Rapid low-temperature curing photosensitive resin

Abstract

The invention discloses a rapid low-temperature curing photosensitive resin, and relates to the field of coatings. The rapid low-temperature curing photosensitive resin provided by the invention is prepared from the following components in parts by weight: 40 to 70 parts of hyperbranched polyester acrylate prepolymer, 2 to 8 parts of composite photoinitiator, 5 to 15 parts of functionalized nano silicon dioxide, 20 to 40 parts of reactive diluent, 0.5 to 2 parts of flatting agent and 0.1 to 1 part of defoaming agent. The hyperbranched structure has a highly branched three-dimensional network, intermolecular entanglement is less, interlayer bonding is excellent, the viscosity of a resin system is remarkably reduced, the fluidity is improved, and the hyperbranched structure is suitable for precision forming processes such as 3D printing and photoresist; a plurality of acrylate end groups with high functionality are contained, a multi-crosslinking-point reaction is initiated during ultraviolet irradiation, the curing time is shortened, and the curing efficiency is high; the crosslinking density is high, and the mechanical property is strong; and the molecular chain has good flexibility, can still maintain reaction activity at low temperature, and is suitable for rapid low-temperature curing scenes such as working conditions in regions with low air temperature.

Description

Technical Field

[0001] The present invention relates to the field of coatings, and in particular to a fast low-temperature curing photosensitive resin. Background Art

[0002] In the prior art, photosensitive resins often have the following problems in low-temperature curing applications:

[0003] First, the curing efficiency is low. Second, the mechanical properties are insufficient. Conventional nanofillers are prone to agglomeration and difficult to disperse evenly, resulting in low mechanical strength after the resin is cured. Third, existing photosensitive resins are prone to poor interlayer bonding in 3D printing, making them difficult to use. Summary of the Invention

[0004] The present invention is made to solve the above problems and aims to provide a low-temperature curing photosensitive resin with high curing efficiency, strong mechanical properties and excellent interlayer bonding.

[0005] The present invention provides a fast low-temperature curing photosensitive resin, comprising, by weight:

[0006] 40-70 parts of hyperbranched polyester acrylate prepolymer, 2-8 parts of composite photoinitiator, 5-15 parts of functionalized nano-silica, 20-40 parts of active diluent, 0.5-2 parts of leveling agent and 0.1-1 parts of defoaming agent,

[0007] Wherein, the composite photoinitiator includes an α-hydroxyketone compound and a diaryl iodonium salt compound.

[0008] Furthermore, the composite photoinitiator is composed of 1-3 parts by weight of an α-hydroxyketone compound and 1-2 parts by weight of a diaryliodonium salt compound.

[0009] Furthermore, in some embodiments of the present invention, the nano-silica is functionalized nano-silica with γ-methacryloxypropyltrimethoxysilane grafted on its surface; the preparation method of the functionalized nano-silica is as follows:

[0010] 1. Raw Materials Preparation

[0011] Nano-SiO2 (VN3 type, particle size 20-30 nm, Degussa);

[0012] γ-Methacryloxypropyltrimethoxysilane (KH-570);

[0013] Ethanol, deionized water, hydrochloric acid (for pH adjustment);

[0014] 2. Preparation Method

[0015] 1) Mix ethanol and deionized water in a mass ratio of 9:1, and add hydrochloric acid dropwise to adjust the pH to 4.0-4.5;

[0016] 2) Add 1% of the total mass of the solution, KH-570, and stir for 8-10 hours to allow KH-570 to fully hydrolyze into silanols;

[0017] 3) Add nano-SiO2 into the hydrolyzate at a mass of 9 times that of KH-570 and heat to 70-75°C;

[0018] 4) React for 8-10 hours under stirring at 500-600 r / min; the grafting efficiency can be optimized by adding KH-570 stepwise or adding a small amount of catalyst (such as ammonia).

[0019] 5) After the reaction is completed, the mixture is extracted with ethanol using a Soxhlet extractor for 24 hours to remove physically adsorbed KH-570.

[0020] 6) The extracted product was dried in a forced air drying oven at 80° C. for 24 hours to obtain grafted SiO 2 powder (GS).

[0021] Furthermore, in some embodiments of the present invention, the composite photoinitiator is composed of 1-3 parts by weight of 2-hydroxy-2-methyl-1-phenyl-1-propanone and 1-2 parts by weight of 4,4'-dimethyldiphenyliodonium hexafluoroantimonate.

[0022] Furthermore, the functionalized nano-silica is surface-grafted with γ-methacryloxypropyltrimethoxysilane.

[0023] Furthermore, the grafting rate of the surface grafted γ-methacryloxypropyltrimethoxysilane is 15-25%.

[0024] Furthermore, the particle size of the functionalized nano-silica is 20-30 nm.

[0025] Furthermore, the reactive diluent is selected from epoxy acrylate and / or itaconate.

[0026] Furthermore, the method for preparing the rapid low-temperature curing photosensitive resin comprises the following steps:

[0027] The hyperbranched polyester acrylate prepolymer is mixed with an active diluent, functionalized nano-silica is added, dispersed, three-roll milled, ultrasonically dispersed, a composite photoinitiator, a leveling agent and a defoaming agent are added, and vacuum degassing is performed to obtain the product.

[0028] Furthermore, in the method for preparing a rapid low-temperature curing photosensitive resin, the parameter of the three-roller grinding is that the roller spacing is set to 10-50 μm.

[0029] Furthermore, in the method for preparing a rapid low-temperature curing photosensitive resin, the ultrasonic dispersion is performed at a frequency of 20-50 kHz and for a duration of 1-5 hours.

[0030] Functions and effects of the invention

[0031] The fast, low-temperature curing photosensitive resin involved in the present invention has excellent interlayer bonding, a hyperbranched structure with a highly branched three-dimensional network, less intermolecular entanglement, significantly reducing the viscosity of the resin system and improving fluidity, making it suitable for precision molding processes such as 3D printing and photoresist; high curing efficiency, the hyperbranched prepolymer contains multiple high-functionality acrylate end groups, which trigger multiple cross-linking point reactions when irradiated with ultraviolet light, shortening the curing time; strong mechanical properties, high cross-linking density, and excellent hardness, wear resistance and chemical resistance of the cured material; better low-temperature adaptability, good molecular chain flexibility, and the ability to maintain reaction activity at low temperatures, making it suitable for fast low-temperature curing scenarios such as working conditions in areas with low temperatures. DETAILED DESCRIPTION

[0032] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is described in detail below with reference to the embodiments.

[0033] <Example 1>

[0034] A fast low-temperature curing photosensitive resin

[0035] This embodiment provides a fast, low-temperature curing photosensitive resin, which includes, by weight, 50 parts of a hyperbranched polyester acrylate prepolymer, 6 parts of a composite photoinitiator, 12 parts of nano-silica (particle size 20 nm), 28 parts of an epoxy acrylate diluent, 1.2 parts of a leveling agent (BYK-333), and 0.5 parts of a defoaming agent (BYK-055).

[0036] The hyperbranched polyester acrylate prepolymer comprises pentaerythritol, dimethylolpropionic acid (DMPA) and adipic acid, and the molar ratio of pentaerythritol, dimethylolpropionic acid and adipic acid is 1:2.5:1.

[0037] The preparation method of the hyperbranched polyester acrylate prepolymer:

[0038] 1. Under nitrogen protection, add pentaerythritol, DMPA and adipic acid into the reactor and mix, then heat to 130℃;

[0039] 2. Add 0.5% of the mass of the mixture in step 1 as a p-toluenesulfonic acid catalyst, mix, and react at 130-160°C for 3 hours. Stop when the acid value is <10 mgKOH / g;

[0040] 3. Cool to 80°C, add acrylic acid (molar ratio of 1:1.05 to total hydroxyl groups) and 0.03% hydroquinone as a polymerization inhibitor, and control the temperature at 100-110°C to react until the acid value reaches <10 mgKOH / g to obtain a hyperbranched polyester acrylate prepolymer (hydroxyl value approximately 80-100 mgKOH / g). During the acrylation, maintain a nitrogen flow rate of >0.5 L / min to prevent double bond oxidation.

[0041] The composite photoinitiator is prepared by mixing 2-hydroxy-2-methyl-1-phenyl-1-propanone and 4,4'-dimethyldiphenyliodonium hexafluoroantimonate in a mass ratio of 2:1.

[0042] The method for preparing the fast low-temperature curing photosensitive resin provided in this embodiment is as follows:

[0043] Step 1, mixing the hyperbranched polyester acrylate prepolymer and the reactive diluent at 40-50° C.

[0044] Step 2: Add nano-silica and disperse at a high speed of 2000-3000 rpm for 30 minutes;

[0045] In step 3, a composite photoinitiator, leveling agent, and defoaming agent are added, and vacuum degassing is performed to obtain the finished product. During the three-roll milling process, the roller spacing is set to 30 μm, the milling frequency is 4 times, the ultrasonic dispersion frequency is 40 kHz, and the time is 1 hour. The uniformity of the nanoparticle dispersion is ensured to reach D90 < 200 nm, thus obtaining a fast low-temperature curing photosensitive resin.

[0046] <Example 2>

[0047] A fast low-temperature curing photosensitive resin

[0048] This embodiment provides a fast, low-temperature curing photosensitive resin, which includes, by weight, 55 parts of a hyperbranched polyester acrylate prepolymer, 5 parts of a composite photoinitiator, 8 parts of nano-silica (particle size 20 nm), 35 parts of diethyl itaconate diluent, 0.8 parts of a leveling agent (BYK-333), and 0.3 parts of a defoaming agent (BYK-055).

[0049] The composition and preparation method of the hyperbranched polyester acrylate prepolymer are the same as those in Example 1.

[0050] The composite photoinitiator is prepared by mixing 2-hydroxy-2-methyl-1-phenyl-1-propanone and 4,4'-dimethyldiphenyliodonium hexafluoroantimonate in a mass ratio of 2:1.

[0051] The method for preparing the fast low-temperature curing photosensitive resin provided in this embodiment is as follows:

[0052] Step 1, mixing the hyperbranched polyester acrylate prepolymer and the reactive diluent at 40-50° C.

[0053] Step 2: Add nano-silica and disperse at a high speed of 2000-3000 rpm for 30 minutes;

[0054] In step 3, a composite photoinitiator, leveling agent, and defoaming agent are added, and vacuum degassing is performed to obtain the finished product. During the three-roll milling process, the roller spacing is set to 15 μm, the milling frequency is 5, the ultrasonic dispersion frequency is 40 kHz, and the time is 1 hour. The uniformity of the nanoparticle dispersion is ensured to reach D90 < 200 nm, thus obtaining a fast low-temperature curing photosensitive resin.

[0055] <Example 3>

[0056] A fast low-temperature curing photosensitive resin

[0057] This embodiment provides a fast, low-temperature curing photosensitive resin, which includes, by weight, 50 parts of a hyperbranched polyester acrylate prepolymer, 7 parts of a composite photoinitiator, 15 parts of nano-silica (particle size 20 nm), 35 parts of a diluent (epoxy acrylate: diethyl itaconate mass ratio of 3:1), 0.8 parts of a leveling agent (BYK-333), and 0.3 parts of a defoaming agent (BYK-055).

[0058] The composition and preparation method of the hyperbranched polyester acrylate prepolymer are the same as those in Example 1.

[0059] The composite photoinitiator is prepared by mixing 2-hydroxy-2-methyl-1-phenyl-1-propanone and 4,4'-dimethyldiphenyliodonium hexafluoroantimonate in a mass ratio of 3:4.

[0060] Step 1, mixing the hyperbranched polyester acrylate prepolymer and the reactive diluent at 40-50° C.

[0061] Step 2: Add nano-silica and disperse at a high speed of 2000-3000 rpm for 30 minutes;

[0062] In step 3, a composite photoinitiator, leveling agent, and defoaming agent are added, and vacuum degassing is performed to obtain the finished product. During the three-roll milling process, the roller spacing is set to 15 μm, the milling frequency is 5, the ultrasonic dispersion frequency is 40 kHz, and the time is 1 hour. The uniformity of the nanoparticle dispersion is ensured to reach D90 < 200 nm, thus obtaining a fast low-temperature curing photosensitive resin.

[0063] <Example 4>

[0064] A fast low-temperature curing photosensitive resin

[0065] This embodiment provides a fast, low-temperature curing photosensitive resin, which includes, by weight, 55 parts of a hyperbranched polyester acrylate prepolymer, 5 parts of a composite photoinitiator, 8 parts of functionalized nano-silica (particle size 20 nm), 35 parts of diethyl itaconate diluent, 0.8 parts of a leveling agent (BYK-333), and 0.3 parts of a defoaming agent (BYK-055).

[0066] The composition and preparation method of the hyperbranched polyester acrylate prepolymer are the same as those in Example 1.

[0067] The preparation method of the functionalized nano-silica is as follows:

[0068] 1. Raw Materials Preparation

[0069] Nano-SiO2 (VN3 type, particle size 20-30 nm, Degussa);

[0070] γ-Methacryloxypropyltrimethoxysilane (KH-570);

[0071] Ethanol, deionized water, hydrochloric acid (for pH adjustment);

[0072] 2. Preparation Method

[0073] 1) Mix ethanol and deionized water in a mass ratio of 9:1, and add hydrochloric acid dropwise to adjust the pH to 4.0-4.5;

[0074] 2) Add 1% of the total mass of the solution, KH-570, and stir for 8-10 hours to allow KH-570 to fully hydrolyze into silanols;

[0075] 3) Add nano-SiO2 into the hydrolyzate at a mass of 9 times that of KH-570 and heat to 70-75°C;

[0076] 4) React for 8-10 hours under stirring at 500-600 r / min; the grafting efficiency can be optimized by adding KH-570 stepwise or adding a small amount of catalyst (such as ammonia).

[0077] 5) After the reaction is completed, the mixture is extracted with ethanol using a Soxhlet extractor for 24 hours to remove physically adsorbed KH-570.

[0078] 6) The extracted product was dried in a forced air drying oven at 80°C for 24 hours to obtain grafted SiO2 powder (GS). The grafting rate was calculated by thermogravimetric analysis (TGA) to be 20%.

[0079] The composite photoinitiator is prepared by mixing 2-hydroxy-2-methyl-1-phenyl-1-propanone and 4,4'-dimethyldiphenyliodonium hexafluoroantimonate in a mass ratio of 2:1.

[0080] The method for preparing the fast low-temperature curing photosensitive resin provided in this embodiment is as follows:

[0081] Step 1, mixing the hyperbranched polyester acrylate prepolymer and the reactive diluent at 40-50° C.

[0082] Step 2: Add nano-silica and disperse at a high speed of 2000-3000 rpm for 30 minutes;

[0083] In step 3, a composite photoinitiator, leveling agent, and defoaming agent are added, and vacuum degassing is performed to obtain the finished product. During the three-roll milling process, the roller spacing is set to 15 μm, the milling frequency is 5, the ultrasonic dispersion frequency is 40 kHz, and the time is 1 hour. The uniformity of the nanoparticle dispersion is ensured to reach D90 < 200 nm, thus obtaining a fast low-temperature curing photosensitive resin.

[0084] <Test Example>

[0085] Functional tests were performed on the fast low-temperature curing photosensitive resins prepared in Examples 1-4. The test methods are shown in Table 1:

[0086] Table 1

[0087] Test items Standard method tensile strength ASTM D638 speed 5mm / min Type III specimen Volume resistivity ASTM D257 electrode spacing 2mm 500V DC Curing depth <![CDATA[ISO 4049光源波长385nm,辐照度80mW / cm 2 ]]> Dispersion uniformity ISO 13320 Laser Diffraction Method Low temperature stability IEC 60068-2-1 Cold shock Interlayer bonding strength ASTM D3164 lap shear rate 1mm / min Temperature stability IEC 60068-2-14 -40℃~80℃ cycle 10 times flexibility ASTM D522 tapered mandrel bending without cracks Curing efficiency at 25℃ ISO 11357 DSC method Curing shrinkage GB / T 36800.1-2018 Laser Displacement Sensor Online Monitoring Low temperature impact strength ISO 179-1 Charpy impact test, precooled at -20℃ for 2h Viscosity (mPa·s, 25°C) ISO 2555 rotor speed 20 rpm, 25°C

[0088] The test results of the fast low-temperature curing photosensitive resins of Examples 1-4 are shown in Table 2.

[0089] Table 2

[0090] Test items Example 1 Example 2 Example 3 Example 4 Tensile strength (MPa) 68.5 72.3 67.6 72.5 Volume resistivity (Ω·cm) <![CDATA[9.5*10 13 ]]> 1.2*10 14 ]]> <![CDATA[1.5*10 14 ]]> <![CDATA[1.6*10 14 ]]> Curing depth (um) 160 180 150 165 Dispersion uniformity Uniform dispersion Uniform dispersion Uniform dispersion Uniform dispersion Low temperature stability (-20℃) No change No change No change No change Interlayer bonding strength (MPa) 13.9 13.8 13.5 13.7 Temperature stability (△T=50℃) No deformation No deformation No deformation No deformation Flexibility (bending radius mm) 3.2 3.1 3.5 3.1 25℃ curing efficiency (s / layer) 16 12 15 11 Curing shrinkage (%) 1.8 1.9 1.7 1.3 Low temperature impact strength (kJ / m 2 ) 9.8 11.0 10.3 11.2 Viscosity (mPa·s, 25°C) 760 720 660 690

[0091] Functions and Effects of the Embodiments

[0092] The test data from the examples clearly demonstrate that the fast-curing photosensitive resins prepared in Examples 1-4 of the present invention exhibit excellent interlayer bonding, high curing efficiency, short curing times, strong mechanical properties, and good low-temperature adaptability. Furthermore, a comparison of Examples 2 and 4 with Examples 1 and 3 reveals that the hyperbranched polyester acrylate prepolymer significantly improves mechanical properties. A comparison of the curing shrinkage of Examples 1-4 reveals that functionalized nano-silica significantly improves the curing efficiency and curing shrinkage of the resin, while also contributing to further improvements in the resin's mechanical properties.

[0093] The above embodiments are preferred examples of the present invention and are not intended to limit the scope of protection of the present invention.

Claims

1. A fast low-temperature curing photosensitive resin, characterized in that: Including by weight: 40-70 parts of hyperbranched polyester acrylate prepolymer, 2-8 parts of composite photoinitiator, 5-15 parts of nano-silicon dioxide, 20-40 parts of active diluent, 0.5-2 parts of leveling agent and 0.1-1 parts of defoaming agent, Wherein, the composite photoinitiator includes an α-hydroxyketone compound and a diaryl iodonium salt compound.

2. The rapid low-temperature curing photosensitive resin according to claim 1, characterized in that: in, The composite photoinitiator consists of 1-3 parts by weight of an α-hydroxyketone compound and 1-2 parts by weight of a diaryliodonium salt compound.

3. The rapid low-temperature curing photosensitive resin according to claim 1, characterized in that: in, The composite photoinitiator consists of 1-3 parts by weight of 2-hydroxy-2-methyl-1-phenyl-1-propanone and 1-2 parts by weight of 4,4'-dimethyldiphenyliodonium hexafluoroantimonate.

4. The rapid low-temperature curing photosensitive resin according to claim 1, characterized in that: in, The nano-silica is functionalized nano-silica with gamma-methacryloxypropyltrimethoxysilane grafted on the surface.

5. The rapid low-temperature curing photosensitive resin according to claim 4, characterized in that: in, The grafting rate of the functionalized nano-silicon dioxide is 15-25%.

6. The rapid low-temperature curing photosensitive resin according to claim 4, characterized in that: in, The particle size of the functionalized nano-silica is 20-30 nm.

7. The rapid low-temperature curing photosensitive resin according to claim 1, characterized in that: in, The reactive diluent is selected from epoxy acrylate and / or itaconate.

8. The rapid low-temperature curing photosensitive resin according to claim 1, characterized in that: The preparation method comprises the following steps: The hyperbranched polyester acrylate prepolymer is mixed with an active diluent, nano-silicon dioxide is added, dispersed, three-roll milled, ultrasonically dispersed, a composite photoinitiator, a leveling agent and a defoaming agent are added, and vacuum degassing is performed to obtain the product.

9. The rapid low-temperature curing photosensitive resin according to claim 8, characterized in that ； The three-roller grinding parameter is that the roller spacing is set to 10-50 μm.

10. The rapid low-temperature curing photosensitive resin according to claim 8, characterized in that ； The ultrasonic dispersion condition is 20-50 kHz and the duration is 1-5 hours.