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CN-121975063-A - High-barrier polyvinyl acetal resin, preparation method thereof, barrier film and application

CN121975063ACN 121975063 ACN121975063 ACN 121975063ACN-121975063-A

Abstract

The invention discloses a high-barrier polyvinyl acetal resin, a preparation method thereof, a barrier film and application thereof, and belongs to the technical field of high polymer materials. The preparation method takes polyvinyl alcohol with alcoholysis degree more than or equal to 95mol percent and polymerization degree of 600-1200 as a raw material, and prepares the high-barrier polyvinyl acetal resin through long/short chain aldehyde compound acetal reaction and polar rigid monomer grafting modification. The transmittance of the resin 15wt% alcohol solution is more than or equal to 90%, and the oxygen transmittance of the prepared 25 mu m film under standard environment is less than 10cm 3 /m 2 24h The adhesive force grade is less than or equal to 1 grade under 0.1 MPa. The invention also discloses a preparation process of the barrier film, which adopts the ethanol-acetone mixed solvent for low-temperature coating and drying, and has good film forming property. The resin and the film have excellent barrier property, alcohol solubility and flexibility, simple process and low cost, and can be widely applied to the fields of food and medicine packaging, electronic packaging, medical protection and the like.

Inventors

  • ZHOU YUJIE
  • YAN QI
  • WANG DAOLIANG
  • LIU WEI
  • WU ZHIFEI

Assignees

  • 安徽皖维先进功能膜材料研究院有限公司

Dates

Publication Date
20260505
Application Date
20260212

Claims (10)

  1. 1. The high-barrier polyvinyl acetal resin is characterized by meeting the following technical indexes: The light transmittance of the 15wt% alcohol solution at the wavelength of 550nm is more than or equal to 90%, the total content of acetoxy, vinyl alcohol and other grafted polar groups in the molecule is 35-55 mol%, wherein the content of acetoxy is less than or equal to 5mol%, the content of vinyl alcohol is less than or equal to 40mol%, and the content of other grafted polar groups is less than 10mol%; The content of hydroxyl in the resin is 20-40wt%, and the oxygen transmittance of the film with the thickness of 25 mu m prepared by the resin is less than 10cm measured under the conditions of the ambient temperature of 23+/-2 ℃ and the ambient humidity of 50+/-5 RH% 3 /m 2 24h 0.1MPa; After the film is coated on the surface of the substrate, the adhesive force grade evaluated by a cross-cut method is less than or equal to 1 grade.
  2. 2. A process for producing a high barrier polyvinyl acetal resin according to claim 1, which comprises the steps of: Step 1, preparing a polyvinyl alcohol solution, namely selecting a polyvinyl alcohol raw material with alcoholysis degree of more than or equal to 95mol% and polymerization degree of 600-1200, dissolving the polyvinyl alcohol raw material in deionized water to prepare a polyvinyl alcohol solution with concentration of 10-12 wt%, heating to 95 ℃, and stirring until the polyvinyl alcohol raw material is completely dissolved; Step 2, carrying out an acetalization reaction, namely cooling the polyvinyl alcohol solution to 5 ℃, adding an aldehyde mixture and acid, carrying out heat preservation for 30min, then raising the temperature to 40 ℃ at a temperature raising rate of 8 ℃ per hour, carrying out heat preservation reaction for 3h, and carrying out neutralization, filtration, washing and drying on a reaction product to obtain polyvinyl acetal resin powder, wherein the addition amount of the aldehyde mixture is 30-70% of the mass of the polyvinyl alcohol, the addition amount of the acid is 40% of the mass of the polyvinyl alcohol, and the aldehyde mixture is a compound system of long-chain aldehyde and short-chain aldehyde, and the mass ratio of the long-chain aldehyde to the short-chain aldehyde is more than or equal to 8:2; And 3, graft modification, namely dissolving the polyvinyl acetal resin powder in an organic solvent, adding a polar rigid monomer and an initiator, stirring and reacting for 3 hours at 70 ℃, separating out a product, and drying to obtain the high-barrier polyvinyl acetal resin, wherein the graft content of the polar rigid monomer is 5-10mol%.
  3. 3. The method for preparing high-barrier polyvinyl acetal resin according to claim 2, wherein the raw material of the polyvinyl alcohol in step 1 is single-specification polyvinyl alcohol or a mixture of two different-specification polyvinyl alcohols, and the acid in step 2 is hydrochloric acid with a concentration of 15 wt%.
  4. 4. The method for preparing the high-barrier polyvinyl acetal resin according to claim 2, wherein in the step 2, the long-chain aldehyde is an aldehyde with a main chain of 3-4 carbon atoms, the short-chain aldehyde is an aldehyde with a main chain of 1-2 carbon atoms, and in the step 3, the polar rigid monomer is any one of methyl methacrylate, p-methylstyrene, maleic anhydride, acrylonitrile, 2-chloroethyl isocyanate, glycidyl methacrylate, methacrylic acid, crotonic acid, acrylamide, methacrylamide, vinyl ketone and N-vinyl pyrrolidone.
  5. 5. The method for preparing a high barrier polyvinyl acetal resin according to claim 2, wherein the long-chain aldehyde is propionaldehyde, the short-chain aldehyde is acetaldehyde, and the mass ratio of acetaldehyde in the aldehyde mixture is lower than 20wt%.
  6. 6. A high-barrier polyvinyl acetal resin barrier film comprising the high-barrier polyvinyl acetal resin according to claim 1, wherein the preparation method of the high-barrier polyvinyl acetal resin barrier film comprises the following steps: Dissolving high-barrier polyvinyl acetal resin in a mixed organic solvent to prepare resin solution with the concentration of 10-20wt%, uniformly coating the resin solution on the surface of a substrate at 20-40 ℃ to form a wet film, controlling the thickness of the wet film to be 25 mu m, and drying at 20-40 ℃ for 5-10 min to obtain the high-barrier polyvinyl acetal resin barrier film.
  7. 7. The high barrier polyvinyl acetal resin barrier film according to claim 6, wherein the mixed organic solvent is one or more of ethanol, n-butanol, isopropanol, acetone, diethyl ether, methyl acetate, ethyl acetate, propyl acetate, ethyl formate, propyl formate.
  8. 8. The high barrier polyvinyl acetal resin barrier film according to claim 6, wherein the mixed organic solvent is a combination of ethanol and acetone, and a mass ratio of the acetone in the mixed organic solvent is less than 20wt%.
  9. 9. The high barrier polyvinyl acetal resin barrier film according to claim 6, wherein said base material is any one of a steel plate, a release film, and a plastic film.
  10. 10. The application of the high-barrier polyvinyl acetal resin barrier film is characterized in that the high-barrier polyvinyl acetal resin barrier film is the high-barrier polyvinyl acetal resin barrier film according to any one of claims 6 to 9, and the high-barrier polyvinyl acetal resin barrier film is applied to the fields of food packaging, medicine packaging, electronics and electrical appliances, medical fields or optics.

Description

High-barrier polyvinyl acetal resin, preparation method thereof, barrier film and application Technical Field The invention belongs to the technical field of high polymer materials, and particularly relates to a high-barrier polyvinyl acetal resin, a preparation method thereof, a barrier film and application thereof. Background The polyvinyl acetal is a product obtained by condensation reaction of polyvinyl alcohol and various aldehydes, and the molecular chain contains three groups of alcoholic hydroxyl groups, acetoxy groups and acetal groups. The material has good flexibility, tensile strength, impact strength, transparency, light resistance, water resistance and weather resistance, and has potential application value in a plurality of fields. However, the conventional polyvinyl acetal resin has poor gas barrier property, and limits the application of the conventional polyvinyl acetal resin in the fields of high-barrier packaging, electronic component packaging and the like. Materials having excellent gas barrier properties in the prior art mainly include polyvinyl alcohol (PVA), ethylene-vinyl alcohol copolymer (EVOH), and the like. The PVA molecular chain contains a large number of hydroxyl groups, and the hydroxyl groups are easy to form strong hydrogen bond action, so that the molecular chain is compact and regular in arrangement, meanwhile, the PVA has stronger polarity and low affinity to nonpolar oxygen molecules, and therefore, the oxygen barrier property is excellent. However, PVA has poor water resistance, is insoluble in ethanol, and is greatly limited in processing applications. EVOH has slower barrier property attenuation speed in a humid environment compared with PVA, has better stability to grease and chemical media, and is suitable for most packaging scenes. In the related patent technology, US10392527B2 discloses a barrier coating prepared by mixing PVA/EVOH copolymer and an organic solvent, which can be quickly dried at high temperature to form a water-resistant and oil-resistant high-barrier multilayer composite film, but the coating can only be dispersed in about 45% of ethanol aqueous solution and cannot use single ethanol as a solvent. CN120035613A adopts ethylene-vinyl alcohol copolymer blending modification, and needs to accurately control polymer proportion, melting temperature and shearing rate so as to realize uniform distribution of matrix-domain, while the multilayer composite technology relates to multi-step coating, crosslinking reaction or evaporation process, while the barrier property can be improved, the barrier property interval of the product is 0.2-90 cm 3/m224hFluctuation between 0.1MPa and poor stability. The material has poor solvation capability, is only suitable for a high-temperature melting and casting process, cannot prepare ultrathin and uniform-component coating, has high requirements on a substrate material, and has the problems of long production period, high energy consumption and low production efficiency. CN120024099a adopts a multilayer coextrusion mode to prepare the barrier film, the process is complicated, and the additives are excessive, so that the production efficiency is further reduced. In conclusion, the existing high-barrier material generally has the problems of complex solvent system, incapability of dissolving single ethanol, complex processing technology, low production efficiency, insufficient barrier property stability and the like, and restricts the application of the high-barrier material in specific fields. Disclosure of Invention The invention aims to provide a preparation method of a high-barrier polyvinyl acetal resin, which solves the problem of insufficient barrier property of the traditional polyvinyl acetal resin. The second object of the present invention is to provide a high barrier polyvinyl acetal resin produced by the above method, which has excellent oxygen barrier properties, alcohol solubility, flexibility and adhesion. The third object of the present invention is to provide a barrier film made of the above resin, which has high transparency, strong adhesion, good film forming property, and excellent barrier property. The fourth object of the present invention is to provide the application of the barrier film, and cover the fields of high-barrier packaging or protection such as food and drug packaging, electronic component packaging, medical instrument protection, optical lens protection, etc. The aim of the invention can be achieved by the following technical scheme: In a first aspect, a method for preparing a high barrier polyvinyl acetal resin includes the steps of: Step 1, preparing a polyvinyl alcohol solution, namely selecting a polyvinyl alcohol raw material with alcoholysis degree of more than or equal to 95mol% and polymerization degree of 600-1200, dissolving the polyvinyl alcohol raw material in deionized water to prepare a polyvinyl alcohol solution with concentration of 10-12 wt%, heating to 95 ℃, and sti