MX2011002221A

MX2011002221A - Article formed from electrospinning a dispersion.

Info

Publication number: MX2011002221A
Application number: MX2011002221A
Authority: MX
Inventors: Randal M Hill; Eric J Joffre; Donald T Liles; Bonnie J Ludwig
Original assignee: Dow Corning
Priority date: 2008-08-29
Filing date: 2009-08-28
Publication date: 2011-08-03
Also published as: JP2012501390A; CN102187022A; WO2010025381A3; WO2010025381A2; EP2318575A2; WO2010025381A4; CN102187022B; US20110165811A1; CA2735440A1; TW201016909A; KR20110058827A; IL211432A0

Abstract

An article of fibers includes a cured compound. The fibers are formed from electrospinning a dispersion. The dispersion includes a liquid and a condensation curable compound. A content of the liquid in the dispersion is reduced such that the condensation curable compound cures. The article is formed from a method of manufacturing which includes the step of forming the dispersion. The method also includes the step of electro spinning the dispersion to reduce the content of the liquid such that the condensation curable compound cures.

Description

ARTICLE FORMED FROM THE ELECTROHYLATURE OF A DISPERSION FIELD OF THE INVENTION The present invention relates in general to an article and a method for manufacturing the article. More specifically, the method includes forming a dispersion including a liquid and a condensation curable compound and electrospinning the dispersion to manufacture the article.

DESCRIPTION OF THE RELATED TECHNIQUE The development of fibers that have micro- and nano-diameters is currently the center of much research and development in industry, academia, and government. These types of fibers may be formed of organic and inorganic materials such as polyaniline, polypyrrole, polyvinylidene, polyacrylonitrile, polyvinyl chloride, polymethyl methacrylate, polythiophene, and polyacetylene added with iodine. Fibers of this type have also been formed from hydrophilic biopolymers such as proteins, polysaccharides, collagens, fibrinogens, silks, and hyaluronic acid, in addition to polyethylene and synthetic hydrophilic polymers such as polyethylene oxide.

Many of these types of fibers can be formed through a process known in the art as electrospinning. Electro-spinning; It is a versatile method which includes the use of an electric charge to form a mesh of fibers. Typically, electrospinning includes loading a solution into a syringe and driving the solution to the tip of the syringe with a syringe pump to form a droplet at the tip. Electrospinning commonly also includes applying a voltage to the needle to form an electrified jet of the solution. The jet is then elongated and continuously coiled by electrostatic repulsion until it is deposited in a grounded collector, thus forming the fiber mesh.

The fibers that are formed through electrospinning can be used in a wide variety of industries including in medical and scientific applications. More specifically, these types of fibers have been used to reinforce certain compounds. These fibers have also been used to produce nanometer tubes used in medical dialysis, gas separation, osmosis, and water treatment. ' In some applications, the fibers are formed by electrospinning several types of two and three phase systems such as emulsions. The electrospinning techniques that are used with these systems typically produce fibers that exhibit undesirable mechanical characteristics that make brittle and brittle fibers. In accordance with the above, there remains an opportunity to form articles of fibers that are formed from dispersions and that exhibit improved strength and tension properties. There also remains an opportunity to develop a method to form such articles.

SUMMARY OF THE INVENTION AND ADVANTAGES The present invention provides a fiber article and a method for manufacturing the article. The fibers include a cured compound and a dispersion is formed by electrospinning. The dispersion includes a liquid and a curable compound. The method includes the steps of forming the dispersion and electrospinning the dispersion. In one embodiment, the method includes the step of curing the curable compound.

The electrospinning of the dispersion allows the fibers that are formed to exhibit typical characteristics of the cured composite and exhibit improved strength and tensile properties. This fiber formation allows the most efficient and accurate production of a variety of materials to be used in the medical, scientific, and manufacturing industries. The use of the dispersion also allows a variety of condensation-curable types of compounds to be used to form products that can be manipulated based on desired physical and chemical properties.

BRIEF DESCRIPTION OF THE DRAWING Other advantages of the present invention are they will readily appreciate, as it is better understood by reference to the following detailed description when considered in connection with the accompanying drawing in which Figure 1 is a scanning electron microscope image of an article including fibers of the present invention. invention including fiber-fiber joints and spherical defects.

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an article that includes fibers (i.e., an article of fibers), as shown in Figure 1. The present invention also provides a method for manufacturing the article. The method, which includes the electrospinning step, is described in more detail below.

The article may include a single layer of fibers or multiple layers of fibers. As such, the article can have a thickness of at least 0.01 μ. More typically, the article has a thickness of from about 1 μp? up to about 100 μ ?? and more typically has a thickness of about 25 μp? to approximately 100 μ? a. The article is not limited to any particular number of fiber layers. The article may be woven or non-woven, and may exhibit a microphase separation. In one embodiment, the fibers and the article are not woven and the article is further defined as a mesh. In another modality, fibers and article are not woven and the article is also defined as a network. Alternatively, the article may be a membrane. The fibers may also be uniform or non-uniform and may have any surface irregularity. The article can be waterproof, water resistant, fire resistant, electrically conductive, self-cleaning, water drainer, strength reducer, and combinations thereof. In one embodiment, the article is a coating. It is also contemplated that the article may be a fabric, a breathable fabric, a filter, or combinations thereof. In addition, the article can be used in a variety of industries such as in catalysts, filters, solar cells, electrical components, transdermal patches, bandages, drug delivery systems, and in antimicrobial applications. Another potential application for the article is that it can be used as a porous superhydrophobic membrane for oil-water separation or for use in biomedical devices, such as for blood vessel replacements and uses in burn dressings to provide breathability without sticking.

The article may be a superhydrophobic fiber mesh and may exhibit a water contact angle greater than about 150 degrees. In several modalities, the article exhibits contact angles with the water from 150 to 180, 155 to 175, 160 to 170, and 160 to 165, degrees. The article may also exhibit a hysteresis of contact angle with water below 15 degrees. In various embodiments, the article exhibits hysteresis of contact angle with water of from 0 to 15, from 5 to 10, from 8 to 13, and from 6 to 12. The article may also exhibit an isotropic or non-isotropic nature of the angle of contact with water and / or hysteresis of contact angle with water. Alternatively, the article may include domains that exhibit an isotropic nature and domains that exhibit a non-isotropic nature.

The fibers may also be of any size and shape and are typically cylindrical. Typically, the fibers have a diameter of from 0.01 to 100, more typically from 0.05 to 10, and more typically from 0.1 to 1, microns (μp). In various embodiments, the fibers have a diameter of from 1 nm to 30 microns, from 1-500 nm, from 1-100 nm, from 100-300 nm, from 100-500 nm, from 50-400 nm, from 300- 600 nm, 400-700 nm, 500-800 nm, 500-1000 nm, 1500-3000 nm, 1000-5000 nm, 2000-5000 nm, or 3000-4000 nm. The fibers also typically have a size of from -5 to 20 microns and more typically have a size of from 10-15 microns. However, the fibers are not limited to any particular size. Fibers are often referred to as "fine fibers", which comprise fibers that they have both micrometer-scale diameters (ie, fibers having a diameter of at least 1 mire) and fibers having "nanometer-scale diameters" (i.e., fibers having a diameter less than 1 mire). have a vitreous transition temperature (Tg) of from 25 ° C to 500 ° C.

The fibers can also be connected to each other by any means known in the art. For example, the fibers can be fused in places where they overlap or can be physically separated so that the fibers are only placed one on top of the other in the article. It is contemplated that the fibers, when connected, can form a network or mesh having pore sizes from 0.01 to 100 μ ??. In various modalities, the pore sizes vary in size from 0.1-100, 0.1-50, 0.1-10, 0.1-5, 0.1-2, or 0.1-1.5, microns. It should be understood that the pore sizes may be uniform or non-uniform. That is, the article may include different domains with different pore sizes in each domain or between domains. In addition, the fibers may have any transverse profile including, but not limited to, a transverse profile similar to a tape, an oval cross profile, a circular cross section, and combinations thereof. In some embodiments, the "beading" of the fibers can be observed, which may be acceptable for most applications.

The presence of beading, the cross-sectional profile of the fiber (varying from circular to lath-shaped), and the diameter of the fiber are functions of the conditions of a method in which the fibers are formed, to be described in more detail or In some embodiments, the fibers may also be fire resistant, as previously mentioned. The fire resistance of the fibers, particularly the non-woven mesh including the fibers, was tested using the UL-94V-0 vertical combustion test on non-woven mesh samples deposited on aluminum foil substrates. In this test, a ribbon of non-woven mesh is held above a flame for approximately 10 seconds. The flame is then removed for 10 seconds and reapplied for another 10 seconds. The samples are observed during this process by hot drifts that diffuse the fire, the presence of delayed flame and residual incandescence, and the distance of combustion along the height of the sample. For non-woven meshes including the fibers according to the present invention, intact fibers were typically observed below those that went into combustion. The incomplete combustion of nonwoven meshes is evidence of self-extinction, a typical behavior of fire retardant materials and excellent fire resistance is estimated. In many - - circumstances, non-woven meshes can still achieve the UL 94 V-0 classification. Without proposing to be limited by any particular theory, it is considered that fire resistance is typically attributed to a low proportion of organic groups to silicon atoms in the fibers. The low proportion of organic groups to silicon atoms is attributed to the absence of organic polymers and organic copolymers in the fibers. However, it is also contemplated that the fire resistance may be due to factors other than the low proportion of organic groups to silicon atoms in the fibers.

The fibers are formed from a dispersion. As is known in the art, dispersions include a phase of matter that is immiscible with, and dispersed in, another phase of matter, i.e., a dispersed phase in a continuous phase. In the present invention, the dispersion includes a liquid and a curable compound, described in more detail below. In one embodiment, the liquid is a non-polar liquid. In another embodiment, the liquid is a polar liquid such as an alcohol, an ionic liquid, or water. Typically, the liquid is water. The water may be tap water, well water, purified water, deionized water, and combinations thereof and may be present in the dispersion in varying amounts depending on the type of dispersion. The liquid can be either the dispersed phase or the continuous phase. In a modality, the dispersion includes solid particles such as the dispersed phase and the liquid as the continuous phase. In another embodiment, the dispersion includes a non-polar liquid such as the dispersed phase and a polar liquid as the continuous phase. In various embodiments, the liquid may be present in amounts of from 20 to 80, from 30 to 70, from 40 to 60, or in an amount of about 50, parts - by weight per 100 parts by weight of the dispersion , provided that the total amount of the dispersion does not exceed 100 parts by weight.

The dispersion can also be defined as a "colloid" or "colloidal dispersion," terminology that can be used interchangeably. Typically, colloids include particles less than 100 nanometers in size - dispersed in the continuous phase. Colloids can be classified in numerous ways. For purposes of the present invention, the colloid can also be classified as a gel (a liquid dispersed phase and a solid continuous phase), an emulsion (a liquid dispersed phase and a liquid continuous phase), and / or a foam (a dispersed phase). of gas and a continuous liquid phase). The colloid can be reversible (that is, it exists in more than one state) or irreversible. In addition, the colloid may be elastomeric or viscoelastic.

In one embodiment, the dispersion is further defined as an emulsion, as it is first introduced immediately - - above. Emulsions are typically classified into one of four categories according to the chemical nature of the phases, dispersed and continuous. As a first category it is an oil-in-water emulsion (0 / W). Emulsions 0 / typically include a non-polar dispersed phase (e.g., oil) in an aqueous continuous phase (e.g., water) that forms droplets, which are typically referred to as emulsion particles. For purposes of the present invention, the term "oil" includes non-polar molecules and may include the curable compound. A second category of emulsion is a water-in-oil (W / 0) emulsion. W / O emulsions typically include a polar dispersed phase in a non-polar continuous phase thus forming an inverted emulsion. A third category is a water-in-oil-in-water emulsion (W / O / W). These types of emulsions include a polar dispersed phase in a non-polar continuous phase which, in turn, is dispersed in a polar continuous phase. For example, W / O / W emulsions may include droplets of water trapped within larger oil droplets which in turn are dispersed: in a continuous water phase. A fourth category is a water-petticoat emulsion (W / W). These types of emulsions include aqueous solvated molecules in a continuous aqueous solution wherein both the aqueous solvated molecules and the continuous aqueous solution include different molecules that are - - soluble in water. Without proposing to be limited by any particular theory, it is considered that the types of emulsions mentioned above depend on hydrogen bonding, pi stacking, and / or the saline bridge of both phases, dispersed and continuous. In this invention, the dispersion can also be defined as any of these four types of emulsions.

As is also known in the art, dispersions are, to a certain degree, unstable. Typically, there are three types of dispersion instability that include (i) flocculation, where particles of the dispersed phase form groups in the continuous phase, (ii) migration of the dispersed phase, where the particles of the dispersed phase are concentrated towards a surface or lower part of the continuous phase, and (iii) breaking and coalescence, where the particles of the dispersed phase join and form a liquid layer in the continuous phase. The present dispersion may exhibit one or more of these types of instability.

The dispersion of the present invention can include particles of varying sizes. In one embodiment, the dispersion includes particles from 1 nm to 10 pm, more typically from 1 nm to 1 μm, and more typically from 1 to 100 nm. In another embodiment, the dispersion can be classified as a nanoemulsion. The dispersion may include particles smaller or larger than the sizes described immediately above, depending on the desire of those experts in the field.

As described initially in the above, the dispersion also includes the curable compound. The curable compound can be any organic or inorganic compound known in the art that can be cured. Non-limiting examples of suitable curable compounds include compounds that are cured by free radical mechanisms, hydrosilation, condensation, addition reactions, ultraviolet light, microwaves, and heat. Examples of such curable compounds include, but are not limited to, peroxides, amides, acrylates, esters, ethers, imides, oxiranes, sulfones, ureas, urethanes, compounds with ethylenically unsaturated bonds, and combinations thereof. In one embodiment, the curable compound is selected from the group of silanes, siloxanes, silazanes, silicones, silicas, silenes, silsesquioxanes, and combinations thereof. In this embodiment, the curable compound is typically cured through free radical mechanisms, condensation, and / or hydrosilation. In various embodiments, the curable compound may be present in amounts of from 20 to 80, from 30 to 70, from 40 to 60, or in an amount of about 50, parts by weight per 100 parts by weight of the dispersion, provided that the: total amount of the dispersion does not exceed 100 parts by weight.

Alternatively, the curable compound can also define itself as a compound curable by condensation. As is known in the art, condensation curable compounds are cured through condensation reactions. Condensation reactions are chemical reactions in which two molecules combine to form a new single molecule, along with the loss of a small molecule, such as water. When water is lost, the condensation reaction can also be known as a dehydration reaction. For descriptive purposes only, a reaction system (dehydration) by general condensation is established below: R3Si-OH + HO-SiR3 - r "R3SÍ-O-SÍR3 wherein R is an organic or inorganic part. The condensation reaction is not limited to loss of water and may instead include a loss of an organic or inorganic compound or a hydrogen molecule. The condensation reaction can also occur where one or more atoms Si in the range scheme is replaced by a carbon atom (C).

The condensation curable compound may include monomers, dimers, oligomers, polymers, pre-polymers, copolymers, block polymers, star polymers, graft polymers, random co-polymers, macromonomers, telechelic oligomers, nanoparticles, and combinations thereof. .

The term "oligomer" as used herein includes identifiable chemical groups, including dimers, trimers, tetramers and / or pentamers, linked through reactive portions capable of condensation. Examples of preferred organic reactive portions capable of condensation which may be included in the condensation-curable compound include, but are not limited to, hydrolyzable portions, hydroxyl fractions, hydrides, isocyanate fractions, amine fractions, amide fractions, acid fractions , alcohol fractions, amine fractions, acrylate fractions, carbonate fractions, epoxide fractions, ester fractions, and combinations thereof. The condensation curable compound may also include inorganic parts including, but not limited to, silicones, siloxanes, silanes, transition metal compounds, and combinations thereof. In addition to the condensation reactions, the articles of the present invention can also be formed by various addition reactions such as free radical additions, Michael reactions, hydrosilation reactions, and / or Diels Alder reactions. Polymerizations with a ring opening can also be used.

In one embodiment, the condensation curable compound can be any compound of the Provisional Application of E.U. Number 61/003726 filed on 11/20/07, which is expressly incorporated herein by reference. In another embodiment, the condensation curable compound may include organic and inorganic polymers such as polyesters, polyamides, polyimides, polyureas, polyethers, polyamines, polyurethanes, aramides, polycarbonates, carbonates, and combinations thereof. Alternatively, the condensation curable compound can be cured to form a compound selected from the group of polyesters, nylons, polyurethanes, aramides, carbonates, and combinations thereof.

The curable compound (condensation) may be substantially free of silicon (ie, silicon atoms and / or compounds containing silicon atoms). It should be understood that the term "substantially free" refers to a silicon concentration of less than 5,000, more typically less than 900, and more typically less than 100, fractions of compounds that include silicon atoms, per one million parts. of the compound curable by condensation. It is also contemplated that the curable compound (condensation) can be completely free of silicon.

Alternatively, the curable compound (condensation) can include a polymerization product of at least one silicon monomer and an organic monomer. It is contemplated that the organic monomer and / or silicon monomer may be present in the curable compound (condensation) in any volume fraction. In various embodiments, the organic monomer and / or silicon monomer are present in volume fractions of from 0.05-0.9, 0.1-0.6, 0.3-0.5, 0.4-0.9, 0.1-0.9, 0.3-0.6, or 0.05-0.9. .

The organic monomer can include any organic part described above. The term "silicon monomer" includes any monomer that includes at least one silicon atom (Si) such as silanes, siloxanes, silazanes, silicones, silicas, silenes, silsesquioxanes, and combinations thereof. It is to be understood that the silicon monomer may include polymerized groups and retain a silicon monomer as long as it retains the ability to polymerize. In one embodiment, the silicon monomer is selected from the group of silanes, silsesquioxanes, siloxanes, and combinations thereof.

In an alternative embodiment, the curable compound (condensation) is selected from the group of an organosilane, an organopolysiloxane, and combinations thereof. In this embodiment, the organopolysiloxane can be selected from the group of a siloxane terminated at. silanol, a siloxane finished in alkoxylsilyl, and combinations thereof.

The curable compound (condensation) may be linear or non-linear and may include hydroxyl and / or organosiloxy groups (-SiOR) and may include hydroxyl-terminated polydimethylsiloxane. The curable compound (condensation) It can include the general structure: wherein each of R1 and R2 independently includes one of a hydrogen, a hydroxyl group, an alkyl group, an alkyl group substituted by halogen, an alkylenyl group, an aryl group, an aryl group substituted by halogen, an alkaryl group, an alkoxy group, an acyloxy group, a ketoximate group, an amino group, an amido group, an amido acid group, an amino-oxy group, a mercapto group, and an alkenyloxy group, and n can be any integer.

Alternatively, the curable compound (condensation) may include hydrocarbylene and / or fluorocar- bylene groups. The hydrocarbylene groups include a divalent moiety that includes carbon and hydrogen. Fluorocar- bylene groups include a hydrocarbylene moiety with at least one of the hydrogens replaced with at least one fluorine atom. Typical fluorocarblene groups include alkylene groups partially or completely substituted with fluorine. The curable compound (condensation) may also include olefinic portions including acrylate fractions, methacrylate fractions, vinyl fractions, acetylenyl fractions, and combinations thereof.

If the curable compound (condensation) includes a hydroxyl group, the curable organopolysiloxane (condensation) can include siloxanes having at least one terminal silanol group or a hydrogen atom bonded to silicon or a hydrolysable group which, on exposure to moisture, forms groups silanol. Silanol, pendant or terminal groups, or their precursors, allow condensation.

Alternatively, the curable compound (condensation) can also be defined as an elastomer or as a curable elastomer. As is known in the art, "elastomers" are compounds that exhibit elasticity, that is, a capacity to deform under tension and return to the approximately original form. In the present invention, the terminology "elastomer" is not limited to polymer or monomers and can include one or both. Additionally, the elastomer can include any of the curable compounds (condensation) mentioned above. In one embodiment, the curable elastomer is commercially available from Dow Corning Corporation of Midland, MI under the trademark Dow Corning Additive 84.

In one embodiment, the curable compound has a number average molecular weight (Mn) greater than 5,000 g / mol and more typically greater than 10,000 g / mol. However, the curable compound is not limited to such a numerical average molecular weight. In another modality, the curable compound has a number average molecular weight greater than about 100, 000 g / mol. In various other embodiments, the curable compound has numerical average molecular weights of from 100, 000-5, 000, 000, 100,000-1,000,000, 100,000-500,000, 200,000-300,000, greater than approximately 250,000, or approximately 150,000, g / mol In yet another embodiment, the curable compound has a number average molecular weight greater than 50,000 g / mol, and more typically greater than 100,000 g / mol. In alternative embodiments, the curable compound can have a number average molecular weight of at least about 300 g / mol, from about 1,000 to about 2,000 g / mol, or from about 2,000 g / mol to about 2,000,000 g / mol. mol. In other embodiments, the curable compound may have a number average molecular weight greater than 350 g / mol, from about 5,000 to about 4,000,000 g / mol, or from about 500,000 to about 2,000,000 g / mol.

In addition to the curable compound, the dispersion may also include one or more surfactants. In various embodiments, the dispersion includes a (first) surfactant and a second surfactant or multiple surfactants. The surfactant can be combined with the liquid, with the curable compound, or both with the - - liquid as the curable compound, before the formation of the dispersion. Typically, the surfactant is combined with the liquid before the dispersion is formed. Surfactants are also known as active surfactants, surface active solutes, emulsifiers, emulsifiers, and surfactants. Relative to this invention, the terminology "surface active agent", "surface active solutes", "surfactants", "emulsifiers", "emulsifiers", and "surfactants" can be used interchangeably. Surface-active agents reduce the surface tension of a liquid by being absorbed in a liquid-gas inferium. The surfactants: also reduce interfacial tension between polar and non-polar molecules when absorbed in a liquid-liquid interface. Without proposing to be limited by any particular theory, surfactants are considered to act at these interfaces and depend on various forces including excluded volume repulsion forces, electrostatic interaction forces, van der forces, entropic forces, and spherical forces. In the present invention, the surfactant may be chosen or manipulated based on one or more of these forces.

• The surfactant, surfactant agents, first and second agents, or first / second / multiple surfactants can be selected independently from the group of non-active surfactants. - - ionics, cationic surfactants, anionic surfactants, amphoteric surfactants, and combinations thereof. Suitable nonionic surfactants include, but are not limited to, alkylphenol alkoxylates, alcohol ethoxylates including fatty alcohol ethoxylates, glycerol esters, sorbitan esters, glucose and sucrose esters, including alkyl polyglucosides and hydroxyalkyl polyglycosides. , alkanolamides, N-alkylglucamides, alkylene oxide block copolymers such as block copolymers of ethylene oxide, propylene oxide and / or butylene oxide, polyhydroxy and polyalkoxy fatty acid derivatives, amine oxides, polyether based siloxane, and combinations thereof.

Suitable surfactant-cationic agents include, but are not limited to,. interphase-active compounds including ammonium groups such as alkyldimethylammonium halides and compounds having the chemical formula RR 'R "R' '' N + X" wherein R, R ', R ", and R" "are independently selected from the group of alkyl groups, aryl groups, alkylalkoxy groups, arylalkoxy groups, hydroxyalkyl (alkoxy) groups, and hydroxyaryl (alkoxy) groups wherein X is an anion Suitable anionic surfactants include, but are not limited to, In addition, non-limiting examples of suitable anionic surfactants include alkanesulfonates, linear alkylbenzenesulfonates, and linear alkyl toluenesulfonates. Still, the anionic surfactant may include olefinsulfonates and di-sulfonates, mixtures of alkene sulfonates and hydroxyalkane or di-sulfonates, alkyl ester sulphonates, sulfonated polycarboxylic acids, glyceryl alkyl sulfonates, glycerol fatty acid ester sulfonates, Polyglycol ether of; alkylphenol, oiefine sulfonates, paraffinsulfonates, alkyl phosphates, acyl isothionates, acyl taurates, methyl acyl taurates, alkylsuccinic acids, sulfosuccinates, alkenylsuccinic acids and corresponding esters and amides thereof, corresponding alkylsulfosuccinic acids and amides, mono- and di-esters of sulfosuccinic acids, acyl sarcosinates, sulfated alkyl polyglucosides, polyglycol alkyl carboxylates, hydroxyalkyl sarcosinates, and combinations thereof. Suitable amphoteric surfactants include, but are not limited to, aliphatic derivatives of secondary and / or tertiary amines including an anionic group, betaines and combinations thereof.

Additionally, the surfactant and / or surfactant agents, first and second, can independently include aliphatic and / or aromatic alkoxylated alcohols, LAS (linear alkyl benzene sulfonates), paraffin sulfonates, FAS (fatty alcohol sulfates), FAES (fatty alcohol ether sulphates), alkylene glycols, trimethylolpropane ethoxylates, glycerol ethoxylates, pentaerythritol ethoxylates, bisphenol A alkoxylates, and alkoxylates of 4-methylhexanol and 5-methyl-2-propylheptanol, and combinations thereof. Typically, the surfactant is present in an amount of from 0.1 to 100, more typically from 0.:01 to 5, even more typically from 0.5 to 5, and more typically from 1.5 to 5, parts by weight per 100. parts by weight of the dispersion.

The dispersion may also include a thickener. As is known in the art, thickeners increase a viscosity of the dispersion at low cutting speeds while maintaining the flow properties of the dispersion at higher cutting speeds. Thickeners suitable for use in the present invention include, but are not limited to, polyalkylene oxides such as polyethylene oxide, polypropylene oxide, polybutylene oxide, and combinations thereof. In one embodiment, the thickener is selected from the group of algenic acid and its derivatives, polyethylene oxide, polyvinyl alcohol, methyl cellulose, hydroxypropylmethyl cellulose, alkyl and hydroxyalkyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, guar gum, gum arabic, ghatti gum, polyvinyl pyrrolidone, starch, modified starch, tamarind gum, gum, xanthan, polyacrylamide, polyacrylic acid, and combinations thereof. The thickener may also include a nanoparticle such as titanium dioxide and / or nanoclay such as betonite. The thickener can also be conductive, semi-conductive, insulating, magnetic, or light emitting. Alternatively, the thickener may include a conductive polymer such as polypyrrole, polyaniline, and / or polyacetylene. The thickener may also include biological components such as proteins or DNA.

The thickener can be combined with the liquid, with the curable compound, or both with the liquid and the curable compound before the dispersion is formed. Typically, the thickener is combined with the liquid before the dispersion is formed. The thickener is typically present in an amount of from 0.001 to 25, more typically from 0.05 to 5, and more typically from 0.1 to 5, parts by weight per 100 parts by weight of the dispersion.

As is also known in the art, dispersions typically have two different types of viscosities, a total viscosity and a viscosity of the dispersed phase. The dispersion of: the present invention typically has a total viscosity of at least 20 centistokes at a temperature of 25 ° C. In several embodiments, the dispersion has a viscosity of at least 20 centistokes, more typically from about 30 to about 100 centistokes, more typically from about 40 to about 75 centistokes at a temperature of 25 ° C using a Brookfield rotary disk viscometer equipped with a cell thermal and a spindle SC4-31 operated at a constant temperature of 25 ° C and a rotational speed of 5 rpm. The viscosity of the dispersed phase is not limited and is not considered to affect the total viscosity. In one embodiment, the dispersed phase is solid and has an infinite viscosity.

The dispersion may also have zero shear rate viscosity of from 0..1 to 10, from 0.5 to 10, from 1 to 10, from 5 to 8, or approximately 6, PaS; In addition, the dispersion can: have a conductivity of 0.01-25 mS / m. In various modalities, the dispersion conductivity varies from 0.1-10, from 0.1-5, from 0.1-1, from 0.1- 0.5, or is approximately 0.3, mS / m. The dispersion can also have a surface tension of from 10-100 mN / m. In different modalities, the surface tension varies from 20-80, or from 20-50, mN / m. In one embodiment, the surface tension of the dispersion is approximately 30 mN / m. The dispersion can also have a dielectric constant of from 1-100. In various modalities, the dielectric constant is between 5-50, 10-70, or 1-20. In one embodiment, the dielectric constant of the dispersion is approximately 10.

The dispersion may also include an additive. The additive may include, but is not limited to, additives that improve conductivity, salts, dyes, colorants, labeling agents, and combinations thereof. Additives that improve conductivity can contribute to excellent fiber formation, and can also allow the diameters of the fibers to be reduced, especially when the fibers are formed by electrospinning. In one embodiment, the additive that improves conductivity includes an ionic compound. In another embodiment, additives that improve conductivity are generally selected from the group of amines, organic salts and. inorganic salts, and mixtures thereof. Typical conductivity improving additives include amines, quaternary ammonium salts, quaternary phosphonium salts, ternary sulfonium salts, and mixtures of inorganic salts with organic ligands. The most typical conductivity enhancing additives include organic quaternary ammonium salts including, but not limited to, tetrabutylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium iodide, phenyltrimethylammonium chloride, phenyltriethylammonium chloride, phenyltrimethylammonium bromide, iodide. of phenyltrimethylammonium, dodecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, dodecyltrimethylammonium iodide, tetradecyltrimethylammonium chloride, tetradecyltrimethylammonium bromide, tetradecyltrimethylammonium iodide, hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, and hexadecyltrimethylammonium iodide. The additive ÷ may be present in either the continuous or dispersed phase of the dispersion in any amount selected by a person skilled in the art as long as the amount of the additive allows the curing of the curable compound to occur. In various embodiments, the amount of the additive is typically from about 0.0001 to about 25%, more typically from about 0.001 to about 10%, and more typically from about 0.01 to about 1% based on the total weight of the fibers. In one embodiment, the additive includes methylaminomethylpropanol.

Referring now to the method for making the article, the method includes the step of forming the dispersion, described above. The dispersion can be formed by adding the curable compound and the liquid together and mixing. In one embodiment, the method includes the step of adding the condensation curable compound and the liquid together and mixing. The mixing step can include mechanical mixing using lath mixers, paddle mixers, fluidizing paddle mixers, sigma blade mixers, - - tumbling blenders, vortex mixers, feed mixers, vertical mixers, horizontal mixers, rotor-stator mixers, sonicators, Speedmixers®, and combinations thereof.

The present invention is not limited to any particular order of addition. In one embodiment, the dispersion is formed by combining the thickener and water to form a mixture and adding the mixture to the curable compound. Alternatively, the dispersion can be formed by any method known in the art. : The method also includes the stage of electrospinning the dispersion. In one embodiment, this step reduces the content of the liquid (e.g., water) so that the condensation curable compound is cured. Without proposing to be limited by any particular theory, it is considered that the electrospinning causes at least partial evaporation of the liquid, such as water, so that. the condensation curable compound is cured. The loss of solvent can allow the curable compounds to mix, that is, to come into intimate contact, allowing them to heal. Without proposing to be limited by any particular theory, it is considered that the strength of an electric field, used in electrowing, can align the functional groups so that they are more easily in contact. The electrospinning stage can be conducted by any known methodin the matter. A typical electrospinning process includes the use of an electric charge to form the fibers. Typically, the dispersion used to form the fibers is loaded into a syringe, the dispersion is led to a tip of the syringe with a syringe pump, and a droplet forms on the tip of the syringe. The pump allows control of the flow rate of the dispersion used to form the fibers at the spinning head. The flow rate of the dispersion used to form the fibers through the tip of the syringe can have an effect on the formation of the fibers. The flow rate of the dispersion through the tip of the syringe can be from about 0.005 ml / min to about 0.5 ml / min, typically from about 0.005 ml / min to about 0.1 ml / min, more typically from about 0.01. ml / min to approximately 0.1 ml / min, and. more typically from about 0.02 ml / min to about 0.1 ml / min. In a specific modality, the flow velocity of the dispersion through the tip of. The syringe can be approximately 0.05 ml / min.

Then the droplet is typically exposed to a high voltage electric field. In the absence of the high-voltage electric field, the droplet .sale the tip of the syringe in a quasi-spherical shape, which is the result of the surface tension in the droplet. The application of the field Electricity results in the distortion of the spherical shape in that of a cone. The generally accepted explanation for this distortion in the droplet form is that the surface tension forces within the droplet are neutralized by electrical forces. The narrow diameter jets of the dispersion emanate from the tip of the cone. Under certain process conditions, the jet of the dispersion experiences the phenomenon of "basting" instability. This basting instability results in repeated bifurcation of the jet, producing a network of fibers. The fibers are finally collected in a collector plate. It is considered that the liquid, such as water, evaporates rapidly from the dispersion during the electrospinning process, leaving behind the solids portion of the dispersion to form the fibers. and cure the curable compound. The collector plate is typically formed of a solid conductive material such as, but not limited to, aluminum, steel, nickel alloys, silicon flakes, Nylon® fabric, and cellulose (e.g., paper). The collector plate acts as a terrestrial source for the electron flow through the fibers during the electrospinning of the dispersion. As time passes, the number of fibers 1 collected in the collector plate increases and the mesh of non-woven fiber is formed in the collector plate. Alternatively, instead of using the collector plate, the fibers can be collected on the surface of a liquid that is not part of the dispersion, thus achieving an independent non-woven mesh. An example of liquid that can be used to collect fibers is water.

In various embodiments, the electrospinning stage comprises supplying electricity from a DC generator having a capacity of from about 10 to about 100 kilovolts (KV). In particular, the syringe is electrically connected to the generator. The step of exposing the droplet to the high voltage electric field typically involves applying a voltage and an electric current to the syringe. The applied voltage can be from about 5 KV to about 100 KV, typically from about 10 KV to about 40 KV, more typically from about 15 KV to about 35 KV, more typically from about 20 KV to about 30 KV. In a specific example, the applied voltage can be approximately 30 KV. The applied electric current may be from about 0.01 nA to about 100,000 nA, typically from about 10 nA to about 1000 nA, more typically from about 50 nA to about 500 nA, more typically from about 75 nA to about 100 nA. In a specific embodiment, the electric current is approximately 85 nA. Typically, When the electrospinning, the dispersion is at a temperature within 60 ° C of room temperature. More typically, when electrospinning, the dispersion is at a temperature within 60 ° C of a processing temperature.

It is considered that the electrospinning step at least partially cures the condensation curable compound. In one embodiment, the electrospinning stage completely cures the condensation curable compound. In other embodiments, the electrospinning stage does not completely cure, or even partially cure, the curable compound so that an additional healing step is needed. The method may include the drying step to more fully cure the curable compound. When the curable compound is further defined as the condensation curable compound, it is hypothesized that the drying step removes the liquid (e.g., water) and conducts the condensation reaction to the right, i.e., termination.

The method may also include the step of curing the curable compound, as first introduced above. the curing step can be implemented independent of, or in combination with, the electrospinning stage. This step can include any healing step known in the art including, but not limited to, those related to free radical healing, hydrosilylation cure, curing by condensation, curing by UV light, microwave curing, thermal curing, and combinations thereof.

The method may also include the step of annealing the fibers. This step can be completed by any method known in the art. In one embodiment, the annealing step can be used to improve the hydrophobicity of the fibers. In another embodiment, the annealing step can improve a microphase regularity of the fibers. the stage: annealing can include heating the article. Typically, to carry out the annealing step, the article is heated to a temperature above ambient temperature of about 20 ° C. More typically, the article is heated to a temperature of from about 40 ° C to about 400 ° C, more typically from about 40 ° C to about 200 ° C. Heating the item can result in melting; Increased fiber junctions within the article, the creation of chemical or physical bonds within fibers (generally referred to as "degradation"), volatilization of one or more fiber components, and / or a change in the surface morphology of the fibers.

EXAMPLES A series of fibers and a non-woven mesh (i.e., the article of the present invention) are formed according to the present method. The non-woven mesh includes the fibers formed from the dispersion including a silicone elastomer as a condensation curable compound.

More specifically, 2 g of 2.5% polyethylene oxide (2,000,000 number average molecular weight) solution in water are added to 10 g of a dispersion including 63 wt.% Dow Corning 84 Additive in water. Dow Corning 84 Additive includes a mixture of silica and degraded silicone rubber including functional groups that may undergo condensation cure. The polyethylene oxide and the dispersion are agitated to form a translucent white dispersion. The dispersion is then supplied by a syringe / syringe pump to a stainless steel tube with an inner diameter of 1016 millimeters in preparation for electrospinning. An electric field is applied- between the stainless steel tube and a piece of aluminum foil, ground. As the electric field is applied, a droplet on a tip of the stainless steel tube is electrohilated into thin white fibers that are deposited on the foil: milled. The electrospinning stage is carried out in a plate space of 30 cm, a tip protrusion of 3 cm, an applied voltage of 22 kV, and a flow rate of 1 mL / hr. The electrospinning is done for one hour. The resulting fibers are from one to five microns in diameter and tend to have fiber-fiber bonds. Spherical defects are present within the fibers, as shown in Figure 1.

After electrospinning for one hour, the fibers form an opaque white membrane with a thickness of approximately 200 microns. After 24 hours, the membrane is detached from the aluminum foil and tested to determine the tensile properties (strength / tension) at a break point using an Alliance RT / 5 Voltage Tester commercially available from RTS. More specifically, a sample in the form of "dog bone" of the membrane having a width of 0.1 inches in a maximum load cell of 10 N is tested at a tensile speed of 100 mm / min. A resistance-tension curve is also generated. The maximum fiber resistance measurement is approximately 19 psi and the voltage measurement is approximately 120 percent. Additionally, the resistance-tension curve is approximately linear suggesting that the fibers are elastomeric at the point of rupture.

The fibers formed in the aforementioned Example show that the electrospinning of a dispersion allows the fibers exhibiting characteristics of the fiber to be formed; dispersed phase, that is, the compound curable by condensation, as opposed to the continuous phase. The fibers formed in this Example show elastomeric strength and tension properties and an elastomeric resistance-tension curve. The formation of these types of fibers allows the most efficient and accurate production of a variety of materials to be used in the medical, scientific and manufacturing industries. The use of dispersion also allows a variety of types of curable compounds to be used to form new products in this way. The use of, for example, a dispersion in which a continuous phase is water, allows an electrospinning process to be performed through evaporation of a non-hazardous volatile liquid. The use of an active material, for example a bacterium, in the continuous phase, can allow the creation of biologically functionalized fibers that are curable in a one-step process.

The invention has been described in an illustrative manner, and it should be understood that the terminology that has been used is proposed to be in the nature of the words of the description rather than limitation. Obviously, many modifications and variations of the present invention are possible in view of the above teachings, and the invention can be practiced in another way than specifically described.

Claims

1. A method for manufacturing an article comprising fibers formed from a dispersion, said method comprising the steps of: A. forming the dispersion comprising; (i) a liquid, and (ii) a silicone rubber curable by condensation, and B. electrospinning the dispersion to reduce the liquid content so that the condensation-curable silicone rubber is cured through condensation.

2. A method as set forth in claim 1, wherein the dispersion further comprises a surfactant.

3. A method as set forth in claim 2, wherein the surfactant is combined with the liquid before the dispersion is formed.

4. A method as set forth in claim 2, wherein the surfactant is present in the dispersion in an amount of from 0.5 to 5 percent by weight based on the weight of the condensation curable silicone rubber.

5. A method as set forth in claim 1, wherein the dispersion further comprises a thickener.

6. A method as set forth in claim 5, wherein the thickener is further defined as polyethylene oxide.

7. A method as set forth in claim 5, wherein the thickener is combined with the liquid before the dispersion is formed.

8. A method as set forth in claim 5, wherein the thickener is present in the dispersion in an amount of from 0.05 to 5 percent by weight based on the weight of the dispersion.

9. A method as set forth in any of claims 1-8 wherein the dispersion further comprises a condensation curable organic compound.

10. A method as set forth in any one of claims 1-8 wherein the dispersion comprises from 20 to 80 parts by weight of the condensation curable silicone rubber per 100 parts by weight of the dispersion so long as the total amount of the dispersion does not exceed - 100 parts by weight.

11. A method as set forth in claim 10, wherein the dispersion comprises from 20 to 80 parts by weight of the liquid per 100 parts by weight of the dispersion so long as the total amount of the dispersion does not exceed 100 parts by weight.

12. A method as stated in any of claims 1-8, wherein the liquid is further defined as water.

13. A method as set forth in claim 12, wherein the condensation curable silicone rubber is dispersed in water.

14. A method as set forth in any of claims 1-8, further comprising the step of drying the fibers to further reduce the content of the liquid, so that the condensation curable silicone rubber is cured.

15. A method as set forth in claim 1, wherein the dispersion comprises a dispersed phase comprising the condensation curable silicone rubber and a continuous phase comprising the liquid, an agent: surfactant, and a thickener.

16. A method as set forth in any of claims 1-8 or 15, wherein the fibers have a strength of at least 15 psi at break and a tension of at least 100 percent at break.

17. An article of fibers comprising a cured composite and formed by electrospinning a dispersion comprising: A. a liquid; Y B. a silicone rubber curable by condensation; where the content of said liquid is reduced in a that said condensation-curable silicone rubber be cured.

18. An article as set forth in claim 17, wherein said dispersion further comprises a surfactant.

19. An article as set forth in claim 18, wherein said surfactant is combined with said liquid before said dispersion is formed.

20. An article as set forth in claim 18, wherein said surfactant is present in said dispersion in an amount of from 0.5 to 5 percent by weight based on the weight of said condensation curable silicone rubber.

21. An article as set forth in claim 17, wherein said dispersion further comprises a thickener.

22. An article as set forth in claim 21, wherein said thickener is further defined as polyethylene oxide.

23. An article as set forth in claim 21, wherein said thickener is combined with said liquid before said dispersion is formed.

24. An article as set forth in claim 21, wherein said thickener is present in said dispersion in an amount of from 0.05 to 5 per percent by weight based on the weight of said dispersion.

25. An article as set forth in any of claims 17-24, wherein said dispersion further comprises an organic compound curable by condensation.

26. An article as set forth in any of claims 17-24, wherein said dispersion comprises from 20 to 80 parts by weight of said condensation curable silicone rubber per 100 parts by weight of said dispersion provided that the total amount of said dispersion Do not exceed 100 parts by weight.

27. An article . as set forth in claim 26, wherein said dispersion comprises from 20 to 80 parts by weight of said liquid per 100 parts by weight of said dispersion as long as the total amount of said dispersion does not exceed 100 parts by weight.

28. An article as set forth in any of claims 17-24, wherein said liquid is further defined as water. :

29. An article as set forth in claim 17, wherein said dispersion comprises a dispersed phase comprising said condensation curable silicone rubber and a continuous phase comprising said liquid, a surfactant, and a thickener.

30. An article as established in claim 29, wherein said condensation curable silicone rubber comprises a silicone elastomer present in an amount of from 20 to 80 parts by weight per 100 parts by weight of said dispersion, said liquid being further defined as water and being present in an amount from 20 to 80 parts by weight per 100 parts by weight of the dispersion, said surface active agent comprising methylaminomethylpropanol, present in an amount of from 0.5 to 5 parts by weight per 100 parts by weight of said dispersion, said thickener being further defined as an oxide of polyethylene and being present in an amount of from 0.05 to 5 parts by weight per 100 parts by weight of said dispersion.

31. An article as set forth in any of claims 17-24, 29, or 30 which is further defined as a non-woven mesh.

32. A method for manufacturing an article comprising fibers formed from a dispersion, said method comprising the steps of: A. forming the dispersion comprising; (i) a liquid, and (ii) a condensation curable silicone rubber, B. Electrophilize the dispersion to form the C. Curing the silicone rubber curable by condensation.

33. A method as set forth in claim 32, wherein the dispersion further comprises a surfactant and a thickener.

34. A method as set forth in claim 33, wherein the surfactant is present in the dispersion in an amount of from 0.5 to 5 percent by weight based on the weight of the condensation curable silicone rubber.

35. A method as set forth in claim 33, wherein the thickener is further defined as polyethylene oxide.

36. A method as set forth in claim 33, wherein the thickener is present in the dispersion in an amount of from -0.05 to 5 percent by weight of the dispersion. :

37. A method as set forth in any of claims 32-36, wherein the dispersion comprises from 20 to 80 parts by weight of the liquid per 100 parts by weight of the dispersion provided that the total amount of the dispersion does not exceed 100 parts by weight .

38. A method as set forth in any of claims 32-36, wherein the liquid is further defined as water.

39. A method as set forth in claim 38, wherein the condensation curable silicone rubber is dispersed in water. r