CN110643063B

CN110643063B - TPU (thermoplastic polyurethane) foamed bead containing thin-layer graphene permanent antistatic light gray coating and preparation method and application thereof

Info

Publication number: CN110643063B
Application number: CN201910958702.3A
Authority: CN
Inventors: 戴成章; 戴尧
Original assignee: Shanghai Yucheng Polymer Material Co ltd
Current assignee: Shanghai Yucheng Polymer Material Co ltd
Priority date: 2019-10-10
Filing date: 2019-10-10
Publication date: 2022-07-08
Anticipated expiration: 2039-10-10
Also published as: CN110643063A

Abstract

The invention discloses TPU foaming beads containing a thin graphene permanent antistatic light gray coating, which comprise: (1) TPU expanded beads; and (2) spraying the aqueous polyurethane solution containing the thin graphene layer on the surface of the TPU foamed bead to form an aqueous polyurethane antistatic coating with the thickness of 10-200 mu m; cleaning and degreasing the surface of the TPU foamed bead by ultrasonic waves and carrying out low-temperature plasma activation treatment on the surface of the TPU foamed bead; the aqueous polyurethane solution comprises: the water-based paint comprises water-based polyurethane, thin-layer graphene water-based slurry, a water-based antioxidant, water-based titanium dioxide slurry, a cross-linking agent and deionized water. The TPU expanded bead containing the thin graphene permanent antistatic light gray coating has uniform and stable antistatic property, and the preparation process is green and environment-friendly.

Description

TPU (thermoplastic polyurethane) foamed bead containing thin-layer graphene permanent antistatic light gray coating and preparation method and application thereof

Technical Field

The invention relates to the field of high polymer materials, and particularly relates to TPU (thermoplastic polyurethane) foamed beads containing a thin graphene permanent antistatic light gray coating, and a preparation method and application thereof.

Background

The thermoplastic polyurethane TPU foaming material has good rebound resilience, impact resistance, wear resistance, compression resistance, buffering property, oil resistance and other properties, is mainly applied to the shoe material industry, is also applied to a plurality of fields such as runways, helmets, logistics packaging materials, household new materials, education equipment, sports goods, automotive interiors and the like, and has great development potential.

However, thermoplastic polyurethane TPU materials are easily triboelectrically charged due to their high electrical insulation properties, but in some locations in the modern electronics industry, antistatic properties are required to be imparted to the materials.

At present, the following methods are mainly used for modifying antistatic polymer materials: A) the method of adding antistatic agent, the antistatic agent is mainly two types, one is organic micromolecule antistatic agent, it has organic matter of surfactant characteristic structure, there is easy to run off the disadvantage that the antistatic effect is not lasting, another type is macromolecule permanent antistatic agent, this type of antistatic agent is the hydrophilic high polymer with large molecular weight, they have better compatibility with matrix resin, therefore the antistatic effect is stable and lasting, but this type of antistatic agent consumption is greater (10% -20%), the cost is higher, change the physical property of matrix resin greatly, and still rely on the ambient humidity; B) the method for adding the conductive filler is characterized in that various inorganic conductive fillers are usually doped into a resin matrix, the prepared composite material can realize a permanent antistatic effect in the true sense independent of the environmental humidity, the inorganic conductive fillers mainly comprise metal fillers and carbon fillers, the metal fillers mainly comprise metal powder, metal fibers and metal oxides (SnO, CuO, ZnOw and the like), the metal powder and the metal fibers have the defects of easy oxidation, large addition amount and the like, and the conventional metal oxides have the defects of no oxidation problem but large addition amount so as to influence the mechanical property of the material and the like. The carbon-based filler mainly comprises the traditional carbon-based filler (conductive carbon black, graphite and carbon fiber) and the novel carbon-based filler (a carbon nano-tube and graphene), and the traditional carbon-based filler has the biggest defects of black, large addition amount and poor product color adjustability; the novel carbon material has less addition amount and less influence on the physical property and foaming of matrix resin, wherein the addition of the thin graphene and the titanium dioxide can prepare a light gray permanent antistatic high polymer material, so that the material has color adjustability and higher application value, but the novel carbon nano conductive material has high price, and if the novel carbon nano conductive material is added into a matrix of TPU foaming resin, the cost is higher, and the nano carbon material is dispersed in a TPU melt to reach a nano level, which also is a technical problem.

Disclosure of Invention

The invention aims to solve the problems and provides TPU foamed beads containing a thin graphene permanent antistatic light gray coating, a preparation method and application thereof.

The purpose of the invention is realized as follows:

the TPU expanded bead containing the thin-layer graphene permanent antistatic light gray coating comprises the following components in percentage by weight:

(1) TPU expanded beads; and

(2) spraying an aqueous polyurethane solution containing a thin graphene layer on the surface of the TPU foamed beads to form an aqueous polyurethane antistatic coating with the thickness of 10-200 mu m;

the TPU foamed beads are prepared by adopting an extrusion foaming-underwater granulating method or a kettle gas impregnation method, and the surfaces of the TPU foamed beads are subjected to ultrasonic surface cleaning and degreasing and low-temperature plasma activation treatment;

the aqueous polyurethane solution comprises: the water-based paint comprises water-based polyurethane, thin-layer graphene water-based slurry, a water-based antioxidant, water-based titanium dioxide slurry, a cross-linking agent and deionized water.

The aqueous polyurethane solution in the TPU foamed bead containing the thin graphene permanent antistatic light gray coating is carboxyl type thermoplastic aqueous polyurethane emulsion.

The addition amount of the thin graphene in the aqueous slurry of the thin graphene in the TPU foamed bead containing the thin graphene permanent antistatic light gray coating is 0.25 to 1.0 weight percent of the total amount of the aqueous polyurethane antistatic coating on the surface of the TPU foamed bead.

The water antioxidant in the TPU foamed bead containing the thin graphene permanent antistatic light gray coating is a dispersion liquid containing hindered phenol antioxidants; the amount of the water-based antioxidant is 0.5-5% of the solid amount of the water-based polyurethane solution.

The aqueous antioxidant in the TPU expanded beads containing the thin graphene permanent antistatic light gray coating is preferably an aqueous antioxidant dispersion containing triethylene glycol ether-bis (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate.

The amount of titanium dioxide in the aqueous titanium dioxide slurry in the TPU foamed bead containing the thin graphene permanent antistatic light gray coating is 2-10% of the solid content of the aqueous polyurethane solution.

The cross-linking agent in the TPU foamed bead containing the thin graphene permanent antistatic light gray coating is an aziridine type cross-linking agent, the cross-linking agent is used for improving the water resistance of the aqueous polyurethane coating, the cross-linking degree needs to be controlled, the aqueous polyurethane coating coated on the surface of the TPU foamed bead after drying does not lose the thermal bonding capacity, and the addition amount of the cross-linking agent is 0.05-2% of the mass percent of the aqueous polyurethane emulsion.

The solid content of the aqueous polyurethane emulsion containing the thin graphene in the TPU foamed bead containing the thin graphene permanent antistatic light gray coating is 1-20%.

The aqueous polyurethane solution in the TPU foamed bead containing the thin graphene permanent antistatic light gray coating also comprises an aqueous color paste.

The proportion of the TPU expanded beads in the TPU expanded beads containing the thin graphene permanent antistatic light gray coating is 0.1-0.8 g/cm³。

The invention provides a preparation method of TPU (thermoplastic polyurethane) expanded beads containing a thin graphene permanent antistatic light gray coating, which adopts a spray coating and drying device and at least comprises the following steps:

a drum-shaped rotating drum with an open upper end;

a hot air pipe with an outlet communicated with the interior of the rotary drum and connected with a hot air blowing device outside the rotary drum;

a stirrer installed in the drum for assisting in dispersing the TPU expanded beads; and

a spray gun with an outlet positioned in the rotary drum and connected with a liquid tank outside the rotary drum through a pipeline for atomization;

the preparation method of the TPU expanded beads containing the thin graphene permanent antistatic light gray coating comprises the following steps:

1) cleaning the surface of the TPU foamed beads by adopting an ultrasonic cleaning process, and drying at 50-100 ℃ after cleaning;

2) processing the surface of the cleaned TPU foamed beads by adopting a low-temperature plasma processing process;

3) uniformly stirring waterborne polyurethane, thin-layer graphene waterborne slurry, a waterborne antioxidant, waterborne titanium dioxide slurry, a cross-linking agent and deionized water, and then matching with ultrasonic dispersion to prepare a waterborne polyurethane solution containing thin-layer graphene for later use;

4) adding the TPU foamed beads into a rotary drum of a spray drying device, starting the rotary drum to rotate and heat, introducing hot air to dry materials, after the TPU foamed beads are preheated to a set drying temperature of 80-105 ℃, starting a stirrer to assist in dispersing the TPU foamed beads, spraying the aqueous polyurethane spray solution containing the thin-layer graphene prepared in the step 3) on the surfaces of the TPU foamed beads by using a spray gun, continuously heating and drying the surfaces of the TPU foamed beads while intermittently spraying the aqueous polyurethane spray solution containing the thin-layer graphene for multiple times in the process of uniformly rolling and dispersing the TPU foamed beads until the aqueous polyurethane spray solution is completely consumed, stopping spraying, finally forming a uniform coating on the surfaces of the TPU foamed beads, and continuously drying until the surface coating of the TPU foamed beads is dried.

In the preparation method of the TPU foamed bead containing the thin graphene permanent antistatic light gray coating, in the step 1), the ultrasonic cleaning process adopts a water-based cleaning agent containing at least one anionic surfactant or nonionic surfactant with the concentration of 1-20%, and the ultrasonic frequency is>20KHz, power density>0.3W/cm²。

In the preparation method of the TPU foamed bead containing the thin graphene permanent antistatic light gray coating, in the step 2), the working gas adopted by the low-temperature plasma treatment process is one or a mixed gas of argon, nitrogen, oxygen, ammonia and carbon dioxide, the gas flow is 30-900 sccm, the working pressure is 10-300 Pa, the treatment time is 20 s-10 min, the temperature is 20-130 ℃, and the treatment power is 1500-12000W.

In the preparation method of the TPU foamed beads containing the thin graphene permanent antistatic light gray coating, the rotary drum is arranged on a base, and the installation inclination angle is 30-45 degrees; the outer wall of the drying box is provided with an auxiliary electric heating dryer.

The invention also provides a molded body of TPU foamed beads containing the thin graphene permanent antistatic light gray coating, and the surface resistivity of the molded body is 10⁸～10¹⁰Omega, the preparation method is as follows: and adding TPU (thermoplastic polyurethane) foamed beads containing the thin graphene permanent antistatic light gray coating into a mold of a foamed bead forming machine, carrying out steam heating treatment, cooling and demolding to obtain the product.

The TPU foamed bead containing the thin graphene permanent antistatic light gray coating and the preparation method and application thereof are disclosed, the prepared TPU composite foamed bead has uniform and stable antistatic property, and the preparation process is green and environment-friendly.

Drawings

Fig. 1 is a schematic configuration diagram of a spray coating drying apparatus of the present invention.

Detailed Description

The TPU expanded beads containing the thin-layer graphene permanent antistatic light gray coating comprise:

(1) TPU expanded beads; and

the TPU foamed beads are prepared by adopting an extrusion foaming-underwater granulating method or an in-kettle gas impregnation method, and the surfaces of the TPU foamed beads are subjected to ultrasonic wave surface cleaning and degreasing and low-temperature plasma activation treatment;

the aqueous polyurethane solution comprises: the paint comprises waterborne polyurethane, thin-layer graphene waterborne slurry, a waterborne antioxidant, waterborne titanium dioxide slurry, a cross-linking agent and deionized water.

Wherein the aqueous polyurethane solution is carboxyl type thermoplastic aqueous polyurethane emulsion;

the addition amount of the thin-layer graphene in the thin-layer graphene aqueous slurry is 0.25-1.0 wt% of the total amount of the aqueous polyurethane antistatic coating on the surface of the TPU foamed bead;

the water-based antioxidant is a dispersion liquid containing hindered phenol antioxidants; preferably aqueous antioxidant dispersion containing triethylene glycol ether-bis (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate (CAS NO:36443-68-2), wherein the amount of the aqueous antioxidant is 0.5-5% of the solid amount of the aqueous polyurethane solution;

the amount of titanium dioxide in the aqueous titanium dioxide slurry is 2-10% of the solid content of the aqueous polyurethane solution;

the cross-linking agent is an aziridine cross-linking agent, the cross-linking agent is used for improving the water resistance of the aqueous polyurethane coating, but the cross-linking degree needs to be controlled, so that the aqueous polyurethane coating coated on the surface of the TPU foamed beads after drying does not lose the thermal bonding capability, and the addition amount of the cross-linking agent is 0.05-2 percent of the mass percent of the aqueous polyurethane emulsion;

the solid content of the aqueous polyurethane emulsion is 1-20 percent;

the aqueous polyurethane solution also comprises aqueous color paste;

before the TPU foamed bead surface coating is sprayed with the waterborne polyurethane antistatic coating, the specific gravity is 0.1-0.8 g/cm³；

The preparation method of the TPU expanded bead containing the thin graphene permanent antistatic light gray coating comprises the following steps:

4) adding TPU foamed beads into a drum-shaped rotary drum 1 of a spray drying device, starting the rotary drum 1 to rotate and heat, introducing hot air to dry materials, after the TPU foamed beads are preheated to a set drying temperature of 80-105 ℃, starting an auxiliary bead dispersing stirrer 3 arranged in the rotary drum 1, spraying the aqueous polyurethane spray solution containing the thin-layer graphene prepared in the step 3) on the surfaces of the TPU foamed beads by using a spray gun 4 with an atomization effect, so that the surfaces of the TPU foamed beads are continuously heated and dried while being repeatedly and discontinuously sprayed with the aqueous polyurethane spray solution containing the thin-layer graphene in the process of uniformly rolling and dispersing the TPU foamed beads in the rotary drum 1 until the aqueous polyurethane solution is completely consumed, stopping the spray gun 4, finally forming a uniform coating on the surfaces of the TPU beads, and continuously drying until the surface coating of the TPU foamed beads is dried by moisture, and (4) finishing.

Preferably, the ultrasonic cleaning process in the step 1) adopts a water-based cleaning agent containing at least one anionic surfactant or nonionic surfactant with the concentration of 1-20%, and the ultrasonic frequency is>20KHz, power density>0.3W/cm²。

Preferably, the working gas adopted by the low-temperature plasma treatment process in the step 2) is one or a mixture of several of argon, nitrogen, oxygen, ammonia and carbon dioxide, the gas flow is 30-900 sccm, the working pressure is 10-300 Pa, the treatment time is 20 s-10 min, the temperature is 20-130 ℃, and the treatment power is 1500-12000W.

Preferably, as shown in fig. 1, step 4) is implemented by using a spray coating drying device, which comprises:

a rotating drum 1 with an opening at the upper end, wherein the rotating drum 1 is arranged on a base 11;

a hot air pipe 2 with an outlet communicated with the interior of the rotary drum 1 and connected with a hot air blowing device 21 outside the rotary drum 1;

a stirrer 3 installed in the drum 1 to assist in dispersing the TPU expanded beads; and

a spray gun 4 for atomization, the outlet of which is located in the rotating drum 1 and is connected with a liquid tank outside the rotating drum 1 through a pipeline.

Preferably, the installation inclination angle of the rotary drum 1 is 30-45 degrees;

preferably, the drum 1 is a drum-type stainless steel drum;

preferably, an auxiliary electric heating dryer is installed on the outer wall of the rotary drum 1;

the invention also provides a molded body of TPU foamed beads containing the thin graphene permanent antistatic light gray coating, and the preparation method comprises the following steps:

and adding the TPU foamed beads containing the thin graphene permanent antistatic light gray coating into a mold of a foamed bead forming machine, carrying out steam heating treatment, cooling and demolding to obtain a TPU foamed bead forming body containing the thin graphene permanent antistatic light gray coating. Softening the surface of the white TPU foamed beads and the external aqueous polyurethane coating by steam heating, so that molecular chains of interfaces between the white TPU foamed beads and the aqueous polyurethane coating and between the aqueous polyurethane coatings are diffused mutually to form firmer adhesion, enabling the thin graphene in the coatings to be wrapped by the molecular chains and stably distributed on each interface layer, extruding and fixing the antistatic material wrapped on the surface of the TPU foamed beads on the surface of the formed body and the inside of the formed body, and enabling the surface resistivity of the antistatic material to be 10⁸～10¹⁰Ω。

The present invention will be further described with reference to examples 1 to 2.

Example 1

The specific gravity of the product prepared by the in-kettle gas immersion method is 0.12g/cm³The white TPU expanded beads of (1), the average particle diameter of the beads being 3.5 mm.

1) Firstly, grease and dirt on the surface of white TPU foamed beads are removed, rinsed and dried at 50-100 ℃ by utilizing an ultrasonic cleaning process, wherein the cleaning liquid is a water-based cleaning liquid containing 10% of a surfactant 6501, the ultrasonic frequency is 25KHz, and the power density is 0.35W/cm²；

2) Then carrying out low-temperature plasma treatment on the surface of the treated white TPU foamed beads, wherein the working gas is nitrogen, the working gas pressure is 100Pa, and the temperature is 80 ℃;

3) preparing a carboxyl type aqueous polyurethane spray solution containing thin-layer graphene with solid content of 10%, which comprises the following steps:

a. the total addition amount of the thin-layer graphene is 0.25wt% of the total solid amount of the aqueous polyurethane spray liquid;

b. selecting an aqueous antioxidant dispersion liquid containing triethylene glycol ether-bis (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate (CAS NO:36443-68-2), wherein the amount of the aqueous antioxidant is 2% of the solid content of the aqueous polyurethane solution;

c. the amount of the titanium dioxide in the aqueous titanium dioxide slurry is 5 percent of the total solid amount of the aqueous polyurethane solution

d. The cross-linking agent adopts aziridine cross-linking agent SAC-100, and the addition amount of the aziridine cross-linking agent is 0.2 percent of the mass percentage of the aqueous polyurethane emulsion;

4) adding the white TPU expanded beads treated in the step 2) into a spray coating and drying device (shown in the attached figure 1), setting the hot air temperature to be 100 ℃, setting the solid content of the aqueous polyurethane spray solution containing the thin graphene prepared in the step 3) to be 30% of the content of the white TPU expanded beads, and obtaining the TPU composite expanded beads containing the thin graphene permanent antistatic coating with the specific gravity of about 0.16g/cm³；

5) And (3) putting the prepared TPU composite foamed beads containing the thin graphene permanent antistatic coating into a mold, heating by adopting steam, cooling, and demolding to obtain a TPU composite foamed bead forming body containing the thin graphene permanent antistatic coating.

Tests show that the coating of the TPU foamed bead forming body containing the thin graphene permanent antistatic coatingEven, passes a water resistance test of 60 ℃, relative humidity of 95 percent and seven days, does not fade after being wiped by external force, and has surface resistivity of 8 x 10¹⁰Ω。

Example 2

The specific gravity of the product prepared by the in-kettle gas immersion method is 0.12g/cm³The average particle diameter of the white TPU expanded beads of (1) is 3.5 mm.

a. the total addition amount of the thin-layer graphene is 0.75 wt% of the total solid amount of the aqueous polyurethane spray liquid;

4) adding the white TPU expanded beads treated in the step 2) into a spray coating and drying device (shown in the attached figure 1), setting the hot air temperature to be 100 ℃, setting the solid content of the aqueous polyurethane spray solution of the thin graphene prepared in the step 3) to be 20% of the amount of the white TPU expanded beads, and obtaining the TPU composite expanded beads containing the thin graphene permanent antistatic coating with the specific gravity of about 0.17g/cm³；

Tests prove that the TPU foamed bead forming body containing the thin graphene permanent antistatic coating has uniform coating, passes a water resistance test of 60 ℃, the relative humidity is 95 percent, the TPU foamed bead forming body can not fade after being wiped by external force after passing a seven-day water resistance test, and the surface resistivity is 7 x 10⁹Ω。

The above embodiments are provided only for illustrating the present invention and not for limiting the present invention, and those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and therefore all equivalent technical solutions should also fall within the scope of the present invention, and should be defined by the claims.

Claims

1. A preparation method of TPU expanded beads containing a thin graphene permanent antistatic light gray coating is characterized in that the TPU expanded beads containing the thin graphene permanent antistatic light gray coating comprise:

(1) TPU expanded beads; and

(2) spraying an aqueous polyurethane solution containing thin-layer graphene on the surface of the TPU foamed beads to form an aqueous polyurethane antistatic coating with the thickness of 10-200 mu m;

cleaning and degreasing the surface of the TPU foamed bead by ultrasonic waves and activating the surface by low-temperature plasma;

the aqueous polyurethane solution consists of aqueous polyurethane, thin-layer graphene aqueous slurry, an aqueous antioxidant, aqueous titanium dioxide slurry, a cross-linking agent and deionized water;

the aqueous polyurethane solution is carboxyl type thermoplastic aqueous polyurethane emulsion;

the aqueous antioxidant is a dispersion liquid containing hindered phenol antioxidants;

the cross-linking agent is an aziridine type cross-linking agent, and the addition amount of the cross-linking agent is 0.2 percent of the mass percent of the aqueous polyurethane emulsion;

the preparation method of the TPU expanded bead containing the thin graphene permanent antistatic light gray coating adopts a spray coating and drying device, and at least comprises the following steps:

a drum-shaped rotating drum with an open upper end;

the spray gun is used for atomization, and an outlet of the spray gun is positioned in the rotary drum and is connected with a liquid tank outside the rotary drum through a pipeline;

4) adding the TPU expanded beads into a rotary drum of the spray coating drying device, starting the rotary drum to rotate and heat, introducing hot air to dry materials, starting a stirrer to assist in dispersing the TPU expanded beads after the TPU expanded beads are preheated to a set drying temperature of 80-105 ℃, spraying the aqueous polyurethane spray solution containing the thin-layer graphene prepared in the step 3) on the surfaces of the TPU expanded beads by using a spray gun, continuously heating and drying the surfaces of the TPU expanded beads while intermittently spraying the aqueous polyurethane spray solution containing the thin-layer graphene for multiple times in the process of uniformly rolling and dispersing the TPU expanded beads until the aqueous polyurethane solution is completely consumed, stopping spraying, finally forming a uniform coating on the surfaces of the TPU expanded beads, and continuously drying until the surface coating of the TPU expanded beads is dried by moisture.

2. The method of claim 1, wherein the aqueous antioxidant is an aqueous antioxidant dispersion comprising triethylene glycol ether-bis (3-t-butyl-4-hydroxy-5-methylphenyl) propionate.

3. The method for preparing the TPU expanded beads containing the thin-layer graphene permanent antistatic light gray coating according to claim 1, wherein the addition amount of the thin-layer graphene in the thin-layer graphene aqueous slurry is 0.25 to 1.0 weight percent of the total amount of the aqueous polyurethane antistatic coating on the surface of the TPU expanded beads;

the amount of the water-based antioxidant is 0.5 to 5 percent of the solid amount of the water-based polyurethane solution;

the solid content of the aqueous polyurethane emulsion containing the thin-layer graphene is 1-20%.

4. The method for preparing the TPU foamed beads containing the thin graphene permanent antistatic light gray coating according to claim 1, wherein the specific gravity of the TPU foamed bead surface coating before spraying the aqueous polyurethane antistatic coating is 0.1-0.8 g/cm³。

5. The method for preparing the TPU expanded beads containing the thin-layer graphene permanent antistatic light gray coating according to claim 1, wherein the ultrasonic cleaning process in the step 1) adopts a water-based cleaning agent containing at least one anionic surfactant or nonionic surfactant with the concentration of 1-20%, and the ultrasonic frequency is controlled>20KHz, power density>0.3W/cm²。

6. The preparation method of the TPU expanded bead containing the thin-layer graphene permanent antistatic light gray coating, as claimed in claim 1, is characterized in that the working gas adopted in the low-temperature plasma treatment process in step 2) is one or a mixture of several gases of argon, nitrogen, oxygen, ammonia and carbon dioxide, the gas flow is 30-900 sccm, the working gas pressure is 10-300 Pa, the treatment time is 20 s-10 min, the temperature is 20-130 ℃, and the treatment power is 1500W-12000W.

7. The method for preparing the TPU expanded beads containing the thin-layer graphene permanent antistatic light gray coating according to claim 1, wherein the rotary drum is installed on a base, and the installation inclination angle of the rotary drum is 30-45 degrees; the outer wall of the drying box is provided with an auxiliary electric heating dryer.