Composite material for aluminum foil bag and preparation method thereof

Abstract

The invention discloses a composite material for an aluminum foil bag and a preparation method thereof, belonging to the technical field of packaging material preparation. The composite material comprises an aluminum foil, wherein at least one layer of plastic film is compounded on both sides of the aluminum foil, and the plastic film compounded on one side or both sides of the aluminum foil is compounded by a polyester resin matrix modified by methyl maleic anhydride and linear polyethyleneimine. The invention reduces the hardness of the polyester film while retaining the high strength and wear resistance of the polyester film through modification and compounding based on the polyester resin.

Description

Technical Field

[0001] The invention relates to the technical field of packaging material preparation, and in particular to a composite material for an aluminum foil bag and a preparation method thereof. Background Art

[0002] Aluminum foil bags are a composite packaging material made of aluminum foil and plastic film through a composite process. They have certain toughness and flexibility. Aluminum foil bags have very good barrier properties and can effectively prevent the intrusion of external substances such as oxygen, moisture, and microorganisms, protecting the quality and safety of items in the bag.

[0003] Generally speaking, aluminum foil bag composite materials mainly include outer layer, middle layer and inner layer. The inner layer is usually made of materials such as polyethylene (PE) or polypropylene (PP) with good heat sealing properties. These materials have good sealing properties and can ensure the tightness of the packaging bag to prevent product leakage. At the same time, the inner layer material also has good water resistance and oil resistance, and can adapt to different environmental conditions; the middle layer is the core part of the aluminum foil bag composite material, usually made of aluminum foil (Aluminum Aluminum foil has good barrier properties and can effectively block external factors such as air, water vapor and light to ensure the quality and stability of the product in the package. At the same time, aluminum foil also has good ductility and flexibility, which can adapt to different packaging needs. The outer layer usually uses materials such as polyester (PET) or nylon (PA), which have high strength, wear resistance and puncture resistance. In addition, they have good printing properties and can be printed with various patterns and texts to meet the packaging needs of different products. However, the high-strength outer layer also causes the composite material to have poor flexibility, which is difficult to match well with the flexibility of aluminum foil. After being compounded with aluminum foil, the bending in actual packaging use can easily cause the outer plastic to bubble, or even peel off and cause packaging failure. Summary of the invention

[0004] In view of the above problems, the present invention provides a composite material for aluminum foil bags and a preparation method thereof.

[0005] The purpose of the present invention is achieved by the following technical solutions:

[0006] A composite material for an aluminum foil bag comprises an aluminum foil, wherein at least one layer of plastic film is laminated on both sides of the aluminum foil, and a method for preparing the plastic film laminated on one or both sides of the aluminum foil comprises the following steps:

[0007] (1) Preparation of resin matrix

[0008] Weigh phthalic anhydride and dissolve it in toluene solvent, add a catalyst and 1,2-cyclohexanediol, stir and mix thoroughly, then add tert-butyl glycidyl ether, stir and mix again, pass nitrogen to deoxygenate, heat to 50-70° C. under a protective atmosphere, keep stirring and react for 24-48 hours, cool after the reaction is completed, evaporate the solvent under reduced pressure, add tetrahydrofuran to dissolve, precipitate in cyclohexane, wash and dry to obtain a resin matrix;

[0009] (2) Resin modification

[0010] Weigh 2-propionic acid-3-methylmaleic anhydride and dissolve it in dichloromethane, add oxalyl chloride and dimethylformamide under ice-water bath conditions, stir and mix thoroughly, and then stir and react at room temperature for 0.5-1h. After the reaction is completed, evaporate the solvent, add the tetrahydrofuran solution of the resin matrix, add pyridine as a catalyst, stir and react at room temperature for 2-3h, after the reaction is completed, add an equal volume of saturated ammonium chloride solution to dilute the reaction system, separate the layers, take the organic phase, concentrate under reduced pressure, precipitate in ether, wash, and dry to obtain a modified resin;

[0011] (3) Resin composite

[0012] The modified resin and linear polyethyleneimine are mixed and dissolved in tetrahydrofuran, and then dried after coating to obtain the plastic film.

[0013] In some preferred embodiments, the mass ratio of the phthalic anhydride to the catalyst, the 1,2-cyclohexanediol, and the tert-butyl glycidyl ether in step (1) is 10:(1-1.2):(0.8-0.9):(10-11).

[0014] In some preferred embodiments, the catalyst is a mixture of Salen metal chromium chloride coordination compound and bis(triphenylphosphine)ammonium chloride in a molar ratio of 1:1.

[0015] In some preferred embodiments, the mass ratio of the 2-propionic acid-3-methylmaleic anhydride to the oxalyl chloride, the dimethylformamide, the resin matrix, and the pyridine in step (2) is (0.69-0.72): (0.92-0.98): (0.003-0.005): 10: (0.003-0.005).

[0016] In some preferred embodiments, the mass ratio of the modified resin to the linear polyethyleneimine in step (3) is (5-10):1.

[0017] In some preferred embodiments, the number average molecular weight of the linear polyethyleneimine is 1000-2000.

[0018] In some preferred embodiments, one side of the aluminum foil is a polyethylene plastic film or a polypropylene plastic film.

[0019] In some preferred embodiments, a nylon film layer is further provided between the aluminum foil and the polyethylene plastic film or the polypropylene plastic film.

[0020] In some preferred embodiments, the thickness of the aluminum foil is 5-20 μm, and the thickness of the plastic film is 10-80 μm.

[0021] Another aspect of the present invention is to provide a method for preparing the composite material for the aluminum foil bag, specifically, the plastic film is compounded in sequence according to the interlayer design to obtain the composite material, and the compounding method is coating and drying, gluing, hot pressing or laminating.

[0022] The beneficial effects of the present invention are:

[0023] Aiming at the problem of mismatched flexibility between the plastic film of the aluminum foil bag composite material and the aluminum foil in the prior art, the present invention reduces the hardness of the polyester film by modified composite on the basis of polyester resin while retaining the high strength and wear resistance. Specifically, the present invention uses phthalic anhydride and tert-butyl glycidyl ether as raw materials, obtains the polyester material by ring-opening copolymerization, reduces the rigidity of the polymer by introducing tert-butyl groups into the side chains, reduces the polymerization degree of the polyester chain by reducing the polymerization reaction time, and then caps the end with chlorinated methyl maleic anhydride, and finally cross-links with a straight-chain secondary amine, polyethyleneimine, and then introduces tertiary maleic acid amide into the cross-linking system, so that it has the characteristics of both polyester and polyamide, thereby improving its flexibility while maintaining high strength and wear resistance. At the same time, the tertiary maleic acid amide with reversible bond breaking performance can be used in strong acid (H + The concentration is greater than 2 mol / L) and hydrolyzes it to achieve simple decomposition and recycling of discarded aluminum foil bags. DETAILED DESCRIPTION

[0024] The present invention is further described in conjunction with the following examples. Example 1

[0025] A composite material for an aluminum foil bag, wherein the interlayer components are modified polyester film, aluminum foil and polyethylene film in sequence, the composite material is formed by hot pressing, the thickness of the aluminum foil is 8 μm, the thickness of the modified polyester film is 24 μm, and the thickness of the polyethylene film is 28 μm, wherein the preparation method of the modified polyester film comprises the following steps:

[0026] (1) Preparation of resin matrix

[0027] Weigh phthalic anhydride and dissolve it in toluene solvent, add a catalyst and 1,2-cyclohexanediol, stir and mix thoroughly, then add tert-butyl glycidyl ether, stir and mix again, pass nitrogen to deoxygenate, heat to 60° C. under a protective atmosphere, keep stirring and react for 30 hours, cool after the reaction is completed, evaporate the solvent under reduced pressure, add tetrahydrofuran to dissolve, precipitate in cyclohexane, wash and dry to obtain a resin matrix;

[0028] The catalyst is a mixture of Salen metal chromium chloride coordination compound and bis(triphenylphosphine)ammonium chloride, the molar ratio of which is 1:1;

[0029] Wherein, the mass ratio of the phthalic anhydride to the catalyst, the 1,2-cyclohexanediol, and the tert-butyl glycidyl ether is 10:1.1:0.85:10.4;

[0030] (2) Resin modification

[0031] Weigh 2-propionic acid-3-methylmaleic anhydride and dissolve it in dichloromethane, add oxalyl chloride and dimethylformamide under ice-water bath conditions, stir and mix thoroughly, and then stir and react at room temperature for 0.5h. After the reaction is completed, evaporate the solvent, add the tetrahydrofuran solution of the resin matrix, add pyridine as a catalyst, and stir and react at room temperature for 2h. After the reaction is completed, add an equal volume of saturated ammonium chloride solution to dilute the reaction system, separate the layers, take the organic phase, concentrate under reduced pressure, precipitate in ether, wash, and dry to obtain a modified resin;

[0032] Wherein, the mass ratio of the 2-propionic acid-3-methylmaleic anhydride to the oxalyl chloride, the dimethylformamide, the resin matrix, and the pyridine is 0.7:0.95:0.004:10:0.004;

[0033] (3) Resin composite

[0034] The modified resin and linear polyethyleneimine are mixed and dissolved in tetrahydrofuran, and then dried after coating to obtain the plastic film;

[0035] The number average molecular weight of the linear polyethyleneimine is 1800, and the mass ratio of the modified resin to the linear polyethyleneimine is 7.3:1. Example 2

[0036] A composite material for an aluminum foil bag, wherein the interlayer components are modified polyester film, aluminum foil and polyethylene film in sequence, the composite material is formed by hot pressing, the thickness of the aluminum foil is 8 μm, the thickness of the modified polyester film is 24 μm, and the thickness of the polyethylene film is 28 μm, wherein the preparation method of the modified polyester film comprises the following steps:

[0037] (1) Preparation of resin matrix

[0038] Weigh phthalic anhydride and dissolve it in toluene solvent, add a catalyst and 1,2-cyclohexanediol, stir and mix thoroughly, then add propylene oxide, stir and mix again, pass nitrogen to deoxygenate, heat to 60° C. under a protective atmosphere, keep stirring and react for 30 hours, cool after the reaction is completed, evaporate the solvent under reduced pressure, add tetrahydrofuran to dissolve, precipitate in cyclohexane, wash and dry to obtain a resin matrix;

[0039] The catalyst is a mixture of Salen metal chromium chloride coordination compound and bis(triphenylphosphine)ammonium chloride, the molar ratio of which is 1:1;

[0040] Wherein, the mass ratio of the phthalic anhydride to the catalyst, the 1,2-cyclohexanediol, and the propylene oxide is 10:1.1:0.85:10.4;

[0041] (2) Resin modification

[0042] Weigh 2-propionic acid-3-methylmaleic anhydride and dissolve it in dichloromethane, add oxalyl chloride and dimethylformamide under ice-water bath conditions, stir and mix thoroughly, and then stir and react at room temperature for 0.5h. After the reaction is completed, evaporate the solvent, add the tetrahydrofuran solution of the resin matrix, add pyridine as a catalyst, and stir and react at room temperature for 2h. After the reaction is completed, add an equal volume of saturated ammonium chloride solution to dilute the reaction system, separate the layers, take the organic phase, concentrate under reduced pressure, precipitate in ether, wash, and dry to obtain a modified resin;

[0043] Wherein, the mass ratio of the 2-propionic acid-3-methylmaleic anhydride to the oxalyl chloride, the dimethylformamide, the resin matrix, and the pyridine is 0.7:0.95:0.004:10:0.004;

[0044] (3) Resin composite

[0045] The modified resin and linear polyethyleneimine are mixed and dissolved in tetrahydrofuran, and then dried after coating to obtain the plastic film;

[0046] The number average molecular weight of the linear polyethyleneimine is 1800, and the mass ratio of the modified resin to the linear polyethyleneimine is 7.3:1. Example 3

[0047] A composite material for an aluminum foil bag, wherein the interlayer components are modified polyester film, aluminum foil and polyethylene film in sequence, the composite material is formed by hot pressing, the thickness of the aluminum foil is 8 μm, the thickness of the modified polyester film is 24 μm, and the thickness of the polyethylene film is 28 μm, wherein the preparation method of the modified polyester film comprises the following steps:

[0048] (1) Preparation of resin matrix

[0049] Weigh phthalic anhydride and dissolve it in toluene solvent, add a catalyst and 1,2-cyclohexanediol, stir and mix thoroughly, then add tert-butyl glycidyl ether, stir and mix again, pass nitrogen to deoxygenate, heat to 60° C. under a protective atmosphere, keep stirring and react for 30 hours, cool after the reaction is completed, evaporate the solvent under reduced pressure, add tetrahydrofuran to dissolve, precipitate in cyclohexane, wash and dry to obtain a resin matrix;

[0050] The catalyst is a mixture of Salen metal chromium chloride coordination compound and bis(triphenylphosphine)ammonium chloride, the molar ratio of which is 1:1;

[0051] Wherein, the mass ratio of the phthalic anhydride to the catalyst, the 1,2-cyclohexanediol, and the tert-butyl glycidyl ether is 10:1.1:0.85:10.4;

[0052] (2) Resin modification

[0053] Weigh 2-propionic acid-3-methylmaleic anhydride and dissolve it in dichloromethane, add oxalyl chloride and dimethylformamide under ice-water bath conditions, stir and mix thoroughly, and then stir and react at room temperature for 0.5h. After the reaction is completed, evaporate the solvent, add the tetrahydrofuran solution of the resin matrix, add pyridine as a catalyst, and stir and react at room temperature for 2h. After the reaction is completed, add an equal volume of saturated ammonium chloride solution to dilute the reaction system, separate the layers, take the organic phase, concentrate under reduced pressure, precipitate in ether, wash, and dry to obtain a modified resin;

[0054] Wherein, the mass ratio of the 2-propionic acid-3-methylmaleic anhydride to the oxalyl chloride, the dimethylformamide, the resin matrix, and the pyridine is 0.7:0.95:0.004:10:0.004;

[0055] (3) Resin composite

[0056] The modified resin is dissolved in tetrahydrofuran, coated and then dried to obtain the plastic film. Example 4

[0057] A composite material for an aluminum foil bag, wherein the interlayer components are modified polyester film, aluminum foil and polyethylene film in sequence, the composite material is formed by hot pressing, the thickness of the aluminum foil is 8 μm, the thickness of the modified polyester film is 24 μm, and the thickness of the polyethylene film is 28 μm, wherein the preparation method of the modified polyester film comprises the following steps:

[0058] (1) Preparation of resin matrix

[0059] Weigh phthalic anhydride and dissolve it in toluene solvent, add a catalyst and 1,2-cyclohexanediol, stir and mix thoroughly, then add tert-butyl glycidyl ether, stir and mix again, pass nitrogen to deoxygenate, heat to 60° C. under a protective atmosphere, keep stirring and react for 30 hours, cool after the reaction is completed, evaporate the solvent under reduced pressure, add tetrahydrofuran to dissolve, precipitate in cyclohexane, wash and dry to obtain a resin matrix;

[0060] The catalyst is a mixture of Salen metal chromium chloride coordination compound and bis(triphenylphosphine)ammonium chloride, the molar ratio of which is 1:1;

[0061] Wherein, the mass ratio of the phthalic anhydride to the catalyst, the 1,2-cyclohexanediol, and the tert-butyl glycidyl ether is 10:1.1:0.85:10.4;

[0062] (2) Resin composite

[0063] The resin matrix and linear polyethyleneimine are mixed and dissolved in tetrahydrofuran, and then dried after coating to obtain the plastic film;

[0064] The number average molecular weight of the linear polyethyleneimine is 1800, and the mass ratio of the resin matrix to the linear polyethyleneimine is 7.3:1. Example 5

[0065] A composite material for an aluminum foil bag, wherein the interlayer components are modified polyester film, aluminum foil and polyethylene film in sequence, the composite material is formed by hot pressing, the thickness of the aluminum foil is 8 μm, the thickness of the modified polyester film is 24 μm, and the thickness of the polyethylene film is 28 μm, wherein the preparation method of the modified polyester film comprises the following steps:

[0066] (1) Preparation of resin matrix

[0067] Weigh phthalic anhydride and dissolve it in toluene solvent, add a catalyst and 1,2-cyclohexanediol, stir and mix thoroughly, then add tert-butyl glycidyl ether, stir and mix again, pass nitrogen to deoxygenate, heat to 60° C. under a protective atmosphere, keep stirring and react for 30 hours, cool after the reaction is completed, evaporate the solvent under reduced pressure, add tetrahydrofuran to dissolve, precipitate in cyclohexane, wash and dry to obtain a resin matrix;

[0068] The catalyst is a mixture of Salen metal chromium chloride coordination compound and bis(triphenylphosphine)ammonium chloride, the molar ratio of which is 1:1;

[0069] Wherein, the mass ratio of the phthalic anhydride to the catalyst, the 1,2-cyclohexanediol, and the tert-butyl glycidyl ether is 10:1.1:0.85:10.4;

[0070] (2) Film preparation

[0071] The resin matrix is ​​dissolved in tetrahydrofuran, and the plastic film is prepared by coating and drying.

[0072] The folding resistance and abrasion resistance of the modified polyester film surface of the aluminum foil bag described in Examples 1-5 were measured, wherein the folding resistance was folded 50 times with reference to GB / T 457-2008, and the coating condition was observed; the abrasion resistance test method was to select 1500-grit sandpaper, pull and wear the coating at a distance of 350 mm at a load of 200g, and wear it 15 times in total, and measure the remaining thickness of the plastic film at the worn part; the measurement results are shown in the following table.

[0073]

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A composite material for an aluminum foil bag, comprising aluminum foil, characterized in that: The two sides of the aluminum foil are respectively laminated with at least one layer of plastic film, and the preparation method of the plastic film laminated on one or both sides of the aluminum foil comprises the following steps: (1) Preparation of resin matrix Weigh phthalic anhydride and dissolve it in toluene solvent, add a catalyst and 1,2-cyclohexanediol, stir and mix thoroughly, then add tert-butyl glycidyl ether, stir and mix again, pass nitrogen to deoxygenate, heat to 50-70° C. under a protective atmosphere, keep stirring and react for 24-48 hours, cool after the reaction is completed, evaporate the solvent under reduced pressure, add tetrahydrofuran to dissolve, precipitate in cyclohexane, wash and dry to obtain a resin matrix; (2) Resin modification Weigh 2-propionic acid-3-methylmaleic anhydride and dissolve it in dichloromethane, add oxalyl chloride and dimethylformamide under ice-water bath conditions, stir and mix thoroughly, and then stir and react at room temperature for 0.5-1h. After the reaction is completed, evaporate the solvent, add the tetrahydrofuran solution of the resin matrix, add pyridine as a catalyst, stir and react at room temperature for 2-3h, after the reaction is completed, add an equal volume of saturated ammonium chloride solution to dilute the reaction system, separate the layers, take the organic phase, concentrate under reduced pressure, precipitate in ether, wash, and dry to obtain a modified resin; (3) Resin composite The modified resin and linear polyethyleneimine are mixed and dissolved in tetrahydrofuran, and then dried after coating to obtain the plastic film; In step (1), the mass ratio of the phthalic anhydride to the catalyst, the 1,2-cyclohexanediol, and the tert-butyl glycidyl ether is 10:(1-1.2):(0.8-0.9):(10-11); The catalyst is a mixture of Salen metal chromium chloride coordination compound and bis(triphenylphosphine)ammonium chloride, the molar ratio of which is 1:1; The mass ratio of the 2-propionic acid-3-methylmaleic anhydride to the oxalyl chloride, the dimethylformamide, the resin matrix, and the pyridine in step (2) is (0.69-0.72): (0.92-0.98): (0.003-0.005): 10: (0.003-0.005); The mass ratio of the modified resin to the linear polyethyleneimine in step (3) is (5-10):

1.

2. The composite material for aluminum foil bags according to claim 1, characterized in that: The number average molecular weight of the linear polyethyleneimine is 1000-2000.

3. The composite material for aluminum foil bags according to claim 1, characterized in that: One side of the aluminum foil is a polyethylene plastic film or a polypropylene plastic film.

4. The composite material for aluminum foil bags according to claim 3, characterized in that: A nylon film layer is also arranged between the aluminum foil and the polyethylene plastic film or the polypropylene plastic film.

5. The composite material for aluminum foil bags according to claim 1, characterized in that: The thickness of the aluminum foil is 5-20 μm, and the thickness of the plastic film is 10-80 μm.

6. The method for preparing a composite material for aluminum foil bags according to any one of claims 1 to 5, characterized in that: The plastic film is compounded in sequence according to the interlayer design to obtain the product, and the compounding method is coating and drying, gluing, hot pressing or laminating.

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