JPH11156986A - Flat reticular body and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the surface flatness satisfactory and increase the adhesive strength between uniaxially orientated bodies by flattening a reticular body obtained by laminating uniaxially orientated bodies as a weft and a warp, of thermoplastic resin selected from a split web, a slit web and a uniaxially orientated tape or processing the bodies otherwise, in such a manner that the orientation areas cross each other. SOLUTION: A uniaxially orientated body used for forming a flat reticular body is a split web 1 obtained by uniaxially orientating a film longitudinally, then splitting the fiber in the longitudinal direction and broadening the width of the film, a slit web 6 obtained by cutting numerous slits in the width direction of the film and uniaxially stretching the film laterally or a uniaxially orientated tape. Each of these is of a three-tier structure comprising laminated thermoplastic resins. Further, a reticular body constructed of the slit web 6 and the split web 1 laminated as a weft and a warp 1 in such a manner that their orientated axes cross each other, is pressed by a pair of rolling rolls which are rotated at a uniform surface velocity. Consequently, the thick wall part is collapsed to be flattened. Thus it is possible to broaden the adhesive area of an intersection part and thereby increase the adhesive strength significantly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat reticulated body obtained by laminating or weaving a uniaxially oriented body made of a thermoplastic resin, and a method for producing the same.

[0002]

BACKGROUND OF THE INVENTION It has already been reported by the applicant of the present invention that a reinforced mesh body, which is a kind of nonwoven fabric or woven fabric, can be obtained by weft laminating or weaving a uniaxially oriented body made of a thermoplastic resin. I have. As the uniaxially oriented body, (a) after uniaxially or vertically stretching the film,
Examples include a split web split in the stretching direction, (b) a slit web formed by forming a large number of slits in the film in a longitudinal or horizontal direction, and then uniaxially stretched in the slit direction, and (c) a uniaxially oriented tape. Such meshes are made of paper,
By bonding with aluminum foil or the like, it is used as a reinforcing material for various kinds of packaging materials, or as a simple substance, used as a reinforced mesh material having air permeability.
However, since the net is formed by laminating or weaving a uniaxially oriented body, if the thickness of the uniaxially oriented body constituting the net is large, unevenness occurs on the surface of the net, and particularly the laminating or weaving is performed. The thickness of the web at the intersection of the formed web increases and the product lacks smoothness. For this reason, not only does it have an adverse effect on the thermocompression bonding when laminated with other materials such as paper and film, but also the thermocompression-bonded product lacks flatness as a product, and has various printing characteristics and the like. Inconvenience occurs.

[0003] The irregularities on the surface of the mesh body as described above are particularly remarkable in a nonwoven fabric obtained by laminating the above-mentioned slit web with another uniaxially oriented body. The slit web is inevitably thicker from the viewpoint of manufacturing technology, and the fibers of the web are thin. Therefore, when the webs are laminated one after another, irregularities on the surface of the slit web side are conspicuous. To improve this has been a problem for some time, but only by changing the manufacturing conditions of the slit web, the extent to which the fibers of the web can be flattened is small and limited.

[0004] As a method for rolling a net, a net formed by integrally combining vertical and horizontal filaments made of a thermoplastic resin is disclosed in the invention by the present applicant (Japanese Patent Application Laid-Open No. 62-97829). A method is disclosed in which a pair of rolling rolls rotating in opposite directions rotate in the longitudinal direction at a temperature lower than the crystal melting point or softening point of the thermoplastic resin.
In this method, the two surface speeds of the pair of rolling rolls are set to different sizes, and the ratio of the two surface speeds is set to be equal to the target rolling ratio, and the longitudinal stretching is performed about 3 to 8 times. This method aims at improving the strength of the net by aligning the meshes by stretching, and is characterized by changing the surface speed of the rolling roll. However, as described above, when rolling is performed at a temperature lower than the melting point or softening point of the thermoplastic resin constituting the surface of the reticulated body, the reticulated body obtained by laminating or weaving the uniaxially stretched body has a uniaxially oriented body. The mutual adhesive strength decreases in reverse.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, the present invention flattens a net formed by laminating or weaving a uniaxially oriented body made of a thermoplastic resin, and has excellent surface smoothness. An object of the present invention is to provide a flat net-like body having improved adhesion strength between uniaxially oriented bodies and a method for producing the same.

[0006]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve the above-mentioned object, and as a result, have found that a net-like body obtained by laminating or weaving a specific uniaxially oriented body made of a thermoplastic resin. By rolling, the thick portion of the net is flattened, and a net with a smooth surface is obtained,
The inventors have found that the adhesive strength at the intersections is improved, and completed the present invention. That is, the first of the present invention is the following (a):
A flat net formed by flattening a net formed by laminating or weaving at least one kind of thermoplastic resin uniaxially oriented member selected from the group of (b) and (c) so that the orientation axes intersect. It is about. (A) A split web that is split in the stretching direction after stretching the film uniaxially in the vertical or horizontal direction. (B) A slit web that is uniaxially stretched in the slit direction after inserting a number of slits in the film in the vertical or horizontal direction. Uniaxially Oriented Tape The second aspect of the present invention relates to a method for producing a flat mesh body, wherein the flat body is flattened by a pair of rolling rolls rotating at a constant speed. Further, the third aspect of the present invention
Is a multilayer uniaxially oriented body formed by laminating a layer of a second thermoplastic resin having a lower melting point than the first thermoplastic resin on one or both sides of a layer of the first thermoplastic resin as the uniaxially oriented body. And the first thermoplastic resin is higher than the melting point of the second thermoplastic resin.
Rolling in a temperature range lower than the melting point of the thermoplastic resin of the present invention.

Hereinafter, the present invention will be described in detail. The network to be flattened is not particularly limited as long as it is a laminate of a gas-permeable oriented body, and is a laminate of a uniaxially or biaxially oriented perforated film and a punching film made of a thermoplastic resin. It is also possible to use a nonwoven fabric or a woven fabric obtained by laminating or weaving at least one kind of uniaxially oriented material selected from the group consisting of a split web, a slit web and a uniaxially oriented tape so that the orientation axes intersect. Cloth and those obtained by further combining them are used. The split web may be a single layer, but preferably, a multi-layer film composed of at least two layers produced by extrusion such as a multilayer inflation method and a multilayer T-die method is used in a longitudinal direction (length direction) or a lateral direction (width direction). ), A uniaxially oriented net-like film formed by intermittently forming a large number of tears in the stretching direction and widening the slit web. It is a uniaxially oriented net-like film that is stretched in the slit direction after making a cut. In addition, uniaxially oriented tape (yarn)
The monolayer or multilayer film is uniaxially stretched in the longitudinal or transverse direction before and / or after cutting.

More specifically, as the nonwoven fabric and the woven fabric made of the uniaxially oriented body, for example, a nonwoven fabric obtained by laminating and thermally bonding a split web, a nonwoven fabric obtained by laminating a slit web and thermocompressing, a split web and a slit web are used. Examples of the nonwoven fabric include a nonwoven fabric that is laminated and thermocompression-bonded, a nonwoven fabric in which a split web or slit web and a uniaxially oriented tape are laminated so that the orientation axes intersect, or a woven fabric in which a uniaxially oriented tape is woven. As the nonwoven fabric made of a uniaxially oriented body, it is preferable that at least one kind of uniaxially oriented body selected from a split web, a slit web, and a uniaxially oriented tape is laminated in such a manner that the orientation axes intersect, as described above. May be laminated with the orientation axes randomly or in the same direction. Furthermore, these woven fabrics or nonwoven fabrics can be used in a composite laminate.

In the above uniaxially oriented body, a second thermoplastic resin layer having a melting point lower than that of the first thermoplastic resin is provided as an adhesive layer on at least one surface of the crystalline first thermoplastic resin layer. It is desirable that the multilayer uniaxially oriented body is formed by the above method. The second thermoplastic resin not only serves as an adhesive layer between the uniaxially oriented bodies when weftly laminating or weaving the above uniaxially oriented bodies (a) to (c), but also forms the flat net-like body with another material. It also acts as an adhesive layer when laminating.

As the first thermoplastic resin, homopolymers of α-olefins such as high- and medium-density polyethylene, polypropylene, polybutene-1, poly-4-methylpentene-1 and polyhexene-1, propylene- Examples include polyolefins such as α-olefin copolymers such as ethylene copolymers, polyamides, polyesters, polycarbonates, and polyvinyl alcohols.

The second thermoplastic resin having a lower melting point than the first thermoplastic resin includes high-, medium-, and low-density polyethylene, linear low-density polyethylene, ultra-low-density polyethylene, and ethylene-vinyl acetate copolymer. Copolymers, ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, ethylene-acrylic acid ester copolymers such as ethylene-ethyl acrylate copolymers, and ethylene-methacrylic acids such as ethylene-ethyl methacrylate copolymers Examples include acid ester copolymers, ethylene- (maleic acid or its ester) copolymers, propylene-based polymers such as polypropylene and propylene-ethylene copolymers, and polyolefins modified with unsaturated carboxylic acids. Further, a mixture of these resins and other polyolefin-based resins may be used. For example, a high-density polyethylene or a polyethylene such as an ethylene-α-olefin copolymer may be used as a random copolymer of propylene and ethylene or 1-butene. What mixed the base resin is used.

For reasons of manufacturing and for preventing a decrease in strength increased by stretching or rolling of the uniaxially oriented body, the second
The difference between the melting points of the thermoplastic resin and the first thermoplastic resin is preferably 5 ° C. or more, more preferably 1 ° C.
The range is from 0 to 50 ° C.

The specific resin composition of the multilayer film includes high-density polyethylene (HDPE) / low-density polyethylene (LDPE), LDPE / HDPE / LDPE, H
DPE / ethylene-vinyl acetate copolymer (EVA), E
VA / HDPE / EVA, polypropylene (PP) / propylene-ethylene copolymer (PEC), PEC / PP
/ PEC, polyester (PEs) / copolyester (CPEs), CPEs / PEs / CPEs, and the like.

As a method for producing a flat net-like body in the present invention, a general method using a pair of rolling rolls rotating at a constant speed is used. Here, “constant velocity” means “constant surface velocity”. In the rolling used in the present invention, the purpose is to flatten the thick portion of the net by pressing, and not the purpose of stretching. Therefore, it is not necessary to provide a difference between the two surface speeds of the pair of rolling rolls as in the above invention. Rather, if the speed is changed, there is a concern that a plurality of uniaxially oriented bodies to be laminated may be shifted from each other, which is not preferable. When the uniaxially oriented body forming the network is made of a single thermoplastic resin, the pressing must be performed at a temperature equal to or higher than the melting point of the raw thermoplastic resin. When pressed at such a temperature, the reticulated body is flattened, but the orientation effect as a uniaxially oriented body must be reduced. On the other hand, if the pressing is performed at a temperature lower than the melting point, the adhesive strength between the vertically laminated or woven uniaxially oriented bodies is reduced, which adversely affects the product properties. Therefore, pressing is performed by selecting a temperature which is equal to or higher than the melting point of the raw material thermoplastic resin and which does not break the mesh of the net-like body. The uniaxially oriented body is provided on one side or both sides of the first thermoplastic resin layer with a second thermoplastic resin having a lower melting point than the first thermoplastic resin.
In the case of a uniaxially oriented body having a multilayer structure formed by laminating layers of a thermoplastic resin, the temperature is higher than the melting point of the second thermoplastic resin and lower than the melting point of the first thermoplastic resin. Rolling is performed under pressure.

By pressing as described above, the thick portion of the net-like body is flattened, and the unevenness on the surface becomes smooth. The thick portion to be crushed is a portion of the intersection where the thickness has been increased particularly when laminated or woven. If necessary, portions other than the intersections may be pressed and flattened. However, if the portions other than the intersections are flattened, the strength of the net itself decreases. Therefore, usually, the pressing is performed by adjusting the interval between the rolling rolls so as to obtain a flat mesh body in which only the thick portion at the intersection is crushed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 (A) is a partially enlarged perspective view showing a split web in which a film is uniaxially stretched vertically, split vertically, and expanded as an example of a uniaxially oriented body forming a flat network of the present invention. It is. The split web 1 made of a thermoplastic resin is made of a first thermoplastic resin and a second thermoplastic resin having a melting point lower than that of the first thermoplastic resin, using a multilayer inflation method, a multilayer T
After stretching a multilayer film composed of at least two layers manufactured by extrusion molding such as a die method in the longitudinal direction (length direction) to an elongation ratio of 1.1 to 15, preferably 3 to 10, it is staggered in the same direction. It is split (split processing) using a splitter to form a net-like film, which is further expanded to a predetermined width. The split web 1 is a uniaxially oriented body having strength in the longitudinal direction over the entire width direction. Also,
In the figure, 2 is a trunk fiber and 3 is a branch fiber. FIG. 1B is an enlarged perspective view of a portion B in FIG. 1A, and the split web 1 has a second thermoplastic resin layer 5 laminated on both surfaces of a first thermoplastic resin layer 4. It has a three-layer structure.

FIG. 2A shows another example of a uniaxially oriented body for forming a flat network according to the present invention, which shows a slit web formed by forming a plurality of slits in a film and then uniaxially stretching in a lateral direction. It is an expansion perspective view. A slit web 6 made of a thermoplastic resin is formed by forming intermittent slits such as staggered in a lateral direction (width direction), for example, in parallel with a hot blade or the like in a portion of the multilayer film except for both ears. Stretching ratio in the lateral direction is 1.1 to 15, preferably 3 to 1.
It is a uniaxially oriented body stretched to 0 and has strength in the transverse direction. Preferably, the multilayer film is longitudinally 1.
After finely orienting by about 1 to 3 times by rolling or the like, slit processing is performed in a staggered manner in the horizontal direction with a hot blade, and horizontal stretching is performed. FIG.
FIG. 2B is an enlarged perspective view of a portion B in FIG. 2A, and a slit web 6 has a second thermoplastic resin layer 5 laminated on both surfaces of a first thermoplastic resin layer 4. It has a three-layer structure.

FIG. 3 is a partially enlarged perspective view showing a uniaxially oriented tape as another example of the uniaxially oriented body. The uniaxially oriented tape 7 made of a thermoplastic resin is made of a first thermoplastic resin and a second thermoplastic resin having a melting point lower than that of the first thermoplastic resin, using a multilayer inflation method and a multilayer T-die method. Before and / or after cutting, a multilayer film composed of at least two layers produced by extrusion molding, etc., is uniaxially oriented in an elongation ratio of 1.1 to 15, preferably 3 to 10, and cut to obtain a multilayer film. It was a stretched tape. The uniaxially oriented tape 7 also has a three-layer structure in which the second thermoplastic resin layer 5 is laminated on both surfaces of the first thermoplastic resin layer 4 in the same manner as described above.

FIGS. 4 to 6 show specific examples of the mesh before rolling used in the present invention. FIG. 4 is a partial plan view of the nonwoven fabric 8 obtained by laminating the slit web 6 and the split web 1 in a weft manner. FIG. 5 is a partial plan view of a nonwoven fabric 9 in which two sets of uniaxially oriented tapes 7 are arranged in parallel, and FIG.
FIG. 2 is a partial perspective view of a woven fabric 10 in which a uniaxially oriented tape 7 is woven. As a specific example of the nonwoven fabric 8, "Nisseki Warif (T)
HS-T "(registered trademark, manufactured by Nisseki Plast Co., Ltd.).

FIG. 7 is a partially enlarged perspective view of the intersection of the nonwoven fabric 8 (FIG. 4) before rolling, in which the slit web 6 and the split web 1 are laminated so that their orientation axes intersect.
The slit web 6 is thinner and thicker than the split web 1, and the thickness particularly increases at the intersection of the trunk fiber 2 of the split web 1 and the slit web 6.

FIG. 8A is a longitudinal sectional view taken along line AA of FIG. 7, and FIG. 8B is a longitudinal sectional view taken along line BB of FIG. FIGS. 8C and 8D are longitudinal sectional views showing the state after rolling in FIGS. 8A and 8B, respectively. Since the fibers of the slit web are thin and thick, a remarkable unevenness occurs on the surface of the slit web side in the mesh body in which the slit web and the split web are laminated, but a pair of rolling rolls rotating the mesh body at a constant speed. 8 by crushing the thick part by pressing
As shown in (C) and (D), the split web 1
Is inserted into the slit web 6 and is flattened. As a result, the bonding area at the intersection is increased, and the bonding strength is significantly improved.

[0022]

<Example 1> HD as a first thermoplastic resin
PE (melting point 129 ° C.) was used as the second thermoplastic resin and L
A net-like nonwoven fabric “Nisseki Warif” formed by laminating a split web, which is a uniaxially oriented body having a three-layer structure using DPE (melting point 109 ° C.), and a slit web, which is a uniaxially oriented body made of the same resin as the above split web. (T) HS-T "
(Registered trademark, manufactured by Nisseki Plast Co., Ltd.). The preheating roll is 100 ° C, and the rolling roll is the HDP
120 lower than the melting point of E and higher than the melting point of LDPE
° C and a linear pressure of 13 kgf / c using a rolling mill equipped with a pair of rolling rolls rotating at a constant speed with a roll width of 500 mm.
m, and the rolling speed was 5 m / min. Table 1 shows changes in physical properties due to rolling.

<Comparative Example 1> [Nisseki Warif]
(T) HS-T ”and the temperature of the rolling roll was set to L
Example 1 except that the temperature was 100 ° C. lower than the melting point of DPE.
The rolling was performed under the same conditions as in the above. Table 1 shows the physical property values.

[0024]

[Table 1]

As can be seen from Table 1, in Example 1, as a result of the rolling, the thickness of the intersection of the split web and the slit web was reduced by about 30%, the physical properties of the product were not reduced, and the adhesive strength was not increased. The improvement was significantly increased by about 50%.

[0026]

The flat reticulated body obtained by the production method of the present invention has excellent surface smoothness, so that it has good thermocompression bonding properties with other materials, and is suitable for printing on the surface. The characteristics are also excellent. In addition, since the intersections between the uniaxially oriented bodies laminated or woven when forming the net-like body are crushed by the pressing using the rolling rolls to increase the bonding area, the bonding strength is remarkably improved. Furthermore, winding wrinkles that occur when the surface is not smooth are unlikely to occur.

[Brief description of the drawings]

1 (A) is a partially enlarged perspective view of a split web, and FIG. 1 (B) is an enlarged perspective view of a portion B in FIG. 1 (A).

2 (A) is a partially enlarged perspective view of a slit web, and FIG. 2 (B) is an enlarged perspective view of a portion B in FIG. 2 (A).

FIG. 3 is a partially enlarged perspective view of a uniaxially oriented tape.

FIG. 4 is a partial plan view of a nonwoven fabric obtained by laminating a slit web and a split web in a weft manner.

FIG. 5 is a partial plan view of a nonwoven fabric laminated with a uniaxially oriented tape.

FIG. 6 is a partial perspective view of a woven fabric woven with a uniaxially oriented tape.

FIG. 7 is an enlarged perspective view of an intersection portion of the nonwoven fabric shown in FIG.

8 (A) is a longitudinal sectional view taken along line AA in FIG. 7, and FIG. 8 (B) is a longitudinal sectional view taken along line BB in FIG. 7; FIGS. 8 (C) and 8 (D). In FIG. 8 (A)
It is a longitudinal cross-sectional view which shows the state after flattening of (B).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Split web 2 Trunk fiber 3 Branch fiber 4 First thermoplastic resin layer 5 Second thermoplastic resin layer 6 Slit web 7 Uniaxially oriented tape 8, 9 Nonwoven fabric 10 Woven fabric

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29L 28:00

Claims (3)

[Claims] 1. A monoaxially oriented body made of at least one thermoplastic resin selected from the following groups (a), (b) and (c), laminated or woven so that the orientation axes intersect. A flat net formed by flattening a net. (A) A split web that is split in the stretching direction after stretching the film uniaxially in the vertical or horizontal direction. (B) A slit web that is uniaxially stretched in the slit direction after inserting a number of slits in the film in the vertical or horizontal direction. Uniaxially oriented tape 2. A monoaxially oriented body made of at least one thermoplastic resin selected from the group consisting of (a), (b) and (c) below, laminated or woven so that the orientation axes intersect. A method for producing a flat net, comprising flattening the net using a pair of rolling rolls rotating at a constant speed. (A) A split web that is split in the stretching direction after stretching the film uniaxially in the vertical or horizontal direction. (B) A slit web that is uniaxially stretched in the slit direction after inserting a number of slits in the film in the vertical or horizontal direction. Uniaxially oriented tape 3. The uniaxially oriented body is formed by laminating a second thermoplastic resin layer having a melting point lower than that of the first thermoplastic resin on one or both sides of the first thermoplastic resin layer. 3. The method according to claim 2, wherein rolling is performed in a temperature range higher than the melting point of the second thermoplastic resin and lower than the melting point of the first thermoplastic resin, using a multilayer uniaxially oriented body. .