Water-based self-extinction polyurethane and preparation method thereof

Abstract

The invention belongs to the technical field of polyurethane resin, and provides water-based self-extinction polyurethane and a preparation method thereof.The water-based self-extinction polyurethane is prepared from, by mass, 160-240 parts of long-chain dihydric alcohol; 50 to 80 parts of isocyanate; 1.4 to 2.8 parts of a hydrophilic chain extender; 4-12 parts of an amine chain extender; and 0.1 to 0.4 part of a catalyst. According to the water-based self-extinction polyurethane disclosed by the invention, the use amount of the hydrophilic chain extender in the raw materials is low, the acid value of the corresponding product is 3-6mgKOH / g, the water absorption rate of the resin can be obviously reduced due to the reduction of the acid value, and the water resistance of the resin is improved; the solid content of the water-based self-extinction polyurethane is high and can reach 50% or above, and space and cost can be saved in the aspects of storage and transportation.

Description

Technical Field

[0001] The present invention belongs to the technical field of waterborne polyurethane resins, and particularly relates to a waterborne self-extinguishing polyurethane and a preparation method thereof. Background Art

[0002] Traditional matting resins are prepared by dispersing a matting agent into a base material emulsion under the action of shear force, supplemented with auxiliaries having functions such as anti-settling and thickening; after film formation, a surface material with high roughness can be formed, so that light is diffusely reflected and scattered, achieving a matting effect. Common matting agents can be divided into two categories: organic matting agents and inorganic matting agents; organic matting agents mainly include metal soaps, waxes and tung oil; inorganic matting agents mainly include diatomaceous earth, kaolin, talcum powder and silicon dioxide. The above matting agents have obvious matting effects, but adding matting agents will cause problems such as increased brittleness of the coating, poor hand feeling, poor adhesion, easy fragmentation and peeling, poor polishing resistance, and low transparency of the coating film; at the same time, the components in the matting agent precipitate, resulting in poor storage stability and different glosses of the coating.

[0003] After the self-extinguishing waterborne polyurethane emulsion cures on the substrate surface through its latex particles with large particle size and high strength, a micro-nano rough surface is generated, enhancing the scattering and refraction of light, thereby achieving a matting effect. This method not only solves the defects brought by the use of traditional matting agents to the coating, but also has excellent emulsion stability. However, in the prior art, most self-extinguishing waterborne polyurethane emulsions have a low solid content (20%-40%), increasing the product packaging, storage and transportation costs; at the same time, the product has a high acid value, resulting in high water absorption and poor water resistance. Self-extinguishing waterborne polyurethanes with low acid value and high solid content (solid content ≥ 50%) have low water content, so the drying and film-forming time is shortened to some extent, and the production efficiency of high-solid-content waterborne polyurethanes is higher than that of low-solid-content waterborne polyurethanes, and the storage and transportation costs are low. At the same time, the low acid value can reduce the hydrophilic property of waterborne polyurethane and improve the product application performance. Therefore, the development of low acid value and high solid content of waterborne polyurethane has become a hot research topic in this field. Chinese Patent CN109206588A discloses a high-solid-content self-extinguishing waterborne polyurethane emulsion containing large particles, which achieves the effect of improving the degree of matting through the reaction of raw materials such as polyester polyol mixture, hydrophilic sulfonate oligomer diol, and diisocyanate, etc. However, the highest solid content of the polyurethane product obtained by this prior art is only 43.6%, and the improvement in hydrophilicity is not involved; it is difficult to balance the matting degree and solid content of polyurethane and improve multiple high-performance effects.

[0004] Based on this, exploring a waterborne polyurethane with high solid content, strong matting property, low acid value and strong operability has become an urgent problem to be solved in this field. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to improve the solid content of the aqueous polyurethane matting agent and reduce its hydrophilic property, overcome the deficiencies and defects mentioned in the above background art, and provide an aqueous self-matting polyurethane and a preparation method thereof.

[0006] To solve the above technical problems, the technical solution proposed by the present invention is as follows: An aqueous self-matting polyurethane, the raw materials of the aqueous self-matting polyurethane include the following components by mass: 160 - 240 parts of long-chain diol; 50 - 80 parts of isocyanate; 1.4 - 2.8 parts of hydrophilic chain extender; 4 - 12 parts of amine chain extender; 0.1 - 0.4 parts of catalyst. Preferably, the acid value of the aqueous self-matting polyurethane is 3 - 6 mgKOH / g, and the solid content is greater than or equal to 50%.

[0007] The aqueous self-matting polyurethane synthesized in this application has a low acid value and a high solid content. The reduction of the acid value can improve the water resistance and water absorption rate of the aqueous polyurethane, and improve the service life of the aqueous polyurethane. Preferably, the long-chain diol includes one or more of polytetrahydrofuran diol, polycarbonate diol, polyester diol or polyether diol, and the molecular weight of the long-chain diol is 1000 - 3000.

[0008] Preferably, the isocyanate includes 4,4'-dicyclohexylmethane diisocyanate.

[0009] The selection of isocyanate is the key to synthesizing polyurethane. 4,4'-dicyclohexylmethane diisocyanate is an aliphatic isocyanate with relatively regular structure. The resulting polyurethane has good yellowing resistance while strengthening the chain segment regularity of the resulting polyurethane, promoting the phase separation of the hard and soft segments in the polyurethane structure and the self-assembly of hydrophilic and hydrophobic units. The strengthening of phase separation can reduce the amount of hydrophilic units in the hydrophilic shell layer of the core-shell structure of the aqueous polyurethane, thereby reducing the amount of hydrophilic chain extender and reducing the acid value.

[0010] Preferably, the hydrophilic chain extender includes dimethylolpropionic acid and / or dimethylolbutyric acid.

[0011] Preferably, the catalyst includes dibutyltin dilaurate and / or organic bismuth catalyst; the amine chain extender includes ethylenediamine and / or hydroxyethyl ethylenediamine. When the amine chain extender is ethylenediamine, the addition amount is 4 - 7 parts, and when the amine chain extender is hydroxyethyl ethylenediamine, the addition amount is 6 - 12 parts.

[0012] Under the same technical concept, the present application also provides a preparation method of an aqueous self-matting polyurethane, including the following steps: (1) Mix 80 - 120 parts by mass of long-chain diol and 25 - 40 parts of isocyanate and stir. Add a catalyst at 50 - 70 °C, continue to heat up to 85 - 90 °C, and react for 1 - 4 h; add 0.7 - 1.4 parts of hydrophilic chain extender and react for 3 - 5 h; cool down to 30 - 50 °C, add 120 - 180 parts of deionized water for waterborne modification, and then add 2 - 6 parts of amine chain extender for chain extension to obtain a waterborne self-extinguishing polyurethane reaction solution with a solid content of 35 - 40%. (2) Mix 80 - 120 parts by mass of long-chain diol and 25 - 40 parts of isocyanate and stir. Add a catalyst at 50 - 70 °C, continue to heat up to 85 - 90 °C, and react for 1 - 4 h; add 0.7 - 1.4 parts of hydrophilic chain extender and react for 3 - 5 h; cool down to 30 - 50 °C, add 120 - 180 parts of the waterborne self-extinguishing polyurethane reaction solution with a solid content of 35 - 40% obtained in step (1) for waterborne modification, and add 2 - 6 parts of amine chain extender for chain extension to obtain waterborne self-extinguishing polyurethane.

[0013] It is very difficult to make a high-solid-content product for the self-extinguishing resin because its extinction principle is that the particle size of waterborne polyurethane is relatively large. When forming a film, the surface arrangement of large-particle-size particles forms an uneven surface, resulting in diffuse reflection and thus generating the effect; however, during the synthesis process of self-extinguishing waterborne polyurethane, after the formation of large particle sizes, there is a subsequent chain extension step, which further causes particle aggregation and an increase in particle size, easily leading to product sedimentation or gelation. Therefore, it is necessary to reduce the product concentration to control particle aggregation. The solid content of self-extinguishing waterborne polyurethane on the market is usually around 30%.

[0014] High-solid-content and low-acid-value waterborne self-extinguishing polyurethane is synthesized by a stepwise method. In the stepwise method, first, waterborne self-extinguishing polyurethane with a solid content of 35 - 40% is synthesized, then this waterborne self-extinguishing polyurethane is used to replace deionized water for waterborne modification, and finally chain extension is carried out to obtain high-solid-content and low-acid-value waterborne self-extinguishing polyurethane. The synthesis and chain extension link of waterborne polyurethane is a very important step in the polyurethane synthesis process. In this step, chain extension occurs both inside and between polyurethane particles. When the solid content of polyurethane is relatively high, the probability of collision between particles increases, thus increasing the probability of chain extension reaction between particles, increasing particle size, and even causing agglomeration; while using waterborne polyurethane that has already undergone chain extension as water to increase the solid content, since the added waterborne polyurethane particles have completed chain extension, their reaction activity is greatly reduced, and even if they collide with newly generated waterborne polyurethane particles, no inter-particle chain extension will occur. Moreover, the addition of chain-extended waterborne polyurethane can play a role in blocking particle collisions in the new system, reducing the chain extension reaction between newly formed polyurethane particles, thereby improving the stability of the system.

[0015] Therefore, in the second step of the two-step synthesis of the present application, water-based self-extinguishing polyurethane is used to replace deionized water for water-based treatment, which can well improve the dispersibility of the system, avoid agglomeration in the chain extension step, and achieve the technical goal of improving the solid content of water-based self-extinguishing polyurethane through two-step synthesis.

[0016] Preferably, the long-chain diol in steps (1) and (2) is dehydrated before stirring.

[0017] Preferably, the catalyst in steps (1) and (2) is added in an amount of 0.05 - 0.2 parts by mass, and the addition amounts of the long-chain diol, isocyanate, hydrophilic chain extender, amine chain extender, and catalyst in steps (1) and (2) are kept consistent.

[0018] When the addition amounts of the raw materials in steps (1) and (2) are kept consistent, the particle size distribution of the water-based self-extinguishing polyurethane obtained is narrower.

[0019] Preferably, before water-based treatment in steps (1) and (2), a neutralizing amine is added for neutralization, and the deionized water or the water-based self-extinguishing polyurethane reaction solution with a solid content of 35 - 40% is cooled to 1 - 5 °C in advance; more preferably, the neutralizing amine is triethylamine. The added neutralizing amine can fully react with the carboxyl groups in the polyurethane to ensure the water solubility of the resin during water-based treatment.

[0020] Preferably, the chain extension in steps (1) and (2) is specifically as follows: dispersion, adding an amine chain extender and reacting at room temperature for 20 - 40 min, heating to 40 - 60 °C for curing for 1 - 3 h, and filtering and discharging.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention provides a water-based self-extinguishing polyurethane with a low dosage of hydrophilic chain extender in the raw materials. The corresponding product has an acid value of 3 - 6 mgKOH / g. The reduction of the acid value can significantly reduce the water absorption rate of the resin and improve the water resistance of the resin; the water-based self-extinguishing polyurethane has a high solid content, which can reach 50% or more, saving space and cost in storage and transportation. (2) The production efficiency of the present invention is high. Through a step-by-step synthesis method, first, a water-based self-extinguishing polyurethane with a solid content of 35 - 40% is synthesized, then this water-based self-extinguishing polyurethane is used to replace deionized water for water-based treatment, and then chain extension is carried out to obtain a high-solid-content and low-acid-value water-based self-extinguishing polyurethane; the water-based self-extinguishing polyurethane replaces deionized water for water-based treatment, which can well improve the dispersibility of the system, avoid agglomeration in the chain extension step, achieve the technical goal of improving the solid content of water-based self-extinguishing polyurethane through two-step synthesis, and improve the synthesis efficiency. Description of the Drawings

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0023] Figure 1 It is a comparison chart of the water absorption rates of the waterborne self-extinguishing polyurethane in Embodiment 1 of the present invention and a conventional matting agent; Figure 2 It is a physical diagram before and after water absorption of the waterborne self-extinguishing polyurethane in Embodiment 1 of the present invention and a conventional matting agent. Specific Embodiments

[0024] To facilitate the understanding of the present invention, the following will describe the present invention more comprehensively and meticulously in conjunction with the accompanying drawings of the specification and the preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.

[0025] Unless otherwise defined, all the professional terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention.

[0026] Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the present invention can be obtained through market purchases or can be prepared by existing methods.

[0027] Embodiment 1 This embodiment provides a waterborne self-extinguishing polyurethane, and the raw materials are as follows by mass: 200 g of polytetrahydrofuran diol; 70.4 g of 4,4-dicyclohexylmethane diisocyanate; 2.4 g of dimethylolethyl propionic acid; 6 g of ethylenediamine; 0.2 g of dibutyltin dilaurate ; 1.8 g of triethylamine; The acid value of the waterborne self-extinguishing polyurethane is 3.65 mgKOH / g, and the solid content is 50.5%.

[0028] The preparation method of the waterborne self-extinguishing polyurethane in this embodiment includes the following steps: (1) Put 100 g of polytetrahydrofuran diol into a reaction flask, evacuate to remove moisture at 120 °C for 2 h, cool down to 60 °C, add 35.2 g of HDMI (4,4-dicyclohexylmethane diisocyanate), stir evenly, then add 0.1 g of dibutyltin dilaurate as a catalyst. Wait for natural temperature rise and control the temperature below 90 °C. After the natural temperature rise ends, keep the temperature at 85 °C and react for 4 h. Add 1.2 g of dimethylethanolpropionic acid and react for 4 h until the NCO value is less than 4.7%. Cool down to 30 - 50 °C, then add 0.9 g of triethylamine for neutralization. Use 150 g of ice water at 5 °C for waterborne treatment. After good dispersion, in an ice bath, use a mixed solution of 3 g of ethylenediamine and 50 g of ice water for chain extension. After reacting at room temperature for 30 min, cure at 40 - 60 °C for 2 h, filter and discharge to obtain a waterborne self-extinguishing polyurethane reaction solution with a solid content of 36.2 wt%. (2) Put 100 parts of polytetrahydrofuran diol into a reaction flask, evacuate to remove moisture at 120 °C for 2 h, cool down to 60 °C, add 35.2 g of HDMI (4,4-dicyclohexylmethane diisocyanate), stir evenly, then add 0.1 g of dibutyltin dilaurate as a catalyst. Wait for natural temperature rise and control the temperature below 90 °C. After the natural temperature rise ends, keep the temperature at 85 °C and react for 4 h. Add 1.2 g of dimethylethanolpropionic acid and react for 4 h until the NCO value is less than 4.7%. Cool down to 30 - 50 °C, then add 0.9 g of triethylamine for neutralization. Disperse with 150 g of a waterborne self-extinguishing polyurethane reaction solution with a solid content of 36.2 wt% that has been pre-cooled to 5 °C. After good dispersion, in an ice bath, use a mixed solution of 3 g of ethylenediamine and 50 g of ice water for chain extension. After reacting at room temperature for 30 min, cure at 40 - 60 °C for 2 h, filter and discharge to obtain a waterborne self-extinguishing polyurethane with a solid content of 50.5 wt% and a solid content acid value of 3.65 mgKOH / g.

[0029] Example 2 This example provides a waterborne self-extinguishing polyurethane, and the raw materials are as follows by mass parts: 200 g of polytetrahydrofuran diol; 66 g of 4,4-dicyclohexylmethane diisocyanate; 3 g of dimethylethanolbutyric acid; 5.2 g of ethylenediamine; 0.3 g of dibutyltin dilaurate; 2.2 g of triethylamine; The acid value of the waterborne self-extinguishing polyurethane is 4.6 mgKOH / g, and the solid content is 52.5%.

[0030] The preparation method of the waterborne self-extinguishing polyurethane in this example includes the following steps: (1) Put 100 g of polytetrahydrofuran diol into a reaction flask, evacuate under vacuum at 120 °C for 2 h to remove moisture, cool down to 60 °C, add 33 g of HDMI (4,4-dicyclohexylmethane diisocyanate), stir evenly, then add 0.15 g of dibutyltin dilaurate as a catalyst. Wait for natural temperature rise and control the temperature below 90 °C. After the natural temperature rise ends, keep the temperature at 85 °C and react for 4 h. Add 1.5 g of dihydroxyethyl propionic acid and react for 4 h until the NCO value is less than 4%. Cool down to 30 - 50 °C, then add 1.1 g of triethylamine for neutralization, disperse with 120 g of ice water at 5 °C. After good dispersion, in an ice-water bath, use a mixed solution of 2.6 g of ethylenediamine and 50 g of ice water for chain extension. Then react at room temperature for 30 min, cure at 40 - 60 °C for 2 h, filter and discharge to obtain an aqueous self-extinguishing polyurethane reaction solution with a solid content of 39 wt%. (2) Put 100 g of polytetrahydrofuran diol into a reaction flask, evacuate under vacuum at 120 °C for 2 h to remove moisture, cool down to 60 °C, add 33 g of HDMI (4,4-dicyclohexylmethane diisocyanate), stir evenly, then add 0.15 g of dibutyltin dilaurate as a catalyst. Wait for natural temperature rise and control the temperature below 90 °C. After the natural temperature rise ends, keep the temperature at 85 °C and react for 4 h. Add 1.5 g of dihydroxyethyl propionic acid and react for 4 h until the NCO value is less than 4%. Cool down to 30 - 50 °C, then add 1.1 g of triethylamine for neutralization, and disperse with 120 g of an aqueous self-extinguishing polyurethane reaction solution with a solid content of 39 wt% that has been pre-cooled to 5 °C. After good dispersion, in an ice-water bath, use a mixed solution of 2.6 g of ethylenediamine and 50 g of ice water for chain extension. Then react at room temperature for 30 min, cure at 40 - 60 °C for 2 h, filter and discharge to obtain an aqueous self-extinguishing polyurethane with a solid content of 52.5 wt% and an acid value of 4.6 mgKOH / g.

[0031] Example 3 This example provides an aqueous self-extinguishing polyurethane, and the raw materials are as follows by mass: 200 g of polytetrahydrofuran diol; 66 g of 4,4-dicyclohexylmethane diisocyanate; 3 g of dihydroxyethyl butyric acid; 5.2 g of ethylenediamine; 0.4 g of organic bismuth catalyst; 2 g of triethylamine; The acid value of the aqueous self-extinguishing polyurethane is 4.18 mgKOH / g, and the solid content is 52.5%.

[0032] The preparation method of the aqueous self-extinguishing polyurethane in this example includes the following steps: (1) Put 100 g of polytetrahydrofuran diol into a reaction flask, evacuate to remove moisture at 120 °C for 2 h, cool down to 60 °C, add 33 g of HDMI (4,4-dicyclohexylmethane diisocyanate), stir evenly, then add 0.2 g of organobismuth catalyst, wait for natural temperature rise, and control the temperature below 90 °C. After the natural temperature rise ends, keep the temperature at 85 °C and react for 4 h, add 1.5 g of dihydroxyethyl propionic acid, react for 4 h until the NCO value is less than 4%, cool down to 30 - 50 °C, then add 1 g of triethylamine for neutralization, and disperse with 120 g of ice water at 5 °C. After good dispersion, carry out chain extension in an ice bath with a mixed solution of 2.6 g of ethylenediamine and 50 g of ice water, then react at room temperature for 30 min, cure at 40 - 60 °C for 2 h, filter and discharge to obtain an aqueous self-extinguishing polyurethane reaction solution with a solid content of 39 wt%. (2) Put 100 g of polytetrahydrofuran diol into a reaction flask, evacuate to remove moisture at 120 °C for 2 h, cool down to 60 °C, add 33 g of HDMI (4,4-dicyclohexylmethane diisocyanate), stir evenly, then add 0.2 g of organobismuth catalyst, wait for natural temperature rise, and control the temperature below 90 °C. After the natural temperature rise ends, keep the temperature at 85 °C and react for 4 h, add 1.5 g of dihydroxyethyl propionic acid, react for 4 h until the NCO value is less than 4%, cool down to 30 - 50 °C, then add 1 g of triethylamine for neutralization, and disperse with 120 g of an aqueous self-extinguishing polyurethane reaction solution with a solid content of 39 wt% that has been pre-cooled to 5 °C. After good dispersion, carry out chain extension in an ice bath with a mixed solution of 2.6 g of ethylenediamine and 50 g of ice water, then react at room temperature for 30 min, cure at 40 - 60 °C for 2 h, filter and discharge to obtain an aqueous self-extinguishing polyurethane with a solid content of 52.5 wt% and an acid value of 4.18 mgKOH / g.

[0033] Example 4 This example provides an aqueous self-extinguishing polyurethane, and the raw materials are as follows by mass: 200 g of polytetrahydrofuran diol; 62 g of 4,4-dicyclohexylmethane diisocyanate; 2.8 g of dihydroxyethyl butyric acid; 6 g of ethylenediamine; 0.2 g of dibutyltin dilaurate; 2 g of triethylamine; The acid value of the aqueous self-extinguishing polyurethane is 4.38 mgKOH / g, and the solid content is 57.2%.

[0034] The preparation method of the aqueous self-extinguishing polyurethane in this example includes the following steps: (1) Put 100 g of polytetrahydrofuran diol into a reaction flask, evacuate for 2 h at 120 °C to remove moisture, cool down to 60 °C, add 31 g of HDMI (4,4 - dicyclohexylmethane diisocyanate), after stirring evenly, add 0.1 g of dibutyltin dilaurate as a catalyst, wait for natural temperature rise, and control the temperature below 90 °C. After the natural temperature rise ends, keep the temperature at 85 °C and react for 4 h, add 1.4 g of dimethylethanolpropionic acid, react for 4 h until the NCO value is less than 4%, cool down to 30 - 50 °C, then add 1 g of triethylamine for neutralization, and disperse with 150 g of ice water at 5 °C. After good dispersion, carry out chain extension in an ice - water bath with a mixed solution of 3 g of ethylenediamine and 50 g of ice water, then react at room temperature for 30 min, and cure at 40 - 60 °C for 2 h, filter and discharge to obtain an aqueous self - extinction polyurethane reaction solution with a solid content of 35.5 wt%; (2) Put 100 g of polytetrahydrofuran diol into a reaction flask, evacuate for 2 h at 120 °C to remove moisture, cool down to 60 °C, add 31 g of HDMI (4,4 - dicyclohexylmethane diisocyanate), after stirring evenly, add 0.1 g of dibutyltin dilaurate as a catalyst, wait for natural temperature rise, and control the temperature below 90 °C. After the natural temperature rise ends, keep the temperature at 85 - 90 °C and react for 4 h, add 1.4 g of dimethylethanolpropionic acid, react for 4 h until the NCO value is less than 4%, cool down to 30 - 50 °C, then add 1 g of triethylamine for neutralization, and disperse with 160 g of an aqueous self - extinction polyurethane reaction solution with a solid content of 35.5 wt% which has been pre - cooled to 5 °C. After good dispersion, react at room temperature for 30 min, then cure at 40 - 60 °C for 2 h, filter and discharge to obtain an aqueous self - extinction polyurethane with a solid content of 57.2 wt% and an acid value of 4.38 mgKOH / g.

[0035] Comparative Example 1 Commercially available matting agent, product name: Huigu Chemical WPU - 2327.

[0036] Comparative Example 2 Synthesize aqueous self - extinction polyurethane by ordinary methods.

[0037] Put 100 g of polytetrahydrofuran diol into a reaction flask, evacuate the air at 120 °C for 2 h to remove moisture, cool down to 60 °C, add 35.2 g of HDMI (4,4-dicyclohexylmethane diisocyanate), 1.2 g of dihydroxyethyl propionic acid, stir evenly, add the catalyst dibutyltin dilaurate, wait for natural temperature rise, and control the temperature below 95 °C. After the natural temperature rise ends, keep the temperature at 85 - 90 °C and react for 5 hours until the NCO value is less than 4.7%, add 0.9 g of neutralizing amine for neutralization, and disperse with 150 g of ice water at 5 °C. After good dispersion, carry out chain extension in an ice-water bath with a mixed solution of 3 g of ethylenediamine and 50 g of ice water, react at room temperature for 30 min, then cure at 40 - 60 °C for 2 h, filter and discharge to obtain a waterborne self-extinguishing resin with a solid content of 36.2 wt%.

[0038] Comparative Example 3 Put 100 g of polytetrahydrofuran diol into a reaction flask, evacuate the air at 120 °C for 2 h to remove moisture, cool down to 60 °C, add 35.2 g of IPDI (isophorone diisocyanate), stir evenly, add 0.1 g of the catalyst dibutyltin dilaurate, wait for natural temperature rise, and control the temperature below 90 °C. After the natural temperature rise ends, keep the temperature at 85 - 90 °C and react for 4 h, add 3 g of dihydroxyethyl propionic acid, react for 4 h until the NCO value is less than 4.7%, cool down to 30 - 50 °C, add 0.9 g of triethylamine for neutralization, and disperse with 160 g of ice water at 5 °C. After good dispersion, carry out chain extension in an ice-water bath with a mixed solution of 3.8 g of ethylenediamine and 50 g of ice water, react at room temperature for 30 min, then cure at 40 - 60 °C for 2 h, filter and discharge to obtain a waterborne self-extinguishing polyurethane with a solid content of 35.4 wt%.

[0039] Put 100 g of polytetrahydrofuran diol into a reaction flask, evacuate the air at 120 °C for 2 h to remove moisture, cool down to 60 °C, add 35.2 g of IPDI (isophorone diisocyanate), stir evenly, add 0.1 g of the catalyst dibutyltin dilaurate, wait for natural temperature rise, and control the temperature below 90 °C. After the natural temperature rise ends, keep the temperature at 85 - 90 °C and react for 4 h, add 3 g of dihydroxyethyl propionic acid, react for 4 h until the NCO value is less than 4.7%, cool down to 30 - 50 °C, add 0.9 g of triethylamine for neutralization, and disperse with 160 g of a reaction solution of waterborne self-extinguishing polyurethane with a solid content of 35.4 wt% that has been pre-cooled to 5 °C. After good dispersion, carry out chain extension in an ice-water bath with a mixed solution of 3.8 g of ethylenediamine and 50 g of ice water, react at room temperature for 30 min, then cure at 40 - 60 °C for 2 h, filter and discharge to obtain a waterborne self-extinguishing polyurethane with a solid content of 49.2 wt%.

[0040] Perform performance tests on the waterborne self-extinguishing polyurethanes obtained in Examples 1 - 4 and Comparative Examples 1 - 3, and the test data are shown in Table 1 below. Figure 1Water absorption rate comparison chart of the matting agents in Example 1 and Comparative Example 1; it can be clearly seen from the figure that the water absorption performance of the waterborne self-matting polyurethane of the Example product is significantly better than that of Comparative Example 1. Figure 2 Physical pictures of the waterborne self-matting polyurethane of Example 1 of the present invention before and after water absorption and those of a conventional matting agent. It can be seen that Comparative Example 1 becomes significantly white after water absorption, while the appearance of the product of Example 1 has no obvious change before and after water absorption. By comparing Example 1-4 with Comparative Example 2-3, it can be seen that the two-step synthesis method using 4,4-dicyclohexylmethane diisocyanate has obvious advantages in terms of solid content and acid value of the obtained waterborne polyurethane, thereby obtaining a self-matting waterborne polyurethane with high solid content and low acid value.

[0041] Table 1 shows the comparison of the solid content, acid value, gloss and water absorption rate of the waterborne self-matting polyurethanes obtained in Examples 1-4 and Comparative Examples 1-3

Claims

1. A waterborne self - dulling polyurethane, characterized in that, The raw materials of the aqueous self - extinction polyurethane include the following components by mass parts: 160 - 240 parts of long - chain diol; 50 - 80 parts of isocyanate; 1.4 - 2.8 parts of hydrophilic chain extender; 4 - 12 parts of amine chain extender; 0.1 - 0.4 parts of catalyst.

2. The waterborne self - matting polyurethane according to claim 1, characterized in that, The acid value of the aqueous self - extinction polyurethane is 3 - 6mgKOH / g, and the solid content is greater than or equal to 50%.

3. The waterborne self-extinguishing polyurethane according to claim 1, wherein The long - chain diol includes one or more of polytetrahydrofuran diol, polycarbonate diol, polyester diol or polyether diol, and the molecular weight of the long - chain diol is 1000 - 3000.

4. The waterborne self - extinction polyurethane according to claim 1, characterized in that, The isocyanate includes 4,4 - dicyclohexylmethane diisocyanate.

5. The waterborne self-extinguishing polyurethane according to claim 1, characterized in that The hydrophilic chain extender includes dimethylolpropionic acid and / or dimethylolbutyric acid.

6. The aqueous self - extinction polyurethane according to claim 1, characterized in that, The catalyst includes dibutyltin dilaurate and / or organic bismuth catalyst; the amine chain extender includes ethylenediamine and / or hydroxyethyl ethylenediamine. When the amine chain extender is ethylenediamine, the addition amount is 4 - 7 parts, and when the amine chain extender is hydroxyethyl ethylenediamine, the addition amount is 6 - 12 parts.

7. A preparation method of a waterborne self - matting polyurethane, characterized in that, It includes the following steps: (1) Mix and stir 80 - 120 parts of long - chain diol and 25 - 40 parts of isocyanate by mass. Add the catalyst at 50 - 70°C, continue to heat up to 85 - 90°C, and react for 1 - 4h; add 0.7 - 1.4 parts of hydrophilic chain extender and react for 3 - 5h; cool down to 30 - 50°C, add 120 - 180 parts of deionized water for water - based treatment, and then add 2 - 6 parts of amine chain extender for chain extension to obtain an aqueous self - extinction polyurethane reaction solution with a solid content of 35 - 40%; (2) Mix and stir 80 - 120 parts of long - chain diol and 25 - 40 parts of isocyanate by mass. Add the catalyst at 50 - 70°C, continue to heat up to 85 - 90°C, and react for 1 - 4h; add 0.7 - 1.4 parts of hydrophilic chain extender and react for 3 - 5h; cool down to 30 - 50°C, add 120 - 180 parts of the aqueous self - extinction polyurethane reaction solution with a solid content of 35 - 40% obtained in step (1) for water - based treatment, and add 2 - 6 parts of amine chain extender for chain extension to obtain the aqueous self - extinction polyurethane.

8. The preparation method according to claim 7, characterized in that, In steps (1) and (2), the addition amount of the catalyst by mass parts is 0.05 - 0.2 parts, and the addition amounts of the long - chain diol, isocyanate, hydrophilic chain extender, amine chain extender and catalyst in steps (1) and (2) are the same.

9. The preparation method according to claim 7, characterized in that, Before water - based treatment in steps (1) and (2), add neutralizing amine, and cool the deionized water or the aqueous self - extinction polyurethane reaction solution with a solid content of 35 - 40% to 1 - 5°C in advance.

10. The preparation method according to claim 7, characterized in that, The chain extension in steps (1) and (2) is specifically: disperse, add the amine chain extender and react at room temperature for 20 - 40min, heat up to 40 - 60°C for curing for 1 - 3h, and then filter and discharge.

Images