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CN-122008601-A - Biodegradable barrier composite film and preparation method thereof

CN122008601ACN 122008601 ACN122008601 ACN 122008601ACN-122008601-A

Abstract

The invention provides a biodegradable barrier composite film and a preparation method thereof, and relates to the technical field of preparation of oxygen barrier master batches, preparation of water barrier master batches and coextrusion film forming; the preparation of the anti-oxygen layer master batch comprises the steps of mixing PBAT, an alkaline catalyst and diisocyanate, carrying out melt reaction at 150-220 ℃ to enable hydroxyl end groups of the PBAT to react with isocyanate to obtain a PBAT prepolymer with isocyanate groups at the tail ends, then adding caprolactam and a polymerization catalyst thereof into a reaction system, carrying out melt polymerization at 220-260 ℃ to enable the caprolactam to carry out ring-opening polymerization under the initiation of the isocyanate groups at the tail ends of the PBAT prepolymer, and granulating after the reaction is finished to obtain the PBAT-b-PA segmented copolymer master batch, wherein the preparation of the anti-oxygen layer master batch comprises the steps of mixing PBAT and hydrophobically modified PBAT, carrying out melt extrusion granulation to obtain the anti-oxygen layer master batch. The invention has the advantages that the low-cost PBAT is taken as the main raw material, and the unity of barrier property, degradability and economy is realized through physical and chemical modification, so that the invention is easy for large-scale production.

Inventors

  • FAN ZHIJIAO

Assignees

  • 双志包装(佛山)有限公司

Dates

Publication Date
20260512
Application Date
20260205

Claims (10)

  1. 1. The preparation method of the biodegradable barrier composite film is characterized by comprising the following steps of: (1) Preparing an oxygen barrier master batch, namely mixing PBAT, an alkaline catalyst and diisocyanate, carrying out melt reaction at 150-220 ℃ to enable hydroxyl end groups of the PBAT to react with isocyanate to obtain a PBAT prepolymer with isocyanate groups at the tail ends, then adding caprolactam and a polymerization catalyst thereof into a reaction system, carrying out melt polymerization at 220-260 ℃ to enable the caprolactam to carry out ring-opening polymerization under the initiation of the isocyanate groups at the tail ends of the PBAT prepolymer, and granulating after the reaction is finished to obtain the PBAT-b-PA segmented copolymer master batch; (2) Preparing a water-resistant master batch, namely mixing PBAT and hydrophobically modified PBAT, and carrying out melt extrusion granulation to obtain the water-resistant master batch, wherein the hydrophobically modified PBAT is a product of grafting long-chain alkane with the carbon number of 1-30 on a PBAT molecular chain; (3) And (3) co-extrusion film forming, namely taking the waterproof layer master batch obtained in the step (2) as an outer layer raw material, taking the PBAT-b-PA master batch obtained in the step (1) as an intermediate layer raw material, putting the PBAT-b-PA master batch into multi-layer co-extrusion equipment together, and carrying out melt casting or blow molding and cooling at 200-250 ℃ to obtain the biodegradable barrier composite film with a three-layer structure.
  2. 2. The method according to claim 1, wherein in the step (1), the diisocyanate is isophorone diisocyanate, the basic catalyst is sodium hydroxide, and the polymerization catalyst of caprolactam is caprolactam sodium salt.
  3. 3. The production method according to claim 1 or 2, wherein in the step (1), 100 parts by mass of PBAT, 1 to 6 parts by mass of diisocyanate and 40 to 220 parts by mass of caprolactam are used.
  4. 4. The method according to claim 1, wherein the hydrophobically modified PBAT is used in an amount of 40 to 80 parts by weight based on 100 parts by weight of PBAT in step (2).
  5. 5. The method according to claim 1 or 4, wherein in the step (2), the long-chain alkane has 10 to 20 carbon atoms, and the hydrophobically modified PBAT is produced by graft-polymerizing stearyl acrylate in the presence of PBAT.
  6. 6. The preparation method of the waterproof layer master batch according to claim 1, wherein in the step (2), the mixed raw materials further comprise 0-10 parts by weight of filler and/or 0-5 parts by weight of functional additive, wherein the filler is at least one of calcium carbonate, talcum powder and montmorillonite, and the functional additive is at least one of antioxidant, ultraviolet absorber and opening agent.
  7. 7. The method according to claim 1, wherein in the step (3), the co-extrusion film forming process parameters are controlled so that the total thickness of the finally prepared composite film is 0.01-0.30mm, the total thickness of the two layers of the water-blocking layers is 60% -96% of the total thickness of the film, and the thickness of the oxygen-blocking layer is 4% -40% of the total thickness of the film.
  8. 8. The method according to any one of claims 1 to 7, wherein in step (3), the cooling temperature is 20 to 40 ℃.
  9. 9. A biodegradable barrier composite film, characterized in that it is directly obtained from the preparation process according to any one of claims 1 to 8.
  10. 10. The biodegradable barrier composite film according to claim 9, characterized in that said composite film comprises at least a first water-resistant layer, an oxygen-resistant layer and a second water-resistant layer, which are laminated in this order, said oxygen-resistant layer comprising a PBAT-b-PA block copolymer, said first water-resistant layer and said second water-resistant layer both comprising PBAT and hydrophobically modified PBAT; The first water-resistant layer and/or the second water-resistant layer also comprises 0-10 parts by weight of filler and/or 0-5 parts by weight of functional additive.

Description

Biodegradable barrier composite film and preparation method thereof Technical Field The invention belongs to the technical field of functional plastic composite films, and particularly relates to a biodegradable barrier composite film and a preparation method thereof. Background The barrier film is a functional film with lower water vapor and oxygen transmittance, is commonly used in the packaging field, can greatly inhibit the exchange of gas between the packaging content and the outside, has the effects of prolonging the shelf life of the packaging content, retaining the flavor of food and the like, and is widely applied to the fields of medicine, food, electronics and the like. The film is generally applied to quick-release products, is mostly disposable, and can be used for disposal, so that huge pressure is caused on environmental protection for a long time. The use of biodegradable materials to make barrier films is a two-way method. In the prior art, polyhydroxyalkanoate (PHA) and polypropylene carbonate (PPC) are generally selected as biodegradable materials for preparing the barrier film, wherein the polyhydroxyalkanoate has outstanding oxygen and carbon dioxide barrier properties, and the polypropylene carbonate (PPC) has excellent barrier effect on water vapor. However, the disadvantages of the two materials limit their application. For example, PHA has a narrow thermoplastic window and high processing difficulty, and is low in yield and high in price due to microbial fermentation at present, PPC has poor heat resistance and is easy to deform when heated, and packaging application requirements are difficult to meet. Therefore, how to prepare biodegradable barrier films by a simple and easy method remains a problem to be overcome. Disclosure of Invention The invention overcomes the defects in the prior art, provides a biodegradable barrier composite film and a preparation method thereof, uses low-cost PBAT as a main raw material, realizes the unification of barrier property, degradability and economy through physical and chemical modification, and is easy for large-scale production. A method for preparing a biodegradable barrier composite film, comprising the following steps: (1) Preparing an oxygen barrier master batch, namely mixing PBAT, an alkaline catalyst and diisocyanate, carrying out melt reaction at 150-220 ℃ to enable hydroxyl end groups of the PBAT to react with isocyanate to obtain a PBAT prepolymer with isocyanate groups at the tail ends, then adding caprolactam and a polymerization catalyst thereof into a reaction system, carrying out melt polymerization at 220-260 ℃ to enable the caprolactam to carry out ring-opening polymerization under the initiation of the isocyanate groups at the tail ends of the PBAT prepolymer, and granulating after the reaction is finished to obtain the PBAT-b-PA segmented copolymer master batch; (2) Preparing a water-resistant master batch, namely mixing PBAT and hydrophobically modified PBAT, and carrying out melt extrusion granulation to obtain the water-resistant master batch, wherein the hydrophobically modified PBAT is a product of grafting long-chain alkane with the carbon number of 1-30 on a PBAT molecular chain; (3) And (3) co-extrusion film forming, namely taking the waterproof layer master batch obtained in the step (2) as an outer layer raw material, taking the PBAT-b-PA master batch obtained in the step (1) as an intermediate layer raw material, putting the PBAT-b-PA master batch into multi-layer co-extrusion equipment together, and carrying out melt casting or blow molding and cooling at 200-250 ℃ to obtain the biodegradable barrier composite film with a three-layer structure. Further, in the step (1), the diisocyanate is isophorone diisocyanate, the basic catalyst is sodium hydroxide, and the polymerization catalyst of caprolactam is caprolactam sodium salt. Further, in the step (1), 100 parts by mass of the PBAT, 1 to 6 parts by mass of the diisocyanate and 40 to 220 parts by mass of the caprolactam are used. Further, in the step (2), the hydrophobically modified PBAT is used in an amount of 40 to 80 parts by weight based on 100 parts by weight of the PBAT. Still further, in the step (2), the long-chain alkane has 10 to 20 carbon atoms, and the hydrophobically modified PBAT is prepared by graft polymerizing stearyl acrylate in the presence of PBAT. In the step (2), when the water-resistant layer master batch is prepared, the mixed raw materials further comprise 0-10 parts by weight of filler and/or 0-5 parts by weight of functional additive, wherein the filler is at least one of calcium carbonate, talcum powder and montmorillonite, and the functional additive is at least one of antioxidant, ultraviolet absorber and opening agent. Further, in the step (3), the co-extrusion film forming process parameters are controlled so that the total thickness of the finally prepared composite film is 0.01-0.30mm, the total thickness of the two layers of the