Stabilized PVC compositions comprising pvdc

Abstract

The present invention relates to a stabilized PVDC-containing PVC composition, comprising at least 70 wt% of PVC and from 0.05 wt% to 30 wt% of PVDC and further comprising at least one compound selected from the list consisting of organotin compounds and epoxidized compounds and to a method for preparing this composition. The invention also relates to the use of the stabilized PVDC-containing PVC composition in extrusion or injection molding applications and to items made thereof.

Description

Stabilized PVC compositions comprising PVDCCross reference

[0001] This application claims priority to application No.202411010308 filed in India on 14 February 2024, the whole content of this application being incorporated herein by reference for all purposes.Technical field

[0002] The present invention relates to a stabilized PVDC-containing PVC composition, comprising at least 70 wt% of PVC and from 0.05 wt% to 30 wt% of PVDC and further comprising at least one compound selected from the list consisting of organotin compounds and epoxidized compounds.Background

[0003] Copolymers based on vinylidene chloride typically comprising vinyl chloride, alkyl acrylates, ethylene, acrylonitrile or mixtures thereof are often used as a coating onto plastic films in order to ensure to the later excellent barrier properties either against oxygen or against water vapor.

[0004] Such coated films are used mainly in food or pharmaceutical packaging applications and more particularly to form blister packs for drugs.

[0005] In such applications, most films are made of polyvinyl chloride (PVC). Indeed, PVC rigid film with a thickness of e.g. 250 pm can be easily thermoformed to prepare the plastic part of the package. Beforehand, PVC films are typically coated by polyvinylidene chloride (PVDC) copolymers latexes and the resulting coated substrate is further dried to obtain the film having the desired barrier properties.

[0006] Generally, in order to enhance the adhesion of the PVDC coating to the PVC substrate, PVC films are first coated with an anchor agent or primer that can be selected from polyacrylic acid resins, polyurethane resins, isocyanate resins, polyesters resins, oxazoline resins and carbodiimide resins. Therefore, PVC / PVDC coated films can be considered as multilayer films.

[0007] Those multilayers films generally comprise up to 30 wt % of PVDC.

[0008] The recycling of blister package wastes is complex due to the layered structure of plastic parts and due to the presence of aluminum lidding in the case of end- of-life wastes.

[0009] Although aluminum lidding is present in-end-of life waste and likely present in post-industrial waste, it can be efficiently separated from the plastic part by methods well known to the skilled person; for example through dissolving aluminum foil with a hydrochloric acid solution. However, delamination between PVC films and coated layer such as PVDC layer is not possible and the entirety of the plastic part of the blister has to be recycled as a single material.

[0010] Mechanical recycling of this PVDC / PVC plastic material from pharmaceutical blisters in PVC composition suitable for extrusion and injection molding applications is rendered difficult since PVDC and PVC heat stabilities are different. Indeed, the thermal degradation of PVDC occurs at a lower temperature than PVC thermal degradation and at a higher rate for a given temperature. Extrusion and injection molding applications generally require temperatures above 170°C.

[0011] Accordingly, a small amount of PVDC copolymer in a PVC based composition is detrimental to the thermal stability of such a compound and suitable stabilization is required for use in some applications requiring temperatures above 170°C.

[0012] Generally, thermal degradation of PVC based compositions results in the loss of mechanical properties and in turning to yellow up to dark brown colour.

[0013] US5726234 raises the problem of recycling multilayer films comprising PVDC in PVC compositions for applications requiring processing temperatures above 170°C. Indeed, degradation inducing discoloration and HCI evolution is generally observed, even when standard PVC stabilizers based e.g. on Ca / Zn are used. The solution provided by US5726234 is a stabilized PVDC- containing PVC composition comprising inorganic compounds of the series of metal oxides, metal hydroxides or metal carbonates wherein metals are preferably barium (Ba), calcium (Ca), magnesium (Mg), zinc (Zn), titanium (Ti),lead (Pb), tin (Sn), and manganese (Mn). However, the stability of these compositions is rather limited as revealed by the coloration of samples submitted to temperatures exceeding 170°C.

[0014] Therefore, there is still a need for a stabilized PVC composition comprising PVDC suitable for extrusion and injection molding applications with improved thermal stability.

[0015] There is a need for a stabilized PVC composition comprising PVDC suitable for extrusion and injection molding applications showing good retention of colour when processed at high temperatures.

[0016] There is a need for a stabilized PVC composition comprising PVDC, suitable for extrusion and injection molding applications, having enhanced mechanical properties such as improved ductility.Summary of the invention

[0017] With the aim of fulfilling the above needs, the Applicant faced the problem of providing a new stabilized PVDC-comprising PVC composition suitable for use in extrusion and injection molding applications.

[0018] Thus, in a first aspect, the present application relates to a stabilized PVDC- comprising PVC composition comprising at least 70 wt% of PVC and from 0.05 wt% to 30 wt% of PVDC and further comprising at least one compound selected from the list consisting of organotin compounds and epoxidized compounds.

[0019] Without being bound to any theory, organotin compounds and epoxidized compounds are considered as heat stabilizers for the composition according to the invention.

[0020] In another aspect, the present application relates to a method for preparing the stabilized PVDC-comprising PVC composition according to the invention.

[0021] This is advantageous because the stabilized PVDC-comprising PVC composition according to the invention can be used in extrusion and injection molding applications to manufacture items for e.g. building industry such as pipes and profiles like window profiles.

[0022] It is also advantageous because the stabilized PVDC-comprising PVC composition according to the invention can be prepared by a method that can be easily implemented by a person of ordinary skill in the art.

[0023] It is also the opportunity to recycle multilayer films comprising PVDC and PVC from blister packs coming from end-of-life waste or post-industrial waste in PVC compositions for extrusion and injection molding applications to manufacture items for e.g. building industry such as pipes and profiles like window profiles.

[0024] Therefore, still another aspect of the invention is the use of the stabilized composition according to the invention in extrusion and injection molding applications.

[0025] Finally, another aspect of the invention is an item manufactured with the stabilized composition according to the invention.Detailed description

[0026] The inventors have found that stabilized PVDC-comprising PVC compositions as described in prior art show moderate resistance to thermal degradation when exposed to demanding temperature conditions.

[0027] In particular, the inventor have found that stabilized PVDC-comprising PVC compositions from prior art using calcium oxide as heat stabilizer, Ca-Zn heat stabilizer or calcium oxide in combination with Ca-Zn heat stabilizer give poor heat stability when submitted to a temperature of 180°C.

[0028] It has also been found that stabilized compositions from prior art using calcium oxide as heat stabilizer, Ca-Zn heat stabilizer or calcium oxide in combination with Ca-Zn heat stabilizer gives material having limited mechanical properties such as tensile strength or elongation at break.

[0029] The present application relates to a stabilized PVDC-comprising PVC composition comprising at least 70 wt % of PVC and from 0.05 wt% to 30 wt% of PVDC and further comprising at least one compound selected from the list consisting of organotin compounds and epoxidized compounds.

[0030] Without being bound to any theory, organotin compounds and epoxidized compounds are considered as heat stabilizers for the composition according to the invention.

[0031] In some embodiments, the stabilized PVDC-comprising PVC composition comprises at least 80 wt % of PVC, preferably at least 85 wt % of PVC, more preferably at least 90 wt % of PVC and even more preferably at least 95 wt % of PVC.

[0032] In some embodiments, the stabilized PVDC-comprising PVC composition comprises from 0.1 wt % to 25 wt % of PVDC, preferably from 0.5 wt % to 20 wt % of PVDC, more preferably from 1 wt % to 15 wt % of PVDC, preferably from 1 wt % to 12 wt % of PVDC.

[0033] Good results were obtained with stabilized PVDC-comprising PVC composition comprising 89 wt % of PVC and 11 wt % of PVDC.

[0034] In the present invention, the term PVDC encompasses copolymers based on vinylidene chloride typically comprising vinyl chloride, acrylonitrile, acrylates or ethylene as comonomers.

[0035] Without any limitation, organotin compounds suitable for the invention can be selected from the list consisting of dimethyltin bis(2-ethylhexylthioglycolate), mono methyltin tris-(2-ethylhexylthioglycolate), di-n-octyl tin mercaptide, octyl tin mercaptide, butyl tin mercaptide, methyl tin mercaptide, di-n-octyltin oxide, tetra-n-octyltin, butyltin laurate, di-n-butyltin dilaurate, dimethyltin bis(2- ethylhexylmercaptoacetate), dimethyltin bis(2-ethylhexyl thioglycolate), dimethyl tin mercaptide, dibutyl tin mercaptide, dibutyltin maleate ester, methyltin tris(2-ethylhexyl mercaptoacetate), methyl tin maleates, methyl tin octyl thioacetate, methyl tin lauryl thioacetate, methyl tin carboxylates and mixtures thereof.

[0036] Good results were obtained with methyl tin mercaptide.

[0037] Generally, organotin compounds can be used in an amount ranging from 0.1 to 10, preferably from 0.1 to 5, more preferably from 0.1 to 3 parts by weight based on 100 parts by weight of polymers PVDC and PVC.

[0038] Without any limitation, epoxidized compounds suitable for the invention can be selected from the list consisting of epoxidized soybean oil, epoxidized linseed oil, epoxy esters such as octyl epoxy stearate and 2-ethylhexyl epoxy stearate and mixtures thereof.

[0039] Good results were obtained with epoxidized soybean oil (ESO).

[0040] Generally, epoxidized compounds can be used in an amount ranging from 0.1 to 10, preferably from 0.1 to 5, more preferably from 0.1 to 3 parts by weight based on 100 parts by weight of polymers PVDC and PVC.

[0041] In some embodiments, the composition according to the invention is substantially free or even completely from calcium oxide, from Ca-Zn heat stabilizer or from calcium oxide in combination with Ca-Zn heat stabilizer.

[0042] In some other embodiments, the composition according to the invention further comprises at least one compound selected from the list consisting of betadiketones and metal beta-diketones salts.

[0043] Without being bound to any theory, beta-diketones and metal beta-diketones salts are considered as co-stabilizers for the composition according to the invention.

[0044] Beta-diketones can be selected from compounds of formula (I) below RI-(C=O)-CHR2-(C=O)-R3 wherein Ri and R3 which may be the same or different, represent a C1-C22 linear, branched or cyclic alkyl group, a C2-C20 linear, branched or cyclic alkenyl group, a C1-C18 linear, branched or cyclic alkoxy group, an optionally substituted aryl group or an optionally substituted alkyl aryl group; and wherein R2 represents H, or a C1-C22 linear, branched or cyclic alkyl group, a C2-C20 linear, branched or cyclic alkenyl group, an optionally substituted aryl group or an optionally substituted alkyl aryl group.

[0045] R1 and R3 preferably represent a C1-C22 linear, branched or cyclic alkyl group, a phenyl group, a phenyl group substituted by -OH, methyl or methoxy group, or a cyclohexyl group.

[0046] R2 preferably represents H.

[0047] Suitable beta-diketone is for example, acetyl acetone (AcAc), dibenzoyl methane (DBM) and stearoyl benzoyl methane (SBM) or a mixture thereof.

[0048] Good results were obtained with SBM, Rhodiastab® 55 available from Syensqo.

[0049] Generally, beta-diketones can be used in an amount ranging from 0.01 to 5 , preferably from 0.01 to 2, more preferably from 0.01 to 1 parts by weight based on 100 parts by weight of polymers PVDC and PVC.

[0050] Metal beta-diketones salts can be selected from metal salts of compounds of formula (I) as previously described, wherein metal is Ca, Zn, Mg, Al or mixture thereof.

[0051] Suitable metal beta-diketones salts are for example, calcium acetyl acetonate (Ca(acac)2), magnesium acetyl acetonate (Mg(acac)2), zinc acetyl acetonate (Zn(acac)2) and aluminum acetyl acetonate (Al(acac)3).

[0052] Good results were obtained with Ca(acac)2, Rhodiastab® 77 available from Syensqo.

[0053] Generally, metal beta-diketones salts can be used in an amount ranging from 0.01 to 5 , preferably from 0.01 to 2, more preferably from 0.01 to 1 parts by weight based on 100 parts by weight of polymers PVDC and PVC

[0054] In some embodiments, the composition according to the invention comprises at least 70 wt % of PVC and from 0.05 wt% to 30 wt% of PVDC, at least one compound selected from the list consisting of organotin compounds and epoxidized compounds and at least one compound selected from the list consisting of beta-diketones and metal beta-diketones salts.

[0055] In some other embodiments, the composition according to the invention comprises at least 70 wt % of PVC and from 0.05 wt% to 30 wt% of PVDC, at least one organotin compound, at least one beta-diketone and at least one metal beta-diketone salts.

[0056] Still in some other embodiments, the composition according to the invention comprises 70 wt % of PVC and from 0.05 wt% to 30 wt% of PVDC, methyl tin mercaptide, stearoyl benzoyl methane and Ca(acac)2.

[0057] In some other embodiments, the composition according to the invention comprises at least 70 wt % of PVC and from 0.05 wt% to 30 wt% of PVDC, at least one epoxidized compound, at least one beta-diketone and at least one metal beta-diketone salts.

[0058] Good results were obtained, with a composition comprising 70 wt % of PVC and from 0.05 wt% to 30 wt% of PVDC, epoxidized soybean oil, stearoyl benzoyl methane and Ca(acac)2.

[0059] In some other embodiments, the composition according to the invention further comprises at least one organic compound selected from the list consisting of amino crotonates, nitrogen heterocyclic compounds and organosulfur compounds.

[0060] This organic compound is considered as an organic co-stabilizer for the composition according to the invention.

[0061] Nitrogen heterocyclic compound can be for example 1 ,3,5-tris(2-hydroxyethyl) isocyanurate is used to improve PVC processing temperature and performance.

[0062] Accordingly, in some embodiments, the composition according to the invention comprises at least 70 wt % of PVC and from 0.05 wt% to 30 wt% of PVDC, at least one compound selected from organotin compounds and epoxidized compounds, optionally at least one beta-diketone, optionally at least one metal beta-diketone salt and 1 ,3,5-tris(2-hydroxyethyl) isocyanurate.

[0063] In some embodiments, the composition according to the invention comprises at least 70 wt % of PVC and from 0.05 wt% to 30 wt% of PVDC, at least one compound selected from organotin compounds and epoxidized compounds, at least one beta-diketone, at least one metal beta-diketone salt and 1 ,3,5-tris(2- hydroxyethyl) isocyanurate.

[0064] In some other embodiments, the composition according to the invention comprises at least 70 wt % of PVC and from 0.05 wt% to 30 wt% of PVDC, methyl tin mercaptide, stearoyl benzoyl methane, Ca(acac)2 and 1 ,3,5-tris(2- hydroxyethyl) isocyanurate.

[0065] Still in some other embodiments, the composition according to the invention comprises at least 70 wt % of PVC and from 0.05 wt% to 30 wt% of PVDC, epoxidized soybean oil, stearoyl benzoyl methane, Ca(acac)2 and 1 ,3,5-tris(2- hydroxyethyl) isocyanurate.

[0066] The composition according to the invention can also comprise additives selected from processing aid, lubricants, impact modifier, filler(s), pigment, UV stabilizer, antioxidants, fire retardants, plasticizers or mixture thereof.

[0067] Accordingly, the composition according to the invention can comprise at least one processing aid such as alkyl / aryl phosphite.

[0068] Good results were obtained with tris(2,4-di-tert.-butylphenyl) phosphite, Irgafos® 168 available from BASF.

[0069] Therefore, in some embodiments, the composition according to the invention comprises at least 70 wt % of PVC and from 0.05 wt% to 30 wt% of PVDC, at least one compound selected from organotin compound and epoxidized compounds, optionally at least one beta-diketone, optionally at least one metal beta-diketone salt and at least one alkyl / aryl phosphite.

[0070] In some embodiments, the composition according to the invention comprises at least 70 wt % of PVC and from 0.05 wt% to 30 wt% of PVDC, at least one compound selected from organotin compound and epoxidized compounds, at least one beta-diketone, at least one metal beta-diketone salt and at least one alkyl / aryl phosphite.

[0071] In some other embodiments, the composition according to the invention comprises at least 70 wt % of PVC and from 0.05 wt% to 30 wt% of PVDC, methyl tin mercaptide, stearoyl benzoyl methane, Ca(acac)2 and tris(2,4-di- tert.-butylphenyl) phosphite.

[0072] Still in some other embodiments, the composition according to the invention comprises at least 70 wt % of PVC and from 0.05 wt% to 30 wt% of PVDC, epoxidized soybean oil, stearoyl benzoyl methane, Ca(acac)2 and tris(2,4-di- tert.-butylphenyl) phosphite.

[0073] Moreover, the composition according to the invention can comprise processing aids such as acrylic elastomers.

[0074] Good results were obtained with the acrylic processing aid lndofil-k-120ND available from Indofil Chemicals Company.

[0075] Accordingly, in some embodiments, the composition according to the invention comprises at least 70 wt % of PVC and from 0.05 wt% to 30 wt% of PVDC, at least one compound selected from organotin compound and epoxidized compounds, optionally at least one beta-diketone, optionally at least one metal beta-diketone salt and at least one acrylic elastomer.

[0076] In some embodiments, the composition according to the invention comprises at least 70 wt % of PVC and from 0.05 wt% to 30 wt% of PVDC, at least one compound selected from organotin compound and epoxidized compounds, at least one beta-diketone, at least one metal beta-diketone salt and at least one acrylic elastomer.

[0077] In some other embodiments, the composition according to the invention comprises at least 70 wt % of PVC and from 0.05 wt% to 30 wt% of PVDC, methyl tin mercaptide, stearoyl benzoyl methane, Ca(acac)2, tris(2,4-di-tert.- butylphenyl) phosphite and at least one acrylic elastomer such as Indofil-k- 120ND.

[0078] Still in some embodiments, the composition according to the invention comprises at least 70 wt % of PVC and from 0.05 wt% to 30 wt% of PVDC, epoxidized soybean oil, stearoyl benzoyl methane, Ca(acac)2, tris(2,4-di-tert.- butylphenyl) phosphite and at least one acrylic elastomer such Indofil-k- 120ND.

[0079] The composition according to the invention can comprise lubricants like metal stearates, dicarboxylic esters of fatty acids and paraffin wax for example.

[0080] Additionally, the composition according to the invention can comprise impact modifiers such as chlorinated polyethylenes, ethylene / vinyl acetate copolymers, methacrylate / butadiene / styrene elastomers and butylacrylate elastomers crosslinked into beads.

[0081] Good results were obtained with the acrylic impact modifier Indofil KM-323B available from Indofil Chemicals Company.

[0082] Therefore, in some embodiments, the composition according to the invention comprises at least 70 wt % of PVC and from 0.05 wt% to 30 wt% of PVDC, at least one compound selected from organotin compound and epoxidized compounds, optionally at least one beta-diketone, optionally at least one metal beta-diketone salt, at least one acrylic elastomer and at least one acrylic impact modifier.

[0083] In some embodiments, the composition according to the invention comprises at least 70 wt % of PVC and from 0.05 wt% to 30 wt% of PVDC, at least one compound selected from organotin compound and epoxidized compounds, at least one beta-diketone, at least one metal beta-diketone salt, at least one acrylic elastomer and at least one acrylic impact modifier.

[0084] In some other embodiments, the composition according to the invention comprises at least 70 wt % of PVC and from 0.05 wt% to 30 wt% of PVDC, methyl tin mercaptide, stearoyl benzoyl methane, Ca(acac)2, tris(2,4-di-tert.- butylphenyl) phosphite, at least one acrylic elastomer such as lndofil-k-120ND and at least one acrylic impact modifier such as Indofil KM-323B.

[0085] Still in some other embodiments, the composition according to the invention comprises at least 70 wt % of PVC and from 0.05 wt% to 30 wt% of PVDC, epoxidized soybean oil, stearoyl benzoyl methane, Ca(acac)2, tris(2,4-di-tert.- butylphenyl) phosphite, at least one acrylic elastomer such as lndofil-k-120ND and at least one acrylic impact modifier such as Indofil KM-323B.

[0086] The composition according to the invention can comprise fillers, such as carbonates, glass fibres, glass beads, kaolin, talc, silica, wollastonite, mica, and carbon fibres.

[0087] The composition according to the invention can comprise inorganic pigments selected from oxides, mixed oxides, sulphides, chromates, silicates, phosphates and sulphates of metals chosen from titanium, iron, zinc, chromium, cobalt and manganese.

[0088] Good results were obtained with white pigment TiO2.

[0089] The composition according to the invention can comprise organic pigments like pigments containing azo groups or pigments derived from porphyrin.

[0090] The composition according to the invention can comprise light stabilizers like 2-hydroxybenzophenones, 2-hydroxyphenylbenzotriazoles, phenyl salicylate and sterically hindered amines for example.

[0091] The composition according to the invention can comprise hindered phenolics and polyols antioxidants like di-t-butyl-para-cresol, tetrakis{3-(3’,5’-di-t-butyl-4’- hydroxyphenyl)} pentaerythritol.

[0092] The composition according to the invention can comprise fire retardants like di(2-ethylhexyl)phosphate and tri(2-ethylhexyl)phosphate, boric acid, ammonium, sodium, calcium, barium and zinc borates, and zinc hydroxystannate .

[0093] The composition according to the invention can also comprise plasticizers like citrates, phthalates, benzoates, adipates, sebacates, trimellitates and mixtures thereof.

[0094] In the PVDC-containing PVC composition according to the invention, PVDC can come from recyclates, more particularly from blister packs coming from end-of-life waste or post-industrial waste.

[0095] In particular PVDC can come from PVC / PVDC blister flakes of duplex structure, with 40 grams per square meter (gsm) of PVDC, containing about 11 wt% of PVDC with regards to the total weight of PVDC and PVC or from PVC / PVDC blister flakes of duplex structure, with 120 grams per square meter (gsm) of PVDC, containing about 25 wt% of PVDC with regards to the total weight of PVDC and PVC.

[0096] Another aspect of the present invention is a method for preparing the stabilized PVDC-containing PVC composition previously disclosed.

[0097] The composition according to the invention can be prepared by any method well known by the skilled person.

[0098] Generally, the method for preparing the stabilized PVDC-containing PVC composition according to the invention comprises adding to at least 70 wt% of PVC and from 0.05 wt% to 30 wt% of PVDC at least one compound selected from the list consisting of organotin compounds and epoxidized compounds.

[0099] In some embodiments, the method for preparing the stabilized PVDC- containing PVC composition according to the invention comprises adding to at least 70 wt% of PVC and from 0.05 wt% to 30 wt% of PVDC at least one compound selected from the list consisting of organotin compounds and epoxidized compounds, and any co-stabilizers and additives as previously described.

[0100] Still another aspect of the invention is the use of the stabilized PVDC- containing PVC composition in extrusion and injection molding applications.

[0101] Generally, these applications are performed at a temperature exceeding 170°C and therefore require stabilized composition such as the composition according to the invention.

[0102] Finally, another aspect of the invention is an item comprising the stabilized PVDC-containing PVC composition.

[0103] Generally, said item is composed of the composition according to the invention.

[0104] Just for the sake of example, the items according to the invention can be pipes or profiles such as window profiles, mandrels, core tubes for paper rolls, etc..

[0105] Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.

[0106] The invention will be now described with reference to the following examples, whose purpose is merely illustrative and not intended to limit the scope of the invention.Experimental section

[0107] Raw materials

[0108] Methyl tin mercaptide was purchased from Himalaya Polyplast Industry.

[0109] Epoxidized soybean oil (ESO) was purchased from Zeta Scientific.

[0110] Paraffin wax was obtained from Sisco Research Laboratories Pvt. Ltd.

[0111] Sebacate, adipate etc. were obtained from TCI Chemicals.

[0112] Calcium carbonate was purchased from SiscoChem Pvt. Ltd.

[0113] Liveo and ACG PVC / PVDC blister flakes of duplex structure, with 40 grams per square meter (gsm) of PVDC and containing 11 wt% of PVDC with regards to the total weight of PVDC and PVC were used.

[0114] Liveo and ACG PVC / PVDC blister flakes of duplex structure, with 120 grams per square meter (gsm) of PVDC and containing 25 wt% of PVDC with regards to the total weight of PVDC and PVC were also used successfully.

[0115] Virgin PVC K57 from Formosa (Formolon® B57) was used to “dilute” PVC / PVDC blister flakes of duplex structure to obtain desired PVC content in the final compound.

[0116] Sample preparation

[0117] PVDC / PVC blister compositions were prepared using different weight ratio of PVDC / PVC blister (Duplex structure, 40 gsm, PVDC 11wt%) and PVC (K57) resin. The mixture of PVDC / PVC and PVC were physically mixed with heat stabilizer in an internal mixer Brabender® plasticorder®. The PVDC / PVC blister and PVC (K57) mixture with heat stabilizer / co-stabilizers were melt mixed at 180°C for 4 min at 40 rpm.

[0118] Please note that good results could also be obtained with PVDC / PVC blister Duplex structure, 120 gsm, PVDC 25 wt%.

[0119] The various PVDC / PVC compositions are as given in table 1

[0120] Table 1 : PVDC (from PVDC / PVC blister flakes) and PVC compositions

[0121] The solids were then compression molded at a mold temperature of 180°C and a pressure 5000 psi to obtain 10 x 10 cm plaque for the colour measurement (AE) and specimens for the mechanical properties.

[0122] Colour measurement (AE)

[0123] The compression-molded plaques were measured for colour, particularly AE measured against white standard using Color i7 as recommended by ASTM D2244. The highest the AE, the more coloured is the sample under evaluation, and the lower the thermal stability is.

[0124] Mechanical testing

[0125] The plaques were die punched to obtain tensile specimens as per ASTM D638. The tensile properties measured using Zwick-Roll UTM at 23 °C and 50% RH.

[0126] Table 2 contains the results of colour measurements and mechanical testing of the different PVDC (from PVDC / PVC blister flakes) and PVC compositions stabilized respectively by methyl tin mercaptide, ESO and stabilizers of prior art.

[0127] Table 2: Colour measurement and mechanical properties of PVDC (from PVDC / PVC blister flakes) and PVC compositions*brabender® 180°C, 4 min, 40 rpm**Ex. 1 of patent application US5726234***Ex. 4 of patent application US5726234

[0128] The results of Table 2 show that recycled PVDC / PVC blister flakes comprising 11 wt % of PVDC can be stabilized using an organotin compound such as methyl tin mercaptide or an epoxidized compound such as ESO in a more efficient way than using the stabilizers of prior art. Indeed, Example 5a and Example 5b reveal lower AE values than Comparative Example 1 and Comparative Example 2 (respectively 56 and 53 vs 64.5 and 66).

[0129] Moreover, the mechanical properties are better in the case of PVDC / PVC blister flakes comprising 11 wt % of PVDC stabilized by methyl tin mercaptide or by ESO than in the case of PVDC / PVC blister flakes comprising 11 wt % of PVDC stabilized by the stabilizers of prior art. Indeed, Example 5a and Example 5b reveal higher tensile strength values than Comparative Example 1 and Comparative Example 2 (respectively 53.8 MPa and 46.9 MPa vs 43.2 MPa and 44.9 MPa) and higher or similar elongation at break values (respectively 90.3 % and 94.2 % vs 66.9 % and 108.1 %).

[0130] Finally, the inventors have found surprisingly that PVDC (from PVDC / PVC blister flakes) and PVC compositions, stabilized by methyl tin mercaptide or by ESO comprising from 2 wt % to 11 wt % of PVDC (examples 2a-5a and 2b-5b respectively) reveal slightly lower tensile strength but higher elongation at break than pure PVC K57 stabilized by the same additives (examples 1a and 1 b respectively).

[0131] The inventors have also found surprisingly that epoxidized compounds such as ESO are more efficient to stabilize PVDC (from PVDC / PVC blister flakes) and PVC compositions comprising 2-11 wt % of PVDC than to stabilize pure PVC (AE = 51-55 for Examples 2b-5b and AE = 75 for Example 1 b).

[0132] Table 3 describes the list of additives for preparing PVDC (from PVDC / PVC blister flakes) and PVC white compositions suitable to be processed by extrusion or injection molding to manufacture items for e.g. building industry such as pipes and profiles like window profiles. The amount of additives is given in gram per hundred gram of resin of PVDC and PVC (PHR).

[0133] The polymer powder and / or flakes were physically mixed with heat stabilizers and other additives and were charged to the internal mixer with screw rotors at 180°C, 40-50 rpm.

[0134] Table 3: PVC white formulation additives packages

[0135] Table 4 contains the results of colour measurements and mechanical testing of the different PVDC (from PVDC / PVC blister flakes) and PVC white compositions comprising the additives of Table 3.

[0136] Table 4: Colour measurement and mechanical properties of PVDC (fromPVDC / PVC blister flakes) and PVC white compositions*brabender® 180°C, 4 min, 40 rpm

[0137] The results of Table 4 show that the formulation of the additives of table 3, allows preparing PVDC (from PVDC / PVC blister flakes) and PVC white compositions, which have heat stabilities close to the stability of a pure PVC white composition. Indeed, AE value for PVC only white composition is 12.9 for Example 1 c while it does not exceed 21 .6 for Example 5c wherein 11 wt % of PVDC is present.

[0138] Moreover, the results of Table 4 show surprisingly that the presence of PVDC is not detrimental to tensile strength, which is maintained up to 39.4 Mpa, for Example 5c, wherein 11 wt % of PVDC is present while it is 51 .3 Mpa, for Example 1 c, wherein no PVDC is present.

[0139] Finally, the results of Table 4 show surprisingly that the presence of PVDC improves the elongation at break, which increases from 82.5 % to 112.2 % when the amount of PVDC increases from 2 wt % to 11 wt % in Examples 2c to 5c, while it is only 78.4 % for Example 1 c wherein no PVDC is present. Accordingly, improved ductility is generally observed for samples containing PVDC as compared to samples of PVC free of PVDC.

[0140] According to all these results, the inventors demonstrated that PVDC / PVC from a pharmaceutical blister could be recycled mechanically into PVC compounds suitable for common PVC applications.

Claims

ClaimsClaim 1. Stabilized PVDC-containing PVC composition, comprising at least 70 wt% of PVC and from 0.05 wt% to 30 wt% of PVDC and further comprising at least one compound selected from the list consisting of organotin compounds and epoxidized compounds.Claim 2. The stabilized PVDC-containing PVC composition according to claim 1 , wherein organotin compounds are selected from the list consisting of dimethyltin bis(2-ethylhexylthioglycolate), mono methyltin tris-(2-ethylhexylthioglycolate), di-n- octyl tin mercaptide, octyl tin mercaptide, butyl tin mercaptide, methyl tin mercaptide, di-n-octyltin oxide, tetra-n-octyltin, butyltin laurate, di-n-butyltin dilaurate, dimethyltin bis(2-ethylhexylmercaptoacetate), dimethyltin bis(2- ethylhexyl thioglycolate), dimethyl tin mercaptide, dibutyl tin mercaptide, dibutyltin maleate ester, methyltin tris(2-ethylhexyl mercaptoacetate), methyl tin maleates, methyl tin octyl thioacetate, methyl tin lauryl thioacetate, methyl tin carboxylates .Claim 3. The stabilized PVDC-containing PVC composition according to claim 1 or 2, wherein the organotin compound is present in an amount ranging from 0.1 to 10 parts by weight based on 100 parts by weight of polymers PVDC and PVC.Claim 4. The stabilized PVDC-containing PVC composition according to claim 1 , wherein epoxidized compounds are selected from the list consisting of epoxidized soybean oil, epoxidized linseed oil, epoxy esters such as octyl epoxy stearate and 2-ethylhexyl epoxy stearate.Claim 5. The stabilized PVDC-containing PVC composition according to claims 1 or 4, wherein the epoxidized compound is present in an amount ranging from 0.1 to 10 parts by weight based on 100 parts by weight of polymers PVDC and PVC.Claim 6. The stabilized PVDC-containing PVC composition according to any one of claims 1 to 5, further comprising at least one compound selected from the list consisting of beta-diketones and metal beta-diketones salts.Claim 7. The stabilized PVDC-containing PVC composition according to claim 6 comprising at least one compound selected from the list consisting of betadiketones and at least one compound selected from the list consisting of metal betadiketones salts.Claim 8. The stabilized PVDC-containing PVC composition according to claims 6 or 7, wherein beta-diketone is acetyl acetone (AcAc), dibenzoyl methane (DBM), stearoyl benzoyl methane (SBM) or a mixture thereof and, wherein beta-diketone salt is Ca, Zn Mg, Al or mixture thereof salt.Claim 9. The stabilized PVDC-containing PVC composition according to claim 7 comprising methyl tin mercaptide or epoxidized soybean oil, stearoyl benzoyl methane and Ca(acac)2.Claim 10. The stabilized PVDC-containing PVC composition according to any one of the previous claims, further comprising at least one organic compound selected from the list consisting of amino crotonates, nitrogen heterocyclic compounds and organosulfur compounds.Claim 11 . The stabilized PVDC-containing PVC composition according to any one of the previous claims further comprising additives selected from processing aids, lubricants, impact modifiers, fillers, pigments, UV stabilizers, antioxidants, fire retardants, plasticizers or mixture thereof.Claim 12. The stabilized PVDC-containing PVC composition according to any one of the previous claims wherein PVDC comes from recyclates.Claim 13. Method for preparing the stabilized PVDC-containing PVC composition according to any one of the previous claims, comprising adding to at least 70 wt% of PVC and from 0.05 wt% to 30 wt% of PVDC at least one compound selected from the list consisting of organotin compounds and epoxidized compounds.Claim 14. Use of the stabilized composition according to any one of claims 1 to 12 in extrusion and injection molding applications.Claim 15. Item comprising the stabilized composition according to any one of claims 1 to 12.

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