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CN-121975482-A - LED UV moisture curing adhesive and preparation method thereof

CN121975482ACN 121975482 ACN121975482 ACN 121975482ACN-121975482-A

Abstract

The invention relates to the technical field of UV moisture curing adhesive and discloses an LED UV moisture curing adhesive and a preparation method thereof, wherein the LED UV moisture curing adhesive comprises, by mass, 40% -60% of dual-curing polyurethane acrylate resin, 10% -30% of reactive diluent, 1% -5% of LED photoinitiator, 2% -8% of photo-induced latent moisture curing catalyst, 0.5% -2% of chemical water scavenger and 1% -6% of functional auxiliary agent, the sum of the mass percentages of all the components is 100%, the main chain of the dual-curing polyurethane acrylate resin is a polyurethane chain segment, and an acryloyloxy group and an alkoxy silane group are grafted on the molecular chain at the same time. The invention builds an active linkage mechanism of light curing and moisture curing, so that illumination not only completes the instant shaping of the surface layer, but also activates a high-activity moisture curing catalyst for deep layers or shadow areas, so that the subsequent moisture curing reaction is not completely dependent on natural permeation of environmental humidity, and the reaction rate of curing the shadow areas to the inside is obviously improved.

Inventors

  • Luo Zhangqiong
  • GAN TING

Assignees

  • 东莞市高图新材料有限公司

Dates

Publication Date
20260505
Application Date
20260306

Claims (10)

  1. 1. The LED UV moisture curing adhesive is characterized by comprising the following components in percentage by mass: 40% -60% of dual-curing polyurethane acrylate resin; 10% -30% of reactive diluent; 1% -5% of LED photoinitiator; 2% -8% of a photo-induced latent type moisture curing catalyst; 0.5 to 2 percent of chemical water scavenger; 1-6% of functional auxiliary agent; wherein the sum of the mass percentages of the components is 100 percent; The main chain of the dual-curing polyurethane acrylate resin is a polyurethane chain segment, and an acryloyloxy group and an alkoxy silane group are grafted on a molecular chain at the same time; The photo-induced latent type moisture curing catalyst is a compound which generates photolysis reaction under the irradiation of LED UV light and releases active substances for catalyzing hydrolytic condensation of alkoxy silane groups.
  2. 2. A method of preparing an LED UV moisture curable paste according to claim 1, comprising the steps of: S1, synthesizing dual-curing polyurethane acrylate resin, namely enabling diisocyanate and polyol to react to generate a prepolymer, and then enabling the prepolymer to react with hydroxyl-containing acrylate monomers and active hydrogen-containing silane coupling agents respectively to prepare the dual-curing polyurethane acrylate resin; S2, preparing a catalyst mother liquor, namely dispersing and dissolving a photo-induced latent type moisture curing catalyst in a formula amount of a part of active diluent under a light-shielding condition to prepare a homogeneous catalyst mother liquor; S3, dewatering and compounding, namely mixing the dual-cured polyurethane acrylate resin obtained by synthesis, the residual reactive diluent, the chemical dewatering agent and the functional auxiliary agent in the formula amount, and dewatering under vacuum condition to obtain a dewatering base material; and S4, final mixing and packaging, namely adding the LED photoinitiator and the prepared catalyst mother liquor into the dehydration base material under the conditions of light shielding and temperature control, uniformly mixing, filtering and packaging to obtain the LED UV moisture curing adhesive.
  3. 3. The preparation method of the LED UV moisture curing adhesive according to claim 2, wherein in the step of synthesizing the dual curing polyurethane acrylate resin, a stepwise asymmetric end-capping process is adopted, and the specific reaction control process is that firstly, the diisocyanate and the polyatomic alcohol are subjected to chain extension reaction at the temperature of 75-85 ℃ until the content of isocyanate groups in a system is reduced to 50% +/-5% of a theoretical value; then cooling the system to 45-55 ℃, dropwise adding the hydroxyl-containing acrylate monomer, and reacting at a temperature which is kept constant until the isocyanate group content is half of that consumed; and finally, controlling the system temperature at 40-50 ℃, dropwise adding the active hydrogen-containing silane coupling agent, and continuing the reaction until infrared spectrum detection shows that the characteristic peak of the isocyanate group completely disappears.
  4. 4. The method for preparing the LED UV moisture curing adhesive according to claim 3, wherein in the step-by-step asymmetric end-capping process, the feeding ratio of each reaction raw material meets the following conditions that the molar ratio of diisocyanate to polyol is 2.0-2.2, the feeding amount of the hydroxyl-containing acrylate monomer is 45-55% of the molar amount of the residual isocyanate groups, and the feeding amount of the active hydrogen-containing silane coupling agent is equal to the molar equivalent of the final residual isocyanate groups.
  5. 5. The method for preparing an LED UV moisture curable paste according to claim 2, wherein in the step of preparing the catalyst mother liquor, process parameters are controlled as follows: The light-shielding condition is a yellow light source environment, the temperature of the whole preparation process is controlled to be 15-25 ℃, the dosage of the part of active diluent used for preparing the mother liquor is 20-30% of the total amount of the active diluent in the formula, the stirring speed in the dispersing and dissolving process is 400-800rpm, and the stirring time is 20-40 minutes.
  6. 6. The method for preparing the LED UV moisture curable adhesive according to claim 2, wherein in the step of removing water and compounding, the process parameters and pretreatment are controlled as follows: the vacuum degree of the vacuum condition is controlled between-0.090 MPa and-0.098 MPa, and the holding time is 30-45 minutes; before the functional auxiliary agent is added and mixed, the functional auxiliary agent is subjected to vacuum drying treatment for 4-6 hours at the temperature of 110-130 ℃ in advance.
  7. 7. The method of preparing an LED UV moisture curable glue according to claim 2, wherein in the final mixing and packaging steps, the process parameters are controlled as follows: The temperature control condition is that the temperature of the materials is forcedly controlled to be not more than 30 ℃ by a cooling device; the mixing process is carried out under the condition that the vacuum degree is better than-0.095 MPa, the dispersing speed is controlled to be 300-500rpm, and the mixing time is 15-20 minutes.
  8. 8. The method for preparing the LED UV moisture curing adhesive according to claim 2, wherein the specific types of the photo-latent moisture curing catalyst and the LED photoinitiator are as follows: The photo-induced latent type moisture curing catalyst is selected from one or more of quaternary ammonium salt derivatives of tetraphenylborate or photolysis amine-producing carbamate compounds; The LED photoinitiator is selected from one or more of 2,4, 6-trimethylbenzoyl-diphenyl phosphine oxide or bis (2, 4, 6-trimethylbenzoyl) phenyl phosphine oxide.
  9. 9. The method for preparing the LED UV moisture curing adhesive according to claim 2, wherein the synthetic raw materials of the dual curing polyurethane acrylate resin are specifically selected from the following types: The hydroxyl-containing acrylate monomer is selected from hydroxyethyl acrylate or hydroxypropyl acrylate; the active hydrogen-containing silane coupling agent is selected from 3-aminopropyl trimethoxy silane or 3-mercaptopropyl trimethoxy silane.
  10. 10. The method for preparing the LED UV moisture curable glue according to claim 2, wherein the specific types of the reactive diluent and the chemical water scavenger are: The reactive diluent is selected from one or more of isobornyl acrylate, acryloylmorpholine and 1, 6-hexanediol diacrylate; the chemical water scavenger is selected from vinyl trimethoxy silane or vinyl triethoxy silane.

Description

LED UV moisture curing adhesive and preparation method thereof Technical Field The invention relates to the technical field of UV moisture curing adhesives, in particular to an LED UV moisture curing adhesive and a preparation method thereof. Background With the rapid development of electronic packaging technology, in order to protect Printed Circuit Boards (PCBs) and electronic components from environmental moisture, chemical corrosion and mechanical impact, ultraviolet (UV) curing adhesives have been widely used in the field of electronic assembly due to the advantages of fast curing speed, high production efficiency, suitability for assembly line operation, etc., and along with the increasing strictness of environmental regulations and the improvement of energy-saving requirements, conventional mercury lamp light sources are gradually replaced by LED UV light sources with lower energy consumption, longer service life and no ozone generation, which makes cured materials based on LED light sources hot spots for industry development. However, in practical applications, the structure of the electronic component is increasingly complex and the integration level is continuously improved, so that light is difficult to penetrate through the bottom of the component or the pin gaps densely arranged, and the shadow areas cannot be cured by ultraviolet irradiation. Although the existing UV-moisture dual curing technology alleviates shadow curing problems to a certain extent, a significant technical bottleneck is still faced in practical application, in the existing dual curing system, the photo-curing reaction and the moisture curing reaction are generally two mutually independent parallel processes, the light is only responsible for initiating free radical polymerization, and the moisture curing process lacks active promotion effect, so that the curing of a shadow area is completely in a passive state, the reaction rate of the shadow area is extremely dependent on the environmental humidity and the diffusion speed of moisture, and the shadow area can be completely cured in a dry environment or a deep potting scene usually in days or even weeks, so that the circulation efficiency and the final performance of a product are seriously affected. In order to improve the moisture curing rate, the prior art often adds high-activity organic tin or organic bismuth catalysts into the formula, however, the conventional catalysis means brings a contradiction that the high-activity catalysts can slowly initiate reaction due to trace moisture or thermal history in the glue solution storage period (even in a closed container), so that the viscosity of the adhesive climbs too fast or even gels, the storage period of the product is greatly shortened, otherwise, if the catalyst dosage is reduced to ensure the storage stability, the shadow part after sizing is not completely cured or is sticky, in addition, in the selection of a resin matrix, the prior art mostly adopts a simple physical blending mode, namely, the photo-curing resin and the moisture curing resin are directly mixed, the compatibility of the system is poor due to the polarity and molecular structure difference of the two types of resins, microscopic phase separation is easy to occur in the curing process, the appearance of the cured product is easy to be fogged and the light transmittance is reduced, and microcracks easily appear under the internal stress of the cured glue layer due to the lack of organic connection of chemical bonds, so that the requirements of high-end electronic encapsulation on the severe mechanical performance and the optical performance of materials are difficult to meet. Disclosure of Invention The invention aims to provide an LED UV moisture curing adhesive and a preparation method thereof, which solve the problems that the curing reaction of a shadow area in the existing LED UV moisture dual-curing system is passive and slow, the curing reaction is seriously dependent on environmental humidity, and the deep rapid curing is difficult to realize on the premise of ensuring the long-term storage stability of an adhesive solution. In order to achieve the above purpose, the invention is realized by the following technical scheme: an LED UV moisture curing adhesive comprises the following components in percentage by mass: 40% -60% of dual-curing polyurethane acrylate resin; 10% -30% of reactive diluent; 1% -5% of LED photoinitiator; 2% -8% of a photo-induced latent type moisture curing catalyst; 0.5 to 2 percent of chemical water scavenger; 1-6% of functional auxiliary agent; wherein the sum of the mass percentages of the components is 100 percent; The main chain of the dual-curing polyurethane acrylate resin is a polyurethane chain segment, and an acryloyloxy group and an alkoxy silane group are grafted on a molecular chain at the same time; The photo-induced latent type moisture curing catalyst is a compound which generates photolysis reaction under