CN102634073A - Starch/polypropylene degradable composite material and preparation method thereof - Google Patents

Abstract

The invention discloses a starch/polypropylene degradable composite material, which consists of 50% to 70% of starch by weight, 5% to 15% of vegetable oil plasticizer, 15% to 30% of polypropylene or modified Made of polypropylene and 5% to 30% compatibilizer raw materials, the compatibility of starch and polypropylene is improved by the compatibilizer, and the starch is plasticized by the vegetable oil plasticizer, and the plasticized starch has stable performance, making this product The toughness and impact resistance of the invented starch/polypropylene degradable composite material are greatly enhanced, and the performance is stable at the same time, which is suitable for the fields of plastic packaging materials, agricultural mulch films and disposable tableware. The invention also discloses a preparation method of the starch/polypropylene degradable composite material, which is simple in preparation, easy in implementation, easy in operation and control, low in preparation cost, easy in industrialized production, and has broad application prospects.

Description

A kind of starch/polypropylene degradable composite material and preparation method thereof

technical field

The invention relates to the field of plastic materials, in particular to a starch/polypropylene degradable composite material and a preparation method thereof.

Background technique

The plastic industry has developed rapidly, and its use has penetrated into various fields of the national economy, and its use is very extensive. China produces about 5 million tons of waste plastics every year, most of which are polypropylene (PP), polyethylene (PE) and polystyrene (PS) materials, which cannot be decomposed naturally. Therefore, if the disposable plastic packaging waste made of PP material, PE material and PS material and its corresponding agricultural film and disposable tableware are randomly discarded, they will be piled up on the land due to their non-degradability, causing serious damage. White pollution, and this potential pollution will also intensify with the increase of people's usage and the accumulation of time. At present, my country's white pollution is serious, which has attracted the general attention of relevant government departments and society. Relevant laws and regulations have been issued, especially Especially in the European and American markets, the use of non-degradable plastics is strictly restricted.

With the continuous improvement of people's awareness of environmental protection, biodegradable environmentally friendly materials will receive more and more attention, and related industrial chains and R & D investment have been formed. It is reported that in 2013, the demand for biodegradable materials in the United States will be There is a market space of 2.6 billion U.S. dollars. China's current demand for degradable plastics is also huge. According to the analysis of related industries, it is 3 million tons. ) and polybutylene succinate (PBS) are very expensive and have a certain gap in performance compared with traditional plastics such as PP and PE, resulting in low market recognition for their development in recent years, while starch-based plastics (mainly It is a composite degradable plastic obtained by filling traditional plastics such as PP, PE and PS with starch), because it is developed on the basis of blending with traditional plastic fillings, it not only has the performance of traditional plastics, but also has the price Inexpensive and biodegradable, it is developing rapidly and has been recognized by the industry and the market.

Although starch is a natural polymer compound that can be completely biodegraded, its further application is limited in this respect because of its obvious structural differences with plastics, resulting in poor compatibility between the two. At present, the methods to improve the compatibility of plastics and starch mainly include physical modification and chemical modification of starch, grafting modification of plastics and adding suitable compatibilizers. The introduction of compatibilizer is one of the most widely used and most effective methods at present. The most commonly used compatibilizers are ethylene-acrylic acid copolymer (EAA), ethylene-vinyl acetate copolymer (EVA), polypropylene/glycidyl methacrylate (PP/GMA) graft and starch/methacrylate Ester graft copolymers, etc. Chen Xianhong of Hunan University used glycidyl methacrylate (GMA) and GMA/starch grafts as compatibilizers for polypropylene/starch blends in the presence of initiators, and realized thermal plasticization of starch by twin-screw extrusion And the blending and compatibilization of starch and polypropylene, a biodegradable polypropylene/starch blend material with excellent performance was prepared (Functional Materials 2009 Fifth Issue (40) Volume). However, no toughening agent is added to the blended material, and the blended material is difficult to be plasticized and extruded in a twin-screw and will be very brittle.

In addition, while solving the compatibility between starch and polypropylene, it is also necessary to solve the defect that the toughness of the entire composite system is too poor. Since starch is a rigid particle, general literature and patent reports are plasticized and filled. The method used is to add Small molecular compounds such as polyols, polyamines, alcohol amines or monoglycerides are melt blended with starch for plasticization. Yu et al. used a mixture of urea and ethanolamine as a plasticizer for the preparation of thermoplastic starch, and performed melt blending and extrusion in a screw. It is found through experiments that after the compound use of 15wt% urea and 15wt% ethanolamine in the system, the plasticized starch has better thermal and mechanical properties than glycerol plasticized starch (Carbohydrate Polymers 64 (2006) 267-273). However, small molecules are used to plasticize starch, and the performance of the plasticized starch is unstable. Small molecules are easy to precipitate, resulting in the recrystallization of the plasticized starch, resulting in a decrease in product performance, and the plasticized starch with small molecules is not resistant to high temperatures, and the product is easy to turn yellow. The Chinese invention patent application with the publication number CN 101805463A discloses a starch-filled biodegradable polypropylene and its preparation method. The starch-filled biodegradable polypropylene consists of 30% to 70% by weight of starch, 5% to 15% plasticizer, 10% to 50% polypropylene, 0.5% to 1% dispersant, 5% to 8% toughening agent and 0.5% to 1% photodegradant, although the starch filling is biodegradable The mechanical properties of polypropylene are good, but the plasticizer used is a mixture of one or two of sorbitol and glycerin. Both sorbitol and glycerin are small molecule plasticizers, and the above-mentioned problems still exist.

Contents of the invention

The invention provides a starch/polypropylene degradable composite material. Under the improvement of a compatibilizer and a vegetable oil plasticizer, the starch and polypropylene have excellent mechanical properties and strong wrinkle resistance, and the vegetable oil plasticizer is not easy to separate out.

A starch/polypropylene degradable composite material is made of the following raw materials in percentage by weight:

Starch 50%～70%;

Vegetable oil plasticizer 5% to 15%;

Polypropylene or modified polypropylene 15% to 30%;

Compatibilizer 5% to 30%.

The present invention improves the compatibility of starch and polypropylene through a compatibilizer, plasticizes the starch through a vegetable oil plasticizer, and the performance of the plasticized starch is stable, and the four raw materials can interact, so that the starch/polypropylene of the present invention is degradable The composite material exhibits excellent mechanical properties under the premise of relatively high starch content.

As a preference, the starch/polypropylene degradable composite material is made of the following raw materials in percentage by weight:

Starch 50%～60%;

Vegetable oil plasticizer 8% to 12%;

Polypropylene or modified polypropylene 15% to 25%;

Compatibilizer 15% to 25%.

The starch is one or both of natural starch and modified starch. The natural starch is one or more of corn starch, tapioca starch, mung bean starch, sweet potato starch, sweet potato starch, potato starch, wheat starch, water chestnut starch and lotus root starch. The modified starch is one or both of maleic anhydride grafted modified starch, phosphate distarch, acetylated distarch phosphate, acetylated distarch adipate, hydroxypropyl distarch phosphate more than one species. The maleic anhydride grafted modified starch can be specifically selected from maleic anhydride grafted cornstarch. Starch can be biodegradable. Natural starch is a natural polymer compound that can be completely biodegradable. Considering the cost and degradability of starch/polypropylene degradable composite materials, natural starch is not only low in cost, but also has good degradability. Considering the mechanical properties of starch/polypropylene degradable composites, modified starch is more conducive to the improvement of mechanical properties of starch/polypropylene degradable composites while ensuring a certain degradation performance of the composites.

The present invention uses a macromolecular vegetable oil plasticizer to plasticize the starch, and the plasticized starch has stable properties, and the macromolecular vegetable oil plasticizer is not easy to separate out, which is beneficial to the improvement of the mechanical properties of the starch/polypropylene degradable composite material, especially the composite material. Toughness, and the starch plasticized by macromolecular vegetable oil plasticizer is resistant to high temperature, and the product is not easy to turn yellow. The vegetable oil plasticizer is one or more of soybean oil, peanut oil, coconut oil, palm oil, linseed oil, cottonseed oil, corn oil, sunflower oil, pine nut oil, tung oil, and castor oil. Further preferably, the vegetable oil plasticizer is soybean oil, and the weight percentage of soybean oil is 10%, and the use of soybean oil with a weight percentage of 10% can not only prepare a starch/polypropylene degradable composite Materials, and the cost of soybean oil is relatively low compared to other oils, which greatly reduces the production cost of starch/polypropylene degradable composite materials.

The polypropylene can be a commercially available product, and a commercially available general brand can be used. Modified polypropylene can also choose commercially available general grades. Specifically, maleic anhydride grafted polypropylene can be used. Polypropylene modified with maleic anhydride has better compatibility with starch, which improves the compatibility between polypropylene and starch. compatibility.

Due to the obvious difference in structure between starch and polypropylene, the compatibility between the two is not good. The present invention improves the compatibility of starch and polypropylene through a compatibilizer, and the compatibilizer is ethylene-acetic acid One or both of ethylene copolymer (EVA), ethylene-acrylic acid copolymer (EAA). Further preferably, the compatibilizer is an ethylene-vinyl acetate copolymer, which can very well improve the compatibility of starch and polypropylene.

The invention also provides a preparation method of the starch/polypropylene degradable composite material, which is simple in preparation, easy in implementation, easy in operation and control.

The preparation method of described starch/polypropylene degradable composite material comprises the following steps:

Mix starch, vegetable oil plasticizer, polypropylene and compatibilizer uniformly to obtain a mixed material; or mix starch, vegetable oil plasticizer, modified polypropylene and compatibilizer uniformly to obtain a mixed material; The mixed material is fed into a twin-screw extruder for melting and blending, and then drawn and pelletized to obtain a granular mixed resin; the granular mixed resin is dried to obtain a starch/polypropylene degradable composite material.

The screw length-to-diameter ratio of the twin-screw extruder is 35:1 to 45:1; the temperature of the melt blending is 160°C to 180°C, and the vegetable oil plasticizer plasticizes the starch, and the plasticized The performance of starch is stable, the vegetable oil plasticizer is not easy to precipitate, and the raw material can be melted and extruded at a relatively high temperature of 160°C to 180°C.

The starch/polypropylene degradable composite material of the present invention is suitable for fields such as plastic packaging materials, agricultural mulch films and disposable tableware, and the starch/polypropylene degradable composite material is used as a raw material to produce plastic packaging films and agricultural mulch films through existing processing technologies And disposable tableware.

Compared with prior art, the present invention has following advantage:

In the starch/polypropylene degradable composite material of the present invention, the starch content is relatively high, so that the starch/polypropylene degradable composite material of the present invention has better degradability. Polypropylene degradable composites still have good mechanical properties and high temperature resistance, while better degradability. Vegetable oil plasticizers can be decomposed by microorganisms under certain conditions and are biodegradable. Therefore, both the main raw material starch and the vegetable oil plasticizer in the starch/polypropylene degradable composite material of the present invention can be degraded, so that the starch/polypropylene degradable composite material of the present invention has better degradability.

The starch/polypropylene degradable composite material of the present invention improves the compatibility of starch and polypropylene through a compatibilizer, plasticizes the starch through a vegetable oil plasticizer, and the performance of the plasticized starch is stable, and the vegetable oil plasticizer is not easy to separate out, And the starch plasticized by the vegetable oil plasticizer is resistant to high temperature, so that the raw material can be melted and extruded at a relatively high temperature of 160°C to 180°C, and the product is not easy to turn yellow, which makes the starch/polypropylene degradable composite material of the present invention tough and impact resistant The performance is greatly enhanced, and the performance is stable at the same time. The four raw materials of the present invention can interact with each other, so that the starch/polypropylene degradable composite material of the present invention exhibits excellent mechanical properties and certain high temperature resistance under the premise of relatively high starch content.

The starch/polypropylene composite material of the present invention can not only be applicable to fields such as plastic packaging material, agricultural mulch film and disposable tableware, and the final part of the starch/polypropylene composite material of the present invention can be decomposed and absorbed by microorganisms in the soil, which is harmful to environmental pollution. Small, with good environmental benefits and social value.

The preparation method of the starch/polypropylene degradable composite material of the present invention has the advantages of simple preparation, easy implementation, easy operation and control, low preparation cost, excellent and stable product performance, easy industrial production, good economic benefits, and wide application prospect.

Detailed ways

The following examples further describe the invention, but the invention is not limited to these examples.

Preparation Example 1

With 60g of cornstarch (the weight percentage of moisture is 4.1%, Zhucheng Xingmao Corn Development Co., Ltd.), 2.6g of maleic anhydride (National Medicine Reagent), 100mL of N,N-dimethylacetamide (DMAc, Chinese medicine reagent) and 20mL toluene (Chinese medicine reagent) were added to a 250mL three-necked flask and stirred evenly, mechanically stirred at 130°C for 1h, and the upper solvent was removed at rest, then acetone was added to stir to wash away unreacted maleic anhydride, and the upper solvent was removed at rest, Add acetone again to remove the upper layer solvent, add acetone to remove the upper layer solvent for a total of 3 times, filter, then rinse with acetone repeatedly 3 times, put the obtained modified cornstarch in a vacuum drying oven at 80°C for 12 hours to obtain 60g Maize starch grafted with maleic anhydride.

Example 1

Weigh the following raw materials in parts by weight:

55 parts by weight of maleic anhydride grafted cornstarch prepared by Preparation Example 1, 10 parts by weight of soybean oil (Aladdin's reagent), maleic anhydride grafted polypropylene (general grade, Ningbo Nengzhiguang New Material Technology Co., Ltd., model is GPM200A) 10 parts by weight, ethylene-vinyl acetate copolymer (Korean Hanwha, model is 1317 type) 25 parts by weight.

Mix 55 parts by weight of cornstarch grafted with maleic anhydride, 10 parts by weight of soybean oil, 10 parts by weight of grafted polypropylene with maleic anhydride and 25 parts by weight of ethylene-vinyl acetate copolymer, and then add the mixed materials After melting and blending in a twin-screw extruder (the mixed materials pass through the melt blending sections at temperatures of 160°C, 170°C, 170°C, 170°C, 175°C, 170°C, 170°C, and 160°C) Stranding and cutting into pellets to obtain granular mixed resin; the granular mixed resin is dehydrated and dried to obtain a starch/polypropylene degradable composite material. The selected twin-screw extruder has a screw length-to-diameter ratio of 40:1.

Add the starch/polypropylene degradable composite material obtained above into an injection molding machine for injection molding to obtain a product sample. The temperature in the injection molding area is 200°C, and the temperature in the template area is 45°C.

Example 2

Weigh the following raw materials in parts by weight:

55 parts by weight of maleic anhydride grafted cornstarch prepared by Preparation Example 1, 10 parts by weight of soybean oil (Aladdin's reagent), maleic anhydride grafted polypropylene (general grade, Ningbo Nengzhiguang New Material Technology Co., Ltd., model is GPM200A) 20 parts by weight, 15 parts by weight of ethylene-vinyl acetate copolymer (Hanwha, Korea, type 1317).

After mixing 55 parts by weight of corn starch grafted with maleic anhydride, 10 parts by weight of soybean oil, 20 parts by weight of grafted polypropylene with maleic anhydride and 15 parts by weight of ethylene-vinyl acetate copolymer, the mixed materials were added After melting and blending in a twin-screw extruder (the mixed materials pass through the melt blending sections at temperatures of 160°C, 170°C, 175°C, 170°C, 170°C, 170°C, 170°C, and 160°C) Stranding and cutting into pellets to obtain granular mixed resin; the granular mixed resin is dehydrated and dried to obtain a starch/polypropylene degradable composite material. The selected twin-screw extruder has a screw length-to-diameter ratio of 40:1.

Add the starch/polypropylene degradable composite material obtained above into an injection molding machine for injection molding to obtain a product sample. The temperature in the injection molding area is 200°C, and the temperature in the template area is 45°C.

Example 3

Weigh the following raw materials in parts by weight:

55 parts by weight of maleic anhydride grafted cornstarch prepared by Preparation Example 1, 10 parts by weight of soybean oil (Aladdin's reagent), 20 parts by weight of polypropylene (ExxonMobil, model is 7684KN), ethylene-vinyl acetate copolymer (Korean Hanwha, model is 1317 type) 15 parts by weight.

After mixing 55 parts by weight of cornstarch grafted with maleic anhydride, 10 parts by weight of soybean oil, 20 parts by weight of polypropylene and 15 parts by weight of ethylene-vinyl acetate copolymer, the mixed material is then added to the twin-screw extruder Melt blending in the machine (the mixed materials pass through the melt blending sections at temperatures of 160°C, 170°C, 175°C, 180°C, 185°C, 175°C, 170°C, and 160°C in sequence) and then slivered and pelletized to obtain a granular mixed resin; the granular mixed resin is dehydrated and dried to obtain a starch/polypropylene degradable composite material. The selected twin-screw extruder has a screw length-to-diameter ratio of 40:1.

Add the starch/polypropylene degradable composite material obtained above into an injection molding machine for injection molding to obtain a product sample. The temperature in the injection molding area is 200°C, and the temperature in the template area is 45°C.

Example 4

Weigh the following raw materials in parts by weight:

60 parts by weight of maleic anhydride grafted cornstarch prepared by Preparation Example 1, 10 parts by weight of soybean oil (Aladdin's reagent), 15 parts by weight of polypropylene (ExxonMobil, model is 7684KN), ethylene-vinyl acetate copolymer (Korean Hanwha, model is 1317 type) 15 parts by weight.

After mixing 60 parts by weight of maleic anhydride grafted cornstarch, 10 parts by weight of soybean oil, 15 parts by weight of polypropylene and 15 parts by weight of ethylene-vinyl acetate copolymer, the mixed material is then added to the twin-screw extruder Melt blending in the machine (the mixed material passes through the melt blending sections with temperatures of 160°C, 170°C, 175°C, 170°C, 175°C, 170°C, 160°C, 160°C in sequence) and then strands, pelletized to obtain a granular mixed resin; the granular mixed resin is dehydrated and dried to obtain a starch/polypropylene degradable composite material. The selected twin-screw extruder has a screw length-to-diameter ratio of 40:1.

Add the starch/polypropylene degradable composite material obtained above into an injection molding machine for injection molding to obtain a product sample. The temperature in the injection molding area is 200°C, and the temperature in the template area is 45°C.

Example 5

Weigh the following raw materials in parts by weight:

60 parts by weight of maleic anhydride grafted cornstarch prepared by Preparation Example 1, 10 parts by weight of soybean oil (Aladdin's reagent), 20 parts by weight of polypropylene (ExxonMobil, model is 7684KN), ethylene-vinyl acetate copolymer (Korean Hanwha, model is 1317 type) 10 parts by weight.

After mixing 60 parts by weight of cornstarch grafted with maleic anhydride, 10 parts by weight of soybean oil, 20 parts by weight of polypropylene and 10 parts by weight of ethylene-vinyl acetate copolymer, the mixed material is then added to the twin-screw extruder Melt blending in the machine (the mixed material passes through the melt blending sections with temperatures of 160°C, 170°C, 175°C, 170°C, 175°C, 175°C, 160°C, 160°C in sequence) and then strands, pelletized to obtain a granular mixed resin; the granular mixed resin is dehydrated and dried to obtain a starch/polypropylene degradable composite material. The selected twin-screw extruder has a screw length-to-diameter ratio of 40:1.

Add the starch/polypropylene degradable composite material obtained above into an injection molding machine for injection molding to obtain a product sample. The temperature in the injection molding area is 200°C, and the temperature in the template area is 45°C.

Example 6

Weigh the following raw materials in parts by weight:

Distarch phosphate (Zhangjiakou Shenzhou Starch Technology Co., Ltd.) 60 parts by weight, soybean oil (Aladdin reagent) 10 parts by weight, polypropylene (Exxon Mobil, model is 7684KN) 15 parts by weight, ethylene-vinyl acetate copolymer Thing (Korean Hanwha, model is 1317 type) 15 parts by weight.

Mix 60 parts by weight of distarch phosphate, 10 parts by weight of soybean oil, 15 parts by weight of polypropylene and 15 parts by weight of ethylene-vinyl acetate copolymer, and then add the mixed material into a twin-screw extruder to melt Blending (the mixed materials pass through the melt blending zones at temperatures of 160°C, 170°C, 175°C, 170°C, 175°C, 175°C, 160°C, and 160°C in turn) and then draw strands, pelletize, and obtain granules The granular mixed resin is dehydrated and dried to obtain a starch/polypropylene degradable composite material. The selected twin-screw extruder has a screw length-to-diameter ratio of 40:1.

Add the starch/polypropylene degradable composite material obtained above into an injection molding machine for injection molding to obtain a product sample. The temperature in the injection molding area is 200°C, and the temperature in the template area is 45°C.

Example 7

Weigh the following raw materials in parts by weight:

Acetylated distarch adipate (Zhangjiakou Shenzhou Starch Technology Co., Ltd.) 60 parts by weight, soybean oil (Aladdin reagent) 10 parts by weight, polypropylene (Exxon Mobil, model is 7684KN) 15 parts by weight, ethylene- Vinyl acetate copolymer (Korea Hanwha, model is 1317 type) 15 parts by weight.

Mix 60 parts by weight of acetylated distarch adipate, 10 parts by weight of soybean oil, 15 parts by weight of polypropylene and 15 parts by weight of ethylene-vinyl acetate copolymer, and then add the mixed material to the twin-screw extruder. Melt blending in the discharge machine (the mixed materials pass through the melt blending sections with temperatures of 160°C, 170°C, 175°C, 170°C, 175°C, 175°C, 160°C, and 160°C in sequence) and then pull the strips, cut granules to obtain a granular mixed resin; the granular mixed resin is dehydrated and dried to obtain a starch/polypropylene degradable composite material. The selected twin-screw extruder has a screw length-to-diameter ratio of 40:1.

Add the starch/polypropylene degradable composite material obtained above into an injection molding machine for injection molding to obtain a product sample. The temperature in the injection molding area is 200°C, and the temperature in the template area is 45°C.

Example 8

Vegetable oil plasticizer adopts peanut oil among the embodiment 8, other is the same as embodiment 7.

Example 7 Compared with Example 8, the starch/polypropylene degradable composite material prepared by using soybean oil as a vegetable oil plasticizer has better performance, and from the perspective of marketization and industrialization, using soybean oil is also more efficient. Being cheap, starch/polypropylene biodegradable composites are cheaper to produce.

Example 9

Weigh the following raw materials in parts by weight:

Acetylated distarch adipate (Zhangjiakou Shenzhou Starch Technology Co., Ltd.) 58 parts by weight, soybean oil (Aladdin reagent) 12 parts by weight, polypropylene (Exxon Mobil, model is 7684KN) 15 parts by weight, ethylene- Vinyl acetate copolymer (Korea Hanwha, model is 1317 type) 15 parts by weight.

Mix 58 parts by weight of acetylated distarch adipate, 12 parts by weight of soybean oil, 15 parts by weight of polypropylene and 15 parts by weight of ethylene-vinyl acetate copolymer, and then add the mixed material to the twin-screw extruder. Melt blending in the discharge machine (the mixed materials pass through the melt blending sections with temperatures of 160°C, 170°C, 175°C, 170°C, 175°C, 175°C, 160°C, and 160°C in sequence) and then pull the strips, cut granules to obtain a granular mixed resin; the granular mixed resin is dehydrated and dried to obtain a starch/polypropylene degradable composite material. The selected twin-screw extruder has a screw length-to-diameter ratio of 40:1.

Add the starch/polypropylene degradable composite material obtained above into an injection molding machine for injection molding to obtain a product sample. The temperature in the injection molding area is 200°C, and the temperature in the template area is 45°C.

Example 10

Weigh the following raw materials in parts by weight:

Acetylated distarch adipate (Zhangjiakou Shenzhou Starch Technology Co., Ltd.) 58 parts by weight, soybean oil (Aladdin reagent) 8 parts by weight, polypropylene (Exxon Mobil, model is 7684KN) 19 parts by weight, ethylene- Vinyl acetate copolymer (Korea Hanwha, model is 1317 type) 15 parts by weight.

Mix 58 parts by weight of acetylated distarch adipate, 12 parts by weight of soybean oil, 15 parts by weight of polypropylene and 15 parts by weight of ethylene-vinyl acetate copolymer, and then add the mixed material to the twin-screw extruder. Melt blending in the discharge machine (the mixed materials pass through the melt blending sections with temperatures of 160°C, 170°C, 175°C, 170°C, 175°C, 175°C, 160°C, and 160°C in sequence) and then pull the strips, cut granules to obtain a granular mixed resin; the granular mixed resin is dehydrated and dried to obtain a starch/polypropylene degradable composite material. The selected twin-screw extruder has a screw length-to-diameter ratio of 40:1.

Add the starch/polypropylene degradable composite material obtained above into an injection molding machine for injection molding to obtain a product sample. The temperature in the injection molding area is 200°C, and the temperature in the template area is 45°C.

Embodiment 9, embodiment 10 compared with embodiment 7, main difference is the weight part of soybean oil, as seen when the weight percentage of soybean oil is 10%, the starch/polypropylene degradable composite material of preparation has better performance.

Example 11

Weigh the following raw materials in parts by weight:

Cornstarch (the weight percentage of moisture is 4.1%, Zhucheng Xingmao Corn Development Co., Ltd.) 50 parts by weight, soybean oil (Aladdin's reagent) 10 parts by weight, polypropylene (ExxonMobil, model is 7684KN) 20 parts by weight Parts, 20 parts by weight of ethylene-vinyl acetate copolymer (Korea Hanwha, model is 1317 type).

After mixing 50 parts by weight of cornstarch, 10 parts by weight of soybean oil, 20 parts by weight of polypropylene and 20 parts by weight of ethylene-vinyl acetate copolymer, the mixed material is then added to a twin-screw extruder for melt blending (The mixed material passes through the melt blending zones with temperatures of 165°C, 165°C, 170°C, 170°C, 170°C, 165°C, 160°C, and 160°C in turn) and then draws, pelletizes, and obtains a granular mixture Resin; the granular mixed resin is dehydrated and dried to obtain a starch/polypropylene degradable composite material. The selected twin-screw extruder has a screw length-to-diameter ratio of 40:1.

Add the starch/polypropylene degradable composite material obtained above into an injection molding machine for injection molding to obtain a product sample. The temperature in the injection molding area is 200°C, and the temperature in the template area is 45°C.

Example 12

Weigh the following raw materials in parts by weight:

Cornstarch (the weight percentage of moisture is 4.1%, Zhucheng Xingmao Corn Development Co., Ltd.) 55 parts by weight, soybean oil (Aladdin's reagent) 10 parts by weight, polypropylene 20 parts by weight (Exxon Mobil, model is 7684KN ), ethylene-vinyl acetate copolymer (Korean Hanwha, model is 1317 type) 15 parts by weight.

After mixing 55 parts by weight of cornstarch, 10 parts by weight of soybean oil, 20 parts by weight of polypropylene and 15 parts by weight of ethylene-vinyl acetate copolymer, the mixed material is then added to a twin-screw extruder for melt blending (The mixed material passes through the melt blending zones with temperatures of 165°C, 165°C, 170°C, 170°C, 170°C, 165°C, 160°C, and 160°C in turn) and then draws, pelletizes, and obtains a granular mixture Resin; the granular mixed resin is dehydrated and dried to obtain a starch/polypropylene degradable composite material. The selected twin-screw extruder has a screw length-to-diameter ratio of 40:1.

Add the starch/polypropylene degradable composite material obtained above into an injection molding machine for injection molding to obtain a product sample. The temperature in the injection molding area is 200°C, and the temperature in the template area is 45°C.

The starch/polypropylene degradable composite material prepared in Examples 1 to 10 was subjected to an impact performance test according to ASTM D256-2006 (notched impact test, pendulum 5.5J, average value of four groups of experiments), and the test results are shown in Table 1. Show. The starch/polypropylene degradable composite material prepared in Examples 11-12 is subjected to impact resistance test according to ASTM D 256-2006 (notch impact test, pendulum 5.5J, average value of four groups of experiments), according to GB1040-2006 Carry out the test of elongation at break and tensile strength (four groups of experiments take the average value), and its test results are shown in Table 2.

Table 1

Table 2

Example 11 12 Impact strength (KJ/m ² ) 16.5 14.3 Elongation at break (%) 120 90 Tensile strength (MPa) 11 14

Claims (10)

1. A starch/polypropylene degradable composite material, made of the following raw materials in percentage by weight: Starch 50%～70%; Vegetable oil plasticizer 5% to 15%; Polypropylene or modified polypropylene 15% to 30%; Compatibilizer 5% to 30%. 2. starch/polypropylene degradable composite material according to claim 1, is characterized in that, is made of the raw material of following percentage by weight: Starch 50%～60%; Vegetable oil plasticizer 8% to 12%; Polypropylene or modified polypropylene 15% to 25%; Compatibilizer 15% to 25%. 3. The starch/polypropylene degradable composite material according to claim 1 or 2, wherein said starch is one or both of native starch and modified starch. 4. starch/polypropylene degradable composite material according to claim 3, is characterized in that, described native starch is corn starch, tapioca starch, mung bean starch, sweet potato starch, sweet potato starch, potato starch, wheat starch, One or more of water chestnut starch and lotus root starch. 5. starch/polypropylene degradable composite material according to claim 3, is characterized in that, described modified starch is maleic anhydride graft modified starch, phosphate distarch, acetylated distarch phosphate, One or more of acetylated distarch adipate and hydroxypropyl distarch phosphate. 6. The starch/polypropylene degradable composite material according to claim 1 or 2, wherein said vegetable oil plasticizer is soybean oil, peanut oil, coconut oil, palm oil, linseed oil, cottonseed oil, corn One or more of oil, sunflower oil, pine nut oil, tung oil, castor oil. 7. The starch/polypropylene degradable composite material according to claim 1 or 2, wherein the vegetable oil plasticizer is soybean oil, and the weight percentage of soybean oil is 10%. 8. The starch/polypropylene degradable composite material according to claim 1 or 2, wherein the compatibilizer is one or both of ethylene-vinyl acetate copolymer and ethylene-acrylic acid copolymer kind. 9. The preparation method of the starch/polypropylene degradable composite material according to any one of claims 1 to 8, comprising the following steps: Mix starch, vegetable oil plasticizer, polypropylene and compatibilizer uniformly to obtain a mixed material; or mix starch, vegetable oil plasticizer, modified polypropylene and compatibilizer uniformly to obtain a mixed material; The mixed material is fed into a twin-screw extruder for melting and blending, and then drawn and pelletized to obtain a granular mixed resin; the granular mixed resin is dried to obtain a starch/polypropylene degradable composite material. 10. The preparation method of starch/polypropylene degradable composite material according to claim 9, characterized in that, the screw length-to-diameter ratio of the twin-screw extruder is 35 to 45: 1; The mixing temperature is 160°C to 180°C.