CN113248875A

CN113248875A - Fully-degradable shopping bag film and preparation method thereof

Info

Publication number: CN113248875A
Application number: CN202110335139.1A
Authority: CN
Inventors: 施晓旦; 甄晓宇; 金霞朝
Original assignee: Shanghai Changfa New Materials Co Ltd
Current assignee: Shanghai Changfa New Materials Co Ltd
Priority date: 2021-03-29
Filing date: 2021-03-29
Publication date: 2021-08-13

Abstract

The invention discloses a fully-degradable shopping bag film and a preparation method thereof, wherein the fully-degradable shopping bag film comprises the following components in parts by weight: 45-90 parts of biodegradable resin, 5-30 parts of hemicellulose, 5-25 parts of starch, 1-8 parts of plasticizer, 1-8 parts of phase solvent, 0.5-3 parts of cross-linking agent and 1-5 parts of dispersing agent. The preparation method comprises the following steps: uniformly mixing biodegradable resin, hemicellulose, starch, a plasticizer, a compatilizer, a cross-linking agent and a dispersing agent, carrying out melt extrusion through a double-screw extruder to obtain bio-based fully-degradable particles, and carrying out blow molding to prepare bags. According to the fully-degradable shopping bag film disclosed by the invention, the hemicellulose and the biodegradable resin are blended and modified, so that the prepared fully-degradable shopping bag film has good mechanical property, can meet the use requirement, greatly reduces the raw material cost, is green, environment-friendly and degradable, accords with the sustainable development view, and is easier to popularize.

Description

Fully-degradable shopping bag film and preparation method thereof

Technical Field

The invention relates to the field of composite materials, in particular to a fully-degradable shopping bag film and a preparation method thereof.

Background

At present, plastic shopping bags on the market are basically made of petroleum-based polyolefin serving as a raw material and are very difficult to degrade. Most of the shopping bags are used as garbage bags for the secondary purpose, except that part of the plastic shopping bags filled with garbage is incinerated, the rest of the plastic shopping bags are transported to a landfill to easily damage the ecological environment, and the cost is increased due to the fact that the petroleum resources are increasingly exhausted and the petroleum price is continuously increased. Therefore, a film bag product which can replace petroleum-based film bag products and relieve the pressure of resources is urgently sought.

The hemicellulose is the most abundant polysaccharide except the cellulose, accounts for one third of the renewable biological resources on the earth, is a renewable and easily degradable raw material with great potential for preparing the membrane, is filled into a membrane material product, and can improve the economic benefit of a paper making enterprise on the basis of protecting the environment. However, the potential value of hemicellulose has not been paid attention so far, for example, in chemical pulp, cellulose in agriculture and forestry biomass raw materials is mainly utilized, and hemicellulose accounting for about 20% -38% of the content of the cellulose is dissolved in waste liquid during cooking; even if these waste liquids are burned to obtain energy, a great waste of resources is caused due to the low calorific value of hemicellulose; the starch has the advantages of wide source, low price, safety and harmlessness, is a renewable resource, and degrades and destroys the mulching film by the action of amylase in soil.

The hemicellulose is added into the degradable resin to prepare the membrane, so that the membrane is environment-friendly and degradable, and the shortage of resources is relieved, so that the high-value utilization of the hemicellulose in the aspect of degrading the membrane material is realized. Therefore, there is a need in the art to develop a shopping bag which has a wide range of raw materials, low cost, efficient utilization of resources, easy processing and synthesis, and excellent mechanical properties.

Disclosure of Invention

The invention aims to provide a fully-degradable shopping bag film and a preparation method thereof, so as to solve the defects in the background art.

In order to solve the above problems, the present invention provides the following technical solutions: a fully-degradable shopping bag film comprises the following components in parts by weight: 45-90 parts of biodegradable resin, 5-30 parts of hemicellulose, 5-25 parts of starch, 1-8 parts of plasticizer, 1-8 parts of compatilizer, 1-5 parts of dispersant and 0.5-3 parts of cross-linking agent.

Preferably, the biodegradable resin comprises one or more of a combination of poly adipic acid, polybutylene terephthalate and polylactic acid.

Preferably, after the papermaking pulp is soaked in a sodium hydroxide solution for 0.5 to 3 hours, the papermaking pulp is subjected to solid-liquid separation treatment to obtain a soaking solution; collecting the maceration extract, pretreating with filter bag, and treating with ultrafiltration membrane to obtain concentrated solution and filtrate; recovering and reusing the filtrate for recovering alkali, collecting the concentrated solution, adding dilute sulfuric acid to separate out hemicellulose with the pH value of 3-7, and treating by using an ultrafiltration membrane to obtain concentrated solution and filtrate; adding pure water for dialysis, collecting concentrated solution, treating with ultrafiltration membrane at a temperature of at least 50 deg.C, and spray drying to obtain hemicellulose dry powder of 500-3000 meshes.

Preferably, the starch comprises one or more of edible corn starch, potato starch, wheat starch and tapioca starch.

Preferably, the non-toxic plasticizer comprises one or more of epoxidized soybean oil, tributyl citrate, sorbitol, or glycerin.

Preferably, the compatilizer comprises one or more of maleic anhydride graft material and acrylic acid.

Preferably, the crosslinking agent comprises one or more of DCP, BPO and tetrabutyl titanate.

Preferably, the dispersant comprises one or more of stearic acid, oleamide, erucamide and calcium stearate.

Preferably, it is characterized in that: the method comprises the following steps:

step one, placing the biodegradable resin, the hemicellulose, the starch, the plasticizer, the compatilizer, the crosslinking agent and the dispersing agent in a high mixing machine according to a preset proportion, and uniformly mixing to obtain a primary mixed material, wherein the rotating speed of the high mixing machine is 10-1000rpm, and the mixing time is 5-100 min;

step two, melting, extruding and granulating the primary mixed material through a bin of a co-rotating double-screw extruder to prepare the bio-based degradable master batch, wherein the extrusion temperature is 140-190 ℃;

and step three, performing film blowing molding on the bio-based degradable master batch through a film blowing machine, and making bags to obtain the fully degradable shopping bag film, wherein the film forming temperature is 1450-190 ℃.

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

1) in the invention, the preparation of the bio-based shopping bag has wide sources of main raw materials, simple process route and green and environment-friendly product, and the prepared shopping bag film product still has good mechanical property and impact resistance and can meet the use requirement.

2) In the invention, the main raw materials of hemicellulose and starch of the prepared shopping bag are wide in source and low in price; the use of the hemicellulose and the starch can reduce the use amount of plastic matrix materials, reduce the cost of shopping bag film products, realize the efficient utilization of resources and protect the environment, and is a good substitute for future petroleum-based plastics.

3) The semi-fiber and the starch are added into the thermoplastic biodegradable resin, so that the photo-oxidative degradation of the film in the natural environment is accelerated; the humic acid soil can be buried in soil, the degradation of the humic acid soil into carbon dioxide and water is accelerated by virtue of the action of soil enzymes, the value of humic acid soil is not influenced, and the humic acid soil plays a good role in relieving white pollution and protecting soil.

4) The plant fiber raw material after the hemicellulose is extracted from the papermaking pulp can still be used for pulping and papermaking, so that the sustainable utilization of biomass resources can be realized, and additional economic benefits are brought to papermaking enterprises.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the tables in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As a preferable scheme of the invention, the fully-degradable shopping bag film comprises the following components in parts by weight:

TABLE 1

As a better technical scheme of the invention, the fully-degradable shopping bag film comprises the following components in parts by weight:

biodegradable resin	55 to 80 portions of
		Hemicellulose	10-30 parts of
Starch	10-15 parts of
		Plasticizer	3-8 parts of
Compatilizer	2-7 parts of
		Crosslinking agent	0.5 to 2 portions of
Dispersing agent	2-4 parts of

TABLE 2

As a better technical scheme, the fully-degradable shopping bag film comprises the following components in parts by weight:

TABLE 3

In the present invention, the biodegradable resin may be poly adipic acid, polybutylene terephthalate (PBAT), or polylactic acid (PLA).

In the invention, the hemicellulose dry powder is obtained by carrying out pretreatment cleaning, membrane separation, filtration and purification on papermaking pulp; the particle size is generally selected from 500-3000 mesh, preferably 1000-2500 mesh, and more preferably 1500-2000 mesh.

In the invention, the starch can be at least one of food grade corn starch, wheat starch, potato starch and cassava starch; the particle size of the starch can be less than or equal to 3000 meshes, preferably 750-2500 meshes, and more preferably 1500-2000 meshes.

In the present invention, the auxiliary may be an auxiliary conventionally used in the art, and is preferably one or more of a compatibilizing agent, a crosslinking agent, a plasticizer and a dispersing agent, and more preferably "a compatibilizing agent, a crosslinking agent, a mixture of a plasticizer and a dispersing agent", "a crosslinking agent, a mixture of a plasticizer and a dispersing agent" or "a mixture of a compatibilizing agent, a plasticizer and a dispersing agent".

In the present invention, the plasticizer includes, but is not limited to, a mixture of one or more of epoxidized soybean oil, tributyl citrate, acetyl tri-n-butyl citrate, sorbitol, or glycerol;

in the present invention, the compatibilizer includes, but is not limited to, a mixture of one or more of maleic anhydride graft and acrylic acid.

The crosslinking agent in the present invention includes, but is not limited to, a mixture of one or more of DCP (dicumyl peroxide), BPO (benzoyl peroxide) and tetrabutyl titanate.

In the present invention, the dispersant includes, but is not limited to, one or more of stearic acid, oleic acid amide, erucamide, and calcium stearate.

The invention also provides a preparation method of the fully-degradable shopping bag film, which is formed by uniformly mixing the hemicellulose dry powder extracted from the papermaking slurry, the biodegradable resin, the starch, the plasticizer, the compatilizer, the cross-linking agent and the dispersing agent, extruding, granulating, and blowing the film for bag making.

The method specifically comprises the following steps:

step one, placing the biodegradable resin, the hemicellulose, the edible starch, the plasticizer, the compatilizer and the dispersant in a high-speed mixer according to a predetermined proportion and uniformly mixing to obtain a primary mixed material, wherein the rotation speed is 100-500rpm, and the mixing time is 5-50 min;

and step three, performing film blowing molding on the bio-based degradable master batch through a film blowing machine, and making bags to obtain the fully degradable shopping bag film, wherein the film forming temperature is 140-190 ℃.

Wherein, the mixing time in the first step is 5-100min, preferably 10-80min, and more preferably 20-50 min; the mixing speed is 10-1000rpm, preferably 300-800rpm, more preferably 400-700 rpm; the mixing temperature can be set to different temperatures according to the requirement, generally 10-150 ℃, preferably 40-120 ℃, and more preferably 50-80 ℃.

Wherein, the extrusion conditions in the second step are that the temperature from the first zone to the sixth zone is 50-190 ℃, the temperature of the machine head is 120-; preferably, the temperature of the first zone to the sixth zone is 80-180 ℃, the temperature of the machine head is 130-; more preferably, the temperature of the first zone to the sixth zone is 120-.

Wherein the temperature for making the bag by blowing the film in the third step is 190 ℃, preferably 140-180 ℃, and more preferably 160-175 ℃.

On the basis of the common knowledge in the field, the above preferred conditions can be combined randomly to obtain the preferred embodiments of the invention.

The reagents and starting materials used in the present invention are commercially available.

Example 1

A fully-degradable shopping bag film and a preparation method thereof are disclosed, and the fully-degradable shopping bag film comprises the following components in parts by weight:

the above formula is reacted according to the following steps:

1. putting the PBAT, the hemicellulose, the corn starch, the glycerol, the maleic anhydride grafting material PBAT and the stearic acid in the raw materials into a high-speed blender together, and mixing for 60min at the rotating speed of 100rpm to obtain a primary mixture;

2. placing the primary mixture in a double-screw extruder for extrusion granulation, wherein the temperature from the first zone to the sixth zone is 120 ℃, 135 ℃, 145 ℃, 165 ℃, 175 ℃, 175 ℃, the head temperature is 175 ℃, the screw rotation speed is 180rpm, and performing melt extrusion to obtain master batches;

3. and (3) putting the master batch into a film blowing machine, and carrying out blow molding bag making and molding at the temperature of 180 ℃ to prepare the degradable shopping bag.

Example 2

the above formula is reacted according to the following steps:

1. and (3) putting the PBAT, the PLA, the hemicellulose, the corn starch, the maleic anhydride grafted PBAT, the epoxidized soybean oil, the DCP and the stearic acid into a high-speed blender together, and mixing for 70min at the rotating speed of 150rpm to obtain a primary mixture.

2. And (3) putting the primary mixture into a double-screw extruder for extrusion granulation, wherein the temperature from the first zone to the sixth zone is 130 ℃, 145 ℃, 160 ℃, 180 ℃, 185 ℃, 180 ℃ at the head temperature, 180 ℃ at the screw rotation speed, and performing melt extrusion to obtain the master batch.

3. And (3) putting the master batch into a film blowing machine, and carrying out blow molding bag making and molding at 180 ℃ to prepare the degradable shopping bag film.

Example 3

the above formula is reacted according to the following steps:

1. and (3) putting the PBAT, the hemicellulose, the wheat starch, the maleic anhydride grafted PBAT, the glycerol and the calcium stearate together into a high-speed blender, and mixing for 40min at the rotating speed of 220rpm to obtain a primary mixture.

2. And (3) putting the primary mixture into a double-screw extruder for extrusion granulation, wherein the temperature from the first zone to the sixth zone is 110 ℃, 135 ℃, 150 ℃, 160 ℃, 160 ℃, 165 ℃, the head temperature is 165 ℃, and the screw rotation speed is 160rpm, and performing melt extrusion to obtain the master batch.

3. And (3) putting the master batch into a film blowing machine, and carrying out blow molding bag making and forming at 165 ℃ to prepare the degradable shopping bag film.

Example 4

the above formula is reacted according to the following steps:

1. and (3) putting the PBAT, the PLA, the hemicellulose, the corn starch, the acrylic acid, the sorbitol and the oleamide together into a high-speed blender, and mixing for 45min at the rotating speed of 230rpm to obtain a primary mixture.

2. And (3) putting the primary mixture into a double-screw extruder for extrusion granulation, wherein the temperature from the first zone to the sixth zone is 150 ℃, 160 ℃, 165 ℃, 175 ℃, 175 ℃, 175 ℃, 180 ℃ at the head temperature, and the screw rotation speed is 110rpm, and performing melt extrusion to obtain the master batch.

Example 5

the above formula is reacted according to the following steps:

1. and (3) putting the PBAT, the hemicellulose, the potato starch, the acrylic acid, the glycerol and the calcium stearate into a high-speed blender together, and mixing for 60min at the rotating speed of 230rpm to obtain a primary mixture.

2. And (3) putting the initial mixture into a double-screw extruder for extrusion granulation, wherein the temperature from the first zone to the sixth zone is 140 ℃, 155 ℃, 170 ℃, 185 ℃, 185 ℃, 185 ℃, the head temperature is 185 ℃, and the screw rotation speed is 130rpm, and performing melt extrusion to obtain the master batch.

3. And (3) putting the master batch into a film blowing machine, and carrying out blow molding bag making and molding at 185 ℃ to prepare the degradable shopping bag film.

Example 6

the above formula is reacted according to the following steps:

1. and (3) putting the PBAT, the PLA, the hemicellulose, the tapioca starch, the maleic anhydride grafted PBAT, the glycerol, the tetrabutyl titanate and the calcium stearate into a high-speed blender together, and mixing for 30min at the rotating speed of 330rpm to obtain a primary mixture.

2. And (3) putting the primary mixture into a double-screw extruder for extrusion granulation, wherein the temperature from the first zone to the sixth zone is 120 ℃, 130 ℃, 145 ℃, 170 ℃, 180 ℃, 180 ℃, the head temperature is 190 ℃, and the screw rotating speed is 360rpm, and performing melt extrusion to obtain the master batch.

3. And (3) putting the master batch into a film blowing machine, and carrying out blow molding bag making and molding at 190 ℃ to prepare the degradable shopping bag film.

Comparative example 1

the above formula is reacted according to the following steps:

1. and (3) putting the PBAT, the hemicellulose, the wheat starch, the maleic anhydride grafted PP, the glycerol and the stearic acid into a high-speed blender together, and mixing for 60min at the rotating speed of 300rpm to obtain a primary mixture.

2. And (3) putting the primary mixture into a double-screw extruder for extrusion granulation, wherein the temperature from the first zone to the sixth zone is 120 ℃, 135 ℃, 140 ℃, 150 ℃, 170 ℃, the head temperature is 170 ℃, and the screw rotation speed is 180rpm, and performing melt extrusion to obtain the master batch.

3. And (3) putting the master batch into a film blowing machine, and carrying out blow molding bag making and molding at 155 ℃ to prepare the degradable shopping bag film.

Comparative example 2

the above formula is reacted according to the following steps:

1. and (3) putting the PBAT, the hemicellulose, the sorbitol, the maleic anhydride grafted PBAT and the erucamide into a high-speed blender together, and mixing for 40min at the rotating speed of 380rpm to obtain a primary mixture.

2. And (3) putting the initial mixture into a double-screw extruder for extrusion granulation, wherein the temperature from the first zone to the sixth zone is 150 ℃, 160 ℃, 165 ℃, 175 ℃, 185 ℃, 185 ℃, the head temperature is 185 ℃, and the screw rotation speed is 250rpm, and the master batch is prepared by melt extrusion.

According to the method in the national standard GB/T1040.2-2006, the formula particles in the examples 1-6 and the comparative examples 1-2 are made into a dumbbell-type sample strip to be tested, the length of the sample strip to be tested is 150mm, the width of a narrow part is 10mm, and the gauge length is 75 mm. The tensile strength and elongation at break of the above examples and comparative examples were measured by a universal electronic tensile tester (model KY 8000C) according to the national standard GB/T1040.1-2006. The tensile strength is greater than 12MPa and the elongation at break is greater than 400%. The dart drop impact strength performance of the double-layer plastic after the blown film molding prepared in the above examples and comparative examples is tested according to the national standard GB/T1348-2008 'determination of Plastic Izod impact Strength', and the test standard of the dart drop impact strength is more than 150 g. Specific data are shown in table 1.

TABLE 4

The data results in Table 4 show that the tensile property and impact property data of the modified bio-based degradable shopping bag film are superior to those of comparative examples 1 and 2 in mechanical property, and can meet the use requirements.

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. A fully-degradable shopping bag film is characterized by comprising the following components in parts by weight: 45-90 parts of biodegradable resin, 5-30 parts of hemicellulose, 5-25 parts of starch, 1-8 parts of plasticizer, 1-8 parts of compatilizer, 1-5 parts of dispersant and 0.5-3 parts of cross-linking agent.

2. The fully degradable shopping bag film as claimed in claim 1, wherein: the biodegradable resin comprises one or more of a composition of poly adipic acid, polybutylene terephthalate and polylactic acid.

3. The fully degradable shopping bag film as claimed in claim 1, wherein: soaking the papermaking pulp in a sodium hydroxide solution for 0.5-3h, and then carrying out solid-liquid separation treatment to obtain a soaking solution; collecting the maceration extract, pretreating with filter bag, and treating with ultrafiltration membrane to obtain concentrated solution and filtrate; recovering and reusing the filtrate for recovering alkali, collecting the concentrated solution, adding dilute sulfuric acid to separate out hemicellulose with the pH value of 3-7, and treating by using an ultrafiltration membrane to obtain concentrated solution and filtrate; adding pure water for dialysis, collecting concentrated solution, treating with ultrafiltration membrane at a temperature of at least 50 deg.C, and spray drying to obtain hemicellulose dry powder of 500-3000 meshes.

4. The fully degradable shopping bag film as claimed in claim 1, wherein: the starch comprises one or more of edible corn starch, potato starch, wheat starch and cassava starch.

5. The fully degradable shopping bag film as claimed in claim 1, wherein: the non-toxic plasticizer comprises one or more of epoxidized soybean oil, tributyl citrate, sorbitol or glycerol.

6. The fully degradable shopping bag film as claimed in claim 1, wherein: the compatilizer comprises one or more of maleic anhydride graft and acrylic acid.

7. The fully degradable shopping bag film as claimed in claim 1, wherein: the cross-linking agent comprises one or more of DCP, BPO and tetrabutyl titanate.

8. The fully degradable shopping bag film as claimed in claim 1, wherein: the dispersant comprises one or more of stearic acid, oleamide, erucamide and calcium stearate.

9. A method of making a fully degradable shopping bag film according to any one of claims 1 to 8, wherein: the method comprises the following steps: