Patent ID: 12187930

BEST MODE

Hereinafter, the present application will be specifically described by way of examples, but the scope of the present application is not limited by the following examples.

1. Measurement Method of Curing Rate

The curing rate was evaluated through a gel fraction. After cross-linkable compositions prepared in Examples or Comparative Examples were each coated to an appropriate thickness, it was maintained at a temperature of about 120° C. for 3 minutes or so. Subsequently, it was again maintained at a temperature of 50° C. for 3 days to form a cross-linked layer, and then the relevant cross-linked layer was maintained in a constant temperature and humidity room (a temperature of 23° C., 50% relative humidity) for 7 days. Thereafter, about 0.2 g (=A in the gel fraction determination equation) was collected from the cross-linked layer. The collected cross-linked product was completely immersed in 50 mL of ethyl acetate and then stored in a dark room at room temperature for 1 day. Subsequently, a portion that was not dissolved in ethyl acetate (insoluble content) was collected in a #200 stainless steel wire net, which was dried at 150° C. for 30 minutes to measure the mass (dry mass of insoluble contents=B in the gel fraction measurement equation). Subsequently, the gel fraction (unit: %) was determined by substituting the measurement result into the following equation.
Gel fraction=B/A×100  <Gel fraction determination equation>A: mass (0.2 g) of the pressure-sensitive adhesiveB: dry mass of insoluble contents (unit: g)
2. Surface Resistance Measurement Method

The surface resistance was confirmed by a probe method using a surface resistance meter from Mitsubishi. Also, the high temperature surface resistance was evaluated in the above manner after the cross-linked layer was maintained at a temperature of 80° C. for about 120 hours. Then, the moist-heat resistant surface resistance was evaluated in the above manner after the cross-linked layer was maintained at a temperature of 60° C. and 90% relative humidity for about 240 hours.

3. NMR Measurement Method

NMR was confirmed by Li NMR using a Bruker 500 MHz NMR instrument.

Preparation Example 1. Preparation of Pressure-Sensitive Adhesive Polymer (A)

To an 1 L reactor in which a nitrogen gas was refluxed and a cooling apparatus was installed for easy temperature control, n-butyl acrylate (n-BA) and acrylic acid (AA) were introduced in a weight ratio of 95:5 (n-BA: AA), and 100 parts by weight of ethyl acetate (EAc) was introduced thereto as a solvent. Subsequently, after the nitrogen gas was purged for 1 hour in order to remove oxygen, 0.03 parts by weight of azobisisobutyronitrile (AIBN) diluted in ethyl acetate to a concentration of 50 wt % was introduced thereto as a reaction initiator and reacted for 8 hours to prepare a copolymer (A) having a molecular weight (Mw) of about 1,800,000 or so.

Example 1

An epoxy cross-linking agent (T-743L, Soken Co., Japan) was combined with the copolymer (A) of Preparation Example 1 in a ratio of about 0.037 parts by weight relative to 100 parts by weight of the solid content of the copolymer (A), LiTFSI (lithium bis(trifluoromethanesulfonylimide) as an ionic compound was combined in a ratio of about 0.74 parts by weight relative to 100 parts by weight of the solid content of the copolymer (A), and then acetylacetone was again combined in a ratio of about 0.03 parts by weight relative to 100 parts by weight of the solid content of the copolymer (A) to prepare a cross-linkable composition.

Example 2

A cross-linkable composition was prepared in the same manner as in Example 1, except that the contents of the ionic compound and acetylacetone were changed to about 3.7 parts by weight and 0.03 parts by weight, respectively, relative to 100 parts by weight of the solid content of the copolymer (A).

Example 3

A cross-linkable composition was prepared in the same manner as in Example 1, except that the contents of the ionic compound and acetylacetone were changed to about 3.7 parts by weight and 0.15 parts by weight, respectively, relative to 100 parts by weight of the solid content of the copolymer (A).

Comparative Example 1

A cross-linkable composition was prepared in the same manner as in Example 1, except that the ionic compound and acetylacetone were not applied.

Comparative Example 2

A cross-linkable composition was prepared in the same manner as in Example 1, except that acetylacetone was not combined.

Comparative Example 3

A cross-linkable composition was prepared in the same manner as in Example 2, except that acetylacetone was not combined.

The composition of each of the cross-linkable compositions is summarized in Table 1 below.

TABLE 1Epoxy cross-IonicCopolymerlinking agentcompoundAcAcExample 11000.0370.740.03Example 21000.0373.70.03Example 31000.0373.70.15Comparative Example 11000.03700Comparative Example 21000.0370.740Comparative Example 31000.0373.70Unit: part by weightCopolymer: copolymer (A) prepared in Preparation Example 1Epoxy cross-linking agent: T-743L, Soken Co., JapanIonic compound: LiTFSI(lithium bis(trifluoromethanesulfonyl imide))AcAc: acetylacetone

The curing rate and surface resistance value measured for each cross-linkable composition are summarized in Table 2 below.

TABLE 2CuringRoom temperatureHigh temperatureMoisture-heatratesurface resistancesurface resistancesurface resistance(%)(Ω/sq)(Ω/sq)(Ω/sq)Example 185.32.64 × 10115.13 × 10111.47 × 1011Example 245.51.08 × 10102.98 × 10107.55 × 109Example 3809.99 × 1092.38 × 10107.15 × 109Comparative Example 181.5Over RangeOver Range1.17 × 1012Comparative Example 278.93.14 × 10116.32 × 10111.63 × 1011Comparative Example 301.17 × 10102.57 × 10101.08 × 1010Over Range: more than measurement performance of measuring equipment
Review of Results

As a result of measuring the curing rate of each of the cross-linkable compositions of Examples 1 to 3 and Comparative Examples 1 to 3 in the above-mentioned manner, Examples 1 to 3 were 85.3%, 45.5% and 80%, respectively, and Comparative Examples 1 to 3 were 81.5%, 78.9% and 0%, respectively.

Among the results, Comparative Example 1 exhibits a high curing rate in the state that the ionic compound is not included, whereas it can be seen that when comparing with the results of Comparative Examples 2 and 3, as the addition amount of the ionic compound is increased, the curing rate is decreased. Accordingly, it can be confirmed that the ionic compound causes a decrease in the cross-linking efficiency and in particular, when a considerable amount of the ionic compound is combined as in Comparative Example 3, the cross-linking is rarely achieved.

However, it can be confirmed that when the acetylacetone corresponding to the compound of Formula 1 is combined in the same composition as those of Comparative Examples 2 and 3 above (Examples 1 to 3), the curing rate is greatly increased.

These results can also be verified by NMR measurement, which will be described with reference to the FIGURE as follows.

In the FIGURE, the lowermost NMR result is the result measured after LiTFSI, which is an ionic compound used in Examples and Comparative Examples, is solely dissolved in a solvent of ethyl acetate, and the uppermost NMR is the result measured by combining the same epoxy cross-linking agent as applied in Examples and Comparative Examples.

Comparing the two results, it can be seen that if the epoxy cross-linking agent is added to LiTFSI, the peak shifts to a down field. In the FIGURE, the second NMR from the top is the case where acetylacetone is added to a solution containing LiTFSI and the epoxy cross-linking agent so that the volume ratio thereof to the epoxy cross-linking agent is 1:0.25 (epoxy cross-linking agent: acetylacetone), and the third NMR is the result measured after being added so that the volume ratio is about 1:0.5 (epoxy cross-linking agent: acetylacetone). Through the drawing, it can be confirmed that as acetylacetone is added, the peak again shifts to an upfield. Accordingly, it can be confirmed that the phenomenon of interfering with the cross-linking reaction is solved through interaction of LiTFSI with acetylacetone.