JP2020029557A - Adhesive composition, laminate, and packaging material for lithium ion battery - Google Patents

Abstract

To provide an adhesive composition that shows excellent adhesiveness between a polyolefin resin base material and a metal base material, and electrolyte resistance, and exhibits excellent heat resistance; and also provide a laminate containing an adhesive layer composed of the adhesive composition, and a packaging material for lithium ion battery having the laminate as a component.SOLUTION: An adhesive composition contains an acid-modified polyolefin (A), a polyphenylene ether (B) and an isocyanate curing agent (C).SELECTED DRAWING: None

Description

  The present invention relates to an adhesive composition, a laminate, and a packaging material for a lithium ion battery.

  2. Description of the Related Art In recent years, lithium-ion batteries (hereinafter referred to as LiB), which can be made ultra-thin and compact, have been actively developed as batteries used in personal digital assistants, mobile phones and other portable terminal devices, video cameras, satellites, and the like. This LiB packaging material is different from a conventionally used metal can in that it has a light weight and allows the shape of the battery to be freely selected, so that a laminate having a configuration such as a base material layer / barrier layer / sealant layer is used. It is being used.

LiB is impregnated with an electrolyte or a solution in which a lithium salt is dissolved in an aprotic solvent such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate, together with a positive electrode material and a negative electrode material as battery contents. And an electrolyte layer made of a polymer gel. When such a highly permeable solvent passes through the sealant layer, the lamination strength between the barrier layer and the sealant layer is reduced to cause delamination, which eventually causes a problem that the electrolyte leaks out. In addition, materials such as LiPF ₆ and LiBF ₄ are used as a lithium salt as an electrolyte of the battery, but these salts generate hydrofluoric acid by a hydrolysis reaction with moisture, and the hydrofluoric acid corrodes the barrier layer. By doing so, the laminate strength is reduced. It is necessary that the battery packaging material has resistance to the electrolyte as described above.

  In addition, LiB needs to have more severe resistance assuming that it is used in various environments. For example, when used in a mobile device, it is required to have a liquid leakage resistance in a high temperature environment of 60 to 70 ° C. such as in a vehicle. Also, assuming that it is used by a mobile phone and accidentally dropped into water, it is necessary to have water resistance so that moisture does not enter.

  Under such circumstances, various packaging materials for lithium batteries with improved electrolyte resistance have been proposed (for example, see Patent Documents 1 and 2). Patent Document 1 describes an adhesive containing a modified olefin polymer and a polyisocyanate curing agent. Patent Document 2 describes an adhesive composition comprising two types of modified polyolefin resin, a tackifier and a curing agent, and the curing agent is an epoxy curing agent. By containing an agent, resistance to an electrolytic solution at 85 ° C. is achieved. Patent Document 3 describes an adhesive composition containing a modified polyolefin-based resin, a tackifier, and a crosslinking agent. The adhesive composition contains not only the modified polyolefin resin and the curing agent but also a tackifier. Good adhesion at ℃ is achieved.

WO 2014/123183 pamphlet WO 2017/187904 pamphlet JP 2017-101145 A

However, the proposed adhesive composition was still insufficient in heat resistance and durability.
Specifically, for use in vehicles, use in harsh environments is expected compared to general small LiB applications. Therefore, the proposed adhesive composition has poor adhesiveness of the adhesive after curing in a high-temperature environment, or has a low adhesive strength after long-term immersion in an electrolytic solution, The properties and durability were still insufficient.

  The present invention provides an adhesive composition which exhibits good adhesion between a polyolefin resin substrate and a metal substrate and electrolytic solution resistance (durability) and exhibits excellent heat resistance. Further, the present invention provides a laminate including an adhesive layer made of the adhesive composition and a packaging material for a lithium ion battery including the laminate as a constituent member.

  In order to achieve the above object, the present inventors have conducted intensive studies and found that the combination of an acid-modified polyolefin, polyphenylene ether and an isocyanate curing agent is effective, and have proposed the following invention. That is, the present invention has the following configurations.

[1] An adhesive composition containing an acid-modified polyolefin (A), polyphenylene ether (B), and an isocyanate curing agent (C).
[2] The adhesive composition according to [1], wherein the number average molecular weight of the polyphenylene ether (B) is 20,000 or less.
[3] The adhesive composition according to [1] or [2], wherein the polyphenylene ether (B) is functionalized at the terminal of the main chain.
[4] The adhesive composition of [1] to [3], wherein the polyphenylene ether (B) is 0.1 to 20 parts by mass with respect to 100 parts by mass of the acid-modified polyolefin (A).
[5] The adhesive composition according to any one of [1] to [4], wherein the acid value of the acid-modified polyolefin (A) is 1 to 40 mgKOH / g.
[6] The adhesive composition according to any one of [1] to [5], which is used for bonding a polyolefin resin substrate and a metal substrate.
[7] A laminate of a polyolefin resin substrate and a metal substrate bonded by the adhesive composition according to any one of [1] to [6].
[8] A packaging material for a lithium ion battery containing the laminate according to [7] as a constituent member.

    Since the adhesive composition of the present invention contains an acid-modified polyolefin, polyphenylene ether, and an isocyanate curing agent, the adhesive composition exhibits good adhesion between a polyolefin resin substrate and a metal substrate and electrolytic solution resistance (durability). And shows excellent heat resistance after curing.

  Hereinafter, embodiments of the present invention will be described in detail.

<Acid-modified polyolefin (A)>
The acid-modified polyolefin (A) used in the present invention is not limited, but at least one of polyethylene, polypropylene and propylene / α-olefin copolymer may contain at least one of α, β-unsaturated carboxylic acid and its acid anhydride. Those obtained by grafting one type are preferred.

  The propylene / α-olefin copolymer is obtained by copolymerizing α-olefin with propylene as a main component. As the α-olefin, for example, one or several kinds of ethylene, 1-butene, 1-heptene, 1-octene, 4-methyl-1-pentene, vinyl acetate and the like can be used. Among these α-olefins, ethylene and 1-butene are preferred, and 1-butene is most preferred.

  Examples of at least one of the α, β-unsaturated carboxylic acids and their acid anhydrides include maleic acid, itaconic acid, citraconic acid and acid anhydrides thereof. Of these, acid anhydrides are preferred, and maleic anhydride is more preferred. Specifically, maleic anhydride-modified polypropylene, maleic anhydride-modified propylene / ethylene copolymer, maleic anhydride-modified propylene / 1-butene copolymer, maleic anhydride-modified propylene / ethylene / 1-butene copolymer, etc. These acid-modified polyolefins can be used alone or in combination of two or more. Among them, a maleic anhydride-modified propylene / 1-butene copolymer is preferred.

  The acid value of the acid-modified polyolefin (A) is from 1 to 40 mgKOH / g from the viewpoints of adhesiveness with the polyolefin resin base material, compatibility with the polyphenylene ether (B), and crosslinking density with the isocyanate curing agent (C). It is preferably within the range. The range is more preferably 3 to 40 mgKOH / g, still more preferably 4 to 30 mgKOH / g, and particularly preferably 5 to 20 mgKOH / g. When the value is less than the above value, the crosslink density is low, so that the adhesiveness may be poor. On the other hand, when it exceeds the above value, a problem may occur in pot life.

  The melting point (Tm) of the acid-modified polyolefin (A) is preferably in the range of 50C to 95C. More preferably, it is in the range of 60C to 93C, particularly preferably in the range of 65C to 92C, more preferably in the range of 75C to 90C, most preferably in the range of 78C to 85C. When the value is less than the above value, the cohesive force derived from the crystal becomes weak, and the adhesiveness and chemical resistance may be poor. On the other hand, if it exceeds the above-mentioned value, the pot life property and the fluidity are low, and a problem may arise in the operability when bonding.

  The acid-modified polyolefin (A) preferably has propylene and 1-butene as olefin components. The preferred range of the molar ratio of propylene to 1-butene is propylene / 1-butene = 98 to 60/2 to 40, and more preferably 90 to 70/10 to 30. When the molar ratio of propylene is 60% or more, excellent adhesion to a polyolefin substrate can be exhibited. If the molar ratio of 1-butene is 2% or more, the solubility in an organic solvent increases, and the coatability as an adhesive improves.

  As the olefin component, the total amount of the propylene and 1-butene components is preferably at least 62 mol%. It is more preferably at least 80 mol%, further preferably at least 90 mol%, particularly preferably at least 95 mol%, and even if it is at least 100 mol%. If it is less than the above value, the adhesiveness and chemical resistance may be reduced.

  The weight-average molecular weight (Mw) of the acid-modified polyolefin (A) is preferably in the range of 10,000 to 200,000. It is more preferably in the range of 20,000 to 180,000, further preferably in the range of 30,000 to 160,000, particularly preferably in the range of 40,000 to 140,000, and most preferably in the range of 50 to 140,000. 000 to 110,000. If it is less than the above value, the cohesive strength may be weak and the adhesiveness may be poor. On the other hand, if it exceeds the above-mentioned value, there may be a problem in operability at the time of adhesion due to low fluidity, and the compatibility with the polyphenylene ether (B) may be poor.

  The method for producing the acid-modified polyolefin (A) is not particularly limited, and may be, for example, a radical grafting reaction (that is, a method in which a radical species is generated with respect to a polymer serving as a main chain, the unsaturated carboxylic acid and A reaction for graft-polymerizing an acid anhydride).

  The radical generator is not particularly limited, but it is preferable to use an organic peroxide. The organic peroxide is not particularly limited, but may be di-tert-butylperoxyphthalate, tert-butyl hydroperoxide, dicumyl peroxide, benzoyl peroxide, tert-butylperoxybenzoate, tert-butylperoxy-. Peroxides such as 2-ethylhexanoate, tert-butyl peroxypivalate, methyl ethyl ketone peroxide, di-tert-butyl peroxide and lauroyl peroxide; azobisisobutyronitrile, azobisisopropionitrile and the like Azonitriles and the like.

  These acid-modified polyolefins (A) may be used alone or in combination of two or more.

<Polyphenylene ether (B)>
The polyphenylene ether (B) used in the present invention is not limited, but preferably a compound having a structural unit represented by the following general formula (1) can be used.

In the general formula (1), R1, R2, R3, and R4 each independently represent a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkenyl group, an optionally substituted alkynyl group, It is preferably an aryl group which may be substituted, an aralkyl group which may be substituted or an alkoxy group which may be substituted. The “alkyl group” of the optionally substituted alkyl group is, for example, a linear or branched alkyl group having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms. More specifically, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl and the like, and a methyl or ethyl group More preferably, there is. Examples of the “alkenyl group” of the alkenyl group which may be substituted include, for example, an ethenyl group, a 1-propenyl group, a 2-propenyl group, a 3-butenyl group, a pentenyl group, a hexenyl group and the like. And more preferably a -propenyl group. Examples of the “alkynyl group” of the optionally substituted alkynyl group include, for example, an ethynyl group, a 1-propynyl group, a 2-propynyl (propargyl) group, a 3-butynyl group, a pentynyl group, a hexynyl group, and the like. More preferably, it is a group. Examples of the “aryl group” of the optionally substituted aryl group include a phenyl group, a naphthyl group and the like, and a phenyl group is more preferable. Examples of the “aralkyl group” of the optionally substituted aralkyl group include, for example, a benzyl group, a phenethyl group, a 2-methylbenzyl group, a 4-methylbenzyl group, an α-methylbenzyl group, a 2-vinylphenethyl group, Examples thereof include a vinylphenethyl group, and more preferably a benzyl group. The “alkoxy group” of the optionally substituted alkoxy group is, for example, a linear or branched alkoxy group having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms. For example, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a sec-butoxy group, a tert-butoxy group, a pentyloxy group, a hexyloxy group and the like are mentioned, and the methoxy group or the ethoxy group is more preferable. preferable. When the above alkyl group, aryl group, alkenyl group, alkynyl group, aralkyl group and alkoxy group are substituted, they may have one or more substituents. Examples of such a substituent include a halogen atom (for example, a fluorine atom, a chlorine atom, and a bromine atom) and an alkyl group having 1 to 6 carbon atoms (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group). , Isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group), aryl group (eg, phenyl group, naphthyl group), alkenyl group (eg, ethenyl group, 1-propenyl group, 2-propenyl group) ), An alkynyl group (eg, ethynyl group, 1-propynyl group, 2-propynyl group), an aralkyl group (eg, benzyl group, phenethyl group), an alkoxy group (eg, methoxy group, ethoxy group) and the like. Among them, it is preferred that (i) R1 and R4 are methyl groups, R2 and R3 are hydrogen, or (ii) R1 and R4 are hydrogen and R2 and R3 are methyl groups.

  The polyphenylene ether (B) is partially or wholly modified with an ethylenically unsaturated group such as a vinylbenzyl group, an epoxy group, an amino group, a hydroxy group, a mercapto group, a carboxyl group, and a silyl group. It may be polyphenylene ether. The polyphenylene ether (B) preferably has the main chain terminal functionalized with the functional group. More preferably, the terminal of the main chain has an epoxy group or an ethylenically unsaturated group. As the ethylenically unsaturated group, an ethenyl group, an allyl group, a methacryl group, a propenyl group, a butenyl group, a hexenyl group, an alkenyl group such as an octenyl group, a cyclopentenyl group, a cycloalkenyl group such as a cyclohexenyl group, a styrene group, An alkenylaryl group such as a vinylbenzyl group and a vinylnaphthyl group is exemplified. Both ends of the main chain may be the same functional group or different functional groups. From the viewpoint of compatibility with the acid-modified polyolefin (A), the terminal of the main chain is preferably a styrene group, and more preferably both terminals of the main chain are styrene groups. When the compatibility is good, the pot life tends to be good. Further, the styrene group preferably has a vinyl group at an ortho position or a para position, and particularly preferably has a vinyl group at a para position.

The compound having the structural unit represented by the general formula (1) most preferably has the structure represented by the general formula (2).

In the general formula (2), n is preferably 2 or more, more preferably 4 or more, and preferably 165 or less, more preferably 60 or less, further preferably 23 or less, and particularly preferably 23 or less. Preferably it is 20 or less, most preferably 18 or less.

  The number average molecular weight of the polyphenylene ether (B) is preferably 20,000 or less. It is more preferably 10,000 or less, and still more preferably 2500 or less. It is more preferably at most 2,000, particularly preferably at most 1,800, most preferably at most 1,500. The number average molecular weight of the polyphenylene ether (B) is preferably 500 or more, and more preferably 700 or more. By setting the number average molecular weight of the polyphenylene ether (B) to the lower limit or more, the flexibility of the obtained adhesive layer can be improved. On the other hand, when the number average molecular weight of the polyphenylene ether (B) is equal to or less than the upper limit, solubility in an organic solvent can be improved.

These polyphenylene ethers may be used alone or in combination of two or more.

  The content of the polyphenylene ether (B) in the adhesive composition of the present invention is preferably in the range of 0.1 to 20 parts by mass, more preferably 0.2 to 20 parts by mass, based on 100 parts by mass of the acid-modified polyolefin (A). The amount is 10 parts by mass, more preferably 0.3 to 7 parts by mass, most preferably 0.5 to 5 parts by mass. When the amount is 0.1 parts by mass or more, the heat resistance of the adhesive after curing tends to be good. When the amount is 20 parts by mass or less, the cohesive force of the acid-modified polyolefin (A) is sufficiently exhibited, and the chemical resistance tends to be further improved.

<Isocyanate curing agent (C)>
The isocyanate curing agent used in the present invention is not particularly limited, and diisocyanates, triisocyanates and compounds derived therefrom can be preferably used. Examples of the isocyanate curing agent include an aromatic curing agent, an aliphatic curing agent, and an alicyclic curing agent. Examples of the aromatic curing agent include 2,4-tolylene diisocyanate and 2,6-tolylene isocyanate. Diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthalenediisocyanate, hexamethylene diisocyanate (HDI) as an aliphatic curing agent, isophorone diisocyanate as an alicyclic curing agent, bis (4-isocyanatocyclohexyl) Examples thereof include methane and diisocyanates such as hydrogenated diphenylmethane diisocyanate. Further, a compound derived from the diisocyanate, that is, an isocyanurate form, an adduct form, a biuret form, a uretdione form, an allophanate form, a prepolymer having an isocyanate residue (a low polymer obtained from diisocyanate and polyol), tri Glycidyl isocyanurate, a complex thereof, and the like are included. These may be used alone or in combination of two or more. As the isocyanate curing agent used in the present invention, an aliphatic curing agent is preferable.

  As the isocyanate curing agent (C) used in the present invention, a compound having an isocyanurate of the diisocyanate compound is preferable because of particularly excellent electrolytic solution resistance.

  The amount of the isocyanate curing agent (C) in the adhesive composition of the present invention is preferably in the range of 1 to 30 parts by mass, more preferably 2 to 25 parts by mass, based on 100 parts by mass of the acid-modified polyolefin (A). And more preferably 3 to 20 parts by mass, particularly preferably 5 to 15 parts by mass. When the amount is 1 part by mass or more, a sufficient curing effect is obtained, and the adhesiveness and chemical resistance are further improved. When the amount is less than 30 parts by mass, the pot life and the adhesiveness are improved, and the improvement of the followability makes it difficult to generate pinholes during molding. Further, it is more preferable from the viewpoint of cost.

<Organic solvent (D)>
The adhesive composition of the present invention can further contain an organic solvent (D). The organic solvent (D) used in the present invention is not particularly limited as long as it can dissolve the acid-modified polyolefin (A), polyphenylene ether (B), and isocyanate curing agent (C). Specifically, for example, aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as hexane, heptane, octane, and decane; and alicyclic hydrocarbons such as cyclohexane, cyclohexene, methylcyclohexane, and ethylcyclohexane. Alcohol solvents such as hydrogen, methanol, ethanol, isopropyl alcohol, butanol, pentanol, hexanol, propanediol, and phenol; ketone solvents such as acetone, methyl isobutyl ketone, methyl ethyl ketone, pentanone, hexanone, cyclohexanone, isophorone, and acetophenone; methyl Cellsolves such as Cellsolve and ethyl Cellsolve; ester solvents such as methyl acetate, ethyl acetate, butyl acetate, propyl acetate, amyl acetate, methyl propionate and butyl formate; Glycol mono n-butyl ether, ethylene glycol mono iso-butyl ether, ethylene glycol mono tert-butyl ether, diethylene glycol mono n-butyl ether, diethylene glycol mono iso-butyl ether, triethylene glycol mono n-butyl ether, tetraethylene glycol mono n-butyl ether, etc. A glycol ether solvent or the like can be used, and one or more of these can be used in combination. Particularly, methylcyclohexane and toluene are preferred from the viewpoint of work environment and drying property.

  The organic solvent (D) is preferably at least 80 parts by mass, more preferably at least 90 parts by mass, and more preferably at least 100 parts by mass, based on 100 parts by mass of the acid-modified polyolefin (A). It is particularly preferably at least 110 parts by mass. Further, it is preferably at most 2,000 parts by mass, more preferably at most 1,500 parts by mass, further preferably at most 1,000 parts by mass, further preferably at most 900 parts by mass, more preferably at most 800 parts by mass. It is particularly preferable that the content is not more than 700 parts by mass. When the amount is 80 parts by mass or more, the solution state and the pot life are improved, and when the amount is 2,000 parts by mass or less, there is a tendency that the production cost and the transportation cost are advantageous.

  As the organic solvent (D), at least one selected from the group consisting of aromatic hydrocarbons, aliphatic hydrocarbons, and alicyclic hydrocarbons from the viewpoint of the solution state and pot life of the adhesive composition. A mixed solution of at least one solvent (D2) selected from the group consisting of a solvent (D1), an alcohol solvent, a ketone solvent, an ester solvent, and a glycol ether solvent is preferable. The mixing ratio is preferably solvent (D1) / solvent (D2) = 50 to 97/50 to 3 (mass ratio), more preferably 55 to 95/45 to 5 (mass ratio), It is more preferably from 60 to 80/40 to 20 (mass ratio), and particularly preferably from 60 to 70/40 to 30 (mass ratio). If the ratio is outside the above range, the solution state and pot life of the adhesive composition may decrease. It is particularly preferable that the solvent (D1) is an aromatic hydrocarbon or an alicyclic hydrocarbon, and the solvent (D2) is a ketone solvent or an ester solvent. More preferably, the solvent (D1) is methylcyclohexane and the solvent (D2) is ethyl acetate.

  The adhesive composition according to the present invention includes various tackifiers and plasticizers in addition to the acid-modified polyolefin (A), polyphenylene ether (B), and isocyanate curing agent (C) as long as the performance of the present invention is not impaired. Additives such as an agent, a stress relieving agent, a curing accelerator, a flame retardant, a pigment, and an anti-blocking agent can be used.

<Laminate>
The laminate of the present invention is obtained by laminating a polyolefin resin base and a metal base with the adhesive composition according to the present invention.

As a method of laminating, a conventionally known laminate manufacturing technique can be used. For example, although not particularly limited, the adhesive composition is applied to the surface of the metal substrate by using an appropriate application means such as a roll coater or a bar coater, and dried. After drying, while the layer of the adhesive composition (adhesive layer) formed on the surface of the metal substrate is in a molten state, the polyolefin resin substrate is laminated and adhered (laminated) to the application surface to form a laminate. Obtainable.
The thickness of the adhesive layer formed by the adhesive composition is not particularly limited, but is preferably 0.5 to 10 μm, more preferably 0.8 to 9.5 μm, and more preferably 1 to 9 μm. More preferably,

<Polyolefin resin substrate>
The polyolefin resin substrate may be appropriately selected from conventionally known polyolefin resins. For example, although not particularly limited, polyethylene, polypropylene, ethylene-propylene copolymer and the like can be used. Among them, use of a non-stretched polypropylene film (hereinafter, also referred to as CPP) is preferable. The thickness is not particularly limited, but is preferably 20 to 100 μm, more preferably 25 to 95 μm, and further preferably 30 to 90 μm. The polyolefin resin base material may be mixed with a pigment or various additives as necessary, or may be subjected to a surface treatment.

<Metal base material>
Although it does not specifically limit as a metal base material, For example, various metals, such as aluminum, copper, steel, chromium, zinc, duralumin, and die casting, and alloys thereof can be used. In addition, any shape such as a metal foil, a rolled steel plate, a panel, a pipe, a can, and a cap can be used. Generally, aluminum foil is preferred from the viewpoint of workability and the like. Further, although it varies depending on the purpose of use, it is generally used in the form of a sheet having a thickness of 0.01 to 10 mm, preferably 0.02 to 5 mm.
The surface of these metal substrates may be subjected to a surface treatment in advance, or may be left untreated. In any case, the same effect can be exhibited.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the embodiments.

<Production example of acid-modified polyolefin (A)>
Production Example 1
In a 1 L autoclave, 100 parts by mass of a propylene-butene copolymer (Tm: 80 ° C., propylene / butene = 80/20 molar ratio), 233 parts by mass of toluene and 20 parts by mass of maleic anhydride, di-tert-butyl peroxide 5 After the addition of parts by mass, the temperature was raised to 140 ° C., and the mixture was further stirred for 1 hour (here, it was referred to as “reacted” for 1 hour). Thereafter, the obtained reaction solution was cooled to 100 ° C., and then poured with stirring into a container containing 717 parts by mass of toluene and 950 parts by mass of methyl ethyl ketone, which had been previously heated to 40 ° C., cooled to 40 ° C., and further stirred for 30 minutes. Then, the resin was precipitated by further cooling to 25 ° C. (Here, an operation of pouring the reaction solution into a solvent such as methyl ethyl ketone with stirring and cooling to precipitate the resin is referred to as “reprecipitation”). Thereafter, the slurry liquid containing the resin was centrifuged to separate an acid-modified propylene-butene copolymer on which maleic anhydride was graft-polymerized from (poly) maleic anhydride and a low molecular weight product.
Further, the acid-modified propylene-butene copolymer taken out by centrifugation was charged with stirring into a new container of 2,000 parts by mass of methyl ethyl ketone kept at 25 ° C. in advance, and stirring was continued for 1 hour. Thereafter, the slurry liquid was centrifuged to further separate the acid-modified propylene-butene copolymer from (poly) maleic anhydride and a low molecular weight product. This operation was repeated twice to purify (here, the acid-modified propylene-butene copolymer taken out by centrifugation was added to methyl ethyl ketone with stirring, and centrifuged again to strengthen the purification. Is referred to as “reslurry”).
After purification, the polymer was dried at 70 ° C. for 5 hours under reduced pressure to obtain a maleic anhydride-modified propylene-butene copolymer (PO-1, acid value 25 mg KOH / g, weight average molecular weight 60,000, Tm 80 ° C.) which is an acid-modified polyolefin. ) Got.

Production Example 2
The charge amount of maleic anhydride was changed to 3 parts by mass, the charge amount of di-tert-butyl peroxide was changed to 1 part by mass, the number of reslurries was changed once, and the amount of methyl ethyl ketone to be charged at the time of reslurry was changed to 1000 parts by mass. The same procedure as in Production Example 1 was carried out except that a maleic anhydride-modified propylene-butene copolymer (PO-2, acid value 5 mgKOH / g, weight average molecular weight 90,000, Tm80 ° C.) as an acid-modified polyolefin was obtained. Obtained.

Production Example 3
The propylene-butene copolymer (Tm: 80 ° C.) used in Production Example 1 was changed to a propylene-butene copolymer (Tm: 90 ° C., propylene / butene = 85/15 molar ratio), and maleic anhydride was charged. Same as Production Example 1 except that the amount was changed to 3 parts by mass, the charged amount of di-tert-butyl peroxide was changed to 1 part by mass, the number of times of reslurry was changed to 1, and the amount of methyl ethyl ketone to be charged at the time of reslurry was changed to 1000 parts by mass. Thus, a maleic anhydride-modified propylene-butene copolymer (PO-3, acid value 5 mgKOH / g, weight-average molecular weight 90,000, Tm 90 ° C.) as an acid-modified polyolefin was obtained.

Production Example 4
The propylene-butene copolymer (Tm: 80 ° C) used in Production Example 1 was changed to a propylene-butene copolymer (Tm: 70 ° C, propylene / butene = 75/25 molar ratio), and maleic anhydride was charged. Same as Production Example 1 except that the amount was changed to 3 parts by mass, the charged amount of di-tert-butyl peroxide was changed to 1 part by mass, the number of times of reslurry was changed to 1, and the amount of methyl ethyl ketone to be charged at the time of reslurry was changed to 1000 parts by mass. Thus, a maleic anhydride-modified propylene-butene copolymer (PO-4, acid value 5 mgKOH / g, weight average molecular weight 90,000, Tm 70 ° C.), which is an acid-modified polyolefin, was obtained.

(Preparation of main agent 1)
In a 500 ml four-necked flask equipped with a water-cooled reflux condenser and a stirrer, 100 parts by mass of the maleic anhydride-modified propylene-butene copolymer (PO-1) obtained in Production Example 1 and polyphenylene ether (B- 3 parts by mass of 1), 280 parts by mass of methylcyclohexane and 120 parts by mass of ethyl acetate were charged, the temperature was raised to 80 ° C. with stirring, the stirring was continued for 1 hour, and then the main agent 1 was obtained by cooling.

(Preparation of main agents 2 to 13)
The acid-modified polyolefin, polyphenylene ether, and organic solvent were changed as shown in Table 1, and main agents 2 to 13 were produced in the same manner as in main agent 1. The amounts are shown in Table 1.

The polyphenylene ether (B) used in Table 1 is as follows.
B-1: OPE (registered trademark) 2St-2200 manufactured by Mitsubishi Gas Chemical Company, Inc. (compound having a number average molecular weight of 2,200 and a structure of the general formula (2))
B-2: OPE (registered trademark) 2St-1200 manufactured by Mitsubishi Gas Chemical Company (compound having a number average molecular weight of 1200 and a structure of the general formula (2))
B-3: NORYL (registered trademark) SA-90 manufactured by Sabic (a compound having a number average molecular weight of 1800 and having a structure of the general formula (1) and having a hydroxy group at the terminal of the main chain)
B-4: PPO resin powder manufactured by Sabic (compound having a number average molecular weight of 20,000, having a structure of general formula (1), and having a hydroxy group at the terminal of the main chain)

Example 1
500 parts by mass of the main agent 1 and 10 parts by mass of the isocyanate compound (C-1) were blended to obtain an adhesive composition. Using this adhesive composition, a laminate was prepared by the following method.

Preparation of a laminate of a metal substrate and a polyolefin resin substrate An aluminum foil (8079-0, 40 μm thick, manufactured by Sumitomo Aluminum Foil Co., Ltd.) was used for the metal substrate, and unstretched polypropylene was used for the polyolefin resin substrate. A film (Pyrene (registered trademark) film CT, manufactured by Toyobo Co., Ltd., thickness: 40 μm) (hereinafter, also referred to as CPP) was used.
The obtained adhesive composition was applied to a metal substrate by using a bar coater so that the thickness of the dried adhesive layer was 3 μm. The coated surface was dried in a 100 ° C. atmosphere for 5 minutes using a warm air drier to obtain a metal substrate on which an adhesive layer having a thickness of 3 μm was laminated. A polyolefin resin base material is superimposed on the surface of the adhesive layer, and is applied at a lamination temperature of 100 ° C. at a lamination temperature of 100 ° C. at 0.3 MPa and 1 m / min using a small table test laminator (SA-1010-S) manufactured by Tester Sangyo. The laminate was cured at 40 ° C. and 50% RH for 5 days to obtain a laminate.
The resulting laminate was evaluated for adhesion by initial adhesion, heat resistance by storage elastic modulus, durability by electrolyte resistance, and storage stability by pot life. Table 2 shows the results.

Examples 2 to 15 and Comparative Examples 1 to 4
An adhesive composition was prepared by changing the main agent and the curing agent as shown in Table 2, and a laminate was prepared in the same manner as in Example 1, and each evaluation was performed.

The curing agent (C) used in Table 2 is as follows.
C-1: Sumidur (registered trademark) N3300 (manufactured by Covestro) (HDI type isocyanurate)
C-2: Epicron (registered trademark) HP-7200 (manufactured by DIC) (dicyclopentadiene skeleton-containing epoxy resin)
C-3: Duranate (registered trademark) 24A-100 (manufactured by Asahi Kasei Corporation) (HDI biuret)

Analytical measurement and evaluation were performed on each of the acid-modified polyolefin, main agent, and adhesive composition obtained as described above based on the following methods.
<Measurement of acid value>
The acid value (mgKOH / g) in the present invention is the amount of KOH required to neutralize 1 g of the acid-modified polyolefin (A), and was measured according to the test method of JIS K0070 (1992). . Specifically, after dissolving 1 g of the acid-modified polyolefin in 100 g of xylene adjusted to a temperature of 100 ° C., a 0.1 mol / L potassium hydroxide ethanol solution [trade name “0” using phenolphthalein as an indicator at the same temperature. .1 mol / L ethanolic potassium hydroxide solution ", manufactured by Wako Pure Chemical Industries, Ltd.]. At this time, the acid value (mgKOH / g) was calculated by converting the amount of potassium hydroxide required for the titration into mg.

<Measurement of number average molecular weight (Mn) and weight average molecular weight (Mw)>
In the present invention, the number average molecular weight and the weight average molecular weight are gel permeation chromatograph Alliance e2695 (hereinafter, GPC, standard substance: polystyrene resin, mobile phase: tetrahydrofuran, column: Shodex KF-806 + KF-803, column manufactured by Japan Waters Co., Ltd.) Temperature: 40 ° C., flow rate: 1.0 ml / min, detector: value measured by a photodiode array detector (wavelength 254 nm = ultraviolet light).

<Measurement of melting point>
The melting point in the present invention is measured by using a differential scanning calorimeter (hereinafter, DSC, manufactured by TA Instruments Japan, Q-2000) at a rate of 10 ° C./min. This is a value measured from the top temperature of the melting peak at the time of melting at elevated temperature.

<Evaluation of pot life>
The pot life refers to the stability of the solution immediately after the compounding or after a certain period of time after the compounding, in which a crosslinking agent or a curing agent is mixed with the acid-modified polyolefin. If the pot life property is good, it means that the solution has a small increase in viscosity and can be stored for a long period of time. If the pot life property is poor, the viscosity of the solution increases (thickness), and if it is severe, This indicates that gelation occurs, making it difficult to apply the composition to a base material and making it impossible to store for a long period of time.
The pot life of the adhesive composition was evaluated by measuring the solution viscosity at 25 ° C. using a B-type viscometer after storing it in a static state at 25 ° C. for 24 hours.
Table 2 shows the evaluation results.
(Evaluation criteria)
☆ (especially excellent in practical use): less than 300 mPa · s ◎ (excellent in practical use): 300 mPa · s or more and less than 500 mPa · s ○ (practicable): 500 mPa · s or more and less than 1000 mPa · s × (impractical): 1000 mPa · s Viscosity cannot be measured due to gelation or longer

The laminate obtained as described above was evaluated by the following method.
<Evaluation of initial adhesion>
The laminate was cut into a size of 100 mm × 15 mm, and the adhesion was evaluated by a T-peel test according to the following criteria.
The T-peel test was based on the test method of ASTM-D1876-61, and the peel strength at a tensile speed of 50 mm / min was measured under an environment of 25 ° C. using Tensilon RTM-100 manufactured by Orientec Corporation. The peel strength (N / cm) between the metal substrate and the polyolefin resin substrate was an average of five test values.
(Evaluation criteria)
☆ (excellent in practical use): 8.0 N / cm or more ◎ (excellent in practical use): 7.5 N / cm or more and less than 8.0 N / cm ○ (practicable): 7.0 N / cm or more and 7.5 N / cm Less than × (impractical): less than 7.0 N / cm

<Evaluation of resistance to electrolyte at 85 ° C>
The electrolyte resistance was evaluated in order to examine the applicability of lithium ion batteries as packaging materials. The laminate was cut into a size of 100 mm × 15 mm, and the electrolyte solution was prepared by adding 13 g of lithium hexafluorophosphate to 100 g of ethylene carbonate / diethyl carbonate / dimethyl carbonate = 1/1/1 (volume ratio). It was immersed at 85 degreeC for 1 day. Thereafter, the laminate is taken out, washed with ion-exchanged water, wiped off with a paper wiper, dried sufficiently, cut into a size of 100 mm x 15 mm, and evaluated for electrolyte resistance by a T-type peel test according to the following criteria. did.
☆ (excellent in practical use): 8.0 N / cm or more ◎ (excellent in practical use): 7.5 N / cm to less than 8.0 N / cm ○ (practical): 7.0 N / cm to 7.5 N / cm Less than × (impractical): less than 7.0 N / cm

Measurement of Storage Elastic Modulus The storage elastic modulus (E ' ) in the present invention was measured according to the test method of JIS K7244-4 (1999). Specifically, it is a value measured using a dynamic viscoelasticity measuring apparatus DVA-200 manufactured by IT Measurement Control Co., Ltd. at a frequency of 10 Hz while increasing the temperature from -50 ° C at a rate of 5 ° C / min. . The storage elastic modulus was measured in a 230 ° C. environment. The test piece was prepared such that the adhesive composition obtained in Examples 1 to 15 and Comparative Examples 1 to 4 was dried on a Teflon (registered trademark) sheet using an applicator so that the adhesive layer had a thickness of 40 µm. And applied. The coated surface was dried in a 100 ° C. atmosphere for 5 minutes using a warm air dryer, and then cured at 40 ° C. and 50% RH for 5 days to obtain a test piece.
☆ (very excellent in practical use): 1.0 × 10 ⁶ Pa or more ◎ (particularly excellent in practical use): 1.0 × 10 ⁵ Pa or more and less than 1.0 × 10 ⁶ Pa ○ (excellent in practical use): 5.0 × 10 ⁴ Pa or more and less than 1.0 × 10 ⁵ Pa △ (practicable): 1.0 × 10 ⁴ Pa or more and less than 5.0 × 10 ⁴ Pa × (impractical): less than 1.0 × 10 ⁴ Pa

  Since the adhesive composition according to the present invention contains an acid-modified polyolefin, polyphenylene ether and an isocyanate curing agent, it can exhibit good adhesion and chemical resistance between a polyolefin resin substrate and a metal substrate, and After curing, it has excellent heat resistance. Therefore, a laminate of a polyolefin resin substrate and a metal substrate formed from the adhesive composition of the present invention is a household appliance outer panel, a material for furniture, a member for building interior, or a personal computer, a mobile phone, or a video camera. In addition, it can be widely used as a packaging material (pouch type) for lithium ion batteries that require higher heat resistance than in automotive applications.

Claims (8)

An adhesive composition containing an acid-modified polyolefin (A), a polyphenylene ether (B) and an isocyanate curing agent (C). The adhesive composition according to claim 1, wherein the number average molecular weight of the polyphenylene ether (B) is 20,000 or less. The adhesive composition according to claim 1, wherein a terminal of a main chain of the polyphenylene ether (B) is functionalized. The adhesive composition according to any one of claims 1 to 3, wherein the polyphenylene ether (B) is contained in an amount of 0.1 to 20 parts by mass with respect to 100 parts by mass of the acid-modified polyolefin (A). The adhesive composition according to any one of claims 1 to 4, wherein the acid value of the acid-modified polyolefin (A) is 1 to 40 mgKOH / g. The adhesive composition according to claim 1, which is used for bonding a polyolefin resin substrate and a metal substrate. A laminate of a polyolefin resin substrate and a metal substrate bonded by the adhesive composition according to claim 1. A packaging material for a lithium ion battery, comprising the laminate according to claim 7 as a constituent member.