CN110540741A - Degradable composite material and preparation method and application thereof - Google Patents

Abstract

the invention provides a degradable composite material, a preparation method and application thereof. The degradable composite material provided by the invention has excellent mechanical strength and toughness, can eliminate the influence of peculiar smell, poor granulation performance and the like caused by lignin, hemicellulose and the like, and can effectively solve the brittleness defect of resin.

Description

Degradable composite material and preparation method and application thereof

Technical Field

The invention belongs to the technical field of biodegradable materials, and relates to a degradable composite material and a preparation method and application thereof.

Background

In the modern society, plastic packaging products which are difficult or can not be degraded are used and discarded in a large quantity, and the environment is seriously polluted. In recent years, white pollution caused by difficult degradation of waste plastics has been increasing, which has attracted extensive attention all over the world, and countries in the world have continued to make relevant regulations restricting or prohibiting the use of non-degradable plastic packages. On the other hand, since petroleum, which is a raw material for manufacturing conventional plastics, is a non-renewable resource and is inevitably exhausted with the use of a large amount of human beings, the development of degradable environment-friendly plastic materials using renewable resources as raw materials is urgent. In order to eliminate the social harm brought by the traditional plastic package, measures are taken to popularize a new packaging technology, and the research and development of degradable packaging materials become the technical problem which needs to be solved urgently at present.

Due to the high price of degradable resin (such as polylactic acid, PBAT and the like), wood flour is generally required to be added in the process of preparing degradable plastic, the production cost is reduced, and meanwhile, the physical properties of the plastic are improved.

CN103724958A discloses a high-toughness polylactic acid composite material and a preparation method thereof, wherein the composite material is composed of 58-98.9 parts by weight of polylactic resin, 0.5-20 parts by weight of butadiene/butyl acrylate block copolymer, 0.5-20 parts by weight of wood flour and 0.1-2 parts by weight of chain extender. CN107118393A discloses a preparation method of a modified cellulose/polylactic acid composite material, which comprises the steps of hydrolyzing hemicellulose with corn straws by acid, treating the hemicellulose by alkali-soluble lignin to prepare a cellulose precursor, crushing and dispersing the cellulose precursor to prepare fibrillated cellulose, impregnating the fibrillated cellulose by a flame retardant, carrying out low-temperature oxidation treatment to obtain dehydroxylcellulose, scattering the dehydroxylcellulose, carbonizing the dehydroxylcellulose at low temperature to prepare carbon fibers, oxidizing the fibrillated fibers by sodium hypochlorite to prepare carboxylated cellulose, esterifying the carboxylated cellulose with polyethylene glycol to prepare esterified cellulose, adding the dehydroxylcellulose, the carbonized cellulose and the esterified cellulose into an internal mixer, homogenizing and mixing the mixture with polylactic acid, dispersing the mixture by an open mill to prepare the modified cellulose/polylactic acid composite material, wherein the performance of the finally obtained composite material is excellent, but the preparation method is too complex. CN103541022A discloses a porous corn cob fiber and a preparation method thereof, wherein the surface of the porous corn cob fiber is provided with pores, and the patent also discloses that the porous corn cob fiber can be used as a filter material or a carrier, but does not disclose other applications.

Therefore, it is necessary to develop a new degradable composite material with superior strength and toughness to meet the application requirements and to develop a new application of the porous corncob fiber.

Disclosure of Invention

The invention aims to provide a degradable composite material and a preparation method and application thereof. The degradable composite material provided by the invention has excellent mechanical strength and toughness, can eliminate the influence of peculiar smell, poor granulation performance and the like caused by lignin, hemicellulose and the like, and can effectively solve the brittleness defect of resin.

In order to achieve the purpose, the invention adopts the following technical scheme:

In a first aspect, the present invention provides a degradable composite material comprising a degradable resin and porous corn cob fibers, and being free of a crosslinking agent.

The porous corncob fiber provided by the invention has the main component of cellulose, contains more hydroxyl groups, and the surface of the fiber is provided with round, oval and other irregularly-shaped pores, so that the specific surface area of the corncob fiber can be greatly improved, the contact area of the hydroxyl groups on the surface of the fiber and the surface groups of the degradable resin is further increased, and the reaction activity and compatibility of the corncob fiber and the degradable resin are improved, therefore, the degradable composite material provided by the invention has higher mechanical strength, toughness and other properties on the premise of not containing a cross-linking agent.

In the present invention, the porous corn cob fiber is contained in an amount of 10 to 25 wt%, for example, 12 wt%, 15 wt%, 18 wt%, 20 wt%, 22 wt%, etc., and more preferably 10 to 15 wt%, based on 100% by mass of the total degradable composite material.

if the content of the porous corncob fibers is too high, the dispersion is not uniform, the composite material is not sufficiently melted, the rheological property is poor, and the granulation is difficult or impossible.

Preferably, the porous corn cob fibers have a diameter of 0.1-150 μm, such as 1 μm, 5 μm, 10 μm, 20 μm, 50 μm, 80 μm, 100 μm, 120 μm, 140 μm, etc., and a length of 1-1000 μm, such as 10 μm, 50 μm, 100 μm, 200 μm, 500 μm, 800 μm, etc.

The diameters and lengths described in the examples of the present invention are average diameters and average lengths.

Preferably, in the porous corncob fiber, the content of hemicellulose is 10 wt% or less, such as 9 wt%, 8 wt%, 6 wt%, 4 wt%, 3 wt%, 2 wt%, 1 wt%, etc., and the content of lignin is 10 wt% or less, such as 9 wt%, 8 wt%, 6 wt%, 4 wt%, 3 wt%, 2 wt%, 1 wt%, etc.

The porous corncob fiber provided by the invention has extremely low content of hemicellulose and lignin part, can effectively eliminate the influence of peculiar smell, poor granulation performance and the like caused by components such as lignin, hemicellulose and the like, and can effectively solve the brittleness defect of degradable resin under the condition of not adding other reinforcing and toughening materials.

Preferably, the degradable resin comprises any one of or a combination of at least two of polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS) or polylactic acid (PLA).

in the invention, the degradable composite material also comprises an auxiliary agent.

Preferably, the auxiliary agent is selected from any one or a combination of at least two of an antioxidant, a whitening agent, a heat stabilizer or an antistatic agent.

in the present invention, the auxiliary may be selected as needed, or the auxiliary may not be added.

Preferably, the mass percentage of the auxiliary agent is 10-15 wt%, such as 11 wt%, 12 wt%, 13 wt%, 14 wt%, etc., based on 100% of the total mass of the degradable composite material.

as a preferable technical scheme, the degradable composite material comprises 10-25 wt% of porous corncob fiber, 60-80 wt% of degradable material and 10-15 wt% of auxiliary agent, wherein the total mass of the degradable composite material is 100%.

The 10-25 wt% can be 12 wt%, 15 wt%, 18 wt%, 20 wt%, 22 wt%, etc.

The 60-80 wt% can be 62 wt%, 65 wt%, 68 wt%, 70 wt%, 72 wt%, 75 wt%, 78 wt%, etc.

The 10-15 wt% may be 11 wt%, 12 wt%, 13 wt%, 14 wt%, etc.

In a second aspect, the present invention provides a method for preparing the degradable composite material according to the first aspect, wherein the preparation method comprises the following steps:

and mixing, extruding and granulating the porous corncob fibers, the degradable resin, the optional cross-linking agent and the optional auxiliary agent to obtain the degradable composite material.

preferably, the temperature of the mixing is 70-80 ℃, such as 72 ℃, 74 ℃, 76 ℃, 78 ℃ and the like.

Preferably, the stirring speed of the mixing is 1000-1500r/min, such as 1100r/min, 1200r/min, 1300r/min, 1400r/min, etc.

Preferably, the extrusion is carried out in a twin screw extruder.

Preferably, the temperature of the extrusion is 190-.

Preferably, the granulation is followed by drying.

Preferably, the drying is at a temperature of 70-80 deg.C, such as 72 deg.C, 74 deg.C, 76 deg.C, 78 deg.C, etc., for a period of 4-5h, such as 4.2h, 4.5h, 4.8h, etc.

in the invention, the preparation method of the porous corncob fiber comprises the following steps: and (3) carrying out acid treatment on the corncob raw material to obtain acid-treated slurry, and then purifying to obtain the porous corncob fiber.

Preferably, the acid-treated acid has a mass of 2-50%, such as 5%, 10%, 20%, 30%, 40%, etc., of the mass of the corncob, a treatment time of 1-10h, such as 2h, 4h, 6h, 8h, 9h, etc., and a treatment temperature of 90-170 ℃, such as 100 ℃, 120 ℃, 140 ℃, 160 ℃, etc.

Preferably, the alkaline treatment is performed before the purification to obtain an alkaline treated slurry.

preferably, the alkali treatment is performed at 5-100%, such as 10%, 20%, 40%, 60%, 80%, 90%, etc., based on the mass of the corn cob, the treatment time after the alkali treatment is 1-10h, such as 2h, 4h, 6h, 8h, 9h, etc., and the treatment temperature is 70-150 ℃, such as 80 ℃, 100 ℃, 120 ℃, 140 ℃, etc.

Preferably, the purification is followed by pulverization to 300-1000 mesh, such as 400 mesh, 500 mesh, 600 mesh, 700 mesh, 800 mesh, 900 mesh, etc., to obtain the porous corn cob fiber.

in a third aspect, the invention provides an application of the degradable composite material according to the first aspect as a biodegradable composite master batch.

In a fourth aspect, the present invention provides the use of a degradable composite according to the first aspect for the preparation of a cutlery item or a film item.

The degradable composite material provided by the invention can be used for producing tableware such as dinner plates, cutlery, disposable straws and the like after injection molding, and can be used for producing film products such as shopping bags, garbage bags and the like after a film blowing process.

Compared with the prior art, the invention has the following beneficial effects:

(1) the porous corncob fiber provided by the invention has round, oval and other irregular small holes on the surface, the specific surface area of the corncob fiber can be greatly improved, and the relative content of hydroxyl on the surface of the fiber is improved, so that the reactivity and compatibility of the corncob fiber and the degradable resin are improved, and the degradable composite material provided by the invention has higher mechanical strength, toughness and other properties on the premise of not containing a cross-linking agent;

(2) The porous corncob fiber provided by the invention has extremely low content of hemicellulose and lignin part, can effectively eliminate the influence of peculiar smell, poor granulation performance and the like caused by components such as lignin, hemicellulose and the like, and can effectively solve the brittleness defect of degradable resin under the condition of not adding other reinforcing and toughening materials;

(3) The degradable composite material provided by the invention has excellent mechanical properties, wherein when the degradable resin is polylactic acid, the tensile strength is more than 35MPa, and the elongation at break is more than 30%; when the mass percentage of the porous corncob fiber is 10-15 wt%, the tensile strength is over 53MPa, and the elongation at break is over 49%. In the case of other degradable resins, the tensile strength is 32MPa or more and the elongation at break is 60% or more.

Drawings

FIG. 1 is a scanning electron micrograph of a porous corn cob fiber provided in example 1 of the present invention.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

Example 1

A degradable composite material is composed of 10 parts of porous corncob fibers, 80 parts of polylactic acid, 5 parts of a heat stabilizer and 5 parts of a whitening agent.

Wherein the average diameter of the porous corncob fiber is 25 μm, the average length is 150 μm, the hemicellulose content is 2%, and the lignin content is 1.5%; the molecular weight of the polylactic acid is 3.3 (the mark is 3052D); the heat stabilizer is calcium stearate, and the whitening agent is titanium dioxide.

The preparation method comprises the following steps:

mixing the components in a high-speed mixer with the rotating speed of 1000r/min, controlling the mixing temperature at 75 ℃, mixing for 30min, then adding the mixture into a double-screw extruder, granulating at 190 ℃, and drying at 70 ℃ for 4h to obtain the degradable composite material.

Examples 2 to 5

The difference from the example 1 is that the weight percentage of the porous corncob fiber is 15 wt% (example 2), 25 wt% (example 3), 5 wt% (example 4), 30 wt% (example 5) by adjusting the addition amount of the porous corncob fiber and the polylactic acid based on 100 parts by weight of the degradable composite material.

Examples 6 to 8

The difference from example 1 is that the polylactic acid was replaced by poly (butylene adipate terephthalate) (PBAT, model 801T, example 6), poly (butylene succinate) (PBS, injection molding grade, ansqing and xinghe chemical limited liability company, example 7), 21 parts of polylactic acid was replaced by poly (butylene adipate terephthalate) (example 8).

Example 9

a degradable composite material is composed of 25 parts of porous corncob fibers and 75 parts of polylactic acid.

Wherein the average diameter of the porous corncob fiber is 75 μm, the average length is 500 μm, the hemicellulose content is 2%, and the lignin content is 1.5%; the polylactic acid had a molecular weight relative viscosity of 3.3 (No. 3052D).

The preparation method comprises the following steps:

the components are mixed in a high-speed mixer with the rotating speed of 1500r/min, the mixing temperature is controlled at 70 ℃, the mixing is carried out for 30min, then the mixture is added into a double-screw extruder to be granulated at 200 ℃, and then the mixture is dried for 5h at the temperature of 80 ℃, so as to obtain the degradable composite material.

Example 10

A degradable composite material is composed of 25 parts of porous corncob fibers, 65 parts of polylactic acid, 5 parts of an antistatic agent, 5 parts of an antioxidant and 5 parts of a heat stabilizer.

Wherein the average diameter of the porous corncob fiber is 140 μm, the average length is 900 μm, the hemicellulose content is 2%, and the lignin content is 1.5%; the molecular weight relative viscosity of the polylactic acid is 3.3 (the mark is 3052D); the antioxidant is polyphenol antioxidant 1010; the heat stabilizer is calcium stearate.

The preparation method comprises the following steps:

Mixing the components in a high-speed mixer with the rotation speed of 1200r/min, controlling the mixing temperature at 80 ℃, mixing for 30min, then adding the mixture into a double-screw extruder, granulating at 190 ℃, and drying at 75 ℃ for 4.5h to obtain the degradable composite material.

comparative examples 1 to 3

The difference from example 1 is that the porous corncob cellulose is replaced by corncob meal (comparative example 1), peanut hull meal (comparative example 2), poplar meal (comparative example 3).

Comparative example 4

The difference from comparative example 1 is that 10 parts of a crosslinking agent (5 parts each of maleic anhydride and sorbitol) was added by adjusting the addition amount of polylactic acid, keeping the total weight of the degradable composite material at 100 parts.

Performance testing

The degradable composite materials provided in examples 1 to 10 and comparative examples 1 to 4 were subjected to a performance test by the following method:

(1) Microscopic morphology: the porous corncob fibers in example 1 were subjected to microscopic morphology characterization;

FIG. 1 is a scanning electron micrograph of the porous corn cob fibers according to example 1, which shows that the porous corn cob fibers used in the present invention have a porous surface, a pore diameter of 0.1-5 μm, and an interpore distance of 0.1-100. mu.m.

(2) Mechanical properties: injecting a standard test sample strip in an injection molding machine, and testing according to a method specified by the national standard GB/1040.2-2006;

(3) Apparent morphology: the appearance and the appearance of the tea are directly observed by naked eyes, and whether the tea has peculiar smell or not is determined.

The test results are shown in table 1:

TABLE 1

Sample (I)	appearance of the product	Tensile strength/MPa	Elongation at break/%
				Example 1	Smooth surface and no peculiar smell	53.7	49
Example 2	Smooth surface and no peculiar smell	61.4	53
				Example 3	Smooth surface and no peculiar smell	47.3	41
example 4	Smooth surface and no peculiar smell	37.7	34
				Example 5	has small pores on the surface and peculiar smell	35.6	30
Example 6	smooth surface and no peculiar smell	32.2	70
				Example 7	Smooth surface and no peculiar smell	34.2	65
Example 8	Smooth surface and no peculiar smell	38.6	60
				Example 9	Smooth surface and no peculiar smell	48.0	42
Example 10	Smooth surface and no peculiar smell	48.4	43
				Comparative example 1	Large amount of pores on the surface and large peculiar smell	23.5	23
Comparative example 2	large amount of pores on the surface and large peculiar smell	23.0	27
				Comparative example 3	Large amount of pores on the surface and large peculiar smell	23.7	24
Comparative example 4	Has a large number of pores on the surface and has peculiar smell	27.5	30

According to the embodiment and the performance test, the degradable composite material provided by the invention has higher mechanical strength and toughness; when the degradable resin is polylactic acid, the tensile strength is more than 35MPa, and the elongation at break is more than 30%; when the mass percentage of the porous corncob fiber is 10-15 wt%, the tensile strength is over 53MPa, and the elongation at break is over 49%. In the case of other degradable resins, the tensile strength is 32MPa or more and the elongation at break is 60% or more.

as can be seen from the comparison between example 1 and examples 2 to 5, in the present invention, the porous corn cob fibers have better mechanical strength at 10 to 15 wt% than the porous corn cob fibers at a mass% other than 10 to 25 wt%; as is clear from comparison between example 1 and examples 6 to 8, the degradable resin of the present invention is more effective when it is polylactic acid.

As can be seen from the comparison between example 1 and comparative examples 1-3, the porous corncob fiber provided by the present invention can provide superior mechanical properties to the final degradable composite material of the present invention compared to other fiber powders. As can be seen from the comparison of example 1 and comparative example 4, the present invention has better mechanical properties without adding a crosslinking agent.

The applicant states that the present invention is illustrated by the above examples to the degradable composite material of the present invention and the preparation method and application thereof, but the present invention is not limited to the above process steps, i.e. it does not mean that the present invention must rely on the above process steps to be carried out. It will be apparent to those skilled in the art that any modification of the present invention, equivalent substitutions of selected materials and additions of auxiliary components, selection of specific modes and the like, which are within the scope and disclosure of the present invention, are contemplated by the present invention.

Claims (10)

1. A degradable composite material, wherein the degradable composite material comprises degradable resin and porous corncob fiber, and does not contain a crosslinking agent.

2. The degradable composite material of claim 1, wherein the porous corncob fiber is present in an amount of 10 to 25 wt%, more preferably 10 to 15 wt%, based on 100% of the total mass of the degradable composite material.

3. The degradable composite material of claim 1 or 2, wherein the porous corncob fibers have a diameter of 0.1 to 150 μ ι η and a length of 1 to 1000 μ ι η;

Preferably, in the porous corncob fiber, the content of hemicellulose is less than 10 wt%, and the content of lignin is less than 10 wt%;

Preferably, the degradable resin comprises any one of or a combination of at least two of polybutylene adipate/terephthalate, polybutylene succinate or polylactic acid.

4. The degradable composite of any one of claims 1 to 3, further comprising an auxiliary agent in the degradable composite;

Preferably, the auxiliary agent is selected from any one or a combination of at least two of an antioxidant, a whitening agent, a heat stabilizer or an antistatic agent;

Preferably, the cross-linking agent is selected from any one of maleic anhydride, a silane coupling agent, a citrate, sorbitol or a glyceride or a combination of at least two thereof.

5. The degradable composite material of claim 4, wherein the mass percentage of the auxiliary agent is 10-15 wt% based on 100% of the total mass of the degradable composite material.

6. The degradable composite of any of claims 1 to 5, wherein the degradable composite comprises 10 to 25 wt% porous corncob fibers, 60 to 80 wt% degradable resin and 10 to 15 wt% auxiliary agent, based on 100% total mass of the degradable composite.

7. Method for the preparation of a degradable composite according to any of the claims 1 to 6, characterized in that it comprises the following steps:

and mixing, extruding and granulating the porous corncob fibers, the degradable resin and the optional auxiliary agent to obtain the degradable composite material.

8. The method of claim 7, wherein the temperature of the mixing is 70-80 ℃;

Preferably, the stirring speed of the mixing is 1000-;

Preferably, the extrusion is carried out in a twin screw extruder;

Preferably, the temperature of the extrusion is 190-200 ℃;

Preferably, drying is carried out after granulation;

Preferably, the drying temperature is 70-80 ℃ and the drying time is 4-5 h.

9. Use of the degradable composite material according to any one of claims 1-6 as a biodegradable composite masterbatch.

10. Use of the degradable composite according to any one of claims 1 to 6 for the preparation of a cutlery item or a film item.