Flame-retardant starch-based biomass composite material and preparation method thereof

Abstract

The invention discloses a flame-retardant starch-based biomass composite material and a preparation method thereof. The flame-retardant starch-based biomass composite material comprises starch and N-methylmorpholine-N-oxide, and can also comprise biomass fibers, a biodegradable synthetic polymer, ammonium polyphosphate and pentaerythritol. The mass ratio of the starch to the N-methylmorpholine-N-oxide to the ammonium polyphosphate to the pentaerythritol is (60-75): (20-30): (6-12): (2-5). The preparation method of the flame-retardant starch-based biomass composite material comprises the following steps: firstly, mixing part or all of starch with N-methylmorpholine-N-oxide liquid, and heating to prepare a thermoplastic starch material; and melting, mixing and extruding the thermoplastic starch material, ammonium polyphosphate, pentaerythritol, a reinforcing material and a biodegradable synthetic polymer by adopting a screw extruder. The flame-retardant starch-based biomass composite material disclosed by the invention is completely biodegradable, excellent in mechanical property and flame-retardant property, and the preparation method is simple and convenient.

Description

Technical Field

[0001] The invention relates to a starch-based biomass composite material and a preparation method thereof, in particular to a flame-retardant starch-based biomass composite material and a preparation method thereof, belonging to the field of flame-retardant biodegradable polymer materials and products. Background Art

[0002] With the continuous development of material types and functions, people's requirements for materials are not only excellent performance, but also need to comply with the concept of environmental protection and green ecology. Traditional petrochemical plastics bring many adverse effects to the environment and do not conform to the concept of sustainable development. Therefore, the research on alternative materials for petrochemical plastics has been continuing. Biomass materials are widely available, pure natural and renewable. Biomass-based materials are ideal potential plastic materials. Starch is a common biomass raw material for preparing biomass-based degradable plastics. There are a large number of hydroxyl groups inside it, forming a large number of intramolecular and intermolecular hydrogen bonds, which give biomass-based degradable plastics rigidity and good mechanical properties. However, due to the presence of a large number of hydroxyl groups, it is difficult to thermoplastic process, and starch-based materials are easy to burn. Therefore, it is an important research direction to plasticize starch with a new plasticizer to obtain starch-based materials that can be thermoplastically formed, especially to develop thermoplastic starch-based materials with good flame retardancy, good mechanical properties and biodegradability, which will help promote and apply biomass-based plastics in more and more fields. Summary of the invention

[0003] The object of the present invention is to provide a flame-retardant starch-based biomass composite material which is biodegradable, has excellent mechanical properties, good flame retardant properties and a simple preparation method, and a preparation method thereof.

[0004] The technical solution for achieving the purpose of the present invention is: a flame retardant starch-based biomass composite material, comprising starch, N-methylmorpholine-N-oxide, ammonium polyphosphate and pentaerythritol.

[0005] In the flame-retardant starch-based biomass composite material of the present invention, the mass ratio of starch: N-methylmorpholine-N-oxide: ammonium polyphosphate: pentaerythritol is (60-75): (20-30): (6-12): (2-5).

[0006] The flame-retardant starch-based biomass composite material of the present invention may also contain biomass fibers.

[0007] The flame-retardant starch-based biomass composite material of the present invention may also contain biodegradable synthetic polymers.

[0008] The method for preparing the flame-retardant starch-based biomass composite material of the present invention comprises the following steps in sequence:

[0009] Step 1, mixing part or all of the starch with N-methylmorpholine-N-oxide liquid having an N-methylmorpholine-N-oxide content of ≥75% and heating the mixture to prepare a thermoplastic starch material;

[0010] In the second step, the thermoplastic starch material is melt-mixed and extruded with ammonium polyphosphate, pentaerythritol, reinforcing material and biodegradable synthetic polymer by a screw extruder to form a flame-retardant starch-based biomass composite material.

[0011] In the second step of the method for preparing the flame-retardant starch-based biomass composite material of the present invention, the melting and mixing temperature is ≤140°C.

[0012] Compared with the prior art, the flame-retardant starch-based biomass composite material and the preparation method thereof of the present invention have the following significant advantages: (1) the N-methylmorpholine-N-oxide used in the present invention is environmentally friendly, and ammonium polyphosphate and pentaerythritol have good flame-retardant modification effects on starch-based biomass (composite) materials. The flame-retardant starch-based biomass composite material of the present invention is biodegradable, has excellent mechanical properties, and is low in price; (2) the preparation method of the flame-retardant starch-based biomass composite material of the present invention is simple and easy, can be processed by thermoplastic molding, and the molding method is simple and low in cost. DETAILED DESCRIPTION

[0013] The flame-retardant starch-based biomass composite material of the invention comprises starch, N-methylmorpholine-N-oxide, ammonium polyphosphate and pentaerythritol.

[0014] In the flame-retardant starch-based biomass composite material of the present invention, the starch may be one or more of wheat, corn, rice, sorghum, and tubers. The tubers may be sweet potatoes, cassava, potatoes, etc. The "one or more" mentioned herein refers to two or more than two.

[0015] In the flame-retardant starch-based biomass composite material of the present invention, the mass ratio of starch: N-methylmorpholine-N-oxide: ammonium polyphosphate: pentaerythritol is (60-75): (20-30): (6-12): (2-5).

[0016] The flame retardant starch-based biomass composite material of the present invention may also contain biomass fibers. Here, the biomass fibers are used as reinforcing materials. The biomass fibers may be cotton, wood powder, etc.

[0017] The flame retardant starch-based biomass composite material of the present invention may also contain biodegradable synthetic polymers, which may be polybutylene terephthalate-adipate, polybutylene succinate, polylactic acid, polycaprolactone, polyhydroxybutyric acid, and the like.

[0018] The method for preparing the flame-retardant starch-based biomass composite material of the present invention comprises the following steps in sequence:

[0019] Step 1, mixing part or all of the starch with N-methylmorpholine-N-oxide liquid having an N-methylmorpholine-N-oxide content of ≥75% and heating the mixture to prepare a thermoplastic starch material;

[0020] In the second step, the thermoplastic starch material is melt-mixed and extruded with ammonium polyphosphate, pentaerythritol, reinforcing material and biodegradable synthetic polymer by a screw extruder to form a flame-retardant starch-based biomass composite material.

[0021] In the second step of the method for preparing the flame-retardant starch-based biomass composite material of the present invention, the melting and mixing temperature is ≤140°C.

[0022] Example 1

[0023] 108 grams of corn starch and 72 grams of N-methylmorpholine-N-oxide hydrate containing 13.3wt% of water are heated to 105°C for mixing and dissolving to obtain a masterbatch, and then mixed with 90 grams of corn starch, 22.5 grams of ammonium polyphosphate, 7.5 grams of pentaerythritol, and 3 grams of antioxidant 1010 at 105°C; the mixed materials are melt-blended and extruded in a micro twin-screw extruder, and the four-stage working temperatures of the extruder are respectively set to 115°C, 120°C, 120°C, and 120°C, and then cooled by an air-cooled conveyor and pelletized by a micro pelletizer to obtain the flame-retardant starch-based biomass composite material of the present invention. The flame-retardant starch-based biomass composite material of the present invention has a tensile strength of 12.8MPa, a UL94 vertical burning test reaching V-0 level, and a limiting oxygen index of 25.3%.

[0024] Example 2

[0025] 108 grams of dried corn starch and 72 grams of N-methylmorpholine-N-oxide hydrate containing 13.3wt% of water are heated to 105°C for mixing and dissolving to obtain a masterbatch, and then mixed with 75 grams of corn starch, 33.75 grams of ammonium polyphosphate, 11.25 grams of pentaerythritol, and 3 grams of antioxidant 1010 at 105°C; the mixed materials are melt-blended and extruded in a micro twin-screw extruder, and the four-stage working temperatures of the extruder are respectively set to 115°C, 120°C, 120°C, and 120°C, and then cooled by an air-cooled conveyor and pelletized by a micro pelletizer to obtain the flame-retardant starch-based biomass composite material of the present invention. The flame-retardant starch-based biomass composite material of the present invention has a tensile strength of 10.6MPa, a UL94 vertical burning test reaching V-0 level, and a limiting oxygen index of 26%.

[0026] Example 3

[0027] 108 grams of dried corn starch and 72 grams of N-methylmorpholine-N-oxide hydrate containing 13.3wt% of water are heated to 105°C for mixing and dissolving to obtain a masterbatch, and then mixed with 66 grams of corn starch, 22.5 grams of ammonium polyphosphate, 7.5 grams of pentaerythritol, 24 grams of cotton yarn, and 3 grams of antioxidant 1010 at 105°C; the mixed materials are melt-blended and extruded in a micro twin-screw extruder, and the four-stage working temperatures of the extruder are respectively set to 115°C, 120°C, 120°C and 120°C, and then cooled by an air-cooled conveyor and pelletized by a micro pelletizer to obtain the flame-retardant starch-based biomass composite material of the present invention. The flame-retardant starch-based biomass composite material of the present invention has a tensile strength of 14.1MPa, a UL94 vertical burning test reaching V-1 level, and a limiting oxygen index of 25.3%.

[0028] Example 4

[0029] 108 grams of dried corn starch and 72 grams of N-methylmorpholine-N-oxide hydrate containing 13.3wt% of water are heated to 105°C for mixing and dissolving to obtain a masterbatch, and then mixed with 51 grams of corn starch, 33.75 grams of ammonium polyphosphate, 11.25 grams of pentaerythritol, 24 grams of cotton yarn, and 3 grams of antioxidant 1010 at 105°C. The mixed materials are melt blended and extruded in a micro twin-screw extruder, and the four-stage working temperatures of the extruder are set to 115°C, 120°C, 120°C and 120°C respectively, and then cooled by an air-cooled conveyor and pelletized by a micro pelletizer to obtain the flame-retardant starch-based biomass composite material of the present invention. The flame-retardant starch-based biomass composite material of the present invention has a tensile strength of 13.0MPa, a UL94 vertical burning test reaches V-0 level, and a limiting oxygen index of 25.5%.

[0030] Example 5

[0031] 108 grams of dried corn starch and 72 grams of N-methylmorpholine-N-oxide hydrate containing 13.3wt% of water are heated to 105°C for mixing and dissolving to obtain a masterbatch, and then mixed with 30 grams of corn starch, 33.75 grams of ammonium polyphosphate, 11.25 grams of pentaerythritol, 45 grams of cotton yarn, and 3 grams of antioxidant 1010 at 105°C; the mixed materials are melt-blended and extruded in a micro twin-screw extruder, and the four-stage working temperatures of the extruder are respectively set to 115°C, 120°C, 120°C and 120°C, and then cooled by an air-cooled conveyor and pelletized by a micro pelletizer to obtain the flame-retardant starch-based biomass composite material of the present invention. The flame-retardant starch-based biomass composite material of the present invention has a tensile strength of 20.4MPa, a UL94 vertical burning test reaching V-0 level, and a limiting oxygen index of 25.3%.

[0032] Example 6

[0033] 112 grams of pre-dried wheat starch and 48 grams of N-methylmorpholine-N-oxide hydrate with a water content of 13.3wt% are mixed and dissolved at 105°C, and then mixed with 240 grams of polybutylene terephthalate-adipate and 5 grams of antioxidant 1010; the mixed materials are melt-blended and extruded in a micro twin-screw extruder, and the four-stage working temperatures of the extruder are respectively set to 115°C, 120°C, 120°C and 120°C, and then cooled by an air-cooled conveyor and pelletized by a micro pelletizer to obtain the flame-retardant starch-based biomass composite material of the present invention. The flame-retardant starch-based biomass composite material of the present invention has a tensile strength of 5.26MPa, a UL94 vertical burning test reaching V-0 level, and a limiting oxygen index of 28.0%.

[0034] Comparative Example 1

[0035] 108 grams of corn starch and 72 grams of N-methylmorpholine-N-oxide hydrate containing 13.3wt% of water were heated to 105°C for mixing and dissolving to obtain a masterbatch, and then mixed with 120 grams of corn starch and 3 grams of antioxidant 1010 at 105°C; the mixed materials were melt blended and extruded in a micro twin-screw extruder, and the four-stage working temperatures of the extruder were set to 115°C, 120°C, 120°C and 120°C, respectively, and then cooled by an air-cooled conveyor and pelletized by a micro pelletizer to obtain a comparative starch-based biomass blend of the present invention. The tensile strength of the comparative starch-based biomass blend is 14.6MPa, and the UL94 vertical burning test shows that it is completely flammable and does not meet the flame retardant rating standard, and the limiting oxygen index is 20.5%.

Claims

1. A flame retardant starch-based biomass composite material, characterized in that: Includes starch, N-methylmorpholine-N-oxide, ammonium polyphosphate and pentaerythritol.

2. The flame-retardant starch-based biomass composite material according to claim 1, characterized in that: The mass ratio of starch: N-methylmorpholine-N-oxide: ammonium polyphosphate: pentaerythritol is 60-75: 20-30: 6-12: 2-5.

3. The flame-retardant starch-based biomass composite material according to claim 1 or 2, characterized in that: Also contains biomass fibers.

4. The flame-retardant starch-based biomass composite material according to any one of claims 1 to 3, characterized in that: Also contains biodegradable synthetic polymers.

5. The method for preparing a flame-retardant starch-based biomass composite material according to any one of claims 1 to 4, characterized in that: The following steps are included in sequence: Step 1, mixing part or all of the starch with N-methylmorpholine-N-oxide liquid having an N-methylmorpholine-N-oxide content of ≥75% and heating the mixture to prepare a thermoplastic starch material; In the second step, the thermoplastic starch material is melt-mixed and extruded with ammonium polyphosphate, pentaerythritol, reinforcing material and biodegradable synthetic polymer by a screw extruder to form a flame-retardant starch-based biomass composite material.

6. The method for preparing a flame-retardant starch-based biomass composite material according to claim 5, characterized in that: The melt mixing temperature in step 2 is ≤ 140°C.