JP2020102386A - Resin current collector for negative electrode - Google Patents

Abstract

To provide a resin current collector for a negative electrode having sufficient mechanical strength and electrical characteristics.SOLUTION: Disclosed in a resin current collector for a negative electrode formed by molding a resin composition. The resin composition contains a resin, a conductive filler and a dispersant. The conductive filler is dispersed in the resin. An acid value of the dispersant is 55 or more. A weight ratio of the dispersant is 0.1 to 10 wt.% based on weight of the resin current collector. The dispersant is a reaction product of polyolefin (A) having 0.1 to 35 double bonds per 1,000 carbon atoms and unsaturated (poly)carboxylic acid (anhydride) (B) or a reaction product of (A), (B) and aliphatic unsaturated hydrocarbon (C) having 6 to 36 carbon atoms.SELECTED DRAWING: None

Description

The present invention relates to a negative electrode resin current collector.

In recent years, reduction of carbon dioxide emissions has been eagerly desired for environmental protection. In the automobile industry, expectations are growing for the reduction of carbon dioxide emissions by the introduction of electric vehicles (EVs) and hybrid electric vehicles (HEVs), and the development of motor drive secondary batteries, which holds the key to their practical application, is earnestly undertaken. Has been done. As a secondary battery, attention has been focused on a lithium ion battery that can achieve high energy density and high output density.

In a lithium-ion battery, a metal foil (metal current collector foil) has been conventionally used as a current collector, but in recent years, a so-called resin collector made of a resin to which a conductive material has been added instead of the metal foil. Electric bodies have been proposed. Such a resin current collector is lighter in weight than the metal current collector foil, and is expected to improve the output per unit weight of the battery.

Patent Document 1 discloses a resin current collector material containing a resin current collector dispersant, a resin and a conductive filler, and a resin current collector having the resin current collector material.

International Publication No. 2015/005116

However, in the conventional resin current collector, the dispersibility of the conductive filler is insufficient, and the electrical resistance of the resin current collector cannot be said to be sufficient. Further, if the amount of the dispersant added is increased to improve the dispersibility of the conductive filler, the mechanical strength of the resin current collector is impaired.

An object of the present invention is to provide a negative electrode resin current collector having sufficient mechanical strength and electrical characteristics.

The present inventors have arrived at the present invention as a result of extensive studies to solve these problems. That is, the present invention is the following invention.
A negative electrode resin current collector molded resin composition, the resin composition contains a resin, a conductive filler and a dispersant, the conductive filler is dispersed in the resin, the acid value of the dispersant 55 or more, the weight ratio of the dispersant is 0.1 to 10% by weight based on the weight of the resin current collector, and the dispersant contains 0.1 to 35 carbon atoms per 1,000 carbon atoms. A reaction product of a polyolefin (A) having a double bond and an unsaturated (poly)carboxylic acid (anhydride) (B), or the above (A), (B) and an aliphatic non-aliphatic having 6 to 36 carbon atoms. A resin current collector for a negative electrode which is a reaction product with a saturated hydrocarbon (C).

The resin collector for negative electrode of the present invention has sufficient mechanical strength and electrical characteristics

Hereinafter, the present invention will be described in detail.
The present invention is a resin current collector for a negative electrode formed by molding a resin composition, wherein the resin composition contains a resin, a conductive filler and a dispersant, and the conductive filler is dispersed in the resin. Has an acid value of 55 or more, the weight ratio of the dispersant is 0.1 to 10% by weight based on the weight of the resin current collector, and the dispersant is 0.1 per 1,000 carbon atoms. A reaction product of a polyolefin (A) having 35 double bonds and an unsaturated (poly)carboxylic acid (anhydride) (B), or (A), (B) and 6 to 36 carbon atoms. It is a negative electrode resin current collector which is a reaction product with a certain aliphatic unsaturated hydrocarbon (C).

Examples of the resin constituting the negative electrode current collector of the present invention include polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), polycycloolefin (PCO), polyethylene terephthalate (PET), polyether nitrile (PEN). ), polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), polyacrylonitrile (PAN), polymethyl acrylate (PMA), polymethyl methacrylate (PMMA), polyvinylidene fluoride (PVdF), epoxy resin, silicone resin or These mixtures etc. are mentioned.
From the viewpoint of electrical stability, polyethylene (PE), polypropylene (PP), polymethylpentene (PMP) and polycycloolefin (PCO) are preferable, and polyethylene (PE), polypropylene (PP) and polymethylpentene are more preferable. (PMP).

The conductive filler contained in the negative electrode resin current collector of the present invention is selected from materials having conductivity, but from the viewpoint of suppressing ion permeation in the current collector, conductive with respect to ions used as a charge transfer medium. It is preferable to use a material having no property.
Here, the ion is an ion as a charge transfer medium used in a battery including the negative electrode resin current collector of the present invention, for example, a lithium ion battery indicates a lithium ion, and a sodium ion battery indicates a sodium ion. ..

Specifically, metals {nickel, aluminum, stainless steel (SUS), silver, copper, titanium, etc.}, carbon {graphite and carbon black [acetylene black, ketjen black, furnace black, channel black, thermal lamp black, etc.], etc. }, and mixtures thereof, but are not limited thereto.
These conductive fillers may be used alone or in combination of two or more. Moreover, these alloys or metal oxides may be used. From the viewpoint of electrical stability, nickel, aluminum, stainless steel, carbon, silver, copper, titanium and a mixture thereof are preferable, and carbon, nickel or stainless steel is more preferable. Further, these conductive fillers may be obtained by coating a particle-based ceramic material or a resin material with a conductive material (of the above-mentioned conductive fillers, a metal) by plating or the like.

The resin collector for a negative electrode of the present invention contains a dispersant, and the dispersant is a polyolefin (A) having 0.1 to 35 double bonds per 1,000 carbon atoms and an unsaturated (poly)carboxylic acid. It is a reaction product of an acid (anhydride) (B) or a reaction product of the (A), the (B) and an aliphatic unsaturated hydrocarbon (C) having 6 to 36 carbon atoms.

The polyolefin (A) has 0.1 to 35 double bonds per 1,000 carbon atoms.
The (A) is one or more (co)polymers of olefins having a predetermined number of double bonds, and one or more olefins and other than olefins. A copolymer with a monomer having a predetermined number of double bonds is included.
Examples of the olefin include alkenes having 2 to 30 carbon atoms (ethylene, propylene, 1- or 2-butene, isobutene, etc.), and α-olefins having 5 to 30 carbon atoms (1-hexene, 1-decene, 1-dodecene). Etc.) can be mentioned. Examples of the monomer other than the olefin include unsaturated monomers (vinyl acetate and the like) having reactivity with the olefin and having 4 to 30 carbon atoms and excluding the olefin.

As a specific example of the above (A),
Ethylene unit-containing (non-propylene unit) (co)polymer having a predetermined number of double bonds, for example, high, medium and low density polyethylene having a predetermined number of double bonds, Copolymerization of ethylene with an unsaturated monomer having 4 to 30 carbon atoms [butene (1-butene, etc.), α-olefin having 5 to 30 carbon atoms (1-hexene, 1-dodecene, etc.), vinyl acetate, etc.] Union having a predetermined number of double bonds,
A propylene unit-containing (ethylene unit-free) (co)polymer having a predetermined number of double bonds, such as polypropylene, propylene and an unsaturated monomer having 4 to 30 carbon atoms (the same as above). A copolymer of ethylene/propylene copolymer,
And a (co)polymer of an olefin having 4 or more carbon atoms and having a predetermined number of double bonds, for example, polybutene.
Of these, from the viewpoint of reactivity with the unsaturated (poly)carboxylic acid (anhydride) (B) described below or with (B) and the aliphatic unsaturated hydrocarbon (C), polyethylene, polypropylene, and An ethylene/propylene copolymer and a propylene/unsaturated monomer copolymer having 4 to 30 carbon atoms are preferable, and an ethylene/propylene copolymer is more preferable.

The (A) has 0.1 to 35 double bonds per 1,000 carbon atoms. From the viewpoint of reactivity with (B) or (B) and (C), the number of double bonds contained in (A) is preferably 0.3 to 20 per 1,000 carbon atoms, and 0 0.5 to 15 pieces are more preferable.
The number of double bonds contained in (A) can be determined from the spectrum of 1H-NMR (nuclear magnetic resonance) spectroscopy of (A). That is, the peak in the spectrum obtained by the above-mentioned measurement is assigned, and from the integrated value derived from the double bond at 4.5 to 6.0 ppm of (A) and the integrated value derived from (A), The relative value between the number of heavy bonds and the carbon number of (A) is determined, and the number of double bonds in the molecular end and/or polymer chain per 1,000 carbons of (A) is calculated. The number of double bonds in the above-mentioned (A) in Examples described later was according to the method.

The number average molecular weight of the above (A) before reacting with the above (B) and/or (C) [hereinafter, abbreviated as Mn. The measurement is based on the gel permeation chromatography (GPC) method described later. The same applies hereinafter] is preferably 800 to 50,000, and more preferably 1,000 to 45,000 from the viewpoint of the mechanical strength of the resin current collector of the present invention.

The measurement conditions of Mn by GPC in the present invention are as follows.
Equipment: High temperature gel permeation chromatograph ["Alliance
GPC V2000", manufactured by Waters Co., Ltd.]
Solvent: Orthodichlorobenzene standard substance: Polystyrene sample concentration: 3 mg/ml
Column stationary phase: PLgel 10 μm, MIXED-B 2 in series
[Polymer Laboratories Co., Ltd.]
Column temperature: 135℃

The (A) is a polymerization method (for example, one described in JP-A-59-206409) and a degradation method [thermal, chemical and mechanical degradation methods such as thermal degradation method ( Hereinafter, it may be referred to as a thermal degradation method), for example, those described in JP-B-43-9368, JP-B-44-29742, and JP-B-6-70094].

Among these production methods (A), a method having a larger number of double bonds in the molecular end and/or the polymer chain is easily obtained, and (A) and (B) or (A) and (B) From the viewpoint of easy reaction with (C), the degradation method is preferred, and the thermal degradation method is more preferred.

For the degradation method, a polyolefin (A0) having a high molecular weight [preferably a number average molecular weight (Mn) of 30,000 to 400,000, more preferably 50,000 to 200,000] is thermally, chemically or mechanically used. The method of degrading is included.

Among the degradation methods, in the thermal degradation method, the polyolefin (A0) is aerated with nitrogen, and (1) in the absence of organic peroxide (dicumyl peroxide, di-t-butyl peroxide, etc.), A method of thermally degrading continuously or discontinuously at 300 to 450° C. for 0.5 to 10 hours, and (2) in the presence of an organic peroxide, continuously at 180 to 300° C. for 0.5 to 10 hours. Alternatively, a method such as discontinuous thermal degradation is included.
From the viewpoint of the reactivity of (A) obtained among these (1) and (2) with (B), or (B) and (C), a molecular terminal and/or a polymer chain is preferable. It is the method (1) in which it is easy to obtain one having a larger number of double bonds.

In order to bring the number of double bonds per 1,000 carbon atoms contained in (A) into the range of 0.1 to 35, the heating temperature and the heating time in the method of (1) may be adjusted. .. The higher the heating temperature and the longer the heating time, the more the number of double bonds per 1,000 carbon atoms in (A) tends to increase.

The unsaturated (poly)carboxylic acid (anhydride) (B) is a C3-30 (poly)carboxylic acid (anhydride) having one polymerizable unsaturated group. In the present invention, the unsaturated (poly)carboxylic acid (anhydride) means an unsaturated monocarboxylic acid, an unsaturated polycarboxylic acid and/or an unsaturated polycarboxylic acid anhydride.
Among the above-mentioned (B), as the unsaturated monocarboxylic acid, aliphatic (having 3 to 24 carbon atoms, for example, acrylic acid, methacrylic acid, α-ethylacrylic acid, crotonic acid, isocrotonic acid), containing an alicyclic ring (having a carbon number of 6 to 24, such as cyclohexenecarboxylic acid). As the unsaturated polycarboxylic acid (anhydride), unsaturated dicarboxylic acid (anhydride) [aliphatic dicarboxylic acid (anhydride) (having 4 to 24 carbon atoms, for example, maleic acid, fumaric acid, itaconic acid, citraconic acid, mesacon) Acids and their anhydrides), alicyclic-containing dicarboxylic acids (anhydrides) (having 8 to 24 carbon atoms, such as cyclohexene dicarboxylic acid, cycloheptene dicarboxylic acid, bicycloheptene dicarboxylic acid, methyl tetrahydrophthalic acid and these Etc.] and the like. The above (B) may be used alone or in combination of two or more.
Of these, unsaturated dicarboxylic acids (anhydrides) are preferable, and unsaturated dicarboxylic acid anhydrides are more preferable, from the viewpoint of reactivity with an aliphatic unsaturated hydrocarbon (C) having 6 to 36 carbon atoms described below. Maleic anhydride is particularly preferred.

The aliphatic unsaturated hydrocarbon (C) having 6 to 36 carbon atoms of the present invention is a linear α-olefin having 6 to 36 carbon atoms or an α-olefin having a branched chain.
Examples of the linear α-olefin include 1-hexene, 1-octene, 1-nonene, 1-decene, and a mixture of two or more of these. Examples of the α-olefin having a branched chain include propylene trimer, propylene tetramer, and a mixture of two or more kinds of them.

When the dispersant contained in the negative electrode resin current collector of the present invention is a reaction product of (A) and (B), from the viewpoint of dispersibility of the conductive filler, (A) and (B) The weight ratio [(A)/(B)] is preferably 80/20 to 95/5.
Further, when the dispersant contained in the negative electrode resin current collector of the present invention is a reaction product of the above (A), (B) and (C), from the same point of view, (A) and (B) The weight ratio [(A)/(B+C)] with (C) is preferably 30/70 to 80/20, and the weight ratio [(B)/(C)] with (B) and (C) is 10/. 90 to 70/30 is preferable.

The dispersant contained in the negative electrode current collector of the present invention is a radical generation source [radical initiator (d), or (A) and (B) or (A), (B) and (C). , Heat, light, etc.]. The reaction here refers to an addition reaction of (B) or (C) to the above-mentioned (A) having a double bond. The presence or absence of the reaction is judged by the decrease in the number of double bonds in the mixture before and after the reaction (mixture of A and B or mixture of A, B and C). The number of double bonds can be determined from the spectrum of 1H-NMR (nuclear magnetic resonance) spectroscopy as described above. The presence/absence of a reaction in producing a dispersant in Examples described later was also confirmed according to the same method.

Examples of the radical initiator (d) include azo compounds [azobisisobutyronitrile, azobisisovaleronitrile, etc.], peroxides [monofunctional (having one peroxide group in the molecule) (benzoylperoxide). Oxides, di-t-butyl peroxide, lauroyl peroxide, dicumyl peroxide, etc.) and polyfunctional compounds (having two or more peroxide groups in the molecule) [2,2-bis(4,4-di-t -Butylperoxycyclohexyl)propane, di-t-butylperoxyhexahydroterephthalate, diallylperoxydicarbonate and the like]] and the like.
Among these, from the viewpoint of the reactivity of (A) and (B) or (A), (B) and (C), the radical initiator is preferably a peroxide, and more preferably a monofunctional peroxide. Especially preferred are di-t-butyl peroxide, lauroyl peroxide and dicumyl peroxide.

The amount of (d) used is based on the total weight of (A) and (B) or the total weight of (A), (B) and (C) from the viewpoint of reactivity and suppression of side reactions. It is preferably 0.05 to 10%, more preferably 0.2 to 5%, and particularly preferably 0.5 to 3%.

Specific methods for producing the dispersant of the present invention include the following methods [1] and [2].
[1] The above (A) and (B) or (A), (B) and (C) are combined with a suitable organic solvent [C2-18, such as hydrocarbons (hexane, heptane, octane, dodecane, benzene). , Toluene, xylene, etc.), halogenated hydrocarbons (di-, tri-, or tetrachloroethane, dichlorobutane, etc.), ketones (acetone, methyl ethyl ketone, di-t-butyl ketone, etc.), ethers (ethyl-n-propyl ether, Di-n-butyl ether, di-t-butyl ether, dioxane, etc.)], and optionally (d) [or (d) is dissolved in a suitable organic solvent (the same as above). A solution], a method of adding a chain transfer agent (t) and a polymerization inhibitor (f) described below, and stirring with heating (solution method);
[2] The above (A) and (B), or (A) and (B) and (C), and optionally (d), (t), and (f) are mixed in advance, and an extruder, a Banbury mixer, A method of melt-kneading using a kneader or the like (melting method).

The reaction temperature in the solution method may be a temperature at which the above (A) is dissolved in an organic solvent, and from the viewpoint of reactivity, it is preferably 50 to 220°C, more preferably 110 to 210°C, and particularly preferably 120 to 120°C. 180°C.

Further, the reaction temperature in the melting method may be a temperature at which the above (A) melts, and from the viewpoint of reactivity and decomposition temperature of the reaction product, preferably 120 to 260°C, more preferably 130 to 240°C. Is.

Examples of the chain transfer agent (t) include alcohol (having 1 to 24 carbon atoms, such as methanol, ethanol, 1-propanol, 2-butanol, and allyl alcohol); thiol (having 1 to 24 carbon atoms, such as ethylthiol and propio). Thiol, 1- or 2-butylthiol, 1-octylthiol); aldehyde (C2-18, for example, 2-methyl-2-propylaldehyde, 1- or 2-butyraldehyde, 1-pentylaldehyde); phenol ( C6-C36 such as phenol, o-, m- or p-cresol); amine (C3-24 such as diethylmethylamine, triethylamine, diphenylamine); disulfide (C42-24 such as diethyl disulfide, Di-1-propyl disulfide).
The amount of (t) used is preferably 30% or less based on the total weight of (A) and (B), or the total weight of (A), (B) and (C), and in terms of reactivity. Therefore, it is more preferably 0.1 to 20%.

Examples of the polymerization inhibitor (f) include catechol (having 6 to 36 carbon atoms, for example, 2-methyl-2-propylcatechol), quinone (having 6 to 24 carbon atoms, for example, p-benzoquinone), and hydrazine (having 2 to 36 carbon atoms). , For example, 1,3,5-triphenylhydrazine), nitro compounds (having 3 to 24 carbon atoms, for example, nitrobenzene), stabilizing radicals [having 5 to 36 carbon atoms, for example, 1,1-diphenyl-2-picrylhydrazyl ( DPPH), 2,2,6,6-tetramethyl-1-piperidinyl oxide (TEMPO)].
The amount of (f) used is preferably 5% or less based on the total weight of (A) and (B) or the total weight of (A), (B) and (C), and from the viewpoint of reactivity. , And more preferably 0.01 to 0.5%.

The acid value of the dispersant of the present invention is 55 or more. When the acid value of the dispersant is less than 55, the dispersibility of the conductive filler in the resin deteriorates.
The acid value of the dispersant is a value obtained by measurement according to the following procedures (i) to (iii) according to JIS K0070.
(I) 1 g of (X) is dissolved in 100 g of xylene whose temperature is adjusted to 100°C.
(Ii) Using phenolphthalein as an indicator, titration is performed with a 0.1 mol/L potassium hydroxide ethanol solution [trade name "0.1 mol/L ethanolic potassium hydroxide solution", manufactured by Wako Pure Chemical Industries, Ltd.].
(Iii) The acid value (unit: mgKOH/g) is calculated by converting the amount of potassium hydroxide required for titration into mg.
In the above measurement, one acid anhydride group is equivalent to one carboxyl group. The acid value in the examples described below was according to the method.

As a method of adjusting the acid value of the dispersant to the above range, the acid value can be adjusted by controlling the weight ratio of (B) in the dispersant.

The negative electrode resin current collector of the present invention contains the dispersant in an amount of 0.1 to 10% by weight based on the weight of the resin current collector. When the content of the dispersant is less than 0.1% by weight based on the weight of the resin current collector, the dispersibility of the conductive filler is deteriorated, and when it exceeds 10% by weight, mechanical properties of the resin current collector are increased. Strength deteriorates.

The negative electrode resin current collector of the present invention can be preferably produced by the following method.
First, a resin (matrix resin) serving as a base material, a conductive carbon filler, a dispersant, and, if necessary, other components are mixed to obtain a resin current collector material.
As a mixing method, after obtaining a masterbatch of conductive carbon filler, a method of further mixing with a matrix resin, a matrix resin, a conductive carbon filler, a dispersant and, if necessary, a masterbatch of other components is used. There is a method, and a method of mixing all the raw materials at once, and for the mixing, a suitable known mixer such as a kneader, an internal mixer, a Banbury mixer and a roll is used for mixing components in pellet form or powder form. Can be used.

There is no particular limitation on the order of addition of the components during mixing. The obtained mixture may be further pelletized or powdered by a pelletizer or the like.

The resin current collector of the present invention is obtained by molding the obtained resin current collector material into, for example, a film shape. Examples of the method of forming into a film include known film forming methods such as T-die method, inflation method and calender method. The resin current collector of the present invention can be obtained by a molding method other than film molding.

Next, the present invention will be specifically described by way of examples, but the present invention is not limited to the examples without departing from the gist of the present invention. In addition, unless otherwise indicated, a part means a weight part and% means weight%.

<Production Example 1: Production of polyolefin (A-1)>
100 parts of polyolefin (A0-1) [trade name "Versify 3000", manufactured by Dow Chemical Co., Ltd.] using a metallocene catalyst having propylene and ethylene as constitutional units was charged into a reaction vessel, and industrial nitrogen was added to a gas phase portion. (Purity of 99.999%) was aerated by heating and melting with a mantle heater while aeration, and thermal degradation was carried out at 360° C. for 100 minutes while stirring to obtain a polyolefin (A-1). The number of double bonds at the molecular end per 1000 carbons of (A-1) was 18, and Mw was 1500.

<Production Example 2: Production of polyolefin (A-2)>
The reaction vessel was charged with 100 parts of the (A0-1) [trade name "Versify 3000", manufactured by Dow Chemical Co., Ltd.], and the gas phase portion was aerated with industrial nitrogen (purity 99.999%) while mantle. It was heated and melted with a heater, and heat-degraded at 360° C. for 120 minutes while stirring to obtain a polyolefin (A-2). The number of double bonds at the molecular end per 1000 carbons of (A-2) was 35, and Mw was 800.

<Production Example 3: Production of polyolefin (A-3)>
100 parts of a polyolefin (A0-2) using a Ziegler-Natta catalyst containing propylene and ethylene as a constituent unit [trade name "SAN ALOMAR PZA-20A", manufactured by SAN ALOMAR Co., Ltd.] was charged into a reaction vessel, and the gas phase portion was industrially used. While passing nitrogen (purity 99.999%), it was heated and melted with a mantle heater, and heat-degraded at 360° C. for 120 minutes while stirring to obtain a polyolefin (A-3). The number of double bonds at the molecular end per 1000 carbons of (A-3) was 7.2 and Mw was 3900.

<Production Example 4: Production of polyolefin (A-4)>
A reactor was charged with 100 parts of a polymer (A0-3) [trade name "Tufmer XM-5080", manufactured by Mitsui Chemicals, Inc.] having 80 mol of propylene and 20 mol% of 1-butene as a constitutional unit, and a gas phase While passing industrial nitrogen (purity 99.999%) through the portion, it was heated and melted by a mantle heater, and heat-degraded at 360° C. for 50 minutes while stirring to obtain a polyolefin (A-4). The number of double bonds at the molecular end per 1000 carbons of (A-4) was 4, and Mw was 7,000.

<Production Example 5: Production of polyolefin (A-5)>
Into a reaction vessel, 100 parts of the above (A0-2) [trade name "Sun Allomer PZA-20A", manufactured by Sun Allomer Co., Ltd.] was charged, and while injecting industrial nitrogen (purity 99.999%) into the gas phase portion, It was heated and melted with a mantle heater, and heat-degraded at 360° C. for 50 minutes while stirring to obtain a polyolefin (A-5). The number of double bonds at the molecular end per 1000 carbons of (A-5) was 5, and Mw was 5,600.

<Production Example 6: Production of Dispersant (1)>
A reactor was charged with 100 parts of (A-1) and 10.5 parts of maleic anhydride, heated to 200° C. under aeration with industrial nitrogen (purity 99.999%), and stirred for 10 hours. Then, unreacted maleic anhydride was distilled off under reduced pressure (1.5 kPa, the same applies hereinafter) to obtain a dispersant (1). The dispersant (1) had an acid value of 55 and Mw of 8000.

<Production Example 7: Production of dispersant (2)>
Dispersant (2) was obtained by performing the same operation as in Production Example 6 except that (A-1) in Production Example 6 was changed to (A-2) and the equivalent weight of maleic anhydride was changed from 10.5 to 23 parts. It was The dispersant (2) had an acid value of 105 and Mw of 5,500.

<Production Example 8: Production of dispersant (3)>
(A-3) 100 parts, maleic anhydride 32.7 parts, 1-decene 23.6 parts and xylene 100 parts were charged into a reaction vessel, and after nitrogen substitution, the temperature was raised to 130° C. under nitrogen aeration to be uniform. Dissolved in. A solution prepared by dissolving 0.5 parts of dicumyl peroxide [trade name "Parkmill D", manufactured by NOF CORPORATION) in 10 parts of xylene was added dropwise over 10 minutes, and then stirring was continued under reflux of xylene for 3 hours. It was Then, xylene and unreacted maleic anhydride were distilled off under reduced pressure (1.5 kPa, the same applies below) to obtain a dispersant (3). The dispersant (3) had an acid value of 120 and Mw of 15,000.

<Production Example 9: Production of dispersant (4)>
(A-3) of Production Example 8 was changed to (A-1), maleic anhydride was changed from 32.7 parts to 116.8 parts, and 13.6-decene 23.6 parts was changed to 1-hexene 50.5 parts. Except for this, the same operation as in Production Example 8 was performed to obtain a dispersant (4). The dispersant (4) had an acid value of 250 and Mw of 8000.

<Production Example 9: Production of dispersant (5)>
The same operation as in Production Example 8 was repeated except that 32.7 parts of maleic anhydride in Production Example 8 was changed to 33 parts and 23.6 parts of 1-decene was changed to 200 parts of 1-hexatriacontene, and the dispersant (5) was used. Got The dispersant (5) had an acid value of 57 and Mw of 15,000.

<Production Example 10: Production of dispersant (6)>
Except that (A-3) in Production Example 8 was changed to (A-1), 32.7 parts of maleic anhydride was changed to 18.2 parts, and 23.6 parts of 1-decene was changed to 11.6 parts of 1-hexene. Was subjected to the same operation as in Production Example 8 to obtain a dispersant (6). The dispersant (6) had an acid value of 80 and Mw of 8,000.

<Production Example 11: Production of dispersant (7)>
Same as Production Example 8 except that (A-3) in Production Example 8 was changed to (A-4), 32.7 parts of maleic anhydride was changed to 30 parts, and 23.6 parts of 1-decene was changed to 17 parts of styrene. The operation was performed to obtain a dispersant (7). The dispersant (7) had an acid value of 120 and Mw of 20,000.

<Production Example 12: Production of dispersant (8)>
The same operations as in Production Example 8 were performed except that (A-3) in Production Example 8 was not added to (A-5), 32.7 parts of maleic anhydride was added to 11 parts, and 23.6 parts of 1-decene was not added. Then, a dispersant (8) was obtained. The dispersant (8) had an acid value of 52 and Mw of 20,000.

<Example 1>
Using a twin-screw extruder, 180 parts of polypropylene [trade name "San Allomer PL500A", manufactured by Sun Allomer Co., Ltd.] 27 parts, nickel particles [Type 255, manufactured by Vale Japan Co., Ltd.] 71 parts, and 2 parts of dispersant (1) were used. The mixture was melt-kneaded under the conditions of a temperature of 100 rpm and a residence time of 5 minutes to obtain a negative electrode resin current collector material (Z-1). The obtained (Z-1) was rolled by a hot press to obtain a resin current collector (W-1) having a film thickness of 100 μm.

<Examples 2-11 and Comparative Examples 1-2>
Negative electrode resin current collector materials (Z-2) to (Z-11) and (RZ-1) (RZ-2) were obtained in the same manner as in Example 1 except that the compositions shown in Table 2 were changed. Then, by rolling with a hot press machine, resin current collectors (W-2) to (W-11) and (RW-1) and (RW-2) having a film thickness of 100 μm were obtained.

In Table 2, the following were used as the resin and the conductive filler.
Resin: Polypropylene [Product name "Sun Allomer PL500A", manufactured by Sun Allomer Co., Ltd.]
Conductive filler 1: Nickel particles [Type 255, manufactured by Vale Japan Co., Ltd.]
Conductive filler 2: SUS361L particles [PF-3F, manufactured by Epson Atomix Co., Ltd.]

[Electron conductivity evaluation]
The electrical resistance values of the resin current collectors (W-1) to (W-11) and (RW-1) and (RW-2) obtained in Examples 1 to 11 and Comparative Examples 1 and 2 were measured according to JIS K. 7194 (resistivity test method by four-point probe method of conductive plastic). The results are shown in Table 2.

[Tensile strength evaluation]
The tensile strengths of the resin current collectors (W-1) to (W-11) and (RW-1) and (RW-2) obtained in Examples 1 to 11 and Comparative Examples 1 and 2 were measured according to JIS K 7161. The measurement was performed according to (Plastic-Test method for tensile properties). The results are shown in Table 2.

The resin current collector of the present invention is particularly useful as a current collector for a lithium ion battery used for a mobile phone, a personal computer, a hybrid vehicle, and an electric vehicle.

Claims (3)

A resin current collector for a negative electrode formed by molding a resin composition,
The resin composition contains a resin, a conductive filler and a dispersant, the conductive filler is dispersed in the resin,
The acid value of the dispersant is 55 or more,
The weight ratio of the dispersant is 0.1 to 10% by weight based on the weight of the resin current collector,
The dispersant is a reaction product of a polyolefin (A) having a double bond of 0.1 to 35 per 1,000 carbon atoms and an unsaturated (poly)carboxylic acid (anhydride) (B), or A negative electrode resin current collector which is a reaction product of (A), the above (B), and an aliphatic unsaturated hydrocarbon (C) having 6 to 36 carbon atoms. The negative electrode resin current collector according to claim 1 or 2, wherein the resin is one or more selected from the group consisting of polypropylene, polyethylene, and polyethylene terephthalate. The negative electrode resin current collector according to claim 1, wherein the conductive filler is at least one selected from the group consisting of carbon, nickel, and stainless steel.