WO2018130117A1 - Photochromic polypropylene composite, preparation method for same, and applications thereof - Google Patents

Abstract

Disclosed is a photochromic polypropylene composite, comprising the following components in terms of parts by weight: a polypropylene resin 96.5-98.5 parts and a photochromic microcapsule 0.5-2.5 parts. The core material of the photochromic microcapsule is a spiropyran, the wall material is a melamine formaldehyde resin, the wall material is formed by polymerizing formaldehyde and melamine, and the molar ratio of formaldehyde/melamine is 2.5/1-3/1. First, melamine and formaldehyde undergo an addition reaction in an environment of pH 7.5-8.5 to produce a hydroxymethyl melamine prepolymer, then a photochromic material spiropyran compound is dispersed in sodium dodecyl sulfate aqueous solution of a concentration of 0.2-1.0 wt%, then the hydroxymethyl melamine prepolymer is added to the solution, and the solution is regulated to a pH of 5.5-6.5 to produce a microcapsule emulsion, which is reacted at 80-90 °C for 3 h, rinsed, suction-filtered, and dried to produce the photochromic microcapsule. The photochromic polypropylene composite is capable of withstanding long-term exposure to sunlight, steadily changes colors back and forth, has great long-term weather resistance, and is widely applicable in interior and exterior decorative accessories for a vehicle.

Description

Photochromic polypropylene composition and preparation method and application thereof Technical field

The invention relates to the technical field of plastic modification, in particular to a photosensitive color changing polypropylene composition and a preparation method and application thereof.

Background technique

As people's individual needs increase, people hope that the color of automotive parts can change from a static single color to a color change with the change of the environment. Discoloration usually requires external environmental factors such as light and heat. For example, plastic changes from one color to another under the action of light, and changes back to its original color when it is protected from light.

CN 105111768 A and CN 103275509 A describe a color changing plastic process formulation which is a combination of a plastic body, a color changing agent, a photochromic material, an oxidizing agent and a stabilizer, said photochromic material being Spiropyrans. Under ultraviolet light irradiation, the CO bond in the colorless pyran structure is broken and opened to obtain a colored isoquinoline isomer. The isoquinoline can absorb visible light and develop color. The CO bond break in the spiropyran is completely reversible. After the ultraviolet light is removed, the open-loop body can return to the original spiro structure without coloration and become the original color, but photochemical side reactions occur during the reversible change, thereby affecting the number of cycles of the reversible color. And when subjected to strong light or strong heat, the spiropyran is susceptible to fatigue and loses its ability to change color, and thus fails to change color.

Summary of the invention

SUMMARY OF THE INVENTION An object of the present invention is to provide a photosensitive color-changing polypropylene composition which can be subjected to long-term illumination by sunlight, stably reversible, and has long-term weather resistance.

Another object of the present invention is to provide a process for the preparation of the above polypropylene composition.

A photosensitive color-changing polypropylene composition comprising, by weight, the following components:

Polypropylene resin 96.5～98.5 parts;

Photochromic microcapsules 0.5 to 2.5 parts;

The core material of the photosensitive color microcapsule is a spiropyran compound, the wall material is a melamine formaldehyde resin, and the melamine formaldehyde resin is polymerized by formaldehyde and melamine.

The microcapsule preparation process of the present invention comprises the steps of first adding an alkylation reaction of formaldehyde and melamine having a molar ratio of 2.5/1 to 3/1 at a pH of 7.5 to 8.5 to obtain a methylol melamine prepolymer, and then Dispersing the optically variable material spiropyran compound in an aqueous solution of sodium dodecyl sulfate having a concentration of 0.2 to 1.0 wt%, finally adding a methylol melamine prepolymer to the above solution, and adjusting the solution to a pH of 5.5. ～6.5 obtained microcapsule emulsion, reacted at 80-90 ° C for 3 h, washed, suction filtered, dried to obtain photochromic microcapsules.

The photosensitive color microcapsule has a particle diameter of 1 to 5 μm. When the particle size of the microcapsules is too large, the microcapsule emulsion is unstable and easy to be layered, the microcapsules are poorly coated, the discoloration is uneven, and the color difference before and after discoloration is large, and the number of times of the photochromic polypropylene composition can be changed back and forth. When the particle size of the microcapsules is too small, the amount of sodium dodecylsulfonate is too high, the residue is large, the smell is large, the cost is high, the processing is not easy to disperse, and the discoloration is uneven. When the particle diameter of the microcapsule is 1 to 5 um, the microcapsule has good coating property, the particle size is suitable, and the processing dispersibility is good.

The polypropylene resin is a random copolymer polypropylene resin, and the melt flow rate of the random copolymer polypropylene resin is 10 to 30 g/10 min under the load of 2.16 kg at 230 ° C according to ASTM D1238.

The photosensitive color-changing polypropylene composition further comprises 0.5-2 parts of an auxiliary agent selected from one or a mixture of an antioxidant, a light stabilizer, or a lubricant.

The antioxidant is a mixture of hindered phenols and phosphite antioxidants.

The light stabilizer is a hindered amine light stabilizer.

The lubricant is selected from one or a mixture of ethylene bis stearamide, erucamide, zinc stearate or silicone oil.

Mixing the polypropylene resin and the photochromic microcapsules into the twin-screw extruder from the main feed port located at one end of the twin-screw extruder, and adding one of an antioxidant, a light stabilizer or a lubricant if necessary The mixture or a mixture of the above-mentioned polypropylene resin and the photosensitive color-changing microcapsules is mixed, melt-kneaded, melt-kneaded at a temperature of 170 to 190 ° C, and extruded and granulated to obtain the polypropylene composition.

A photochromic polypropylene composition can be used in automotive dashboards, sub-dashboards, seats, door panels, bumpers or columns.

Compared with the prior art, the present invention has the following beneficial effects:

By selecting a photochromic microcapsule with a special structure, the microcapsule wall material makes the core material photo-deformation material not be destroyed by the ultraviolet light in the sunlight, thereby effectively protecting the optically variable material from the long-term illumination of the sunlight. Stable to change color back and forth, the prepared polypropylene composition has fast discoloration and good long-term weather resistance.

detailed description

The invention is further illustrated by the following detailed description of the preferred embodiments of the invention, but the embodiments of the invention are not limited by the following examples.

Raw material

Polypropylene resin, random copolymer polypropylene resin, J-570S, Lotte Chemical Co., Ltd., tested at 230 ° C, 2.16 kg load according to ASTM D-1238 melt flow rate of 28g/10min;

Photochromic powder, produced by Guangzhou Jingcai Pigment Technology Co., Ltd.;

Spiropyran compound, N-hydroxyethyl-3,3-dimethyl-6-nitroporphyrin spiropyran, produced by Guangzhou Wengjiang Chemical Reagent Co., Ltd.; toluene diisocyanate, BASF;

Polypropylene glycol, PPG2000, Shandong Lanxing Dongda Chemical Co., Ltd.;

Emulsifier Tween 80, Guangzhou Hao Chemical Co., Ltd.;

Dimethylolpropionic acid, Guangzhou Xinputai Chemical Co., Ltd.;

Antioxidants, light stabilizers, lubricants, melamine, formaldehyde, sodium dodecyl sulfonate are all commercially available.

Example 1-10 Preparation of Photochromic Microcapsules

First, a molar ratio of 2.5/1 to 3/1 of formaldehyde and melamine were added in a weak pH of 7.5 to 8.5 to obtain a methylol melamine prepolymer, and then the optically variable material spiropyran compound was dispersed at 0.2. - 1.0 wt% concentration of sodium dodecyl sulfate in aqueous solution, finally adding methylol melamine prepolymer to the above solution, and adjusting the solution to a pH of 5.5 to 6.5 to obtain a microcapsule emulsion, 80-90 ° C After reacting for 3 hours, washing, suction filtration and drying, a photochromic microcapsule was obtained; wherein the molar ratio of formaldehyde to melamine in Example 1-2 was 2.5/1, and the molar ratio of formaldehyde to melamine in Example 3-4 was 2.75/ 1. The molar ratio of formaldehyde to melamine in Examples 5-10 was 3/1.

The concentration of the above aqueous sodium dodecylsulfonate solution is 0.8% by weight, and the product is a photosensitive color-changing microcapsule A having a particle diameter of 0.5 um.

The concentration of the above aqueous sodium dodecylsulfonate solution is 0.7% by weight, and the product is a photosensitive color-changing microcapsule B having a particle diameter of 1 μm.

The concentration of the above aqueous sodium dodecyl sulfate solution is 0.6% by weight, and the product is a photosensitive color-changing microcapsule C having a particle diameter of 2.5 μm.

The concentration of the above aqueous sodium dodecylsulfonate solution is 0.5% by weight, and the product is a photosensitive color-changing microcapsule D having a particle diameter of 4 μm.

The concentration of the above aqueous sodium dodecyl sulfate is 0.4% by weight, and the product is a photosensitive color-changing microcapsule E having a particle size of 5 μm.

The above aqueous sodium dodecylsulfonate solution has a concentration of 0.3% by weight, and the product is a photosensitive color-changing microcapsule F having a particle diameter of 7 μm.

Comparative Example 4 Preparation of Photochromic Microcapsules

The spiropyran compound was added to a three-necked flask, and 20 ml of toluene diisocyanate (TDI), 10 ml of polypropylene glycol, 1.5 ml of emulsifier Tween 80, and 23 ml of acetone were slowly added dropwise, stirred at a low speed of 200 r/min for 10 min, and reacted at 46 ° C for 30 min. Dimethylolpropionic acid (DMPA) was added, the temperature was raised to 60 ° C, the mixture was stirred at 1500 r/min at a high speed, and the reaction was carried out for about 30 minutes, cooled and dried, and ground into a powder to obtain a photosensitive color-changing microcapsule G having a particle diameter of 2.5 μm.

Preparation of Photosensitive Discoloration Polypropylene Compositions of Examples 1-10 and Comparative Example 4:

According to the formulation of Table 1, the polypropylene resin, the antioxidant, the light stabilizer, the lubricant and the photochromic microcapsules are mixed and added to a twin-screw extruder for melt-kneading, and the melt-kneading temperature is 170 to 190 ° C. Extrusion granulation gave the polypropylene composition, which was then injection molded into a color plate for testing its color change properties.

Comparative Example 1-3 Preparation of Photochromic Polypropylene Composition:

According to the formulation of Table 1, polypropylene resin, antioxidant, light stabilizer, lubricant and photosensitive color changing powder are mixed and added to a twin-screw extruder for melt-kneading, and the melt-kneading temperature is 170-190 ° C. Granulation was carried out to obtain the polypropylene composition, and then the composition was injection molded into a color plate for testing its discoloration property.

Performance test method

(1) Observing whether the polypropylene composition of the present invention can be stably changed back and forth after being irradiated by visually observing the color before the swatch illumination and the color after 30 days of sunlight irradiation;

(2) The L, a, b and ΔE of the swatch before the sun illumination and after 30 days of sunlight are measured by a color difference meter of Color-Eye 7000a. The Lab color model is composed of illuminance L and related colors a and b. composition elements, L represents illuminance, brightness equivalent to, a represents the range from magenta to green, b represents the range from yellow to blue, in table 1 below, without sunlight for 30 days using color swatch L _1, a ₁ and b ₁ indicate that the color after 30 days of exposure to sunlight is represented by L ₂ , a ₂ , and b ₂ , and the color difference ΔE = ((L _{2 -} L ₁ ) ² + (a ₂ - a ₁ ) ² + before and after discoloration (b ₂ -b ₁ ) ² ) ^1/2 ;

(3) Melt flow rate, 230 ° C, 2.16 kg load, tested in accordance with ASTM D-1238.

Table 1 Example 1-10 and Comparative Examples 1-4, each group distribution ratio (parts by weight) and each performance test result

Continued Table 1

It can be seen from the data in Table 1 that the polypropylene composition prepared in the example has a small color difference ΔE after 30 days of continuous sunlight illumination, and can be changed back to the original color when the light is removed. The polypropylene composition of the photosensitive color-changing microcapsules which were not subjected to microcapsule coating or the photosensitive color-changing microcapsules which were made of micro-capsules in the comparative example had a large color difference ΔE after continuous illumination for 30 days, and could not be changed back to the original color when the light was removed, and was ineffective. .

Claims (10)

A photosensitive color-changing polypropylene composition characterized by comprising the following components by weight: Polypropylene resin 96.5～98.5 parts; Photochromic microcapsules 0.5 to 2.5 parts; The core material of the photosensitive color microcapsule is a spiropyran compound, and the wall material is a melamine formaldehyde resin. A photosensitive color-changing polypropylene composition according to claim 1, wherein the photosensitive color-changing microcapsule preparation process comprises the steps of firstly adding formaldehyde and melamine in a molar ratio of 2.5/1 to 3/1. The addition reaction occurs in the environment of pH 7.5-8.5 to obtain a methylol melamine prepolymer, and then the optically variable material spiropyran compound is dispersed in an aqueous solution of sodium dodecyl sulfate of 0.2-1.0 wt%, and finally The methylol melamine prepolymer was added to the above solution, and the solution was adjusted to a pH of 5.5 to 6.5 to obtain a microcapsule emulsion, which was reacted at 80-90 ° C for 3 hours, washed, filtered, and dried to obtain a photosensitive color-changing microcapsule. The photosensitive color-changing polypropylene composition according to claim 1, wherein the photosensitive color-changing microcapsule has a particle diameter of from 1 to 5 μm. The photosensitive color-changing polypropylene composition according to claim 1, wherein the polypropylene resin is a random copolymer polypropylene resin, which is tested according to ASTM D1238 at 230 ° C under a load of 2.16 kg. The polypropylene resin has a melt flow rate of 10 to 30 g/10 min. The photosensitive color-changing polypropylene composition according to claim 1, wherein the photosensitive color-changing polypropylene composition further comprises 0.5-2 parts of an auxiliary agent selected from the group consisting of antioxidants and light. One or a mixture of stabilizers or lubricants. A photosensitive color-changing polypropylene composition according to claim 1, wherein said antioxidant is a mixture of hindered phenols and phosphite antioxidants. A photosensitive color-changing polypropylene composition according to claim 1, wherein the light stabilizer is a hindered amine light stabilizer. A photosensitive color-changing polypropylene composition according to claim 1, wherein the lubricant is one or more selected from the group consisting of ethylene bis stearamide, erucamide, zinc stearate or silicone oil. a mixture. The method for preparing a photosensitive color-changing polypropylene composition according to any one of claims 1 to 8, comprising the steps of: mixing a polypropylene resin and a photosensitive color-changing microcapsule from a twin-screw extruder The main feed port at one end is added to the twin-screw extruder, and if necessary, a mixture of one or more of an antioxidant, a light stabilizer or a lubricant is additionally added and the above polypropylene resin and the photosensitive color-changing microcapsule are mixed together. Thereafter, the mixture was melt-kneaded, and the melt kneading temperature was 170 to 190 ° C, and extrusion granulation was carried out to obtain the polypropylene composition. Use of a photosensitive color-changing polypropylene composition according to any of claims 1-8 in automotive dashboards, sub-dashboards, chairs, door panels, bumpers or columns.