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CN-121975396-A - Low-mobility UV free radical/cation hybrid type finishing oil and preparation method thereof

CN121975396ACN 121975396 ACN121975396 ACN 121975396ACN-121975396-A

Abstract

The application relates to the technical field of ultraviolet light curing coatings, and particularly discloses low-mobility UV free radical/cation hybrid type finishing oil and a preparation method thereof. The low-mobility UV free radical/cation hybrid type finishing oil comprises, by weight, 50-70 parts of alicyclic epoxy resin, 5-10 parts of modified polyester acrylate, 5-10 parts of aliphatic polyurethane acrylate, 15-30 parts of diluent, 4-9 parts of photoinitiator, 0.5-2 parts of wax powder, 0-1 part of leveling agent and 0-2 parts of coupling agent, wherein the molecular weight of the modified polyester acrylate and the molecular weight of the aliphatic polyurethane acrylate are both more than or equal to 1500, and the molecular weight of the photoinitiator is more than 1000. The low-mobility UV free radical/cation hybrid type finishing oil can be used as an inner and outer wall coating of a food packaging can, has low mobility, is free of BPA, avoids BPA from being introduced from the source, and greatly reduces the migration risk of a photoinitiator.

Inventors

  • MAO LINGLING

Assignees

  • 上海超彩油墨有限公司

Dates

Publication Date
20260505
Application Date
20260312

Claims (9)

  1. 1. The low-mobility UV free radical/cation hybrid type finishing oil is characterized by comprising the following components in parts by weight: 50-70 parts of alicyclic epoxy resin, 5-10 parts of modified polyester acrylate, 5-10 parts of aliphatic polyurethane acrylate, 15-30 parts of diluent, 4-9 parts of photoinitiator, 0.5-2 parts of wax powder, 0-1 part of flatting agent and 0-2 parts of coupling agent; the molecular weight of the modified polyester acrylic ester and the aliphatic polyurethane acrylic ester is more than or equal to 1500; the molecular weight of the photoinitiator is >1000.
  2. 2. The low migration UV free radical/cationic hybrid overprint varnish of claim 1, wherein the modified polyester acrylate and the aliphatic polyurethane acrylate have molecular weights of >2000.
  3. 3. The low migration UV free radical/cationic hybrid overprint varnish of claim 1, wherein the diluent comprises the following components in parts by weight: 10-20 parts of cation reactive diluent; 5-10 parts of free radical reactive diluent.
  4. 4. The low migration UV-free/cationic hybrid overprint varnish according to claim 3, wherein the cationic reactive diluent is an oxetane compound.
  5. 5. The low migration UV-free/cationic hybrid overprint varnish of claim 3, wherein the reactive diluent is a difunctional monomer.
  6. 6. The low-mobility UV free radical/cation hybrid overprint varnish according to claim 1, wherein the photoinitiator comprises the following components in parts by weight: 3-6 parts of a cationic photoinitiator; 1-3 parts of free radical photoinitiator.
  7. 7. The low migration UV free radical/cationic hybrid overprint varnish of claim 1, wherein the wax powder is a fluorine-free polyethylene wax powder.
  8. 8. A method of preparing the low mobility UV radical/cation hybrid overprint varnish of any one of claims 1 to 7, comprising the steps of: S1, mixing wax powder and part of modified polyester acrylic ester under the light-shielding condition, and grinding to the fineness of less than 2.5 mu m to prepare wax slurry; s2, mixing the rest modified polyester acrylate, alicyclic epoxy resin, aliphatic polyurethane acrylate and diluent with wax slurry under the light-shielding condition, and dispersing for 25-35 minutes at the rotating speed of 400-600 rpm; s3, adding a leveling agent and a coupling agent into the mixture obtained in the step S2, and mixing; S4, adding a photoinitiator into the mixture obtained in the step S3, and mixing; And S5, filtering and packaging the mixture obtained in the step S4 to obtain the composite material.
  9. 9. Use of a low migration UV radical/cation hybrid overprint varnish according to any one of claims 1-7 as a protective coating on the inner and outer walls of a metal food can.

Description

Low-mobility UV free radical/cation hybrid type finishing oil and preparation method thereof Technical Field The application relates to the technical field of ultraviolet light curing coatings, in particular to low-mobility UV free radical/cation hybrid type finishing oil and a preparation method thereof. Background Metal food cans, such as beverage cans, snack cans, milk cans, and the like, are typically coated with a finish oil on their surfaces to provide protection, decoration, and printability. Ultraviolet light curing paint is widely applied in the field due to the fast curing speed, high efficiency and low VOCs emission. With the emphasis placed on food safety in countries and even different countries around the world, food safety related requirements are becoming more stringent and regulations are increasing, mainly concerning substances that may migrate into food. The main stream UV finishing oil at present generally adopts bisphenol A type epoxy acrylate as prepolymer and micromolecular photoinitiator, and has two major potential safety hazards: first, bisphenol a epoxy acrylate is commonly used as a prepolymer, bisphenol a (BPA) is a known endocrine disrupter whose use is severely limited or even prohibited in food contact materials. Second, small molecule photoinitiators are used in large quantities and these small molecule substances, after curing, tend to migrate from the coating into the packaged food, with a risk of food safety. Disclosure of Invention In order to simultaneously solve the problems of no bisphenol A and reduced migration of UV finishing oil for metal food cans, the application provides a low-migration UV free radical/cation hybrid finishing oil and a preparation method thereof. In a first aspect, the application provides a low-mobility UV free radical/cation hybrid type finishing oil, which adopts the following technical scheme: The low-mobility UV free radical/cation hybrid type finishing oil comprises the following components in parts by weight: 50-70 parts of alicyclic epoxy resin, 5-10 parts of modified polyester acrylate, 5-10 parts of aliphatic polyurethane acrylate, 15-30 parts of diluent, 4-9 parts of photoinitiator, 0.5-2 parts of wax powder, 0-1 part of flatting agent and 0-2 parts of coupling agent; the molecular weight of the modified polyester acrylic ester and the aliphatic polyurethane acrylic ester is more than or equal to 1500; the molecular weight of the photoinitiator is >1000. By adopting the technical scheme, the bisphenol A type epoxy resin is completely abandoned by taking the alicyclic epoxy resin as a main body, so that the risk of BPA migration is eliminated from the source. By simultaneously using photoinitiators with molecular weights >1000, traditional small molecular initiators are thoroughly replaced, and the possibility of migration of initiator residues is greatly reduced. In addition, the interpenetrating polymer network is constructed by mixing and solidifying the alicyclic epoxy resin, the modified polyester acrylic ester with specific content and the aliphatic polyurethane acrylic ester. The system skillfully combines the advantages of cationic curing (high hardness, small shrinkage, good adhesive force) and free radical curing (good flexibility and fast curing), solves the industrial problems that the brittleness of a pure cationic system is high, and the adhesive force and the flexibility of a pure free radical system are difficult to be compatible, and enables the coating to finally obtain excellent adhesive force, hardness, flexibility and impact resistance at the same time, thereby meeting the processing requirements of a metal can. By the ternary synergistic combination of the cycloaliphatic epoxy resin plus the non-BPA acrylate resin of a specific molecular weight plus the macroinitiator, excellent adhesion, flexibility and processing applicability are unexpectedly achieved while achieving food safety requirements. Optionally, the molecular weight of both the modified polyester acrylate and the aliphatic urethane acrylate is >2000. By adopting the technical scheme, the molecular weight of the two acrylic ester resins is definitely limited to be more than 2000, and compared with a small molecular monomer or oligomer, the high molecular weight prepolymer has obviously reduced mobility. Meanwhile, the high molecular weight resin can more effectively contribute to cohesive strength and toughness of the coating, and the high molecular weight resin is complementary with a rigid alicyclic epoxy resin network as a soft chain segment, plays a key role in realizing excellent flexibility and impact resistance, and avoids cracking of the coating due to deformation in subsequent processing. Optionally, the diluent comprises the following components in parts by weight: 10-20 parts of cation reactive diluent; 5-10 parts of free radical reactive diluent. The technical scheme is that the cationic reactive diluent is adopted to participate in the cur