阅读说明：本技术 一种脲醛亚甲基脲液体肥料的制备 (Preparation of urea formaldehyde methylene urea liquid fertilizer ) 是由 苗志伟 孙波 蔡岩 于 2019-11-08 设计创作，主要内容包括：本发明公开了一种脲醛液体缓释肥的制备方法,制备过程以尿素和甲醛水溶液为基本原料,分别与不同的胺类物质缩合,通过控制反应条件,可以制备得到不同类型的脲醛亚甲基脲聚合物,即液体缓释肥料。该制备方法便于控制聚合进行的程度以及产物中各种组分的含量,还可以根据不同作物生长期及需肥要求,制备不同组分含量即不同缓释期的专用水溶性脲醛液体肥。(The invention discloses a preparation method of urea formaldehyde liquid slow release fertilizer, which takes urea and formaldehyde aqueous solution as basic raw materials in the preparation process, respectively condenses with different amine substances, and urea formaldehyde methylene urea polymers of different types, namely the liquid slow release fertilizer, can be prepared by controlling the reaction conditions. The preparation method is convenient for controlling the degree of polymerization and the content of various components in the product, and can also be used for preparing the special water-soluble urea-formaldehyde liquid fertilizer with different component contents, namely different slow release periods according to the growth periods and fertilizer requirements of different crops.)

1. The invention discloses a preparation method of urea formaldehyde methylene urea liquid slow release fertilizer, which comprises the following steps of using urea and formaldehyde aqueous solution as basic raw materials, respectively condensing with different amine substances, and controlling reaction conditions to prepare urea formaldehyde polymers of different types to obtain the urea formaldehyde methylene urea liquid slow release fertilizer, wherein the reaction process is as follows:

wherein R can be C1-C6 alkyl, C1-C6 alkylol or hydrogen atom.

2. According to the claim 1, the preferable amine substance is ethanolamine, ethylamine, butanol amine, butylamine or ammonia water, and the specific structure is as follows:

3. the process of preparing urea formaldehyde liquid slow release fertilizer according to claims 1 and 2, comprising the steps of:

(1) mixing urea (U) and formaldehyde (F) according to a molar ratio of U to F of 0.2-1 to 1, adding an alkaline solution to adjust the pH of a system to 7.5-10.5, controlling the temperature of the system to be 20-110 ℃, and carrying out the next reaction after reacting for 1-3 h;

(2) after the reaction of the previous step is finished, adding a proper amount of amine substances (A) into the system, adjusting the molar ratio of the added materials to be 0.2-1: 0.2-1, adding an alkaline solution to adjust the pH of the system to be 7.5-10.5, controlling the temperature of the system to be 30-120 ℃, cooling the system to room temperature after the reaction is carried out for 0.5-3 h, and finishing the reaction to obtain the urea formaldehyde liquid fertilizer.

4. According to claim 3, the formaldehyde used in the preparation process can be polyformaldehyde or an aqueous formaldehyde solution, and the alkaline substance for adjusting the pH value can be triethylamine, borax, sodium bicarbonate, potassium bicarbonate, sodium carbonate or potassium carbonate.

5. According to the claims 1-4, the urea-formaldehyde polymer prepared by the method can be used as a liquid slow-release fertilizer, can be directly diluted for use, can be compounded with other trace elements for use, and can be applied to the fertilization requirements of different crops in the agricultural field.

The technical field is as follows:

the invention relates to a preparation method of urea formaldehyde methylene urea liquid fertilizer, which is a preparation method of slow release adjustable urea formaldehyde liquid fertilizer prepared by a multi-step method.

Background art:

in recent years, the fertilizer industry is developing vigorously in the directions of high concentration, compounding, liquidization and slow effect, and liquid fertilizers are going to be attractive in the market to form strong internal power requirements and continuously release green potential. In the past, the price of chemical fertilizers has once been increased, the planting cost of farmers is continuously increased, and in addition, excessive application of nitrogen fertilizers causes serious land acidification, thus not only influencing the output of cultivated land, but also destroying the ecological environment and causing great threat to the health and safety of human beings.

With the promotion of the large-scale land operation process, the agricultural production mode is changed, and the fertilizer industry is necessarily changed. The new technical achievement is filling new kinetic energy for the high-quality, high-efficiency and green development of modern agriculture. At present, China is in a development stage of greatly promoting 'water and fertilizer integration', and liquid fertilizer is the best choice for realizing the water and fertilizer integration.

Compared with the traditional liquid nitrogen fertilizer, the liquid slow-release nitrogen fertilizer has the advantages of high safety, quick absorption, long fertilizer effect duration, high utilization rate, easy combination, deep absorption, convenient mechanical application and the like, and has the advantages of high-efficiency slow release and stability and wide attention of the agricultural and financial field. In the attack and hardening period of chemical fertilizer transformation in China, the liquid slow-release nitrogen fertilizer meets the requirement of 'reduction and efficiency improvement' of the chemical fertilizer put forward in rural areas of agriculture at the time of the time, and has very important significance for guaranteeing the quality safety of agricultural products.

Urea-formaldehyde liquid fertilizers are based on the reaction between urea, formaldehyde and ammonia as the most predominant liquid slow-release nitrogen fertilizers. Such urea formaldehyde fertilizers are prepared to provide a more controlled (and sometimes also characterized as extended) release of the nitrogen source, thereby allowing the release of nitrogen from the fertilizer to more closely match the nitrogen demand profile of plant growth to reduce the nitrogen loss associated with the rapid release of the nitrogen source (e.g., urea, UAN solution).

Although the prior patents have provided various methods for preparing the slow-release urea formaldehyde liquid fertilizer, the application of the liquid fertilizer is gradually increased along with the development of agriculture, and the development of new preparation methods of the slow-release urea formaldehyde liquid fertilizer is still a hot spot in the development of new fertilizers.

The method for preparing the clear liquid urea formaldehyde liquid fertilizer in the prior patent is mainly a one-step method, and the reaction progress and the product structural components cannot be controlled, so that the development of a controllable method for preparing the clear liquid urea formaldehyde liquid fertilizer becomes the urgent need of the development of the fertilizer industry.

The invention content is as follows:

the urea reacts with formaldehyde and amine substances to prepare the clear urea formaldehyde liquid fertilizer, the main reaction is shown in figure 1, and the prepared urea formaldehyde liquid fertilizer mainly comprises excessive unreacted urea, urea formaldehyde methylene urea with different polymerization degrees and triazinone compounds. The nutrient release periods of the liquid urea formaldehyde methylene urea slow release fertilizer with different components are different, and the release period of the component with higher polymerization degree is longer. In the prior patents such as U.S. Pat. Nos. 4554005, 4599102, and 6632262, urea formaldehyde liquid fertilizer is prepared by one-step method, which has the main disadvantage that the composition of the product components and the content of each component cannot be controlled.

Preferred amine substances R-NH in the invention₂Is ethanolamine, ethylamine, butanol amine, butylamine or ammonia water, and has a specific structure shown in figure 2.

The invention aims to provide a preparation method of a urea formaldehyde methylene urea liquid fertilizer. The technical scheme adopted by the invention for solving the technical problem is that the preparation method comprises the following steps:

the first step reaction selects proper U: F (urea to formaldehyde) molar ratio, reaction conditions are controlled during the reaction, urea and formaldehyde are enabled to generate hydroxymethyl urea and dimethylol urea, different U: F and reaction conditions are different, the ratio of the two products can be adjusted according to different target products, and dimethylol urea is preferably synthesized.

After the first-step reaction is finished, adding amine substances to continue the second-step reaction, and controlling the urea formaldehyde condensate of the methylene urea with different polymerization degrees by controlling the proportion and the reaction conditions of the added amine substances, wherein the obtained product can be used as a urea formaldehyde methylene urea liquid fertilizer.

As described above, the reason for preparing the urea formaldehyde methylene urea liquid fertilizer through the multi-step reaction is to control the composition and content of each component in the target product, thereby controlling the release period of the liquid fertilizer, and the urea formaldehyde methylene urea liquid fertilizer with different polymerization states can be prepared by controlling the reaction conditions. The urea formaldehyde methylene urea liquid fertilizer has the advantages of controllable release period, no toxic action of urea on plant leaves and direct application to foliar fertilization.

The key point of the urea formaldehyde methylene urea liquid fertilizer prepared by the multi-step method is that the proportion of products such as methylol urea, triazinone compounds and the like in the products is controlled by controlling the reaction conditions such as the proportion of each reaction raw material, pH value, reaction temperature, reaction time and the like in the reaction. Thus obtaining urea formaldehyde liquid fertilizers with different slow release periods, namely preparing the special urea formaldehyde liquid fertilizer for crops according to the fertilizer requirement periods and the fertilizer requirement requirements of different crops.

The source of formaldehyde in the present invention may be in various forms, for example, paraformaldehyde, an aqueous formaldehyde solution or a urea-formaldehyde concentrate, etc., and formaldehyde may also be used in a gaseous form, any of which is suitable for the operational use in the present invention, and it is preferred to use an aqueous formaldehyde solution as the source of formaldehyde in the present invention.

The pH can be maintained at an appropriate value by adding an alkaline compound such as triethylamine, borax, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium carbonate, potassium carbonate, or the like.

In the first step, urea and formaldehyde are mixed according to the ratio of U to F of 0.2-1 to 1, the pH value is adjusted to 7.5-8.5, the temperature is 20-110 ℃, and the next reaction is carried out after the reaction is carried out for 1-3 h.

And secondly, adding a proper amount of amine substances, adjusting the molar ratio of the added materials to be 0.2-1: 0.2-1, adjusting the pH to be 7.5-10.5, reacting at the temperature of 30-120 ℃ for 0.5-3 h, and then carrying out the next reaction.

The pH value in the reaction process is controlled by adopting a pH adjusting and controlling method in the first step, the pH value can be kept the same as that in the first step, or can be changed, such as pH adjustment and the like, the reaction temperature can be kept unchanged or increased or decreased, the temperature increase and the pH adjustment are favorable for the generation of the triazinone compound, and the pH and the temperature adjustment are mainly adjusted according to a target product.

Compared with the prior art, the invention has the innovation points that: (1) the urea formaldehyde methylene urea liquid fertilizer is prepared by adopting a multi-step method, so that the reaction direction and the content of various components in the product are more conveniently controlled; (2) the special urea formaldehyde methylene urea liquid fertilizer with different component contents, namely different slow release periods, can be prepared according to the growth periods and fertilizer requirements of different crops.

Description of the drawings:

FIG. 1 is a reaction equation of urea with formaldehyde and amine species;

FIG. 2 is a preferred amine.

The specific implementation mode is as follows:

the following examples are further illustrative of the present invention, but the present invention is not limited to these examples.

Example 1:

in the first step, urea and formaldehyde are mixed according to the molar ratio of U to F of 0.2 to 1, 1M NaOH solution is added to adjust the pH value to 7.5-8.5, the temperature is 60 ℃, and the next reaction is carried out after 1h of reaction.

And secondly, adding a proper amount of ethanolamine, adjusting the molar ratio of the added materials to be 0.2: F: A to 0.2: 1: 0.2, adjusting the pH to 7.5-8.5 at the temperature of 60 ℃, and cooling to room temperature after reacting for 0.5h to finish the reaction.

Example 2:

in the first step, urea and formaldehyde are mixed according to the molar ratio of U to F of 0.5 to 1, 1M NaOH solution is added to adjust the pH value to be 8.5-9.0, the temperature is 80 ℃, and the next reaction is carried out after 2 hours of reaction.

And secondly, adding a proper amount of ethanolamine, enabling the molar ratio of the added materials to be U: F: A to be 0.5: 1: 0.5, adjusting the pH to be 8.5-9.0, controlling the temperature to be 80 ℃, and carrying out the next reaction after 2 hours of reaction.

And thirdly, adding a proper amount of formaldehyde to ensure that the molar ratio of the added materials is U to F to A is 0.5 to 1 to 0.5, adjusting the pH value to be 8.5-9.0 at the temperature of 80 ℃, and cooling to room temperature after reacting for 1h to finish the reaction.

Example 3:

in the first step, urea and formaldehyde are mixed according to the molar ratio of U to F of 1 to 1, 1M NaOH solution is added to adjust the pH value to be 9.5-10.5, the temperature is 100 ℃, and the next reaction is carried out after 3 hours of reaction.

And secondly, adding a proper amount of ethanolamine, wherein the molar ratio of the added materials is U: F: A is 1: 1, adjusting the pH value to be 9.5-10.5, controlling the temperature to be 100 ℃, and carrying out the next reaction after 3 hours of reaction.

And thirdly, adding a proper amount of formaldehyde to ensure that the molar ratio of the added materials is 1: 1, adjusting the pH value to be 9.5-10.5 at the temperature of 100 ℃, reacting for 2h, and cooling to room temperature to finish the reaction.

Example 4:

in the first step, urea and formaldehyde are mixed according to the molar ratio of U to F of 1 to 3, 1M NaOH solution is added to adjust the pH value to be 7.5-8.5, the temperature is 90 ℃, and the next reaction is carried out after 1h of reaction.

And secondly, adding a proper amount of ethanolamine, adjusting the molar ratio of the added materials to be 1: 3: 1 (U: F: A), adjusting the pH value to be 8.5-9.5, reacting at 100 ℃ for 3h, and cooling to room temperature to finish the reaction.

Example 5:

the reaction conditions were the same as in example 1 except that in the second reaction step, the ethanolamine was replaced with ammonia water of equal nitrogen quality.

Example 6:

the reaction conditions were the same as in example 3 except that after the second reaction, appropriate amount of formaldehyde was added to make U: F: A1: 3: 1, and the third reaction was continued at 95 ℃ and pHAnd (5) reacting for 0.5h, and cooling to room temperature to finish the reaction.

Example 7:

the reaction conditions were the same as in example 6 except that after the third reaction step, urea was added in an appropriate amount so that U: F: A was 2: 3: 1, and the fourth reaction step was continued at a reaction temperature of 95 ℃ and a pH of 1And (5) reacting for 0.5h, and cooling to room temperature to finish the reaction.

The quality standards of the urea formaldehyde methylene urea of the invention are shown in Table 1.

TABLE 1