CN114108383B

CN114108383B - Degradable barrier material and application thereof

Info

Publication number: CN114108383B
Application number: CN202111327585.4A
Authority: CN
Inventors: 李银勇
Original assignee: Zhejiang Yuewei New Materials Technology Co ltd
Current assignee: Zhejiang Yuewei New Materials Technology Co ltd
Priority date: 2021-11-10
Filing date: 2021-11-10
Publication date: 2022-12-30
Anticipated expiration: 2041-11-10
Also published as: CN114108383A

Abstract

The invention discloses a degradable barrier material and application thereof. The degradable barrier material comprises a polyester emulsion and a thickening agent, and also comprises a barrier reinforcing agent. The degradable barrier material has good biocompatibility and high safety, can be used for food packaging, and has no overflow of harmful ingredients; the adopted polyester particles, emulsifier, thickener and barrier enhancer are bio-based materials, can be completely biodegraded, and are environment-friendly; the paper-based barrier material obtained by compounding the paper-based material with the paper-based material has good barrier property, is waterproof, oilproof and alcohol-proof, and can be completely biodegraded.

Description

Degradable barrier material and application thereof

Technical Field

The invention relates to the technical field of packaging paper preparation, in particular to a degradable barrier material and application thereof.

Background

The barrier materials currently used for paper-based coating are mainly surface waxing, PE film coating or olefin/acrylic barrier coating. However, the melting point of wax is low and cannot be used in a high-temperature environment; PE coated paper is difficult to biodegrade, and waste paper of the PE coated paper cannot be copied and reused, so that environmental pollution is caused; the acrylic functional coating can be reused after being coated, but the coating is micro-plastic in the production engineering and is difficult to biodegrade. With the wide popularization of plastic-limited orders, various manufacturers attach more importance to degradable and renewable packaging materials. Therefore, there is a need to develop more environmentally friendly food grade degradable barrier materials for paper coating.

Patent application CN110184854A introduces a preparation method of PLA (polylactic acid) coated paper, and the coated paper prepared by the method has good water and oil proofing effects. However, the method needs to use a higher temperature (170-250 ℃) for film coating, and at the temperature, polyesters such as PLA, PCL and the like are easy to thermally degrade, so that the performance of the coating is affected. In addition, the method has the advantages of large coating weight (> 20 gsm) and high cost.

Patent application US6103858A discloses a method for high-temperature high-pressure melt emulsification. The method melts polyester under high temperature condition and emulsifies the polyester in water by a high-speed shearing method. However, because the melting point of polyester is high (usually 120-180 ℃), the emulsifying temperature is higher than the melting point of the polyester material (usually 150-230 ℃), and the temperature is far higher than the boiling point of the water phase, the emulsifying process needs to be carried out in a high-pressure reaction kettle, and the polyester is easily degraded under the condition, so that the performance is influenced. Meanwhile, the high-pressure reaction kettle has the defects of high energy consumption, high safety risk, high cost and the like, and is not beneficial to large-scale production.

Patent applications CN107001774B, JP2004099883A and JP2002356612A adopt ethyl acetate as solvent, polyacrylic acid-acrylamide, polyvinyl alcohol and the like as emulsifier, and carry out high-speed shearing emulsification at 120 ℃. Although the temperature is lower than the melting emulsification temperature described in the previous example, the temperature is still far higher than the boiling point (77.2 ℃) of ethyl acetate, and the method also adopts a high-pressure reaction kettle for emulsification, so the method has the problems of high energy consumption, high cost and the like. In addition, ethyl acetate is flammable and explosive under high temperature and high pressure conditions, and has a large safety risk, so that the method is not suitable for large-scale low-cost production.

The PLA microsphere emulsion is successfully prepared by adopting an emulsification/solvent removal method in the literature (J.Agric.food chem.2012,60,16,4111-4119, int.J.Pharm.2005,295, 201; journal of Controlled Release 99 (2004) 271-280), but the proportion of an oil phase and an aqueous phase is very low and is only 1/10, the content of polylactic acid in the oil phase is less than 10%, and the solid content of the prepared emulsion is less than 1%, so that the method is not beneficial to low-cost large-scale production.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a degradable barrier material.

Another object of the present invention is to provide the use of the above degradable barrier material.

The purpose of the invention is realized by the following technical scheme: a degradable barrier material comprises a polyester emulsion and a thickening agent.

Preferably, the degradable barrier material further comprises a barrier enhancer.

Preferably, the polyester emulsion is at least one of polylactic acid (PLA) emulsion and Polycaprolactone (PCL) emulsion; more preferably, the polyester emulsion is a polylactic acid emulsion.

Preferably, the thickener is a biopolymer; more preferably, the thickener is at least one of carboxymethyl cellulose, gelatin, sodium hyaluronate, xanthan gum and methyl cellulose; most preferably, the thickener is carboxymethyl cellulose or sodium hyaluronate.

Preferably, the barrier reinforcing agent is at least one of cellulose nano-fiber, cellulose nanocrystalline, cellulose microcrystal, microfibrillated cellulose, chitin nano-fiber and chitin nanocrystalline; more preferably, the barrier enhancing agent is a cellulose nanofiber or a cellulose nanocrystal.

Preferably, the preparation method of the polyester emulsion comprises the following steps: adding the polyester/dichloromethane organic phase into an aqueous phase containing an emulsifier, emulsifying, and removing the solvent to obtain a polyester emulsion.

Preferably, the mass fraction of polyester in the polyester/dichloromethane organic phase is between 5% and 50%.

Preferably, the emulsifier is an alkyl glycoside (APG) surfactant; more preferably, the emulsifier is at least one of APG0810, APG1214, APG0814, APG0816, APG 1216; most preferably, the emulsifier is APG0810.

Preferably, the emulsifier is added while simultaneously adding the emulsification enhancer.

Preferably, the emulsification enhancer is an inorganic nanoparticle; more preferably, the emulsification enhancer is at least one of silica nanoparticles, titanium dioxide nanoparticles, zinc oxide nanoparticles, and calcium carbonate nanoparticles; more preferably, the emulsification enhancer is silica nanoparticles.

Preferably, the emulsification method is high-speed mechanical stirring, ultrasound or high-pressure homogenization; more preferably, it is a high speed mechanical agitation.

Preferably, the solvent is removed by stirring or vacuum.

Preferably, the particle size of the polyester emulsion is 0.5-20 μm, and the solid content is 10% -50%; more preferably, the particle size is 0.5 to 5 μm and the solid content is 30 to 50%.

Preferably, the degradable barrier material comprises the following components in parts by mass: 5-45% of polyester particles, 0.1-12% of emulsifier, 0-5% of emulsification reinforcing agent, 0.05-2% of thickening agent, 0-5% of barrier reinforcing agent and the balance of water; more preferably, in terms of mass fractions: 10 to 40 percent of polyester particles, 0.2 to 5 percent of emulsifier, 0.5 to 3 percent of emulsification reinforcing agent, 0.1 to 1 percent of thickening agent, 0.5 to 4 percent of barrier reinforcing agent and the balance of water; most preferably, in terms of mass fractions: 20 to 30 percent of polyester particles, 0.5 to 2 percent of emulsifier, 1 to 2 percent of emulsification reinforcing agent, 0.2 to 0.5 percent of thickening agent, 1 to 3 percent of barrier reinforcing agent and the balance of water.

The preparation process of the degradable barrier material comprises the following steps: and fully stirring the polyester emulsion and the thickening agent to obtain the polyester emulsion.

The degradable barrier material is applied to the preparation of paper-based barrier materials.

The preparation method of the paper-based barrier material comprises the following steps: and (3) coating the degradable barrier material on the paper-based material, and carrying out heat treatment on the steel roller to obtain the paper-based barrier material.

Preferably, the coating weight of the degradable barrier material is 4 to 20g/m ² (ii) a More excellentOptionally, the coating weight is 4-10 g/m ² 。

Preferably, the temperature of the steel roller heat treatment is 100-150 ℃; more preferably, the temperature is from 100 to 120 ℃.

The thickening agent is a bio-based emulsion, can effectively improve the stability of the polyester emulsion, and can 'glue' the polyester particles in the drying process, thereby improving the film forming property of the polyester emulsion.

The barrier enhancer enhances the barrier properties of the water and oil repellent coating.

In the preparation of the emulsion, emulsion reinforcing agent-inorganic nano particles can be added, which can effectively prevent the emulsion from agglomerating in the process of removing the solvent, thereby improving the emulsifying efficiency and reducing the using amount of the emulsifier. In addition, the emulsion enhancer nanoparticles may also enhance the mechanical properties of the coated film.

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

1. the polyester particles, the emulsifier, the thickener and the barrier reinforcing agent adopted by the degradable barrier material are bio-based materials, can be completely biodegraded, and are environment-friendly; the material is food grade, has good biocompatibility and high safety, can be used for food packaging, and has no harmful ingredient overflow.

2. The APG emulsifier adopted by the invention not only has the biodegradable characteristic, but also has good emulsifying effect on the polyester/dichloromethane solution organic phase. Other commonly used emulsifiers, such as tween series, whey protein, sodium caseinate, alkyl sulfonate series, alkyl sulfate series, polyvinyl alcohol, polyacrylic acid-acrylamide, etc., cannot emulsify polyester/methylene chloride organic phase into stable emulsion with high solid content under normal temperature and pressure conditions. In addition, the non-degradable emulsifier is not favorable for the degradation of the polyester component, and is not in accordance with the concept of environmental protection.

3. The preparation method of the polyester emulsion is simple, does not need high temperature and high pressure, has low production cost, is safe and environment-friendly, and is suitable for producing high-performance polyester emulsion on a large scale.

4. The invention adopts an optimized emulsifying system, the mass ratio of organic phase/water phase is high and can reach more than 5/1 at most, and the solid content of the prepared emulsion is high and can reach more than 50 at most. In contrast, in the comparative documents (J.Agric.food chem.2012,60,16,4111-4119, int.J.Pharm.2005,295, 201), the oil phase/water phase ratio is only 1/10, and the resulting emulsion has a solids content of only about 1%.

5. The paper-based barrier material obtained by compounding the degradable barrier material and the paper-based material has good barrier property, is waterproof, oilproof and alcohol-proof, and can be completely biodegraded.

Drawings

FIG. 1 is a photograph of PLA emulsion obtained in example 1 using APG0810 as an emulsifier.

FIG. 2 is a photograph of PLA emulsion obtained in example 6 using APG0810 at a low concentration as an emulsifier and silica nanoparticles as an emulsification enhancer.

FIG. 3 is a photograph showing agglomeration of the product obtained in comparative example 1 using PVA as an emulsifier after removing the solvent by stirring.

FIG. 4 is a photograph showing emulsion breaking and aggregation during the process of removing a solvent by stirring the emulsion obtained by using only a low concentration of the emulsifier without adding the silica emulsion enhancer in comparative example 2.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings 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 of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of protection of the present invention.

Example 1

The method comprises the following steps: taking 25 parts by mass of PLA master batch, drying in an oven at 80 ℃ for 1 hour, adding the PLA master batch into 75 parts by mass of Dichloromethane (DCM) solvent under the stirring state, and fully stirring and dissolving to obtain a 25% (w/w) PLA/DCM organic phase.

Step two: adding 1 part by mass of APG0810 emulsifier into 74 parts by mass of water under the stirring state, and fully dissolving; slowly adding 100 parts by mass of PLA/DCM organic phase into 75 parts by mass of water, and shearing and emulsifying by high-speed stirring (5000 rpm); the emulsion was stirred mechanically to remove the DCM solvent to give a PLA emulsion with 25% (w/w) PLA concentration and 10.3 μm PLA mean particle size (FIG. 1).

Step three: adding 20 parts by mass of 1.5% (w/w) carboxymethyl cellulose aqueous solution into 100 parts by mass of PLA emulsion, and fully stirring to obtain the degradable barrier material with good stability.

Step four: coating the degradable barrier material on the surface of a paper-based material by adopting an air knife coating mode (the coating weight is 10 g/m) ² ) And then the paper-based barrier material which has good water resistance, oil resistance and alcohol resistance and can be biodegraded is obtained by heat treatment of a steel roller at 150 ℃.

Example 2

The method comprises the following steps: in accordance with example 1.

Step two: adding 5 parts by mass of APG0810 emulsifier into 25 parts by mass of water under the stirring state, and fully dissolving; slowly adding 80 parts by mass of PLA/DCM organic phase into 30 parts by mass of water, and shearing and emulsifying in a homogenizer at high speed (10000 rpm); the emulsion was stirred mechanically to remove the DCM solvent to give an emulsion with a PLA concentration of 40% (w/w) and a PLA mean particle size of 1.9. Mu.m.

Step three and step four were identical to example 1.

Example 3

The method comprises the following steps: in accordance with example 1.

Step two: adding 2 parts by mass of APG0810 emulsifier and 3 parts by mass of 30% (w/w) concentration silicon dioxide nanoparticles (8 nm) into 25 parts by mass of water under stirring, and fully dissolving; slowly adding 80 parts by mass of PLA/DCM organic phase into 30 parts by mass of water phase, and shearing and emulsifying in a homogenizer at high speed (10000 rpm); the emulsion was stirred mechanically to remove the DCM solvent to give an emulsion with a PLA concentration of 40% (w/w) and a PLA mean particle size of 1.4. Mu.m.

Step three and step four were identical to example 1.

Example 4

The method comprises the following steps: and (3) taking 20 parts by mass of PLA master batches, drying the PLA master batches in an oven at 80 ℃ for 1 hour, adding the PLA master batches into 80 parts by mass of DCM solvent in a stirring state, and fully stirring and dissolving to obtain a 20% (w/w) PLA/DCM organic phase.

Step two: adding 3 parts by mass of APG0810 emulsifier and 3 parts by mass of 30% concentration silica nanoparticles (8 nm) into 24 parts by mass of water under stirring, and fully dissolving; slowly adding 60 parts by mass of PLA/DCM organic phase into 30 parts by mass of water phase, and shearing and emulsifying in a homogenizer at high speed (10000 rpm); the emulsion was stirred mechanically to remove DCM and to obtain a PLA emulsion with an average particle size of 0.92. Mu.m.

Step three: adding sodium hyaluronate and a proper amount of water, controlling the concentration of PLA to be 30% (w/w) and the concentration of sodium hyaluronate to be 0.2% (w/w), and fully stirring to obtain the degradable barrier material with good stability.

Step four: the obtained degradable barrier material is coated on the surface of a paper-based material by adopting an air knife coating mode, and then is subjected to heat treatment by a steel roller at 100 ℃ to obtain the biodegradable paper-based barrier material with good water resistance, oil resistance and alcohol resistance. The paper-based barrier material has a Water Vapor Transmission Rate (WVTR) of 15.01 g/(m) under a test condition of 38 ℃ and a relative humidity of 90% ² .h)。

Example 5

Step one and step two are the same as in example 4.

Step three: adding sodium hyaluronate, cellulose Nanocrystalline (CNC) and a proper amount of water into the PLA emulsion, controlling the concentration of PLA to be 30% (w/w), the concentration of sodium hyaluronate to be 0.2% (w/w) and the concentration of CNC to be 4% (w/w), and fully stirring to obtain the degradable barrier material with good stability.

Step four was identical to example 4 to obtain a paper-based barrier material. The paper-based barrier material has a Water Vapor Transmission Rate (WVTR) of 7.35 g/(m) under test conditions of 38 ℃ and a relative humidity of 90% ² H). Compared to the paper-based barrier material without CNC in example 4, the addition of CNC at about 12% solids in example 5 greatly reduced the water vapor transmission rate of the paper-based barrier material, improving the vapor barrier properties.

Example 6

Step one corresponds to example 1.

Step two: adding 0.5 part by mass of APG0810 emulsifier into 26.5 parts by mass of water under a stirring state, fully dissolving, and then adding 3 parts by mass of 30% (w/w) concentration silicon dioxide nanoparticles (8 nm) to prepare 30 parts by mass of a water phase; slowly adding 80 parts by mass of PLA/DCM organic phase into 30 parts by mass of water phase, and shearing and emulsifying under high-speed stirring (8000 rpm); the emulsion was stirred mechanically to remove the DCM solvent to give an emulsion with a PLA concentration of 40% (w/w) and a PLA mean particle size of 6.2. Mu.m. The emulsion stability was good and no agglomeration of the emulsion occurred after removal of the solvent, as shown in figure 2.

Example 7

The method comprises the following steps: taking 10 parts by mass of PCL master batch, and drying in an oven at 80 ℃ for 1 hour; the resulting solution was added to 90 parts by mass of a Dichloromethane (DCM) solvent with stirring, and dissolved by stirring sufficiently to obtain a PCL/DCM solution having a concentration of 10% (w/w).

Step two: adding 2 parts by mass of APG1214 emulsifier and 2 parts by mass of 30% silica nanoparticles (8 nm) into 26 parts by mass of water under stirring, and sufficiently dissolving; slowly adding 80 parts by mass of PCL/DCM organic phase into 30 parts by mass of water phase, and shearing and emulsifying at high speed (10000 rpm) in a homogenizer; the emulsion was stirred mechanically to remove the DCM solvent to give an emulsion with a PCL concentration of 21% (w/w) and an average particle size of 2.9 μm.

Step three: adding 1 part by mass of 1% (w/w) xanthan gum aqueous solution with concentration into 10 parts by mass of PCL emulsion, and fully stirring to obtain the degradable barrier material with good stability.

Step four: the obtained degradable barrier material is coated on the surface of a paper-based material by adopting an air knife coating mode, and then is hot-pressed by a steel roller at 100 ℃ to obtain the biodegradable paper-based barrier material with good water resistance, oil resistance and alcohol resistance.

The oil-proof performance of the barrier paper obtained in the embodiment is close to that of PE film coated paper, and the barrier paper has good water-proof and oil-proof effects. Examples 1, 4, 7 paper-based barrier materials using polyester as the raw material showed oil repellency as shown in table 1.

TABLE 1 comparison of oil-proof performance of paper-based barrier material and PE (polyethylene) coated paper sold in market

Comparative example 1

The method comprises the following steps: in accordance with example 1.

Step two: taking 1 part by mass of polyvinyl alcohol (PVA) as an emulsifier, adding the emulsifier into 74 parts by mass of water under a stirring state, and fully dissolving; 100 parts by mass of PLA/DCM organic phase is slowly added into 75 parts by mass of water phase, the mixture is stirred at high speed (5000 rpm) and sheared, the emulsification effect is poor, uniform emulsion can not be obtained, and PVA is agglomerated after solvent DCM is removed, as shown in figure 3.

Comparative example 2

Step one corresponds to example 1.

Step two: adding 0.5 mass part of APG0810 emulsifier into 29.5 mass parts of water under stirring, and fully dissolving to obtain 30 mass parts of water phase; slowly adding 80 parts by mass of PLA/DCM organic phase into 30 parts of water phase, and shearing and emulsifying under high-speed stirring (8000 rpm); a uniform emulsion can be obtained after emulsification, but when the DCM solvent is removed, the emulsion is broken, the agglomeration of particles is obvious, and a uniform and stable emulsion cannot be obtained, as shown in fig. 4.

Comparative example 3

Step one corresponds to example 1.

Step two: adding 0.5 part by mass of sodium caseinate emulsifier into 26.5 parts by mass of water under a stirring state, fully dissolving, and adding 3 parts by mass of 30% (w/w) concentration silicon dioxide nanoparticles (8 nm) to prepare 30 parts by mass of a water phase; 80 parts by mass of the PLA/DCM organic phase are slowly added to 30 parts by mass of the aqueous phase and emulsified by shearing with high-speed stirring (8000 rpm). The formulation does not complete emulsification and the organic phase is not completely dispersed to form a uniform emulsion.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.

Claims

1. A degradable barrier material, which is characterized by comprising a polyester emulsion and a thickening agent;

the polyester emulsion is at least one of polylactic acid emulsion and polycaprolactone emulsion;

the preparation method of the polyester emulsion comprises the following steps: adding the polyester/dichloromethane organic phase into an aqueous phase containing an emulsifier, emulsifying, and removing the solvent to obtain a polyester emulsion;

the emulsifier is alkyl glycoside surfactant;

the thickening agent is at least one of carboxymethyl cellulose, gelatin, sodium hyaluronate, xanthan gum and methyl cellulose;

the degradable barrier material further comprises a barrier enhancer;

the barrier reinforcing agent is at least one of cellulose nano-fiber, cellulose nano-crystal, cellulose microcrystal, microfibrillated cellulose, chitin nano-fiber and chitin nano-crystal.

2. The degradable barrier material of claim 1,

the polyester emulsion is polylactic acid emulsion.

3. The degradable barrier material of claim 1, wherein,

the thickening agent is carboxymethyl cellulose or sodium hyaluronate;

the barrier reinforcing agent is cellulose nanofiber or cellulose nanocrystal.

4. The degradable barrier material of claim 1,

the mass fraction of the polyester in the polyester/dichloromethane organic phase is 5% -50%;

the particle size of the polyester emulsion is 0.5-20 mu m, and the solid content is 10-50%.

5. The degradable barrier material of claim 4,

the emulsifier is at least one of APG0810, APG1214, APG0814, APG0816 and APG 1216;

the particle size of the polyester emulsion is 0.5-5 mu m, and the solid content is 30-50%;

when the emulsifier is added, an emulsion enhancer which is inorganic nano-particles is added at the same time;

the emulsification method comprises high-speed mechanical stirring, ultrasonic or high-pressure homogenization;

the solvent is removed by stirring or vacuumizing.

6. The degradable barrier material of claim 5, wherein the emulsification enhancer is at least one of silica nanoparticles, titanium dioxide nanoparticles, zinc oxide nanoparticles, and calcium carbonate nanoparticles.

7. The degradable barrier material of claim 6, wherein the degradable barrier material comprises the following components in parts by mass: 5 to 45 percent of polyester particles, 0.1 to 12 percent of emulsifier, 0 to 5 percent of emulsification reinforcing agent, 0.05 to 2 percent of thickening agent, 0 to 5 percent of barrier reinforcing agent and the balance of water.

8. The degradable barrier material of claim 7, wherein the degradable barrier material comprises the following components in parts by mass: 10 to 40 percent of polyester particles, 0.2 to 5 percent of emulsifier, 0.5 to 3 percent of emulsification reinforcing agent, 0.1 to 1 percent of thickening agent, 0.5 to 4 percent of barrier reinforcing agent and the balance of water.

9. The degradable barrier material of claim 8 wherein the degradable barrier material comprises the following components in percentage by mass: 20 to 30 percent of polyester particles, 0.5 to 2 percent of emulsifier, 1 to 2 percent of emulsification reinforcing agent, 0.2 to 0.5 percent of thickening agent, 1 to 3 percent of barrier reinforcing agent and the balance of water.

10. Use of the degradable barrier material of any one of claims 1 to 9 in the preparation of a paper-based barrier material, wherein the paper-based barrier material is prepared by coating the degradable barrier material on a paper-based material, and performing steel roll heat treatment to obtain the paper-based barrier material;

the coating weight of the degradable barrier material is 4 to 20g/m ² ；

The heat treatment temperature of the steel roller is 100-150 ℃.