JPH09278974A - Thermally shrinkable cyclic olefin-based polymer tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject tube derived from a specific olefin-based resin composition, excellent in firmness, shrink finish and inexpensiveness, and useful for e.g. covering the cathode cases of lithium ion secondary batteries. SOLUTION: This tube is made of a composition 55-90 deg.C in the main glass transition temperature comprising (A) a cyclic olefin-based polymer consisting of (A1 ) a cyclic olefin-based random copolymer composed of ethylene component and a cyclic olefin component (Z) of the formula (R1 to R12 are each H or a hydrocarbon group; (n) is >=0), (A2 ) a cyclic polymer composed of at least one kind of the component Z or a hydrogenated product thereof, or blend of the components A1 and A2 and (B) an olefin-based resin other than the component A >=5×10<9> dyne/cm<2> in the storage modulus determined at a frequency of 10Hz and 30 deg.C in the weight ratio A/B of (60-50) to (40-50).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-shrinkable cyclic olefin polymer tube which is preferably used for coating batteries and has excellent shrink finish and good coating processability.

[0002]

2. Description of the Related Art As a heat-shrinkable tube for coating a zinc can of a dry cell, a cap seal or a shrink coating of various articles, a tube made of polyvinyl chloride (PVC) is widely used. Although PVC tubes have excellent practical characteristics and cost efficiency, in recent years materials other than PVC have been demanded because they generate toxic gas containing chlorine when incinerated after disposal.

As one of the candidates for the raw material, there is a cyclic olefin polymer comprising an ethylene component and a cyclic olefin component. Unlike other polyethylene-based polymers, this polymer can be imparted with substantial heat shrinkability by stretching without being subjected to crosslinking treatment or the like. However, a heat-shrinkable tube containing only a cyclic olefin polymer lacks flexibility and is not practical. Therefore, it has been proposed to add appropriate flexibility to the cyclic olefin polymer by adding another polyolefin resin.

However, in the conventional technique, the amount of the other olefin resin to be added to the cyclic olefin polymer in order to maintain the elasticity of the tube itself is limited, so that it is not practical in terms of cost. There has been a problem that if the amount of other olefin resin is increased, sufficient heat shrinkability, particularly low temperature heat shrinkability practically preferable, cannot be obtained.

[0005]

Means for Solving the Problems As a result of extensive studies to solve the above problems, the present invention is excellent in waist strength and low temperature heat shrinkability required as a heat shrinkable tube, and is cost effective. A heat-shrinkable tube which is also advantageous is obtained.

That is, the gist of the present invention is as follows (A),
A composition containing the component (B), having a mixing weight ratio of the component (A) and the component (B) of A / B = 60 to 50/40 to 50, and having a main glass transition temperature in the range of 55 to 90 ° C. It is a heat-shrinkable cyclic olefin-based polymer tube.

Component (A): Cyclic olefin polymer consisting of the following (A ₁ ), (A ₂ ) or (A ₃ ) (A ₁ ): Ethylene component and cyclic olefin represented by the following general formula (1) Cyclic olefin-based random copolymer (A ₂ ) composed of a component and a ring-opening polymer or a hydride thereof (A ₃ ) composed of one or more olefin components selected from the cyclic olefins represented by the following general formula (1). ): A mixture of (A ₁ ) and (A ₂ ) (B) An olefin resin other than the component (A) having a storage elastic modulus of 5 × 10 ⁹ dyn / cm ² or more measured at a frequency of 10 Hz and a temperature of 30 ° C.

Embedded image Further, the present invention provides a heat-shrinkable cyclic olefin polymer tube composed of a composition containing a low molecular weight compound as the component (C) in the above composition.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. The component (A) in the material that is the main component of the heat-shrinkable tube of the present invention is a cyclic olefin polymer comprising the above-mentioned (A ₁ ), (A ₂ ) or (A ₃ ). As (A ₁ ), a cyclic olefin represented by the above general formula (1) is added in an amount of 20 to 50.
An amorphous copolymer with ethylene, which is contained in about mol%, can be exemplified, and it may be one containing α-olefin other than ethylene, or one containing butadiene, isoprene or the like as the third component. Some have various glass transition temperatures depending on the content of cyclic olefin, and are commercially known as Apel (Mitsui Petrochemical Industry Co., Ltd.).

An example of the cyclic olefin represented by the general formula (1) is bicyclohept-2- of the following formula (2).
En (2-norbornene) and its derivatives such as norbornene, 6-methylnorbornene, 6-ethylnorbornene, 6-n-butylnorbornene, 5-propylnorbornene, 1-methylnorbornene, 7-methylnorbornene, 5,6-dimethyl. Norbornene, 5-phenylnorbornene, 5-benzylnorbornene and the like can be mentioned.

Examples of tetracyclo-3-dodecene represented by the following formula (3) and derivatives thereof include 8-methyltetracyclo-3-dodecene and 8-ethyltetracyclo-
3-dodecene, 8-hexyltetracyclo-3-dodecene, 2,10-dimethyltetracyclo-3-dodecene,
Examples thereof include 5,10-dimethyltetracyclo-3-dodecene.

[0011]

Embedded image

Embedded image

(A ₂ ) is a ring-opening polymer of cyclic olefin represented by the general formula (1) or a hydride thereof,
Generally, it is an amorphous polymer having a high glass transition temperature, and is known under the names such as Zeonex (Nippon Zeon) and Arton (Nippon Synthetic Rubber).

However, the heat-shrinkable tube containing only the component (A) lacks flexibility and is not practical in terms of cost.
Therefore, in the cyclic olefin polymer of the component (A),
It is known that other olefin resin is mixed as the component (B) to impart appropriate flexibility, but it is desirable to increase the amount of the other olefin resin in terms of cost, while the amount is preferable. However, there is a problem in that the elasticity of the tube decreases and the suitability for an automatic coating / packaging machine deteriorates, and the low temperature heat shrinkability of the stretch tube cannot be obtained.

On the other hand, in the present invention, other olefin resin to be mixed is selected, and preferably (C) described later is used.
By using the components together, a large amount of other olefin resin can be mixed.

In the present invention, the other olefin resin added is a frequency of 10H by dynamic viscoelasticity measurement.
z, storage elastic modulus E ′ measured at a temperature of 30 ° C. is 5 × 10 ⁹
Select a resin with a dyn / cm ² or higher. Storage elastic modulus E '
If the amount of the resin is less than 5 × 10 ⁹ dyn / cm ² , mixing with a large amount unfavorably reduces the stiffness of the tube.

The other olefin resin used may be a blend of a single type or several types, and in the case of a blend, the blended product may satisfy the above-mentioned characteristics as a whole.
As a specific resin, a polymer mainly composed of ethylene is preferable in consideration of compatibility with the component (A), and high density polyethylene, medium density polyethylene, or low density polyethylene or propylene-ethylene elastomer is preferable. And a mixed resin thereof. Normal low-density polyethylene and EVA (ethylene-vinyl acetate copolymer)
It is difficult to meet the above characteristics by themselves.

A cyclic olefin polymer as component (A),
The mixing weight ratio of the component (B) with other olefin resin is A
The range of / B = 60 to 50/40 to 50 is suitable.
If the content of the component (B) is less than 40% by weight based on the total weight of the component (A + B), it is not practical in terms of cost, and the temperature-shrinkage curve of the resulting heat-shrinkable tube tends to rise rapidly.
Generally, when the rise of the temperature-shrinkage curve becomes steep,
It is known that as a result of the shrinkage rate fluctuating sensitively with temperature, the appropriate condition region of the shrink coating becomes narrow, which makes it difficult to use as a heat shrinkable tube. On the other hand, when it exceeds 50% by weight, low-temperature heat shrinkability cannot be obtained, and the heat shrinkable tube lacks practicality.

In the present invention, it is important to adjust the main glass transition temperature of the composition (hereinafter, the glass transition temperature may be abbreviated as "Tg") to be in the range of 55 to 90 ° C. is there. When the Tg of the composition is lower than 55 ° C., the natural shrinkage of the obtained heat-shrinkable tube (a temperature slightly higher than room temperature, for example, the tube shrinks in the summer) becomes very large, and the tube lacks dimensional stability. It is not practically preferable. On the other hand, if the temperature exceeds 90 ° C., low temperature stretching becomes difficult, and as a result, low temperature heat shrinkability cannot be obtained, which is not preferable.

In order to adjust the Tg of the composition in the range of 55 to 90 ° C., one method is to select a component (A) having a relatively low glass transition temperature (for example, 95 ° C. or less). is there. Further, as the component (A), one having a high Tg is used, and when the Tg cannot be adjusted within the above range only with the components (A) and (B), the component (C) described later may be used together. It is to be noted that the composition having only the components (A) and (B) and having a glass transition temperature in the range of 55 to 90 ° C. is added with the component (C) to enhance the heat shrinkability, particularly the low temperature heat shrinkability. Therefore, the addition of the component (C) is effective also in this case. Here, the low molecular weight compound of component (C) is
When it is mixed with the components (A) and (B), it has such a compatibility that it does not seem to separate when it is mixed, preferably a transparent or translucent appearance, and the elastic modulus of the composition in the stretching temperature range decreases. This is an organic low molecular weight compound which has the effect of enabling low temperature stretching to enhance the heat shrinkability, and moreover to moderate the rise of the temperature-shrinkage curve to broaden the range of appropriate conditions for shrink coating.

That is, the storage elastic modulus E'is 5 × 10 ⁹ d
When a large amount of olefin resin of yn / cm ² or more is mixed, the stretching stress at the time of stretching the tube becomes high, so that the low temperature stretching becomes difficult and, as a result, the low temperature shrinkability tends to decrease. It is effective to add a low molecular weight compound as the component (C).

The low molecular weight compound is generally known as a plasticizer for polyvinyl chloride resins, for example, phthalic acid alkyl esters such as dibutyl phthalate, di-2-ethylhexyl phthalate and diisononyl phthalate; di-2-ethylhexyl. Examples thereof include adipic acid alkyl esters such as adipate and diisononyl adipate; azelaic acid alkyl esters such as di-2-ethylhexyl azelate; epoxidized vegetable oils such as epoxidized soybean oil.

Further, rosin, modified rosin, polymerized rosin,
Rosin-based resin such as rosin glycerin ester; polyterpene-based resin such as α-pinene polymer, β-pinene polymer, dipentene polymer, terpene-phenol copolymer; C
₅ series petroleum resin, dicyclopentadiene series petroleum resin, C ₈
Petroleum resins such as .about.C ₁₀ tar-based petroleum resins; their partial hydrides or complete hydrides can also be preferably used.

Further, liquid polybutene, liquid polybutadiene, liquid polyisoprene, liquid polyisobutylene, liquid butyl rubber and the like can be preferably used. Here, the low molecular weight means a compound having a molecular weight of approximately 10,000 or less, usually 5,000 or less.

When the low molecular weight compound is added, the addition amount thereof is preferably in the range of 1 to 25% by weight with respect to 100% by weight of (A + B), and more preferably 5 to 20% by weight.
Range. Generally, if it is less than 1% by weight, the effect of improving the low temperature stretchability at the time of stretching the tube is not obtained, and if it exceeds 25% by weight, the glass transition temperature of the plasticized mixture becomes close to room temperature, and the natural shrinkage of the tube is suppressed. It becomes very large and the tube lacks in dimensional stability, and the tube inferior in mechanical strength is not preferable. However, the addition amount of the above-mentioned low molecular weight compound depends on the composition of the mixture and the glass transition temperature, and therefore is appropriately determined within the above range in consideration of the quality of the tube.
The glass transition temperatures of the compositions (B) and (C) are 55 to 90.
It is important to adjust the temperature within the range of ° C. The component (C) may be added alone or as a mixture of two or more.

From the above points, the low molecular weight compounds exemplified above are particularly preferably those having a glass transition temperature of 50 to 100.
Those having a glass transition temperature of 50.
Examples include rosin-based resins, polyterpene-based resins, petroleum resins and hydrogenated products thereof at -100 ° C. Such a low molecular weight compound is a solid at room temperature, does not significantly lower the stiffness of the tube, and has a stretching temperature range (a guideline is 100%).
(° C.) has the advantage of softening and not hindering stretching.

In the tube of the present invention, for the purpose of improving and adjusting the molding processability and the physical properties of the tube, other polymer materials or antioxidants are added within the range that does not impair the effects of the present invention.
It is also possible to add additives / modifiers such as lubricants, inorganic fillers, ultraviolet absorbers, and light stabilizers.

The tube of the present invention can be widely used for shrink coating of various articles, shrink binding, etc., but in order to easily coat the object to be coated, the coefficient of dynamic friction of the inner surface of the tube is 0.4 or less. It is particularly preferable that it is 0.3 or less. When the coefficient of dynamic friction of the inner surface of the tube is larger than 0.4, it may be difficult to coat. As a method of setting the dynamic friction coefficient to 0.4 or less, it is preferable to add a lubricant together with the selection of the low molecular weight compound. Organic lubricants include hydrocarbons such as paraffin, microwax, and low molecular weight polyethylene; fatty acids such as higher fatty acids and oxyfatty acids; fatty acid amides such as monofatty acid amides and alkylenebisfatty acid amides; fatty acid lower alcohol esters. Examples thereof include ester type such as fatty acid polyhydric alcohol ester; alcohol type such as fatty acid alcohol, polyhydric alcohol, polyglycol and polyglycerol; metal soap type.

Further, an inorganic lubricant which is an inert fine particle such as kaolin, clay, calcium carbonate, silicon oxide, calcium terephthalate, aluminum oxide, titanium oxide, calcium phosphate, lithium fluoride may be contained. The amount of addition is appropriately determined according to the degree of decrease in the dynamic friction coefficient.

The composition comprising the components described above can be mixed by a usual kneader, but it is preferable to use an extruder, particularly a twin-screw extruder, from the viewpoint of easy operation. Alternatively, it may be dry-blended and directly extruded.

The mixed composition is extruded into a tube by an extruder with an annular die. The unstretched tube is tubularly stretched in the length direction and the radial direction. The stretching ratio in that case is determined by the target heat shrinkage ratio, but is generally 1 to 1.7 times, preferably 1 to 1.7 times in the length direction.
It is 1.4 times, and the range is 1.7 to 4 times, preferably 1.8 to 3.5 times in the radial direction. The stretching temperature varies depending on the characteristics of the composition, particularly the glass transition temperature, but is usually 75 to 1
It is selected from the range of 00 ° C. The thickness of the tube obtained as described above is not particularly limited, but is usually 30 to 15
0 μm.

The heat shrinkage characteristics of the tube of the present invention are mainly determined by the above stretching conditions. For sleeve coating such as coating of inner cans of dry batteries or other batteries, shrinkage in 100 ° C. hot water for 30 seconds is performed. The ratio is 40% or less in the length direction, preferably 30% or less, and 40% or more in the radial direction, preferably 4
It is necessary to be at least 5%. Radial shrinkage is 4
If it is less than 0%, the sleeve ends are not in close contact with each other and are raised, which is not suitable. Also, the radial shrinkage is 40%
Even if the contraction rate in the length direction exceeds 40%, the coating position may be displaced when the coating is performed, and the length of the cut needs to be increased, leading to cost increase.

As a preferred example of use of the tube of the present invention,
The coating of the negative electrode can of the lithium ion secondary battery can be mentioned.
In a lithium ion secondary battery, a wound product of a positive electrode, a negative electrode and a separator is stored in a negative electrode can together with an electrolytic solution,
A heat-shrinkable tube is coated on the outer peripheral surface of the negative electrode can or from the outer peripheral surface of the negative electrode can to the positive electrode lid for the purpose of preventing electrolyte leakage. Although ethylene carbonate and propylene carbonate are commonly used as the electrolytic solution, the tube of the present invention has high resistance to these electrolytic solutions and also has high heat resistance derived from the component (A). Can be suitably used for this purpose.

[0033]

The present invention is not limited by the following examples. The measurements and evaluations shown in the examples were carried out as follows.

1) Storage elastic modulus Viscoelasticity spectrometer VES- manufactured by Iwamoto Seisakusho KK
The measurement was performed using F3 at a vibration frequency of 10 Hz and a temperature of 30 ° C. 2) Glass transition temperature (Tg) Viscoelasticity spectrometer VES- manufactured by Iwamoto Manufacturing Co., Ltd.
The peak temperature of the main dispersion of the loss elastic modulus measured at a vibration frequency of 10 Hz using F3 was taken as the glass transition temperature.

3) Thermal shrinkage (%) After immersing in hot water of 100 ° C. for 30 seconds, the lengthwise and radial directions were calculated according to the following equations. Thermal shrinkage (%) = [(L ₀ −L ₁ ) / L ₀ ] × 100 L ₀ : Dimension before shrinkage L ₁ : Dimension after shrinkage 4) Natural shrinkage rate The tube is kept at 30 ° C. × 80% RH After being left in the tank for 30 days, the shrinkage ratio in the radial direction was calculated in the same manner as 3) above.

5) Automatic machine runnability The automatic machine runnability (SW-1) manufactured by Nippon Automatic Seiki Co., Ltd. is used to judge the automatic machine runnability, and there is no running trouble such as catching of a tube during running. The case where 1 to 5 running troubles out of 10 pieces was set as Δ, and the case where 6 or more running troubles out of 10 pieces were set as x.

6) Finishability When using a battery automatic machine (SW-1) manufactured by Nippon Automatic Seiki Co., Ltd., a tube with a folding diameter of 23 mm and a cut length of 53 mm was coated on an AA battery and then heat-shrinked. , The end is not in close contact and is in a standing state, or the coating is misaligned at the coated position x, and those where these inconveniences are extremely small Δ,
Those which did not have any of these inconveniences were evaluated as ○.

(Example 1) Random copolymer containing ethylene component and cyclic olefin component (Apel 6509 manufactured by Mitsui Petrochemical Co., Ltd .; Tg 85 ° C, or Apel 6011;
The following materials were added in the proportions shown in Table 1 to Tg 110 ° C.), 0.5 parts by weight of an antioxidant was further added, and the mixture was melt-mixed using a twin-screw extruder in the same direction to obtain a pellet of the composition. The composition was extruded from a circular die by tubing to obtain an outer diameter of 8.0.
An unstretched tube having a thickness of 0.2 mm and a thickness of 0.20 mm was obtained. This was drawn 1.2 times in the length direction and 2.
Stretching was performed 5 times to obtain a stretched tube. The evaluation results of each tube are shown in Table 1.

HDPE; E'is 1.5 × 10 ¹⁰ dyn /
cm ² high density polyethylene liquid polybutene; molecular weight 500 petroleum resin; hydrogenated cyclontadiene type petroleum resin (Arakawa Chemical Industries Alcon P100, molecular weight about 70
0)

[Table 1]

From the results shown in Table 1, the composition had a Tg of 55.
No. in the range of 90 ° C to 90 ° C. 1-3, 6-9 and 11
It can be seen that this tube has excellent natural shrinkage, runnability by automatic machines, and shrink finish. No. 1 and N
o. Comparing 2 and 3 with each other, it can be seen that the shrink finish property is improved by adding the component (C).

On the other hand, No. 4,5
Has a problem that stretching is difficult or a high shrinkage ratio cannot be obtained, and Tg is too low. In No. 10, the natural contraction is large, the waist of the tube is weak, and the running performance of the automatic machine is poor. No. In Nos. 12 to 13, since the amount of HDPE was too large, sufficient heat shrinkability was not obtained and the shrink finish was poor.

Example 2 The materials shown in Table 2 were added to a random copolymer (Apel 6509 manufactured by Mitsui Petrochemical Co., Ltd .; Tg 85 ° C.) containing an ethylene component and a cyclic olefin component, and the same procedure as in Example 1 was performed. A heat shrinkable tube was obtained.
Table 2 shows the evaluation results of each tube. E in Table 2
′ Indicates the storage elastic modulus of HDPE (high density polyethylene) and / or LDPE (low density polyethylene).
The Tg of each composition was 71 ° C.

[0043]

[Table 2]

From the results shown in Table 2, N's for general purpose polyolefin resins having E ′ of 5 × 10 ⁹ dyn / cm ² or more.
o. Nos. 16 to 19 have sufficient stiffness of the tube evaluated by the running property of the automatic machine and are in a practical range, but E'of the general-purpose polyolefin resin is less than 5 × 10 ⁹ dyn / cm ² N
o. From 14 to 15, it can be seen that the stiffness of the tube is inferior.

[0045]

INDUSTRIAL APPLICABILITY The tube of the present invention is a non-vinyl chloride type heat-shrinkable tube which is excellent in waist strength and finish of shrinkage and is cost-effective, and is useful as a coating for a negative electrode can of a lithium ion secondary battery.

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Claims (4)

[Claims] 1. A composition comprising the following components (A) and (B):
The mixing weight ratio of the component and the component (B) is A / B = 60 to 50 /
40 to 50, and the main glass transition temperature is 55 to 90.
A heat-shrinkable cyclic olefin polymer tube comprising a composition in the range of ° C. Component (A): Cyclic olefin polymer consisting of the following (A ₁ ), (A ₂ ) or (A ₃ ) (A ₁ ): From ethylene component and cyclic olefin component represented by the following general formula (1) Cyclic olefin-based random copolymer (A ₂ ): A ring-opening polymer or a hydride thereof (A ₃ ): one or more olefin components selected from the cyclic olefins represented by the following general formula (1): A mixture of A ₁ ) and (A ₂ ) (B) An olefin resin other than the component (A) having a storage elastic modulus of 5 × 10 ⁹ dyn / cm ² or more measured at a frequency of 10 Hz and a temperature of 30 ° C. ] 2. The components (A) and (B) according to claim 1 further include the following component (C), and the mixing weight ratio of the components (A) and (B) is A / B = 60 to 50 /. 40-50, (C)
Mixing weight ratio of components is 1 to 25 with respect to (A + B) 100%
%, A heat-shrinkable cyclic olefin polymer tube comprising a composition having a main glass transition temperature in the range of 55 to 90 ° C. (C): low molecular weight compound 3. The heat-shrinkable cyclic olefin polymer tube according to claim 2, wherein the low molecular weight compound is petroleum resin, rosin resin, polyterpene resin or hydrides thereof, liquid polybutene or liquid polybutadiene. . 4. A lithium ion secondary battery in which the outer peripheral surface of a negative electrode can is shrink-coated with the heat-shrinkable cyclic olefin polymer tube according to claim 1.