A laser-engravable PU elastic paint, a preparation method and application thereof

Abstract

This invention belongs to the field of coating technology and discloses a laser-etchable PU elastic paint, its preparation method, and its application. The paint includes components A, B, and C. Component A is prepared from modified flexible polyester and polycarbonate resin. Component B is prepared from aliphatic polyisocyanate and butyl acetate. Component C is prepared from ethyl acetate, butyl acetate, and diacetone alcohol. The modified flexible polyester is prepared from polyester polyol and 2-hydroxy-4-methoxybenzophenone. This invention provides a laser-etchable PU elastic paint, its preparation method, and its application. This paint can be applied to the surface of electronic cigarette casings and can be used in conjunction with various color effect primers.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, and specifically relates to a laser-engravable PU elastic paint, its preparation method, and its application. Background Technology

[0002] With the advancement of technology and the rise of electronic devices, smart electronic devices are becoming increasingly common. While pursuing product performance, consumers are also placing higher demands on appearance. Many products that come into direct contact with the skin or respiratory tract require special aesthetic effects while meeting environmental protection requirements. In particular, the rise of the e-cigarette industry in recent years, coupled with media hype, has led to the rapid development of the e-cigarette market. As an emerging product, e-cigarettes have replaced traditional cigarettes. Traditional processes involve: plastic shell material, spraying a colored base coat, silkscreening the brand logo and environmental protection mark, and then spraying a tactile topcoat. This process is complex, has low production capacity, and is costly. Laser engraving can replace the previous silkscreening process, avoiding the complex steps of spraying the colored base coat, automatically going offline, then silkscreening again, and then automatically going online to spray the topcoat. The process can directly automate the colored base coat application, spray the tactile topcoat, and then directly laser engrave after the product goes offline.

[0003] Therefore, it is necessary to develop a flexible, laser-engravable paint with a tactile feel. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a laser-engravable PU elastic paint, its preparation method and application, which is applied to the surface of electronic cigarette casing products and can be used in conjunction with various color effect primers.

[0005] The present invention also provides a method for preparing laser-engravable PU elastic paint.

[0006] The present invention also provides an application of laser-engravable PU elastic paint on the surface of plastic shells.

[0007] A first aspect of the present invention provides a laser-engravable PU elastic paint, comprising component A, component B and component C;

[0008] The raw materials for preparing component A include: modified flexible polyester and polycarbonate resin;

[0009] The raw materials for preparing component B include: aliphatic polyisocyanate and solvent 1.

[0010] Solvent 1 includes: butyl acetate;

[0011] The raw materials for preparing component C include: solvent 2

[0012] The solvent 2 includes at least one of ethyl acetate, butyl acetate, and diacetone alcohol;

[0013] The raw materials for preparing the modified flexible polyester include polyester polyol and 2-hydroxy-4-methoxybenzophenone.

[0014] The laser-engravable PU elastic paint provided by this invention is a baking-type coating applied to the surface of electronic device shells such as e-cigarettes and Bluetooth devices that come into direct contact with the skin. It can meet product testing performance requirements while also meeting environmental protection requirements. In addition, the elastic feel paint can be laser-engraved.

[0015] Modified flexible polyester has a delicate and smooth feel, strong elasticity and thickness, fast drying speed, and easy laser engraving. In the modified flexible polyester compound, the hydroxyl hydrogen on the benzene ring and the adjacent carbonyl oxygen can form an intramolecular hydrogen bond to form a chelate ring. When a UV laser engraving machine is used, the polymer absorbs ultraviolet light, and the molecules undergo thermal vibration, the hydrogen bonds are broken, and the chelate ring is opened. At this time, the compound is in an unstable high-energy state. In the process of returning to the original low-energy stable state, excess energy is released, which can prevent laser engraving bubbling and paint peeling.

[0016] Carbonate resins, with polycarbonate bonds in their molecular chains, give coatings superior mechanical properties, hydrolysis resistance, and chemical resistance. They also have good flexibility and elastic feel. When incorporated into a formulation, they can synergistically assist laser engraving and prevent problems such as burns and blistering after laser engraving.

[0017] In some embodiments of the present invention, component A comprises the following raw materials in parts by weight: 15 to 35 parts of modified flexible polyester and 5 to 10 parts of polycarbonate resin.

[0018] Component B comprises the following raw materials in parts by weight: 70-80 parts of aliphatic polyisocyanate and 20-30 parts of butyl acetate;

[0019] The C component comprises the following raw materials in parts by weight: 30 to 60 parts of ethyl acetate, 10 to 25 parts of butyl acetate, and 15 to 25 parts of diacetone alcohol.

[0020] In some embodiments of the present invention, the aliphatic polyisocyanate comprises IPDI trimer.

[0021] In some embodiments of the present invention, the weight ratio of component A, component B and component C is 100:20-30:30-50.

[0022] The above weight ratio yields the best paint film application results.

[0023] In some embodiments of the present invention, the hydroxyl value of the polycarbonate resin is 51-61 mg KOH / g.

[0024] In some embodiments of the present invention, the polycarbonate resin comprises polycarbonate diol.

[0025] The polycarbonate resin of this invention, polycarbonate diol (PCDL), is a polyol used in polyurethane resins. Its molecular chain contains polycarbonate bonds, resulting in excellent mechanical properties, hydrolysis resistance, and chemical resistance, while also exhibiting good flexibility and elasticity. The structure of the polycarbonate bonds gives the coating film excellent heat and temperature resistance. When incorporated into the formulation, it also synergistically assists in laser engraving, preventing problems such as burn-in and blistering after laser engraving.

[0026] In some embodiments of the present invention, the raw materials for preparing component A further include: a drying agent;

[0027] The drying agent includes at least one of organotin compounds and metal carboxylate catalysts.

[0028] In some embodiments of the present invention, the drying agent comprises a metal carboxylate catalyst.

[0029] According to some embodiments of the present invention, metal carboxylate catalysts are novel, non-toxic, and environmentally friendly catalysts. When applied to polyurethane elastomers, they exhibit better hydrolytic stability than tin compounds, significantly reduce bubble formation in the product, and substantially increase the reaction rate. Their reaction mechanism differs significantly from that of organotin catalysts; they promote the reaction between isocyanate groups (-NCO) and hydroxyl groups (-OH) while avoiding the side reaction of -NCO. They not only increase the rate of polyurethane synthesis but also regulate the reactivity of polyols with different relative molecular masses with isocyanates, resulting in polyurethane prepolymers with a narrower molecular weight distribution and lower viscosity. Furthermore, these catalysts are non-toxic, harmless to humans, and safe, thus replacing currently used, more toxic organotin, lead, and mercury-based heavy metal catalysts.

[0030] In some embodiments of the present invention, the raw materials for preparing component A further include: a leveling agent;

[0031] The leveling agent includes at least one of an acrylic leveling agent and a polyether-modified silicone leveling agent.

[0032] In some embodiments of the present invention, the raw materials for preparing component A further include: a matting agent and a diluent.

[0033] In some embodiments of the present invention, the matting powder comprises surface-treated silica powder.

[0034] In some embodiments of the present invention, the diluent includes at least one selected from ethyl acetate, butyl acetate, propylene glycol methyl ether acetate, ethylene glycol butyl ether, and diacetone alcohol.

[0035] In some embodiments of the present invention, component A comprises the following raw materials in parts by weight: 15 to 35 parts of modified flexible polyester, 5 to 10 parts of polycarbonate resin, 0.1 to 0.5 parts of leveling agent, 0.1 to 0.5 parts of drying agent, 3 to 8 parts of matting agent, and 30 to 65 parts of diluent.

[0036] In some embodiments of the present invention, component B comprises the following raw materials in parts by weight: 70 to 80 parts of aliphatic polyisocyanate and 20 to 30 parts of butyl acetate.

[0037] Component B, IPDI, is an aliphatic diisocyanate, which is also a cyclic aliphatic diisocyanate. Its reactivity is lower than that of aromatic diisocyanates. The two NCO groups in the IPDI molecule have different reactivity. The secondary NCO group attached to the cyclohexane ring has 1.3 to 2.5 times higher reactivity than the primary NCO group. Polyurethane resin made from IPDI has excellent light stability, so it is also helpful for laser engraving.

[0038] In some embodiments of the present invention, component C comprises the following raw materials in parts by weight: 30 to 60 parts of ethyl acetate, 10 to 25 parts of butyl acetate, and 15 to 25 parts of diacetone alcohol.

[0039] In some embodiments of the present invention, the modified flexible polyester has a solid content of 95% to 100%.

[0040] In some embodiments of the present invention, the modified flexible polyester has a viscosity of Z to Z1 / at 25°C;

[0041] The viscosity mentioned is the viscosity of the Gietho tube.

[0042] In some embodiments of the present invention, the modified flexible polyester has an acid value of 2 mg KOH / g to 5 mg KOH / g.

[0043] In some embodiments of the present invention, the modified flexible polyester has a hydroxyl value of 40 mg KOH / g to 70 mg KOH / g.

[0044] In some embodiments of the present invention, the polycarbonate resin has a solid content of 95% to 100%.

[0045] In some embodiments of the present invention, the polycarbonate resin has a viscosity of 7000 to 16000.

[0046] The viscosity mentioned above is Viscosity (mpa.sat50c).

[0047] In some embodiments of the present invention, the polycarbonate resin has an acid value of 0 mg KOH / g to 3 mg KOH / g.

[0048] In some embodiments of the present invention, the polycarbonate resin has a hydroxyl value of 51 mg KOH / g to 61 mg KOH / g.

[0049] A second aspect of the present invention provides a method for preparing a laser-etchable PU elastic paint, comprising: mixing the A component, the B component and the C component to obtain the laser-etchable PU elastic paint.

[0050] In some embodiments of the present invention, the preparation method of component A includes the following steps:

[0051] S1. Add modified flexible polyester and polycarbonate resin according to the weight parts and mix;

[0052] S2. Add 1 / 4 to 1 / 3 of the weight of the diluent and mix.

[0053] S3. Add matting powder while stirring according to the weight proportions. After the powder is completely added, mix for 20 to 30 minutes.

[0054] S4. Mix the leveling agent and about 1 / 4 to 1 / 3 of the weight of the diluent according to the weight proportions;

[0055] S5. Add the drier and the remaining diluent according to the weight proportions and mix.

[0056] S6. After mixing, filter, separate the solid and liquid phases, and collect the liquid phase to obtain component A.

[0057] According to some embodiments of the present invention, the preparation method of component B includes the following steps: mixing the aliphatic polyisocyanate and butyl acetate, stirring and dispersing for 10 min to 15 min, separating the solid and liquid phases, and collecting the liquid phase to obtain component B.

[0058] According to some embodiments of the present invention, the preparation method of component C includes the following steps: mixing ethyl acetate, butyl acetate and diacetone alcohol, stirring and dispersing for 5 min to 10 min to obtain component C.

[0059] Component C is a mixed solvent containing ethyl acetate (fast-evaporating), butyl acetate (moderately volatile), and diacetone alcohol (slow-evaporating). If the evaporation is too fast, the surface leveling will be poor, the matte powder will not adhere properly, and the overall feel will be unpleasant. If the evaporation is too slow, it will result in a thicker film and a slower drying speed. The aforementioned mixed solvent is more conducive to application.

[0060] A third aspect of the present invention provides the application of laser-engravable PU elastic paint on the surface of a plastic shell.

[0061] In some embodiments of the present invention, the plastic shell surface includes the plastic shell surface of electronic consumer products that come into contact with the skin, such as electronic cigarettes and Bluetooth headsets.

[0062] In some embodiments of the present invention, the application includes applying the laser-engravable PU elastic paint to the surface of a plastic shell and then drying it.

[0063] In some embodiments of the present invention, the application process includes at least one of the following conditions: 1) the thickness of the coated film is 30 μm to 45 μm; 2) the drying time is 40 min to 60 min.

[0064] In some embodiments of the present invention, the spraying viscosity of the laser-engravable PU elastic paint is 9.5s to 10.5s (NK-2 cup).

[0065] In some embodiments of the present invention, the thickness of the coated film is 30 μm to 45 μm; and the drying time is 40 min to 60 min.

[0066] In some embodiments of the present invention, the drying temperature is 70°C to 80°C.

[0067] In this invention, for electronic product decorative parts that require a coating and laser engraving of characters on their surface, a common color paint series primer is sprayed according to the appearance and color requirements, and dried under specific conditions to obtain a colored paint; then, a laser-engravable PU elastic paint is sprayed on the colored paint layer, and dried to obtain a laser-engravable PU elastic paint coating.

[0068] This invention provides an environmentally friendly laser-engravable PU elastic paint. Utilizing modified flexible polyester, it offers a smooth, delicate feel, strong elasticity, and is suitable for laser engraving. It is easy to laser engrave, and the engraved paint film does not bubble or peel. Combined with polycarbonate resin, it enhances the heat and temperature resistance of the paint film, improving the laser engraving effect. The drying agent is a mixture of metal carboxylate catalysts, a novel, non-toxic, and environmentally friendly catalyst with low odor, meeting environmental protection requirements. The curing agent is an aliphatic polyisocyanate (IPDI trimer), which has good light stability, further facilitating laser engraving. This coating, through its formulation, satisfies both the laser engraving effect and the material control requirements for products exported to Europe and America. Attached Figure Description

[0069] Figure 1 The image shows a laser-engraved product according to Embodiment 1 of the present invention;

[0070] Figure 2 The image shows a laser-engraved product according to Embodiment 2 of the present invention;

[0071] Figure 3 The image shown is of the laser-engraved product in Comparative Example 1 of this invention.

[0072] Figure 4 The image shown is of the laser-engraved product in Comparative Example 2 of this invention.

[0073] Figure 5 The image shown is of the laser-engraved product in Comparative Example 3 of this invention.

[0074] Figure 6 The image shown is of the laser-engraved product in Comparative Example 5 of this invention. Detailed Implementation

[0075] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0076] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0077] The following examples use TX-3161, a modified flexible polyester purchased from Shanghai Yile, with a solid content of 100%; viscosity of Z to Z1 / 25℃ (Gergère tube viscosity); acid value of 2 mg KOH / g to 4 mg KOH / g; and hydroxyl value of 60 mg KOH / g.

[0078] The polycarbonate resin was purchased from Asahi Kasei Corporation of Japan as T-5652, with a solid content of 100%, a viscosity of 7000-16000 (MPa, SAT 50°C), an acid value of 0-3 mg KOH / g, and a hydroxyl value of 51-61 mg KOH / g.

[0079] The leveling agent was purchased from BYK 333 from BYK Corporation.

[0080] The drying agent was purchased from Germany. Kat 24;

[0081] The matte powder was purchased from Degussa's OK520;

[0082] The diluent is a mixed solvent of ethyl acetate, butyl acetate, and diacetone alcohol, all of which are commercially available.

[0083] Aliphatic polyisocyanate (IPDI trimer) curing agent, purchased from Covestro, Germany, Z4470, with an NCO content of 11.9 ± 0.4% and a solid content of 70% ± 2%.

[0084] Example 1

[0085] An environmentally friendly laser-engravable PU elastic paint, the raw materials for which are prepared are:

[0086] It includes component A, component B, and component C; wherein, component A includes the preparation raw materials in the weight parts shown in Table 1; component B includes the preparation raw materials in the weight parts shown in Table 2; and component C includes the preparation raw materials in the weight parts shown in Table 3.

[0087] Table 1. Weight parts of raw materials for preparing component A

[0088]

[0089] Table 2. Weight parts of raw materials for the preparation of component B

[0090] Component B Number of weights Aliphatic polyisocyanate (IPDI trimer) Z4470 75 Butyl acetate 25

[0091] Table 3. Weight parts of raw materials for the preparation of component C

[0092]

[0093] The specific preparation method of the above-mentioned environmentally friendly laser-engravable PU elastic paint is as follows:

[0094] The preparation method of component A includes the following steps:

[0095] S1. Add the modified flexible polyester resin and polycarbonate resin according to the weight proportions and stir evenly.

[0096] S2. Add 1 / 3 of the weight of the diluent and stir well;

[0097] S3. Add matting powder while stirring according to the weight proportions. After the powder is completely added, stir for 20 minutes.

[0098] S4. Mix the leveling agent and about 1 / 3 of the weight of the diluent evenly according to the weight proportions.

[0099] S5. Add the drier and about 1 / 3 of the weight of the diluent according to the weight proportions and stir well;

[0100] S6. After stirring evenly, filter using a 200 filter bag to separate the solid and liquid phases, and collect the liquid phase to obtain component A.

[0101] The preparation method of component B includes the following steps: mixing the aliphatic polyisocyanate (IPDI trimer) and butyl acetate, stirring and dispersing under nitrogen atmosphere for 10-15 minutes, separating the solid and liquid phases, and collecting the liquid phase to obtain component B. Nitrogen atmosphere is used during the preparation process to prevent moisture in the air from reacting with the isocyanate curing agent and causing it to become ineffective.

[0102] The preparation method of component C includes the following steps: mixing ethyl acetate, butyl acetate and diacetone alcohol, stirring and dispersing for 5 min to 10 min to obtain component C;

[0103] A method for preparing an environmentally friendly laser-engravable PU elastic paint also includes the following application steps:

[0104] 1. For the decorative parts of electronic products that require a coating and laser engraving, spray Matsui general-purpose color paint BP380-XXXXX or SF312-XXXXX series primer according to the customer's appearance and color requirements, and dry them under specific conditions to obtain the color paint.

[0105] 2. Next, spray environmentally friendly laser-engravable PU elastic paint onto the color paint layer. Mix the components A, B, and C in a weight ratio of 100:25:30-50 until the viscosity is adjusted to 10s (NK-2 cup) to obtain the environmentally friendly laser-engravable PU elastic paint. The sprayed film thickness is 35μm-45μm. The drying temperature is 70℃-80℃ and the drying time is 40min-60min. After drying, the environmentally friendly laser-engravable PU elastic paint coating is obtained.

[0106] 3. Perform laser engraving on the above-mentioned coating.

[0107] Example 2

[0108] This embodiment is an environmentally friendly laser-engravable PU elastic paint, consisting of components A, B, and C; the difference from Embodiment 1 is:

[0109] Component A consists of the raw materials prepared in the proportions shown in Table 4 by weight.

[0110] Table 4. Weight parts of raw materials for preparing component A

[0111]

[0112] The preparation method and coating process are the same as in Example 1. The resin remains the same. The difference is that the amount of the main resin in the formula is adjusted. The amount of TX-3161 is 35 and the amount of T-5652 is 5. Other aspects remain the same.

[0113] Example 3

[0114] This embodiment is an environmentally friendly laser-engravable PU elastic paint, consisting of components A, B, and C; the difference from Embodiment 1 is:

[0115] Table 5. Weight parts of raw materials for preparing component A

[0116]

[0117]

[0118] The preparation method and coating process are the same as in Example 1. The difference from Example 1 is that the drying agent is dibutyltin dilaurate, and the other conditions are the same.

[0119] Comparative Example 1

[0120] This comparative example is an environmentally friendly laser-engravable PU elastic paint, comprising component A, component B, and component C; the difference from Example 1 is that component A is the preparation raw material in the weight parts shown in Table 6.

[0121] Table 6. Weight parts of raw materials for preparing component A

[0122]

[0123] The preparation method and coating process are the same as in Example 1. The difference is that the modified flexible polyester resin in the formula is replaced by an equal amount of polyester resin TX-3300 from Taisei Chemicals Co., Ltd. of Japan, with a solid content of 88%; viscosity of Z to Z1 / 25℃ (Geiger tube viscosity); acid value of 2mg KOH / g to 4mg KOH / g; hydroxyl value of 120mg KOH / g; and features such as good hand feel, good wear resistance, and excellent chemical resistance.

[0124] Comparative Example 2

[0125] This comparative example is an environmentally friendly laser-engravable PU elastic paint, consisting of component A and component B. The difference from Example 1 is that component A includes the preparation raw materials in the weight parts shown in Table 7.

[0126] Table 7. Weight parts of raw materials for preparing component A

[0127]

[0128]

[0129] The preparation method and coating process are the same as in Example 1, except that the modified flexible polyester resin in the formula is removed and replaced entirely with polycarbonate resin.

[0130] Comparative Example 3

[0131] This comparative example is an environmentally friendly laser-engravable PU elastic paint, consisting of component A and component B. The difference between this example and Example 1 is that component A includes the raw materials prepared in the weight proportions shown in Table 8.

[0132] Table 8. Weight parts of raw materials for preparing component A

[0133]

[0134] The preparation method and coating process are the same as in Example 1. The difference is that laser engraving additive 8733 is added to the formula. It is a common laser engraving additive of Dazhan Jiyuan 8733. This additive is a light gray powder. It is added to the coating to make the product laser engraved on the surface, making the laser engraving clearer, stronger and more durable.

[0135] Comparative Example 4

[0136] This comparative example is an environmentally friendly laser-engravable PU elastic paint, consisting of component A and component B. The difference from Example 1 is that component A includes the preparation raw materials in the weight parts shown in Table 9.

[0137] Table 9. Weight parts of raw materials for preparing component A

[0138]

[0139] The preparation method and coating process are the same as in Example 1, except that hydroxyl acrylic resin A-859 (Dearson resin, solid content 75%; viscosity Z3~Z5 / 25℃; acid value 2mg KOH / g~4mg KOH / g; hydroxyl value 100mg KOH / g; good leveling, fast drying speed, good wear resistance, excellent chemical resistance, etc.) is used to replace the polycarbonate resin in the formulation.

[0140] Comparative Example 5

[0141] This embodiment is an environmentally friendly laser-engravable PU elastic paint, comprising component A, component B, and component C; the difference from Embodiment 1 is:

[0142] Component A consists of the raw materials prepared in the proportions shown in Table 10 by weight.

[0143] Table 10. Weight parts of raw materials for preparing component A

[0144]

[0145] The preparation method and coating process are the same as in Example 1, except that the amount of the main resin in the formulation is adjusted. The amount of TX-3161 is 15 and the amount of T-5652 is 25, while the others remain unchanged.

[0146] Test Example 1

[0147] The coatings prepared in Examples 1-3 and Comparative Examples 1-3 of this invention were applied to specific products, and the results were as follows: Figures 1-6 As shown, when used with Matsui's colored paint, an environmentally friendly laser-engravable PU elastic paint coating is obtained.

[0148] The specific implementation process is as follows:

[0149] 1. For the decorative parts of electronic products that require a coating and laser engraving, spray Matsui general-purpose color paint BP380-XXXXX or SF312-XXXXX series primer according to the customer's appearance and color requirements, and dry them under specific conditions to obtain the color paint.

[0150] 2. Next, spray environmentally friendly laser-engravable PU elastic paint onto the color paint layer, according to the weight ratio of component A: component B: component C;

[0151] The ratio is 100:25:30 to 50. Adjust the viscosity to 10s (NK-2 cup) to obtain an environmentally friendly laser-engravable PU elastic paint. The film thickness of the sprayed film is 35μm to 45μm. The drying temperature is 70℃ to 80℃ and the drying time is 40min to 60min. After drying, the environmentally friendly laser-engravable PU elastic paint coating is obtained.

[0152] 3. Perform laser engraving on the above-mentioned coating.

[0153] All the above coatings were sprayed together to create an environmentally friendly, laser-engravable PU elastic paint coating. Comparative and performance tests were then conducted, with the specific test items as follows:

[0154] I. Adhesion Test:

[0155] Visually inspect the surface to be tested; no abnormalities are found. Use a sharp blade (blade angle 20°~30°, blade thickness 0.43±0.03mm) to draw a 1mm×1mm grid on the surface of the test sample according to the film thickness specification. Adhere NICHIBAN CT405AP-24 tape to the grid area being tested, and use the back of your fingernail to press the tape flat above the grid area. After standing for (90±30) seconds, grasp one end of the tape and quickly pull it off at a 60° angle in the opposite direction. Check for paint coating peeling (refer to GB / T9286-88).

[0156] II. Boiling Test:

[0157] Inspect the product coated with environmentally friendly laser-engravable PU elastic paint coating for any abnormalities in appearance, such as discoloration, bubbles, cracks, or peeling. Wipe the surface clean with a lint-free cloth. Add pure water to a water bath and heat it to and maintain it at 99℃±1℃. Immerse the test sample completely in the hot water for 40 minutes. After the specified boiling time, remove the sample and let it stand at room temperature for 10 minutes. Inspect the sample coating surface for any abnormalities such as cracking, blistering, or discoloration of the paint film, and perform an adhesion test on the surface.

[0158] III. Texture of the coating surface:

[0159] By touching the paint film, assess its smoothness and thick, velvety texture to meet customer requirements;

[0160] IV. Environmental Protection Requirements:

[0161] Meets environmental protection requirements (including: control of heavy metals, polycyclic aromatic hydrocarbons, organotin compounds, etc.);

[0162] V. Laser engraving appearance effect:

[0163] Laser-engraved characters are clear and the surface does not bubble.

[0164] VI. Surface drying effect:

[0165] After baking at 80℃ for 15 minutes, touch the surface with your finger to see if it leaves a mark; this is used to assess the drying effect.

[0166] VII. Activation Period:

[0167] After the paint is diluted according to the ratio, let it stand at room temperature for two hours. If the viscosity change is less than 1.5 seconds, it is OK.

[0168] The test results of the environmentally friendly laser-engravable PU elastic paint coatings in Examples 1-3 and Comparative Examples 1-5 of the present invention are shown in Table 11;

[0169] Table 11 Performance test results of Examples 1-3 and Comparative Examples 1-5 of the present invention

[0170]

[0171] As shown in Table 11, the environmentally friendly laser-engravable PU elastic paint provided by this invention meets all test requirements in the examples. The resulting PU elastic paint exhibits excellent overall performance, a good appearance and feel, clear laser-engraved characters without any paint bursting or bubbling issues, and meets export environmental protection requirements. However, if any raw material is replaced, or if the selected raw material is added outside the parameter range provided by this invention, environmental requirements cannot be met, laser-engraved characters are unclear or bubbling occurs, or overall performance fails to meet performance test requirements. The environmentally friendly laser-engravable PU elastic paints of Examples 1 and 2 have clear laser-engraved characters and no appearance defects. The environmentally friendly laser-engravable PU elastic paint of Example 3 mainly uses organotin-based drying agents, but environmental tests show excessive heavy metals. It also has a slightly slower surface drying speed but a short activation period. Comparative Example 1 shows bubbling on the laser-engraved surface, as shown in the results. Figure 4 As shown, the main issue is the poor heat resistance and poor laser engraving ability of conventional polyester resin; in Comparative Example 2, blistering occurred on the laser-engraved surface, as shown in the following figure. Figure 5 As shown, although polycarbonate resin has good heat resistance, its laser engraving ability is poor; in Comparative Example 3, the laser-engraved characters are unclear, and the appearance shows bubbling results. Figure 6 As shown.

[0172] The embodiments of the present invention have been described in detail above with reference to the specification. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A laser-engravable PU elastomeric paint, characterized in that: The PU laser-engravable elastic paint comprises an A component, a B component and a C component. The raw material for preparing the A component comprises a modified flexible polyester, a drier and a polycarbonate resin. The raw material for preparing the B component comprises an aliphatic polyisocyanate and a solvent 1. The solvent 1 comprises butyl acetate. The raw material for preparing the C component comprises a solvent 2. The solvent 2 comprises at least one of ethyl acetate, butyl acetate and diacetone alcohol. The raw material for preparing the modified flexible polyester comprises a polyester polyol and 2-hydroxy-4-methoxybenzophenone. The A component comprises the following raw materials by weight: 15-35 parts of the modified flexible polyester and 5-10 parts of the polycarbonate resin. The B component comprises the following raw materials by weight: 70-80 parts of the aliphatic polyisocyanate and 20-30 parts of the butyl acetate. The C component comprises the following raw materials by weight: 30-60 parts of the ethyl acetate, 10-25 parts of the butyl acetate and 15-25 parts of the diacetone alcohol. The drier is a carboxylate catalyst.

2. The laser-engravable PU elastomeric paint according to claim 1, characterized in that, The weight ratio of the A component, the B component and the C component is 100:20-30:30-50.

3. The laser-engravable PU elastomeric paint according to claim 1, wherein, The hydroxyl value of the polycarbonate resin is 51-61 mg KOH / g.

4. The laser-engravable PU elastomeric paint according to claim 1, wherein, The raw material for preparing the A component further comprises a leveling agent. The leveling agent comprises at least one of an acrylic leveling agent and a polyether-modified silicone leveling agent.

5. A method of preparing the laser-engravable PU elastomeric paint according to any one of claims 1 to 4, characterized in that, The PU laser-engravable elastic paint comprises an A component, a B component and a C component. The PU laser-engravable elastic paint is prepared by mixing the A component, the B component and the C component.

6. The PU laser-engravable elastic paint according to any one of claims 1-4 for use in a plastic shell surface.

7. Use according to claim 6, characterized in that, The use comprises the steps of: applying the PU laser-engravable elastic paint to a plastic shell surface and drying.

8. Use according to claim 7, characterized in that, The application process comprises at least one of the following conditions: 1) the thickness of the applied film is 30-45 μm; and 2) the drying time is 40-60 min.

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