Polysiloxane defoaming agent

Abstract

The invention relates to the use of a polysiloxane having a plurality of siloxane groups and at least one tertiary amide group covalently linked as a pending and/or terminal group to the polysiloxane, as a defoaming agent in a liquid composition.

Claims

1. A process comprising: adding a polysiloxane to a non-aqueous liquid composition, the polysiloxane including a plurality of siloxane groups and 2 to 7 covalently linked tertiary amide groups as pending and/or terminal groups, wherein the polysiloxane does not contain fluorinated organic groups and has a number average molecular weight in the range of 800 to 8000 g/mol, wherein the polysiloxane is added to the non-aqueous liquid composition in an amount effective to reduce or eliminate foaming within a coating formed by spray application of the non-aqueous liquid composition.

2. The process according to claim 1, wherein the tertiary amide group is a cyclic amide group.

3. The process according to claim 1, wherein the tertiary amide group is a non-cyclic amide group.

4. The process according to claim 1, wherein a covalent link between the polysiloxane and the 2 to 7 covalently linked tertiary amide groups contains the group —Si—O—CHR—, and wherein R represents hydrogen or an alkyl group.

5. The process according to claim 1, wherein the polysiloxane further comprises a pending and/or terminal polyether segment.

6. The process according to claim 1, wherein the polysiloxane contains between 0.0 and 10.0 mole % of non-tertiary amide groups, calculated on the number of tertiary amide groups.

7. The process according to claim 1, wherein the amount of polysiloxane added to the non-aqueous liquid composition ranges from 0.100 to 2.000 wt.-%, based on the total weight of the non-aqueous liquid composition and the polysiloxane.

8. The process according to claim 1, wherein the non-aqueous liquid composition is a coating composition.

9. The process according to claim 1, wherein the non-aqueous liquid composition is a curable pre-polymer composition.

10. The process according to claim 1, further comprising spraying the non-aqueous liquid composition.

11. The process according to claim 1, further comprising coating a substrate with the non-aqueous liquid composition.

12. A process of preparing a coated substrate, the process comprising: providing a non-aqueous liquid coating composition comprising a polysiloxane including a plurality of siloxane groups and 2 to 7 covalently linked tertiary amide groups as pending and/or terminal groups, wherein the polysiloxane does not contain fluorinated organic groups and has a number average molecular weight in the range of 800 to 8000 g/mol, wherein the polysiloxane is included in an amount effective to reduce or eliminate foaming within a coating formed by spray application of the non-aqueous liquid coating composition, and applying the non-aqueous liquid coating composition to a substrate to provide a dry layer thickness of at least 50 μm.

13. The process according to claim 12, wherein applying the non-aqueous liquid coating composition to the substrate comprises spraying of the non-aqueous liquid coating composition using a spraying device.

14. The process according to claim 13, wherein the spraying device is an airless spray gun.

15. The process according to claim 12, wherein the substrate is a transportation vehicle or a part thereof.

Description

EXAMPLES

(1) Preparation of Polysiloxanes Having Tertiary Amide Groups as a Pending and/or Terminal Group

Example 1

(2) A 500 ml flask equipped with a stirrer, reflux condenser, thermometer, dropping funnel and water separator was flushed with nitrogen and then charged with 64.7 g of xylene and 125.0 g of a methylhydrosiloxane of mean average formula M.sup.HD14M.sup.H. The water separator was filled with xylene. Under a nitrogen atmosphere, the solution was heated up to 120° C. At this temperature, 0.18 g of zinc acetyl acetonate was added into the reactor. Thereafter, the mixture was heated up to 155° C. Afterwards, 26.96 g of 1-(2-hydroxyethyl)-2-pyrrolidon was dosed into the flask within 140 minutes. The mixture was stirred at 155° C. for 30 minutes and was then distilled at 150° C. and 15 mbar using a rotary evaporator.

(3) The molecular weight of the substance was Mw=2157 g/mol and polydispersity=2.33, measured by GPC.

Example 2

(4) A 500 ml flask equipped with a stirrer, reflux condenser, thermometer, dropping funnel and water separator was flushed with nitrogen and them charged with 65.0 g xylene and 135 g of a methylhydrosiloxane of mean average formula M.sup.HD24M.sup.H. The water separator was filled with xylene. Under nitrogen atmosphere, the solution was heated up to 120° C. At this temperature, 0.18 g of zinc acetyl acetonate was filled into the reactor. Thereafter, the mixture was heated up to 155° C. Afterwards, 17.7 g of 1-(2-hydroxyethyl)-2-pyrrolidon was dosed into the flask within 140 minutes. The mixture was stirred at 155° C. for 30 minutes and was then distilled at 150° C. and 15 mbar using a rotary evaporator.

(5) The molecular weight of the substance was Mw=3216 g/mol and polydispersity=2.19, measured by GPC.

Example 3

(6) A 500 ml flask equipped with a stirrer, reflux condenser, thermometer, dropping funnel and water separator was flushed with nitrogen and then charged with 127.6 g xylene and 250 g of a methylhydrosiloxane of mean average formula M.sup.HD.sub.14M.sup.H.

(7) The water separator was filled with xylene. Under nitrogen atmosphere, the solution was heated up to 120° C. At this temperature, 0.36 g of zinc acetyl acetonate was filled into the reactor. Thereafter, the mixture was heated up to 155° C. Afterwards, 48.90 g of N,N-Dimethyl lactamide was dosed into the flask within 140 minutes. The mixture was stirred at 140° C. for 30 minutes and was then distilled at 150° C. and 15 mbar using a rotary evaporator.

(8) The molecular weight of the substance was Mw=2818 g/mol and polydispersity=2.14, measured by GPC.

Example 4

(9) A 500 ml flask equipped with a stirrer, reflux condenser, thermometer, dropping funnel and water separator was flushed with nitrogen and them charged with 65.1 g xylene and 120 g of a methylhydrosiloxane of mean average formula MD.sup.H2,3 D.sub.10M. The water separator was filled with xylene. Under nitrogen atmosphere, the solution was heated up to 120° C. At this temperature, 0.18 g of zinc acetyl acetonate was filled into the reactor. Thereafter, the mixture was heated up to 140° C. Afterwards, 32.92 g of N,N-Dimethyl lactamide was dosed into the flask within 140 minutes. The mixture was stirred at 140° C. for 30 minutes and was then distilled at 150° C. and 15 mbar using a rotary evaporator.

(10) The molecular weight of the substance was Mw=4025 g/mol and polydispersity=3.28, measured by GPC.

Example 5

(11) A 500 ml flask equipped with a stirrer, reflux condenser, thermometer and dropping funnel was flushed with nitrogen and then charged with 125 g of a methylhydrosiloxane of mean average formula M.sup.HD.sub.14M.sup.H and 0.08 g 2,6-Di-tert-Butyl-4-Methyl-Phenol. Under nitrogen atmosphere, the solution was heated up to 80° C. At this temperature, 0,004 g of Platinum-Divinyltetramethyldisiloxane-Complex (Pt-DVTMD) were filled into the reactor and 22.82 g of N-Vinylcaprolactam were dosed within 60 minutes into the flask. Thereafter, the mixture was heated up to 100° C. At this temperature, 0.002 g of 1,3-Divinyltetramethyldisiloxane were filled into the reactor. After 120 minutes reaction time, the mixture was heated up to 110° C. and 0.002 g of Pt-DVTMD were filled into the reactor. After additional reaction time of 120 minutes, the mixture was distilled at 150° C. and 15 mbar using a rotary evaporator.

(12) The molecular weight of the substance was Mw=2132 g/mol and polydispersity=1.82, measured by GPC.

Example 6

(13) A 500 ml flask equipped with a stirrer, reflux condenser, thermometer, dropping funnel and water separator was flushed with nitrogen and then charged with 117.0 g xylene and 222.0 g of a methylhydrosiloxane of mean average formula M.sup.HD24M.sup.H. The water separator was filled with xylene. Under nitrogen atmosphere, the solution was heated up to 120° C. At this temperature, 0.16 g of zinc acetyl acetonate was filled into the reactor. Thereafter, the mixture was heated up to 155° C. Afterwards, 24.4 g of a ethylene oxide/propylene oxide based polyether alcohol of average formula CH.sub.3-4.3 EO/5.1 PO—OH (random) was dosed into the flask within 30 minutes. The mixture was stirred at 155° C. for 30 minutes. After that the mixture was cooled down to 140° C. Afterwards 24.4 g of 1-(2-hydroxyethyl)-2-pyrrolidon was dosed into flask within 15 minutes. The mixture was stirred at 140° C. for 30 minutes. The volatiles were distilled off at 150° C. and 15 mbar using a rotary evaporator. The molecular weight of the residue was Mw=3370 g/mol and polydispersity=2.16, measured by GPC.

Comparative Example 1

(14) A 500 ml flask equipped with a stirrer, reflux condenser, thermometer and water separator was flushed with nitrogen and charged with 100 g of a methylhydrosiloxane of mean average formula MD.sup.H.sub.2,3 D.sub.10M and 0.079 g 2,6-Di-tert-Butyl-4-Methyl-Phenol. Under nitrogen atmosphere, the solution was heated up to 60° C. At this temperature, 0.003 g Platinum-Divinyltetramethyldisiloxane-Complex (Pt-DVTMD) were filled into the reactor. Afterwards, 81.36 g of allyl-3PO—OH are dosed into the flask within 20 minutes. The mixture was stirred at 60° C. for 30 minutes and was then distilled at 150° C. and 15 mbar using a rotary evaporator. The molecular weight of the substance was Mw=2071 g/mol and polydispersity=3.22, measured by GPC.

Comparative Example 2: Preparation of a Defoamer According to EP 2482948 B1

(15) A 500 mL-flask equipped with a stirrer, reflux condenser, thermometer and water separator was flushed with nitrogen and then charged with 156.5 g of polypropylene glycol having a number average molar mass Mn of 2000 g/mol, 43.2 g of oleic acid, 0.2 g of dibutyltin dilaurate, 0.2 g of triphenylphosphite and 16.00 g of xylene. The mixture was heated to 240° C. with stirring under a blanket of nitrogen within two hours. Water was removed by azeotropic distillation at 240° C. and under atmospheric pressure until an acid number of less than 15 mgKOH/g was reached. The mixture was then distilled at 150° C. and 15 mbar using a rotary evaporator. A liquid reaction product having a mass fraction of solids of 99% and a dynamic viscosity of 380 mPa.Math.s. was obtained.

(16) Comparative Sample 3

(17) Tego Airex 990 is a commercial defoaming agent for airless/airmix application ex Evonik. Its formulation is described as being based on deaerating organic polymers, with a tip of polydimethylsiloxane. It is recommended for clear and pigmented coatings.

(18) Preparation of a Pigmented White Topcoat for Airless Application and Description of Airless Application

(19) 35 g of an acrylic resin (Synthalat A 086HS, Synthopol), 9.3 g solvents (4.0 g Butyl acetate; 5.3 g Xylene), 1.5 g Dispersing Additive (Disperbyk-110, BYK) and 0.5 g Rheology additive (Garamite 7305, BYK) were mixed. 10 g of white pigment (TiPure R 960, Chemours), 17 g fillers (6.0 g Luzenac 20M2, Imerys Minerals; 6.0 g Bariumsulfate EWO, Huntsman; 5.0 g Millicarb OG, Omya) and 9 g anti-corrosive fillers (8.0 g Heucophos SAPP, Heubach; 1.0 g Heucorin RZ, Heubach) were added with stirring. The mixture was grinded by dissolver with 6 cm tooth-blade for 20 minutes at 40° C. at 7000 rpm.

(20) After grinding, 15.4 g of the acrylic resin (Synthalat A 086HS, Synthopol), 1.9 g of solvents (1.0 g Butyl acetate; 0.9 g Butylglycol acetate) and a surface additive (BYK-310, BYK) were added to the mixture. The mixture was stirred by dissolver with 6 cm tooth-blade for 5 minutes at 2000 rpm.

(21) The mixture was filtered over a 210 μm sieve.

(22) The defoaming agents of Examples 1-5 and Comparative Examples 1-3 were incorporated by dissolver with tooth-blade for 3 minutes at 25° C. at 1865 rpm. For each defoaming agent two concentrations were tested, namely 0.5 and 1.0% by weight.

(23) After storage overnight, 12.3 g hardener (Desmodur N 3390, Covestro) and 18 g solvent (Butyl acetate) were incorporated by stirring with a spatula.

(24) Application was done by Sata spray mix 3000, 192 bar paint pressure, 3350 nozzle on primed steel panels. The coated substrates were stored vertically for drying at room temperature.

(25) After complete drying the panels were judged visually in terms of foam (on a scale from 1=no foam to 5=severe foam), microfoam (on a scale from 1=no microfoam to 5=severe microfoam), levelling (on a scale from 1=good levelling to 5=bad levelling) and craters (on a scale from 1=no craters to 5=severe craters).

(26) The results are summarized in Table 1

(27) TABLE-US-00001 TABLE 1 Defoamer (concentration) Foam Micro-foam Levelling Craters None 5 5 — — Example 1 (0.5%) 2 3-4 1-2 1 Example 1 (1.0%) 1-2 2 1 1 Example 2 (0.5%) 2 3 1 1 Example 2 (1.0%) 1-2 2 1 1 Example 5 (0.5%) 2-3 3 2-3 1 Example 5 (1.0%) 3-4 3-4 3 1 Example 6 (0.5%) 2-3 2 1 1 Example 6 (1.0%) 2 1-2 1 1 Comparative 5 5 5 1 example 1 (0.5%) Comparative 4-5 4 5 1 example 1 (1.0%) Comparative 5 5 3 1 example 2 (0.5%) Comparative 5 4-5 3 1 example 2 (1.0%) Comparative 4 4-5 5 1 example 3 (0.5%) Comparative 4 4-5 5 3 example 3 (1.0%)

(28) From Table 1 it can be inferred that coating compositions wherein defoaming agents are used according to the invention exhibit better defoaming properties than the compositions wherein defoaming agents according to the state of the art are used at the same concentrations. Furthermore, the coating compositions according to the invention exhibit improved levelling properties, and the cratering behavior is not negatively impacted.

(29) Description of Draw Down Test

(30) A part of the paint with hardener was also applied on glass panels to measure the gloss and haze values.

(31) After complete drying the presence of craters was determined visually on a scale from 1=no craters to 5=severe craters. The results are summarized in Table 2.

(32) TABLE-US-00002 TABLE 2 Defoamer Gloss (concentration) 20° 60° Haze Craters None 54 85 380 1 Example 1 (0.5%) 52 85 375 1 Example 1 (1.0%) 52 84 345 1 Example 2 (0.5%) 51 85 365 1 Example 2 (1.0%) 50 83 360 1 Example 3 (0.5%) 56 88 360 1 Example 3 (1.0%) 55 86 300 1 Example 4 (0.5%) 57 88 360 1 Example 4 (1.0%) 58 88 340 1 Example 5 (0.5%) 60 88 300 1 Example 5 (1.0%) 57 84 286 1 Example 6 (0.5%) 56 88 320 1 Example 6 (1.0%) 57 89 310 1 Comparative 57 88 370 1 example 1 (0.5%) Comparative 55 87 360 1 example 1 (1.0%) Comparative 57 88 370 1 example 2 (0.5%) Comparative 57 89 370 1 example 2 (1.0%) Comparative 58 89 370 1 example 3 (0.5%) Comparative 59 89 360 1 example 3 (1.0%)

(33) From Table 2 it can be inferred that gloss, haze and cratering of the coatings prepared from the coating compositions according to the invention are not negatively impacted, as compared to the use of comparative defoaming agents.

(34) Description of Foam Volume (Density) Test.

(35) A 50 g sample of paint without hardener was stirred for one minute by dissolver tooth-blade and immediately after stirring filled into a metric cylinder, which was placed on a scale. To calculate the density the weight was divided by the volume. The results are summarized in Table 3.

(36) TABLE-US-00003 TABLE 3 Defoamer (concentration) Density in g/cm.sup.3 None 0.94 Example 1 (0.5%) 1.06 Example 1 (1.0%) 1.06 Example 2 (0.5%) 1.10 Example 2 (1.0%) 1.15 Example 3 (0.5%) 1.13 Example 3 (1.0%) 1.12 Example 4 (0.5%) 1.13 Example 4 (1.0%) 1.17 Example 5 (0.5%) 1.06 Example 5 (1.0%) 1.08 Comparative example 1 (0.5%) 0.85 Comparative example 1 (1.0%) 0.89 Comparative example 2 (0.5%) 0.93 Comparative example 2 (1.0%) 0.92 Comparative example 3 (0.5%) 0.97 Comparative example 3 (1.0%) 0.93

(37) From Table 3 it can be inferred that the density after stirring of the coating compositions according to the invention is higher than the density of comparative coating compositions with a defoaming agent according to the state of the art. This indicates improved defoaming properties of the inventive compositions.

(38) Preparation of Clear Coat and Description of Application Test

(39) A mixture of 82.1 g of an acrylic binder ((Synthalat A 086HS, Synthopol), 8.9 g Butyl acetate, 7.4 g Xylene and 1.6 g Butyl glycol acetate were mixed by dissolver for 5 minutes at 2000 rpm.

(40) The defoamer (Example 1-3 and 5 and comparative example 1-3) was incorporated by dissolver with tooth-blade for 3 minutes at 25° C. at 1865 rpm.

(41) Application was done by Sata spray mix 3000, 192 bar paint pressure, 3350 nozzle on primed steel panels. The metal substrates were stored vertically for drying at room temperature.

(42) After complete drying the panels were judged visually in terms of foam (on a scale from 1=no foam to 5=severe foam), microfoam (on a scale from 1=no microfoam to 5=severe microfoam), levelling (on a scale from 1=good levelling to 5=bad levelling), craters (on a scale from 1=no craters to 5=severe craters), pinholes (on a scale from 1=no pinholes to 5=severe pinholes) and clouds (on a scale from 1=no clouds to 5=severe clouds).

(43) The results are summarized in Table 4.

(44) TABLE-US-00004 Defoamer Micro- Level- (concentration) Foam foam ling Craters Pinholes Clouds 4 3-4 5 1 5 1 Example 1 2 2-3 3 1 3 2 (0.5%) Example 1 1-2 2 2 1 2 2 (1.0%) Example 2 2-3 3-4 2-3 1 3 4 (0.5%) Example 2 1-2 2 2-3 1 3 2-3 (1.0%) Example 3 2-3 3 2-3 1 3 3 (0.5%) Example 3 2 3 2-3 1 3 3 (1.0%) Example 5 1-2 1-2 1 1 2 1-2 (0.5%) Example 5 1-2 1-2 1 1 2 1-2 (1.0%) Comp. example 3-4 3-4 4-5 1 4 4 1 (0.5%) Comp. example 3-4 3-4 4-5 1 4 4 1 (1.0%) Comp. example 5 5 — 1 5 3-4 2 (0.5%) Comp. example 5 5 — 1 5 3 2 (1.0%) Comp. example 4 4 5 1 4-5 3-4 3 (0.5%) Comp. example 5 5 5 1 5 3-4 3 (1.0%)

(45) From Table 4 it can be inferred that the coatings from the compositions according to the invention exhibit less foaming, better levelling, less pinholes and less clouds than the coatings containing defoaming agents according to the state of the art. There is no negative influence on crater formation.

(46) Description of Foam Volume (Density) Test

(47) A 50 g sample of paint without hardener was stirred for 1 min by dissolver tooth-blade and immediately after stirring filled into a metric cylinder, which was placed on a scale. To calculate the density the weight was divided by the volume. The results are summarized in Table 5.

(48) TABLE-US-00005 TABLE 5 Defoamer (Concentration) Density in g/cm.sup.3 0.75 Example 1 (0.5%) 0.85 Example 1 (1.0%) 0.85 Example 2 (0.5%) 0.90 Example 2 (1.0%) 0.93 Example 3 (0.5%) 0.90 Example 3 (1.0%) 0.91 Example 4 (0.5%) 0.93 Example 4 (1.0%) 0.93 Example 5 (0.5%) 0.86 Example 5 (1.0%) 0.85 Comparative example 1 (0.5%) 0.74 Comparative example 1 (1.0%) 0.73 Comparative example 2 (0.5%) 0.75 Comparative example 2 (1.0%) 0.76 Comparative example 3 (0.5%) 0.76 Comparative example 3 (1.0%) 0.80

(49) From Table 5 it can be inferred that the density after stirring of the coating compositions according to the invention is higher than the density of comparative coating compositions with a defoaming agent according to the state of the art. This indicates improved defoaming properties of the inventive compositions.