OBPA

OBPA currently accounts for about half of the market for plastic biostabilisers worldwide but this level is slowly diminishing due to environmental and health concerns. These considerations are highlighted by the potential leaching of arsenic from plastic articles 

Available surface active may be limited by external leaching or by internal migration within the plastic 

The levels of arsenic are however fairly low which is often sufficient to achieve the MIC against the majority of fungi and bacteria of 10 mg/1. Upsher Roseblade (a. 19) have reported in 1984 that long-term activity of OPBA exposed at a jungle site is limited due to its 

ISO 846 A (top) and ISO 846 B (bottom) tests for PVC containing OBPA (5% pellet type) at extrusion time of 20 minutes and 120 minutes at 180 °C 

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The compound 10,10 -oxybisphenoxarsine (OBPA) is a unique organoarsenic antimicrobial. The powerful antimicrobial properties of organoarsenics had long been recognized, and there is plentiful treatment of the synthesis of organoarsenic derivatives in the literature. OBPA is used primarily in the plastics industry, where its high temperature stability and low vapor pressure make it the leading industrial antimicrobial in this market (30). 

Based on their thermal stability, compatibility, permanence and broad spectral performance against different fungi, the most common microbiocides are 10,l(E-oxybisphenoxyarsine (OBPA),... 

Known widely by its trade name Vinyzene (Morton now part of Rohm and Haas) this is typically available in 2% or 5% eoneentration in plasticiser or PVC pellets, 10,10 oxybisphenoxarsine (OBPA Figure 25) was initially registered in the United States in 1965. It is used at a dose rate of 0.6-5% based on the total weight of the formulation. 

Because of DCOIT s low water solubility and good UV stability, it makes it ideal for external environments (Figure 45) and permanently or often moisture saturated products such as pool liners, awnings, tarpaulins and so on. Furthermore once released to the environment it is readily degraded which makes it an environmentally favourable alternative to OBPA. Degradation can also be seen with some mercapto tin stabilisers and other reducing agents. 

For antibacterial agents the use of silver and trielosan are most prevalent. For use as an antifungal agent, the traditional products like OBPA are now being replaeed largely by isothiazolinones. All products have some deficiencies or gaps in the spectrum of their aetivity and some mixed products are therefore offered. With mixed products, there will be some issues of patent to be avoided. 

The Intercide OBF microbiocides are based on the active ingredient 2-n-octyl-4-isothiazolin-3-one (OIT). The products are effective fungicides which are widely used in paints and coatings. Characteristics and applications are described for Intercide grades OBF-8-DINP, and OBF-8-ED6. OIT is highly compatible with PVC and offers advantages over OBPA in terms of resistance to UV radiation. 

Akcros Chemicals (in the United States—Akcros Chemicals America, New Brunswick, NJ) makes a few brands of fungicidal products based on OBPA as the active ingredient, all under a name Intercide ABF, which use PVC or PVC/PVA copolymer as carriers, among other liquid and solid carriers. Activity of one of those products, Intercide ABF-2-DIDP, in two different tests is shown in Table 13.10. Other set of data is shown in Table 13.8. 

TABLE 13.10 Activity of an OBPA-based biocide (Intercide ABF-2-DIDP) versus single-test fungi, NSA, and Disk tests (plastisol folmulation)... 

Note 1 Intercide ABF-2-DIDP consists of a 2% solution of OBPA in DIDP (a plasticiser). 

A similar biocide, Intercide ABF-5-DIDP in the amount of 0.05 and 0.1% (w/w) of the active principle (OBPA), that is, 1.0 and 2.0% (w/w) of the commercial biocide, was tested in a woodfiber-PVC composite (data obtained courtesy of Akcros Chemicals). The unprotected composite (no biocides) did not prevent an active... 

The data in Table 13.11 show a certain level of performance of the biocide against all the test fungi, though its level is somewhat below that for OBPA (Table 13.10). 

For example, in South Ohio, Folpet showed excellent data in the natural environment, and practically no activity in the ASTM D 3273 test copper thiocyanate and zinc caprylate, on the contrary, showed excellent chamber activity, but no activity at all in the natural setup. OBPA at 1% w/w also showed excellent activity in the chamber, but no activity outdoors. 

In the New Jersey test there was also very poor correlation between biocide protection in the environmental chamber and outdoors. Many biocides showed excellent indoors protection, such as OBPA, copper hydroxide, chlorothalonil, bethoguard, but none of them showed fairly noticeable protective activity in the natural conditions (Table 13.17). Only two biocides, IPBC and Folpet, have shown what can be considered as a fair, but still not very good correlation of their biocidal activity in the environmental chamber and outdoors. 

Oxybisphenoxarsinine (OBPA) 8 has been prepared by treatment of 1 with an 8-15% NaOH solution at the molar ratio 1 1.2-1.8 in the presence or absence of a phase-transfer catalyst (Scheme 4) <2003MIP1415620>. 

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