Cross-linked plastic material with an intrinsic antimicrobial effect based on vinyl esters and vinyl ester urethanes

Abstract

The present invention is directed to a radically curable chemical composition in form of a resin for the production of materials having an intrinsic antimicrobial effect, to the applications of these materials, to a method for the preparation of these resins and materials, and to the use of an amino-functionalized styrene derivative as a reactive diluent. The cross-linked plastic materials formed after curing have an intrinsic antimicrobial effect without the use of additional biocides.

Claims

1. A resin composition for the preparation of products having an antimicrobial effect, containing a) vinyl ester and/or vinyl ester urethane, and b) styrene derivative as a reactive diluent, wherein for each double bond in component a) there are 0.5 to 8 styrene derivative molecules present in the composition, wherein component b) is amino-functionalized and the amino functionality is of the formula
—(CH.sub.2).sub.q—NH.sub.pR.sup.1R.sup.2A.sub.p, wherein q is either 1 or 2, p is 0 or 1, R.sup.1 is selected from H, linear or branched or cyclic alkyl radicals comprising 1 to 10 carbon atoms, R.sup.2 is a linear or branched or cyclic alkyl radical comprising 1 to 10 carbon atoms, A is the anion of an acid, and the amine nitrogen N of the above formula is neutrally (p=0) or positively (p=1) charged, wherein the amino-functionalized styrene derivative is selected from the group consisting of ##STR00005## and mixtures thereof, wherein R1 is hydrogen and R2 is selected from the group consisting of isopropyl, tert-butyl and tert-pentyl.

2. A composition according to claim 1, wherein the vinyl ester urethane contains amino-group-containing chain extenders.

3. A composition according to claim 1, wherein said composition contains at least 20 wt % of a mixture of components a) and b).

4. A composition according to claim 1, wherein for each double bond in component a) there are 1.5 to 4 styrene derivative molecules present in the composition.

5. A method of coating, painting, pouring, dipping, laminating, gap impregnation, spinning, gluing, resin injection, compression moulding, injection moulding, profile drawing, filling or wrapping, said method comprising curing the composition of claim 1.

6. A method for the preparation of cured products, wherein a composition according to claim 1 is cured.

7. A product having an antimicrobial effect including a cured composition according to claim 6.

8. The product according to claim 7 selected from the following products: furniture and furniture coatings, adhesives, veneers and paper laminates, knobs, handles, buttons, switches and housings, panels, floors, pipes, profiles, tanks and containers for drinking water, food and oils, linings, roof coatings, light panels, sealants, cements, plugging compounds, polymer concrete, agglomarble, kitchen sinks, shower trays, bathtubs, sinks, toilet seats, garden furniture, garden fences, facade panels, basement window wells, vehicle parts, lights, wind power plants, impregnations, binders, sealing compounds, fillers and/or reaction mortar, coatings, varnishes, gel coats, top coats, ships, boats or recreational items.

9. The composition of claim 1 wherein R.sup.2 is tert-pentyl.

10. A composition according to claim 1, wherein said composition contains at least 80 wt % of a mixture of components a) and b).

Description

WORKING EXAMPLES

(1) Preparation of the Amino-Functionalized Styrene Derivative (General Procedure)

(2) 200 ml of water and 42 g (1.05 mol) NaOH were placed in a 1,000 ml flask and once completely dissolved, they were added to 1.05 mol of the corresponding amine. While stirring, the flask was heated to 60-85° C. and during about 75 minutes, a solution of 53.42 g (0.35 mol) chlorine methylstyrene and 150 ml of THF was added dropwise. Once all of it had been added dropwise, the reaction flask was left in the oil bath for a total reaction period of 4-120 hours under constant stirring. The reaction time and reaction temperature depend on the amine used. The analysis was performed by means of GC-MS. The purification was effected by means of vacuum distillation.

(3) According to this general procedure, amino-functionalized styrene derivatives were synthesized using the following amines: tert. butylamine, n-propylamine, isopropylamine, n-butylamine, sec. butylamine, isobutylamine, n-pentylamine, 3-pentylamine, isopentylamine, tert. pentylamine, cyclopentylamine, cyclohexylamine, diethylamine, diisopropylamine.

(4) The tert. butylaminomethylstyrene obtained with tert. butylamine was abbreviated as TBAMS. It was produced at a reaction temperature of 70° C. and a subsequent stirring time of 24 hours with a conversion of >98% and a selectivity of >98%. In the vacuum distillation, the boiling point of TBAMS 1 was 115° C. at 6 mbar.

Example 1

(5) In a brown glass bottle, 44.26 g (35 wt %) of the bisphenol A-based vinyl ester CRYSTIC VE 671 manufactured by Scott Bader and 82.29 g (65 wt %) of the amino-functionalized reactive diluent TBAMS (tert. butylaminomethylstyrene) were placed on a dolly for 14 days to dissolve, and once completely dissolved, 2 wt % of the azo initiator V601 [2,2′-azobis[dimethyl 2,2′-azobis(2-methylpropionate)] manufactured by Wako was added. Then, about 8 g of the transparent homogeneous resin initiator mixture was placed in each of various glass petri dishes and cured in a nitrogen atmosphere at 70° C. for 2 hours, at 80° C. for 2 hours and at 90° C. for 2 h.

(6) The resulting fully cured VE thermoset was tack-free and hard. The VE thermoset was practically odourless and showed excellent antimicrobial properties.

Example 2

(7) Into a three-necked flask, 0.25 g (600 ppm) of 3,5-di-tert.-butyl-4-hydroxyltoluene (BHT), 0.03 g (60 ppm) of 4-methoxyphenol (HQME), 57.68 g (0.4 mol) of 2-hydroxypropyl methacrylate (HPMA), 32.30 g (0.2 mol) of tert. butyl bis-hydroxyethylamine (TBBHEA) and 84.90 g (20 wt % based on the full VEU resin) of diethylaminomethylstyrene (DEAMS) were measured. The mixture was heated to 65° C. under constant stirring. Once the reaction temperature had been reached, 101.08 g (0.404 mol) of Lupranat MI manufactured by BASF SE (49 wt % of 4,4′-methylene diphenyl diisocyanate, 49 wt % 2,4′-methylene diphenyl diisocyanate, 2 wt % 2,2′-methylene diphenyl diisocyanate) was added dropwise so that the reaction mixture reached a constant temperature between 70° C. and 80° C. The resulting heat was removed via a water bath. Once all had been added dropwise (40 minutes), the mixture was subsequently stirred for 1 hour. Then 148.75 g (35 wt % based on the total VEU resin) of tert. butylaminomethylstyrene (TBAMS) was added and stirred for another 5 minutes.

(8) For curing, 2 wt % of the azo initiator V601 [dimethyl 2,2′-azobis(2-methylpropionate)] manufactured by Wako was added and fully dissolved in the resin. Then about 8 g of the transparent homogeneous resin initiator mixture was placed in each of various glass petri dishes and cured in a nitrogen atmosphere at 70° C. for 2 hours, at 80° C. for 2 hours and at 90° C. for 2 hours.

(9) The resulting fully cured VEU resin thermoset was hard, tack-free, virtually odourless and showed excellent antimicrobial properties.

(10) In this embodiment, the ratio of styrene derivative to double bond is 3.07:1.

Example 3

(11) In a three-necked flask were placed 0.25 g (600 ppm) of 3,5-di-tert.-butyl-4-hydroxyltoluene (BHT), 0.03 g (60 ppm) of 4-methoxyphenol (HQME), 57.68 g (0.4 mol) of 2-hydroxypropyl methacrylate (HPMA), 32.30 g (0.2 mol) of tert. butyl bis-hydroxyethylamine (TBBHEA) and 200 ml of water-free acetone. The mixture was heated to 65° C. under constant stirring. Once the reaction temperature had been reached, 101.08 g (0.404 mol) of Lupranat MI manufactured by BASF SE (49 wt % of 4,4′-methylene diphenyl diisocyanate, 49 wt % 2,4′-methylene diphenyl diisocyanate, 2 wt % 2,2′-methylene diphenyl diisocyanate) was added dropwise so that the reaction mixture reached a constant temperature between 65° C. and 75° C. The resulting heat was removed via a water bath. After all had been added dropwise (25 minutes), the mixture was stirred for 1 hour. Subsequently, the contents of the flask were divided approximately equally between three single-neck flasks weighed empty and an amount of 20.00 g of tert. butylaminomethylstyrene (TBAMS) was placed in each. The acetone was then separated out from all flasks, first at atmospheric pressure and then under vacuum, until a constant total flask mass was reached. After reweighing, the VEU mass present in the each flask was calculated.

Example 3A

(12) Preparation and Curing of the VEU Resin with 65 wt % TBAMS

(13) To the flask containing 66.09 g of VEU and 20.00 g of TBAMS, a further 102.40 g of TBAMS was added to prepare a VEU resin with a total of 65 wt % TBAMS. Subsequently, 2 wt % of the azo initiator V601 [dimethyl 2,2′-azobis(2-methylpropionate)] manufactured by Wako was added and the flask contents were homogenized. About 8 g of the transparent homogeneous resin initiator mixture was placed in each of various glass petri dishes and cured in a nitrogen atmosphere at 70° C. for 2 hours, at 80° C. for 2 hours and at 90° C. for 2 hours.

(14) The resulting fully cured VEU resin thermoset was hard, tack-free, virtually odourless and showed excellent antimicrobial properties.

(15) This embodiment exemplifies how the ratio of styrene derivative to double bond may be calculated.

(16) The vinyl ester urethane (VEU) content corresponds to component a) and amounts to 66.09 g (35 wt %). From example 3 above, one can see that this component a) is obtained from the additive reactions of an equivalent of a chain extender (tert. butyl bis-hydroxyethylamine) with two equivalents of diisocyanate(methylenphenyldiisocyanate) and two equivalents of 2-hydroxypropyl methacrylate, so their molecular weight is 950 g/mol. The VEU component has two vinylic double bonds, so the functionality f equals 2.

(17) This results in n.sub.Dop=f.Math.m.sub.Dop/M.sub.Dop=2.Math.66.09 g/950 g/mol=0.139 mol

(18) The styrene derivative content (tert. butylaminomethylstyrene, TBAMS) corresponds to component b) and amounts to 20+102.4 g=122.4 g (65 wt %). The molecular weight is 189 g/mol.

(19) This results in n.sub.Sty=m.sub.Sty/M.sub.Sty=122.4 g/189 g/mol=0.648 mol

(20) The ratio of styrene derivative to double bond is:
n.sub.sty:n.sub.Dop=0.648 mol:0.139 mol=4.66:1

Example 3B

(21) Preparation and Curing of the VEU Resin with 60 wt % TBAMS

(22) To the flask containing 58.73 g of VEU and 20.00 g of TBAMS, a further 68.10 g of TBAMS was added to produce a VEU resin with a total of 60 wt % TBAMS. Subsequently, 2 wt % of the azo initiator V601 [dimethyl 2,2′-azobis(2-methylpropionate)] manufactured by Wako was added and the flask contents were homogenized. About 8 g of the transparent homogeneous resin initiator mixture was placed in each of various glass petri dishes and cured in a nitrogen atmosphere at 70° C. for 2 hours, at 80° C. for 2 hours and at 90° C. for 2 hours.

(23) The resulting fully cured VEU resin thermoset was hard, tack-free, virtually odourless and showed excellent antimicrobial properties.

(24) In this embodiment, the ratio of styrene derivative to double bond is 3.79:1.

Example 3C

(25) Preparation and Curing of the VEU Resin with 55 wt % TBAMS

(26) To the flask containing 57.43 g of VEU and 20.00 g of TBAMS, a further 50.19 g of TBAMS was added to produce a VEU resin with a total of 55 wt % TBAMS. Subsequently, 2 wt % of the azo initiator V601 [dimethyl 2,2′-azobis(2-methylpropionate)] manufactured by Wako was added and the flask contents were homogenized. About 8 g of the transparent homogeneous resin initiator mixture was placed in each of various glass petri dishes and cured in a nitrogen atmosphere at 70° C. for 2 hours, at 80° C. for 2 hours and at 90° C. for 2 hours.

(27) The resulting fully cured VEU resin thermoset was hard, tack-free, virtually odourless and showed excellent antimicrobial properties.

(28) In this embodiment, the ratio of styrene derivative to double bond is 3.07:1.

Example 4

(29) In a brown glass bottle, 50.00 g (37.6 wt %) of the vinyl esters (1-methylethylidene)bis[4,1-phenyleneoxy(2-hydroxy-3,1-propanediyl)]bismeth-acrylate (corresponds to component a) available from Sigma Aldrich, product number: 494356, M=512.59 g/mol) and 83.09 g (62.4 wt %.%) of the amino-functionalized reactive diluent TBAMS (tert. butylaminomethylstyrene corresponds to component b)) were placed on a dolly for 4 days to dissolve, and once completely dissolved, 2 wt % of the azo initiator V601 [Dimethyl 2,2′-azobis(2-methylpropionate)] manufactured by Wako was added. Then, about 8 g of the transparent homogeneous resin initiator mixture was placed in each of various glass petri dishes and cured in a nitrogen atmosphere at 70° C. for 2 hours, at 80° C. for 2 hours and at 90° C. for 2 h.

(30) The resulting fully cured VE thermoset was tack-free and hard. The VE thermoset was practically odourless and showed excellent antimicrobial properties.

(31) In this embodiment, the ratio of styrene derivative to double bond is 2.26:1.

(32) Procedure Used to Determine Mechanical Behaviour and Glass Transition Temperature

(33) To determine the network TG, glass-fibre reinforced thermoset test pieces were produced from the resins and characterized by means of dynamic mechanical analysis (DMA).

(34) Using the DMA 242 manufactured by Netzsch it is possible to determine storage modulus and loss modulus as well as the loss factor of a sample as a function of the temperature, time and frequency of a sinusoidal vibration load applied.

(35) To produce the required test pieces, the resins prepared as per the embodiments, charged with 2 wt % initiator (V601 by Wako), were used.

(36) To this end, three 15×15 cm layers of Saertex® glass fibre non-crimp fabric (biaxial 0°/90°/type: S14EB540-00620-T1300-487000) were impregnated with the respective resin, placed in a 150×150×5 mm screw-down plate mould lined with Mylar® film, and air bubbles were removed as far as possible by brushing down with a spatula. The cavity of the mould was then filled up with more resin, covered with Mylar® film and closed by screwing down the upper mould plate. The curing was carried out for 2 hours at 70, 80 and 90° C., respectively, in a drying cabinet.

(37) After cooling, the GRP panels were cut with a table saw and, where necessary, brought to the required sample size with a sanding belt.

(38) Parameters and measurement settings in the DMA analyses performed:

(39) Sample Size: 50×10×5 mm

(40) Deformation mode: Dual cantilever

(41) Amplitude: 30 μm

(42) Dynamic force: 7.55 N

(43) Static force: 4 N

(44) Temperature range: 20-160° C.

(45) Heating range: 2 K/min

(46) Frequency: 1 Hz/10 Hz

(47) Atmosphere: N2

(48) Flow rate N2: 5 ml/min

(49) Procedure Used for Antimicrobial Testing

(50) The method applied is based on the Japanese JIS Z 2801:2000 standard. The test microorganism used in the experiments was the pathogenic germ Staphylococcus aureus. Rather than a multiresistant strain, a standard strain (ATCC 6538) was used.

(51) With each test germ (here Staphylococcus aureus), a microorganism-specific germ content was determined under the production conditions of the starting solution or starting suspension. With Staphylococcus aureus, this value was 108 germs per ml (see also remarks below).

(52) Antimicrobial activity was determined by comparing the growth of Staphylococcus aureus on reference surfaces to that on the sample materials.

(53) Empty petri dishes were used as reference material. The samples consisted of petri dishes into each of which a thin layer of a polymer sample had been poured. In each test series, three reference plates were used to determine the initial germ content (separate experiment independent of the antimicrobial behaviour test) as well as three reference plates and three sample plates to determine the surface germ content after incubation.

(54) All plates were inoculated with 400 μl of Staphylococcus aureus inoculum that was set to a germ content of 4.0-10*10.sup.5 CFU/ml.

(55) The inoculum applied was covered with a sterile PP film in order to avoid evaporation. Immediately after the inoculation, the three sample plates and three reference plates were placed in an incubation cabinet and incubated for 2 hours and 24 hours, respectively, at 35° C. and 90% humidity.

(56) To determine the germ content of the inoculation solution (initial germ content), three reference plates were washed immediately after inoculation by placing 10 ml of SCDLP bouillon (soy casein peptone bouillon with lecithin and polyoxyethylene medium) in the petri dish. The film was flipped using sterile tweezers and repeatedly flooded and flushed using a 1 ml pipette. The petri dish was waved in a figure eight before pipetting 1 ml of the rinsing solution into the first dilution level. Once a thinning series had been set up, the living germ content was determined using the drop plate method. The drop plate method entailed applying—in duplicate—5 drops of 10 μl each onto a plate count (PC) agar plate in every sector of the dilution level. The plates were incubated for 2 hours and 24 hours, respectively, at 37° C.

(57) The rinsing and determination of the living germ count on the reference and test plates after the incubation was performed applying the procedure followed to determine the initial germ content. As regards the test plates, besides raising the detection limit, the germ content of the direct rinsing solution was determined using the pour plate method. To this end—also in duplicate—1 ml of the solution was placed in an empty petri dish, over which liquid PC agar, tempered at 45° C., was poured. By waving it in a figure eight, the bacteria were distributed in the agar. The plates were incubated for 48 hours at 37° C.

(58) After the incubation, the colonies in the petri dish were counted. It was assumed that each germ had turned into a visible colony. After the incubation, the colonies could be discerned by the naked eye. If necessary, a light table could be used to make the germs more visible.

(59) Based on the volume of the inoculation solution and the thinning ratios applied, one could deduce the living germ count of the microorganisms per volumetric unit (i.e. per ml) of inoculation solution. The calculation was performed based on a weighted arithmetic average, applying the following formula:

(60) $\stackrel{\_}{c}=\frac{.Math.c}{n_1.Math.1+n_2.Math.0.1}.Math.d$
where c represents the weighted arithmetic average Σc represents the sum of the colonies of all petri dishes or sectors used as a basis for the calculation, n.sub.1 represents the number of the petri dishes or sectors of the lowest evaluable dilution level, n.sub.2 represents the number of petri dishes or sectors of the next higher dilution level, and d represents the lowest evaluated dilution level.

(61) When using the pour plate method, petri dishes with up to 300 CFU could be counted. When using the drop plate method, only plates with up to 150 CFU per sector could be counted.

(62) The thinning factor F1 had to be maintained when determining the living germ count per ml. This was the sum of the volume of the SCDLP bouillon and the volume of the bacterial suspension on the inoculated plate divided by the volume of the bacterial suspension on this inoculated plate.

(63) $F_1=\frac{10\mathrm{ml}+0.4\mathrm{ml}}{0.4\mathrm{ml}}=26$ F.sub.1 represents the thinning factor of the SCDLP bouillon.

(64) This resulted in the following formula, which was applied to determine the total germ count on the inoculated sample or reference plates using the pour plate method:

(65) $\mathrm{CFU}=\frac{.Math.c}{n_1.Math.1+n_2.Math.0.1}.Math.d.Math.F_1$

(66) When using the drop plate method, a further thinning factor became relevant, as a quarter of a plate was only inoculated with 50 μl, i.e. 0.05 ml. To deduce the germ content per ml, 0.05 ml had to be scaled up to 1 ml by multiplying it by 20.
F.sub.2=26.Math.20 F.sub.2 represents the thinning factor used to obtain the CFU in the drop plate method per ml.

(67) Accordingly, the total germ count of the inoculated sample and reference plates was calculated for the drop plate method taking account of all thinning factors applying the following formula:

(68) $\mathrm{CFU}=\frac{.Math.c}{n_1.Math.1+n_2.Math.0.1}.Math.d.Math.F_2$

(69) To calculate antimicrobial activity, in every test series, the individual results of the living germ count for the plates were combined to form a simple arithmetic mean, based on which the log.sub.10 reduction between the sample and reference plates was determined.

(70) The calculation was performed by applying the following formula:
log.sub.10−Reduction=log.sub.10(KG).sub.Ref(x)−log.sub.10(KG).sub.Pr(x)
where
(KG).sub.Ref(x) represents the CFU on the reference plates at time instance x
(KG).sub.Pr(x) represents the CFU on the sample plates at time instance x

(71) According to JIS Z 2801:2000, antimicrobial activity exists if the log reduction is at least 2.0 after 24 hours of exposure.

(72) If there are no countable colonies on the agar plates of the samples at the lowest dilution level using the pour plate method, the result was stated as <10 CFU/ml, in line with the requirement in the test standard.

Results of the Mechanical and Antimicrobial Tests

(73) TABLE-US-00001 Reference Surface germ Reactive Initial germ content content of sample Composition diluent (mass T.sub.G at T.sub.G at germ content after 24 h after 24 h Log Example VE or VEU fraction) 1 Hz 10 Hz (log CFU/ml) (log CFU/ml) (log CFU/ml) reduction 1 Crystic VE 671 (Scott Bader) TBAMS (0.65) 104.3 111.5 5.6 7.5 1.1 6.4 2 HPMA.sub.0.4TBBHEA.sub.0.2Lupranant MI.sub.0.404 DEAMS (0.2)/ 106.7 114.8 5.3 8.4 2.7 5.7 TBAMS (0.35) 3A HPMA.sub.0.4TBBHEA.sub.0.2Lupranant MI.sub.0.404 TBAMS (0.65) 97.6 106.4 5.3 8.4 1 7.4 3B HPMA.sub.0.4TBBHEA.sub.0.2Lupranant MI.sub.0.404 TBAMS (0.60) 102.6 111.2 5.3 8.4 3.1 5.3 3C HPMA.sub.0.4TBBHEA.sub.0.2Lupranant MI.sub.0.404 TBAMS (0.55) 100.5 109.1 5.3 8.4 2.4 6.0 4 (1-Methylethylidene)bis-[4,1- TBAMS (0.62) 110.3 117.5 5.7 7.8 1.5 6.3 phenyleneoxy(2-hydroxy-3,1- propanediyl)]bis methacrylate