JPH05247822A - Polymer web having blend of spunbonded filament and melt-blown fiber integrated into single layer - Google Patents

Abstract

PURPOSE: To obtain a nonwoven-formed web from a blend as a composite web of spunbonded filaments and melt-blown fibers. CONSTITUTION: This nonwoven composite web comprises spunbonded filaments and melt-blown fibers, wherein each of the spunbonded filaments has an average diameter of >=6 μm and a birefringence of >=10×10<-3> and each of the melt-blown fibers has an average diameter of <=6 μm and a birefringence of >=10×10<-3> and the spunbonded filaments accounts for >=50 wt.% of the composite web. Alternatively, the nonwoven composite web may further include melt-brown fibers each with a diameter of >=6 μm and a birefringence of <=10×10<-3> . In both the cases described above, the spunbonded filaments and melt-blown fibers can be produced from polypropylene and/or linear low-density polyethylene, respectively.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to an integrated mixture of two types of fibers, spunbond and meltblown, prior to their deposition on a collecting or forming surface. The web formed by integrating these fibers can be used for various purposes. For example, disposable diapers, sanitary napkins, surgical drapes, or in combination with other materials can be used as a substrate in forming laminates.

[0002]

Nonwoven fabrics can be used in a wide variety of applications including personal nursing products such as sanitary napkins and disposable diapers. Nonwoven fabrics of the type having a capillary structure are useful, for example, in personal care products as an intermediate transfer layer to disperse liquids and minimize leakage. In addition to this, those having a large basic weight have good absorbability and can be used as an absorbent medium for personal care products. In addition to its use as a non-woven fabric for personal care products, the present invention allows the non-woven fabric to be used in many other applications. For example, it can be used as a cleaning material or wipe in household chores, as a towel or bath mat in the service field, as a cleaning material or wipe in the field of automobiles and ships, and as a wipe in the field of hospitals and veterinary hospitals. it can. As will be apparent from the description below,
The present invention allows non-woven fabrics to be widely used in many applications other than those mentioned above. The present invention also provides methods and apparatus for forming such nonwoven fabrics into a three-dimensional web.

The technology for producing non-woven fabrics is quite advanced.
Generally, in the manufacture of nonwoven webs, after forming the filaments or fibers, they are deposited on a carrier and the filaments or fibers are laid or entangled as a mat having the desired basis weight. .. The mats thus formed are simply entangled or by other means. Other means are, for example, application of adhesive, heating and / or pressurization of the heat-sensitive fibers, or in some cases only pressurization. Although many methods are generally known, two commonly used methods are the spunbond method and the meltblown method.

Spunbond nonwoven structures are described in many US patents. For example, US Pat. No. 3,565,729 to Hartmann (issued February 23, 1971), US Pat. Nos. 4,4 to Appel and Morman.
05,297 (issued September 20, 1983), Dor
schner, Carduck, Storkebaum
U.S. Pat. No. 3,692,618 (issued Sep. 19, 1972). Spunbond webs made from thermoplastic fibers are well known in the art and have many uses.

Descriptions of the meltblown process can also be found in many references. For example, "IND
USUAL AND ENGINEERING C
HEMISTRY "Volume 48, No. 8 (19
56), 1342-1346, We.
ndt's paper "Ultrafine thermoplastic fibers", Bunti
U.S. Pat. No. 3, n., Keller, Harding
No. 978,185 (issued August 31, 1976), Pr
U.S. Pat. No. 3,795,571 to Entice (1
U.S. Pat. No. 3,811,957 to Buntin (issued Mar. 21, 1974).

Spunbond and meltblown webs are widely used in many applications. For example, Matt
hews, Allison, Woon, Steven
U.S. Pat. No. 4,397,644 (issued Aug. 9, 1983) to F. S., Bornslaeger.
personal care products such as those described in US Pat. No. 4,372,312 to Enler, Bernardin (issued February 8, 1983). In such applications, spunbond fibers and meltblown fibers are often used in adjacent layers.

One of the recent prior arts, European Patent Application 403,840A1 (Corovin), discloses the mixing of small diameter discontinuous microfibers and large diameter continuous filaments to form a composite nonwoven. ing. In this non-woven fabric, "there is almost no gradient in cross section regarding the difference in fiber diameter", and "the two functions of different fiber components are combined". This European patent claims the combination of small diameter (10 micron or less) discontinuous fibrils "with little molecular orientation" and large diameter (15 micron or more) continuous filaments "having molecular orientation". I am trying. One of the advantages of this composite non-woven is that it can be quickly transported from the integrated belt to the thermal bond calendering mechanism. This advantage allows the composite nonwoven material to be pre-bonded (prior to main bonding).

Therefore, it is desirable to provide a polymer web in which spunbond filaments and meltblown fibers are integrated in the same layer. In the present invention, “spunbond filament” refers to a filament or fiber drawn from a melt, and the cross-sectional dimension of these filaments or fibers has an average diameter of more than 6 microns and an average diameter of 15-40. Micron is preferred,
Sufficient molecular orientation is given by the spinning process, the average birefringence is larger than 10 × 10 ⁻³ , and further 15
It is preferably larger than × 10 ^-3 . Similarly, "meltblown fibers" refers to fibers that have been trickled from the melt, and the cross-sectional dimensions of these fibers have an equivalent diameter of 6 microns or less and a refractive index greater than 10 x 10 ^-3. Or having a diameter of 6 microns or more and a birefringence number of 10 × 10.
^-3 or less. One of the improvements in such a mixture is an increase in the degree of bonding, which contributes to the physical entanglement of the meltblown fibers around the spunbond filaments.

[0009]

SUMMARY OF THE INVENTION A nonwoven web according to the present invention comprises a blend.
Has at least one layer
Spunbond filaments and multiple small diameter meltblends
With spunbond filament
Has an average diameter greater than 6 microns, preferably 15-
It is in the range of 40 microns and the average birefringence is 10 × 10.
^-3This average birefringence is greater than
Shown, small diameter meltblown fibers are 6 microns or less
Has a lower diameter and a birefringence number of 10 × 10^-3Greater than
This birefringence number indicates the existence of molecular orientation.
At least 50% (wt%) of the coalescence is spunbond fiber
It is Lament. This mixture also includes multiple
Diameter meltblown fibers can be included. This
Rutblown fibers have a diameter of at least 6 microns
And the number of birefringence is 10 × 10^-3And this birefringence number
Indicates that the molecular orientation is small, and the
At least 50% (wt%) is spunbond filament
is there.

The present invention further provides a method of forming a layer of a nonwoven web comprising a mixture of spunbond filaments and meltblown fibers. This method comprises the steps of forming a plurality of spunbond filaments having an average diameter of 6 μm or more, preferably 15 to 40 μm, and having an average birefringence number of 10 × 10 ⁻³ or more showing molecular orientation, and A process of forming a plurality of small diameter meltblown fibers having a diameter of 6 microns or less and a birefringence number of 10 × 10 ⁻³ or more, and mixing the plurality of spunbond filaments with the meltblown fibers to obtain at least 50% of the mixture.
(Wt%) into spunbond filament,
Depositing the mixture on the forming surface to form a layer. This method comprises the steps of forming a plurality of large diameter meltblown fibers having a diameter of at least 6 microns and a birefringence number of 10 × 10 ⁻³ or less, and prior to depositing these large diameter meltblown fibers on the forming surface. The method may further include mixing the meltblown fibers with the spunbond filaments and the small diameter meltblown fibers.

The above mixture may be one in which spunbond filaments are mixed only with large diameter meltblown fibers, or small diameter meltblown fibers may be the third plurality of fibers. However, in each case, at least 50% (wt%) of spunbond filaments must remain in the mixture.

[0012] One of the important points of the present invention is the characteristic of distinguishing between spunbond filaments and meltblown fibers. The diameter of the spunbond filament and the corresponding birefringence number (measured value of molecular orientation) are narrowly distributed around the average value. U.S. Pat. No. 4,405,297 (Ap
Applicants' investigation of polypropylene spunbond filaments made according to the method described in Pel et al.) resulted in the values shown in Table 1A for individual spunbond filaments.

Table 1A Filament diameter (microns) Birefringence number (× 10 ⁻³ ) 21.1 21.0 26.6 10.9 20.9 22.6 21.4 24.1 21.0 23.6 22 0.0 21.8 23.7 16.1 Average 22.4 20.0

The following cases (cases 1-5, 7-15)
The polypropylene spunbond filaments prepared according to the conditions shown in 1) also showed a narrow distribution centered on the average diameter and the average birefringence number. Mean values obtained from the sample population are shown in Table 1B. This average value indicates that the smaller the fiber diameter, the greater the molecular orientation.

Table 1B Average filament diameter (microns) Average birefringence number (× 10 ⁻³ ) 13.9 32.2 14.5 33.6 18.7 20.3

For polyethylene (linear low density) spunbond filaments made according to Cases 6 and 16, the values of diameter and birefringence as shown in Table 2 are:
Similar to those values for polypropylene SB filaments.

Table 2 Filament diameter (micron) Birefringence number (× 10 ⁻³ ) 14 to 16 17.8 to 23.5 17.5 to 18.6 18.3 to 24.5 27 17.9 to 27. 9

These data show typical distributions of expected diameter and birefringence for polypropylene and polyethylene spunbond filaments. The birefringence number was calculated by determining the filament deceleration measurements using a Berek compensator (which was fitted with a polar microscope) and dividing the measurements by the diameter of each filament. The birefringence for spunbond filaments made from other polymers such as copolymers, nylons and polyesters (not thermally stabilized) is believed to be in the same range as birefringence for polypropylene.

Meltblown fibers generally have an average diameter of 6 microns or less, but can be 20 microns or more by reducing the trickling force. In determining the average diameter of meltblown fibers made by the meltblown method, the range of diameters involved in determining the average diameter is wide. 100
An example of the diameter distribution in a sample population of individual meltblown fibers is as follows.

[0020]

As can be seen from the measured values, most of the meltblown fibers have a diameter of 6 microns or less, but 1
Some have a diameter of 0 microns or more. The birefringence number for polypropylene meltblown fibers with a diameter of 6 microns or less was determined by the Applicant and is measured by INDA Jo
urn of of Nonwovens Research
ch 1991 Spring issue (Volume 3, N
O. 2, page 27), and can be compared to spunbond filaments and conventional melt spun fibers. In this diameter range (6 microns or less), I
Birefringence number reported in NDA Journal is 1
It is 5.2 × 10 ^{−3 to} 26.1 × 10 ⁻³ . When the present applicant measured the birefringence number in the same meltblown fiber diameter range, it was 14.0 × 10 ^{−3 to} 60.0 × 10 ^−3.
Met.

As the diameter of polypropylene meltblown fiber becomes 6 microns or more, the birefringence number becomes 10 × 1.
It fell below 0 ^-3 . That is, the larger the meltblown fiber, the smaller the birefringence number. The data shown in Table 4 indicates the birefringence number (and range) corresponding to polypropylene meltblown fiber diameter, as determined by the applicant.

Table 4 Diameter range (micron) Birefringence number range (× 10 ⁻³ ) <1.0 30-60 1.0-2.0 24-55 2.0-3.0 11-48 3.0 Up to 4.0 11 to 40 4.0 to 5.0 10 to 31> 6.0 10 or less

Table 5 shows diameter and birefringence values for polypropylene meltblown fibers made according to the conditions set forth in the cases described below (eg, Cases 1 and 3).

Table 5 Diameter (micron) Birefringence number (× 10 ⁻³ ) 3.48 40.0 4.06 35.3 4.45 21.0 4.96 24.9 4.97 24.2 5. 88 27.9 7.73 5.3 5.3 10.00 9.6 19.00 6.7

According to this data, the degree of molecular orientation represented by the birefringence number decreases as the diameter of the meltblown fiber increases. When the diameter is larger than 6 μm, the birefringence number is 10 × 10 ⁻³ or less.

Cases described later (for example, Cases 5 and 6)
The birefringence number for a polyethylene (linear low density) meltblown fiber made according to the conditions described in 1. was the same as that of polypropylene meltblown. Table 6 shows examples of these birefringence numbers.

Table 6 Diameter (micron) Birefringence number (× 10 ⁻³ ) 4.42 38.1 5.05 32.5 5.31 32.5

Generally, spunbond filaments are
It is possible to distinguish from meltblown fibers by comparing the differences in diameter. As indicated above, the diameter of meltblown fibers is typically less than 6 microns. However, since a wide range of fiber diameters can be obtained in the process of producing meltblown fibers, it is necessary to distinguish spunbond filaments from meltblown fibers based on factors other than fiber diameter.

In the diameter range where the spunbond filaments and the meltblown fibers overlap in size, the birefringence number can be used to distinguish between meltblown fibers and spunbond filaments. The diameter of the fiber is determined by two factors: extrusion rate and trickling. The trickling imparts a molecular orientation to the fiber, which can be measured by refractometry. The following possibilities arise depending on the degree of trickling of both fibers. (A) If the degree of molecular orientation with respect to the meltblown fibers is greater than the degree of molecular orientation with respect to the spunbond filaments, the diameter of the meltblown fibers will be 6 microns or less. Alternatively, (b) if the degree of molecular orientation with respect to the meltblown fibers is smaller than the degree of molecular orientation with respect to the spunbond filaments, the diameter of the meltblown fibers will be 6 microns or more. Alternatively,
(C) If the degree of molecular orientation with respect to the meltblown fiber is the same as the degree of molecular orientation with respect to the spunbond filament, the diameter of the meltblown fiber is usually 6 to 1.
The range is 0 micron.

The relative degree of molecular orientation can be determined by measuring the birefringence number. The setting of the meltblown fiber diameter range for a given birefringence number is based on data for meltblown fibers and spunbond filaments.

It can be seen that by using the fiber diameter and the birefringence number for the meltblown fiber in combination, the meltblown fiber having a larger diameter can be distinguished from the spunbond filament. The birefringence of meltblown fibers with a diameter less than 6 microns is at least 20 ×
^Frequently 10 ^-3 , but melt-blown fibers with diameters larger than 6 microns typically have a birefringence number of 10 x 1
It is smaller than 0 ^-3 .

Accordingly, it is an object of the present invention to include an integrated layer of spunbond filaments and meltblown fibers, the meltblown fibers being incorporated into the spunbond filaments by frictional forces, the meltblown fibers being spunbond filaments. To provide a non-woven web that is physically entangled with to stabilize the position of spunbond filaments in the web.

It is a further object of the present invention to include an integrated layer of spunbond filaments and meltblown fibers, the meltblown fibers being incorporated into the spunbond filaments by frictional forces, the meltblown fibers being spunbond filaments. To provide a method for forming a nonwoven web that is physically entangled with and stabilizes the position of spunbond filaments in the web.

It is a further object of the present invention to provide a mixture of spunbond filaments and meltblown fibers, such that some degree of integration of both is done prior to depositing the fibers on the forming surface. is there.

It is a further object of the present invention to provide a method of forming a mixture of spunbond filaments and meltblown fibers, such that some degree of integration of both occurs before the fibers are deposited on the forming surface. It is to be.

To achieve these ends, the nonwoven webs of the present invention consist of thermoplastic fibers made from polyolefin homopolymers using spunbond and meltblown processes. Polyolefin homopolymers include polypropylene or polyethylene, blends of polyolefin homopolymers, copolymers of polyolefins, blends of polyolefin homopolymers and copolymers, polyesters, copolymers of polyesters with nylon and nylon, and / or the aforementioned thermoplastic fibers. There are bicomponent fibers in any combination of.

The diameter of spunbond filaments having a circular cross section is measured optically using a light transmission and / or scanning electron microscopy system. For trilobal, bilobal, or other spunbond filaments with a non-circular cross section, the "equivalent" diameter is calculated from a micrograph of the non-circular cross section of the fiber obtained by scanning electron microscopy. The area enclosed by the non-circular cross section is adjusted according to the degree of magnification. This area value is used to determine the corresponding diameter value.

Filament formation (narrowing from melt)
During this time, the thermoplastic macromolecules are preferentially oriented in the axial direction of the filament. This molecular orientation, the degree of which is related to the degree of trickling, gives rise to anisotropic properties that are observable under polarized light (and the microscope). The degree of this anisotropy can be measured as a "deceleration value". The deceleration value is the difference in refractive index based on the vibration direction of light passing through the filament. More specifically, when polarized light enters inside an optically anisotropic filament, it is decomposed into oscillating components in two perpendicular planes. One of the planes is parallel to the length of the filament and the other is vertical. Since each component faces two principal directions of vibration with different indices of refraction, each component will pass through the filament at different rates. As a result, one component appears with a deceleration by a predetermined amount depending on the difference between the two indices of refraction and the difference in material thickness.

The birefringence number is a dimensionless number obtained by dividing the deceleration value of plane polarized light passing through the sample by the thickness of the sample. The birefringence number indicates the degree of molecular orientation of the material. The deceleration value is until the deceleration values in both directions become equal.
It can be obtained by adding the compensation amount of the deceleration value to one of the vibration components. A Berek compensator, which is a quartz crystal attached to a rotating micrometer, is typically used to measure deceleration values.

The methods for measuring the fiber diameter and the birefringence number of the meltblown fibers are the same as for the spunbond filaments.

The present invention provides several advantages over conventional methods of making spunbond webs because the unbonded web formed in accordance with the invention does not require a compaction process during its manufacture. Have. In general, a compaction process for unbonded spunbond webs is necessary to increase the degree of bonding, i.e. the web forming strength for subsequent processes. Subsequent steps to the compaction process include hot point calender bonding, hot draft bonding, laminating, and transporting the web to other support surfaces.

In the present invention, the presence of meltblown fibers integrated into the spunbond filament matrix provides sufficient strength to the unbonded web such that the compaction step can be omitted.
This increased degree of bond in the unbonded web provides the advantage of superior fabric and physical properties over conventional spunbond webs.

The following are the advantages obtained when the spunbond filament is produced by the method of the present invention. (A) The degree of vacuum required to fix the spunbond filament to the forming substrate can be reduced. (B) The compact roll can be omitted. Along with this, it is possible to eliminate the production loss caused by winding the cloth around these compact rolls. (C) It is easy to convey the unbonded web to the next step (for example, hot point calender bonding) because the degree of bonding when unbonded is increased. (D) winding the unbonded web into rolls for temporary storage or for transport to the next manufacturing step,
In addition, you can unwind.

The physical properties which are improved by using the method according to the invention are those relating to bulk and stiffness. The bulk of the web according to the present invention is large when compared to a compacted spunbond web having a similar basis weight.

The advantages of the present invention over conventional spunbond fabrics result from the proper selection of polymer components for both spunbond filaments and meltblown fibers. Improved hand properties and subsequent processing steps (eg hot point calendering) are possible when the spunbond filaments have different thermal properties, such as melt / softening temperature, from the meltblown fibers.

In addition, the present invention allows the addition of the inherent strength of spunbond filaments which acts as a strength-imparting component in the fabric structure. However, unlike conventional point-bonded spunbonded fabrics, the present invention has the advantage of eliminating point-bonding, which impairs the aesthetics of the finished fabric. This aesthetic advantage is particularly useful when using spunbond filaments as a strength adder in underwater entanglement and / or heat point calendering when laminating other nonwoven fabrics or films.

In the present invention, a nonwoven fabric composed of spunbond filaments and meltblown fibers is integrated as a three-dimensional web. The web is formed by combining the air streams used to pull and carry each fiber. The degree of integration of these two types of fibers can vary from a completely uniform structure to one in which the integration of these two types of fibers occurs only in portions of thickness less than the total web thickness. is there.

The present invention combines a spunbond filament carrying air stream made by any spunbond filament manufacturing method with a meltblown fiber carrying airstream made by any meltblown fiber manufacturing method. Consists of.

As will be described later in detail with reference to the drawings, in the method according to the present invention, the spunbond filaments and the meltblown fibers are each produced using known devices. From the point where the spunbond filament exits the tensioning device and is surrounded by trickling air, the spunbond filament is a porous integrated surface, usually a movable porosity forming wire,
Head to. The direction in which the spunbond filaments travel is usually at a right angle to the forming wire, but this direction may be less than a right angle. A vacuum source may be placed below the forming wire to facilitate formation of the composite web.

As described in US Pat. No. 4,405,297 to Appeal and Norman, meltblown fibers may be one or the other (ie, upstream or downstream) with respect to the "curtain" formed by the spunbond filaments. ), Or both, toward the spunbond filament. These meltblown fibers are typically formed at a height that is less than the exit height of the spunbond puller and at some distance from the plane defined by the spunbond curtain.

The degree of integration between the spunbond filaments and the meltblown fibers depends on the volumetric flow rate and velocity of the air jets used to form these two types of fibers, their position within the aforementioned ranges. And it is calculated from the magnitude of the forming vacuum degree.

[0053]

EXAMPLES The present invention will be described below with reference to the preferred examples, but the scope of the present invention is not limited to these examples. To the contrary, it is intended to include all changes, modifications and equivalents that are intended to be included within the scope of the invention as defined by the claims.

FIG. 1 is a sectional view of the manufacturing apparatus of the present invention. A fluid-borne spunbond filament jet or curtain 10 is produced by a spunbond tensioning device 20. The spunbond tensioning device 20 is located along the central plane D. This central plane D defines the position of the spunbond filament curtain 10. The outlet 19 of the spunbond tensioning device 20 is located a distance A from the porosity forming surface 10. This distance A is 20 inches or less and defines the formation height of the spunbond. The two meltblowing dies 30, 40 each have a die tip 31, 41. These two meltblowing dies 30, 40 are symmetrically located on opposite sides of the spunbond filament curtain 10, and the die tips 31, 41 are located equidistant B, C from the center plane D. Distances B and C are
The range is 0.5 to 7 inches with respect to the center plane D included in the spunbond filament curtain 10. The melt-blowing die tips 31, 41 are located above the forming surface 110 by distances J and H, respectively. The meltblowing dies 30,40 produce airborne meltblown fiber curtains 50,60. Each curtain 50, 6
0 has central planes E and F, respectively. These meltblown fiber curtains 50, 60 have central planes D and E.
Angle 70 between and and angle 8 between the median planes D and F
Hit the spunbond filament curtain 10 so that 0 is equal. These angles 70, 80 range from 90 degrees (maximum merging angle) to 5 degrees or less, which is the angle for carrying fibers in most thin film structures. The spunbond filaments and meltblown fibers are mixed in mixing zone 90 to form fiber mixture 100. This fiber mixture 100 has a merged jet or curtain 1 with a central plane G.
01 included. Center plane G of fiber mixture 100
From the first central plane D of the spunbond filament curtain 10 can be shifted by an angle 140 to a position G ', or by an angle 150 to a position G ". The angles 140, 150 can range from 0 degrees to 20 degrees. The fiber mixture 100 is then mixed with the movable porosity forming surface 1.
10 is deposited. Air for fiber delivery forms surface 110
To form a fibrous web 120 on the forming surface 110. A vacuum source 130 can be placed below the forming wire to promote fiber deposition on the forming surface 110.
Once the fibers are deposited on the forming surface 110, the web is removed from the forming surface 110 for further processing.

A second manufacturing apparatus according to the present invention is shown in FIG. The same reference numerals indicate the same components as in FIG. Figure 2
The apparatus shown in Figure 1 has the same features as Figure 1, except that the meltblowing dies 30, 40 are arranged asymmetrically. The meltblowing dies 31 and 41 are separated from the central plane D by distances B and C, respectively. Distance B and C
May or may not be equal, but are still in the range 0.5 to 7 inches from the midplane D included in the spunbond filament curtain 10. The melt-blowing dies 31 and 41 are located above the forming surface 110 at intervals of distances J and H, respectively. Melt blown filament curtain 5 carried by air
0 and 60 have central planes E and F, respectively. These meltblown fiber curtains have an angle of 7
It corresponds to a spunbond filament at 0 and 80. Angle 7
0 and 80 are not equal. These angles 70, 80 are 90
Values range from degrees (maximum confluence angle) to 5 degrees or less, which is the angle for carrying fibers in most thin film structures. The spunbond filaments and meltblown fibers are integrated and deposited on the porosity forming surface in a manner similar to the device shown in FIG.

A third device according to the present invention is shown in FIG. The same reference numerals indicate the same components as those in FIGS. 1 and 2. The apparatus shown in FIG. 3 has the same features as FIGS. 1 and 2, except that only one meltblowing die 30 is used to add meltblown fibers to the spunbond filaments from one side. The meltblowing die 30 is located on either side of the spunbond filament curtain 10. In the present example, the meltblown die tip 31 is located upstream of the porosity forming surface 110 in the direction of motion. The meltblown die tip 31 is located a distance B from a central plane D contained in the spunbond filament curtain 10. This distance B is
Within 0.5 to 7 inches from the midplane D included in the spunbond filament curtain 10. The melt-blown die tip 31 is located a distance J above the forming surface 110. The meltblowing die 30 forms a meltblown fiber curtain 50 that includes a midplane E. The meltblown fiber curtain 50 has an angle 70 between the median planes D and E from 90 degrees (maximum confluence angle) to 5 degrees or less, which is the angle for carrying fibers in most thin film structures. It hits the spunbond filament curtain 10 so that the value of the range becomes.
The spunbond filaments and meltblown fibers are mixed in mixing zone 90 to form fiber mixture 100. This fiber mixture 100 has a central plane G,
It is included in the merged jet or curtain 101. The median plane G of the fiber mixture 100 may be displaced from the initial center plane D of the spunbond filament curtain 10 by an angle 140 to a position G ', or by an angle 150 to a position G ". 150 can range from 0 to 30. The integrated spunbond filaments and meltblown fibers are then deposited on the porosity forming surface in the same manner as previously described.

A fourth device according to the present invention is shown in FIG. The same reference numerals indicate the same components as those shown in FIGS. 1, 2 and 3. The apparatus shown in FIG. 4 makes an angle 160 with the forming surface 110 because the spunbond filament curtain 10 and its mid-plane D use a curved section 21 adjacent the exit 19 of the spunbond tensioning apparatus 20. 3 has the features shown in FIG. The meltblowing die 30 forms a meltblown fiber curtain 50 having a median plane E. The meltblown die tip 31 is located above the spunbond filament curtain 10 such that the distance A between the meltblown die tip 31 and the forming surface 110 is 20 inches or less. The center plane D of the spunbond filament curtain 10 is a distance B from the meltblown die tip 31. This distance B represents the shortest distance between the center plane D and the melt-blown die tip 31, and is 0.5 to
Within 7 inches. The outlet 19 of the spunbond tensioning device 20 is located a distance K above the forming surface 110. This meltblown fiber curtain 50
Has a value in the range of 90 degrees (maximum merging angle) between the central planes D and E to 5 degrees or less (this is an angle for carrying fibers in a structure of almost a thin film). As in spunbond filament curtain 10
Hit The spunbond filaments and meltblown fibers are mixed in mixing zone 90 to form fiber mixture 1
00 is formed. This fiber mixture 100 has a central plane G
Included in a merged jet or curtain 101 having a. The median plane G of the fiber mixture 100 is from the first median plane E of the meltblown fiber curtain 50,
Deviate by an angle of 140 to position G'or an angle of 15
It is possible to shift to position G ″ by shifting by 0. Angles 140, 15
0 can range from 0 to 30 degrees. The integrated spunbond filaments and meltblown fibers are then deposited on the porous forming surface in the same manner as described above.

A fifth device according to the present invention is shown in FIG. The same reference numerals indicate the same components as those shown in FIGS. 1 to 4. The apparatus shown in FIG. 5 has the same features as the apparatus of FIG. 1 except that the fiberized pulp 201 is added to the spunbond filament curtain 10 by the Coanda surface 200. The fibers of these fiberized pulps are carried by an air stream and at a point above the mixing zone 90 where the spunbond filaments and meltblown fibers are mixed, the spunbond filament curtain 1
It is thrown into 0.

A nonwoven web having at least one layer containing a mixture of spunbond filaments and meltblown fibers formed using the present invention was formed and tested according to the following cases. These cases show the various advantages possible with the present invention.

[Case 1 ... Symmetrical device] In this sample, as shown in FIG.
An apparatus was used in which two meltblown sources were placed symmetrically on either side of a bundle or curtain formed by filaments. The specific locations of the meltblown (MB) die tips 31 and 41, the exit 19 of the spunbond tensioner 20, and the porosity forming surface 110 used in this sample are as shown in Table 7.

Table 7 Position Value Forming height (A) 17 inches Distance from tip 31 to SB filament curtain (B) 7 inches Distance from tip 41 to SB filament curtain (C) 7 inches Formed from tips 31 and 41 Distance to surface (J, H) 11 inches Angle of tips 31, 41 (70, 80) 45 degrees

In forming the nonwoven web of the present invention, Exxon Chemical Corpora is used.
Spunbond filaments were made from polypropylene (PP) sold by Tion under the name "PD-3445". Extruded molten polypropylene at 400 degrees Fahrenheit at 0.45 g / min per capillary (GHM) through a spinning plate consisting of an array of uniformly spaced 0.6 mm diameter capillaries. It was Sufficient force to trickle the fibers was applied to bring the final diameter of the spunbond filaments to 20-30 microns.

Meltblown fibers are, for example, Himo
nt USA formed from molten polypropylene sold under the name "PF-015". The molten polypropylene was extruded at 425 degrees Fahrenheit through the meltblown tip at a rate of 0.44 pounds of polymer per inch of die tip length (PIH) per hour. The trickling force on the extruded polymer is varied by controlling the volumetric flow rate of heated air (heated to 550 to 600 degrees F) that is impinged on the molten polypropylene extruded through a capillary at the die tip. Let The diameter of the meltblown fibers formed is 4 to under certain conditions.
6 microns, and under other conditions 8-12 microns.

The meltblown fibers from the meltblowing die tips 31, 41 are meltblown by an expanding and slowing air jet, which is used to trickle the meltblown fibers in the molten state. The spunbond filaments were oriented in the fiber curtain and bonded with the spunbond filaments at a height of about 4 inches above the forming surface.
This spunbond filament also expands and
A decelerating air jet, initially used for trickling, is directed into the forming surface in the spunbond filament curtain. Mixing these fiber curtains carrying each fiber above the forming surface distributes the meltblown fibers to the spunbond filaments in the combined curtain, which in turn forms a porous formation. Sent to the surface.

The porosity-forming surface allows the air of the bonded fiber curtain to pass through it while collecting the mixed fibers into a nonwoven web. A vacuum source (negative pressure) is provided below the forming surface to facilitate the deposition of these fibers on the porous forming surface. The vacuum source allows air to be passed through the porous forming surface at a rate of 2000 to 3000 feet / minute. The composition ratio of fibers in the nonwoven web is about 30 for meltblown fibers.
%, Spunbond filaments are about 70%. The basis weight was low, 7.3 grams / square meter. The basis weight diameter indicates dimensional stability. The frictional force between the meltblown fibers and the spunbond filaments within the nonwoven web can prevent necking of the nonwoven web during stretching in the machine direction or unwinding.

[Case 2 ... Asymmetrical device] In this sample, as shown in FIG.
B) A device was used in which two sources of meltblown were placed asymmetrically on either side of the bundle or curtain formed by the filaments. The meltblown die tip 31 is located upstream of the spunbond tensioner 20 (relative to the direction of motion of the forming surface) and is angled to concentrate the meltblown fibers toward the outer surface of the finished nonwoven web. It was The meltblown die tip 41 (downstream meltblown tip) was positioned to fully integrate the meltblown fibers into the spunbond filaments. Melt blown (MB) die tips 31 and 41 used in this sample, exit 1 of spunbond tensioner 20
9. The specific position of the porous forming surface 110 is as shown in Table 8.

Table 8 Position Value Forming height (A) 14 inches Distance from tip 31 to SB filament curtain (B) Approximately 5.5 inches Distance from tip 41 to SB filament curtain (C) Approximately 4 inches Tip 31 To the forming surface (J) about 9 inches tip 31 angle (70) 30 degrees or less Distance from tip 41 to forming surface (H) about 11 inches tip 41 angle (80) 45 degrees

The spunbond filament is case 1 except that a spinning plate with trilobal capillaries is used.
Was formed in the same manner as. The equivalent diameter of the trilobal spunbond filament was 20-30 microns.

A polyethylene mixture was used to form the meltblown fibers. This mixture has a very low molecular weight polyethylene NA601 (Quantum C
chemicals products) and Aspun® 6
814 and / or 6806 (Dow Chemical
as product) in equal weight. The extrusion conditions were the same as in Case 1. The force used to trickle the fibers used to form the meltblown fibers was controlled by the volumetric flow rate of air flowing through the meltblown die tip to create a combination of fibers of various sizes. Tensile force is melt blowing die 3030,
Hold constant for both 40 to form meltblown fibers with a diameter of 5 microns or less, 5-8 microns, about 8 microns. Further, this tensile force is changed between the tips of the melt blown, and the melt blowing die 30 has a diameter of about 8 mm.
Melt blowing die 40 to form micron fibers
Was designed to form fibers with a diameter of 5 microns or less.

In the present composite nonwoven web, polyethylene meltblown fibers account for 35-50% (wt%) (the amount is evenly divided between the meltblowing dies 30 and 40) with the remainder being It was a trilobal polypropylene spunbond filament. The basis weight was 20-60 grams / square meter (depending on the speed of the porosity forming surface).

[Case 3 ... One-sided feeding device] In this sample, as shown in FIG. 3, one-sided feeding in which one melt-blown source is arranged on one side of a bundle formed by spunbond (SB) filaments, that is, a curtain The device was used. The meltblown die tip 31 is located downstream of the spunbond tensioner 20 (relative to the direction of motion of the forming surface) and is angled to concentrate the meltblown fibers toward one surface of the finished nonwoven web. It was Melt blown (MB) die tip 3 used in this sample
The specific locations of 1 and 41, the exit 19 of the spunbond tensioner 20, and the porosity forming surface 110 are as shown in Table 9.

Table 9 Position Value Forming height (A) 16 inches Distance from tip 31 to SB filament curtain (B) 6 to 6.5 inches Distance from tip 31 to forming surface (J) 9.5 to 13 Inch Angle of tip 31 (70) About 30-40 degrees

As in the previous case, the spunbond filaments were fused polypropylene (Exxon Corpo).
"PD-3445" of "Ration". This polypropylene was extruded at 485 degrees Fahrenheit at a rate of 0.80 g / min per capillary (GHM) through a spinning plate consisting of an array of equally spaced 0.6 mm diameter capillaries. It was The force to trickle the fibers is such that the final diameter of the spunbond filament is 20-30.
Sufficient force to make micron.

Meltblown fibers were made from fused polypropylene ("PF-015" from Himont USA). The polypropylene was extruded through a meltblown tip at a rate of 0.4 PIH at 475 degrees Fahrenheit. This extrusion rate results in a finished nonwoven web of about 16
% Meltblown fiber remained.

The force of the fiber trickling used to make the meltblown fibers is the heated air (450 Fahrenheit 450 ° F) which strikes the molten polypropylene extruded through the capillary at the tip of the die.
It is varied by controlling the volumetric flow rate (which is heated to ~ 575 degrees). The diameter of the meltblown fibers trickle when the volumetric air flow was high was 5-10 microns. The diameter of the meltblown fibers trickle when the volumetric flow rate of air was low was 20-30 microns.

[Case 4 ... One-sided Supply Device Having Curved Spunbond Exit] Using the device shown in FIG. 4, in the same manner as the device shown in Case 3 (the device shown in FIG. 3),
Both spunbond filaments and meltblown fibers were made. The difference from Case 3 is that the spunbond filament makes an angle with the porosity forming surface,
The point at which the meltblown fibers are perpendicular to the porosity-forming surface. In practice, the relative position of the spunbond filaments and the meltblown fibers at the start is Case 3
And the positions are opposite to those shown in FIG. Thus, the advantages of changing the relative position of each other are:
It is easier to position the meltblowing die tip. By placing a Coanda type curvilinear section at the exit of the spunbond tensioning device, the initial orientation of the spunbond filaments can be changed from a conventional right angle direction to an angle of about 20 degrees with respect to the porosity forming surface. Table 10 shows the specific positions of the tip of the melt-blowing die, the exit of the spunbond tensioning device, and the surface for forming the porosity used in this sample.

Table 10 Position Value Forming height (K) 1 to 10 inches Distance from tip 31 to SB filament curtain (B) 3.5 inches Distance from tip 31 to forming surface (A) 4.5 to 13 .5 inch tip 31 angle (70) 82.5 degrees

[Case 5 ... Comparison of spunbond, meltblown and unbonded polypropylene of the present invention at 15 grams / square meter] Symmetrical type device (Case 1
And the equipment shown in FIG. 1) was used to make unbonded polypropylene webs according to the parameters shown in Table 11.

Table 11 Position Value Forming height (A) 20 inches Distance from tip 31 to SB filament curtain (B) 5 inches Distance from tip 41 to SB filament curtain (C) 5 inches Formed from tips 31 and 41 Distance to surface (J, H) 13 inches Tip angles 31, 41 (70, 80) Approx. 60 degrees

In forming the spunbond filaments, 0.42 ghm was extruded at 450-475 degrees Fahrenheit through a spinning plate consisting of an array of equally spaced 0.6 mm diameter capillaries. A trickling force was applied to molten polypropylene (PD-3445). This trickling force was large enough to bring the final diameter of the spunbond filaments to 20-30 microns.

In forming meltblown fibers, a trickling force is applied to the molten polypropylene (PF-015) extruded through the meltblown die tip at a rate of 0.44 PIH at 450-500 degrees Fahrenheit. Let This trickling force is due to the heated air (55 degrees Fahrenheit) that strikes the molten polypropylene extruded through the capillary at the tip of the die.
It is varied by controlling the volumetric flow rate (heated to 0-600 degrees).

About 75% spunbond filaments and 2
A non-woven web of 5% meltblown fibers (Sample A) was subjected to various basis weights (about 15, 30, 40, 80 grams / gram) depending on the velocity of the porosity-forming surface.
It was wound into a roll. For the data presented in this case, the basis weight is 14-1
It was 6 grams / square meter.

A nonwoven web of 100% spunbond filaments (Sample B) was made under the same conditions as the Sample A web. However, the conditions of Sample A were that the polymer was not extruded through the melt-blowing die, spunbond filaments were accumulated on the carrier sheet, and the basis weight was adjusted by adjusting the speed of the porous formation surface. The difference is that it is set to 10 grams / square meter.

A nonwoven web of 100% meltblown fibers (Sample C) was made under the same conditions as the sample A web. However, the conditions for Sample A were that the polymer was not extruded through a spunbond spinning plate, the velocity of the porosity forming surface was adjusted to a basis weight of about 8 and 16 grams / square meter,
Are different.

These three types of unbonded, uncompacted webs were cut into 1 inch × 4 inch samples and 4
The inch-long sides were aligned in the machine direction (the direction in which the web was wound into a roll). These samples were subjected to Method 5102 Federal Test Method Standard 19 using a constant elongation tensile tester.
1A and ASTM standards D1117-6 and D1682
The cut strip tensile and% elongation values in the machine direction were tested according to the procedure defined in. The average value of the tensile value and the elongation value at the time of peak load (the value obtained by conducting at least 8 tests for each sample) was 15 g /
The basic weight of square meters was standardized, and the data shown in Table 12 were obtained.

Table 12 Unbonded Samples 1 inch Machine Direction Tensile Value% Elongation Value (grams / square meter) Sample A (75% SB / 25% MB) 1687 ± 440 92 ± 15 Sample B (100% PPSB) 1288 ± 460 233 ± 20 Sample C (100% PPMB) 812 ± 135 51 ± 3

Incorporation of meltblown fibers into spunbond filaments resulted in a significant reduction in% elongation values as compared to the 100% polypropylene spunbond web (Sample B), as shown by the web. The degree of coupling has been greatly improved.

[Case 6 ... Comparison of unbonded web consisting of 100% polyethylene spunbond filament, 100% polypropylene meltblown fiber, polyethylene spunbond filament, polypropylene meltblown fiber at 40 grams / square meter] Polyethylene (PE) span An unbonded web according to the invention consisting of bond filaments and polypropylene meltblown fibers was formed in a symmetric device using the parameters shown in Case 5 (FIG. 1). When forming a polyethylene spunbond filament, the trickling force is the melted polyethylene (Dow Chemical's Aspun 681).
1A) and about 0.6 gh through a spinning plate consisting of an array of equally spaced 0.6 mm diameter capillaries.
Extruded at a temperature of 400 degrees Fahrenheit at a rate of m. The trickle was large enough to bring the final diameter of the spunbond filaments to 20-30 microns.

When forming meltblown fibers, the trickling force is melt polypropylene (Himont PF01).
5). This molten polypropylene is
Ratio of 0.44 PIH (to about 50% meltblown components) and 0.22 through the meltblown die tip
It was extruded at 450-500 degrees Fahrenheit with a proportion of PIH (relative to about 30% meltblown component). This trickling force is due to the heated air (55 degrees Fahrenheit) that strikes the molten polypropylene extruded through the capillary at the tip of the die.
It is varied by controlling the volumetric flow rate (heated to 0-600 degrees). The meltblown fibers formed were 6 microns or less in diameter.

When the polypropylene meltblown extrusion rate was about 0.44 PIH, the nonwoven web (Sample D) consisted of about 50% polyethylene spunbond filaments and 50% polypropylene meltblown fibers. This web (Sample D) varied in basis weight (about 3
0 and 50 grams / square meter), rolled up.

When the polypropylene meltblown extrusion rate was about 0.22 PIH, the nonwoven web (Sample E) consisted of about 70% polyethylene spunbond filaments and 30% polypropylene meltblown fibers. This web (Sample E) varied in basis weight (2) determined by the velocity of the porosity forming surface.
5, 40, 75 grams / square meter), wound into a roll.

A non-woven web of 100% polyethylene spunbond filaments (Sample F) was laminated under the same conditions as described above, except for the following. The difference was that the polymer was not extruded through the meltblown tip, the polyethylene spunbond filaments were accumulated on the carrier sheet, and the speed of the porosity-forming surface was adjusted to a basis weight of about 40 grams / square meter. That is,

A non-woven web of 100% polypropylene meltblown fibers (Sample G) was laminated under the same conditions as the web of Sample D except for the following. The difference is that the polymer was not extruded through a spunbond spinning plate and the speed of the porosity forming surface was adjusted to a basis weight of about 47 grams / square meter.

These four types of non-bonded and non-compacted webs were cut into 3 inch × 7 inch samples, and the sides having a length of 7 inches were aligned in the machine direction (the direction in which the web was wound into a roll). These samples were tested for cut strip tensile and% elongation values in the same manner as Case 5. Of the data presented in Table 13, the average tensile values (tested at least 4 times for each sample) were standardized to a basis weight of 40 grams / square meter.

Table 13 Unbonded sample 3 inch strip MD% elongation value Tensile value (g / m ² ) Sample D (50% PESB / 50% PPMB) 1492 ± 270 123 ± 18 Sample E (70% PESB / 30% PPMB) ) 1065 ± 132 175 ± 20 Sample F (100% PESB) 2310 ± 1330 767 ± 202 Sample G (100% PPMB) 2083 ± 150 83 ± 15

Similar to the data listed in Case 5, by incorporating polypropylene meltblown fibers into polyethylene spunbond filaments, the% elongation values compared to unbonded 100% polyethylene spunbond web (Sample F). As can be seen from the significant decrease in the, the degree of web coupling has improved significantly.

[Case 7 ... No vacuum used during formation] 10
It is usually necessary to use a vacuum source when forming a web of 0% spunbond filaments. This is because the vacuum source pulls air through the forming surface (while leaving the spunbond filaments deposited on the upper surface of the forming surface) and also keeps the spunbond filaments in a fixed position relative to the forming surface. Without this vacuum source, air flow over the forming surface interferes with the deposited spunbond filaments.

Using the method according to the invention, this vacuum source can be made small or even completely eliminated. The meltblown fibers integrated with the spunbond filaments produce sufficient frictional force so that once the spunbond filaments are deposited on the porosity-forming surface, the spunbond filaments will not move. In order to show this state, polypropylene spunbond filaments and meltblown fibers were prepared and both were bonded in the same manner as in the case 1 (FIG. 1). However, no vacuum source was placed below the porosity-forming surface. Despite the absence of a vacuum source, the porosity-forming surface forms a barrier that shields both spunbond filaments and meltblown fibers from airflow that directs both fibers toward the forming surface. It was The meltblown fibers produced sufficient friction to prevent the spunbond filaments from being washed away by the air flowing over the forming surface.

[Case 8 ... Fiber Sizes in Unbonded Web and Bonded Web] The finished non-woven fabric depends on the size of the spunbond filament and the meltblown fiber (which means the effective surface area) bonded by the present invention. The strength properties of the web vary. Have an equal basis weight,
For nonwoven webs with the same ratio of spunbond filaments to meltblown fibers, the following was found. (1) The degree of bonding of non-compacted unbonded web is not affected by changes in the diameter of spunbond filaments (equivalent diameter for spunbond filaments of non-circular cross section), but the diameter of meltblown fibers changes And affected. (2) The tensile strength of the heating point bonded web is almost unchanged even if the size of the meltblown fiber changes.
It is affected when the size of the spunbond filament changes.

These observations are in agreement with the results for the 100% meltblown fabric for the bond strength of the web and the 100% spunbond fabric for the tensile strength of the heat bonded fabric (note that the bond strength of the spunbond web is For the uncompacted web).

In order to measure the effect of the fiber size on the strength, polypropylene spunbond filaments and meltblown fibers were prepared, and Case 1 (FIG. 1) was prepared.
Both fibers were bonded into a non-woven web according to the conditions shown in (1). In addition, the nonwoven web was extruded and trickled under different conditions. The results are shown below.

A. Effect of Spunbond Fiber Diameter on Tensile Strength of Unbonded Strip 0.42 g polypropylene spunbond filament
extruded at hm and trickled under three different conditions, about 30-35 microns (Sample H), 22-30 microns (Sample I), 15-22 microns (Sample J)
A fiber having a diameter of In addition, polypropylene meltblown fibers were extruded with 0.485 PIH to maintain a constant trickling force to form fibers having a diameter of 5 to 8 microns. Generalized tensile strength values at peak load measured on 1 inch x 4 inch strips (cut in the machine direction) and compared to average values at 45 grams / square meter (8 or more tests) I was able to do it. Table 14 shows the values of tensile strength. The fiber distribution was about 70% spunbond filaments and 30% meltblown fibers. Considering the range of each test value, there is no apparent difference between the strength or degree of bonding of each unbonded web, as reflected in the standard deviation (±).

Table 14 Sample MD Strip MD% (SB Diameter) Tensile Strength (gms) Elongation Sample H (30-35 micron) 1815 ± 370 171 ± 30 Sample I (22-30 micron) 1930 ± 173 144 ± 35 Sample J (15-22 microns) 2236 ± 122 130 ± 23

B. Effect of meltblown fiber diameter on tensile of unbonded strip 0.42 g polypropylene spunbond filament
Extruded at hm, made into a trickle under specified conditions, about 15-2
A fiber with a diameter of 2 microns was made. Further, polypropylene meltblown fibers were extruded with 0.243 PIH and the trickling force was changed to prepare a sample of fiber having a diameter of 5 to 8 microns (Sample K) and a sample having a diameter of 5 microns or less (Sample L). .. 1 inch x 4
The tensile load values at peak load measured on inch strips (machined) were generalized for basis weight to allow comparison of average values at 40 grams / square meter (8 or more tests). I did it. The fiber distribution is about 8 for spunbond filaments.
0% and 20% meltblown fiber. As shown in Table 15, there is a significant difference in the tensile strength value at the time of peak load, but there is almost no difference in the% elongation value indicating the degree of web bonding.

Table 15 Sample MD Strip MD% (MB Diameter) Tensile Strength (gms) Elongation Sample K (5-8 microns) 2233 ± 413 90 ± 8 Sample L (5 microns or less) 4318 ± 361 91 ± 12

C. Effect of Spunbond Filament Diameter and Meltblown Fiber Diameter on Bonded Web The unbonded web used to demonstrate the effect of fiber diameter changes on the strength properties of the unbonded web (Samples H, J,
K, L) are heat-treated by using a steel roll having a pattern formed on the surface (bonding area is about 15% and the number of points is about 300 per square inch) and a smooth anvil roll. It was a point combination. Bonding parameters are: surface temperature of 260 degrees Fahrenheit, bonding speed of 10 ft / min, load between calender rolls of 2
It was 5 pounds per square inch. The binding fabric is a tester (I
The strengths of both bonded and unbonded webs were measured according to the Grab Tensile Test Method (Method 5100, Federal Test Method Standard 191A) as they exhibited strengths above the upper limit of nstrn load cells). These averages (8 tests or more, standard deviation up to ± 20%) were generalized to a basis weight of 45 grams / square meter for direct comparison. The average values of these are shown in Table 16.

Table 16 Sample MD Grab Tensile (lbs) MD% Elongation Ratio & Diameter (microns) Unbonded Bonded Unbonded Bonded Sample H 70% PPSB (30-35) 9.3 28.3 110 33 -30% PPMB ( 5-8) Sample J 70% PPSB (15-22) 8.3 35.8 75 36 -30% PPMB (5-8) Sample K 80% PPSB (15-22) 9.1 38.5 110 35- 20% PPMB (5-8) Sample L 80% PPSB (15-22) 23.1 44.0 130 41 -20% PPMB (5 or less)

What can be said from these values is that in the non-bonded state, the size of the meltblown fibers most affects the strength of the web. In the bonded state, it is the size and percentage of spunbond filaments that have the greatest impact on web strength.

[Case 9: 95% spunbond and 5%
Melt blown: lower limit of melt blown fiber content]
Nonwoven webs in most of the previous examples have a spunbond filament to meltblown fiber ratio of 80:
It was 20 to 50:50, but in this case a minimum of 5% meltblown fibers were incorporated into the spunbond filaments. Inclusion of this minimum proportion of meltblown fiber pulls the uncompacted web away from the porosity-forming surface and unsupports a distance of 4 feet to the heated point-bonded calender (2 stacks) or wraps. It was sufficient to carry a distance of 10 feet to the catcher. Using the equipment and polypropylene resin described in Case 1 (FIG. 1) and the extrusion conditions shown in Table 17, 5% meltblown fiber and 95% spunbond filament (the cross-sectional shape of this spunbond filament is 50 % Of "H" and 50% of "X") to form a 27 gram / square meter web. The fiber sizes shown in Table 17 represent equivalent values for fibers of circular cross section.

Table 17 Types of fibers Size (microns) Extrusion conditions PPSB 22-28 430-50 degrees Fahrenheit, 0.80 ghm PPMB 5-8 430 degrees Fahrenheit, 0.33 PIH

Non-compacted and unbonded MDGrab for a 3 ″ × 7 ″ sample cut from a web having a basis weight of 27 grams / square meter.
Tensile values (at peak load) were averaged at 1.25 pounds.

[Case 10 ... Method for Improving Friction Entanglement] The frictional force generated by the presence of meltblown fibers dispersed in a large amount of spunbond web (compared to 100% spunbond web) is non-woven. It can be improved by confounding the web underwater. For example, a method of entanglement by exposing a nonwoven web to a small jet of high pressure water is described in US Pat. No. 3,485,706.
No. 4,950,531. Underwater entanglement increases the frequency of entanglement between spunbond filaments and meltblown fibers. With increasing degree of physical entanglement, underwater entangled webs made according to the present invention will be similar to those made by point bonding if the fiber size (diameter) and content (%) of the web are appropriate. Has a strength close to, and sometimes greater than, the web strength (determined by peak load).

To demonstrate this improvement, polypropylene spunbond filaments and polypropylene meltblown fibers were made according to the conditions shown in Case 1 (FIG. 1). However, the conditions for making the meltblown fibers finer were adjusted so that the fiber diameters were 5 to 8 microns (Sample M) and 5 microns or less (Sample N).

The samples used to measure the effect of the degree of fiber entanglement improved by the underwater entanglement method are shown in Table 18.

Table 18 Sample MB Fiber Diameter Basis Weight (micron) (g / m ² ) Sample M 5-843 (40% MB / 60% Trilobal SB) Sample N 5 or less 43 (32% MB / 68%) Trilobal SB)

After underwater entanglement, it was measured that the MD strip tensile strength was improved by 15 to 28% and 55% (strip tensile) for each of the samples M and N. The conditions used for underwater confounding are 4/80 aperture strip, 100
Water jet pressure of 0-1200 pounds per square inch, 2-3 jet passes per side, 25 fpm.

The difference in strength between the two samples M and N both before and after underwater entanglement was due to the size of the meltblown fibers, rather than the difference in spunbond / meltblown ratio, as shown in Table 19. is doing. This explains that the improvement in the degree of bonding of the web is due to the meltblown fibers in the spunbond filaments (that is, the smaller the fiber diameter, the more frictional bond points and the higher the strength). It is consistent with the same principle that

Table 19 Sample Basic Weight Tensile Strength (g / m ² ) MD (gms) CD (gms) Sample M (before) 43 1400 1200 Sample M (underwater entanglement) 43 1600 to 1800 1300 Sample N (before) 43 1800 ~ 1900 --- sample N (underwater confounding) 43 2755 2140

Even when the conditions under which these non-woven webs were entangled in water were changed, no significant difference in tensile properties was caused. For sample M, the water jet pressure was changed from 1000 to 1200 pounds per square inch, and the number of passes below the jet (2 to 3 times for each side)
The intensity values were almost the same even when was changed. The two conditions used to entangle sample N in water (twice or three on one side at a pressure of 1200 pounds per square inch).
No significant difference was found in the tensile value even by the time.

[Case 11 ... Thermal Point Coupling with Compaction and Thermal Point Coupling without Compaction]
In accordance with the present invention, the loft or bulk in a nonwoven web can be improved by not compacting the web prior to hot point bonding. Basic weight is 14-27 grams / square meter, 100%
The thickness of compacted and hot point calendered nonwoven webs (Samples O and Q) consisting of polypropylene spunbond filaments was measured using a Foam bulk tester. This testing machine was tested by Testing Machines Inc. Is manufactured by. The foam bulk tester has a support frame, a gauge capable of measuring up to 0.001 inch, and a moveable platen coupled to the gauge. Thickness was measured by placing the sample between the moving platen and the impermeable surface. This thickness is shown on the gauge. The force exerted by the moving platen coupled to the gauge is 1 gram weight per square centimeter (gmf / cm ² ).
Is.

Compaction of the non-woven webs (Samples O and Q) consisted of a spunbond filament supported by a porous surface between a smooth hard roll (ceramic coated steel) and a hardened rubber coated steel roll. It was done by passing it through a nip formed in between. Hot point calendering was performed with a patterned roll opposite the smooth anvil roll (each point has a square shape with 200 points per square inch and a total bond area of 20-25%). ).

Nonwoven webs (Samples P and R) were formed by the method shown in Case 6 using 70-80% polypropylene spunbond filaments and 30-20% polyethylene meltblown fibers. 14-2
These non-woven webs with a basis weight of 5 grams / square meter (Samples P and R) used the same pattern and anvil roll used to bond the 100% spunbond fibrous webs (Samples O and Q). do it,
Heat point bonded. We did not compact these webs. The thickness of these webs after hot point bonding are as shown in Table 20.

Table 20 Sample Basic Weight Bulk (g / m ² ) (inch) * Sample O 14 0.006 to 0.012 (100% PPSB compaction) Sample P 14 0.011 to 0.024 (to 75%) PPSB + to 25% PEMB) Sample Q 24 to 27 0.011 to 0.015 (100% PPSB compaction) Sample R 20 to 24 0.014 to 0.025 (to 75% PPSB + to 25% PEMB) * Bulk 3 times or more

In the range where the bulk measurements overlap, the uncompacted web has a higher bulk. The bulk overlapping area of spunbond and meltblown fibers having a basis weight of 14 to 20 to 24 grams / square meter indicates the maximum depth of the engraving pin.

[Case 12 ... Addition of Discontinuous, Individual Fibers] The property of binding other types of particles, especially short fibers, to spunbond filaments and meltblown fibers before they are deposited on the surface of the porous formation is fiber. It is proved by adding liquefied pulp. For the addition of fiberized pulp, the individual, discontinuous pulp fibers carried in the air stream were placed in a combined air stream carrying spunbond filaments and meltblown fibers.

An apparatus similar to that shown in FIG. 5 was used. The parameters for making spunbond filaments and meltblown fibers are as follows:
Same as case 1.

Table 21 Fiber Type Extrusion Conditions Trilobal SB Exxon's 3445PP, 0.35 ghm; ~ 20 microns to 430 degrees Fahrenheit Upstream SB Quantum's NA601PE, 1.3PIH; ~ 5 microns to 400 degrees Fahrenheit MB MB Himont's PF015PP. .8 PIH; ~ 8 microns ~ 400 degrees Fahrenheit

The fiberized pulp is a CR-54 pulp sheet (Kimberry-ClarkCorporati).
4.5 PIH
At a rate of about 1/8 to 1/4 inch. These fibers were carried by an air stream and were directed between the upstream meltblown fiber source and the spunbond filament curtain via a curved metal sheet that acted as a Coanda surface. FIG. 5 shows this device. A curtain of bonded fibers carrying spunbond filaments, meltblown fibers and pulp fibers was directed onto the porosity-forming surface and then rolled. Then
Thermal point bonding was performed to increase the strength of the nonwoven.

Nonwovens obtained by combining fibrous pulp fibers with spunbond filaments and meltblown fibers as described above exhibited the following properties. (1) Due to the presence of pulp fiber, it exhibited absorbability to an aqueous solution. (2) Since there are spunbond filaments (including those with and without thermal point bonding),
The strength before and after fluid saturation was shown. (3) Coform structure (for example, An
Capability to capture individual pulp fibers due to the presence of meltblown fibers as in US Pat. No. 4,100,324 to Derson et al.

[Case 13 ... Addition of Particles] In order to show the property of binding other types of particles, especially particles in a separated state, to spunbond filaments and meltblown fibers before being deposited on the porous surface, Superabsorbent particles (SAP) were added. The equipment and conditions used were those shown in Case 1. SAP (Dow Chemicals)
Manufactured by K.K., "1500P") was added from the upstream side of the spunbond filament curtain via the carrier air generated by the air jet carrying the spunbond filaments. These particles were entrained in a confluent air jet of spunbond filaments and meltblown fibers as they were directed toward the porosity-forming surface. The SAP was captured by the meltblown fibers, but if vibrated, S
AP was not fixed and was not completely contained inside the non-woven structure.

[Case 14 ... Polyethylene Spunbond Filament and Polypropylene Meltblown Fiber for Change in Touch and Acceleration in Hot Point Bonding] By selecting dissimilar polymers to form spunbond filaments and meltblown fibers, each polymer A nonwoven web exhibiting the properties of can be made. To what extent this non-woven web represents the properties of each polymer is
It depends on the content (%) of each fiber contained in the nonwoven web. The different polymers contained in each fiber (meltblown and spunbond) provide the tactile properties of the nonwoven web, ie, softness, stiffness, smoothness, and the like. The two-component nature of this nonwoven web also extends the scope and impact of subsequent heat treatments (eg, bonding, shrinking, etc.).

The nonwoven web, both unbonded and hot point bonded, provides greater drape (flexibility), lower friction and strength as compared to polypropylene spunbond filaments. Small polyethylene spunbond filaments are formed. Also, due to the difference in the melting properties of polyethylene and polypropylene, the problem during calendering (usually called "lapping") is the heat point under conditions (surface roll temperature 240 degrees Fahrenheit) that gives maximum bonded web strength. Occurs in bonded polyethylene spunbond filament webs. By binding polypropylene meltblown fibers according to the present invention, the unbonded web strength (bondability) is low and the problem of wrapping during calender rolls can be reduced to an acceptable range.

To demonstrate the effect of proper choice of polymer type on the degree of bonding of the unbonded web, -60% polyeletin spunbond filaments to -40% polyethylene meltblown fibers (Sample W) or -40%.
Of polypropylene meltblown fiber (Sample X) to form a nonwoven web having a basis weight of 20 to 45 grams / square meter. The device is case 1
It is the same as (Fig. 1), and the conditions for extrusion / trickling are shown in Table 2.
As shown in 2.

Table 22 Samples Fiber Polymers Extruded / Trenched Samples W Bilobal Aspun 0.65 ghm (Fahrenheit PESB (60%) 6811A 400 degrees), 20-25 micron PEMB (circular) (40%) 50% NA601 0 .12 PIH (each M & 50% Aspun B source) (450 to 6814 500 degrees Fahrenheit), 5 micron or less Sample X Bi-Lobal Aspun 0.65 ghm (Fahrenheit PESB (60%) 6811A 400 degrees), 20 to 25 micron PPMB PF- 015 0.12 PIH (each M (circular) (40%) B source) (450-500 degrees Fahrenheit), 5 microns or less

The difference in the degree of bonding between the webs is represented by the relative dimensional stability of the webs when wound into a roll. A sample W of a web consisting entirely of polyethylene fibers (both spunbond and meltblown) was too weak to be wound into rolls. The web has grown extremely. Sample X, which is a web of polyethylene spunbond filaments and polypropylene meltblown fibers, had much less elongation (extension) than Sample W during roll-up. It is shown that the polypropylene meltblown fibers (Sample X) included in the range of -30% changed the tactile properties of the web. In addition, the fact that the polypropylene meltblown fibers, which were rougher and harder than the polyethylene meltblown fibers, were contained in the sample X was also revealed in the drape, softness, and smoothness of the web.

A web (Sample Y) consisting of ~ 60% polyethylene (linear low density) spunbond filaments (circular cross section) and ~ 40% polypropylene meltblown fibers was applied to a 714 pattern roll (bonding area 15%, number of points 300). Surface temperature of 241 degrees Fahrenheit per square inch) and 2 degrees Fahrenheit on a smooth anvil roll.
Thermal point bonding at -20 FPM using a surface temperature of 34 degrees. In addition, a web (Sample Z) made of 100% polyethylene (linear low density) spunbond filaments was made. When Sample Z was made, pattern roll wrapping often occurred. On the contrary, in sample Y, lapping did not occur at all. Sample Y is a composite nonwoven web consisting of -60% polyethylene spunbond filaments and -40% polypropylene meltblown fibers.

[Case 15 ... Polypropylene Spunbond Filament and Polyethylene Meltblown Fiber for Heating Air Melting] When a nonwoven web is formed according to the present invention by using polymers having greatly different melting ranges, heating ventilation bonding or infrared bonding is used. And the like can be used. These bonding techniques allow low melting fibers to be combined with (relatively) high melting fibers.
This consists of the following steps. (1) exposing a web of fibers of different melting points to a temperature such that the low melting point fibers melt and bond at the points where they intersect the high melting point fibers, and then (2) between the high melting point and The web is cooled so that the bonded fusion zone located at the intersection solidifies.

This bonding method is such that upon bonding with a physical mixture of staple fibers (one of which is a bonding fiber),
Alternatively, it is the same as the method used for bonding with the bicomponent fiber. The difference from these webs lies in the initial state of the fibers making up the web, ie the bonded structure consisting of spunbond filaments and meltblown fibers.

For example, a nonwoven web (Sample AA) consists of polypropylene spunbond filaments and polyethylene meltblown fibers as shown in Case 11, where Case 11 contains about 75% spunbond filaments and melt. The difference is that the proportion of blown fibers is about 25%. Sample AA was heated in a heated air circulation oven for 10 minutes to 230 degrees Fahrenheit, which is above the melting point of the polyethylene meltblown fibers.

Sample A after bonding by air heating
The strength of A was compared to similar webs that were unbonded and heat point bonded. The conditions for forming the web are as follows. (1) The device was used in Case 1. (2) The polypropylene spunbond filament was used in Case 12, and was made into a stream with a diameter of 22 to 30 microns. (3) The polyethylene meltblown fiber was used for the case 12, and was made into a fine stream with a diameter of 5-8 microns.

MD elongation (%) and grab tensile strength at peak load (basic weight 3 for direct comparison)
(Standardized to 5 grams per square inch) is shown in Table 23. Standard deviation for those data is ± 1
Within the range of 5%. Thermal point bonding has a bond area of 1
5%, the number of points was about 20 fpm, and the pattern was 300 pieces / square inch. Ventilation connection is 99f
pm at 230-260 degrees Fahrenheit. The effect of the thermal point bond is clear from the fact that the grab tensile strength is significantly improved compared to the value of the non-bonded condition, and the effect of the heated draft bond is the% elongation value (± 15%).
(Which takes into account the standard deviation of).

Table 23 Bonding Method for Sample AA MD Grab Tensile Strength (lbs) MD Elongation (%) Unbonded 8.1 126 Thermal Poin with 714 Pattern at 230 ° F. 14.7 114 To Bonded at 230 ° F. Ventilation coupling 6.4 103 Ventilation coupling at 245 degrees Fahrenheit 9.7 102 Ventilation coupling at 260 degrees Fahrenheit 8.5 76

[Case 16 ... Glycol-modified polyester spunbond filament and polypropylene meltblown fiber for shrinkage] The method for changing the loft and basis weight of a nonwoven web when heat treating the nonwoven web is one type of fiber. Consists of selecting fibers from a variety of polymers, such that they are shrinkable and other types of fibers are non-shrinkable. This method makes it possible to create a large loft structure from a flat, low loft structure, and as the loft improves, other dimensions of the web (width, width,
The length or both) will change accordingly.

The sample is a nonwoven web (Sample BB) made from glycol modified polyester (PETG) spunbond filaments and polypropylene meltblown fibers. Sample BB has a basic weight of 5
At 4 grams / square meter, it consists of about 70% PETG spunbond filaments and about 30% polypropylene meltblown fibers. This sample BB was cut into a size of 1.5 inches x 1.5 inches,
It is soaked in 80-200 degrees) and loosened. The thermally labile PETG spunbond filaments of Sample BB changed the geometry of the meltblown fibers present in the web. The dimensions of the sample before and after immersion in hot water are shown in Table 24.

Table 24 Sample BB Front Back Width (inch) 1.5 0.5 Length (inch) 1.5 0.5 Foam bulk (inch) 0.048 0.095

The preferred structure for the types of shrinkable fibers that form meltblown fibers and spunbond filaments are those that are thermally stable.

[Case 17 ... Improving Appearance] When laminated and bonded with another non-woven fabric by some means, the unbonded web made according to the present invention improves strength with respect to spunbond filaments. At the same time, it also gives an appearance advantage. The improvement in strength due to the spunbond filaments present in the unbonded web made according to the present invention is the same as that obtained from point bonded fabrics made from 100% spunbond filaments. The visual advantage of the reinforcing web made according to the present invention is due to the absence of bond points. A hydroentangled laminate (Sample CC) was made to show these visual advantages.

The laminate (Sample CC) has a wet-formed pulp layer made according to the present invention and laminated to a nonwoven containing spunbond filaments. The nonwoven web was made according to Case 1 and rolled into a non-bonded state. The nonwoven web was then unwound from the roll onto the porosity forming wire. In addition, the forming wire passed under the paper forming headbox and a layer of wet formed pulp fibers was deposited on the nonwoven substrate.
The pulp fibers were wrapped around the spunbond filaments of the nonwoven web by a subsequent hydroentanglement process. This resulted in a laminate that was integrated with the majority of the wet-formed pulp fibers incorporated into the thickness of the nonwoven web by the force of the water jet (most pulp fibers were concentrated on one side). The remaining). The non-bonded nonwoven web made according to Case 1 had a basis weight of 14 and 20 grams / square meter. Final laminate is about 90 grams /
It had a basis weight of square meters.

Unlike spunbond reinforced substrates (or other non-wovens) that have thermal point bonds, the unbonded webs of the present invention have a visually unfavorable pattern (comparable to those formed by the hydraulic entanglement process). (Join point)
Does not have.

[Brief description of drawings]

1-5 are examples of apparatus for mixing spunbond filaments and meltblown fibers to form a nonwoven fibrous web that includes at least one layer having an integrated mixture of spunbond filaments and meltblown fibers. It is shown.

FIG. 1 is a schematic diagram of a symmetrical apparatus for combining spunbond filaments and meltblown fibers.

FIG. 2 is a schematic diagram of an asymmetric apparatus for combining spunbond filaments and meltblown fibers.

FIG. 3 is a schematic diagram of a single-sided feeding device for combining spunbond filaments and meltblown fibers.

FIG. 4 is a schematic illustration of a single-sided feeding device separate from FIG. 3 for combining spunbond filaments and meltblown fibers. This device uses a curved exit for spunbond filaments.

FIG. 5 is a schematic diagram of a symmetrical apparatus for combining spunbond filaments, meltblown fibers, and fiberized pulp using a Coanda surface.

[Explanation of symbols]

 10 Spunbond Filament Curtain 19 Exit 20 Spunbond Tensioner 21 Curved Part 30 Melt Blowing Die 31 Die Tip 40 Melt Blowing Die 41 Die Tip 50 Melt Blown Fiber Curtain 60 Melt Blown Fiber Curtain 90 Mixing Zone 100 Fiber Mixture 101 Curtain 110 Porosity Forming surface 120 Fiber web 130 Vacuum source 200 Coanda surface 201 Fiberized pulp

Front Page Continuation (72) Inventor Richard McFarlan Shane Georgia, USA 30136 Duluth East Meadow Drive 4401

Claims (18)

[Claims] 1. A non-woven web comprising at least one layer of a mixture, said mixture having a mean diameter of at least 6 microns and a mean birefringence number greater than 10 × 10 ⁻³ . And a second plurality of fibers having a diameter of 6 microns or less and a birefringence number of 10 × 10 ⁻³ or more, at least 50% (wt%) of the mixture being A non-woven web, characterized in that it is a plurality of filaments. 2. The nonwoven web of claim 1, wherein the first plurality of filaments is selected from the group consisting of polypropylene and linear low density polyethylene. 3. The nonwoven web of claim 1, wherein the second plurality of fibers is selected from the group consisting of polypropylene and linear low density polyethylene. 4. The mixture is at least 6 microns.
Diameter and 10x10 ^-3A third with a birefringence number of
The method further comprising a plurality of fibers.
The nonwoven web according to 1. 5. The nonwoven web of claim 4, wherein the third plurality of fibers is selected from the group consisting of polypropylene and linear low density polyethylene. 6. A method of forming a layer of a nonwoven web having a fiber mixture, comprising: (a) a first plurality having an average diameter of at least 6 microns and a birefringence number of 10 × 10 ⁻³ or more. Forming a second filament having a diameter of 6 microns or less and a birefringence number of 10 × 10 ⁻³ or more; and (c) the first step. A plurality of filaments and the second plurality of fibers,
Mixing such that the first plurality of filaments occupy at least 50% (wt%); and (d) depositing the mixture on a forming surface to form the layer,
A method consisting of. 7. The method of claim 1, wherein the first plurality of filaments is selected from the group consisting of polypropylene and linear low density polyethylene. 8. The method of claim 6, wherein the second plurality of fibers is selected from the group consisting of polypropylene and linear low density polyethylene. 9. A diameter of at least 6 microns and 10 ×
A third plurality of fibers having a birefringence number of 10 ⁻³ or less,
7. The method of claim 6, wherein the first plurality of filaments and the second plurality of fibers are mixed prior to depositing the mixture on the forming surface. 10. The method of claim 9, wherein the third plurality of fibers is selected from the group consisting of polyethylene and linear low density polyethylene. 11. A nonwoven web comprising at least one layer of a mixture, said mixture having an average diameter of at least 6 microns and an average birefringence number greater than 10 × 10 ⁻³ . A second filament having a diameter of 6 microns or less and a birefringence number of 10 × 10 ⁻³ or more; a diameter of at least 6 microns and a birefringence of 10 × 10 ⁻³ or less And a third plurality of fibers having a number, wherein at least 50% (wt%) of the mixture is the first plurality of filaments. 12. The nonwoven web of claim 11, wherein the first plurality of filaments is selected from the group consisting of polypropylene and linear low density polyethylene. 13. The nonwoven web of claim 11, wherein the second plurality of fibers is selected from the group consisting of polypropylene and linear low density polyethylene. 14. The nonwoven web of claim 11, wherein the third plurality of fibers is selected from the group consisting of polypropylene and linear low density polyethylene. 15. A method of forming a layer of a nonwoven web having a fiber mixture, comprising: (a) a first plurality having an average diameter of at least 6 microns and a birefringence number of 10 × 10 ⁻³ or more. And (b) forming a second plurality of fibers having a diameter of 6 microns or less and a birefringence number of 10 × 10 ⁻³ or more, and (c) at least 6 microns. Forming a third plurality of fibers having a diameter and a birefringence number of 10 × 10 ⁻³ or less;
(D) Mixing the first plurality of filaments, the second plurality of fibers, and the third plurality of fibers so that the first plurality of filaments occupy at least 50% (wt%). And (d) depositing the mixture on a forming surface to form the layer. 16. The method of claim 15, wherein the first plurality of filaments is selected from the group consisting of polypropylene and linear low density polyethylene. 17. The method of claim 15, wherein the second plurality of fibers is selected from the group consisting of polypropylene and linear low density polyethylene. 18. The method of claim 15, wherein the third plurality of fibers is selected from the group consisting of polyethylene and linear low density polyethylene.