% PLA and from about 10wt% to about 50wt% PCL, such as about 50wt% PLA with about 50wt% PCL; about 55wt% PLA with about 45wt% PCL; about 60wt% PLA with about 40wt% PCL; about 65wt% PLA with about 35wt% PCL; about 70wt% PLA with about 30wt% PCL; about 75wt% PLA with about 25wt% PCL; about 80wt% PLA with about 20wt% PCL; about 85wt% PLA with about 15wt% PCL; or about 90wt% PLA with about 10wt% PCL.

According to some embodiments, the second outer layer comprises a mixture of PBSA and PLA. In some such embodiments, the mixture comprises from about 70wt% to about 90wt% PBSA and from about 10wt% to about 30wt% PLA, such as about 70wt% PBSA with about 30wt% PLA; about 75wt% PBSA with about 25wt% PLA; about 75wt% PBSA with about 25wt% PLA; about 80wt% PBSA with about 20wt% PLA; about 85wt% PBSA with about 15wt% PLA; or about 90wt% PBSA with about 10wt% PLA.

According to some embodiments, the first outer layer or the second outer layer comprises a mixture of PLA and PCL. In some such embodiments, the mixture comprises from about 50wt% to about 90wt% PLA and from about 10wt% to about 50wt% PCL, such as about 50wt% PLA with about 50wt% PCL; about 55wt% PLA with about 45wt% PCL; about 60wt% PLA with about 40wt% PCL; about 65wt% PLA with about 35wt% PCL; about 70wt% PLA with about 30wt% PCL; about 75wt% PLA with about 25wt% PCL; about 80wt% PLA with about 20wt% PCL; about 85wt% PLA with about 15wt% PCL; or about 90wt% PLA with about 10wt% PCL.

According to some embodiments, the first outer layer comprises PBAT. In some embodiments, the first outer layer consists of 100wt% PBAT. According to some embodiments, the second outer layer comprises 100wt% PBSA.

According to some embodiments, the second outer layer comprises PBAT. In some embodiments, the second outer layer consists of 100wt% PBAT.

According to some embodiments, the inner layer comprises PBAT. In some embodiments, the inner layer consists of 100wt% PBAT.

According to an aspect of some embodiments of the present invention, there is provided a method of producing a compostable fastener as disclosed herein, the method comprising: providing a composition comprising a mixture of PBAT with PBS and/or PBSA; discharging a first portion of said composition through a first extrusion die configured to provide a first extrudate forming said first interlocking closure element; and discharging a second portion of said composition comprising through a second extrusion die configured to provide a second extrudate forming said second interlocking closure element.

According to some embodiments, the method further comprises substantially immediately following said discharging, cooling said extrudate.

According to some embodiments of the method, said cooling comprises introducing said first and said second extrudates into a cold water bath, such as in the temperature range of about 20-30°C, more preferably 15-30°C.

According to some embodiments, the compostable fastener is attached to the bag portion by standard sealing methods as known in the art.

EXAMPLES

In the experimental section below, all percentages are weight percentages.

Materials and Methods

All the embodiments of polymer sheets according to the teachings herein were made using commercially-available raw materials and devices, using one or more standard methods including: polymer resin drying, resin mixing, film extrusion.

Materials The following polymer resins and raw materials were acquired from commercial sources: PBAT poly(butylene adipate terphtalate) PBS poly (butylene succinate)

PLA poly(lactic acid)

PCL poly(epsilon-caprolactone)

Resin drying

Before use, resins were dried overnight in an air flow Shini SCD-160U-120H dryer desiccator heated to 50 °C.

Resin compositions

To make the required resin compositions, the appropriate amounts of the dried PBAT, PBS and PBSA constituent resins were dry-blended, introduced into the feed of a twin screw compounder and then melt extruded to form the resin compositions. During melt extrusion in the compounder, the temperature zone settings were 170-175-180-185-190 °C Die at 190 °C, a screw speed of 350 rpm and pressure 15-25 bar.

The compounded resin compositions was ground into 1-5 mm diameter pellets using strand pelletizer.

Extrusion

Some embodiments of fasteners according to the teachings herein were made by extrusion through extrusion dies having suitable shape, configured to extrude a first and a second interlocking closure element.

Fasteners were made using an extruder using standard settings as known in the art. Typically the composition comprising the mixture of PBAT with PBS and/or PBSA was feed into the extruder with the temperature zone settings 120-190 °C. The screw speed was set to provide an extrudate having the desired thickness in the usual way.

Substantially immediately following extrusion the extrudate was cooled. Cooling is preferably carried out by introducing the extrudate into a cold water bath, such as in the temperature range of about 15-30°C.

The inventions illustratively described herein may suitably be practiced in the absence of any element or elements, limitation or limitations, not specifically disclosed herein. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise indicated.

Although the above examples have illustrated particular ways of carrying out embodiments of the invention, in practice persons skilled in the art will appreciate alternative ways of carrying out embodiments of the invention, which are not shown explicitly herein. It should be understood that the present disclosure is to be considered as an exemplification of the principles of this invention and is not intended to limit the invention to the embodiments illustrated.

Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation, equivalents of the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims.