UV / thermal dual-curing coating for carbon fiber composite material and preparation method of UV / thermal dual-curing coating

Abstract

The invention relates to the technical field of coatings, in particular to a UV (ultraviolet) / thermal dual-curing coating for a carbon fiber composite material and a preparation method of the UV / thermal dual-curing coating. The UV / thermal dual-curing coating is prepared from various hydroxyl-containing resins and monomers which have better reactivity with isocyanate, and tetrafunctional polyurethane acrylate has high hardness and toughness; the bifunctional polyurethane acrylate has excellent flexibility, the hydroxyl acrylate can generate high reaction with the isocyanate, and the bifunctional monomer 1.6-hexanediol diacrylate containing a small amount of hydroxyl can react with the isocyanate while reducing the viscosity, so that by compounding the raw materials, the viscosity of the polyurethane acrylate is reduced, and the viscosity of the polyurethane acrylate is reduced. The formula can be subjected to secondary thermocuring under different illumination curing conditions, so that the problems of substandard physical properties, poor adhesive force and the like caused by poor illumination of a traditional UV coating in a shadow shielding area of a carbon fiber composite material are solved. Through the UV / thermal dual-curing synergistic effect and nano Al2O3 enhancement, the core properties such as adhesive force, wear resistance and temperature resistance are remarkably superior to those of a traditional single-curing system, and the coating is suitable for carbon fiber composite material coating in the fields of automobiles, aerospace, high-end electronics and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and particularly relates to a UV / thermal dual-curing coating for carbon fiber composites and a preparation method thereof. Background Art

[0002] In recent years, carbon fiber composites have been widely used in many fields. In high-value-added fields, in order to enhance the chemical resistance, weather resistance and other specific properties of carbon fiber composites, paints are usually used for coating protection. However, traditional paints cannot be used because of their poor chemical resistance, long drying time resulting in low production efficiency, high VOC emissions and environmental unfriendliness. UV paints can be widely used on high-value-added carbon fiber composites due to their high solid content, low VOC emissions, high hardness, excellent chemical resistance, fast curing speed and high production efficiency.

[0003] However, it is found in the actual use of UV that most high-value-added carbon fiber composites have irregular shapes (such as carbon fiber bicycle frames, carbon fiber drone frames, carbon fiber cue sticks, rackets, etc.), so ultraviolet light cannot completely irradiate the shadow shielding area, resulting in incomplete curing of some coatings and affecting the physical properties of the coatings. The main manifestations are poor hardness and unqualified physical properties. In severe cases, there will be various problems such as sticky paint film and poor adhesion.

[0004] In view of the above technical pain points, it is necessary to develop a UV / thermal dual-curing coating for carbon fiber composites. Summary of the Invention

[0005] The purpose of the present invention is to provide a UV / thermal dual-curing coating for carbon fiber composites and a preparation method thereof in view of the deficiencies in the prior art.

[0006] The purpose of the present invention is achieved by the following technical solutions:

[0007] A UV / thermal dual-curing coating for carbon fiber composites is composed of the following raw materials in parts by weight:

[0008]

[0009] Among them, the tetrafunctional polyurethane acrylate uses the product of Blue Color Road with the model number L-6460.

[0010] Among them, the difunctional polyurethane acrylate uses the product of Guangxin New Materials with the model number LT-6123.

[0011] Among them, the solvent-free high-hydroxyl acrylate uses the product of DIC with the model number ZHB-213.

[0012] The photoinitiator is composed of photoinitiator TPO and photoinitiator 1173 in a mass ratio of (1-2): (8-10).

[0013] Wherein, the defoaming agent is one or both of an organic silicon defoaming agent and an acrylic defoaming agent.

[0014] Wherein, the leveling agent is one or both of an organic silicon leveling agent and an acrylic leveling agent.

[0015] The nano-aluminum oxide is phosphate-coated nano-aluminum oxide, which is specifically obtained by mixing Al2O3 and phosphate in a ratio of (9-10):1 and ball milling for 4-6 hours.

[0016] A method for preparing a UV / thermal dual-curing coating on a carbon fiber composite material, comprising the following process steps:

[0017] Step (1) tetrafunctional polyurethane acrylate, difunctional polyurethane acrylate, solvent-free high hydroxyl acrylate, and 1,6-hexanediol diacrylate are stirred for 20-30 minutes;

[0018] Step (2) continue to add nano-aluminum oxide and continue stirring for 30-40 minutes;

[0019] Finally, in step (3), blocked isocyanate, defoamer, photoinitiator and leveling agent are added in sequence and stirred for 20-30 minutes.

[0020] The stirring speed in steps (1) and (3) is 950-1050 rpm, the stirring speed in step (2) is 1150-1250 rpm, and the temperature in steps (1), (2) and (3) is controlled not to exceed 45 degrees Celsius to avoid premature unblocking of the blocked isocyanate or thermal decomposition of the photoinitiator.

[0021] When developing a high-performance coating, special attention is paid to its application on carbon fiber composite materials. Therefore, adhesion, hardness, wear resistance, and temperature resistance are all key indicators. Tetrafunctional polyurethane acrylate is used as the main resin to provide higher crosslinking density, hardness, and chemical resistance, which is suitable for the high hardness requirements of carbon fiber surfaces; bifunctional groups are used to increase flexibility, balance rigidity, reduce coating brittleness, and improve adhesion to carbon fibers; hydroxyl acrylate provides additional hydroxyl groups, which may serve as thermal curing active sites (reacting with isocyanates), forming polyurethane bonds, enhancing thermal crosslinking density, and improving the tensile strength of the paint film; at the same time, due to its small molecular properties, it can more flexibly penetrate into the micropores on the carbon fiber surface, enhancing the interface anchoring effect; and synergistically with 1,6-hexanediol diacrylate diluent to reduce the viscosity of the resin system.

[0022] 1,6-Hexanediol diacrylate; a highly reactive diluent that improves UV curing speed and crosslinking density. The crosslinked network formed after UV curing provides a support for thermal curing. After the blocked isocyanate is unblocked, it reacts with the hydroxyl group to form an interpenetrating network. The dual curing synergistically enhances the temperature resistance. At the same time, the rigid skeleton provided after curing enhances the "anchoring effect" of Al2O3.

[0023] The addition of nano-Al2O3 significantly improves hardness, wear resistance and high temperature resistance (carbon fiber components often need to withstand environments above 120°C). The phosphate groups chelate with the Al2O3 surface, enhancing the interfacial bonding with the polar surface of the carbon fiber, thereby indirectly improving adhesion.

[0024] The leveling agent can be silicone leveling agent TEGO 245. The defoamer can be BYK-1796 silicone defoamer. The blocked isocyanate can be product model 75-13-8 from Hubei Xinyuhong Biopharmaceutical Technology Co., Ltd.

[0025] The combination of blocked isocyanate and hydroxyl resin ensures the crosslinking density of heat curing and realizes the synergistic effect of UV / heat dual curing. The mechanism of action of the present invention: First, the UV curing stage: the photoinitiator triggers the polymerization of acrylate double bonds to form a preliminary crosslinking network (curing in seconds). At this time, the blocked isocyanate remains stable and does not participate in the reaction; then the heat curing stage: heating to the unblocking temperature, the blocked isocyanate releases -NCO, and reacts with the hydroxyl group to form a polyurethane network. The light-curing network and the heat-curing network form an interpenetrating structure (IPN), which synergistically improves hardness, temperature resistance and adhesion.

[0026] Beneficial effects of the present invention: The present invention targets the characteristics of carbon fiber composite materials and utilizes a variety of hydroxyl-containing resin monomers, all of which have good reactivity with isocyanate. Tetrafunctional polyurethane acrylate has high hardness and toughness, and difunctional polyurethane acrylate has excellent flexibility. Secondly, hydroxyl acrylate can react highly with isocyanate. The difunctional monomer 1,6-hexanediol diacrylate containing a small amount of hydroxyl can react with isocyanate while reducing viscosity. Through the compounding of the above raw materials, the formula can be subjected to secondary heat curing under different light curing conditions, thereby achieving the best physical properties. This can solve various problems of traditional UV coatings such as substandard physical properties and poor adhesion caused by poor lighting in the shadowed areas of carbon fiber composite materials. Ultimately, the present invention significantly outperforms traditional single-curing systems in core properties such as adhesion, wear resistance, and temperature resistance through the synergistic effect of UV / heat dual curing and enhancement of nano-Al2O3, making it suitable for coating carbon fiber composite materials in the fields of automobiles, aerospace, and high-end electronics. DETAILED DESCRIPTION

[0027] The present invention is further described with reference to the following examples.

[0028] Example 1

[0029] A UV / heat dual-curing coating on a carbon fiber composite material, comprising the following raw materials in parts by weight:

[0030]

[0031]

[0032] The tetrafunctional polyurethane acrylate is a product of Lancolu model L-6460.

[0033] Among them, the bifunctional polyurethane acrylate adopts the product model LT-6123 of Guangxin New Materials.

[0034] The solvent-free high-hydroxy acrylate is a product of DIC model ZHB-213.

[0035] The photoinitiator is composed of photoinitiator TPO and photoinitiator 1173 in a mass ratio of 1:8. The nano-alumina is phosphate-coated nano-alumina, which is obtained by mixing Al2O3 and phosphate in a mass ratio of 9:1 and ball milling for 4 hours.

[0036] The leveling agent used was the silicone leveling agent TEGO 245. The defoamer used was BYK-1796 silicone defoamer. The blocked isocyanate used was product model 75-13-8 from Hubei Xinyuhong Biopharmaceutical Technology Co., Ltd.

[0037] A method for preparing a UV / heat-cured coating on a carbon fiber composite material comprises the following process steps: step (1) stirring tetrafunctional polyurethane acrylate, bifunctional polyurethane acrylate, solvent-free high-hydroxyl acrylate, and 1,6-hexanediol diacrylate for 20 minutes;

[0038] Step (2) continue to add nano-aluminum oxide and continue stirring for 30 minutes;

[0039] Finally, in step (3), blocked isocyanate, defoamer, photoinitiator and leveling agent were added in sequence and stirred for 20 minutes.

[0040] The stirring speed in steps (1) and (3) is 950 rpm, the stirring speed in step (2) is 1150 rpm, and the temperature in steps (1), (2) and (3) is controlled not to exceed 45 degrees Celsius to avoid premature unblocking of the blocked isocyanate or thermal decomposition of the photoinitiator.

[0041] Example 2

[0042] A UV / heat dual-curing coating on a carbon fiber composite material, comprising the following raw materials in parts by weight:

[0043]

[0044]

[0045] The tetrafunctional polyurethane acrylate is a product of Lancolu model L-6460.

[0046] The bifunctional polyurethane acrylate is a product of Guangxin New Materials with the model number LT-6123. The solvent-free high-hydroxy acrylate is a product of DIC with the model number ZHB-213.

[0047] The photoinitiator is composed of photoinitiator TPO and photoinitiator 1173 in a mass ratio of 1:4. The nano-alumina is phosphate-coated nano-alumina, which is obtained by mixing Al2O3 and phosphate in a mass ratio of 10:1 and ball milling for 5 hours.

[0048] The leveling agent used is the silicone leveling agent TEGO 245. The defoaming agent used is BYK-1796 silicone defoaming agent. The blocked isocyanate used is the product model 75-13-8 produced by Hubei Xinyuhong Biopharmaceutical Technology Co., Ltd. A method for preparing a UV / heat-curing dual-curing coating on a carbon fiber composite material, comprising the following process steps: Step (1) stirring tetrafunctional polyurethane acrylate, bifunctional polyurethane acrylate, solvent-free high-hydroxyl acrylate, and 1,6-hexanediol diacrylate for 25 minutes;

[0049] Step (2) continue to add nano-aluminum oxide and continue stirring for 35 minutes;

[0050] Finally, in step (3), blocked isocyanate, defoamer, photoinitiator and leveling agent were added in sequence and stirred for 25 minutes.

[0051] The stirring speed in steps (1) and (3) is 1000 rpm, the stirring speed in step (2) is 1200 rpm, and the temperature in steps (1), (2) and (3) is controlled not to exceed 45 degrees Celsius to avoid premature unblocking of the blocked isocyanate or thermal decomposition of the photoinitiator.

[0052] Example 3

[0053] A UV / heat dual-curing coating on a carbon fiber composite material, comprising the following raw materials in parts by weight:

[0054]

[0055]

[0056] The tetrafunctional polyurethane acrylate is a product of Lancolu model L-6460.

[0057] The bifunctional polyurethane acrylate is a product of Guangxin New Materials with the model number LT-6123. The solvent-free high-hydroxy acrylate is a product of DIC with the model number ZHB-213.

[0058] The photoinitiator is composed of photoinitiator TPO and photoinitiator 1173 in a mass ratio of 1:10. The nano-alumina is phosphate-coated nano-alumina, specifically obtained by mixing Al2O3 and phosphate in a mass ratio of 9:1 and ball milling for 6 hours.

[0059] The leveling agent used is the silicone leveling agent TEGO 245. The defoaming agent used is BYK-1796 silicone defoaming agent. The blocked isocyanate used is the product model 75-13-8 produced by Hubei Xinyuhong Biopharmaceutical Technology Co., Ltd. A method for preparing a UV / heat-curing dual-curing coating on a carbon fiber composite material, comprising the following process steps: Step (1) stirring tetrafunctional polyurethane acrylate, bifunctional polyurethane acrylate, solvent-free high-hydroxyl acrylate, and 1,6-hexanediol diacrylate for 30 minutes;

[0060] Step (2) continue to add nano-aluminum oxide and continue stirring for 40 minutes;

[0061] Finally, in step (3), blocked isocyanate, defoamer, photoinitiator and leveling agent were added in sequence and stirred for 30 minutes.

[0062] The stirring speed in steps (1) and (3) is 1050 rpm, the stirring speed in step (2) is 1250 rpm, and the temperature in steps (1), (2) and (3) is controlled not to exceed 45 degrees Celsius to avoid premature unblocking of the blocked isocyanate or thermal decomposition of the photoinitiator.

[0063] Comparative Example 1

[0064] The difference between Comparative Example 1 and Example 2 is that no bifunctional polyurethane acrylate is used, and the other components are the same.

[0065] Comparative Example 2

[0066] The difference between Comparative Example 1 and Example 2 is that there is no solvent-free high-hydroxy acrylate, and the other components are the same.

[0067] Comparative Example 3

[0068] The difference between Comparative Example 1 and Example 2 is that 1,6 - hexanediol diacrylate was not used, and other components are the same.

[0069] The coatings of Examples 1 - 3 and Comparative Examples 1 - 3 of the present invention were subjected to experimental tests. For UV curing: A 365 nm LED light source was used with an energy of 800 - 1000 mJ / cm 2 , and the irradiation time was 3 - 8 seconds to ensure rapid surface setting. For thermal curing: Bake at 80 - 120 °C for 20 - 40 minutes to complete deep cross - linking. The experimental data for each item are shown in Table 1.

[0070] Table 1

[0071]

[0072] Through analysis of the above table, in Comparative Example 1, bifunctional polyurethane acrylate was not used. This is because the toughening effect of the bifunctional resin is lacking, the brittleness of the coating increases, and the interfacial stress concentration leads to a significant reduction in adhesion; the brittle coating is prone to micro - cracks, and the abrasion amount increases significantly; the excessive rigidity causes the thermal stress to be unable to be released, and the adhesion decreases severely at high temperatures. In Comparative Example 2, high - hydroxyl acrylate was not used. This is because the number of hydroxyl groups decreases, the reaction sites of blocked isocyanate are insufficient, the thermal curing network is incomplete, and the heat resistance and adhesion decrease; the low cross - linking density leads to a decrease in the hardness of the coating. In Comparative Example 3, HDDA was not used. This is because the absence of HDDA leads to too high viscosity, uneven dispersion of nano - Al2O3, and insufficient UV curing cross - linking density; the low cross - linking density leads to a decrease in wear resistance; the number of double bonds decreases, and the UV curing network is loose.

[0073] Examples 1 - 3 of the present invention have the best comprehensive performance through the synergistic effect of tetra - functional resin (hardness), bifunctional resin (toughness), HDDA (cross - linking density), and high - hydroxyl acrylate (thermal curing).

[0074] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present invention, rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A UV / thermal dual-curing coating on carbon fiber composite materials, characterized in that: It consists of the following raw materials in parts by weight:

2. The UV / thermal dual-curing coating on the carbon fiber composite material according to claim 1, wherein: The tetrafunctional polyurethane acrylate uses the product of Bluecol's model L-6460.

3. The UV / thermal dual-curing coating on a carbon fiber composite material according to claim 1, characterized in that: The difunctional polyurethane acrylate uses the product of Guangxin New Materials' model LT-6123.

4. A UV / thermal dual-curing coating on a carbon fiber composite material according to claim 1, characterized in that: The solvent-free high-hydroxyl acrylate uses the product of DIC's model ZHB-213.

5. A UV / thermal dual-curing coating on a carbon fiber composite material, characterized in that: The photoinitiator consists of photoinitiator TPO and photoinitiator 1173 with a mass ratio of (1-2):(8-10).

6. A UV / thermal dual-curing coating on a carbon fiber composite material according to claim 1, characterized in that: The defoamer is one or two of silicone defoamers and acrylic defoamers.

7. A UV / thermal dual-curing coating on a carbon fiber composite material according to claim 1, characterized in that: The leveling agent is one or two of silicone leveling agents and acrylic leveling agents.

8. The UV / thermal dual-curing coating on a carbon fiber composite material according to claim 1, wherein: The nano-aluminum oxide is phosphate-coated nano-aluminum oxide, specifically obtained by mixing Al2O3 and phosphate in a ratio of (9-10):1 and ball milling for 4-6 hours.

9. The preparation method of a UV / thermal dual-curing coating on a carbon fiber composite material according to claim 1, characterized in that: It includes the following process steps: Step (1): Stir the tetrafunctional polyurethane acrylate, difunctional polyurethane acrylate, solvent-free high-hydroxyl acrylate, and 1,6-hexanediol diacrylate for 20-30 min. Step (2): Continuously add nano-aluminum oxide and continue stirring for 30-40 min. Step (3): Finally, sequentially add blocked isocyanate, defoamer, photoinitiator, and leveling agent and stir for 20-30 min.

10. A method for preparing a UV / thermal dual-curing coating on a carbon fiber composite material according to claim 9, characterized in that: The stirring speed in steps (1) and (3) is 950-1050 revolutions per minute, the stirring speed in step (2) is 1150-1250 revolutions per minute, and the temperature in steps (1), (2), and (3) is controlled not to exceed 45 °C.

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