阅读说明：本技术 高固含低粘度净味羟基聚氨酯树脂及其制备方法与应用 (High-solid-content low-viscosity odorless hydroxyl polyurethane resin and preparation method and application thereof ) 是由 瞿金清 梅运来 朱延安 于 2020-12-24 设计创作，主要内容包括：本发明公开了高固含低粘度净味羟基聚氨酯树脂及其制备方法与应用,其制备方法为：将小分子多元醇、酸酐、催化剂一和有机溶剂混合在115～125℃保温反应2-3小时,加入环氧化合物和催化剂二在105～115℃保温5～7小时,降温90℃以下,减压蒸馏,得到星形支化结构的羟基多元醇；向反应釜中加入第一步生成的星形支化结构的羟基多元醇、小分子多元醇、聚醚多元醇、多异氰酸酯及有机溶剂,在75～85℃保温4～5h；得到高固含低粘度净味羟基聚氨酯树脂。本发明所制备的羟基聚氨酯树脂固含可达90％以上,粘度在2000mPa.s以下,反应温度低,副反应少,不需高温酯化反应,无小分子多元醇损失,树脂结构和性能易控可调等。(The invention discloses a high-solid-content low-viscosity odorless hydroxyl polyurethane resin, a preparation method and an application thereof, wherein the preparation method comprises the following steps: mixing micromolecule polyol, anhydride, a catalyst I and an organic solvent, reacting for 2-3 hours at the temperature of 115-125 ℃, adding an epoxy compound and a catalyst II, keeping the temperature for 5-7 hours at the temperature of 105-115 ℃, cooling to below 90 ℃, and distilling under reduced pressure to obtain hydroxyl polyol with a star-shaped branched structure; adding the hydroxyl polyol with the star-shaped branched structure, the micromolecular polyol, the polyether polyol, the polyisocyanate and the organic solvent which are generated in the first step into a reaction kettle, and preserving heat for 4-5 hours at the temperature of 75-85 ℃; obtaining the odorless hydroxyl polyurethane resin with high solid content and low viscosity. The hydroxyl polyurethane resin prepared by the invention has the solid content of more than 90 percent, the viscosity of less than 2000mPa.s, low reaction temperature, less side reaction, no need of high-temperature esterification reaction, no loss of micromolecular polyol, easily controllable and adjustable resin structure and performance and the like.)

1. A preparation method of high-solid-content low-viscosity odorless hydroxyl polyurethane resin is characterized by comprising the following steps of:

1) preparation of hydroxyl polyol with star-branched structure: mixing small molecular polyol, anhydride, a first catalyst and an organic solvent at 115-125 ℃ for heat preservation reaction for 2-3 hours, adding an epoxy compound and a second catalyst when the acid value of the resin is determined to be below 155mgKOH/g, preserving the temperature at 105-115 ℃ for 5-7 hours, determining the acid value of the resin to be below 12.0mgKOH/g, cooling to be below 90 ℃, and carrying out reduced pressure distillation to obtain hydroxyl polyol with a star-shaped branched structure; the epoxy compound is one of benzyl glycidyl ether, tert-butyl glycidyl ether, epichlorohydrin and tert-carbonic acid glycidyl ether; the catalyst I is one of p-toluenesulfonic acid and p-toluenesulfonic acid monohydrate; the catalyst II is one of tetraethylammonium bromide, tetrabutylammonium bromide and triphenylphosphine;

2) preparation of high-solid low-viscosity odorless hydroxyl polyurethane resin: adding the hydroxyl polyol with the star-shaped branched structure, the micromolecular polyol, the polyether polyol, the polyisocyanate and the organic solvent which are generated in the first step into a reaction kettle, and preserving heat for 4-5 hours at the temperature of 75-85 ℃; and stopping the reaction when the NCO content of the system is measured to be lower than 0.5 percent, thus obtaining the odorless hydroxyl polyurethane resin with high solid content and low viscosity.

2. The method of preparing a high solids, low viscosity, odorless hydroxy polyurethane resin of claim 1, wherein: in the step 1), the raw materials are used in parts by mass: 3.5-6.7 parts of micromolecular polyol, 15.6-19.5 parts of acid anhydride, 0.02-0.03 part of catalyst I, 12.2-18.0 parts of epoxy compound and 0.02-0.03 part of catalyst II;

in the step 2), the raw materials are used in parts by mass: 5.5-8 parts of small molecular polyol, 23.4-27.3 parts of polyether polyol and 13-23 parts of polyisocyanate.

3. The method of preparing a high solids, low viscosity, odorless hydroxy polyurethane resin of claim 1, wherein: the polyether polyol is one or more of N210, N220 and N303;

in the step 1) and the step 2), the small molecular polyol is one of trimethylolpropane, pentaerythritol, 1, 3-butanediol, 1, 4-butanediol, neopentyl glycol, diethylene glycol and 2-butyl-2-ethyl-1, 3-propanediol.

4. The method of preparing a high solids, low viscosity, odorless hydroxy polyurethane resin of claim 1, wherein: the polyisocyanate is diisocyanate or the adduct of toluene diisocyanate and trimethylolpropane.

5. The method of preparing a high solids, low viscosity, odorless hydroxy polyurethane resin of claim 4, wherein: the diisocyanate is one of toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate and diphenylmethane diisocyanate; the adduct of the toluene diisocyanate and the trimethylolpropane is one of a toluene diisocyanate trimer, a hexamethylene diisocyanate trimer and a biuret of hexamethylene diisocyanate;

the acid anhydride is one or more of phthalic anhydride, hexahydrophthalic anhydride, methyl hexahydrophthalic anhydride, maleic anhydride and succinic anhydride.

6. The method of preparing a high solids, low viscosity, odorless hydroxy polyurethane resin of claim 1, wherein: in the step 1) and the step 2), the organic solvent is one or more of acetone, butanone, methyl isoamyl ketone, ethyl acetate and butyl acetate; the amount of the organic solvent in the step 1) is 1-2 parts by mass, and the amount of the organic solvent in the step 2) is 4-4.5 parts by mass.

7. The method of preparing a high solids, low viscosity, odorless hydroxy polyurethane resin of claim 1, wherein: the reduced pressure distillation in the step 1) is reduced pressure distillation for 1-3h under the vacuum degree of 0.06-0.08 MPa.

8. A high-solid-content low-viscosity odorless hydroxyl polyurethane resin is characterized in that: the preparation method of claim 1 to 7, wherein the high-solid low-viscosity odorless hydroxyl polyurethane resin has a VOC content of less than 40g/L, a solid content of 90% or more, a viscosity of 2000mPa.s or less, and a hydroxyl content of 2.5 to 6.0%.

9. The use of the high solids, low viscosity, odor free polyurethane resin in a two component wood lacquer coating of claim 8, wherein the two component wood lacquer coating is formulated from a component a and a component B of a curing agent, in the presence of an adjuvant; 38-42 parts of high-solid low-viscosity odorless hydroxyl polyurethane resin in the component A and 40-43 parts of curing agent B in parts by mass; the auxiliary agent comprises matte powder, a defoaming agent and a wetting agent.

10. The application of the high-solid-content low-viscosity odorless hydroxyl polyurethane resin in the two-component wood lacquer coating is characterized in that the amount of the matte powder is 3.6-4.5 parts by mass, the amount of the defoaming agent is 0.2-0.3 part by mass, and the amount of the wetting agent is 0.2-0.3 part by mass;

the curing agent is one of curing agent F900, curing agent G21 and curing agent G18;

the matte powder is one of C803, ED30 and KY 30;

the defoaming agent is one of BYKA530 and BYK-028;

the wetting agent is one of BYK349 and BYK 333;

the surface drying time of the obtained paint film is within 15min, the actual drying time is less than 1.5H, the activation period is more than 4H, the residual VOC of the paint film after 48H is less than 4g/L, the hardness is higher than 2H, the adhesive force is 0 grade, and the paint film has good chemical resistance and thermal stability.

Technical Field

The invention belongs to the technical field of double-component polyurethane wood lacquer, relates to hydroxyl polyurethane resin, and particularly relates to a preparation method and application of high-solid-content low-viscosity odorless hydroxyl polyurethane resin.

Background

The two-component polyurethane wood paint has excellent physical and chemical properties, and is widely applied to wood furniture and wood floors. According to the difference of the hydroxyl-containing components, the polyurethane can be classified into acrylic polyurethane, alkyd polyurethane, polyacid polyurethane, polyether polyurethane, epoxy polyurethane and the like.

Along with the improvement of living standard of people, the restriction regulation of Volatile Organic Compound (VOC) emission in the two-component polyurethane wood paint is stricter, and people also put higher requirements on the size and components of the odor emitted when the two-component polyurethane wood paint is used for furniture and floors; because the solvent is released slowly in the traditional wood lacquer film-forming process, the release period is long, and certain odor remains after a long period of time after construction, great potential harm is brought to the health of people. Therefore, the existing paint film of the two-component polyurethane wood paint has long-term odor which can not meet the demands of the market and consumers.

The prior art also has relevant improvement aiming at the odor of polyurethane wood lacquer, for example, Chinese patent application CN102634274A discloses a wood lacquer and a preparation method thereof, comprising a main agent and a curing agent, 1) 55-75 parts of alkyd resin, 2) 1.5-9.5 parts of matting powder, 3) 3-12 parts of polymethyl acrylate, 4) 3-18 parts of castor oil resin, 5) 5-15 parts of butyl acetate and ethyl acetate, 6) an auxiliary agent and 0.3-1.5 parts of the main agent and the curing agent; curing agent: 1) 10-25 parts of butyl acetate, 2) 15-25 parts of ethyl acetate, 3) 10-20 parts of isocyanate tripolymer curing agent, 4) 20-40 parts of isocyanate addition product curing agent, wherein the mass ratio of the main agent to the curing agent is as follows: 1: 0.3-0.8. However, the crosslinking density of the alkyd resin and the curing agent of the woodware is low, so that the surface drying time is more than 40 minutes, the time for coating the paint and volatilizing gas is long, the compactness of the paint film is poor, the residual smell is still contained in a long time, and the production cost is high.

The invention Chinese patent CN102286246A discloses a short-oil alkyd resin and a low-odor polyurethane paint comprising the alkyd resin, wherein an adipic acid long-chain structure is added in the resin design, and three-functional group alcohol and four-functional group alcohol with different structures are matched to enhance the three-dimensional structure of a resin molecular chain, so that the release property of the product in the film forming process is improved, the odor of a furniture product is greatly reduced, and the odor is released within 24 hours after the furniture product is normally dried.

Chinese invention patent CN105399934A discloses a two-step process for synthesizing low-odor alkyd resin, which comprises the steps of adding soybean oleic acid, pentaerythritol, an auxiliary agent and a solvent for mixing, introducing nitrogen to replace internal air, heating to 205-plus-215 ℃, preserving heat for 1 hour, cooling to 120 ℃, adding ethylene glycol, neopentyl glycol, phthalic anhydride, maleic anhydride and the solvent, heating to 160-plus-170 ℃, preserving heat for 1 hour, heating to 180-plus-190 ℃, preserving heat for one hour, heating to 205-plus-215 ℃, preserving heat, esterifying until the viscosity and acid value are qualified, cooling, adding the solvent, diluting, filtering and discharging, wherein when the prepared resin is used for wood lacquer and finish paint, the film-forming and odor-removing effects are good, the solvent volatility is good, the gloss stability is good, the scratch resistance is excellent, the requirements of the manufacturing industry of suites and hotels are met, but the synthesis process temperature is higher, the highest temperature reaches 215 ℃, the cost is high, and the reaction is accompanied by a large amount of by-products.

In conclusion, the prior art thoroughly solves the problem of residual odor after the furniture coating paint is dried, and the comprehensive performance of the coating film needs to be improved.

Disclosure of Invention

The invention aims to overcome the problems in the prior art and provide the high-solid-content low-viscosity odorless hydroxyl polyurethane resin with small residual odor after paint drying, reaction temperature lower than 130 ℃, solid content higher than 90%, viscosity lower than 2000mPa.s and VOC content lower than 40g/L and the preparation method thereof.

The invention also aims to provide the application of the high-solid-content low-viscosity odorless hydroxyl polyurethane resin in the two-component wood lacquer coating, the residual VOC of a lacquer film after 48 hours is lower than 4g/L, the hardness is higher than 2H, the adhesive force reaches 0 level, the surface drying time is less than 15min, the actual drying time is less than 1.5 hours, and the two-component wood lacquer coating has excellent chemical resistance and thermal stability.

The invention provides a preparation method of odorless hydroxyl polyurethane resin with high solid content and low viscosity aiming at the defects and shortcomings of the odorless polyurethane wood lacquer. The invention adopts micromolecular polyalcohol as a core, and the micromolecular polyalcohol reacts with acid anhydride to form polybasic acid with a branched structure, so that the polybasic acid and an epoxy compound carry out ring-opening reaction to remove redundant water of a system, synthesize hydroxyl polyalcohol with a star-shaped branched structure, then react with polyisocyanate to synthesize hydroxyl polyurethane resin with a three-dimensional structure, and further adjust the hydroxyl functionality of the polyurethane polyalcohol by adopting the micromolecular polyalcohol and the polyether polyalcohol. On one hand, due to the highly branched structure of the synthesized hydroxyl polyurethane resin, organic solvent is hardly required to be added in the reaction process, so that the solid content of the synthesized hydroxyl polyurethane resin is up to more than 90 percent, the residue of the VOC content of the hydroxyl polyurethane is greatly reduced, and the VOC content of the generated hydroxyl polyurethane resin is lower than 40g/L, on the other hand, due to the highly branched structure, under the condition of the same molecular weight, the winding among molecular chains of the hydroxyl polyurethane is greatly reduced, so that the viscosity of the generated hydroxyl polyurethane resin is lower than 2000mPa & s, and due to the larger space three-dimensional structure, the synthesized hydroxyl polyurethane resin is beneficial to the release of the solvent, and the residue of the solvent in the paint film after the paint film is cured is reduced; in addition, the hydroxyl groups are uniformly distributed on the outer surface of the spatial structure, so that the hydroxyl groups have stronger activity, the quick reaction between the hydroxyl groups and NCO groups of a curing agent is facilitated to form a urethane bond, the surface drying time and the actual drying time of the hydroxyl groups are accelerated, the hydroxyl groups have better thermodynamic performance, the hardness of a paint film prepared by the hydroxyl groups and the curing agent can reach more than 2H, the adhesive force is 0 grade, the residual VOC (volatile organic compounds) of the paint film after being dried for 48 hours is lower than 4g/L, the chemical resistance is excellent, and the synthesized hydroxyl polyurethane structure can be regulated and controlled.

The purpose of the invention is realized by the following technical scheme:

a preparation method of high-solid-content low-viscosity odorless hydroxyl polyurethane resin comprises the following steps:

1) preparation of hydroxyl polyol with star-branched structure: mixing small molecular polyol, anhydride, a first catalyst and an organic solvent at 115-125 ℃ for heat preservation reaction for 2-3 hours, adding an epoxy compound and a second catalyst when the acid value of the resin is determined to be below 155mgKOH/g, preserving the temperature at 105-115 ℃ for 5-7 hours, determining the acid value of the resin to be below 12.0mgKOH/g, cooling to be below 90 ℃, and carrying out reduced pressure distillation to obtain hydroxyl polyol with a star-shaped branched structure; the epoxy compound is one of benzyl glycidyl ether, tert-butyl glycidyl ether, epichlorohydrin and tert-carbonic acid glycidyl ether (E10P); the catalyst I is one of p-toluenesulfonic acid and p-toluenesulfonic acid monohydrate; the catalyst II is one of tetraethylammonium bromide, tetrabutylammonium bromide and triphenylphosphine;

2) preparation of high-solid low-viscosity odorless hydroxyl polyurethane resin: adding the hydroxyl polyol with the star-shaped branched structure, the micromolecular polyol, the polyether polyol, the polyisocyanate and the organic solvent which are generated in the first step into a reaction kettle, and preserving heat for 4-5 hours at the temperature of 75-85 ℃; and stopping the reaction when the NCO content of the system is measured to be lower than 0.5 percent, thus obtaining the odorless hydroxyl polyurethane resin with high solid content and low viscosity.

In order to further achieve the purpose of the invention, preferably, in step 1), the raw materials are used in parts by mass: 3.5-6.7 parts of micromolecular polyol, 15.6-19.5 parts of acid anhydride, 0.02-0.03 part of catalyst I, 12.2-18.0 parts of epoxy compound and 0.02-0.03 part of catalyst II;

in the step 2), the raw materials are used in parts by mass: 5.5-8 parts of small molecular polyol, 23.4-27.3 parts of polyether polyol and 13-23 parts of polyisocyanate.

Preferably, the polyether polyol is one or more of N210 (polyether diol with molecular weight of 1000), N220 (polyether diol with molecular weight of 2000) and N303 (polyether triol with molecular weight of 375); in the step 1) and the step 2), the small molecular polyol is one of trimethylolpropane, pentaerythritol, 1, 3-butanediol, 1, 4-butanediol, neopentyl glycol, diethylene glycol and 2-butyl-2-ethyl-1, 3-propanediol.

Preferably, the polyisocyanate is diisocyanate or an adduct of toluene diisocyanate and trimethylolpropane.

Preferably, the diisocyanate is one of toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate and diphenylmethane diisocyanate; the adduct of the toluene diisocyanate and the trimethylolpropane is one of a toluene diisocyanate trimer, a hexamethylene diisocyanate trimer and a biuret of hexamethylene diisocyanate;

the acid anhydride is one or more of phthalic anhydride, hexahydrophthalic anhydride, methyl hexahydrophthalic anhydride, maleic anhydride and succinic anhydride.

Preferably, in step 1) and step 2), the organic solvent is one or more of acetone, butanone, methyl isoamyl ketone, ethyl acetate and butyl acetate; the amount of the organic solvent in the step 1) is 1-2 parts by mass, and the amount of the organic solvent in the step 2) is 4-4.5 parts by mass.

Preferably, the reduced pressure distillation in the step 1) is reduced pressure distillation for 1 to 3 hours under the vacuum degree of 0.06 to 0.08 MPa.

The high-solid-content low-viscosity odorless hydroxyl polyurethane resin is prepared by the preparation method, and has the VOC content of less than 40g/L, the solid content of more than 90 percent, the viscosity of less than 2000mPa.s and the hydroxyl content of 2.5 to 6.0 percent.

The application of the high-solid-content low-viscosity odorless hydroxyl polyurethane resin in the two-component wood paint coating is as follows: the two-component wood lacquer coating is prepared from a component A and a component B of a curing agent under the action of an auxiliary agent; 38-42 parts of high-solid low-viscosity odorless hydroxyl polyurethane resin in the component A and 40-43 parts of curing agent B in parts by mass; the auxiliary agent comprises matte powder, a defoaming agent and a wetting agent.

Preferably, the weight parts of the matte powder are 3.6-4.5 parts, the defoaming agent is 0.2-0.3 part, and the wetting agent is 0.2-0.3 part;

the curing agent is one of curing agents F900, G21 and G18 which are produced by Jia Bao Li chemical group Limited company;

the matte powder is one of American Grace C803, American Grace ED30 and Keyingyin chemical KY30, and the defoaming agent is one of Bikk BYKA530 and BYK-028;

the wetting agent is one of BYK349 and BYK 333;

the application of the high-solid-content low-viscosity odorless hydroxyl polyurethane resin in the wood paint is used as a component A of a double-component wood paint and a component B of a curing agent, the paint is prepared under the action of an auxiliary agent, the surface drying time of a paint film is within 15min, the actual drying time is less than 1.5H, the activation period is more than 4H, the actual construction requirement can be met, the residual VOC of the paint film after 48H is less than 4g/L, the hardness is more than 2H, the adhesive force is 0 grade, and the paint film has good chemical resistance and thermal stability.

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

(1) according to the invention, the star-shaped hydroxyl polyol is synthesized, and the star-shaped hydroxyl polyol has a highly branched structure and a larger spatial three-dimensional structure, so that the volatilization of residual solvent in a paint film can be accelerated, and the cured paint film can achieve the effect of odor elimination.

(2) The solid content of the hydroxyl polyurethane resin synthesized by the method reaches more than 90 percent, the viscosity is lower than 2000mPa.s, the use of organic solvents is greatly reduced, and the synthesized hydroxyl polyurethane resin achieves the effect of odor elimination.

(3) Compared with the existing process, the synthesis process has the advantages of low energy consumption, no high temperature exceeding 120 ℃, stable reaction process, no need of high-temperature esterification reaction, no loss of micromolecular polyol and the like;

(4) the resin structure of the invention is easy to regulate and control, and the contents of soft and hard segments, the functionality of hydroxyl and the like in the molecular structure can be regulated and controlled according to market demands, thereby regulating and controlling the hardness and flexibility of a paint film.

Drawings

FIG. 1 is a graph showing the appearance of the high solid low viscosity odorless hydroxy polyurethane resin product obtained in example 1.

FIG. 2-1 is a molecular structural formula of trimethylolpropane;

FIG. 2-2 shows the molecular structure of pentaerythritol.

FIG. 3 is an IR spectrum of the high solid low viscosity odour free hydroxy polyurethane resin obtained in example 1.

FIG. 4 is a thermogram and a microtransaction thermogram of a two-component polyurethane wood paint coating paint film prepared from the high solids low viscosity odour-free hydroxyl polyurethane resin of example 1.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described with reference to the accompanying drawings and examples. It should be understood that the examples are only for explaining the present invention, and do not limit the scope of protection of the present invention.

The jaboticaoli H198 resin for comparison in the embodiment is produced by jaboticaoli chemical group member company Limited, is used as a component A of polyurethane wood paint, is matched with a curing agent component B to form a two-component polyurethane wood paint coating, is mainly used in the fields of wood furniture, wood floors and the like, has excellent mechanical properties, is low in yellowing and low in VOC volatilization.

In the following examples, percentages (%) are mass percentages unless otherwise specified.

The performances of the high-solid-content low-viscosity odorless hydroxyl polyurethane resin and the polyurethane wood lacquer coating are detected by adopting the following method:

the viscosity of the resin was determined according to ASTM D2196-1986 using a Brookfield RVF type rotational viscometer;

the solids content of the resin was determined according to GB 1725-79; testing the hardness of the coating film according to GB/6379-2006;

determining the adhesion of the coating according to ISO2409-2007 Chinese edition;

the glossiness of the coating film is measured according to GB/T9754-2007;

measuring the water absorption of the coating according to GB/T23999-;

the flexibility of the coating film is measured according to GB/1731-93;

determining the VOC content of the resin and the coating according to GB/T23986-2009;

putting the cured paint film into a glass jar, opening the jar after 48h, smelling the smell, and grading and measuring the smell.

Example 1:

(1) preparation of high-solid-content low-viscosity odorless hydroxyl polyurethane resin

The raw material components and the dosage are shown in the following table 1 in parts by mass

TABLE 1

The preparation process comprises the following steps:

(1) preparation of hydroxyl polyol with star-branched structure: adding trimethylolpropane, phthalic anhydride, p-toluenesulfonic acid (catalyst I) and a small amount of ethyl acetate into a reaction kettle, heating to 120 ℃, stirring, carrying out heat preservation reaction at 120 ℃ for 2 hours, and determining the acid value of the resin to be below 155 mgKOH/g; adding epichlorohydrin and tetrabutylammonium bromide (catalyst II) into the system, keeping the temperature at 110 ℃ for 5 hours, and determining that the acid value of the resin is below 12.0 mgKOH/g; cooling to below 90 ℃, distilling under reduced pressure for 1-3h under the vacuum degree of 0.06-0.08MPa, and removing the excessive moisture solvent to obtain the hydroxyl polyol with the star-shaped branched structure.

(2) Preparation of high-solid low-viscosity odorless hydroxyl polyurethane resin: adding the hydroxyl polyol, polyether triol N303, polyether diol N210, neopentyl glycol, toluene diisocyanate, TDI/TMP adduct (G21) and a small amount of acetone and butyl acetate which are generated in the first step into a reaction kettle, and keeping the temperature at 85 ℃ for 4 hours; when the NCO content of the system is determined to approach 0.5 percent, the reaction is stopped, and the odorless hydroxyl polyurethane resin with high solid content and low viscosity is obtained.

(2) The properties of the high solids low viscosity neat hydroxyl polyurethane resin are shown in table 2.

TABLE 2

(3) Preparation and performance of double-component polyurethane wood paint

The formulation and composition of the two-component polyurethane wood lacquer coating in parts by mass are given in table 3

TABLE 3

Adding the high-solid-content low-viscosity odorless hydroxyl polyurethane resin, the matt powder, the defoaming agent and the wetting agent into a container, dispersing at a low speed of 5min at a rotating speed of 600r/min, adding an F900 curing agent and a diluent into the container, dispersing for 10min at a rotating speed of 1000r/min, filtering through 300-mesh filter cloth to obtain a two-component polyurethane wood paint coating, and coating the coating on a wood plate, a tinplate and a glass plate respectively.

(4) The properties of the paint film were determined in comparison with the properties of Jia Bao Li H198, as shown in Table 4 below:

TABLE 4

Odor: and (3) putting the cured paint film into a sealed glass jar, uncovering after 48 hours, and smelling the smell, wherein the evaluation value is 0-5 grade, and the lower the grade, the smaller the smell is.

FIG. 1 shows the appearance of a high solids, low viscosity, odorless hydroxyl polyurethane resin as a colorless, transparent liquid, which may be referred to as a "crystal resin".

FIG. 2-1 is a structural formula of trimethylolpropane, which is the core of the star-branched hydroxyl polyol of example 1.

The structural formula of pentaerythritol in FIG. 2-2 is the structure of the hydroxyl polyol of the star-branched structure of example 2.

FIG. 3 is an IR spectrum of the high solids low viscosity odorless hydroxy polyurethane resin of example 1. As shown in FIG. 3, 3531cm of the spectrum^-1Absorption peak of extension vibration and bending vibration, 1070cm, attributed to N-H^-1The peak of the C-N absorption of stretching vibration at 1734cm^-1A strong stretching vibration absorption peak of C ═ O in the urethane bond appears, indicating that the aqueous dispersion forms a urethane group; at 2923cm^-1A stretching vibration absorption peak of methyl; 2852cm^-1A methylene stretching vibration absorption peak is formed; 1461cm^-1、1382cm^-1The deformation vibration peaks of methyl and methylene are formed; at 741cm^-1The characteristic absorption peak of a C-Cl bond is formed, so that the hydroxyl polyol participates in the reaction, and infrared spectrum analysis shows that the high-solid-content low-viscosity odorless hydroxyl polyurethane resin is synthesized.

FIG. 4 is a thermogravimetric plot and a micro-commercial thermogravimetric plot of a UV-cured wood lacquer coating paint film prepared from a high-solid low-viscosity odorless hydroxyl polyurethane resin. The mass loss of the paint film at 210 ℃ is less than 1 percent, and almost no mass loss is caused, and the loss is probably mainly caused by the volatilization of residual solvent of the paint film; the temperature is higher than 265 ℃ when the mass loss is 5 percent and higher than 350 ℃ when the mass loss is 50 percent, which shows that the paint film has better heat-resistant stability.

As can be seen from table 4, the odor of example 1 has a smaller odor and the VOC content of the coating film is lower than that of the comparative example, because the synthesized hydroxyl polyurethane has a larger spatial three-dimensional structure, which accelerates the volatilization of the residual solvent VOC in the resin, takes longer time than the dry film and volatile gas of the wood lacquer described in chinese patent application CN102634274A, and still contains residual odor, and in addition, the production cost is higher; compared with a comparative example, the surface drying time and the actual drying time of the paint film are faster in example 1, so that the paint film has excellent mechanical properties, the hydroxyl groups of the synthesized hydroxyl polyurethane are uniformly distributed outside a spatial three-dimensional structure, the activity of the hydroxyl groups is improved, the crosslinking density of the hydroxyl groups and the component B of a curing agent is increased, the curing film forming speed of the paint film is accelerated, the residual VOC (volatile organic compound) of the paint film is lower than 2g/L, and therefore the odor purification effect is achieved, compared with the paint disclosed by Chinese patent CN102286246A, the short-oil alkyd resin and the low-odor polyurethane paint, the release performance of the product in the film forming process is improved by improving the three-dimensional structure of the molecular chain of the alkyd resin, but the real odor purification of the product is not achieved; compared with the comparative example, the example has better thermodynamic performance, the hardness of the paint film reaches 2H, the structure of the synthesized hydroxyl polyurethane can be regulated, the functionality of the hydroxyl polyurethane can be regulated by changing the structure of the small molecular polyol, the crosslinking density of the hydroxyl polyurethane can be changed, and the hardness and the flexibility of the paint film formed by curing the hydroxyl polyurethane can be regulated by regulating the proportion of the hard segment component and the soft segment component of the resin system. The hydroxyl polyurethane resin has excellent chemical resistance, the structure of the synthesized hydroxyl polyurethane can be regulated, the functionality of the hydroxyl polyurethane can be regulated by changing the structure of the micromolecule polyalcohol, the crosslinking density of the hydroxyl polyurethane can be changed, and the hardness and the flexibility of a paint film formed by curing the hydroxyl polyurethane can be regulated by regulating the proportion of a hard section component and a soft section component of a resin system. Compared with the technology for synthesizing the low-odor alkyd resin by the two-step method disclosed by the Chinese invention patent CN105399934A, the prepared alkyd resin can basically meet the requirement of odor elimination when being used for polyurethane wood paint, but the synthesis technology has higher temperature, the highest temperature reaches 215 ℃, the cost is higher, and a large amount of byproducts are accompanied by reaction. The process does not need high-temperature reaction, has low cost, no loss of micromolecular polyhydric alcohol and few side reactions, contains a small amount of ester bonds compared with alkyd resin, and improves the chemical resistance of the alkyd resin.

In the embodiment, the high-solid-content low-viscosity odorless hydroxyl polyurethane resin is mainly applied to preparation of the two-component wood paint. Most of hydroxyl resin of the wood paint existing in the current market is alkyd resin, has more ester bonds, is poor in chemical resistance, has the hardness of a paint film below H, has residual resin smell derived from unreacted oleic acid, has high resin viscosity, and needs more diluents when being mixed with a curing agent B component to prepare paint, so that more organic solvents remain in the paint film after solid content, the hardness of the paint film is low, the residual VOC content of the paint film is too high, after the paint film is coated in a furniture factory and packaged, the paint film is still provided with large unpleasant smell after being unpacked by a customer. The invention can perfectly solve the problems, on one hand, the synthesized hydroxyl polyurethane resin has a highly branched structure, almost no organic solvent is needed to be added in the reaction process, so that the solid content of the synthesized hydroxyl polyurethane resin is more than 90 percent, the residue of the VOC content of the hydroxyl polyurethane is greatly reduced, and the VOC content of the generated hydroxyl polyurethane resin is lower than 40g/L, on the other hand, the winding among molecular chains of the hydroxyl polyurethane is greatly reduced under the condition of the same molecular weight due to the highly branched structure, so that the viscosity of the generated hydroxyl polyurethane resin is lower than 2000mPa.s, the synthesized hydroxyl polyurethane resin is beneficial to the release of the solvent due to the larger space three-dimensional structure, the residue of the solvent in a paint film after the paint film is cured is reduced, and in addition, the hydroxyl is uniformly distributed on the outer surface of the space structure, so that the hydroxyl has stronger activity and is beneficial to the quick reaction of the hydroxyl with the NCO group of, the surface drying time and the actual drying time of the hydroxyl-modified polyurethane resin are accelerated, so that the hydroxyl-modified polyurethane resin has better thermodynamic property, the hardness of a paint film after being matched with a curing agent can reach more than 2H, the adhesive force is 0 grade, the residual VOC of the paint film is lower than 4g/L, the hydroxyl-modified polyurethane resin has excellent chemical resistance, the structure of the synthesized hydroxyl-modified polyurethane can be regulated, the functionality of the hydroxyl-modified polyurethane can be regulated by changing the structure of micromolecule polyol, the crosslinking density of the hydroxyl-modified polyurethane resin can be changed, and the hardness and the flexibility of the paint film formed by curing the hydroxyl-modified polyurethane can be regulated by regulating the proportion of hard-segment components and soft-segment components.

Example 2:

(1) preparation of high-solid-content low-viscosity odorless hydroxyl polyurethane resin

The raw material components and the amounts thereof are shown in the following table 5 in parts by mass

TABLE 5

The preparation process comprises the following steps:

(1) preparation of hydroxyl polyol with star-branched structure: adding pentaerythritol, maleic anhydride, hexahydrophthalic anhydride, p-toluenesulfonic acid monohydrate (catalyst I) and a small amount of ethyl acetate into a reaction kettle, heating to 115 ℃, stirring, carrying out heat preservation reaction at 115 ℃ for 2 hours, and determining that the acid value of the resin is below 150 mgKOH/g; adding benzyl glycidyl ether and tetraethyl ammonium bromide (catalyst II) into the system, keeping the temperature at 110 ℃ for 7 hours, and measuring the acid value of the resin to be below 12.0 mgKOH/g; cooling to below 90 ℃, distilling under reduced pressure for 1-3h under the vacuum degree of 0.06-0.08MPa, and removing excessive water solvent to obtain the hydroxyl polyol with the star-shaped branched structure.

(2) Preparation of high-solid low-viscosity odorless hydroxyl polyurethane resin: and adding the hydroxyl polyol generated in the first step, polyether triol N303, polyether diol N210, 2-butyl-2-ethyl-1, 3-propylene glycol, diethylene glycol, isophorone diisocyanate, toluene diisocyanate trimer and a small amount of butanone and butyl acetate into a reaction kettle, keeping the temperature at 75 ℃ for 5 hours, and stopping the reaction when the NCO content of a measured system approaches to 0 to obtain the high-solid-content low-viscosity odorless hydroxyl polyurethane resin. (2) The properties of the high solids low viscosity neat hydroxyl polyurethane resin are shown in table 6.

TABLE 6

(3) Preparation and performance of double-component polyurethane wood paint

The formulation and composition of the two-component polyurethane wood paint in parts by mass are given in Table 7

TABLE 7

Adding the high-solid-content low-viscosity odorless hydroxyl polyurethane resin, the matt powder, the defoaming agent and the wetting agent into a container, dispersing at a low speed of 5min at a rotating speed of 600r/min, adding an F900 curing agent and a diluent into the container, dispersing for 10min at a rotating speed of 1000r/min, filtering through 300-mesh filter cloth to obtain a two-component polyurethane wood paint coating, and coating the coating on a wood plate, a tinplate and a glass plate respectively.

(4) The film properties were measured in comparison with the properties of Jia Bao Li H198, as shown in Table 8 below:

TABLE 8

Odor: and (3) putting the cured paint film into a sealed glass jar, uncovering after 48 hours, and smelling the smell, wherein the evaluation value is 0-5 grade, and the lower the grade, the smaller the smell is.

Example 3:

(1) preparation of high-solid-content low-viscosity odorless hydroxyl polyurethane resin

The raw material components and the amounts thereof are as follows in parts by mass in the following table 9

TABLE 9

The preparation process comprises the following steps:

(1) preparation of hydroxyl polyol with star-branched structure: adding pentaerythritol, succinic anhydride, methyl hexahydrophthalic anhydride, p-toluenesulfonic acid (catalyst I) and a small amount of ethyl acetate into a reaction kettle, heating to 120 ℃, stirring, reacting at 125 ℃ for 3 hours under heat preservation, and determining the acid value of the resin to be below 150 mgKOH/g; adding tert-butyl glycidyl ether and triphenylphosphine (catalyst II) into the system, keeping the temperature at 105 ℃ for 6 hours, and measuring the acid value of the resin to be below 12.0 mgKOH/g; cooling to below 90 ℃, distilling under reduced pressure for 1-3h under the vacuum degree of 0.06-0.08MPa, and removing excessive water solvent to obtain the hydroxyl polyol with the star-shaped branched structure.

(2) Preparation of high-solid low-viscosity odorless hydroxyl polyurethane resin: adding the hydroxyl polyol generated in the first step, polyether triol N303, polyether diol N220, 2-butyl-2-ethyl-1, 3-propanediol, 1.3-butanediol, toluene diisocyanate, hexamethylene diisocyanate trimer and a small amount of methyl isoamyl ketone and butyl acetate into a reaction kettle, preserving the temperature at 85 ℃ for 4.5 hours, and stopping the reaction when the measured NCO content of the system is less than 0.5 percent to obtain the odorless hydroxyl polyurethane resin with high solid content and low viscosity.

(2) The properties of the high solids low viscosity neat hydroxyl polyurethane resin are shown in table 10.

Watch 10

(3) Preparation and performance of double-component polyurethane wood paint

The formulation and composition of the two-component polyurethane wood paint in parts by mass are given in Table 11

TABLE 11

Adding the high-solid-content low-viscosity odorless hydroxyl polyurethane resin, the matt powder, the defoaming agent and the wetting agent into a container, dispersing at a low speed of 5min at a rotating speed of 600r/min, adding an F900 curing agent and a diluent into the container, dispersing for 10min at a rotating speed of 1000r/min, filtering through 300-mesh filter cloth to obtain a two-component polyurethane wood paint coating, and coating the coating on a wood plate, a tinplate and a glass plate respectively.

(4) The paint film properties were measured in comparison with the properties of javelin H198, as shown in table 12 below:

TABLE 12

Odor: and (3) putting the cured paint film into a sealed glass jar, uncovering after 48 hours, and smelling the smell, wherein the evaluation value is 0-5 grade, and the lower the grade, the smaller the smell is.

Example 4:

(1) preparation of high-solid-content low-viscosity odorless hydroxyl polyurethane resin

The raw material components and the amounts thereof are as shown in Table 13 below in parts by mass

Watch 13

The preparation process comprises the following steps:

(1) preparation of hydroxyl polyol with star-branched structure: adding trimethylolpropane, methyl hexahydrophthalic anhydride, phthalic anhydride, p-toluenesulfonic acid (catalyst I) and a small amount of ethyl acetate into a reaction kettle, heating to 120 ℃, stirring, reacting at 120 ℃ for 3 hours under heat preservation, and determining the acid value of the resin to be below 150 mgKOH/g; adding tertiary carbonic acid glycidyl ether (E10P) and triphenylphosphine (catalyst II) into the system, keeping the temperature at 105 ℃ for 5 hours, and measuring the acid value of the resin to be below 12.0 mgKOH/g; cooling to below 90 ℃, distilling under reduced pressure for 1-3h under the vacuum degree of 0.06-0.08MPa, and removing excessive water solvent to obtain the hydroxyl polyol with the star-shaped branched structure.

(2) Preparation of high-solid low-viscosity odorless hydroxyl polyurethane resin: adding hydroxyl polyol generated in the first step, polyether triol N303, polyether diol N210, 2-butyl-2-ethyl-1, 3-propanediol, 1.4-butanediol, toluene diisocyanate, diphenylmethane diisocyanate, biuret of hexamethylene diisocyanate and a small amount of acetone and butyl acetate into a reaction kettle, preserving the temperature for 4 hours at 80 ℃, and stopping the reaction when the measured NCO content of the system is less than 0.5 percent to obtain the odorless hydroxyl polyurethane resin with high solid content and low viscosity.

(2) The properties of the high solid low viscosity neat hydroxyl polyurethane resin are shown in table 14.

TABLE 14

(3) Preparation and performance of double-component polyurethane wood paint

The formulation and composition of the two-component polyurethane wood paint in parts by mass are given in Table 15

Watch 15

Adding the high-solid-content low-viscosity odorless hydroxyl polyurethane resin, the matt powder, the defoaming agent and the wetting agent into a container, dispersing at a low speed of 5min at a rotating speed of 600r/min, adding an F900 curing agent and a diluent into the container, dispersing for 10min at a rotating speed of 1000r/min, filtering through 300-mesh filter cloth to obtain a two-component polyurethane wood paint coating, and coating the coating on a wood plate, a tinplate and a glass plate respectively.

(4) The film properties were measured in comparison with the properties of Jia Bao Li H198, as shown in Table 16 below:

TABLE 16

Odor: and (3) putting the cured paint film into a sealed glass jar, uncovering after 48 hours, and smelling the smell, wherein the evaluation value is 0-5 grade, and the lower the grade, the smaller the smell is.

The high-solid-content low-viscosity odorless hydroxyl polyurethane resin prepared by the invention has the characteristics of low VOC (volatile organic compound) emission, low viscosity and high solid content, and the prepared coating film has the advantages of high glossiness, good chemical resistance, high hardness, low VOC content of a residual paint film and the like.

It should be noted that the scope of the present invention is not limited by the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which are made without departing from the spirit and principle of the present invention should be construed as equivalents and included in the scope of the present invention.