JP2005539154A - Polyolefin fibers and their use in making bulky and highly resilient nonwovens - Google Patents

Abstract

Non-woven materials from polyolefin-based fibres which have bulk and resilience comparable to polyester fibres are described herein, thus expanding the utility of polyolefin fibres and nonwovens to a plethora of industrial applications which previously excluded products based on polyolefin fibres due to their hitherto inadequate bulk or resilience. Control of polyolefin fibre characteristics such as the fibre/fibre friction, fibre crystallinity, draw ratio, or selection of the spin finish so as to comprise essentially of an aqueous emulsion of polysiloxanes render them suitable for preparing bulky and resilient nonwovens.

Description

FIELD OF THE INVENTION By controlling the characteristics of polyolefin fibers, a bulky polyolefin nonwoven fabric can be obtained. Among the physical characteristics of fibers that are suitable for making bulky and resilient nonwovens, fiber / fiber friction and crystallinity are disclosed. These new fibers allow polyolefin nonwovens to be used in technologies previously limited or occupied by polyolefins and nylons until now due to inappropriate bulkiness or resilience. .

Background of the Invention Conventional polypropylene staple fibers do not give nonwovens high resilience and bulkiness, at least to the extent of polyester fibers.

  Fibers from conventional polyolefins such as polypropylene and polyethylene are not sufficient to make the nonwovens bulky and resilient enough to be suitable polyester nonwoven substitutes.

The bulkiness of conventional polyolefin fibers is about 20-25 cm ³ / g and the resilience is about 85%. We are part of a group that commercialized polyolefin fiber products with improved bulkiness but significantly reduced resilience. The bulkiness of Fibervisions HY-Comfort® fibers has been improved to 45 cm ³ / g, but the resilience is less than 50%. However, it should be noted that nonwoven fabrics with bulkiness comparable to polyester are not produced from HY-Comfort® fibers. It would be of great commercial interest to increase the bulkiness of nonwovens made from polyolefin fibers.

The polyester nonwoven has a bulkiness of about 100 cm ³ / g and a resilience of about 75%, depending on the oven bonding method and the type of finish.

  US 6,388,013 for polyolefin fibers described improved balance of properties including increased tenacity, modulus, and elongation. This is by mixing 1 to 10 weight percent aromatic hydrocarbon resin with a polypropylene fiber-forming composition (which is based on a propylene homopolymer or a copolymer or blend of these propylene polymer resins and non-propylene containing resins). Achieved. The present invention provides a polyolefin fiber having improved tenacity by adding a small amount of an aromatic hydrocarbon resin to the polyolefin. Polypropylene fibers extruded and drawn from this blend exhibit higher tenacity and can therefore be processed at higher speeds and with fine denier.

  US 5,770,532 is made of spun filaments of artificial short fibers (including polyester fibers, polyethylene fibers or polypropylene fibers) or artificial fiber forming materials (including polyester, polyethylene or polypropylene fibers) and binding fibers (composite fibers or Explains how to strengthen a fiber fleece that can be mixed with natural fibers and is produced with a thickness as large as 10mm or less without the use of special melt fibers) and without the use of binders . This method is characterized in that the fleece is strengthened by a single water needling at a high water pressure of only 60 bar.

  US 5,589,256 relates to a method for producing easily bulked fibers with fine particles attached. This bulky fiber has hydrogen bonding or coordinate covalent functionality and a binder is added to the fiber to bind the particles to the fiber. The binder has functional groups that form hydrogen bonds or coordinate covalent bonds with the particles and functional groups that form hydrogen bonds with the fibers. A significant portion of the particles attached to the fibers are attached in particulate form by hydrogen bonding or coordinate covalent bonding with the binder, and then the binder is attached to the fibers by hydrogen bonding. This fiber product is bound to the fibers by individual fibers (having a density of 0.1 to 0.7 g / cc and hydrogen bonding functional groups) that are densified by applying pressure; and a binder that goes between the particles and the fibers Particles. The particle has a hydrogen bond or a coordinate covalent bond functional group, and the binder can form a coordinate covalent bond between the functional group or the binder and the particle that can form a hydrogen bond between the binder and the particle. It has a functional group and a functional group capable of forming a hydrogen bond between the binder and the fiber. The binder is (a) a polymer binder having repeating units, where each repeating unit forms a hydrogen bond or coordinate covalent bond with the particle, or a hydrogen bond with the fiber. And (b) may be selected from the group consisting of non-polymeric organic binders, the product contains 0.05-80% bound particles, the bound particles being mainly hydrogen bonded Or it is bonded to the fiber by a coordinate covalent bond.

  US5,478,646 extrudes the main raw material from polypropylene with a syndiotactic quintuplet ratio of 0.7 or more, and selectively stretched the resulting extruded material, with the strength Describes polypropylene fibers having a high average size of 10,000 to 0.1 denier.

  US 5,204,174 relates to a nonwoven web made of highly drawn unoriented thermoplastic fibers formed from a blend of propylene polymer and butylene polymer. The blend is 90% to 50% polypropylene and 10% to 50% polybutylene by weight. The resulting nonwoven web has high toughness, tear resistance, drape, and conformability.

  US 4,563,392 relates to coated polyolefin fibers. The fiber is (a) a monofilament fiber or multifilament fiber made of polyethylene or polypropylene having a weight average molecular weight of at least about 500,000 (in the case of polyethylene, the tenacity is at least about 15 g / denier and the tensile modulus is at least about 300 g / denier). In the case of polypropylene, tenacity is at least 8 g / denier and tensile modulus is at least about 160 g / denier); and (b) coatings on monofilaments and multifilament filaments, including polymers with ethylene or propylene crystals Including at least a portion of the coating, wherein the coating is present in an amount of about 0.1% to about 200% by weight of the fiber.

  None of the prior art is associated with an increase in the bulkiness of the polyolefin nonwoven and does not increase the bulkiness of the polyolefin nonwoven to an appreciable amount. The present inventors have found a solution to the problem that the bulkiness of polyolefin nonwoven fabric is insufficient.

SUMMARY OF THE INVENTION The present invention is based on novel polyolefin fibers suitable for improving the bulkiness of nonwoven fabrics made from polyolefin fibers.

The first aspect of the invention relates to a polymer fiber based on a novel polyolefin. This fiber is suitable for producing a bulky nonwoven fabric. The fibers of the present invention are based on a polyolefin polymer and have at least one characteristic selected from the group consisting of:
i) 600 g or less of fiber / fiber friction;
ii) a spin finish consisting essentially of a polysiloxane emulsion;
iii) a draw ratio of at least 1: 1.5; and
iv) Fiber crystallinity of at least 50%.

  A further aspect of the invention relates to a method of making a polyolefin-based fiber. This process is characterized by the use of a nucleated polymer, generally a draw ratio of at least 1: 1.5 at a final fineness of 2-10 dtex, and a spin finish consisting essentially of an improved polysiloxane emulsion.

The present invention reveals that the high bulkiness of the fibers does not necessarily correspond to the high bulkiness of the nonwoven fabric. The present invention can be used to identify fiber characteristics and is used to create important fiber properties (spin finish selection; and / or fiber creation) corresponding to the high bulkiness of nonwovens. Including selection of polymer grade and / or selection of draw ratio in fiber creation). An important objective is a nonwoven material made from short fibers based on polyolefins, as defined herein. A further object of the present invention relates to a nonwoven material based on short fibers based on polyolefin, the nonwoven material having a bulkiness of at least 30 cm ³ / g and a resilience of at least 50%.

An interesting aspect of the present invention relates to a method for producing a bulky nonwoven from a polyolefin-based fiber that is comparable in bulkiness and resilience to a polyester material. Using new fibers, suitable production methods or bonding methods, we have created nonwovens with bulkiness up to approximately 80 cm ³ / g and resilience of approximately 80%. This is comparable to conventional nonwovens made from conventional polyolefin fibers with an estimated bulkiness of 22 cm ³ / g and resilience of about 86%. An important object of the present invention relates to a method of making a nonwoven material comprising the use of the fibers of the invention or the use of fibers made according to the method of making the fibers of the invention.

  A further aspect of the present invention relates to a hygiene product comprising the nonwoven material of the present invention and a process for making a sanitary product comprising the use of the non-woven material of the present invention.

DESCRIPTION OF THE INVENTION The terms “bulk” and “bulkiness” as used herein are intended to refer to a large volume (large volume per weight), cm ³ / g Measured in

  The term “fiber / fiber friction” as used herein is intended to refer to the force required to separate the fibers from each other.

  As used herein, the term “fiber crystallinity” is intended to refer to the presence of three-dimensional order at the molecular level in a polymer. Fiber crystallinity is measured by differential scanning calorimetry (DSC) and X-ray diffraction (XRD).

  As used herein, the term `` resilience '' is the ability to recover to its original shape and size after the load or strain that caused the deformation is removed (e.g., the ability to return to its original shape or state after being compressed). ) To say.

  Researchers of the present invention have made nonwoven materials from polyolefin-based fibers that have bulkiness and resilience comparable to polyester fibers. Therefore, the usefulness of polyolefin fibers and non-woven fabrics extends to a vast number of industrial fields that were previously locked out to products based on polyolefin fibers due to inappropriate bulkiness or resilience.

  The inventors have surprisingly discovered that the high bulkiness of the fibers does not necessarily correspond to the high bulkiness of the nonwoven. The present inventors have discovered that when the fiber / fiber friction is small, the bulkiness of the nonwoven fabric is higher than that of the fiber with high fiber / fiber friction. Without being bound by any particular theory, this is because, at least in part, it is very easy for the low friction fibers to move freely during the carding and thermobonding processes used. . These low-friction fibers have low fiber bulkiness due to the ability to slip well.

  The bulkiness of the nonwoven material is determined, at least in part, by the characteristics of the polyolefin fibers. The researchers of the present invention have discovered that the characteristics of the fiber have a significant effect on the bulkiness of the nonwoven fabric, and have created fibers suitable for creating nonwoven fabrics with desirable bulkiness.

The first object of the present invention relates to a fiber suitable for producing a bulky nonwoven fabric. The researchers of the present invention have found that the fiber characteristics necessary to obtain a bulky nonwoven (i.e., fiber / fiber friction (this is a spin finish consisting at least in part of a polysiloxane emulsion). Can be controlled by selection); suitable draw ratio; and suitable fiber crystallinity). The researchers of the present invention have discovered that by properly setting any one of these parameters, fibers can be made that enable bulky nonwovens. Accordingly, a fiber based on a polyolefin polymer has at least one characteristic selected from the group consisting of:
i) 600 g or less of fiber / fiber friction;
ii) a spin finish consisting essentially of a polysiloxane emulsion;
iii) a draw ratio of generally at least 1: 1.5 with a final fineness of 2 to 10 dtex; and
iv) Fiber crystallinity of at least 50%.

  As described above, fiber / fiber friction is an important parameter that should be appropriately set in order to obtain a bulky polyolefin nonwoven fabric. In a preferred embodiment, the fiber / fiber friction is 500 g or less (eg, 400 g or less). The fiber / fiber friction is generally 200-1000 g (eg 200-800 g), preferably 200-600 g, more preferably 200-500 g, most preferably 200-400 g.

  Researchers of the present invention have discovered that the type of spin finish significantly affects fiber bulkiness. It has been discovered that the type of spin finish controls fiber / fiber friction to some extent and fiber bulkiness to some extent. Accordingly, it has been discovered that spin finishes that reduce fiber / fiber friction of the fibers exhibit low fiber bulkiness. Without being bound by any particular theory, it is suggested that this effect is caused by the well-sliding properties of the fiber. In this case, the fibers cannot be separated from each other, and therefore the fiber bulkiness is relatively low.

  As mentioned above, fiber / fiber friction is determined, at least in part, by the choice of spin finish. In the context of the present invention, a “spin finish” is a liquid composition (primary finish) that can be added to the fiber in the spinning process and a liquid composition (secondary finish) that can be added to the fiber in the subsequent drawing process. ) To say. Spin finishes facilitate the spinning process, in particular by smoothing the fibers and preventing static electricity. Antistatic agents may be used to ensure that the fibers are not charged during the spinning and drawing processes; anionic, cationic, and nonionic antistatic agents are It may be used in a spin finish as described herein. The total amount of antistatic agent added to the fiber is preferably as low as possible while achieving the desired antistatic effect (e.g., 0,01-0,5 wt% based on the weight of the fiber , Preferably 0,02-0,35% by weight, even more preferably 0,05-0,2% by weight). The amount of antistatic agent is also preferably minimized with secondary spin finishes. Preferably, the amount of spin finish added during the spinning process is greater than the amount added during the drawing process. When the secondary spin finish includes a cationic antistatic agent, the cationic antistatic agent is preferably in an amount of at most 20%, based on the total active ingredient content of the secondary spin finish. More preferably it is present in an amount of at most 10%.

  The spin finish may further include an amount of a cohesion conferring agent to ensure that the filaments are bundled together. When this is used, processing can be performed without tangling the fibers. Examples of cohesive agents used for this purpose are neutral vegetable oils, long chain alcohols, ethers and esters, sarcosine, and nonionic surfactants specified herein.

  The spin finish may further include a lubricant that adjusts both fiber / fiber friction and fiber / metal friction during the manufacturing process so that the filaments do not fray or become crumbly during processing. . In particular, it is necessary to adjust the fiber / metal friction during the spinning stage, the fiber / metal friction against the draw roller, and the fiber / fiber friction and fiber / metal friction in the crimper.

  Spin finishes generally further include an emulsifier or surfactant that keeps the water and the more or less lipophilic components in the aqueous solution. Water is a preferred solvent in the present invention. Other solvents should be avoided whenever possible to eliminate the possibility of threatening the environment.

  The fibers of the present invention generally comprise a spin finish consisting essentially of a polysiloxane emulsion. The fibers of the present invention more generally comprise a spin finish consisting essentially of an aqueous polysiloxane emulsion. Aqueous polysiloxane emulsions suitable for use in spin finishes generally have at least 25% active ingredient content (eg, at least 30% active ingredient content), preferably at least 35% active ingredient content. (For example, about 40%). The spin finish is suitably added at a concentration of 2-15% (eg, 5-10%).

  In a general embodiment, the fiber spin finish concentration is about 0.2-1% wt / wt (eg, 0.25-0.9%), preferably 0.3-0.85%, more preferably 0.35-0.85%, based on the fiber. is there.

  Although not bound by any particular spin finish, a particularly suitable spin finish according to the present invention is Synthesin 7490 FILL®. This spin finish comprises an elastomer based on silicone, in particular an improved polysiloxane emulsion. A large number of finishes, including modified polysiloxane emulsions, are suitable, as is Synthecin 7490 Fill®. The spin finish is suitably dissolved in water at ambient temperature and can be added by dipping, padding, or spraying. The spin finish crosslinks when dried at a temperature of about 100 ° C. (eg, 80 ° C.).

  The spin finish may be added in two or more stages. The total concentration of suitable active ingredients (i.e., antistatic agents, one or more lubricants, emulsifiers, and cohesive agents) contained in the spin finish is generally the secondary spin finish. Primary spin finishes (generally 0,7-2,5% active ingredient content) are lower than (generally 4-12% active ingredient content). Therefore, usually the viscosity of the primary spin finish is lower. Thus, it may be advantageous to use any highly viscous component in the lowest viscosity dispersion (ie, the primary spin finish).

  A further important feature of the fiber that gives the nonwoven fabric high bulkiness is fiber crystallinity. As mentioned above, the fiber crystallinity is suitably at least 50%. In embodiments where the fiber crystallinity is manipulated to give the nonwoven fabric a high bulkiness, the fiber crystallinity is preferably at least 55% (eg, at least 60%) as measured by DSC or XRD. .

  In a further aspect of the invention, bulkiness may be controlled by selecting the polymer grade (or matrix polymer) used in making the fiber. Polymers include polypropylene homopolymers and random copolymers with ethylene, 1-butene, 4-methyl-1-pentene, etc., and various densities of linear polyethylene (e.g., high density polyethylene, low density polyethylene, and linear low density). Polyethylene), as well as blends thereof. The polymer material may be mixed with other non-polyolefin polymers, such as polyamide or polyester, if the polyolefin still accounts for the largest part of the composition.

  In yet another aspect of the present invention, fiber bulkiness may be controlled by selecting a nucleating agent (eg, a nucleating agent used in polyolefin raw materials). Nucleating agents are commonly used in industrial practice, often in combination with crystalline thermoplastic polymers to impart improved characteristics (eg, improved mechanical characteristics). Known common nucleating agents include metal salts of aliphatic or aromatic carboxylic acids, branched polymers including dendritic branches, and chalk, gypsum, clay, kaolin, mica, talc, and silicates It is an inorganic material. More recently developed nucleating agents such as compounds based on D-sorbitol and 1,3-2,4-bis- (3,4-dimethylbenzylidene) -D-sorbitol dissolve in the polymer melt.

  The action of the nucleating agent is the action of initiating the crystallization process in the parent polymer. The nucleating agent has a very large surface area and is the preferred nucleation site in the parent polymer. The nucleation process is a thermodynamic process that is substantially driven by reducing the specific surface area of the nucleating agent (eg, by reducing the specific surface area of chalk or talc particles in the parent polymer).

  Nucleating agents also facilitate the polymer crystallization process. Thus, the nucleating agent can make the parent polymer more or less crystalline (e.g., making it substantially amorphous or making it more crystalline than making it crystalline). . In the context of the present invention, “crystalline” means crystalline regions within an amorphous polymer matrix (e.g., polymer chains or portions of polymer chains are aligned in a regular pattern substantially parallel to each other. The purpose is to say. In contrast, "non-crystalline" is intended to refer to a region in the polymer matrix where the polymer chains are not substantially aligned or ordered.

  In preferred embodiments, the polyolefin comprises isotactic or syndiotactic polypropylene homopolymer, homopolymers and copolymers of monoolefins such as ethylene, propylene, α-olefin, 4-methyl-1-pentene and blends thereof, linear polyethylene, Selected from the group consisting of high density polyethylene, low density polyethylene, and linear low density polyethylene and blends thereof. More preferably, the polyolefin is selected from the group consisting of homopolymer polypropylene and homopolymer polyethylene. Most preferably, the polyolefin is a homopolymer polypropylene.

  The degree of crystallinity is at least partially controlled by the nucleating agent. This in turn affects the mechanical properties of the polymer. For example, polymer chains or portions of polymer chains that are closely packed in the crystalline region have more polymer chains per unit area that can withstand a certain stress. Also, because the polymer chains are in close and regular contact over a relatively long distance in the crystallite, the secondary force that brings the polymer chains together is cumulatively greater than that in the amorphous region. Thus, having substantially more crystalline polymer increases the strength and stiffness of the polymer.

  In a general embodiment of the invention, the polyolefin polymer is a nucleated polymer. Suitably, the nucleating agent is selected from the group consisting of compounds based on talc, chalk, gypsum, clay, kaolin, silicate, aromatic carboxylate, phosphate ester salt, and sorbitol. Most suitably, the nucleating agent is talc. In embodiments where the polyolefin polymer is a nucleated polymer nucleated with talc, nucleation is generally performed to a talc concentration of 5000-10000 ppm.

  While not being bound to any particular polymer grade, if the preferred raw material polypropylene polymer grade is used in the present invention, it may be Adstif HA840R. Adstiff HA840R is a high performance homopolymer characterized by extremely high stiffness and gloss. This polymer grade is nucleated with 8500 ppm of talc to increase crystallinity. In a further aspect of the present invention, fibers produced from Adstiff HA840R homopolymer raw material give the fibers a higher flexural modulus compared to fibers produced from standard polypropylene materials. Without being bound by any particular theory, the high flexural modulus obtained with Adstiff HA840R suggests that this homopolymer is nucleated with talc. Accordingly, the nucleated homopolymer has high crystallinity and therefore high rigidity. For example, Adstiff HA840R used in the present invention has a flexural modulus of about 2250 MPa. Compared to this value, the flexural modulus of conventional raw material polypropylene homopolymer grades such as PPH7059 is about 1450 MPa.

  Fiber bulkiness is controlled, at least in part, by selecting the draw ratio in fiber creation. In the context of the present invention, “draw-ratio” or “stretch ratio” is intended to refer to the ratio of the speed of the last roller set to the speed of the first roller set.

  The fibers of the present invention can be obtained with suitable fineness (generally, for example, about 2-20 dtex (e.g., 2-10 dtex), generally 3-9 dtex, most commonly 5-8 dtex), In general, for polypropylene fibers, about 1: 1.5 to about 1: 8 (e.g., about 1: 1.5 to 1: 6, e.g., about 1: 1.5 to 1: 4, about 1: 2 to 1: 8, Stretched using a draw ratio of about 1: 2 to 1: 6, or about 1: 2 to 1: 4), for polyethylene fibers and polypropylene / polyethylene bicomponent fibers, a draw ratio of 1: 2 to 1: 4.5 . The draw ratio affects the crystallinity. That is, at higher stretch ratios, the polymer chains become increasingly aligned and therefore become more crystalline. Large stretch ratios also tend to orient the crystalline regions substantially along the length of the fibers, making these fibers substantially anisotropic. As the crystallinity of the fiber increases, the rigidity of the fiber increases (for example, the greater the degree of crystallinity and the more oriented the crystals, the higher the fiber rigidity).

  Preferably, the draw ratio of polypropylene fibers suitable for obtaining a nonwoven with high bulkiness is generally in the range of 1: 2 to 1: 4. Generally, the draw ratio of polypropylene fibers according to the present invention is about 1: 1.5 to 1: 6 (eg, about 1: 2 to 1: 5), preferably 1: 2.5 to 1: 4.

  According to the present invention, the high crystallinity of the individual fibers results in a bulky nonwoven material (e.g., highly crystalline and thus stiff fibers make a bulky appearance of nonwoven material. Bring). Without being bound by any particular theory, when an external force acts on the nonwoven material, it suggests that the highly crystalline fiber will have some ability to flex and return to its original state due to the inherent stiffness of the fiber. Is done. This feature is quantified at least in part by resilience. Resilience is intended to refer to the ability to recover to its original shape and size after the load or strain that caused the deformation is removed. Suitable fiber resilience for making bulky nonwovens is generally at least about 30% (eg, at least about 40%, eg, about 42%).

As described above, the bulkiness of fibers suitable for the production of a bulky nonwoven fabric does not necessarily correspond to the bulkiness of the nonwoven fabric. However, generally, fibers of the present invention suitable for the creation of a bulky nonwoven fabric is at least about 20 cm ³ / g, preferably at least about 30 cm ³ / g and 35 cm ³ / g (e.g., at least about 40 cm ³ / g) bulky.

  The flexural modulus of polyolefins used to make fibers suitable for making bulky nonwoven fabrics according to the present invention is generally at least 1200 MPa (eg, at least 1500 MPa).

As described above, a bulky nonwoven fabric by appropriately controlling any one of the fiber characteristics selected from the group including: fiber / fiber friction; spin finish; draw ratio; and fiber crystallinity A fiber suitable for the production of is obtained. Preferably, the fibers based on polyolefin polymers according to the invention have at least two of the characteristics selected from the group consisting of:
i) 600 g or less of fiber / fiber friction;
ii) a spin finish consisting essentially of a polysiloxane emulsion;
iii) a draw ratio of at least 1: 1.5;
iv) at least 50% fiber crystallinity;
v) the polyolefin polymer is a nucleated polymer;
vi) the flexural modulus of the polyolefin is at least 1500 MPa;
vii) ST dtex values from 2 to 20 dtex; and
viii) Fiber bulkiness of 20 cm ³ / g, preferably at least about 30 cm ³ / g.

Suitably, the fibers of the invention have at least three of the following characteristics (e.g. at least four of the following characteristics, e.g. at least five, six, seven, selected from the group consisting of: Or 8):
i) 600 g or less of fiber / fiber friction;
ii) a spin finish consisting essentially of a polysiloxane emulsion;
iii) a draw ratio of at least 1: 1.5;
iv) at least 50% fiber crystallinity;
v) the polyolefin polymer is a nucleated polymer;
vi) the flexural modulus of the polyolefin is at least 1500 MPa;
vii) ST dtex values from 2 to 20 dtex; and
viii) Fiber bulkiness of 20 cm ³ / g, preferably at least about 30 cm ³ / g.

More preferably, the fibers of the present invention have at least two of the characteristics selected from the group consisting of:
i) 600 g or less of fiber / fiber friction;
ii) a spin finish consisting essentially of a polysiloxane emulsion;
iii) a draw ratio of at least 1: 1.5;
iv) at least 50% fiber crystallinity;
v) The polyolefin polymer is a nucleated polymer.

Suitably, the fiber of the present invention comprises
i) 600 g or less of fiber / fiber friction;
ii) a spin finish consisting essentially of a polysiloxane emulsion;
iii) a draw ratio of at least 1: 1.5;
iv) at least 50% fiber crystallinity;
v) the polyolefin polymer is a nucleated polymer;
At least two features selected from the group consisting of:
vi) the flexural modulus of the polyolefin is at least 1500 MPa;
vii) ST dtex values from 2 to 20 dtex; and
viii) Fiber bulkiness of 20 cm ³ / g, preferably at least about 30 cm ³ / g;
At least one feature selected from the group consisting of (eg, at least two of the following features).

In a most preferred embodiment, the fiber based on a polyolefin polymer according to the invention is such that the polyolefin polymer is a nucleated polymer;
i) 600 g or less of fiber / fiber friction;
ii) a spin finish consisting essentially of a polysiloxane emulsion;
iii) a draw ratio of at least 1: 1.5; and
iv) have a fiber crystallinity of at least 50%.

  A further object of the present invention relates to a nonwoven material made from short fibers based on polyolefins as defined above.

  The present invention further relates to a method of creating a nonwoven fabric from short fibers. The method includes the steps of (a) forming a fiber web comprising staple fibers from the fibers described herein and (b) bonding the fiber web. In particular, the short fibers exhibit small fiber / fiber friction (eg, 600 g or less, eg 400 g or less, suitably 300 g or less).

Alternatively, the nonwoven material of the present invention is based on short fibers based on polyolefins, where the bulkiness of the nonwoven material is at least 30 cm ³ / g and the resilience is at least 50%. Generally, the resilience of nonwoven materials is at least 55% (eg, at least 60%).

  Generally, the bulkiness of the nonwoven material is at least 35% (eg, at least 40%), preferably at least 45%, more preferably at least 50%, even more preferably at least 55%, most preferably at least 60%. is there.

  A further object of the present invention relates to a method for making fibers based on polyolefins. This method is characterized by the use of a spin finish consisting essentially of a nucleated polymer, a draw ratio of at least 1: 1.5, and a modified polysiloxane emulsion.

  In a preferred embodiment of the invention, the fibers disclosed herein are short fibers based on polyolefins or copolymers thereof. Polyolefins used to produce such fibers include isotactic or syndiotactic polypropylene homopolymers and random copolymers with ethylene, 1-butene, 4-methyl-1-pentene, and lines of various densities. Polyolefins selected from the group consisting of linear polyethylene (eg, high density polyethylene, low density polyethylene, and linear low density polyethylene), and blends thereof. The polymer material may be mixed with other non-polyolefin polymers, such as polyamide or polyester, if the polyolefin still accounts for the largest part of the composition. The polymer is suitably selected from polyethylene and polypropylene.

Melts used to produce polyolefin-containing fibers vary from calcium stearate, antioxidants, process stabilizers, compatibilizers, and pigments (including white pigments such as TiO ₂ and / or other colorants) Conventional fiber additives may also be included.

  The fiber may be a monocomponent fiber or a composite fiber. The composite fiber is, for example, a sheath-core type composite fiber in which the core is located off-center (not in the center) or concentrically (substantially in the center). Bicomponent fibers generally have a core and a sheath, where the core and sheath are respectively polypropylene / polyethylene, high density polyethylene / linear low density polyethylene, polypropylene random copolymer / -polyethylene, or polypropylene / polypropylene random copolymer. Including. Further, the cross-sectional shape of the fiber may be circular, three-lobal, four-lobal, and may have a hollow core in addition to this shape.

  The spinning of the fibers is preferably done using conventional melt spinning (also known as long spinning) where spinning and drawing are performed in two separate stages. Alternatively, other means of producing short fibers (especially “compact spinning”, a one-step procedure) may be used to carry out the present invention.

  For spinning, the polyolefin-containing material is extruded and the polymer melt is passed through a hole in the spinneret. The extrudate is then cooled and consolidated by air flow and simultaneously drawn into filaments. After the filament is consolidated, it is treated with a primary spin finish. This is typically done with a lick roller. Other systems such as spraying the filament bundle or dipping the filament bundle in a spin finish are also suitable.

  The amount of fiber degradation affects the thermobonding properties. Therefore, if the fiber decomposition is too low, sufficient thermobonding characteristics are not imparted to the fiber, and sufficient processability tends to be not obtained in the spinning line. Polymer degradation depends on the amount of stabilizer contained in the polyolefin-containing material, the temperature of the extruder, and the speed and temperature of the quenching air. A means for determining the degree of degradation of the as-spun fiber is a means of measuring the melt flow rate (MFR) of the fiber and comparing this to the MFR of the original polymer material. In a preferred embodiment of the present invention, the MFR of the as-spun fiber is 1.5-7 times that of the raw material, generally 2-5 times that of the raw material. However, it should be noted that this depends to some extent on the MFR of the raw material. Therefore, the preferred ratio of fiber MFR to raw material MFR is often slightly less for raw materials with relatively high MFR (e.g., 3-5 times for raw materials with MFR of 10-15, 15-20 MFR). 2 to 4 times in the case of raw materials).

  The drawing process generally involves a series of hot rollers and a hot air oven. First, the filament passes through a roller set, then through a hot air oven, and then through a second roller set. Generally, the temperature of the hot roller and hot air oven is about 50-140 ° C. (eg, about 70-130 ° C.), and the temperature is selected depending on the type of fiber. In general, the temperature is 115 to 135 ° C for polypropylene fibers, 95 to 105 ° C for polyethylene fibers, and 110 to 120 ° C for polypropylene / polyethylene composite fibers. The speed of the second roller set is faster than the speed of the first set, so the heated filament is drawn accordingly. A second oven and a third roller set can also be used (two-stage stretching) and the speed of the third roller set is faster than the second set. Similarly, additional roller sets and ovens may be used. The draw ratio is the ratio of the last roller set to the first roller set. The fibers of the present invention are generally drawn using a draw ratio of about 1: 1 to about 1:10.

  After stretching, the filament bundle is treated with a secondary spin finish using, for example, a lick roller or spraying or dipping.

  In order to make the fibers suitable for carding, the drawn fibers are usually processed (crimped) (eg by making the fibers corrugated). Effective processing (i.e. a relatively large number of crimps in the fiber) increases the processing speed in the card machine (e.g. at least 80 m / min, generally at least 150 m / min, or more than 200 m / min), Productivity can be increased.

  Crimping is conveniently performed using a so-called stuffer box or, alternatively, the filament can be processed with air. In certain cases (ie in the case of asymmetric bicomponent fibers), heat treatment of such fibers results in three-dimensional self-crimping, so a crimping device may not be necessary.

  The fibers of the present invention are generally processed to a degree of about 5-15 crimps / cm, typically about 7-12 crimps / cm, and the number of crimps is the number of crimped portions of the fiber. It is.

  Optionally, after the crimper, a third spin finish treatment may be applied to the filament (eg, by spraying).

  After crimping, the filament is typically passed through a hot air oven for fixation and drying. The temperature of the oven depends on the composition of the fiber, but most obviously is below the melting point of the least molten component. The oven temperature is generally in the range of 90-130 ° C (eg, 95-125 ° C). The heat treatment also removes a certain amount of water from the spin finish. This drying process is an important factor in making the finish insoluble, for example by possible cross-linking, and as a result imparts permanent properties. The residual moisture content is preferably less than 2,0%, more preferably less than 1,0%, based on the fiber weight.

  The dried filament is then passed through a cutter. Here, the filament is cut into short fibers of a desired length. The fibers of the present invention are generally cut into short fibers having a length of about 18 to 180 mm, more typically about 25 to 100 mm, especially about 30 to 75 mm.

  Antistatic agents can be added at any of the three points in the fiber line (ie, after spinning, after drawing, or after crimping). Antistatic agents are preferably nonionic (eg, phosphate esters) or anionic (eg, phosphates), but cationic antistatic agents are less preferred. However, in a preferred embodiment of the invention, the antistatic agent is added after the crimper.

  The method of making the nonwoven material of the present invention generally includes making fibers at a fiber draw ratio of 1: 2 to 1: 8 (eg, 1: 2 to 1: 6).

  The method of making the nonwoven material of the present invention generally consists essentially of an aqueous polysiloxane emulsion and has an active ingredient content of at least 25% (e.g., an active ingredient content of at least 30%), preferably at least Using a spin finish having an active ingredient content of 35% (eg about 40%). The spin finish is suitably added at a concentration of 2-15% (eg, 5-10%). The concentration of the spin finish is suitably 0.2-1% wt / wt (eg 0.25-0.9%), preferably 0.3-0.85%, more preferably 0.35-0.85%, based on the fiber.

  The present invention further relates to a method of making a nonwoven material comprising the use of a fiber as defined herein or the use of a fiber made as defined herein.

  In making the nonwoven material of the present invention, the fibers are 130-150 ° C. (e.g. 132-148 ° C.), suitably using suitable composite binding fibers such as ES-Fiber Visions fiber type ES-C Cure. Preferably, it is oven-bonded at a temperature of 134 to 144 ° C.

  A further aspect of the invention relates to a hygiene product comprising a nonwoven material as defined herein. A further object of the invention relates to a process for making a sanitary product comprising the use of a non-woven material as defined herein.

  The fibers described in the following examples are characterized according to various parameters important in the respective determination of fiber bulkiness and nonwoven bulkiness. The most prominent of these parameters are crystallinity and fiber / fiber friction. The bulkiness and resilience of the fibers and nonwovens is determined according to any one of standard methods well known to those skilled in the art.

  All measurements were measured according to ISO 554 Standard Atmosphere 23/50.

  The degree of fiber crystallinity can be determined when measured by differential scanning calorimetry (DSC) or X-ray diffraction (XRD). Both of these methods are well known to those skilled in the art.

  Bulkiness and resilience can be measured according to the Inda Standard test “Measuring Compression and Recovery of Highloft Nonwoven” IST 120.3-92. This method was also tailored to measure fiber bulkiness and resilience.

Example
Example 1
The bulkiness and resilience of various fibers and their corresponding nonwovens are shown in Table 1 below.

  As can be seen from the data shown in Table 1, a number of parameters affect the bulkiness and resilience of both fibers and nonwovens. In particular, the type of matrix polymer used, the type of spin finish added during the drawing process, and the draw ratio have an effect. In addition, two other parameters were measured: fiber / fiber friction and fiber crystallinity. These parameters also depend to some extent on the type of matrix polymer used, the type of spin finish added during the drawing process, and the draw ratio. Thus, the bulkiness and resilience of fibers and nonwovens is directly dependent on the type of matrix polymer, the type of spin finish, the draw ratio, and indirectly on the fiber / fiber friction and crystallinity (e.g., These characteristics only reflect the type of matrix polymer used, the type of spin finish used, and the draw ratio used in the manufacturing process). Fiber / fiber friction and crystallinity values are used to help ascertain the connection between numerous parameters in the present invention. Crystallinity is measured by differential scanning calorimetry (DSC) and X-ray diffraction (XRD), and fiber / fiber friction is measured according to the methods described herein.

(Table 1) Data summary. Sample 1 was used as a reference (conventional PPH7059 matrix polymer (no nucleating agent) and conventional spin finish Silastol GF18).

  Surprisingly, Table 1 demonstrates that the inventors of the present invention have discovered that the type of matrix polymer and the type of spin finish are important for the bulkiness and resilience of fibers and nonwovens.

  The trend reflected in the data from Table 1 demonstrates that the fiber / fiber friction of the fiber added with Synthecin 7490 fill in the draw process is smaller than the fiber added with silastol GF602-c alone. This effect is clearly seen when sample numbers 2 and 4 are compared to samples 3 and 5.

  Furthermore, the fiber added with silastol GF602-c has improved bulkiness compared to the fiber added with Synthecin 7490 fill in the drawing process (fiber bulkiness is opposite to nonwoven bulkiness). This is clearly seen when comparing sample numbers 2 and 4 in Table 1 with samples 3 and 5.

  Fibers made of Adstiff HA840R (nucleated polypropylene homopolymer) have a higher degree of crystallinity compared to fibers made of PPH7059 (non-nucleated polypropylene homopolymer). This is clearly seen when comparing sample numbers 2 and 4 with sample numbers 3 and 5 in Table 1.

  Fibers made with Adstiff HA840R (nucleated polypropylene homopolymer) have improved bulk when compared to fibers made with PPH7059 (non-nucleated polypropylene homopolymer) when the same finish is added. Yes. This is clearly seen when comparing sample number 4 and sample number 2 and sample number 5 and sample number 3 in Table 1.

  High draw ratio fibers provide high fiber bulk and high nonwoven bulk compared to low draw ratio fibers. To draw this conclusion, it is necessary that the same type of polymer and spin finish be used (for example, the conditions must be the same for comparison). For example, when comparing Samples 5, 8, and 10 in Table 1, this trend is evident.

  Non-woven fabrics based on fibers with added Synthecin 7490 fill have improved bulk compared to non-woven fabrics with only Silastol GF602-c added. This is clearly seen when comparing sample numbers 3 and 5 in Table 1 with samples 2 and 4.

  Nonwoven fabrics based on fibers made of Adstiff HA840R (nucleated polypropylene homopolymer) have improved bulk compared to nonwoven fabrics based on fibers made of PPH7059 (non-nucleated polypropylene homopolymer). This is clearly seen when comparing sample number 4 and sample number 2 in Table 1 and comparing sample number 5 and sample number 3.

Example 2
The bulkiness and resilience achieved of the fibers and nonwovens are shown in Table 2. The nonwoven fabric was oven bonded using a 30% ES-C composite fiber in the bonding range of 134-140 ° C. Test number 1 was used as a reference (eg, a conventional homopolymer with no nucleating agent added (PPH7059 matrix polymer)).

Table 2 Maximum bulkiness obtained for selected fibers and nonwovens

Of particular note from Table 2 are sample numbers 1 and 4. Sample No. 1 contains a conventional PPH7059 matrix polymer (no nucleation) and a conventional spin finish GF602-c, while Sample No. 4 contains a nucleated Adstiff HA840R matrix polymer and a Synthecin 7490 Phil spin finish. Comparing the two samples, it can be estimated that sample number 4 exhibits a nonwoven bulkiness value (28 cm ³ / g → 74 cm ³ / g) corresponding to an increase of approximately 164%. According to the present invention, and not being bound by any particular theory, this surprising bulkiness surge is a nucleated homopolymer (Adstiff HA840R) that results in highly crystalline and rigid fibers. And Synthecin 7490 Phil spin finish. This combination also results in fibers where the fiber / fiber friction is surprisingly small, and as a result, preferably results in a high bulky nonwoven (eg, the movement between fibers is relatively “free”).

Example 3
Table 3 shows the effect of bonding temperature on bulkiness and resilience. The most preferred bulkiness was obtained at a bonding temperature of 140 ° C. for Adstiff HA840R nucleated matrix polymer containing Synthecin 7490 fill spin finish.

(Table 3) Effect of bonding temperature on bulkiness and resilience

Claims (34)

Fibers based on polyolefin polymers having at least one characteristic selected from the group consisting of:
i) 600 g or less of fiber / fiber friction;
ii) a spin finish consisting essentially of an aqueous polysiloxane emulsion and having an active ingredient content of at least 25%;
iii) a draw ratio of at least 1: 1.5;
iv) Fiber crystallinity of at least 50%.   2. The fiber according to claim 1, wherein the fiber / fiber friction is 500 g or less, preferably 400 g or less.   2. A fiber according to claim 1, wherein the fiber / fiber friction is 200-1000 g (e.g. 200-800 g), preferably 200-600 g, more preferably 200-500 g, most preferably 200-400 g.   The spin finish consists essentially of an aqueous polysiloxane emulsion (e.g., the active ingredient content is at least 30%, preferably the active ingredient content is at least 35% (e.g. about 40%)), The fiber according to any one of claims 1 to 3.   5. The fiber of claim 4, wherein the spin finish is added at a concentration of 2-15% (eg, 5-10%).   The concentration of the spin finish is 0.2-1% wt / wt (eg 0.25-0.9%), preferably 0.3-0.85%, more preferably 0.35-0.85%, based on the fiber. The fiber according to any one of the above.   The fiber of any one of the preceding claims, wherein the fiber crystallinity is at least 55% (eg, at least 60%) as measured by DSC or XRD.   The fiber according to any one of the preceding claims, wherein the polyolefin polymer is a nucleated polymer.   The polyolefin polymer is a nucleated polymer and the nucleating agent is a talc, a metal salt of an aliphatic or aromatic carboxylic acid, a branched polymer including a dendritic branch, and chalk, gypsum, clay, kaolin, mica, and Any of the preceding claims selected from the group consisting of minerals such as silicates and compounds based on D-sorbitol and 1,3-2,4-bis- (3,4-dimethylbenzylidene) -D-sorbitol The fiber according to claim 1.   10. The fiber according to claim 9, wherein the nucleating agent is talc.   10. The fiber of claim 9, wherein the polyolefin polymer is a nucleated polymer nucleated with 5000-10000 ppm talc.   Polyolefins are isotactic or syndiotactic polypropylene homopolymers, homopolymers and copolymers of monoolefins such as ethylene, propylene, α-olefins, 4-methyl-1-pentene and blends thereof, linear polyethylene, high density polyethylene, The fiber according to any one of the preceding claims, selected from the group consisting of low density polyethylene and linear low density polyethylene and blends thereof.   10. The fiber of claim 9, wherein the polyolefin is selected from the group consisting of homopolymer polypropylene and homopolymer polyethylene.   10. The fiber of claim 9, wherein the polyolefin is a homopolymer polypropylene. 2. The fiber of claim 1, having a bulkiness of at least about 30 cm < ³ > / g, at least about 35 cm < ³ > / g (e.g., at least about 40 cm < ³ > / g).   A fiber according to any preceding claim, wherein the draw ratio is about 1: 2 to 1: 8 (eg about 1: 2 to 1: 6), preferably 1: 2 to 1.5.   The fiber of any one of the preceding claims, wherein the ST dtex value is 2 to 20 dtex (eg 2 to 10 dtex), generally 3 to 9 dtex, more typically 5 to 8 dtex.   Polyolefin-based fibers that have a resilience of at least about 40% (eg, about 42%).   The fiber according to any one of the preceding claims, wherein the polyolefin has a flexural modulus of at least 1500 MPa. The polyolefin polymer-based fiber according to any one of the preceding claims, having at least two features selected from the group consisting of:
i) 600 g or less of fiber / fiber friction;
ii) a spin finish consisting essentially of a polysiloxane emulsion;
iii) a draw ratio of at least 1: 1.5 with a final fineness of 2 to 10 dtex;
iv) at least 50% fiber crystallinity;
v) the polyolefin polymer is a nucleated polymer;
vi) The flexural modulus of the polyolefin is at least 1500 MPa. The polyolefin polymer-based fiber according to any one of the preceding claims, having at least two features selected from the group consisting of:
i) 600 g or less of fiber / fiber friction;
ii) a spin finish consisting essentially of a polysiloxane emulsion;
iii) a draw ratio of at least 1: 1.5 with a final fineness of 2 to 10 dtex;
iv) at least 50% fiber crystallinity;
v) The polyolefin polymer is a nucleated polymer. The polyolefin polymer-based fiber according to any one of the preceding claims, wherein the polyolefin polymer is a nucleated polymer and has the following characteristics:
i) 600 g or less of fiber / fiber friction;
ii) a spin finish consisting essentially of a polysiloxane emulsion;
iii) a draw ratio of at least 1: 1.5 with a final fineness of 2 to 10 dtex;
iv) Fiber crystallinity of at least 50%.   23. A nonwoven material made from short fibers based on polyolefins according to any one of claims 1-22. Nonwoven materials based on short fibers based on polyolefins with a bulkiness of at least 30 cm ³ / g and a resilience of at least 50%.   25. The nonwoven material of any one of claims 23-24, wherein the resilience is at least 55% (e.g., at least 60%).   The bulkiness is at least 35% (eg at least 40%), preferably at least 45%, more preferably at least 50%, even more preferably at least 55%, most preferably at least 60%. The nonwoven material as described in any one of Claims.   A method of making fibers based on polyolefins, characterized by the use of: a nucleated polymer, a draw ratio of at least 1: 1.5 at a final fineness of 2-10 dtex, and a spin finish consisting essentially of a polysiloxane emulsion Agent use.   28. The method of claim 27, wherein the polymer is selected from polyethylene and polypropylene.   29. A method according to any one of claims 27 to 28, wherein the draw ratio is 1: 2 to 1: 8 (e.g. 1: 2 to 1: 6).   The spin finish consists essentially of an aqueous polysiloxane emulsion and has an active ingredient content of at least 25% (eg at least 30% active ingredient content), preferably at least 35% active ingredient content (eg about 40% 30) The process of any one of claims 27 to 29.   32. The method of claim 30, wherein the spin finish is added at a concentration of 2-15% (eg, 5-10%).   The concentration of the spin finish is 0.2-1% wt / wt (eg, 0.25-0.9%), preferably 0.3-0.85%, more preferably 0.35-0.85%, based on the fiber. The method according to any one of the above.   35. A method of making a nonwoven material comprising the use of a fiber according to any one of claims 1 to 22, or a fiber made according to the method of any one of claims 27 to 32.   34. The method of claim 33, wherein the fibers are oven bonded at a temperature of 130-150 [deg.] C (e.g. 132-148 [deg.] C), preferably 134-144 [deg.] C.