阅读说明：本技术 复合阻燃剂、添加型单组份阻燃水性聚氨酯及其制备方法 (Composite flame retardant, additive type single-component flame-retardant waterborne polyurethane and preparation method thereof ) 是由 田志雄 祝世杰 陈婕敏 叶丹阳 金凤 孟喜 杨羽南 郑萍 于 2021-08-20 设计创作，主要内容包括：本发明公开了一种复合阻燃剂、添加型单组份阻燃水性聚氨酯及其制备方法,使用复合阻燃剂与硅溶胶的搭配,对单组份水性聚氨酯进行阻燃改性研究,能改善对材料固有力学性能影响大、相容性差等缺点,同时赋予了水性聚氨酯良好的阻燃性能；制备方法具有实施简易、原料易得等优点,条件温和、步骤简单,适合实验室和工业生产应用。(The invention discloses a composite flame retardant, additive single-component flame-retardant waterborne polyurethane and a preparation method thereof, wherein the flame-retardant modification research is carried out on the single-component waterborne polyurethane by using the matching of the composite flame retardant and silica sol, so that the defects of large influence on the inherent mechanical property of materials, poor compatibility and the like can be improved, and the waterborne polyurethane is endowed with good flame-retardant property; the preparation method has the advantages of simple implementation, easily obtained raw materials and the like, is mild in condition and simple in steps, and is suitable for laboratories and industrial production.)

1. The composite flame retardant is characterized by comprising aluminum hypophosphite AHP, ammonium polyphosphate APP, melamine polyphosphate MPP, melamine cyanurate MCA and magnesium hydroxide Mg (OH)₂Calcium hydroxide Ca (OH)₂Aluminum hydroxide ATH, zinc borate, zinc oxide, fumed silica, or talc.

2. The composite flame retardant of claim 1, which is a mixture of ammonium polyphosphate APP, melamine polyphosphate MPP, aluminum hydroxide ATH and zinc borate.

3. The composite flame retardant according to claim 2, wherein the composite flame retardant comprises the following components in parts by mass: melamine polyphosphate MPP: aluminum hydroxide ATH: 3-6% of zinc borate: 3-6: 1-2: 1 to 2.

4. The composite flame retardant of claim 2, wherein the ammonium polyphosphate APP is of type II structure, and the degree of polymerization is greater than 1000.

5. An additive type single-component flame-retardant waterborne polyurethane is characterized by being prepared from the following raw materials in parts by mass:

the composite flame retardant is one of the composite flame retardants of claims 1 to 4.

6. The additive type single-component flame-retardant waterborne polyurethane as claimed in claim 5, wherein SiO in the silica sol₂The mass fraction of (A) is 20-40%; the thickener is one of alkyl ammonium salt, gelatin or sodium carboxymethylcellulose; the film-forming assistant is one of propylene glycol, propylene glycol butyl ether, dodecyl alcohol ester or N, N-dimethylformamide DMF.

7. The additive type single-component flame-retardant waterborne polyurethane as claimed in claim 6, wherein SiO in the silica sol₂The mass fraction of (A) is 20% + -2%.

8. The additive type single-component flame-retardant waterborne polyurethane as claimed in claim 6, wherein the film-forming assistant is N, N-dimethylformamide DMF; the thickening agent is sodium carboxymethyl cellulose.

9. The preparation method of the additive type single-component flame-retardant waterborne polyurethane as claimed in any one of claims 5 to 8, wherein the method comprises the following steps:

(1) dispersing the composite flame retardant into deionized water;

(2) adding single-component waterborne polyurethane into the product obtained in the step (1), and uniformly mixing;

(3) and (3) sequentially adding silica sol, a thickening agent solution and a film-forming aid into the product obtained in the step (2), and fully mixing to obtain the single-component flame-retardant waterborne polyurethane.

10. The preparation method of the additive-type single-component flame-retardant waterborne polyurethane as claimed in claim 9, wherein in the step (3), the mass part ratio of the thickener to the deionized water in the thickener solution is 1-2: 10-30.

Technical Field

The invention belongs to the technical field of polyurethane modification, and particularly relates to a composite flame retardant, additive type single-component flame-retardant waterborne polyurethane and a preparation method thereof.

Background

The waterborne polyurethane takes water as a dispersing agent to replace an organic solvent in the traditional polyurethane coating, has a series of advantages of no toxicity, environmental protection, easy storage and the like, and has excellent mechanical strength and modulus, so that the waterborne polyurethane can be widely used in the fields of coating, adhesive, leather processing and the like. But the waterborne polyurethane has the defects of no high temperature resistance, flammability, large combustion smoke quantity and the like, so that potential safety hazards and limitation exist in the use process of the waterborne polyurethane. The development of waterborne polyurethanes with flame retardant properties is a problem that is urgently sought to be solved.

The method of adding modified waterborne polyurethane can be called blending modification, and is to physically disperse the flame retardant in the waterborne polyurethane so that the polyurethane emulsion adsorbs and coats the flame retardant, thereby imparting the flame retardant property to the waterborne polyurethane. The addition type modification method is simple to implement, has strong operability and is suitable for modification of various in-situ waterborne polyurethanes. At present, the most widely used additive flame retardant is a halogen flame retardant, but the halogen flame retardant has great harm to the environment, generates toxic smog and gas in the combustion process and is not beneficial to human health. Since 3/1/2021, the european union has prohibited the use of halogen-based flame retardants in all electronic displays, television cabinets and housings, and halogen-free flame retardants have become the mainstream products in the market.

In patent CN 108395513, phosphate is used as a flame retardant to obtain a flame-retardant aqueous polyurethane resin with good film-forming properties, but the phosphate flame retardant used therein has a variety of types, high price, and large usage amount (35% -50% is needed), and has certain difficulty in practical application and industrial production. In patent CN110343413, the aqueous polyurethane coating can achieve better flame retardant effect only by a small amount of prepared nitrogen and phosphorus intumescent flame retardant, but the process for preparing the nitrogen and phosphorus intumescent flame retardant in the method is complex, has higher requirement, is not easy to implement, and is difficult to apply in actual production. The nitrogen-phosphorus intumescent flame retardant has the characteristics of high flame retardant efficiency, low toxicity, no corrosiveness and the like, gives consideration to the flame retardant effect of the nitrogen-phosphorus flame retardant, and acid, carbon layer and gas generated when heated can cooperate to form an intumescent thermal insulation layer to effectively prevent combustion from continuing. However, most additive flame retardants have a large influence on the inherent mechanical properties of the material, and particularly, the emulsion breaking and sedimentation can be caused by the direct addition of the single-component waterborne polyurethane, and the flame retardants are very easy to precipitate at the bottom in the drying process. Therefore, it is especially important to develop a high-efficiency intumescent flame retardant formula with small influence on the inherent mechanical property of the waterborne polyurethane and good compatibility.

Disclosure of Invention

The invention aims to overcome the defects and provides the composite flame retardant, the additive single-component flame-retardant waterborne polyurethane and the preparation method thereof, the composite flame retardant and the silica sol are matched to carry out flame-retardant modification research on the single-component waterborne polyurethane, so that the defects of large influence on the inherent mechanical property of the material, poor compatibility and the like can be improved, and meanwhile, the waterborne polyurethane is endowed with good flame-retardant property; the preparation method has the advantages of simple implementation, easily obtained raw materials and the like, is mild in condition and simple in steps, and is suitable for laboratories and industrial production.

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

a composite flame retardant is prepared from aluminium hypophosphite AHP, ammonium polyphosphate APP, melamine polyphosphate MPP, melamine cyanurate MCA, magnesium hydroxide Mg (OH)₂Calcium hydroxide Ca (OH)₂Aluminum hydroxide ATH, zinc borate, zinc oxide, fumed silica, orA mixture of two or more of talc.

Further, the composite flame retardant is a mixture of ammonium polyphosphate APP, melamine polyphosphate MPP, aluminum hydroxide ATH and zinc borate.

Further, the composite flame retardant comprises the following components in parts by mass: melamine polyphosphate MPP: aluminum hydroxide ATH: 3-6% of zinc borate: 3-6: 1-2: 1 to 2.

Further, the ammonium polyphosphate APP is of a II-type structure, and the polymerization degree is greater than 1000.

An additive type single-component flame-retardant waterborne polyurethane is prepared from the following raw materials in parts by mass:

the composite flame retardant is the composite flame retardant.

Further, in the additive type single-component flame-retardant waterborne polyurethane, SiO in the silica sol₂The mass fraction of (A) is 20-40%; the thickener is one of alkyl ammonium salt, gelatin or sodium carboxymethylcellulose; the film-forming assistant is one of propylene glycol, propylene glycol butyl ether, dodecyl alcohol ester or N, N-dimethylformamide DMF.

Further, in the additive type single-component flame-retardant waterborne polyurethane, SiO in the silica sol₂The mass fraction of (A) is 20% + -2%.

Further, in the additive type single-component flame-retardant waterborne polyurethane, the film-forming aid is N, N-dimethylformamide DMF; the thickening agent is sodium carboxymethyl cellulose.

The preparation method of the additive type single-component flame-retardant waterborne polyurethane comprises the following steps:

(1) dispersing the composite flame retardant into deionized water;

(2) adding single-component waterborne polyurethane into the product obtained in the step (1), and uniformly mixing;

(3) and (3) sequentially adding silica sol, a thickening agent solution and a film-forming aid into the product obtained in the step (2), and fully mixing to obtain the single-component flame-retardant waterborne polyurethane.

Further, in the preparation method of the additive type single-component flame-retardant waterborne polyurethane, in the step (3), the mass part ratio of the thickening agent to deionized water in the thickening agent solution is 1-2: 10-30.

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

(1) the invention designs a composite flame retardant formula for the additive single-component flame-retardant waterborne polyurethane for the first time, and the preferred scheme is that APP, MPP, ATH and zinc borate are mixed to form a composite flame retardant which has good compatibility with the waterborne polyurethane;

(2) the invention designs a formula of additive single-component flame-retardant waterborne polyurethane, and the flame-retardant modification research is carried out on the single-component waterborne polyurethane by matching the composite flame retardant and the silica sol, so that the flame-retardant property of the waterborne polyurethane is greatly improved, the product reaches the flame-retardant grade in the vertical combustion grade, the limit oxygen index is close to the flame-retardant grade, and the use requirement is met; meanwhile, the additive flame retardant, especially the inorganic flame retardant, can influence the accumulation mode of polyurethane molecular chains, so that the reduction of the comprehensive mechanical property of the waterborne polyurethane is inevitably caused, the composite flame retardant has good compatibility with the waterborne polyurethane, and can slightly influence the inherent mechanical property of the waterborne polyurethane when being used together with silica sol, a thickening agent and the like, so that the tensile strength and the elongation at break of the waterborne polyurethane are kept well, and the normal use of the flame-retardant waterborne polyurethane is ensured;

(3) in the formula of the additive type single-component flame-retardant waterborne polyurethane, the used flame retardant and other materials are large products in the market, and the additive type single-component flame-retardant waterborne polyurethane is low in price and easy to obtain;

(4) in the formula of the additive type single-component flame-retardant waterborne polyurethane, the silica sol and the flame-retardant formula are matched for use, so that the emulsion can be stabilized, the flame-retardant waterborne polyurethane obtained by the method is basically free from layering within 30 days in a closed container, and the prepared 3mm sample plate is free from cracking, settling and other phenomena;

(5) the additive type single-component flame-retardant waterborne polyurethane can generate an expanded carbon layer to cover the surface of a material in the combustion process, has excellent flame-retardant property, and can better ensure the original mechanical property of the waterborne polyurethane material; the flame-retardant waterborne polyurethane has high flame-retardant efficiency, good mechanical property and environmental protection;

(6) the preparation method of the additive-type single-component flame-retardant waterborne polyurethane is simple, can be directly added into finished waterborne polyurethane or prepolymer, and has the advantages of safe and efficient preparation process, no toxicity or pollution, safe and controllable process and green environmental protection idea compounding; mild condition, simple steps and suitability for laboratory and industrial production.

Detailed Description

The features and advantages of the present invention will become more apparent and appreciated from the following detailed description of the invention.

The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

The invention discloses a preparation method of a high-efficiency intumescent flame retardant formula, aiming at the problems of large addition amount of a flame retardant, poor compatibility and the like in the prior art, the method has the advantages of simplicity and easiness in implementation, easiness in obtaining raw materials and the like, when the flame retardant formula is applied to flame retardant modification of single-component waterborne polyurethane, the defects of large influence on inherent mechanical properties of materials, poor compatibility and the like can be improved, and meanwhile, the waterborne polyurethane is endowed with good flame retardant property.

The invention relates to an additive type single-component flame-retardant waterborne polyurethane which is prepared from the following raw materials in parts by mass: 30-50 parts of composite flame retardant (preferably, APP, MPP, ATH and zinc borate are mixed according to the proportion of 3-6: 3-6: 1-2: 1-2), 80-100 parts of single-component waterborne polyurethane, 50-80 parts of deionized water, 5-10 parts of silica sol, 1-2 parts of thickener and 1-2 parts of film forming additive.

The preparation method comprises the following steps:

(1) aluminum hypophosphite AHP, ammonium polyphosphate APP, melamine polyphosphate MPP, melamine cyanurate MCA, magnesium hydroxide Mg (OH)₂Calcium hydroxide Ca (OH)₂Aluminum hydroxide ATH, zinc borate, zinc oxide, fumed silica, or talc, preferably, APP, MPP, ATH, zinc borate are mixed in a ratio of 3 to 6: 3-6: 1-2: 1-2, and fully and uniformly mixing to obtain a composite intumescent flame retardant formula;

(2) adding 30-50 parts of deionized water into 30-50 parts of the composite flame retardant, and fully stirring for 10-15min to obtain a thick paste flame retardant, wherein the flame retardant can be fully dispersed in the waterborne polyurethane so as to avoid the solid agglomeration phenomenon;

(3) then adding 80-100 parts of single-component waterborne polyurethane into the mixed flame retardant, and stirring for 20-30 min;

(4) adding 5-10 parts of silica sol into the product obtained in the last step, and fully mixing for 20-30 min; and (2) completely dissolving 1-2 parts of thickening agent in 20-30 parts of deionized water, adding the solution, mixing and stirring for 20-30min, adding 1-2 parts of film-forming aid, and fully and uniformly mixing to obtain the flame-retardant waterborne polyurethane emulsion, wherein the solid content of the flame-retardant waterborne polyurethane obtained by the method is 30-50%.

Compared with other methods, the preparation method of the additive-type single-component flame-retardant waterborne polyurethane provided by the invention has the advantages that the raw materials are cheap and easy to obtain, the implementation is convenient and simple, the process is safe and controllable, and the prepared flame-retardant waterborne polyurethane has high flame-retardant efficiency, good mechanical property and environmental friendliness.

In the following examples, the particle size range of the solid powder flame retardant used is 5-60um, which is commercially available; the single-component waterborne polyurethane is 1624 type product produced by Shenzhen Jitian chemical industry, and the solid content of the single-component waterborne polyurethane is (38 +/-5)%, but the single-component waterborne polyurethane is not limited to the waterborne polyurethane; the silica sol used is self-made in a laboratory, the solid content of the silica sol is (20 +/-2)%, the silica sol is light white transparent liquid, and the additives in the following examples are calculated according to the mass part of the solid content.

Example 1

In this embodiment, a preparation method of the additive-type single-component flame-retardant waterborne polyurethane is as follows:

(1)30 parts of composite flame retardant (APP, MPP, ATH and zinc borate in a ratio of 3: 6: 2: 1) are fully and uniformly mixed, 30 parts of deionized water is added, and stirring is carried out for 10 min;

(2) then adding 80 parts of waterborne polyurethane, and stirring for 20 min;

(3) adding 5 parts of silica sol into the product obtained in the step (2), and fully mixing for 20 min; and (2) completely dissolving 1 part of sodium carboxymethylcellulose in 20 parts of deionized water, adding the solution, mixing and stirring for 20min, adding 1 part of film-forming aid, and fully and uniformly mixing to obtain the flame-retardant waterborne polyurethane emulsion.

Example 2

In this embodiment, a preparation method of the additive-type single-component flame-retardant waterborne polyurethane is as follows:

(1) fully and uniformly mixing 35 parts of composite flame retardant (APP, MPP, ATH and zinc borate in a ratio of 4: 6: 1: 2), adding 30 parts of deionized water, and stirring for 12 min;

(2) then adding 80 parts of waterborne polyurethane, and stirring for 20 min;

(3) adding 7 parts of silica sol into the product obtained in the step (2), and fully mixing for 20 min; and (2) completely dissolving 1 part of sodium carboxymethylcellulose in 20 parts of deionized water, adding the solution, mixing and stirring for 20min, adding 1 part of film-forming aid, and fully and uniformly mixing to obtain the flame-retardant waterborne polyurethane emulsion.

Example 3

In this embodiment, a preparation method of the additive-type single-component flame-retardant waterborne polyurethane is as follows:

(1)40 parts of composite flame retardant (APP, MPP, ATH and zinc borate in a ratio of 3: 5: 1: 1) are fully and uniformly mixed, 40 parts of deionized water is added, and stirring is carried out for 15 min;

(2) then adding 90 parts of waterborne polyurethane, and stirring for 20 min;

(3) adding 8 parts of silica sol into the product obtained in the step (2), and fully mixing for 20 min; and (2) completely dissolving 1.5 parts of sodium carboxymethylcellulose in 20 parts of deionized water, adding the solution into the solution, mixing and stirring for 25min, adding 1.5 parts of film-forming aid into the solution, and fully and uniformly mixing to obtain the flame-retardant waterborne polyurethane emulsion.

Example 4

In this embodiment, a preparation method of the additive-type single-component flame-retardant waterborne polyurethane is as follows:

(1)50 parts of composite flame retardant (APP, MPP, ATH and zinc borate in a ratio of 5: 6: 2: 1) are fully and uniformly mixed, 40 parts of deionized water is added, and stirring is carried out for 15 min;

(2) then adding 100 parts of waterborne polyurethane, and stirring for 30 min;

(3) adding 10 parts of silica sol into the product obtained in the step (2), and fully mixing for 20 min; and (2) completely dissolving 2 parts of sodium carboxymethylcellulose in 30 parts of deionized water, adding the solution, mixing and stirring for 30min, adding 2 parts of film-forming aid, and fully and uniformly mixing to obtain the flame-retardant waterborne polyurethane emulsion.

Comparative example 1:

the comparative example was pure waterborne polyurethane without any addition.

And (3) performance testing:

the method is mainly used for testing the flame retardant grade, the limited oxygen index, the glow wire temperature, the tensile strength and the elongation at break of a sample.

And placing the prepared polyurethane in a standard sample plate, drying and molding, and preparing a standard sample strip according to the test standard. The flame retardant rating was evaluated using a horizontal/vertical combustion tester (Nanjing Jiangning analytical instruments, Inc., CZF-5CD50W) using the UL94(Underwriters Laboratories Inc) standard in the same manner as GB/T2408-2008; evaluating the limit oxygen index by using a limit oxygen index tester (Nanjing Jiangning analytical instrument, Inc., JF-5) according to GB/T2406.2-2009 standard; using a glowing filament tester (Nanjing Jiangning analysis instrument Co., Ltd., ZRS-2) to evaluate the glowing filament temperature by adopting the GB/T5169.10-2017 standard; tensile strength and elongation at break of the material were evaluated using a tensile testing apparatus (WB 9000B, Weibang instruments, Inc., of Dongguan) using the GB/T1040-92 standard.

The test results are shown in table 1:

TABLE 1 test results of products obtained in examples 1 to 4 and comparative example

The curing mode of the single-component waterborne polyurethane is solvent volatilization curing, and during the curing, polyurethane macromolecular chains are wound and stacked, and interaction force is generated among molecules to endow the waterborne polyurethane with mechanical properties. Pure waterborne polyurethane samples are essentially non-flame retardant, with a large amount of melt dripping and smoke associated with the combustion process.

The test results in the table show that after the composite flame retardant is used for carrying out flame retardant modification on the single-component waterborne polyurethane, the flame retardant property of the waterborne polyurethane is greatly improved, the flame retardant can reach the flame-retardant level in the vertical combustion level, the limited oxygen index is close to the flame-retardant level, and the use requirement is basically met. The composite flame retardant disclosed by the invention has good compatibility with the waterborne polyurethane, can slightly influence the inherent mechanical property of the waterborne polyurethane when being used together with silica sol, a thickening agent and the like, so that the tensile strength and the elongation at break of the waterborne polyurethane are kept well, and the normal use of the flame-retardant waterborne polyurethane is ensured.

In conclusion, when the composite intumescent flame retardant formula introduced by the invention is used together with silica sol and the like, the waterborne polyurethane can be endowed with good flame retardant property, the good mechanical property of the waterborne polyurethane is ensured, and the additive type single-component flame retardant waterborne polyurethane disclosed by the invention has excellent performance.

The invention has been described in detail with reference to specific embodiments and illustrative examples, but the description is not intended to be construed in a limiting sense. Those skilled in the art will appreciate that various equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its embodiments without departing from the spirit and scope of the present invention, which fall within the scope of the present invention. The scope of the invention is defined by the appended claims.

Those skilled in the art will appreciate that those matters not described in detail in the present specification are well known in the art.