JPH08158234A - Polyester mesh nonwoven fabric and method for producing the same - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to a polyester reticulated nonwoven fabric and a method for producing the same, and in particular, by carrying out multi-stage drawing,
The object is to obtain a non-woven fabric having fine threads, high strength and excellent transparency. [Structure] The polyester reticulated nonwoven fabric and the method for producing the same according to the present invention include an unstretched film (6) made of polyethylene terephthalate, and a large number of cuts in a direction parallel to the stretching direction (A) of the film (6). 8) is formed and a multi-stage drawing is performed so that the breaking stress of the yarn (9) between the cuts (8) is 10 kg / mm ² or more, whereby a reticulated nonwoven fabric having high strength can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester reticulated non-woven fabric and a method for producing the same, and more particularly to a novel non-woven fabric for obtaining a non-woven fabric having a thin yarn, high strength and excellent transparency by carrying out multi-stage drawing. Related to improvements.

[0002]

2. Description of the Related Art Conventionally, a mesh nonwoven fabric is made of polyethylene (hereinafter referred to as PE). As a method for producing a PE non-woven fabric, for example, Japanese Patent Application Laid-Open No. 55-107427 discloses a method for forming a cut. In this method, the film is placed under tension, and a large number of blades having sharp edges are embedded in a roll rotating in the moving direction of the film at a substantially right angle to the moving direction, whereby a cut is formed in the film. Japanese Utility Model Publication No. 3-57439 discloses a method of passing an unstretched film between rolls made of an elastic material. The film thus formed with the cuts is stretched 10 times or more at the temperature at which the molecular chains are oriented in order to orient the molecular chains and thin the threads. The method relating to the multi-stage drawing shown in the present invention is often practiced in the production of polymer fibers and films. For example, in Japanese Examined Patent Publication No. 55-32805, stepwise stretching is carried out in order to prevent the stretching ratio from rapidly increasing. Further, in Japanese Examined Patent Publication No. 3-66403, the second stage is stretched in order to selectively re-stretch the stretch unevenness generated in the first stage. Further, in JP-A-5-286029, stepwise stretching is performed in order to prevent dimensional stability of the biaxially stretched film and prevent breakage during stretching.

[0003]

The conventional reticulated nonwoven fabric is
Since it was configured as described above, there were the following problems. That is, this PE reticulated nonwoven fabric has a tensile breaking stress of 2.5 kg / mm ² , which is about a quarter of 10 kg / mm ² of polyethylene terephthalate (hereinafter referred to as PET). Therefore, in order to produce a reticulated nonwoven fabric having the same strength as PET with PET, the cross-sectional area must be four times or more that of PET. Therefore, it is conceivable to form the reticulated nonwoven fabric with a material having high tensile strength such as PET. However, it is very difficult to produce a PET reticulated nonwoven fabric by the above method. One of the reasons for difficulty is that PET is a hard material and it is difficult to form a cut. As is well known that hardness is proportional to tensile yield stress, it is not easy to form a break in a material having high tensile strength. For example, if a PET film having a thickness of 0.2 mm is used to form a cut using the receiving roll made of the elastic body, the PET film is pushed into the elastic body, and thus it is impossible to form the cut. . The second difficult reason is that the maximum draw ratio of PET is smaller than that of PET, so that the yarn cannot be thinned. That is, the stretching of the film having a cut is performed for the purpose of thinning the yarn and increasing the strength of the film, but in order to increase the strength, it is necessary to orient the molecular chains in the crystal. is there. However, in the case of PET, the optimum stretching temperature for increasing the strength is limited to just above the vitrification transition temperature, and the maximum stretching ratio at that time is 4 to 5 times. The thread cannot be thinned. This will be described in detail with reference to FIG. In FIG. 4, the horizontal axis represents the draw ratio; λ
The vertical axis is the normal temperature breaking stress; σ. Width of yarn after drawing;
W is K = Kλ ^-1/2 , which is inversely proportional to λ, where K is the width of the yarn before drawing (this is equal to the interval between the blades forming the cut). Therefore, the width of this yarn is also shown on the horizontal axis.
What is important here is that K cannot be made as small as possible. The reason for this is that the blade forming the cut has a certain width and that there is a limit to the processing technique for directly processing the blade on the roll. Therefore, K ≧
0.7 mm is the limit, and since K ≧ 0.8 mm in reality (relatively cheap and easy to process), K = 0.
8 mm. From Figure 4, the area required for reticulated non-woven fabric is W
If ≦ 0.3 mm and P ≧ 10 kg / mm ² , it means that a PET non-woven fabric satisfying this region cannot be produced by one-stage stretching.

Further, in the case of the above-mentioned conventional example of multi-stage stretching, it was not carried out to increase the stretching ratio as in the present invention, and the total stretching ratio was 7 times or less. Therefore, at present, as a reticulated non-woven fabric, required properties are described. The reticulated non-woven fabric may be used as a packaging material, a tape base material, and the like.
Excellent properties such as strength resistance and tear resistance are required, and in order to satisfy these properties, the yarn is required to be thin and have high strength. Specifically, the thread thickness is preferably 0.3 mm or less and the strength is preferably 10 kg / mm ² or more. As described above, the PET non-woven fabric having a thin thread and high strength is very effective in industry, and its appearance in the market is desired.

The present invention has been made to solve the above problems, and in particular, by carrying out multi-stage drawing, it is possible to obtain a non-woven fabric having a thin yarn, high strength and excellent transparency. An object of the present invention is to provide a reticulated nonwoven fabric made of polyester and a method for producing the same.

[0006]

The polyester reticulated nonwoven fabric according to the present invention is a film made of polyethylene terephthalate, which has a large number of cuts in a direction parallel to the stretching direction, and between the cuts and in the longitudinal direction of the film. The yarn has a breaking stress of 10 kg / mm ² or more and a plurality of films are laminated.

In the method for producing a polyester reticulated nonwoven fabric according to the present invention, a large number of cuts are formed in an unstretched film made of polyethylene terephthalate, and the film is stretched in the longitudinal direction of the cuts to form between the cuts. In a method for producing a polyester reticulated non-woven fabric, which comprises thinning the formed yarns and laminating and adhering the films so that the longitudinal directions of the cuts are orthogonal to each other, a cutter roll having a large number of blades and a smooth surface Forming a cut in the film with a receiving roll having, and performing a multi-stage drawing satisfying the following formula for the film having the cut, the breaking stress of the yarn is 10Kg
/ Mm ² or more, a method for producing a polyester reticulated non-woven fabric. Tg + 30 ≦ T ₁ (° C.) ≦ 150 Δn ₁ ≦ 2 × 10 ^1-2 Tg ≦ T ₂ (° C.) ≦ Tg + 20 3.0 ≦ DR ₂ ≦ 4.5 7 ≦ DR ₁ × DR ₂ = TDR However, Tg Glass transition temperature T ₁ ; one or more stages of stretching temperature T ₂ carried out in the preceding stage T ₂ ; one or more stages of stretching temperature carried out subsequent to the preceding stage Δn ₁ ; one or more stages of stretching carried out in the preceding stage Birefringence at the time of completion DR ₁ ; One-stage or multiple-stage draw ratio DR ₂ performed in the previous stage; One-stage or multiple-stage draw ratio TDR performed in the latter stage TDR; Overall draw ratio

More specifically, it is a method in which the blade interval of the cutter roll is set to 0.7 mm or more.

[0009]

In the polyester reticulated nonwoven fabric and the method for producing the same according to the present invention, a large number of cuts are formed by passing an unstretched film of polyesterene terephthalate between a cutter roll and a receiving roll. By stretching the film in multiple stages along the line, the yarn formed between the cuts is thinned to produce a polyester reticulated non-woven fabric that is thin and has a high fracture strength of 10 kg / mm ² or more. can do.

[0010]

The preferred embodiments of the polyester reticulated nonwoven fabric and the method for producing the same according to the present invention will be described in detail below with reference to the drawings. In the examples and experimental examples, the first stage 1
The case of the first stage or the second stage will be described (the first stage is referred to as the first stage and the second stage is referred to as the second stage). The same thing as the stretched one is obtained. FIG. 1 shows a splitting device for forming cuts in a polyester mesh nonwoven fabric according to the present invention. 1 is a cutter roll having a large number of blades 2, and this cutter roll 1 has a receiving roll 3 having a smooth surface.
Are opposed to each other, a first film feed roll 4 is arranged on the upstream side of the cutter roll 1, and a second film feed roll 5 is arranged on the downstream side thereof.

An unstretched film 6 made of polyester terephthalate (PET) guided between the cutter roll 1 and the receiving roll 3 is wound by a winder 7 and is formed by a plurality of blades 2. Break 8
The unstretched film 6 having the is as shown in FIG.
A thread 9 is formed between the cuts 8 along the longitudinal direction of the cuts 8, and a stretching direction A, which will be described later, with respect to the film 6 and a roll feeding direction B of the cutter roll 1 are orthogonal to each other.

Next, a case where the PET film 6 is actually stretched in a plurality of stages to manufacture a polyester mesh nonwoven fabric will be described. As shown in FIG. 1, unstretched PET film 6
Through a first film feed roll 4, a cut roll 1 for forming a slit, and a receiving roll 3 to form a slit 8 in the film 6, and then the film 6 is passed through a second film feed roll 5 for winding the film. Wind up at 7, break 8
To obtain a PET film 6. The cut roll 1 and the receiving roll 3 used at this time are made of a material having high rigidity, for example, S
It can be used with KD steel and the like, and almost no roll deflection occurs. Therefore, the cut 8 can be easily formed in the PET film 6 having a thickness of 0.2 mm or more. Here, since a slight gap is provided between the tip of the blade of the cutting roll 1 and the receiving roll 3 to protect the tip of the blade 2, the blade 2
Is not expected to penetrate the film 6 completely, but there is no such concern. Actually PE with a thickness of 0.2 mm
The T film 6 was subjected to a split device 20 at a total load of the cut roll 1 of 10 tons and a feed speed of the film 6 of 10 m / min to form a cut, and a cut that completely penetrated was formed. This is because the rotation of the roll exerts stress in the direction perpendicular to the cut.

Next, the cut 8 produced in this way
The unstretched film 6 (FIG. 2) having the above is stretched in a direction parallel to the cuts 8 by a stretching machine (not shown), and the yarn 9 is thinned in parallel to the stretching direction A formed between the adjacent cuts 8.
At the same time, the strength of the film 6 is increased. At this time, the first-stage drawing is intended to make the yarn 9 thin, and it is desirable that the crystal state is not changed by drawing as much as possible. For that purpose, the stretching temperature is set so that the orientation of the molecular chain hardly occurs due to the stretching and the crystallization does not occur.
It is necessary to satisfy g (glass transition temperature) + 30 ≦ T ₁ (° C.) ≦ 150. If the stretching temperature is lower than (Tg + 30) ° C., the molecular chains are strongly oriented in the stretching direction. Further, at this time, the stretching ratio is limited to about 5 times, and further stretching causes breakage. On the other hand, when the stretching temperature is 150 ° C. or higher, crystallization occurs earlier than the completion of stretching and the film 6 becomes cloudy. When the second-stage stretching is performed on the crystallized film 6, the film 6 is hardly stretched and is broken. Since there is almost no molecular chain orientation in such a first-stage stretching,
The birefringence generated by stretching is Δn ₁ ≦ 2 × 10 ⁻² , and it is desirable to satisfy this condition. The second-stage drawing aims to increase the strength of the yarn by orienting the molecular chains, and Tg ≦ T ₂ (° C.) ≦ Tg + 20, 3.0 ≦ DR ₂
It is necessary to be ≦ 4.5. When the stretching temperature is Tg ° C or lower, the film is broken by stretching. On the other hand, the stretching temperature is (Tg + 20)
Above 0 ° C, the orientation of the molecular chains hardly occurs, so that the yarn cannot be made to have high strength. Further, in order to sufficiently orient the molecular chains, it is necessary to take a sufficient stretching ratio. Therefore, the draw ratio of the second stage needs to be at least 3 times or more. In addition, since the yarn breaks at 4.5 times or more,
It must be less than 4.5 times. Overall stretch ratio by such two-stage stretching; TDR is DR ₁ × DR ₂ ,
In order to reduce the yarn width to 0.3 mm or less, it is necessary to satisfy TDR ≧ 7. In particular, since the size of DR ₁ can be arbitrarily set, this value can be changed to obtain the required thread thickness. Therefore, there is also an advantage that it is not necessary to manufacture the cutter roll 1 according to the thickness of the yarn 6, and the cost and the delivery time can be reduced.

The above-mentioned multi-stage stretching by the first stage and the second stage satisfies the following formula, and the interval between the blades 2 is set to 0.7 mm or more due to the thickness of the blades and the limit of processing technology. Has been done. Tg + 30 ≦ T ₁ (° C.) ≦ 150 Δn ₁ ≦ 2 × 10 ⁻² Tg ≦ T ₂ (° C.) ≦ Tg + 20 3.0 ≦ DR ₂ ≦ 4.5 7 ≦ DR ₁ × DR ₂ = TDR However, Tg; Glass transition temperature T ₁ ; 1-stage or multi-stage stretching temperature performed in the previous stage T ₂ ; 1-stage or multiple-stage stretching temperature performed in the subsequent stage and subsequent stage Δn ₁ ; 1-stage or multiple-stage stretching performed in the previous stage is completed Birefringence at the time of performing DR ₁ ; 1-stage or multiple-stage draw ratio DR ₂ performed in the previous stage; 1-stage or multiple-stage draw ratio TDR performed in the latter stage TDR; Total draw ratio

Experimental Example An unstretched film 6 of PET having a width of 400 mm and a thickness of 0.4 mm obtained by melt extrusion by a conventional method and rapid solidification was formed with a large number of cuts 8 by using the split device 20 of FIG. At this time, the feed speed of the cutter roll 1 of the split device 20 is 10 m / min, and the feed speed of the first film feed roll 4 is slightly slower than this in order to adjust the tension of the film 6, and the second film feed roll is adjusted. The feed rate of 5 was slightly faster. The film 6 produced in this manner was used as L ₁ ×
It was cut into a size of L ₂ = 50 × 300 mm and placed in an unillustrated stretching machine (made by Iwamoto Seisakusho) for experiments. here,
L ₁ is the length in the direction parallel to the cut 8, and L ₂ is the length in the direction perpendicular to the cut 8. At this time, the temperature of the stretching machine is already heated to 110 ° C., the film 6 is quickly installed, and after preheating for several minutes to stabilize the atmosphere temperature of the stretching machine, the film 6 is stretched at 100% / min. It was stretched 3 times at a speed in a direction parallel to the cut 8. Next, set the ambient temperature to 8
After the temperature was lowered to 0 ° C. and the ambient temperature of the stretching machine was stabilized, this film was stretched 3.4 times at a stretching rate of 100% / min. Finally, in order to crystallize the film, it was heat-treated at 160 ° C. for 1 minute, cooled to near room temperature, and then taken out from the stretching machine. The shape of the film 6 thus produced is 510
The yarn 9 had a thickness of × 300 mm and a thickness of about 0.26 mm. Next, this film 6 is set to L ₁ × L ₂ = 50 mm × 200 mm and 2
It was cut into a size of 00 mm x 50 mm. And this 2
The sheets of film 6 were laminated so that the threads 9 were orthogonal to each other, passed through a rolling roll having a width of 300 mm and heated at 120 ° C., and bonded by thermocompression bonding to obtain a PET reticulated nonwoven fabric (not shown). .

The breaking strength of the reticulated nonwoven fabric thus produced was measured by a tensile tester (Shimadzu AG2000) in accordance with JIS L-1096.
It was 5 cm. Further, when the thread 9 was cut out from the film 6 before thermocompression bonding and the breaking stress thereof was measured, it was 17.7 kg /
It was mm ² . Similarly, a reticulated non-woven fabric was prepared by setting the draw ratio of the first step to 2.5 times and the draw ratio of the second step to 3.2 times, and measuring the room-temperature breaking strength and the breaking stress of the yarn, It was 59 kg / 5 cm and 19.2 kg / mm ² . A reticulated nonwoven fabric was produced under other conditions, and the room-temperature breaking strength was measured. The results are summarized in FIG. The horizontal axis of FIG. 3 shows the total draw ratio by the first and second steps of drawing, and the vertical axis shows the room temperature breaking stress of the produced PET net-like nonwoven fabric yarn 9. As shown in FIG. 3, the total draw ratio can be increased by increasing the draw ratio of the first stage.
The width of the thread can be reduced. Further, the present invention is 1
In order to investigate the degree of orientation of the molecular chains in the film due to the stretching in the second and second steps, a 0.4 mm thick unbroken 100 × 100 mm film was stretched under the same conditions and the first and second steps were performed.
When the birefringence after stretching in the second step was measured, the birefringence after stretching in the first step was 0.003, and the birefringence after stretching in the second step was 0.09. That is, it was confirmed that the orientation of the molecular chains hardly occurred in the first stretching, and the orientation of the molecular chains sufficient to obtain the tensile strength of the film occurred in the second stretching. When the tensile breaking stress of this film was actually measured, it was 20 Kg / mm ² . This is P
The value is almost the same as that of the ET mesh non-woven fabric.

[0017]

Since the polyester reticulated nonwoven fabric and the method for producing the same according to the present invention are constructed as described above, the following effects can be obtained. That is, since the film is processed by drawing in multiple stages, the thread is thin and the strength in the direction parallel to the break is 10 kg.
It is possible to obtain a polyester net-like non-woven fabric having a / mm ² or more. Further, the width of the yarn can be easily adjusted by the method for producing the polyester reticulated nonwoven fabric of the present invention,
A polyester reticulated nonwoven fabric having a high tensile breaking strength can be easily produced.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a split device applied to the present invention.

FIG. 2 is an explanatory view showing an unstretched film having a slit.

FIG. 3 is a characteristic diagram showing the total draw ratio and breaking strength by the two-step drawing of the present invention.

FIG. 4 is a characteristic diagram showing a stretching ratio and a breaking strength only by conventional one-step stretching.

[Explanation of symbols]

 1 Cutter Roll 2 Blade A Stretching Direction 3 Support Roll 6 Film 8 Cut 9 Thread

Claims (3)

[Claims] 1. A film (6) made of polyethylene terephthalate has a large number of cuts in a direction parallel to the stretching direction (A).
(8), between the cuts (8) and the film (6)
The breaking stress of the thread (9) formed in the longitudinal direction is 10 kg / mm ²
In addition to the above, the polyester reticulated non-woven fabric is characterized in that the plurality of films (6) are laminated. 2. A plurality of cuts (8) are formed on an unstretched film (6) made of polyethylene terephthalate, and the film (6) is stretched in the longitudinal direction of the cuts (8) to form the cuts (8). ) Thin the thread (9) formed between the
(8) Each film so that the longitudinal direction thereof is orthogonal to each other
(6) In the method for producing a polyester reticulated non-woven fabric which is configured to be laminated and adhered, a cutter roll (1) having a large number of blades (2) and a receiving roll (3) having a smooth surface and the film ( The break (8) is formed in 6), and the film (6) having the break (8) is subjected to multi-stage drawing satisfying the following formula, and the breaking stress of the yarn (9) is 10 kg.
/ Mm ² or more, a method for producing a polyester reticulated non-woven fabric. Tg + 30 ≦ T ₁ (° C.) ≦ 150 Δn ₁ ≦ 2 × 10 ^1-2 Tg ≦ T ₂ (° C.) ≦ Tg + 20 3.0 ≦ DR ₂ ≦ 4.5 7 ≦ DR ₁ × DR ₂ = TDR However, Tg Glass transition temperature T ₁ ; one or more stages of stretching temperature T ₂ carried out in the preceding stage T ₂ ; one or more stages of stretching temperature carried out subsequent to the preceding stage Δn ₁ ; one or more stages of stretching carried out in the preceding stage Birefringence at the time of completion DR ₁ ; One-stage or multiple-stage draw ratio DR ₂ performed in the previous stage; One-stage or multiple-stage draw ratio TDR performed in the latter stage TDR; Overall draw ratio 3. The distance between the blades (2) of the cutter roll (1)
The method for producing a polyester reticulated nonwoven fabric according to claim 2, wherein the method is used as 0.7 mm or more.