A water-based dual-curing matte touch coating, a preparation method and application thereof

Abstract

The application discloses a kind of water-based double-cured matt hand feel coating and its preparation method and application, including coating component and curing agent component, the preparation raw material of the coating component includes the following components by weight parts: water-based elastic resin 20~30 parts, water-based six functional group aliphatic polyurethane acrylic emulsion 40~50 parts, photo initiator 1~3 parts, solvent 3~8 parts and water 15~35 parts.The water-based six functional group aliphatic polyurethane acrylic emulsion can be surface cured under 254nm excimer lamp, and through excimer curing+UV curing+post-curing process, realize super-matt effect.The water-based double-cured matt hand feel coating obtained by the application has the characteristics of smooth film, good elasticity, good adhesion, good stain resistance, good wear resistance, etc.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coatings, and particularly relates to a water-based matte touch coating, a preparation method and application thereof. BACKGROUND

[0002] With the improvement of people's environmental awareness, water-based coatings as a more environmentally friendly coating material are accepted by more and more people, and the prospect of water-based coatings is getting better and better. Water-based coatings use water as solvent, saving a lot of resources. Water-based coatings eliminate the fire hazard during construction, reducing air pollution. Water-based coatings only use a small amount of low-toxicity alcohol ether organic solvents, improving the working environment, and significantly reducing pollution and saving resources.

[0003] In the 3C coating market, different terminal brands have different requirements for hand feeling. Some terminal brands like to use UV topcoat, which is smooth and delicate, and has good chemical resistance. Some terminal brands choose to use hand feeling coatings because the touch is more comfortable and soft. No matter which choice is made, the purpose is to obtain the recognition and love of consumers. For 3C products, appearance is one aspect, and performance also needs to meet customer use requirements, such as the use of hand feeling coatings, which is very important for stain resistance and wear resistance, because it can improve the service life of the product and improve the competitiveness of the product.

[0004] However, the performance of the current water-based elastic coating is not as good as that of the oil-based elastic coating, especially the water-based elastic coating prepared by using a general emulsion has poor adhesion on some substrates, poor stain resistance, and poor chemical resistance and wear resistance; which indirectly affects the use of water-based hand feeling paint and the competitiveness of the product; therefore, improving the chemical resistance, wear resistance and stain resistance of the coating has a good market prospect. SUMMARY

[0005] The technical problem to be solved by the present application is to overcome the deficiencies and defects mentioned in the background, provide a water-based matte touch coating, a preparation method and application thereof, solve the problems of poor adhesion, poor stain resistance and poor wear resistance of water-based hand feeling coatings, and obtain super matte effect and good hand feeling.

[0006] To solve the above technical problems, the technical solution provided by the present application is as follows:

[0007] A water-based double-curing matte touch coating, comprising a coating component and a curing agent component, characterized in that the preparation raw materials of the coating component comprise the following components by weight: 20-30 parts of water-based elastic resin, 40-50 parts of water-based six-functional aliphatic polyurethane acrylic emulsion, 1-3 parts of photoinitiator, 3-8 parts of solvent and 15-35 parts of water;

[0008] The water-based elastic resin is a polycarbonate modified polyurethane resin.

[0009] The water-based six-functional aliphatic polyurethane acrylic emulsion is a polyurethane modified acrylic emulsion;

[0010] The curing agent component comprises an oily isocyanate curing agent and a diluent;

[0011] The photo initiator can be excited by 254nm light, so that the water-based six-functional aliphatic polyurethane acrylic emulsion can be surface cured under a 254nm excimer lamp.

[0012] As a further improvement, the coating component further comprises 0.3-0.6 parts of a substrate wetting agent, 1-3 parts of a dispersant, and 0.5-2 parts of an auxiliary agent.

[0013] As a further improvement, the water-based elastic resin has a molecular weight less than 1000 and an OH content of 3.0-3.5wt%.

[0014] As a further improvement, the water-based elastic resin is PCDL 8011 of Asahi Kasei Corporation, and the water-based six-functional aliphatic polyurethane acrylic emulsion is SEAPUR 33G41 of Sichuan Sitong New Material Co., Ltd.

[0015] As a further improvement, the photo initiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0016] As a further improvement, the mass ratio of the coating component to the curing agent component is 100:10-15.

[0017] As a further improvement, the oily isocyanate curing agent is hexamethylene diisocyanate.

[0018] The present application also provides a preparation method of the water-based double-cured matte touch coating, comprising the following steps:

[0019] dissolving the photo initiator in part of the solvent to obtain a photo initiator solution;

[0020] dispersing the water-based elastic resin in part of the water to obtain a mixed solution;

[0021] mixing the water-based six-functional aliphatic polyurethane acrylic emulsion and the photo initiator solution uniformly, then adding the mixed solution, the substrate wetting agent, the dispersant, the auxiliary agent, the remaining solvent, and the remaining water, and stirring and dispersing to obtain the coating component.

[0022] The present application also provides an application of the water-based double-cured matte touch coating, mixing the coating component and the curing agent component, spraying on a substrate surface, and sequentially performing baking, surface curing by a 254nm excimer lamp, deep layer curing by a UV mercury lamp, and post-curing.

[0023] As a further improvement, the baking condition is baking at 55-65 DEG C for 5-10 minutes; and the post-curing condition is drying at 70-80 DEG C for 4-8 hours.

[0024] Compared with the prior art, the present application has the following advantages:

[0025] The water-based double-curing matte hand feel paint of the present application uses a water-based six-functional aliphatic polyurethane acrylic emulsion, and adds a proper amount of a photoinitiator that can be completely excited at 254 nm, so that surface curing can be performed under excitation of the excimer at 254 nm, and deep curing can also be performed by a mercury lamp.

[0026] The water-based elastic resin is added, and since the molecular weight of the water-based elastic resin is less than 1000 and the water-based six-functional aliphatic polyurethane acrylic emulsion has good compatibility, this type of resin has good thickness and flexibility, which is just opposite to the characteristics of the water-based six-functional aliphatic polyurethane acrylic emulsion, and the two have a complementary effect after being mixed. By proper proportioning in the formula, the desired hand feel effect can be obtained. The water-based elastic resin with small molecules also has the characteristics of slow surface drying and easy migration, which is beneficial to the surface "wrinkles" under excimer curing in the water-based double-curing matte hand feel paint of the present application, so that a lower matte effect is obtained.

[0027] However, to achieve the effect of super matte paint (60-degree gloss less than 2 degrees), the "wrinkles" formed by the coating layer are not enough. In fact, the water-based elastic resin is easy to achieve a high gloss appearance due to its high hydroxyl value, and no matte powder or filler is added in the formula of the present application, so to achieve the super matte effect, on the one hand, the present application selects an oily curing agent that is compatible with the water-based elastic resin but has poor compatibility, forming a water-in-oil interface, which can achieve a good extinction effect; this effect can only achieve a gloss of about 5 degrees. To further reduce the gloss of the paint, excimer curing is needed. Therefore, under the action of the two conditions, the gloss of the paint can be reduced to about 1 degree, thereby achieving the super matte effect.

[0028] Since no matte powder or filler is added in the formula, the paint film has very high density, and the curing film is formed by the double-curing process of (excimer curing + UV curing) + post-curing. Since the excimer curing process is added, the water-based double-curing matte hand feel paint has good stain resistance, chemical resistance and wear resistance; and the problems of inconsistent gloss, easy black spots, hard and smooth hand feel and insufficient thickness of pure excimer curing can be overcome.

[0029] Meanwhile, the toughness and elasticity of the paint film are improved due to the addition of the water-based polycarbonate elastic resin, and the strength, hydrophobicity and chemical resistance of the paint are further improved due to the addition of the oil-based curing agent. In combination with the UV coating film cured by the excimer, the water-based double-curing matt hand feel paint has unique silky and thick hand feel and stain resistance.

[0030] Therefore, the water-based double-curing matt hand feel paint obtained by the application has the characteristics of smooth and elastic paint film, good adhesion, good stain resistance and good wear resistance. The adhesion of the water-based double-curing matt hand feel paint is 5B, the hardness is H, the elasticity is fine and smooth, and the oil resistance marker pen is resistant.

[0031] The application of the water-based double-curing matt hand feel paint of the application to the substrate can directly spray the paint component and the curing agent component of the water-based double-curing matt hand feel paint on the surface of the substrate by adding an appropriate amount of water, which is simple to operate, improves the work efficiency in the construction process and reduces the construction cost.

[0032] The paint can also be matched with primer paints for various different substrates, such as single-component water-based paint, water-based PU paint, water-based baking paint and the like. The composite coating after matching has excellent performance of the topcoat and can be used in various fields such as automotive interiors, instrument dials, 3C electronic products and the like. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0034] Figure 1 Figure 1 is a photo of the paint film prepared in Example 1 under a microscope at 200 times magnification. DETAILED DESCRIPTION

[0035] In order to facilitate the understanding of the application, the following will make a more comprehensive and detailed description of the application in combination with the preferred embodiments, but the protection scope of the application is not limited to the following specific embodiments.

[0036] Unless otherwise defined, all the professional terms used in the following have the same meaning as generally understood by those skilled in the art. The professional terms used in the present application are only for the purpose of describing the specific embodiments and are not intended to limit the protection scope of the application.

[0037] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the application can be purchased from the market or can be prepared by the existing method.

[0038] The water-based double-curing matte touch coating of some embodiments of the present application comprises a coating component and a curing agent component, wherein the raw materials for preparing the coating component comprise the following components by weight: 20-30 parts of a water-based elastic resin, 40-50 parts of a water-based six-functional aliphatic polyurethane acrylic emulsion, 0.3-0.6 parts of a substrate wetting agent, 1-3 parts of a dispersing agent, 1-3 parts of a photoinitiator, 0.5-2 parts of an auxiliary agent, 3-8 parts of a solvent, and 15-35 parts of deionized water.

[0039] In some embodiments, the water-based elastic resin is a polycarbonate-modified water-based polyurethane resin. Preferably, it has a solid content of 96-100 wt%, an OH content of 3.0-3.5 wt%, and a number average molecular weight of less than 1000. It can form a stable emulsion when mixed with deionized water at room temperature. The toughness and elasticity of the resin are improved through polycarbonate modification. Specifically, PCDL 8011 from Asahi Kasei Corporation of Japan can be used.

[0040] In some embodiments, the water-based six-functional aliphatic polyurethane acrylic emulsion is a polyurethane-modified acrylic emulsion. Preferably, it has a solid content of 35-45 wt%. It has a functionality of 6, which allows fast reaction with the initiator, is suitable for excimer process curing, and forms a coating film with excellent touch and good chemical resistance. Specifically, SEAPUR 33G41 from Sityon can be used. Higher functionality results in brighter surface gloss (but better hardness, wear resistance, chemical resistance, and stain resistance, etc.), but the use of high-functionality acrylic emulsion in the present application, together with the shrinkage space formed on the surface by the migration of the water-based elastic resin, can achieve better matte effect on the surface.

[0041] In some embodiments, the substrate wetting agent is a modified polyether siloxane copolymer and / or an alkyne diol surfactant.

[0042] In some embodiments, the dispersing agent is a water-based dispersing agent, specifically a copolymer aqueous solution containing a pigment-compatible group, which has good effects on coating stability and anti-flocculation.

[0043] In some embodiments, the photoinitiator is a light yellow liquid of 2-hydroxy-2-methyl-1-phenyl-1-propanone. It can be fully excited at 254 nm, is suitable for surface curing in an acrylic varnish system, is easy to mix, and has good yellowing resistance.

[0044] In some embodiments, the auxiliary agent includes a leveling and smoothing agent and a defoaming agent. The leveling and smoothing agent is a polysiloxane-polyether copolymer, which is used to improve the elastic and smooth properties of the water-based double-curing matte touch coating. The defoaming agent is a polyether siloxane copolymer, which is used to eliminate bubbles generated during production and possible bubbles during the construction process.

[0045] In some embodiments, the solvent is one or more of DPM, DPNB, PM.

[0046] In the present application, both the coating component and the curing agent component are packaged separately, and mixed before use to form a film on the surface of the substrate. Preferably, the mass ratio of the coating component to the curing agent component is 100:10-15, the curing agent component includes an oily isocyanate curing agent and a diluent, the weight percentage of the isocyanate curing agent is 70-90%, and the weight percentage of the diluent is 10-30%. The addition of the curing agent reacts with the molecules of the coating component to form a dense network structure, significantly improving the hardness, boiling water resistance, and wear resistance of the water-based double-curing matte touch coating.

[0047] In some embodiments, the curing agent is an aliphatic polyisocyanate, such as hexamethylene diisocyanate. Hexamethylene diisocyanate type curing agent has a long chain segment, the reactant is soft, and the reaction speed is fast, improving the drying performance and chemical resistance of the water-based coating.

[0048] The preparation method of the water-based double-curing matte touch coating in some embodiments of the present application includes the following steps:

[0049] (1) Mix the photoinitiator powder and part of the solvent, and fully dissolve at high temperature. Preferably, the mixing conditions are 60-80°C, 800-1000 r / min for 20-30 min until complete dissolution.

[0050] (2) Mix the water-based elastic resin and part of the water thoroughly, and stir and disperse to obtain a mixed solution. Preferably, the stirring conditions are 1200-1500 r / min for 20-30 min.

[0051] (3) Mix the water-based hexafunctional aliphatic polyurethane acrylic emulsion and the photoinitiator solution in step 1 uniformly, then add the mixed solution in step 2, the substrate wetting agent, the dispersant, the auxiliary agent, the remaining solvent, and the remaining water, stir and disperse, and filter to obtain the coating component A. Preferably, the stirring conditions are 800-1000 r / min for 25-40 min.

[0052] (4) Package the coating component A and the curing agent component B to obtain the water-based double-curing matte touch coating. The preparation method of the curing agent component is to mix the isocyanate curing agent and the diluent (preferably, 500-1000 r / min for 25-40 min), and filter to obtain the curing agent component B.

[0053] The water-based double-curing matte touch coating of the present application is coated on a substrate by the following application process: mixing the coating component and the curing agent component of the water-based double-curing matte touch coating, adding an appropriate amount of water for dilution (for example, diluting by 5-15% in mass ratio), spraying on the surface of the substrate, first air-drying at room temperature for 2-5 minutes, then baking at 55-65°C for 5-10 minutes, then surface curing by 254nm excimer lamp, then deep curing by UV mercury lamp, and then post-curing, the post-curing drying conditions being 70-80°C*4-8h.

[0054] During the film-forming process, first, the small molecular water-based polycarbonate elastic resin will crosslink with the hydroxyl groups in the curing agent, this process is slow at low-temperature baking (for example, 60 degree baking for 5-10 minutes), and the proportion of the real OH and NCO complete combination is very low, so most of the small molecular "water-in-oil" particles will have a tendency to migrate to the surface of the coating film, then the water-based six-functional aliphatic polyurethane acrylic emulsion is surface cured under the action of the photoinitiator, due to the small molecular "water-in-oil" particles on the surface of the paint film, the UV paint film will have more space for movement during excimer curing, thereby further causing the "wrinkles" of the excimer paint film surface to be more obvious, thereby causing the gloss of the paint film surface under excimer process to be lower, the touch to be more outstanding, and the hand feeling to be better; then deep curing by mercury lamp, the UV resin is completely cured and fully utilized. But since OH and NCO do not react under excimer process, post-curing at 70-80 degrees is needed, generally 4-8 hours of post-curing is needed, thereby forming a paint film that is tough and elastic, has a unique hand feeling, and has good stain resistance.

[0055] The water-based double-curing matte touch coating of the present application has the excellent hand feeling, high hardness, stain resistance, wear resistance, high chemical resistance, etc. of elastic coatings.

[0056] Examples

[0057] The raw materials used in the water-based double-curing matte touch coating in Examples 1-6 and Comparative Examples 1-4 are shown in Tables 1 and 2.

[0058] Table 1: Amount of each component in the specific examples (unit: weight parts)

[0059]

[0060] Table 2

[0061]

[0062]

[0063] The ratio of the curing agent and the diluent in the curing agent component is 80:20.

[0064] The preparation method of the water-based dual-curing matte touch coating of the above embodiment comprises the following steps:

[0065] (1) Mix the photoinitiator powder and part of the solvent, and fully dissolve at high temperature without obvious particulate impurities. The mixing condition is to disperse at 800-1000 r / min for 20-30 min at 60-80°C until complete dissolution.

[0066] (2) Mix the water-based elastic resin and part of the water thoroughly, and stir and disperse to obtain a mixed solution. The stirring condition is to disperse at 1200-1500 r / min for 20-30 min until the fineness is less than 15 μm.

[0067] (3) Mix the water-based hexafunctional aliphatic polyurethane acrylic emulsion and the photoinitiator solution in step 1 uniformly, and then add the mixed solution in step 2, the substrate wetting agent, the dispersant, the auxiliary agent, the remaining solvent and the remaining water, stir and disperse, and filter to obtain the coating component A. The stirring condition is to disperse at 800-1000 r / min for 25-40 min until the fineness is less than 15 μm, and the filtering is 300 mesh filtering.

[0068] (4) Package the coating component A and the curing agent component B to obtain the water-based dual-curing matte touch coating. The preparation method of the curing agent component is to mix the isocyanate curing agent and the diluent (disperse at 500-1000 r / min for 25-40 min), and filter (300 mesh screen) to obtain the curing agent component B.

[0069] The water-based dual-curing matte touch coating obtained by the preparation in the above specific embodiments 1-6 and comparative examples 2-4 is coated on a plastic substrate by using the following construction process: substrate treatment: oil and ash removal, the construction environment temperature is 20-25°C, the water-based dual-curing matte touch coating (mixed after the coating component and the curing agent component) is diluted with deionized water according to a mass ratio of 5-15%, the construction viscosity (Zahn 3# cup 25°C) is 10-30 s, the construction air pressure is 3-6 KPa, the spray gun caliber is 0.9-1.4, the paint film thickness is 10-30 μm, and the paint film is first air dried at room temperature for 2-5 min, then baked at 60°C for 5-10 min, then subjected to surface curing in a 254 nm excimer box, and then subjected to deep layer curing in a UV mercury lamp, the UV energy is 800-1000 mj / cm 2 , and then post-cured, the post-curing drying condition is 70-80°C*4-8h. Comparative example 1 omits the excimer curing, and the other steps are the same as above.

[0070] The paint film obtained in the above specific embodiments and comparative examples is subjected to performance test according to the test methods or test standards in Table 3:

[0071] Table 3: The performance of the application reaches the requirements of 3C electronic products, mainly meets the performance standards

[0072]

[0073] The test performance results of the paint films obtained in the above Examples 1-6 and Comparative Examples 1-4 and the comparative samples are shown in Tables 4 and 5.

[0074] Table 4: Test performance results of the paint films obtained in the Examples

[0075]

[0076] Table 5

[0077]

[0078] From the above tables and Figure 1 It can be seen that the water-based dual-curing matte touch paint obtained in Examples 1-6 has good performance in terms of touch, wear resistance, stain resistance, hardness, water boiling adhesion, safety and environmental protection, etc.

[0079] In Comparative Example 1, since no excimer is used for curing, the surface touch and stain resistance of the paint film are obviously poor, and the gloss is also the highest, which is a high light effect and cannot achieve the desired matte appearance.

[0080] In Comparative Example 2, since the molecular weight of the resin is 2000, the upward migration of the resin molecules is affected in the post-curing stage, resulting in a higher gloss and a softer touch on the surface of the paint film, and the smoothness is reduced, but the overall performance is not greatly affected.

[0081] In Comparative Example 3, since the functionality of the acrylic emulsion is reduced, the crosslinking degree of the resin is also reduced, thus leading to a certain degree of decrease in the chemical resistance, stain resistance, hardness and wear resistance of the paint film, but the overall gloss is also reduced.

[0082] In Comparative Example 4, since the curing agent is replaced by a pure water-based curing agent, the elastic resin and the curing agent are completely compatible in the formula, thus leading to a significant increase in the surface gloss and an inability to achieve the desired matte appearance effect; at the same time, the wear resistance, stain resistance and chemical resistance are all decreased to a certain extent.

[0083] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, which does not deviate from the technical scheme of the present application, shall fall within the scope of protection of the technical scheme of the present application.

Claims

1. An aqueous dual-cure matt finish coating comprising a coating component and a curing agent component, characterised in that, The raw materials for preparing the coating component include the following components in parts by weight: 20-30 parts of water-based elastic resin, 40-50 parts of water-based six-functional aliphatic polyurethane acrylic emulsion, 1-3 parts of photoinitiator, 3-8 parts of solvent, and 15-35 parts of water; The water-based elastic resin is PCDL 8011 from Asahi Kasei Corporation of Japan; The water-based six-functional aliphatic polyurethane acrylic emulsion is a polyurethane-modified acrylic emulsion; The curing agent component includes an oily isocyanate curing agent and a diluent; The photoinitiator can be excited by 254 nm light, so that the water-based six-functional aliphatic polyurethane acrylic emulsion can be surface-cured under a 254 nm excimer lamp; The water-based double-curing matte touch coating does not contain matte powder or filler; In use, the coating component and the curing agent component are mixed, sprayed on the surface of a substrate, and sequentially baked, surface-cured under a 254 nm excimer lamp, deep-cured under a UV mercury lamp, and post-cured.

2. The aqueous dual-cure matte-haptouch coating of claim 1, wherein, The coating component further includes 0.3-0.6 parts of substrate wetting agent, 1-3 parts of dispersant, and 0.5-2 parts of auxiliary agent; the auxiliary agent includes leveling and smoothing agent and defoaming agent.

3. The aqueous dual-cure matte touch coating according to claim 1 or 2, characterized in that, The water-based six-functional aliphatic polyurethane acrylic emulsion is SEAPUR 33G41 from Sichuan Sitong New Material Co., Ltd.

4. The aqueous dual-cure matte touch coating of claim 1 or 2, wherein, The photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone.

5. The aqueous dual-cure matte touch coating of claim 1 or 2, wherein, The mass ratio of the coating component to the curing agent component is 100:10-15.

6. The aqueous dual-cure matte touch coating of claim 1 or 2, wherein, The oily isocyanate curing agent is hexamethylene diisocyanate.

7. A process for the preparation of the aqueous dual-cure matt- touch coating according to any one of claims 1 to 6, characterized in that The method includes the following steps: Dissolving the photoinitiator in part of the solvent to obtain a photoinitiator solution; Dispersing the water-based elastic resin in part of the water to obtain a mixed solution; Mixing the water-based six-functional aliphatic polyurethane acrylic emulsion and the photoinitiator solution uniformly, and then adding the mixed solution, the substrate wetting agent, the dispersant, the auxiliary agent, the remaining solvent, and the remaining water, and stirring and dispersing to obtain the coating component.

8. Use of the aqueous dual-cure matt finish coating according to any one of claims 1 to 6, characterized in that Mixing the coating component and the curing agent component, spraying on the surface of a substrate, and sequentially baking, surface-curing under a 254 nm excimer lamp, deep-curing under a UV mercury lamp, and post-curing.

9. Use according to claim 8, characterized in that, The baking condition is baking at 55-65°C for 5-10 minutes; and the post-curing condition is drying at 70-80°C for 4-8 hours.

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