CN111019502A

CN111019502A - Preparation method of polyurethane coating, product and application thereof

Info

Publication number: CN111019502A
Application number: CN201911242233.1A
Authority: CN
Inventors: 张军瑞; 徐梦丹; 何振威; 谢君; 史达
Original assignee: Zhijiang College of ZJUT
Current assignee: Zhijiang College of ZJUT
Priority date: 2019-12-06
Filing date: 2019-12-06
Publication date: 2020-04-17
Anticipated expiration: 2039-12-06
Also published as: CN111019502B

Abstract

The invention discloses a preparation method of a polyurethane coating, a product and application thereof, wherein the coating comprises the following components of waterborne polyurethane monomer, glass powder, nano silicon dioxide, aluminum compound and cross-linking agent; the preparation method comprises the following steps: adding nano silicon dioxide into deionized water, adding an aluminum compound under the stirring condition, adding an aqueous polyurethane monomer after uniformly mixing, carrying out closed reaction in a high-pressure closed reaction vessel under inert atmosphere, adding glass powder, and cooling to room temperature to obtain an aqueous polyurethane coating; adding the cross-linking agent into the waterborne polyurethane coating, uniformly mixing, spraying the mixture on the surface of a product to be processed, and drying and curing the mixture to obtain the polyurethane coating. The coating has important development and application values.

Description

Preparation method of polyurethane coating, product and application thereof

Technical Field

The invention relates to the technical field of coatings, in particular to a preparation method of a polyurethane coating, a product and application thereof.

Background

Polyurethane (PU) is a polymer with urethane chain segment repeating structural units made by reacting isocyanate with polyol, can obtain various excellent properties by adjusting its chemical composition, and is widely used in the fields of automobile industry, aerospace, construction, medical equipment, and the like. However, the conventional polyurethane resin material is optically opaque, so that its application range is greatly limited.

The transparency of the polyurethane is restricted by the structure, the polyol used for preparing the polyurethane comprises two categories of polyester and polyether, because polyester polyol molecules contain ester groups (-COO-), the ester groups have high polarity, are easy to crystallize, influence the transparency of the PU, and the interaction force among polyether molecular chains is weaker than that of the polyester, is easy to randomly arrange, has low crystallinity and good relative transparency, but the mechanical property and the weather resistance of the polyether polyurethane are poorer, so the polyether polyurethane is not suitable for fields with special requirements on the mechanical property and the weather resistance. Therefore, it is highly desirable to develop a polyester polyurethane coating having good optical transparency.

The key point of the development of the polyester type transparent polyurethane coating is that on the basis of ensuring that the basic mechanical property can meet the use requirement, the hard section and the soft section of the polyurethane are not crystallized or the crystallization is controlled to the maximum extent as far as possible, and according to the theory of the structure of a high polymer, for the polyester type polyurethane, the transparent polymer is possible only by breaking the internal crystalline structure of the polyester type polyurethane and enabling the polyester type polyurethane to become a random amorphous polymer. Therefore, in the prior art, modification substances are added into raw materials in the preparation process of the polyurethane coating to modify the polyurethane coating so as to prevent hard segment and soft segment of polyurethane from crystallizing or control crystallization to the maximum extent, thereby improving the transparency of the polyurethane coating.

Disclosure of Invention

In order to solve the technical problems, the invention provides a preparation method, a product and application of a polyurethane coating.

The invention provides a preparation method of a polyurethane coating, which comprises the following raw materials, by mass, 55-65 parts of a water-based polyurethane monomer, 10-15 parts of glass powder, 15-25 parts of nano silicon dioxide, 1-3 parts of an aluminum compound and 3-5 parts of a cross-linking agent;

the preparation method comprises the following steps:

(1) adding nano silicon dioxide into deionized water, adding an aluminum compound under the stirring condition, adding an aqueous polyurethane monomer after uniformly mixing, carrying out closed reaction in a high-pressure closed reaction vessel for 1-2h under an inert atmosphere, adding glass powder, keeping the temperature at 70-80 ℃, stirring for 2-4h, and cooling to room temperature to obtain an aqueous polyurethane coating;

(2) adding the cross-linking agent into the waterborne polyurethane coating, uniformly mixing, spraying the mixture on the surface of a product to be processed, and drying and curing the mixture to obtain the polyurethane coating.

Preferably, the glass powder is 8000-mesh low borosilicate glass powder.

Preferably, the particle size of the nano silicon dioxide is 3-15 nm.

Preferably, the aluminum compound is one or more of aluminum sulfate, aluminum chloride, aluminum nitrate and aluminum oxide.

Preferably, the addition amount of the deionized water in the step (1) is 3-5 times of that of the waterborne polyurethane monomer.

Preferably, the high-pressure sealed reaction condition in the step (1) is 30-50MPa, the temperature is 150-.

Preferably, the crosslinking agent in the step (2) is an organosilicon crosslinking agent.

Preferably, the surface drying time in the step (2) is 10-20min, and the curing condition is normal temperature curing for 7 days or 100-120 ℃ baking for 10-15 h.

The invention also provides the polyurethane coating prepared by the preparation method of the polyurethane coating.

The invention also provides application of the polyurethane coating in the aspects of automobile coatings, airplane coatings and optical glass.

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

the invention selects the existing water polyurethane monomer to carry out the nanometer silicon dioxide modification, adds the polyurethane monomer into the nanometer silicon dioxide water solution containing the metal aluminum compound before the construction, and combines a certain temperature to carry out the stirring reaction, on one hand, the aluminum compound strengthens the bonding force between the nanometer silicon dioxide through the electrostatic force, improves the stability of the nanometer silicon dioxide in the water, is not easy to agglomerate, more importantly, under the high-pressure closed reaction condition of the aluminum compound, the nanometer silicon dioxide and the polyurethane material are well cross-linked and mixed, thereby the nanometer silicon dioxide/polyurethane blend is generated by polymerization, pi-pi bond is constructed on the interface of the nanometer silicon dioxide/polyurethane, simultaneously, the hard ester functional group on the polyurethane monomer and the hydroxyl group, the oxygen-containing functional group and the like on the nanometer silicon dioxide react to connect the hard ester functional group and the oxygen-containing functional group on the polyurethane monomer, thereby enhancing the toughness and ductility of the polyurethane coating, simultaneously avoiding the crystallization of polyurethane ester group and improving the transparency of the polyurethane material due to the addition of the nano silicon dioxide in the polyurethane ester functional group. The doping of the aluminum compound also promotes to some extent the improvement of the transparency of the polyurethane coating. This application has added a quantitative glass powder simultaneously, adopts superfine glass miropowder, and its refracting index is the closest polyurethane coating in the inorganic matter, can not cause the luminousness decline of coating, the mechanical properties of improvement coating that can great degree simultaneously.

Detailed Description

Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The specification and examples are exemplary only.

As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.

The waterborne polyurethane monomer selected in the following examples is selected from AH-1705 polyurethane produced by New Material Ltd of DAHUATAI, Anhui.

Example 1

Taking 55 parts of raw material waterborne polyurethane monomer, 10 parts of glass powder, 15 parts of nano silicon dioxide, 2 parts of aluminum oxide and 4 parts of organic silicon cross-linking agent;

(1) adding nano silicon dioxide into deionized water 4 times of the amount of the waterborne polyurethane monomer, adding aluminum oxide under stirring, adding the waterborne polyurethane monomer after uniformly mixing, setting the reaction temperature to be 200 ℃ and the pressure to be 30MPa in a high-pressure closed reaction container under the atmosphere of helium, carrying out closed reaction for 1h, adding glass powder, keeping the temperature to be 80 ℃, stirring for 2h, and cooling to room temperature to obtain the waterborne polyurethane coating;

(2) adding the organosilicon crosslinking agent into the waterborne polyurethane coating, uniformly mixing, spraying the mixture on the surface of a product to be processed for 20min, and curing at normal temperature for 7 days to obtain a polyurethane coating, wherein the spraying thickness is 80 microns.

Example 2

60 parts of raw material waterborne polyurethane monomer, 12 parts of glass powder, 20 parts of nano silicon dioxide, 3 parts of aluminum sulfate and 5 parts of organic silicon cross-linking agent.

(1) Adding nano silicon dioxide into deionized water which is 5 times of that of an aqueous polyurethane monomer, adding aluminum oxide under the stirring condition, adding the aqueous polyurethane monomer after uniformly mixing, setting the reaction temperature to be 250 ℃ and the pressure to be 35MPa in a high-pressure closed reaction container under the atmosphere of helium, carrying out closed reaction for 1h, adding glass powder, keeping the temperature to be 70 ℃, stirring for 2h, and cooling to room temperature to obtain an aqueous polyurethane coating;

(2) adding the organosilicon crosslinking agent into the waterborne polyurethane coating, uniformly mixing, spraying the mixture on the surface of a product to be processed, drying for 20min, and baking for 12h at 120 ℃ to obtain a polyurethane coating, wherein the spraying thickness is 80 microns.

Example 3

The difference from example 2 is that no aluminium sulphate is added.

Example 4

The difference from example 2 is that the reaction conditions after the aqueous polyurethane monomer is added in step (1) are heating at 70 ℃ and reacting at normal pressure.

Example 5

The difference from example 2 is that no glass frit was added.

Application example

The polyurethane coatings prepared in examples 1-5 were performance tested:

the coating hardness test adopts the national standard GB-T26704 and 2011 test;

the impact resistance test adopts the national standard GB/T1732-93 to test;

the light transmittance is detected by a WGW photoelectric haze meter;

the flexibility test adopts the test of national standard GB/T1731-;

the results are shown in Table 1;

TABLE 1

As can be seen from Table 1, the polyurethane coating modified by the nano-silica under the high-pressure closed condition of the invention has excellent coating performance and obviously improved light transmittance.

Claims

1. The preparation method of the polyurethane coating is characterized in that the raw materials comprise, by mass, 55-65 parts of a water-based polyurethane monomer, 10-15 parts of glass powder, 15-25 parts of nano silicon dioxide, 1-3 parts of an aluminum compound and 3-5 parts of a cross-linking agent;

the preparation method comprises the following steps:

2. The method of claim 1, wherein the glass frit is 8000 mesh low borosilicate glass frit.

3. The method of claim 1, wherein the nano silica has a particle size of 3 to 15 nm.

4. The method of claim 1, wherein the aluminum compound is one or more of aluminum sulfate, aluminum chloride, aluminum nitrate, and aluminum oxide.

5. The method for preparing a polyurethane coating according to claim 1, wherein the amount of the deionized water added in step (1) is 3-5 times of the amount of the aqueous polyurethane monomer.

6. The method as claimed in claim 1, wherein the high pressure sealing reaction conditions in step (1) are 30-50MPa, temperature 150-.

7. The method of claim 1, wherein the crosslinking agent in step (2) is an organosilicon crosslinking agent.

8. The method for preparing a polyurethane coating as claimed in claim 1, wherein the surface drying time in step (2) is 10-20min, and the curing condition is normal temperature curing for 7 days or 100-120 ℃ baking for 10-15 h.

9. A polyurethane coating prepared by the method of any one of claims 1 to 8.

10. Use of the polyurethane coating according to claim 9 for automotive coatings, aircraft coatings, optical glass.