CN113861564A - Organic/inorganic polypropylene composite material capable of being marked by laser and preparation method and application thereof - Google Patents

Abstract

The invention discloses a laser-markable organic-inorganic polypropylene composite material, and a preparation method and application thereof, and belongs to the fields of high-molecular polypropylene composite materials and laser marking. BNNSs is prepared by adopting a solvent-assisted ultrasonic stripping method, then the BNNSs is subjected to heat treatment for 6h in air at 850 ℃, and the BNNSs is subjected to thermal oxidation to obtain BNNSs-OH. BNNSs-OH is added into polypropylene, and the polypropylene composite material is prepared by adopting a melt blending method. And selecting a proper formula through laser marking comparison and various test comparisons to prepare the polypropylene marking material with excellent laser marking performance. The laser marking machine is utilized to carry out surface laser radiation treatment on the polypropylene composite material to generate black marking patterns, so that the cost is effectively reduced, and continuous, environment-friendly, efficient and large-scale marking of the polypropylene composite material is realized.

Description

Organic/inorganic polypropylene composite material capable of being marked by laser and preparation method and application thereof

Technical Field

The invention belongs to the field of high polymer materials, and particularly relates to a laser-markable organic/inorganic polypropylene composite material, and a preparation method and application thereof.

Background

The polypropylene has high crystallinity and regular structure, so that it has excellent mechanical performance and excellent heat resistance, and its product can be sterilized at 100 deg.c and 150 deg.c without deformation. The chemical stability of the polypropylene is good, the polypropylene can be corroded by concentrated sulfuric acid and concentrated nitric acid, and is stable to other various chemical reagents, so that the polypropylene is suitable for manufacturing various chemical pipelines and accessories, and the corrosion prevention effect is good. Polypropylene is excellent in high-frequency insulating properties, and since it hardly absorbs water, the insulating properties are not affected by humidity. It has a high dielectric coefficient and can be used to make heated electrical insulation products as the temperature rises. The breakdown voltage of the high-voltage power supply is high, the high-voltage power supply is suitable for being used as electrical accessories and the like, and the high-voltage power supply has high voltage resistance and arc resistance.

In some specific applications, the polypropylene material needs to be marked on the surface thereof to provide information such as the production date, the expiration date, the serial number, and the company logo. But the laser marking effect is not ideal, and the polypropylene itself does not absorb 1064nm wavelength, so the polypropylene can not be carbonized under the irradiation of a laser marking machine. Therefore, the method has important research significance for conveniently, quickly and efficiently marking and identifying the polypropylene material and the product thereof.

The laser marking technology is a new and rapidly developed laser technology, and selective scanning irradiation is carried out on the surface area of a material according to a patterning or writing instruction given by a computer program, and the irradiated area on the surface of the material can absorb laser energy and be heated to generate thermal-chemical change, so that black marks are formed. By designing various patterns and controlling the pulse laser through computer software, colorful marking patterns such as characters, figures, symbols, bar codes, images and the like can be generated. The laser marking does not need ink, does not need a high-intensity energy drying process of an ink marking technology, does not need a solvent, and is more environment-friendly. Due to the characteristics of quick marking, excellent durability, high contrast and environmental friendliness, the fluorescent marking agent is widely applied to surface marking of various materials such as plastic macromolecules, metals, ceramics and the like. Laser marking has been widely used in the fields of electronic components, insulation, plastics, and packaging. By changing the operating parameters of the laser beam, such as scanning speed, current, spot size, line width and the like, the laser marking effect of the material surface, including surface roughness, marking contrast and definition, chromatic aberration and the like, can be regulated.

The laser sensitive additive is generally inorganic oxide particles sensitive to laser, such as mica, bismuth oxide, titanium dioxide and the like, the inorganic oxide particles are dispersed in plastic resin, can effectively absorb the energy of the laser, generate photo-chemical change per se, and simultaneously the absorbed energy causes the polymer molecular chains around the particles to be pyrolyzed and carbonized to form black marks, so that the effect of laser marking is achieved, which is the mechanism of the traditional laser marking. The traditional laser additives are inorganic oxide additives, which have poor compatibility with polymer matrix, and some inorganic oxide additives can change the color of polymer matrix and even reduce the mechanical properties of the polymer. For example, bismuth oxide additives are toxic and, by their very nature, do not uniformly disperse particles during melt blending.

Disclosure of Invention

The invention provides an organic-inorganic polypropylene composite material and a preparation method thereof, wherein a heat conduction path can be formed by adding functional boron nitride nanosheets into polypropylene by utilizing good heat conduction performance and dielectric property of the functional boron nitride nanosheets, and the functional boron nitride nanosheets absorb laser energy and are subjected to photo-thermal conversion, so that heat is well transferred in a polypropylene matrix. The polypropylene composite material with high strength, high hydrophobicity, high thermal conductivity and high dielectric property obtained by the preparation method can generate black marks with high contrast and definition on the surface through pulse laser irradiation, can realize quick, efficient and nondestructive marking under laser irradiation, and is suitable for application in the fields of commodity information marking, identification, surface modification and the like of high-molecular polypropylene composite materials.

According to the invention, a patterned die or a patterned substrate is not required to be designed in advance, a special chemical reagent and an etching technology are not required to be used, no environmental pollution is caused, the functionalized boron nitride nanosheet is introduced into the existing common polypropylene material structure to prepare the organic-inorganic polypropylene composite material, and the polypropylene material is subjected to rapid and efficient laser marking by utilizing the emerging laser marking technology so as to solve the problems existing in the existing polypropylene marking technology, thereby realizing simplified process and controllable marking and identification.

The technical scheme of the invention is as follows:

a laser-markable organic-inorganic polypropylene composite material comprises the following components in parts by mass: 0.5-2 parts of functionalized boron nitride nanosheet, 10 parts of compatilizer and 100 parts of polypropylene.

Wherein the compatilizer is polypropylene grafted maleic anhydride (PP-g-MAH), and the grafting rate of the maleic anhydride is 1%.

The preparation method of the modified boron nitride nanosheet comprises the following steps: firstly, preparing Boron Nitride Nanosheets (BNNSs) by adopting a solvent-assisted ultrasonic stripping method, which specifically comprises the following steps: dispersing Boron Nitride (BN) particles in N, N-dimethylacetamide (DMAc), and ultrasonically stripping for 12 h; followed by centrifugation at 3000r/min for 15min, the upper dispersion was filtered through a polytetrafluoroethylene membrane with a pore size of 0.1 μm, and the product was dried at 100 ℃ to obtain BNNSs. And then, carrying out heat treatment on the BNNSs in an environment at 850 ℃ for 6h, carrying out thermal oxidation on the BNNSs in high-temperature air, and grafting hydroxyl (-OH) to the surface of the BNNSs to obtain BNNSs-OH.

The purity of the Boron Nitride (BN) is 98 wt%, the particle size of the Boron Nitride (BN) is 0.1-0.4 mu m, and the crystal form is a hexagonal crystal form.

The invention also provides a preparation method of the laser-markable organic-inorganic polypropylene composite material, which comprises the following steps: and (3) melting and blending the polypropylene, the compatilizer and the functionalized boron nitride nanosheet, and then pressing and molding the mixture by using a flat-plate vulcanizing instrument to obtain the PP/BNNSs-OH composite material.

The melt blending is carried out for 3 minutes at 190 ℃ by a torque rheometer; and the functionalized boron nitride nanosheets are dried in an air-blowing drying oven at 70 ℃ for 30min before being melted and blended.

The organic-inorganic polypropylene composite material capable of being marked by laser can be used for marking patterns such as characters, figures, images, symbols and the like, such as production date, effective period, two-dimensional codes and the like, on the surface of the material by using a semiconductor laser marking machine, so that the application of identifying, marking and modifying polypropylene products is realized.

The specific application method comprises the following steps: carrying out surface laser marking treatment on the organic/inorganic polypropylene composite material by using semiconductor pulse laser (KDD-50, the wavelength is 1064nm), wherein the maximum output power of a laser marking machine is 50W, and the pulse laser wavelength is as follows: 1064nm, the surface of the polypropylene composite material presents black laser characters and pattern marks, and the depth can reach 200-400 μm.

The principle of the invention is as follows:

(1) adding a compatilizer into the functionalized boron nitride nanosheet, and then melting and blending the functionalized boron nitride nanosheet with polypropylene to obtain the organic-inorganic polypropylene composite material. BN is a heat-conducting nano sheet and has good heat-conducting property, and a heat-conducting channel can be formed by modifying, modifying and adding PP; BNNSs-OH absorbs laser energy, performs photo-thermal conversion, and well transfers heat to the matrix PP, so that good laser carbonization marking performance is achieved.

(2) The BNNSs grafted with hydroxyl (-OH) through high-temperature thermal oxidation has good compatibility with a compatilizer (PP-g-MAH), reduces the agglomeration phenomenon of boron nitride in the composite material, improves the dispersibility of the boron nitride in polypropylene, and improves the compatibility and the bonding force of the BN nanosheet and the polypropylene, thereby improving the mechanical strength of the composite material.

(3) Adding the functionalized boron nitride nanosheet into a compatilizer, and then carrying out melt blending with polypropylene to obtain the organic-inorganic polypropylene composite material. The polypropylene surface is subjected to laser marking under the action of controllable pulse laser irradiation of the laser marking machine, patterns marked by the laser can be designed through software communicated with the laser marking machine in a computer, the patterns comprise characters, symbols, graphs, images and the like, the selection is various, the size is adjustable, and the laser working parameters can also be adjusted. The modified boron nitride nanosheets embedded in the polypropylene material absorb laser energy entering the polypropylene surface to undergo thermo-chemical change, so that black marks are generated. In this process, the depth of the black laser mark can reach 200-. By controlling the content of the modified boron nitride nanosheets and the laser power, black marked characters and patterns with different contrasts and definitions can be generated on the surface of the organic-inorganic polypropylene material without affecting the structure of the high-density polypropylene.

Compared with other traditional polypropylene marking methods, the method has the following advantages:

1. the polypropylene composite material comprises the compatilizer (PP-g-MAH) and the laser-sensitive functionalized boron nitride nanosheets, the prepared organic-inorganic polypropylene composite material can be subjected to laser marking, and the polypropylene also has good mechanical properties, stable chemical properties and other properties due to the reinforcing effect of the inorganic material.

2. The preparation method adopted by the invention comprises the steps of dispersing BN particles in N, N-dimethylacetamide (DMAc), and ultrasonically stripping for 12 hours; centrifuging at 3000r/min for 15min, filtering the upper layer dispersion liquid by a polytetrafluoroethylene membrane with the pore diameter of 0.1 μm, drying the product at 100 ℃ to obtain BNNSs, carrying out heat treatment on the BNNSs at 850 ℃ for 6h, and carrying out thermal oxidation on the BNNSs at high temperature to realize hydroxyl functionalization to obtain BNNSs-OH. And carrying out melt blending on BNNSs-OH and PP to obtain the polypropylene composite material embedded with the laser sensitive particles, so as to form the organic-inorganic polypropylene composite material.

3. The marking method adopted by the invention does not need to produce patterned dies and silicon chip substrates in advance in the early stage, does not need chemical etching, and can effectively reduce the cost, reduce the consumption of chemical reagents and reduce the environmental pollution. The laser marking machine which is newly developed is utilized to mark, and the industrial, continuous, efficient and large-scale marking of the polypropylene material can be realized. By changing the content of the functionalized boron nitride nanosheets and the laser power in the marking process, characters and patterns with different contrasts and definitions can be obtained on the surface of the polypropylene, and the marking method has more advantages than the marking obtained by the traditional cutting and etching technology.

Drawings

FIG. 1 is a marking effect diagram of pure PP and functionalized boron nitride composite polypropylene materials with different contents.

FIG. 2 is a color difference analysis diagram of marked pure PP and functionalized boron nitride composite polypropylene materials with different contents.

FIG. 3 is a scanning electron microscope marked by the functionalized boron nitride composite polypropylene materials with different contents.

FIG. 4 is a comparison of marking of pure PP, PP/BN, BNNSs-OH/PP-g-MAH/PP.

FIG. 5 is a graph of water contact angles at the marking position, where a, b, c, d, e are pure PP, BNNSs-OH/PP-g-MAH/PP (0.5/10/100), BNNSs-OH/PP-g-MAH/PP (1/10/100), BNNSs-OH/PP-g-MAH/PP (1.5/10/100), BNNSs-OH/PP-g-MAH/PP (2/10/100), respectively.

Detailed Description

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

example 1:

(1) respectively weighing the following raw materials: BN, PP-g-MAH, PP;

(2) the preparation method of the functionalized boron nitride nanosheet comprises the following steps: 10g of BN particles are dispersed in 100mL of N, N-dimethylacetamide (DMAc) and ultrasonically stripped for 12 hours; then centrifuging at 3000r/min for 15min, filtering the upper layer dispersion liquid by a polytetrafluoroethylene membrane with the pore diameter of 0.1 mu m, then placing BNNSs precipitate at 100 ℃ for drying to obtain BNNSs, then carrying out heat treatment on 10g of BNNSs in air at 850 ℃ for 6h, and carrying out thermal oxidation on the BNNSs at high temperature in air to realize hydroxyl functionalization to obtain 11.8g of BNNSs-OH.

(3) And melting, blending and pressing the polypropylene, the compatilizer and the functionalized boron nitride nanosheet to obtain the PP/BNNSs-OH composite material capable of being marked by laser.

The PP/BNNSs-OH composite material prepared by the method can represent the morphology, the change of the structure and the performance of the organic/inorganic polypropylene composite material before and after laser marking, the mechanism of laser marking, the change of the structure and the performance and the mechanism of laser marking by means of laser marking performance test, scanning electron microscope, thermogravimetric analysis, XRD comparative analysis, contact angle comparative analysis, mechanical performance test and the like, and the specific test is as follows.

Firstly, carrying out laser marking on pure PP and composite polypropylene materials with different contents of functionalized boron nitride, wherein a, b, c, d and e in a figure 1 are respectively pure PP and BNNSs-OH/PP-g-MAH/PP

(0.5/10/100), BNNSs-OH/PP-g-MAH/PP (1/10/100), BNNSs-OH/PP-g-MAH/PP (1.5/10/100), BNNSs-OH/PP-g-MAH/PP (2/10/100) laser marking at a line speed of 200mm/s at 60% output. After the laser marking, only a few scattered black spots are seen on the PP plate from the graph a, which indicates that the pure PP plate has unobvious laser marking effect, lighter marks, unclear squares and less photothermal decomposition and carbonization. When the BNNSs-OH/PP-g-MAH/PP ratio is 0.5/10/100, the composite mark remains lighter and the marked square is intact, but the contrast is improved. When the BNNSs-OH/PP-g-MAH/PP ratio was 1/10/100, the composite mark remained lighter, but the contrast was already high. When the BNNSs-OH/PP-g-MAH/PP ratio is 1.5/10/100, the color of the laser mark becomes dark and clearly visible to the naked eye. When the BNNSs-OH/PP-g-MAH/PP ratio is 2/10/100, the color of the laser mark of the composite material becomes lighter, and the surface of the material is rougher, because the BNNSs-OH content is too high to absorb energy, and larger discontinuous holes are formed on the surface of the material. Therefore, the composite labeling effect is best when the BNNSs-OH/PP-g-MAH/PP ratio is 1.5/10/100.

Chromatic aberration analysis of marked (II) pure PP and functionalized boron nitride composite polypropylene materials with different contents

The error is larger by naked eyes, so that the chromatic aberration analysis is carried out on the composite material by a spectral chromatic aberration instrument. FIG. 2 shows the color differences of pure PP, BNNSs-OH/PP-g-MAH/PP (0.5/10/100), BNNSs-OH/PP-g-MAH/PP (1/10/100), BNNSs-OH/PP-g-MAH/PP (1.5/10/100), BNNSs-OH/PP-g-MAH/PP (2/10/100) at different powers. From the curves in the figure, it can be derived: with the increase of laser power, the color difference values of pure PP and PP composite materials are improved. The larger the laser power is, the better the laser marking effect is. Compared with pure PP, the color difference value of the composite material is obviously improved after BNNSs-OH is added into PP, which shows that BNNSs-OH has better absorption performance on laser. When the laser power is 30%, the color difference value of BNNSs-OH/PP-g-MAH/PP (1.5/10/100) is the largest after comparing the five curves, which shows that the laser marking effect of BNNSs-OH/PP-g-MAH/PP (1.5/10/100) is the best.

And thirdly, scanning electron microscope analysis of marked functionalized boron nitride composite polypropylene materials with different contents shows that a, b, c and d in the picture 3 are surface scanning electron microscope pictures of BNNSs-OH/PP-g-MAH/PP (0.5/10/100), BNNSs-OH/PP-g-MAH/PP (1/10/100), BNNSs-OH/PP-g-MAH/PP (1.5/10/100) and BNNSs-OH/PP-g-MAH/PP (2/10/100). As can be seen from the figure, the marked surface of the graph a and the marked surface of the graph b are very uniform in color, smooth and smooth in surface, free of obvious bubbles and cavities on the surface, very uniform and regular in distribution of carbonization points, good in laser marking effect, good in dispersion of BNNSs-OH in PP and not obvious in agglomeration phenomenon, and the dispersion of the set of formula in the design is better. The surface of the graph c is provided with uniform and dense holes, the carbonization effect is good, the holes of the graph d are not uniformly distributed, the aperture is larger, the surface is rougher, and the laser marking effect is not ideal.

In FIG. 5, a, b, c, d, e are pure PP, BNNSs-OH/PP-g-MAH/PP (0.5/10/100), BNNSs-OH/PP-g-MAH/PP (1/10/100), BNNSs-OH/PP-g-MAH/PP (1.5/10/100), and BNNSs-OH/PP-g-MAH/PP (2/10/100), wherein the angles are 70 degrees, 72 degrees, 78 degrees, 89 degrees, and 93 degrees respectively, and the contact angles are increased along with the increase of the content of the functionalized boron nitride. As the laser marking forms a carbonized structure on the surface of the PP, the roughness of the surface of the composite material is increased, and the hydrophobicity of the surface of the material is increased. Therefore, the marking performance of the composite material is improved along with the increase of the addition amount of the functionalized boron nitride.

Comparative example 1

And melting, blending and pressing the polypropylene, the compatilizer and the boron nitride nanosheet to obtain the PP/BNNSs-OH composite material capable of being marked by laser.

In fig. 4, a, b and c are graphs of laser marking effects of pure PP, BN/PP (1.5/100), BNNSs-OH/PP-g-MAH/PP (1.5/10/100) at the same laser power, respectively, it can be seen that pure PP does not respond to the laser by comparing the effects of three images, laser marking can form black marks when unmodified BN is added into PP, but the contrast and uniformity of the pattern are not as good as those of BNNSs-OH/PP-g-MAH/PP composite materials, so that the addition of modified boron nitride makes PP polymer have excellent marking effect.

The above description is only a few specific embodiments of the present invention, and it should be noted that many modifications and improvements may be made by those skilled in the art, and all modifications and improvements not beyond the scope of the claims should be considered as the protection scope of the present invention.

Claims (8)

1. A laser markable organic-inorganic polypropylene composite characterized by: the polypropylene composite material comprises the following components in parts by weight: 0.5-2 parts of functionalized boron nitride nanosheet, 10 parts of compatilizer and 100 parts of polypropylene; the functionalized boron nitride nanosheet is prepared by carrying out heat treatment on Boron Nitride Nanosheets (BNNSs) obtained by ultrasonic stripping for 6h at 850 ℃ to carry out functionalization, so as to obtain BNNSs-OH.

2. The laser markable organic-inorganic polypropylene composite according to claim 1 wherein: the compatilizer is polypropylene grafted maleic anhydride (PP-g-MAH), and the grafting rate of the maleic anhydride is 1%.

3. The laser markable organic-inorganic polypropylene composite according to claim 1 wherein: the boron nitride nanosheet is prepared by adopting a solvent-assisted ultrasonic stripping method, and specifically comprises the following steps: dispersing Boron Nitride (BN) particles in N, N-dimethylacetamide (DMAc), and ultrasonically stripping for 12 h; followed by centrifugation at 3000r/min for 15min, the upper dispersion was filtered through a polytetrafluoroethylene membrane with a pore size of 0.1 μm, and the product was dried at 100 ℃ to obtain BNNSs.

4. The laser markable organic-inorganic polypropylene composite according to claim 3 wherein: the purity of the Boron Nitride (BN) is 98 wt%, the particle size of the Boron Nitride (BN) is 0.1-0.4 mu m, and the crystal form belongs to a hexagonal crystal form.

5. A method for preparing the laser-markable organic-inorganic polypropylene composite according to claim 1, characterized in that: the preparation method comprises the following steps: and (3) melting and blending the polypropylene, the compatilizer and the functionalized boron nitride nanosheet, and then pressing and molding the mixture by using a flat-plate vulcanizing instrument to obtain the PP/BNNSs-OH composite material.

6. The method for preparing a laser markable organic-inorganic polypropylene composite according to claim 5, wherein: the melt blending is carried out by a torque rheometer at 190 ℃ for 3 minutes; and the modified functionalized boron nitride nanosheets are dried in an air-blowing drying oven at 70 ℃ for 30min before being melted and blended.

7. Use of an organic-inorganic polypropylene composite according to any one of claims 1 to 4 for the identification, marking and modification of polypropylene products.

8. The use of the organic-inorganic polypropylene composite according to claim 7, wherein the specific application method comprises: the surface laser marking treatment is directly carried out on the organic-inorganic polypropylene composite material by using a laser marking machine, the maximum output power of the laser marking machine is 50W, and the pulse laser wavelength is as follows: 1064 nm.

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