CN1117495A - Tin methide Stabilizer, the prepn. thereof - Google Patents

Abstract

This invention relates to a prepn. method of a PVC heat stabilizer stannous methide di(isooctyl thioglycolate) and its raw material intermediate. This method is the one-step method. The mixture of metyl tin chloride as intermediate is dissolved in isooctyl thioglycolate, then it is neutralized to neutral with ammonia water. under the heat preservation reaction, static laying separation, water scrubbing and vacuum drying, finally the product is obtd. The intermediate is prepd. by the high-pressure one-step method. The catalyst is DMSO.

Description

Preparation of methyl tin stabilizer

The invention relates to the technical field of a process for preparing a PVC heat stabilizer dimethyltin bis (isooctyl thioglycolate) and a raw material intermediate.

There have been many patents on the use of organotin compounds as stabilizers forPVC resins, us Pat. 3222317, 3396185, etc., mainly butyl tin and octyl tin, because propyl tin has an odor and ethyl tin is toxic and substituted.

In the seventies, dimethyl tin bis (mercaptoacetic acid isopropyl ester) (TM-181) developed by M&T chemical companies in the United states is an efficient stabilizer for preparing PVC and PVC copolymers, the TM-181 has various characteristics and wide application, and the TM-181, PVC and other auxiliary agents have good solubility, can improve the transparency of products and can be used for blow molding. The TM-181 can reduce the melt viscosity and increase the fluidity when mixing PVC powder, and the dosage is between 0.1% and 0.5%.

The TM-181 processing characteristics are suitable for processing methods such as strict PVC processing, single-screw or double-screw extrusion molding, injection molding, blow molding, calendering and the like; while tin stabilizers for PVC are classified into three categories according to tin content: common type (16% -18% of tin content), high content type (23% -25% of tin content) and low content type (7% -8% of tin content), wherein the common type is most ideal.

As to the toxicity problem of methyltin, it has been reported according to the relevant information that the stabilizer dimethyltin dichloride used for intravenous injection in rabbits is less toxic than other dialkyltin dichlorides. Performing oral toxicity and skin eye irritation test with TM-181, wherein the oral toxicity (LD50) is 1102mg/kg body weight, and the basic skin toxicity index is 2.36; the values for dibutyltin bis (isooctyl thioglycolate) (TM-180) are 1037 and 2.36, respectively, and from the above data, it can be seen that TM-181 is less toxic than TM-180.

The stabilizer dimethyltin bis (isooctyl thioglycolate) is prepared by adding raw materials isooctyl thioglycolate, water, sodium bicarbonate and heptane (solvent) into a reactor, and dropwise adding an aqueous solution of dimethyltin dichloride to the reactor to react, as in U.S. Pat. No. 3810868, 3887519. And carrying out post-treatment on the reactant to obtain the stabilizer TM-181. The process is complicated, and a large amount of solvent is added; to recover the solvent, an investment in a solvent recovery apparatus is required, thereby increasing the production cost of the stabilizer.

In addition, the stabilizer TM-181 is prepared by using dimethyl tin oxide as a raw material, although the method is simpler than the method, the dimethyl tin oxide is expensive, the preparation process is complex, and the stabilizer TM-181 can be obtained through several steps of reactions.

The reaction formula is as follows:

the invention aims to simplify the process, improve the quality and yield of the final product to over 98 percent, and ensure that the content of trimethyl tin chloride impurity is not more than 0.6 percent; and the preparation method of the synthetic raw material intermediate is simple, the cost is reduced, and the yield is 99%.

The task of the invention is realized by the following technical scheme: mixing and dissolving a raw material intermediate methyltin chloride in a raw material isooctyl thioglycolate, dropwise adding ammonia water with the concentration ranging from 5-30% to ensure that the pH value is 7 to the neutral value,the reaction temperature is within the range of 30-80 ℃, and the reaction time is within 1-5 hours; the direct dissolution of the methyl tin chloride in the raw material isooctyl thioglycolate is completed in one step without adding any solvent, and the yield of the stabilizer dimethyltin bis (isooctyl thioglycolate) prepared by post-treatment of the reactant reaches more than 98 percent. The optimal process conditions of the invention are as follows: the reaction time is 2 hours, the reaction temperature is 50-60 ℃, and the concentration of liquid ammonia is 15%.

The method for preparing the mixture of the intermediate dimethyltin dichloride and the methyltin trichloride adopts DMSO as the catalyst, has simple technical process and a high-pressure one-step method, adds the metallic tin, the stannic chloride, the catalyst and the solvent into a high-pressure kettle, and completes the reaction by introducing the chloromethane once. The reaction time is short, the yield is 99 percent, and the content of trimethyl tin chloride is lower than 0.6 percent.

The ratio of the intermediate dimethyl tin dichloride and methyl tin trichloride of the raw materials prepared by the invention accords with the following formula: $\frac{n-m}{2m}(n>m)$

n represents the number of moles of tin, m represents the number of moles of tin tetrachloride, and n and m are adjusted to different ratios as necessary.

The stabilizers of the present invention include the structural formula:

(1) 60 to 90 percent of compound

(2) 4 to 40 percent of compound

CH₃-Sn·[S-(CH₂)_nCOOR]₃

(3) The content of the compound is not more than 0.6%

R represents C_1-20A hydrocarbon compound, n represents an integer of 1 to 3

The invention has the following positive effects: the performance comparison test of dimethyl tin bis (isooctyl thioglycolate) (TM-181) and dibutyl tin bis (isooctyl thioglycolate) (TM-180) shows that when the TM-181 is used in an amount of less than 20% of the TM-180, the TM-181 shows excellent processing stability. The key point is that the method has simple process, high product purity and yield and greatly reduced production cost.

The mixture of dimethyl tin dichloride and methyl tin trichloride as the raw material intermediates can replace the import. U.S. Pat. No. 3,351966,4129584 is a complex process using expensive and difficult-to-obtain catalyst, i.e., tetrabutyl phosphonium iodide and tetramethylene iodonium sulfide. The technical contents and applications of the present invention are described in detail by the following preferred embodiments:

preparation of stabilizer dimethyltin bis (isooctyl thioglycolate) method example 1 reaction formula:

100 g of a mixture of methyltin chlorides (dimethyltin dichloride: methyltin trichloride: 80: 20) was charged into a 500-ml three-necked flask with stirring,200 g of isooctyl thioglycolate was then added thereto, stirring was started to completely dissolve the methyltin chlorides, 15% ammonia water was slowly added dropwise thereto, the pH was controlled to neutral, the temperature was maintained at 40 to 50 ℃ until the dropwise addition was stopped (dropwise addition was carried out for about 50 minutes), the temperature was raised to 60 ℃ and the temperature was maintained for 1 hour, the reaction solution was placed in a separatory funnel, the mixture was allowed to stand and layer, the aqueous layer was removed, the lower organic layer was washed twice with water, the organic layer was reduced in vacuum, water was completely evaporated at a distillation dehydration temperature of about 105 ℃ (the degree of vacuum was 10mmHg), and then the mixture was filtered to obtain 237g of a transparent oily liquid. And (3) product analysis results:

tin content: 21.0%, sulfur content: 11.2%, refractive index (25 ℃): 1.5070,

specific gravity (25 ℃): 1.18 example 2 reaction scheme:

204 g (1.0 mol) of isooctyl thioglycolate and 82 g (0.5 mol) of dimethyltin oxide were put into a three-necked flask, heated to 100 ℃ and kept at this temperature for 1 hour, the reaction solution was allowed to stand for separation to remove the aqueous layer, the organic layer was washed with water, and the product was distilled under vacuum to dehydrate and dry to obtain 257.1 g of a transparent oily liquid product (yield 98%). And (3) product analysis results:

tin content: 21.3%, sulfur content: 11.8%, refractive index (25 ℃): 1.5051,

specific gravity (25 ℃): 1.15Example 3 reaction formula:

100 g of a mixture of 100 g of methyltin chloride is added into a 500ml three-necked flask, then 214 g of isooctyl mercaptopropionate is added, stirring is started to completely dissolve the methyltin chloride, 15% ammonia water is slowly dripped to control the pH value to be neutral, the dripping temperature is stopped (the dripping time is about 50 minutes), the temperature is kept between 40 and 50 ℃, then the temperature is heated to 60 ℃, the reaction is maintained for 1 hour under the temperature, and after the reaction is finished, the reaction liquid is treated by the same method as the method in the example 1 to obtain 241 g of a transparent oily liquid (the yield is 98%). And (3) product analysis results:

tin content: 20.1%, sulfur content: 10.9%, refractive index (25 ℃): 1.5052

Preparation of intermediate methyltin chloride example 4

Catalyst and process for preparing same

In a 500ml stainless steel autoclave with stirring, a mixture of 44.0 g of methyl tin chloride (as solvent), 118.7 g (1.0 mol) of tin powder, 260 g (1.0 mol) of tin tetrachloride and 3.2 g (0.052 mol) of catalyst were added, and then 34 g (2.65 mol) of methyl chloride was metered into the autoclave and heated to elevated temperature. When the temperature reached 100 ℃ the stirring was started and the temperature was slowly raised to 205 ℃ and maintained at this temperature for 1.5 to 2 hours until methyl chloride could not be consumed, the reaction pressure was reduced from the initial pressure of the reaction of 7MPa to 2MPa, after cooling to room temperature, excess methyl chloride was removed to give 268.2 g (yield 99%) of a white solid product with a melting point of 104 to 108 ℃ as a result of product analysis:

adding the catalyst according to the mixture of all methyl tin chloride

Theoretical value: cl34.63, S0.93, Sn51.32

Adding catalyst according to the total dimethyltin dichloride mixture

Measured value: cl34.1, S0.90, Sn51.37

Gas chromatography analysis results:

(CH₃)₂SnCl₂——79.1％

CH₃SnCl₃——20.5％

(CH₃)₃SnCl-0.5% comparative test formulation for Performance of stabilizer TM-181 and TM-180 of example 5:

100 portions of PVC

0.5 part of calcium stearate

The stabilizer is added according to the specification

Time (in minutes)

Parts 0153045607590 TM-1801.01444469 TM-1811.01222358 TM-1810.812235910

From the above table, it is clear that TM-181 is superior to TM-180 in initial coloring property even when used in a small amount. And (3) testing the processing stability:

100 portions of formula PVC

0.5 part of calcium stearate

Stabilizer see table stabilizer parts melting time maximum torque stabilization time minimum torque

(minute) Low level TM-1800.402.227003.71900

TM-1810.361.834255.61725 Medium TM-1800.603.824006.11600

TM-1810.531.739506.91725 high quantity TM-1800.801.532008.71600

TM-181 0.72 1.2 3850 9.0 1600

As can be seen from the above table, it is clearly superior to TM-180 in both processing stability and color stability during processing, also at low levels. TM-181 exhibited good processability, both in twin-screw extrusion and single-screw extrusion, even when it was used in an amount of 20% less than that of TM-180. Note: TM-180: dibutyltin bis (isooctyl thioglycolate)

TM-181: dimethyl tin bis (isooctyl thioglycolate)

Claims (4)

1. A method for preparing dimethyl tin bis (isooctyl thioglycolate) adopts a one-step method to prepare a PVC heat stabilizer, and is characterized in that: dissolving a mixture of raw material intermediate methyl tin chloride in isooctyl thioglycolate, dropwise adding ammonia water with the concentration of 5-30% to adjust the pH value to be neutral, wherein the reaction time is 1-5 hours, the reaction temperature is 30-80 ℃, the method is also finished in one step by directly dissolving the methyl tin chloride in the isooctyl thioglycolate raw material, and the yield of the thermal stabilizer dimethyl tin bis (isooctyl thioglycolate) is more than 98%.

2. The method of claim 1, wherein the dimethyl tin bis (isooctyl thioglycolate) is characterized by: the pH value of the middle point is 7 when ammonia water is added dropwise.

3. The method of claim 1 for preparing dimethyltin bis (isooctyl thioglycolate), wherein: after the reaction mixture methyl tin bis (isooctyl thioglycolate), standing, layering, washing and vacuum drying.

4. The method for preparing dimethyltin bis (isooctyl thioglycolate) as claimed in claim 1, wherein the intermediate dimethyltin dichloride and methyltin trichloride are prepared by mixing tin and tin tetrachloride in the solvent methyltin chloride, using Dimethylsulfone (DMSO) as catalyst, reacting at 150-250 ℃ for 1-8 hours under the pressure of 6.0-7.0MPa, adding the raw materials and catalyst into an autoclave, introducing methyl chloride, completing the reaction in one step, and the mixture ratio of the intermediate dimethyltin dichloride and methyltin trichloride is 80/20, the yield is more than 99%, and the trimethyl chloride is less than 0.6%.