CN113416478B - PU varnish, preparation method and application thereof - Google Patents

Abstract

The invention provides a PU varnish and a preparation method and application thereof, wherein the PU varnish comprises a component A and a component B; the component A comprises: 10-60 parts of thermoplastic acrylic resin, 1-10 parts of CAB resin and 5-15 parts of wax-containing additive; the component B comprises 5-20 parts of a curing agent containing isocyanate groups; the wax-containing additive is a composition of wax powder and wax slurry. The preparation method comprises the following steps: (1) mixing thermoplastic acrylic resin, CAB resin and optionally a defoaming agent to obtain a mixture A; (2) mixing the mixture A, the wax-containing additive and the optional anti-settling agent to obtain a mixture B; (3) mixing the mixture B, an optional leveling agent and an optional organic solvent to obtain a component A; (4) and mixing the component A and the component B to obtain the PU varnish. The varnish provided by the invention has an extra-matte effect, is uniform in gloss and resistant to yellowing, and can be used for furniture protection materials.

Description

PU varnish, preparation method and application thereof

Technical Field

The invention belongs to the technical field of coatings, and particularly relates to a PU varnish, and a preparation method and application thereof.

Background

With the improvement of living standard of people, people have higher and higher living requirements. Furniture is a pen for lighting in rooms, and after the storage time is over, the surface of the furniture can be aged and discolored, so that the surface of the furniture needs to be coated with a coating in order to maintain the attractiveness and durability of the furniture. The color, transparency and gloss of the coating directly affect the aesthetics of the furniture. Sometimes, in order to pursue the original aesthetic feeling of furniture, people need to adopt a matte coating to protect the surface of the furniture, so as to realize the effect that the coating is invisible visually.

Much research is currently done on matte coatings, for example CN104327719A discloses a recoated ultra clear polyurethane matte varnish. The recoated ultra-clear polyurethane matte varnish is prepared from alkyd resin, a dispersing agent, an anti-settling agent, wax powder, flatting powder, glass powder, CAB liquid, a solvent, a defoaming agent, a drier and a flatting agent. The varnish is not easy to whiten when used on a substrate, and has high definition. CN102020905A discloses a single-component water-based matte varnish, which comprises, by mass, 30-60% of a water-based acrylic emulsion, 5-30% of a water-based aliphatic polyurethane emulsion, 3-10% of a film-forming assistant, 0.01-2% of a defoaming agent, 0.01-2% of a dispersing agent, 0.1-5% of a matting agent, 0.01-2% of a wax assistant, 0.01-2% of a hand feeling assistant, 0.01-2% of a thickening agent, 0.01-2% of a crosslinking agent and 5-40% of water. The single-component matte varnish disclosed by the invention has the advantages of super-strong hand feeling, high fullness, high hardness, good chemical resistance, low harm to the bodies of production and construction personnel and low environmental pollution. CN104610824A discloses a water-based curtain coating special matte toning finish paint which comprises the following components in percentage by weight: 35-45% of water-based acrylic resin, 16-20% of water-based polyurethane modified acrylic resin, 0.1-0.2% of defoaming agent, 3-5% of flatting agent, 5-7% of film-forming assistant, 0.5-1% of wetting agent, 0.5-1% of dispersing agent, 0.5-1% of thickening agent and the balance of water. The water-based curtain coating matte clear finish paint has the advantages of high hardness, good fullness, good weather resistance, good flexibility, good hand feeling, high gloss, water resistance and good chemical resistance, and has good adhesive force on solvent type polyurethane wood Paint (PU), nitrocellulose paint (NC), unsaturated polyester Paint (PE) and oily UV photocuring paint. At present, all the matte coatings are delustred by adopting matting powder, and the problems of uneven luster, blooming and easy yellowing of paint films always exist.

Therefore, the research on the varnish with the special matte effect, uniform gloss and yellowing resistance has important practical application significance.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a PU varnish and a preparation method and application thereof, and the coating prepared from the PU varnish has the advantages of special matt effect, uniform gloss, smooth hand feeling and yellowing resistance through the synergistic effect of wax powder, wax slurry, thermoplastic acrylic resin and CAB resin in the varnish components.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a PU varnish, the PU varnish comprising an a component and a B component; the component A comprises the following components in parts by weight: 10-60 parts of thermoplastic acrylic resin, 1-10 parts of CAB resin and 5-15 parts of wax-containing additive; the component B comprises 5-20 parts by weight of an isocyanate-containing curing agent; the wax-containing additive is a composition of wax powder and wax slurry.

The PU varnish, namely the polyurethane varnish, provided by the invention has the advantages that the thermoplastic acrylic resin in the components can perform chemical crosslinking reaction with the curing agent to form a hard paint film, and meanwhile, the PU varnish has excellent yellowing resistance and good extinction performance; CAB resin, namely cellulose acetate butyrate resin, has the advantages of promoting the solvent to volatilize quickly, enhancing the cracking resistance of the coating, having good compatibility with acrylic resin, and still having good mechanical property when the thickness of the coating is thinner; the wax powder and the wax slurry replace the traditional flatting agent, can well solve the problem of uneven gloss of the PU special matt varnish coating, and simultaneously has excellent flatting performance, so that the prepared coating has smooth touch. According to the invention, the wax powder, the wax slurry, the thermoplastic acrylic resin and the CAB resin are compounded in specific contents to perform a synergistic effect, so that the prepared varnish coating has an extra-matte effect, uniform gloss, smooth touch and excellent yellowing resistance.

The thermoplastic acrylic resin is 10-60 parts, for example, 12 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts or 55 parts, and the specific values therebetween are not exhaustive for the purpose of brevity and clarity.

The CAB resin is 1-10 parts, such as 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, or 9 parts, and the specific values therebetween are limited by space and for brevity, and the invention is not intended to be exhaustive of the specific values included in the ranges set forth.

The wax-containing additive is 5-15 parts, such as 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts or 14 parts, and the specific values therebetween are limited by space and for brevity, and the invention is not intended to be exhaustive of the specific values included in the ranges.

The isocyanate-containing curing agent is present in an amount of 5 to 20 parts, for example 6, 8, 10, 12, 14, 16 or 18 parts, and the particular values therebetween are not exhaustive for the invention and are not intended to limit the scope of the invention to the specific values contained therein for brevity and clarity.

In the present invention, the viscosity of the thermoplastic acrylic resin is 4000 to 30000cps, for example, 5000cps, 6000cps, 8000cps, 10000cps, 15000cps, 20000cps, 25000cps, 26000cps, 27000cps, 28000cps or 29000cps, and specific point values therebetween are not limited by space and for the sake of brevity, and the present invention is not exhaustive.

In the present invention, the viscosity of the CAB resin is 0.1-2 s, for example, 0.12s, 0.14s, 0.15s, 0.16s, 0.17s, 0.18s, or 0.19s, and the specific values therebetween are limited by space and for brevity, and the present invention is not exhaustive list of the specific values included in the range.

Preferably, the mass ratio of the wax powder to the wax slurry is 1 (2-6), and may be, for example, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, or 1: 5.5.

Preferably, the wax powder is selected from a polyolefin wax powder and/or an amide wax powder.

Preferably, the particle size of the wax powder is 5-40 μm, for example, 6 μm, 8 μm, 10 μm, 15 μm, 20 μm, 22 μm, 25 μm, 30 μm, 32 μm, 35 μm, 38 μm or 39 μm, and the specific values therebetween are limited by space and for the sake of brevity, and the invention is not exhaustive.

When the particle size of the wax powder is too large, the surface of the final varnish coating is rough and uneven in gloss; if the particle size of the wax powder is too small, the matting effect of the final varnish coating becomes poor and does not reach an extra matte grade.

Preferably, the wax slurry is a modified polyolefin wax slurry.

Preferably, the wax slurry has a solids content of 40-60%, for example, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 55%, 56%, 58% or 59%, and specific values therebetween, for reasons of space and brevity, the present invention is not intended to be exhaustive of the specific values included in the ranges.

In the present invention, the isocyanate-containing curing agent is selected from an N3390 curing agent or an N75 curing agent.

In the invention, the component A of the PU varnish also comprises any one or the combination of at least two of a defoaming agent, an anti-settling agent, a plasticizer, a leveling agent or an organic solvent.

Preferably, the defoamer is a silicone defoamer.

Preferably, the content of the silicone defoamer in the a component of the PU varnish is 0.1 to 0.5 parts by weight, for example, 0.12 part, 0.15 part, 0.2 part, 0.22 part, 0.25 part, 0.3 part, 0.35 part, 0.4 part or 0.45 part, and specific values therebetween are not limited to the space and for the sake of brevity, and the invention is not exhaustive.

Preferably, the content of the anti-settling agent in the component a of the PU varnish is 1-2 parts by weight, for example, 1.1 part, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts or 1.9 parts, and specific values therebetween, which is not exhaustive for brevity and conciseness.

Preferably, the content of the plasticizer in the component a of the PU varnish is 1 to 3 parts by weight, for example, 1.1 part, 1.2 parts, 1.5 parts, 2 parts, 2.2 parts, 2.5 parts, 2.6 parts, 2.8 parts or 2.9 parts, and specific values therebetween, which are limited by space and for the sake of brevity, the present invention is not exhaustive list of specific values included in the range.

Preferably, the leveling agent is an organosilicon leveling agent.

Preferably, the content of the silicone leveling agent in the component a of the PU varnish is 0.1 to 0.5 parts by weight, for example, 0.12 part, 0.15 part, 0.2 part, 0.22 part, 0.25 part, 0.3 part, 0.35 part, 0.4 part or 0.45 part, and specific values therebetween are limited by space and for the sake of brevity, and the invention is not exhaustive of the specific values included in the range.

Preferably, the organic solvent is a mixture of an ester solvent and xylene.

Preferably, the content of the ester solvent in the component A of the PU varnish is 20-50 parts by weight, such as 22 parts, 25 parts, 30 parts, 32 parts, 35 parts, 40 parts, 45 parts, 48 parts or 49 parts, and the specific values therebetween are limited by space and for the sake of brevity, and the invention is not exhaustive.

Preferably, the content of xylene in the a component of the PU varnish is 10 to 20 parts by weight, for example, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts or 19 parts, and specific values therebetween are not exhaustive, but for brevity and clarity.

In a second aspect, the present invention provides a method for producing the PU varnish described in the first aspect, the method comprising the steps of:

(1) mixing thermoplastic acrylic resin, CAB resin and optionally a defoaming agent to obtain a mixture A;

(2) mixing the mixture A obtained in the step (1), a wax-containing additive and an optional anti-settling agent to obtain a mixture B;

(3) mixing the mixture B obtained in the step (2), optionally a leveling agent and optionally an organic solvent to obtain the PU varnish.

In the invention, the mixing method of the step (1), the step (2) and the step (3) is mechanical stirring.

Preferably, the rotation speed of the mechanical stirring in the step (1) is more than 800r/min, such as 900r/min, 1000r/min, 1100r/min or 1200 r/min.

Preferably, the rotation speed of the mechanical stirring in the step (2) and the step (3) is 600-800 r/min, such as 620r/min, 650r/min, 700r/min, 720r/min, 780r/min or 790r/min, and the specific values therebetween are not exhaustive for the sake of brevity and simplicity.

The temperature of the system can be increased under the condition of high rotating speed, so that the melting point of the wax powder is easily reached, the wax powder is easy to gather after being melted, the particle size of the wax powder is increased, the surface of the varnish coating is rough, and the use requirement cannot be met.

Preferably, the temperature of the mechanical stirring in the step (2) and the step (3) is 25 to 50 ℃ independently, for example, 26 ℃, 28 ℃, 30 ℃, 32 ℃, 35 ℃, 38 ℃, 40 ℃, 42 ℃, 45 ℃, 48 ℃ or 49 ℃, and the specific values therebetween are limited by space and for the sake of brevity, and the invention is not exhaustive.

When the temperature of the system is higher than 50 ℃, the wax powder is easy to melt and then gathers, so that the particle size of the wax powder is increased, the surface of the varnish coating is rough, and the use requirement cannot be met.

Preferably, the mechanical stirring time in step (1), step (2) and step (3) is independently 5-25 min, such as 6min, 8min, 10min, 12min, 15min, 20min, 21min, 22min, 23min or 24min, and the specific values therebetween are limited by space and for the sake of brevity, and the invention is not exhaustive.

As a preferred technical scheme of the invention, the preparation method specifically comprises the following steps:

(1) mechanically stirring thermoplastic acrylic resin, CAB resin and an optional defoaming agent for 5-25 min under the condition that the rotating speed is more than 800r/min to obtain a mixture A;

(2) mechanically stirring the mixture A obtained in the step (1), a wax-containing additive and an optional anti-settling agent for 5-25 min at a rotating speed of 600-800 r/min to obtain a mixture B;

(3) mechanically stirring the mixture B obtained in the step (2), optionally leveling agent and optionally solvent for 5-25 min under the condition that the rotating speed is 600-800 r/min to obtain a component A of the PU varnish;

(4) and (4) mixing the component A of the PU varnish obtained in the step (3) with the component B of the PU varnish to obtain the PU varnish.

In a third aspect, the present invention provides a use of the PU varnish according to the first aspect in furniture protection materials.

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

according to the invention, through the synergistic effect generated by compounding the thermoplastic acrylic resin, the CAB resin, the wax powder and the wax slurry according to specific contents, the prepared varnish coating has a special matt effect, the gloss is below 5% (60 DEG), the gloss is uniform, the touch is smooth, the varnish is resistant to yellowing, and the total color difference delta E is less than 1.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

The following examples and comparative examples of the present invention use materials including:

(1) thermoplastic acrylic resin: changxing chemical Co., Ltd, ETERAC;

(2) CAB resin: eastman, CAB-381-0.5;

(3) PE wax powder: lumbolug modified synthetic wax, Lanco ^TM 1400SF；

(4) Anti-settling agent: polyethylene anti-settling wax syrup, Elementis DeuRheo 202P;

(5) and (3) organic silicon defoaming agent: BYK 141;

(6) modified synthetic wax slurry: lumbolug modified synthetic wax, Lanco ^TM 450C；

(7) Organic silicon flatting agent: BYK 323;

(8) plasticizer: the amount of the acid to be used in the process of the Pasteur reaction,

example 1

The embodiment provides a PU varnish and a preparation method thereof, wherein the PU varnish comprises a component A and a component B; the component A comprises the following components in parts by weight: 35 parts of thermoplastic acrylic resin, 5.5 parts of CAB resin, 10 parts of wax-containing additive, 0.3 part of organic silicon defoamer, 1.5 parts of anti-settling agent, 2 parts of plasticizer, 0.3 part of organic silicon flatting agent, 15 parts of xylene and 35 parts of butyl acetate; the component B comprises N339015 parts by weight; the mass ratio of the PE wax powder to the modified synthetic wax slurry in the wax-containing additive is 1:4, and the solid content of the wax slurry is 50%.

The preparation method of the PU varnish comprises the following steps;

(1) mechanically stirring thermoplastic acrylic resin, CAB resin and an organic silicon defoaming agent for 15min under the condition of the rotating speed of 1000r/min to obtain a mixture A;

(2) mechanically stirring the mixture A obtained in the step (1), the wax-containing additive and the anti-settling agent for 15min under the condition that the rotating speed is 700r/min to obtain a mixture B;

(3) mechanically stirring the mixture B obtained in the step (2), an organic silicon leveling agent, xylene and butyl acetate for 15min under the condition that the rotating speed is 700r/min to obtain a component A of the PU varnish;

(4) and (4) mixing the component A of the PU varnish obtained in the step (3) with the component B of the PU varnish to obtain the PU varnish.

Example 2

The embodiment provides a PU varnish and a preparation method thereof, wherein the PU varnish comprises a component A and a component B; the component A comprises the following components in parts by weight: the PU varnish comprises the following components in parts by weight: 10 parts of thermoplastic acrylic resin, 1 part of CAB resin, 5 parts of wax-containing additive, 0.1 part of organic silicon defoamer, 1 part of anti-settling agent, 1 part of plasticizer, 0.1 part of organic silicon flatting agent, 10 parts of xylene and 20 parts of butyl acetate; the component B comprises N33905 parts by weight; the mass ratio of the PE wax powder to the modified synthetic wax slurry in the wax-containing additive is 1:4, and the solid content of the wax slurry is 50%.

The preparation method of the PU varnish comprises the following steps;

(1) mechanically stirring thermoplastic acrylic resin, CAB resin and an organic silicon defoaming agent for 5min under the condition of the rotating speed of 1200r/min to obtain a mixture A;

(2) mechanically stirring the mixture A obtained in the step (1), the wax-containing additive and the anti-settling agent for 5min under the condition that the rotating speed is 600r/min to obtain a mixture B;

(3) and (3) mechanically stirring the mixture B obtained in the step (2), the organic silicon flatting agent, the xylene and the butyl acetate for 5min under the condition that the rotating speed is 600r/min to obtain the PU varnish.

Example 3

The embodiment provides a PU varnish and a preparation method thereof, wherein the PU varnish comprises the following components in parts by weight: 60 parts of thermoplastic acrylic resin, 10 parts of CAB resin, 15 parts of wax-containing additive, 0.5 part of organic silicon defoamer, 2 parts of anti-settling agent, 3 parts of plasticizer, 0.5 part of organic silicon flatting agent, 20 parts of xylene and 50 parts of butyl acetate; the component B comprises N339020 parts by weight; the mass ratio of the PE wax powder to the modified synthetic wax slurry in the wax-containing additive is 1:4, and the solid content of the wax slurry is 50%.

The preparation method of the PU varnish comprises the following steps;

(1) mechanically stirring thermoplastic acrylic resin, CAB resin and an organic silicon defoaming agent for 25min under the condition of the rotating speed of 1000r/min to obtain a mixture A;

(2) mechanically stirring the mixture A obtained in the step (1), polyethylene wax powder and the anti-settling agent for 25min under the condition that the rotating speed is 800r/min to obtain a mixture B;

(3) and (3) mechanically stirring the mixture B obtained in the step (2), the organic silicon flatting agent, the xylene and the butyl acetate for 25min under the condition that the rotating speed is 800r/min to obtain the PU varnish.

Example 4

The embodiment provides a PU varnish and a preparation method thereof, wherein the PU varnish comprises the following components in parts by weight: 35 parts of thermoplastic acrylic resin, 5.5 parts of CAB resin and 10 parts of wax-containing additive; the component B comprises N339015 parts by weight; the mass ratio of the PE wax powder to the modified synthetic wax slurry in the wax-containing additive is 1:4, and the solid content of the wax slurry is 50%.

The preparation method of the PU varnish comprises the following steps;

(1) mechanically stirring thermoplastic acrylic resin and CAB resin for 15min at the rotating speed of 1000r/min to obtain a mixture A;

(2) and (2) mechanically stirring the mixture A obtained in the step (1) and the wax-containing additive for 15min under the condition that the rotating speed is 700r/min to obtain the PU varnish.

Example 5

This example provides a PU varnish and a method for preparing the same, which differs from example 1 only in that the mass ratio of PE wax powder to modified synthetic wax slurry in the wax-containing additive is 1: 1; the preparation method is the same as that of example 1.

Example 6

This example provides a PU varnish and a method for preparing the same, which differs from example 1 only in that the mass ratio of PE wax powder to modified synthetic wax slurry in the wax-containing additive is 1: 10; the preparation method is the same as that of example 1.

Comparative example 1

This comparative example provides a varnish and a method for preparing the same, differing from example 1 only in that polyvinylidene fluoride resin was used instead of thermoplastic acrylic resin, in the same amount. Other raw materials, amounts and preparation methods were the same as those of example 1.

Comparative example 2

This comparative example provides a varnish and a preparation method thereof, differing from example 1 only in that the CAB resin was 0.5 parts by weight; other raw materials, amounts and preparation methods were the same as those of example 1.

Comparative example 3

This comparative example provides a varnish and a preparation method thereof, differing from example 1 only in that the CAB resin was 40 parts by weight; other raw materials, amounts and preparation methods were the same as those of example 1.

Comparative example 4

This comparative example provides a varnish and a process for its preparation, differing from example 1 only in that the wax-containing additive is present in 2 parts by weight; other raw materials, amounts and preparation methods were the same as those of example 1.

Comparative example 5

This comparative example provides a varnish and a process for its preparation, differing from example 1 only in that the wax-containing additive is present in an amount of 60 parts by weight; other raw materials, amounts and preparation methods were the same as those of example 1.

Comparative example 6

This comparative example provides a commercially available PU matte clear topcoat (Dabao, CR-60 ZA).

And (3) performance testing:

preparation of a test sample: the varnishes provided in examples 1 to 6 and comparative examples 1 to 6 were sprayed on a substrate and cured at 40 ℃ for 8 hours to obtain varnish coatings for performance tests;

and (3) testing the glossiness: the gloss of the clear coat provided in examples 1 to 6 and comparative examples 1 to 6 was tested according to GB/T9754-2007 determination of the specular gloss of metallic pigment-free pigmented paint films.

Yellowing resistance test: the varnish coatings provided in examples 1 to 6 and comparative examples 1 to 6 were tested for yellowing resistance according to GB T23987-2009 Exposure to fluorescent UV and water for Artificial weather aging Exposure of pigmented and varnish coatings; Δ E indicates the total color difference between the pre-aged and post-aged samples, and the smaller the value of Δ E, the better the yellowing resistance.

The test results are shown in table 1:

TABLE 1

	Degree of gloss	Yellowing resistance
			Example 1	1％	ΔE*＜1
Example 2	2％	ΔE*＜1
			Example 3	3％	ΔE*＜1
Example 4	4％	ΔE*＜1
			Example 5	3％	ΔE*＜1
Example 6	15％	ΔE*＜1
			Comparative example 1	20％	ΔE*＜2
Comparative example 2	58％	ΔE*＜1
			Comparative example 3	7％	ΔE*＜1
Comparative example 4	23％	ΔE*＜1
			Comparative example 5	1％	ΔE*＜2
Comparative example 6	15％	ΔE*＜5

According to the test results of the examples 1 to 6 in the table 1 and the comparative example 6, the invention enables the coating prepared by the varnish to have excellent extinction effect through the synergistic effect of the wax powder, the wax slurry, the thermoplastic acrylic resin and the CAB resin, the lowest glossiness can reach 1%, and the coating has the extra-matte effect; at the same time, the coating has excellent yellowing resistance, delta E < 1. The extinction performance and the yellowing resistance of the PU varnish coating are obviously better than those of the PU varnish coating sold in the market.

When other resins were used instead of the thermoplastic acrylic resin (comparative example 1), the varnish coating prepared had significantly poor matting and yellowing resistance. When the CAB resin content in the varnish component is too low or too high (comparative example 2), too slow or too fast volatilization of the varnish coating solvent results in a varnish coating with a high gloss. When the content of the wax-containing additive is too low, the matting effect is deteriorated and the gloss of the coating is increased; when the content of the wax-containing additive is too high, the yellowing resistance of the varnish coating is reduced.

The applicant states that the present invention is illustrated by the above examples of PU varnishes and methods of preparation and use thereof, but the present invention is not limited to the above examples, i.e. it is not meant to imply that the present invention must be practiced by means of the above examples. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

Claims (23)

1. A PU varnish is characterized in that the PU varnish consists of a component A and a component B; the component A comprises the following components in parts by weight: 10-60 parts of thermoplastic acrylic resin, 1-10 parts of CAB resin and 5-15 parts of wax-containing additive; the component B comprises 5-20 parts by weight of isocyanate-containing curing agent; the wax-containing additive is a composition of wax powder and wax slurry;

the mass ratio of the wax powder to the wax slurry is 1 (2-6);

the wax powder is selected from polyolefin wax powder Lanco 1400 SF;

the wax slurry is modified polyolefin wax slurry Lanco 450C;

the component A of the PU varnish also comprises a defoaming agent, an anti-settling agent, a plasticizer, a leveling agent and an organic solvent.

2. The PU varnish according to claim 1, wherein the thermoplastic acrylic resin has a viscosity of 4000 to 30000 cps.

3. The PU varnish according to claim 1, wherein the CAB resin has a viscosity of 0.1 to 2 seconds.

4. The PU varnish according to claim 1, wherein the wax powder has a particle size of 5 to 40 μm.

5. The PU varnish according to claim 1, wherein the wax slurry has a solid content of 40 to 60%.

6. The PU varnish according to claim 1, wherein the isocyanate-containing curing agent is selected from an N3390 curing agent or an N75 curing agent.

7. The PU varnish according to claim 1, wherein the defoaming agent is a silicone defoaming agent.

8. The PU varnish according to claim 7, wherein the content of the silicone defoamer in the A component of the PU varnish is 0.1 to 0.5 parts by weight.

9. The PU varnish according to claim 1, wherein the content of the anti-settling agent in the A component of the PU varnish is 1 to 2 parts by weight.

10. The PU varnish according to claim 1, wherein the plasticizer is contained in the A component of the PU varnish in an amount of 1 to 3 parts by weight.

11. The PU varnish according to claim 1, wherein the leveling agent is an organosilicon leveling agent.

12. The PU varnish according to claim 11, wherein the content of the silicone leveling agent in the A component of the PU varnish is 0.1 to 0.5 part by weight.

13. The PU varnish according to claim 1, wherein the organic solvent is a mixture of an ester solvent and xylene.

14. The PU varnish according to claim 13, wherein the content of the ester solvent in the A component of the PU varnish is 20 to 50 parts by weight.

15. The PU varnish according to claim 13, wherein the xylene content in the A component of the PU varnish is 10 to 20 parts by weight.

16. A method for producing the PU varnish of any one of claims 1 to 15, wherein the production method comprises the steps of:

(1) mixing thermoplastic acrylic resin, CAB resin and a defoaming agent to obtain a mixture A;

(2) mixing the mixture A obtained in the step (1), a wax-containing additive and an anti-settling agent to obtain a mixture B;

(3) mixing the mixture B obtained in the step (2), a flatting agent and an organic solvent to obtain a component A of the PU varnish;

(4) and (4) mixing the component A of the PU varnish obtained in the step (3) with the component B of the PU varnish to obtain the PU varnish.

17. The method of claim 16, wherein the mixing in step (1), step (2) and step (3) is by mechanical stirring.

18. The method of claim 17, wherein the mechanical agitation of step (1) is at a speed of > 800 r/min.

19. The method according to claim 17, wherein the rotation speed of the mechanical stirring in the step (2) and the step (3) is 600 to 800r/min independently from each other.

20. The method of claim 17, wherein the mechanical agitation in step (2) and step (3) is at a temperature of 25 to 50 ℃ independently of each other.

21. The method of claim 17, wherein the mechanical stirring in step (1), step (2) and step (3) is carried out independently for 5 to 25 min.

22. The method of claim 16, wherein the method specifically comprises the steps of:

(1) mechanically stirring thermoplastic acrylic resin, CAB resin and a defoaming agent for 5-25 min under the condition that the rotating speed is more than 800r/min to obtain a mixture A;

(2) mechanically stirring the mixture A obtained in the step (1), the wax-containing additive and the anti-settling agent for 5-25 min at a rotating speed of 600-800 r/min to obtain a mixture B;

(3) mechanically stirring the mixture B obtained in the step (2), the leveling agent and the solvent for 5-25 min under the condition that the rotating speed is 600-800 r/min to obtain a component A of the PU varnish;

(4) and (4) mixing the component A of the PU varnish obtained in the step (3) with the component B of the PU varnish to obtain the PU varnish.

23. Use of the PU varnish recited in any one of claims 1 to 15 in furniture protection materials.