JP4100516B2 - High stretch multicomponent fiber containing starch and polymer - Google Patents

Description

  The present invention relates to multicomponent fibers comprising starch and polymers. The fibers have a high elongation and can be used to make nonwoven webs and disposable articles.

  It would be desirable to provide a low cost fiber with improved extensibility or extensibility. It would also be desirable to provide such fibers that incorporate polymer components derived from biorenewable resources. There is also a need for nonwovens that can provide flexibility and extensibility. Nonwoven fabrics that allow high progress with relatively low forces are also desired. They can be used to give sustained compatibility in the product and facilitate the use of various mechanical aftertreatments. In general, extensibility is known to be difficult to achieve without increasing the manufacturing cost of the fiber. Typical methods for increasing fiber extensibility include the use of high cost materials and / or special and often expensive mixing requirements.

  Today, there is a need to be met for stretchable nonwovens that can be made of thermoplastic polymers. The present invention provides stretchable fibers that are cost effective and can be easily processed. The fibers are made from a combination of starch and thermoplastic polymer. The starch and polymer composition is preferably a commercially available device used to make multicomponent fibers.

The present invention relates to multicomponent fibers. The multicomponent fiber comprises a core component that includes a thermoplastic starch, which is surrounded by a thermoplastic polymer component that includes a non-starch thermoplastic polymer. The composition of the multicomponent fiber is in the form of a sheath-core, with the thermoplastic polymer component constituting the sheath and the thermoplastic starch component constituting the core component. The core component may have a single core or more than one core. Multicomponent fibers have higher extensibility than the same thermoplastic single component fibers produced under the same processing conditions.
The invention also relates to nonwoven webs and disposable articles comprising multicomponent fibers. Nonwoven webs can also contain other synthetic or natural fibers that are blended with the fibers of the present invention.

These and other features, aspects, and advantages of the present invention will become better understood upon consideration of the following description, the appended claims, and the accompanying drawings.
All percentages, ratios and proportions used herein are by weight percent of the composition unless otherwise specified. All average values are calculated by "weight" of the composition or its components unless otherwise indicated. “Average molecular weight” or “molecular weight” for polymers refers to number average molecular weight unless otherwise indicated. The number average molecular weight is measured by gel permeation chromatography unless otherwise specified. All patents or other publications cited herein are for the purpose of reference citation and are incorporated herein by reference for all text contained therein. The inclusion of either such patents or publications is not intended to acknowledge that the cited reference is cited as prior art or as prior art of material to the subject invention. . The compositions, products and methods described herein may include or include any or all of the required and / or optional components, ingredients, compositions or steps described herein. Consists essentially of or consists of them.
This specification contains a detailed description of (1) the material of the invention, (2) the shape of the multicomponent fiber, (3) the material properties of the multicomponent fiber, (4) the process, and (5) the article.

(1) Material (Constituent component A: Thermoplastic polymer)
Suitable melting temperatures for the thermoplastic polymer and the thermoplastic polymer component are from about 60 ° C to about 300 ° C, preferably from about 80 ° C to about 250 ° C, and preferably from 100 ° C to 215 ° C. When using a plasticizer or diluent or other polymer to lower the observed melting temperature of the thermoplastic polymer-containing component composition within the above range, a melting temperature higher than 250 ° C. It is also possible to use thermoplastic polymers having (Tm). It may be desirable to use a thermoplastic polymer having a glass transition (Tg) temperature of less than 0 ° C. The thermoplastic polymer component has rheological properties suitable for melt spinning. The molecular weight of the polymer must be high enough to allow entanglement between polymer molecules, but low enough to be melt spinnable. Thermoplastic polymers suitable for melt spinning are about 1,000,000 g / mol or less, preferably about 5,000 g / mol to about 800,000 g / mol, more preferably about 10,000 g / mol to about 700,000 g / mol. mol, and most preferably from about 20,000 g / mol to about 500,000 g / mol.

  The thermoplastic polymer can preferably solidify fairly rapidly under stretch flow, as encountered in known processes for short fibers (spun drawing process), continuous filament or spunbond continuous filament processes. It is also desirable to be able to form a thermally stable fiber structure. As used herein, “thermally stable fiber structure” means that the diameter is measured at 50% relative humidity over a period of 24 hours at 25 ° C. and ambient atmospheric pressure, and the fibers are formed. Defined as not exhibiting significant melting or dimensional changes when placed in that environment within 5 minutes of being. It is believed that it is a significant dimensional change that the measured fiber diameter difference differs by more than 25% using the corresponding fibril diameter measurement as a reference. If the fibril is not round, the minimum diameter should be used in the calculation. The smallest diameter should also be used for 24 hour measurements.

  Suitable thermoplastic polymers include polyolefins such as low density, high density, linear low density or very low density polyethylenes, polypropylene or copolymers thereof, for example polyethylene containing atactic polypropylene or copolymers thereof; polybutylene or the like Copolymers; polyamides such as nylon 6, nylon 11, nylon 12, nylon 46, nylon 66 or copolymers thereof; polyesters such as polyethylene terephthalates or copolymers thereof; ethylene / acrylic acid copolymers, ethylene / maleic acid copolymers, ethylene / Olefin carboxylic acid copolymers such as methacrylic acid copolymers, ethylene / vinyl acetate copolymers or combinations thereof; polyacrylates, polymethacrylates and Li copolymers thereof, such as (methyl methacrylate) s. Non-limiting examples of other polymers include polycarbonates, polyvinyl acetates, poly (oxymethylene), styrene copolymers, polyacrylates, polymethacrylates, poly (methyl methacrylate), polystyrene / methyl methacrylate copolymers, poly Examples include ether imides, polysulfones, and combinations thereof. In some embodiments, thermoplastic polymers include polypropylene, polyethylene, polyamides, polyvinyl alcohol, ethylene acrylic acid, polyolefin carboxylic acid copolymers, polyesters, and combinations thereof.

  Biodegradable thermoplastic polymers are also suitable for use herein. Biodegradable materials, such as molds, fungi and bacteria, when the biodegradable material is buried in the ground or contacted with microorganisms (including contact under environmental conditions that promotes the growth of microorganisms) It is easy to be assimilated by other microorganisms. Suitable biodegradable polymers include biodegradable using an aerobic or anaerobic digestion process, or by the effect of exposure to environmental elements such as sunlight, rain, moisture, wind, temperature, etc. Degradable materials are also included. The biodegradable thermoplastic polymers can be used individually or as a combination of biodegradable or non-biodegradable polymers. Biodegradable polymers include polyesters containing aliphatic constituents. Among polyesters are ester polycondensates containing aliphatic constituents and poly (hydroxycarboxylic) acid. Ester polycondensates include diacid / diol aliphatic polyesters (eg, polybutylene succinate, polybutylene succinate adipic acid copolymers, aliphatic / aromatic polyesters (eg, butylene diol, adipic acid, and Poly (hydroxycarboxylic) acids include lactic acid based homopolymers and copolymers, polyhydroxybutyrate (PHB), or other polyhydroxyalkanoate homopolymers and copolymers. Such polyhydroxyalkanoates include copolymers of PHB having higher chain length monomers of C6-C12 and higher, and US Reissue Patent 36,548 (US Patent RE 36,548) and US Pat. Disclosure in 5,990,271 And polyhydroxyalkanoates.

  Examples of suitable polylactic acids that are commercially available are NATUREWORKS from Cargill Dow and LACEA from Mitsui Chemical. Examples of suitable diacid / diol aliphatic polyesters that are commercially available are polybutylene succinates sold as Showa Highpolymer Company, Ltd., Tokyo, Japan as BIONOLLE 1000 and BIONORE 3000. Acid ester / adipic acid ester copolymer. Examples of suitable aliphatic / aromatic copolyesters that are commercially available are sold from Eastman Chemical as EASTAR BIO copolyester or as ECOFLEX from BASF. Poly (tetramethylene adipate-co-terephthalate).

  The choice of polymer and polymer amount will affect the flexibility, texture and properties of the final product, as will be appreciated by those skilled in the art. The thermoplastic polymer component can include a single polymer species or a blend of two or more non-starch thermoplastic polymers. In addition, other materials can be present in the thermoplastic polymer component, including but not limited to thermoplastic starch. Typically, the non-starch thermoplastic polymer is in an amount of about 51% to 100%, preferably about 60% to about 95%, more preferably about 70% to about 90% of the total weight of the thermoplastic polymer component. Exists.

  The thermoplastic polymer component surrounds the outer surface of the starch component and the starch component from ambient conditions including but not limited to mechanical conditions, thermodynamic conditions, electrical conditions or solvent conditions, or combinations thereof. Can be protected. The thermoplastic polymer component can completely surround the outer surface of the thermoplastic starch component. Thermoplastic polymer components can also make the fibers more functional so that the fibers are more temperature stable, more resistant to solvents, and can be thermally bonded.

(Component B: Thermoplastic starch)
The present invention relates to the use of starch, a low cost naturally occurring biopolymer. The starch used in the present invention is a thermoplastic unstructured starch. The term “destructurized starch” is used to mean starch that no longer has its naturally occurring granular structure. The term “thermoplastic starch” or “TPS” is used to mean a starch with a plasticizer to improve its thermoplastic flow properties so that it can be spun into fibers.

  Natural starch does not melt or flow like conventional thermoplastic polymers. Because native starch generally has a granular structure, it should desirably be “destructurized” or “destructured” before it can be melt processed and spun like a thermoplastic material. It is. Without being bound by theory, the granular structure of starch is characterized by particles with distinct amylopectin and amylose domain structures within the starch particles. This granular structure can be destroyed during destructuring, after which the capacity of the starch component can be expanded in the presence of a solvent or plasticizer. Starches that are destructured in the presence of a solvent or plasticizer typically have a higher viscosity than starch that is not destructured with a solvent or plasticizer. The resulting unstructured starch can be in gelatinized form or in crystalline form when dried and / or slowly cooled, but once broken, the natural starch granular structure is generally It will not return. It is desirable that the starch be sufficiently unstructured so that there are no lumps affecting the fiber spinning process. The destructuring agent used to destructure the starch may remain with the starch during further processing, as long as it is removed so that it does not remain in the fiber spun with starch. It may be a natural one.

  Starch can be destructured in a variety of different ways. The starch can be destructured with a solvent. For example, starch can be destructured by subjecting a mixture of starch and solvent to heat, which can be under pressure and shear, to gelatinize the starch, leading to destructuring. The solvent can also act as a plasticizer and desirably can be retained in the composition to serve as a plasticizer during subsequent processing. A variety of plasticizers are described herein that can act as solvents for destructuring starch. These include low molecular weight or monomer plasticizers, such as but not limited to hydroxyl-containing plasticizers including but not limited to polyols such as mannitol, sorbitol and glycerin. Water can also act as a solvent for starch and can be used to destructure the starch by dissolving it in water.

  In order for starch to flow like conventional thermoplastic polymers and to be melt-spun, starch must have a plasticizer present. When the unstructuring agent is removed, it is generally the nature of the starch that remains unstructured, but the plasticizer imparts thermoplastic properties to the starch component to facilitate fiber spinning. And should be added to the starch component or otherwise contained therein. Thus, the plasticizer present during spinning may be the same as that used to destructure the starch. Alternatively, a separate or additional plasticizer may be added to the starch, especially when the destructuring agent is transient as described above. As long as such additional plasticizer remains in the starch during the fiber spinning process, the plasticizer can be added before, during or after the starch is destructured.

  Suitable naturally occurring starches include corn starch (including, for example, waxy maize starch), potato starch, sweet potato starch, wheat starch, sago palm, tapioca starch, rice starch, soybean starch, kuzukon starch, Examples include, but are not limited to, bracken starch, lotus starch, cassava starch, high amylose corn starch, and commercially available amylose powder. A blend of starches may also be used. Although all starches are useful herein, the present invention is based on natural starch derived from crop sources that has the advantage of being abundantly supplied, easily supplementable, and inexpensive. Implemented normally. Naturally occurring starches, especially corn starch (eg including waxy maize starch), wheat starch and potato starch are starch polymers to choose because of their economics and availability .

  Modified starch may also be used. Modified starch is defined as unsubstituted or substituted starch that has altered its original molecular weight properties (ie, molecular weight has changed but other changes are not necessarily relative to starch). Not done). Many of them may modify, preferably reduce, the molecular weight by any of the techniques well known in the art. For example, these include chemical modification of starch by acid or alkali hydrolysis, acid reduction, redox, enzyme reduction, etc., physical / mechanical degradation (eg, by thermomechanical energy input of processing equipment), or these Combinations are listed. Thermomechanical and oxidation methods offer additional advantages when performed in situ. The actual chemistry and molecular weight reduction method of the starch is not critical as long as the average molecular weight is provided at the desired level or range. Such techniques can also reduce the molecular weight distribution.

  Natural unprocessed starch generally has a very high average molecular weight and a broad molecular weight distribution (eg, natural corn starch averages up to about 60,000,000 grams / mole (g / mol)). Having a molecular weight). It is desirable to reduce the molecular weight of the starch used in the present invention. Molecular weight reduction can be achieved by any technique known in the art, including those described above. The molecular weight range for the unstructured starch or starch blend added to the melt is from about 3,000 g / mol to about 8,000,000 g / mol, preferably from about 10,000 g / mol to about 5,000,000. 000 g / mol, and more preferably from about 20,000 g / mol to about 3,000,000 g / mol.

  Optionally, substituted starch can be used. Chemical modification of starch to provide a substituted starch includes, but is not limited to, etherification and esterification. For example, methyl, ethyl or propyl (or larger aliphatic groups) can be replaced with starch using conventional etherification and esterification techniques as are well known in the art. Such substitution can be made when the starch is in its natural granular form or after the starch has been destructured. Substitution can not only reduce the rate of starch biodegradation, but can also reduce the time, temperature, shear force and / or pressure conditions for destructuring. The degree of substitution of chemically substituted starch is typically about 0.01 to about 3.0, but is not necessarily so, and can be about 0.01 to about 0.06. .

  Typically, the thermoplastic starch is from about 51% to about 100%, preferably from about 60% to about 95%, more preferably from about 70% to about 90% by weight thermoplastic starch component. including. The ratio of starch component to thermoplastic polymer determines the proportion of thermoplastic starch in the bicomponent fiber component. The weight of starch in the composition includes starch and its naturally occurring bound water content. The term “bound water” means the water that is naturally present in the starch before it is mixed with the other components to make the composition of the present invention. The term “free water” means water added in the manufacture of the composition of the present invention. One skilled in the art will appreciate that once the components are mixed into the composition, water can no longer be distinguished by its source. Natural starch typically has a bound water content of about 5% to about 16% by weight of the starch.

(Plasticizer)
One or more plasticizers can be used in the present invention to destructure the starch and make the starch flowable (ie, to make a thermoplastic starch). As mentioned above, plasticizers may be used as destructuring agents for starch. The plasticizer may remain in the unstructured starch component to function as a plasticizer for the thermoplastic starch, or may be removed and replaced with another plasticizer in the thermoplastic starch component. Also good. Plasticizers can also improve the flexibility of the final product, which can be attributed to a decrease in the glass transition temperature of the composition. Plasticizers or diluents for thermoplastic polymer components to lower the melting temperature of the polymer, modify the flexibility of the final product, or improve the overall compatibility with the thermoplastic starch blend May be present. In addition, thermoplastic polymers having higher melting temperatures may be used in the presence of a plasticizer or diluent that suppresses the melting temperature of the polymer.

  In general, plasticizers should be substantially compatible with the polymer components of the present invention in which they are mixed. As used herein, the term “substantially compatible” means that when heated to a temperature above the softening and / or melting temperature of the composition, the plasticizer is present in the components in which it is mixed. It means that a homogeneous mixture with the polymer can be formed.

  Plasticizers herein can include monomeric compounds and polymers. Polymer plasticizers typically have a molecular weight of about 100,000 g / mol or less. Polymer plasticizers can include block copolymers and random copolymers (including their terpolymers). In some embodiments, the plasticizer has a low molecular weight plasticizer, for example, having a molecular weight of about 20,000 g / mol or less, or about 5,000 g / mol or less, or about 1,000 g / mol or less. The plasticizer may be used alone or two or more plasticizers may be used in any particular component of the present invention.

  The plasticizer can be, for example, an organic compound having at least one hydroxyl group, such as a polyol having two or more hydroxyl groups. Non-limiting examples of useful hydroxyl plasticizers include sugars such as glucose, sucrose, fructose, raffinose, maltodextrose, galactose, xylose, maltose, lactose, mannose erythrose and pentaerythritol; erythritol, xylitol, malitol, mannitol And sugar alcohols such as sorbitol; polyols such as glycerol (glycerin), ethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, hexanetriol and polymers thereof; and mixtures thereof. Suitable plasticizers include glycerin, mannitol and sorbitol, among others.

  Also useful herein are hydroxyl polymers such as poloxomers (polyoxyethylene / polyoxypropylene block copolymers) and poloxamines (polyoxyethylene / polyoxypropylene block copolymers of ethylenediamine). It is a plasticizer. These copolymers are available as Pluronic® from BASF Corp., Parsippany, NJ. Suitable poloxamers and poloxamines are available as Synperonic® from ICI Chemicals in Wilmington, Del. Or Tetronic from Basf in Parsippany, NJ. (Registered trademark).

  Also suitable for use herein are organic compounds that do not have hydroxyl groups and that form hydrogen bonds, including urea and urea derivatives; sugar alcohol anhydrides such as sorbitan; animal proteins such as gelatin; sunflower Vegetable proteins such as protein, soy protein, cottonseed protein; and mixtures thereof. Other suitable plasticizers are phthalates, dimethyl succinate and diethyl succinate and related esters, glycerol triacetate, glycerol monoacetate and diacetates, glycerol monopropionate, dipropionate and tripropionate, butanoate , Stearates, lactic acid esters, citrate esters, adipic acid esters, stearic acid esters, oleic acid esters, and other further acid esters that are biodegradable. For example, aliphatic acids based on ethylene acrylic acid, ethylene maleic acid, butadiene acrylic acid, butadiene maleic acid, propylene acrylic acid, propylene maleic acid, and other hydrocarbons.

  The amount of plasticizer depends on the molecular weight and amount of starch and the plasticizer's affinity for the starch or thermoplastic polymer. An amount that effectively plasticizes the polymer component can be used. The plasticizer must sufficiently plasticize the starch component so that the starch component can be effectively processed to form fibers. In general, as the molecular weight of starch increases, the amount of plasticizer increases. Typically, the plasticizer may be present in an amount from about 2% to about 70% of the component with which it is mixed, and even from about 5% to about 55%, or from about 10% to about 50%. possible. The polymer incorporated in the starch component that functions as a plasticizer for the starch should be considered as part of that component's plasticizer component of the present invention. The plasticizer is optional for the thermoplastic polymer component in the present invention and amounts of 0% or less than 2% are not meant to be excluded.

(Optional substance)
Optionally, other ingredients may also be incorporated into the thermoplastic starch and thermoplastic polymer composition. These optional ingredients may be present in an amount up to about 49% by weight of the component, or from about 0.1% to about 30%, or from about 0.1% to about 10%. Any material may be used to modify processability and / or to modify physical properties such as elasticity, tensile strength, and modulus of the final product. Other effects include, but are not limited to, stability including oxidation stability, brightness, color, flexibility, elasticity, workability, processing aids, viscosity modifiers, and odor control. A preferred processing aid is magnesium stearate. Another optional material particularly desired in the starch component is ethylene acrylic acid, which is marketed by Dow as Primacor. Examples of optional ingredients can be found in US patent application Ser. No. 09 / 853,131, which is hereby incorporated by reference in its entirety.

(2) Shape The fibers of the present invention are at least bicomponent fibers. As used herein, a component means a segmented portion of a fiber that has a spatial relationship with another portion of the fiber. The term multicomponent, as used herein, is defined as a fiber having more than one segmented portion in spatial relationship to each other. The term multicomponent includes two components that are defined as fibers having two compartments in spatial relation to each other. Different components of the multicomponent fiber are placed in substantially discernable areas across the fiber cross section and extend continuously along the length of the fiber.

  As noted above, either or both of the required components may be multi-component components. A component, as used herein, is defined as meaning a chemical species of a substance or material. Multicomponent fiber, as used herein, is defined to mean a fiber, or a component of a fiber, that contains two or more chemical species or materials.

  The multicomponent fiber of the present invention may be in any of several different shapes as long as the thermoplastic polymer component surrounds the starch component. Bicomponent fibers can be, for example, sea-island (a plurality of starch constituent cores are surrounded by a thermoplastic polymer sheath) or sheath-core shape (a single starch constituent core is a thermoplastic polymer constituent). In which the starch component is completely surrounded by the thermoplastic polymer.

The multicomponent fiber may be in the shape of an island or other sheath-core, where the starch is completely surrounded, i.e. surrounded by a thermoplastic polymer.
1A-1E are cross-sectional views of bicomponent fibers having a sheath / core shape. Component X is a starch component because it is always surrounded by component Y, which is a thermoplastic polymer component.
FIG. 1A illustrates a concentric sheath-core configuration.
FIG. 1B illustrates a sheath-core configuration with a solid core and a shaped continuous sheath.
FIG. 1C illustrates a sheath-core configuration with a hollow core and a continuous sheath.
FIG. 1D illustrates a sheath-core configuration with a hollow core and a shaped continuous sheath.
FIG. 1E illustrates an eccentric sheath-core configuration.
2A to 2C are cross-sectional views of bicomponent fibers having a sea-island shape.
FIG. 2A shows a solid sea-island shape in which the component X is surrounded by the component Y. The shape of the component X is a triangle. FIG. 2B shows a solid sea-island shape in which the component X is surrounded by the component Y. FIG. 2C shows a hollow sea island shape in which component X is surrounded by component Y.

The weight ratio of thermoplastic starch component to thermoplastic polymer component can be from about 5:95 to about 95: 5. In alternative embodiments, this ratio is from about 10:90 to about 65:35 and / or from about 15:85 to about 50:50.
There may be any number of separate segments of components for multicomponent fibers flowing through a single spinneret capillary during fiber manufacture. Typically, the number of segments can range from 2 to about 2000, or from 4 to about 400, or from 8 to about 164, or from about 16 to about 64, but is not limited.

(3) Material Properties The diameter of the fiber of the present invention is typically less than about 200 micrometers (microns), and alternative embodiments are less than about 100 microns, less than about 50 microns, or less than 30 microns. obtain. In one embodiment of the invention, the fiber diameter is from about 5 microns to about 25 microns. The fiber diameter is controlled by factors well known in the fiber spinning field such as spinning speed and mass discharge amount.

The fibers produced in the present invention may be environmentally degradable depending on the amount of starch present, the polymer used, and the specific shape of the fiber. “Environmentally degradable” is defined as being biodegradable, disintegrating, dispersible, flashable, or compostable, or a combination thereof. In the present invention, the fibers, nonwoven webs, and articles may be environmentally degradable.
The fibers described herein are generally used in the manufacture of disposable nonwoven articles. The article is usually flashable. The term “flashable”, as used herein, dissolves, disperses, disintegrates, and / or breaks down in a septic system such as a toilet and flows into the toilet or any other sewer pipe when flushed into the toilet. Represents material that is disposed of without clogging. The fiber and the resulting article may also be water reactive. The term water-reactive as used herein means that an observable and measurable change occurs when placed in water or flushed. Typical observations include observations of article swelling, disassembly, dissolution, or general degradation structures.

  The fibers of the present invention have enhanced extensibility or elongation. Extensibility or elongation is measured by elongation to break. Extensibility or elongation is defined as being extensible under an applied force, but is not necessarily recoverable. Elongation to break is measured as the distance that can be stretched until the fiber breaks. The elongation to break of the single fibers is tested according to ASTM standard D3822, except that a strain rate of 200% / min is used. Testing is performed on an MTS Synergie 400 tensile tester using a 10N load cell and air grip. The test is performed at a speed of 5.08 cm (2 in / min) with a sample with a gauge distance of 2.54 cm (1 in). Pull the sample to break. Record peak stress and percent elongation at break and average over 10 specimens. The “elongation to break” of a fiber is defined as the elongation to break as measured according to the tests and conditions described above. The elongation ratio to break of the fiber of the present invention is the same as the thermoplastic polymer component under essentially the same fiber spinning conditions and parameters, except for the elongation to break of the multicomponent fiber of the present invention. Defined as divided by the elongation to break of the single component fiber produced. In particular, the mass discharge rate of the thermoplastic polymer component, the extrusion melt temperature, the spinneret design and the spinning speed should be the same. The elongation ratio to break for the multicomponent fibers of the present invention should be greater than 1.0 and may be about 1.5 or greater, or about 2.0 or greater.

The fiber of the present invention has low brittleness and high toughness, for example, a toughness of about 2 MPa or more. Toughness is defined as the area under the stress-strain curve.
Nonwoven products made from the fibers of the present invention may also exhibit desirable mechanical properties, particularly strength, flexibility, softness and absorbency. Strength measurements include dry tensile strength and / or wet tensile strength. Flexibility is related to stiffness and can be attributed to flexibility. Flexibility is generally described as a physiologically recognized attribute associated with both flexibility and texture. Absorbency relates to the ability of a product to absorb fluid and to retain that fluid.

(4) Process The 1st process which manufactures a multicomponent fiber is a mixing | blending or mixing process. In the compounding process, the raw materials are typically heated under shear forces. Shearing in the presence of heat produces a uniform melt if the composition is properly selected. The melt is then placed in an extruder where fibers are formed. The fiber collection is combined with each other using heat, pressure, chemical binder, mechanical entanglement, and combinations thereof, resulting in a nonwoven web. Subsequently, the nonwoven fabric is assembled into articles.

(Combination)
The purpose of the compounding process is to produce a homogeneous molten composition of each component of the fiber. Preferably, the molten composition is homogeneous, meaning that there is a uniform distribution of the components in the melt. The resulting melt composition or compositions should be essentially free of water to the fiber being spun. Essentially absent is defined as not causing substantial problems such as creating bubbles that cause the fiber to ultimately break during spinning. The free water content of the molten composition can be about 1% or less, about 0.5% or less, or about 0.15% or less. The total water content includes bound water and free water. Preferably the total water content (including bound water and free water) is about 1% or less. To achieve this low water content, the starch or polymer may need to be dried prior to processing and / or a vacuum may be applied during processing to remove any free water. . The thermoplastic starch or other component of the present invention can be dried prior to spinning at elevated temperatures, such as about 60 ° C. The drying temperature is determined by the chemical nature of the component components. Thus, different compositions can use different drying temperatures, which can range from 20 ° C. to 150 ° C. and are generally below the melting temperature of the polymer. The drying of the components may be, for example, continuous or as a separate process combined with spinning. Techniques for drying as are well known in the art can be used for the purposes of the present invention.

  In general, the components of the components of the present invention can be combined using methods known in the art or suitable for the purposes of the present invention. Typically, such techniques include heat, mixing and pressure. The particular sequence or mixing, temperature, mixing rate or time, and equipment can be varied as will be understood by those skilled in the art, but the temperature should be controlled so that the starch is not significantly degraded. The resulting melt should be homogeneous.

A preferred method of mixing the starch and plasticizer blend is as follows.
1. A plasticizer is added to destructure the starch. If the plasticizer is a solid, such as sorbitol or mannitol, it can be added to the twin screw extruder with starch (powder form). Liquids such as glycerin can be combined with starch via a displacement pump.
2. Starch is completely destructured by applying heat and shear forces in an extruder. The starch and plasticizer mixture is typically heated to 120 ° C. to 180 ° C. for a period of about 10 seconds to about 15 minutes until the starch gelatinizes.
3. Typically, at least once, vacuum can be applied to the melt in the extruder to remove free water. The vacuum can be applied, for example, to a distance of approximately two thirds of the length of the extruder, or other points as desired by the operator.
4). Alternatively, multiple feed zones can be used to introduce multiple plasticizers or starch blends.
5. Alternatively, starch can be mixed with a liquid plasticizer and pumped into the extruder.

  As will be recognized by those skilled in the compounding arts, for starch destructuring, starch melt shaping (including but not limited to feed port location and screw extruder profile). Numerous variations and alternative methods and conditions can be used.

  A suitable mixing device is a twin screw extruder with multiple mixing zones having multiple injection points. Multiple injection points can be used to add unstructured starch and polymer. A twin screw batch mixer or a single screw extrusion system can also be used. As long as sufficient mixing and heat is generated, the particular equipment used is not critical.

  An alternative method of blending the materials involves adding plasticizer, starch and polymer to the extrusion system, where they are mixed at progressively higher temperatures. For example, in a twin screw extruder having six heating zones, the first three zones are heated to 90 ° C., 120 ° C., and 130 ° C., and the latter three zones are heated above the melting point of the polymer. This procedure results in minimal pyrolysis of the starch and the starch is completely unstructured before it is thoroughly mixed with the thermoplastic material.

  An example of blending an unstructured thermoplastic starch is a co-rotating Werner & Pfleiderer (diameter 30 mm, length: diameter ratio 40: 1) set at 26 rad / sec (250 RPM) Using a twin screw extruder, the first two heating zones are set at 50 ° C. and the remaining five heating zones are set at 150 ° C. A vacuum is installed between the penultimate and last heated part and a 10 atm vacuum is drawn. Starch powders and plasticizers (eg, sorbitol) are extruded using, for example, a mass loss feeder with a binding rate of 30 pounds / hour (13.6 kg / hour) and a starch / plasticizer weight ratio of 60/40. Individually fed into a feed throat at the base of the molding machine. A processing aid can be added along with the starch or plasticizer. For example, magnesium separate can be added, for example, in an amount of 0% to 1% by weight of the thermoplastic starch component.

(spinning)
The fibers of the present invention can be made by melt spinning. Melt spinning is distinguished from other spinning, such as wet or dry spinning from solution, and in such an alternative method, a solvent is present in the melt, by volatilizing or stripping it from the extrudate. Eliminated.
The spinning temperature for the melt can range from about 105 ° C to about 300 ° C, and in some embodiments can be from about 130 ° C to about 230 ° C, or from about 150 ° C to about 210 ° C. Processing temperature depends on the chemical nature, molecular weight, and concentration of each component.
In general, higher fiber spinning speeds are desired for the present invention. A fiber spinning speed of about 10 meters / minute or more can be used. In some embodiments of the invention, the fiber spinning speed is from about 100 to about 7,000 meters / minute, or from about 300 to about 3,000 meters / minute, or from about 500 to about 2,000 meters / minute. is there.

  The fibers are made by a fiber spinning process characterized by a high drawdown rate. The drawdown rate is defined as the ratio of the maximum diameter of the fiber (which typically occurs immediately after exiting the spinneret capillaries in a conventional spinning process) to the final diameter of the shaped fiber. The drawdown rate of the fiber, either by staple, spunbond or meltblown processes, is typically 1.5 or higher and can be about 5 or higher, about 10 or higher, or about 12 or higher.

  Continuous fibers can be produced, for example, by a spunbond method or a meltblown method. Alternatively, discontinuous fibers (short fibers) can be produced according to conventional short fiber processes well known in the art. As will be appreciated by those skilled in the art, various fiber manufacturing methods can be combined into a combination technique. For example, hollow fibers can be manufactured as described in US Pat. No. 6,368,990. Methods such as those described above for fiber spinning are well known and understood in the art.

The spun fibers can be collected and then shaped using a conventional godet winding system or by an air tension dampening device. When using a godet system, the fibers can be further oriented by stretching after extrusion at a temperature of about 50 ° C to about 200 ° C. The drawn fibers may then be crimped and / or cut to form discontinuous fibers (short fibers) used in carding, airlaid, or fluidlaid processes.
In the fiber spinning process, especially when the temperature is higher than 105 ° C., the residual moisture content is typically 1% or less, or 0.5% or less, or 0.15% or less by weight of the fiber. It is desirable to be present in various components.

Suitable multicomponent melt spinning equipment is commercially available, for example, from Hills Inc. in Melbourne, Florida USA and is described in US Pat. No. 5,162,074 (Hills). ing.
The spinneret capillary diameter can be varied depending on the desired fiber size and design, spinning conditions and polymer properties. Suitable capillary dimensions include, but are not limited to, a length to diameter ratio of 4 (diameter 0.350 mm).
As will be appreciated by those skilled in the art, fiber spinning and component blending can optionally be performed in-line, with compounding, drying and spinning being a continuous process.

  The residence time of each component in the spinning line can have special significance when a high melting temperature thermoplastic polymer is selected as it is spun with unstructured starch. The spinning equipment can be designed to minimize the residence of unstructured starch components to high processing temperatures by minimizing the unstructured time and volume that is retained in the spinneret. it can. For example, the polymer supply line for the spinneret can be sealed and separated until it is introduced into the multi-component pack. Further, those skilled in the field of multicomponent fiber spinning will understand that at least two components can be introduced and processed in separate extruders at different temperatures and then introduced into the spinneret. .

  For example, a preferred method for spinning a bicomponent sea-island shaped fiber having one unstructured starch sea and a plurality of polypropylene islands is as follows. The extruder profile of the unstructured starch component is 80 ° C., 150 ° C. and 150 ° C. for the first three zones of the extruder with three heater zones with a starch composition similar to Example 1. It may be ° C. The transport line and melt pump heater temperature is also 150 ° C. for the starch composition. The extruder temperature profile of the polypropylene component is 180 ° C., 230 ° C. and 230 ° C. in the first three zones of the extruder with three heater zones. The transport line and melt pump are heated to 230 ° C. In this case, the temperature of the spinneret can range from 180 ° C to 230 ° C.

(5) Articles The fibers of the present invention can also be used for any purpose for which fibers are conventionally used. This includes, but is not limited to, blending into a nonwoven substrate. The fibers herein can also be converted to non-woven fabrics by any suitable method known in the art. Continuous fibers can be formed into a web using industry standard spunbond technology, while short fibers can be formed into a web using industry standard carding, airlaid, or wet placement techniques. . Exemplary bonding methods include rolling (pressure and heat), aeration heating, mechanical entanglement, hydrodynamic entanglement, needle punching, and chemical and / or resin bonding. Rolling, thru-air heat, and chemical bonding are the preferred bonding methods for starch and polymer multicomponent fibers. Thermally bondable fibers are necessary for pressurized heat and vented heat bonding methods.

  The fibers of the present invention can also be combined or combined with other synthetic or natural fibers to produce nonwoven articles. Synthetic or natural fibers may be blended together in the molding process or may be used in separate layers. Suitable synthetic fibers include fibers made from polypropylene, polyethylene, polyester, polyacrylate, and copolymers and mixtures thereof. Natural fibers include cellulose fibers and their derivatives. Suitable cellulosic fibers include cellulosic fibers derived from any tree or plant, including hardwood fibers, coniferous fibers, hemp, and cotton. Also included are fibers made from processed natural cellulosic resources such as rayon.

  The fibers of the present invention can be used in the manufacture of nonwoven fabrics, among other suitable articles. Nonwoven articles may contain, for example, 15% or more of a plurality of fibers that are continuous or discontinuous and physically and / or chemically attached to each other. The nonwoven may be in the form of a protective layer, a barrier layer, a liquid and / or gas impermeable layer, or an absorbent core or web. Nonwovens are additional nonwovens to produce layered products (eg, baby diapers or feminine sanitary pads) that are used either by themselves or as a component of composites of other materials. Or it may be combined with a film. Specific embodiments envisioned herein include disposable nonwoven articles. It can be seen that the resulting product is an example of use in many different applications. Suitable articles of the present invention include disposable nonwovens for hygiene, cleaning, surface treatment and medical applications. Hygiene applications include wipes; diapers (especially as a topsheet or backsheet, or as a protective layer covering the elastic material of other components of the diaper); and women's pads or products (especially topsheets or backsheets) And other items.

The following examples further illustrate the present invention. The starch used in the following examples is StarDri 1, Stardri 100, Ethylex 2015 or Ethilex 2035, all of which are from Staley Chemical Co. The latter Starray material is substituted starch. Polypropylene (PP) is Basell Profax PH-835, Basell PDC 1298 or Exxon / Mobil Achieve 3854. The polyethylene (PE) is Dow Chemical Aspun 6811A, Dow Chemical Aspan 6830A or Dow Chemical Aspan 6842A. Glycerin is Kosher Grade BU OPTIM ^* glycerin 99.7% from Dow Chemical Company. Sorbitol is Crystalline NF / FCC 177440-2S from Archer-Daniels-Midland Co. (ADM). Polyethylene acrylic acid is PRIMACOR 5980-I from Dow Chemical Co. Other polymers having similar chemical compositions differing in molecular weight, molecular weight distribution, and / or comonomer or defect level can also be used. The processing conditions used in Comparative Example 1 and Examples 1 to 12 are a total mass discharge amount of 0.8 ghm. A practical range of mass discharge is from about 0.1 ghm to about 8 ghm.

(Comparative Example 1)
A solid polypropylene (PP) monocomponent fiber consisting of Basell Profax PH-835 was prepared at a discharge rate of 0.8 grams per hole per minute (ghm) and melt extruded at 190 ° C. When the fiber diameter was 18 μm when melt-spun into a fiber by a continuous filament method at the molding temperature, the elongation to break of this fiber was 181%.

Example 1
Solid sheath / core bicomponent fiber (as illustrated in FIG. 1A): Component A is polypropylene (Basell Profax PH-835). Component B is a TPS component, 60 parts StarDri 1, 40 parts sorbital, 15 parts Primacore 5980-I and 1 part magnesium stearate (all starch formulations) Included in the product). The melt processing temperature is 190 ° C. Fibers are produced with component A: component B ratios of 10:90, 20:80, 30:70 and 50:50.

(Example 2)
Solid sheath / core bicomponent fiber (as illustrated in FIG. 1A): Component A is polyethylene. Component B is a TPS component and is formulated using 60 parts StarDri 1 and 40 parts sorbital. The melt processing temperature ranges from 150 ° C to 190 ° C. The ratio of component A: component B is 95: 5 to 20:80.

(Example 3)
Solid sheath / core bicomponent fiber (as illustrated in FIG. 1A): Component A is PLA. Component B is a TPS component and is formulated using 60 parts StarDri 1 and 40 parts sorbital. The melt processing temperature ranges from 180 ° C to 210 ° C. The ratio of component A: component B is 95: 5 to 20:80.

Example 4
Solid sheath / core bicomponent fiber (as illustrated in FIG. 1A): Component A is Eastman 14285. Component B is a TPS component and is formulated using 60 parts StarDri 1 and 40 parts sorbital. The melt processing temperature ranges from 210 ° C to 250 ° C. The ratio of component A: component B is 95: 5 to 20:80.

(Example 5)
Solid sheath / core bicomponent fiber (as illustrated in FIG. 1A): Component A is Bionolle 1020. Component B is a TPS component and is formulated using 60 parts StarDri 1 and 40 parts sorbital. The melt processing temperature ranges from 160 ° C to 200 ° C. The ratio of component A: component B is 95: 5 to 20:80.

(Example 6)
Solid sheath / core bicomponent fiber (as illustrated in FIG. 1A): Component A is EASTAR BIO. Component B is a TPS component and is formulated using 60 parts StarDri 1 and 40 parts sorbital. The melt processing temperature ranges from 150 ° C to 180 ° C. The ratio of component A: component B is 95: 5 to 20:80.

(Example 7)
Sea-island bicomponent fiber (as illustrated in FIG. 2B): Component A is polypropylene. Component B is a TPS component and is formulated using 60 parts StarDri 1 and 40 parts sorbital. The melt processing temperature ranges from 180 ° C to 210 ° C. The ratio of component A: component B is 95: 5 to 30:70.

(Example 8)
Sea-island bicomponent fiber (as illustrated in FIG. 2B): Component A is polyethylene. Component B is a TPS component and is formulated using 60 parts StarDri 1 and 40 parts sorbital. The melt processing temperature ranges from 150 ° C to 190 ° C. The ratio of component A: component B is 95: 5 to 30:70.

Example 9
Sea-island bicomponent fiber (as illustrated in FIG. 2B): Component A is PLA. Component B is a TPS component and is formulated using 60 parts StarDri 1 and 40 parts sorbital. The melt processing temperature ranges from 180 ° C to 210 ° C. The ratio of component A: component B is 95: 5 to 30:70.

(Example 10)
Sea-island bicomponent fiber (as illustrated in FIG. 2B): Component A is Eastman 14285. Component B is a TPS component and is formulated using 60 parts StarDri 1 and 40 parts sorbital. The melt processing temperature ranges from 210 ° C to 250 ° C. The ratio of component A: component B is 95: 5 to 30:70.

(Example 11)
Sea-island bicomponent fiber (as illustrated in FIG. 2B): Component A is Bionolle 1020. Component B is a TPS component and is formulated using 60 parts StarDri 1 and 40 parts sorbital. The melt processing temperature ranges from 160 ° C to 200 ° C. The ratio of component A: component B is 95: 5 to 30:70.

(Example 12)
Sea-island bicomponent fiber (as illustrated in FIG. 2B): Component A is Easter Bio. Component B is a TPS component and is formulated using 60 parts StarDri 1 and 40 parts sorbital. The melt processing temperature ranges from 150 ° C to 180 ° C. The ratio of component A: component B is 95: 5 to 30:70.

  Although specific embodiments are described above, devices including, but not limited to, different combinations of materials, ratios, and counter-rotating biaxial or high shear uniaxial with vents may also be used.

  While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. All such variations and modifications within the scope of the present invention are intended to be covered by the appended claims.

Sectional drawing of the bicomponent fiber which has a sheath / core shape. Illustrated concentric sheath-core shape. Sectional drawing of the bicomponent fiber which has a sheath / core shape. 1 illustrates a sheath-core configuration with a solid core and a shaped continuous sheath. Sectional drawing of the bicomponent fiber which has a sheath / core shape. Figure 2 illustrates a sheath-core configuration with a hollow core and a continuous sheath. Sectional drawing of the bicomponent fiber which has a sheath / core shape. 1 illustrates a sheath-core configuration with a hollow core and a shaped continuous sheath. Sectional drawing of the bicomponent fiber which has a sheath / core shape. Illustrated off-center sheath-core configuration. Sectional drawing of the bicomponent fiber which has a sea island shape. Solid sea island shape. Sectional drawing of the bicomponent fiber which has a sea island shape. Alternative solid sea island shape. Sectional drawing of the bicomponent fiber which has a sea island shape. Hollow sea island shape.

Claims (11)

A. A thermoplastic polymer component comprising a non-starch thermoplastic polymer;
B. A thermoplastic starch component;
A multi-component fiber comprising
The multicomponent fiber is obtained from a molten composition of each constituent, and the total water content of each molten composition is 1% or less,
The thermoplastic starch component comprises unstructured starch and a plasticizer;
The plasticizer is selected from the group consisting of saccharides, sugar alcohols, polyols, and mixtures thereof, and the polyols include glycerol, ethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, hexanetriol and the like. Is selected from the group consisting of mixtures,
The multicomponent fiber is a large multicomponent fiber having an elongation ratio up to break exceeding 1.0. The multicomponent fiber according to claim 1, wherein the multicomponent fiber has a diameter of 200 μm or less.   The multi-component fiber of claim 1 or 2, wherein the thermoplastic starch component has an outer surface and the thermoplastic polymer component surrounds the thermoplastic starch component.   The multicomponent fiber according to any one of claims 1 to 3, wherein the fiber has a sheath-core shape, the thermoplastic polymer component is the sheath, and the thermoplastic starch component is a core. . The thermoplastic polymer component comprises a non-starch thermoplastic polymer of 5 wt% or more of the components, the thermoplastic starch component comprises 5 1 wt% of thermoplastic starch of the component, wherein Item 5. The multicomponent fiber according to any one of Items 1 to 4 . The multicomponent fiber according to any one of claims 1 to 5 , which is produced at a fiber spinning speed of 2,000 m or less per minute . The elongation ratio to break is 1 . 5 or more in either, walk two. It is 0 or more, The multicomponent fiber as described in any one of Claims 1-6 . Nonwoven web comprising multicomponent fibers as claimed in any one of claims 1-7. 9. The nonwoven web of claim 8 , further comprising at least one type of single component fiber mixed with the multicomponent fiber and having an interfiber bond. The nonwoven web of claim 9 , wherein the interfiber bond comprises a thermoplastic polymer bond between the fibers. A disposable article comprising the nonwoven web of claim 9 or 10 .

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