Water-resistant composition

Abstract

The present invention provides a water-resistant composition for adsorbing volatile organic compounds (VOCs) derived from organic matter including: a) palladium doped hydrogen-ZSM-5, wherein the Si:AI ratio of the hydrogen-ZSM-5 is less than or equal to 200:1; and b) at least one water-soluble binder. The invention also provides a method for using the water-resistant composition for adsorbing volatile organic compounds (VOCs) derived from organic matter.

Claims

1. A water-resistant composition for adsorbing volatile organic compounds (VOCs) derived from organic matter comprising: a) palladium doped hydrogen-ZSM-5, wherein the Si:AI ratio of the hydrogen-ZSM-5 is less than or equal to 200:1; and b) at least one water-soluble binder, wherein the water-soluble binder is selected from the group consisting of: at least one polyvinyl alcohol having a M.sub.w from 27,000 to 215,000 and a degree of hydrolysis ?80%; guar gum; gum arabic; 2-hydroxyethylcellulose; hydroxypropyl methylcellulose; and polyethylene oxide having a M.sub.w from 100,000 to 1,000,000.

2. A water-resistant composition according to claim 1, wherein the Si:AI ratio of the hydrogen-ZSM-5 is less than or equal to 100:1.

3. A water-resistant composition according to claim 1, further comprising one or more binder modifiers, driers, plasticisers, fillers, surfactants, pigments or preservatives.

4. A method for adsorbing volatile organic compounds (VOCs) derived from organic matter, comprising applying a water-resistant compound to the volatile organic compounds, wherein the water-resistant composition comprises: a) palladium doped hydrogen-ZSM-5, wherein the Si:AI ratio of the hydrogen-ZSM-5 is less than or equal to 200:1; and b) at least one water-soluble binder, wherein the water-soluble binder is selected from the group consisting of: at least one polyvinyl alcohol having a M.sub.w from 27,000 to 215,000 and a degree of hydrolysis ?80%; guar gum; gum arabic; 2-hydroxyethylcellulose; hydroxypropyl methylcellulose; and polyethylene oxide having a M.sub.w from 100,000 to 1,000,000.

5. The method according to claim 4, wherein the Si:AI ratio of the hydrogen-ZSM-5 is less than or equal to 100:1.

6. The method according to claim 4, the water-resistant composition further comprising one or more binder modifiers, driers, plasticisers, fillers, surfactants, pigments, or preservatives.

7. The method according to claim 4, wherein the organic matter consists of perishable organic goods.

8. The method according to claim 7, wherein the perishable organic goods comprise items of food or horticultural produce.

9. The method according to claim 8, wherein the items of food comprise fruit and/or vegetables.

10. The method according to claim 8, wherein the horticultural produce comprises plants and/or cut flowers.

11. The method according to claim 4, wherein the organic matter comprises refuse.

12. The method according to claim 4, wherein the organic matter is contained in a storage container or package.

13. The method according to claim 12, wherein the water-resistant composition is incorporated into, or into part of, the storage container or package.

14. The method according to claim 4, wherein the water-resistant composition is incorporated into a label comprising a substrate.

15. The method according to claim 12, wherein the storage container or package is a refuse receptacle.

16. The method according to claim 4, wherein the VOCs are adsorbed at a temperature of from ?10? C. to 50? C.

17. The method according to claim 4, wherein the VOCs are selected from the group consisting of ethylene, formaldehyde and acetic acid.

18. The method according to claim 4, wherein the water-resistant composition is used in an environment comprising less than 10 vol % of oxygen.

19. The method according to claim 18, wherein the environment is a controlled atmosphere or modified atmosphere environment.

20. The method according to claim 18, wherein the oxygen is present in the range between >0.5 vol % and <10 vol %.

21. The method according to claim 4, wherein the VOCs are adsorbed to a level of less than or equal to 0.10 ppm.

22. An article comprising: packaging or a container configured to hold organic matter; and a water-resistant composition comprising: a) palladium doped hydrogen-ZSM-5, wherein the Si:AI ratio of the hydrogen-ZSM-5 is less than or equal to 200:1; and b) at least one water-soluble binder, wherein the water-soluble binder is selected from the group consisting of: at least one polyvinyl alcohol having a M.sub.w from 27,000 to 215,000 and a degree of hydrolysis ?80%; guar gum; gum arabic; 2-hydroxyethylcellulose; hydroxypropyl methylcellulose; and polyethylene oxide having a M.sub.w from 100,000 to 1,000,000.

23. The article according to claim 22, wherein the article is a label or sheet.

24. An aqueous formulation comprising: a) palladium doped hydrogen-ZSM-5, wherein the Si:AI ratio of the hydrogen-ZSM-5 is less than or equal to 200:1; b) at least one water-soluble binder, wherein the water-soluble binder is selected from the group consisting of: at least one polyvinyl alcohol having a M.sub.w from 27,000 to 215,000 and a degree of hydrolysis ?80%; guar gum; gum arabic; 2-hydroxyethylcellulose; hydroxypropyl methylcellulose; and polyethylene oxide having a M.sub.w from 100,000 to 1,000,000; c) and water.

25. An admix comprising: a) palladium doped hydrogen-ZSM-5, wherein the Si:AI ratio of the hydrogen-ZSM-5 is less than or equal to 200:1; b) at least one water-soluble binder, wherein the water-soluble binder is selected from the group consisting of: at least one polyvinyl alcohol having a M.sub.w from 27,000 to 215,000 and a degree of hydrolysis ?80%; guar gum; gum arabic; 2-hydroxyethylcellulose; hydroxypropyl methylcellulose; and polyethylene oxide having a M.sub.w from 100,000 to 1,000,000.

Description

(1) In order that the invention may be more fully understood the following non-limiting Examples are provided by way of illustration only and with reference to the accompanying figures in which:

(2) FIGS. 1 and 2 illustrate the ethylene removal abilities of PVA compositions comprising palladium doped hydrogen-ZSM-5.

(3) FIG. 3 shows the ethylene removal abilities of PVA/PTFE compositions comprising palladium doped hydrogen-ZSM-5.

(4) FIG. 4 illustrates the ethylene removal abilities of various gums and cellulosic compositions comprising palladium doped hydrogen-ZSM-5.

(5) FIG. 5 shows the ethylene removal abilities of various compositions comprising palladium doped hydrogen-ZSM-5 which were subjected to different drying temperatures and times.

(6) FIG. 6 illustrates the ethylene removal ability of a fresh and aged sample of PVA-6.

EXAMPLES

Example 1

(7) Preparation of Doped Supports

(8) The palladium doped hydrogen-ZSM-5 was prepared using the incipient wetness impregnation method. Typically 20 g of the hydrogen-ZSM-5 was impregnated with a nitrate salt or chloride salt of palladium, and then dried at 110? C. before being calcined in air at 500? C. for 2 hrs to form the palladium doped hydrogen-ZSM-5.

Example 2

(9) Ethylene Adsorption Capacity Experiments

(10) The ethylene adsorption capacity of palladium doped hydrogen-ZSM-5 was compared against palladium doped sodium-ZSM-5.

(11) TABLE-US-00001 Ethylene Adsorption .sup.(c) 2.5 wt % Pd/Na-ZSM-5 .sup.(a) 282 ?l/g (comparative) 2.5 wt % Pd/H-ZSM-5 .sup.(b) 4162 ?l/g .sup.(a) 2.5 wt % palladium doped sodium-ZSM-5 was prepared using the incipient wetness impregnation method. Thus, 5 g of sodium-ZSM-5 was impregnated with palladium nitrate solution, dried at 105? C. and calcined at 500? C. for 2 hours. .sup.(b) 2.5 wt % palladium doped hydrogen-ZSM-5 was prepared using the incipient wetness impregnation method. Thus, 5 g of hydrogen-ZSM-5 was impregnated with palladium nitrate solution, dried at 105? C. and calcined at 500? C. for 2 hours. .sup.(c) the ethylene adsorption capacity was tested as follows: measurements were carried out in a plug flow reactor at 21? C. with 0.1 g doped support of particle size 250-355 ?m with a flow rate of 50 ml/min of gas comprising 10% O.sub.2, 200 ppm C.sub.2H.sub.4, ~1% water (where present) and balance He/Ar.

(12) As can be seen from the data provided above, the ethylene adsorption capacity for palladium doped hydrogen-ZSM-5 is 4162 ?l/g as compared to 282 ?l/g for the palladium doped sodium-ZSM-5 i.e. the palladium doped hydrogen-ZSM-5 has an ethylene adsorption capacity nearly fifteen times greater than palladium doped sodium-ZSM-5.

Example 3

(13) Preparation of Water-Resistant Compositions

(14) Aqueous stock solutions of polymer binders were prepared by dissolving the polymer in water and stirring with heating until the polymer had completely dissolved. For polyvinyl alcohol (PVA) based compositions this required >90? C. for a completely clear solution. All solutions were prepared at 4.3 wt. % concentration, unless otherwise stated.

(15) The polymer solution (18 g of 4.3 wt. % polymer) was weighed out and mixed with palladium doped hydrogen-ZSM-5 (20 g). Mixing was achieved with a Speed Mixer? set at 3000 rpm for 30 sec. This equated to a dry weight composition of 4.3% polymer and 95.7% palladium doped hydrogen-ZSM-5 powder. If the viscosity was too high, a 2.5% solution was prepared (equivalent to 2.15% dry weight).

(16) Ethylene Removal Tests

(17) The formulations were printed onto Tyvek? paper using a 25 ?m k-bar. Samples were left to dry in air overnight and then stored in sealed plastic bags for ethylene removal testing. The ethylene removal experiments were carried out at room temperature in an unstirred batch reactor (0.86 L) with a 3?3 inch (7.62?7.62 cm) printed sheet and an initial gas composition of 550 ?L L.sup.?1 (i.e. 550 ppm) ethylene, 40% (v/v) air balanced with Ar. Selected gas concentrations were measured at hourly intervals with a Varian CP-4900 Micro GC (Varian Inc., CA). Gas samples (40 ms duration) were taken via an automated recirculating sampling system. Column and injector temperatures were set at 60 and 70? C., respectively. The 0.15 mm diameter, 10 m long column was packed with PoraPLOT Q. Ethylene and CO.sub.2 were calibrated against 10 ?L L.sup.?1 ethylene balanced with air and 5% (v/v) CO.sub.2 balanced with Ar (Air Products Europe, Surrey, UK). A thermal conductivity detector was used with He carrier gas at 276 kPa inlet pressure. Peak integration was carried out within the Varian STAR software.

(18) A graph of ethylene removal rate against time was plotted to assess the quality of the coating. Water resistance and adhesion was also checked by spraying water onto the surface and by folding the Tyvek? to look for flaking or cracking. Samples were only tested for ethylene uptake if the adhesion was considered acceptable. In the tables, the term good adhesion means the coating did not fall off when rubbed or folded once. Good water resistance means the coating did not fall off when sprayed with a jet of water.

Example 4

(19) PVA Compositions

(20) PVA compositions were prepared and tested as described in Example 3.

(21) TABLE-US-00002 TABLE 1 PVA compositions Coating Dry Coating resistance to Sample Polymer adhesion water jet PVA-1 M.sub.w ~205k (Mowiol? 40-88), 88% hydrolysed Good Good PVA-2 M.sub.w 85-146k, 99+% hydrolysed, Aldrich Good Good PVA-3 M.sub.w 89-98k 99+% hydrolysed, Aldrich Good Good PVA-4 M.sub.w 130k 99+% hydrolysed Good Good PVA-5 M.sub.w 145k (Mowiol? 28-99) 99+% hydrolysed Good Good PVA-6 M.sub.w 146-186k, 99+% hydrolysed Good Good PVA-7 4.3% stock solution (PVA (75%)-PEG (25%) Poor All removed (comparative) PVA-8 2.5% stock solution PVA (75%)-PEG (25%) Poor All removed (comparative) PVA-9 4.3% MOWIOL? PVA 4-88 M.sub.w 31k Good Poor (comparative) 88% hydrolysed PVA-10 4.3% MOWIOL? PVA 4-98 M.sub.w 27k Good Good 98% hydrolysed PVA-11 4.3% MOWIOL? PVA 40-88 M.sub.w 195k Good Good 88% hydrolysed PVA-12 4.3% MOWIOL? PVA 40-88 M.sub.w 205k Good Good 88% hydrolysed PVA-13 4.3% PVA (M.sub.w146-186)/PFTE (0.5%) Good Good PVA-14 4.3% PVA (M.sub.w146-186)/PFTE (1%) Good Good PVA-15 4.3% PVA (M.sub.w146-186)/PFTE (4.3%) Good Good

(22) FIG. 1 illustrates that PVA-7 and PVA-8 exhibited no significant ethylene adsorption capacity. The other PVA samples tested, however, demonstrated efficient ethylene removal (see FIGS. 1 and 2).

(23) Without wishing to be bound by theory, it appears that the PVAs which exhibited good dry coat adhesion and water-resistance are those which have a higher % hydrolysis and/or M.sub.W. While low M.sub.W and low % hydrolysis PVAs may provide flexible/softer coatings, the PVAs tested in this instance do not appear to be sufficiently water-resistant after drying.

(24) Samples made directly from PTFE solutions showed poor adhesion to Tyvek? and so were not tested further in ethylene uptake experiments. It was found, however, that small amounts of PTFE added to PVA formulations did not significantly affect the rate of ethylene removal (see FIG. 3).

(25) The high molecular weight PVA may cause some cracking when prepared into a coating and then folded or creased. PVA-15 (which comprises PTFE) appears to be more flexible than PVA-13 or PVA-14 and therefore does not crack when creased in the same way. Without wishing to be bound by theory, it is possible that the hydrophobic PTFE acts as a binder modifier to introduce greater flexibility to the coating.

Example 5

(26) Gums and Cellulosic Compositions

(27) Gums and cellulosic compositions were prepared and tested as described in Example 3.

(28) TABLE-US-00003 TABLE 2 Gums and Cellulosic Compositions Coating Dry coat resistance to Sample Polymer adhesion water jet A 1% Guar gum stock Good, some Good dusting B Gum arabic (5%) Good Good C 2-Hydroxyethylcellulose Good Good D 2.5% hypromellose, Acceptable Good highly viscous adhesion

(29) FIG. 4 shows that the both the gums and cellulosic compositions A-D performed well in adsorbing ethylene.

Example 6

(30) Polyethylene Oxide Compositions

(31) Polyethylene oxide compositions were prepared and tested as described in Example 3.

(32) TABLE-US-00004 TABLE 3 Polyethylene Oxides Coating Dry coat resistance to Sample Polymer adhesion water jet E 2.5% Polyethylene oxide Good Acceptable (PEO) M.sub.w 1,000,000 F 2.5% Polyethylene oxide Good Good (PEO) M.sub.w 100,000

(33) FIG. 4 illustrates that the polyethylene oxide compositions E and F performed well in adsorbing ethylene.

Example 7

(34) Variation in Drying Temperatures and Times

(35) A variety of coatings were subjected to different drying temperatures and times. The experimental conditions described in Example 3 were otherwise unchanged.

(36) TABLE-US-00005 TABLE 4 variation in drying temperatures and times Drying Sample Polymer temperature Time/hour PVA-6 M.sub.w 146-186 99+% hydrolysed 70? C. 2 hours PVA-16 4.3% PVA (M.sub.w146-186)/PFTE 40? C. 30 mins (4.3%) PVA-16 4.3% PVA (M.sub.w146-186)/PFTE 40? C. 2 hours (4.3%) C 2-Hydroxyethylcellulose 70? C. 2 hours

(37) FIG. 5 shows that coatings made from PVA (M.sub.W 146-186, 99+% hydrolysed) or PVA/PTFE survive heating at 40? C. and 70? C. This suggests that drying is not an issue for these formulations. Sample C (2hydroxyethylcellulose) also performed well after drying a sheet at 70? C. for 2 hours.

Example 8

(38) Sheet Ageing

(39) PVA coating PVA-6 was retested after 12 weeks storage (at room temperature in a sealed plastic bag) to assess whether there was any deactivation with storage time. FIG. 6 illustrates no significant deactivation occurred over 12 weeks at room temperature for this sample.

Example 9

(40) Submersion in Water

(41) Sample coatings which had passed the water spray test and showed good ethylene uptake rates were also tested for longer term water resistance. A square ?2 cm?2 cm was cut out from the print and submerged in water. The samples were checked after 5 min, 2 hours and 12 hours for adhesion and softening.

(42) TABLE-US-00006 TABLE 5 submersion in water for 5 minutes Sample 5 mins in water PVA-1 Coating intact PVA-2 Coating intact PVA-3 Coating intact PVA-4 Coating intact PVA-5 Coating intact PVA-6 Coating intact PVA-10 Coating intact PVA-11 Coating intact PVA-12 Coating intact A Coating intact B Coating intact C Coating intact D Coating intact E Coating intact F Coating intact

(43) TABLE-US-00007 TABLE 6 submersion in water for 2 hours Sample 2 hours in water PVA-1 Coating intact PVA-2 Coating intact PVA-3 Coating intact PVA-4 Coating intact PVA-6 Coating intact PVA-11 Coating intact PVA-12 Coating intact C Coating intact E Coating intact

(44) TABLE-US-00008 TABLE 7 submersion in water for 12 hours Sample 12 hours in water PVA-4 Coating intact PVA-6 Coating intact C Coating intact

(45) From these experiments it was found that a variety of polymer binders survived 5 minutes, 2 hours or 12 hours in water.

Example 10

(46) Submersion in Water

(47) Samples PVA-2, PVA-4, PVA-5 and PVA-6 (which had been prepared according to Example 3) were redried at 40? C. for 3 hours and subjected to the water immersion test as described in Example 9. This was done to ensure that the PVA had adhered completely to the Tyvek? and to assess whether this improved the adhesion.

(48) TABLE-US-00009 TABLE 8 Results of submerging PVA coated (40? C.) sample in water for up to 12 hours Sample 5 min in water 2 h in water 12 h in water PVA-2 Coating intact Coating intact Coating intact; removed (40? C.) only by hard rubbing PVA-4 Coating intact Coating intact Coating intact; removed (40? C.) only by hard rubbing PVA-5 Coating intact Coating intact Coating intact; removed (40? C.) only by hard rubbing PVA-6 Coating intact Coating intact Coating intact; removed (40? C.) only by hard rubbing

(49) Table 8 shows a trend of improved water-resistance for the PVA samples with higher M.sub.W. This was most noticeable after 12 hours submergence in water. The higher M.sub.W PVA samples could only removed by firm rubbing of the coating.