Hydrophilic additive

Details Hydrophilic additive Hydrophilic additive

2001-02-13

2004-03-02

Niland, Patrick D. (Department: 1714)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

At least one aryl ring which is part of a fused or bridged...

C264S211220, C264S211000, C442S059000, C442S118000, C442S327000

Reexamination Certificate

active

06699922

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority of German patent application number 100 155 54.5, filed on Mar. 30, 2000.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT
Not Applicable.
BACKGROUND OF THE INVENTION
For many applications, the surface of polymeric articles of manufacture must possess specific properties such as the improved wettability with polar liquids such as water; this would be useful for the manufacture of personal hygiene articles, for example.
Personal hygiene articles, such as diapers or sanitary napkins, are manufactured using materials capable of absorbing aqueous fluids. To prevent direct contact with the absorbent material in use and to increase the wear comfort, this material is sheathed with a thin, water-pervious nonwoven fabric. Such nonwovens are customarily produced from synthetic fibers, such as polyolefin or polyester fibers, since these fibers are inexpensive to produce, have good mechanical properties and possess heat resistance. However, untreated polyolefin or polyester fibers are unsuitable for this purpose, since their hydrophobic surface makes them insufficiently pervious to aqueous fluids.
It is in principle possible to impart the requisite hydrophilic properties to fibers by coating the fibers with appropriate spin finishes or by including suitable additives in the polymer material from which the fibers are produced. The latter is described in U.S. Pat. No. 5,439,734, which discloses diesters of polyethylene glycol with fatty acids having up to 18 carbon atoms or derivatives thereof as suitable durable additives.
SUMMARY OF THE INVENTION
The present invention provides for the use of di-C
10-12
fatty acid esters of polyethylene glycol which can be made by reacting one mole of polyethylene glycol with 2 moles of a fatty acid having 10 to 12 carbon atoms or derivatives thereof. These esters function as additives for the permanent hydrophilicization of polyolefinic materials.
It has now been found that, surprisingly, selected diesters of polyethylene glycols have better properties with regard to the hydrophilic finishing of polymeric materials than the compounds disclosed in U.S. Pat. No. 5,439,734.
Accordingly, one aspect of the invention relates to a process for increasing the hydrophilicity of a polymer comprising adding to the polymer an effective amount of a di-C
10-12
fatty acid ester of polyethylene glycol.
Another aspect of the invention relates to a process for making a synthetic fiber having increased hydrophilicity comprising the steps of: (1) adding an effective amount of a di-C
10-12
fatty acid ester of polyethylene glycol to a polymer to form a mixture; (2) heating the mixture to form a melt; and (3) spinning the melt into a fiber.
Yet another aspect of the invention relates to a non-woven fabric having increased hydrophilicity which comprises synthetic fibers comprised of a polymer containing an effective amount of a di-C
10-12
fatty acid ester of polyethylene glycol.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
Not Applicable
DETAILED DESCRIPTION OF THE INVENTION
The term additive as used herein means di-C
10-12
fatty acid esters of polyethylene. These additives can be added to or incorporated into polymeric materials which are subsequently made into fibers, fabrics, such as nonwovens, films and foams having permanent hydrophilicization because of the presence of one or more of the additives. The additives according to the invention can be added to any type of polymeric material that can be formed into fibers. Such fibers are commonly known as synthetic fibers because they are made from synthetric polymers. These polymers include, but are not limited to, all types of polyolefins such as homopolymers and copolymers of ethylene or propylene and blends of polyolefins with copolymers such as, for example, poly(ethylene) such as HDPE (high density polyethylene), LDPE (low density polyethylene), VLDPE (very low density polyethylene), LLDPE (linear low density polyethylene), MDPE (medium density polyethylene), UHMPE (ultra high molecular polyethylene), CPE (crosslinked polyethylene), HPPE (high pressure polyethylene); poly(propylene) such as isotactic polypropylene; syndiotactic polypropylene; metallocene propylene, impact-modified polypropylene, random copolymers based on ethylene and propylene, block copolymers based on ethylene and propylene; EPM (poly[ethylene-co-propylene]); EPDM (poly[ethylene-co-propylene-co-conjugated diene]); poly(styrene); poly(methylstyrene); poly(oxymethylene); metallocene-catalysed alpha-olefin or cycloolefin copolymers such as norbornene-ethylene copolymers; copolymers containing not less than 60% of ethylene and/or styrene and not more than 40% of monomers such as vinyl acetate, acrylic esters, methacrylic esters, acrylic acid, acrylonitrile, vinyl chloride. Examples of such polymers are: poly(ethylene-co-ethyl acrylate), poly(ethylene-co-vinyl acetate), poly(ethylene-co-vinyl chloride), poly(styrene-co-acrylonitrile); graft copolymers and also polyblends, i.e. blends of polymers including, inter alia, the aforementioned polymers, for example polyblends based on polyethylene and polypropylene.
While all types of polyolefins are preferred polymers according to the invention, homo- and copolymers based on ethylene and propylene are particularly preferred. One embodiment of the present invention accordingly comprises using polyethylene only as the polyolefin, while another embodiment utilizes polypropylene exclusively and yet another embodiment copolymers based on ethylene and propylene.
The additives according to the invention are diesters of polyethylene glycol, also known as polyoxyethylene, wherein the acid moiety of the esters is a saturated or unsaturated, including polyunsaturated, aliphatic moiety having from 10 to 12 carbon atoms. Examples of such acids include, but are not limited to, decanoic acid or capric acid, undecanoic acid or undecylic acid, dodecanoic acid or lauric acid, 4-decenoic acid or obtusilic acid, 9-decenoic acid or caproleic acid, 11-undecenoic acid or undecylenic acid, 3-dodenoic acid or linderic acid, and the like. The di-C
10-12
fatty acid esters of polyethylene glycol according to the invention can be made by reacting polyethylene glycols, preferably having a molecular weight of 300 to 600 and more preferably those having a molecular weight of 400, with fatty acids having 10 to 12 carbon atoms or derivatives thereof in a conventional manner, preferably in the presence of catalysts.
In a very particularly preferred embodiment of the invention, the additives are used in polypropylene fibers and are comprised of saturated fatty acids having 10 to 12 carbon atoms. Methyl esters of C10 to C12 fatty acids are preferred as fatty acid derivatives. The alcohol component and the acid component are reacted in a molar ratio of about 1:2. Particularly preferred esters are the di-decanoate and di-laurate esters of polyethylene glycol having a molecular weight of 400 and mixtures of such esters. It is also possible to react mixtures of the acids with the polyethylene glycol.
The amount of additive that can be used in the processes and compositions according to the invention is an effective amount which is any amount required to bring about a desired degree of hydrophilicity of a particular polymer. The effective amount will typically depend upon the desired degree of hydrophilicity, the polymer and the additive itself and will be readily determinable by one of ordinary skill in the art. Typically, the amount of the additive required to increase the hydrophilicity of a polymer will be from about 0.5% to about 10% by weight of the polymer, preferably the amount will be from about 0.5% to about 5% by weight and most preferably from about 1.0% to about 2.5% by weight.
The invention further provides a process for producing hydrophilicized polypropylene fibers, wherein polyolefins are mixed with the additives, this mixture is then heated to form a melt and the melt is spun into fibers in a conventional manner. P

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