Light-cured sheet molding compound and preparation method thereof

Abstract

The invention relates to the technical field of composite materials, in particular to a light-cured sheet molding compound and a preparation method thereof. Comprising the following steps: 1, uniformly stirring and mixing vinyl resin, a photoinitiator, tri (N-nitroso-N-phenylhydroxylamine) aluminum salt, an additive and an inorganic filler to obtain resin paste; step 2, adding the resin paste, magnesium oxide and a reinforced matrix material into an SMC unit, and rolling and compacting through a pressure roller to obtain an SMC sheet; and 3, rolling the SMC sheet, thickening at 40-50 DEG C for 12-15 hours, and carrying out light curing to obtain the sheet molding compound. The preparation method has the beneficial effects that the additive is added, the modified titanium dioxide is used in the inorganic filler, and the additive and the modified titanium dioxide jointly act, so that the prepared photocuring sheet can be rapidly cured under ultraviolet light, and construction operation is facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, in particular to a light-curing sheet molding compound and a preparation method thereof. Background Art

[0002] Sheet molding compound (SMC) is a thermoset composite material composed of resin, glass fiber, fillers, and catalysts. Originating in the 1940s, it was initially used in the aviation industry, where it gained popularity for its lightweight and high strength. With technological advancements, SMC's applications have gradually expanded to industries such as automotive, construction, electrical equipment, and sports equipment. SMC offers numerous advantages, including corrosion resistance, heat resistance, excellent electrical insulation, and ease of processing and molding. These properties make it an ideal material for manufacturing automotive parts, electrical insulation components, and structural components.

[0003] Existing sheet molding compounds typically require heating and curing during molding, making them difficult to use in some outdoor construction scenarios, such as pipeline repair and insulation layer installation. Therefore, to address the above problems, the present invention prepares a light-curing sheet molding compound. Summary of the Invention

[0004] The object of the present invention is to provide a photocurable sheet molding compound and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] More optimally, the light-curing sheet molding compound includes the following components: 200-300 parts of resin matrix, 50-100 parts of additives, 1-2 parts of photoinitiator, 1-2 parts of polymerization inhibitor, 300-400 parts of inorganic filler, 2-5 parts of thickener, and 100-450 parts of reinforcing matrix material.

[0007] More optimally: the resin matrix includes one or more of unsaturated polyester and vinyl resin; the photoinitiator includes one or more of benzyl, alkyl phenone, benzophenone, thioxanthone, diazonium salt, and dialkyl iodonium salt; the polymerization inhibitor is tris(N-nitroso-N-phenylhydroxylamine) aluminum salt; the thickener includes one or more of calcium oxide, magnesium oxide, calcium hydroxide, and magnesium hydroxide; the reinforcing matrix material includes one or more of chopped fibers, chopped fiber fabrics, chopped fibers, and chopped fiber fabrics.

[0008] More optimally: the preparation method of the additive is as follows: (1) stirring pentaerythritol and potassium methoxide at 50-60°C for 1-2 hours, heating to 95-100°C under a protective atmosphere, slowly adding glycerol monomer, stirring for 3-4 hours, separating and drying to obtain intermediate A; (2) mixing DMAP, intermediate A, and 2-hydroxy-4-pentenoic acid and adding them to dichloromethane, then adding DCC, reacting at 30-40°C for 40-50 minutes, separating and drying to obtain the additive.

[0009] More optimally, the intermediate A comprises the following components: by weight, 0.1-0.2 parts of pentaerythritol, 0.4-0.5 parts of potassium methoxide, and 11-13 parts of glycerol monomer; the additive comprises the following components: by weight, 20-22 parts of intermediate A and 18-20 parts of 2-hydroxy-4-pentenoic acid.

[0010] More optimally, the inorganic filler is a composition of calcium carbonate and modified titanium dioxide, and the mass ratio of calcium carbonate to modified titanium dioxide is 1:(1.2-1.5).

[0011] More optimized: The preparation method of the modified titanium dioxide is as follows: (1) salicylaldehyde, acrylonitrile and triethylenediamine are mixed, reacted at 140-150°C for 30-50 minutes, and a yellow solid is separated; (2) the yellow solid is mixed with sodium hydroxide, stirred and refluxed for 3-5 hours, adjusted to pH 3-4 with hydrochloric acid, and filtered and dried; the obtained solid and dichlorothionyl are refluxed for 1.5-2 hours, and evaporated to dryness under reduced pressure to obtain intermediate B; (3) intermediate B and vigabatrin are mixed and refluxed for 1.5-2 hours, and evaporated to dryness under reduced pressure to obtain intermediate B. , tetrahydrofuran, add triethylamine, stir at room temperature for 3-4h, extract, elute, recrystallize to obtain a modifier; (4) dissolve nano titanium dioxide in toluene, add γ-aminopropyltriethoxysilane under a protective atmosphere, react at 80-90°C for 4-5h, and dry to obtain amino titanium dioxide; (5) dissolve amino titanium dioxide in ethyl acetate, add a modifier and benzenesulfonic acid, react at 60-70°C for 4-5h, filter, wash and dry to obtain modified titanium dioxide.

[0012] More optimally, the yellow solid comprises the following components: 1-2 parts of salicylaldehyde, 1-2 parts of acrylonitrile, and 0.5-0.6 parts of triethylenediamine, by weight; the modifier comprises the following components: 1-2 parts of intermediate B and 1-2 parts of vigabatrin, by weight; the amination titanium dioxide comprises the following components: 5-6 parts of nano-titanium dioxide and 8-10 parts of γ-aminopropyltriethoxysilane, by weight; and the modified titanium dioxide comprises the following components: 1-2 parts of amination titanium dioxide, 1-2 parts of modifier, and 0.5-0.7 parts of benzenesulfonic acid, by weight.

[0013] More optimally: comprising the following steps:

[0014] Step 1: Stir and mix the resin matrix, photoinitiator, polymerization inhibitor, additives, and inorganic filler to obtain a resin paste;

[0015] Step 2: Add the resin paste, thickener and reinforcing matrix material into the SMC unit and compact them with a pressure roller to obtain SMC sheet;

[0016] Step 3: Roll up the SMC sheet and thicken it at 40-50°C for 12-15 hours to obtain the finished product.

[0017] More optimally, the finished product can be photocured to obtain a sheet molding compound.

[0018] The present invention adds additives and uses modified titanium dioxide in the inorganic filler. The combined effect of the two enables the prepared light-cured sheet to be rapidly cured under ultraviolet light. The details are as follows:

[0019] First, the additive prepared in this invention is a polyhydroxy compound. The hydroxyl functional groups can react with multiple free radicals to form a large number of crosslinking points, increasing the crosslink density of the cured network. Furthermore, the terminal olefinic groups enable good polymerization with vinyl resins, improving the mechanical strength of the material. Furthermore, the high number of hydroxyl groups enhances ultraviolet light absorption, increasing the activity of the photoinitiator and reducing the curing time. Furthermore, the additive is a macromolecular substance, which can reduce the fluidity of the resin during processing and improve the quality of the final product.

[0020] Second, nano-titanium dioxide primarily absorbs UVB, which has a limited effect on the sheet's curing under ultraviolet light. Therefore, the present invention first modifies the nano-titanium dioxide with a silane coupling agent, grafting amino groups onto its surface. The modified titanium dioxide then reacts with a synthesized modifier to produce the modified titanium dioxide. The modified titanium dioxide has a pyran structure, and the conjugated system formed by its double bonds and oxygen atoms can absorb ultraviolet or visible light and act as an energy donor, transferring energy to the active center of the photoinitiator, promoting the photochemical reaction and improving the sheet's curing efficiency. Furthermore, the chemical molecules grafted onto the nano-titanium dioxide have terminal olefin groups, which enable good polymerization with vinyl resins, effectively increasing the material's strength.

[0021] Third, the absorption wavelength range of phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO184) is 360-410nm; the absorption wavelength range of 1-hydroxycyclohexyl phenyl ketone is 244-350nm. The combination of the two expands the wavelength range of light curing and thus increases the curing speed. DETAILED DESCRIPTION

[0022] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0023] Preparation of additives:

[0024] (1) 0.1 parts of pentaerythritol were placed in a three-necked round-bottom flask equipped with a septum and a mechanical stirrer and connected to a vacuum line. 0.4 parts of potassium methoxide were then added and stirred at 50°C for 1 hour. After deprotonation, methanol was removed in vacuo and the solution was heated to 95°C under a nitrogen atmosphere. 11 parts of glycerol monomer were then added to the dosing plastic at 2 ml / L using a syringe pump, stirred for 3 hours, cooled to room temperature, passed through an ion exchange column filled with cations, and dried in vacuo at 80°C to obtain intermediate A.

[0025] (2) 3 parts of DMAP, 20 parts of intermediate A, and 18 parts of 2-hydroxy-4-pentenoic acid were mixed and added to dichloromethane, and then 30 parts of DCC were added. The mixture was reacted at 30° C. for 40 minutes, and the additive was separated and dried to obtain the additive.

[0026] Preparation of modified titanium dioxide:

[0027] (1) 1 part salicylaldehyde and 1 part acrylonitrile were reacted in a microwave synthesizer at 140°C for 30 min. After cooling, the mixture was removed and an appropriate amount of dichloromethane was added. The mixture was separated by column chromatography using petroleum ether and ethyl acetate in a volume ratio of 5:1 as eluents to obtain a yellow solid.

[0028] (2) Place one portion of the yellow solid in a round-bottom flask, add 20 mL of a 5 mol / L sodium hydroxide solution, and stir under reflux for 3 h. Cool to room temperature, adjust the pH to 3 with 4 mol / L hydrochloric acid, then add 6 mL of thionyl chloride, heat under reflux for 1.5 h, and evaporate to dryness under reduced pressure to obtain Intermediate B.

[0029] (3) Dissolve 1 part of intermediate B and 1 part of vigabatrin in tetrahydrofuran, add triethylamine, stir at room temperature for 3-4 hours, extract, elute, and recrystallize to obtain a modifier;

[0030] (4) 5 parts of nano-titanium dioxide were dissolved in toluene, and 8 parts of γ-aminopropyltriethoxysilane were added under nitrogen atmosphere. The mixture was reacted at 80° C. for 4 h and dried to obtain amino-treated titanium dioxide.

[0031] (5) Dissolve 1 part of amino titanium dioxide in ethyl acetate, add 1 part of modifier and 0.5 parts of benzenesulfonic acid, react at 60°C for 4 hours, filter, wash and dry to obtain modified titanium dioxide.

[0032] Example 1: A method for preparing a light-curing sheet molding compound, comprising the following steps:

[0033] Step 1: Add 200 parts of vinyl resin, 2 parts of 1-hydroxycyclohexyl phenyl ketone, and 1 part of tris(N-nitroso-N-phenylhydroxylamine) aluminum salt into a stirring kettle, start stirring, and stir at 800 r / min for 5 minutes, then add 50 parts of additives and 300 parts of inorganic fillers and stir at 1000 r / min for 5 minutes to uniformly mix to obtain a resin paste;

[0034] Step 2: Add 200 parts of resin paste, 3 parts of magnesium oxide, and 300 parts of chopped fibers into the SMC unit and compact them with a pressure roller to obtain an SMC sheet;

[0035] Step 3: Roll up the SMC sheet and thicken it at 40°C for 12 hours to obtain the finished product.

[0036] Example 2: A method for preparing a light-curing sheet molding compound, comprising the following steps:

[0037] Step 1: Add 200 parts of vinyl resin, 2 parts of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and 1 part of tris(N-nitroso-N-phenylhydroxylamine)aluminum salt into a stirring kettle, start stirring, and stir at 800 r / min for 5 minutes, then add 50 parts of additives and 300 parts of inorganic fillers and stir at 1000 r / min for 5 minutes to uniformly mix to obtain a resin paste;

[0038] Step 2: Add 200 parts of resin paste, 3 parts of magnesium oxide, and 300 parts of chopped fibers into the SMC unit and compact them with a pressure roller to obtain an SMC sheet;

[0039] Step 3: Roll up the SMC sheet and thicken it at 40°C for 12 hours to obtain the finished product.

[0040] Example 3: A method for preparing a light-curing sheet molding compound, comprising the following steps:

[0041] Step 1: Add 200 parts of vinyl resin, 2 parts of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 1 part of 1-hydroxycyclohexylphenyl ketone, and 1 part of tris(N-nitroso-N-phenylhydroxylamine)aluminum salt into a stirring kettle, start stirring, and stir at 800 r / min for 5 minutes, then add 50 parts of additives and 300 parts of inorganic fillers and stir at 1000 r / min for 5 minutes to uniformly mix to obtain a resin paste;

[0042] Step 2: Add 200 parts of resin paste, 3 parts of magnesium oxide, and 300 parts of chopped fibers into the SMC unit and compact them with a pressure roller to obtain an SMC sheet;

[0043] Step 3: Roll up the SMC sheet and thicken it at 40°C for 12 hours to obtain the finished product.

[0044] Example 4: A method for preparing a light-curing sheet molding compound, comprising the following steps:

[0045] Step 1: Add 200 parts of vinyl resin, 2 parts of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 1 part of 1-hydroxycyclohexylphenyl ketone, and 1 part of tris(N-nitroso-N-phenylhydroxylamine)aluminum salt into a stirring kettle, start stirring, and stir at 800 r / min for 5 minutes, then add 50 parts of additives and 300 parts of inorganic fillers and stir at 1000 r / min for 5 minutes to uniformly mix to obtain a resin paste;

[0046] Step 2: Mix 200 parts of resin paste, 3 parts of magnesium oxide, 300 parts of chopped strand mat (450g / m 2 ) is added to the SMC unit and compacted by a pressure roller to obtain an SMC sheet;

[0047] Step 3: Roll up the SMC sheet and thicken it at 40°C for 12 hours to obtain the finished product.

[0048] Comparative Example 1: No additives were added, and the rest was the same as Example 4, specifically as follows:

[0049] Step 1: Add 200 parts of vinyl resin, 2 parts of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 1 part of 1-hydroxycyclohexylphenyl ketone, and 1 part of tris(N-nitroso-N-phenylhydroxylamine)aluminum salt into a stirring kettle, start stirring, stir at 800 r / min for 5 minutes, then add 300 parts of inorganic filler and stir at 1000 r / min for 5 minutes to uniformly mix to obtain a resin paste;

[0050] Step 2: Mix 200 parts of resin paste, 3 parts of magnesium oxide, 300 parts of chopped strand mat (450g / m 2 ) is added to the SMC unit and compacted by a pressure roller to obtain an SMC sheet;

[0051] Step 3: Roll up the SMC sheet and thicken it at 40°C for 12 hours to obtain the finished product.

[0052] Comparative Example 2: Aluminum hydroxide was added alone to the inorganic filler, and the rest was the same as in Example 4, specifically as follows:

[0053] Step 1: Add 200 parts of vinyl resin, 2 parts of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 1 part of 1-hydroxycyclohexylphenyl ketone, and 1 part of tris(N-nitroso-N-phenylhydroxylamine)aluminum salt into a stirring kettle, start stirring, stir at 800 r / min for 5 minutes, then add 300 parts of aluminum hydroxide and stir at 1000 r / min for 5 minutes, and mix evenly to obtain a resin paste;

[0054] Step 2: Mix 200 parts of resin paste, 3 parts of magnesium oxide, 300 parts of chopped strand mat (450g / m 2 ) is added to the SMC unit and compacted by a pressure roller to obtain an SMC sheet;

[0055] Step 3: Roll up the SMC sheet and thicken it at 40°C for 12 hours to obtain the finished product.

[0056] Experiment: The finished products obtained in the examples and comparative examples were placed under ultraviolet light and the time required for complete curing was measured. The tensile strength of the cured sheet molding compounds obtained in the examples and comparative examples was measured according to GB8410-2006. The measured data are shown in the following table:

[0057] project Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Curing time / min 4.5 5 3 3 8.4 9.5 Tensile strength / Mpa 123 115 116 117 100 105

[0058] Table 1

[0059] Conclusion: Examples 1-4, by adding additives and using modified titanium dioxide as an inorganic filler, achieve a combined effect that allows the resulting UV-curable sheets to cure rapidly under UV light, improving physical properties and facilitating construction. Comparative Example 1, which lacks additives, exhibits increased curing time but decreased tensile strength. Comparative Example 2, which lacks modified titanium dioxide, exhibits increased curing time but decreased tensile strength.

[0060] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A photocurable sheet molding compound, Features: The photocurable sheet molding compound comprises the following components: 200-300 parts of a resin matrix, 50-100 parts of an additive, 1-2 parts of a photoinitiator, 1-2 parts of an inhibitor, 300-400 parts of an inorganic filler, 2-5 parts of a thickener, and 100-450 parts of a reinforcing matrix material.

2. The photocurable sheet molding compound according to claim 1, Features: The resin matrix includes one or more of unsaturated polyester and vinyl resin; the photoinitiator includes one or more of benzil, alkyl phenone, benzophenone, thioxanthone, diazonium salt and dialkyl iodonium salt; the inhibitor is tri(N-nitroso-N-phenylhydroxylamine)aluminum salt; the thickener includes one or more of calcium oxide, magnesium oxide, calcium hydroxide and magnesium hydroxide; the reinforcing matrix material includes one or more of chopped fibers, chopped fiber fabrics, chopped fibers and chopped fiber fabrics.

3. The photocurable sheet molding compound according to claim 1, Features: The preparation method of the additive is as follows: (1) stirring pentaerythritol and potassium methoxide at 50-60° C. for 1-2 hours, heating to 95-100° C. under a protective atmosphere, slowly adding glycerol monomer, stirring for 3-4 hours, separating and drying to obtain an intermediate A; (2) mixing DMAP, intermediate A, and 2-hydroxy-4-pentenoic acid, adding them to dichloromethane, then adding DCC, reacting at 30-40° C. for 40-50 minutes, separating and drying to obtain the additive.

4. The photocurable sheet molding compound according to claim 3, Features: The intermediate A comprises the following components: by weight, 0.1-0.2 parts of pentaerythritol, 0.4-0.5 parts of potassium methoxide, and 11-13 parts of glycerol monomer; the additive comprises the following components: by weight, 20-22 parts of intermediate A and 18-20 parts of 2-hydroxy-4-pentenoic acid.

5. The photocurable sheet molding compound according to claim 1, Features: The inorganic filler is a composition of calcium carbonate and modified titanium dioxide, and the mass ratio of calcium carbonate to modified titanium dioxide is 1:(1.2-1.5).

6. The photocurable sheet molding compound according to claim 5, Features: The preparation method of the modified titanium dioxide comprises: (1) mixing salicylaldehyde, acrylonitrile and triethylenediamine, reacting at 140-150° C. for 30-50 minutes, and separating to obtain a yellow solid; (2) mixing the yellow solid with sodium hydroxide, stirring and refluxing for 3-5 hours, adjusting the pH value to 3-4 with hydrochloric acid, and filtering and drying; refluxing the obtained solid with thionyl chloride for 1.5-2 hours, and evaporating under reduced pressure to obtain an intermediate B; (3) mixing the intermediate B, vigabatrin and tetrahydrocannabinol; and (4) dissolving nano titanium dioxide in toluene, adding γ-aminopropyltriethoxysilane under a protective atmosphere, reacting at 80-90°C for 4-5h, and drying to obtain amino titanium dioxide; (5) dissolving amino titanium dioxide in ethyl acetate, adding the modifier and benzenesulfonic acid, reacting at 60-70°C for 4-5h, filtering, washing, and drying to obtain modified titanium dioxide.

7. The photocurable sheet molding compound according to claim 6, Features: The yellow solid comprises the following components: by weight, 1-2 parts of salicylaldehyde, 1-2 parts of acrylonitrile, and 0.5-0.6 parts of triethylenediamine; the modifier comprises the following components: by weight, 1-2 parts of intermediate B and 1-2 parts of vigabatrin; the amination titanium dioxide comprises the following components: by weight, 5-6 parts of nano titanium dioxide and 8-10 parts of γ-aminopropyltriethoxysilane; The modified titanium dioxide comprises the following components: by weight, 1-2 parts of amino titanium dioxide, 1-2 parts of a modifier, and 0.5-0.7 parts of benzenesulfonic acid.

8. A method for preparing a photocurable sheet molding compound according to any one of claims 1 to 7, Features: The following steps are involved: Step 1: Mix the resin matrix, photoinitiator, polymerization inhibitor, additives and inorganic filler to obtain a resin paste; Step 2: Add the resin paste, thickener and reinforcing matrix material into the SMC unit, and compact them by a pressure roller to obtain an SMC sheet; Step 3: Roll up the SMC sheet and thicken it at 40-50°C for 12-15h to obtain the finished product.

9. A method for preparing a photocurable sheet molding compound according to any one of claim 8, Features: The finished product can be photocured to obtain a sheet molding compound.