MXPA96006060A - Degradable multilayer melt blown microfibers - Google Patents

Abstract

Degradable multilayer melt blown microfibers are provided. The fibers comprise (a) at least one layer of polyolefin resin and at least one layer of polycaprolactone resin, at least one of the polyolefin or polycaprolactone resins containing a transition metal salt;or (b) at least one layer of polyolefin resin containing a transition metal salt and at least one layer of a degradable resin or transition metal salt-free polyolefin resin. Also provided is a degradable web comprising the multilayer melt blown microfibers.

Description

MICROFIBERS BLOWED BY FUSION OF MULTIPLE DEGRADABLE LAYERS FIELD OF THE INVENTION The present invention relates to multi-layer degradable meltblown microfibers, which in the form of cloth are useful, as for example, in wicks, absorbent articles, tape backings, release liners, filtration means, insulation means , surgical gowns and curtains and bandages for wounds.

BACKGROUND OF THE INVENTION Numerous attempts have been made to increase the degradability of conventional non-degradable polymers, such as polyolefins for the use of additive systems. These additive systems are often designed to increase the degradability of polymers in a specific type of environment. For example, ferric stearate with various free fatty acids and manganese stearate with stearic acid, have been suggested as suitable systems for providing the degradability in polyolefin materials in the presence of ultraviolet radiation. In addition to a biodegradable polymer such as poly (caprolactone) they have been suggested REF: 23621 to improve the degradability of polyolefins in a ground environment. It has also been suggested that the addition of a starch, an iron compound and a fatty acid or a fatty acid ester can cause the poly (ethylene) to degrade when exposed to heat, ultraviolet radiation or under conditions of composting. It has further been suggested that polyolefins capable of forming manure can be prepared by the addition of a transition metal salt selected from cobalt, manganese, copper, cerium, vanadium and iron and a fatty acid or ester having from 10 to 22 atoms of carbon providing unsaturated species and free acid. Although several-systems have been suggested, improvements in degrading polymeric materials, particularly polyolefins, continue to be sought.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides multi-layer melt blown microfibers comprising (a) at least one layer of polyolefin resin and at least one layer of polycaprolactone resin, at least one of the polyolefin or polycaprolactone resins containing a transition metal salt; or (b) at least one layer of polyolefin resin containing a metal salt of transition, and at least one layer of a degradable resin or a polyolefin resin free of transition metal salt. The degradable resins can be, for example, biodegradable, capable of forming fertilizer, hydrolyzable or soluble in water. In preferred embodiments of the invention, the polyolefin, in addition to the transition metal salt, may contain a fatty acid, a fatty acid ester or combination thereof, which functions as a self-oxidant, i.e., increases oxidative degradation. Surprisingly, the multi-layer meltblown microfibers of the present invention degrade to a greater extent than would be expected from the potential degradation of each of the fiber components. This faster degradation generally occurs without considering the location of the transition metal salt or the optional fatty acid salt or fatty acid ester in the layers. The multi-layer meltblown microfibers of the present invention degrade well in moisture, biologically active environments such as compost, where the biodegradable, water soluble, or composting polymer layers of the microfibers are eroded and from this form expose the remaining degradable polyolefin, even before such exposure, the degradable polymer protects against premature oxidation of the polyolefin layers.

The present invention further provides a fabric comprising multi-layer melt blown microfibers, comprising (a) at least one layer of polyolefin resin and at least one layer of polycaprolactone resin, at least one of the resins of polyolefin or polycaprolactone containing a transition metal salt; or (b) at least one layer of polyolefin resin containing a transition metal salt and at least one layer of a degradable or resin. a free polyolefin resin of the transition metal salt. The fabric can degrade to become brittle in about 14 days at a temperature of 60 ° C and a relative humidity of at least 80%.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top view of an apparatus useful for preparing the multi-layer melt blown microfibers of the present invention.

FIG. 2 is a microphotograph of a five layer microfiber of the present invention at 2,000X as produced.

FIG. 3 is a microphotograph of the microfiber of FIG. 2 after 10 days of _ exposure to fertilizer conditions.

FIG. 4 is a microphotograph of another five layer microfiber of the present invention at 2,500X as produced.

FIG. 5 is a microphotograph of. the microfiber of FIG. 4 after 45 days of exposure to the fertilizer conditions.

DETAILED DESCRIPTION OF THE INVENTION Polyolefin resins, or polyolefins, useful in the present invention include poly (ethylene), poly (propylene), copolymers of ethylene and propylene, poly (butylene), poly (4-methyl-1-pentene), and combinations thereof. The degradable resin can be, for example, biodegradable, capable of forming fertilizer, hydrolysable or soluble in water. Examples of biodegradable resins include poly (caprolactone), poly (hydroxybutyrate), poly (hydroxybutyrate-valerate) and related poly (hydroxyalkanoates), poly (vinyl alcohol), poly (ethylene oxide) and plasticized carbonates such as starch and pullulan. The Examples of composting resins include modified poly (ethylene terephthalate), for example, Experimental Resin Lot No. 9743, available from EI DuPont of Nemours and Company, Wilmington, DE, extrudable starch based resins such as Mater-BiMR , available . from Novamont, S.p.A., Novara, Italy. Examples of hydrolysable resins include poly (lactic acid), cellulose esters, such as cellulose acetates and propionates, hydrolytically sensitive polyesters such as EarthguardRM Lot No. 930210 (experimental), available from Polymer Chemistry Innovations, State College, PA, polyesteramide and polyurethanes. Water-soluble resins include poly (vinyl alcohol), poly (acrylic acid) and KodakRM AQ (experimental polyester), available from Kodak Chemical Co. , Rochester, N.Y. Additionally, poly (vinyl alcohol) copolymers with a polyolefin, for example, poly (ethylene vinyl alcohol) or poly (vinyl acetate), both of which are less easily soluble in water, but biodegradable, can be 'degradable resins. tools. The transition metal salts which can be added to the polyolefin or, in some aspects of the invention, to the poly (caprolactone), include those discussed, for example in U.S. Patent No. 4,067,836 (Potts et al. .). These salts can be those that have organic or inorganic ligands. Ligands Suitable inorganics include chlorides, nitrates, sulfates, and the like. Preferred organic ligands are such as octanoates, acetates, stearates, oleates, naphthenates, linoleates, talates and the like. Although a wide range of transition metals have been described in the art as being suitable for various degrading systems, in the present invention it is preferred that the transition metal be selected from cobalt, manganese, copper, cerium, vanadium and iron, more preferably cobalt, manganese, iron and cerium. The transition metal is preferably present in a concentration in the range of 5 to 500 ppm, more preferably 5 to 200 ppm, which is highly advantageous, such as metals that are generally undesirable in high concentrations. The high transition metal concentrations in polyolefin or poly (caprolactone) can lead to toxicological and environmental issues due to the leaching of the aquifer mantle of these metals in the surrounding environment. In addition, higher transition metal concentrations can produce fibers, which degrade rapidly in such a way that storage stability can be a problem. The optional fatty acid or fatty acid ester is preferably present in the polymer composition at a concentration of 0.1 to 10 percent by weight. The fatty acid, when present, is preferably present in a concentration sufficient to provide a concentration of free acid species greater than 0.1 percent by weight based on the total composition. The fatty acid ester, when present, is preferably present in a concentration sufficient to provide a concentration of unsaturated species greater than 0.1 percent by weight. Preferably, the fatty acid, the fatty acid ester or combinations thereof, when present, are present in a concentration sufficient to provide a concentration of free acid species greater than 0.1 percent by weight and a concentration of saturated species greater than 0.1 percent by weight based on the total composition. In general, it is preferred that the composition must be freestanding for at least two weeks, and more preferably 2 to 12 months. As degradation occurs slowly, even at room temperature for some of the embodiments of the invention, for products with longer shelf life, generally lower concentrations of the transition metal or fatty acid (free acid and / or saturated species) will be required. to provide a fiber fabric to the average intended shelf life of the fabric. on the contrary, higher concentrations of the metal or fatty acid species will be required for fibers with short, shelf-stable shelf life.

It was found that adequate degradation under typical composting conditions requires salts of the transition metals mentioned in the foregoing in combination with the acidic portions such as those found in unsaturated fatty acids. It was also found that the unsaturation in the fatty acid, or a mixture of the mixed fatty acid ester or natural oil, is required to produce adequate degradation with the appropriate transition metal compound. Preferably, this fatty acid is present in the composition of the polymer at concentrations of at least 0.1 percent by weight of the composition. Also suitable are mixtures of fatty acids and fatty acid esters or oils while the amount of free acid and unsaturated species are generally equivalent to the ranges described above for a composition containing pure fatty acid. Generally, it is found that unsaturated fatty acids and fatty acid esters having 10 to 22 carbon atoms work well in providing the rate of degradation required for a composting material. Such materials include, for example, oleic acid, linoleic acid, and linolenic acid; Oleoestearic acid, found in high concentration in the ester form, in natural palo oil; flaxseed oil and fish oils such as sardine, fish liver, shad and herring oil. The preferred process for preparing the fibers of the invention is described in U.S. Patent No. 5,207,970 (Joseph et al.). The process used the apparatus shown in FIG. 1 wherein the polymeric components are introduced into the cavity 12 of the die 10 of a separate divider, the divider or distributor region 14 in combination, for example in the extruder divider, such as 16 and 17. The gear pumps and / or purge blocks can also be used to finely control the flow rate of the polymer. In a combination splitter or distributor, the flow currents of the separated polymer component are formed in a single layer flow stream. However, preferably, the separated flow streams are kept out of direct contact for as long a period as possible before reaching the matrix 10. The divided or separate streams are combined only immediately before reaching the matrix or holes in the matrix. This minimizes the possibility of flow instabilities that they generate in separate flow streams after it is combined into the single-layer flow stream, which tends to result in a non-uniform and discontinuous longitudinal layer in multi-layer microfibers. From the matrix cavity 12, the polymer flow stream of. Multiple layers are extruded through an orifice arrangement 19 side by side. Prior to that extrusion, the feed may be formed in the appropriate profile in the cavity 12 acfecuated by the use of a transition piece of a conventional coating hook. The air slots 18, or the like, are positioned on either side of the row of holes 19 to direct the uniformly heated air at a high velocity in the melt streams in extruded layers.The air temperature is generally about the current of the melt, although preferably from 20 ° C to 30 ° C, higher than the melt temperature of the polymer.This heat extracts air at high speed and attenuates the extruded polymer material, which usually solidifies after being displaced a relatively short distance from the matrix 10. The solidified or partially solidified fibers are then formed into a fabric by the known methods and harvested.The following examples further illustrate this invention, but the particular materials and their amounts in these examples, as well as also the conditions and details, should not be considered unduly for limit this invention. In the examples, all parts and percentages are by weight unless otherwise specified. In the examples, the following test procedures were used.

Base Weight A sample of 10 x 10 cm (cm) was cut from the microfiber cloth and weighed as close to ± 0.001 g. The weight was multiplied by 100 and base weight in g / m2 was reported.

Fragility Test Fabric samples are tested by hand for frailty after aging in forced air ovens at 49 ° C, 60 ° C and 70 ° C in 12 to 24 hour intervals. A state of frailty is defined as the time at which samples of the fabric have little or no tear or tensile strength that they lend or would be crumbled when folded. With lower melting or softer melting polymers such as poly (caprolactone), the sample fabrics generally do not disintegrate or crumble, but on the contrary, become stiff and lose tensile strength. The conditions of the fertilizer were stimulated by placing the fabric samples in a water container which was buffered to a pH of 6 of the phosphate buffer and it is heated to 60 ° C and those fabric samples are tested for brittleness at intervals of 30 to 50 hours. Additionally, the fabric samples are removed from the water containers at regular time intervals and are measured for weight priority.

Weight Loss Test The fabric samples (5 cm x 5 cm) are pre-weighed as close to ± 0.0001 g. The fabric samples are placed in a forced air oven at 60 ° C or 93 ° C and removed at regular time intervals and measured for weight loss.

Test for Fertilizer Simulation A mixture of the following was prepared: 445 g of crushed maple leaves 180 g of shredded paper (50:50 newspaper: computer) 75 g of meat waste (1: 1 mixture of dry Cat ChowMR and Dry Dog Chow ™ from Ralson Purina Company, St. Louis, MO) 200 g of food waste (frozen mixed vegetables, commercial mix of peas, beans, carrots and corn) 13.5 g plus compost (from Ringer Corporation, Minneapolis, MN) 60 g of dehydrated cow pasture 900 mi water 6 g of urea The complete mixture is placed in a 22.7 liter (1) rectangular tank (35.6 cm X 25.4 cm X 25.4 cm) of poly (propylene) Nalgene with a cover (from Fisher Scientific Co., St. Louis, MO). The humid air moves through the fertilizer mixture at a rate of 15 ml / minute dispersing the air through water with thick glass frit (25.4 cm X 3.8 cm) and then in the lower part of the fertilizer tank. through a perforated stainless steel tube. The microfiber fabrics are cut into 5 cm X 5 cm squares and labeled, such that the samples are designated for removal at predetermined time intervals. If the weight loss is to be determined, the fabric samples are pre-weighed. The fabric samples (10-15) are uniformly placed in the fertilizer mixture and the tank is covered to minimize the loss of moisture.

The tank is placed in an oven at 55 ° C. Generally, after a period of four to ten days, the additional water is added to give 60 percent by weight of water. Approximately every two days the condition of the fertilizer and the fabric samples are verified. The fabric samples are pulled and folded to determine any changes in strength or brittleness. The fabric samples are duplicated in different tanks, the fabric samples are They are typically removed at predetermined intervals of 10, 20, 30 and 45 days and cleaned by gentle washing in water, dried and weighed. The change in percent by weight is determined. The condition of the fertilizer is determined by measuring the pH, the percentage of humidity and the temperature. The initial pH was typically in the range of 4.5-5.5 and increased slowly during the test period to the range of 7.5-8.5, with the average pH during the test period being 6.8 to 8.0. The percent of water is maintained at approximately 60% by the careful addition of water as needed. The average percent of registered water was in the range of 50-65% by weight. The temperature of the fertilizer increased during the first two weeks of operation, due to the high level of microbiological activity during this period of time. After the temperature of the fertilizer is maintained at the oven temperature of 55 ° C with average temperatures during the duration of the test in the average range of 53-62 ° C. The trial period was 45-60 days. ' Tension Module and Percent of Tension to Breaking The data of the tension module on multi-layer microfiber fabrics are obtained in accordance with ASTM D882-91"Standard Test Method for Tensile Properties of Thin Plastic Sheeting "using an Instron Stress Tester (Model 1122), Instron Corporation, Canton, MA with a clamping space or clamp of 10.48 cm and a crosshead speed of 25.4 cm / min. The samples of the fabrics were 2.54 cm wide.

PREPARATION OF THE BLOWED MICROFIBER FABRIC Examples 1-11 The multi-layer blown microfiber fabrics of the present invention were prepared using a meltblowing process as described in U.S. Patent No. 5,207,970 (Joseph et al. ). The process used a meltblown matrix having uniform, circular (10 / cm) surface holes with a length-to-diameter ratio of 5: 1. The microfiber fabrics are prepared using the amount and type of metal stearate and the amount and type of auto-oxidant as shown in Table 1. The powdered metal stearate and / or the fatty self-oxidants are added to the polymer resins in a mixer with a mixing blade driven by an electric motor to control the mixing speed. The mixture of metal stearate / auto-oxidant / resin, metal stearate / resin, or auto-oxidant / resin is placed in the hopper of the first or second extruder depending on whether the mixture is used in Polymer 1 or Polymer 2 or both of them. The first extruder (210sC) supplied a melt stream of one speed of melt flow rate of 800 (MFR) and a mixture of poly (propylene) resin (PP) (PP 3495G, available from Exxon Chemical Corp., Houston, TX) to the feed block assembly, which is heated to approximately 210 ° C. The second extruder, which also was maintained at about 210 ° C, supplied a melt stream of a poly (caprolactone) (PCL) resin (ToneMR 767P, available from Union Carbide, Danbury, CT) to the feed block. The power block divides the two streams of melt. The polymer melt streams are fused in an alternating fashion in a five-layered melt stream at the outlet of the feed block, with the inner layers which are the poly (propylene) resin. The gear pumps are adjusted in such a way that the ratio of the polymer 1: olimer 2 pump is supplied to the feedblock assembly as given in Table 1. A polymer production speed of matrix width of 0.14 kg / h / cm is maintained in the matrix (210 ° C). The primary air temperature is maintained at approximately 209 ° C and at a suitable pressure to produce a uniform fabric with a 0.076 cm space. The fabrics are collected in a collector at a distance of 26.7 cm from the matrix. The resulting microfiber fabrics comprising five layer microfibers having an average diameter of about micrometers has a basis weight of approximately 100 g / cm2. The brittleness test is performed on the microfiber fabrics of Examples 1-11 and the results are reported in Table 2. The weight loss after 300 hours of aging at 60 ° C in a furnace as well as the average weight of the molecular weight (M ^) and the average number of the molecular weight (Mn) after such aging conditions at various intervals are determined for the microfiber fabrics of Examples 5, 9b, and 11 and are reported in Table 3 The weight loss for Examples 4, 10 and 11 after several time intervals of being in water (pH = 6.0) at 60 ° C as described in the Fragility Test are reported in Table 4. The loss of Weight for the microfiber fabrics of Example 4, 10 and 11 after being subjected to the Fertilizer Simulation Test are reported in Table 5. The initial modulus and the percent of tension at break were determined for microfiber fabrics of Examples 1-11 and what The results are reported in Table 6.

Control Fabric I The control fabric of polypropylene resin 800 MFR was prepared according to the procedure of Examples 1-11, except that only one extruder was used, which was maintained at 220 ° C, and was connected directly to the matrix through a gear pump. The temperatures of the matrix and air are maintained at 220 ° C. The resulting microfiber fabric had a basis weight of 100 g / m2 and a fiber diameter of less than about 10 microns. The weight loss after 300 hours of aging at 60 ° C in an oven and the average weight of molecular weight (M ^) and the average number of molecular weight (Mn) after such aging conditions at various intervals was determined and they are reported in Table 3.

Control Fabric II A control fabric of the polypropylene resins and the poly (caprolactone) resin was prepared according to the procedure of Examples 1-11. The temperatures of the matrix and the air were maintained at 220 ° C. The resulting microfiber fabric had a basis weight of 102 g / m2 and an average fiber diameter of less than about 10 microns. The microfiber fabric is tested for brittleness and for the initial modulus and tensile stress at breaking. The results are reported in Tables 2 and 6, respectively.

Comparative Examples A-C Three microfiber comparative fabrics of the polypropylene resin and the poly (caprolactone) resin without the metal stearate were prepared according to the procedure of Examples 1-11. The amount and type of auto-oxidant is set forth in Table 1. The resulting microfiber fabrics had a basis by weight of 102 g / m2 and an average fiber diameter of approximately 10 microns. The microfiber fabrics were tested for brittleness and for the initial modulus and tensile stress at breaking. The results are reported in Tables 2 and 6, respectively.

Comparative Examples D-F Three microfiber comparative fabrics of the polypropylene resin with or without the auto-oxidant were prepared according to the procedure of Examples 1-11 as modified in the Control I procedure to use an extruder. The amounts and types of the metal stearate and the auto-oxidant are given in Table 1. The resulting microfiber fabrics have bases by weight of 97, 102, and 104 g / m2, respectively, and an average fiber diameter of less of approximately 10 micrometers.

The weight loss after 300 hours of aging at 60 ° C in an oven and the average weight of the molecular weight (Mw) and the average number of the molecular weight (Mn) after such aging conditions at various intervals are established in the Table 3 Comparative Examples GH Two comparative microfiber fabrics of the poly (caprolactone) resin with two types of metal stearate and a self-oxidizer are prepared according to the procedure of Examples 1-11 as modified in the Control I procedure. to use an extruder. The quantities and types of the metal stearate and the auto-oxidant are given in Table 1. The resulting microfiber fabrics had a basis by weight of 100 g / m2, and an average fiber diameter of less than about 10 microns. The weight loss after 300 hours of aging at 60 ° C in an oven and the average weight of molecular weight (NL ^) and the average number of molecular weight (Mn) after such aging conditions at various intervals are established in Table 3 Example 2 A microfiber fabric having a basis by weight of 96 g / mm2 and comprising 5-layer microfibers which have an average diameter of less than about 10 microns, was prepared according to the procedure of Examples 1-11, except that the polypropylene resin without metal stearate and auto-oxidant was replaced by the poly (caprolactone) resin in the second extruder. The microfiber cloth was tested for frailty with the results reported in Table 2. Weight loss after 300 hours of aging at 60 ° C in an oven and average molecular weight (NL and average number) Molecular weight (Mn) after such aging conditions at various intervals, were determined and reported in Table 3. Weight loss after various time intervals of being in water (pH 06.0) at 60 ° C as described in the brittleness test was determined and reported in Table 4. The fabric was evaluated for the initial modulus and the tensile stress at break and the results are reported in the Table 6 Examples 13-14 Two microfiber fabrics having a basis weight of 110 g / m2 and comprise 5-layer microfibers having an average diameter of less than about 10 microns are prepared according to the procedure of Examples 1-11, except that a modified poly (ethylene terephthalate) (PET) (resin) experimental lot # 9743 available from EI Du Pont de Nemours and Company, Wilmington, DE) was replaced by the poly (caprolactone) resin in the second extruder. Fabrics were tested for brittleness with results reported in Table 2. Weight loss after 300 hours of aging at 60 ° C in an oven and average weight of molecular weight p (M ^) the average number of molecular weight (Mn) after such aging conditions at various intervals are set forth in Table 3. The weight loss after several time intervals of being in water (pH = 6.0) as described in the Fragility Test are reported in the Table 4. The weight loss of the fabric of Example 13 after being subjected to the stimulation test to form fertilizer is reported in Table 5. The fabrics of Examples 13-14 were evaluated for the initial module and the percent of tension to breaking and the results are established in Table 6.

Comparative Example I A comparative microfiber fabric of the poly (ethylene terephthalate) used in Examples 13 and 14 with a metal stearate and a self-oxidizer is prepared according to the procedure of Examples 1-11 as modified by the process in Control I for the use of an extruder. The amount of cobalt stearate and oleic acid used are set out in the Table I. The resulting microfiber fabrics have a basis weight of 137 g / m2 and a fiber diameter of less than about 10 microns. The weight loss after 300 hours of aging at 60 ° C in an oven is reported in Table 3.

Example 15 A microfiber fabric having a basis weight of 107 g / m2 and comprising 5-layer microfibers having an average diameter of less than about 10 microns is prepared according to the procedure of Examples 1- II, except that an experimental hydrolysable polyester (PEH) (Kodaktm AQ available from Kodak Chemical Co., Rochester, NY) was replaced by the poly (caprolactone) resin in the second extruder. The microfiber cloth was tested for brittleness with the results set forth in Table 2. Weight loss after 300 hours of aging at 60 ° C in an oven and the average molecular weight (M ^) and the average number Molecular weight (Mn) after such aging conditions at various intervals are reported in Table 3. Weight loss after several time intervals of being in water (pH = 6.0) at 60 ° C as described in Fragility Test was reported in Table 4. Weight loss after being submitted to the Stimulation Test to form Compost is reported in Table 5. The microfiber cloth was evaluated for the initial modulus and the percentage of tension at break and the results are set forth in Table 6.

Example 16-17 Two microfiber fabrics having a basis weight of 107 g / m2 and comprising 5-layer microfibers having an average diameter of less than about 10 microns are prepared according to the procedure of Examples 1-11, except that a polyurethane resin (PUR) (PE90-200 available from Morton International, Seabrook, NH) was replaced by the poly (caprolactone) resin in the second extruder. Fabrics were tested for frailty with results reported in Table 2. Weight loss after 300 hours of aging at 60 ° C in an oven and average molecular weight (NL ^) the average number of molecular weight ( Mn) after such aging conditions at various intervals are set forth in Table 3. Weight loss after several time intervals of being in water (pH = 6.0) at 60 ° C as described in the Fragility Test is reported in Table 4. The weight loss of the fabric of Example 16 after being subjected to the Stimulation Test to form Fertilizer is reported in Table 5. The fabrics were also evaluated for the initial module and the percentage of stress at break and the results are set forth in Table 6.

Comparative Examples JK Two microfiber comparative fabrics of the polyurethane resin used in Examples 16 and 17 with two types of metal stearate and a self-oxidizer were prepared according to the procedure of Examples 1-11 as modified in the 1 Control I procedure for the use of an extruder. The amounts and types of metal stearate and auto-oxidant are set forth in Table 1. The resulting microfiber fabrics have a basis weight of 74 g / m2 and an average fiber diameter of less than about 10 microns. The weight loss after 300 hours of aging at 60 ° C in an oven and the average weight of the molecular weight (M ^ and the average number of molecular weight (Mn) after such aging conditions at various intervals, are reported in Table 3 Examples 18-19 The two microfiber fabrics having a basis weight of 107 g / m2 and comprising 5-layer microfibers, having an average diameter of less than about 10 microns were prepared according to the procedure of Examples 1-11, except that a polyvinyl alcohol (PVOH) resin (Vinex r 2019 available from Air Products and Chemicals, Allentown, PA) was replaced by the poly resin. (caprolactone) in the second extruder. The amounts of manganese stearate and oleic acid are set forth in Table 1. The microfibers of Example 18 are shown in FIGURES 2 and 3. FIGURE 2 shows a 5-layer microfiber 20, containing layers of poly (polypropylene), 22A and 22B and poly (vinyl alcohol) layers 24A, 24B and 24C as they were run at a 2000X amplification. FIGURE 3 shows the result of subjecting the fiber 20 to the Fertilizer Formation Stimulation Test for 10 days at an amplification of 2 OOOX. The water-soluble biodegradable layers had been eroded, leaving the polyolefin fiber 23 degradable exposed and dispersed. The microfiber fabrics were committed to the Fragility Test and the results are set forth in Table 2. The weight loss after 300 hours of aging at 60 ° C in an oven and the average weight of the molecular weight (M ^.) and the average number of molecular weight (Mn) after such aging conditions at various intervals for the microfiber fabrics are reported in Table 3. Weight loss after various time intervals of being in water (pH = 6.0) at 60 ° C as described in the Fragility Test was reported in Table 4. The weight loss for Example 18 after being subjected to the Fertilizer Stimulation test is reported in the Table 5. The fabrics were evaluated for the initial module and the percentage of tension to the break is established in Table 6.

Comparative Examples LM Two comparative microfiber cloths of the polyvinyl alcohol resin used in Examples 18-19 with two types of metal stearate and a self-oxidizer were prepared according to the procedure of Examples 1-11 as modified in the Control I procedure for the use of an extruder. The amounts and types of metal stearate and auto-oxidant are given in Table 1. The resulting microfiber fabrics had a basis weight of 148 and 140 g / m2, respectively and an average fiber diameter of less than about 10 microns. The weight loss after 300 hours of aging at 60 ° C in an oven and the average molecular weight weight (M ^) and the average number of molecular weight (Mn) after such aging conditions at various intervals for the fabrics of microfibers are reported in Table 3.

Examples 20-21 Two microfiber fabrics having a basis weight of 107 g / m2 and comprising 5-layer microfibers having an average diameter of less than about 10 microns were prepared according to the procedure of Examples 1-11 , except that a poly (lactic acid) (PLA) resin (EC0PLAmr Experimental resin # DVD 98, available from Cargill Inc., Minneapolis, MN) was replaced by the poly (caprolactone) resin in the second extruder. The microfiber fabrics were subjected to the Fragility Test with the results reported in Table 2. The weight loss after 300 hours of aging at 60 ° C in an oven and the average weight of the molecular weight (M ^ and the number Molecular weight average (Mn) after such aging conditions at various intervals for microfiber fabrics are reported in Table 3. Weight loss after several time intervals of being in water (pH = 6.0) at 60 ° C as described in the Fragility Test are reported in the Table. The weight loss of the fabrics after being submitted to the Fertilizer Formation Stimulation Test are reported in Table 5. The fabrics were evaluated for the initial module and the percentage of tension to the break and the results are given in the Table 6 Comparative Example N A comparative microfiber fabric of the poly (lactic acid) resin used in Examples 20-21 with cobalt stearate and oleic acid were prepared according to the procedure of Examples 1-11 as modified in the process of Control I to use an extruder. The amount of metal stearate and auto-oxidant are given in Table 1. The resulting microfiber cloth has a basis weight of 158 g / m2 and an average fiber diameter of less than about 10 microns. The weight loss after 300 hours of aging at 60 ° C in an oven and the average weight of the molecular weight (Mw) and the average number of molecular weight (M_) after such aging conditions at various intervals for the fabrics of Microfibers are reported in Table 3.

Examples 22-23 Two microfiber fabrics having a basis weight of 96 g / m2 and comprising 5-layer microfibers having an average diameter of less than about 10 microns were prepared according to the procedure of Examples 1-11 , except that a poly (hydroxybutyrate-co-valerate) resin (18% valerate) (PHBP) (PHBP-18, available from Zeneca Bioproducts, New Castle, DE) was replaced by the poly (caprolactone) resin in the second extruder. The microfibers of Example 22 are shown in FIGURES 4 and 5. FIGURE 4 shows the 5-layer microfibers 30 at a 2 500X amplification containing the degradable poly (propylene) layers 32A and 32B and the poly (hydroxybutyrate) layers. -valerate) 34A, 34B and 34C as initially formed. FIGURE 5 shows the microfibers of Example 22 after being committed to the Fertilizer Formation Stimulation Test for 45 days at an amplification of 2 500X. The biodegradable layers have been eroded, leaving the degradable polyolefin fibers 36 exposed. The microorganisms 38 which may have helped in the degradation of the fiber are observed attached to the fiber. The fabrics were subjected to the Fragility Test and the results are set forth in Table 2. The weight loss after 300 hours of aging at 60 ° C in an oven and the average weight of the molecular weight (M ^ and the average number Molecular weight '(Mn) after such aging conditions at various intervals for microfiber fabrics are reported in Table 3. Weight loss after several time intervals of being in water (pH = 6.0) at 60 ° C as described in the Frailty Test are reported in Table 4. The weight loss of the fabrics after being subjected to the Stimulation Test of Fertilizer formation are set forth in Table 5. The fabrics were evaluated for the initial module and the percent stress at break and the results are reported in Table 6.

Examples 24-25 Two microfiber fabrics having a basis weight of 114 and 102 g / m2, respectively, and comprising 5-layer microfibers having an average diameter of less than about 10 microns are prepared according to the process of Examples 1-11, except that a hydrolysable polyester (PES) (Earthguardmr, Experimental batch # 930210 available from Polymer Chemistry Innovations, State College, PA) was replaced by the poly (caprolactone) resin in the second extruder. . The microfiber fabrics were subjected to the Fragility Test with the results reported in Table 2. The weight loss after 300 hours of aging at 60 ° C in an oven and the average molecular weight (Mw) weight and number Molecular weight average (Mn) after such aging conditions at various intervals for microfiber fabrics are reported in Table 3. Weight loss after several time intervals of being in water (pH = 6.0) at 60 ° C as described in the Frailty Test are reported in Table 4.

The weight loss for Example 24 after being subjected to the Fertilizer Formation Stimulation Test are reported in Table 5. The fabrics were evaluated for the initial module and the percentage of tension at break and the results are given in the Table 6 As can be seen from the data in Table 2, microfiber fabrics having the lowest frailty times were those containing both a metal stearate salt and a self-oxidizer. However, for fabrics containing only one metal stearate, the lowest brittle time was for Example 2, which had cobalt stearate followed by Example 1, which had manganese stearate and Example 3 which had iron stearate, respectively. This trend in metal stearate activity, Co > Mn > Faith, was observed in each comparison. Microfiber fabrics containing only a self-oxidizer are described in Comparative Examples A-C. These comparative examples demonstrate the improved ability of a self-oxidant containing both of the unsaturation and an acidic proton to effect the oxidative degradation of a polyolefin, when compared with either the unsaturation (stick oil) or an acid proton (stearic acid) alone.

The three materials, oleic acid (Comparative Example A), palo oil (Comparative Example B), and stearic acid (Comparative Example C), are descriptive, but not exhaustive of the types of auto-oxidants found useful in this invention. Examples with a composition ratio (pumping ratio) of 50/50 poly (propylene) / polymer 2 had less brittleness time than when Polymer 2 was also poly (propylene). However, many of these examples presented a fragility time that is still acceptable for another evaluation, with these times of fragility = 336 hours at 60 ° C in the Fragility Test described above. The fact that the fragility of these examples occurred indeed was surprising, since Polymer 2 was not expected to undergo oxidative degradation except where Polymer 2 was poly (propylene) or polyurethane. In general, since the ratios of the composition of the microfibers are changed from 25/75 to 50/50 to 75/25 of poly (propylene) / polymer 2, the times of brittleness in the furnace were diminished in each temperature investigated, due to the higher content of the easily oxidative degradable component. The same trend was observed for the set of examples that have the composition ratios for the microfibres from 50/50 to 75/25 for poly (propylene) / polymer 2. The results for the brittle times in an oven can not be directly compared with the results in water, since several of the materials used as Polymer 2 were either water soluble and / or slightly hydrolytically unstable. Both of these characteristics they can be expected to influence the fragility of the microfiber cloth to an unknown degree.

As can be seen from the data in Table 3, Control I which was 10 percent poly (propylene) without metal stearate or auto-oxidant had very little loss of weight after 300 hours in an oven at 60 ° C and without decrease in average molecular weight (^) or average molecular weight (Mn) indicating that there is no substantial degradation. Comparative examples, which have 100 percent microfibers of poly (propylene) with manganese stearate alone, manganese stearate or cobalt stearate and oleic acid were extensively degraded, as evidenced by weight loss and molecular weight decrease . the molecular weight data indicate that no degradation occurred in fabrics having 100 percent microfibers of poly (caprolactone). The molecular weight data indicate that no degradation occurred in fabrics having 10 percent microfibers of poly (caprolactone) with stearate of manganese or cobalt stearate and oleic acid,. fabrics that have 100 percent microfibers of polyvinyl alcohol with manganese stearate or cobalt stearate and oleic acid and the fabric that has 100 percent microfibers of poly (lactic acid) with cobalt stearate and oleic acid. In the comparative example that has microfibers of 100 percent modified poly (ethylene terephthalate) (PET) with cobalt stearate and oleic acid, there was little weight loss and the molecular weight data was not obtained, due to the insolubility of this polymer in appropriate solvents. In the examples, which contain 5-layer 50/50 microfibers of poly (propylene) / poly (caprolactone) with manganese stearate and oleic acid or stearic acid in poly (propylene) and in the example, which had 75/25 5-layer microfibers of poly (propylene) / poly (caprolactone) also with manganese stearate and oleic acid in poly (propylene), poly (caprolactone) was also degraded as poly (propylene). However, the fraction of the poly. { caprolactone) degraded more slowly than the poly (propylene) fraction and the maximum 50/50 combination at a higher molecular weight during degradation. In the following examples, each layer of fibers, whether containing manganese stearate or cobalt stearate and a self-oxidizer or not, was observed to undergo extensive degradation, evidenced by weight loss and / or molecular weight decrease: fabrics from the comparative examples that have 100% poly (propylene) microfibers with manganese stearate and oleic acid in some of the layers of poly (propylene), the fabric having 5-layer 50/50 microfibers of poly (propylene) / Koda rar AQ polyester (PEH) with manganese stearate and oleic acid in layers of poly (propylene) and fabrics having 5-layer microfibres of 50/50 and 75/25 poly (propylene) / polyurethane respectively with manganese stearate and oleic acid in the layers of poly (propylene). However, 100% polyurethane with manganese stearate or cobalt and oleic acid degraded by themselves. Fabrics having 50/50 and 75/25 5-layer microfibers of poly (propylene) / poly (vinyl alcohol) with manganese stearate and oleic acid in the layers of poly (propylene), the fabrics having microfibers of 5 50/50 and 75/25 layers of poly (propylene) / poly (hydroxybutyrate-valerate). with manganese stearate and oleic acid in the layers of poly (propylene), fabrics that have 50/50 5-layer microfibers and 75/25 poly (propylene) / poly (hydroxybutyrate-valerate) with manganese stearate and oleic acid in the layers of poly (propylene) each showed extensive degradation in each layer. In fabrics having 50/50 and 75/25 5-layer microfibers of poly (propylene) / hydrolysable polyester (PES) with manganese stearate and oleic acid in the poly (propylene) layers, the molecular weight data in the 50/50 poly (propylene) / hydrolysable polyester fabric does not clearly indicate degradation, but the results in the poly (propylene) / hydrolysable polyester fabric, 75/25 indicated degradation of the entire fabric. In fabrics that have 50/50 5-layer microfibers and 75/25 poly (propylene) / poly (lactic acid) microfibers with Manganese stearate and oleic acid in the layers of poly (propylene) changes in molecular weight indicated less degradation. In fabrics that have 50/50 and 75/25 5-layer microfibers of poly (propylene) / poly (terephthalate, modified ethylene) (PET) with manganese stearate and oleic acid in the layers of poly (propylene), the molecular weight data were inconclusive since the degradation of the modified poly (ethylene terephthalate) due to insolubility but the poly (propylene) layers were degraded.

The results in Table 4 indicate that fabrics containing hydrolytically degradable or water soluble polymers have relatively high percent by weight losses in the Weight Loss Test in water at 60 ° C. Fabrics which experience weight loss and / or disintegrate in this test are expected to work well in the Simulated Fertilizer Test. The fragility data for these examples were described in Table 2.

The data in Table 5 demonstrate that fabrics containing biodegradable or hydrolysable resins show significant weight loss when subjected to the Fertilizer Formation Simulation Test. In addition, the fabrics were tested for fragility at two or three day intervals. Fabrics that have 50/50 5-layer microfibers of poly (propylene.) / Poly (caprolactone), 25/75 of poly (propylene) / poly (caprolactone) and 75/25 of poly (propylene) / poly (caprolactone), respectively with manganese stearate and oleic acid in the poly (propylene) contain poly (caprolactone) which is biodegradable. The 25/75 poly (propylene) / poly (caprolactone) fabric was really brittle or fragile in 30 days in the compost and the 50/50 fabrics of poly (propylene) / poly (caprolactone) and 75/25 poly (propylene) / poly (caprolactone) both became embrittled in 49 days in the fertilizer. The fabric that has 5-layer 50/50 microfibers of poly (propylene) / poly (vinyl alcohol), with manganese stearate and oleic acid in poly (propylene) contains poly (vinyl alcohol), which is soluble in water and biodegradable and the fabric was brittle after 42 days in the fertilizer. The fabric that has 50/50 5-layer microfibers of poly (propylene) / poly (lactic acid) with manganese stearate and oleic acid in poly (propylene) contains the poly (lactic acid) which is biodegradable and the fabric It was brittle in 42 days of testing and the 75/25 poly (propylene) / poly (lactic acid) fabric brittle at 49 days. The fabric that has 5-layer 50/50 microfibres of poly (propylene) / poly (hydroxybutyrate-valerate) with manganese stearate and oleic acid in poly (propylene) contains the biodegradable and brittle poly (hydroxybutyrate-valerate) at 49 ° C. days. The remaining samples in Table 5 were not observed to experience brittleness during the 58 day trial period.

As can be seen from the data in Table 6, the tension modulus and the stress percentage at break, measured in the initial 5-ply fabrics, indicates that the fabrics of the invention initially had usable voltage modules.

Examples 26-36 The microfiber fabrics having a basis weight as shown in Table 7 and comprising, two-layer microfibers, having an average diameter of less than about 10 microns were prepared according to the process of Examples 1-11, except that the molten streams of poly (propylene) and poly (caprolactone) were supplied to a two-layer feed block, the first extruder is heated to about 242 ° C, the second extruder is heated to about 190 ° C. ° C, the power block assembly is heated to approximately 240 ° C, the temperature of the die and the air are maintained at approximately 240 ° C and 243 ° C, respectively. The amount of manganese stearate and / or the amount of oleic acid used in the poly (propylene) / or the poly (caprolactone) and the pumping ratios are given in Table 7. Examples 26-30 were exposed to three temperatures different in an oven to determine the amount of time necessary for the fragility of the fabrics as described in the previous test procedures. Examples 26-30 are aged at a higher temperature (93 ° C) in an oven and removed at regular intervals to determine weight loss as described in the above test procedures. The results are given in Table 8. Examples 31-32 were aged at 93 ° C for intervals of 50, 100, 150, 200 and 250 hours and the weight loss was determined. The results are given in Table 9. Examples 33-36 were also aged at 93 ° C for intervals of 150 and 250 hours and the weight priority was determined. In addition to the weight loss, the average weight of the molecular weights and the average number of the molecular steps were determined using gel permeation chromatography (GPC). The results are given in Table 10.

Examples 37-38. Two microfiber fabrics comprising three layer microfibers having an average diameter of less than about 10 microns were prepared according to the procedure of Examples 20-36, except that the molten streams of poly (propylene) and poly (caprolactone) were supplied to a three-layer feed block.

The amount of manganese stearate used in the poly (propylene) and the pumping ratios are given in Table 7. Examples 37-38 were aged at 93 ° C for intervals of 50, 100, 150, 200 and 250 hours and the weight loss was determined. The results are given in Table 9.

Examples 39-40 Two microfiber fabrics comprising five layer microfibers having an average diameter of less than about 10 microns are prepared according to the procedure of Examples 26-36, except that the molten streams of poly (propylene) and Poly (caprolactone) were supplied to a five layer feed block. The amount of manganese stearate used in the poly (propylene) and the pumping ratios are given in Table 7. Examples 39-40 are aged at 93 ° C for intervals of 50, 100, 150, - 200 and 250 hours and the weight loss was determined. The results are given in Table 9.

Examples 41-42 Two microfiber fabrics comprising nine layer microfibers having an average diameter of less than about 10 microns were prepared in accordance with Process of Examples 26-36, except that the molten streams of poly (propylene) and. Poly (caprolactone) were supplied to a nine-layer feed block. The amount of the manganese stearate used in the poly (propylene) and the pumping ratios are given in Table 7. Examples 41-42 are aged at 93 ° C for intervals of 50, 100, 150, 200 and 250 hours and the weight loss is determined. The results are given in Table 9.

Examples 43-44 Two microfiber fabrics comprising nine layer microfibers having an average diameter of less than about 10 microns were prepared according to the procedure of Examples 41-42, except that a different polypropylene was replaced (DyproMR 3576 available from Shell Chemical Co., Houston, TX) by the polypropylene resin in the first extruder. The amount of the manganese stearate used in the poly (propylene) and the pumping ratios are given in Table 7. Examples 43-44 were aged at 93 ° C for 150 and 250 hour intervals and the weight loss is determined . In addition to the weight loss, the average weight the molecular weights and the average number of weights Molecules were determined using GPC scales. The results are given in Table 10.

Examples 45-53 Fabrics of nine microfibers comprising twenty-seven layer microfibers, having an average diameter of less than about 10 microns, were prepared according to the procedure of Examples 26-36, except that the molten streams of poly ( propylene) and poly (caprolactone) were supplied to a twenty-seven layer feed block. The amount of the manganese stearate and / or the amount of oleic acid used in the poly (propylene) and / or the poly (caprolactone) and the pumping ratios are given in Table 7. Examples 45-49 are exposed to three different temperatures in an oven, to determine the amount of time needed to make fabrics brittle or brittle as described in the previous test procedures. Examples 26-30 were aged at a higher temperature (93 ° C) in an oven and removed at regular intervals to determine the weight loss as described in the above test procedures. The results are given in Table 8.

Examples 50-52 were aged at 93 ° C for intervals of 50, 100, 150, 200 and 250 hours and the weight loss determined. The results are given in Table 9. Example 53 was also aged at 93 ° C for 150 and 250 hour intervals and the weight loss was determined. In addition to the weight loss, the average weight of the molecular weights and the average number of molecular weights determined using GPC scales. The results are given in Table 10.

Control Fabric III The control fabric comprises twenty-seven layer microfibers having an average diameter of less than about 10 microns, is prepared according to the Control Fabric II procedure, except that the molten streams of poly (propylene) and Poly (caprolactone) were supplied to a twenty-seven layer feed block. Control Fabric III was aged at 93 ° C for 150 and 250 hour intervals and weight loss was determined. In addition to the weight loss, the average weight of the molecular weights and the average number of molecular weights determined using GPC scales. The results are given in Table 10.

When only manganese stearate was used, the lowest brittle times were observed for fabrics where manganese stearate was added to both poly (propylene) and poly (caprolactone). The placement of manganese stearate only in the poly (propylene) layers was also effective, as was surprisingly, the placement of manganese stearate only in the layers of poly (caprolactone). Fabrics containing both of manganese stearate and oleic acid in poly (propylene) exhibited the lowest times for brittleness. Fabrics containing manganese stearate in poly (caprolactone) and oleic acid in poly (propylene) had the following lower times for brittleness, followed by fabrics containing manganese stearate in both poly (propylene) and poly (caprolactone) . Keeping the composition of the fabric constant, the number of layers has little effect on the amount of degradation as can be seen in the percent weight loss. The time for fragility seems to be the best indicator of the performance of a degradable fabric than the results of high temperature weight loss.

As can be seen from the data in Table 9, fabrics containing microfibers of two, three, five, nine, and twenty-seven layers exhibited weight loss during oven aging at 93 ° C. Time seems to be the only significantly significant factor shown by the statistical analysis. In general, the highest weight losses were observed for samples containing higher percentages of poly (propylene). The highest percent weight loss was observed for three and twenty-seven layer fabrics. fifteen As can be seen from the data in Table 10, the twenty-seven layer fabric that does not contain manganese stearate did not have a significant molecular weight change or weight loss, while the twenty-seven layer microfiber fabric containing manganese stearate in poly (propylene) undergoes significant weight loss by aging and molecular weight changes were significant. Similar results were observed for microfiber fabrics of two and nine layers of equivalent basis weight. Fabrics produced from two-layer microfibers with a basis in weight less than the losses in percent by weight greater by aging at 93 ° C, due to the surface area of the larger fabric per mass. Any of the differences observed in the extent of degradation, as evidenced by the change in molecular weight, for examples of microfiber fabrics containing two, nine or twenty-seven layers were negligible. Various modifications and alterations of this invention will be apparent to those skilled in the art without departing from the scope and spirit of this invention., and this invention should not be restricted to what is set forth herein for illustrative purposes. It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention is the conventional one for the manufacture of the objects to which it refers. Having described the invention as above, the content of the following is claimed as property:

Claims (23)

RgXVI DICACIONES

1. Multilayer meltblown microfibers characterized in that they comprise: (a) at least one layer of polyolefin resin and at least one layer of polycaprolactone resin, at least one of the polyolefin or polycaprolactone resins containing a salt of transition metal in an amount of at least 5 ppm; or (b) at least one layer of polyolefin resin containing a transition metal in an amount of at least 5 ppm and at least one layer of a degradable resin or a polyolefin resin without transition metal salt.

2. The meltblown, multi-layer microfibers according to claim 1, characterized in that the polyolefin is poly (ethylene), poly (propylene), copolymers of ethylene and propylene, poly (butylene), poly (4-methyl-l- pentene), or a combination thereof.

3. The multi-layer meltblown microfibers according to claim 1, characterized in that the degradable resin is biodegradable, form fertilizer, hydrolyzable, soluble in water or a combination thereof.

4. The meltblown, multi-layer microfibers according to claim 3, characterized in that the biodegradable resin is poly (caprolactone), a poly (hydroxyalkanoate), poly (vinyl alcohol), poly (ethylene vinyl alcohol), poly (ethylene oxide) ) or plasticized carbohydrate.

5. The multi-layer meltblown microfibers according to claim 4, characterized by qi. the poly (hydroxyalkanoate) is poly (hydroxybutyrate) or poly (hydroxybutyrate-valerate).

6. The multi-layer meltblown microfibers according to claim 3, characterized in that the compost-forming resin is modified poly (ethylene terephthalate) or a resin based on extrudable starch.

7. The meltblown, multi-layer microfibers according to claim 3, characterized in that the hydrolysable resin is poly (lactic acid), a cellulose ester, poly (vinyl acetate), a on the way to a polyester, a hydrolytically sensitive polyester or a polyurethane.

8. The multi-layer meltblown microfibers according to claim 3, characterized in that the water-soluble resin is polyvinyl alcohol or polyacrylic acid.

9. The multi-layer meltblown microfibers according to claim 1, characterized in that the transition metal salts have organic or inorganic ligands.

10. The multi-layer meltblown microfibers according to claim 9, characterized in that the organic ligands are octanoates, acetates, stearates, oleates, naphthenates, linoleates or talates.

11. The multifilated meltblown microfibers according to claim 9, characterized in that the inorganic ligands are chlorides, nitrates or sulfates.

12. The multi-layer meltblown microfibers according to claim 1, characterized in that the transition metal is cobalt, manganese, copper, cerium, vanadium or iron.

13. The multi-layer meltblown microfibers according to claim 1, characterized in that the transition metal is present in the polymer composition in an amount of about 5 to 500 ppm.

14. The multi-layer meltblown microfibers according to claim 1, further characterized in that they comprise a fatty acid, an ester of the fatty acid or a combination thereof.

15. The meltblown, multi-layer microfibers according to claim 14, characterized in that the fatty acid, the fatty acid ester or its combination is present in the polymer composition at a concentration of about 0.1 to 10 percent by weight.

16. The multi-layer melt blown microfibers according to claim 14, characterized in that the fatty acid is oleic acid, linoleic acid, oleoestearic acid, or stearic acid.

17. The multi-layer meltblown microfibers according to claim 14, characterized in that the fatty acid ester is stick oil, linseed oil or fish oil.

18. The meltblown, multi-layer microfibers according to claim 14, characterized in that the fatty acid is present in sufficient concentration to provide a concentration of a free acid species greater than 0.1 percent by weight based on the total composition.

19. The multi-layer meltblown microfibers according to claim 14, characterized in that the fatty acid ester is present in sufficient concentration to provide a concentration of unsaturated species greater than 0.1 percent by weight based on the total composition.

20. The multi-layer meltblown microfibers according to claim 14, characterized in that the combination of fatty acid and ester of the fatty acid is present in a sufficient concentration to provide a concentration of unsaturated species greater than 0.1 percent by weight and 0.1 percent by weight based on the total composition.

21. A fabric comprising multi-layer melt blown microfibers characterized in that it comprises: (a) at least one layer of the polyolefin resin and at least one layer of polycaprolactone resin, at least one of the polyolefin or polycaprolactone resins they contain a transition metal salt in an amount of at least 5 ppm; or (b) at least one layer of the polyolefin resin containing a transition metal salt in an amount of at least 5 ppm and at least one layer of a degradable resin or polyolefin resin without metal salt of transition.

22. The fabric according to claim 21, characterized in that the fabric degrades to brittleness in about 14 days at a temperature of 60 ° C and a relative humidity of at least 80%.

23. The fabric according to claim 21, further characterized in that it comprises a fatty acid, an ester of the fatty acid or its combination.