Controlled flow polymer blends and products including the same

Abstract

The present invention is directed to polymer blends having controlled flow properties. The polymer blends can be useful in various applications including bonding systems and additive delivery systems, which can provide durable binding and / or delivery and / or affixing of additives. The polymer blends can include at least two different components, at least one being a polymer component having a higher molecular than the other of the components. When heated to an activating temperature, the resultant blend exhibits desirable flow or wet out properties without applied pressure. Despite the controlled flow properties, the blends do not exhibit blocking or fusing properties typically associated with high flow polymer materials.

Description

FIELD OF THE INVENTION[0001]The present invention relates to polymer blends and articles including the same. More particularly, the present invention relates to polymer blends having useful flow or wetting properties without undesirable blocking properties and to products including the same.BACKGROUND OF THE INVENTION[0002]Fibrous materials having various functionalities are useful in many different applications. Often, it can be useful to treat a fibrous material to impart or enhance a particular property thereof, such as flame retardance, UV resistance, and the like.[0003]The functionality of a fibrous material can be modified by introducing a suitable additive into the fibrous structure. Many natural fibers exhibit polar functionality (such as hydroxyl functionality found in cotton fibers), due at least in part to the biological origins of such materials. Nonetheless, functional groups present in many natural fibrous materials can exhibit limited reactivity, and accordingly, addi...

AI Technical Summary

Benefits of technology

[0010]The present invention is directed to polymer blends exhibiting desirable flow properties without also exhibiting the blocking properties typically associated with high flow polymers. The polymer blends of the invention are capable of substantially wetting out a surface at a flow activating temperature without requiring the application of substantial pressure. Yet despite the melt flow properties of the blends, the polymer blend after applying and solidifying further exhibits blocking resistance properties, thereby facilitating manufacturing and downstream storage and transportation of products produced using the polymer blends.

[0011]The polymer blends of the invention include at least two, or more, components that differ from one another with regard to molecular weight. The polymer blend includes a first blend component including at least one polymer having a first molecular weight and a second blend component including at least one compound having a second molecular weight that is less than the first molecular weight of the at least one polymer of the first blend component. The molecular weight of the at least one polymer of the first blend component is sufficiently high to prevent the substantial wet out of the at least one polymer of the first blend component without the application of pressure at the activating temperature of the blend. The second molecular weight of the at least one compound of the second component of the blend is sufficiently low so that the at least one compound of the second component of the blend exhibits a level of molecular mobility sufficient to limit its usefulness by itself for the production of an article such as a fiber or fabric. The at least one compound of the second component of the blend may, for example, exhibit such a high level of molecular mobility that when processed alone, its usefulness is limited because it may be susceptible to blocking, and / or because it may exhibit too much creep, and / or it may have inadequate melt strength or viscosity to be processed. Yet together the blend components can provide a combination of properties including sufficient flow for fiber formation and / or wet-out of a desired substrate without causing problems associated with blocking or creep.

[0012]The polymer blends of the invention can be useful in the production of products, such as binder fibers, that can be tailored to exhibit a range of various properties, such flow rates, activation temperatures, melt strengths, blocking temperatures, and the like, depending on the desired application of the product. The inventor has surprisingly found that polymer blends can be prepared of at least two components having high and low molecular weights, relative to one another, that can exhibit a melt strength that is higher than expected given the resulting viscosity of the blend. This is particularly surprising and useful in that it allows the production of articles, such as fibers, from materials that can have unusually low viscosity when remelted, as for instance when used as a binder fiber. The invention accordingly can provide a mechanism to fine tune polymer formulations for specific applications.

[0013]In exemplary embodiments of the invention, at least one of the components can include a substantially crystalline polymer, which can promote a sharp flow profile. In other exemplary embodiments of the invention, at least one of the components can include a functionalized polymer component, such as a maleic anhydride functionalized polyolefin, which can improve wetting and / or adhesive properties of the blend. In yet other embodiments of the invention, the polymer blend can include at least one additive.

[0016]Other aspects of the invention are directed to a polymeric delivery system and additive delivery methods using the same. The polymeric delivery system of the invention can include the polymer blend described herein in combination with an additive, and can also be provided in the form of an article, such as a fibrous material, film, foam, coating, a particulate material, and the like. The polymer delivery system can be applied to a substrate and treated (heated) to promote flow and form a coating. In this embodiment of the invention, the coating can be relatively low add on, can be substantially discontinuous (for example small islands) or substantially continuous, and / or can be applied in a pattern by various techniques. The coating may also be thin and / or flexible, which can aid durability.

Problems solved by technology

The at least one compound of the second component of the blend may, for example, exhibit such a high level of molecular mobility that when processed alone, its usefulness is limited because it may be susceptible to blocking, and / or because it may exhibit too much creep, and / or it may have inadequate melt strength or viscosity to be processed.

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