Fungicide Mixtures

Abstract

The invention refers to a fungicide mixture comprising the biocides thiabendazole (TBZ), pyrimethanil (PYM) and fludioxonil (FDL), wherein the total amount of FDL based on the entire amount of biocidal actives is greater than 2 wt. %.

Claims

1. A fungicide mixture comprising the biocides thiabendazole (TBZ), pyrimethanil (PYM) and fludioxonil (FDL), wherein the total amount of FDL based on the entire amount of biocidal actives is greater than 2 wt. %.

2. The fungicide mixture according to claim 1, wherein the weight ratio of the biocides TBZ and PYM are in the range of 20:1 to 1:20.

3. The fungicide mixture according to claim 1, wherein the total amount of TBZ, PYM and FDL based on the entire amount of biocidal actives is greater than 99 wt. %.

4. The fungicide mixture according to claim 1, wherein the mixture is an aqueous suspension containing the biocidal actives in an amount of 1 to 60 wt.

5. The fungicide mixture according to claim 1, wherein the sum of biocidal active and water is 80 to 99 wt. %, based on the mixture.

6. The fungicide mixture according to claim 1, wherein the mixture contains the biocidal actives and water and 0.2 to 5 wt. % of at least one dispersant, 0.05 to 5 wt. % thickener, and 0 to 1 wt. % defoamer.

7. The fungicide mixture according to claim 1, wherein the average particle size of the biocidal actives, TBZ, PYM and FDL is smaller than 100 μm.

8. A process for the manufacturing of the fungicide mixture according to claim 1, wherein the biocides TBZ, PYM and FDL are mixed.

9. The process according to claim 8, comprises the following steps: a. mixing the biocidal actives TBZ, PYM and FDL, and at least one surfactant and water and optionally a wetting agent, a defoaming agent, an in-can preservatives and/or other biocidal actives, b. homogenize the mixture under a) a high speed stirrer in a respective tank or other suitable vessel, c. optionally further treat such homogenized mixture under b) in a bead mill and d. adding optionally a thickener before, during and/or after the milling step.

10. A wallboard comprising a gypsum core and a facing layer, containing the biocides thiabendazole (TBZ), pyrimethanil (PYM) and fludioxonil (FDL), wherein the total amount of FDL based on the entire amount of biocidal actives is greater than 2 wt. %.

11. The wallboard according claim 10 wherein the facing layer is paper or glass fibre mat.

12. The wallboard according to claim 10 whereby the total amount of biocidal actives in the wallboard is from 10 ppm to 3000 ppm.

13. The wallboard according to claim 10, wherein the biocidal actives are included in the gypsum core of the wallboard.

14. The wallboard according to claim 10, wherein the biocidal actives are included in or on the facing layer, which in particular is paper.

15. The wallboard according to claim 10, wherein the biocidal actives is contained in the gypsum core and the facing layer.

16. A process for manufacturing the wallboard according claim 10 wherein the wallboard is treated with a the fungicide mixture according to claim 1 or with the biocides thiabendazole (TBZ), pyrimethanil (PYM) and fludioxonil (FDL) separately, wherein the total amount of FDL based on the entire amount of biocidal actives is greater than 2 wt. %, during the manufacturing process of said wallboard and/or thereafter.

17. The process for manufacturing the wallboard according claim 16, wherein the fungicide mixture according to claim 1 is added during the manufacturing process: a. to a gypsum slurry before the gypsum core is formed and/or b. to the surface of the gypsum core of the wallboard before the facing layer and/or c. to the facing layer making process, and/or d. to the surface of the facing layer.

Description

EXAMPLES

[0118] The following examples are presented to illustrate the invention and are not meant to limit its scope.

[0119] The term synergism is used when the action of a combination of antimicrobial substances is being evaluated. When combining two different actives, several different effects may occur, which usually cannot be foreseen, but have to be determined by adequate testing: [0120] Additive effect [0121] The additive effect of a combination of antimicrobial substances is one in which the effects of the combination is equal to that of the sum of the effect of the individual components. [0122] Synergistic effect [0123] Synergistic action of a combination of antimicrobial substances is present if the effect of the combination exceeds the additive effects of the individual components. [0124] Antagonistic effect [0125] Antagonism is present if a reduced effect of a combination of antimicrobial substances is observed in comparison with the effect of the most effective individual substance.

[0126] The synergism found for the mixtures according to the invention can be determined via the following mathematical formula (cf. F. C. Kull, P. C. Elisman, H. D. Sylwestrowicz and P. K. Mayer, Appl. Microbiol. 9, 538 (1961):

[00001]$\mathrm{synergistic}\mathrm{index}\left(\mathrm{SI}\right)=\frac{Q_a}{Q_A}+\frac{Q_b}{Q_B}$

[0127] where

[0128] Q.sub.a=amount of component A in the active substance mixture which achieves the desired effect, i. e. no microbial growth,

[0129] Q.sub.A=amount of component A which, when used alone, suppresses the growth of the microorganisms,

[0130] Q.sub.b=amount of component B in the active substance mixture which suppresses the growth of the microorganisms,

[0131] Q.sub.B=amount of component B which, when used alone, suppresses the growth of the microorganisms

[0132] If the sum of the ratios for a mixture Q.sub.a/Q.sub.A+Q.sub.b/Q.sub.B=1, additivity is indicated; if it is <1, synergism has occurred; a value of >1 is indicative of antagonism.

Example 1: Synergism of Mixtures of Thiabendazole (TBZ), Pyrimethanil (PYM) and Fludioxonil (FDL)

[0133] To determine the antimicrobial efficacy and synergy of active ingredients mixtures, the Minimum Inhibitory Concentration (MIC) of the active substances and their respective combinations were determined. The Minimum Inhibitory Concentration of a given antimicrobial compound or mixture is the lowest concentration expressed in mg/mL (ppm) that under defined in vitro conditions inhibits the growth of a given micro-organism (for example bacteria, mould fungi, yeasts). The growth of the microorganisms is observed on petri dishes containing a defined nutrient agar.

[0134] The antimicrobial efficacy and synergy of combinations based on TBZ, PYM and FDL were determined. The results obtained in this experiment are summarized in table 1.

TABLE-US-00001 TABLE 1 TBZ/PYM/FDL mixtures - MIC (in ppm) and synergistic indices (SI) TBZ:PYM:FDL = TBZ:PYM:FDL = TBZ:PYM:FDL = TBZ:PYM:FDL = Fungi tested TBZ PYM FDL 1:0.5:0.05 SI 1:0.5:0.1 SI 1:1:0.05 SI 1:1:0.1 SI Alternaria 250 25 5 10 0.22 5 0.14 10 0.26 5 0.15 alternata Aureobasidium 5 175 1500 5 0.65 5 0.63 5 0.50 5 0.49 pullulans Chaetomium 5 250 1500 5 0.71 5 0.63 5 0.50 5 0.51 globosum Paecilomyces 5 90 175 5 0.66 5 0.64 5 0.52 5 0.50 variotii Stachybotris 50 100 5 17.5 0.40 17.5 0.49 25 0.49 7.5 0.18 chartarum

[0135] As can be seen in table 1, by combination of TBZ, PYM and FDL in different ratios and against various fungal species, noticeable synergistic performance effects, indicated by synergistic indices of <1 are achieved.

Example 2: Gypsum Board Efficacy Testing (Paper Protection)

[0136] The fungicide mixtures as of the present invention and of the comparison example to be tested were made as follows:

[0137] The respective actives were mixed in their respective weight ratio (see table 2) together with water and 1 wt. % dispersant Tristyrylphenol ethoxylate (in form of Soprophor® S 25), as thickener 0.1 wt. % of Xanthan gum and 1 wt. % wetting agent non-ionic EO/PO-Copolymer (in form of Pluronic 127 F), where the wt. % are based on the entire mixture and were homogenized with a high speed mixer (IKA Ultra Turrax Labor Dispergator) to give an aqueous suspension having a viscosity measured in accordance with CIPAC 192 method of 500-600 mPas and a particle size of the biocides of smaller than 30 μm measured in accordance with the CIPAC 187 method.

[0138] Fungicide mixtures as described above of following fungicidal actives were applied to the surface of the facing paper sandwiching the gypsum core (total amount of actives in ppm see table 2): [0139] Thiabendazole (TBZ) [0140] Pyrimethanil (PYM) [0141] Fludioxonil (FDL) [0142] Comparative examples: Thiabendazole/Azoxystrobin (AZO) or rather Thiabendazole/Azoxystrobin (AZO)/Fludioxonil (FDL) mixtures

[0143] For examination of the antifungal performance of the inventive mixtures testing directly in gypsum boards provides realistic and practically relevant data for evaluation. To achieve such data, gypsum boards were produced in the laboratory.

[0144] Preparation of Gypsum Board Samples:

[0145] The gypsum board samples were prepared based on a typical slurry recipe

TABLE-US-00002 Gypsum (dry stucco) (CaSO.sub.4 × 0.5 H.sub.2O) 9500 g Tap water 5700 g Starch  285 g

[0146] The gypsum slurry is formed by mixing the dry components and the wet components together. The slurry is then mixed to achieve a homogeneous consistency. For sandwiching the gypsum core, the treated cardboard (see below) with a grammage of appr. 180 g/m.sup.2 was used and after assembly of the plate the hand sheets are dried. The following antifungal compounds and respective formulations were used:

[0147] The test wallboards were produced in the lab and tested according to the standard ASTM G 21-09. Differing from the fungi spectrum as typically used by ASTM G 21-09, in this test the efficacy against Aspergillus hiratsukae was investigated. According to recent publications (Indoor Air. 2017 January; 27(1):6-12), Aspergillus hiratsukae was found to be an important fungus on gypsum wallboards.

[0148] In this trial the facing paper was equipped with the fungicidal mixtures as described above. To treat the paper, the fungicides were applied to the surface of the paperboard by means of an electrically driven film applicator device (Erichsen Unicoater), providing films of uniform thickness. The fungicides mixtures prepared above were applied to the coating machines, to achieve homogeneous suspensions well suited for this process step.

[0149] For every concentration level, 3 test pieces are used in the test. Each sample is placed in a separate petri dish and then inoculated with a mixed inoculum of the fungi mixture. The closed petri dishes are then incubated at 28-30° C. for 28 days. Pre-reading of the samples may be performed at approximately 10 days after inoculation. The activity of the treatments may be assessed visually, using a rating system of 0-4 for growth inhibition of fungal growth.

TABLE-US-00003 Observed Growth Rating None 0 Traces of growth (less than 10%) 1 Light growth (10 to 30%) 2 Medium growth (30 to 60%) 3 Heavy growth (60% to complete coverage) 4 [0150] Results: The results as recorded after 4 weeks testing at 28-30° C. according to the requirements of test method ASTM G 21 are summarized in table 2.

TABLE-US-00004 TABLE 2 ASTM G 21 testing results for Aspergillus hiratsukae Mixtures of TBZ, PYM and FDL applied to paper surfaces, amount in ppm active ingredients (a.i.) on dry paper (no core treatment) Tested specifically against test fungi Aspergillus hiratsukae a.i.'s in ppm Rating Control sample 0 4 TBZ - AZO 1.3:1 175 4 TBZ - AZO 1.3:1 350 4 TBZ - AZO 1.3:1 700 4 TBZ - AZO 1.3:1 875 3 TBZ - AZO 1.3:1 1050 3 TBZ -AZO-FDL 1:1:0.1 200 3 TBZ -AZO-FDL 1:1:0.1 400 3 TBZ -AZO-FDL 1:1:0.1 800 1 TBZ -AZO-FDL 1:1:0.1 1000 1 TBZ -AZO-FDL 1:1:0.1 1200 0 TBZ -PYM-FDL 1:1:0.1 200 1 TBZ -PYM-FDL 1:1:0.1 400 0 TBZ -PYM-FDL 1:1:0.1 800 0 TBZ -PYM-FDL 1:1:0.1 1000 0 TBZ -PYM-FDL 1:1:0.1 1200 0

[0151] Interpretation of Table 2:

[0152] The control sample (untreated paper, no fungicide in the core) exhibits heavy growth of fungi (rating “4”). The TBZ/AZO mixture in the tested concentration range is not good enough to suppress the growth of Aspergillus hiratsukae. The comparative TBZ/AZO/FDL mixture in the tested concentration range only at the upper limit of dosage is effective in control of growth of Aspergillus hiratsukae. In comparison, the inventive and new TBZ/PYM/FDL mixture is able to control growth of Aspergillus hiratsukae at lower dosages, demonstrating the benefit of the new combinations.

TABLE-US-00005 TABLE 3 ASTM G 21 testing results Mixtures of TBZ, PYM and FDL applied to paper surfaces, amount in ppm active ingredients on dry paper (no core treatment). Tested against test fungi of ASTM G 21-09. Organisms which are included in ASTM G 21 comprise Aspergillus niger (ATCC 9642), Aureobasidium pullulans (ATCC 15233) Chaetomium globosum (ATCC 6205), Gliocladium virens (ATCC 6459) and Penicillium pinophilium (ATCC 11797) (as pure culture but also as mixed a.i.'s in ppm Rating Control sample 0 4 TBZ -AZO-FDL 1:1:0.1 200 0 TBZ -AZO-FDL 1:1:0.1 400 0 TBZ -AZO-FDL 1:1:0.1 800 0 TBZ -AZO-FDL 1:1:0.1 1000 0 TBZ -AZO-FDL 1:1:0.1 1200 0 TBZ -PYM-FDL 1:1:0.1 200 0 TBZ -PYM-FDL 1:1:0.1 400 0 TBZ -PYM-FDL 1:1:0.1 800 0 TBZ -PYM-FDL 1:1:0.1 1000 0 TBZ -PYM-FDL 1:1:0.1 1200 0

[0153] Interpretation of Table 3:

[0154] The control sample (untreated paper, no fungicide in the core) exhibits heavy growth of fungi (rating “4”). The gypsum boards manufactured with paper treated with TBZ/AZO/FDL as well as with TBZ/PYM/FDL mixture in the tested concentration range exhibited a good protection against the standard fungi mix as indicated by ASTM G 21-09 test method.