阅读说明：本技术 一种包含聚苯乙烯/纳米银复合物的激光标记涂料的制备方法及应用 (Preparation method and application of laser marking paint containing polystyrene/nano-silver compound ) 是由 戴彦恺 卢光威 曹峥 范黎琳 闻晓倩 王凯伦 赵晋源 游兴华 成骏峰 刘春林 于 2019-09-30 设计创作，主要内容包括：本发明公开了一种包含聚苯乙烯/纳米银复合物的激光标记涂料的制备方法及应用,属于高分子材料及激光标记领域。首先采用十二烷基硫酸钠对纳米银颗粒进行超声震荡预处理,得到纳米银的预处理分散液；再将苯乙烯、AIBN、聚乙烯吡咯烷酮、无水乙醇混合并磁力搅拌成透明溶液；将二者混合并超声振荡反应,制得聚苯乙烯/纳米银复合物,将复合物加入到丁苯乳液、云母等的混合物中,继续搅拌并水浴得到包含聚苯乙烯/纳米银复合物的激光标记涂料；最后将制备好的涂料喷涂到聚丙烯、聚乙烯等板材表面,得到可激光标记的涂层材料。该方法在制品的表面或基底进行标识,提高其易辨识性和可追溯性,实现了聚丙烯、聚乙烯等材料的连续、高效大规模标记。(The invention discloses a preparation method and application of a laser marking coating containing a polystyrene/nano-silver compound, belonging to the fields of high polymer materials and laser marking. Firstly, carrying out ultrasonic oscillation pretreatment on nano silver particles by adopting sodium dodecyl sulfate to obtain a pretreatment dispersion liquid of nano silver; then mixing styrene, AIBN, polyvinylpyrrolidone and absolute ethyl alcohol, and magnetically stirring to obtain a transparent solution; mixing the polystyrene and the nano-silver, carrying out ultrasonic oscillation reaction to obtain a polystyrene/nano-silver compound, adding the compound into a mixture of styrene-butadiene emulsion, mica and the like, continuously stirring and carrying out water bath to obtain the laser marking coating containing the polystyrene/nano-silver compound; finally, spraying the prepared coating on the surfaces of plates such as polypropylene, polyethylene and the like to obtain the coating material capable of being marked by laser. The method marks the surface or the substrate of the product, improves the legibility and the traceability of the product, and realizes the continuous, efficient and large-scale marking of materials such as polypropylene, polyethylene and the like.)

1. A preparation method of a laser marking paint containing a polystyrene/nano-silver compound is characterized by comprising the following steps:

1) under the condition of stirring in a water bath at the temperature of 30-40 ℃, adding 0.5g of nano-silver particles, 0.5g of sodium dodecyl sulfate and 10mL of deionized water into a 50mL beaker, and then carrying out ultrasonic oscillation to carry out pretreatment on the nano-silver particles to prepare a pretreatment dispersion liquid of nano-silver;

2) mixing 10mL of styrene monomer, 0.1g of azobisisobutyronitrile initiator, 0.5g of polyvinylpyrrolidone and 80mL of absolute ethyl alcohol, and uniformly stirring by using a magnetic stirrer to obtain a transparent solution;

3) blowing nitrogen gas into the transparent solution obtained in the step 2) for 2 hours, then dropwise adding the solution obtained in the step 1) into the transparent solution, setting the rotating speed of a magnetic stirrer to be 150rpm, and stirring and mixing the solution at room temperature for 24 hours;

4) reacting the mixed solution reacted in the step 3) under the ultrasonic oscillation condition, cleaning and filtering the mixed solution for many times by using ethanol for purification after the reaction is finished, and drying the product for 24 hours in vacuum at 40 ℃ for later use;

5) adding the polystyrene/nano-silver compound prepared in the step 4) into a mixture of styrene-butadiene emulsion, mica, needle-shaped wollastonite, diatomite, light calcium carbonate, deionized water and a thickening agent, keeping the water bath temperature at 30-50 ℃, setting the rotating speed of a mechanical stirrer at 300-500 rpm, and stirring for 40-60 min to obtain the laser marking paint containing the polystyrene/nano-silver compound.

2. The method for preparing the laser marking paint containing the polystyrene/nano-silver composite according to claim 1, wherein the nano-silver particles in the step (1) have a particle size of 35-100 nm; the ultrasonic oscillation power is 600W, and the oscillation time is 2 h.

3. The preparation method of the laser marking paint containing the polystyrene/nano-silver composite according to claim 1, wherein the ultrasonic power in the step (4) is 300-600W, and the oscillation reaction time is 3-5 h.

4. The preparation method of the laser marking paint containing the polystyrene/nano-silver composite according to claim 1, wherein the mass ratio of the styrene-butadiene emulsion, the mica, the needle-shaped wollastonite, the diatomite, the light calcium carbonate, the deionized water and the thickener in the step (5) is 400-420: 180-160: 120-100: 100-80: 50-40: 40-30: 8-6.

5. Use of a laser marking paint comprising a polystyrene/nanosilver composite according to claim 1 for the preparation of laser marking coatings of polypropylene, polyethylene, polyisobutylene, thermoplastic polyurethane.

6. The use of a laser marking paint comprising a polystyrene/nanosilver composite according to claim 5, wherein the laser marking coating is prepared by a method comprising: spraying the prepared laser marking paint on the surfaces of polypropylene, polyethylene, polyisobutylene and thermoplastic polyurethane plates by adopting air in a normal-temperature drying environment, heating the plates coated with the paint at 80-90 ℃ for 30 minutes, and repeating the process for three times to obtain the coating material capable of being marked by laser.

7. The application of the laser marking paint containing the polystyrene/nano-silver composite as claimed in claim 6, wherein the polypropylene, the polyethylene, the polyisobutylene and the thermoplastic polyurethane plate are coated with a layer of chlorinated polypropylene with the thickness of 2-5 μm on the surface before the surface of the polypropylene, the polyethylene, the polyisobutylene and the thermoplastic polyurethane plate is sprayed.

8. The application of the laser marking paint containing the polystyrene/nano-silver compound as claimed in claim 6, wherein the coating film thickness of the spraying laser marking coating is 50-100 μm.

Technical Field

The invention belongs to the field of high polymer materials and laser marking, and particularly relates to a preparation method and application of a laser marking coating containing a polystyrene/nano-silver compound. The laser-markable coating material with easy identification and traceability is obtained by the preparation method and is used for surface marking of products such as polypropylene, polyethylene, polyisobutylene, thermoplastic polyurethane and the like.

Background

Polypropylene (PP) material is nontoxic and tasteless, is convenient to process, is widely applied to the aspects of light industry, textile industry, automobile industry, electronic and electric appliance industry, pipe fittings and the like, is also used for producing television housings, radio housings, telephone housings and the like, and is thermoplastic plastic with wide application. Most PP products need to be marked before leaving a factory, and relevant information of the products is marked by using characters, patterns and other modes, and the traditional ink printing technology is limited due to the use of organic solvents, high price and environmental protection problems. The emerging laser marking technology is widely concerned due to the rapidness, high efficiency, lasting marking and environmental protection and safety, but the polypropylene material is not sensitive to laser and is difficult to absorb laser energy, so that the large-scale application of the laser marking technology is limited. Therefore, the polypropylene material capable of being marked by laser has extremely wide market space, and the improvement of the laser marking performance of the polypropylene material has important significance.

Improving PPThe process of laser marking performance is primarily performed by adding laser marking additives. At present, the laser marking additives for PP are mainly inorganic compounds, most of which are complex additives based on metal oxides, such as TiO₂、Fe₂O₃、Sn₂O₃And the like. The addition of the laser sensitive additives is beneficial to absorbing laser energy to generate photothermal conversion, so that adjacent polymer molecular chains are degraded and carbonized to be black, and black marks are generated. However, the direct addition of laser sensitive additives into the PP matrix resin still has problems and drawbacks. Firstly, the inorganic laser sensitive additive has the problem of dispersibility when dispersed in PP resin, and a plurality of powder particles are gathered together to cause uneven dispersion; in addition, the amount of the laser marking additive is not excessive, otherwise, the original mechanical property and other properties of the PP material are influenced; inorganic particles are still completely filled throughout the matrix resin, but the range of effective laser marking is only a few hundred microns in size of the surface. Therefore, there is still a need to develop a simple and convenient method for generating high-definition and high-contrast laser marking patterns and characters on the surface of the polypropylene material.

Disclosure of Invention

The invention provides a preparation method of a laser-markable coating capable of being coated on the surfaces of polypropylene, polyethylene, polyisobutylene, thermoplastic polyurethane and other materials, and the laser-markable coating can be applied to the market marking industry and field.

A preparation method of a laser marking paint containing a polystyrene/nano-silver compound sequentially comprises the following steps:

1) adding 0.5g of nano silver particles, 0.5g of sodium dodecyl sulfate and 10mL of deionized water into a 50mL beaker under the condition of stirring in a water bath at the temperature of 30-40 ℃. Then, carrying out ultrasonic oscillation to carry out pretreatment on the nano silver particles, wherein the ultrasonic oscillation power is 600W, and the oscillation time is 2h (ensuring that the nano silver is uniformly dispersed and has no agglomeration), so as to prepare a pretreatment dispersion liquid of the nano silver;

the particle size of the nano silver particles is 35-100nm, the particle size is 35-100nm in consideration of the synthesis difficulty and the exertion of the photothermal effect of the nano silver particles, and the particle size is 35-100nm, and has high synthesis requirement and great difficulty for less than 35 nm; for >100nm, the particle size is too large to affect the exertion of laser response performance.

The surface performance of the nano-silver is improved and the dispersion performance of the nano-silver is improved through the dual functions of ultrasonic oscillation and a surfactant.

2) Mixing 10mL of styrene monomer, 0.1g of azobisisobutyronitrile initiator, 0.5g of polyvinylpyrrolidone and 80mL of absolute ethyl alcohol, and uniformly stirring by using a magnetic stirrer to obtain a transparent solution;

3) blowing nitrogen gas into the solution prepared in the step 2) for 2 hours, then dropwise adding the solution obtained in the step 1), setting the rotating speed of a magnetic stirrer to be 150rpm, and stirring and mixing for 24 hours at room temperature (ensuring that the solution is fully and uniformly mixed, but the styrene monomer does not have a polymerization reaction yet);

4) reacting the mixed solution for 3-5 h under the oscillation condition of ultrasonic power of 300-600W, after the reaction is finished, cleaning and filtering the mixed solution for many times by using ethanol for purification, and drying the product for 24h in vacuum at 40 ℃ for later use;

the invention adopts a styrene dispersion polymerization method, namely styrene is dispersed in a water/ethanol phase, polyvinylpyrrolidone is used as a stabilizer, AIBN is used as an initiator, and the initiator is decomposed and initiated to react through the cavitation action of ultrasonic oscillation to prepare the polystyrene/nano silver compound.

5) Adding the prepared polystyrene/nano-silver compound into a mixture of mica, needle-shaped wollastonite, diatomite, light calcium carbonate, deionized water and a thickening agent, keeping the water bath temperature at 30-50 ℃, setting the rotating speed of a mechanical stirrer at 300-500 rpm, and stirring for 40-60 min (the filler, the emulsion and the polystyrene/nano-silver compound are uniformly dispersed without phase separation or emulsion breaking through stirring to obtain the coating with high quality stability and reliability. ) And obtaining the laser marking paint containing the polystyrene/nano silver compound.

Wherein the mass ratio of the butylbenzene emulsion to the mica to the needle-shaped wollastonite to the diatomite to the light calcium carbonate to the deionized water to the thickening agent is 400-420: 180-160: 120-100: 100-80: 50-40: 40-30: 8-6. The needle-shaped wollastonite, the diatomite and the light calcium carbonate are used as fillers, and have the function of friction resistance, so that the stability and the reliability of the coating are ensured.

6) Then spraying the prepared coating on the surfaces of polypropylene, polyethylene, polyisobutylene and thermoplastic polyurethane plates in a normal-temperature drying environment, coating a layer of chlorinated polypropylene (with the thickness of 2-5 mu m) on the surfaces of the polypropylene, polyethylene and thermoplastic polyurethane plates before coating, and spraying the chlorinated polypropylene with air, wherein the coating thickness is 50-100 mu m; and heating the polypropylene plate coated with the coating at 80-90 ℃ for 30 minutes, and repeating the process for three times to obtain the coating material capable of being marked by laser.

The coating of the chlorinated polypropylene is equivalent to the pretreatment of spraying the coating, the surface performance of the substrate is improved, the combination or adhesion of the butylbenzene aqueous emulsion is facilitated, and if the chlorinated polypropylene is not coated, the coating is not firm and is easy to fall off. The surface energy of the polypropylene and other plates is low, and the styrene-butadiene emulsion is difficult to combine.

The principle of the invention is that a polystyrene/nano-silver compound is selected as a laser sensitive additive, nano-silver can absorb the energy of near-infrared laser, polystyrene is a high polymer which is easy to form carbon and has high carbon residue rate, and the polystyrene is easy to carbonize under the irradiation energy of laser; meanwhile, the styrene-butadiene emulsion is also easy to be carbonized and blackened because the styrene-butadiene emulsion also contains a styrene structural unit; mica in the coating formula can absorb near-infrared laser energy and also contributes to the laser marking effect of the coating. The nano silver particles and the mica are sensitive to laser and generate different levels of photo-thermal effect, the nano silver is in a nano range, the mica is in a micron level, the polystyrene and the nano silver particles form a compound, the polystyrene is close to the nano silver particles, and the nano silver performs photo-thermal conversion after absorbing laser energy, so that the adjacent polystyrene can be quickly locally overheated and carbonized to be blackened, and the formation of laser marks is facilitated; and the mica is dispersed in the styrene-butadiene copolymer in a micron size, laser energy is absorbed through laser irradiation, the styrene-butadiene copolymer is carbonized and blackened, and the two layers cooperatively contribute to laser marking.

The surface of a polypropylene, polyethylene, polyisobutylene and thermoplastic polyurethane base material is coated with a coating containing a polystyrene/nano silver compound, a styrene-butadiene copolymer and a mica filler, so that the surface of the polypropylene, polyethylene, polyisobutylene and thermoplastic polyurethane can be coated with a coating with excellent laser marking performance, and the thickness of the coating is 50-100 mu m. And meanwhile, the coating is heated for 30 minutes at 80-90 ℃, and the process is repeated for three times, so that the coating is more compact, stable and reliable, good in molding property and resistant to scraping, and the polypropylene surface can display high-definition and high-contrast patterns and characters after laser marking.

Compared with other traditional methods for directly adding inorganic laser sensitive adding marks into polypropylene matrix resin, the method has the following advantages that:

1. the dispersibility of the nano-silver particles is improved by preparing the polystyrene and nano-silver compound, then the polystyrene and nano-silver compound is introduced into a coating system, and the polystyrene and nano-silver compound is stirred and forcibly mixed to improve the dispersibility of all additives in polypropylene, polyethylene, polyisobutylene and thermoplastic polyurethane resin;

2. the thickness of the added laser marking coating is only controlled to be 50-100 mu m, and the original mechanical properties and other properties of polypropylene, polyethylene, polyisobutylene and thermoplastic polyurethane materials are not influenced;

3. because only the surfaces of polypropylene, polyethylene, polyisobutylene, thermoplastic polyurethane and the like are coated and laser marked, the laser sensitive additive does not need to be filled into the whole resin, the utilization rate is improved, and the cost is reduced;

4. the method utilizes the original coating system, can exert the synergistic effect of the styrene-butadiene emulsion, the mica and the polystyrene/nano silver compound, and prepares the coating with excellent laser marking performance.

Drawings

Fig. 1 shows the laser marking pattern produced by laser irradiation of pure polypropylene and polypropylene coated with a laser markable coating according to example 1.

Detailed Description

The invention is described in more detail below with reference to the following examples: