The present invention claims priority under 35 U.S.C. 119(a-d) to CN 202110614323.X, filed Jun. 2, 2021.
The present invention relates to a technical field of envelope materials for controlled-release fertilizers, and more particularly to a sebacic acid by-product fatty acid polyester polyol for a polyurethane controlled-release fertilizer envelope, a preparation method thereof and an envelope.
Sebacic acid is a main raw material for nylon fibers. Chinese sebacic acid production accounts for about 90% of the world's total. Conventionally, Chinese preparation method uses castor oil as a raw material. Castor oil is prepared through hydrolysis, cracking, acidification and other steps, wherein a large number of by-products are produced. These by-products mainly contain fatty acids and their sodium soaps, as well as water, phenol and organic polymer components. Fatty acid is the main by-product in the production process of sebacic acid (referred to as decanoate), accounting for 60% of the production of sebacic acid. The by-product fatty acid is processed with high temperature cracking, the composition and properties thereof are fundamentally different from those of the original oil, including the addition of phenolic substances which are very harmful to the environment and the human body. Due to complex composition and difficult separation, such by-product is usually discarded. On the one hand, it causes environmental pollution. On the other hand, the valuable fatty acids contained in the by-product are not fully utilized, which is a great waste. The added value of fatty acids is very low, the price is also low. Furthermore, there is few market demands, leading to large backlog, which will cause a great burden on the production of the sebacic acid.
Conventionally, sebacic acid by-product fatty acid is mainly used to: synthesize lubricating grease, lubricants and surfactants; prepare biodiesel and soap; and even be discarded since the industrial value is low. However, there is almost no report on the synthesis of polyester polyol polyurethane controlled-release envelope material with the sebacic acid by-product fatty acid.
Chinese patent application CN 201210137099.0 disclosed a method for preparing polyester polyol from waste oil, which comprises steps of: mixing and reacting the waste oil, a catalyst and an initiator for 1-5 hours, and using a nitrogen or inert gas for protecting during reaction; heating to 100-300° C.; mixing a reaction product obtained by the above steps with phthalic anhydride for 5-10 hours, and using the nitrogen or inert gas for protecting during reaction, and heating to 100-300° C.; mixing a reaction product obtained by the above steps with sodium carbonate, and reacting for 1-3 hours; vacuuming and dehydrating during reaction, and heating to 100-150° C., until a vacuum degree is less than 0.08 MPa. Although this application can use waste oil to prepare polyester polyol, the method cannot be widely used due to the complicated and unstable composition of the waste oil, high production cost and complicated processes.
Chinese patent application CN 201310655152.0 disclosed a method for preparing a waste oil modified polyester polyol by using recycled alcohol and waste oil, which comprises steps of: putting low molecular polyol raw materials, waste oil and a catalyst into a polyester reactor, heating to 140-150° C., and reacting for 1-1.5 h; injecting N2, heating to 180-190° C., and reacting for 1.5-2 h; heating to 220-230° C. and keeping for 4-5 h; and then cooling to 120° C., stopping the nitrogen, vacuuming, and reacting for 1.5-2 h until a product moisture is ≤0.07; finally, cooling to below 75° C. and discharging. The method has a complicated process and unstable product performance, which is not suitable for popularization.
Chinese patent application CN 201610370195.8 disclosed a method for preparing castor oil polyester polyol and application thereof in controlled-release fertilizer, which comprises steps of: using castor oil as a raw material and small molecular alcohol as a modifier; preparing high hydroxyl value castor oil polyol through transesterification reaction under with a catalyst, and then using a polybasic acid or anhydride as a modifier to catalyze a condensation reaction, so as to obtain castor oil polyester polyol with a hydroxyl value of 200-350 mgKOH/g; using castor oil polyester polyol as a white material and isocyanate as a black material, and preparing an enveloped controlled-release fertilizer through an in-situ reaction. The method modifies castor oil to prepare polyester polyol, and further prepares the enveloped controlled-release fertilizer. However, the castor oil modification process is uncontrollable, and the price of the castor oil is relatively high, which increases the production cost.
In order to solve the above-mentioned problems and final novel application of sebacic acid by-product fatty acid, the present invention provides a sebacic acid by-product fatty acid polyester polyol for polyurethane controlled-release fertilizer envelope, as well as a preparation method and an application thereof. The polyester polyol prepared by the present invention is cross-linked with MDI on a surface of a fertilizer, so as to form a polyurethane controlled-release fertilizer envelope material, thereby providing a polyurethane controlled-release fertilizer. The present invention uses the sebacic acid by-product fatty acid as a raw material to synthesize the polyester polyol because the sebacic acid by-product fatty acid is low in price and low in cost, the prepared fertilizer has excellent envelope and controlled-release performance, product structure performance is stable, cost performance is high, and degradation performance is sufficient after being applied to soil. The present invention comprehensively uses the sebacic acid by-product.
Accordingly, in order to accomplish the above objects, the present invention provides technical solutions as follows.
First, the present invention provides a sebacic acid by-product fatty acid polyester polyol for a polyurethane controlled-release fertilizer envelope, comprising a polyester polyol synthesized by an esterification reaction with a sebacic acid by-product fatty acid as a raw material; wherein the sebacic acid by-product fatty acid is refined from a by-product produced during preparing a sebacic acid from a castor oil; the sebacic acid by-product fatty acid comprises, in weight percentage: a palmitic acid 15-25%, a stearic acid 10-16%, an oleic acid 45-57%, and a linoleic acid 12-28%.
Preferably:
Palmitic acid is also known as hexadecanoic acid, whose chemical formula is C16H32O2, is a saturated fatty acid.
Stearic acid, whose chemical formula is C18H36O2, is a saturated fatty acid.
Oleic acid, whose chemical formula is C18H34O2, is a monounsaturated fatty acid.
Linoleic acid, whose chemical formula is C18H32O2, is an unsaturated fatty acid.
Preferably:
The present invention also provides a method for preparing the sebacic acid by-product fatty acid polyester polyol, comprising steps of:
Preferably:
Preferably, the high temperature for hydrolyzing is 120-180° C.
Preferably, the sebacic acid by-product fatty acid comprises, in weight percentage: the palmitic acid 15-25%, the stearic acid 10-16%, the oleic acid 45-57%, and the linoleic acid 12-28%.
Preferably, the acid value of the sebacic acid by-product fatty acid is 200-220 mgKOH/g, and an iodine value is 60-80.
Preferably:
a phthalic acid
a phthalic anhydride
and an isophthalic acid
When the reactant uses terephthalic acid as a main molecular structure, one of molecular structural formulas of the synthesized sebacic acid by-product fatty acid polyester polyol is:
When the reactant uses phthalic acid or phthalic anhydride as the main molecular structure, one of the molecular structural formulas of the synthesized sebacic acid by-product fatty acid polyester polyol is:
When the reactant uses isophthalic acid as the main molecular structure, one of the molecular structural formulas of the synthesized sebacic acid by-product fatty acid polyester polyol is:
The preparation method provided by the present invention is relatively complicated, and main reactions principles are illustrated as follows:
Based on the above reaction principles, a molecular system of the sebacic acid by-product fatty acid polyester polyol prepared by the method provided of the present invention comprises a variety of compounds with the benzenedicarboxylic acid as a main molecular structure, and the compounds expressed by the above formulas (1) (2) and (3) are possible structures. It can be understood that other compounds with other structures may also involved, as long as such compounds are produced under rational reaction principles and adopt the benzenedicarboxylic acid as the main molecular structure.
Preferably, in the step (3), the catalyst is an esterification catalyst. Preferably, the esterification catalyst is any one of an organic titanate catalyst, an organic tin catalyst, calcium oxide, and zinc acetate. Preferably, the organic titanate catalyst is either isopropyl titanate or butyl titanate.
Preferably, an addition amount of the esterification catalyst is 0.1-0.5% of a total reactant mass.
The present invention also provides applications of the above sebacic acid by-product fatty acid polyester polyol or the polyester polyol prepared by the above method in the polyurethane controlled-release fertilizer envelope or the polyurethane controlled-release fertilizer.
The present invention also provides a polyurethane controlled-release fertilizer envelope, which is prepared by cross-linking the sebacic acid by-product fatty acid polyester polyol or the polyester polyol prepared by the above method with isocyanate. The isocyanate is selected from a group consisting of polymethylene polyphenyl polyisocyanate, toluene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate (MDI), liquefied MDI, isophorone diisocyanate, 1,6-hexylene diisocyanate (HDI), HDI trimer, trimethylhexamethylene diisocyanate, xylylene diisocyanate, and dimethyl biphenyl diisocyanate. MDI is preferred due to great price advantage and lower cost.
The present invention also provides a polyurethane controlled-release fertilizer, consisting of fertilizer particles and a polyurethane controlled-release fertilizer envelope on surfaces of the fertilizer particles. The polyurethane controlled-release fertilizer envelope is formed on the surfaces of the fertilizer particles by cross-linking the sebacic acid by-product fatty acid polyester polyol with isocyanate. The fertilizer particles may be common water-soluble elemental fertilizers such as: urea, ammonium sulfate, ammonium chloride, ammonium nitrate, monoammonium phosphate, diammonium phosphate, potassium chloride, potassium sulfate, potassium nitrate, magnesium sulfate, magnesium nitrate, zinc sulfate, copper sulfate and zinc chloride.
The present invention has at least the following beneficial effects:
Referring to accompanying embodiments, the present invention will be further illustrated. However, the following embodiments are provided for clearly describe the present invention, and not intended to be limiting.
First, the present invention provides a method from preparing a sebacic acid by-product fatty acid, comprising steps of: hydrolyzing a by-product (purchased from companies that use the castor oil to produce the sebacic acid) produced during preparing a sebacic acid form a castor oil at 120-180° C., distilling under a vacuum degree of −0.095-0.098 MPa, collecting distilled parts at 120-245° C., so as to obtain the sebacic acid by-product fatty acid.
According to test results, the sebacic acid by-product fatty acid comprises, in weight percentage: the palmitic acid 15-25%, the stearic acid 10-16%, the oleic acid 45-57%, and the linoleic acid 12-28%.
According to the test results, an acid value of the sebacic acid by-product fatty acid is 200-220 mgKOH/g, and an iodine value is 60-80.
I. The embodiment 2 provides a method for preparing the sebacic acid by-product fatty acid polyester polyol, comprising steps of:
II. According to a Chinese national standard GB/T12008.3-2009, a phthalic anhydride method is used for measurement. The polyester polyol prepared in the embodiment 2 has a hydroxyl value of 180.5 mgKOH/g and a viscosity of 15100 CPS/25° C.
I. The embodiment 3 provides a method for preparing a enveloped polyurethane controlled-release fertilizer with the polyester polyol synthesized in the embodiment 2, comprising steps of:
II. Test on controlled-release performance of the enveloped controlled-release fertilizer prepared in the embodiment 3
A nutrient release period of the enveloped controlled-release fertilizer was tested at 25° C. by a static water extraction method, which was expressed as the number of days required for a cumulative nutrient release rate to reach 80%.
The nutrient release period of the enveloped controlled-release fertilizer prepared in the embodiment 3 is 60 days.
In order to illustrate biodegradability, the envelope material in the embodiment 2 was accurately weighed and buried in 58° C.±2° C. soil. After 6 months, samples were collected and dried in vacuum for 24 hours after surface soil was cleaned. After weighing, a sample weight loss rate is 31.2%.
I. The embodiment 4 provides a method for preparing the sebacic acid by-product fatty acid polyester polyol, comprising steps of:
II. According to a Chinese national standard GB/T12008.3-2009, a phthalic anhydride method is used for measurement. The polyester polyol prepared in the embodiment 4 has a hydroxyl value of 207.3 mgKOH/g and a viscosity of 12300 CPS/25° C.
I. The embodiment 5 provides a method for preparing a enveloped polyurethane controlled-release fertilizer with the polyester polyol synthesized in the embodiment 4, comprising steps of:
II. Test on controlled-release performance of the enveloped controlled-release fertilizer prepared in the embodiment 5
A test method is the same as that of the embodiment 3.
A nutrient release period of the envelope controlled-release fertilizer prepared in the embodiment 5 is 60 days.
I. The embodiment 6 provides a method for preparing the sebacic acid by-product fatty acid polyester polyol, comprising steps of:
II. According to a Chinese national standard GB/T12008.3-2009, a phthalic anhydride method is used for measurement. The polyester polyol prepared in the embodiment 6 has a hydroxyl value of 266.9 mgKOH/g and a viscosity of 2860 CPS/25° C.
I. The embodiment 7 provides a method for preparing a enveloped polyurethane controlled-release fertilizer with the polyester polyol synthesized in the embodiment 6, comprising steps of:
II. Test on controlled-release performance of the enveloped controlled-release fertilizer prepared in the embodiment 7
A test method is the same as that of the embodiment 3.
A nutrient release period of the envelope controlled-release fertilizer prepared in the embodiment 7 is 90 days.
I. The embodiment 8 provides a method for preparing the sebacic acid by-product fatty acid polyester polyol, comprising steps of:
II. According to a Chinese national standard GB/T12008.3-2009, a phthalic anhydride method is used for measurement. The polyester polyol prepared in the embodiment 8 has a hydroxyl value of 347.6 mgKOH/g and a viscosity of 1760 CPS/25° C.
I. The embodiment 9 provides a method for preparing a enveloped polyurethane controlled-release fertilizer with the polyester polyol synthesized in the embodiment 8, comprising steps of:
II. Test on controlled-release performance of the enveloped controlled-release fertilizer prepared in the embodiment 9
A test method is the same as that of the embodiment 3.
A nutrient release period of the envelope controlled-release fertilizer prepared in the embodiment 9 is 90 days.
I. The embodiment 10 provides a method for preparing the sebacic acid by-product fatty acid polyester polyol, comprising steps of:
II. According to a Chinese national standard GB/T12008.3-2009, a phthalic anhydride method is used for measurement. The polyester polyol prepared in the embodiment 10 has a hydroxyl value of 277.5 mgKOH/g and a viscosity of 3530 CPS/25° C.
I. The embodiment 11 provides a method for preparing a enveloped polyurethane controlled-release fertilizer with the polyester polyol synthesized in the embodiment 10, comprising steps of:
II. Test on controlled-release performance of the enveloped controlled-release fertilizer prepared in the embodiment 11
A test method is the same as that of the embodiment 3.
A nutrient release period of the envelope controlled-release fertilizer prepared in the embodiment 11 is 120 days.
I. The embodiment 12 provides a method for preparing the sebacic acid by-product fatty acid polyester polyol, comprising steps of:
II. According to a Chinese national standard GB/T12008.3-2009, a phthalic anhydride method is used for measurement. The polyester polyol prepared in the embodiment 12 has a hydroxyl value of 181.4 mgKOH/g and a viscosity of 23500 CPS/25° C.
I. The embodiment 13 provides a method for preparing a enveloped polyurethane controlled-release fertilizer with the polyester polyol synthesized in the embodiment 12, comprising steps of:
II. Test on controlled-release performance of the enveloped controlled-release fertilizer prepared in the embodiment 13
A test method is the same as that of the embodiment 3.
A nutrient release period of the envelope controlled-release fertilizer prepared in the embodiment 13 is 150 days.
I. Sample: the enveloped polyurethane controlled-release fertilizer prepared in the embodiments 3, 5, 7, 9, 11 and 13.
The foregoing descriptions are only the embodiments of the present invention and are not intended to be limiting. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, the recorded technical solutions can be modified, or some of the technical features can be equivalently replaced. Such modification, equivalent replacement and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Number | Date | Country | Kind |
---|---|---|---|
202110614323.X | Jun 2021 | CN | national |
Number | Name | Date | Kind |
---|---|---|---|
2317668 | Cheetham | Apr 1943 | A |
Number | Date | Country | |
---|---|---|---|
20220153678 A1 | May 2022 | US |