Development and application of high-performance full-biodegradable express packaging bag

Abstract

The invention provides development and application of a high-performance full-biodegradable express packaging bag, a film and an express packaging bag are prepared from an alloy of biodegradable polyester based on aliphatic and aromatic dicarboxylic acid and an aliphatic dihydroxy compound and a PBSN polymer, and the high-performance full-biodegradable express packaging bag is prepared by adjusting the monomer proportion in the PBSN polymer and the proportion of the monomer in the formula. And optimization and adjustment of different performances of the express packaging bag are realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and particularly relates to the development and application of a high-performance fully biodegradable express delivery packaging bag. Background Art

[0002] According to the National Postal Transportation Administration, the annual usage of express delivery packaging bags reaches 40 billion, and the direct plastic usage exceeds 600,000 tons. Most of them are non-degradable PE material express delivery bags, causing great pollution to the environment. With the implementation of the national "plastic limit order", the express delivery packaging industry has gradually switched to degradable express delivery bags. However, the cost of fully degradable express delivery bags is higher than that of PE, and the acceptance of downstream bag manufacturers is average. Currently, the common cost reduction idea is achieved by adding inorganic mineral powder. However, when the mineral powder filling exceeds a certain proportion, the express delivery packaging bag is prone to problems such as poor sealing performance, low puncture strength, poor printing performance, and poor adhesiveness. Summary of the Invention

[0003] The specific solution of the present invention includes:

[0004] The present invention first provides a polyester alloy, comprising:

[0005] i) 40 to 80 parts by weight of a biodegradable polyester based on aliphatic and aromatic dicarboxylic acids and aliphatic dihydroxy compounds;

[0006] ii) 0.5 to 20 parts by weight of a PBSN polymer;

[0007] The PBSN polymer comprises a polyester main structural unit and a modified unit, and the modified unit comprises a structure of formula (I):

[0008]

[0009] R1 is independently a straight-chain or branched-chain alkylene group of C2-C4;

[0010] R2 is a straight-chain or branched-chain secondary alkylene group of C2-C4;

[0011] The polyester main structural unit is selected from one or more of PBS, PES, PBA, PET, PBT, PTT, PBAT or PBST; preferably PBS.

[0012] Preferably, the proportion of the modified unit containing the structure of formula (I) in the total polyester units of the PBSN polymer is 1-50%, preferably 5-50%.

[0013] Preferably, R2 is a residue of 2-amino-1,3-propanediol or 3-amino-1,2-propanediol;

[0014] Preferably, R1 is a succinic acid residue (i.e., ethyl).

[0015] Preferably, the PBSN polymer content is 1 to 10 parts.

[0016] In a specific embodiment of the present invention, the biodegradable polyester based on aliphatic and aromatic dicarboxylic acids and aliphatic dihydroxy compounds is PBAT; preferably, the weight average molecular weight of PBAT is 100,000 to 150,000.

[0017] Preferably, the PBAT content is 50 to 70 parts by weight.

[0018] On the other hand, the present invention provides a biodegradable polyester film masterbatch, which comprises:

[0019] i) 40 to 80 parts by weight of a biodegradable polyester based on aliphatic and aromatic dicarboxylic acids and aliphatic dihydroxy compounds;

[0020] ii) 0.5 to 20 parts by weight of PBSN polymer;

[0021] iii) 10 to 50 parts by weight of inorganic mineral powder, biomass powder or plasticized starch or a combination thereof.

[0022] In a specific embodiment of the present invention, the inorganic mineral powder includes calcium carbonate or calcium carbonate modified with stearic acid, wollastonite or kaolin or a combination thereof, preferably 20 - 45 parts.

[0023] In a specific embodiment of the present invention, the biomass powder is selected from straw powder or bagasse powder, preferably 0 - 20 parts.

[0024] In a specific embodiment of the present invention, the masterbatch contains 0 to 20 parts by weight of plasticized starch.

[0025] In a specific embodiment of the present invention, the masterbatch further contains 0 to 5 parts by weight of polylactic acid.

[0026] In a specific embodiment of the present invention, the masterbatch further contains 0 to 10 parts by weight of talc powder.

[0027] In a specific embodiment of the present invention, the masterbatch further contains one or more of a compatibilizer, a dispersant, a lubricant and an antioxidant.

[0028] Preferably, the masterbatch further contains 0 - 1 part of a plasticizer.

[0029] The present invention also provides a film, which is made of the above polyester alloy or masterbatch.

[0030] The present invention also provides a packaging bag, preferably an express packaging bag, made of the above film.

[0031] The present invention also provides the use of PBSN polymer in the preparation of packaging bags, preferably express delivery packaging bags, and the PBSN polymer has the above-defined structure.

[0032] Beneficial technology

[0033] 1) By adding PBSN polymer, the comprehensive performance of the degradable express delivery bag is improved.

[0034] 2) The PBSN polymer of the present invention is a fully bio-based biodegradable material, which is more environmentally friendly.

[0035] 3) By adjusting the monomer ratio in the PBSN polymer and its proportion in the formulation, the optimization and adjustment of different properties of the degradable express delivery bag are realized. Moreover, as the addition ratio of PBNS increases, the filling ratio of the corresponding inorganic mineral powder also increases, and the material cost is lower. A solution for a low-cost and high-performance degradable express delivery bag is truly achieved. Detailed implementation mode

[0036] Biodegradable polyesters based on aliphatic and aromatic dicarboxylic acids and aliphatic dihydroxy compounds

[0037] The biodegradable polyesters based on aliphatic and aromatic dicarboxylic acids and aliphatic dihydroxy compounds in the present invention include poly(butylene adipate terephthalate) (PBAT), poly(butylene sebacate terephthalate) (PBSeT), poly(butylene azelate terephthalate) (PBAzT), or poly(butylene succinate terephthalate) (PBST).

[0038] Among them, PBAT is a copolymer of butylene adipate and butylene terephthalate, combining the characteristics of PBA and PBT. It has good ductility and elongation at break, as well as good heat resistance and impact performance. Due to its good film-forming processability and comprehensive performance superior to traditional LDPE materials, PBAT has become the preferred base material for degradable express delivery packaging bags. The PBAT grade used in the examples of the present invention is BASF C1200; blown film grade.

[0039] PBSN polymer

[0040] The PBSN polymer used in the present invention refers to Chinese Patent Application (CN202311583766.2). The preferably used PBSN polymer contains a polyester main structural unit and a modification unit, and the modification unit contains the structure of formula (I):

[0041]

[0042] R1 and R3 are independently a straight-chain or branched-chain alkylene group with 2-4 carbon atoms;

[0043] R2 is a straight-chain or branched-chain secondary alkylene group with 2-4 carbon atoms;

[0044] The polyester main structural unit is selected from one or more of PBS, PES, PBA, PET, PBT, PTT, PBAT or PBST; preferably PBS.

[0045] Preferably, the proportion of the modified unit containing the structure of formula (I) in the total polyester units of the PBSN polymer is 1-50%, preferably 5-50%.

[0046] Preferably, R2 is the residue of 2-amino-1,3-propanediol or 3-amino-1,2-propanediol;

[0047] Preferably, R1 is the residue of succinic acid (i.e., ethylidene).

[0048] Preferably, the melt index of the polyester is less than 130 g / 10 min, according to the ASTM-D1238 standard; preferably, less than 50 g / 10 min.

[0049] The preparation method of the PBSN polymer of the present invention includes:

[0050] Step 1: Carry out an amidation reaction on a primary amino diol (such as 2-amino-1,3-propanediol or 3-amino-1,2-propanediol) with an easily cyclizable dicarboxylic acid (such as succinic acid or glutaric acid) and / or its corresponding acid anhydride to obtain a monomer composition; the monomer composition includes a diol monomer containing an imide ring structure as shown in formula (Ⅱ):

[0051]

[0052] Step 2: Carry out an esterification / transesterification reaction on the monomer composition, a diol for polymer synthesis (such as butanediol or ethylene glycol) and a dicarboxylic acid / ester / acid anhydride for polymer synthesis (such as succinic acid, adipic acid or terephthalic acid) to obtain a PBSN polymer, wherein the structure of the diol monomer containing an imide ring structure polymerized with a diacid is:

[0053] R3 is the residue of a dicarboxylic acid for polymer synthesis or the residue of an easily cyclizable dicarboxylic acid or a combination of both; in the specific embodiments of the present invention, R3 is the residue of succinic acid.

[0054] The PBSN polymers used in the examples are as follows in the table:

[0055]

[0056] Polylactic acid

[0057] The polylactic acid used in the examples of the present invention is Haizheng 101, injection molding grade.

[0058] Thin film

[0059] The present invention further provides a biodegradable thin film prepared from the above masterbatch. The process of processing polymers into thin films is well known in the art. For example, through the blown film process, the polymer masterbatch is heated to a molten state and then blown into a film by high-pressure air and cooled by cold air to form a thin film.

[0060] Packaging bag

[0061] The thin film of the present invention is suitable for express packaging bags and can be prepared into specifications that meet national standards by conventional methods and equipment.

[0062] Process operations and other auxiliary materials

[0063] PBAT, PLA and the selected additives are added to a high-speed mixer and blended for 5 min at a stirring rate of 250 r / min; then the blended components are added to the hopper of a twin-screw extruder for granulation and extrusion, and finally blown into a film for performance testing, with a blown film thickness of 0.05 mm. Among them, the PLA material can be replaced with a PBNS polymer with different monomer ratios to compare its performance; Examples 1-8 show the representative formula types of the degradable express bags of the present invention.

[0064] The processing temperature range of the twin-screw extruder: 100-185 °C, where the temperature of the first section is 100 °C, the temperature of the second section is 130 °C, the temperature of the third section is 155 °C, the temperature of the fourth section is 160 °C, the temperature of the fifth section is 165 °C, and the temperature of the sixth section is 165 °C; the die head temperature is 190 °C;

[0065] Drying temperature: 100 °C, 4 h, moisture less than 400 ppm;

[0066] Blown film machine temperature: the first section is 160 °C, the second section is 165 °C, the third section is 170 °C, the fourth section is 175 °C; blown film thickness 0.05 mm;

[0067] The compatibilizer used in the present invention is selected from one or more of BASF ADR4468, Xiuyuan Chemical KL-4370, styrene maleic anhydride copolymer S-MAH, and pentaerythritol stearate, preferably BASF ADR4468; the addition ratio is 0.1-0.5 parts.

[0068] The lubricating dispersant used in the present invention is selected from one or more of erucamide, oleamide, polyethylene wax, monoglyceryl stearate, calcium stearate, and magnesium stearate, preferably the compound of erucamide and calcium stearate; the addition ratio is 0.1-0.5 parts.

[0069] The antioxidant used in the present invention is selected from BASF hindered phenols 1010, 168, or phosphoric acid phenyl esters, and aluminum trioxide, etc., preferably the compound of BASF 1010 and 168; the addition ratio is 0.1-0.5 parts.

[0070] Performance Test

[0071] Refer to GBT / 166606.3-2018 "Packaging Supplies for Express Bags - Part 3: Packaging Bags" to test the tensile strength, elastic modulus, elongation at break, right-angle tear strength, heat-sealing strength, puncture strength, etc. of the film materials obtained from the examples.

[0072] The test of the melt flow index (abbreviated as MFI) refers to the reference standard ASTM-D1238-2010.

[0073] The soil degradability is tested by laboratory methods as follows: Select forest land, remove the topsoil, take the loose soil at a depth of 10 - 15 cm from the surface, and sieve out obvious solids such as fallen leaves and stones with a sieve to obtain soil particles with a diameter less than 2 mm; Spread the obtained natural soil evenly in a test storage box of 60 cm × 30 cm × 30 cm by its own weight, with the soil pH about 6.8 and the relative humidity maintained at 40%. The resin is hot-pressed into a film in a flat vulcanizer and then cooled with distilled water at 20°C to obtain a resin film with a length of 100 mm, a width of 80 mm, and a thickness of 0.2 mm. The film specimens are buried in the soil at equal intervals for soil degradability testing, and the humidity in the box is controlled at about 40% during the period; After 100 days, take out the specimens, wash them with distilled water, dry them in vacuum and weigh them, calculate the weight loss rate, and use this to characterize the degradation rate of the resin material; Degradation rate = Weight loss rate = (m0 - m) / m0 × 100%; In the formula, m0 is the initial mass of the specimen; m is the final mass of the specimen after 100 days of degradation test.

[0074]

[0075]

[0076] Performance Summary

[0077] 1. Comparing Example 2 with Example 1, with the same addition of mineral powder, when PBSN replaces PLA, the mechanical properties, heat-sealing strength, and puncture strength are significantly improved;

[0078] 2. Comparing Example 3 with Example 1, with the increase in the addition of mineral powder, the cost of the express bag is reduced, but the comprehensive performance declines;

[0079] 3. Comparing Example 4 with Example 1, although the addition of straw powder increases the organic matter content, the dispersion is significantly worse than that of calcium carbonate, and the final performance is lower than that of Example 1;

[0080] 4. Comparing Example 5 with Example 2, the addition of straw powder increases the organic matter content, but the dispersion is significantly worse than that of calcium carbonate, and the final performance is lower than that of 2;

[0081] 5. Comparing Example 6 with Comparative Example 1, the addition of bagasse powder increases the organic matter content, but the dispersion is significantly worse than that of calcium carbonate, and the final performance is lower than that of Example 1;

[0082] 6. The comprehensive comparison of Examples 7, 8, and 9 all shows that the addition of calcium carbonate is superior to bagasse and straw powder;

[0083] 7. Comparing Example 10 with Example 2 and Example 1, it shows that the addition of plasticized starch has better performance than the calcium carbonate group;

[0084] 8. Comparing Examples 11, 12, 13, and 14 with Example 2, it shows that as the monomer ratio increases, the overall performance of the material decreases.

[0085] Summary: The addition of PBSN material to the express bag formula significantly improves the material performance and makes it possible to replace PLA as the preferred choice; secondly, the addition of PBSN material enables straw and bagasse with low original performance to be applied to express bags, which benefits from the performance advantages of the PBSN substrate.

Claims

1. A polyester alloy, comprising: i) 40 to 80 parts by weight of a biodegradable polyester based on aliphatic and aromatic dicarboxylic acids and aliphatic dihydroxy compounds; ii) 0.5 to 20 parts by weight of a PBSN polymer; The PBSN polymer comprises a polyester main structural unit and a modified unit, and the modified unit comprises a structure of formula (I): R1 is independently a straight-chain or branched alkylene group with 2 to 4 carbon atoms; R2 is a straight-chain or branched sub-alkylene group with 2 to 4 carbon atoms.

2. The polyester alloy according to claim 1, wherein: The polyester main structural unit in the PBSN polymer is selected from one or more of PBS, PES, PBA, PET, PBT, PTT, PBAT or PBST; preferably PBS.

3. The polyester alloy according to claim 1, wherein: The proportion of the modified unit containing the structure of formula (I) in the total polyester units of the PBSN polymer is 1-50%, preferably 5-50%; Preferably, R2 is a residue of 2-amino-1,3-propanediol or 3-amino-1,2-propanediol; Preferably, R1 is a succinic acid residue (i.e., ethyl).

4. The polyester alloy according to claim 2, wherein: The biodegradable polyester based on aliphatic and aromatic dicarboxylic acids and aliphatic dihydroxy compounds is PBAT; preferably, the weight-average molecular weight of PBAT is 100,000-150,000; Preferably, the content of PBAT is 50-70 parts by weight.

5. The polyester alloy according to claim 1, wherein the content of the PBSN polymer is 1-10 parts by weight, preferably 4-6 parts by weight.

6. A biodegradable polyester film masterbatch, the polyester film masterbatch comprising: i) 40 to 80 parts by weight of a biodegradable polyester based on aliphatic and aromatic dicarboxylic acids and aliphatic dihydroxy compounds; ii) 0.5 to 20 parts by weight of a PBSN polymer; iii) 10 to 50 parts by weight of an inorganic mineral powder, a biomass powder or a plasticized starch or a combination thereof; The PBSN polymer and the biodegradable polyester are as defined in claims 1-4; Preferably, the inorganic mineral powder includes calcium carbonate or stearic acid-modified calcium carbonate, wollastonite or kaolin or a combination thereof, preferably 20-45 parts by weight; Preferably, the biomass powder is selected from straw powder or bagasse powder, preferably 0-20 parts by weight; Preferably, the masterbatch contains 0 to 20 parts by weight of plasticized starch; Preferably, the masterbatch further contains 0 to 5 parts by weight of polylactic acid; Preferably, the masterbatch further contains 0 to 10 parts by weight of talc powder; Preferably, the masterbatch further contains one or more of a compatibilizer, a dispersant, a lubricant and an antioxidant; Preferably, the masterbatch further contains 0-1 part by weight of a plasticizer.

7. A film, the film being made of the polyester alloy according to claims 1-5 or the masterbatch according to claim 6.

8. A packaging bag made of the film according to claim 7, preferably an express delivery packaging bag.

9. Use of a PBSN polymer in the preparation of a packaging bag, preferably an express delivery packaging bag, the PBSN polymer comprising a polyester main structural unit and a modified unit, the modified unit comprising a structure of formula (I): R1 is a straight-chain or branched-chain C2-C4 alkylene group; R2 is a straight-chain or branched-chain C2-C4 sub-alkylene group; The polyester main structural unit is selected from one or more of PBS, PES, PBA, PET, PBT, PTT, PBAT or PBST; Preferably it is PBS; The proportion of the modified unit containing the structure of formula (I) in the total polyester units of the PBSN polymer is 1-50%, preferably 5-50%; Preferably, R2 is the residue of 2-amino-1,3-propanediol or 3-amino-1,2-propanediol; Preferably, R1 is the residue of succinic acid (i.e., ethyl).

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