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Method to make an article comprising polymer concentrate

Method to make an article comprising polymer concentrate description/claims

This invention relates to a method to make an article comprising combining a polymer with a polymer concentrate. The invention also relates to a polymer concentrate, also known as a masterbatch, and a process of making the same.

Polyolefins are widely used in a number of everyday articles, machines, consumer goods, and the like. Polyolefins are relatively inexpensive to produce and are capable of providing a number of useful functions. Polyolefins may be formed into various shapes, films, laminates, and the like. Polyolefins may be coated on, or co-extruded with various substrates. Polyolefins may also be combined with other materials to form a structure having a plurality of layers, each layer having a specific purpose. Laminates, for example, may comprise a plurality of layers, such as a configurationally rigid core layer, an outer liquid-tight layer, an oxygen gas barrier such as a mid-layer of aluminum foil, and/or other layers depending on application needs.

However, polyolefins may have relatively high glass transition temperatures. This may render various polyolefins brittle, inflexible, and thus unsuitable for particular uses, particularly uses at lower temperatures. Many applications of polyolefins would benefit from a polyolefin having useful properties over a wide range of temperatures, and under a variety of conditions. Such useful properties may include both high and low temperatures performance in the areas of impact strength, toughness, flexibility, and the like. One way in which such properties may be obtained is by the addition of plasticizers to polyolefins.

Examples of the addition of plasticizers to polyolefins may be found, for example, in U.S. Pat. Nos. 4,960,820, 4,132,698, 3,201,364, and in WO 02/31044, WO 01/18109, and EP 0 300 689. These and other references are directed to the addition of functionalized plasticizers to polyolefins. Examples of functionalized plasticizers include mineral oils containing aromatic groups. These exampled fail to provide improvements in impact strength, transparency, and other properties of polyolefins. Other references which are directed to the addition of plasticizers to polyolefins include EP 0 448 259, EP 1 028 145, U.S. Pat. Nos. 4,073,782, and 3,415,925.

It would be desirable to utilize compounds such as paraffins to plasticize polyolefins. However, such an approach is taught to be counter to producing improved polyolefins (See e.g., Chemical Additives for Plastics Industry 107-116 (Radian Corp., Noyes Data Corporation, NJ 1987); and WO 01/18109 A1.)

U.S. patent application Ser. No. 10/716,306, filed Feb. 19, 2004 is directed to a plasticized polyolefin composition comprising one or more polyolefins and one or more non-functionalized plasticizers. The plasticized polyolefins produced are reported to comprise improved softness, better flexibility (lower flexural modulus), a depressed glass transitions temperature, and/or improved impact strength when compared to plasticized polyolefins known in the art.

However, a need remains for facile incorporation of plasticizers into polyolefins. Plasticizers are often liquids. On the other hand, polyolefins are typically formulated, compounded, and/or combined as solids or partially molten semi-solids in extruders, mixers, kneaders, and the like. Such processes are not readily amenable to addition of liquids. Addition of liquids to an extruder, for example, may require utilization of metering pumps and extruder configurations in opposite to those useful to produce polyolefin articles of commerce. Accordingly, there remains a need for a method by which plasticizers may be incorporated into polyolefin compositions wherein the plasticizers are in a solid form that is flowable.

This invention relates to a method to make an article comprising:

combining a semi-amorphous polymer having a heat of fusion of less than 70 J/g with a plasticizer and optionally one or more additives, to produce a polymer concentrate;

combining the polymer concentrate with one or more polymers to produce an article precursor; and

forming the article at least partially from the article precursor.

This invention further relates to a method to make an article comprising:

combining a semi-amorphous polymer having a heat of fusion of less than 70 J/g with a semi-crystalline polymer having a melting point of 100° C. or greater, and optionally one or more additives, with a non-functionalized plasticizer to produce a polymer concentrate, pelletizing the polymer concentrate into a plurality of free flowing particles;

combining at least a portion of the particles of the polymer concentrate with one or more polymers to produce an article precursor; and

forming the article at least partially from the article precursor.

In a preferred embodiment, the semi-amorphous polymer comprises 55 to 95 mole % of a first alpha olefin having 2 to 6 carbon atoms (preferably propylene), and 5 to 45 mole % of at least one comonomer comprising an alpha-olefin having 2 to 6 carbon atoms which is different from the first alpha olefin (preferably ethylene), and where the semi-amorphous polymer has a heat of fusion of less than 45 joules per gram, and a tacticity index of 75% or greater.

In another preferred embodiment, the polymer concentrate shows no visible phase separation as demonstrated by the polymer concentrate having no visually detectable loss of the plasticizer on an absorbent surface, after a portion of the polymer concentrate is aged on the absorbent surface for 24 hours at 25° C.

In another preferred embodiment the plasticizer has a VI of 120 or more and a pour point of −10° C. or less.

An article produced according to the above methods is also disclosed. These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and claims.

• Provisional Patent
• Utility Patent

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