Preparation Method of a Class of Binuclear Organotin and Its Application in Flexible Polyurethane Foam

Abstract

The present invention relates to the field of chemical engineering, involving organotin, and specifically to a preparation method of a class of binuclear organotin compounds and their application in polyurethane flexible foams. First, a preparation method of binuclear organotin is provided. This method uses inexpensive reagents, has a simple formula, is easy to operate, and at the same time, is green, safe, highly efficient and environmentally friendly, and is suitable for industrial production. The organotin synthesized by this method contains two tin atoms in the molecule, and the polycyclic fragments in the molecule increase the rigidity and stability of the molecule, effectively enhancing its activity and catalytic efficiency. This organotin can be used in the production of polyurethane flexible foams, and the various indicators of the obtained polyurethane flexible foams are higher than those of the polyurethane flexible foams produced by ordinary stannous octoate.

Description

Technical Field

[0001] The present invention relates to the chemical industry field, and more particularly to organotin compounds, specifically to a preparation method of a class of binuclear organotin compounds and their application in polyurethane flexible foams. Background Art

[0002] Organotin can be used as a heat stabilizer for many polymer materials, and it has relatively strong stability and weather resistance. The initial products of organotin are easy to color and are non-toxic and harmless. Currently, it stands out among numerous stabilizers in the world and has become the product with the widest range of uses. According to data statistics, the proportion of organotin consumed in the production of PVC heat stabilizers in developed European countries reaches 15%, while in the United States it accounts for 25%. Currently in the world, organotin is mainly applied to materials that require a certain hardness and transparency and can be used as a heat stabilizer. Among the thousands of organotin compounds, there are only more than a dozen basic structures in the types with extensive industrial uses. Organotin can also be used as a polyurethane catalyst and is widely applied to the production of products such as foams, coatings, elastomers, adhesives, and resins. Traditional stannous octoate Sn(EH)2 is used as a basic catalyst for the production of polyurethane foams, a catalyst for room temperature curing silicone rubbers, polyurethane rubbers, and polyurethane coatings. However, its chemical properties are unstable. After opening, it is extremely vulnerable to the influence of oxygen and moisture in the air, and oxidation and hydrolysis reactions occur, thereby leading to a decrease or even inactivation of the catalytic efficiency, affecting the quality and qualification rate of the final product.

[0003] The general formula of the organotin structure can be represented by R n SnY (4-n) wherein R represents an alkyl group. According to the type of Y, organotin can be divided into mercaptan-based organotin, maleic monoester-based organotin, and lauric acid-based organotin. Among them, mercaptan-based organotin refers to a class of organotin stabilizers when Y is a mercaptan or a thiophenol. Commonly seen ones include dimethyltin bis(lauryl mercaptide), dibutyltin bis(lauryl mercaptide), and di-n-octyl-bis-(2-ethylhexyl mercaptoacetate)tin. Currently, this type of mercaptan-based organotin has a relatively single structure and fewer varieties.

[0004] The present invention provides a class of binuclear mercaptan-based organotin through technological innovation. The molecules of this class of substances contain two tin atoms, enabling this class of tin reagents to exhibit excellent properties. Summary of the Invention

[0005] In order to overcome the defects existing in the above-mentioned prior art, the present invention provides a class of binuclear organotin with the following structure:

[0006]

[0007] In the above structure, R is selected from an alkyl group and an alkyl group with substituents; further, R is preferably selected from n-hexyl, n-heptyl, n-octyl, n-dodecyl, etc.;

[0008] Represents an organic structure containing 4 thiol units, such as:

[0009] wait.

[0010] The above-mentioned binuclear organotin stabilizer is synthesized by the following synthetic route:

[0011] first step:

[0012] Step 2: In the first step, tetrathiol is synthesized by using tetraol, p-toluenesulfonyl chloride, sodium trithiocarbonate and lithium aluminum hydride as raw materials; and in the second step, organotin is synthesized by using tetrathiol and dialkyltin dichloride as raw materials.

[0013] Furthermore, the synthesis steps are as follows: the first step is to add pyridine solvent to the reactor, and then add tetraol and p-toluenesulfonyl chloride in a molar ratio of 1: (4.0-5.0), react for 10-16 hours, add an appropriate amount of dilute hydrochloric acid, stir for ten minutes and filter, dissolve the obtained solid in DMF, add sodium trithiocarbonate, then reflux for 8-10 hours, cool to room temperature, add dilute hydrochloric acid, stir for ten minutes and filter, wash the filter cake with water, methanol and acetone in turn, dry the obtained solid and dissolve it in THF, cool to below 0 degrees, add lithium aluminum hydride in batches with stirring, react at room temperature for 6 hours after the addition, then cool to zero degrees, quench the reaction with dilute sodium hydroxide aqueous solution, extract with ethyl acetate, dry, concentrate and distill under reduced pressure to obtain tetrathiol.

[0014] In the second step, tetrathiol is dissolved in an appropriate amount of solvent, 4 to 5 times the molar amount of base is added, and after stirring for 1 hour, 2 times the molar amount of dialkyltin dichloride is added, and reflux reaction is carried out for 8 to 10 hours, and then diluted with water, extracted with ethyl acetate, dried, and concentrated to obtain organotin.

[0015] In another aspect, the organotin compound can be used to produce flexible polyurethane foam, characterized in that the organotin compound provided by the present invention replaces conventional stannous octoate as an organic catalyst for polyurethane foaming. A typical formulation comprises: 60-90 parts of a polyether polyol, 20-30 parts of castor oil, 3-5 parts of water, 0.20-0.30 parts of an amine catalyst, 0.10-0.20 parts of the organotin compound, 1.5-0.5 parts of an organosilicon surfactant, and 45-55 parts of an isocyanate. The flexible polyurethane foam produced using this formulation exhibits superior performance compared to conventional stannous octoate-based foams.

[0016] The beneficial effects of the present invention are:

[0017] The present invention provides a new organotin compound and its synthesis method. The organotin molecule contains two tin atoms, and the polycyclic fragment in the molecule increases the rigidity and stability of the molecule, effectively enhancing its activity and catalytic efficiency. Its synthesis method uses inexpensive reagents, has a simple formulation, and is convenient to operate. At the same time, it is green, safe, highly efficient, and environmentally friendly, and is suitable for industrial production. On the other hand, this organotin can be used in the production of flexible polyurethane foam, and the various indicators of the obtained flexible polyurethane foam are higher than those of the flexible polyurethane foam produced by ordinary stannous octoate. Detailed implementation mode

[0018] General synthesis steps of organotin stabilizer:

[0019] The first step:

[0020] The second step:

[0021] In the first step, 200 mL of solvent pyridine, tetraol (100 mmol), and p-toluenesulfonyl chloride (500 mmol) are added to a reactor. After reacting for 10 - 16 hours, 1 M hydrochloric acid (200 mL) is added, stirred for ten minutes, and then filtered. The obtained solid is dissolved in DMF, and sodium trithiocarbonate (250 mmol) is added. Then, after refluxing for 8 - 10 hours, it is cooled to room temperature, dilute hydrochloric acid is added, stirred for ten minutes, and then filtered. The filter cake is washed once with water (100 mL), methanol (100 mL), and acetone (100 mL) in sequence. The obtained solid is dried and then dissolved in THF (200 mL). It is cooled below 0 °C, and lithium aluminum hydride (300 mmol) is added portionwise with stirring. After adding, the reaction is carried out at room temperature for 6 hours. Subsequently, it is cooled to 0 °C, and the reaction is quenched with 1 M aqueous sodium hydroxide solution (200 mL). It is extracted with ethyl acetate, dried, concentrated, and distilled under reduced pressure to obtain tetra-thiol.

[0022] In the second step, the tetra-thiol obtained in the previous step is dissolved in acetonitrile (200 mL), potassium hydroxide (500 mmol) is added, and after stirring and reacting for 1 hour, dialkyldichlorotin (220 mmol) is added. After refluxing for 8 - 10 hours, it is diluted with water, extracted with ethyl acetate, dried, and concentrated to obtain organotin.

[0023] Example 1 (Synthesis of organotin 1):

[0024]

[0025] According to the general synthesis steps of organotin stabilizer, pentaerythritol is selected as the tetraol, and didodecyldichlorotin is selected as the dialkyldichlorotin to synthesize the corresponding organotin 1 with a yield of 82%. Anal.calcd for C 53 H 108S4Sn2: C, 57.29; H, 9.80; S, 11.54. Found: C, 57.02; H, 9.97; S, 11.23.

[0026] Example 2 (Synthesis of Organotin 2):

[0027]

[0028] First, using dicycloheptadiene as the raw material and referring to the method in the literature (J. Org. Chem. 1991, 56, 7022 - 7026), the two double bonds of dicycloheptadiene were simultaneously oxidized to obtain tetrol. Then, using this tetrol as the raw material and following the general synthesis procedure of organotin stabilizers, dioctyltin dichloride was selected as the dialkyltin dichloride to synthesize the corresponding organotin 2 with a yield of 85%. Anal. calcd for C 39 H 76 S4Sn2: C, 51.44; H, 8.41; S, 14.08; Found: C, 51.22; H, 8.14; S, 14.33.

[0029] Example 3 (Synthesis of Organotin 3):

[0030]

[0031] First, using dicyclopentadiene as the raw material and referring to the method in the literature (J. Org. Chem. 1991, 56, 7022 - 7026), the two double bonds of dicyclopentadiene were simultaneously oxidized to obtain tetrol. Then, using this tetrol as the raw material and following the general synthesis procedure of organotin stabilizers, dihexyltin dichloride was selected as the dialkyltin dichloride to synthesize the corresponding organotin 3 with a yield of 87%. Anal. calcd for C 34 H 64 S4Sn2: C, 48.70; H, 7.69; S, 15.29; Found: C, 48.53; H, 7.45; S, 15.02.

[0032] Example 4 (Synthesis of Organotin 4):

[0033]

[0034] First, using dicyclopentadiene as the raw material and referring to the method in the literature (J. Org. Chem. 1991, 56, 7022 - 7026), the two double bonds of dicyclopentadiene were simultaneously oxidized to obtain tetrol. Next, using this tetrol as a raw material, following the general synthetic procedure for organotin stabilizers, and selecting diheptyltin dichloride as the dialkyltin dichloride, the corresponding organotin 4 was synthesized with a yield of 81%. Anal. calcd for C 38 H 72 S4Sn2: C, 51.02; H, 8.11; S, 14.33; Found: C, 51.31; H, 8.23; S, 14.09.

[0035] Example 5 (Synthesis of Organotin 5):

[0036]

[0037] First, using dicycloheptadiene as a raw material, referring to the method in the literature (J. Org. Chem. 1991, 56, 7022 - 7026), the two double bonds of dicycloheptadiene were simultaneously oxidized to obtain a tetrol Next, using this tetrol as a raw material, following the general synthetic procedure for organotin stabilizers, and selecting didodecyltin dichloride as the dialkyltin dichloride, the corresponding organotin 5 was synthesized with a yield of 86%. Anal. calcd for C 55 H 108 S4Sn2: C, 58.20; H, 9.59; S, 11.30; Found: C, 58.75; H, 9.33; S, 11.53.

[0038] Example 6 (Synthesis of Organotin 6):

[0039]

[0040] First, using dicyclopentadiene as a raw material, referring to the method in the literature (J. Org. Chem. 1991, 56, 7022 - 7026), the two double bonds of dicyclopentadiene were simultaneously oxidized to obtain a tetrol Next, using this tetrol as a raw material, following the general synthetic procedure for organotin stabilizers, and selecting didodecyltin dichloride as the dialkyltin dichloride, the corresponding organotin 6 was synthesized with a yield of 81%. Anal. calcd for C 58 H 112 S4Sn2: C, 59.28; H, 9.61; S, 10.91; Found: C, 59.01; H, 9.39; S, 10.77.

[0041] Examples 7 - 12

[0042] A green and environmentally friendly polyurethane flexible foam produced using organotin and applied to automotive interior materials, by weight, its formula is: 60 - 90 parts of polyether polyol, 20 - 30 parts of castor oil, 3 - 5 parts of water, 0.20 - 0.30 parts of amine catalyst, 0.10 - 0.20 parts of organotin, 1.5 - 0.5 parts of silicone surfactant, 45 - 55 parts of isocyanate.

[0043] The prior art is a conventional 25 - density sponge formula. Organotin provides catalytic activity for the gel reaction of the sponge. Its formula is shown in Table 1.

[0044] Table 1 Formula Table

[0045]

[0046] A preparation method of a green and environmentally friendly polyurethane flexible foam produced using organotin and applied to automotive interior materials, comprising the following steps:

[0047] (1) Preparation of raw materials: Prepare the raw materials according to the formula. Among them, component A is a mixture of polyether polyol, castor oil, water, amine catalyst, organotin catalyst, and silicone surfactant in the formula amounts, and stirred for 30 - 50 s to make them fully mixed. Component B is a single isocyanate component;

[0048] (2) Mixing: Mix the component A and component B raw materials prepared in step (1). The raw material temperature is 27°C - 30°C, and the head is stirred at a speed of 6000 rpm for 6 - 8 s;

[0049] (3) Creaming: Quickly pour the mixture into a mold, and observe it changing from semi - transparent to fully turbid and white viscous liquid. The creaming time is 14 - 15 s;

[0050] (4) Gelling: Observe that the rising foam body stops growing and a large number of bubbles spit out from the surface. The gelling time is 135 s - 140 s. Description of raw material selection:

[0051] VORANOL 3010 is produced by The Dow Chemical Company in the United States. It is a glycerol - initiated polyoxypropylene ether with a functionality of 3, a hydroxyl value of 56 mgKOH / g, and a viscosity of 500 mPa*s. It is widely used in the production of polyurethane flexible foams.

[0052] The bio-based polyether AT-8020 is produced by Shanghai Maihao New Material Technology Co., Ltd. It is synthesized using green vegetable oil and is a green polyol that replaces part of the polyether. It can effectively promote the efficient utilization of green renewable resources. At the same time, it can increase the hardness of the sponge and is applicable to block soft foams, slow-rebound sponges, etc. Its hydroxyl value is 40mgKOH / g. By adding 20 - 30 parts of bio-based polyether to replace ordinary soft foam polyether polyol in production, the usage of fossil-source polyether polyol can be saved by 20 - 30%. However, bio-based polyethers generally have relatively low reaction activity and slow post-curing, resulting in poor physical properties of the finished product. By improving the catalytic activity of organotin, the post-curing reaction can be promoted, and the physical properties of the finished product can be enhanced, which can better reflect the unique properties of organotin catalysts in green and environmentally friendly polyurethane soft foams.

[0053] The amine catalyst AT-367 is produced by Shanghai Maihao New Material Technology Co., Ltd. It is a tertiary amine-based, low-odor, environmentally friendly polyurethane catalyst. It mainly promotes the foaming reaction by catalyzing the reaction of water and isocyanate to generate CO2 gas, thereby reducing the density of the foam body. Deionized water is prepared in the laboratory and is mainly used to react with NCO to generate CO2 to produce a foaming effect.

[0054] Stannous octoate T-9 is produced by Jiangsu Yak Science & Technology Co., Ltd. Its main component is stannous isooctoate, and it is a maturely applied tin-based catalyst.

[0055] The silicone surfactant BL-828LO is produced by Shanghai Maihao New Material Technology Co., Ltd. It is a surfactant with an allyl polyether-modified silicone main chain, featuring environmental protection, low odor, and low VOC. It is applicable to the production of green and environmentally friendly sponges and has a certain flame retardant effect. During the foaming process, it mainly plays the roles of emulsification, foam stabilization, and nucleation.

[0056] The isocyanate DESMODUR T80 is produced by Covestro Polymer (China) Co., Ltd. It is a toluene diisocyanate product, in which the ratio of 2,4 and 2,6 isomers is 80%:20%, and the NCO content is 48% - 48.2%. It is mainly used in the production of polyurethane soft foams.

[0057] In summary, by controlling the same feeding ratio and process conditions, the examples are screened and optimized.

[0058] The test results of the physical properties of the finished product are shown in Table 2.

[0059] Table 2 Physical Property Test Report of the Finished Product

[0060]

[0061]

[0062] It can be seen from the test report in Table 2 that the various indicators of the polyurethane flexible foam produced using the tin catalysts prepared in Examples 1-6 are higher than those of the polyurethane flexible foam produced using ordinary stannous octoate. The reason is that stannous octoate is prone to oxidation and hydrolysis, and the generated tin oxide cannot react with NCO. Therefore, the catalytic effect gradually weakens as the reaction progresses. For the tin catalysts synthesized in Examples 1-6, since each molecule contains two tin atoms and the polycyclic fragments in the molecule increase the molecular rigidity and stability, their activity and catalytic efficiency are effectively enhanced, and they can continuously catalyze the NCO-hydroxy reaction during the post-curing process. Due to different examples, the effective content and molecular weight of the synthesized tin catalysts are different, which leads to differences in the content of tin catalyzing the gel reaction, and thus differences in physical properties. Generally speaking, the performance of the tin catalyst in Example 3 is relatively excellent, and the effects of other examples have reached or exceeded the performance indicators of traditional stannous octoate.

[0063] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A method for preparing a binuclear organotin compound, the synthesis route of which is as follows: ， Among them, The first step is to synthesize tetrathiols using tetraol, p-toluenesulfonyl chloride, sodium trithiocarbonate, and lithium aluminum hydride as raw materials; the second step is to synthesize organotin using tetrathiols and dialkyldichlorotin as raw materials; wherein, R is selected from n-hexyl, n-heptyl, n-octyl, or n-dodecyl; selected from the following structures: , or .

2. The preparation method of a binuclear organotin according to claim 1, wherein, The synthesis steps are as follows: first, adding pyridine as a solvent to a reactor, then adding tetramer and p-toluenesulfonyl chloride in a molar ratio of 1:(4.0-5.0), reacting for 10-16 hours, adding an appropriate amount of dilute hydrochloric acid, stirring for ten minutes, and filtering, dissolving the resulting solid in DMF, adding sodium trithiocarbonate, and then refluxing for 8-10 hours, cooling to room temperature, adding dilute hydrochloric acid, stirring for ten minutes, and filtering, washing the filter cake once with water, methanol, and acetone, drying the resulting solid and dissolving it in THF, cooling to below 0 degrees, adding lithium aluminum hydride in batches with stirring, reacting at room temperature for 6 hours after the addition, then cooling to zero degrees, quenching the reaction with dilute sodium hydroxide aqueous solution, extracting with ethyl acetate, drying, concentrating, and distilling under reduced pressure to obtain tetramer; In the second step, tetrathiol is dissolved in an appropriate amount of solvent, 4 to 5 times the molar amount of base is added, and after stirring for 1 hour, 2 times the molar amount of dialkyltin dichloride is added, and reflux reaction is carried out for 8 to 10 hours, and then diluted with water, extracted with ethyl acetate, dried, and concentrated to obtain organotin.

3. Application of a binuclear organotin in the preparation of polyurethane flexible foam, characterized in that, The polyurethane soft foam is prepared using the binuclear organotin prepared according to any one of claims 1 to 2 as a catalyst.

4. A composition for producing flexible polyurethane foam, characterized in that, The components of the composition are, by weight, 60-90 parts of polyether polyol, 20-30 parts of castor oil, 3-5 parts of water, 0.20-0.30 parts of amine catalyst, 0.10-0.20 parts of binuclear organotin prepared according to any one of claims 1-2, 1.5-0.5 parts of organosilicon surfactant, and 45-55 parts of isocyanate.

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