PU elastic paint capable of being subjected to laser etching as well as preparation method and application of PU elastic paint

Abstract

The invention belongs to the technical field of coatings, and discloses a laser-engravable PU elastic paint and a preparation method and application thereof, and the laser-engravable PU elastic paint comprises a component A, a component B and a component C, the component A is prepared from the following raw materials: modified flexible polyester and polycarbonate resin; the component B is prepared from the following raw materials: aliphatic polyisocyanate and butyl acetate; the component C is prepared from the following raw materials: ethyl acetate, butyl acetate and diacetone alcohol; the modified flexible polyester is prepared from the following raw materials: polyester polyol and 2-hydroxy-4-methoxybenzophenone. According to the PU elastic paint capable of being subjected to laser etching and the preparation method and application thereof, the paint covers the surface of an electronic cigarette shell product, and meanwhile, the paint can be matched with primer with various color effects for use.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings, and particularly relates to a laser-engravable PU elastic paint and a preparation method and application thereof. Background Art

[0002] With the improvement of science and technology, the rise of electronic devices, and the increasing prevalence of smart electronic devices, people are pursuing product performance while also having higher and higher requirements for appearance. Many products that directly contact the skin or respiratory tract require special appearance effects while meeting environmental protection requirements. In particular, the rise of the e-cigarette industry in recent years and the publicity of public opinion have led to the rapid development of the e-cigarette market. As an emerging product, e-cigarettes have replaced traditional cigarettes. According to the traditional process: plastic shell material, spraying color primer, silk-screen brand logo, environmental protection logo, and then spraying hand-feel topcoat, there are many processes, low production capacity, and high costs. The laser engraving process can replace the previous silk-screen printing process, avoiding the complex process of the product needing to be automatically offline and then silk-screened after spraying the color primer, and then automatically spraying the topcoat online. After the color primer is applied directly to the automatic line, the hand-feel topcoat can be sprayed, and laser engraving can be performed directly after the line is offline.

[0003] Therefore, it is necessary to develop an elastic paint that can be laser engraved with an elastic feel. Summary of the invention

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

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

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

[0007] The 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 the A component include: modified flexible polyester and polycarbonate resin;

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

[0010] The solvent 1 comprises: butyl acetate;

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

[0012] The solvent 2 comprises: 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 the present invention is a baking type, which is applied to the surface of the shell of electronic equipment such as electronic cigarettes and Bluetooth that directly contact the skin. It can meet the product test performance and environmental protection requirements. At the same time, the elastic hand-feel paint can be laser-engraved.

[0015] Modified flexible polyester has the characteristics of delicate and smooth hand feel, strong elasticity and thickness, fast drying speed, and easy laser engraving. The modified flexible polyester compound can form intramolecular hydrogen bonds between the hydroxyl hydrogen on the benzene ring and the adjacent carbonyl oxygen in the structure to form a chelate ring. When the ultraviolet laser engraving machine is laser engraving, the polymer absorbs ultraviolet light, the molecules undergo thermal vibration, the hydrogen bonds are destroyed, and the chelate ring opens. At this time, the compound is in an unstable high-energy state. In the process of returning to the original low-energy stable state, it releases excess energy, which plays a role in preventing laser engraving from blistering and paint peeling.

[0016] Carbonate resin contains polycarbonate bonds in its molecular chain, which makes the coating have excellent mechanical properties, hydrolysis resistance, and chemical resistance. It also has good flexibility and elastic touch. When added to the formula, it can also synergize with laser engraving and prevent problems such as burns and blistering after laser engraving.

[0017] In some embodiments of the present invention, the 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] The B component includes the following raw materials in parts by weight: 70 to 80 parts of aliphatic polyisocyanate and 20 to 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 paint film construction effect is best under the above weight ratio.

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

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

[0025] The polycarbonate resin of the present invention: polycarbonate diol PCDL (Polycarbonatediol) is a polyol used in polyurethane resin, and contains polycarbonate bonds in the molecular chain, so that the mechanical properties, hydrolysis resistance, and chemical resistance are very excellent, and at the same time, it has good flexibility and elastic touch. The structure of the polycarbonate bond makes the paint film have good heat resistance and temperature resistance. When added to the formula, it can also play a role in synergizing with laser engraving to prevent problems such as burning 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 an organic tin compound and a metal carboxylate catalyst.

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

[0029] According to some embodiments of the present invention, the metal carboxylate catalyst is a new type of non-toxic, green and environmentally friendly catalyst. It has better hydrolysis stability than tin compounds when used in polyurethane elastomers, can significantly reduce the generation of bubbles in the product, and can greatly increase the reaction rate. Its reaction mechanism is significantly different from that of organic tin. It can promote the reaction of isocyanate (-NCO) and hydroxyl (-OH) and avoid the side reaction of -NCO. It can not only increase the speed of polyurethane synthesis reaction, but also adjust the reactivity of polyols with different relative molecular weights and isocyanates, so that the prepared polyurethane prepolymer has a narrower molecular weight distribution and lower viscosity; at the same time, this type of catalyst also has the advantages of being non-toxic, harmless to human body, and safe, so as to replace the currently used organic tin, lead, and mercury heavy metal catalysts with relatively high toxicity.

[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-modified 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 includes surface-treated silicon dioxide powder.

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

[0035] In some embodiments of the present invention, the component A includes the following preparation 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 powder and 30 to 65 parts of diluent.

[0036] In some embodiments of the present invention, the B component 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] IPDI in component B is an aliphatic diisocyanate and also a cycloaliphatic diisocyanate. Its reactivity is lower than that of aromatic diisocyanate. The reactivity of the two NCO groups in the IPDI molecule is different. The reactivity of the secondary NCO group attached to the cyclohexane ring is 1.3 to 2.5 times higher than that of the primary NCO. The 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, the C component includes 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 format 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 above viscosity 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-engravable PU elastic paint, comprising: mixing the component A, the component B and the component C to obtain the laser-engravable PU elastic paint.

[0050] In some embodiments of the present invention, the method for preparing component A comprises the following steps:

[0051] S1, adding modified flexible polyester and polycarbonate resin in parts by weight and mixing;

[0052] S2, add 1 / 4 to 1 / 3 of the weight of diluent and mix;

[0053] S3. Add matting powder by weight while stirring. 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 weight;

[0055] S5, adding the drier and the remaining weight of the diluent in parts by weight and mixing;

[0056] S6. After mixing, filtering, solid-liquid separation, and collecting the liquid phase to obtain the A component.

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

[0058] According to some embodiments of the present invention, the preparation method of the C component comprises the following steps: ethyl acetate, butyl acetate and diacetone alcohol are mixed, and the mixture is stirred and dispersed for 5 to 10 minutes to obtain the C component.

[0059] Component C is a mixed solvent, which includes ethyl acetate with fast volatility, butyl acetate with moderate volatility, and diacetone alcohol with slow volatility. If the volatility is too fast, the appearance leveling will be poor, the matte powder arrangement will be poor, and the hand feel will also be poor; if the volatility is too slow, it will be difficult to build up a thick film, and the drying speed will also be slower. The above mixed solvent is more conducive to construction.

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

[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 coating the laser-engravable PU elastic paint on the surface of a plastic shell and drying it.

[0063] In some embodiments of the present invention, the application process includes at least one of the following conditions: 1) the coating film thickness 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 coating film thickness 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 the present invention, the electronic product decorative parts whose surfaces need to be sprayed with coatings and laser engraved with characters are sprayed with ordinary color paint series primers according to the appearance color requirements, and dried under specific conditions to obtain color paint; then laser-engravable PU elastic paint is sprayed on the color paint layer, and the laser-engravable PU elastic paint coating is obtained after drying.

[0068] The environmentally friendly laser-engravable PU elastic paint prepared by the present invention uses modified flexible polyester, has a smooth and smooth hand feel, strong elasticity and thickness, can be laser-engraved, is easy to laser-engraved, and has the characteristics of no blistering and paint explosion on the surface of the paint film after laser engraving; it is matched with polycarbonate resin to improve the heat resistance and temperature resistance of the paint film, and help improve the appearance of laser engraving effect; the drying agent is a metal carboxylate catalyst mixture, which is a new type of non-toxic, green and environmentally friendly catalyst with little odor and meets environmental protection requirements; the curing agent is aliphatic polyisocyanate (IPDI trimer), which has good light stability and is more conducive to laser engraving. This coating can meet the material control requirements of products produced in Europe and the United States while meeting the laser engraving effect through the combination of formulas. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 This is a picture of a laser engraved product according to Example 1 of the present invention;

[0070] Figure 2 This is a picture of a laser engraved product according to Example 2 of the present invention;

[0071] Figure 3 This is a picture of a laser engraved product of Comparative Example 1 of the present invention;

[0072] Figure 4 This is a picture of a laser engraved product of Comparative Example 2 of the present invention;

[0073] Figure 5 This is a picture of a laser engraved product of Comparative Example 3 of the present invention;

[0074] Figure 6 This is a picture of the laser engraved product of Comparative Example 5 of the present invention. DETAILED DESCRIPTION

[0075] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be noted that the following embodiments do not limit the protection scope of the present invention.

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

[0077] The following examples use the modified flexible polyester in the embodiment of the present invention purchased from Shanghai Yile TX-3161, with a solid content of 100%; a viscosity of Z to Z1 / 25°C (format tube viscosity); an acid value of 2 mg KOH / g to 4 mg KOH / g; and a hydroxyl value of 60 mg KOH / g;

[0078] The polycarbonate resin was purchased from T-5652 of Asahi Chemical Industry of Japan, with a solid content of 100%, a viscosity of 7000 to 16000 (mpa.sat50c), an acid value of 0 mg KOH / g to 3 mg KOH / g, and a hydroxyl value of 51 mg KOH / g to 61 mg KOH / g;

[0079] The leveling agent was purchased from BYK333 of BYK Company;

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

[0081] Matting 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, Z4470 purchased from Covestro of Germany, has 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, prepared from the following raw materials:

[0086] It comprises component A, component B and component C; wherein component A comprises the raw materials in parts by weight as shown in Table 1; component B comprises the raw materials in parts by weight as shown in Table 2; component C comprises the raw materials in parts by weight as shown in Table 3;

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

[0088]

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

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

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

[0092]

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

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

[0095] S1. Add modified flexible polyester resin and polycarbonate resin in parts by weight and stir evenly;

[0096] S2, add 1 / 3 weight portion of diluent and stir evenly;

[0097] S3. Add matting powder by weight while stirring. 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 ratio;

[0099] S5, add the drying agent and about 1 / 3 of the weight of the diluent by weight and stir evenly;

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

[0101] The preparation method of the B component includes the following steps: mixing the aliphatic polyisocyanate (IPDI trimer) and butyl acetate, stirring and dispersing for 10 to 15 minutes under nitrogen filling, solid-liquid separation, and collecting the liquid phase to obtain the B component. The nitrogen filling during the preparation process is to prevent the water vapor in the air from reacting with the isocyanate curing agent to cause failure.

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

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

[0104] 1. Spray the electronic product decoration parts whose surfaces need to be sprayed with coatings and laser engraved characters with Matsui ordinary paint BP380-XXXXX, SF312-XXXXX series primers according to the customer's appearance color requirements, and dry them under specific conditions to obtain colored paint;

[0105] 2. Spray environmentally friendly laser-engravable PU elastic paint on the color paint layer, with the weight ratio of component A: component B: component C being 100:25:30-50, and mix and adjust to a viscosity of 10s (NK-2 cup) to obtain environmentally friendly laser-engravable PU elastic paint. The sprayed film thickness is 35μm-45μm, the drying temperature is 70℃-80℃, the drying time is 40min-60min, and the environmentally friendly laser-engravable PU elastic paint coating is obtained after drying.

[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, which includes component A, component B and component C. The difference from embodiment 1 is that:

[0109] Component A is the raw material for preparation in the parts by weight shown in Table 4.

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

[0111]

[0112] The preparation method and coating process are the same as those in Example 1, and the resin remains unchanged. The difference is that the amount of the main resin in the formula is adjusted to a certain extent, the amount of TX-3161 is 35, the amount of T-5652 is 5, and the others remain unchanged.

[0113] Example 3

[0114] This embodiment is an environmentally friendly laser-engravable PU elastic paint, which includes component A, component B and component C. The difference from embodiment 1 is that:

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

[0116]

[0117]

[0118] The preparation method and coating process are the same as those of 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, including component A, component B and component C; the difference from Example 1 is that component A is a preparation raw material with the weight parts shown in the table, as shown in Table 6.

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

[0122]

[0123] The preparation method and coating process are the same as those in Example 1, except that the modified flexible polyester resin in the formula is replaced with an equal amount of polyester resin TX-3300 from Daisei Chemical Co., Ltd. of Japan, with a solid content of 88%; a viscosity of Z to Z1 / 25°C (format tube viscosity); an acid value of 2 mg KOH / g to 4 mg KOH / g; a hydroxyl value of 120 mg KOH / g; and the coating has the characteristics of 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, which includes component A and component B. The difference from Example 1 is that component A includes the preparation raw materials in parts by weight as shown in Table 7.

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

[0127]

[0128]

[0129] The preparation method and coating process are the same as those 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, which includes component A and component B. The difference from Example 1 is that component A includes the preparation raw materials in parts by weight as shown in Table 8.

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

[0133]

[0134] The preparation method and coating process are the same as those in Example 1, except that the laser engraving agent 8733 is added to the formula. It is a common laser engraving agent 8733 produced by Dazhan Jiyuan. The agent is a light gray powder. When added to the coating, the product is laser engraved on the surface, making the laser engraving clearer, firmer and more durable.

[0135] Comparative Example 4

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

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

[0138]

[0139] The preparation method and coating process are the same as those in Example 1, except that hydroxy acrylic resin A-859 (DIC resin, solid content 75%; viscosity Z3-Z5 / 25°C; 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 formula.

[0140] Comparative Example 5

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

[0142] Component A is the preparation raw material with the weight parts as shown in the table, as shown in Table 10.

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

[0144]

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

[0146] Test Example 1

[0147] The coatings prepared in Examples 1 to 3 of the present invention and Comparative Examples 1 to 3 were applied to specific products. The results are as follows: Figures 1 to 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. Spray the electronic product decoration parts whose surfaces need to be sprayed with coatings and laser engraved characters with Matsui ordinary paint BP380-XXXXX, SF312-XXXXX series primers according to the customer's appearance color requirements, and dry them under specific conditions to obtain colored paint;

[0150] 2. Then spray the environmentally friendly laser-carved PU elastic paint on the color paint layer according to the weight of component A: component B: component C;

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

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

[0153] All the above coatings are sprayed together to produce an environmentally friendly laser-engravable PU elastic paint coating. Then a comparison and performance test is carried out. The specific test items are as follows:

[0154] 1. Adhesion test:

[0155] Visually inspect the surface to be tested, and there is no abnormality in appearance. Use a sharp blade (blade angle of 20°~30°, blade thickness of 0.43±0.03mm) to scratch a 1mm×1mm small grid on the surface of the test sample according to the film thickness specification; stick the NICHIBAN CT405AP-24 tape to the small grid to be tested, and use the back of the fingernail to flatten the part of the tape above the grid area, and let it stand for (90±30)s; grab one end of the tape by hand and quickly pull off the tape in the opposite direction of 60°. Check the peeling condition of the paint coating (refer to GB / T9286-88).

[0156] 2. Boiling test:

[0157] Check that the product coated with the environmentally friendly laser-engravable PU elastic paint has no abnormal appearance, no discoloration, bubbles, cracks, falling off, etc., and wipe the surface clean with a dust-free cloth; add pure water to the water bath, and heat it to and maintain it at 99℃±1℃; immerse the test sample completely in hot water, test time: 40 minutes, take it out after the specified time of the boiling test, and let it stand at room temperature for 10 minutes; check the sample coating surface for cracks, bubbles, paint film discoloration and other abnormalities, and perform adhesion test on the surface.

[0158] 3. Paint surface feel:

[0159] Touch by hand to evaluate the smoothness and thick velvety feel of the paint film to meet customer requirements;

[0160] 4. Environmental protection conditions:

[0161] Meet environmental protection requirements (including: control of heavy metals, polyaromatic hydrocarbons, organotin and other substances);

[0162] 5. Laser carving appearance effect:

[0163] The laser engraved characters are clear and the surface does not bubble;

[0164] 6. Surface drying effect:

[0165] After baking at 80℃ for 15 minutes, touch the surface with your finger to see if there are any marks left, which can be used to evaluate the drying effect;

[0166] 7.Activation period:

[0167] After the paint is diluted according to the proportion, it is placed 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 to 3 of the present invention and Comparative Examples 1 to 5 are shown in Table 11;

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

[0170]

[0171] It can be seen from Table 11 that the environmentally friendly laser-engravable PU elastic paint provided by the present invention can meet the test requirements in all tests of the embodiments. The PU elastic paint produced has excellent comprehensive performance, good appearance and feel, clear laser-engraved characters, and no paint explosion and blistering problems, and can meet the export environmental protection requirements; however, if any raw material is replaced, or the addition range of the selected raw materials is not within the parameter range provided by the present invention, the environmental protection requirements cannot be met, the laser-engraved characters are unclear or blistering, or the comprehensive performance cannot meet the performance test requirements. The environmentally friendly laser-engravable PU elastic paints of Examples 1 to 2 have clear laser-engraved characters, no defects in appearance, and clear laser-engraved characters. The environmentally friendly laser-engravable PU elastic paint of Example 3 mainly uses an organic tin drying agent, and the heavy metal content in the environmental protection test exceeds the standard. At the same time, its surface drying speed is slightly slower, but the activation period is short. The surface of the laser engraved surface of Comparative Example 1 has blistering, and the results are as follows Figure 4 As shown, the main reason is that conventional polyester resin has poor heat resistance and poor laser engraving performance; the surface of laser engraving in comparative example 2 has bubbles, and the results are as follows Figure 5 As shown, although polycarbonate resin has good heat resistance, it has poor laser engraving performance; the laser engraved characters of comparative example 3 are not clear and the appearance is bubbling. Figure 6 shown.

[0172] The embodiments of the present invention are described in detail above in conjunction with the specification, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. A laser-engravable PU elastic paint, characterized in that: It includes component A, component B and component C; The raw materials for preparing the A component include: modified flexible polyester and polycarbonate resin; The raw materials for preparing the B component include: aliphatic polyisocyanate and solvent 1 The solvent 1 comprises: butyl acetate; The raw materials for preparing the C component include: solvent 2 The solvent 2 comprises: at least one of ethyl acetate, butyl acetate and diacetone alcohol; The raw materials for preparing the modified flexible polyester include polyester polyol and 2-hydroxy-4-methoxybenzophenone.

2. The laser-engravable PU elastic paint according to claim 1, characterized in that: The A component 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; The B component includes the following raw materials in parts by weight: 70 to 80 parts of aliphatic polyisocyanate and 20 to 30 parts of butyl acetate; 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.

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

4. The laser-engravable PU elastic paint according to claim 1, characterized in that: The polycarbonate resin has a hydroxyl value of 51 to 61 mg KOH / g.

5. The laser-engravable PU elastic paint according to claim 1, characterized in that: The raw materials for preparing the A component also include: a drying agent; The drying agent includes at least one of an organic tin compound and a carboxylate catalyst.

6. The laser-engravable PU elastic paint according to claim 1, characterized in that: The raw materials for preparing the A component also include: a leveling agent; The leveling agent includes at least one of an acrylic leveling agent and a polyether-modified silicone-modified leveling agent.

7. A method for preparing a laser-engravable PU elastic paint as claimed in any one of claims 1 to 6, characterized in that: include: The component A, the component B and the component C are mixed to obtain the laser-engravable PU elastic paint.

8. Use of the laser-engravable PU elastic paint as claimed in any one of claims 1 to 6 on the surface of a plastic housing.

9. The use according to claim 8, characterized in that: The application comprises the following steps: applying the laser-engravable PU elastic paint on the surface of the plastic shell and drying it.

10. The use according to claim 9, characterized in that: The application process includes at least one of the following conditions: 1) the coating film thickness is 30 μm to 45 μm; 2) the drying time is 40 min to 60 min.

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