Composition and process for applying hydrophobic coating to fibrous substrates

Abstract

Fabrics are treated with a hydrophobic treatment that includes at least one hydrophobic monomer and a crosslinker. The treatment is low in volatile organic compounds and water. It is a liquid at 22 C. or a suspension having a phase that is liquid at 22 C. The monomer and crosslinker are cured in a free radical polymerization to form a hydrophobic coating on a fibrous substrate.

Claims

1. A curable coating composition comprising: a-1) at least one monomer having exactly one free-radical polymerizable group per molecule and being a liquid at 22 C., the at least one monomer having at least one hydrocarbyl group that has at least eight carbon atoms bonded directly or indirectly to the polymerizable group, wherein the hydrocarbyl group may be nonfluorinated, partially fluorinated or perfluorinated, the at least one monomer having a boiling temperature equal to or greater than 100 C., a-2) at least one monomer having exactly one free-radical polymerizable group per molecule and being a solid at 22 C., the at least one monomer having at least one hydrocarbyl group that has at least eight carbon atoms bonded directly or indirectly to the polymerizable group, wherein the hydrocarbyl group may be nonfluorinated, partially fluorinated or perfluorinated, the at least one monomer having a boiling temperature equal to or greater than 100 C., b) at least one monomer having at least two free-radical polymerizable groups and a boiling temperature equal to or greater than 100 C.; and 2 to 98 weight percent, based on the weight of the curable coating composition, of at least one linear, branched or cyclic polysiloxane; wherein the coating composition is a liquid at 22 C. or a suspension of one or more solids in a liquid phase at 22 C.

2. The coating composition of claim 1 which contains no more than 10% by weight of organic compounds that have boiling temperatures below 100 C. and no more than 5% by weight water, based on the entire weight of the coating composition.

3. The coating composition of claim 2 wherein components a-1) and a-2) have a solubility in water of no greater than 1 part by weight per 100 parts by weight of water at 30 C., and water is soluble in each of components a-1.) and a-2) to the extent of no greater than 1 part by weight per 100 parts by weight of components a-1) and a-2) at 30 C.

4. The coating composition of claim 3, wherein the polymerizable group of components a-1) and a-2) is an acrylate or methacrylate group.

5. A curable coating composition comprising a) a mixture of at least one monomer having exactly one free-radical polymerizable acrylate or methacrylate group per molecule and which is a liquid at 22 C. and at least one monomer having exactly one free-radical polymerizable acrylate or methacrylate group per molecule and which is a solid at 22 C., wherein component a) has a solubility in water of no greater than 1 part by weight per 100 parts by weight of water at 30 C., and water is soluble in component a) to the extent of no greater than 1 part by weight per 100 parts by weight of component a) at 30 C., and b) at least one monomer having at least two free-radical polymerizable groups and a boiling temperature equal to or greater than 100 C.; wherein the coating composition is a liquid at 22 C. or a suspension of one or more solids in a liquid phase at 22 C., the coating composition contains no more than 10% by weight of organic compounds that have boiling temperatures below 100 C. and no more than 5% by weight water, based on the entire weight of the coating composition.

6. The coating composition of claim 1 wherein component b) includes at least one polyacrylate compound having 2 to 8 acrylate and/or methacrylate groups per molecule, at least one drying oil, or a mixture of thereof.

7. The coating composition of claim 1 wherein component b) includes one or more of 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,8-octanediol diacrylate, cyclohexane dimethanol diacrylate, trimethylolpropane triacrylate, glycerin triacrylate, pentaerythritol tetraacrylate, dip entaerythritol tetraacrylate, dipentaerythritol hexacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,8-octanediol dimethacrylate, cyclohexane dimethanol dimethacrylate, trimethylolpropane trimethacrylate, glycerin trimethacrylate, pentaerythritol tetramethacrylate, dip entaerythritol tetramethacrylate, dipentaerythritol hexamethacrylate, linseed oil, safflower oil and tung oil.

8. The coating composition of claim 1, further comprising a heat-activatable free radical initiator.

9. The coating composition of claim 1 which contains no more than 1% by weight of organic compounds that have boiling temperatures below 100 C. and no more than 1% by weight water, based on the entire weight of the coating composition.

10. The coating composition of claim 1, further comprising a wax.

11. The coating composition of claim 4, further comprising a wax.

12. The coating composition of claim 5, further comprising a wax.

Description

Example 1

(1) A non-fluorocarbon, laundry-durable, water-repellent treatment is made for application on 100% polyester fleece by mixing the following ingredients:

(2) Component a): 4.1 g stearyl methacrylate (liquid), 4.1 g lauryl acrylate (liquid), 15 g octadecyl acrylate (solid)

(3) Component b): 4.7 g 1,6-hexanediol diacrylate, 1.4 g dipentaerythrital penta-/hexa acrylate, 4.3 g linseed oil

(4) Component e): 9.1 g paraffin wax, 10.8 g decamethylcyclopentasiloxane.

(5) These ingredients are heated to 83 C. and form clear, yellow solution. The solution is allowed to cool to room temperature, and 2.5 g lauroyl peroxide (component d)) is added with further mixing.

(6) If this material is then left to sit at room temperature, it solidifies, possibly due to the solid materials (such as octadecyl acrylate) forming a continuous or co-continuous phase. However, by stirring the material for several hours, a suspension of solid particles within a liquid phase instead forms. The solid phase of the suspension may contain particles of the paraffin wax and/or the octadecyl acrylate.

(7) 0.8 to 1.6 mL of this suspension is applied to the face side of an 88 swatch of 100% polyester fabric using a paint roller. The mixture is cured by heat-pressing the coated fabric for 60 seconds on a heat plate operated between 120 to 205 C. A light water spray is applied to the surface of the fabric before curing it to generate steam as it is heated. The treatment provides durable water-repellent treatment without the use of fluorocarbons and also had a nice hand. No significant color change to the fabric is observed. Additional oven-curing is not necessary, but doing so increases durability during multiple laundry cycles. These samples withstand more than 65 sequential wash/dry cycles without any observable water repellency degradation. By contrast, a commercial, fluorocarbon-based wet treatment applied to the same fabric and subjected to the same laundry testing is fully removed by laundry exposure after only 30 wash/dry cycles.

Example 2

(8) A non-fluorocarbon, impermeable water-repellent treatment is made for application on 100% acrylic outdoor furniture fabric by mixing the following ingredients:

(9) Component a): 2.2 g stearyl methacrylate (liquid), 2.3 g of lauryl acrylate, (liquid) 10.1 g octadecyl acrylate (solid)

(10) Component b): 2.8 g of 1,6 hexanediol diacrylate, 0.8 g of dipentaerythritol penta-/hexa acrylate

(11) Component e:) 6.3 g paraffin wax, 7.3 g decamethylcyclopentasiloxane

(12) These ingredients are heated to 83 C. and form clear solution. The solution is allowed to cool to room temperature, and 1.5 g lauroyl peroxide (component d)) is added with further mixing. This mixture is left stirring overnight on a cold stirring hotplate, resulting in a thick suspension, similar in consistency to the mixture of Example 1.

(13) The face side of various 88 swatches of 100% acrylic awning or outdoor furniture upholstery fabric each are coated with 2-3 mL of this suspension using a paint roller. A light water aerosol spray is applied to the surface of the coated swatches. The water is volatilized and the coating composition is cured by heat-pressing the moistened and coated swatches for 80 seconds on a heat press operated at 205 C. The cured swatches were impermeable to penetration when sprayed with water continuously for 15 minutes.

(14) One of the thus-treated samples is then coated on each side with a hot (65 C.) fluorocarbon liquid mixture that contained 0.7 g azobisisobutyronitrile and 9.2 g of 2-(perfluorohexyl) ethyl acrylate. The coated sample is then pressure heat pressed at 160 C. for 80 seconds without the prior addition of water spray to cure the polymer. The sample is then oven cured for 10 minutes at 125 C. to complete the curing. At the completion of the curing process, the coated aramid sample is resistant to dodecane penetration as well as water penetration, indicating both hydrophobicity and oleophobicity treatment.

Example 3

(15) Another curing composition was made in the same general manner described in Examples 1 and 2, using these ingredients:

(16) Component a): 6.7 g of lauryl acrylate (liquid), 20.2 g octadecyl acrylate (solid)

(17) Component b): 6 g of 1,6 hexanediol diacrylate, 2 g dipentaerythritol penta-/hexa acrylate, 5.3 g linseed oil

(18) Component d): 3.4 g lauroyl peroxide

(19) Component e): 14 g paraffin wax, 18.4 g decamethylcyclopentasiloxane

(20) All ingredients except the lauryl peroxide are heated on a hot plate until a solution forms, then are allowed to cool while being constantly stirred. When the temperature reaches to 40 C., the lauroyl peroxide is added and the mixture is continuously stirred for another 24 hours to, forming a suspension similar to those described in Examples 1 and 2.

(21) Using a roller, 1 mL of the resulting suspension is coated onto both sides of several 88 swatches of aramid fabric. The coated swatches are then sprayed with an aerosol spray of water and pressure-heated for 80 seconds at about 140 C. to volatilize the water and partially cure the composition. The samples are then oven-cured for 15 minutes at 123 C. The samples were able to withstand a pressurized spray of 10 L/min of water for 10 minutes with only 7.5% water absorption by weight.

Example 4

(22) A suspension is formed in the same general manner described in Examples 1-3 from the following ingredients:

(23) Component a): 0.81 g stearyl methacrylate (liquid), 1.1 g lauryl acrylate (liquid), 4.8 g of 2-(perfluorohexyl) ethyl acrylate (liquid), 4.0 g octadecyl acrylate (solid)

(24) Component b): 1.4 g 1,6 hexanediol diacrylate

(25) Component d): 1.3 g azobisisobutyronitrile

(26) Component e): 6.7 g paraffin wax, 3.6 g of decamethylcyclopentasiloxane

(27) Component f): 4.2 g of PTFE Teflon micropowder (10-50 m particle size).

(28) After stirring overnight at room temperature, a thick white suspension forms. The PTFE micropowder does not dissolve. The slurry is applied to both sides of an aramid test sample using a roller. The coated sample is heat pressed at 160 C. for 80 seconds without the prior addition of water spray. The curing is completed by placing the sample in an oven for 10 minutes at 120 C. When fully cured, the polymerized coating resists dodecane penetration and water penetration.