JPH0321648B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a heterocomponent filament that can be bonded by heating and a method for producing the same.

[Prior Art] It is already well known to use heterogeneous filaments that can be bonded together by heating to produce nonwoven fabrics. Typically, such heterogeneous filaments are formed from two thermoplastic materials arranged in a side-by-side or sheath-to-core relationship. One of these thermoplastic materials, the so-called adhesive component, has a considerably lower melting point than the other thermoplastic material contained in the filament;
It is selected from those that exhibit adhesive properties and bond with other fibers in the nonwoven fabric when heated and then cooled. Such adhesion occurs between the dissimilar filaments or, if the nonwoven fabric includes conventional non-adhesive filaments, between the dissimilar filaments and the non-adhesive filaments. The other component in the heterogeneous filament functions as a structural or shape-retaining material for the fibers.

Heterogeneous filaments were primarily developed to produce lightweight nonwoven fabrics, that is, nonwoven fabrics with a relatively low weight per unit area, but currently they are not used much for this purpose due to various drawbacks. It has not yet been achieved. Among these drawbacks, the most problematic ones are excessive shrinkage during heat bonding, resulting in uneven density and thickness of the nonwoven fabric, and insufficient bonding strength between fibers. The tensile strength of the resulting nonwoven fabric may be insufficient, or the resulting nonwoven fabric may lack desirable properties traditionally possessed by textiles, such as drapability, resilience, or bulkiness, i.e., a fluffy feel. This is the missing point.

Of course, various attempts have been made to eliminate such drawbacks. 23-31 of “Nonwovens Industry” magazine published in May 1981.
Mr. Tomioka's paper published on the page includes the two-component material "ES" commercially available from Chitsuso Corporation.
The characteristics of the fiber are described. This fiber, consisting of polyethylene and polypropylene arranged in a so-called modified "side-by-side" configuration (in fact, the sheath and core have a highly eccentric arrangement), is disclosed in U.S. Pat. No. 4,189,338 (inventors: Ejima et al.; It appears to be the same as that disclosed by Chitsuso Corporation (patent holder: Chitsuso Co., Ltd.). Among the factors contributing to this fiber's features, Mr. Tomioka detailed the fact that the fiber undergoes relatively low heat shrinkage during the bonding process, which allows for uniform density and thickness. He stated that he noticed that a nonwoven fabric with excellent elasticity, fluffy feel, and good drapability could be obtained.

Although the fiber introduced by Tomioka is certainly a significant improvement over the state of the art of previous fibers that can be bonded by heating, this new fiber itself still has some deficiencies. Don't criticize something that is enough. As an example, although the degree of heat shrinkage of this new fiber is certainly lower than that of previous fibers, it has been confirmed that it still causes considerable heat shrinkage and that the degree of heat shrinkage is too large. In addition, attempts to eliminate heat shrinkage are theoretically good attempts from the standpoint of improving the quality of heat-adhesive fibers, but it seems unlikely that such methods will have much of an improvement effect. .

Although heat shrinkage itself may be undesirable for thermobondable fibers, the generation of shrinkage forces within the nonwoven after the interfilament bond is formed is believed to be desirable in practice. The shrinkage force that occurs at this point does not actually shrink the nonwoven fabric, but rather has built-in forces that improve the properties of the resulting nonwoven fabric, such as bulkiness, resilience, drapability, or hand. It seems more reasonable to assume that it remains in the nonwoven fabric as tension.

[Problems to be Solved by the Invention] An object of the present invention is to provide a heterocomponent filament useful for producing nonwoven fabrics, particularly light and medium weight nonwoven fabrics, and a method for producing the same.

A more specific objective of the present invention is to exhibit minimal thermal shrinkage during thermal bonding, but to enhance tensile strength and improve recovery, drapability, bulkiness, texture, etc. after thermal bonding. The object of the present invention is to provide a heterogeneous filament for the production of improved nonwoven fabrics.

A more specific application object of the present invention is to generate less shrinkage force or shrinkage before or during heat bonding, but to generate significant shrinkage force after the interfilament bonds are formed within the nonwoven. The purpose of the present invention is to provide a heterogeneous filament.

A further object of the invention is to provide a manufacturing method which makes it possible to adjust or modify the thermal properties of the heterogeneous filament obtained to suit individual requirements.

A final objective of the present invention is to provide a heterogeneous filament that allows nonwoven fabrics with improved properties to be produced efficiently and with less energy consumption.

[Means for Solving the Problems] That is, the first aspect of the present invention is a method comprising an adhesive component for forming an inter-filament bond when heated and subsequently cooled, and another component consisting of polyester. 0.01 only after resolidification of said adhesive component upon application of sufficient heating to melt said adhesive component and subsequent cooling.
g/denier (0.0091 g/dtex); an adhesive component for forming an interfilament bond upon subsequent cooling and another component consisting of polyester, when heated sufficiently to melt said adhesive component and subsequently cooled. A heterogeneous component having a thermomechanical response characteristic such that a shrinkage force greater than about 0.01 g/denier (0.0091 g/dtex) occurs in the other component only after the adhesive component is resolidified. A method for producing a filament, the method comprising: (a) spinning a heterogeneous filament made of both of the above components; and (b) imparting the thermomechanical response properties of the heterogeneous filament spun in step (a). In order to cause
This method of producing a heterocomponent filament is characterized by comprising the step of performing conditioning heat treatment in which the method is heated at a predetermined temperature below the melting point of a low melting point component for at least a predetermined period of time.

In the present invention, it is preferable to use a thermoplastic having a melting point at least 15°C lower than that of polyester as the adhesive component, and the adhesive component and another component consisting of polyester are used in a side-by-side relationship, that is, in parallel. Although it is possible to arrange them, it is preferred that they are arranged in a sheath-core relationship, with the polyester occupying the core portion.
After completing the spinning, drawing and winding steps in a conventional manner, the heterogeneous filament produced according to the invention is subjected to a conditioning heat treatment step. In this step, the filament is heated at a temperature below the melting point of the adhesive component, i.e., a low melting point component, for at least a predetermined period of time, sufficient to melt the adhesive component by modifying the thermal response of the filament. Upon heating followed by cooling, shrinkage forces greater than about 0.01 grams per denier (0.0091 g/dtex) are created in the polyester component only after resolidification of the adhesive component. The temperature at which the above shrinkage force occurs is called the "conditioned response temperature", which describes the conditions such as temperature and time that must be used to suitably adjust the fiber properties in the above method. It is impossible to define it exactly. As is clear from the explanation below, the conditions required for heating adjustment are determined by the thermal history of the individual fibers used and the individual adhesive components used, and the conditions required for heating adjustment are determined by the thermal history of the individual fibers used and the individual adhesive components used. Determined by temperature etc.

For dissimilar filaments made in accordance with the present invention, interfilament bonds have been observed to form between the dissimilar filaments before contraction forces occur. As detailed below, this property increases the strength of the interfilament bonds within the nonwoven fabric, further improving the drape, hand, bulkiness, or recovery properties of the nonwoven fabric.

As a result of achieving the objects of the present invention, nonwoven fabrics can be produced from the heterogeneous filaments of the present invention, in which case relatively gentle production and processing conditions can be chosen.

FIG. 1 shows a microscopic photograph of a nonwoven fabric produced from the heterogeneous filament (hereinafter simply referred to as fiber) of the present invention. When producing such nonwoven fabrics, the fibers are formed into a web, heated sufficiently to perform the function of the adhesive component, and then formed by the component melted at the intersections between the individual filaments. The bond 2 is cooled to solidify.

The thermomechanical response properties of fibers subjected to such heating and cooling treatments are expected to affect not only the properties of the bond formed but also the overall properties of the resulting nonwoven fabric. It is desirable to characterize these fibers by several thermomechanical analysis methods. Therefore, the fibers of the present invention were tested using a technique known as thermal stress testing (TSA). In this test,
The sample is held for a fixed length while changing the temperature, and the tension generated in the sample is recorded at fixed time intervals. This TSA law is based on the “Textile
Published on page 732 of “Research Journal”
It is explained in the paper by Buchanan and Hardegree. However, to the best of the present inventors' knowledge, the above authors and others who have published research results using this method have limited their studies to only the response of samples at elevated temperatures. On the contrary, during the research process of the present invention, the same attention was paid to the response of the sample upon lowering the temperature. This suggests that it is necessary to investigate the reaction of the sample when the temperature is lowered in order to appropriately reproduce the heat treatment applied to the nonwoven fabric constituent materials during the nonwoven fabric manufacturing process as described above. This is because the.

In preparing samples for this study, 100 to 500
To make a bundle with an equivalent denier in the range of
The appropriate number of independent fibers were grouped together. The compilation method used was Perkin-Elmer Co. of Norwalk, Conn., USA, using its TMS-1.
It was designed for use in thermomechanical analyzers. A standard pretension of 0.02 g/denier was chosen to increase uniformity of test conditions. In all tests, the temperature was increased at a rate of approximately 15°C/min.

FIG. 2 shows representative results of TSA testing of fibers of the invention. In this case, high-density polyethylene-polyester was used as the fiber of the present invention, and high-density polyethylene-polypropylene was used as the fiber according to the prior art. The tension of the sample was plotted on the vertical axis, ie, the Y axis, and the sample temperature was plotted on the horizontal axis, ie, the X axis. The arrows on the curves show how the changes progressed over time. First, a 200 denier sample is used and 4 grams of pretension is applied at room temperature. Keep the length of the sample constant during subsequent tests. It can be seen that as the temperature increases, this pretension decreases to almost zero in each case due to the strain relaxation and thermal expansion that the samples normally exhibit. However, after the initially applied pretension has relaxed, the tested samples exhibit a completely different thermal stress behavior. That is, the prior art specimen, high-density polyethylene-polypropylene, exhibits an increase in tension as the temperature increases to 150°C, and more importantly, a rapid increase in tension as the specimen cools. . It should be kept in mind that this tension build-up upon heating and the rapid increase in tension upon subsequent cooling is considered undesirable for the production of nonwoven fabrics. Contrary to the above thermal stress behavior of the prior art samples, the inventive samples ensure that when there are fibers in the web, these interfiber bonds do not exert shrinkage forces on newly formed interfiber bonds. There is no increase in tension during either the heating or cooling stages until the fibers forming the bundle have cooled sufficiently to solidify.

It is clear that the temperature at which tension begins to develop when the sample is cooled is the most important point in distinguishing the fibers of the present invention from those of the prior art. As a means of determining this temperature, we defined the onset of tension build-up as the temperature at which the tension exceeds a threshold of 0.01 grams/denier based on the denier of the shape-retaining component. This value was chosen as the lowest value that can be used in practice, but is still clearly discernible, even taking into account errors from the measuring equipment in the recorded tension values. As an example,
As mentioned above, 300 samples containing half and half of both components were prepared for testing.
The shape retention fiber formed into a denier bundle is only 150 denier, so the tension threshold for this sample is 1.5 grams.

As a means of illustrating how fibers with such desirable cooling curves can be produced, the results were obtained when fibers produced under identical spinning and drawing conditions were subjected to several different condensation treatments. The results are shown in Figure 3. Table 1 below shows the conditioning treatment conditions used.
Figure 3 shows together the TSA curves of several different samples, each heat treated under unique heat treatment conditions.

Table 1 Sample conditioning treatment conditions A: No treatment B: 90℃, 3 minutes C: 100℃, 3 minutes D: 110℃, 3 minutes E: 120℃, 3 minutes F: 130℃, 3 minutes Similarly, the tension was taken on the vertical axis, but
The scale in Figure 3 differs from the scale in Figure 2 in that the first 6 grams of pretension is plotted at the bottom left of the graph. All of these tests show the same pattern of decreasing tension as the temperature is increased at the beginning of the test. Beyond this initial heating stage, differences between samples become apparent.

In the case of sample A, which was not subjected to heat treatment after stretching,
When the temperature rises to about 100°C, an accumulation of tension is observed,
It can be seen that this tension reaches a maximum value at about 120°C and decreases to a minimum value (but not zero) at 140°C. This is a characteristic of polyester and is
It is also described in the paper by Buchanan and Hardegree. Upon cooling, this sample initially increases in tension, and a rapid increase in tension is observed below 130°C.
In fact, this sample has the above-mentioned properties in the high-temperature range.
It is impossible to indicate a tension that exceeds a threshold of 0.01 grams/denier, and ultimately a starting value for tension accumulation.

For sample B treated at 90° C. for 3 minutes, the tension decreased considerably from the initial maximum value during the heating process of the curve, and the tension accumulation curve during cooling was only slightly lower than that of sample A.

In the case of samples C, D, and E, no tension is developed during heating, and only appreciable tension is developed upon cooling well below the resolidification temperature of the sheathing material. These samples are representative of fibers made according to the present invention.

Sample F shows that excessive heat treatment completely eliminates even the tendency to generate tension upon cooling.

Theoretically, there are many aspects that still need to be clarified, but in the nonwoven fabric made of fibers produced according to the present invention, the strength of the bond between filaments, such as the cross-linked portion 2 in Fig. 1, is the same as that of the fibers. Even if the fiber is heated to melt the sheath and then cooled to solidify the bond between the filaments, there will be no formation within the fiber until the temperature falls below the solidification temperature range of the sheath and such bond actually forms. It is believed to be strengthened by the fact that little or no tension is created. In other words, when using the fibers of the present invention, bonds are expected to form in the absence of stress, which increases the strength of the interfilament bonds.

Although it has not yet been completely explained theoretically, the tension or contraction force generated within the fibers of the present invention after the interfilament bond is formed affects various fabric properties of nonwoven fabrics made of the fibers. It is considered to be something that will help you improve. Therefore, the unique thermomechanical behavior of the novel fibers acts to confine tension within the nonwoven, and this tension improves the favorable recovery, drapability, and loftiness of the nonwoven fabric made from the fibers produced according to the present invention. It is believed that this helps at least in part to improve texture and texture.

Now, in order to provide a more detailed explanation of the composition of the fiber that is the subject of the present invention and its manufacturing method,
Reference is made to the examples below which describe methods of making such fibers in large quantities. In each example, an example was created in which the shape-retaining polymer was polyester. Also in each example, the adhesive component was selected from the group consisting of polyethylene and polypropylene having fiber-forming qualities. For this purpose, the temperature must be at least about 15°C below the melting point of polyester.
It is envisaged that other polymers with low melting points could be used as well.

The fibers of each example had a sheath-core structure in which the polyester component occupied the core portion, and the sheath and core portions were each formed eccentrically. We also used fibers in which the sheath and core portions were formed concentrically. However, fibers arranged in a side-by-side relationship should also be construed as falling within the scope of the present invention.

It is particularly noteworthy that although very different conditioning heat treatment conditions were applied to the fibers of each example, the thermomechanical response of the various fibers was the same after conditioning. Should. That is, in each fiber, if sufficient heat was applied to melt the adhesive component and then cooled, significant shrinkage forces developed only within the polyester component after the adhesive component resolidified. Although it is difficult to specifically state the conditions necessary to properly perform conditioning heat treatment, the following examples show that these conditions affect the past thermal history of the individual fibers used, and the bonding of the nonwoven fabric. It will be appreciated that this will be determined by factors such as the temperature at which the adhesive is applied (which temperature is determined by the particular adhesive component used), and the degree of shrinkage desired to occur within the fiber. As a general rule, there appears to be some direct relationship between the fusible component and the required heat conditioning temperature; for fibers where the fusible component has a high melting point, It is expected that the conditioning heat treatment temperature will also increase. Although it is not possible to give specific specific indicators, the exact conditioning heat treatment conditions for a particular fiber can be determined with a minimum of experimentation by referring to the contents of this specification. I think so.

It should be noted that it will be noticed that the "adjusted thermal response temperatures" used for the various fiber samples listed in each example are considerably dispersed. Such variations should be considered specific to staple fiber samples.

The present invention will be described below with reference to Examples.

Example 1 High-density polyethylene (Fortiflex-F-381; Soltex Polymer
Co., Ltd.) and a core made of semi-dull polyester of standard fiber quality.
The sheath and core were spun eccentrically to each other to yield a fiber consisting of 50 weight percent high density polyethylene and 50 weight percent polyester. The density of the high-density polyethylene used is 0.96
In g/cc, the density of the polyester was 1.38 g/cc. The density of the obtained fiber itself was 1.12 g/cc. The melting points of high density polyethylene and polyester were 132°C and about 260°C, respectively.

The two polymers were each melted in separate screw extruders and fed to a common spinneret via separate polymer feed lines and pump chambers. 265−270 high density polyethylene in extruder
After being heated to a temperature of °C, it is sent to the spinneret via a pump, while the polyester is
After heating to 285°C, it was fed to the spinneret via a pump. The polymers were first combined in the spinneret just before entering the filament extrusion capillary opening. As soon as the molten polyethylene contacted the molten polyester, the temperature of the polyethylene rose rapidly to about 285° C. for a short period of time before being cooled and solidified in the blow box. When spinning 3.0 dpf staple, each polymer component was delivered to the spinneret at a flow rate of 0.583 g/min/hole. That is, the total flow rate of both polymer components in this case was 1.166 g/min/hole. The diameter of each hole in the spinneret was 400 μm. After cooling the filament, which was still in tow form, a spinning oil was applied using a water wheel, as is conventionally done for olefinic filaments, and the resulting tow was wound up at a speed of 1752 m/min. The filaments were drawn in two stages to improve orientation and fiber performance. In this case, the first stretching was carried out at room temperature, and the stretching ratio was 1.05. Further, the second stretching was carried out in steam so that the temperature of the tow was 80° C., and the stretching ratio was 2.50. Therefore, the total stretching ratio was 2.62. During the stretching process, curl-like crimps naturally occurred in the tow each time the tension was relaxed. This was due to the difference in tension between the two polymer phases, and the crimp was not permanent. In order to improve the processability of the staple fiber, the tow was crimped by a conventional stuffer box crimping method. Thereafter, the fibers were subjected to conditioning heat treatment by heating them for 240 seconds in a forced air heating oven at 230°C (110°C) without applying any tension. The resulting fibers were then cut into 1.5 inch long staple fibers having the following properties.

Denier 3.00 dpf Strength 3.29 gpd Elongation 55.9% Crimp/inch 24 Seven samples of this fiber were prepared and each sample was thermal stress tested according to the test procedure outlined above. The maximum temperature reached in this test was 150°C. Near this temperature, the individual fibers would have adhesively bonded together to form a nonwoven fabric. In each sample, no significant shrinkage force was generated within the fiber bundle during the heating process of the test. However, significant tension was generated during the cooling process, respectively. The "adjusted thermal response temperature", ie the temperature at which a contraction force equal to the threshold of 0.01 grams of tension per denier was first observed during cooling of the fiber, is shown below for each sample.

Sample Adjusted heat response temperature 1 80°C 2 70°C 3 52°C 4 33°C 5 48°C 6 86°C 7 88°C Application example 1 (Production of nonwoven fabric) The staple fiber sample of Example 1 was made into a mat shape by hand. through a laboratory card machine. The resulting web was wound into four layers. The sample was further compressed into a mat using a 5 inch ram at 2000 psi, removed after 5 minutes and trimmed to shape. This sample was heated in a forced air oven at 145° C. for about 90 seconds to bond. Other samples were similarly prepared by changing the heating time to 60 seconds and 120 seconds, respectively. All samples have a fairly high degree of integrity, as the resulting pine can be pulled back to its original shape even if slightly pulled by hand. In addition, all samples have a high degree of elasticity and resiliency, as the mats return to their original volume after a small compressive force, such as manual pressure, is applied to crush the mats.

Example 2 A sample was spun in substantially the same manner as in Example 1, except that the stretching ratios were 1.10 and 2.136 in the first and second stretching steps, respectively. The properties of the obtained staple fibers were as follows.

Denier: 2.97 dpf Strength: 3.43 gpd Elongation: 54% Number of crimps/inch 23 Four samples of this fiber were prepared and subjected to a thermal stress test in the same manner as in Example 1. Similarly, none of the samples generated nearly any shrinkage force during the heating process of the test, but generation of shrinkage force was observed in all samples during the cooling process. The adjusted thermal response temperatures of these four examples were as follows.

Sample Adjusted Thermal Response Temperature 1 98°C 2 111°C 3 78°C 4 62°C Example 3 In exactly the same manner as in Example 1, except that a separate spinneret was used to create a filament with a symmetrical sheath-core structure. The sample was spun. The total stretching ratio was 2.28. The properties of the obtained staple fibers were as follows.

Denier: 3.03 dpf Strength: 3.28 gpd Elongation: 43.2% Number of crimps/inch: 16 Fiber length: 1.5 inches Two samples of this fiber were prepared and subjected to thermal stress analysis in the same manner as in Example 1. During the heating process of the test, both samples generated almost no shrinkage force, but during the cooling process, contraction force was generated in both samples. The adjusted thermal response temperatures for both samples are as follows.

Sample Adjusted thermal response temperature 1 87°C 2 64°C A nonwoven fabric was prepared using the above fibers in substantially the same manner as in Example 2. The obtained nonwoven fabric exhibited almost the same characteristics as the nonwoven fabric of Example 2.

Example 4 Staple fibers containing 50 weight percent of each of the high density polyethylene and polyester of Example 1 arranged in an eccentric sheath-core relationship were spun with both polymers supplied from separate screw press melting chambers. During spinning, each polymer was introduced into the spinneret at a flow rate of 0.501 g/min/hole, i.e.
A combined flow rate of 1.002 g/min/hole was delivered. The diameter of each hole in the spinneret was 250 μm. After cooling the filament in the form of tow, it is subjected to the same spinning finishing oil treatment that is normally applied to polyolefin filaments using a water wheel.
It was rolled up at a speed of m/min. To improve orientation and fiber performance, the filaments were drawn at a draw ratio of 4.53 through a 50 °C water bath. After the tow was crimped using conventional staff box crimping methods, it was tensioned in a forced air oven at 100°C for 200 seconds to stabilize the crimping and provide the desired tailored thermal response behavior. Processed without applying. Fibers cut into 1.5 inch long staples exhibited the following properties:

Denier: 3.06 dps Strength: 3.62 gpd Elongation: 49% Number of crimps/inch 18 The six fiber samples thus obtained were subjected to a thermal stress test in the same manner as in Example 1. During the heating process of the test, almost no tension was generated in any of the samples, but the sample fibers were heated to the melting point (freezing point) of the polyethylene sheath.
Tension was generated in all cases during the cooling process after cooling as described below. The adjusted thermal response temperature of each sample is shown below.

Sample Adjusted thermal response temperature 1 96°C 2 93°C 3 69°C 4 60°C 5 64°C 6 114°C Example 5 The high-density polyethylene and polyester of Example 1 were arranged in an eccentric sheath-core relationship at 50% by weight each. Both polymers were fed into separate screw extruders and spun into staple fibers. During spinning, each polymer was introduced into the spinneret at a flow rate of 0.50 g/min/hole, i.e.
It was delivered at a flow rate of 1000 g/min/hole. The diameter of each hole in the spinneret was 400 μm. After the extruded filament is cooled, it is passed through a water wheel and subjected to the same spinning finishing oil treatment that is applied to polyolefin filaments.
It was rolled up at a speed of 1000 m/min. filament
The film was stretched at a stretching ratio of 2.50 through a water bath at 70°C, and then further stretched at a stretching ratio of 1.3 in a water bath at 85°C.
Therefore, the total stretching ratio was 3.25. After crimping by conventional staff box crimping methods, the samples were processed without tension in a forced air oven at 90° C. for 300 seconds to obtain the desired tailored thermal response behavior. The properties of the fibers cut into 1.5 inch lengths were as follows.

Denier: 5.37 dpf Strength: 1.95 gpd Elongation: 81.8% Number of crimps/inch 31 A sample of the fiber prepared as described above was subjected to a thermal stress test in the same manner as in Example 1. Almost no tension was generated during the heating process of the test, but tension was generated during the cooling process after the fiber sample was cooled below the melting point (freezing point) of the polyethylene sheath. The adjusted thermal response temperature of this sample was 98°C.

Example 6 Polypropylene with a melt flow index of 33 (Fortilene HY-602A, Soltex Polymers
Staple fibers were spun with a 50 weight percent sheath consisting of Polyester Polyester, manufactured by Co., Ltd.) and a 50 weight percent core consisting of semidull polyester of normal fiber quality, with the sheath and core arranged in an eccentric relationship. The melting points of polypropylene and polyester were 162°C and 260°C, respectively.

As in Example 1, the polypropylene and polyester were melted, spun, and wound in separate screw extruders. The filament was drawn at a draw ratio of 2.6 to maximize orientation and improve properties as a textile fiber. After crimping using the conventional staff box crimping method to facilitate processing of staple fibers, the tow was conditioned at 230°C (110°C) for 240 seconds without tension. Heat treated. The properties of the obtained fibers were as follows.

Denier 2.60dpf Strength 4.04gpd Elongation 20.2% Crimp/inch 12 Emphasizes the effect of each fiber's thermal history on temperature and temporal conditions that must be observed to achieve the desired thermal response according to the present invention For this purpose, thermal stress tests were conducted on two samples of the above fibers in the same manner as described in Example 1. Although the thermal conditioning used in this example for this test was the same as that employed in Example 1, the results of the thermal stress analysis were different. Consistent with the desired thermal response, no shrinkage forces were observed during the heating process in both tests. However, with overcooling and adjusted thermal response temperatures that were significantly higher than those recorded in Example 1, it was evident that significant tension had built up in both samples. The adjusted thermal response temperatures were specifically about 136°C and 137°C, respectively. Although there is no theoretical support yet, the polyester component of the fibers of this example introduced into the core at a higher temperature is due in large part to the use of a sheath-forming material with a higher melting point. This resulted in Example 1
It is clear that a different tailored thermal response than that observed in the fibers occurred.

To emphasize the importance of the melting point of the sheath-forming material, which is 162°C in the case of polypropylene, we increased the maximum temperature reached to 200°C, at which point the fibers in this example would be bonded to the nonwoven fabric. Thermal stress tests were otherwise conducted on four samples of the above fibers in the same manner as described in Example 1. One of the effects of using a high maximum temperature reached was that during the heating process of the test there was an increase in the This was due to the accumulation of contractile force. Additionally, for all but one sample, tension was observed to build up at a much higher temperature during the cooling process of the test than in the previous example.

In order to make fibers from the fibers made in this example that exhibit tailored thermal response behavior consistent with the requirements of the present invention, the fibers made as described above were subjected to 300°C heating at 140°C.
A further conditioning heat treatment was carried out consisting of heating for seconds. Two samples thus treated were subjected to the same thermal stress test as in Example 1, except that the maximum temperature reached was 200°C. As a result, the fibers of the present invention exhibited a unique thermal response. In other words,
During the heating process, almost no shrinkage force was observed in any of the samples, but during the cooling process, significant shrinkage force was observed only when the temperature gradually decreased below 162°C, which is the freezing point of the sheath-forming material. occurred in each sample. The adjusted thermal response temperatures of both samples were 110°C and 135°C, respectively.

Finally, to demonstrate the effect of excessive conditioning heat treatment, another batch of fibers was subjected to a second conditioning heat treatment step as described above. However, this time heat treatment was performed at 145°C for 300 seconds. Two samples were prepared from the above fibers, and the maximum temperature reached was again set at 200°C, and a thermomechanical test was conducted. No accumulation of tension was observed in any of the samples during both heating and cooling processes.

Although the present invention has been explained based on the above-mentioned specific examples and illustrative examples, the scope of the present invention falls within the scope of the present invention except for the limitations described in the claims column. Of course, it is not limited to this range.

[Brief explanation of the drawing]

FIG. 1 is a microscopic photograph of a nonwoven fabric produced using the filaments of different components according to the present invention, and is used to illustrate the bond between filaments present in the nonwoven fabric. FIG. 2 is a graph illustrating the shrinkage force in the polyester component of the heterogeneous filament of the present invention as a function of temperature compared to the shrinkage force in the polypropylene component of the prior art. FIG. 3 is a graph showing the effect of conditioning heat treatment on the shrink force response of a fiber made of a heterogeneous filament containing a polyester component. 2... Bond between filaments.

Claims (1)

Claims: 1. A heterogeneous filament of the type comprising an adhesive component and another component consisting of polyester for forming an interfilament bond upon heating and subsequent cooling, comprising: Approximately 0.01 g/denier (0.0091 g/denier) only after the adhesive component resolidifies if sufficient heat is applied to melt the adhesive component followed by cooling.
A heterocomponent filament characterized in that it has thermomechanical response properties such that a contraction force greater than dtex) occurs in said further component. 2. The heterocomponent filament according to claim 1, wherein the adhesive component is polyethylene. 3. The heterocomponent filament according to claim 1, wherein the adhesive component is high density polyethylene. 4. The heterocomponent filament according to claim 1, wherein the adhesive component is polypropylene. 5. The heterocomponent filament according to claim 1, wherein the two components are arranged side by side. 6. The heterocomponent filament of claim 1, wherein the two components are arranged in a sheath-core relationship, with the other component occupying a core portion. 7. The heterocomponent filament according to claim 6, wherein the two components are eccentrically arranged. 8 consisting of an adhesive component and another component consisting of polyester for forming an interfilament bond upon heating and subsequent cooling;
The shrinkage force is greater than about 0.01 grams per denier (0.0091 g/dtex) only after the adhesive component has resolidified upon application of sufficient heat to melt the adhesive component and subsequent cooling. A method for producing a heterocomponent filament characterized by having a thermomechanical response characteristic occurring in the components, the method comprising: (a) spinning a heterocomponent filament comprising both of the components; and (b) In order to cause the heterogeneous filament spun in the step (a) to exhibit the thermomechanical response characteristics,
1. A method for producing a heterocomponent filament, comprising the step of performing conditioning heat treatment by heating at a predetermined temperature below the melting point of a low melting point component for at least a predetermined period of time. 9. The manufacturing method according to claim 8, further comprising the step of stretching the heterocomponent filament spun in step (a) before the conditioning heat treatment step. 10. The manufacturing method according to claim 8, wherein the adhesive component is polyethylene. 11. The manufacturing method according to claim 8, wherein the adhesive component is polypropylene. 12 The heat treatment temperature for conditioning is approximately
11. The manufacturing method according to claim 10, wherein the conditioning heat treatment time is in the range of about 180 seconds to about 300 seconds at a temperature of 90 DEG C. to 120 DEG C. 13. Claim 1, characterized in that the heterogeneous filament spun in step (a) is heated at a temperature of about 140° C. or higher for at least about 300 seconds.
The manufacturing method according to item 1. 14. The manufacturing method according to claim 9, characterized in that, after the drawing step, the heterogeneous filament spun and drawn in the step (a) is wound up.