CN120535919A - A PU/PBAT composite film and its preparation method and application - Google Patents

Abstract

The invention provides a PU/PBAT composite film and a preparation method and application thereof, wherein the PU/PBAT composite film comprises polyurethane emulsion and polybutylene adipate/terephthalate, the raw materials of the polyurethane emulsion comprise polyalcohol, isocyanate, a catalyst, a hydrophilic chain extender, gallic acid, a structural chain extender and a salifying agent, and the gallic acid is introduced into the polyurethane emulsion as the raw material and then is blended with the polybutylene adipate/terephthalate, so that the oxidation resistance of the PU/PBAT composite film can be effectively improved, and excellent mechanical properties and excellent hydrophobic properties can be maintained.

Description

PU/PBAT composite film and preparation method and application thereof

Technical Field

The invention belongs to the technical field of composite films, and particularly relates to a PU/PBAT composite film, a preparation method and application thereof.

Background

The poly (butylene adipate/terephthalate) (PBAT) is a food packaging application material with great potential due to complete biodegradability, excellent thermal stability and high flexibility, but the oxidation resistance of the pure PBAT can not meet the application requirement in food packaging, so that the improvement of the related performance of the pure PBAT is still of great significance.

The film can be provided with oxidation resistance by adding natural organic compounds such as flavonoids, catechins and derivatives thereof. Gallic acid is a polyphenol organic compound, is widely applied to plants such as rheum palmatum, eucalyptus robusta, dogwood and the like, and has wide application in the fields of food, biology, medicine, chemical industry and the like. Gallic acid has various biological activities such as anti-inflammatory, anti-mutation, anti-oxidation, anti-free radical and the like, and can be used as a raw material to synthesize gallic acid ester compounds, which are all food antioxidants with excellent performance. There have been studies on modification of the addition of gallic acid to PBAT. However, due to the low compatibility of gallic acid with PBAT, the mechanical properties and other properties of PBAT are adversely affected

In summary, developing a PU/PBAT composite film with excellent oxidation resistance and mechanical properties is still an urgent technical problem to be solved in the field.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a PU/PBAT composite film, a preparation method and application thereof, wherein the PU/PBAT composite film has excellent oxidation resistance and mechanical properties, and also has excellent hydrophobic property, and can be used as a packaging material.

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

In a first aspect, the invention provides a PU/PBAT composite film, wherein the PU/PBAT composite film comprises polyurethane emulsion and polybutylene adipate/terephthalate;

The raw materials of the polyurethane emulsion comprise polyalcohol, isocyanate, catalyst, hydrophilic chain extender, gallic acid, structural chain extender and salifying agent.

According to the invention, gallic acid is introduced into Polyurethane (PU) emulsion and then is blended with poly (adipic acid)/butylene terephthalate (PBAT), so that the compatibility of the gallic acid and the poly (adipic acid)/butylene terephthalate (PBAT) can be effectively improved, and the obtained PU/PBAT composite film has excellent oxidation resistance and hydrophobic performance on the premise of keeping excellent mechanical properties.

Preferably, the mass ratio of the polyurethane emulsion to the poly (adipic acid)/butylene terephthalate is (10-50): (50-90), for example, 10:90, 15:85, 20:80, 25:75, 30:70, 35:65, 40:60 or 50:50, etc., and more preferably (20-30): (70-80).

Preferably, the molar ratio of the polyol to the isocyanate to the hydrophilic chain extender to the gallic acid to the structural chain extender to the salt forming agent is (2.5-4.5) 10 (1.5-2.5) 0.5-0.8 (1.5-3.5) 1.5-2.5;

wherein the molar ratio of polyol to isocyanate may be 2.5:10, 2.6:10, 2.7:10, 2.8:10, 2.9:10, 3:10, 3.1:10, 3.2:10, 3.3:10, 3.4:10, 3.5:10, 4:10, or 4.5:10, etc.

The molar ratio of isocyanate to hydrophilic chain extender may be 10:1.5, 10:1.6, 10:1.7, 10:1.8, 10:1.9, 10:2, 10:2.1, 10:2.2, 10:2.3, 10:2.4, 10:2.5, etc.

The molar ratio of isocyanate to gallic acid may be 10:0.5, 10:0.55, 10:0.6, 10:0.65, 10:0.7, 10:0.75, or 10:0.8, etc.

The molar ratio of isocyanate to structural chain extender may be 10:1.5, 10:1.6, 10:1.7, 10:1.8, 10:1.9, 10:2, 10:2.1, 10:2.2, 10:2.3, 10:2.4, 10:2.5, 10:3, or 10:3.5, etc.

The molar ratio of the isocyanate to the salt former is 10:1.5, 10:1.6, 10:1.7, 10:1.8, 10:1.9, 10:2, 10:2.1, 10:2.2, 10:2.3, 10:2.4, 10:2.5, etc.

Preferably, the polyol comprises any one or a combination of at least two of polytetrahydrofuran, castor oil or polyethylene glycol.

Preferably, the number average molecular weight of the polyol is 500 to 2000, for example 500, 700, 900, 1100, 1300, 1500, 1700 or 1900, etc.

Preferably, the isocyanate comprises any one or a combination of at least two of isophorone diisocyanate, hexamethylene diisocyanate, 4' -dicyclohexylmethane diisocyanate, diphenylmethane diisocyanate or toluene diisocyanate.

Preferably, the hydrophilic chain extender comprises 2, 2-bis (hydroxymethyl) propionic acid and/or 2, 2-dimethylolbutyric acid.

Preferably, the structural chain extender comprises 1, 4-butanediol and/or 1, 6-hexanediol.

Preferably, the salifying agent comprises any one or a combination of at least two of triethylamine, sodium hydroxide or hydrochloric acid.

Preferably, the catalyst is used in an amount of 0.01 to 0.04mmol, for example 0.01mmol, 0.015mmol, 0.02mmol, 0.025mmol, 0.03mmol, 0.035mmol, 0.04mmol, etc., based on 1mmol of the isocyanate.

Preferably, the catalyst comprises any one or a combination of at least two of stannous octoate, dibutyltin dilaurate or diethyl tin dilaurate.

Preferably, the raw materials of the polyurethane emulsion further comprise a solvent.

Preferably, the amount of the solvent is 1 to 3mL, for example, 1mL, 1.2mL, 1.4mL, 1.6mL, 1.8mL, 2mL, 2.2mL, 2.4mL, 2.6mL, 2.8mL, 3mL, or the like, based on 1mmol of the polyol.

Preferably, the solvent comprises acetone.

Preferably, the polyurethane emulsion is obtained by reacting a polyol, an isocyanate, a hydrophilic chain extender, gallic acid, a structural chain extender and a salt former.

Preferably, a solvent is added during the reaction to adjust the viscosity of the reactants.

Preferably, the reaction specifically comprises the steps of pre-polymerizing the polyol and the isocyanate for 0.5-2 hours (e.g. 0.5 hours, 0.7 hours, 0.9 hours, 1.1 hours, 1.3 hours, 1.5 hours, 1.7 hours, 1.9 hours or 2 hours, etc.) at 70-100 ℃ (e.g. 70 ℃, 75 ℃, 80 ℃, 85 ℃, 90 ℃, 95 ℃ or 100 ℃, etc.), adding the catalyst and the hydrophilic chain extender for chain extension for 0.5-2 hours (e.g. 0.5 ℃, 0.7 ℃, 0.9 hours, 1.1 hours, 1.3 hours, 1.5 hours, 1.7 hours, 1.9 hours or 2 hours, etc.), adding gallic acid and the structural chain extender for chain extension for 1-4 hours (e.g. 1.5 hours, 2 hours, 3 hours, 3.5 hours or 4 hours, etc.), cooling to 30-50 ℃ (e.g. 30 ℃, 35 ℃, 45 ℃, 0.9 hours, 1.1.3 hours, 3.3 hours, 3 hours, 0.3 ℃ or 4 hours, etc.), and adding the catalyst and the hydrophilic chain extender into the emulsion for the reaction (e.0.5 ℃, 0.7 ℃,0 ℃ or 0.9 hours, 0.0 ℃ or 0).

The step of adding the solvent is not particularly limited, and the solvent may be selectively added according to the actual reaction condition, and when the system viscosity is observed to be increased, that is, the rotation speed of the rotor is reduced in the reaction process, acetone may be added to adjust the system viscosity.

In a second aspect, the invention provides a preparation method of the PU/PBAT composite film, which comprises the steps of mixing polyurethane emulsion and polybutylene adipate/terephthalate in an organic solvent to form a film, so as to obtain the PU/PBAT composite film.

Preferably, the preparation method comprises the following steps:

(1) Dissolving polyurethane emulsion in an organic solvent to obtain a dispersion liquid;

(2) Adding poly (adipic acid)/butylene terephthalate into the dispersion liquid obtained in the step (1) and stirring to obtain a mixed liquid;

(3) Forming a film from the mixed solution to obtain the PU/PBAT composite film;

preferably, the organic solvent of step (1) comprises dichloromethane.

Preferably, the mass percentage of the polyurethane emulsion in the dispersion liquid in the step (1) is 0.6-3%, for example 0.6%, 0.8%, 1%, 1.2%, 1.5%, 2%, 2.3%, 2.5%, 2.8% or 3%.

Preferably, the stirring time in the step (2) is 10-20 h, for example 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h or 20h, etc.

Preferably, the film forming method comprises drying the film.

In a third aspect, the present invention provides the use of a PU/PBAT composite film according to the first aspect as a food packaging material.

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

The PU/PBAT composite film comprises polyurethane emulsion and polybutylene adipate/terephthalate, wherein the polyurethane emulsion comprises polyalcohol, isocyanate, a catalyst, a hydrophilic chain extender, gallic acid, a structural chain extender and a salifying agent, and the gallic acid is introduced into the polyurethane emulsion as the raw material and then is blended with the polybutylene adipate/terephthalate, so that the oxidation resistance of the PU/PBAT composite film can be effectively improved, and excellent mechanical properties and hydrophobic properties can be maintained.

Drawings

FIG. 1 is a FT-IR spectrum of a PU emulsion provided in preparation examples 1-2.

Detailed Description

The technical scheme of the invention is further described by the following specific embodiments. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.

Unless otherwise specified, the raw materials involved in the following embodiments are all conventional materials in the art and are all commercially available, and in particular, part of the raw material information involved in the following embodiments is as follows:

(1) Polytetrahydrofuran with a number average molecular weight of 1000, purchased from Adamas-Beta under the trade name 41565CB;

(2) PBAT, available from constant force Conhui New Material technology Co., ltd, brand KHB21AP11;

(3) Polylactic acid, PLA, available from Nature works, U.S. under the trade designation 4060D.

Preparation example 1

A PU emulsion is prepared by adding 3.99mmoL polytetrahydrofuran and 10.00mmoL isophorone diisocyanate into a 250mL three-neck flask, placing in an 80 ℃ oil bath for heating and pre-polymerizing for 1h, then adding 1.82 mmole of 2, 2-bis (hydroxymethyl) propionic acid and 2 drops (about 0.031 mmol) of stannous octoate for continuous reaction for 1h, then adding 0.57mmoL gallic acid and 1.62 mmole of 1, 4-butanediol for continuous reaction for 2h, adjusting the temperature to 40 ℃, adding 1.82mmoL triethylamine for neutralization reaction for 0.5h when the mixture is cooled to the set temperature, and observing in the steps, adding 2mL of acetone for regulating the viscosity of the system if the system viscosity is found to become large, namely the rotor rotation speed is reduced in the reaction process, and adding about 10mL of acetone in total in the whole reaction process to obtain the PU emulsion.

Preparation example 2

A PU emulsion is prepared by adding 3.99mmoL polytetrahydrofuran and 10.00mmoL isophorone diisocyanate into a 250mL three-neck flask, placing in an 80 ℃ oil bath kettle for heating and pre-polymerizing for 1h, then adding 2.36 mmole of 2, 2-bis (hydroxymethyl) propionic acid and 2 drops (about 0.031 mmol) of stannous octoate for continuous reaction for 1h, then adding 0.74mmoL gallic acid and 2.10 mmole of 1, 4-butanediol for continuous reaction for 2h, adjusting the temperature to 40 ℃, adding 2.36mmoL triethylamine for neutralization reaction (0.5) for h when the mixture is cooled to the set temperature, and observing in the steps, if the viscosity of the system is found to be increased, namely that the rotor rotation speed is reduced during the reaction, adding 2mL of acetone for regulating the viscosity of the system, and adding the total of acetone to be about 10mL during the whole reaction, thereby obtaining the PU emulsion.

Comparative preparation example 1

A PU emulsion is prepared by adding 2.98mmoL polytetrahydrofuran and 10.00mmoL isophorone diisocyanate into a 250mL three-neck flask, heating and pre-polymerizing for 1h in an 80 ℃ oil bath, then adding 2.15mmoL 2, 2-bis (hydroxymethyl) propionic acid and 2 drops (about 0.031 mmol) of stannous octoate for further reaction for 1h, adding 3.2mmoL 1, 4-butanediol for further reaction for 2h, adjusting the temperature to 40 ℃, adding 2.15mmoL triethylamine for neutralization reaction for 0.5h when the mixture is cooled to the set temperature, and adding 2mL acetone for regulating the viscosity of the system if the system viscosity is found to become large, namely the rotor rotation speed is reduced in the reaction process, and adding about 10mL of acetone in total in the whole reaction process.

Example 1

The PU/PBAT composite film comprises PU emulsion (preparation example 1) and PBAT with the mass ratio of 10:90;

the preparation method of the PU/PBAT composite film comprises the following steps:

(1) Adding the PU emulsion provided in the preparation example 1 into dichloromethane, and stirring for 1h to obtain a dispersion liquid with the mass percent of the PU emulsion being 0.67%;

(2) Adding PBAT into the dispersion liquid in the step (1), and stirring for 12 hours at the rotating speed of 600rpm to obtain a mixed liquid;

(3) Pouring the mixed solution prepared in the step (2) into a glass vessel, standing overnight at room temperature, and then placing into a 40 ℃ oven to volatilize the residual solvent to obtain the PU/PBAT composite film.

Example 2

A PU/PBAT composite film was different from example 1 in that the PU emulsion provided in preparation example 2 was used in place of the PU emulsion provided in preparation example 1, and the other matters, amounts and preparation methods were the same as those of example 1.

Example 3

The PU/PBAT composite film is different from example 1 in that the mass ratio of PU emulsion to PBAT is 20:80, and other substances, the dosage and the preparation method are the same as example 1.

Example 4

The PU/PBAT composite film is different from example 1 in that the mass ratio of PU emulsion to PBAT is 30:70, and other substances, the dosage and the preparation method are the same as example 1.

Example 5

The PU/PBAT composite film is different from example 1 in that the mass ratio of PU emulsion to PBAT is 40:60, and other materials, the dosage and the preparation method are the same as example 1.

Example 6

The PU/PBAT composite film is different from example 1 in that the mass ratio of PU emulsion to PBAT is 60:40, and other materials, the dosage and the preparation method are the same as example 1.

Example 7

The PU/PBAT composite film is different from example 1 in that the mass ratio of PU emulsion to PBAT is 5:95, and other materials, the dosage and the preparation method are the same as example 1.

Comparative example 1

A PBAT film is prepared through adding PBAT into dichloromethane to obtain dispersion liquid with mass percentage of 6.7%, pouring the obtained dispersion liquid into a glass dish, standing overnight at room temperature, and volatilizing residual solvent in a 40 ℃ oven.

Comparative example 2

A PLA/PBAT composite film is different from example 1 in that the PU emulsion is replaced by PLA with equal quality, and other substances, the dosage and the preparation method are the same as those of example 1.

Comparative example 3

A PU/PBAT composite film was different from example 1 in that the PU emulsion provided in preparation example 1 was replaced with the PU emulsion provided in preparation example 1 by the same mass as that of comparative preparation example 1, and the other matters, amounts and preparation methods were the same as those of example 1.

Structural test:

testing the PU emulsion provided in preparation examples 1-2 by adopting an FT-IR spectrum tester, wherein the FT-IR spectrum chart of the PU emulsion provided in preparation examples 1-2 is shown in figure 1;

As can be seen from FIG. 1, since the preparation materials of preparation examples 1 and 2 were the same, except that the amounts of the respective materials were different, wherein the contents of 2, 2-bis (hydroxymethyl) propionic acid, 1, 4-butanediol and gallic acid were fixed values, 5wt%, 3wt% and 2wt% of the emulsion, respectively, the intensities of the characteristic absorption peaks were different from each other in FIG. 1, but the peak positions were substantially identical, wherein the absorption peak was N-H stretching vibration at 3300cm ^-1, the absorption peak was C=O characteristic absorption peak at 1710cm ^-1 and the C-O stretching vibration peak at around 1300cm ^-1, indicating that the isocyanate and polyol were sufficiently reacted in preparation examples 1 to 2, the absorption peak at 1530cm ^-1 was due to the stretching vibration of the C-C bond in the aromatic ring, and the characteristic absorption peak at 1100cm ^-1 was due to the C-H bending vibration on the aromatic ring, which was provided by gallic acid, proving that gallic acid had been successfully incorporated into the structure of the PU emulsion.

Performance test:

(1) Elongation at break, tensile Strength the film was cut into 2X 10mm dumbbell-shaped samples and tested according to GB/T13022-1991 at 25℃ambient temperature and 70% relative humidity, the mechanical properties of the composite film were determined by measuring tensile strength, elongation at break and modulus of elasticity, the tensile rate was 10mm/min, and the measurement result was an average of 3 experimental results.

(2) The antioxidation efficiency is that 500mg of sample film is soaked in 5mL of ethanol for 24 hours, 2mL of soaking solution is added into 2mL of 40mg/L DHPP solution, the reaction is kept stand at a dark place for 1 hour, the absorbance (Ai) of the reaction solution at 517nm is detected, pure PBAT is used as a reference (A0), and the antioxidation efficiency of the composite film is calculated according to a formula (1).

(3) Water contact angle test the composite material is subjected to water contact angle by adopting an optical contact angle measuring instrument (OCA 40), and the test is carried out at the test environment temperature of 25 ℃ and the average value of three measurement results is taken.

The films provided in examples 1 to 7 and comparative examples 1 to 3 were tested according to the above test methods, and the test results are shown in table 1:

TABLE 1

From the data in table 1, it can be seen that:

(1) The PU/PBAT composite film provided in examples 1-5 has a tensile stress of not less than 10.32MPa, an elongation at break of not less than 578%, an antioxidation efficiency of not less than 10%, a water contact angle of not less than 83.83 DEG, and excellent mechanical properties, antioxidation properties and hydrophobic properties.

(2) As is clear from the comparison between examples 1, 3-7 and comparative example 1, the mechanical properties of the material are deteriorated by introducing the PU emulsion into the PBAT, because the compatibility between the PU emulsion and the PBAT is poor, and phase separation is easy to occur between the two phases, but the oxidation resistance and the water contact angle of the material are improved by introducing the PU emulsion, because the PU emulsion contains gallic acid component, the excellent oxidation resistance of the material can be endowed, and the oxidation resistance efficiency is improved along with the increase of the content of the PU emulsion, and the unreacted complete isocyanate group in the PU emulsion reacts with the terminal hydroxyl of the PBAT molecular chain to enhance the hydrophobic property of the material, but the content of the PU emulsion reaches 30wt% (example 4), the reacted terminal hydroxyl in the PBAT tends to be saturated, the hydrophilic soft segment in the PU is enhanced, and the hydrophobicity of the material is reduced;

(3) As can be seen from the comparison of the example 1 and the comparative example 2, the mechanical properties of the PU/PBAT composite film are far better than those of the PLA/PBAT composite film by the blend materials with the same proportion, which shows the superiority of the PU/PBAT blend material.

The applicant states that the present invention is described by the above examples as a PU/PBAT composite film and a method for preparing the same and applications thereof, but the present invention is not limited to the above process steps, i.e. it does not mean that the present invention must be implemented by relying on the above process steps. It should be apparent to those skilled in the art that any modification of the present invention, equivalent substitution of selected raw materials, addition of auxiliary components, selection of specific modes, etc. fall within the scope of the present invention and the scope of disclosure.

Claims (10)

1. The PU/PBAT composite film is characterized in that the PU/PBAT composite film comprises polyurethane emulsion and polybutylene adipate/terephthalate;

The raw materials of the polyurethane emulsion comprise polyalcohol, isocyanate, catalyst, hydrophilic chain extender, gallic acid, structural chain extender and salifying agent.

2. The PU/PBAT composite film according to claim 1, wherein the mass ratio of the polyurethane emulsion to the polybutylene adipate/terephthalate is (10-50): (50-90), preferably (20-30): (70-80).

3. The PU/PBAT composite film according to claim 1 or 2, wherein the polyol, isocyanate, hydrophilic chain extender, gallic acid, structural chain extender and salt former have a molar ratio of (2.5-4.5): 10 (1.5-2.5): 0.5-0.8): 1.5-3.5): 1.5-2.5.

4. The PU/PBAT composite film according to any one of claims 1 to 3, wherein the polyol comprises any one or a combination of at least two of polytetrahydrofuran, castor oil, or polyethylene glycol;

Preferably, the isocyanate comprises any one or a combination of at least two of isophorone diisocyanate, hexamethylene diisocyanate, 4' -dicyclohexylmethane diisocyanate, diphenylmethane diisocyanate or toluene diisocyanate;

Preferably, the hydrophilic chain extender comprises 2, 2-bis (hydroxymethyl) propionic acid and/or 2, 2-dimethylolbutyric acid;

Preferably, the structural chain extender comprises 1, 4-butanediol and/or 1, 6-hexanediol;

preferably, the salifying agent comprises any one or a combination of at least two of triethylamine, sodium hydroxide or hydrochloric acid;

preferably, the amount of the catalyst is 0.01-0.04 mmol in terms of 1mmol of the isocyanate;

preferably, the catalyst comprises any one or a combination of at least two of stannous octoate, dibutyltin dilaurate or diethyl tin dilaurate;

preferably, the raw materials of the polyurethane emulsion further comprise a solvent;

Preferably, the consumption of the solvent is 1-3 mL in terms of the consumption of the polyol being 1 mmol;

preferably, the solvent comprises acetone.

5. The PU/PBAT composite film according to any one of claims 1 to 4, wherein the polyurethane emulsion is obtained by reacting a polyol, an isocyanate, a hydrophilic chain extender, gallic acid, a structural chain extender and a salifying agent;

Preferably, a solvent is added during the reaction to adjust the viscosity of the reactants;

Preferably, the reaction specifically comprises the steps of pre-polymerizing polyol and isocyanate for 0.5-2 hours at 70-100 ℃, adding a catalyst and a hydrophilic chain extender for chain extension for 0.5-2 hours, adding gallic acid and a structural chain extender for chain extension for 1-4 hours, cooling to 30-50 ℃, adding a salifying agent for neutralization for 0.3-1 hour, and adding a solvent in the steps to adjust the viscosity of a reactant, thereby obtaining the polyurethane emulsion.

6. The method for preparing the PU/PBAT composite film as claimed in any one of claims 1 to 5, which is characterized in that the method comprises the steps of mixing polyurethane emulsion and polybutylene adipate/terephthalate in an organic solvent, and forming a film to obtain the PU/PBAT composite film.

7. The preparation method according to claim 6, characterized in that the preparation method comprises the steps of:

(1) Dissolving polyurethane emulsion in an organic solvent to obtain a dispersion liquid;

(2) Adding poly (adipic acid)/butylene terephthalate into the dispersion liquid obtained in the step (1) and stirring to obtain a mixed liquid;

(3) And (3) forming a film from the mixed solution to obtain the PU/PBAT composite film.

8. The method of claim 7, wherein the organic solvent of step (1) comprises methylene chloride;

preferably, the mass percentage of the polyurethane emulsion in the dispersion liquid in the step (1) is 0.6-3%;

preferably, the stirring time in the step (2) is 10-20 hours.

9. The method of any one of claims 6 to 8, wherein the film forming method comprises drying to form a film.

10. Use of the PU/PBAT composite film according to any one of claims 1 to 6 as a food packaging material.