JP7227760B2 - Resin current collector for positive electrode - Google Patents

Description

TECHNICAL FIELD The present invention relates to a positive electrode resin current collector.

In recent years, it is strongly desired to reduce carbon dioxide emissions for environmental protection. In the automotive industry, expectations are high for the introduction of electric vehicles (EV) and hybrid electric vehicles (HEV) to reduce carbon dioxide emissions. It is done. Lithium-ion batteries, which can achieve high energy density and high output density, have attracted attention as secondary batteries.

Conventionally, metal foil (metal current collector foil) has been used as the current collector in lithium-ion batteries. An electric body has been proposed. Such a resin current collector is lighter than a metal current collector foil, and is expected to improve the output per unit weight of the battery.

Patent Literature 1 discloses a dispersing agent for a resin current collector, a material for a resin current collector containing a resin and a conductive filler, and a resin current collector having the material for a resin current collector.

WO2015/005116

However, in conventional resin current collectors, the dispersibility of the conductive filler is insufficient, and the electrical resistance and the like of the resin current collectors cannot be said to be sufficient. Moreover, there is a problem that the mechanical strength of the resin current collector is impaired when the amount of the dispersant added is increased in order to improve the dispersibility of the conductive filler.

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

The present inventors arrived at the present invention as a result of intensive studies to solve these problems. That is, the present invention is the following invention.
A positive electrode resin current collector formed by molding a resin composition, wherein the resin composition contains a resin, a conductive filler, and a dispersant, the conductive filler is dispersed in the resin, and the dispersant has a carbon number A polyolefin (A) having 0.5 to 10 terminal double bonds per 1,000 and/or an acid-modified product thereof, wherein the polyolefin (A) has a weight average molecular weight of 8,000 to 60,000. and the dispersant has a melting point of 120 to 145°C.

The positive electrode resin current collector of the present invention has sufficient mechanical strength and electrical properties.

The present invention will be described in detail below.
The present invention relates to a positive electrode resin current collector obtained by molding a resin composition, wherein the resin composition contains a resin, a conductive filler and a dispersant, the conductive filler is dispersed in the resin, and the dispersant is a polyolefin (A) having 0.5 to 10 terminal double bonds per 1,000 carbon atoms and/or an acid-modified product thereof, and the polyolefin (A) has a weight average molecular weight of 8,000 to 60,000, and the dispersant has a melting point of 120 to 145°C.

Resins constituting the positive electrode resin current collector of the present invention include polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), polycycloolefin (PCO), polyethylene terephthalate (PET), polyethernitrile (PEN). ), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), polyacrylonitrile (PAN), polymethyl acrylate (PMA), polymethyl methacrylate (PMMA), polyvinylidene fluoride (PVdF), epoxy resin, silicone resin or A mixture of these and the like are included.
From the viewpoint of electrical stability, polyethylene (PE), polypropylene (PP), polymethylpentene (PMP) and polycycloolefin (PCO) are preferred, and polyethylene (PE), polypropylene (PP) and polymethylpentene are more preferred. (PMP).

The conductive filler contained in the positive electrode resin current collector of the present invention is selected from materials having conductivity. It is preferable to use a material that does not have any properties.
Here, the ion is an ion as a charge transfer medium used in a battery equipped with the positive electrode resin current collector of the present invention. For example, lithium ion for a lithium ion battery and sodium ion for a sodium ion battery. .

Specifically, metal {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, and the like, but are not limited to these.
These conductive fillers may be used singly or in combination of two or more. Alloys or metal oxides of these may also be used. From the viewpoint of electrical stability, nickel, aluminum, stainless steel, carbon, silver, copper, titanium and mixtures thereof are preferred, and carbon, nickel and stainless steel are more preferred. These conductive fillers may also be those obtained by coating a conductive material (a metal among the conductive fillers described above) around a particulate ceramic material or a resin material by plating or the like.

The positive electrode resin current collector of the present invention contains a dispersant, and the dispersant is a polyolefin (A) having 0.5 to 10 terminal double bonds per 1,000 carbon atoms and/or an acid-modified polyolefin (A). and the polyolefin (A) has a weight average molecular weight of 8,000 to 60,000.

The polyolefin (A) of the present invention has 0.5 to 10 double bonds per 1,000 carbon atoms.
(A) includes (co)polymers of one or more olefins having a predetermined number of double bonds, and one or more olefins and other than olefins. Copolymers with one or more monomers and having a specified number of double bonds are included.
The olefins 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.). etc.). Examples of the monomers other than the olefins include unsaturated monomers (vinyl acetate, etc.) having 4 to 30 carbon atoms and having reactivity with olefins, excluding olefins.

Specific examples of (A) include:
(co)polymers containing ethylene units (without propylene units) having a defined number of double bonds, e.g. high, medium and low density polyethylenes having a defined number of double bonds; Copolymerization of ethylene with unsaturated monomers having 4 to 30 carbon atoms [butene (1-butene, etc.), α-olefins having 5 to 30 carbon atoms (1-hexene, 1-dodecene, etc.), vinyl acetate, etc.] merging having a defined number of double bonds;
Propylene unit-containing (ethylene unit-free) (co)polymers having a predetermined number of double bonds, such as polypropylene, propylene and unsaturated monomers having 4 to 30 carbon atoms (same as above) copolymer; ethylene / propylene copolymer,
(Co)polymers of olefins having 4 or more carbon atoms and having a certain number of double bonds, such as polybutene.
Among these, polyethylene, polypropylene, ethylene/propylene copolymers, and propylene/unsaturated monomer copolymers having 4 to 30 carbon atoms are preferred from the viewpoint of mixing efficiency with other resins, and more preferred. are ethylene/propylene copolymers.

(A) has 0.5 to 10 double bonds per 1,000 carbon atoms. From the viewpoint of compatibility with other resins, the number of double bonds in (A) is preferably 0.7 to 8 per 1,000 carbon atoms.
The number of double bonds of (A) can be determined from the spectrum of (A) by 1H-NMR (nuclear magnetic resonance) spectroscopy. That is, the peaks in the spectrum obtained in the measurement are assigned, and from the integral value derived from the double bond at 4.5 to 6.0 ppm of (A) and the integral value derived from (A), the two of (A) The number of double bonds and the number of carbon atoms in (A) are determined relative to each other, and the number of double bonds in the molecular terminal and/or in the polymer chain per 1,000 carbon atoms in (A) is calculated. The number of double bonds in (A) in the examples described later follows the method.

The weight average molecular weight of (A) [hereinafter abbreviated as Mw. The measurement is based on the gel permeation chromatography (GPC) method described later. Same below] is 8,000 to 60,000. If the Mw of (A) is less than 8,000, the mechanical strength of the resulting resin current collector will be insufficient, and if it exceeds 60,000, the dispersion performance of the conductive filler will deteriorate. From the viewpoint of the mechanical strength of the resin current collector of the present invention, it is preferably 10,000 to 40,000.

The measurement conditions of Mw by GPC in the present invention are as follows.
Apparatus: high temperature gel permeation chromatograph ["Alliance
GPC V2000", manufactured by Waters Co., Ltd.]
Solvent: Ortho-dichlorobenzene Reference material: Polystyrene sample Concentration: 3 mg/ml
Column stationary phase: PLgel 10 μm, MIXED-B 2 in series
[Manufactured by Polymer Laboratories Co., Ltd.]
Column temperature: 135°C

The above (A) includes polymerization methods (for example, those described in JP-A-59-206409) and degradation methods [thermal, chemical and mechanical degradation methods, etc., among which thermal degradation methods ( In the following, it may be referred to as a thermal degradation method), for example, those described in Japanese Patent Publication No. 43-9368, Japanese Patent Publication No. 44-29742, and Japanese Patent Publication No. 6-70094].

The degradation method involves subjecting polyolefin (A0) of high molecular weight [preferably number average molecular weight (Mn) of 30,000 to 400,000, more preferably 50,000 to 200,000] to thermal, chemical or mechanical includes a method of degrading to

Among the degradation methods, the thermal degradation method includes: (1) in the absence of an organic peroxide (dicumyl peroxide, di-t-butyl peroxide, etc.) in the presence of the polyolefin (A0) under nitrogen gas flow; (2) continuous or non-continuous thermal degradation at 300-450°C for 0.5-10 hours; Alternatively, a method of discontinuously thermally degrading is included.
Among these (1) and (2), the method (1) is preferable because it is easy to obtain a polymer having a larger number of double bonds at the molecular terminal and/or in the polymer chain.

In order to make the number of double bonds per 1,000 carbon atoms of (A) within the range of 0.5 to 10, the heating temperature and heating time may be adjusted in the method of (1). . The higher the heating temperature and the longer the heating time, the more the number of double bonds per 1,000 carbon atoms of (A) tends to increase.

The dispersant contained in the positive electrode resin current collector of the present invention is the polyolefin (A) and/or its acid-modified product. The acid-modified polyolefin (A) is obtained by acid-modifying the (A) with an unsaturated (poly)carboxylic acid (anhydride) (B). Specifically, it refers to the one in which the (B) is added to the double bond of the (A). In the present invention, unsaturated (poly)carboxylic acid (anhydride) means unsaturated monocarboxylic acid, unsaturated polycarboxylic acid and/or unsaturated polycarboxylic acid anhydride.
The unsaturated monocarboxylic acids include aliphatic (3 to 24 carbon atoms, such as acrylic acid, methacrylic acid, α-ethylacrylic acid, crotonic acid, isocrotonic acid), alicyclic (6 to 24 carbon atoms, such as cyclohexenecarboxylic acid), acid) and the like. Examples of unsaturated polycarboxylic acids (anhydrides) include unsaturated dicarboxylic acids (anhydrides) [aliphatic dicarboxylic acids (anhydrides) (having 4 to 24 carbon atoms, such as maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, acids and their anhydrides), alicyclic-containing dicarboxylic acids (anhydrides) (having 8 to 24 carbon atoms, such as cyclohexenedicarboxylic acid, cycloheptenedicarboxylic acid, bicycloheptenedicarboxylic acid, methyltetrahydrophthalic acid and these anhydride), etc.] and the like. The unsaturated (poly)carboxylic acid (anhydride) may be used alone or in combination of two or more.
Of these, from the viewpoint of reactivity with (A), unsaturated dicarboxylic acids (anhydrides) are preferred, unsaturated dicarboxylic acid anhydrides are more preferred, and maleic anhydride is particularly preferred.

The dispersant contained in the positive electrode resin current collector of the present invention comprises the polyolefin (A), the unsaturated (poly)carboxylic acid (anhydride) (B), and an aliphatic unsaturated compound having 6 to 36 carbon atoms. It may be one obtained by reacting saturated hydrocarbon (C).
The aliphatic unsaturated hydrocarbons having 6 to 36 carbon atoms are linear α-olefins or branched α-olefins having 6 to 36 carbon atoms. Linear α-olefins include 1-hexene, 1-octene, 1-nonene, 1-decene, and mixtures of two or more thereof. Examples of α-olefins having branched chains include propylene trimer, propylene tetramer and mixtures of two or more thereof.

When the dispersant contained in the positive electrode resin current collector of the present invention is an acid-modified polyolefin (A), from the viewpoint of dispersibility of the conductive filler, the polyolefin (A) and the unsaturated (poly ) The weight ratio [(A)/(B)] to carboxylic acid (anhydride) (B) is preferably 98/2 to 75/25.

When the dispersant contained in the positive electrode resin current collector of the present invention is an acid-modified polyolefin (A), the dispersant combines (A) and (B) with a dical generating source [radical initiator ( d), heat, light, etc.]. The reaction here refers to the addition reaction of (B) to the above (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 (mixture of A and B) before and after the reaction. The number of double bonds can be obtained from the spectrum of 1H-NMR (nuclear magnetic resonance) spectroscopy as described above. The presence or absence of reaction during the production of dispersants 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) (benzoyl peroxide oxide, di-t-butyl peroxide, lauroyl peroxide, dicumyl peroxide, etc.) and polyfunctional (having two or more peroxide groups in the molecule) [2,2-bis(4,4-di-t -butylperoxycyclohexyl)propane, di-t-butylperoxyhexahydroterephthalate, diallylperoxydicarbonate, etc.]].
Among these, from the viewpoint of reactivity between (A) and (B), preferred radical initiators are peroxides, more preferred are monofunctional peroxides, and particularly preferred is di-t-butyl peroxide. , lauroyl peroxide, and dicumyl peroxide.

The amount of (d) used is preferably 0.05 to 10%, more preferably 0.2 to 5%, based on the total weight of (A) and (B), from the viewpoint of reactivity and suppression of side reactions. , 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) are combined in a suitable organic solvent [carbon number 2-18, 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 if necessary, the above (d) [or a solution obtained by dissolving (d) in a suitable organic solvent (same as above)], a chain transfer agent (t) described later, A method of adding a polymerization inhibitor (f) and heating and stirring (solution method);
[2] A method of premixing (A) and (B) and optionally (d), (t) and (f) and melt-kneading them using an extruder, Banbury mixer, kneader or the like (melting method).

The reaction temperature in the solution method may be a temperature at which (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.

The reaction temperature in the melting method may be any temperature at which (A) is melted, and from the viewpoint of reactivity and the decomposition temperature of the reaction product, it is preferably 120 to 260°C, more preferably 130 to 240°C. is.

Examples of the chain transfer agent (t) include alcohols (having 1 to 24 carbon atoms, such as methanol, ethanol, 1-propanol, 2-butanol, allyl alcohol); thiols (having 1 to 24 carbon atoms, such as ethylthiol, propio thiol, 1- or 2-butylthiol, 1-octylthiol); aldehydes (2 to 18 carbon atoms, such as 2-methyl-2-propylaldehyde, 1- or 2-butyraldehyde, 1-pentylaldehyde); phenol ( 6-36 carbon atoms, such as phenol, o-, m- or p-cresol); amines (3-24 carbon atoms, such as diethylmethylamine, triethylamine, diphenylamine); disulfides (42-24 carbon atoms, such as diethyldisulfide, di-1-propyl disulfide).
From the viewpoint of reactivity, the amount of (t) used is preferably 30% or less, more preferably 0.1 to 20%, based on the total weight of (A) and (B).

Examples of the polymerization inhibitor (f) include catechol (having 6 to 36 carbon atoms, such as 2-methyl-2-propylcatechol), quinone (having 6 to 24 carbon atoms, such as p-benzoquinone), hydrazine (having 2 to 36 carbon atoms, . 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), and more preferably 0.01 to 0.5% from the viewpoint of reactivity.

The melting point of the dispersant contained in the positive electrode resin current collector of the present invention is 120 to 145°C. If the melting point of the dispersant is less than 120° C. or more than 145° C., the dispersibility of the conductive filler deteriorates because the difference in viscosity from the base resin (matrix resin) during molding of the current collector becomes too large. From the viewpoint of dispersibility of the conductive filler, the melting point of the dispersant is preferably 135 to 145°C, more preferably 140 to 145°C.
In the present invention, the melting point means the melting peak temperature measured by DSC (differential scanning calorimetry) according to JIS K7122 (transition heat measurement method). Examples of the DSC include DSC2910 [trade name, manufactured by T.A. Instruments Co., Ltd.]. Melting points in Examples described later were measured using the method and apparatus.

The positive electrode resin current collector of the present invention preferably 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 0.1 to 10% by weight based on the weight of the resin current collector, the mechanical strength of the resin current collector is improved.

The positive electrode resin current collector of the present invention can be preferably produced by the following method.
First, a resin current collector material is obtained by mixing a base resin (matrix resin), a conductive carbon filler, a dispersant, and, if necessary, other components.
As a mixing method, after obtaining a masterbatch of the conductive carbon filler, it is further mixed with the matrix resin, or a masterbatch of the matrix resin, the conductive carbon filler, the dispersant and, if necessary, other components is used. and a method of mixing all the raw materials at once. For the mixing, pellet-like or powder-like ingredients are mixed with an appropriate known mixer such as a kneader, an internal mixer, a Banbury mixer and a roll. can be used.

There are no particular restrictions on the order in which the components are added during mixing. The obtained mixture may be further pelletized or pulverized by a pelletizer or the like.

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

EXAMPLES Next, the present invention will be specifically described with reference to Examples, but the present invention is not limited to Examples unless it departs from the gist of the present invention. Unless otherwise specified, parts means parts by weight and % means % by weight.
In the following, Examples 1, 3, 6 and 7 refer to Reference Examples 1-4.

<Production Example 1: Production of polyolefin (A-1)>
In a reaction vessel, 100 parts of polyolefin (A0-1) using a metallocene catalyst having propylene and ethylene as structural units (trade name "Wintech WFX6", manufactured by Japan Polypropylene Corporation) was charged, and the vapor phase was filled with industrial grade While passing nitrogen (purity 99.999%), the mixture was melted by heating with a mantle heater, and thermally degraded at 360° C. for 30 minutes with stirring to obtain polyolefin (A-1). The number of double bonds at the molecular terminal per 1,000 carbon atoms of (A-1) was 0.6, and Mw was 50,000.

<Production Example 2: Production of polyolefin (A-2)>
In a reaction vessel, 100 parts of polyolefin (A0-2) [trade name “SunAllomer PZA-20A”, manufactured by SunAllomer Co., Ltd.] using a Ziegranatta catalyst having propylene and ethylene as structural units is charged, and the gas phase is filled with industrial grade While passing nitrogen (purity 99.999%), the mixture was heated and melted with a mantle heater, and thermally degraded at 360° C. for 30 minutes with stirring to obtain polyolefin (A-2). The number of double bonds at the molecular terminal of (A-2) per 1,000 carbon atoms was 0.7, and Mw was 40,000.

<Production Example 3: Production of polyolefin (A-3)>
In a reaction vessel, 100 parts of polyolefin (A0-2) [trade name “SunAllomer PZA-20A”, manufactured by SunAllomer Co., Ltd.] using a Ziegranatta catalyst having propylene and ethylene as structural units is charged, and the gas phase is filled with industrial grade While passing nitrogen (purity 99.999%), the mixture was heated and melted with a mantle heater, and thermally degraded at 360° C. for 40 minutes with stirring to obtain polyolefin (A-3). The number of double bonds at the molecular terminal per 1,000 carbon atoms of (A-3) was 1.9, and Mw was 15,000.

<Production Example 4: Production of polyolefin (A-4)>
In a reaction vessel, 100 parts of polyolefin (A0-2) [trade name “SunAllomer PZA-20A”, manufactured by SunAllomer Co., Ltd.] using a Ziegranatta catalyst having propylene and ethylene as structural units is charged, and the gas phase is filled with industrial grade While passing nitrogen (purity 99.999%), the mixture was heated and melted with a mantle heater, and thermally degraded at 360° C. for 50 minutes with stirring to obtain polyolefin (A-4). The number of double bonds at the molecular terminal per 1,000 carbon atoms of (A-4) was 7.2, and the Mw was 8,000.

<Production Example 5: Production of polyolefin (A-5)>
In a reaction vessel, 100 parts of polyolefin (A0-1) using a metallocene catalyst having propylene and ethylene as structural units (trade name "Wintech WFX6", manufactured by Japan Polypropylene Corporation) was charged, and the vapor phase was filled with industrial grade While passing nitrogen (purity 99.999%), the mixture was heated and melted with a mantle heater, and thermally degraded at 360° C. for 40 minutes with stirring to obtain polyolefin (A-5). The number of double bonds at the molecular terminal per 1,000 carbon atoms of (A-5) was 1.5, and Mw was 23,000.

<Comparative Production Example 1: Production of Polyolefin (RA-1)>
100 parts of polyolefin (RA0-1) [trade name: Versify 3000, manufactured by Dow Chemical Co., Ltd.] using a metallocene catalyst having propylene and ethylene as structural units is charged into a reaction vessel, and industrial nitrogen is added to the gas phase portion. (Purity 99.999%) was heated and melted with a mantle heater while being aerated, and thermal degradation was performed at 360° C. for 20 minutes while stirring to obtain polyolefin (RA-1). The number of double bonds at the molecular terminal per 1,000 carbon atoms of (RA-1) was 0.4, and Mw was 64,000.

<Comparative Production Example 2: Production of polyolefin (RA-2)>
In a reaction vessel, 100 parts of polyolefin (A0-2) [trade name “SunAllomer PZA-20A”, manufactured by SunAllomer Co., Ltd.] using a Ziegranatta catalyst having propylene and ethylene as structural units is charged, and the gas phase is filled with industrial grade While passing nitrogen (purity 99.999%), the mixture was heated and melted with a mantle heater, and thermally degraded at 360° C. for 50 minutes with stirring to obtain polyolefin (RA-2). (RA-2) had 5 double bonds at the end of the molecule per 1,000 carbon atoms and an Mw of 5,600.

<Production Example 6: Production of dispersant (1)>
100 parts of (A-1) and 3 parts of maleic anhydride were placed in a reaction vessel, heated to 200° C. under a stream of industrial nitrogen (99.999% purity), and stirred for 10 hours. Thereafter, unreacted maleic anhydride was distilled off under reduced pressure (1.5 kPa, the same applies hereinafter) to obtain a dispersant (1). Dispersant (1) had a melting point of 123° C. and an Mw of 52,000.

<Production Example 7: Production of dispersant (2)>
Dispersant (2) was obtained in the same manner as in Production Example 6, except that (A-1) in Production Example 1 was changed to (A-3) and the equivalent amount of maleic anhydride was changed from 3 parts to 10 parts. . Dispersant (2) had a melting point of 135° C. and an Mw of 28,000.

<Production Example 8: Production of dispersant (3)>
100 parts of (A-4), 25 parts of maleic anhydride, 18.5 parts of 1-decene and 100 parts of xylene are charged in a reaction vessel, and after purging with nitrogen, the mixture is heated to 130° C. under nitrogen gas flow to dissolve uniformly. let me A solution prepared by dissolving 0.5 parts of dicumyl peroxide [trade name “Percumyl D”, manufactured by NOF Corporation] in 10 parts of xylene was added dropwise thereto over 10 minutes, and then stirring was continued for 3 hours while refluxing xylene. rice field. After that, xylene and unreacted maleic anhydride were distilled off under reduced pressure (1.5 kPa, hereinafter the same) to obtain a dispersant (3). Dispersant (3) had a melting point of 135° C. and an Mw of 25,000.

<Production Example 9: Production of dispersant (4)>
Dispersant (4) was obtained in the same manner as in Production Example 6 except that (A-1) in Production Example 6 was changed to (A-2) and the equivalent amount of maleic anhydride was changed from 3 parts to 5 parts. . Dispersant (4) had a melting point of 142° C. and an Mw of 45,000.

<Dispersant (5)>
(A-2) produced in Production Example 2 was directly used as dispersant (5). Dispersant (5) had a melting point of 141° C. and an Mw of 40,000.

<Production Example 10: Production of Dispersant (6)>
The same operation as in Production Example 8 was performed except that the equivalent of maleic anhydride in Production Example 8 was changed from 25 parts to 35 parts, and the equivalent of dicumyl peroxide was changed from 0.5 parts to 24 parts. got Dispersant (6) had a melting point of 135° C. and an Mw of 32,000.

<Production Example 11: Production of dispersant (7)>
Dispersant (7) was obtained in the same manner as in Production Example 6, except that (A-1) in Production Example 6 was changed to (A-5). Dispersant (7) had a melting point of 123° C. and an Mw of 25,000.

<Comparative Production Example 3: Production of Dispersant (8)>
Dispersant (8) was obtained in the same manner as in Production Example 6 except that (A-1) in Production Example 6 was replaced with (RA-1) and the equivalent of maleic anhydride was changed from 3 parts to 2 parts. . Dispersant (8) had a melting point of 124° C. and an Mw of 68,000.

<Comparative Production Example 4: Production of Dispersant (9)>
The same operation as in Production Example 6 was performed except that (A-1) in Production Example 6 was changed to (RA-2) and the equivalent of maleic anhydride was changed from 3 parts to 11 parts, dispersing agent (9) was added. Obtained. Dispersant (9) had a melting point of 130° C. and an Mw of 20,000.

<Dispersant (10)>
A low-melting-point type polypropylene [trade name “Elmodu S400”, manufactured by Idemitsu Kosan Co., Ltd.] was used as it was as a dispersant (10). Dispersant (10) had a melting point of 80° C. and an Mw of 45,000.

<Example 1>
Using a twin-screw extruder, 85 parts of polypropylene [trade name “SunAllomer PL500A”, manufactured by SunAllomer Co., Ltd.], 10 parts of acetylene black [trade name “Denka Black”, manufactured by Denka Co., Ltd.], dispersant (1) 5 The parts were melt-kneaded under conditions of 180° C., 100 rpm, and a residence time of 5 minutes to obtain a positive 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 thickness of 100 μm.

<Examples 2 to 7 and Comparative Examples 1 to 3>
Positive electrode resin current collector materials (Z-2) to (Z-7) and (RZ-1) to (RZ-3) were prepared in the same manner as in Example 1, except that the compositions were changed to those shown in Table 2. Resin current collectors (W-2) to (W-7) and (RW-1) to (RW-3) having a film thickness of 100 μm were obtained by rolling with a hot press.

In Table 2, the following resins and conductive fillers were used.
Resin: polypropylene [trade name “SunAllomer PL500A”, manufactured by SunAllomer Co., Ltd.]
Conductive filler: acetylene black [trade name “Denka Black” manufactured by Denka Co., Ltd.]

[Evaluation of electronic conductivity]
For the resin current collectors (W-1) to (W-7) and (RW-1) to (RW-3) obtained in Examples 1 to 7 and Comparative Examples 1 to 3, Surface resistivity and penetration resistance were measured. The surface resistivity is an index of contact resistance when stacking single cells, and the penetration resistance is an index of electrical resistance in the bulk (thickness direction) of the battery material. The results are listed in Table 2.

The surface resistivity was measured according to JIS K 7194 (resistivity test method by four-probe method for conductive plastics).
The penetration resistance was measured as follows.
Cut the resin current collector into strips of about 3 cm × 10 cm, and use an electrical resistance measuring instrument [IMC-0240 type, Imoto Seisakusho Co., Ltd.] and a resistor [RM3548, manufactured by HIOKI] to measure the resistance of each resin current collector. values were measured.
The resistance value of the resin current collector is measured with a load of 2.16 kg applied to the electrical resistance measuring instrument, and the resistance value of the resin current collector is measured 60 seconds after the load of 2.16 kg is applied. and As shown in the following formula, the penetration resistance value was obtained by multiplying the contact surface area (3.14 cm ² ) of the jig at the time of resistance measurement.
Penetration resistance value (Ω·cm ² ) = Resistance value (Ω) x 3.14 (cm ² )

[Evaluation of tensile strength]
The tensile strength of the resin current collectors (W-1) to (W-7) and (RW-1) to (RW-3) obtained in Examples 1 to 7 and Comparative Examples 1 to 3 was measured according to JIS K 7161. (Plastics - Test method for tensile properties). The results are listed in Table 2.

The resin current collector of the present invention is particularly useful as a current collector for lithium ion batteries used in mobile phones, personal computers, hybrid vehicles, and electric vehicles.

Claims (3)

A positive electrode resin current collector 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,
The dispersant is a polyolefin (A) having 0.7 to 1.9 terminal double bonds per 1,000 carbon atoms and/or an acid-modified product thereof,
The polyolefin (A) has a weight average molecular weight of 15,000 to 40,000,
The dispersant has a melting point of 135 to 142° C.,
The weight ratio of the dispersant in the resin current collector is 0.1 to 10 weights based on the weight of the resin current collector.
% of the positive electrode resin current collector. 2. The positive electrode resin current collector according to claim 1, wherein the resin is one or more selected from the group consisting of polypropylene, polyethylene and polyethylene terephthalate. 1, wherein the conductive filler is selected from the group consisting of carbon, nickel and stainless steel;
The positive electrode resin current collector according to claim 1 or 2, which is at least one species.