JPH0631879A - Tire packaging - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a tire packaging material that does not stretch when used as a packaging material, does not cause color transfer, and can be manufactured at low cost. [Structure] A packaging material obtained by stretching a laminated film in which an intermediate layer is made of an aliphatic polyamide resin and both outer layers are made of a polyolefin resin in a longitudinal direction by 2 to 5 times.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a tire packaging material. More specifically, the present invention relates to a stretched laminated film which is suitable for tire wrapping, which has high strength, is difficult to stretch during winding, and is advantageous in terms of cost.

[0002]

2. Description of the Related Art Conventionally, tire packaging has been carried out by laminating a polyester (PET) film and paper to form a laminated paper or a linear low density polyethylene (L-LD).
It is carried out by winding a monolayer film or the like uniaxially stretched on a tire in a gaiter shape.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
Laminated paper and paper are complicated in manufacturing process, and have many steps. Even when scrap is collected, paper and synthetic resin, which are completely different materials, are combined, so they are recycled. The problem was that things were very difficult. In addition, the monolayer film obtained by uniaxially stretching L-LD,
Although it is stretched, the strength in the machine direction is weak, and there is a problem that it is easily stretched. Therefore, there is no choice but to increase the film thickness,
There was a problem that it was disadvantageous in terms of cost and it was difficult to wind it. In addition, there is also a defect that the packaging material is discolored to black due to the shift of the anti-aging agent or the like blended in the tire to the packaging material, and the printing or the like applied to the packaging material becomes invisible.

[0004]

Means for Solving the Problems The inventors of the present invention have made extensive studies to produce a packaging film in which the above-mentioned problems of conventional tire wrap films have been solved. As a result, an aliphatic polyamide resin and a polyolefin-based film have been obtained. By using a special laminated film made of resin, the above-mentioned problems are solved, and it is found that a packaging material (film or sheet) for tire wrapping, which has high strength, is hard to be stretched during winding, and is advantageous in cost, can be obtained. The invention was reached.

That is, the gist of the present invention is a packaging material for a film or sheet used for packaging a tire, which is a laminated film in which a polyolefin resin layer is disposed on both sides of an intermediate layer made of an aliphatic polyamide resin or A tire packaging material characterized by being obtained by stretching a sheet 2 to 5 times in the longitudinal direction. A film- or sheet-like packaging material used for packaging a tire, wherein a laminated film or sheet in which a polyolefin-based resin layer is arranged on both sides of an intermediate layer made of an aliphatic polyamide resin is 2 to 2 in the longitudinal direction.
The tire packaging material is characterized by being obtained by stretching it 5 times.

The present invention will be described in detail below. The packaging material of the present invention (hereinafter sometimes referred to as "packaging film") has at least three or more layer constitutions including outer and inner layers which are both surface layers and an intermediate layer therebetween, and is basically an outer layer. / Intermediate layer / inner layer, or three layers or outer layer / adhesive layer / intermediate layer / adhesive layer / inner layer.

Examples of the polyolefin resin constituting the outer layer and inner layer of the packaging film include linear low density polyethylene, branched low density polyethylene, high density polyethylene, polypropylene and the like, or a mixture thereof. Among them, polypropylene resin and linear low density polyethylene are preferable.

The type of polypropylene resin is not particularly limited and may be a propylene homopolymer or a copolymer of ethylene and propylene. Examples of the propylene homopolymer include isotactic polypropylene, syndiotactic polypropylene, and atactic polypropylene, with isotactic polypropylene being particularly preferred. Further, the copolymer of propylene and other components such as ethylene may be either a random copolymer or a block copolymer. The physical properties of this polypropylene resin may be selected according to various uses, conditions, etc., but the melt flow rate (MFR) is 0.5.
To 10 g / 10 min, a density 0.89~0.91g / cm ³
Are preferred. Melt flow rate is JIS K
According to 6758, it was measured at 230 ° C. under a load of 2.16 kg.

The linear low density polyethylene used in the present invention is a copolymer of ethylene and another α-olefin, and is different from the conventional low density polyethylene resin produced by the high pressure method. The linear low density polyethylene is, for example, copolymerized with ethylene and other α-olefins such as butene, hexene, octene, decene, and 4-methylpentene-1 in an amount of about 4 to 17% by weight, preferably about 5 to 15% by weight. It was produced using a Ziegler-type catalyst or Phillips-type catalyst used in the production of medium- and low-pressure method high-density polyethylene.The conventional high-density polyethylene is made into a short branched structure by a copolymerization component, and the density is also Use short chain branching to properly reduce 0.91
It is about 0.95 g / cm3, which is a polyethylene having a structure that is more linear than conventional low-density polyethylene and more branched than high-density polyethylene.

The linear low density polyethylene used in the present invention has a melt flow rate measured at 190 ° C. of 0.1 to 10 g / 10 minutes, preferably 0.5 to 3 g / 1.
It is in the range of 0 minutes and the density is 0.915 to 0.93.
5 g / cm ³ preferably 0.918 to 0.925 g / c
Those in the range of m ³ are preferably used. If necessary, the linear low-density polyethylene may be blended with the high-pressure low-density polyethylene described below.

As the branched low-density polyethylene, an ordinary high-pressure polyethylene, that is, an organic peroxide or a radical generator such as oxygen is used, and the pressure is 1000 to 3000.
A product obtained by homopolymerizing ethylene or copolymerizing ethylene with another copolymerization component under conditions of kg / cm ² and a temperature of 150 to 400 ° C. is used. As a copolymerization component, propylene, butene, hexene, octene, 4-
Α-olefins such as methylpentene-1, vinyl acetate,
Examples thereof include vinyl compounds such as ethyl acrylate and methyl acrylate. The copolymerization amount of the copolymerization component is 0.5 to 18% by weight, preferably about 2 to 10% by weight.

The blending ratio of linear low density polyethylene (LLD) and branched low density polyethylene LD is LLD50.
The LD is preferably in the range of 50 to 0 parts by weight with respect to 100 parts by weight. By blending an appropriate amount of branched low-density polyethylene, the moldability at the time of film formation described later is improved.

On the other hand, examples of the aliphatic polyamide which constitutes the intermediate layer of the packaging film of the present invention include nylon-6, nylon-6,6, nylon-6,10 and nylon-6.
/ 6,6 copolymer, nylon-6 / 6,10 copolymer, etc. can be illustrated. The packaging film of the present invention has a layered structure of at least 2 types and 3 layers or 3 types and 5 layers by specific coextrusion molding of the above polyolefin resin and aliphatic polyamide resin, for example, [polyolefin resin / aliphatic polyamide resin / polyolefin. Resin] or [polyolefin resin / adhesive layer / aliphatic polyamide resin / adhesive layer / polyolefin resin], preferably the latter multilayer film is molded, and then the film is uniaxially stretched in the take-up direction (longitudinal direction). By doing so, it is molded.

As the coextrusion molding, a T-die molding method or an air-cooling type and water-cooling type inflation molding method is adopted. The unstretched multilayer film obtained by the coextrusion molding is then uniaxially stretched in the film-drawing direction (longitudinal direction) at a stretching ratio of 2 to 5 times, preferably 2.5 to 4 times. This uniaxial stretching imparts rigidity to the film, prevents elongation of the film during tire wrapping, improves workability, and prevents loosening. If the stretching ratio is less than 2 times, the strength of the film is insufficient, and if it is more than 5 times, the stretchability is lowered, and the film may be broken or the film may be unevenly stretched. The stretching treatment is carried out by heating the unstretched film as it is or slitting it into a predetermined width and stretching the film in the take-up direction, that is, the longitudinal direction by changing the peripheral speed of a stretching roll. The preheating temperature in the stretching treatment is usually 4
It is suitable to carry out in the range of 0 ° C. or higher and the melting point of the polyolefin resin −10 ° C. or lower.

The heat setting temperature after stretching is higher than the preheating temperature during stretching, and it is preferable that the temperature is as high as possible in order to prevent wrinkles of the film and improve the transverse strength. The melting point of the polyolefin resin is preferably -10 ° C or lower. The preheating and heat setting temperatures are the melting point of the polyolefin resin −10 ° C.
If higher, the film is melted and attached to the draw roll,
On the other hand, if the preheating temperature is lower than 40 ° C., the aliphatic polyamide resin is not preheated sufficiently, so that it becomes difficult to stretch and the film breaks, which is not desirable.

The thickness of the packaging film of the present invention thus obtained is from 10 to 200 μm, preferably from 20.
The thickness is 100 μm, more preferably 40 to 60 μm, and the thickness of the intermediate layer is 10 to 90% of the total thickness of the film. . The thickness of the film is 20
If it is larger than 0 μm, the cost increases and the workability of winding becomes poor.

If the thickness of the intermediate layer is less than 10% of the total thickness, the original mechanical strength of the polyamide resin cannot be maintained. The thickness of the intermediate layer is preferably 15% or more of the total thickness. On the other hand, when it is more than 90%, the thickness of the polypropylene layer becomes thin, and it becomes difficult to uniformly cover the intermediate layer by coextrusion molding. The thickness of the intermediate layer is preferably 80% or less of the total thickness.

Further, this polyamide layer also serves as a barrier layer for preventing the antioxidant in the tire from penetrating to the outer surface of the wrapped film, and the print applied on the surface of the packaging material can be seen. It never goes away. The thickness of the inner and outer layers is preferably 80% or less of the total thickness. The layer structure of the stretched laminated film of the present invention,
For example, the resin layer may be composed of at least three resin layers of outer layer / intermediate layer / inner layer, but other resin layers may be added to form a structure of four or more layers without departing from the gist of the present invention. Absent. As such a structure of four or more layers, one having an adhesive layer, a reclaimed layer (a layer used as a reclaimed raw material by collecting and crushing burrs and defective products of the packaging film, etc.) between the outer layer and the inner layer Alternatively, a resin layer may be further provided on the outer side of the outer layer or the inner side of the inner layer.

In particular, in the present invention, a three-kind five-layer structure in which an adhesive layer made of a modified polyolefin resin is provided between the outer layer and the intermediate layer and between the inner layer and the intermediate layer is the outer layer and the intermediate layer, and the intermediate layer and the inner layer. The adhesive strength between them is excellent and suitable. Examples of the modified polyolefin resin include polyolefin resins such as polyethylene and polypropylene to which a monomer having a polar group such as unsaturated carboxylic acid such as maleic anhydride or a derivative thereof is added by grafting. As the base resin on which the unsaturated carboxylic acid or the like is grafted, the same type of resin as that used for the inner and outer layers is preferable from the viewpoint of adhesion and the like.

From the viewpoint of the adhesiveness with the polyamide resin of the intermediate layer, the amount of the unsaturated carboxylic acid or the like to be grafted is 0.01 to 0.01 based on the weight of the base resin to be grafted.
A range of 10% by weight is preferred. More preferably 0.01
~ 3% by weight. Such an adhesive layer is preferably provided so as to be in the range of 2 to 20%, preferably 3 to 10%, with respect to the total thickness of the packaging film of the present invention.

As a method of packaging a tire using the packaging film of the present invention, a conventionally known method can be applied. For example, it can be performed by using a tire wrapper device to wind the rubber tire in a gaiter shape and heat-sealing the end portion of the film. Furthermore,
It is also possible to obtain a shrink packaged product by covering the tire with a bag-like packaging material and treating it in a hot air oven at 50 to 200 ° C.

[0022]

EXAMPLES Hereinafter, specific embodiments of the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples as long as the gist thereof is not exceeded. Example 1 The following raw materials were extruded by three extruders using a molding machine equipped with a 450 mm wide three-kind five-layer coextrusion T die to form a three-kind five-layer film.

Resin for intermediate layer Polyamide resin (nylon-6 / 6,6 copolymer, manufactured by Mitsubishi Kasei Co., Ltd., trade name: Novamid 2030, melting point: 1
98 ° C)

Materials for inner and outer layers Polyolefin resin (linear low density polyethylene, manufactured by Mitsubishi Kasei Co., Ltd., trade name: Mitsubishi Polyethylene VF330, melt index: 1.0 g / 10 minutes, density: 0.992 g
/ Cm ³ )

Resin for Adhesive Layer Adhesive polyolefin resin (modified polyethylene, Mitsubishi Kasei Co., Ltd., trade name: Novatec AP228L, melt index: 1.0 g / 10 minutes, density: 0.920 g
/ Cm ³ )

The resins for the inner and outer layers and the intermediate layer are put into an extruder having a diameter of 50 mm, and the adhesive polyolefin resin is put into an extruder having a diameter of 40 mm, and coextruded at a die temperature of 280 ° C. and a chill roll temperature of 25 ° C. Molded at a take-off speed of 5 m / min, three types consisting of outer layer (polyolefin resin) / adhesive layer (adhesive polyolefin) / intermediate layer (polyamide resin) / adhesive layer (adhesive polyolefin resin) / inner layer (polyolefin resin) A 5-layer film was obtained. (Thickness 15
0 μm, layer ratio 3: 1: 5: 1: 3) Then, the film was stretched 3.2 times in the machine direction at a preheating temperature of 60 ° C. by roll stretching, and heat-set at a temperature of 120 ° C. to form a 50 μ thick film. Got Table 1 shows the results of tensile strength (longitudinal direction) and tensile strength (longitudinal direction) at 1% elongation of the obtained film.

The tensile strength was measured according to the JIS Z1702 standard. The tensile modulus is ASTM D-
It was measured according to the standard of 882. The obtained film is 6
A slit of 4 mm width was wrapped around a 185 / 70R14 type rubber tire in a gaiter shape by using a tire wrapper device and packaged. The film was cut and stretched, and packaging was possible without problems.

Example 2 In Example 1, the layer ratio of the multilayer film was 3: 1: 3 :.
It carried out similarly except having set it to 1: 3. The physical property measurement results are shown in Table 1. Further, when a tire was packaged using the obtained film in the same manner as in Example 1, good packaging was possible.

Example 3 The same procedure as in Example 1 was carried out except that the water-cooled inflation molding was used as the raw material molding. The results are shown in Table-1. In addition, the original fabric forming condition is a die diameter of 75 m.
A film having a folding width of 210 mm and a thickness of 150 μm was formed with mφ, a die temperature of 250 ° C., a blow-up ratio of 1.8, and a take-up speed of 17 m / min. Table of physical property measurement results
Shown in 1. Moreover, when the obtained film was slit into a width of 64 mm and the tire was packaged in the same manner as in Example 1, the tire was successfully packaged.

Example 4 Instead of the linear low density polyethylene which is the resin for the inner and outer layers of Example 1, polypropylene (manufactured by Mitsubishi Kasei Co., Ltd., trade name:
Mitsubishi Polypro 6500J, MFR at 230 ℃: 9g /
A laminated film was obtained in the same manner as in Example 1 except that 10 minutes and a density of 0.90 g / cm ³ ) were used. The physical property measurement results are shown in Table 1. Further, when a tire was packaged using the obtained film in the same manner as in Example 1, good packaging was possible.

Comparative Example 1 In Example 1, only linear low-density polyethylene was extruded to obtain a linear low-density polyethylene monolayer film. When a tire was packaged using the obtained film in the same manner as in Example 1, the film was stretched to cause a neck-in phenomenon, and the film width was narrowed, so that the film could not be wound successfully. The physical property measurement results are shown in Table 1.

Comparative Example 2 The die slit was adjusted, and the draw ratio was set to 1.5 and 50 μm.
A multilayer film was obtained in the same manner as in Example 1 except that the above film was obtained. When a tire was packaged using the obtained film in the same manner as in Example 1, the tire was stretched as in Comparative Example 1 and a defect occurred. The physical property measurement results are shown in Table 1.

Comparative Example 3 In Example 1, molding was carried out at a draw ratio of 6 times, but it broke and could not be molded.

[0034]

[Table 1]

[0035]

EFFECTS OF THE INVENTION The packaging film of the present invention has high strength and excellent rigidity, and therefore is difficult to stretch and has excellent workability for winding.
In addition, the barrier property of the polyamide layer prevents discoloration of the film. Further, since it is possible to provide a burr collecting layer between the layers, it is possible to obtain a cost-effective one as compared with the conventional tire wrapping film.

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Claims (1)

[Claims] 1. A film- or sheet-shaped packaging material used for packaging a tire, comprising a laminated film or sheet in which a polyolefin-based resin layer is disposed on both sides of an intermediate layer made of an aliphatic polyamide resin. A tire packaging material, which is obtained by stretching 5 times.