Olefin repellant coatings and articles thereof

Abstract

Described herein is a curable composition derived from (i) a polyhedral oligomeric silsesquioxane comprising at least two (meth)acrylate groups; (ii) a second compound comprising at least three (meth)acrylate groups and at least one hydroxy group; and (iii) an initiator. When cured, the curable composition forms a surface that has a styrene contact angle of at least 17.0 degrees.

Description

PA102630W002OLEFIN REPELLANT COATINGS AND ARTICLES THEREOFTECHNICAL FIELD

[0001] A composition derived from (i) a polyhedral oligomeric silsesquioxane comprising at least two (meth)acrylate groups; and (ii) a second compound comprising at least three (meth)acrylate groups and at least one hydroxy group is discussed. Such compositions when cured are shown to create an oleophobic surface, which is advantageous for resistance to olefins, including reactive olefins such as styrene.SUMMARY

[0002] When storing substances, it is important that the container not interact physically or chemically with the substance being stored, which can lead to among other things, mechanical compromise of the container via swelling or softening, reaction of the substance, and / or contaminating the substance with by-products from the container. For example, metal cans are inexpensive containers for food products; however, they can interact with acidic food products such as tomatoes. Thus, metal cans to store acidic food products typically are lined with a food grade resin, such as an epoxy. Similarly, inexpensive plastic containers such as those made of polyolefin or polyacrylate may need to be coated with another material to prevent interaction with the substances held therein, such as styrene. Typically, the coatings comprise fluoropolymers or silicones, which both have their drawbacks.

[0003] Thus, there is a desire to identify new oleophobic coatings. Specifically, a coating that has adequate repellency to reactive olefinic substances such as styrene.

[0004] In one aspect, a curable composition is described. The curable composition comprises: (i) a polyhedral oligomeric silsesquioxane comprising at least two (meth)acrylate groups; (ii) a second compound comprising at least three (meth)acrylate groups and at least one hydroxy group; and (iii) an initiator, wherein the curable composition after cure has a styrene static contact angle of at least 17.0 degrees.

[0005] In one embodiment, a cured composition derived from (i) a polyhedral oligomeric silsesquioxane comprising at least two (meth)acrylate groups; (ii) a second compound comprising at least three (meth)acrylate groups and at least one hydroxy group; and (iii) an initiator, wherein the cured composition has a styrene static contact angle of at least 17.0 degrees is described.

[0006] In yet another embodiment, a method of making an oleophobic surface is described. The method comprising (a) disposing a coating composition onto a surface, wherein the coating composition comprises (i) a polyhedral oligomeric silsesquioxane comprising at least two (meth)acrylate groups; (ii) a second compound comprising at least three (meth)acrylate groups and at least one hydroxy group; and (iii) an initiator; and (b) initiating the initiator to form a cured coating, wherein the cured coating has a styrene static contact angle of at least 17.0 degrees.

[0007] The above summary is not intended to describe each embodiment. The details of one or more embodiments of the invention are also set forth in the description below. Other features, objects, and advantages will be apparent from the description and from the claims.DETAILED DESCRIPTION

[0008] As used herein, the term“a”, “an”, and “the” are used interchangeably and mean one or more; and“and / or” is used to indicate one or both stated cases may occur, for example A and / or B includes, (A and B) and (A or B).

[0001] The term “curing” refers to a process during which a chemical reaction takes place; resulting in a harder, tougher, or more stable linkage or substance. In polymer chemistry, “curing” specifically refers to the toughening or hardening of a polymer via cross-linking of polymer chains. Curing processes are brought about by exposure to radiation.

[0009] The term “(meth)acrylate” refers to any of an acrylate, a methacrylate, and mixtures thereof.

[0010] Also herein, recitation of ranges by endpoints includes all numbers subsumed within that range (e.g., 1 to 10 includes 1.4, 1.9, 2.33, 5.75, 9.98, etc.).

[0011] Also herein, recitation of “at least one” includes all numbers of one and greater (e.g., at least 2, at least 4, at least 6, at least 8, at least 10, at least 25, at least 50, at least 100, etc.).

[0012] As used herein, “comprises at least one of’ A, B, and C refers to element A by itself, element B by itself, element C by itself, A and B, A and C, B and C, or a combination of all three.

[0013] Adequate fluid repellency during storage over the lifetime of a container can correlate with the contact angle of the fluid on the inner surface of the container. Thus, low contact angles are associated with undesirable wetting and high compatibility between the fluid and the surface (with the potential to cause further physical and / or chemical changes), while high contact angles are associated with the ability of the surface to repel the fluid.

[0014] In the present disclosure, it has been found that reacting a polyhedral oligomeric silsesquioxane comprising at least two (meth)acrylate groups with another compound comprising at least three (meth)acrylate groups and at least one hydroxy group can result in a material that is both highly crosslinked and carries hydroxyl content highly incompatible with styrene, generating surfaces that have good styrene repellency.

[0015] The polyhedral oligomeric silsesquioxane comprising at least two (meth)acrylate groups, is a three-dimensional, cage-like structure which comprises a framework formed by Si-O-Si linkages and tetrahedral vertices. Silsesquioxanes are commonly formed by condensation of one or more organosilanes (e.g., trialkoxysilane derivatives).

[0016] In some embodiments, the silsesquioxane of the present disclosure is of the formula [RSiO3 / 2]n, where R refers to hydrogen, alkyl, alkenyl, aryl, alkaryl, arylalkyl, alkoxy, or alkoxyaryl groups and n is 6, 8, 10, or 12.

[0017] The polyhedral oligomeric silsesquioxane of the present disclosure comprises (meth)acrylate- containing groups which are substitutes off the cage silsesquioxane structure. The polyhedral oligomeric silsesquioxane comprises at least two (meth)acrylate groups. In some embodiments, the polyhedral oligomeric silsesquioxane comprises at least 3, 4, 5, or even 6 (meth)acrylate groups. In someembodiments, the polyhedral oligomeric silsesquioxane comprises no more than 8, 10, or even 12 (meth)acrylate groups.

[0018] In some embodiments, the polyhedral oligomeric silsesquioxane is according to Formula IWhere each R’ is independently a H, alkyl, alkenyl, aryl, alkaryl, arylalkyl, alkoxy, or alkoxyaryl group and wherein at least two R’ comprise a (meth)acrylate moiety. Typically, the alkyl, alkenyl, aryl, alkaryl, arylalkyl, alkoxy, or alkoxyaryl groups comprise at least 1, 2, 3, or even 4 carbon atoms and at most 6, 8, 10 or even 12 carbon atoms. Exemplary R’ groups include -H, isobutyl, cyclohexyl, - (CH2)XOC(=O)CH=CH2, -(CH2)XOC(=O)CH=CHCH3, where x is 1, 2, 3, 4, 5, 6, 7, or 8.

[0019] Exemplary polyhedral oligomeric silsesquioxane include: octa(meth)acrylate polyhedral oligosilsesquioxane, deca(meth)acrylate polyhedral oligosilsesquioxane, or dodeca(meth)acrylate polyhedral oligosilsesquioxane. Limited types of polyhedral oligomeric silsesquioxanes functionalized with (meth)acrylates are commercially available. The polyhedral oligomeric silsesquioxane can be synthesized using procedures known in the art, for example, sol-gel chemistry.

[0020] The curable composition of the present disclosure further comprises a second compound having at least three (meth)acrylate groups and at least one hydroxy group. This second compound is different from the polyhedral oligomeric silsesquioxane described above. In some embodiments, the second compound consists of carbon, hydrogen, and oxygen atoms and no other atoms. In other embodiments, the second compound comprises additional atoms. For example, the second compound consists of carbon, hydrogen, and oxygen atoms as well as nitrogen, and / or sulfur atoms.

[0021] The second compound comprises at least three (meth)acrylate groups. In some embodiments, the second compound comprises at least 4, 5, or even 6 (meth)acrylate groups. In some embodiments, the second compound comprises at most 8, 10, 12, 14, or even 16 (meth)acrylate groups. This second compound also comprises at least one hydroxy group. In some embodiments, the second compound comprises at least 2, 3, or even 4 hydroxyl groups. In some embodiments, the second compound comprises at most 6, 8, or even 10 hydroxyl group. In some embodiments, the second compound comprises at least five (meth)acrylate groups and one hydroxy group. An exemplary second compound includes dipentaerythritol penta(meth)acrylate, which is commercially available.

[0022] The curable composition comprises a mixture of the polyhedral oligomeric silsesquioxane and the second compound. In some embodiments, the curable composition comprises at least 15, 20, 25, 30, 40, or even 50 parts by weight and no more than 50, 60, 70, 75, 80, or even 85 parts by weight of the second compound based on the combined weight of the polyhedral oligomeric silsesquioxane and thesecond compound. In some embodiments, the curable composition comprises at least 15, 20, 25, 30, 40, or even 50 parts by weight and no more than 50, 60, 70, 75, 80, or even 85 parts by weight of the polyhedral oligomeric silsesquioxane based on the combined weight of the polyhedral oligomeric silsesquioxane and the second compound).

[0023] In some embodiments, the curable composition (and hence the cured composition derived therefrom) is substantially free (in other words, comprises less than 1, 0.5, 0.1, 0.05, or even 0.01 % by weight or even none) of particles. Particles can include glass or ceramic beads, fumed silica, glass bubbles, polymeric particles, etc.

[0024] In some embodiments, the curable composition (and hence the cured composition derived therefrom) is substantially free of fluorinated polymer, silicone, or polyethylene glycol. In other words, these components are not purposefully added to the composition during manufacture. Therefore, the curable and cured compositions of the present disclosure do not comprise any of these components or, if there is contamination of the composition by these components, there is very little (for example, less than 0.1, or even 0.01 %by weight) of them in the compositions so that they do not contribute to the olefinic repellency.

[0025] Although not wanting to be limited by theory, it is believed that the (meth)acrylate groups of the polyhedral oligomeric silsesquioxane react with other (meth)acrylate groups in the composition to form a densely crosslinked material. It has generally been discovered that the larger the average (meth)acrylate functionality in the curable composition, the better oleophobic property. In some embodiments, the curable composition has an average (meth)acrylate functionality of at least 5, 5.5, 6, 6.5, or even 7. The average (meth)acrylate functionality is a theoretical calculation determined based on the number of (meth)acrylate groups present in the entire formulation (i.e., from the polyhedral oligomeric silsesquioxane and the second compound).

[0026] Based on the experiments conducted, it is believed that at least some hydroxy functionality is needed to provide oleophobic characteristics to the resulting surface. In some embodiments, the curable composition has an average hydroxy content of at least 0.2, 0.5, 0.8, 1.0, or even 1.5 % by weight based on the total weight of the polyhedral oligomeric silsesquioxane and the second compound. In some embodiments, the curable composition has an average hydroxy content of at most 4, 3, 2.5, or even 2 % by weight based on the total weight of the polyhedral oligomeric silsesquioxane and the second compound. The average hydroxy content is determined by calculating the molecular weight of the hydroxy group and dividing that by the weight of the compound and determining the amount of the compound in the curable composition.

[0027] The curable composition of the present disclosure also includes an initiator which is used to initiate the reaction between the polyhedral oligomeric silsesquioxane and the second compound. Typically, the initiator is a photoinitiator, which can be activated by irradiation with actinic radiation. As used herein, actinic radiation refers to electromagnetic radiation in the ultraviolet, visible, and infrared wavelengths. For example, in one embodiment, the photoinitiator is activated by irradiation of wavelengths from at least 180, 200, 210, 220, 240, 260, or even 280 nm (nanometer); and at most 700,800, 1000, 1200, or even 1500 rnn. In one embodiment, the photoinitiator is activated by irradiation of wavelengths from at least 180, 210, or even 220 nm; and at most 340, 360, 380, 400, 410, 450, or even 500 nm.

[0028] In some embodiments, the curable composition of the present invention comprises an initiator in an amount of 0.1 to 10 parts by mass, preferably 0.1 to 5 parts by mass, and particularly preferably 1 to 5 parts by mass relative to 100 parts by mass relative to the total weight of the polyhedral oligomeric silsesquioxane and the second compound.

[0029] Photoinitiators are known in the art. Examples of suitable free radical photoinitiators include those available under the trade designation OMNIRAD 4265, OMNIRAD 184, OMNIRAD 651, OMNIRAD 1173, OMNIRAD 819, OMNIRAD TPO, and OMNIRAD TPO-L from IGM Resins, Charlotte, NC. Particularly suitable photoinitiators include those that feature high absorbance above 365 nm wavelength. These include the acylphosphine oxide family of photoinitiators such as OMNIRAD TPO, OMNIRAD TPO-L, and OMNIRAD 819.

[0030] In some embodiments, the curable composition further comprises a solvent. The term “solvents” is consistent with the generally understood term of art and encompassing volatile organic and non-organic materials that are liquids at room temperature. The solvents should be compatible with the components in the curable composition and can be used to adjust the viscosity and / or to aid in coating of the curable composition. Exemplary solvents include those known in the art, such as alcohol (e.g., ethanol, isopropanol, etc.), ketones (e.g., acetone), etc.

[0031] The curable composition of the present disclosure may be disposed onto a surface. In some embodiments, the curable composition is coated onto a substrate. For example, the curable composition is coated onto a substrate using techniques known in the art including, for example, dip coating, spray coating, spin coating, blade or knife coating, bar coating, roll coating, and pour coating (i.e., pouring a liquid onto a surface and allowing the liquid to flow over the surface).

[0032] Substrates may include plastics such as polyolefins (e.g., polyethylene, polypropylene), polyester (e.g., polyethylene terephthalate, PET), or polyamides, polycarbonate, polymethacrylate, polystyrene, , polyolefin, epoxy, melamine, triacetylcellulose, acrylonitrile- butadiene-styrene copolymers (ABS), acrylonitrile-styrene copolymers (AS), and norbomene resins; inorganic substrates such as glass, ceramics, metals (e.g., carbon steel, stainless steel, and aluminum), or combinations thereof.

[0033] In some embodiments, after coating, the composition is subsequently, preferably pre-dried with an apparatus such as a hot plate and an oven to remove any solvent, before being exposed to actinic radiation to cure the curable composition.

[0034] In some embodiments, the coating composition of the present disclosure can be cured using actinic radiation, preferably ultraviolet light of UV-B (320 nanometers (nm) to 290 nm) and / or UV-C (290 nm to lOOnm). The irradiation dose of ultraviolet rays is preferably 50 to 500 milli Joules per square centimeter (mJ / cm2). Any ultraviolet light source, as long as part of the emitted light can be absorbed by the photoinitiator, may be employed as a radiation source, such as, a high or low pressure mercury lamp, a cold cathode tube, a black light, an ultraviolet LED, an ultraviolet laser, and a flash light.

[0035] In some embodiments, the resulting cured composition has a thickness of at least 0.1, 0.5, 1, 2, 5, 10, 25, 50, 100, 200, or even 400 micrometers to at most 2, 1, 0.8, 0.6 or even 0.5 millimeters.

[0036] In some embodiments, the cured composition has a styrene static contact angle of at least 17.0, 17.5, 18.0, 19.0, 20.0, 21.0, 22.0, or even 23.0 degrees. Although the formulation was designed to have oleophobic hydroxy content combined with a high crosslink density, it was unexpectedly found that closely related formulations comprised of other hydroxy-(meth)acrylates, other polyhedral oligomeric silsesquioxane (meth)acrylates and other high functionality / high crosslink density (meth)acrylates gave significantly lower contact angles, and in some cases styrene completely wetted out (0° angle) on these surfaces.

[0037] In addition to styrene, the cured compositions of the present disclosure may be useful for other oleophobic applications, where olefins such as toluene, ethylbenzene, benzene, hexadecane, dodecane, decalin, and other reactive olefinic monomers are used or stored.

[0038] Oleophobic coatings are useful is a variety of applications including use with products that repel oil, gasoline, diesel oil, crude oil, vegetable oil, and other hydrocarbons, oils and lipids- in applications such as packaging, membranes (oil-water separation), and anti-fouling, anti-fogging, anti-smudge, antifingerprint, anti-graffiti, and self-cleaning surfaces.EXAMPLES

[0039] Unless otherwise noted, all parts, percentages, ratios, etc. in the examples and the rest of the specification are by weight, and all reagents used in the examples were obtained, or are available, from general chemical suppliers such as, for example, Sigma-Aldrich Company, Saint Louis, Missouri.TABLE 1. Materials List

[0040] Procedure to measure static contact angle on styrene

[0041] A drop shape analyzer (Goniometer DS A30E obtained from KRUSS Scientific, Hamburg, Germany) was used for static contact angle measurements. Styrene was used as the contact liquid. A manual syringe (3mL) with a 25G syringe needle (0.515 mm - outer diameter) was used to dispense the contact liquid onto each Sample surface. Samples with significant curvature of the contact liquid (in other words, did not wet out the surface) were bonded to a glass slide using tape (available as 3M VHB tape, 3M Co., St. Paul, MN) to provide a relatively flat surface for contact angle measurements. 5 to 10 measurements were completed for each Sample surface and the average result was reported.

[0042] The following test parameters were used:• Approximately 2 microliters droplet size per each contact angle measurement.• Syringe thickness was set to 0.515 mm (Styrene).• Ellipse (Tangent -1) was used for the contact angle fitting method.• Refresh rate of camera was set to 100 frames per second.• Brightness set to 60.• Retention time was set to 2 seconds retention time for styrene with the manual syringe setup.

[0043] Average functionality (F av).

[0044] The theoretical average number of (meth)acrylate functional groups in the curable composition is taken from the number of (meth)acrylate groups in the Liquid used (not including the initiator). In instances where multiple components are used to make the Liquid, the number of functional groups for the first component is multiplied by the ratio of the first component in the Liquid and added to the product of the number of functional groups for the second component and the ratio of the second component in the Liquid.

[0045] Wt (weight)% OH content of formulation

[0046] The theoretical value of hydroxy content in the curable composition is determined by calculating the molecular weight of -OH groups divided by the molecular weight of the component. In instances where multiple components are used to make the Liquid, the wt% of OH content in the first component is multiplied by the ratio of the of the first component in the Liquid and added to the product of the wt% of OH content in the second component and the ratio of the second component in the liquid.

[0047] Comparative Examples 1-18 (C1-C18) and Examples 1-3 (E1-E3)

[0048] Hard coats on a polymethylmethacrylate (PMMA) substrate were made as follows: To the liquids designated in Table 2, TPO-L was added to achieve a 3 wt% in the final mixture and the sample was mixed. The liquid mixtures were coated onto the PMMA substrate using a number 10 Meyer rod, the liquid mixture was covered with a transparent polyethylene terephthalate (PET) liner, and UV-cured using LED lights (Clearstone CF1000 UV LED system, Clearstonetech, Hopkins, MN, 395 nm, 100% intensity corresponding to 319 milliWatts / centimeter2for 2 minutes at a distance of 1 centimeter from the surface of the sample). After curing, the PET liner was removed. Smooth transparent hard coats were obtained. Each hard coat was tested for its contact angle with styrene. Shown in Table 2 is the reportedcontact angle, the average functionality of the liquid prior to curing and the OH content of the liquid prior to curing.Table 2

[0049] Foreseeable modifications and alterations of this invention will be apparent to those skilled in the art without departing from the scope and spirit of this invention. This invention should not be restricted to the embodiments that are set forth in this application for illustrative purposes. To the extent that there is any conflict or discrepancy between this specification as written and the disclosure in any document mentioned or incorporated by reference herein, this specification as written will prevail.

Claims

What is claimed is:

1. A curable composition comprising (i) a polyhedral oligomeric silsesquioxane comprising at least two (meth)acrylate groups; (ii) a second compound comprising at least three (meth)acrylate groups and at least one hydroxy group; and (iii) an initiator, wherein the curable composition after cure has a styrene static contact angle of at least 17.0 degrees.

2. The curable composition of claim 1, wherein the polyhedral oligomeric silsesquioxane comprises at least eight (meth)acrylate groups.

3. The curable composition of any one of the previous claims, wherein the polyhedral oligomeric silsesquioxane is an octa(meth)acrylate polyhedral oligosilsesquioxane.

4. The curable composition of any one of the previous claims, wherein the second compound comprises at least five (meth)acrylate groups and one hydroxy group.

5. The curable composition of any one of the previous claims, wherein the second compound consists of carbon, hydrogen, and oxygen atoms.

6. The curable composition of any one of the previous claims, wherein the second compound is dipentaerythritol penta(meth)acry late .

7. The curable composition of any one of the previous claims, wherein the curable composition comprises at least 15 parts and no more than 85 parts by weight of the second compound versus the total weight of the polyhedral oligomeric silsesquioxane and the second compound.

8. The curable composition of any one of the previous claims, wherein the curable composition is substantially free of fluoropolymer, silicone, and polyethylene glycol.

9. The curable composition of any one of the previous claims, wherein the curable composition has an average (meth)acrylate functionality of at least 5.

10. The curable composition of any one of the previous claims, wherein the curable composition has an average hydroxy content of at least 0.2 wt%.

11. The curable composition of any one of the previous claims, wherein the initiator is a photoinitiator.

12. A cured composition derived from (i) a polyhedral oligomeric silsesquioxane comprising at least two (meth)acrylate groups; (ii) a second compound comprising at least three (meth)acrylate groups and at least one hydroxy group; and (iii) an initiator, wherein the cured composition has a styrene static contact angle of at least 17.0 degrees.

13. The cured composition of claim 12, wherein the cured composition has a styrene contact angle of at least 19.0 degrees.

14. The cured composition of any one of claims 12-13, wherein the cured composition is disposed on a surface.

15. The cured composition of claim 14, wherein the surface comprises a polyolefin, polyester, polyamide, glass, metal, or combinations thereof.

16. A method of making an oleophobic surface, the method comprising(a) disposing a coating composition onto a surface, wherein the coating composition comprises (i) a polyhedral oligomeric silsesquioxane comprising at least two (meth)acrylate groups; (ii) a second compound comprising at least three (meth)acrylate groups and at least one hydroxy group; and (iii) an initiator; and(b) initiating the initiator to form a cured coating, wherein the cured coating has a styrene static contact angle of at least 17.0 degrees.

17. The method of claim 16, wherein the coating composition is exposed to ultraviolet light to initiate the initiator.

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