RU2809258C2 - Ester with low content of free 2-mercaptoethanol and its application - Google Patents

Abstract

FIELD: polyvinyl chloride (PVC) stabilizers.

SUBSTANCE: use of an ester obtained by the reaction of 2-mercaptoethanol with a C₁₆-C₁₈ fatty acid, with a low content of free 2-mercaptoethanol for stabilization of polyvinyl chloride, as well as to improve the thermal characteristics of the resulting stabilizers based on reverse alkyl tin ester or stabilizers based on alkyl tin thioglycolate or alkyltin mercaptides is proposed. Embodiments of the method for producing a PVC stabilizer and embodiments of a composition for stabilizing PVC are also proposed.

EFFECT: proposed application makes it possible to reduce odor during PVC compounding, its processing, as well as in the final PVC products.

28 cl, 13 tbl

Description

INVENTOR: ROSS, Kevin, John, US citizen, Rockwood, Ontario, CA; NORRIS, Gene, Kelly, US citizen, West Chester, OH, US; and DUNLAP, Jeremy, US citizen, Walton, KY, US.

PATENTENT HOLDER: PMC Organometallix, Inc., a Delaware corporation at 1288 Route 73, Suite 401, Mount Laurel, NJ 08054.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application No. 62/723943, filed August 28, 2018, and U.S. Provisional Patent Application No. 62/878040, filed July 24, 2019, both of which are incorporated herein in their entirety. , via link. Priority to US Provisional Patent Application No. 62/723943, filed August 28, 2018; and US Provisional Patent Application No. 62/878040, filed July 24, 2019,

CONFIRMATION OF FEDERALLY SPONSORED RESEARCH WORKS:

Not provided

LINK TO “MICROFICHE APPENDIX”

Not represented

State of the art

1. Technical field

The present invention relates to low free 2-mercaptoethanol esters and their use. In particular, the present invention relates to the use of esters with low levels of free 2-mercaptoethanol to improve heat stabilizers for halogenated polymers, such as polyvinyl chloride or PVC.

2. General state of the art

PVC is a thermally unstable polymer at traditional processing temperatures, and many stabilizer systems have been developed to address its inherent thermal instability. These technologies include organic stabilizers, mixed metal stabilizers and tin stabilizers. Tin stabilizers are broadly divided into two main technologies: thioglycolic acid (TGA) or reverse ester (RE). TGA or 2-ethyhexyl methacrylate (EHMA) stabilizers have been used successfully since the 1950s, while reverse ester, RE, stabilizers were introduced in the 1970s. Most tin-based PVC heat stabilizers contain both monoalkyl and dialkyl components. This class of stabilizers has also been modified to contain sulfur bridges, which can improve both performance and cost over their non-bridged counterparts (see US Patent 3,565,931).

It is known from US Pat. No. 4,062,881 to Kugele that synergistic stabilizing properties occur when free mercaptan is added to tin mercaptan. Later developments, known from US patent No. 6846861 Herzig et. al, report that organotin mercaptoalkyl heptonates provide improved flavor compared to traditional mercapto esters such as 2-mercaptoethyl tallate, 2-mercaptoethyl oleate, and others. However, this approach is difficult for regulatory and commercial reasons, and this approach has not led to commercial success. The use of 2-mercaptoethanol esters, hereafter referred to as 2ME esters, is commonly accepted in PVC applications where odor is not typically a concern, such as PVC pipes, PVC sheathing and PVC fence backing. There are other applications, such as window profiles and calendering, where odors generated during downstream processing, such as mixing, extrusion, calendering, cutting, welding, have proven to be unacceptable. Typical 2ME esters intended for the production of tin stabilizers may contain up to 3 wt.% residual or free 2ME. Residual 2ME in 2ME-based esters may result from using excess 2ME to increase the yield of the desired 2ME esters. In addition, tin-based stabilizers made from them may also contain up to 2 wt.% residual 2-ME. In addition, additional 2ME can also be added to the reverse ester stabilizer to improve certain aspects of the performance of the final 2ME ester stabilizer. The following US patents are incorporated by reference into this application:

Kugele US Patent No. 4062881; And

Herzig et al. US Patent No. 6846861.

DISCLOSURE OF INVENTION

The present invention is a stabilizer composition for a halogen-containing polymer. It has recently been found that the odor of 2ME esters and the tin stabilizers derived from them can be significantly improved by significantly reducing the amount of residual 2-mercaptoethanol from the ester. This effect can be achieved in several ways, including, but not limited to: water washing, stripping under heat and vacuum, using additional water to facilitate removal under heat and vacuum, using molecular sieves or membrane separation technologies.

It should also be noted that the performance of tin stabilizers for halogenated polymers is directly related to the tin content of the tin stabilizer. However, 2ME extended ester stabilizers provide surprising performance considering that their thermal performance matches that of higher tin stabilizers, thus exhibiting higher thermal efficiency than would be expected based on tin content alone.

2ME-based esters, when used as accelerators for tin-based stabilizers, provide cost advantages over other approaches such as epoxidized soybean oil, commonly designated ESO. ESO has been used for many years in both flexible and rigid PVC as a co-stabilizer to improve the performance of Ca/Zn and tin based stabilizer systems. ESO was commonly used due to its low odor combined with low cost compared to tin-based stabilizers. The color change as shown in Table 1 shows that low free 2-mercaptoethanol ester (LFMEE) provides similar performance to ESO, and the use of LFMEE also avoids the shelf stability problems typically encountered with tin-based stabilizers. ESO.

Table 1: Composition of PVC connection Component PHR 1 2 PVC resin (SE-750) or equivalent 100.0 100.0 Sample 1 2.00 Sample 2 2.00 Calcium stearate 1.2 1.2 Paraffin 165 0.8 0.8 E-14 oxidized polyethylene 0.1 0.1 K400 Acrylic polymer modifier 6.0 6.0 K175 Acrylic polymer modifier 1.0 1.0 CaCO ₃ - UFT Filler 5.0 5.0 _TiO2 pigment 1.0 1.0

Test Conditions : The PVC compound was mixed according to standard additive addition procedures and temperatures. The color stability of each compound was assessed using a Brabender apparatus operating at 190 degrees Celsius/60 rpm, with samples taken at 2-minute intervals. The colors of each chip were measured relative to a standard white tile and the "L-values" are given in Table 2 below.

Table 2: Color meanings Time (min) Color value (L-value) Sample 1 Sample 2 2 90.75 91.01 4 88.98 90.37 6 88.1 89.58 8 86.41 87.79 10 86.25 88.25 14 85.49 86.07 18 80.03 79.04 22 65.78 66.15

Sample 1 85 wt.% ADVASTAB®TM-181FS /15 wt.% LFMEE Sample 2 85 wt.% ADVASTAB®TM-181FS /15 wt.% epoxidized soybean oil

The samples above were prepared using ADVASTAB (TM-181FS grade; however, similar results are expected to be obtained with a generic compound of similar composition.

The present invention also provides the advantage of using renewable sources of fatty acids for the production of 2-mercaptoethyl esters. In contrast, TGA or EHMA based stabilizers are entirely based on oil-derived intermediates.

DETAILED DESCRIPTION OF THE INVENTION

All residual 2-mercaptoethanol removal experiments used standard 2-mercaptoethyl ester produced on commercial PMC Organometallix equipment. The process involves the reaction of 2-mercaptoethanol with a C16-C18 fatty acid using an acid catalyst. As representative manufacturing methods, the following three LFMEE manufacturing methods will be discussed in detail:

Synthesis of standard 2-mercaptoethyl ester:

In the following experiments, 2-mercaptoethyl ester was prepared by reacting one fatty acid equivalent with 1.18 mol 2-mercaptoethanol in the presence of an acid catalyst while slowly heating to 80-85 degrees Celsius in vacuum. Esterification water was removed to speed up the reaction. The reaction mixture was then washed with water to remove the acid catalyst, the wash water was separated, and then the organic layer was dried under vacuum and heat.

Any other suitable method for preparing the standard 2-ME ester may also be used.

Experiment A: 300 grams of standard 2-mercaptoethyl ester were washed 10 times with 100 gram aliquots of water. The washing was carried out in a 500 ml separatory funnel and allowed to stand for 30 minutes. The water (lower phase) was drained and the next aliquot of water was added. After completion of the last wash, the organic phase was dried using vacuum and heating to 110°C.

Experiment B: 100 grams of standard 2-mercaptoethyl ester were treated with 4 times 2.5 grams of water. Standard 2-mercaptoethyl ester was heated to 70°C, then a 2.5 gram aliquot of water was added. The water was removed in vacuo and heated to 70°C. Once the temperature was reached, another 2.5 gram aliquot of water was added. This was repeated for all 4 aliquots of water.

Experiment C: 450 grams of standard 2-mercaptoethyl ester were treated with 112 grams of water, and then the water was removed in vacuo and heated to 85°C.

The percentage of 2-mercaptoethanol removed was determined by measuring the drop in percentage of mercaptosulfur compared to the original 2-mercaptoethyl ester standard.

Table 3: Removing 2ME from 2ME Ester The ex. Initial % mercaptoser % Example. 2-ME Final % mercaptoser %2-IU removed % Example. 2-ME % example. 2-ME removal A 9.12 2.8 8.18 2.22 0.6 80 IN 9.09 2.8 8.02 2.52 0.3 90 WITH 9.09 2.8 7.94 2.70 0.1 >95

Experiments A, B, and C provided high levels of removal of free 2-ME. The resulting esters with lower free 2-ME content were used in further studies to determine their effectiveness as co-stabilizers and/or included as bound species in a tin stabilizer, but without the traditional off-odors resulting from use esters with a higher content of free 2-ME. Other suitable methods for removing 2-ME from 2-ME esters to make the new LFMEE of the present invention may also be used.

Description of the stabilizer manufacturing method

ADVASTAB(TM-181FS) was prepared using the following method:

1.03 equivalents (eq.) of 2-ethylhexylthioglycolate were reacted with an aqueous mixture of monomethyl tin trichloride (25 wt%) and dimethyl tin dichloride (75 wt.%), representing 1.0 equivalent of chloride, using aqueous sodium hydroxide to convert the chloride to mercaptide. This mixture was allowed to stand for 60 minutes to separate the organic and aqueous phases. The lower organic layer was removed, dried under vacuum and heated. This layer was then filtered to obtain a clear liquid.

Table 4: ADVASTAB(TM-181FS* mixed with specified percentage of LFMEE as below Sample ADVASTAB(TM-181FS LFMEE % PHR PHR Tin 1 100% 0% 2.0 0.38 2 95% 5% 2.0 0.361 3 90% 10% 2.0 0.342 4 85% 15% 2.0 0.323 5 80% 20% 2.0 0.304 6 75% 25% 2.0 0.285

Table 5: These samples were incorporated into the PVC as shown Component PHR 1 2 3 4 5 6 PVC (SE-750) or equivalent 100.0 100.0 100.0 100.0 100.0 100.0 Sample 1 2.00 Sample 2 2.00 Sample 3 2.00 Sample 4 2.00 Sample 5 2.00 Sample 6 2.00 Calcium stearate 1.2 1.2 1.2 1.2 1.2 1.2 CS-2054 lubricant 0.8 0.8 0.8 0.8 0.8 0.8 E-14 lubricant 0.1 0.1 0.1 0.1 0.1 0.1 K400 Acrylic modifier 6.0 6.0 6.0 6.0 6.0 6.0 K175 Acrylic modifier 1.0 1.0 1.0 1.0 1.0 1.0 CaCO ₃ - UFT Filler 5.0 5.0 5.0 5.0 5.0 5.0 _TiO2 pigment 1.0 1.0 1.0 1.0 1.0 1.0

Table 6: Color values for TM181FS and LFMEE mixtures Time (min) Color values (L-value) Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Sample 6 2 90.77 92.39 93.91 91.80 93.01 92.79 4 90.84 92.1 93.07 90.66 92.46 93.05 6 91.2 91.85 93.33 89.74 91.71 92.43 8 91.48 92.77 94.04 90.23 92.12 93.4 10 91.78 93.06 94.3 90.15 93.35 93.64 14 92.9 91.94 92.7 94.49 93.27 93.02

*ADVASTAB® TM-181FS was provided by PMC Organometallix, Inc. It is the industry standard for many PVC applications. Other suitable stabilizers may be used. Preferred stabilizer compositions may include compositions similar to the general ADVASTAB® TM-181FS composition shown below:

Type of alkyl group Ligand type Mass% mono component Mass% tin methyl 2-EHMA 27 19.0

PVC blends using the stabilizer compositions listed in Table 5 were subjected to twin-roller performance testing and the corresponding color data (L-values) are shown in Table 6. As shown in Table 6, tin stabilizer blends with up to 25 LFMEE wt.% provided characteristics similar to the control stabilizer. It should also be noted that the performance characteristics of, for example, Samples 5 and 6 are achieved at significantly lower tin contents.

Procedure for the synthesis of stabilizer A and B:

During the manufacture of PVC mixtures for evaluation, the odor of the mixture of ADVASTAB® TM-181FS and LFMEE was found to be similar to the odor of unmodified ADVASTAB® TM-181FS.

ADVASTAB® TM-181FS with standard 2-mercaptoethyl ester, i.e. the ester containing more than 2% by weight of free 2-ME had a noticeably stronger malodor. It is expected that similar results will be achieved in the case of a universal stabilizer of similar composition.

The possibility of using LFMEE in the synthesis of stabilizers was also investigated. The performance of high monooctyltin stabilizers based on LFMEE was compared with its 2-EHMA analog, commercially available Termolit 895. In the context of this work, high monooctyltin refers to tin stabilizers with a mono component content of more than 75% with a corresponding di component content of less than than 25%, and the examples below are based on materials with a mono component content of more than 90%. High monooctyltin content LFMEE was prepared from monooctyltin chloride in a conventional manner as detailed in the experimental section. Tin content was targeted at LFMEE's high monooctyl tin stabilizer, which contains tin, allowing comparison of stabilizers within a narrower range of tin weight percentages, allowing comparison of different stabilizers at similar tin contents and therefore similar loading levels. This approach reduces or eliminates the performance impact of varying thermal stabilizer load levels. Thus, a sulfided version of the original high-mono-octyltin LFMEE was prepared in a manner familiar to one skilled in the art of stabilizers using high-mono-octyltin stannous chloride, LFMEE and sodium sulfide (see Examples for details). This material is described as a high monooctyl LFMEE sulfide and will be referred to as Stabilizer A. Initially, these stabilizers were compared on the same tin base and evaluated in a two-roller stability test. These results are summarized in Table 8.

Description of the stabilizer manufacturing method

Termolit® 895 and stabilizer A were prepared using the following method:

1.02 eq. ester containing mercaptosulfur (for Termolit® 895 it is 2-ethylhexylthioglycolate, for stabilizer A it is a combination of LFMEE and disodium sulfide) was reacted with a mixture of monooctyltin trichloride (95 wt.%) and dioctyltin dichloride (5 wt.%), representing 1, 0 chloride equivalent, using aqueous sodium hydroxide to convert the chloride to mercaptide. This mixture was allowed to stand for 60 minutes to allow the organic and aqueous phases to separate. The lower aqueous layer was removed and the remaining organic phase was dried under vacuum and heat. The solution was then filtered to obtain a clear liquid. Generic equivalents of Thermolite® 895 may be used. It is expected that similar results will be achieved with the generic equivalent of Thermolite® 895.

These stabilizers were evaluated for their effect on PVC processing, particularly their effect on color change with heat and time. These stabilizers were included in the PVC formulation shown in Table 7.

Table 7: Compositions of PVC stabilizers Component PHR Sample 1 Sample 2 Shintech®SE-750 PVC resin 100.0 100.0 Termolit ®895 1.15 Stabilizer A 1.16 Calcium stearate 0.2 0.2 CS-2054 lubricant 0.7 0.7 Arcema® P-530 (polymer modifier) 1.0 1.0 Arcema® P-770 (polymer modifier) 1.0 1.0 Arcema® C-859 (polymer modifier) 8.0 8.0 Omya® UFT CaCO ₃ filler 5.0 5.0 Chemours ®960 TiO ₂ Pigment 0.5 0.5

Generic equivalents of brand name components may be used. It is expected that similar results will be achieved using generic equivalents of brand name components.

Table 8: Testing the stability of stabilizers Time (min) Color values (L-value) Sample 1 Sample 2 2 90.3 91.94 4 90.63 91.56 6 88.70 92.11 8 88.28 92.95 10 84.03 93.09 12 87.86

Sample Description PHR %Tin PHR Tin 1 Termolit ®895 1.15 13.6 2 Stabilizer A 1.16 13.5

As the L values in Table 8 show, Stabilizer A provides better early color, better color development and stability over time compared to the T895 control, which is a traditional EHMA based stabilizer.

To better understand whether the improved performance of LFMEE stabilizers can be extended to lower-end mono stabilizers, an LFMEE stabilizer was prepared from 25% mono/75% di starting material for comparison with commercially available T890F, which has a similar mono/75% di ratio. di-components. T895 and T890F are used for a variety of rigid PVC applications, but find use in films and sheets in particular. The performance of these materials was compared at equal tin contents in a 2-roll mill to evaluate color change, stability over time, relative odor and roll tack, and the results are summarized in Table 10 and Table 11.

These stabilizers were evaluated for their effect on PVC processing, particularly their effect on color change with heat and time. These stabilizers were included in the PVC formulation shown in Table 9.

Table 9: Stabilizer compositions Component PHR Sample 1 Sample 2 Shintech®SE-750 PVC resin 100.0 100.0 Thermolite ®890F 1.0 Stabilizer B 1.05 Calcium stearate 0.2 0.2 CS-2054 lubricant 0.7 0.7 Arcema® P-530 (polymer modifier) 1.0 1.0 Arcema® P-770 (polymer modifier) 1.0 1.0 Arcema® C-859 (polymer modifier) 8.0 8.0 Omya® UFT CaCO ₃ filler 5.0 5.0 Chemours ®960 TiO ₂ Pigment 0.5 0.5

Generic equivalents of brand name components may be used. It is expected that similar results will be achieved using generic equivalents of brand name components.

Table 10: L-value data Time (min) Color values (L-value) Sample 1 Sample 2 2 89.03 88.30 4 88.36 88.62 6 86.89 87.04 8 84.45 86.21 10 74.42 83.22

Sample Description PHR %Tin PHR Tin 1 Thermolite ®890F 1.0 2 Stabilizer B 1.05

Generic equivalents of brand name components may be used. It is expected that similar results will be achieved using generic equivalents of brand name components.

As can be seen in Table 10, the performance of Stabilizer B is superior to that of Thermolite® 890F in terms of color development, indicating that improved LFMEE based stabilizers can be found in a wide range of mono/di components.

Table 11: Relative subjective odor and roll stickiness during processing

T890F T895 Stabilizer A Smell Unpleasant Unpleasant Less unpleasant Stickiness High High Low

Generic equivalents of brand name components may be used. It is expected that similar results will be achieved using generic equivalents of brand name components.

At similar load levels, Stabilizer A provided improved color stability and time stability compared to T890F and T895. Additionally, it provided improved roll stickiness and odor during processing. These performance characteristics are critical for film produced by calendering, which is a process that requires the release of hot plastic melt from hot rolls to produce sheet or film. The calendering process creates a large hot surface, so odor reduction is a positive factor in a production environment.

Further work was aimed at examining the relative effectiveness of Stabilizer A compared to its EHMA-based counterpart, T895. Samples were prepared for testing on a twin-roller stability test using the described PVC composition used to obtain the data in Table 8 above. The results are shown in Table 12.

Table 12: Color values (L-value) of T895 and Stabilizer A at reduced load Time (min) Color values (L-value) Sample 1 Sample 2 Sample 3 Sample 4 2 90.07 89.72 91.87 89.69 4 91.21 89.26 92.03 89.18 6 90.54 88.67 92.35 89.41 8 90.48 90.60 92.93 90.55 10 83.53 90.40 91.73 90.09 12 86.12

Table 13: sample descriptions Sample Description PHR 1 Thermolite®895 1.15 2 Stabilizer A 1.16 3 Stabilizer A 1.08 4 Stabilizer A 1.00

Generic equivalents of brand name components may be used. It is expected that similar results will be achieved using generic equivalents of brand name components.

Table 12 shows that at lower loading levels, Stabilizer A provides better color development than T895 with similar stability over time. All things being equal, it can be concluded that Stabilizer A provides a more cost-effective stabilization solution than its EHMA-based counterpart, along with improved processing.

The unpleasant odor of 2-mercaptoethanol can also be eliminated by reacting as a ligand with an alkyltin halide intermediate. This conversion of 2-mercaptoethanol to a tin-bound mercaptoethanol ligand will reduce volatility and improve odor characteristics. However, the disadvantage of this method is the need to precisely control the stoichiometry, which, if not controlled, can lead to undesirable by-products.

Another alternative means of reacting not only with the residual 2-mercaptoethanol, but with any other active mercaptan group, is the use of the addition of an alkyltin oxide, which is capable of trapping the mercaptan by reacting with the mercaptan to form an alkyltin mercaptide. Examples of alkyltin oxide include, but are not limited to, dioctyltin oxide, dibutyltin oxide, butyl stannic acid and octyl stannic acid.

In the present invention, a low free 2-mercaptoethanol ester (LFMEE) is produced by removing 2-mercaptoethanol from a standard 2-mercaptoethanol ester, wherein the resulting LFMEE has a residual 2-mercaptoethanol content below 1.0 wt%.

In some embodiments, the resulting LFMEE may have a residual 2-mercaptoethanol content below 0.7 wt%.

In some embodiments, the resulting LFMEE has a residual 2-mercaptoethanol content below 0.5 wt%.

The present invention relates to a method of using the above-mentioned LFMEE to improve the thermal performance of alkyltin thioglycolate ester stabilizers.

The present invention is a method of using the above-mentioned LFMEE to improve the thermal performance of reverse alkyltin ester stabilizers.

The present invention provides a method of using the above-mentioned LFMEE to improve the thermal performance of alkyltin mercaptide stabilizers.

In some embodiments, said mercaptide may be dodocyl mercaptan or carboxylates.

In some embodiments, the mercaptide may be a maleate.

In some embodiments of the present invention, the stabilizer further includes a sulfide bridge for alkyl groups ranging from C1 to C8.

In some embodiments of the present invention, the mono- and di-components of the alkyltin groups are in ratios ranging from 100% di-component to 100% mono-component and all combinations in between.

In some embodiments of the present invention, the amount of LFMEE may range from 5 wt.% to 75 wt.%.

In some embodiments of the present invention, the amount of LFMEE may range from 10 wt.% to 40 wt.%.

In some embodiments of the present invention, the resulting stabilizer further includes Ca/Zn based enhancers, organic based stabilizers and/or other conventional performance enhancers such as BHT, polyols, metal salts or other co-stabilisers.

The present invention may include a composition containing:

(a) a reverse alkyl tin ester stabilizer; And

(b) LFMEE according to claims 1-3;

wherein the ratio of reverse alkyl tin ester stabilizer: LFMEE is in the range of 95 wt%: 5 wt% to 25 wt%: 75 wt%.

In the present invention, the composition may include a ratio of reverse alkyl tin ester stabilizer: LFMEE in the range of 85 wt%: 15 wt% to 60 wt%: 40 wt%.

The present invention may include a method of using LFMEE, which is obtained by removing 2-mercaptoethanol from a standard 2-mercaptoethanol ester, characterized in that the resulting LFMEE has a residual content of 2-mercaptoethanol below 1.0 wt.%, as a ligand with 2-EHMA , carboxylates, lauryl mercaptan, 2-mercaptothanol, thioglycolic acid, alkoxides or sulfide.

The present invention may include a method in which the above LFMEE is used together with other ligands in combinations with 2-EHMA, carboxylates, lauryl mercaptan, 2-mercaptothanol, thioglycolic acid, alkoxides or sulfide.

The present invention may include a method for making a PVC stabilizer, comprising:

(a) interaction 1.02 eq. LFMEE obtained by removing 2-mercaptoethanol from a standard 2-mercaptoethanol ester, wherein the resulting LFMEE has a residual 2-mercaptoethanol below 1.0 wt.%, and disodium sulfide with a mixture of monooctyltin trichloride (95 wt.%) and dioctyltin dichloride ( 5 wt.%), which is 1.0 equivalent of chloride, using an aqueous solution of sodium hydroxide;

(b) settling the mixture;

(c) removing the lower aqueous layer;

(d) drying the remaining organic phase; And

(e) filtering the dried organic phase.

The present invention may include the above-mentioned method in which the drying step (d) is carried out under vacuum.

The present invention may include the above-mentioned method in which the drying step (d) is carried out under heating.

The present invention may include the above-mentioned method in which the drying step (d) is carried out under vacuum and heat.

The present invention may include the above method in which step (e) is carried out until a clear liquid is obtained.

List of abbreviations.

2ME - 2-mercaptoethanol

EHMA - 2-ethylhexyl methacrylate

ESO - Epoxidized Soybean Oil

LFMEE - low free 2-mercaptoethanol ester

PHR - parts per hundred resin

PVC - polyvinyl chloride

RE - reverse ester

RPM - number of revolutions per minute

TGA - thioglycolic acid

Claims (45)

1. The use of a low free 2-mercaptoethanol ester (LFMEE) in the stabilization of polyvinyl chloride (PVC), wherein said LFMEE is obtained by removing 2-mercaptoethanol from a standard 2-mercaptoethanol ester, and where the resulting LFMEE has a residual 2-mercaptoethanol content below 1.0 wt.%, wherein said standard 2-mercaptoethanol ester is prepared by reacting 2-mercaptoethanol with a C16-C18 fatty acid. 2. Use according to claim 1, wherein the resulting LFMEE has a residual content of 2-mercaptoethanol below 0.7 wt%. 3. Use according to claim 1, wherein the resulting LFMEE has a residual content of 2-mercaptoethanol below 0.5 wt.%. 4. Application of LFMEE to improve the thermal characteristics of alkyltin thioglycolate ester stabilizers, where the resulting LFMEE has a residual 2-mercaptoethanol content below 1.0 wt.%. 5. The use of LFMEE to improve the thermal characteristics of stabilizers based on reverse alkyl tin esters, where the specified LFMEE has a residual content of 2-mercaptoethanol below 1.0 wt.%. 6. Use of LFMEE to improve the thermal characteristics of alkyltin mercaptide stabilizers, wherein said LFMEE has a residual 2-mercaptoethanol content below 1.0 wt%. 7. Use according to claim 6, wherein the mercaptide is dodecyl mercaptan or carboxylate. 8. Use according to claim 7, wherein the mercaptide is a maleate. 9. Use according to claim 6, wherein said stabilizer further includes a sulfide bridge for alkyl groups in the range C1-C8. 10. Application according to claim 6, in which the mono- and di-components of the alkyltin groups are in ratios from 100% di-component to 100% mono-component and in all combinations between them. 11. Use according to claim 6, in which the amount of LFMEE can be from 5 to 75 wt.%. 12. Use according to claim 6, wherein the amount of LFMEE may be in the range of 10 to 40 wt%. 13. Application according to paragraphs. 4, 5 or 6, wherein the resulting stabilizer further includes Ca/Zn based enhancers, organic based stabilizers and/or other conventional performance enhancers such as BHT, polyols, metal salts or other co-stabilisers. 14. Composition for stabilizing polyvinyl chloride (PVC), containing: (a) a reverse alkyl tin ester stabilizer; And (b) LFMEE, wherein the reverse alkyl tin ester stabilizer is in a ratio to LFMEE ranging from 95 wt%: 5 wt% to 25 wt%: 75 wt%, and wherein said LFMEE has a residual 2-mercaptoethanol content below 1.0 wt% or below 0.7 wt% or below 0.5 wt%. 15. The composition according to claim 14, wherein the reverse alkyl tin ester stabilizer is in a ratio to LFMEE ranging from 85 wt%: 15 wt% to 60 wt%: 40 wt%. 16. Use of LFMEE as a ligand in a tin-based stabilizer, where the resulting LFMEE has a residual 2-mercaptoethanol content below 1.0 wt%. 17. The use of claim 16, wherein the tin stabilizer further comprises a ligand selected from the group consisting of 2-ethylhexyl methacrylate (2-EHMA), carboxylates, lauryl mercaptan, 2-mercaptotanol, thioglycolic acid, alkoxides or sulfides. 18. A method for producing a PVC stabilizer, including: (a) reacting LFMEE and disodium sulfide (total LFMEE and disodium sulfide equivalents are 1.02, where disodium sulfide equivalents may be 0.1-0.6) with a mixture of monooctyltin trichloride (95 wt%) and dioctyl tin dichloride (5 wt.%), which is 1.0 equivalent of chloride, using an aqueous solution of sodium hydroxide; (b) settling the mixture; (c) removing the lower aqueous layer; (d) drying the remaining organic phase; (e) filtering the dried organic phase, wherein said LFMEE has a residual content of 2-mercaptoethanol below 1.0 wt.%. 19. The method according to claim 18, in which the drying step (d) is carried out under vacuum. 20. The method according to claim 18, wherein the drying step (d) is carried out by heating. 21. The method according to claim 18, in which the drying step (d) is carried out under vacuum and heating. 22. The method according to claim 18, in which step (e) is carried out until a clear liquid is obtained. 23. A method for producing a PVC stabilizer, including: (a) reacting LFMEE and disodium sulfide (total LFMEE and disodium sulfide equivalents equal to 1.02, where disodium sulfide equivalents may range from 0.1 to 0.6) with a mixture of monooctyl tin trichloride (2 wt%) and dioctyl tin dichloride (98 wt.%), which is 1.0 equivalent of chloride, using an aqueous solution of sodium hydroxide; (b) settling the mixture; (c) removing the lower aqueous layer; (d) drying the remaining organic phase; (e) filtering the dried organic phase, wherein said LFMEE has a residual content of 2-mercaptoethanol below 1.0 wt.%. 24. The method according to claim 18, in which the drying step (d) is carried out in a vacuum. 25. The method according to claim 18, wherein the drying step (d) is carried out by heating. 26. The method according to claim 18, in which the drying step (d) is carried out under vacuum and heating. 27. The method according to claim 18, in which step (e) is carried out until a clear liquid is obtained. 28. Composition for stabilizing polyvinyl chloride (PVC), containing a material obtained using the method according to claim 18, and a material obtained using the method according to claim 23.