UV curing resin for solvent-free release film and preparation method of UV curing resin

Abstract

The invention relates to the technical field of light-cured oligomers, and discloses UV-cured resin for a solvent-free release film and a preparation method of the UV-cured resin, and the UV-cured resin is prepared by taking polydialkylsiloxane with single terminal (methyl) acrylate, (methyl) acrylic acid, a hard monomer and a soft monomer as raw materials through photopolymerization under the action of 244nm-264nm LED ultraviolet light and a benzophenone photoinitiator. Then, the polymer reacts with glycidyl methacrylate, so that the solvent-free UV resin with high release force and high permeability is prepared.

Description

Technical Field

[0001] The present invention relates to the technical field of photocurable oligomers, and particularly to a UV-curable resin for solvent-free release films and a preparation method thereof. Background Art

[0002] A release film refers to a film with a separating property on its surface. The release film does not have adhesiveness or only has slight adhesiveness after contacting a specific material under limited conditions. The resin for release films refers to a specific resin material used to manufacture release films, and these resins endow the release films with specific properties and application characteristics. Resins for release films usually need to have properties such as non-adhesiveness, good mechanical properties (such as tensile strength and elongation), flexibility, heat resistance, chemical resistance, and oil resistance. Release films are widely used in the fields of electronic power, IT displays, mobile phones, medical treatment, household appliances, anti-counterfeiting materials, semiconductors, automobiles, ceramics, tape production, and die-cutting industries, etc. Especially, they are widely used in composite materials, plastic molds, electronic components, etc.

[0003] Currently, the common release agents on the market are mainly solvent-based silicone release agents. The catalyst of this type of release agent is a platinum-based compound, and the cost is relatively high. Moreover, organic dilution solvents must be used in the coating stage, inevitably causing environmental problems and harming the human body.

[0004] In addition, as a green and efficient curing method, photocuring technology has been widely used in many fields. It uses medium and short-wave radiation of ultraviolet light to make the photoinitiator in the liquid UV material be excited into free radicals or cations through radiation, thereby triggering the rapid cross-linking of oligomers containing active groups into insoluble and infusible solids. It has the characteristics of high efficiency, economy, energy saving, wide applicability, and environmental friendliness. However, there are still certain technical challenges in the application of photocuring technology in the field of release agents.

[0005] Therefore, it is in market demand to develop a release resin for high-performance release agents that is efficient in performance, environmentally friendly in coating, low in cost, and based on photocuring technology. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the present invention provides an environmentally friendly, low-cost, and high-efficiency UV-curable resin for solvent-free release films and a preparation method thereof.

[0007] To achieve the above purposes, the present invention is realized through the following technical solutions: A UV-curable resin for solvent-free release films, the UV-curable resin for solvent-free release films has the following structure: Among them, n is a positive integer; R 1 is an alkyl group or an N-containing group; R 2 and R3 are both alkyl groups; R and R 4 are both alkyl groups.

[0008] A method for preparing a UV-curable resin for a solvent-free release film, comprising the following steps: S1. Under the condition of 35-60 °C, sequentially add polydimethylsiloxane with a single-terminal (meth)acrylate, acrylic acid, hard monomer, and soft monomer into a reaction kettle; S2. Then add a benzophenone initiator, continuously stir to make the system uniformly dispersed, and at the same time turn on the 244nm-264nm LED ultraviolet light irradiation, continuously irradiate for 4h-8h, carry out a free radical polymerization reaction, and terminate the light irradiation when the viscosity of the system reaches the theoretical value; S3. After terminating the light irradiation, add a catalyst and a polymerization inhibitor to the system, heat to 75 °C-90 °C, continuously stir for 30 min, then slowly dropwise add glycidyl methacrylate, maintain the temperature at 90 °C-115 °C, and continuously stir until the acid value drops below 4mgOH / g; S4. After the acid value meets the standard, cool the temperature in the reaction kettle to room temperature, and filter with a microporous filter membrane to remove unreacted substances to obtain a UV-curable resin for a solvent-free release film with a translucent appearance.

[0009] Preferably, the polydialkylsiloxane with a single-terminal (meth)acrylate is any one or a combination of multiple ones with a molecular weight in the range of 1500-5000.

[0010] Preferably, the (meth)acrylic acid is any one or a combination of multiple ones of acrylic acid and methacrylic acid.

[0011] Preferably, the hard monomer is any one or a combination of multiple ones of methyl methacrylate, acrylonitrile, and acrylamide.

[0012] Preferably, the soft monomer is any one or a combination of multiple ones of ethyl acrylate, butyl acrylate, isooctyl acrylate, and lauryl acrylate.

[0013] Preferably, the glycidyl methacrylate used is industrial grade, and the purity can reach more than 98%.

[0014] Preferably, the benzophenone initiator is any one or a combination of multiple ones of benzophenone, 2-methylbenzophenone, 4-methylbenzophenone, and 2,4,6-trimethylbenzophenone.

[0015] Preferably, the catalyst is any one or a combination of multiple ones of triphenylphosphine, triethylamine, N,N-dimethylbenzylamine, and benzyltriethylammonium chloride; The polymerization inhibitor is any one or a combination of multiple ones of p-methoxyphenol, hydroquinone, and tert-butylhydroquinone.

[0016] Preferably, in the steps S1 - S4, the mass ratio of the polydialkylsiloxane of mono - terminal (meth)acrylate, (meth)acrylic acid, hard monomer, soft monomer, benzophenone - type initiator, catalyst, inhibitor, and glycidyl methacrylate is: 100:(25 - 40):(15 - 30):(15 - 30):(3 - 8):(0.5 - 1.5):(0.2 - 1.0):(45 - 85).

[0017] The present invention provides a UV - curable resin for solvent - free release film and its preparation method, which has the following beneficial effects: 1. The solvent - free system of the present invention through free - radical polymerization with a 254 - nm LED ultraviolet point light source achieves the technical effects of high efficiency, environmental protection, excellent release effect, and good photocuring performance. Compared with the prior - art technical solution using a solvent - type silicone release agent, the present invention avoids the use of platinum catalysts and organic dilution solvents, solves the problems of environmental pollution, harm to human health, and high cost, and at the same time improves the curing efficiency, greatly enhancing the controllability of the product quality in industrial production.

[0018] 2. By introducing polydialkylsiloxane with low surface energy into the side chain of the molecular chain and grafting glycidyl methacrylate, the resin has photocuring ability while maintaining high release force. Compared with the prior art, the present invention improves the release performance, enables the product to have high transparency, and at the same time uses photocuring technology to achieve rapid curing, with a significant improvement in efficiency.

[0019] 3. The preparation process of the present invention is simple and highly controllable, with a higher industrial level and lower cost than the process of using a release agent containing a solution of platinum - based compounds, and has strong market competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic structural diagram of the product of the present invention; Figure 2 is a flow chart of the preparation steps of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] Please refer to the attached Figure 1 - attached Figure 2 , Example 1: In this embodiment, the UV - curable resin for solvent - free release film is prepared according to the following steps: S1. Put 100 g of polydimethylsiloxane with a single-terminal methacrylate, 36.36 g of acrylic acid, 23.86 g of methyl methacrylate, 23.64 g of isooctyl acrylate, and 5.5 g of benzophenone into a reaction kettle, start stirring, keep the reaction temperature at 40 °C, use a 254-nm LED point light source for partial initiation at the upper part of the reaction kettle, react for 6 h until the viscosity reaches the theoretical value, and stop the LED irradiation; S2. Add 0.76 g of triphenylphosphine and 0.25 g of p-methoxyphenol, raise the temperature to 85 °C and stir for 30 min, then dropwise add 71.78 g of glycidyl methacrylate. After the addition is completed, keep the reaction temperature at 112 °C and react until the acid value is lower than 4 mgOH / g, then cool down and discharge to obtain a UV-curable resin for solvent-free release film with a semi-transparent appearance; Example 2: In this example, a UV-curable resin for solvent-free release film was prepared according to the following steps: S1. Put 110 g of polydimethylsiloxane with a single-terminal methacrylate, 38.56 g of acrylic acid, 28.62 g of acrylamide, 26.25 g of isooctyl acrylate, and 7.5 g of benzophenone into a reaction kettle, start stirring, keep the reaction temperature at 40 °C, use a 254-nm LED point light source for partial initiation at the upper part of the reaction kettle, react for 6 h until the viscosity reaches the theoretical value, and stop the LED irradiation; S2. Add 1.26 g of triphenylphosphine and 0.85 g of p-methoxyphenol, raise the temperature to 85 °C and stir for 30 min, then dropwise add 81.25 g of glycidyl methacrylate. After the addition is completed, keep the reaction temperature at 112 °C and react until the acid value is lower than 4 mgOH / g, then cool down and discharge to obtain a UV-curable resin for solvent-free release film with a semi-transparent appearance; Example 3: In this example, a UV-curable resin for solvent-free release film was prepared according to the following steps: S1. Put 120 g of polydimethylsiloxane with a single-terminal methacrylate, 36.36 g of acrylic acid, 23.86 g of methyl methacrylate, 23.64 g of isooctyl acrylate, and 5.5 g of benzophenone into a reaction kettle, start stirring, keep the reaction temperature at 40 °C, use a 254-nm LED point light source for partial initiation at the upper part of the reaction kettle, react for 6 h until the viscosity reaches the theoretical value, and stop the LED irradiation; S2. Add 0.76 g of benzyltriethylammonium chloride and 0.65 g of p-methoxyphenol, raise the temperature to 85 °C and stir for 30 min, then dropwise add 71.78 g of glycidyl methacrylate. After the addition is completed, keep the reaction temperature at 112 °C and react until the acid value is lower than 4 mgOH / g, then cool down and discharge to obtain a UV-curable resin for solvent-free release film with a semi-transparent appearance; Example 4: In this embodiment, the UV-curable resin for solventless release film is prepared according to the following steps: S1. Put 130 g of polydimethylsiloxane with a single-terminal methacrylate, 36.36 g of acrylic acid, 21.82 g of methyl methacrylate, 26.25 g of butyl acrylate, and 5.0 g of benzophenone into a reaction kettle, start stirring, with a reaction temperature of 40 °C. Use a 254-nm LED point light source for partial initiation at the upper part of the reaction kettle, with a reaction time of 6 h until the viscosity reaches the theoretical value, and then stop the LED irradiation; S2. Add 1.26 g of N,N-dimethylbenzylamine and 0.45 g of p-methoxyphenol, heat up to 85 °C and stir for 30 min, then dropwise add 71.78 g of glycidyl methacrylate. After the dropping is completed, keep the reaction temperature at 112 °C and react until the acid value is lower than 4 mgOH / g, then cool down and discharge to obtain a UV-curable resin for solventless release film with a semi-transparent appearance; Example 5: In this embodiment, the UV-curable resin for solventless release film is prepared according to the following steps: S1. Put 110 g of polydimethylsiloxane with a single-terminal methacrylate, 36.36 g of acrylic acid, 23.86 g of acrylamide, 26.25 g of butyl acrylate, and 5.0 g of benzophenone into a reaction kettle, start stirring, with a reaction temperature of 40 °C. Use a 254-nm LED point light source for partial initiation at the upper part of the reaction kettle, with a reaction time of 6 h until the viscosity reaches the theoretical value, and then stop the LED irradiation; S2. Add 1.26 g of N,N-dimethylbenzylamine and 0.65 g of p-methoxyphenol, heat up to 85 °C and stir for 30 min, then dropwise add 71.78 g of glycidyl methacrylate. After the dropping is completed, keep the reaction temperature at 112 °C and react until the acid value is lower than 4 mgOH / g, then cool down and discharge to obtain a UV-curable resin for solventless release film with a semi-transparent appearance; Example 6: In this embodiment, the UV-curable resin for solventless release film is prepared according to the following steps: S1. Put 145 g of polydimethylsiloxane with a single-terminal methacrylate, 36.36 g of acrylic acid, 21.82 g of methyl methacrylate, 26.25 g of butyl acrylate, and 5.0 g of benzophenone into a reaction kettle, start stirring, with a reaction temperature of 40 °C. Use a 254-nm LED point light source for partial initiation at the upper part of the reaction kettle, with a reaction time of 6 h until the viscosity reaches the theoretical value, and then stop the LED irradiation; S2. Add 0.76 g of benzyltriethylammonium chloride and 0.45 g of p-methoxyphenol. After heating to 85 °C and stirring for 30 min, add 66.50 g of glycidyl methacrylate dropwise. After the addition is complete, the reaction temperature is 112 °C. React until the acid value is lower than 4 mgOH / g, then cool down and discharge to obtain a UV-curable resin for solvent-free release film with a translucent appearance.

[0023] Comparative Example 1: Select a conventional silicone release agent on the market as the comparative example. The product model is KS-847H, and the manufacturer is Shin-Etsu Chemical Co., Ltd.

[0024] Comparative experiment: Respectively, mix the resins obtained in Examples 1-6 evenly with 3 g of photoinitiator 184. After sufficient dissolution, perform defoaming treatment using a high-speed bench centrifuge. The coating thickness is 5 μm, and use a UV track curing machine for photocuring with a curing energy of 600 mJ / cm 2 ; Mix 100 g of the product of Comparative Example 1 and 2.5 g of platinum catalyst evenly, then cure by hot baking. The dry film thickness is 5 μm.

[0025] Test standard: Release force of the release film: Test according to the standard GB / T25256-2010 "Test Method for 180° Release Force and Residual Adhesion of Release Films for Optical Functional Films".

[0026] Table 1: Peeling force N / 25mm Curing time Example 1 0.090 5s Example 2 0.083 5s Example 3 0.079 5s Example 4 0.091 5s Example 5 0.084 5s Example 6 0.080 5s Comparative Example 1 0.015 5min This experiment aims to evaluate the differences in release performance and curing time between the UV-curable resin for solvent-free release film (Examples 1-6) and the traditional solvent-based silicone release agent (Comparative Example 1). Through standardized testing of various samples, the experiment verified the advantages of the new solvent-free resin in the application of photocurable release films, especially in terms of release force and curing efficiency. The results are shown in Table 1.

[0027] The experimental results show that the solvent-free UV-curable resins prepared in Examples 1-6 all exhibit excellent release force. The release forces are all between 0.079 N / 25 mm and 0.091 N / 25 mm, and the curing time is very short, only 5 seconds, while the curing time required for Comparative Example 1 reaches 5 minutes.

[0028] The experiment shows that the resin synthesized by the synthesis method of the present invention not only has a higher release force, but also the photocuring time is significantly shortened, meeting the requirements of more efficient and environmentally friendly industrial production. It meets the requirements of the UV-curable resin for release films for performance, environmental protection and cost control, and has good market demand prospects.

[0029] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A UV curable resin for solvent-free release film, characterized in that: A UV curable resin for a solvent-free release film has the following structure: Wherein, n is a positive integer; R1 is an alkyl group or an N-containing group; R2 and R3 are both alkyl groups; R and R4 are both alkyl groups.

2. A method for preparing a UV curable resin for a solvent-free release film according to claim 1, characterized in that: The following steps are involved: S1. At 35-60° C., polydimethylsiloxane with single-terminal (meth)acrylate, acrylic acid, hard monomer, and soft monomer are sequentially added into a reaction kettle; S2, add benzophenone initiator, continue stirring to make the system evenly dispersed, and turn on 244nm-264nm LED ultraviolet light irradiation, continue irradiation for 4h-8h, carry out free radical polymerization reaction, and terminate the irradiation when the viscosity of the system reaches the theoretical value; S3. After terminating the light irradiation, add the catalyst and the polymerization inhibitor to the system, heat to 75°C-90°C, continue stirring for 30 minutes, then slowly drop glycidyl methacrylate, maintain the temperature at 90°C-115°C, and continue stirring until the acid value drops below 4 mgOH / g; S4. After the acid value reaches the standard, the temperature in the reactor is cooled to room temperature, and the unreacted products are removed by filtering with a microporous filter membrane to obtain a UV curing resin for a solvent-free release film having a translucent appearance.

3. The method for preparing a UV curable resin for a solvent-free release film according to claim 2, characterized in that: The polydialkylsiloxane having a single terminal (meth)acrylate is any one or more combinations having a molecular weight of 1500-5000.

4. The method for preparing a UV curable resin for a solvent-free release film according to claim 2, characterized in that: The (meth)acrylic acid is any one or more combinations of acrylic acid and methacrylic acid.

5. The method for preparing a UV curable resin for a solvent-free release film according to claim 2, characterized in that: The hard monomer is any one or more combinations of methyl methacrylate, acrylonitrile and acrylamide.

6. The method for preparing a UV curable resin for a solvent-free release film according to claim 2, characterized in that: The soft monomer is any one or more combinations of ethyl acrylate, butyl acrylate, isooctyl acrylate and lauryl acrylate.

7. The method for preparing a UV curable resin for a solvent-free release film according to claim 2, characterized in that: The glycidyl methacrylate is industrial grade, and the purity can reach more than 98%.

8. The method for preparing a UV curable resin for a solvent-free release film according to claim 2, characterized in that: The benzophenone initiator is any one or more combinations of benzophenone, 2-methylbenzophenone, 4-methylbenzophenone and 2,4,6-trimethylbenzophenone.

9. The method for preparing a UV curable resin for a solvent-free release film according to claim 2, characterized in that: The catalyst is any one or more combinations of triphenylphosphine, triethylamine, N,N-dimethylbenzylamine and benzyltriethylammonium chloride; the inhibitor is any one or more combinations of p-hydroxyanisole, hydroquinone and tert-butylhydroquinone.

10. The method for preparing a UV curable resin for a solvent-free release film according to claim 2, characterized in that: In the steps S1 to S4, the mass ratio of the single-terminal (meth)acrylate polydialkylsiloxane, (meth)acrylic acid, hard monomer, soft monomer, benzophenone initiator, catalyst, inhibitor, and glycidyl methacrylate is: 100: (25-40): (15-30): (15-30): (3-8): (0.5-1.5): (0.2-1.0): (45-85).

Images