Resin composition

Abstract

The present application relates to a composition, a battery module and a battery pack. According to one example of the present application, the related manufacturing process can be improved and a battery module having excellent insulation can be provided.

Claims

1. A resin composition having an initial viscosity change ratio defined by the following relational expression 1 in a range of 1.1 to 5.0, and having an initial viscosity change ratio defined by the following relational expression 2 of 10 or more, wherein in the following relational expressions 1 and 2, V.sub.1 is in a range of 100,000 to 500,000 cP, V.sub.2 is 2,000,000 cP or less, and V.sub.3 is 5,000,000 cP or more:
Initial viscosity change ratio=V.sub.2/V.sub.1  [Relational Expression 1]
Initial viscosity change ratio=V.sub.3/V.sub.1  [Relational Expression 2] wherein, V.sub.1 is an initial viscosity, which is a viscosity value as measured at room temperature within 60 seconds after mixing main agent and curing agent of the resin composition, V.sub.2 is a viscosity value measured after leaving the resin composition, in which V.sub.1 has been measured, at room temperature for 5 minutes and V.sub.3 is a viscosity value measured after leaving the resin composition, in which V.sub.1 has been measured, at room temperature for 60 minutes, and when V.sub.1 and V.sub.3 are measured in a shear rate range of 0.01 to 10.0/s using a rheological property measuring device (ARES), they are viscosity values measured at a point of 2.5/s, wherein the resin composition is a urethane-based resin composition comprising, a main composition part comprising an ester-based polyol resin; a curing agent composition part comprising a polyisocyanate; and a filler, and the ester-based polyol resin is an amorphous polyol, in which a crystallization temperature (Tc) and a melting temperature (Tm) are not observed in a DSC (differential scanning calorimetry) analysis, or has a melting temperature (Tm) of less than 15° C.

2. The resin composition according to claim 1, wherein a dielectric breakdown voltage of a cured product measured 24 hours after mixing the main agent and the curing agent is 10 kV/mm or more.

3. The resin composition according to claim 1, wherein a mixture of the ester-based polyol resin and polyisocyanate has a glass transition temperature (Tg) of less than 0° C. after curing.

4. The resin composition according to claim 1, wherein each of the ester-based polyol resin and the polyisocyanate has a viscosity of less than 10,000 cP.

5. The resin composition according to claim 1, wherein the ester-based polyol resin is represented by the following formula 1 or 2: ##STR00002## wherein, X is a carboxylic acid-derived unit, Y is a polyol-derived unit, n is a number within a range of 2 to 10, and m is a number within a range of 1 to 10.

6. The resin composition according to claim 5, wherein the carboxylic acid-derived unit X is one or more units selected from the group consisting of a phthalic acid unit, an isophthalic acid unit, a terephthalic acid unit, a trimellitic acid unit, a tetrahydrophthalic acid unit, a hexahydrophthalic acid unit, a tetrachlorophthalic acid unit, an oxalic acid unit, an adipic acid unit, an azelaic acid unit, a sebacic acid unit, a succinic acid unit, a malic acid unit, a glutaric acid unit, a malonic acid unit, a pimelic acid unit, a suberic acid unit, a 2,2-dimethylsuccinic acid unit, a 3,3-dimethylglutaric acid unit, a 2,2-dimethylglutaric acid unit, a maleic acid unit, a fumaric acid unit, an itaconic acid unit and a fatty acid unit.

7. The resin composition according to claim 5, wherein the polyol-derived unit Y is any one or two or more units selected from the group consisting of an ethylene glycol unit, a propylene glycol unit, a 1,2-butylene glycol unit, a 2,3-butylene glycol unit, a 1,3-propanediol unit, a 1,3-butanediol unit, a 1,4-butanediol unit, a 1,6-hexanediol unit, a neopentyl glycol unit, a 1,2-ethylhexyldiol unit, a 1,5-pentanediol unit, a 1,9-nonanediol unit, a 1,10-decanediol unit, a 1,3-cyclohexanedimethanol unit, a 1,4-cyclohexanedimethanol unit, a glycerin unit and a trimethylolpropane unit.

8. The resin composition according to claim 1, wherein the polyisocyanate is a non-aromatic polyisocyanate.

9. The resin composition according to claim 8, wherein the non-aromatic polyisocyanate is an alicyclic polyisocyanate, a carbodiimide-modified alicyclic polyisocyanate, or an isocyanurate-modified alicyclic polyisocyanate.

10. The resin composition according to claim 1, wherein the filler comprises alumina, AlN (aluminum nitride), BN (boron nitride), silicon nitride, SiC, or BeO.

11. The resin composition according to claim 1, wherein the filler is contained in an amount of 50 to 2,000 parts by weight relative to 100 parts by weight of the sum of the ester-based polyol resin and polyisocyanate contents.

12. A battery module comprising a module case having a top plate, a bottom plate and sidewalls, wherein an inner space is formed by the top plate, the bottom plate, and the sidewalls; a plurality of battery cells existing in the inner space of the module case; and a resin layer formed by curing the resin composition according to claim 1 and in contact with the plurality of battery cells.

13. A battery pack comprising one or more battery modules according to claim 12.

14. An automobile comprising the battery module according to claim 12.

15. A method of manufacturing a battery module, comprising injecting the resin composition according to claim 1 into a module case; housing a battery cell in the module case, and curing the resin composition to form the resin layer.

16. The method of manufacturing a battery module according to claim 15, wherein the curing of the resin composition is performed by holding the resin composition at room temperature or heating at a temperature in a range of about 30° C. to 50° C. for a predetermined time.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 shows an example of determining an amorphous characteristic or a sufficiently low crystallizability of an ester-based polyol according to one example of the present application.

(2) FIG. 2 shows an exemplary module case, which can be applied in the present application.

(3) FIG. 3 schematically shows a form in which battery cells are housed in a module case.

(4) FIG. 4 schematically shows an exemplary bottom plate where injection holes and observation holes are formed.

(5) FIGS. 5 and 6 schematically show an exemplary battery pouch which can be used as a battery cell.

(6) FIGS. 7 and 8 schematically show the structure of an exemplary battery module.

(7) The reference numerals and symbols related to the drawings are as follows. 10: module case 10a: bottom plate 10b: sidewall 10c: top plate 10d: guiding portion 20: battery cell 30: resin layer 50a: injection hole 50b: observation hole 40: insulating layer 100: pouch type cell 110: electrode assembly 120: exterior material 121: upper pouch 122: lower pouch S: sealing portion

BEST MODE

(8) Hereinafter, the battery module of the present application will be described with reference to examples and comparative examples, but the scope of the present application is not limited by the following range.

(9) Evaluation Methods

(10) 1. Viscosity

(11) A viscosity of a resin composition was measured at room temperature and a shear rate condition of from 0.01/s to 10.0/s using a rheological property measuring machine (ARES). The viscosity mentioned in the examples is a viscosity at a point of a shear rate of 2.5/s, where a TI (thixotropic index) can be determined through a ratio of a viscosity at a point of a shear rate of 0.25/s to a viscosity at a point of a shear rate of 2.5/s.

(12) 2. Insulation Performance

(13) When both the withstand voltage and the breakdown voltage described below satisfy a predetermined value, they are denoted by 0, and when they are not denoted by X,

(14) (1) Withstanding Voltage

(15) It was measured according to ISO 6469-3. Specifically, the composition was injected in a module state, and 2 kV was applied for 1 second after 1 hour, where in the case of the leakage current of less than 1 mA, it was indicated by O and in the case of the leakage current of 1 mA or more, it was indicated by X.

(16) (2) Dielectric Breakdown Voltage

(17) A cured product (really cured) having a thickness of 2 mm was prepared on the basis of ASTM D149, and when the dielectric breakdown voltage was measured, in the case of the value of 10 kV/mm or more, it was indicated by O and in the case of less than 10 kV/mm, it was indicated by X.

(18) 3. Processability

(19) As a module case having the same shape as FIG. 1, a module case having a bottom plate, sidewalls, and a top plate, made of aluminum, was used. The case was used, in which guiding portions for guiding installation of battery cells were formed on the internal surface of the bottom plate in the module case, injection holes for injecting the resin composition were formed at regular intervals in the central part of the top plate and the bottom plate in the module case, and observation holes were formed at the end of the top plate and the bottom plate. A bundle of pouches laminating a plurality of battery pouches was housed in the module case. Subsequently, the top plate was covered on the upper surface of the module case.

(20) (1) The resin composition was injected into the injection holes of each of the top plate and the bottom plate, and it was confirmed that the composition reached the observation hole. When the time taken to reach the observation hole was within 5 minutes, it was indicated by O, and when the time exceeded 5 minutes or the composition did not have enough flowability to reach the observation hole, or when the composition was not evenly filled in the upper part and the lower part in the gravity direction, respectively, in the module due to too high flowability after the injection, it was indicated by X.

(21) (2) After 1 hour from the composition injection (filling), it was observed whether the composition flowed out from the module while moving and vibrating the module. When there was no external contamination due to the flowing composition, it was indicated by O, and when there was contamination, it was indicated by X.

Examples and Comparative Examples

Example 1

(22) Polyol: A resin (having a viscosity of about 280 cP as measured with a Brookfield LV type viscometer) comprising, as the caprolactone-based polyol represented by Formula 2 above, a polyol having a number of repeating units (m in Formula 2) of about 1 to 3 or so and containing 1,4-butanediol as the polyol-derived unit (Y in Formula 2) was used in a predetermined amount in the main composition.

(23) Isocyanate: A mixture (having a viscosity of 170 cP as measured with a Brookfield LV type viscometer) of HDI (hexamethylene diisocyanate) and a HDI trimer was used in the curing agent composition. At this time, the used amount of the isocyanate compound was adjusted so that the NCO index was about 100.

(24) Filler: Alumina was used. The content thereof was adjusted in a ratio of 1,000 parts by weight relative to 100 parts by weight of the sum of the polyol and isocyanate contents, and the alumina was divided and formulated in the same amount into the main composition part and the curing agent composition part.

(25) Dispersant: An anionic dispersant was introduced in a predetermined content.

(26) Catalyst: Dibutyltin dilaurate (DBTDL) was used in the same contents as in Table 1.

(27) The components were mixed to prepare a two-component urethane-based composition.

Example 2

(28) A composition was prepared in the same manner as in Example 1, except that the dispersant content was added at 70% of the dispersant content used in Example 1.

Example 3

(29) The main composition part was constituted to comprise a polydimethylsiloxane (PDMS) having a vinyl group, and the curing agent composition part was constituted to comprise a polydimethylsiloxane having a vinyl group and a polydimethylsiloxane having a hydride group, where each was formulated with a filler so as to have a viscosity of 200,000 to 300,000 or so. The used amount of platinum catalyst was appropriately controlled during the mixing process.

Comparative Example 1

(30) A composition was prepared in the same manner as in Example 1, except that the content of the catalyst was used at 30% relative to the content used in Example 1.

Comparative Example 2

(31) A composition was prepared in the same manner as in Example 1, except that the content of the catalyst was used at a level of 3 times the content used in Example 1.

Comparative Example 3

(32) A composition was prepared in the same manner as in Example 1, except that the repeating unit m in Formula 2 of the main composition was less than 1.

(33) TABLE-US-00001 TABLE 1 Catalyst amount Viscosity (cP) (relative amount) V1 V2 V3 Example 1 Urethane 1 100 200000 550000 5870000 2 Urethane 1 100 490000 1400000  7800000 3 Silicone 100 220000 300000 6660000 Comparative 1 Urethane 1 30 210000 250000 1500000 Example 2 Urethane 1 300 510000 3000000< 8030000 3 Urethane 2 100 90000 270000 5200000 ※ Considering the load of the viscosity measuring instrument, in case of exceeding 5,000,000 some error may occur.

(34) TABLE-US-00002 TABLE 2 Insulation performance Sixty minute Dielectric withstanding breakdown Processability voltage voltage (1) (2) Example 1 ◯ ◯ ◯ ◯ 2 ◯ ◯ ◯ ◯ 3 ◯ ◯ ◯ ◯ Comparative 1 X X ◯ X Example 2 ◯ ◯ X (not mea- surable) 3 ◯ ◯ X (not mea- surable)

(35) From Tables 1 and 2 above, it can be seen that in Examples satisfying the viscosity-related conditions of the present application, excellent processability and insulation performance are realized, but in the case of Comparative Examples that the viscosity conditions are not satisfied, processability is poor. Specifically, it can be seen that when the V3 is too low due to insufficient curing as in Comparative Example 1, contamination of the adjacent components or peeling of the adhesive surface may occur, and when too much curing has been performed at the time of measuring V2 as in Comparative Example 2, the injection processability is poor. Then, in the case where the viscosity related to V1 is too low as in Comparative Example 3, the overflow is severely generated even before the curing progresses after the injection, and the injected composition does not form an evenly cured resin layer, while flowing from the upper part to the lower part in the gravity direction in the module, but is filled only in the lower part of the gravity direction, so that the upper part of the gravity direction can be unfilled.