US-12617943-B2 - Photocurable compositions and method of forming topographical features on a membrane surface using photocurable compositions

Abstract

Photocurable compositions and methods of preparation and use of such compositions. More particularly, photocurable compositions useful for forming topographical features on surfaces such as membrane surfaces. Methods of forming topographical features on a membrane surface using photocurable compositions.

Inventors

• Michael M Izzo
• Ivan Gustaf Johnson
• Shuhua Jin

Assignees

• HENKEL AG & CO. KGAA

Dates

Publication Date

20260505

Application Date

20221117

Claims (6)

1. 1 . A light curable composition comprising: a. a light curable component comprising a backbone selected from the group consisting of (meth)acrylates, epoxies, polyisobutenes (PIB), polyurethanes (PU), polyolefins (PO), ethylvinylacetates (EVA), polyamides (PA) and combinations thereof; and a light curing moiety; b. a cure system; and c. a rheology modifying component present in an amount of about 30% to about 50% by weight of the total curable composition; wherein the light curable composition has a Thixotropic Index (TI) (cp at 1 s−1/cp at 10 s−1) of between about 2 and about 15.
2. 2 . The light curable composition of claim 1 , wherein the cure component comprises an ultraviolet light cure component or visible light cure component.
3. 3 . The light curable composition of claim 1 , wherein the rheology modifying component is selected from the group consisting of silica, silicate, alumina, asbestos, barium sulphate, calcium carbonate, calcium fluoride, carbon black, clays, diatomaceous earth, feldspar, ferromagnetics, fly ash, glass fibers, gypsum, jute fiber, kaolin, lingnocellulosics, magnesium hydroxide, mica, microcrystalline cellulose, powdered metals, quartz, starch, talc, titanium dioxide, wood flour, wood fibers, thermoplastic polymers, and combinations thereof.
4. 4 . The light curable composition of claim 1 , wherein the light curable composition subsequent to cure is capable of less than about 5% weight loss when submerged in a aqueous solution at a pH range of about 0.5 to about 13.5 at temperatures of from about 25° C. to about 90° C. for in a 6 week period.
5. 5 . The light curable composition of claim 1 , wherein the light curable composition is capable of forming and maintaining topographical surface features having an aspect ratio (height/width) of between about 0.2 to about 2 prior to full cure.
6. 6 . The light curable composition of claim 1 , wherein the light curable component comprises a material selected from the group consisting of a urethane (meth)acrylate and a (meth)acylate.

Description

BACKGROUND Field The present invention relates to photocurable compositions and methods of preparation and use of such compositions. More particularly, the present invention relates to photocurable compositions useful for forming topographical features, e.g., spacer features, on surfaces such as membrane surfaces, and particularly on membranes used in osmosis and reverse-osmosis applications, such as membrane filters. Brief Description Related Technology Curable compositions have been used widely for sealing, adhesive, coating and potting applications, to name a few. The choice of the type backbones and curable groups is generally selected with reference to the specific end use application and the environment in which it is intended to be used. Polymers having various degrees of unsaturated groups, as well as other functionally crosslinking groups have been used. Formation of spacer features on filtration devices and osmosis membranes used in such devices is known. The use of curable composition patterns printed onto membrane surfaces serve as replacements for more conventional mesh layers which allow liquid, such as water, to flow and also to keep the filtration membranes apart by providing a spacing function. The formation of curable composition patterns on a membrane has been discussed as having distinct advantages over mesh layers, particularly because the patterns provide less obstruction of flow and less build-up of filter debris (commonly referred to as fouling). Moreover, spacers placed directly on the surface of the membrane may have a height reduced by 50% when compared to a convention mesh spacer. A smaller spacer height in a traditional mesh would not be possible as it would dramatically increase feed pressure as well as pressure drop across the element. The smaller height of the printed spacers does not appear to reduce feed pressure significantly. The benefit of the smaller printed spacer height is that it allows for more membrane to be rolled into the element to produce the same specified diameter as the traditional mesh at a greater spacer height. For example, in certain instances, the printed spacers allow for 7 additional leaves to be utilized, for a total of 35 leaves rather than the traditional 28 leaves in the same 8 inch diameter element (i.e., 25% more). In other cases, 3 more leaves may be added, for a total of 10 leaves rather than the typical 7 leaves in a 4 inch diameter element (i.e., 40% more). There are many difficulties in manufacturing, on a commercial scale, membranes having printed curable composition patterns, i.e. referred to herein as topographical features. The topographical feature must have a size and shape which provides sufficient spacing from the adjacent layer, balanced with a minimum coverage of the surface area of the membrane to allow a maximum of fluid flow. Moreover, many curable compositions cannot meet the requirements in terms of chemical and temperature resistance to hold up to the cleaning cycles required for these applications. In addition, the curable composition is required to have high bond strengths to the membrane while also not being too brittle to damage the membrane during rolling or too soft and flexible that will compress and lose the specified spacing required while under pressure in use. While UV inks are capable of high aspect ratios and fast cures, they are limited by how high they can print in a single pass. Generally, many passes of curable composition deposition are required over the same area to build the heights required for these applications, which dramatically slows the printing speed and production of the final product. Standard light cure acrylics (LCA's) or even gel LCA's are not able to meet the requirements necessary for achieving certain heights as they have low aspect ratios. If jet printing is used (jetting) the impact velocity of the curable composition when it hits the membrane further reduces the aspect ratio. Jetting is able to double the print speeds, but at a great loss to the aspect ratio. Polyolefin (PO) hot melt curable compositions with gravure printing allows very fast production speeds of printed membranes, however, it has the slowest cure speed due to cooling, which can take 30 seconds or more, and which requires larger accumulation space to not damage the pattern. The PO hot melt's aspect ratio is not adequate when used at the high viscosities necessary for gravure printing. Print height is limited to maximum print height possible by a single print pass because multiple prints passes are not possible using this technique. Accordingly, the aspect ratio is limited by the limited print height. Moreover, the PO hot melt process is prone to stringing and long start-up times with large membrane waste, which is very expensive in this market/application. Thus, in this market, the PO hot melt process is not an efficient process. There is a need for a curable composition and a process of using such composition which all