KR100244623B1 - Hotmelt-adhesive fiber sheet and process for producing the same - Google Patents

Abstract

The present invention relates to terpolymers of (1) ethylene-acrylic acid ester-maleic anhydride [here, since the terpolymers have a high frictional force against metals and are susceptible to static electricity, these terpolymers have so far been separated from such terpolymers due to inferior bag properties. No microfibers were obtained] and (2) the composite resin was melted at a temperature of 30 ° C. or more higher than the melting point of the terpolymer according to the melt blowing process, and the obtained composite fibers were made without using a specific spinning lubricant. The present invention relates to a melt-adhesive fibrous sheet having high adhesion to paper, cloth, wood, metal, and the like, which is obtained by heat treatment of the web.

Description

Hot Melt Adhesive Fiber Sheets and Manufacturing Method Thereof

The present invention relates to a hotmelt-adhesive fiber sheet and a method of manufacturing the same. In particular, the present invention relates to a hot melt adhesive fibrous sheet which can be firmly adhered to paper, cloth, wood and metal by heating.

Until now, a hot melt adhesive composite fiber or a nonwoven fabric using the same, a polypropylene or polyester as a high melting point component and a polyethylene or ethylene-vinyl acetate copolymer as a low melting point component was obtained by complex spinning to obtain a web, and then Those obtained by heat-treating the web to fix the contact points of the fibers by melt bonding are known [see; Japanese Patent Laid-Open No. 54-44,773 and Japanese Patent Laid-Open No. 2-49,351].

However, these composite fibers have high adhesion to each other to produce high strength nonwoven fabrics, while they have low adhesive strength to other materials such as paper, cloth, wood, and metals, which are insufficient as raw materials for composite materials. In addition, fibers using a copolymer of ethylene and an unsaturated carboxylic acid as a low melting point component of a composite fiber in order to improve adhesion are known [see; Japanese Patent Laid-Open No. 1-92,415], which is also unsatisfactory.

As the composite fibers having high adhesion to other materials, those obtained by mixing terpolymers of ethylene, acrylic esters and maleic anhydride in low melting point components are known [see; Japanese Patent Laid-Open Publication No. 3-133,625, Japanese Patent Laid-Open Publication No. 3-287,875 and Japanese Patent Laid-Open Publication No. 4-146,300. Sufficient adhesion to these fibers. In order to impart, it is necessary to mix at least 15% by weight of such terpolymer into the low melting point component.

However, since terpolymers have a higher frictional force on metals and are more susceptible to static electricity, their bagability becomes poor, making it difficult to obtain small fineness of 10 µm or less. Therefore, many problems have arisen such as winding around the roller in the stretching step or generating a nep in the carding step. In order to overcome the above problems, there have been attempts to attach a large amount of surfactant to the fiber by more than 0.15% by weight, but rather the adhesive strength of the fiber is lowered.

SUMMARY OF THE INVENTION An object of the present invention is to overcome the above-mentioned drawbacks of conventional hot melt adhesive fibers and sheets, and to produce a hot melt adhesive fibrous sheet having a small fineness and high adhesion of the fibers to other materials and to produce the same. Is to provide a simple way.

The inventors of the present invention intensively studied to achieve the above object and obtained a web by spinning composite fibers using a specific terpolymer of ethylene-acrylic acid ester-maleic anhydride as a low melting point component according to the melt blowing method. The present invention was found to be accomplished by heat treatment of the obtained web, thereby completing the present invention.

The present invention has two aspects as follows.

(1) a mixture of at least 20% by weight of the terpolymer of ethylene, acrylic acid ester and maleic anhydride and at most 80% by weight of polyolefin as a first component, wherein the content of maleic anhydride in the mixture is at least 0.7% by weight; and A composite fiber composed of a thermoplastic resin having a melting point of 30 ° C. or more higher than the melting point of the first component as the second component, wherein the first component is continuously formed in the fiber length direction and occupies at least a portion of the surface of the fiber, and has an average fiber diameter. Is 10 μm or less, and the contact points of the composite fibers are fixed by melt-bonding the terpolymer;

(2) a mixture of at least 20% by weight of ternary copolymer of ethylene, acrylic acid ester and maleic anhydride and up to 80% by weight of polyolefin, wherein the content of maleic anhydride in the mixture is at least 0.7% by weight; and Composite melt blown spinning of a mixture of thermoplastic resins having a melting point of 30 ° C. or more higher than the melting point of the first component as the second component so that the first component can be continuously formed in the fiber length direction to occupy at least a portion of the fiber surface Obtaining a fibrous web, and then heat treating the obtained web at a temperature above the melting point of the terpolymer and below the melting point of the second component.

The invention is described in more detail below. A terpolymer used as the first component of the heat-melt adhesive fibers of the present invention, comprising 6 to 30% by weight of acrylic ester, 0.7 to 5% by weight of maleic anhydride and the remaining amount of monomers of ethylene Terpolymers having a melting point of 60 to 110 ° C. and a melt flow rate of 190 ° C. to 2 to 300 g / 10 min are preferable because of their excellent bagability and adhesion. Among the acrylic esters, ethyl acrylate, methyl acrylate, Butyl acrylate, 2-ethylhexyl acrylate, etc. are preferable.

The terpolymer can be used alone or as a first component and can also be mixed with a polyolefin. As such polyolefin, high density polyethylene, low density polyethylene, linear low density polyethylene, polypropylene, etc. can be illustrated. In addition to the above-mentioned polyolefins, polyesters and polyamides are not preferable because of poor compatibility with the terpolymers described above, poor bagability, and small fiber fineness. When terpolymers are used in admixture with polyolefins, the content of terpolymers in the first component should be at least 20% by weight and the content of maleic anhydride in the mixture at least 0.7% by weight. When the content of the terpolymer in the first component and the content of maleic anhydride do not satisfy the respective ranges described above, the adhesiveness of the obtained hot melt adhesive fibers is insufficient.

The content of maleic anhydride mentioned in the present invention means the ratio of maleic anhydride in the first component. For example, when the terpolymer consists of ethylene, ethyl acrylate and maleic anhydride (ethyl acrylate: 19.5% by weight maleic anhydride: 2.5% by weight), the content of maleic anhydride is the tertiary content in the first component. If the content of the coal is 50% by weight is 1.25% by weight.

As the second component of the heat-melting adhesive fiber of the present invention, a thermoplastic resin having a melting point of 30 ° C. or higher than the melting point of the first component is used. As such thermoplastic resins, conventional fibers [eg; Polyolefins, polyesters and polyamides] can be exemplified. Since the first component is inferior in bag property itself, the bag property is improved by mixing and manufacturing the first component. In the case where the melting point difference between the two components is less than 30 ° C, even when the composite spinning is performed, the bag property due to the melt blown spinning process becomes poor, making it difficult to reduce the fiber fineness. Moreover, the temperature range which can endure the heat processing at the time of manufacturing a sheet from a web is narrow. All of these phenomena are undesirable.

Among the thermoplastic resins as the second component, the so-called pyrolysis type polypropylene in which the molecular chain is cut by organic peroxide or the like at the time of melt spinning is not only excellent in the bag property described above but also excellent in reducing the fiber fineness. Such polypropylene resins are preferred because they have strong peelability from components.

In the heat-melt adhesive fiber sheet of the present invention, since the average fiber diameter of the fibers constituting the sheet is 10 µm or less, an anchoring effect occurs during the adhesion of the sheets to each other or on another material. Easier In particular, when the surface of the target materials is rough, the fixing effect becomes remarkable. Mean fiber diameter referred to in the present invention means the values obtained as follows:

In scanning electron micrographs of 100 to 5,000 magnification, the fiber diameters at 100 points are measured to calculate their average value.

The obtained fibrous web having an average fiber diameter of 10 mu m or less can be obtained according to the composite melt blown spinning method, and the fibers constituting the web have a specific fiber length and are hardly stretched.

When the average fiber diameter exceeds 10 mu m, not only the surface area of the fiber but also the contact area of the fiber and the target material at the time of bonding are reduced, so that the amount of heat required for bonding is increased and the fixing effect on the target material cannot be predicted. In short, since the fibers are hardly stretched, the smaller the diameter of the fibers constituting the sheet, the more the surface area of the fibers increases, and the fibers are easier to bend, resulting in a smaller radius of curvature. As a result, since the contact area is increased, the adhesion between the fiber and the target material due to hot melt adhesion is improved. At the same time, because the contact area between the fibers increases and the number of contact points increases, not only the hot melt adhesion area increases, but also the networks between the fibers are reinforced, thereby improving the integrity of the sheet form.

The hot melt adhesive fiber sheet of the present invention is characterized in that the adhesive points of the fibers constituting the sheet are hot melt bonded. That is, when the composite fiber obtained by the composite melt blown spinning is heat-treated at a temperature above the melting point of the terpolymer in the first component and below the melting point of the second component, the obtained composite fiber is kept in the three-way hole at the contact point of the fiber while preserving its shape. The coalescence is fixed by hot melt bonding. When bonding the composite fibers by hot melt bonding, the composite fibers form a three-dimensional structure in the sheet so that the sheet does not deform even when the sheet is subjected to external pressure or force. Thus, the obtained hot melt adhesive fibrous sheet has good form integrity and no bulk reduction or deformation occurs even when laminated for a long time (ie, during its storage). On the other hand, since the sheet is heated in use, the terpolymers that fix the fiber contact points by hot melt adhesion are softened or melted, thereby reducing the restraint of the three-dimensional structure, thereby reducing the movement of the fibers or the sheet in the sheet. Make deformation easy. Thus, the contact of the fiber with the target material is increased and the adhesion of the fiber is effectively utilized. In addition, since the heat-melt adhesive fiber sheet of the present invention is composed of fibers of 10 µm or less, which is much smaller than the fineness of the fibers obtained according to conventional spinning and stretching methods, as described above, the fibers themselves are soft. When the sheet is laminated with a plurality of fiber contact points, the fiber shape is preserved and the sheet is easily deformed when the sheet is used, thereby improving the adhesion of the sheet of the present invention.

In the composite melt blown spinning process, as described in Japanese Patent Application Laid-Open No. 60-99,057, two types of thermoplastic resins melted independently of each other are introduced into one spinneret and combined together, and then The process refers to a process in which molten strands are extruded and stretched from a spinning nozzle by blowing gas at a high speed, and then the obtained fibers are recovered in the form of sheets and stacked on a conveyor. As the composite form, side-side-type or sheath-and-core type may be used depending on the application, but the first component is continuous to at least part of the fiber surface of the fiber surface. It is preferred to form them and coat them as broadly as possible.

The first component and the second component are composite spun according to the melt blowing process at a compounding ratio within the range of 80/20 to 40/60, preferably 70/30 to 50/50 by weight. When the composite ratio of the first component is less than 40/60, the obtained fiber has insufficient adhesiveness, while when the ratio exceeds 80/20, the bag property is degraded to make the fiber powdery or easily generate static electricity.

As blow gas for composite melt blown spinning, air or nitrogen gas of 200 to 300 KPa and about 400 ° C is used. The gas is ejected from the hole in the spinneret at a speed of 350 to 500 m / sec. The distance between the spinneret and the recovery conveyor can be in the range of 30 to 80 cm.

In manufacturing the hot melt adhesive fiber sheet of the present invention, the first component is continuously formed by adjusting the compound ratio, extrusion speed and spinning temperature of the first component with respect to the second component to occupy at least a portion of the fiber surface. Do it.

The webs stacked on the recovery conveyor are heat embossing rolls, heat calendering rolls, heated air circulation drying ovens, far-infrared rays heater ulfrasonic welders and heated air through-overs. (hot air through over) and the like heat treatment and processing to obtain a sheet. Among these means, a heating embossing roll and a heating calendering roll are suitable for obtaining a sheet having a low thickness non-uniformity and uniform quality.

The invention is explained in greater detail using the examples and control examples. Testing of the average fiber diameter and peel strength used in the examples is carried out according to the following method:

[Peel strength]

The test piece of hot melt adhesive fibrous sheet was placed between two sheets of aluminum foil (or kraft paper) 5 cm wide and 10 cm long, and then the obtained material was heat with a press 1 cm wide. Using a heat-sealing tester, the film was pressed at 150 ° C. under a pressure of 3 kg / cm (294 KPa) for 5 seconds, and the aluminum foil (or kraft paper) was not pressed, and the tensile tester was used. The peel strength (g / 5cm) was measured, and the initial gripping distance was 10 cm and the tensile speed was 10 cm / min.

[Average fiber diameter]

The recovered fibers from the web on the recovery conveyor are photographed using a scanning electron microscope to obtain a picture of 100 to 5,000 times magnification, and then the fiber diameter is measured at 100 points on the picture to calculate its average value.

In the examples, the following raw materials are used:

EH-1: ethylene-ethyl acrylate-maleic anhydride terpolymer (ethyl acrylate: 19.5 wt%, maleic anhydride: 2.5 wt%, melt flow rate: 20, melting point: 80 ° C)

EH-2: Ethylene-ethyl acrylate-maleic anhydride terpolymer (ethyl acrylate: 29.4 weight%, maleic anhydride: 2.5 weight%, melt flow rate: 40, melting | fusing point: 68 degreeC)

PE-1: High density polyethylene (melt flow rate: 93, melting point: 129 ° C)

PE-2: Linear low density polyethylene (melt flow rate: 124, melting point: 122 degreeC)

PP-1: Polypropylene (melt flow rate: 80, melting point: 162 ° C)

PET-1: polyethylene terephthalate (intrinsic viscosity (η): 0.62, melting point: 255 ° C)

Example 1

A mixture of 30/70 weight ratio of EH-1 and PE-1 as the first component, using a composite spinneret in the form of a sheet and core having 501 spinnerets with a nozzle diameter of 0.3 mm and arranged in a row for melt blown. Is supplied at a spinning temperature of 260 DEG C, PP-1 is supplied at a spinning temperature of 280 DEG C as the second component (wherein the combined ratio of the two components is 50/50 (weight ratio)), and air is supplied at 350 DEG C. Blown under temperature and 216 KPa pressure, the polymer is extruded from the spinneret onto the recovery conveyor. As a recovery conveyor, a polyester net conveyor which is 48 cm away from the spinneret and moves at a speed of 4 m / min is used. Blown air is removed by suction means provided at the rear of the conveyor. Subsequently, the obtained web was treated using a heat embossing roller at 120 ° C. to obtain a sheet of very fine composite fibers having a basis weight of 35 g / cm 2.

The average fiber diameter of the sheet and the peel strength of the sheet obtained are shown in Table 1.

[Examples 2 to 4 and Comparative Example 1]

Various sheets were obtained under the same conditions as in Example 1 except that the mixing ratio of EH-1 and PE-1 in the first component was changed. The manufacturing conditions and average fiber diameter of these sheets, and the peeling strength of the obtained sheet are shown together in Table 1.

Example 5

The sheet of this example is obtained under the same conditions as in Example 1 except for changing the complex form into side by side. The production conditions and average fiber diameter of the sheet, and the peel strength of the sheet obtained are shown in Table 1 together.

[Examples 6 and 7 and Comparative Example 2]

Except for changing the raw materials of the first component and the second component as shown in Table 1, various sheets were obtained under the same conditions as in Example 1. The production conditions and average fiber diameters of these sheets, and the peel strength of the sheets obtained are shown in Table 1 together.

Comparative Example 3

Using the same material as in Example 1 and following a conventional composite spinning process instead of a meltblowing process, unstretched yarns with short fiber fineness of 10.2 denier (11.2 d tex) are obtained. The yarn was drawn at 3.4 times the original length at a stretching temperature of 50 ° C., and then cut by 13 crimps (13 crimps / 25 mm) per 25 mm to cut 3d / f (3.3 d tex, fiber diameter: 22 μ) x 51 mm staple fibers. To obtain. The staple fibers are carded to obtain a web and then a sheet of composite fiber having a basis weight of 33 g / m 2 by treating the web using a heat embossing roller at 120 ° C. 0.2% by weight of oiling agents (surfactants) are attached to the fiber, but a significant amount of fiber is wound around the needle cloth in the carding process. The peel strength of the sheet was as low as 0.31 kg / 5 cm when using aluminum foil, 0.34 kg / 5 cm when using kraft paper, and the heat encapsulation time was up to 60 seconds (12 times longer than above). Even when extended, their respective peel strengths are only 1.0 kg / 5 cm and 2.0 kg / 5 cm. The production conditions and average fiber diameter of the sheet, and the peel strength of the sheet obtained are shown in Table 1 together.

MAH Rate: Maleic Anhydride Rate

* Peeling strength (A1 foil) of Examples 4 and 6: A1 foil breaks under 3.46 kg / 5 cm.

According to the present invention, an ethylene-acrylic acid ester-maleic anhydride is mixed with a second component having a melting point of 30 ° C. or more higher than the melting point of the first component as a first component having poor bagability, and then the mixture is mixed according to the melt blowing process. By spinning, it became possible to obtain a hot melt adhesive fibrous sheet composed of fine fibers having an average fiber diameter of 10 mu m or less. Since the said hot melt adhesive fiber sheet contains the fiber with a small diameter as mentioned above, it is excellent in the suitability to a target material and contributes to the adhesive improvement. In addition, because of the fixing effect in the material to be bonded due to the small fiber diameter, the adhesiveness can be greatly improved than the adhesion caused by the affinity or compatibility with the material to be bonded with the resin constituting the melt adhesive fiber sheet. Therefore, even when a sheet having a low basis weight has a very large adhesive strength, it is useful as a sheet-type melt adhesive, especially since the sheet is melt-bonded to metal, paper, cloth, and wood as well as aluminum foil or kraft paper. .

In addition, by obtaining the hot melt adhesive fiber sheet in accordance with the melt blowing step, it is possible to prevent a decrease in the hot melt adhesive ability due to the surfactant or the like which has been applied in the conventional stretching step. Thus, the adhesiveness of the resin itself, which effectively constitutes the fibers, can be utilized.

Claims (4)

As a first component, a mixture of 20% by weight or more of a terpolymer of ethylene, acrylic acid ester and maleic anhydride and 80% by weight or less of a polyolefin (wherein the content of maleic anhydride in the mixture is 0.7% by weight or more) and as a second component A composite fiber made of a thermoplastic resin having a melting point of 30 ° C. or more higher than the melting point of the first component, wherein the first component is continuously formed in the fiber length direction to occupy at least a part of the surface of the fiber, and the average fiber diameter is 10 μm or less. And the contact points of the composite fibers are fixed by hot melt bonding the terpolymer). The hot melt adhesive fiber sheet according to claim 1, wherein the polyolefin is polypropylene. As a first component, a mixture of at least 20% by weight of terpolymer of ethylene, acrylic acid ester and maleic anhydride and up to 80% by weight of polyolefin (wherein the content of maleic anhydride in the mixture is at least 0.7% by weight) and as a second component Composite melt blown spinning of a mixture of thermoplastic resins having a melting point of 30 ° C. or more higher than the melting point of the first component to obtain a composite fiber web in which the first component is continuously formed in the fiber length direction so as to occupy at least a portion of the fiber surface. And then heat-treating the obtained web to a temperature below the melting point of the terpolymer and below the melting point of the second component. The method of claim 3 wherein the polyolefin is polypropylene.