Impact modifiers for PVC

Poly(vinyl chloride) (PVC) is the largest and most important resin for the application of emulsion-based impact modifiers. In 1999, over 25 million tons (50 billion lb) of PVC were produced worldwide [109,110]. Virtually aU of the emulsion-made impact modifiers for PVC applications are of the core-shell variety, with the largest commercial producers being Rohm and Haas, AtoFina, Kaneka and Mitsubishi Rayon. 

PVC is a unique polymer in that, while the neat resin is virtually useless, it can be modified by various additives to provide a tremendous range of properties, ranging from soft and flexible to rigid and tough. PVC is an inherently tough polymer, but is 

unplasticized PVC is used extensively in the building and construction markets. Pipe, vinyl siding, and window profiles, all manufactured via profile or sheet extrusion, represent the largest building product markets. Examples of some formulations are shown in Tab. 14-4. 

Rohm and Haas Paraloid KM-334 General purpose all-acrylic 

In Europe, several manufacturers provide pre-toughened PVC resins or concentrates. These are an example of in-situ impact modification, where the rubber polymer is introduced and grafted into the matrix during the PVC polymerization [127-129]. These systems provide excellent impact properties without the need for a separate hard shell or additive step. The corresponding disadvantage to the for-mulator and processor is the lack of flexibility in adjusting the additive types, levels and morphology. 

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Styrene-based plastics are used somewhat in blow mol ding but not as much as linear polyethylene and PVC. HIPS and ABS are used in specialty botdes, containers, and furniture parts. ABS is also used as one of the impact modifiers for PVC. Clear, tough bottles with good barrier properties are blow-molded from these formulations. 

The use and benefits of liquid, partially hindered phenols, such as Irganox 1141, as effective chain-stoppers and antioxidants in PVC polymerisation and as heat stabilisers for MBS (impact modifiers for PVC) and PVC plasticisers are demonstrated. 

ABS-type resins are used as impact modifiers for PVC, but the resultant blend has insufficient transparency for application in clear bottles. Transparency can be obtained by grafting PMMA onto crosslinked PBD (5) or poly (butyl acrylate) (6) which has been previously grafted onto PS (Diagram 4). In this case the PMMA branch is compatible with PVC by virtue of its solubility parameter, and optical clarity results from suitable component ratios in the graft copolymer so that the refractive index matches that of PVC. The desired results are not obtained if a copolymer of methyl methacrylate and styrene is... 

S-PVC calendering formulation. [Data from ParaloidBTA-780S mbs impact modifier for PVC packaging applications. DOW 874-01721-0810.]... 

Uses Antioxidant for polyolefins, polyamides, polyesters, PVC, PS, rubbers, food-grade polymers impact modifier for PVC Regulatay FDA 21CFR 178.2010 Manuf./Dlstrlb. Aldrich Ciba Spec. Chems7/tddit. GE Spec. 

The development of clear poly(vinyl chloride) plastics has been given considerable attention. For example, Petrich (1972) showed that methacrylate-butadiene-styrene (MBS) impact modifiers for PVC can impart toughness as well as clarity. Acrylic modifiers are also described by Ryan and Crochowski (1969), Ryan (1972), and Souder and Larson (1966). 

Uses Clear impact acrylic characterized by exc. gamma ray recovery, abuse/scratch resist. used for food/drug pkg., medical devices, office accessories, small appliances, toys processing aid, impact modifier for PVC Trade Name Synonyms Zylar 90-495 [NOVA Chems. http //www.novachem.com]-, Zylar 93-541 t[NOVA Chems. 

Uses Impact modifier for PVC processing aid Trade Name Synonyms Durastrength 200 [Atofina httpJ/www.atofinachemicals.com, Atofina SA http //www.atofina.com]... 

J.T. Lutz, D. Dunkelberger (eds.). Impact Modifiers for PVC. The History and Practice (Wiley, New York, 1992)... 

Kane Ace-FM Acrylic low gloss impact modifiers for PVC Kanegafuchi Chemicals... 

An alternative approach to toughening PVC is represented by DuPont Dow Elastomers Tyrin range of chlorinated polyethylene impact modifiers for PVC profiles, which are said to offer better processing characteristics and filler compatibility than acrylics. Tyrin can be used for wire and cable insulation, and is the most widely used impact modifier for those grades of ignition resistant ABS that need to contain a brominated flame retardant. 

Enlite from DuPont Dow Elastomers is claimed to be the lowest density impact modifier for PVC on the market, and is targeted at the construction industry. The required dose is said to be low in highly filled grades of PVC. 

Impact modifiers for PVC include methyl butadiene styrene (MBS) and acrylics. MBS modifiers improve the impact strength of PVC compounds without sacrificing the other characteristics. They are used for a variety of rigid and semirigid applications and processes, such as blow moulding of bottles, calendering of film and sheet, extrusion of profiles, and injection moulding of technical parts. Some types can also be tailored to suit specific requirements. 

Acrylic Weather-resistant impact modifiers for PVC Durastrength. Metablen -Elf Atochem Kane Ace - Kaneka Paraloid - Rohm and Haas... 

Kane Ace FM is an acrylic high weather-resistant impact modifier for PVC products such as window profiles, siding and business machine housings, based on Kaneka technology. It imparts good processability, gelation behaviour, heat stability and low die-swell in lead-stabilized compounds, at addition levels of 8 phr. 

SBS and SEBS block copolymers have been employed to impact modify HIPS, PPO/HIPS and various polyolefins. Maleic anhydride modified SEBS offers impact modification of polyamides and polyesters via reactive compatibilization. Chlorinated polyethylene (< 42 wt% Cl) is employed as an impact modifier for PVC, where weatherability is a primary concern [121]. Ethylene-(meth)acrylic acid copolymers and their neutralized versions (ionomers) have been utilized as impact modifiers for polyamides. PBT and PET impact modification with the poly(ester-ether block copolymer) (PBT-poly(tetramethylene oxide) (AB) ) yielded utility in automotive fascia applications. These products have been available under the tradenames Lomod (GE), Bexloy (duPont) andRiteflex (Hoechst-Celanese) [3]. 

Chlorinated polyethylene (CPE) After a starting polyethylene has been chlorinated, the resulting material is typically 25-50 wt.% chlorine. The properties range from thermoplastic to elastomeric. Applications for CPE include automotive hoses, tubing, and wire jacketing plus extensive membranes for roofing. It ean be an impact modifier for PVC. 

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