JP7399694B2 - molded sheet - Google Patents

Description

The present invention relates to a molded sheet with a special structure. The present invention particularly relates to a molded sheet that can easily and stably bind articles for a long period of time and that has high cushioning properties.

2. Description of the Related Art Rubber binding bands have been widely used for the purpose of bundling long and narrow articles, fastening the edges of wrapping paper, or attaching tags or price tags to articles. However, rubber bands generally have insufficient cushioning effects. Therefore, when frangible items are bound with rubber bands, they must be protected separately with paperboard, paper corrugation, or other cushioning material. In particular, the biggest problem with known rubber bands is a decrease in tensile strength due to permanent deformation of the rubber material. Even if the article is tied with the strong tightening force of the rubber at the beginning of binding the article, the binding may no longer serve its purpose after a long period of time.

In addition to rubber bands, belt-shaped tapes with hook-and-loop fasteners, plastic binding bands, cable ties, adhesive tapes, and the like can be used to bind articles. Belt-shaped tapes with hook-and-loop fasteners may have a weak binding force if dust adheres to the hook-and-loop fastener, and the hook-like hooks on the hook-and-loop fastener may adhere to the fiber surface of clothing, etc., staining the bondage item. Sometimes I put it away. Binding bands and cable ties generally have a narrow width and will sink into the article when attempting to securely fix the article, so they are not suitable for binding long or flexible articles. Furthermore, once binding bands and cable ties are tied together, they cannot be removed except by cutting, or cannot be easily untied. Adhesive tape sticks to bound articles, so it can maintain a strong binding force, but the adhesive may adhere to the articles and stain them.

In addition to the above-mentioned binding devices, band-shaped bodies made of polypropylene, polyamide, polyethylene terephthalate, etc., having various uneven patterns on the surface, are also widely used for the purpose of packaging articles. However, with such a band-like body, it is necessary to strongly pull and weld the end portion, and special equipment is required to bind the article. Therefore, it cannot be used as easily as a rubber band or the like.

Patent Document 1 discloses a thin annular body made of an elastomer and characterized by including a flat portion along the circumferential direction and a wavy portion along the orthogonal direction.

Patent Document 2 discloses a packaging sheet for a band-shaped body having concave portions and/or convex portions having similar shapes, and when the band-shaped body is rolled or folded into an annular shape and both ends come into contact with each other, the concave portion Disclosed is a packaging sheet characterized in that the convex portions and convex portions are positioned and arranged so as to fit into each other.

Special Publication No. 58-125461 Utility Model Publication No. 59-10263

Since the annular body of Patent Document 1 is made of an elastomer (ie, rubber), the disadvantages seen in the above-mentioned rubber band may occur. On the other hand, the packaging sheet of Patent Document 2 is attached/detached and locked by fitting the overlapping parts. However, the fitting force of the packaging sheet is insufficient, and there is a problem that the binding may come loose and the article may fall apart.

The present invention improves the shortcomings of the conventional binding devices as described above, and provides a molded sheet that is easy to perform binding operations, has high cushioning properties, has little reduction in initial tightening force over time, and can be repeatedly fitted and removed. The purpose is to provide

One embodiment of the present invention is a sheet formed by molding a resin composition containing an olefin resin, which has a loss tangent (tan δ) value at -20°C in dynamic viscoelasticity measurement of the resin composition. is 0.05 to 0.4, the sheet has a flat portion and a plurality of convex portions having the same shape, and the convex portion has a truncated cone shape.

In the molded sheet of the present invention, by considering the material of the molded sheet and the shape of the convex part, the convex part and the concave part fit together smoothly, and the fitted molded sheet does not easily come off and lasts for a long time. Items can be tied up stably. Further, the molded sheet of the present invention can be easily attached and detached when the need for binding is eliminated and can be used again to bind the article, so that it can be used repeatedly.

FIG. 1-a is a front view of the sheet of the embodiment. FIG. 1-b is a side view of a row of convex portions formed in the width direction of the sheet of the embodiment. FIG. 1-c is a side view of a row of convex portions formed in the longitudinal direction of the sheet according to the embodiment. FIG. 2 is an enlarged front view (2-a) and an enlarged side view (2-b) of the convex portion of the sheet of the embodiment. FIG. 3 is an enlarged side view of the sheet of the embodiment. FIG. 4 is a diagram illustrating an example of how to use the sheet according to the embodiment. FIG. 5 is a side view showing a state in which the sheets of the embodiment are overlapped at their ends and the convex portions are fitted. FIG. 6 is a graph showing temperature changes in the loss tangent (tan δ) of the resin compositions used in the sheets of Examples and Comparative Examples.

One embodiment is a sheet formed by molding a resin composition containing an olefin resin.
In this specification, thin film-shaped materials such as film or sheet-like materials are collectively referred to as "sheets" or "molded sheets."

In the embodiment, the olefin resin refers to a polymer compound obtained by polymerizing olefins, and is generally referred to as a polyolefin. Examples of the olefins to be polymerized include ethylene, propylene, butene, pentene, hexene, octene, nonene, and isomers thereof, and one type or a combination of two or more of these can be used. Olefin resins include ethylene resins such as high-density polyethylene, medium-density polyethylene, high-pressure low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene; isotactic polypropylene, atactic polypropylene, syndiotactic polypropylene, Propylene-based resins such as propylene-ethylene random copolymers, propylene-α-olefin random copolymers, and propylene block copolymers obtained by homopolymerizing propylene and then copolymerizing ethylene and propylene; α-olefin resins containing α-olefin as a main component; etc., and one type or a mixture of two or more of these can be used. That is, in the present specification, the term olefin resin includes a homopolymer, a copolymer, and a mixture thereof. In the embodiment, the resin composition refers to a resin mixture containing at least one type of olefin resin described above. In addition to the above-mentioned olefin resin, the olefin resin composition of the embodiment includes a stabilizer, a heat resistant agent, an antistatic agent, a lubricant, an antifogging agent, an antiblocking agent, a plasticizer, a dye, a pigment, an oil, a wax, Known additives for resin compositions, such as fillers, antioxidants, and neutralizing agents, can be appropriately blended.

In embodiments, the olefinic resin is selected from the group consisting of high pressure processed low density polyethylene (HP-LDPE), linear low density polyethylene (LLDPE), easily processable polyethylene (EPPE), and mixtures consisting of combinations thereof. It is particularly preferred that the Specifically, Novatec-LL (Japan Polyethylene), Novatec C6 (Japan Polyethylene), Ultrazex (Prime Polymer), Neozex (Prime Polymer), Evolu (Prime Polymer), Sumikasen L (Sumitomo Chemical), Sumikasen E (Sumitomo (chemistry) etc. can be used alone or in an appropriate mixture.

The resin composition used in the embodiment has a loss tangent (tan δ) value of 0.05 to 0.4, preferably 0.05 to 0.3, more preferably 0 at -20°C in dynamic viscoelasticity measurement. 0.05 to 0.2, particularly preferably 0.06 to 0.2. Dynamic mechanical analysis (referred to as "DMA") is the measurement of the mechanical properties of a sample by applying a time-varying strain or stress to the sample and measuring the resulting stress or strain. It's a method. DMA is used to analyze the viscoelastic properties of polymeric materials. In DMA, loss tangent is the ratio of loss modulus to storage modulus (E/E') or the ratio of loss shear modulus to storage shear modulus (G/G'), and is written as "tan δ". Ru. The tan δ value indicates how much energy the material absorbs when it is deformed, and is generally a value representing the viscosity of the material. In the DMA of the resin composition used in the embodiment, the value of tan δ at -20°C is 0.05 to 0.4, preferably 0.05 to 0.3, more preferably 0.05 to 0.2, particularly preferably is 0.06 to 0.2. The tan δ value at −20° C. is considered to be a measure of the adhesion force (adhesive force) between sheets molded from resin compositions when they come into contact with each other. Generally, when considering rubber components for tires, the grip characteristics of the tire are estimated from the magnitude of the tan δ value around -20°C, and the rolling characteristics of the tire are estimated from the magnitude of the tan δ value around 60°C. ("Novel solution polymerized SBR for high-performance tires", Imai et al., Sumitomo Chemical 1999-I). On the other hand, as the material for the sheet of the embodiment, it is considered suitable to use a resin composition mainly having high grip properties. Therefore, when considering the embodiments of the present invention, a resin composition will be selected using the tan δ value at -20°C in DMA as a guide, using the above-mentioned viewpoints regarding rubber members for tires. When the value of tan δ at -20°C of the resin composition is 0.05 to 0.4, when the convex portions of the sheets of the embodiment are fitted, the sheets attached to each other will not slip, so that these can be easily done. It doesn't come off. Therefore, articles can be reliably bound by the sheet of the embodiment. Further, when it is no longer necessary to bind the article, the binding can be easily released by removing the fitting of the convex portion.

The sheet of the embodiment has a flat portion and a plurality of convex portions having the same shape, and the convex portions have a truncated cone shape. A frustum is a three-dimensional object obtained by removing a similarly reduced cone that shares a vertex from a cone. A figure obtained by removing a similarly reduced cone that shares a vertex from a cone is a truncated cone, and a figure obtained by removing a similarly reduced cone that shares a vertex from a pyramid is a truncated pyramid. In this embodiment, the convex portion may have any shape of a truncated pyramid, but is particularly selected from the group consisting of a truncated cone, a truncated elliptic pyramid, a truncated triangular pyramid, a truncated square pyramid, a truncated pentagonal pyramid, and a truncated hexagonal pyramid. The convex portion having a truncated cone shape is easy to mold and is suitable for exhibiting the fitting performance described below.

In the sheet of the embodiment, the convex portions are arranged in a row with flat portions having a predetermined width interposed between them. That is, in the sheet of the embodiment, a plurality of convex portions having substantially the same shape are arranged in rows in the length direction of the sheet, and each row is separated by a flat portion having a predetermined width. Preferably, the plurality of convex portions are arranged in rows not only in the length direction of the sheet but also in the width direction of the sheet. Further, it is preferable that the rows in the width direction of the sheet formed by the plurality of convex portions are also separated by flat portions having a predetermined width. The specific shape of the sheet of the embodiment will be described in detail later using drawings.

A specific example of the sheet of the embodiment will be described in detail using the drawings. Note that the sheet shown in the drawings is an example for embodying the present invention, and is not intended to limit the form of the sheet of the present invention.

FIG. 1 is a drawing of a sheet according to an embodiment. Figure 1-a is a front view (partial) of the seat, Figure 1-b is a side view taken along line a-a in Figure 1-a, and Figure 1-c is a view of the seat in Figure 1-a. FIG. 3 is a side view taken along line bb. In FIG. 1, 10 is a sheet, 11 is a convex portion, and 12 and 13 are flat portions. A plurality of convex portions 11 are formed on the sheet 10, and all have the same shape. The convex portions 11 are formed in rows in the length direction of the sheet (vertical direction in FIG. 1-a) via the flat portions 12, and also in the width direction of the sheet (horizontal direction in FIG. 1-a). They are formed in a row with the flat portion 13 in between. Each of the flat portions 12 between the rows formed in the longitudinal direction of the sheet has a predetermined width. That is, in FIG. 1-b, the widths of the flat portions 12 between the convex portions 11 are all the same. On the other hand, each of the flat portions 13 between the rows formed in the width direction of the sheet has a predetermined width. That is, in FIG. 1-c, the widths of the flat portions 13 between the convex portions 11 are all the same.

FIG. 2 is an enlarged view of the convex portion of the sheet of the embodiment. In FIG. 2, 21 is a convex portion, and 22 is a flat portion. 2-a is a view of the convex portion 21 seen from above, and FIG. 2-b is a view of the convex portion 21 of FIG. 2-a viewed from the side, and a side view along line a-a of FIG. It is a diagram. As is clear from FIG. 2-a, the sheet is formed with a convex portion 21 in the shape of a truncated quadrangular pyramid. The convex portion 21 is formed between two flat portions 22 having the same width.

FIG. 3 is a side view (enlarged) of the sheet of FIG. 1 taken along line aa. In FIG. 3, 31 is a convex portion and 32 is a flat portion. The convex portion 31 is formed between flat portions 32 having the same width.

FIG. 4 is a diagram illustrating an example of how to use the sheet according to the embodiment. As shown in FIG. 4, the sheet of the embodiment can be rolled up, both ends overlapped, and the convex portions can be fitted together. This locks both ends of the sheet, so that the article can be tied tightly within the formed loop. The sheet of the embodiment can be freely cut and used according to the shape and size of the article to be bound. In addition, in FIG. 4, of the rows of convex portions of the sheet according to the embodiment, two rows at one end and two rows at the other end are fitted, but depending on the shape and size of the article to be bound, More rows can be mated together, or just one row can be mated together.

FIG. 5 is an enlarged view of a part of the side surface of the sheet shown in FIG. 4 along line cc. In FIG. 5, 51 is a convex portion and 52 is a flat portion. In FIG. 5, the upper sheet and the lower sheet are depicted as being separated from each other, but in reality, these sheets are substantially in close contact with each other. The convex portion 51 is formed between flat portions 52 having the same width. When the sheet of FIG. 4 is rolled up, the convex portions 51 fit into each other at both overlapping ends, and the flat portions 52 come into close contact with each other, so that both ends of the sheet are locked.

As shown in FIG. 4 or 5, when the sheet of this embodiment is used for binding articles, the convex portions 51 at both ends of the overlapping sheets fit together and do not easily come off. is important. The sheet of the embodiment is formed by molding a resin composition containing an olefin resin, and in dynamic viscoelasticity measurement of the resin composition, the loss tangent (tan δ) value at -20°C is 0.05 to 0.4. This makes it difficult for the convex portions 51 that are fitted into each other to come off each other. In the dynamic viscoelasticity measurement of a resin composition, the value of tan δ at -20°C is, as mentioned above, the force (adhesive force) with which sheets molded from the resin composition adhere to each other when they come into contact with each other. This is a guideline. When the value of tan δ of the resin composition at -20° C. is 0.05 to 0.4, the fitted convex portions 51 and the closely contacted flat portions 52 adhere to each other and do not easily come off. Further, in dynamic viscoelasticity measurement of the resin composition, it is particularly preferable that the difference between the tan δ value at -30°C and the tan δ value at -10°C is 0.10 or less.

On the other hand, in the sheet of the embodiment, since the convex portion 51 has a truncated cone shape, when the sheet is rolled up and the convex portion 51 at one end is fitted to the back surface of the convex portion 51 at the other end, It can be fitted smoothly. The shape of the convex portion 51 is a truncated cone, that is, the area of the upper base is narrower than that of the lower base, making it a constricted shape. can be easily fitted. The shape of the convex portion may be any frustum shape, but it is particularly preferable to select it from the group consisting of a frustum of a cone, a frustum of an ellipse pyramid, a frustum of a triangular pyramid, a frustum of a square pyramid, a frustum of a pentagonal pyramid, and a frustum of a hexagonal pyramid.

The sheet of the embodiment is produced by forming a flat sheet using an appropriate resin composition by a conventional sheet processing method and sheet manufacturing method, and then forming a male mold (core) having the shape of the convex portion to be formed. ) and a female die (cavity) that engages with the convex part by forming the convex part by a thermoforming method such as a compression molding method or a vacuum forming method. The sheet may be formed using a combination of male and female molds, or may be performed using only male molds or only female molds. Alternatively, by conventionally used sheet processing methods and sheet manufacturing methods, a sheet-like resin composition extruded from a die is passed between a pair of uneven shape forming rolls to form an uneven shape before solidifying. It is also possible to produce sheets with

[Example]
Sheets with convex portions were manufactured using different resins, and the handling properties and fitting characteristics of the sheets were evaluated.
The resins used were EPPE (Excellen GH030, Sumitomo Chemical), LDPE (Sumikasen F101, Sumitomo Chemical), EP rubber (ethylene propylene rubber) (Tafmer PN3560, Mitsui Chemicals), and PP (polypropylene) (Sumitomo Noblen D101, Sumitomo Chemical). )Met. Table 1 shows the tan δ values of each resin.
Each resin was molded by T-die molding to obtain a resin sheet (flat) with a thickness of 500 μm. Next, each obtained flat resin sheet was passed between a roller having a core having a shape of a convex portion and a roller having a cavity that engaged with the roller to form a convex portion. The convex part had a rectangular shape with a lower base of 4 mm x 5 mm, an upper base of a rectangle of 1.5 mm x 2.2 mm, and a truncated quadrangular pyramid with a height of 3.2 mm.

The handling properties of the sheets are evaluated as "good" if the sheet is flexible and easy to fit when rolling each sheet and overlapping the convex and concave parts, and if the sheet is hard and difficult to wrap, or if it stretches when pulled. Items with poor workability were rated as ``defective.''

The fitting characteristics of the sheets were evaluated by rolling up each sheet and overlapping and fitting the ends. At this time, if one convex part on one end and one convex part on the other end can be fitted and fastened, it is considered "good", and two or more convex parts on one end and one convex part on the other end are considered "good" Those in which two or more convex portions could be fitted and fastened were evaluated as "fair," and those that were difficult to fasten or could not be fastened were evaluated as "impossible."

FIG. 6 shows the tan δ temperature characteristics of each resin used in Examples 1 and 2 and Comparative Examples 1 and 2. The sheets of Examples 1 and 2 using resins with a tan δ value of 0.05 to 0.4 at −20° C. had good handling properties and fitting characteristics. The sheets of Comparative Examples 1 and 2, in which the value of tan δ at −20° C. was not within the above range, had difficulty in handling and fitting characteristics. Examining FIG. 6, it can be seen that in the graph of the temperature characteristics of tan δ of the resins of Examples 1 and 2, the gradient from -30°C to -10°C is small. As mentioned above, the value of tan δ is a measure of the adhesiveness of the resin, but the value of tan δ particularly around -30°C to -10°C is considered to influence the grip of the resin at room temperature. As in Examples 1 and 2, resins having a tan δ value within a specific range in this temperature range have high grip properties at room temperature. Therefore, when convex portions formed of such resin are fitted together, the resins adhere to each other without slipping, and it is thought that the fitted convex portions become difficult to come off.

Claims (4)

A sheet formed by molding a resin composition containing an olefin resin,
In the dynamic viscoelasticity measurement of the resin composition, the loss tangent (tan δ) value at -20°C is 0.05 to 0.4,
In the dynamic viscoelasticity measurement of the resin composition, the difference between the tan δ value at -30°C and the tan δ value at -10°C is 0.10 or less,
The sheet has a flat portion and a plurality of convex portions having the same shape,
The convex portion has a frustum shape.
Said sheet. The olefin resin is selected from the group consisting of high-pressure low density polyethylene (HP-LDPE), linear low density polyethylene (LLDPE), easily processable polyethylene (EPPE), and mixtures consisting of combinations thereof. The sheet according to claim 1. The sheet according to claim 1 or 2, wherein the convex portions are arranged in a row with the flat portions having a predetermined width interposed therebetween. The sheet according to any one of claims 1 to 3, wherein the frustum is selected from the group consisting of a frustum of a cone, a frustum of an ellipse, a frustum of a triangular pyramid, a frustum of a square pyramid, a frustum of a pentagonal pyramid, and a frustum of a hexagonal pyramid.

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