JP2001240113A - Packaging material - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a packaging material which is less likely to crack in a packaging material body at the time of drawing. SOLUTION: This packaging material comprises a packaging material main body 9 and a heat sealing layer 10 attached to one surface of the main body 9. The heat sealing layer 10 is formed of an acid-modified polyolefin film. On the heat sealing layer 10, a slip layer 11 is provided. The slip layer 11 is formed by applying an organosol containing acid-modified polyolefin particles and a slip agent. The other side of the packaging material body 9 (heat sealing layer 10
May be bonded to the surface opposite to the surface provided with a fluorine-based film or the like having good slipperiness. [Effect] Since this packaging material has the slip layer 11 on the heat sealing layer 10, even if it comes into contact with the female or male mold of the drawing machine, it slides well. Therefore, an excessive stress is not easily applied to the packaging material itself, and it is possible to prevent the packaging material itself from being cracked due to the stress.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging material having good moldability, and more particularly to a packaging material which is suitably used for drawing and accommodating an article in a molded recess, followed by heat sealing. Things. In particular, packaging materials used for manufacturing lithium ion secondary batteries (hereinafter, referred to as
The packaging material according to this application is referred to as “outer packaging material for a secondary battery”. ).

[0002]

2. Description of the Related Art In recent years, secondary batteries such as sheet-shaped and thin polymer lithium-ion secondary batteries have become smaller and lighter as electronic devices such as mobile communication devices, notebook computers, headphone stereos, camcorders and the like have become smaller.
It is useful as a driving source. This secondary battery has, for example, a configuration as shown in FIG. That is, a secondary battery such as a positive electrode current collector 2, a positive electrode 3, an isolating material (separator) 4, a negative electrode 5, and a negative electrode current collector 6, which are stacked in this order, and various electrolytes such as a polymer electrolyte and an electrolyte solution. The main body is configured to be packaged and housed in the secondary battery exterior materials 1 and 1. The exterior materials 1 and 1 for the secondary battery have a recess 8 formed by drawing in order to facilitate the storage of the secondary battery body at the center thereof, and are heat-sealed at the ends 7 and 7 thereof. ing.

As shown in FIG. 2, a packaging material such as the exterior material 1 for a secondary battery generally has a form in which a packaging material body 9 and a heat sealing layer 10 are laminated and adhered. As the packaging material body 9, a metal foil, a metal-deposited film, a synthetic resin film, a synthetic resin heat-resistant film, or the like is used alone or in a laminated state. As the heat sealing layer 10, an acid-modified polyolefin film is used. When a three-layer co-extruded film having the structure of acid-modified polyolefin film / polyolefin film / acid-modified polyolefin film is bonded to the metal foil to form a packaging material, the outermost layer of the acid-modified polyolefin The film becomes the heat sealing layer 10 and the other layers collectively form the packaging material body 9.

[0004] The exterior material 1 for a secondary battery is first drawn and formed into a recess 8. Then, after the secondary battery main body is housed in the recess 8, it is heat-sealed at the end 7. By the way, when forming by drawing, the secondary battery exterior material 1 is sandwiched between a male die and a female die, and the secondary battery exterior material 1 is pushed into the female die by the male die. At this time, if the heat sealing layer 10 is in contact with the male type (or female type), the male type (or female type) and the heat sealing layer 10 must slide well. This is because if the slippage is poor, an excessive stress is applied to a specific portion, and cracks or tears occur in the exterior material body. In particular, when a metal foil such as an aluminum foil is used in the exterior material main body, the metal foil may be easily cracked. When such cracks occur, there is a disadvantage that the electrolyte or the like constituting the secondary battery body leaks from this portion. In addition, such a defect can be said not only about the exterior material for secondary batteries, but also about other packaging materials.

Conventionally, the acid-modified polyolefin film used as the heat-sealing layer 10 has a poor sliding property, and often causes cracks in the metal foil of the packaging material during drawing. For this reason, attempts have been made to incorporate a slipping agent such as a surfactant into the acid-modified polyolefin film, but the improvement in slipperiness has been insufficient. The reason for this is not clear, but is considered as follows. That is, even if a slip agent such as a surfactant is contained in the acid-modified polyolefin film,
It is unlikely that it bleeds out to the surface and remains encapsulated inside. In addition, the slip agent bleed out on the surface adheres to rolls or the like or evaporates due to the heat when handling the acid-modified polyolefin film or attaching it to the packaging material body, and the slip agent itself disappears It is thought that it has been done.

From the above, it is considered that the slip property of the heat sealing layer 10 can be improved by applying a slip agent to the surface of the acid-modified polyolefin film as the heat sealing layer 10. However, as a result of actual experiments conducted by the present inventors, when a slip agent is applied to the surface of the heat sealing layer 10, the slip agent exerts an adverse effect upon heat sealing, and the adhesive strength due to heat sealing may be reduced. Was.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a packaging material capable of improving the slipperiness of a heat sealing layer and preventing a decrease in adhesive strength due to heat sealing. . The present inventor has been diligently studying to solve such a problem, and when an organosol comprising heat-fusible particles and a slip agent is applied to the surface of the heat-sealing layer, the slip property of the heat-sealing layer is reduced. Was found to be good, and a decrease in adhesive strength due to heat sealing could be prevented. The present invention has been made based on such findings.

[0008]

That is, the present invention relates to a packaging material comprising a packaging material main body and an acid-modified polyolefin film adhered to one surface of the packaging material main body as a heat sealing layer. The present invention relates to a packaging material comprising a slip layer formed by applying an organosol containing acid-modified polyolefin particles and a slip agent.

As the packaging material body 9, any conventionally known material such as a metal foil or a synthetic resin film can be used. In particular, since the present invention focuses on preventing cracking during drawing, it is preferable to use a metal foil. As the metal foil, any kind of aluminum foil, stainless steel foil, iron foil or copper foil may be used. Since packaging materials are required to be lightweight, inexpensive, etc.,
Generally, it is preferable to use an aluminum foil. Further, the packaging material body 9 may be a bonded product of a metal foil such as an aluminum foil and a synthetic resin film, and further a bonded product of a plurality of metal foils or a plurality of synthetic resin films. It may be. In addition, when the packaging material according to the present invention is used as a secondary battery exterior material, in order to prevent a short circuit of the secondary battery and to prevent peeling of the metal foil and other layers, both sides of the metal foil or Preferably, one side is subjected to an oxidation treatment, a chromium treatment, or the like.

On one side of the packaging material body 6, a heat sealing layer 10
Is provided. As the heat sealing layer 10, an acid-modified polyolefin film is used. Here, the acid-modified polyolefin is obtained by adding dicarboxylic acid to the side chain of polyethylene or polypropylene, and is generally obtained by adding maleic acid or maleic anhydride to the side chain of polypropylene. The thickness of the heat sealing layer 10 may be arbitrary, for example, about 5 to 100 μm,
About μm is good.

The surface of the heat sealing layer 10 has a slip layer 11
Is provided. The slip layer 11 is provided by applying an organosol containing acid-modified polyolefin particles and a slip agent to the surface of the heat sealing layer 10. Here, the organosol is a colloid solution in which acid-modified polyolefin particles are dispersed in a colloidal state in an organic liquid. In the present invention, a slip agent is mixed in this colloid solution. The average particle size of the acid-modified polyolefin particles may be arbitrary, for example, 5 to 10 μm.
About 6 to 8 μm. The content of the acid-modified polyolefin particles is 5 to 5 in the organosol.
It is about 50% by weight. As the organic liquid, a hydrocarbon-based liquid is used, and it is preferable to use mainly toluene. The slip agent is used in an amount of about 5 to 30% by weight, especially 7 to 25% by weight based on the weight of the acid-modified polyolefin particles.
It is preferable to contain about% by weight. If the amount of the slip agent is less than 5% by weight, the slip property of the surface of the heat sealing layer 10 tends to be insufficient. Conversely, if the amount of slip agent is 30
If the content is more than 10% by weight, the adhesive strength of the heat sealing layer 10 tends to decrease.

Various substances can be used as the slip agent. Examples of the particulate or powdery material include graphite, talc, mica, ethylene tetrafluoride resin particles and wholly aromatic polyester resin particles. Synthetic resin particles, silica powder, carbide particles and the like are used. When a particulate or powdery slip agent is used, its average particle size is 0.3 to 10
μm, and more preferably 3 to 6 μm. When the average particle diameter is less than 0.3 μm, the slipperiness of the heat sealing layer 10 tends to be insufficient, and when the average particle diameter is 10 μm, the adhesive strength by the heat sealing layer 10 tends to decrease. Occurs. The average particle size is a median particle size (median size) measured by a Coulter counter. As the fibrous material, glass fiber, metal fiber, heat-resistant synthetic fiber or the like is used.
As the liquid or paste-like material, wax, a surfactant, or the like is used. As the surfactant, a sulfonic acid-based anionic surfactant, an ammonium salt-type cationic surfactant, an alcohol ether-based nonionic surfactant, and a betaine-based amphoteric surfactant can be used. In particular, when the packaging material according to the present invention is used as an exterior material for a secondary battery, it is preferable to use a slip agent that is hardly charged. For example, in the case of a surfactant, it is preferable to use a nonionic surfactant,
In particular, it is preferable to use a nonionic surfactant obtained by adding a predetermined mole of an alkylene oxide to a higher alcohol.

Although the thickness of the slip layer 11 is arbitrary, it is generally preferable that the thickness be smaller than the thickness of the heat sealing layer 10. Therefore, in general, it is preferably 5 μm or less, particularly preferably about 1 to 3 μm. If the thickness of the slip layer 11 exceeds 5 μm, the slip layer 11 tends to inhibit the adhesion by the heat sealing layer 10.

On the other surface of the packaging material body 9, that is, on the opposite side of the packaging material body 9 to which the heat sealing layer 10 is attached,
It is preferable that a slippery film having good slipperiness is bonded. This is because both the heat sealing layer 10 side of the packaging material body 9 and the opposite side can improve the slipperiness and prevent the packaging material body 9 from being cracked or broken. As the slippery film, a fluorine-based film, a silicone-based film, or the like can be used. That is, any film that is conventionally known as a film having good releasability can be used.

The packaging material according to the present invention is suitably used as a secondary battery exterior material capable of storing and packaging a secondary battery body. However, it goes without saying that it is also used as a packaging material for packaging other storage items. In general, the packaging material according to the present invention is preferably drawn and used, but may be used without being drawn.

[0016]

Hereinafter, the present invention will be described based on examples, but the present invention is not limited to the examples. The present invention provides that when an organosol comprising heat-fusible particles and a slip agent is applied to the surface of a heat-sealing layer, it is possible to improve the slipperiness of the heat-sealing layer and to prevent a decrease in adhesive strength due to the heat-sealing. Should be interpreted as being based on the findings of

Example 1 An organosol consisting of 15 parts by weight of maleic anhydride-modified polypropylene particles having an average particle diameter of 7 μm and 85 parts by weight of toluene was applied to one surface of a 50 μm-thick aluminum foil having a double-sided chromium conversion coating formed thereon. Then 200 ° C
For 20 seconds to form an adhesive film having a thickness of 2 μm. Then, a three-layer coextruded film in which a maleic anhydride-modified polypropylene film having a thickness of 10 μm is bonded to both sides of a polypropylene film having a thickness of 30 μm is applied at a temperature of 200 ° C., a pressure of 200 kPa, and a time of 1 second, under an adhesive condition. It was crimped on the film. Thereafter, a polyester film having a thickness of 12 μm was bonded to the other surface of the aluminum foil via a urethane-based adhesive. As described above, a polyester film, a urethane-based adhesive, an aluminum foil, an adhesive film, and a three-layer coextruded film (maleic anhydride-modified polypropylene film / polypropylene film / maleic anhydride-modified polypropylene film) were laminated in this order. A laminate was obtained. In this laminate, the exposed maleic anhydride-modified polypropylene film of the three-layer coextruded film becomes a heat sealing layer, and the polyester film, urethane-based adhesive, aluminum foil, adhesive film, and three-layer coextruded film The maleic anhydride-modified polypropylene film and the polypropylene film adhered to the adhesive film serve as a packaging material body.

The heat sealing layer of the laminate has an average particle size of 7 μm.
m of maleic anhydride-modified polypropylene particles of 15 parts by weight, 1.5 parts by weight of low-molecular-weight ethylene tetrafluoride resin fine powder having an average particle size of 4 μm, and 85 parts by weight of toluene are applied. Drying was performed for 2 seconds to form a slip layer having a thickness of 2 μm. As described above, a packaging material was obtained.

Example 2 A packaging material was obtained in the same manner as in Example 1 except that an organosol containing 4.5 parts by weight of a fine powder of a low molecular weight tetrafluoroethylene resin was used. When the SEM photograph of the surface of the slip layer of the packaging material obtained in Example 2 was taken, it was as shown in FIGS. 6 and 7. FIG.
FIG. 7 is a photograph taken at a magnification of 5,000 times with a magnification of 00 times, 20 is a slip agent (fine powder of low molecular weight tetrafluoroethylene resin), and 21 is a fusion agent of modified maleic anhydride polypropylene particles. It is a formed film.
The SEM photograph shows the equipment used: JSM-JSM-
840A type, sample pretreatment; Au deposition, shooting angle; 45 °
Photographed under the conditions of tilt (1000 times), 30 ° tilt (5000 times), accelerating electrons; 15 KV.

Example 3 A packaging material was obtained in the same manner as in Example 1 except that an organosol containing 6.75 parts by weight of a fine powder of a low molecular weight ethylene tetrafluoride resin was used.

Example 4 A packaging material was obtained in the same manner as in Example 1 except that an organosol containing 10.5 parts by weight of fine powder of a low molecular weight tetrafluoroethylene resin was used.

Comparative Example 1 A packaging material was obtained in the same manner as in Example 1 except that an organosol containing no low molecular weight ethylene tetrafluoride resin fine powder was used.

Comparative Example 2 A packaging material was obtained in the same manner as in Example 1 except that no slip layer was provided.

The following tests were performed on the packaging materials obtained in Examples 1 and 2 and Comparative Examples 1 and 2. Table 1 shows the results. [Static friction coefficient]: 200 g of SUS was placed on the surface of the slip layer (heat-sealing layer for Comparative Example 2), and JIS P
The static friction coefficient (tan θ) was measured according to the tilt method described in 8147 “Test for friction coefficient of paper and paperboard”. [Adhesive strength by heat sealing]: Slip layer surface (Comparative Example 2)
About 200 ° C., 20 ° C.
An adhesive sample is prepared by pressure bonding at 0 kPa for 1 second. The width of the adhesive sample was cut to 15 mm, and a 90 ° peel test was performed at a tensile speed of 200 mm / min to measure the adhesive strength (N / 15 mm width). [Drawing formability]: Using a drawing forming machine (female mold) as shown in FIGS. 4 and 5, the drawing depth h was set to 2.5 mm and 3.0 m.
m, 3.5 mm, 4.0 mm, and 4.5 mm were changed to five stages, and drawn by a male mold matching this female mold. Then, it was visually observed whether or not cracks occurred in the packaging material main body at the corner portion and the straight portion.

[0025]

[Table 1] (Note) In Table 1, “○” indicates that cracks could not be confirmed at both corners and straight parts, and “×” indicates that cracks could be confirmed at straight parts, and “×” Indicates that cracks were confirmed at both the corner portion and the straight portion.

As is clear from the results in Table 1, Example 1
It can be seen that the packaging materials according to Comparative Examples 1 and 2 have a smaller coefficient of friction than the packaging materials according to Comparative Examples 1 and 2, and are less likely to crack in the packaging material body even during drawing.

[0027]

In the packaging material according to the present invention, a slip layer is provided on the surface of the heat sealing layer. The reason why the slip layer exhibits good slip properties is considered as follows. That is, the slip layer is formed by applying an organosol containing acid-modified polyolefin particles and a slip agent. Therefore, since the slip layer is formed by fusing the acid-modified polyolefin particles, the slip agent stays in the particle gap and is hardly taken into the particles (see FIGS. 6 and 7), and the slip property inherent in the slip agent is obtained. It is thought that it exerts. Further, since the acid-modified polyolefin particles in the slip layer are made of the same material as the acid-modified polyolefin film constituting the heat sealing layer, it is considered that even during heat sealing, it is difficult to inhibit the adhesion of the heat sealing layer. .

[0028]

As described above, when the packaging material according to the present invention is drawn and formed, the drawability of the male or female mold of the drawing machine is good, and an excessive stress is not easily applied to the packaging material body. This has the effect that the packaging material body is less likely to crack or break. In addition, even when heat sealing is performed after drawing, it is possible to prevent a decrease in the adhesive strength of the heat sealing layer to a certain extent, and it is possible to obtain an effect that heat sealing can be performed well.

Further, when drawing is performed by using the packaging material according to the present invention, it is possible to form a deeper shape than the conventional one. Therefore, even if the formed concave portion becomes deeper and, for example, the secondary battery main body becomes thicker to increase the battery capacity, the secondary battery main body can be stored and packaged.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an example of an internal structure of a sheet-shaped and thin polymer lithium ion secondary battery.

FIG. 2 is a schematic sectional view showing a general example of a packaging material.

FIG. 3 is a schematic sectional view of a packaging material according to an example of the present invention.

FIG. 4 is a schematic plan view showing an example of a female mold of the drawing machine.

FIG. 5 is a schematic diagram of a cross section taken along line AA of the female die shown in FIG. 4;

FIG. 6 is an SEM photograph of the surface of a slip layer of the packaging material obtained by the method according to Example 2, with a magnification of 1000 times.

FIG. 7 is a SEM photograph of the surface of a slip layer of the packaging material obtained by the method according to Example 2, and the magnification is 5000 times.

[Explanation of symbols]

Reference Signs List 9 packaging material body 10 heat sealing layer 11 slip layer 20 slip agent (fine powder of low molecular weight tetrafluoroethylene resin) 21 film formed by fusion of maleic anhydride-modified polypropylene particles

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C09D 123/26 C09D 123/26 H01M 2/02 H01M 2/02 K (72) Inventor Yuichi Ninomiya Kusatsu, Shiga Prefecture 61-8 Sasaya, Ichiyamadera-cho, Japan Foil Co., Ltd. Shiga Plant (72) Inventor Ken Noguchi 5-13-9, Nishinakajima, Yodogawa-ku, Osaka-shi, Japan F-term Co., Ltd. F-term (reference) 3E086 AB01 AD05 BA04 BA13 BA15 BA24 BA33 BB51 BB55 BB85 BB90 CA40 4F100 AB10 AB33 AK03B AK03C AK03H AK07C AK07H AK17D AK18H AK41 AK51G AL07B AL07C AL07H J00 AT00A BA03 BA04 BA04 BA07 BA10A BA10C BA10C CA10CBA10C CA10C DA016 DA026 DJ016 DJ046 DJ056 FA082 FA086 FD172 FD176 GJ02 GQ00 4J038 CB031 CD122 DD062 HA036 HA456 HA536 HA546 KA09 KA20 LA06 MA08 MA 10 NA23 PA19 PB09 PC08 5H011 AA01 AA03 AA09 CC02 CC10

Claims (6)

[Claims] 1. A packaging material comprising a packaging material body and an acid-modified polyolefin film adhered to one surface of the packaging material body as a heat sealing layer, wherein the heat-sealing layer surface has acid-modified polyolefin particles and a slip agent. A packaging material provided with a slip layer formed by applying an organosol containing 2. The packaging material according to claim 1, wherein the acid-modified polyolefin is a maleic anhydride-modified polyolefin. 3. The packaging material according to claim 1, wherein the slip agent is a synthetic resin particle. 4. The packaging material according to claim 1, wherein the slip agent is a nonionic surfactant. 5. A slidable film such as a fluorine-based film is bonded to the other surface of the packaging material main body.
The packaging material according to any one of the above. 6. The packaging material according to claim 1, which is used as an exterior material for a secondary battery.