JP2003286353A - Machine-wound stretch film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a thin, strong machine-wound stretch film which is excellent in stretch property, high in tensile strength at break, and excellent in adhesion and a property to retain tightness after winding. <P>SOLUTION: The machine-wound stretch film comprises a polyethylene resin composition which gives 5-30 wt.% of an elution fraction at ≤50°C (T50) determined by the temperature rising elution fractionation (TREF) and 5-20 wt.% of an elution fraction at ≤90°C (T90). There is also provided a multilayer machine-wound stretch film at least one layer of which is the above machine- wound stretch film and the whole thickness of which is 13-20 μm. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a mechanically wound stretch film. More specifically, the present invention relates to a thin and durable machine-wound stretch film that has excellent stretchability, high tensile strength at break, and excellent adhesiveness and tightening retention after winding.

[0002]

2. Description of the Related Art Stretch films are generally used in a wide range as a packaging film, and the contents can be protected and accumulated by wrapping products etc. with stretch films, and as a result, It is useful for sales promotion of products and the like. As the stretch film, for example, household wrap film, shrink film for food packaging, stretch film for integrated packaging,
Pallet stretch film and grass stretch film are known.

Stretch films are required to have a certain level of elongation, tensile breaking strength and adhesive strength, and in recent years, it has been desired to reduce dust due to the global environment. Is required to be thin.

[0004] In general, a method of packaging a stretch film by stretching a stretch film by hand to wrap a product etc. (referred to as "hand winding") and a method of stretching a stretch film by a machine There is a method of packaging (called “mechanical winding”). However, in the case of mechanical winding, the stretching ratio is as high as 200% or more and the wrapping speed is faster than the hand winding having a stretching ratio of 100 to 200%. It was easy. Under such circumstances, the mechanically wound stretch film has been required to have improved stretchability, tensile breaking strength, adhesiveness after winding and tightening / holding property, and thinning.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thin and durable mechanically wound stretch film which is excellent in stretchability, has a high tensile breaking strength, and has excellent adhesiveness and tightening retention after being wound. To do.

[0006]

The inventors of the present invention have made earnest studies in view of the above situation, and as a result, temperature rise elution fractionation (TRE
F) the amount of eluted components below 50 ° C (T5
0) is within a certain range, and the amount of elution component (T
The inventors have found that a mechanically wound stretch film made of a polyethylene resin composition having 90) within a certain range can solve the above problems, and completed the present invention.

That is, according to the present invention, the amount of elution component (T50) at 50 ° C. or lower determined by temperature rising elution fractionation (TREF) is 5 to 30% by weight, and the amount of elution component at 90 ° C. or higher (T90) is 5%. The present invention relates to a mechanically wound stretch film made of a polyethylene resin composition of 20% by weight. Hereinafter, the present invention will be described in detail.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the mechanically wound stretch film of the present invention, temperature rising elution fractionation (Temperature Risin
g Elution Fractionation, hereinafter referred to as "TREF". The amount of elution component at 50 ° C. or lower (hereinafter referred to as “T50”) determined by the above) is 5 to 30% by weight, preferably 5 to 25% by weight, and more preferably 5 to 15% by weight. . When T50 exceeds 30% by weight, the film may be soft and the elongation tends to decrease. When T50 is less than 5% by weight, the breaking strength may be low and the film may easily extend and easily break. The amount of components eluted at 90 ° C or higher (hereinafter referred to as "T90") is 5 to 20% by weight, and more preferably 5 to 18% by weight. T9
When 0 exceeds 20%, prestretch (about 2.5
Non-uniform elongation may occur during double-stretching), or the film may be easily broken when it is wound on a high-speed machine and the strength may be insufficient. If it is less than 5% by weight, the breaking strength is low and the film is easily broken. It is easy to do.

The component amount of T50 and T90 is at least 2
It can be adjusted by blending a specific ethylene / α-olefin copolymer (A) component. Also,
By blending the ethylene / α-olefin copolymer (A) component and the high-density polyethylene (B) component, T
Adjustment of 90 is possible.

The polyethylene resin composition used in the mechanically wound stretch film of the present invention comprises at least two ethylene / α-olefin copolymers (which satisfy the following requirements (A-1) to (A-3) ( A polyethylene resin composition containing the component (A), or the following requirements (A-
1) to (A-3), the ethylene / α-olefin copolymer (A) component 99 to 80% by weight, and the following requirements (B)
-1) and 1 to 20% by weight of a high-density polyethylene (B) component satisfying (B-2) are polyethylene resin compositions. Requirement (A-1) It consists of ethylene and an α-olefin having 6 to 12 carbon atoms. Requirement (A-2) melt flow rate (MFR) is 0.1
It is -10g / 10min. The requirement (A-3) density is 870 to 940 kg / m ³ . Requirement (B-1) melt flow rate (MFR) is 0.1
It is -10g / 10min. The requirement (B-2) density exceeds 940 kg / m ³ .

For the mechanically wound stretch film of the present invention
The MFR of the polyethylene resin composition used is 0.5
~ 3g / 10min, density 900 ~ 920kg
/ M ³Is. MFR of polyethylene resin composition
If it is less than 0.5 g / 10 min, the workability may be poor.
Yes, high speed stretch when exceeding 3g / 10min
The film may break during packaging. Density is 900
kg / m³If it is less than the range, it is easy to stretch and the tightening force is not
920kg / m³If it exceeds, adhesive strength
May be lowered and may be easily peeled off.

Examples of the α-olefin having 3 to 12 carbon atoms used in the ethylene / α-olefin copolymer (A) component used in the present invention include propylene, butene-1, pentene-1, and hexene-1. , Heptene-1, octene-1, nonene-1, decene-1, dodecene-1,
4-methyl-pentene-1,4-methyl-hexene-
1, vinylcyclohexane, vinylcyclohexene, styrene, norbornene, butadiene, isoprene and the like.

Ethylene / α-olefin copolymer (A)
As the component, for example, ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene-hexene-1 copolymer, ethylene-octene-1 copolymer, ethylene-4methylpentene-1 copolymer, etc. Is mentioned.
Preferred are ethylene-hexene-1 copolymer, ethylene-octene-1 copolymer and ethylene-4methylpentene-1 copolymer.

Ethylene / α-olefin copolymer (A)
As the melt flow rate (MFR) of the component, from the viewpoint of extrusion load and film strength in film forming,
It is usually 0.1 to 10 g / 10 min, preferably 0.3 to 4 g / 10 min, more preferably 0.1.
It is 4 to 4 g / 10 min.

Ethylene / α-olefin copolymer (A)
The density of the component is usually 880 to 930 kg / m ³ , and preferably 880, from the viewpoint of transparency and impact strength.
˜925 kg / m ³ .

Ethylene / α-olefin copolymer (A)
Examples of the method for producing the component include a production method by a known polymerization method using a known catalyst. Known catalysts include
For example, Ziegler-Natta catalysts, metallocene catalysts, and the like, and known polymerization methods include, for example, a solution polymerization method, a slurry polymerization method, a high-pressure ionic polymerization method, a gas phase polymerization method, and the like, and preferably a solution. Polymerization method, high-pressure ionic polymerization method, and gas phase polymerization method.

Ethylene / α-olefin copolymer (A)
Examples of the metallocene catalyst used for producing the components include a catalyst composed of a metallocene compound and an organoaluminum compound and / or an ionic compound.

The metallocene compound is a transition metal compound having a group having a cyclopentadiene skeleton, and is usually represented by the general formula ML _a X _na (where M is a group 4 or lanthanide series of the periodic table of elements). L is a group having a cyclopentadiene skeleton or a group containing a hetero atom, and at least one is a group having a cyclopentadiene skeleton. X is a halogen atom, hydrogen or a hydrocarbon group having 1 to 20 carbon atoms, n is the valence of the transition metal atom, and a is an integer satisfying 0 <a ≦ n. Examples thereof include compounds, which may be used alone or in combination of two or more kinds.

Examples of the organoaluminum compound include alkylaluminum compounds and alumoxane compounds, and examples of the ionic compound include trityl borate and anilinium borate.

The metallocene compound and the organoaluminum compound and / or the ionic compound are Si
It may be used in combination with a particulate carrier including an inorganic carrier such as O ₂ or Al ₂ O ₃ or an organic polymer carrier such as an olefin polymer such as ethylene or styrene.

The melt flow rate (MFR) of the high-density polyethylene (B) component used in the present invention is compatible with the ethylene / α-olefin copolymer (A) component and prevents generation of spots such as fish eyes. From the viewpoint of adhesiveness and tensile strength at break, it is 0.1 to 10 g / min, preferably 0.3 to 2 g / min.

The density of the high density polyethylene (B) component is
From the viewpoint of imparting elongation for high-speed mechanical winding, it is usually 940.
It is at least kg / m ³ .

As a method for producing the high-density polyethylene (B) component, a known catalyst is used and ethylene and a carbon number of 3 to 3 are used.
A method for producing the α-olefin of 12 by a known polymerization method can be mentioned. Known catalysts include, for example, the Ziegler-Natta catalyst system, and known polymerization methods include, for example, gas phase in the presence or absence of a solvent.
A solid phase polymerization method, a liquid phase-solid phase polymerization method, a homogeneous liquid phase polymerization method and the like can be mentioned. The polymerization temperature is usually 30 to 300 ° C., and the polymerization pressure is usually atmospheric pressure to 3000 kg / c.
m ² . Commercially available high density polyethylene can be used.

Examples of the method for producing the polyethylene resin composition used in the present invention include known dry blending methods and melt blending methods. Various blenders such as a Henschel mixer and a tumbler mixer are used in the dry blend, and various mixers such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, and a heat roll are used in the melt blend.

If necessary, other resins and additives may be added to the polyethylene resin composition used in the present invention. These other resins and additives may be used alone or in combination of at least two kinds.

As additives, stabilizers (antioxidants),
Lubricant, antistatic agent, processability improving agent, anti-blocking agent,
Examples include pigments and the like. Examples of the stabilizer include 2,6
-Di-t-butyl-p-cresol (BHT), tetrakis [methylene-3- (3,5-di-t-butyl-4-)
Hydroxyphenyl) propionate] methane (Ciba
Specialty Chemicals, trade name: IRGANOX
1010), n-octadecyl-3- (4'-hydroxy-3,5'-di-t-butylphenyl) propionate (Ciba Specialty Chemicals, trade name: IR
GANOX 1076) and other phenolic stabilizers, bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite, tris (2,4-di-t).
Examples thereof include phosphite-based stabilizers represented by -butylphenyl) phosphite and the like, and bifunctional stabilizers having the performance of both (Sumitomo Chemical Co., Ltd., trade name: Sumilizer GP).

Examples of the lubricant include higher fatty acid amides and higher fatty acid esters, and examples of the antistatic agent include glycerin esters and sorbitan acid esters of fatty acids having 8 to 22 carbon atoms and 8 to 8 carbon atoms. Examples thereof include alkyldialkanolamides of 22 fatty acids, polyethylene glycol esters, and the like. Examples of the processability improver include fatty acid metal salts such as calcium stearate. If the tackiness is insufficient, a tackifier such as polybutene may be added if necessary.

Other resins and additives to be added according to the above need may be melt-kneaded in advance,
They may be dry blended individually or may be dry blended in one or more masterbatches.

The mechanically wound stretch film of the present invention comprises:
It can be used as at least one layer of a single-layer machine-wound stretch film or a multi-layer machine-wound stretch film. Examples of the method for producing the single-layer machine-wound stretch film or the multi-layer machine-wound stretch film include known film production methods, and examples include a method using an inflation film production apparatus, a T die cast film production apparatus, and the like.

Examples of the multilayer film having at least one layer of the mechanically wound stretch film of the present invention include a multilayer film having a non-adhesive layer such as LDPE on one surface.

The mechanically wound stretch film of the present invention has a thickness of 13 to 20 μm. The thickness of a known mechanically wound film is usually about 30 μm.

The single-layer or multi-layer mechanically wound stretch film of the present invention exhibits self-adhesiveness even when stretched by 200% or more and has sufficient adhesive force. The single-layer or multi-layer mechanically wound stretch film of the present invention can be firmly held in the package without loosening due to aging.

The method for producing the mechanically wound stretch film of the present invention preferably includes a single layer or multi-layer film processing method such as a T-die processing method and an inflation film processing method. The processing resin temperature in the T-die processing method is usually 230 ° C to 300 ° C, and the chill roll temperature is usually 20 ° C to 50 ° C.

When an adhesive such as polybutene is added to the mechanically wound stretch film of the present invention, the addition method may be a method of using a raw material obtained by compounding polybutene in advance with a Banbury kneader, a method of injecting it into an extruder or the like. Can be mentioned. Polybutene concentration is 0.5 to 20
In the case of three layers, it may be added to all layers, both outer layers, or the intermediate layer, or only one side. As the polybutene, commercially available products such as HV35 manufactured by Nippon Petrochemical Co., Ltd. and Polybutene 100H manufactured by Idemitsu Petrochemical Co., Ltd. may be used.

[0035]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. The ethylene / α-olefin copolymer, the high-density polyethylene and the obtained mechanically wound stretch film used in Examples and Comparative Examples were evaluated according to the following methods.

(1) TREF T50 and T90 (unit:% by weight) TREF (Temperature Rising Elution Fractionat)
ion (temperature rising elution fractionation) was measured using a multi-functional LC manufactured by Tosoh Corporation. The ethylene-α-olefin copolymer used in the present invention was dissolved in ortho-dichlorobenzene heated to 145 ° C. (concentration 0.2 g / 20 ml), and 6 ml was injected into a column filled with sea sand in the oven, Lower the temperature to 125 ° C at a rate of 40 ° C / 60 minutes and
The temperature was slowly lowered from 14 ° C to -15 ° C over 14 hours. Subsequently, while increasing the temperature at a rate of 10 ° C./60 minutes, the relative concentration of the copolymer eluted during that period was connected to the column F.
It was measured by T-IR. The data acquisition points were measured at 10 points between 10 ° C. The final temperature was raised to 125 ° C. while determining the relative concentration of the eluted copolymer at each measurement temperature. Calculate the elution temperature and relative concentration every 1 ° C
The amount of elution component below T (T50) and the amount of elution component above 90 ° C (T90) were calculated. Figure 1 TREF
The amount of elution component at 50 ° C. or lower in the curve was determined as T50, and the amount of elution component at 90 ° C. or higher was determined as T90. In the case of a composition comprising an ethylene / α-olefin copolymer (A) component and a high-density polyethylene (B) component, individual T50
And the total value calculated from the product of T90 and each ratio was represented as T50 and T90 of the composition. T of Comparative Example 4
50 and T90 showed the value which consists of the resin ratio of 2 layers (A3) and 3 layers (A2).

(2) Density (unit: kg / m ³ ) The density was measured according to the method specified in JIS K6760-1981.

(3) Melt flow rate (MFR, unit: g / 10 min) The melt flow rate was measured according to the method defined in JIS K6760-181. The load is 2.16 kg and the temperature is 190 ° C.
Then, it was measured.

(4) Actual Package Stretch Wrapping Property A practical test was carried out using a machine-wound pallet stretch wrapping machine manufactured by Lantech (Model T-WRAPER). A stretch film with a paper tube winding width of 500 mm is attached, a pallet is placed on the turntable, and one side made of veneer plywood placed on it is 1100 mm in height and 1200 mm in height.
The film was wrapped around a rectangular parallelepiped, and the presence or absence of film breakage and the tightening condition were evaluated. When the scale (stretch power) of the winding speed is increased, the stretching ratio is increased, and the film is thinly stretched and easily broken. The evaluation criteria are as follows. The rupture state at the time of winding, the adhesive force at the time of completion of winding and the machine-rolled state were left for 2 weeks, and the tightening retention force (slack condition) of the film was evaluated. The holding power was measured with the one with a higher winding scale. The scale must be 9 or more so that the film can be wound without breakage, and the adhesive strength must be such that after winding, the film is cut and lightly pressed by hand so that the film does not peel off.

Scale, stretch ratio and speed ratio of a Lantech mechanical roll pallet stretch wrapping machine Note 1) Indicates the speed ratio of pallet stretch to pre-stretch. Note 2) Indicates the maximum film winding speed of the pallet (result by calculation).

Evaluation Criteria Existence of breakage: ○ No breakage, × Breakage Adhesion after winding: ○ Adhesiveness, × No adhesion Tightening force retention: ○ No slackness, good retention, × Slackness

Ethylene used in Examples and Comparative Examples
Table 1 shows the physical properties of the α-olefin copolymer (A) component and the high-density polyethylene (B) component.

Examples 1 to 3 and Comparative Examples 1 to 7 Table 1 (Examples 1 to 7) and Table 2 show the components (A) and (B).
Pellets having the compositions shown in (Comparative Examples 1 to 4) were mixed with a tumble mixer. Die width 30 for 3 65mmφ extruders
Using a processing machine equipped with an air knife on a T-die of three kinds of three layers of 00 mm and a lip of 1.2 mm, a processing temperature of 28
0 ° C, chill roll temperature 25 ° C, thickness ratio 1 layer / 2 layers /
3 layers = 1/5/4 thickness 20 μm (take-off speed 80 m / m
in), a film having a thickness of 15 μm (take-off speed of 85 m / min) was processed. The physical properties of the obtained film are shown in Table 1. In addition, T50 and T90 are shown by values consisting of two-layer and three-layer resin compositions.

[0044]

[Table 1] A1: Japan Evolution Co., Ltd., Sumitomo Chemical Co., Ltd. sales,
Sumikansen E FV401 A2: Made by Japan Evolution Co., Ltd., Sumitomo Chemical Co., Ltd. sales,
Sumikansen E FV402 A3: Made by Japan Evolution Co., Ltd., Sumitomo Chemical Co., Ltd. sales,
Sumikansen E FV403 A4: Made by Japan Evolution Co., Ltd., Sumitomo Chemical Co., Ltd. sales,
Sumikansen E FV404 A5: Nippon Evolution Co., Ltd., Sumitomo Chemical Co., Ltd. sales,
Sumikansen E FV203 A6: manufactured by Nippon Evolution Co., Ltd., sold by Sumitomo Chemical Co., Ltd.
Sumikansen E FV205 A7: Made by Japan Evolution Co., Ltd., Sumitomo Chemical Co., Ltd. sales,
Sumikansen E FV103 A8: Sumitomo Chemical Co., Ltd., Excellen FX CX3005 A9: Sumitomo Chemical Co., Ltd., Excellen FX CX4002 B1: Nippon Polyolefin, high-density polyethylene S3
60 C1: Sumitomo Chemical Co., Ltd., Sumikasen CY443-3N10 A1 to A9: Ethylene / hexene-1 copolymer

[0045]

[Table 2] Presence or absence of breakage: ○ No breakage, × Breakage Adhesion after winding: ○ Adhesiveness, × No adhesion Tightening force retention: ○ Good retention without slack, × Slackness

[0046]

[Table 3] Presence or absence of breakage: ○ No breakage, × Breakage Adhesion after winding: ○ Adhesiveness, × No adhesion Tightening force retention: ○ Good retention without slack, × Slackness

Examples 1 to 7 satisfying the requirements of the present invention are
It can be seen that it is thin and strong, with excellent stretchability, tensile strength at break, adhesiveness, and holding strength. On the other hand, Comparative Examples 1 and 2 which do not satisfy the requirement of T90, T
Comparative Example 3 which does not satisfy the requirement of 50 and the requirement of T90,
Further, in Comparative Example 4 which does not satisfy the requirement of T50, the film breaks during mechanical winding stretch packaging.

[0048]

As described above in detail, according to the present invention, a thin and durable mechanically wound stretch film excellent in stretchability, strong in tensile rupture strength, and excellent in tackiness and tightening retention after winding. Obtainable.

[Brief description of drawings]

Figure 1: TREF curve

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Satoru Koyama             Sumitomo Chemical Co., Ltd. 1-5 Anezaki Kaigan, Ichihara City, Chiba Prefecture             Business (72) Inventor Yasushi Okamoto             3 Sakae-cho, Sano-shi, Tochigi 3 Itochu Sump             Within Russ Co., Ltd. (72) Inventor Takashi Matsumoto             3 Sakae-cho, Sano-shi, Tochigi 3 Itochu Sump             Within Russ Co., Ltd. (72) Inventor Kazuhisa Takeuchi             3 Sakae-cho, Sano-shi, Tochigi 3 Itochu Sump             Within Russ Co., Ltd. F term (reference) 3E086 AB01 AD17 BA04 BA15 BB66                       BB85                 4F071 AA14X AA15X AA82 AA88                       AF05Y AH04 BA01 BB06                       BB09 BC01                 4F100 AK04A AK04B AK05A AK05B                       AK62A AK62B AL05A AL05B                       BA02 GB15 JA03 JA06A                       JA06B JA13A JA13B JB20A                       JB20B JK03                 4J002 BB05W BB05X

Claims (5)

[Claims] 1. The amount of elution component (T50) at 50 ° C. or lower determined by temperature rising elution fractionation (TREF) is 5 to 30.
% By weight, and the amount of eluted components (T90) at 90 ° C. or higher is 5
A mechanically wound stretch film comprising a polyethylene resin composition in an amount of 20 wt%. 2. A polyethylene resin composition containing at least two ethylene / α-olefin copolymer (A) components satisfying the following requirements (A-1) to (A-3):
The melt flow rate (MFR) of the resin composition is 0.5
~ 3g / 10min, density 900 ~ 920kg /
The machine-wound stretch film according to claim 1, wherein the stretch film is m ³ . Requirement (A-1) It consists of ethylene and an α-olefin having 6 to 12 carbon atoms. Requirement (A-2) melt flow rate (MFR) is 0.1
It is -10g / 10min. The requirement (A-3) density is 870 to 940 kg / m ³ . 3. A polyethylene resin composition comprising 99-80% by weight of an ethylene / α-olefin copolymer (A) component satisfying the following requirements (A-1) to (A-3) and the following requirements (A): B-1) and 1 to 20% by weight of the high-density polyethylene (B) component satisfying (B-2), and the melt flow rate (MFR) of the resin composition is 0.5 to 3 g /
The mechanically-stretched film according to claim 1, wherein the stretched film is 10 minutes and has a density of 900 to 920 kg / m ³ . Requirement (A-1) It consists of ethylene and an α-olefin having 6 to 12 carbon atoms. Requirement (A-2) melt flow rate (MFR) is 0.1
It is -10g / 10min. The requirement (A-3) density is 870 to 940 kg / m ³ . Requirement (B-1) melt flow rate (MFR) is 0.1
It is -10g / 10min. The requirement (B-2) density exceeds 940 kg / m ³ . 4. An ethylene / α-olefin copolymer (A)
Ethylene / α whose component was produced using a metallocene catalyst
-Olefin copolymer, characterized in that
Machine-wound stretch film as described. 5. A multi-layer film, wherein at least one layer is the machine-wound stretch film according to claims 1-3.
A multilayer machine-wound stretch film, wherein the total thickness of the multilayer film is 13 to 20 μm.