High-temperature-resistant and shear-resistant optical discoloration pigment and application thereof in plastics

Abstract

The application discloses a kind of high-temperature-resistant, shear-resistant optical discoloration pigment and its application in plastic, the optical discoloration pigment includes: at least one metal layer and flexible buffer layer between metal layer;Metal layer includes alternately deposited reflection layer and dielectric layer;The reflection layer material is at least one of aluminum, titanium, silver, copper, nickel, platinum or chromium, and the dielectric layer material is at least one of silicon dioxide, titanium dioxide, aluminum oxide, aluminum fluoride or magnesium fluoride;The flexible buffer layer material is at least one of butadiene styrene rubber, organic silicon elastomer or polyolefin.The application breaks through the application bottleneck of traditional optical discoloration pigment in injection molding process by special film system structure design and surface graft modification, and prepares high-temperature-resistant, shear-resistant optical discoloration pigment suitable for injection molding industry, gives plastic product unique visual effect and high added value, and is expected to become important driving force for product upgrading of injection molding industry.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of pigments, and particularly relates to a high-temperature-resistant and shear-resistant optical color-changing pigment and application thereof in plastics. BACKGROUND

[0002] With the increasing demand of the consumer market for product appearance personalization and high-endness, the optical color-changing pigment prepared based on the principle of thin film multi-beam interference is widely applied in the fields of coatings, inks and the like due to its unique goniochromatic and dynamic color characteristics. However, in the injection molding process, the traditional optical color-changing pigment faces harsh processing conditions such as high temperature (180-320 DEG C) and high shear, and is prone to problems such as pigment structure damage and color-changing performance attenuation.

[0003] Firstly, the traditional optical color-changing pigment has limited heat resistance, and can withstand a maximum of 230 DEG C in a short time (5-10 min), and the color-changing performance of the pigment will be obviously damaged when the temperature exceeds 230 DEG C. Secondly, the traditional optical color-changing pigment has a flaky structure (thickness < 1 mu m), and when the optical color-changing pigment is mixed with plastic particles by using high-shear equipment such as an internal mixer and a twin-screw extruder, the structure of the optical color-changing pigment will be severely damaged, and the color-changing performance will be lost. SUMMARY

[0004] Based on the above technical problems, the application provides a high-temperature-resistant and shear-resistant optical color-changing pigment and application thereof in plastics, which breaks through the application bottleneck of the traditional optical color-changing pigment in the injection molding process by special film system structure design and surface graft modification, and prepares a high-temperature-resistant and shear-resistant optical color-changing pigment suitable for the injection molding industry, so as to endow plastic products with unique visual effects and high added value, and is expected to become an important driving force for product upgrading in the injection molding industry.

[0005] The application provides a high-temperature-resistant and shear-resistant optical color-changing pigment, which comprises at least one metal layer and a flexible buffer layer between the metal layers; the metal layer comprises a reflection layer and a dielectric layer which are alternately deposited.

[0006] The reflection layer material is at least one of aluminum, titanium, silver, copper, nickel, platinum or chromium, the dielectric layer material is at least one of silicon dioxide, titanium dioxide, aluminum oxide, aluminum fluoride or magnesium fluoride, and the flexible buffer layer material is at least one of styrene-butadiene rubber, organic silicone elastomer or polyolefin.

[0007] In the present invention, on the one hand, by selecting at least one of nano-silicon dioxide, titanium dioxide, aluminum oxide, aluminum fluoride or magnesium fluoride as the dielectric layer, and at least one of aluminum, titanium, silver, copper, nickel, platinum or chromium as the reflective layer, the two are alternately deposited to form a metal layer, and the thickness of the film layer is controlled, and then the diffraction and interference principles of light are utilized to achieve an optical color-changing effect; on the other hand, by introducing a flexible buffer layer between the metal layers, specifically at least one of styrene-butadiene rubber, silicone elastomer or polyolefin, the mechanical stress during the injection molding process is effectively alleviated, the film layer is prevented from rupturing, and the high-temperature resistance is improved.

[0008] Preferably, the thickness of the reflective layer is 10-200 nm, the thickness of the dielectric layer is 10-100 nm, and the thickness of the flexible buffer layer is 250-500 nm;

[0009] Preferably, the optically chromic pigment has a thickness of 1-2 μm.

[0010] Preferably, the reflective layer and the dielectric layer are deposited by physical vapor deposition.

[0011] Preferably, the surface of the optically color-changing pigment is also grafted with a super-hydrophobic material;

[0012] Specifically, the optical color-changing pigment is subjected to a coupling reaction with a silane coupling agent, and then mixed with a super-hydrophobic lubricating material to obtain the optical color-changing pigment.

[0013] Preferably, the amount of the silane coupling agent is 3-8 wt % of the optically chromic pigment, and the amount of the super hydrophobic lubricating material is 12-20 wt % of the optically chromic pigment.

[0014] In the present invention, the use of a silane coupling agent enhances the compatibility of the optically variable pigment and the carrier resin, avoiding pigment agglomeration and performance degradation due to interface separation; the superhydrophobic lubricating material can construct a low-surface-energy nanostructure on the pigment surface, reducing the wettability of the melt to the pigment, further reducing shear force transmission, and improving high-temperature resistance.

[0015] Preferably, the silane coupling agent is an alkenyl silane coupling agent, preferably at least one of vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, vinyltri(β-methoxyethoxysilane), vinyltri-tert-butoxysilane, allyltrimethoxysilane, allylmethyldimethoxysilane or allyltriethoxysilane.

[0016] Preferably, the super hydrophobic lubricating material is fluorinated alkenyl cage-type polysilsesquioxane;

[0017] Specifically, the alkenyl cage-type polysilsesquioxane and fluorinated thiol are subjected to a thiol-ene click reaction to obtain the obtained product;

[0018] Preferably, the fluorinated mercaptan is at least one of trifluoromethyl mercaptan, 2-(perfluorohexyl)ethyl mercaptan, 3-fluoropropyl mercaptan, perfluorobutylpropyl mercaptan, perfluorohexyl mercaptan, perfluorooctyl mercaptan or perfluorodecyl mercaptan.

[0019] In the present invention, the optically chromic pigment is surface-grafted and modified by using an alkenyl silane coupling agent. Alkenyl groups are introduced onto the surface of the optically chromic pigment, which can undergo copolymerization with fluorinated alkenyl cage-type polysilsesquioxanes. Ultimately, a superhydrophobic material is grafted onto the surface of the optically chromic pigment, thereby further reducing shear force transmission and improving high-temperature resistance.

[0020] Preferably, the optically variable pigment is prepared by the following method:

[0021] S1. forming an isolation film layer on a carrier;

[0022] S2, alternately depositing a reflective layer and a dielectric layer on the isolation film layer to obtain a metal layer, and then coating the metal layer to form a flexible buffer layer, repeating the operation to obtain an optically variable film;

[0023] S3, separating the optically variable film from the carrier and crushing the film to obtain the optically variable pigment.

[0024] Preferably, the plastic further comprises: a carrier resin;

[0025] Preferably, the carrier resin is at least one of PP, PE, PS, PET, ABS, PVC or nylon;

[0026] Preferably, the mass ratio of the optically variable pigment to the carrier resin is 0.1-5:95-99.9.

[0027] Preferably, the plastic is prepared by the following method:

[0028] The optical color-changing pigment and the carrier resin are mixed uniformly and then granulated by twin-screw extrusion to obtain the plastic.

[0029] Beneficial effects of the present invention:

[0030] (1) In the present invention, a flexible buffer layer is introduced between the optically color-changing pigment film layers, which can effectively relieve the mechanical stress during the injection molding process and prevent the film layer from breaking.

[0031] (2) In the present invention, a silane coupling agent is used to enhance the compatibility between the pigment and the carrier resin, thereby avoiding pigment agglomeration and performance degradation caused by interface separation.

[0032] (3) In the present invention, the use of super-hydrophobic materials can construct a low surface energy nanostructure on the pigment surface, reduce the wettability of the melt to the pigment, reduce the shear force transmission, and improve the high temperature resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a rendering of an injection molded product corresponding to the optically color-changing pigment described in Example 1 of the present invention;

[0034] Figure 2 This is a schematic structural diagram of the fluorinated alkenyl cage-type polysilsesquioxane described in Example 3 of the present invention, wherein: for , for . DETAILED DESCRIPTION

[0035] Hereinafter, the present invention will describe the technical solution in detail through specific embodiments. However, it should be clearly stated that these embodiments are provided for illustration only and are not to be construed as limiting the scope of the present invention.

[0036] Example 1

[0037] This embodiment provides a high-temperature-resistant and shear-resistant optical color-changing pigment, comprising four metal layers and three flexible buffer layers located between the metal layers; the metal layers comprise reflective layers and dielectric layers formed by alternating deposition;

[0038] The reflective layer is an aluminum layer with a thickness of 100 nm, the dielectric layer is a silicon dioxide layer with a thickness of 50 nm, and the flexible buffer layer is a styrene-butadiene rubber layer with a thickness of 350 nm.

[0039] The above optical color-changing pigment is specifically prepared by the following method:

[0040] (1) Sodium chloride with a purity of 99.99% was evaporated under vacuum conditions to form a sodium chloride layer with a thickness of 40 nm on a glass substrate;

[0041] (2) Aluminum with a purity of 99.97% is evaporated under vacuum conditions to form a reflective layer with a thickness of 100 nm on the sodium chloride layer, and silicon dioxide with a purity of 99.99% is evaporated under vacuum conditions to form a dielectric layer with a thickness of 50 nm on the reflective layer; styrene-butadiene rubber emulsion is then applied, and after drying, a flexible buffer layer with a thickness of 350 nm is formed on the dielectric layer. The operation is repeated four times to obtain a deposited film;

[0042] (3) The deposited film was immersed in water to remove the sodium chloride layer to obtain an optically chromic film. The optically chromic film was mixed with water and ultrasonically crushed for 1.5 hours. After filtration, the film was washed with ethanol, dried, and sieved to obtain an optically chromic pigment with a D50 particle size of 10.2 μm.

[0043] Example 2

[0044] This embodiment provides a high-temperature-resistant and shear-resistant optical color-changing pigment, comprising four metal layers and three flexible buffer layers located between the metal layers; the metal layers comprise reflective layers and dielectric layers formed by alternating deposition;

[0045] The reflective layer is a chromium layer with a thickness of 100 nm, the dielectric layer is a magnesium fluoride layer with a thickness of 50 nm, and the flexible buffer layer is a silicone elastomer layer with a thickness of 350 nm.

[0046] The above optical color-changing pigment is specifically prepared by the following method:

[0047] (1) Sodium chloride with a purity of 99.99% was evaporated under vacuum conditions to form a sodium chloride layer with a thickness of 40 nm on a glass substrate;

[0048] (2) 99.95% pure chromium is evaporated under vacuum conditions to form a reflective layer with a thickness of 100 nm on the sodium chloride layer, and then 99.99% pure magnesium fluoride is evaporated under vacuum conditions to form a dielectric layer with a thickness of 50 nm on the reflective layer; polymethylvinylsiloxane is then coated and dried to form a flexible buffer layer with a thickness of 350 nm on the dielectric layer. The operation is repeated four times to obtain a deposited film;

[0049] (3) The deposited film was immersed in water to remove the sodium chloride layer to obtain an optically chromic film. The optically chromic film was mixed with water and ultrasonically crushed for 2 hours. After filtration, the film was washed with ethanol, dried, and sieved to obtain an optically chromic pigment with a D50 particle size of 14.7 μm.

[0050] Example 3

[0051] This embodiment provides a high-temperature-resistant and shear-resistant optical color-changing pigment, comprising four metal layers and three flexible buffer layers located between the metal layers; the metal layers comprise reflective layers and dielectric layers formed by alternating deposition;

[0052] The reflective layer is an aluminum layer with a thickness of 100 nm, the dielectric layer is a silicon dioxide layer with a thickness of 50 nm, and the flexible buffer layer is a styrene-butadiene rubber layer with a thickness of 350 nm.

[0053] The above optical color-changing pigment is specifically prepared by the following method:

[0054] (1) Sodium chloride with a purity of 99.99% was evaporated under vacuum conditions to form a sodium chloride layer with a thickness of 40 nm on a glass substrate;

[0055] (2) Aluminum with a purity of 99.97% is evaporated under vacuum conditions to form a reflective layer with a thickness of 100 nm on the sodium chloride layer, and silicon dioxide with a purity of 99.99% is evaporated under vacuum conditions to form a dielectric layer with a thickness of 50 nm on the reflective layer; styrene-butadiene rubber emulsion is then applied, and after drying, a flexible buffer layer with a thickness of 350 nm is formed on the dielectric layer. The operation is repeated four times to obtain a deposited film;

[0056] (3) Soaking the deposited film in water to remove the sodium chloride layer to obtain an optically chromic film, mixing the optically chromic film with water and ultrasonically crushing it for 1.5 hours, filtering it, washing it with ethanol, drying it, and sieving it to obtain an optically chromic pigment with a D50 particle size of 11.4 μm;

[0057] (4) Add the optically chromic pigment to anhydrous ethanol, then add 5 wt% of vinyl triethoxysilane by weight of the optically chromic pigment, stir and react for 12 hours, filter, dry, add to water and disperse evenly, then add 15 wt% of fluorinated alkenyl cage-type polysiloxane by weight of the optically chromic pigment, 0.2 wt% of potassium persulfate by weight, and 0.1 wt% of sodium bisulfite by weight, stir and react at 60° C. for 2 hours, centrifuge, wash, and dry to obtain an optically chromic pigment with a superhydrophobic material grafted on its surface;

[0058] The fluorinated alkenyl cage-type polysilsesquioxane is prepared by the following method: octavinyl cage-type polysilsesquioxane, 2-(perfluorohexyl)ethyl mercaptan, and 2,2-dimethoxy-2-phenylacetophenone are added to dichloromethane in a mass ratio of 10:2:0.5, and after ultrasonic dispersion, the mixture is irradiated with an ultraviolet lamp (365 nm) for 10 minutes, washed, and dried to obtain the fluorinated alkenyl cage-type polysilsesquioxane.

[0059] Comparative Example 1

[0060] This comparative example proposes an optical color-changing pigment, comprising four metal layers; the metal layers comprise a reflective layer and a dielectric layer formed by alternating deposition;

[0061] The reflective layer is an aluminum layer with a thickness of 100 nm, and the dielectric layer is a silicon dioxide layer;

[0062] The above optical color-changing pigment is specifically prepared by the following method:

[0063] (1) Sodium chloride with a purity of 99.99% was evaporated under vacuum conditions to form a sodium chloride layer with a thickness of 40 nm on a glass substrate;

[0064] (2) Aluminum with a purity of 99.97% is evaporated under vacuum conditions to form a reflective layer with a thickness of 100 nm on the sodium chloride layer, and then silicon dioxide with a purity of 99.99% is evaporated under vacuum conditions to form a dielectric layer with a thickness of 50 nm on the reflective layer. The operation is repeated four times to obtain a deposited thin film;

[0065] (3) The deposited film was immersed in water to remove the sodium chloride layer to obtain an optically chromic film. The optically chromic film was mixed with water and ultrasonically crushed for 1.5 hours. After filtration, the film was washed with ethanol, dried, and sieved to obtain an optically chromic pigment with a D50 particle size of 10.5 μm.

[0066] Comparative Example 2

[0067] This comparative example proposes an optical color-changing pigment, comprising four metal layers and three flexible buffer layers located between the metal layers; the metal layers comprise a reflective layer and a dielectric layer formed by alternating deposition;

[0068] The reflective layer is an aluminum layer with a thickness of 100 nm, the dielectric layer is a silicon dioxide layer with a thickness of 50 nm, and the flexible buffer layer is a styrene-butadiene rubber layer with a thickness of 350 nm.

[0069] The above optical color-changing pigment is specifically prepared by the following method:

[0070] (1) Sodium chloride with a purity of 99.99% was evaporated under vacuum conditions to form a sodium chloride layer with a thickness of 40 nm on a glass substrate;

[0071] (2) Aluminum with a purity of 99.97% is evaporated under vacuum conditions to form a reflective layer with a thickness of 100 nm on the sodium chloride layer, and silicon dioxide with a purity of 99.99% is evaporated under vacuum conditions to form a dielectric layer with a thickness of 50 nm on the reflective layer; styrene-butadiene rubber emulsion is then applied, and after drying, a flexible buffer layer with a thickness of 350 nm is formed on the dielectric layer. The operation is repeated four times to obtain a deposited film;

[0072] (3) Soaking the deposited film in water to remove the sodium chloride layer to obtain an optically chromic film, mixing the optically chromic film with water and ultrasonically crushing it for 1.5 hours, filtering it, washing it with ethanol, drying it, and sieving it to obtain an optically chromic pigment with a D50 particle size of 10.2 μm;

[0073] (4) The optically chromic pigment is added to anhydrous ethanol, and then 5 wt% of vinyltriethoxysilane is added to the optically chromic pigment. After stirring for 12 hours, the mixture is filtered and dried to obtain an optically chromic pigment with a silane coupling agent grafted on its surface.

[0074] The optically variable pigments obtained in the examples and comparative examples and PP were added to a high-speed mixer at a mass ratio of 0.5:99.5 and mixed evenly. The mixture was then granulated by twin-screw extrusion at a screw speed of 300 r / min, a screw aspect ratio of 44:1, and a temperature of 180-230°C to ensure uniform dispersion of the pigment. Color plates were then injection molded and their appearance was observed. The specific test results are shown in Table 1 below.

[0075] Among them, the angular color effect, flow marks and weld lines are all visually inspected; the color and glossiness are obtained by testing with the X-Rite CI64 integrating sphere colorimeter, with 5 points sampled and measured each time, and the middle value is taken.

[0076]

[0077] In the above table, the L value reflects the brightness of the product. The higher the L value, the stronger the reflected light at that angle. a represents the color change from green to red, b represents the color change from blue to yellow, and the C value represents the color saturation.

[0078] As can be seen from the above table, compared with Comparative Example 1, Example 1 has a very obvious angular color-changing effect of the product of Example 1, and both color saturation and brightness are significantly improved compared to Comparative Example 1; in Comparative Example 1, the surface flow marks of the product are more, and the weld line is also more serious. It can be seen that after the application introduces a flexible buffer layer between the optically variable pigment film layers, the mechanical stress during the injection molding process can be effectively alleviated, thereby protecting the integrity of the optically variable pigment structure and reducing the probability of the optically variable pigment being squeezed and broken during the injection molding process. Compared with Example 3, although Example 3 uses the same optically variable pigment as Example 1, the angular color-changing effect, color saturation, and brightness of the product of Example 3 are better than those of Example 1. Compared with Example 1, the optically variable pigment of Example 3 uses a super-hydrophobic material, which can construct a low surface energy nanostructure on the pigment surface, reduce the wettability of the melt to the pigment, reduce the shear force transmission, and improve high temperature resistance.

[0079] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A high temperature resistant and shear resistant optical color pigment, characterized in that: The optical color pigment comprises: at least two metal layers and a flexible buffer layer located between the metal layers; the metal layers comprise a reflective layer and a dielectric layer formed by alternating deposition; The reflective layer material is at least one of aluminum, titanium, silver, copper, nickel, platinum or chromium; the dielectric layer material is at least one of silicon dioxide, titanium dioxide, aluminum oxide, aluminum fluoride or magnesium fluoride; the flexible buffer layer material is at least one of styrene-butadiene rubber or silicone elastomer.

2. The high temperature resistant and shear resistant optical color pigment according to claim 1, characterized in that: The thickness of the reflective layer is 10-200 nm, the thickness of the dielectric layer is 10-100 nm, and the thickness of the flexible buffer layer is 250-500 nm; The optically chromic pigment has a thickness of 1-2 μm.

3. The high temperature resistant and shear resistant optical color pigment according to claim 1 or 2, characterized in that: The reflective layer and the dielectric layer are deposited by physical vapor deposition.

4. The high temperature resistant and shear resistant optical color pigment according to claim 1 or 2, characterized in that: The surface of the optically chromic pigment is also grafted with a super-hydrophobic material, specifically, the optically chromic pigment is coupled with a silane coupling agent, and then mixed with a super-hydrophobic lubricating material to obtain the result; The amount of the silane coupling agent used is 3-8 wt % of the optically chromic pigment, and the amount of the super hydrophobic lubricating material used is 12-20 wt % of the optically chromic pigment.

5. The high temperature resistant and shear resistant optical color pigment according to claim 4, characterized in that: The silane coupling agent is an alkenyl silane coupling agent, and the alkenyl silane coupling agent is at least one of vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, vinyltri(β-methoxyethoxysilane), vinyltri-tert-butoxysilane, allyltrimethoxysilane, allylmethyldimethoxysilane or allyltriethoxysilane.

6. The high temperature resistant and shear resistant optical color pigment according to claim 5, characterized in that: The super hydrophobic lubricating material is a fluorinated alkenyl cage-type polysilsesquioxane, specifically obtained by a thiol-ene click reaction of alkenyl cage-type polysilsesquioxane and fluorinated thiol; The fluorinated mercaptan is at least one of trifluoromethyl mercaptan, 2-(perfluorohexyl)ethyl mercaptan, 3-fluoropropyl mercaptan, perfluorobutylpropyl mercaptan, perfluorohexyl mercaptan, perfluorooctyl mercaptan or perfluorodecyl mercaptan.

7. The high temperature resistant and shear resistant optical color pigment according to claim 1 or 2, characterized in that: The optically variable pigment is prepared by the following method: S1. forming an isolation film layer on a carrier; S2, alternately depositing a reflective layer and a dielectric layer on the isolation film layer to obtain a metal layer, and then coating the metal layer to form a flexible buffer layer, repeating the operation to obtain an optically variable film; S3, separating the optically variable film from the carrier and crushing the film to obtain the optically variable pigment.

8. Use of the optically variable pigment according to any one of claims 1 to 7 in plastics.

9. The use of the optically color-changing pigment in plastics according to claim 8, characterized in that: The plastic further comprises: a carrier resin; The carrier resin is at least one of PP, PE, PS, PET, ABS, PVC or nylon; The mass ratio of the optical color-changing pigment to the carrier resin is 0.1-5:95-99.

9.

10. Use of the optically variable pigment in plastics according to claim 8 or 9, characterized in that: The plastic is prepared by the following method: The optical color-changing pigment and the carrier resin are mixed uniformly and then granulated by twin-screw extrusion to obtain the plastic.

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