1. The PGA modified blown film material comprises the following raw materials in parts by weight:

70-80 parts of polyglycolic acid, 5-10 parts of a compatilizer, 5-8 parts of polycaprolactone, 5-8 parts of a plasticizer and 1-10 parts of a opener;

the opening agent is selected from a mixture of amorphous white carbon black and erucamide;

the compatilizer is a mixture of ADR resin and ethylene acrylic acid copolymer;

the plasticizer is industrial castor oil.

2. The PGA modified blown film material according to claim 1, wherein the polyglycolic acid has a weight average molecular weight of 30 ten thousand g/mol or more, a melting point of 200 to 220 ℃, a glass transition temperature of 45 to 55 ℃ and a specific gravity of 1.2 to 1.3g/cm³。

3. The PGA modified blown film material of claim 1, wherein the mass ratio of the amorphous silica to the erucamide is 1.5-2.5: 1.

4. The PGA modified blown film material according to claim 1, wherein the mass ratio of the ADR resin to the ethylene acrylic acid copolymer is 2.5 to 3.5: 1.

5. The PGA modified blown film material of claim 1, wherein the industrial castor oil comprises 80-87 wt% of ricinoleic acid, 7-14 wt% of oleic acid, 2.5-3.5% of linoleic acid, 1.5-2.5% of palmitic acid and 0.8-1.2% of stearic acid.

6. The PGA-modified blown film material of claim 1, wherein the polycaprolactone has a weight average molecular weight of 10 pg/mol or more.

7. The PGA-modified blown film material of claim 1, wherein the ADR resin has an epoxy equivalent of 250g/mol or more;

the ethylene acrylic acid copolymer is selected from 5980I of dow, usa.

8. A method for preparing the PGA modified blown film material according to any one of claims 1 to 7, which comprises the following steps:

70-80 parts of polyglycolic acid, 5-10 parts of compatilizer, 5-8 parts of polycaprolactone, 5-8 parts of plasticizer and 1-10 parts of opening agent are mixed for 20-30 min, and the PGA modified blown film material is obtained after granulation and drying.

9. The method of claim 8, wherein the granulation is carried out using a twin-screw extruder;

the length-diameter ratio of the double-screw extruder cannot be more than 1: 75;

the temperature of the feeding section of the double-screw extruder is 125-135 ℃, the temperature of the mixing section is not more than 160 ℃, and the temperature of the extrusion section is 185-195 ℃.

Background

PGA (polyglycolic acid), also known as polyglycolide, is the shortest segment structure of the completely biodegradable polymers known today. Because the repeating unit in the molecular structure is shortest, the aliphatic polyester material has the highest degradation speed, and can realize complete and rapid biodegradation even in seawater.

However, when manufacturing film bags, PGA materials often have problems with heat seal strength due to its hydrophilic nature, and poor seal strength results in a significant loss of performance in the film bag.

Disclosure of Invention

In view of the above, the present invention aims to provide a PGA-modified blown film material having excellent sealing properties, and a method for preparing the same.

The invention provides a PGA modified blown film material, which comprises the following raw materials in parts by weight:

70-80 parts of polyglycolic acid (PGA), 5-10 parts of a compatilizer, 5-8 parts of Polycaprolactone (PCL), 5-8 parts of a plasticizer and 1-10 parts of a opener;

the opening agent is selected from a mixture of amorphous white carbon black and erucamide;

the compatilizer is a mixture of ADR resin and ethylene acrylic acid copolymer;

the plasticizer is industrial castor oil.

In the invention, the polyglycolic acid has a weight average molecular weight of more than 30 ten thousand g/mol, a melting point of 200 to 220 ℃, a glass transition temperature of 45 to 55 ℃ and a specific gravity of 1.2 to 1.3g/cm³And ash content is less than 0.05%. In specific examples, the PGA has a weight average molecular weight of 55 ten thousand g/mol, a melting point of 220 deg.C, a glass transition temperature of 55 deg.C, and a specific gravity of 1.2g/cm³Ash content is less than 0.05%; or the PGA has a weight average molecular weight of 50 ten thousand g/mol, a melting point of 210 deg.C, a glass transition temperature of 50 deg.C, and a specific gravity of 1.3g/cm³Ash content 0.02%; or the weight average molecular weight of the PGA is 30 ten thousand g/mol, the melting point is 200 ℃, the glass transition temperature is 45 ℃, and the specific gravity is 1.2g/cm³And ash content is 0.03%.

In the invention, the mass ratio of the amorphous white carbon black to the erucamide is 1.5-2.5: 1, preferably 1.8-2.3: 1; in a specific embodiment, the mass ratio of the amorphous white carbon black to the erucamide is 2: 1. The amorphous white carbon black is nano silicon dioxide, and the particle size of the silicon dioxide is 1000-2000 meshes.

In the invention, the mass ratio of the ADR resin to the ethylene acrylic acid copolymer is 2.5-3.5: 1, preferably 2.8-3.2: 1; in a specific embodiment, the mass ratio of the ADR resin to the ethylene acrylic acid copolymer is 3: 1.

In the invention, the industrial castor oil comprises 80-87 wt% of ricinoleic acid, 7-14 wt% of oleic acid, 2.5-3.5% of linoleic acid, 1.5-2.5% of palmitic acid and 0.8-1.2% of stearic acid. In a specific embodiment, the industrial castor oil comprises 80% of ricinoleic acid, 14% of oleic acid, 3% of linoleic acid, 2% of palmitic acid and 1% of stearic acid; or the industrial castor oil comprises 85% of ricinoleic acid, 9% of oleic acid, 3% of linoleic acid, 2% of palmitic acid and 1% of stearic acid; or the industrial castor oil comprises 87% of ricinoleic acid, 7% of oleic acid, 3% of linoleic acid, 2% of palmitic acid and 1% of stearic acid.

In the invention, the weight average molecular weight of the polycaprolactone is more than or equal to 10 ten thousand g/mol. In specific embodiments, the weight average molecular weight of the polycaprolactone is 10, 15, or 30 ten thousand g/mol.

In the present invention, the ADR resin has an epoxy equivalent of 250g/mol or more; the ethylene acrylic acid copolymer is selected from 5980I of dow, usa. In particular embodiments, the ADR resin has an epoxy equivalent weight of 250g/mol, 350g/mol, or 300 g/mol.

In a specific embodiment of the invention, the PGA-modified blown film material comprises the following raw materials in parts by weight:

10 parts of a compatilizer, 80 parts of polyglycolic acid (PGA), 8 parts of Polycaprolactone (PCL), 8 parts of a plasticizer and 10 parts of a shedding agent;

or comprises 7 parts of compatilizer, 75 parts of polyglycolic acid (PGA), 6 parts of Polycaprolactone (PCL), 7 parts of plasticizer and 5 parts of opening agent;

or comprises 5 parts of compatilizer, 70 parts of polyglycolic acid (PGA), 5 parts of Polycaprolactone (PCL), 5 parts of plasticizer and 1 part of opening agent.

The invention provides a preparation method of the PGA modified blown film material in the technical scheme, which comprises the following steps:

70-80 parts of polyglycolic acid, 5-10 parts of compatilizer, 5-8 parts of polycaprolactone, 5-8 parts of plasticizer and 1-10 parts of opening agent are mixed for 20-30 min, and the PGA modified blown film material is obtained after granulation and drying.

In the invention, a double-screw extruder is adopted for granulation;

the length-diameter ratio of the double-screw extruder cannot be more than 1: 75; in specific embodiments, the twin screw extruder has a length to diameter ratio of 1: 85; or 1: 100; or 1: 75.

The temperature of the feeding section of the double-screw extruder is 125-135 ℃, the temperature of the mixing section is not more than 160 ℃, and the temperature of the extrusion section is 185-195 ℃.

All the raw materials adopted in the invention are preferably dried for more than 12 hours at the relative humidity of less than 10% and the temperature of 2-10 ℃. The weight loss water content of all raw materials is below 1 percent, otherwise, the requirement of the melt index in the actual processing process cannot be met; the melt index of the PGA modified blown film material prepared by the invention is required to be within 10g/10 min. Experimental results show that the melt indexes of the PGA modified blown film materials prepared by the embodiment of the invention are all within 10g/10 min.

In the specific embodiment of the invention, the temperature of the feeding section of the twin-screw extruder is 130 ℃, the temperature of the mixing section is 160 ℃, and the temperature of the extrusion section is 190 ℃.

The invention adopts an underwater granulating mode to granulate. In the invention, the drying is realized by combining air blast drying and vacuum drying, more specifically, air blast drying is carried out for 1.5-2.5 h at 75-85 ℃, then vacuum drying is carried out for 5.5-6.5 h at 60-70 ℃, and the vacuum degree is kept at 10 Pa.

The performance of the PGA modified blown film material is tested according to the following method:

the biodegradation rate is detected by GB/T19277.2. The Vicat softening temperature GB/T1633-2000. The sealing strength is detected by QB/T2358, and the test speed is 300mm/min +/-50 mm/min.

The invention provides a PGA modified blown film material, which comprises the following raw materials in parts by weight: 70-80 parts of polyglycolic acid, 5-10 parts of a compatilizer, 5-8 parts of polycaprolactone, 5-8 parts of a plasticizer and 1-10 parts of a opener; the opening agent is selected from a mixture of amorphous white carbon black and erucamide; the compatilizer is a mixture of ADR resin and ethylene acrylic acid copolymer; the plasticizer is industrial castor oil. According to the invention, the PGA modified blown film material obtained by modification has excellent sealing performance by adding the specific opening agent, the compatilizer, the plasticizer and the polycaprolactone into the polyglycolic acid, so that the service performance of the product is improved.

Detailed Description

In order to further illustrate the present invention, the PGA modified blown film material and the preparation method thereof provided by the present invention will be described in detail with reference to the following examples, which should not be construed as limiting the scope of the present invention.

Example 1

A method for improving sealing strength of PGA modified blown film products comprises the following steps: 5 parts of a compatilizer, 70 parts of polyglycolic acid (PGA), 5 parts of Polycaprolactone (PCL), 5 parts of a plasticizer and 1 part of a shedding agent. Low temperature and light shielding during storage.

The weight average molecular weight of the PGA is 30 ten thousand g/mol, the melting point is 200 ℃, the glass transition temperature is 45 ℃, and the specific gravity is 1.2g/cm³And ash content is 0.03%. The opening agent is a mixture of amorphous white carbon black (nano silicon dioxide) and erucamide, the mass ratio of the amorphous white carbon black to the erucamide is 2:1, the water content is lower than 2%, and the particle size of the silicon dioxide is 1000 meshes. The compatibilizer is a mixture of ADR resin produced by BASF and ethylene acrylic acid copolymer (EAA), wherein the epoxy equivalent weight of ADR is 250g/mol, and the EAA is 5980I Dow in USA, and the mass ratio of ADR resin to EAA is 3: 1. The plasticizer is industrial castor oil, and comprises 87% of ricinoleic acid, 7% of oleic acid, 3% of linoleic acid, 2% of palmitic acid and 1% of stearic acid. The weight average molecular weight of the polycaprolactone is 10 ten thousandg/mol, the influence on the sealing strength of the product can be ensured. After the preparation of the material is finished, the material is dried for more than 12 hours under the conditions that the relative humidity is less than 10 percent and the temperature is 5-10 ℃, and the weight loss water content of the material is measured to be 0.7 percent.

According to the method for improving the sealing strength of the PGA modified blown film product, the material is extruded by adopting a double screw rod, the raw materials are mixed for 20 minutes by using a high-speed mixer, and then the mixture is put into the double screw rod for granulation. The length-diameter ratio of the double-screw extruder is 1:75, the temperature of the feeding section is kept at about 130 ℃, the temperature of the mixing section is 160 ℃, and the temperature of the extrusion section is kept at 190 ℃. The material is granulated by adopting an underwater granulation mode, the finished master batch needs to be dried for 2 hours by adopting air blasting at the temperature of 80 ℃, then is dried for 6 hours in vacuum at the temperature of 65 ℃ by adopting a vacuum drying mode, and the vacuum degree needs to be kept below 10 Pa. The material is packaged by aluminum foil and stored in a dry environment.

Preparing the prepared master batch material and unmodified raw material PGA into a film product in a film blowing mode, carrying out Vicat softening temperature and degradation degree tests after heat sealing, and carrying out sealing strength and performance tests after respectively storing the film product for 1 day, 30 days, 60 days and 120 days, wherein the test results are as follows:

table 1 results of performance test of PGA film prepared in example 1

Example 2

A method for improving sealing strength of PGA modified blown film products comprises the following steps: 7 parts of compatilizer, 75 parts of polyglycolic acid (PGA), 6 parts of Polycaprolactone (PCL), 7 parts of plasticizer and 5 parts of opening agent. Low temperature and light shielding during storage.

The weight average molecular weight of the PGA is 50 ten thousand g/mol, the melting point is 210 ℃, and the glass is preparedThe transformation temperature is 50 ℃, and the specific gravity is 1.3g/cm³And ash content is 0.02%. The opening agent is a mixture of amorphous white carbon black (nano silicon dioxide) and erucamide, the mass ratio of the amorphous white carbon black to the erucamide is 2:1, the water content is lower than 2%, and the particle size of the silicon dioxide is 1500 meshes. The compatibilizer is a mixture of ADR resin produced by BASF and ethylene acrylic acid copolymer (EAA), wherein the epoxy equivalent weight of ADR is 350g/mol, and the EAA is 5980I of Dow, USA, and the mass ratio of ADR resin to EAA is 3: 1. The plasticizer is industrial castor oil, and comprises 85% of ricinoleic acid, 9% of oleic acid, 3% of linoleic acid, 2% of palmitic acid and 1% of stearic acid. The weight average molecular weight of the polycaprolactone is 15 ten thousand g/mol. After the preparation of the material is finished, the material is dried for 15 hours under the conditions of the relative humidity of 8 percent and the temperature of 7 ℃, and the weight loss water content of the material is measured to be 0.5 percent.

According to the method for improving the sealing strength of the PGA modified blown film product, the material is extruded by adopting a double screw rod, the raw materials are mixed for 25 minutes by using a high-speed mixer, and then the mixture is put into the double screw rod for granulation. The length-diameter ratio of the double-screw extruder is 1:100, the temperature of the feeding section is kept at 135 ℃, the temperature of the mixing section is kept at 140 ℃, and the temperature of the extrusion section is kept at 190 ℃. The material is granulated by adopting an underwater granulation mode, the finished master batch is dried for 2 hours by adopting blast air at the temperature of 80 ℃, and then is dried for 6 hours in vacuum at the temperature of 65 ℃ by adopting a vacuum drying mode, and the vacuum degree needs to be kept below 10 Pa. The material is packaged by aluminum foil and stored in a dry environment.

Preparing the prepared master batch material and unmodified raw material PGA into a film product in a film blowing mode, carrying out Vicat softening temperature and degradation degree tests after heat sealing, and carrying out sealing strength and performance tests after respectively storing the film product for 1 day, 30 days, 60 days and 120 days, wherein the test results are as follows:

table 2 results of performance test of PGA film prepared in example 2

Example 3

A method for improving sealing strength of PGA modified blown film products comprises the following steps: 10 parts of compatilizer, 80 parts of polyglycolic acid (PGA), 8 parts of Polycaprolactone (PCL), 8 parts of plasticizer and 10 parts of opening agent. Low temperature and light shielding during storage.

The PGA has a weight average molecular weight of 55 ten thousand g/mol, a melting point of 220 ℃, a glass transition temperature of 55 ℃ and a specific gravity of 1.2g/cm³And ash content is less than 0.05%. The opening agent is a mixture of amorphous white carbon black (nano silicon dioxide) and erucamide, the mass ratio of the amorphous white carbon black to the erucamide is 2:1, the water content is 1%, and the particle size of the silicon dioxide is larger than 2000 meshes. The compatibilizer is a mixture of ADR resin produced by BASF and ethylene acrylic acid copolymer (EAA), wherein the epoxy equivalent weight of ADR is 300g/mol, and the EAA is 5980I of Dow, USA, and the mass ratio of ADR resin to EAA is 3: 1. The plasticizer is industrial castor oil, and comprises 80% of ricinoleic acid, 14% of oleic acid, 3% of linoleic acid, 2% of palmitic acid and 1% of stearic acid. The weight average molecular weight of the polycaprolactone is 30 ten thousand g/mol. After the preparation of the material is finished, the material is dried for 13 hours under the conditions that the relative humidity is below 7 percent and the temperature is 510 ℃, and the weight loss water content of the material is measured to be 0.4 percent.

According to the method for improving the sealing strength of the PGA modified blown film product, a double-screw extrusion process is adopted for the material, the raw materials are mixed for 30 minutes by a high-speed mixer, and then the mixture is put into double screws for granulation. The length-diameter ratio of the double-screw extruder is 1:85, the temperature of the feeding section is kept at 135 ℃, the temperature of the mixing section is kept at 155 ℃, and the temperature of the extrusion section is kept at 190 ℃. The material is granulated by adopting an underwater granulation mode, the finished master batch is dried for 2 hours by adopting blast air at the temperature of 80 ℃, and then is dried for 6 hours in vacuum at the temperature of 65 ℃ by adopting a vacuum drying mode, and the vacuum degree needs to be kept below 10 Pa. The material is packaged by aluminum foil and stored in a dry environment.

Preparing the prepared master batch material and unmodified raw material PGA into a film product in a film blowing mode, carrying out Vicat softening temperature and degradation degree test after heat sealing, and carrying out sealing strength and performance test after respectively storing the film product for 1 day, 30 days, 60 days and 120 days, wherein the test results are as follows:

table 3 results of performance test of PGA film prepared in example 3

Comparative example 1

On the basis of the embodiment 3, polycaprolactone is replaced by polyhydroxyalkanoate, and the opening agent is replaced by talcum powder.

Comparative example 2

On the basis of example 3, the compatibilizer was replaced by organic montmorillonite, and the plasticizer was replaced by butylene terephthalate.

TABLE 4 results of performance test of PGA thin films prepared in comparative examples

From the above embodiments, the present invention provides a PGA modified blown film material, which comprises the following raw materials in parts by weight: 70-80 parts of polyglycolic acid, 5-10 parts of a compatilizer, 5-8 parts of polycaprolactone, 5-8 parts of a plasticizer and 1-10 parts of a opener; the opening agent is selected from a mixture of amorphous white carbon black and erucamide; the compatilizer is a mixture of ADR resin and ethylene acrylic acid copolymer; the plasticizer is industrial castor oil. According to the invention, the PGA modified blown film material obtained by modification has excellent sealing performance by adding the specific opening agent, the compatilizer, the plasticizer and the polycaprolactone into the polyglycolic acid, so that the service performance of the product is improved. The experimental results show that: the Vicat softening temperature of the film prepared from the PGA modified blown film material is 205-213 ℃, the sealing strength after 1 day is 10-12N/15 mm, the sealing strength after 30 days is 9-10.5N/15 mm, the sealing strength after 60 days is 8.8-9.5N/15 mm, and the sealing strength after 120 days is 8.2-9.3N/15 mm.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.