|Publication number||WO1999009094 A1|
|Publication date||25 Feb 1999|
|Filing date||21 Aug 1998|
|Priority date||21 Aug 1997|
|Publication number||PCT/1998/17195, PCT/US/1998/017195, PCT/US/1998/17195, PCT/US/98/017195, PCT/US/98/17195, PCT/US1998/017195, PCT/US1998/17195, PCT/US1998017195, PCT/US199817195, PCT/US98/017195, PCT/US98/17195, PCT/US98017195, PCT/US9817195, WO 1999/009094 A1, WO 1999009094 A1, WO 1999009094A1, WO 9909094 A1, WO 9909094A1, WO-A1-1999009094, WO-A1-9909094, WO1999/009094A1, WO1999009094 A1, WO1999009094A1, WO9909094 A1, WO9909094A1|
|Inventors||Anbazhagan Natesh, Shailesh Shah, Michael P. Connor, William A. Zane, Louis J. Brandewiede, Ronald C. Lafreeda, Robert W. Decker|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (9), Referenced by (7), Classifications (6), Legal Events (8)|
|External Links: Patentscope, Espacenet|
BETA-HYDRQXY MERCAPTANS AS COSTABIL12ERS FOR HALOGENATED RESINS
BACKGROUND OF THE INVENTION
This invention relates to additives for processing halogenated resinous compounds, more particularly to costabilizers that enhance the performance of primary heat stabilizers used to improve the thermal stability of halogenated resins, particularly halogenated vinyl resins, and more particularly, polyvinyl chloride (PVC).
This invention, as previously noted, relates to additives for the processing of halogenated resins, particularly polyvinyl chloride. In particular, this invention is concerned with enhancing the heat stabilizing performance of primary L-=at st bilises used in the processing of halogenated resins. These type resins are known to undergo rapid thermal degradation under the conditions found in the processes to which these resins are subjected, such as, for example, calendering, extrusion, and injection molding. Thus it has been found necessary to utilize stabilizers in processing halogenated resins to counteract the harmful effects on resin properties of thermal degradation during processing.
For example, polyvinyl chloride is known to undergo a rapid and sequi .tial elimination of hydrochloric acid, or dehydrochlorination., at elevated process temperatures. Other halogenated resins are known to undergo similar dehydrohalogenation reactions. Dehydrochlorination in PVC can initiate at at labile chlorines usually associated with irregularities in the molecular chain, such as branches or double bonds. Once free, the hydrochloric acid further degrades the polyvinyl chloride and can greatly accelerate the rate of degradation through autocatalytic unzipping of the chlorines along the polymer chain. The primary function of heat stabilizers in PVC is to scavenge the free hydrochloric acid and to depress further hydrochloric acid elimination.
Thus a variety of stabilizing additives have been developed to counteract the thermal degradation of halogenated organic resins. Lead salt stabilizers are widely used for PVC, but are of increasingly limited applicability because of handling and toxicity concerns. They are also unusable in applications requiring transparency. Mixed metal carboxylate soaps of barium, cadmium, calcium, and zinc are also know, but the resulting chlorides are Lewis acids that further encourage degradation, requiring the use of costabilizers such as epoxidized oils, polyols, and organic phosphites. Barium-cadmium, barium-zinc, and calcium-zinc stabilizers also are know, though cadmium compounds are under increasing scrutiny for toxicologies! and cost considerations. These latter stabilizers also give rise to compatibility problems when used in higher concentrations and contribute to poor water and heat resistance in the resins.
The use of sulfur-containing organotin or organoantimony compounds as heat stabilizers for halogenated resins is well known. These compounds react with the released halogen acid and are converted into the corresponding metal salts. Although these compounds are very effective stabilizers, they unfortunately have the disadvantage of being the most expensive. In addition, these known organoroetaliic stabilisers do not always satisfy the requirements of applications relating to shelf-life, odor, processing properties, and heat resistance. It would be of significance, therefore, to provide materials that can extend the performance of these stabilizers without compromising resin performance or quality, preferably in fact improving resin performance and quality by their use.
Typical costabilizers known to the art for enhancing the performance of organometailic primary heat stablizers are sulfur-containing organic ligands having ester functionality. While these known costabilizers can provide excellent heat stability to halogenated organic resins, they typically offer poor resistance to light degradation and poor water resistance due to the ester chemistry. In addition, these costabilizers contribute to odor problems. Thus there remains a need for new, effective costabilizers for halogenated organic resins that avoid the drawbacks associated with the known costabilizers.
It has now been discovered that certain beta-hydroxy mercaptans unexpectedly improve the performance of primary stabilizers, particularly sulfur-containing organotin and sulfur-containing organoantimony compounds, in the heat stabilization of halogenated resins. The combination provides a stabilizer system which permits more efficient use of primary stabilizers, thus offering resin formulators excellent stabilization at a substantially reduced cost. The combination according to the invention also unexpectedly improves the processing properties of the resins, further providing cost and efficiency improvements to resin processors. The inventive combination also reduces odor problems associated with the processing of resins stabilized thereby and provides increased resistance to resin yellowing associated with thermal degradation.
DESCRIPTION OF THE INVENTION
The present invention relates to a novel combination of beta-hydroxy mercaptan costabilizers and primary heat stabilizers for halogenated organic resins, halogenated organic resins containing the novel combination of mercaptan costabilizers and primary stabilizers, and methods of stabilizing halogenated organic resins with the novel combination of primary stabilizers and beta-hydroxymercaptan costabilizers. The novel combination unexpectedly improves the performance of the primary stabilizers and provides unexpected improvement in the processing properties of the halogenated organic resins stabilized thereby.
The beta-hydroxy mercaptan costabilizers of the present invention are compounds of the formula
The beta-hydroxy mercaptans according to the invention can be prepared by methods known in the an per se. One method entails reacting an epoxide compound with hydrogen sulfide, usually in an aqueous medium and optionally in the presence of a catalyst such as sodium hydroxide, porous clay, or alumina. In a preferred embodiment of this method, a C, to C,0 mixed fatty alcohol is reacted in the presence of a catalyst with epichlorohydrin to form a C, to C„ mixed glycidyl ether. The glycidyl ether is then reacted with hydrogen sultde in an aqueous medium in the presence of sodium hydroxide catalyst to form the beta-hydroxymercaptoalkyl ether costabilizer.
The primary stabilizer in the invention can be any of the primary stabilizers of the classes mentioned above, including lead salts, mixed metal carboxyiate soaps of barium, cadmium, calcium, or zinc, and barium-cadmium, barium-zinc, and calcium-zinc stabilizers. Preferably, the stabilizer is an organometallic compound of the formula
R'»MLy.» wherein R' is C, to C„ alkyl, M is a metal having a valence y of 3 or 4, L is a reactive sulfur-containing ligand, and x is less than y and is 1 , 2, or 3. Preferably, the metal M is tin or antimony, and the reactive ligand L is selected from the group consisting of alk lthioalkanoate esters and mercaptoalkylalkanoate esters. In a particularly preferred embodiment, L is an isooctylthioglycolate or a 2- mercaptoethyloleate group. In another preferred embodiment, the primary stabilizer is selected from the group consisting of dimethyltinbis(2-ethylhexylthioglycolate), methyltintris(2-ethyihexylthioglycolate), and mixtures thereof. In accordance with the invention, the primary stabilizer and the costabilizer are combined in a weight ratio that ranges between about 1:2 and about 2:1, preferably b ween about 2:3 and 3:2.
Other organometallic primary stabilizers suitable for use in this invention are disclosed and described in U.S. Patent Nos,: 2,641,588; 2,641,596; 2,680,726, 2,684,956; 2,726,254; 2,789,963; 2,809,956; 2,830,067; 2,855,417; 2,870,119; 2,914,506; 2,998,441; 3,021,302; 3,069,447; 3,126,400; 3,293,273; 3,340,285;
3,396,185; 3,399,220; 3,424,717; 3,466,261; 3,478,071; 3,485,794; 3,530,158; 3,764,571; 4,008,201; 4,062,881; 4,115,352; 4,303,578; 4,310,454; 4,336,176; and 4,701,486, the disclosures of which are hereby incorporated by reference.
The resin used in the present invention can be any organic halogenated resin. The term organic halogenated resin as used herein refers to halogen-containing vinyl and vinylidene polymers or resins in which the halogen is attached directly to the carbon atoms. Preferably, the polymer is a vinyl halide polymer, more particularly a vinyl chloride polymer. Usually, the vinyl chloride polymer is made from monomers consisting of vinyl chloride alone or a mixture of monomers comprising, preferably, at least about 70% by weight based on the total monomer weight of vinyl chloride.
Other halogen-containing polymers which can be stabilized according to this invention include chlorinated polyethylene having 14 to 75%, e.g. 27%, chloride by weight, chlorinated natural and synthetic rubber, rubber hydrochloride, chlorinated polystyrene, polyvinyl chloride, poly vinylidene chloride, polyvinyl bromide, polyvinylidene bromide, polyvinyl fluoride, polyvinylidene fluoride, copolymers of vinyl chloride with 1 to 90%, preferably I to 30%, of a copolymerizable monomer material such as, for example, vinyl acetate, vinyl butyrate, vinyl benzoate, vinylidene chloride, diethyl fumarate, diethyl maleate, other alkyl fumarates and maleates, vinyl propionate, methyl acrylate, 2-ethylhexyl aery late, butyl acrylate and other alkyl acrylates, methyl raethacrylate, ethyl methacrylate, butyl methacrylate and other alkyl methacrylates, methyl alpha-chloroacrylate, styrene, trichloroethylene, vinyl ethers such as vinyl ethyl ether, vinyl chloroethyl ether and vinyl phenyl ether, vinyl ketones such as vinyl methyl ketone and vinyl phenyl ketone, l-fluoro-2-chloroethylene, acrylonitrile, chioroacrylonitriie, allyl acetate, allylidene diacetate, chloroallylidene diacetate, butadiene, butene, butylene, dibutyl maleate, 1,2-dichloroethylene, ethylene, maieic anhydride, propylene, styrene, vinyl isobutyl ether, vinyl laurate, trans-dichloroethane, maieic acid, acrylic acid, fumaric acid, itaconic acid, and N-vinylpyrrolidinone. Typical copolymers include vinyl chloride-vinyl acetate (96:4 sold commercially as VYNW), vinyl chloride-vinyl acetate (87:13), vinyl chloride-vinyl acetate-maleic anhydride
(86:13:1), vinyl chloride-vinylidene chloride (95:5); vinyl chloride-diethyl fumarate (95:5), and vinyl chloride-2-ethylhexyl acrylate (80:20).
The stabilizer/costabilizer combination according to the present invention is added to the halogenated resin in an amount of 0.01 to 10 parts by weight, preferably
0.05 to 5 pans by weight, per 100 parts by weight of resin. The stabilzer/costabilizer combination can be incorporated into ihe resin by any one of many known methods that provide for uniform distribution of additives throughout resin compositions, such as, for example, admixing in an appropriate mill or mixer.
Depending on the end use, further additives can be added to the halogenated organic resins according to the invention, such as other stabilizers and costabilizers, lubricants, plasticizers, impact modifiers, fillers, pigments, anuoxidants, dyes, ultraviolet light absorbing agents, densifying agents and the like. These additives can be added to the resin separately from the stabilizer/costabilizer combination of the present invention, or they can be combined with the stabilizer/costabilizer combination of the invention to form a complete additive package for the halogenated resins.
The invention will be further understood by reference to the following examples which serve to illustrate, but not limit, the invention.
Preparation of Beta-Hv vmercaptan Costabilizer
A pressure reactor was charged with 150 ml of isopropyl alcohol, 6 g of sodium hydroxide catalyst in the form of a 49.7% aqueous solution, and 30 ml of deionized water. The reactor contents were then saturated with hydrogen sulfide at a pressure of 35 psi. following saturation with hydrogen sulfide, the reactor was charged over approximately three hours with 315 g of a C, to C,0 mixed glycidyl ether, commercially available from CVC Specialty Chemicals, Cherry Hill, NJ, as Erisys GE-7, dissolved in isopropyl alcohol. The resulting mixture was allowed to react for approximately two hours at just under 30°C. Following reaction, the vessel was evacuated of hydrogen sulfide using pressurized nitrogen. The reaction mixture was then adjusted to pH 1-3 with concentrated sulfuric acid and stripped of volatiies under vacuum using a nitrogen sparge. After settling overnight, the contents of the reactor were removed to a seperatory funnel and filtered, yielding 284 g of l-mercapto-2-hydroxypropyl C, to C,„ mixed alkyl ether, having a viscosity of 25 cps (Brookfield DVLT, #2 spindle), Gardner color <l, and SH alue of 3.51 meq/g.
pvajyation of fieta-Hvψ-nxv Mercaptan As Co-Stabilizer
Powdered resin compositions were prepared in accordance with the formulations given in the table below. The quantities are expressed in parts by weight.
1. Oxy 225 S.G., polyvinyl chloride available from Occidental Chemical
2. ADVASTAB® TM-181, dimethyltinbis (2-ethylhexylthioglycolate) / methyltintris (2-ethylhexylthioglycolate) stabilizer available from Morton International
3. KM 390, available from Rohn & Haas
4. Loxiol VGE 1883, lubricant available from Henkei Corp., Ambler, PA
5. Stabiol 1079, stabilizer available from Henkei Corp., Ambler, PA
6. R- 101 , titanium dioxide available from Du ont
7. TJFT, stearic-coated calcium carbonate available from Omya
8. Loxiol HOB-7169, available from Henkei Corp., Ambler, PA
9. Ca-St 12b, calcium stearate available from Ferro Corp.
10. AC-629A, oxidized polyethylene wax available from Allied-Signal Fusion Test
65 g each of the above resin formulations were subjected to fusion testing using a Brabender Plasticorder PL2000 with a number 6 roller head with roller blades at 185 °C and 60 rpm. The resin according to the present invention demonstrated no significant difference in fusion time or equilibrium temperature, while providing improved processability due to the decrease in fusion and equlibrium torques.
65 g each of the above resin formulations were subjected to dynamic thermal stability testing using a Brabender Plasticorder PLV300 at 2G0°C and 60 rpm. The resin formulation according to the invention demonstrated no significant difference in thermal stability, while offering improved processability as evidenced by the lower equilibrium torque.
Samples of each of the above resins were extruded using a Brabender Plasticorder PL2000 fitted with a conical twin screw extruder and a 4" adjustible sheet die. The resins were extruded at 15 rpm through four zones each at 185° C. The formulation according to the invention demonstrated unexpected and significant processing advantages. Torque was reduced by more than 13% and pressure by more than 18% with no significant changes in resin quality. Moreover, the resin of the invention experienced greatly superior resistance to yellowing (Color b* below).
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|Citing Patent||Filing date||Publication date||Applicant||Title|
|US6667357||15 Dec 2000||23 Dec 2003||The College Of William And Mary||Organic thiol metal-free stabilizers and plasticizers for halogen-containing polymers|
|US6747081||14 Jun 2002||8 Jun 2004||The College Of William And Mary||Organic thiol metal-free stabilizers and plasticizers for halogen-containing polymers|
|US6762231||19 Jun 2001||13 Jul 2004||The College Of William And Mary||Organic thiol metal-free stabilizers and plasticizers for halogen-containing polymers|
|US6927247||12 Jun 2003||9 Aug 2005||The College Of William And Mary||Organic thiol metal-free stabilizers and plasticizers for halogen-containing polymers|
|US7087193||27 Nov 2001||8 Aug 2006||Akzo Nobel N.V.||Stabilizer composition for use in polyvinyl chloride formulations having a mixture of at least one organotin sulfide, at least one oranotin chloride, and at least one free mercaptan|
|US7250457||19 May 2004||31 Jul 2007||The College Of William And Mary||Organic thiol metal-free stabilizers and plasticizers for halogen-containing polymers|
|US7312266||12 Oct 2004||25 Dec 2007||The College Of William And Mary||Organic thiol metal-free stabilizers and plasticizers for halogen-containing polymers|
|International Classification||C08K5/37, C08K5/56|
|Cooperative Classification||C08K5/37, C08K5/56|
|European Classification||C08K5/37, C08K5/56|
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