WO2018130120A1 - Thermochromic polypropylene composite, preparation method for same, and applications thereof - Google Patents

Abstract

Disclosed is a thermochromic polypropylene composite, comprising the following components in terms of parts by weight: a polypropylene resin 95-99 parts and a thermochromic microcapsule 0.5-3 parts. The core material of the thermochromic microcapsule is a triphenylmethane metal complex, the wall material of the thermochromic microcapsule 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 the triphenylmethane metal complex is dispersed in a sodium dodecyl sulfate aqueous solution of 0.2-1.0 wt% concentration, finally the hydroxymethyl melamine prepolymer is added to the described solution, 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 thermochromic microcapsule. The thermochromic polypropylene composite has great long-term heat resistance, is widely applicable in the instrument panel, auxiliary instrument panel, seats, door panels, bumpers or columns of a vehicle.

Description

Thermosensitive color change polypropylene composition and preparation method and application thereof Technical field

The invention relates to the technical field of plastic modification, in particular to a temperature-sensitive discoloration 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. The heat-induced discoloration is thermochromic, which means that when the temperature reaches a characteristic discoloration temperature, the color-changing material changes from one color to another.

At present, thermochromic color is mainly used in the field of coatings and inks, and has not been involved in the plastics industry. CN 102615890A describes a thermochromic plastic which is composed of five layers of materials, including a plastic base layer, which is provided with a transparent protective film on both sides of the plastic base layer and is heat-pressed on the plastic base layer, and the outer surface of the transparent protective film is also coated with a layer. A color changing ink layer containing a thermochromic powder. The thermochromic plastic is still coated with a thermochromic ink on the surface of the plastic to achieve discoloration. At present, temperature-sensitive discoloration in plastic bodies has not been reported.

Summary of the invention

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermochromic polypropylene composition which can effectively protect a discolored component, can withstand long-term heat, and stably discolors back and forth.

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

A thermochromic polypropylene composition comprising, by weight, the following components:

Polypropylene resin 95~99 parts

Temperature-sensitive color microcapsules 0.5 to 3 parts;

The core material of the thermochromic microcapsule is a triphenylmethane metal complex, and the wall material is a melamine formaldehyde resin.

The preparation method of the melamine formaldehyde resin of the invention comprises the following steps: firstly adding formaldehyde and melamine in 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. Then, the triphenylmethane metal complex is dispersed in a 0.2-1.0 wt% aqueous solution of sodium dodecyl sulfate, and finally the methylol melamine prepolymer is added to the above solution, and the solution is adjusted to pH. The microcapsule emulsion was obtained at 5.5-6.5, reacted at 80-90 ° C for 3 h, and finally washed, filtered, and dried to obtain a thermochromic microcapsule.

The thermochromic microcapsule has a particle size of 10 to 50 um. 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, the color difference before and after discoloration is large, the discoloration is uneven, and the color difference before and after discoloration is large, and the temperature is sensitive. The number of times of discoloration of the discolored polypropylene composition is reduced; when the particle size of the microcapsule is too small, the amount of sodium dodecylsulfonate is too high, the residue is large, the smell is large, the cost is high, and the processing is not easy to disperse, which affects the uniformity of discoloration. Sex. When the particle size of the microcapsules is 10 to 50 um, the microcapsules have good coating properties, suitable particle size, and good processing and dispersibility.

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 thermochromic polypropylene composition further comprises from 0.5 to 2 parts of an adjuvant selected from the group consisting of one or more of an antioxidant, a light stabilizer, or a lubricant.

The antioxidant is a mixture of hindered phenols and phosphite antioxidants, specifically 1010, 1076, 3114, 168.

The light stabilizer is a hindered amine light stabilizer, and specifically, a mixture of one or more of UV～3808PP5, LA～402XP or LA～402AF may be selected.

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

A method for preparing a thermochromic polypropylene composition, comprising the steps of: mixing a polypropylene resin and a thermochromic microcapsule into a twin-screw extruder, adding an antioxidant, and stabilizing if necessary One or a mixture of the agent or the lubricant is mixed with the above polypropylene resin and the thermochromic microcapsule, and then melt-kneaded, and the melt-kneading temperature is 170 to 190 ° C, and extrusion granulation is carried out to obtain the Thermochromic polypropylene composition.

A thermochromic 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 adding the temperature-sensitive color-changing microcapsules, the heat resistance of the micro-capsule wall material is good, so that the temperature-changing material of the core material is less affected by heat, so that the color-changing component can be effectively protected, so that it can withstand long-term heat and can stably It changes color back and forth, and can continue to change color after baking at 100 ° C for 720 h, and has excellent long-term heat 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;

Triphenylmethane metal complex, Shanghai Anzhen Biological Co., Ltd.;

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

Toluene diisocyanate, BASF;

Polypropylene glycol, PPG2000, Shandong Lanxing Dongda Chemical;

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 1-11 Preparation of thermochromic microcapsules:

The addition reaction of formaldehyde and melamine with a molar ratio of 2.5/1 to 3/1 at pH 7.5-8.5 gives a methylol melamine prepolymer, and then the triphenylmethane metal complex is dispersed at 0.2-1.0. In the wt% concentration of sodium dodecyl sulfate aqueous solution, the methylol melamine prepolymer is finally added to the above solution, and the solution is adjusted to a pH of 5.5 to 6.5 to obtain a microcapsule emulsion, and the reaction is carried out at 80-90 ° C for 3 h. After washing, suction filtration and drying, a thermochromic microcapsule is obtained; wherein the molar ratio of formaldehyde to melamine in Example 1-2 is 2.5/1, and the molar ratio of formaldehyde to melamine in Example 3-5 is 2.75/1. The molar ratio of formaldehyde to melamine in Examples 6-11 was 3/1.

The concentration of the above aqueous sodium dodecyl sulfate is 0.8% by weight, and the product is a thermochromic microcapsule A having a particle size of 5 um.

The concentration of the above aqueous sodium dodecyl sulfate is 0.7 wt%, and the product is a thermochromic microcapsule B having a particle size of 10 um.

The concentration of the above aqueous sodium dodecyl sulfate is 0.6 wt%, and the product is a thermochromic microcapsule C having a particle size of 20 μm.

The concentration of the above aqueous sodium dodecyl sulfate is 0.5% by weight, and the product is a thermochromic microcapsule D having a particle size of 40 um.

The concentration of the above aqueous sodium dodecyl sulfate is 0.4% by weight, and the product is a thermochromic microcapsule E having a particle size of 50 μm.

The concentration of the above aqueous sodium dodecyl sulfate was 0.3% by weight, and the product was a thermochromic microcapsule F having a particle size of 70 μm.

Comparative Example 4 Preparation of thermochromic microcapsules:

The triphenylmethane metal complex 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, and stirred at a low speed of 200 r/min for 10 minutes at 46 ° C. After reacting for 30 minutes, dimethylolpropionic acid (DMPA) was added, the temperature was raised to 60 ° C, and the mixture was stirred at 1500 r/min at a high speed for about 30 minutes, cooled and dried, and ground to obtain a thermochromic microcapsule G having a particle size of 20 μm.

Preparation of Thermosensitive Discoloration Polypropylene Compositions of Examples 1-11 and Comparative Example 4:

According to the formulation of Table 1, the random copolymer polypropylene resin, antioxidant, light stabilizer, lubricant and thermochromic microcapsules were mixed and added to a twin-screw extruder for melt-kneading. The melt-kneading temperature was 170. 190 ° C, extrusion granulation, the polypropylene composition was obtained, and then the composition was injection molded into a color plate for testing its color change property.

Preparation of Comparative Example 1-3 Thermochromic Polypropylene Composition:

According to the formulation of Table 1, the random copolymer polypropylene resin, antioxidant, light stabilizer, lubricant and thermochromic powder are mixed and added to a twin-screw extruder for melt-kneading. The melt-kneading temperature is 170~ The polypropylene composition was obtained by extrusion granulation at 190 ° C, and then the composition was injection molded into a color plate for testing its color change property.

Performance evaluation method

(1) Observing whether the polypropylene composition of the present invention can be stably changed back and forth after being heated by visually observing the color before baking of the color plate, the color after baking at 720 ° C for 720 hours, and the color after baking for 24 hours. ;

(2) Determine the L, a, b and ΔE of the swatch before baking and 720h after baking at 100 °C by the color difference meter of Color-Eye 7000a. The Lab color model is composed of illuminance L and related colors a and b. The composition of the elements, L represents the illuminance, which corresponds to the brightness, a represents the range from magenta to green, b represents the range from yellow to blue, and the color of the swatch that is not baked at 100 ° C for 720 h in Table 1 below uses L ₁ , a ₁ , b ₁ indicates that the color after baking at 100 ° C for 720 h is represented by L ₂ , a ₂ , b ₂ , and before and after discoloration ΔE = ((L _{2 -} L ₁ ) ² + (a ₂ - a ₁ ) ² +(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 Distribution ratios (parts by weight) of each of Examples 1 to 11 and Comparative Examples 1 to 4 and respective performance test results

Continued Table 1

It can be seen from the data in Table 1 that the comparative example uses a thermosensitive color-changing powder which is not subjected to microcapsule coating or a thermosensitive color-changing microcapsule which is made of a wall material, and the polypropylene composition obtained by baking at 720 ° C for 720 h has a large color difference ΔE. And can not change back to the original color when not baking, has failed, and the polypropylene composition provided in the embodiment has a small color difference ΔE after baking at 100 ° C for 720 hours, and can still change back to the original color, long-term heat resistance Excellent, it can be concluded that the thermochromic polypropylene composition provided by the present invention can effectively protect the color-changing component, thereby being able to withstand long-term heat and stably change back and forth.

Claims (10)

1. A thermochromic polypropylene composition characterized by the following components by weight:

   Polypropylene resin 95~99 parts

   Temperature-sensitive color microcapsules 0.5 to 3 parts;

   The core material of the thermochromic microcapsule is a triphenylmethane metal complex, and the wall material is a melamine formaldehyde resin.
2. The thermochromic polypropylene composition according to claim 1, wherein the method for preparing the thermochromic microcapsule comprises the following steps: firstly, a molar ratio of 2.5/1 to 3/1 of formaldehyde Addition reaction with melamine at a pH of 7.5-8.5 to obtain a methylol melamine prepolymer, and then dispersing the triphenylmethane metal complex in a 0.2-1.0 wt% aqueous solution of sodium dodecyl sulfate Finally, the methylol melamine prepolymer is added to the above solution, and the solution is adjusted to a pH of 5.5 to 6.5 to obtain a microcapsule emulsion, which is reacted at 80-90 ° C for 3 hours, washed, filtered, and dried to obtain a thermochromic color. capsule.
3. The thermochromic polypropylene composition according to claim 1, wherein the thermochromic microcapsule has a particle diameter of 10 to 50 μm.
4. The thermochromic 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 copolymer polypropylene resin has a melt flow rate of 10 to 30 g/10 min.
5. A thermochromic polypropylene composition according to claim 1, wherein said thermochromic polypropylene composition further comprises 0.5 to 2 parts of an auxiliary agent selected from the group consisting of antioxidants. a mixture of one or more of a light stabilizer or a lubricant.
6. A thermochromic polypropylene composition according to claim 1, wherein said antioxidant is a mixture of hindered phenols and phosphite antioxidants.
7. A thermochromic polypropylene composition according to claim 1, wherein said light stabilizer is a hindered amine light stabilizer.
8. A thermochromic polypropylene composition according to claim 1, wherein the lubricant is selected from one of ethylene bis stearamide, erucamide, zinc stearate or silicone oil or Several mixtures.
9. The method for preparing a thermochromic polypropylene composition according to any one of claims 1 to 8, comprising the steps of: mixing a polypropylene resin and a thermochromic microcapsule from a main feed port; Adding to a twin-screw extruder, if necessary, adding one or more of an antioxidant, a light stabilizer or a lubricant, and mixing the above-mentioned polypropylene resin and thermochromic microcapsule, and then melting and kneading The melt-kneading temperature was 170 to 190 ° C, and extrusion granulation was carried out to obtain the thermochromic polypropylene composition.
10. Use of a thermochromic polypropylene composition according to any one of claims 1 to 8 in an automobile instrument panel, a sub-dashboard, a seat, a door panel, a bumper or a column.