Biodegradable composite material and preparation method thereof

Abstract

The invention belongs to the technical field of degradable materials, and particularly relates to a biodegradable composite material and a preparation method thereof. The degradable material is prepared from the following raw materials in parts by weight: 65 to 75 parts of PBAT resin; 25 to 35 parts of PPCP resin; 12 to 22 parts of straw residue fiber; and 7 to 15 parts of a polyurethane prepolymer. The biodegradable composite material disclosed by the invention has excellent light transmittance, barrier property and heat sealability.

Description

Technical Field

[0001] The invention belongs to the technical field of degradable materials, and in particular relates to a biodegradable composite material and a preparation method thereof. Background Art

[0002] With the improvement of global environmental awareness and the advancement of sustainable development, disposable degradable materials will become one of the important development directions in the field of plastic products in the future. Disposable plastic products are widely used, and the market size of degradable materials is gradually expanding. The application field of disposable degradable materials is very wide, not only limited to traditional disposable plastic products, but also expanded to agriculture, medical care, packaging and other fields. The demand for degradable materials has grown significantly. Biodegradable materials can be gradually degraded into water, carbon dioxide and biomass through the decomposition of microorganisms, becoming an effective means to solve plastic pollution.

[0003] Corn stalks are the stalks of the crop corn, which are mainly composed of leaves, stems and pith, and are widely planted all over the world. China is a major corn-growing country. According to statistics, more than 220 million tons of corn stalks are produced each year. However, most of the corn stalks are abandoned on the ground or directly burned, which not only causes waste of resources but also causes environmental pollution. If corn stalks can be fully utilized as raw materials to produce disposable degradable materials, it is possible to achieve high added value utilization of corn stalks, improve environmental problems caused by burning, and effectively alleviate the dilemma of plastic pollution. However, in the prior art, disposable degradable materials made of corn stalks have poor transparency and average barrier properties. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems of poor transparency and general barrier properties of disposable degradable materials made of corn stalks in the prior art, and to provide a biodegradable composite material and a preparation method thereof, wherein the biodegradable composite material has high barrier properties and light transmittance.

[0005] The first aspect of the present invention provides a biodegradable composite material, wherein the raw materials of the biodegradable material include the following components in parts by weight:

[0006] PBAT resin 65-75 parts;

[0007] PPCP resin 25-35 parts;

[0008] 12-22 parts of straw residue fiber;

[0009] Polyurethane prepolymer 7-15 parts;

[0010] Wherein, the preparation method of the polyurethane prepolymer comprises:

[0011] (1) placing polycarbonate diol and poly(1,6-hexanediol adipate) diol under protective gas protection, dehydrating at 105-115° C. for 1-3 hours, cooling to 75-85° C., adding hexamethylene diisocyanate and an organic tin catalyst, and reacting for 2-3 hours to obtain an intermediate product;

[0012] (2) Add the end-capping agent methyl ethyl ketone oxime to the intermediate product and continue the reaction for 1-2 hours to obtain a polyurethane prepolymer.

[0013] Furthermore, the molar ratio of the polycarbonate diol, poly(1,6-hexanediol adipate) diol, hexamethylene diisocyanate and methyl ethyl ketone oxime is 0.2-0.4: 0.6-0.8: 1-3: 0.1-0.3.

[0014] Furthermore, the molecular weight of the polycarbonate diol is 500-1000.

[0015] Furthermore, the added amount of the catalyst is 0.05-0.15% of the total weight of the polycarbonate diol, the poly(1,6-hexanediol adipate) diol and the hexamethylene diisocyanate.

[0016] Furthermore, the method for preparing the straw residue fiber comprises:

[0017] (S1) taking straw and crushing the straw into powder to obtain straw powder;

[0018] (S2) cooking a portion of the straw powder at 80-120° C. for a certain period of time, immersing in water for a certain period of time for fermentation, then filtering, freeze-drying to constant weight, and steam-exploding to obtain a pretreated product A;

[0019] (S3) immersing another portion of the straw powder in water and subjecting it to humification treatment at a temperature of 20-40° C., wherein the humification degree is controlled at 30-40%, and then filtering, freeze-drying to a constant weight, and steam explosion are performed to obtain a pretreated product B;

[0020] (S4) At room temperature, the pretreated material A and the pretreated material B are mixed evenly to obtain straw residue fibers.

[0021] Furthermore, in step (S1), the cooking time is 40-70 minutes, and the fermentation time is 15-30 hours.

[0022] Furthermore, in step (S4), the weight ratio of the pretreated material A to the pretreated material B is 0.8-1.2:1.5.

[0023] Furthermore, the melt index of the PBAT resin at 190° C. and 2.16 kg is 4-6 g / 10 min, preferably 5 g / 10 min.

[0024] Furthermore, the model of the PBAT resin is PBAT THJS-7801 Lanshan Tunhe, and the melt index at 190° C. and 2.16 kg is 5 g / 10 min.

[0025] Furthermore, the glass transition temperature of the carbon dioxide based polyester-polycarbonate terpolymer is 30-50°C, for example, 30°C, 36.3°C, 40.5°C, 45.6°C, 47.4°C, 50°C.

[0026] Furthermore, in the PPCP resin: the mass percentage of polyester in the polymer is 10-40%, for example, 10%, 15%, 33%, 40%; the mass percentage of polyether in the polymer is less than 10%, for example, 2%, 3.6%, 4.9%, 5.8%, 8%, and the rest is polycarbonate content.

[0027] In the present invention, the content of each segment in the PPCP resin is obtained by nuclear magnetic resonance analysis and is a molar content.

[0028] Furthermore, the number average molecular weight of the PPCP resin is 50-120 kDa, for example, 50 kDa, 52.7 kDa, 61.2 kDa, 102 kDa, 110 kDa, and 120 kDa.

[0029] Furthermore, the PDI of the PPCP resin is 1.15-1.4, for example, 1.15, 1.18, 1.27, or 1.35.

[0030] Furthermore, the preparation method of the PPCP resin is prepared by referring to the preparation method in CN111378101A, specifically: monomers phthalic anhydride, propylene oxide, catalysts tetra-n-butylammonium chloride and triethyl boron are added to a high-pressure reactor, a third monomer carbon dioxide is charged, heating is carried out for a ternary ring-opening copolymerization reaction, and after the reaction is completed, the PPCP resin is obtained by precipitation, drying and granulation; wherein the molar ratio of tetra-n-butylammonium chloride to triethyl boron is 1:2-8; the molar feed ratio of tetra-n-butylammonium chloride to phthalic anhydride is 1:50-2000; the molar feed ratio of propylene oxide to phthalic anhydride is 1:2-30; the carbon dioxide pressure of the ring-opening copolymerization reaction is 0.1-3MPa, the reaction temperature is 40-100°C, and the reaction time is 4-15h.

[0031] The second aspect of the present invention provides a method for preparing the above-mentioned biodegradable composite material, which comprises: drying PBAT resin, PPCP resin, straw residue fiber and polyurethane prepolymer and mixing them evenly, melt blending and then extruding to obtain pellets, and blowing the pellets into film.

[0032] Furthermore, the melt blending temperature is 135-150° C., and the rotation speed is 30-50 r / min.

[0033] Furthermore, the film blowing temperature zone is 135-150° C., the screw speed is 10-15 r / min, the traction speed is 3-6 r / min, and the winding speed is 3-5 r / min.

[0034] Compared with the prior art, the present invention has at least the following beneficial effects:

[0035] The biodegradable composite material of the invention has excellent light transmittance, barrier property and heat sealing property.

[0036] At the same time, the preparation method of the biodegradable composite material is simple in process and easy to control in operation, which is conducive to large-scale industrial production. The obtained biodegradable composite material has stable quality, excellent light transmittance, barrier properties and heat sealing properties, and has excellent comprehensive performance. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] Example 1

[0039] This embodiment provides a biodegradable composite material, the raw materials of which include the following components in parts by weight:

[0040] PBAT resin 65 parts;

[0041] PPCP resin 25 parts;

[0042] 12 parts of straw residue fiber;

[0043] 7 parts of polyurethane prepolymer;

[0044] The preparation method of the polyurethane prepolymer comprises:

[0045] (1) placing polycarbonate diol and poly(1,6-hexanediol adipate) diol under protective gas protection, dehydrating at 105-115° C. for 1-3 hours, cooling to 75-85° C., adding hexamethylene diisocyanate and an organic tin catalyst, and reacting for 2-3 hours to obtain an intermediate product;

[0046] (2) Add the end-capping agent methyl ethyl ketone oxime to the intermediate product and continue the reaction for 1-2 hours to obtain a polyurethane prepolymer.

[0047] The molar ratio of the polycarbonate diol, poly(1,6-hexanediol adipate) diol, hexamethylene diisocyanate and methyl ethyl ketone oxime is 0.3:0.7:2:0.2.

[0048] The molecular weight of the polycarbonate diol is 1,000.

[0049] The added amount of the catalyst is 0.08% of the total weight of the polycarbonate diol, the poly(1,6-hexanediol adipate) diol and the hexamethylene diisocyanate.

[0050] The preparation method of the straw residue fiber comprises:

[0051] (S1) taking straw and crushing the straw into powder to obtain straw powder;

[0052] (S2) steaming a portion of the straw powder at 100° C. for a certain period of time, immersing it in water for a certain period of time for fermentation, then filtering it, freeze-drying it to a constant weight, and then steam-exploding it to obtain a pretreated product A;

[0053] (S3) immersing another portion of the straw powder in water and humifying it at 30° C., with the humification degree controlled at 35%, followed by suction filtration, freeze drying to constant weight, and steam explosion to obtain a pretreated product B;

[0054] (S4) At room temperature, the pretreated material A and the pretreated material B are mixed evenly to obtain straw residue fibers.

[0055] In step (S1), the cooking time is 50 minutes and the fermentation time is 20 hours.

[0056] In step (S4), the weight ratio of the pretreated material A to the pretreated material B is 1:1.5.

[0057] The model of PBAT resin is PBAT THJS-7801 Lanshan Tunhe, and the melt index at 190°C and 2.16kg is 5g / 10min;

[0058] PPCP resin was prepared according to the method in Example 2 of CN111378101 B, Mn=102.8 kDa, PDI=1.35, the mass percentage of polyester in the polymer was 39.9%, the mass percentage of polyether in the polymer was 4.9%, the mass percentage of polycarbonate in the polymer was 55.2%, and Tg=47.4°C;

[0059] The preparation method of the biodegradable composite material comprises: drying PBAT resin, PPCP resin, straw residue fiber and polyurethane prepolymer and mixing them uniformly, melting and blending them and then extruding them to obtain pellets, and blowing the pellets into film and forming them;

[0060] The melt blending temperature is 140°C and the rotation speed is 40r / min;

[0061] The film blowing zone is divided into a feeding section, a melting section and a homogenizing section, the temperatures are 135° C., 140° C. and 150° C. respectively, the screw speed is 13 r / min, the traction speed is 5 r / min, and the winding speed is 4 r / min.

[0062] In this embodiment, the thickness of the prepared biodegradable composite material film is 50 microns.

[0063] Example 2

[0064] This embodiment provides a biodegradable composite material, the raw materials of which include the following components in parts by weight:

[0065] PBAT resin 75 parts;

[0066] PPCP resin 35 parts;

[0067] 22 parts of straw residue fiber;

[0068] 15 parts of polyurethane prepolymer;

[0069] The preparation method of the biodegradable composite material comprises: drying PBAT resin, PPCP resin, straw residue fiber and polyurethane prepolymer and mixing them uniformly, melting and blending them and then extruding them to obtain pellets, and blowing the pellets into film and forming them;

[0070] The melt blending temperature is 140°C and the rotation speed is 40r / min;

[0071] The film blowing zone is divided into a feeding section, a melting section and a homogenizing section, the temperatures are 135° C., 140° C. and 150° C. respectively, the screw speed is 13 r / min, the traction speed is 5 r / min, and the winding speed is 4 r / min.

[0072] Comparative Example 1

[0073] The method according to Example 1 is different in that:

[0074] The straw powder is steam exploded to obtain straw residue, and an equal amount of the straw residue is used to replace the straw residue fiber, that is, the raw materials of the degradable material include the following components in parts by weight: 65 parts of PBAT resin; 25 parts of PPCP resin; 12 parts of straw residue; 7 parts of polyurethane prepolymer, and the rest are the same as in Example 1, and finally a biodegradable composite material is prepared.

[0075] Comparative Example 2

[0076] The method according to Example 1 is different in that:

[0077] PBAT resin and PPCP resin are mixed in a weight ratio of 2.6:1, and an equal amount of polyurethane prepolymer is substituted, that is, the raw materials of the degradable material include the following components in weight: 70 parts of PBAT resin; 27 parts of PPCP resin; 12 parts of straw residue fiber, and the rest are the same as in Example 1, and finally a biodegradable composite material is prepared.

[0078] Test Case

[0079] 1. Barrier properties: Oxygen permeability is tested according to GB / T 19789-2005, and water vapor permeability is tested according to GB / T1037-1988;

[0080] 2. Light transmittance: tested in accordance with GB / T 2410-2008;

[0081] 3. Heat seal strength: Heat seal strength test was carried out on a universal testing machine according to standard QB / T2358-1998, with a tensile speed of 300 mm / min.

[0082] The test results are shown in Table 1:

[0083] Table 1 Test results

[0084]

[0085] From the test results in Table 1, it can be seen that the biodegradable composite material in the present invention has excellent light transmittance, barrier properties and heat sealing properties.

[0086] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A biodegradable composite material, characterized in that: The raw materials of the degradable material include the following components by weight: PBAT resin 65-75 parts; PPCP resin 25-35 parts; 12-22 parts of straw residue fiber; Polyurethane prepolymer 7-15 parts; Wherein, the preparation method of the polyurethane prepolymer comprises: (1) placing polycarbonate diol and poly(1,6-hexanediol adipate) diol under protective gas protection, dehydrating at 105-115° C. for 1-3 hours, cooling to 75-85° C., adding hexamethylene diisocyanate and an organic tin catalyst, and reacting for 2-3 hours to obtain an intermediate product; (2) Add the end-capping agent methyl ethyl ketone oxime to the intermediate product and continue the reaction for 1-2 hours to obtain a polyurethane prepolymer.

2. The degradable material according to claim 1, characterized in that: The molar ratio of the polycarbonate diol, poly(1,6-hexanediol adipate), hexamethylene diisocyanate and methyl ethyl ketone oxime is 0.2-0.4: 0.6-0.8: 1-3: 0.1-0.

3.

3. The degradable material according to claim 1, characterized in that: The molecular weight of the polycarbonate diol is 500-1000.

4. The degradable material according to claim 1, characterized in that: The method for preparing the straw residue fiber comprises: (S1) taking straw and crushing the straw into powder to obtain straw powder; (S2) cooking a portion of the straw powder at 80-120° C. for a certain period of time, immersing in water for a certain period of time for fermentation, then filtering, freeze-drying to constant weight, and steam-exploding to obtain a pretreated product A; (S3) immersing another portion of the straw powder in water and subjecting it to humification treatment at a temperature of 20-40° C., wherein the humification degree is controlled at 30-40%, and then filtering, freeze-drying to a constant weight, and steam explosion are performed to obtain a pretreated product B; (S4) At room temperature, the pretreated material A and the pretreated material B are mixed evenly to obtain straw residue fibers.

5. The degradable material according to claim 4, characterized in that: In step (S4), the weight ratio of the pre-treated material A to the pre-treated material B is 0.8-1.2:1.

5.

6. The degradable material according to claim 1, characterized in that: The PBAT resin has a melt index of 4-6 g / 10 min at 190° C. and 2.16 kg.

7. The degradable material according to claim 1, characterized in that: The glass transition temperature of the carbon dioxide-based polyester-polycarbonate terpolymer is 30-50° C.; the number average molecular weight of the PPCP resin is 50-120 kDa; and the PDI of the PPCP resin is 1.15-1.

4.

8. The degradable material according to claim 1, characterized in that: In the PPCP resin, the mass percentage of polyester in the polymer is 10-40%, the mass percentage of polyether in the polymer is less than 10%, and the rest is polycarbonate content.

9. A biodegradable composite material according to any one of claims 1 to 8, characterized in that: The preparation method comprises: drying PBAT resin, PPCP resin, straw residue fiber and polyurethane prepolymer and mixing them uniformly, melting and blending them and then extruding them to obtain pellets, and blowing the pellets to obtain the pellets.

10. The preparation method according to claim 9, characterized in that: The melt blending temperature is 135-150° C., and the rotation speed is 30-50 r / min; the film blowing temperature zone is 135-150° C., the screw rotation speed is 10-15 r / min, the traction speed is 3-6 r / min, and the winding speed is 3-5 r / min.

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