Biodegradable Living Hinge

Abstract

Disclosed is a molded polymeric article comprising a first structural portion, a second structural portion, and a living hinge connecting the first structural portion and the second structural portion, all integrally molded from a polymeric composition comprising: (1) from about 20 to about 95 weight percent of a polyhydroxyalkanoate, (2) from about 5 to about 75 weight percent of a biodegradable polymer selected from the group consisting of polylactic acid, poly(butylene succinate), poly(butylene succinate-co-adipate), poly(caprolactone), and poly(butylene adipate-co-terephthalate), (3) from about 0.01 to about 5.0 weight percent of a nucleating agent, and (4) from about 0.01 to about 5.0 weight percent of at least one processing aid, such as a mold release agent.

Description

[Technical field]

[0001] The present disclosure relates to biodegradable polymer compositions. More particularly, the present disclosure relates to molded polymer articles including living hinges formed from the biodegradable polymer compositions. [Background technology]

[0002] Hinges are ubiquitous in the production and manufacture of mechanical articles. For injection molded polymeric articles, living hinges are commonly used. A living hinge is a thin polymeric section that connects two plastic parts made from the same polymer. Such living hinges must be durable and remain intact without damage or loss of function over the life of the article, which may include hundreds or even thousands of hinge opening and closing cycles. In order to achieve this desired degree of durability, living hinges have been made from polymers that are neither biodegradable nor compostable, such as polypropylene and polyethylene.

[0003] As environmental responsibility and sustainability concerns grow, it would be desirable to provide molded articles with living hinges formed from biodegradable and / or compostable polymers, however, biodegradable polymers are often very brittle, causing failure of the living hinges after only a few cycles of use.

[0004] That is, it would be desirable to provide a molded polymeric article with a living hinge formed from a biodegradable and / or compostable polymer composition, which has improved flexibility and durability to withstand repeated hinge opening and closing cycles over the life of the molded article. Summary of the Invention

[0005] These and other needs are met by a molded polymeric article provided in accordance with the present disclosure. According to one embodiment, the molded polymeric article includes a first structural portion, a second structural portion, and a living hinge connecting the first structural portion and the second structural portion.

[0006] The first structural portion, the second structural portion, and the living hinge are all integrally molded from a polymeric composition comprising: (1) from about 20 to about 95 weight percent of a polyhydroxyalkanoate; (2) from about 5 to about 75 weight percent of a biodegradable polymer selected from the group consisting of polylactic acid, poly(butylene succinate), poly(butylene-succinate-co-adipate), poly(caprolactone), and poly(butylene adipate-co-terephthalate); (3) from about 0.01 to about 5.0 weight percent of a nucleating agent; and (4) from about 0.01 to about 5.0 weight percent of at least one processing aid, such as a mold release agent.

[0007] In certain embodiments, the polymer composition preferably comprises from about 40 to about 95 weight percent polyhydroxyalkanoate and from about 5 to about 60 weight percent of a biodegradable polymer selected from the group consisting of polylactic acid, poly(butylene succinate), poly(butylene-succinate-co-adipate), poly(caprolactone), and poly(butylene adipate-co-terephthalate).

[0008] In some embodiments, the polymer composition more preferably comprises from about 65 to about 90 weight percent polyhydroxyalkanoate and from about 10 to about 35 weight percent of a biodegradable polymer selected from the group consisting of polylactic acid, poly(butylene succinate), poly(butylene succinate-co-adipate), poly(caprolactone), and poly(butylene adipate-co-terephthalate).

[0009] According to certain embodiments, the polymer composition preferably comprises from about 20 to about 95 weight percent of a polyhydroxyalkanoate copolymer, the copolymer preferably being composed of from about 75 to about 99 mole percent of the monomeric residues of hydroxybutyrate and from about 1 to about 25 mole percent of the monomeric residues of hydroxyalkanoate, the hydroxyalkanoate being selected from the group consisting of hydroxyvalerate, hydroxyhexanoate, hydroxyoctanoate, and hydroxydecanoate.

[0010] In some instances, the polymer composition preferably comprises poly-3-hydroxybutyrate-co-3-hydroxyhexanoate ("P(3HB-co-3HHx)").

[0011] In another embodiment, the polymer composition preferably comprises from about 20 to about 95 weight percent of the polyhydroxyalkanoate terpolymer.

[0012] According to one particular embodiment, the polyhydroxyalkanoate of the polymeric composition has a weight average molecular weight of from about 50,000 Daltons to about 2,500,000 Daltons as specified by ASTM D5296-05.

[0013] In certain embodiments, the polymer composition preferably comprises from about 5 to about 75 weight percent poly(butylene-succinate-co-adipate).

[0014] In some embodiments, the polymer composition preferably comprises from about 5 to about 75 weight percent polylactic acid.

[0015] In some embodiments, the polymer composition preferably comprises from about 5 to about 75 weight percent poly(caprolactone).

[0016] In some cases, the polymeric composition preferably comprises from about 5 to about 75 weight percent poly(butylene adipate-co-terephthalate).

[0017] In certain embodiments, the polymer composition is preferably comprised of less than about 25 weight percent filler. More preferably, the polymer composition is comprised of less than about 1 weight percent filler. Even more preferably, the polymer composition is comprised of less than about 0.1 weight percent filler.

[0018] According to certain embodiments, the polymer composition preferably comprises from about 0.01 to about 5.0 weight percent of at least one nucleating agent, which is selected from the group consisting of pentaerythritol, boron nitride, polyhydroxybutyrate, and mixtures thereof. More preferably, the polymer composition comprises from about 0.1 to about 2.0 weight percent of at least one nucleating agent, which is selected from the group consisting of pentaerythritol, boron nitride, polyhydroxybutyrate, and mixtures thereof. Even more preferably, the polymer composition comprises from about 0.1 to about 2.0 weight percent of pentaerythritol.

[0019] In some embodiments, the polymer composition preferably comprises from about 0.01 to about 5.0 weight percent of at least one processing aid, the processing aid comprising an alkylamide. For example, the at least one processing aid can be selected from the group consisting of behenamide, oleamide, erucamide, stearamide, and mixtures thereof. More preferably, the polymer composition comprises from about 0.1 to about 2.0 weight percent of at least one processing aid, the processing aid comprising from the group consisting of behenamide, oleamide, erucamide, stearamide, and mixtures thereof.

[0020] In certain embodiments, the molded polymeric article is preferably a flip-top cap. In other embodiments, the molded polymeric article is preferably a clamshell container. In yet other embodiments, the molded polymeric article is preferably a foldable cutlery. In yet other embodiments, the molded polymeric article is preferably a hinged dental floss. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] In a first aspect, the present disclosure provides a shaped polymeric article comprising at least one living hinge. Preferably, the shaped polymeric article is biodegradable (as specified by ASTM D5338) and / or compostable (as specified by ASTM D6868). More preferably, the shaped polymeric article is both biodegradable and compostable.

[0022] The polymeric article can be molded into various end-use products according to various embodiments of the present disclosure. For example, in one embodiment, the molded polymeric article can be a flip-top cap, such as a cap for toothpaste or shampoo. In another embodiment, the molded polymeric article can be a clamshell container. In yet another embodiment, the molded polymeric article can be a folding cutlery, such as a fork, knife, spoon, or spork. In yet another embodiment, the molded polymeric article is preferably a hinged dental floss.

[0023] Generally, a molded polymeric article comprises a first structural portion, a second structural portion, and a living hinge connecting the first structural portion and the second structural portion.

[0024] For example, if the shaped article is a clamshell container, the first structural portion can be an upper portion of the container and the second structural portion can be a lower portion of the container. In embodiments where the shaped article is a foldable cutlery, the first structural portion can be a handle and the second structural portion can be a portion of the cutlery that is inserted into the mouth.

[0025] In accordance with the present disclosure, the first structural portion, the second structural portion, and the living hinge are all integrally molded from a common polymeric composition. In other words, the first structural portion, the second structural portion, and the living hinge are all molded simultaneously and as a single continuous polymeric article. Typically, this is accomplished by injection molding, although other molding methods can be used.

[0026] The polymeric composition to be formed into an article typically includes at least the following components: (1) a polyhydroxyalkanoate, (2) a biodegradable polymer selected from the group consisting of polylactic acid, poly(butylene succinate), poly(butylene-succinate-co-adipate), poly(caprolactone), and poly(butylene adipate-co-terephthalate), (3) a nucleating agent, and (4) at least one processing aid.

[0027] The amount of polyhydroxyalkanoate in the polymer composition is generally from about 20 to about 95 weight percent of the composition. More preferably, the composition contains from about 40 to about 95 weight percent of polyhydroxyalkanoate. Even more preferably, the composition contains from about 65 to about 90 weight percent of polyhydroxyalkanoate.

[0028] In various embodiments, the polyhydroxyalkanoate may comprise a homopolymer, a copolymer, and / or a terpolymer. In certain embodiments, the polyhydroxyalkanoate more preferably comprises a copolymer. For example, in some instances, the polymer composition preferably comprises poly-3-hydroxybutyrate-co-3-hydroxyhexanoate ("P(3HB-co-3HHx)").

[0029] Polyhydroxyalkanoate copolymers will typically include monomeric residues of a hydroxybutyrate as well as monomeric residues of a second hydroxyalkanoate. For example, in some embodiments, the copolymer is preferably composed of about 75 to about 99 mole percent monomeric residues of hydroxybutyrate and about 1 to about 25 mole percent monomeric residues of a hydroxyalkanoate selected from the group consisting of hydroxyvalerate, hydroxyhexanoate, hydroxyoctanoate, and hydroxydecanoate.

[0030] In other embodiments, the polyhydroxyalkanoate more preferably comprises a terpolymer.

[0031] In some embodiments, the polyhydroxyalkanoates of the polymeric composition preferably have a weight average molecular weight of from about 50,000 Daltons to about 2,500,000 Daltons as specified by ASTM D5296-05.

[0032] The amount of biodegradable polymer selected from the group consisting of polylactic acid, poly(butylene succinate), poly(butylene succinate-co-adipate), poly(caprolactone), and poly(butylene adipate-co-terephthalate) is generally about 5 to about 75 weight percent of the composition. More preferably, the composition comprises about 5 to about 60 weight percent of the biodegradable polymer. Even more preferably, the composition comprises about 10 to about 35 weight percent of the biodegradable polymer.

[0033] That is, in one embodiment, the polymer composition can comprise from about 5 to about 75 weight percent, preferably from about 20 to about 60 weight percent, and more preferably from about 25 to about 50 weight percent poly(butylene-succinate-co-adipate).

[0034] In another embodiment, the polymer composition can comprise from about 5 to about 75 weight percent, preferably from about 20 to about 60 weight percent, and more preferably from about 25 to about 50 weight percent polylactic acid.

[0035] In another embodiment, the polymer composition can comprise from about 5 to about 75 weight percent, preferably from about 20 to about 60 weight percent, and more preferably from about 25 to about 50 weight percent poly(caprolactone).

[0036] In another embodiment, the polymer composition can comprise from about 5 to about 75 weight percent, preferably from about 20 to about 60 weight percent, and more preferably from about 25 to about 50 weight percent poly((butylene adipate-co-terephthalate).

[0037] The polymer composition also includes a nucleating agent. The amount of nucleating agent in the polymer composition is generally from about 0.01 to about 5.0 weight percent of the composition. More preferably, the composition includes from about 0.1 to about 2.0 weight percent of the nucleating agent.

[0038] The nucleating agent is preferably selected from the group consisting of pentaerythritol, boron nitride, polyhydroxybutyrate, and mixtures thereof.

[0039] The polymer composition further comprises at least one processing aid. The amount of processing aid in the polymer composition is generally from about 0.01 to about 5.0 weight percent of the composition. More preferably, the composition comprises from about 0.1 to about 2.0 weight percent of the processing aid. The processing aid can be, for example, a mold release agent. The processing aid is preferably an alkylamide, which can be selected from the group consisting of behenamide, oleamide, elasumid, steramide, and mixtures thereof.

[0040] In some embodiments, the polymer composition may also include one or more plasticizers. Suitable plasticizers include, for example, epoxidized vegetable oils, such as epoxidized soybean oil, epoxidized linseed oil, epoxidized castor oil, epoxidized coconut oil, epoxidized soybean oil, and mixtures thereof; polyethylene glycols, and triglycerides, such as triacetin. The plasticizer may be present in the polymer composition in an amount of about 0.1 to about 10 weight percent, more preferably 1 to about 5 weight percent.

[0041] Significantly, in accordance with the present disclosure, the amount of filler in the polymer composition is minimized. Typically, the polymer composition comprises less than about 25 weight percent of filler. More preferably, the polymer composition comprises less than about 1 weight percent of filler. Even more preferably, the polymer composition comprises less than about 0.1 weight percent of filler. Suitable examples of fillers that can be used in accordance with the present disclosure include hemp, wood flour, oat hulls, coffee husks, clay, calcium carbonate, talc, and starch.

[0042] As discussed above, the polymeric article can be molded into a variety of end-use products. For example, the molded polymeric article can be a flip-top cap (e.g., a toothpaste or shampoo cap), a clamshell container, a foldable cutlery (e.g., a fork, knife, spoon, or spork), or a hinged dental floss.

[0043] In such end-use products, living hinges formed using the polymer compositions of the present disclosure have been found to be durable and flexible enough to survive at least 10 opening and closing cycles without failure. More preferably, the living hinges can survive at least 100 opening and closing cycles without failure.

[0044] At the same time, the living hinge, as well as the entire molded polymeric article, is preferably biodegradable (as specified by ASTM 5338) and / or compostable (as specified by ASTM D6868). More preferably, the molded polymeric article is both biodegradable and compostable.

[0045] The present disclosure is further illustrated by the following embodiments:

[0046] Embodiment 1. A molded polymeric article comprising:

[0047] a first structural portion, a second structural portion, and a living hinge connecting the first structural portion and the second structural portion;

[0048] The first structural portion, the second structural portion, and the living hinge are all integrally molded from a polymer composition comprising:

[0049] about 20 to about 95 weight percent of a polyhydroxyalkanoate;

[0050] about 5 to about 75 weight percent of a biodegradable polymer, the biodegradable polymer being selected from the group consisting of polylactic acid, poly(butylene succinate), poly(butylene succinate-co-adipate), poly(caprolactone), and poly(butylene adipate-co-terephthalate);

[0051] about 0.01 to about 5.0 weight percent of a nucleating agent; and

[0052] from about 0.01 to about 5.0 weight percent of at least one processing aid; 2. The molded polymeric article comprising:

[0053] Embodiment 2. The polymer composition comprises:

[0054] about 40 to about 95 weight percent polyhydroxyalkanoate; and

[0055] about 5 to about 60 weight percent of a biodegradable polymer, the biodegradable polymer being selected from the group consisting of polylactic acid, poly(butylene succinate), poly(butylene succinate-co-adipate), poly(caprolactone), and poly(butylene adipate-co-terephthalate); 2. The shaped polymeric article of embodiment 1, comprising:

[0056] Embodiment 3. The polymer composition comprises:

[0057] about 65 to about 90 weight percent of a polyhydroxyalkanoate; and

[0058] about 10 to about 35 weight percent of a biodegradable polymer, the biodegradable polymer being selected from the group consisting of polylactic acid, poly(butylene succinate), poly(butylene succinate-co-adipate), poly(caprolactone), and poly(butylene adipate-co-terephthalate); 2. The shaped polymeric article of embodiment 1, comprising:

[0059] Embodiment 4. The polymer composition comprises about 20 to about 95 weight percent of a polyhydroxyalkanoate copolymer;

[0060] The polyhydroxyalkanoate copolymer comprises from about 75 to about 99 mole percent of the monomeric residues of hydroxybutyrate, and from about 1 to about 25 mole percent of the monomeric residues of hydroxyalkanoate, the hydroxyalkanoate being selected from the group consisting of hydroxyvalerate, hydroxyhexanoate, hydroxyoctanoate, and hydroxydecanoate. The molded polymeric article of any one of the preceding embodiments.

[0061] Embodiment 5. The shaped polymeric article of any one of the preceding embodiments, wherein the polymeric composition comprises poly-3-hydroxybutyrate-co-3-hydroxyhexanoate ("P(3HB-co-3HHx)").

[0062] Embodiment 6. The shaped polymeric article of any one of the preceding embodiments, wherein the polyhydroxyalkanoate of the polymeric composition has a weight average molecular weight of from about 50,000 Daltons to about 2,500,000 Daltons as specified by ASTM D5296-05.

[0063] Embodiment 7. The shaped polymeric article of any one of the preceding embodiments, wherein the polymeric composition comprises about 5 to about 75 weight percent poly(butylene-succinate-co-adipate).

[0064] Embodiment 8. The shaped polymeric article of any one of the preceding embodiments, wherein the polymeric composition comprises about 5 to about 75 weight percent polylactic acid.

[0065] Embodiment 9. The shaped polymeric article of any one of the preceding embodiments, wherein the polymeric composition comprises about 5 to about 75 weight percent poly(caprolactone).

[0066] Embodiment 10. The shaped polymeric article of any one of the preceding embodiments, wherein the polymeric composition comprises from about 5 to about 75 weight percent poly(butylene adipate-co-terephthalate).

[0067] Embodiment 11. The molded polymeric article of any one of the preceding embodiments, wherein the polymeric composition comprises less than about 25 weight percent of a filler.

[0068] Embodiment 12. The molded polymeric article of any one of the preceding embodiments, wherein the polymeric composition comprises less than about 1 weight percent of a filler.

[0069] Embodiment 13. The molded polymeric article of any one of the preceding embodiments, wherein the polymeric composition comprises less than about 0.1 weight percent of a filler.

[0070] Embodiment 14. The molded polymeric article of any one of the preceding embodiments, wherein the polymeric composition comprises about 0.01 to about 5.0 weight percent of at least one nucleating agent, the nucleating agent being selected from the group consisting of pentaerythritol, boron nitride, polyhydroxybutyrate, and mixtures thereof.

[0071] Embodiment 15. The molded polymeric article of any one of the preceding embodiments, wherein the polymeric composition comprises about 0.1 to about 2.0 weight percent of at least one nucleating agent, the nucleating agent being selected from the group consisting of pentaerythritol, boron nitride, polyhydroxybutyrate, and mixtures thereof.

[0072] Embodiment 16. The shaped polymeric article of any one of the preceding embodiments, wherein the polymeric composition comprises about 0.1 to about 2.0 weight percent pentaerythritol.

[0073] Embodiment 17. The shaped polymeric article of any one of the preceding embodiments, wherein the polymeric composition comprises about 0.1 to about 10 weight percent of at least one plasticizer selected from the group consisting of epoxidized vegetable oils (e.g., epoxidized soybean oil, epoxidized linseed oil, epoxidized castor oil, epoxidized coconut oil, epoxidized soybean oil, and mixtures thereof), polyethylene glycols, triglycerides (e.g., triacetin), and mixtures thereof.

[0074] Embodiment 18. The shaped polymeric article of any one of the preceding embodiments, wherein the polymeric composition comprises about 0.01 to about 5.0 weight percent of at least one processing aid, the processing aid being selected from the group consisting of behenamide, oleamide, and mixtures thereof.

[0075] Embodiment 19. The molded polymeric article of any one of the preceding embodiments, wherein the polymeric composition comprises about 0.1 to about 2.0 weight percent of at least one processing aid, the processing aid being selected from the group consisting of behenamide, oleamide, and mixtures thereof.

[0076] Embodiment 20. The molded polymeric article of any one of the preceding embodiments, wherein the molded polymeric article is a flip top cap.

[0077] Embodiment 21. The molded polymeric article of any one of the preceding embodiments, wherein the molded polymeric article is a clamshell container.

[0078] Embodiment 22. The molded polymeric article of any one of the preceding embodiments, wherein the molded polymeric article is a foldable cutlery.

[0079] Embodiment 23. The shaped polymeric article of any one of the preceding embodiments, wherein the shaped polymeric article is a hinged dental floss.

[0080] The foregoing description of preferred embodiments of the present invention has been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments have been chosen and described as part of an effort to provide the best explanation of the principles of the invention and its practical application, thereby enabling those skilled in the art to utilize the invention in various embodiments, and with various modifications as appropriate to the particular use contemplated. All such modifications and variations are within the scope of the present invention, as defined by the appended claims, when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.

Claims

1. Molded polymer articles, including the following: A first structural part, a second structural part, and a living hinge connecting the first structural part and the second structural part, Equipped with, The first structural part, the second structural part, and the living hinge are all integrally molded from a polymer composition, which is as follows: 20-95% by weight of polyhydroxyalkanoates, A biodegradable polymer selected from the group consisting of polylactic acid, poly(butylene succinate), poly(butylene succinate-co-adipate), poly(caprolactone), and poly(butylene adipate-co-terephthalate) in an amount of 5 to 75 weight percent, A nucleating agent in an amount of 0.01 to 5.0 weight percent, and A molding aid in an amount of 0.01 to 5.0 weight percent, Includes, It contains less than 1% by weight of a filler selected from the group consisting of hemp, wood flour, oat husks, coffee grounds, clay, calcium carbonate, talc, and starch. The aforementioned molded polymer article.

2. The polymer composition is as follows: 40 to 95 weight percent of polyhydroxyalkanoates, and A biodegradable polymer selected from the group consisting of polylactic acid, poly(butylene succinate), poly(butylene succinate-co-adipate), poly(caprolactone), and poly(butylene adipate-co-terephthalate) in an amount of 5 to 60 weight percent, A molded polymer article according to claim 1, comprising:

3. The polymer composition is as follows: 65 to 90 weight percent of polyhydroxyalkanoates, and A biodegradable polymer selected from the group consisting of polylactic acid, poly(butylene succinate), poly(butylene succinate-co-adipate), poly(caprolactone), and poly(butylene adipate-co-terephthalate) in an amount of 10 to 35 weight percent, A molded polymer article according to claim 1, comprising:

4. The polymer composition comprises 20 to 95 weight percent of a polyhydroxyalkanoate copolymer. The polyhydroxyalkanoate copolymer comprises 75 to 99 mole percent of monomeric residues of hydroxybutyrate and 1 to 25 mole percent of monomeric residues of hydroxyalkanoate selected from the group consisting of hydroxyvalerate, hydroxyhexanoate, hydroxyoctanoate, and hydroxydecanoate. The molded polymer article according to claim 1.

5. The molded polymer article according to claim 1, wherein the polymer composition comprises poly-3-hydroxybutyrate-co-3-hydroxyhexanoate ("P(3HB-co-3HHx)").

6. The molded polymer article according to claim 1, wherein the polymer composition comprises 20 to 95 weight percent of a polyhydroxyalkanoate terpolymer.

7. The molded polymer article according to claim 1, wherein the polyhydroxyalkanoate in the polymer composition has a weight-average molecular weight of about 50,000 daltons to about 2,500,000 daltons, as specified by ASTM D5296-05.

8. The molded polymer article according to claim 1, wherein the polymer composition contains less than 1% by weight of a filler.

9. The molded polymer article according to claim 1, wherein the polymer composition comprises 0.01 to 5.0 weight percent of at least one nucleating agent selected from the group consisting of pentaerythritol, boron nitride, polyhydroxybutyrate, and mixtures thereof.

10. The molded polymer article according to claim 1, wherein the polymer composition comprises 0.1 to 2.0 weight percent of at least one nucleating agent selected from the group consisting of pentaerythritol, boron nitride, polyhydroxybutyrate, and mixtures thereof.

11. The molded polymer article according to claim 1, wherein the polymer composition comprises 0.1 to 2.0 weight percent of pentaerythritol.

12. The molded polymer article according to claim 1, wherein the polymer composition comprises 0.01 to 5.0 weight percent of at least one molding aid selected from the group consisting of behenamide, oleamide, erucamide, steramide, and mixtures thereof.

13. The molded polymer article according to claim 1, wherein the polymer composition comprises 0.1 to 2.0 weight percent of at least one molding aid selected from the group consisting of behenamide, oleamide, erucamide, steramide, and mixtures thereof.

14. The molded polymer article according to claim 1, wherein the molded polymer article is a flip-top cap.

15. The molded polymer article according to claim 1, wherein the molded polymer article is a clamshell container.

16. The molded polymer article according to claim 1, wherein the molded polymer article is a foldable cutlery.

17. The molded polymer article according to claim 1, wherein the molded polymer article is a hinged dental floss.