KR100952416B1 - Acrylic adhesive and polyimide tape for electrolytic condenser using the same - Google Patents

Abstract

The present invention discloses an acrylic adhesive and a polyimide adhesive tape for an electrolytic capacitor using the same. Acrylic pressure-sensitive adhesive is a 2-ethylhexyl acrylate, when (2-Ethylhexylacrylate) and n - butyl acrylate (n -Buthylacrylate) of the main monomer, 50 to 90%, vinyl acetate (Vinyl acetate), and 1-vinyl -2 to aggregation component 10-40% of monomer of pyrrolidinone (1-Vinyl-2-Pyrrolidinone), functional component of acrylic acid, glycidyl methacrylate and hydroxyethyl (Hydroxyethyl methacrylate) The monomer is 2 to 20%, and the polyimide film substrate is provided with an acrylic adhesive having a thickness of 20 to 25 μm, and is a polyimide adhesive tape for an electrolytic capacitor using the acrylic adhesive, comprising: a polyimide film substrate; And an acrylic pressure-sensitive adhesive layer applied to one side of the polyimide film base material. It comprises, and the polyimide film substrate has a thickness of 20 ~ 25㎛.

Acrylic adhesive, polyimide adhesive tape, OPP and PI

Description

Acrylic adhesive and polyimide adhesive tape for electrolytic capacitor using same {ACRYLIC ADHESIVE AND POLYIMIDE TAPE FOR ELECTROLYTIC CONDENSER USING THE SAME}

The present invention relates to a polyamide adhesive tape, and more particularly, to an acrylic pressure-sensitive adhesive and a polyimide adhesive tape for an electrolytic capacitor using the same after the impregnation is greatly improved.

In general, acrylic pressure-sensitive adhesives can be broadly classified into solvent-type acrylic adhesives and solvent-free acrylic adhesives. The monomer composition of the acrylic pressure-sensitive adhesive is generally composed of alkyl acrylate (methacrylate) or methacrylate having 4 to 17 carbon atoms of the alkyl group, the composition ratio of which is 2-ethylhexyl acrylate (2-ethylhexyl acrylate; 2- 50% to 90% of monomers such as EA), 10% to 40% of monomers such as methacrylate, vinyl acetate (VAc) and styrene (ST) as a cohesive component, and acrylic acid (AA) as a functional component , Monomers such as methylmethacrylic acid (MMA) are 2-20%.

Currently, solvent-type acrylic pressure-sensitive adhesives are much used because they have excellent adhesive strength, moisture resistance, water resistance, and heat resistance, compared to solvent-free acrylic pressure-sensitive adhesives.

The pressure-sensitive adhesive is important for balance adjustment technology of three physical properties. However, in order to raise the adhesiveness, the viscosity must be increased, on the contrary, the cohesion force is lowered. Ideally, the adhesiveness and cohesion should be raised simultaneously. For this reason, a crosslinking technique is required. In particular, crosslinking techniques are necessary to minimize the change in physical properties over a wide temperature range.

In a broad sense, intertwined polymers can be said to be a kind of crosslinking. Therefore, a high molecular weight such as natural rubber can take some balance of the physical properties of the pressure-sensitive adhesive even without special chemical crosslinking. Acrylic emulsions also have relatively high molecular weights, so they can be regarded as having natural rubbers as described above. However, solvent-type acrylic pressure sensitive adhesives are difficult to make high molecular weight ones. Needed. That is, most of them require chemical crosslinking when a wide temperature range and heat resistance are required. However, even if the crosslinking is too much, the adhesiveness is lost, so that the crosslinking may be designed in advance, but originally, a method of crosslinking has been taken after fixing the coating or forming a tape.

Addition to the acrylic polymer to change the viscoelastic behavior and interfacial properties (plasticizer, liquid tackifier, solid tackifier, etc.) is called tackifier. The plasticizer causes Tg to move toward the lower temperature and serves to improve the initial adhesive force. Tackifiers are added for the purpose of improving the adhesion of the nonpolar material. In the acrylic system, the elastic modulus increases at room temperature, and the initial adhesive strength is lowered, but the adhesive strength is improved. However, in the high temperature region, the elastic modulus is lowered and the heat resistance is weak.

Tackifiers used in acrylic pressure-sensitive adhesives can be divided into natural products and derivatives thereof (such as rosin, modified rosin, rosin ester, terpene resin, phenol resin, xylene resin). Many softening points (molecular weight difference) have different qualities even in the same kind. As the softening point, an acryl-based pressure-sensitive adhesive having a temperature of about 60 to 150 ° C. is mainly used, and even in the same softening point, the adhesive force and the initial adhesive force are often different. Since the compatibility and performance which appear in the composition and molecular weight of an acryl, the kind and molecular weight of a tackifier differ, it is necessary to select the appropriate thing according to a setting function.

As high-density, high-precision, and high-performance high-performance parts of electric and electronic equipment are being promoted, technologies such as precision micromachining assembly, adoption of new materials, and high-speed automatic production of small quantity parts of various kinds are being developed. It becomes an indispensable element.

In the case of winding type electronic parts such as aluminum electrolytic capacitors, which are synonymous with passive components, electronic devices are fixed with adhesive tape to prevent device loosening after winding. The pressure-sensitive adhesive flows down, and unwinding occurs after winding up, and miniaturization of the aluminum electrolytic capacitor and short-term heat resistance temperature of 260 to 300 ° C are demanded. In addition, there was a problem such as dielectric breakdown due to corrosion of aluminum, which is a dielectric forming substrate, by ionization of halogen components in the adhesive component due to dissolution by paste.

The present invention is to solve the above problems, an object of the present invention to synthesize a pressure-sensitive adhesive excellent in heat resistance and chemical resistance to provide a polyimide adhesive tape for aluminum electrolytic capacitors.

When the present invention is 2-ethylhexyl acrylate (2-Ethylhexylacrylate) and n - butyl acrylate (n -Buthylacrylate) a main monomer and vinyl acetate (Vinyl acetate), and 1-vinyl-2-pyrrolidinone (1 Acrylic 7-membered copolymer, which is a co-monomer having vinyl-2-pyrrolidinone as a cohesive component and having acrylic acid, glycidyl methacrylate and hydroxyethyl as a functional group component The acrylic solution-type pressure-sensitive adhesive of was synthesized and was prepared using three major physical properties of the synthesized pressure-sensitive adhesive (Peel Strength), initial adhesive strength and holding power (Holding power) as a curing agent.

As a result of research on the curing system on the synthesized acrylic adhesive, a two-component adhesive was prepared based on isocyanate, which is good for the paste, and coated on the PI (Polyimide) substrate to test the adhesiveness 320 gf / 10mm, Tack 30mm Hereinafter, the result of the holding force of 4320min or more was obtained, and it was observed that the thermal stability was stable even at 250 ° C or higher. In addition, it was confirmed that the aluminum electrolytic capacitor impregnation solution, EG, GBL, and NMF, which were not solved, could be used as an aluminum electrolytic capacitor winding tape.

And coated on the actual tape to adjust the parameters of the mass production, viscosity, working speed, duct temperature, aging temperature, etc. produced by the specifications of aluminum electrolytic capacitors manufacturers, and obtained good results.

In order to achieve the above object, the present invention

When 2-ethylhexyl acrylate (2-Ethylhexylacrylate) and n - butyl acrylate (n -Buthylacrylate) of the main monomer, 50 to 90%, vinyl acetate (Vinyl acetate) as coagulation component and 1-vinyl-2-pyrrolidone 10-40% of monomers of dinon (1-Vinyl-2-Pyrrolidinone) and monomers of acrylic acid, glycidyl methacrylate and hydroxyethyl (Hydroxyethyl methacrylate) as functional components An acrylic pressure-sensitive adhesive made of ˜20% is provided, and the polyimide pressure-sensitive adhesive tape for an electrolytic capacitor using the acrylic pressure-sensitive adhesive,
Polyimide film substrates; And
The acrylic pressure sensitive adhesive layer applied to one side of the polyimide film substrate; It is made, including
The said polyimide film base material is achieved by providing the polyimide adhesive tape for electrolytic capacitors which has a thickness of 20-25 micrometers.

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It is preferable that both surfaces of the said polyimide film base material were corona-treated.

It is preferable that the corona treatment of both surfaces of the said polyimide film base material is 40-60 dyne / cm.

It is preferable that the other surface of the said polyimide film base material carries out silicone coating process.

 The acrylic pressure-sensitive adhesive and the polyimide pressure-sensitive adhesive tape for an electrolytic capacitor using the same according to the present invention have been greatly improved after the impregnation. Accordingly, it is expected to be used as a high-reliability substrate development technology, to improve the performance of polymer composite materials, to develop functional tapes for semiconductor processes through the development of acrylic-based special adhesives, to use heat-resistant adhesives for electronic materials, to synthesize UV-curable adhesives, and to provide functional tapes. .

[reagent]

A main monomer a 2-ethylhexyl acrylate, when (2-Ethylhexylacrylate) and used as the n-butyl acrylate (n -Buthylacrylate) was used as the "chemical Junsei use" product, the vinyl acetate used sieve complex strategy (Vinyl Acetate; VAc) used "Kanto chemical company" and 1-vinyl-2-pyrrolidinone (1-vinyl-2-pyrrolidinone; NVP) "Aldrich chemical company" product, acrylic acid (Acrylic acid; AA), Glycidyl Methacrylate (GMA) and 2-Hydroxyethyl Methacrylate (MEMA) were manufactured by "Junsei Chemical".

Benzoyl peroxide (BPO) is used as an initiator, and α, α'-azobis isobutyronitrile (AIBN) is a product of "Youngwoo Chemical Co., Ltd." Product was used.

As the solvent, ethyl acetate, methanol, and toluene were used as primary reagents of Daewon Chemical Co., Ltd. The crosslinking agent was used as "Desmodur RF" of "Bayer". The backing agent was used by diluting "peel-oil 1010 from" Asho "" RA-585S "," RA-95HS "and" Ipposha "in toluene. The substrate used was" China CEN ". In addition, EG, GBL, and NMF-based impregnation liquids were used in the "Samyoung Electronics Co., Ltd., Samsung Electro-Mechanics Co., Ltd., Daewoo Electronic Components".

Synthesis of Copolymer

As shown in Fig. 1, a 2-liter four-necked flask was equipped with a stirrer, a thermometer, and a reflux condenser. The total monomer was added at a concentration of 5M, and the order of addition was VAc (0.09), NVP (0.01), AA (0.023), n-BA (0.3), 2-EHA (0.5719), HEMA (0.0001), and initiator (2). × 10 ^-2 mol / ℓ) solution and solvent (EAc: TOL = 7: 3) in the order of heating, GMA (0.005) was added at 45 ℃ during heating and continued to increase the temperature, and at the same time the addition was completed at a stirring speed of 200rpm The polymerization was carried out at 64 ° C. for 8 hours. Upon completion of the reaction, the mixture was adjusted to 40% solids using toluene and cooled with cooling water to measure viscosity. 2 shows a wiring diagram of a pilot device.

Instrument analysis

After the polymerization of the acrylic copolymer, the mixture was left at room temperature for 5 days and then dried under reduced pressure for 1 week to remove the solvent. Nuclear Magnetic Resonance Spectrum (NMR) in the prepared substrate polymers was determined using chloroform-D (CDCL) containing tetramethylsilane (TMS) as an internal standard using ¹ H-NMR (nuclear magnetic resonance) of the "Bruker Advance 400 model". ₃ ) was measured as a solvent. The FT-IR was measured using a "FTS-185 Model" Infrared Spectrophotometer from "Bio-Rad," which was dissolved in THF and made into a film. TGA was modeled by "Perkin-Elemer" in the United States. 7 was used, and the Tg of the polymer was measured using a DSC-550 model of "Differential Scanning Calorimeter (DSC) Instrument Specialists". The measurement method was first heated from room temperature to 100 ° C. at a temperature rising rate of 10 ° C./min (1st run), and then cooled to −100 ° C. using liquid nitrogen, and Tg was tangent at the second heating (2nd run). The mid point of was investigated.

[Viscosity and Solids Measurement]

Viscosity measurement was carried out using a Brookfield Viscometer RVF-100 (Spindle Number 4 20 rpm) of the US "Brookfield Engineering Lab. Inc." after maintaining the polymer synthesized in a 25 ° C constant temperature water bath for 1 hour or more.

For solid content measurement, leave 1g of the synthesized sample in a constant temperature dryer at 110 ℃ for 3 hours, dry the volatiles sufficiently until there is no change in weight, and then leave the sample in the desigate for at least 30 minutes and weigh the weight according to the following equation. Solid content was calculated.

Solid content (%) = sample weight after drying / sample weight before drying × 100

[Saline content measurement]

Extract 2.5 ~ 2.8g of the sample in the beaker so that no foreign matter gets on the 100ml beaker, put the cut sample in 100ml volumetric flask with distilled water, fill it with 100ml of distilled water, and cool. Pipette 2 ml of the cooled sample into the test tube, and then add 1 ppm of the reference solution to the test tube, 1 ml, 2 ml, 3 ml, 4 ml, and 5 ml, respectively, and fill with 20 ml of distilled water. 1 ml of nitric acid (HNO ₃ ) to the test solution of the reference solution and the sample was added to the test tube of the sample solution and stirred with a stirrer. Leave the reference solution and chloride sample for 3 minutes, tilt the test tube with 1 ml of silver nitrate (AgNO ₃ ) and drop one drop at the end of the elliptical sample. At this time, there should be no shaking during the introduction of silver nitrate. The chloride standard solution is left in the dark box for 3 minutes, after comparing the turbidity between the reference solution and the chloride sample, the value of the reference solution with the most turbidity is read.

[Wetness test]

The specimen shall be taken with all the butterflies of the film from two locations, at least 2 meters away from the longitudinal direction of the sample. The swab, the test instrument, shall be wound as uniformly as possible at least 15 mm long at the end of a suitable length rod of approximately 1 mm in diameter. The standard solution is a mixture of formamide and ethylene glycol monoethyl ether. A small amount of dye with high coloration is added to the standard. The composition and surface age of the standard solution are shown in Table 1.

[Table 1] Composition and Surface Tension

The standard solution is applied by moistening a cotton swab so that water droplets do not fall and moving it in one direction to be horizontal to the sample. The width of the applied liquid film is spread as much as possible, and the area thereof is made about 6 cm. The application is completed in 0.5 seconds. Wetness determination is judged as a liquid film state for 2 seconds after the application of the reagent. It is assumed that there is wetness when the liquid film is not broken and the coating state is maintained for 2 seconds or more. Shrinkage around the liquid film within 2 seconds of the next application shall be non-wetting. If the wetness of the test is maintained for 2 seconds or more, a mixed solution having a high surface tension is added again. On the contrary, if the liquid film is broken or totally contracted within 2 seconds, a solution having a low surface tension is added. Repeat this operation and continue until you select the standard solution type with the closest composition to wet the specimen surface for exactly 2 seconds. The value of the selected standard liquid surface tension is taken as the wettability of the specimen. The value of the selected standard liquid surface tension is taken as the wettability of the specimen.

[Chemical Resistance and Heat Resistance Test]

Chemical resistance test

As the impregnation solution, the electrolytic capacitors have already used impregnation solutions of three major domestic companies. The tape is wound on the electrolytic capacitor according to the width of use, and the wound sample is completely precipitated in the electrolyte solution and placed in a closed glass container and stored in a constant temperature dryer for 100 hours at 85 ° C for EG and GBL systems and 105 ° C for NMF systems. However, after leaving for 24 hours at room temperature, the tip of the tape should be lifted less than 5mm.

Heat resistance test

The tape was wound in an electrolytic capacitor with a width of 2 mm, an electrolytic capacitor was made, soaked in a silicon oil bath at 160 ° C. for 2 minutes, and the aluminum case was taken out to determine the appearance of the tape.

[Tensile Strength and Elongation Test]

The specimen is cut into 10mm butterfly and three pieces 150mm long. Use the test device's capacity reading within 15 to 80% of its capacity. In the test method, the bite interval of the tensile tester or the scale interval of the test piece was set to 100 mm, and was pulled at a speed of 300 ± 30 mm / min to measure the load and elongation at break. At this time, tensile strength and elongation were calculated as follows and three average values were obtained.

T = 10 × P / WE = L1 - L0 / L0 × 100

T: Tensile Strength (kg / mm) E: Elongation (%)

P: Maximum load when cutting (kg) L0: Initial bleeding interval (mm)

W: Width of the test piece (mm) L1: Bleeding interval when cutting (mm)

[Measurement of Physical Properties of Adhesives]

The support used in the preparation of the sample for measuring the physical properties was used a polyimide film (PI) treated with corona 48dyn / cm on both sides with a thickness of 25㎛, the preparation procedure of the sample is as follows. First, the polyimide film, which is a support, is fixed on a simple coater, and the synthesized sample and the crosslinking agent are mixed well, poured in front of the roller, pulled between the rods and the rods, coated, dried for 30 seconds with a dryer, and then dried in a 110 ° C thermostat. After drying for seconds, the thickness was checked using a pyrometer. The sample whose thickness was confirmed was aged at 50 ° C. for 24 hours and then used as a sample for measuring physical properties.

180 ℃ peel ( Peel )

The method widely used by the evaluation method of the adhesiveness of an adhesive tape has the method of using a 90 degreeC peel, a 180 degreeC peel, and a cylinder. In the test of the adhesive tape, the conditions under which the adhesive tape is attached to the adhesive are to be constant. The adhesive tape was conditioned in a measuring room at 20 ± 2 ° C. and 65 ± 5% RH (2 hours or more on a film substrate, 8 hours or more on a cloth or paper substrate) according to JIS K 6854, followed by polishing with 280 abrasive papers. After reciprocating pressing (by automatic pressing roll tester) once on SUS 304 or SUS 302 stainless steel sheet with 2000 ± 50g rubber coated roller, it is left for 20 minutes or more and subjected to 180 ° C filling with 300 ± 30mm / min constant speed tensile tester. (See Figure 3).

Initial Adhesion (Rolling Ball Initial Adhesion)

In the initial measuring method using the steel ball, the adhesive tape is attached to the 30 ° inclined surface with the adhesive face up, and the steel ball is rolled up at a certain height to stop the adhesive face. There are J. Dow method for adhesive force and Douglas method for initial adhesive force with the distance until the ball enters the adhesive surface kept horizontally at the end of the inclined surface by rolling the steel ball on the slope of a certain height. In the present invention, it was measured using the Douglas method.

The test method is to make a measurement sample by cutting the coated film into 30 × 120mm size at the normal condition of test temperature 23 ± 2 ℃ and relative humidity 65 ± 5%, then inclination angle 30 °, steel ball running distance 50mm, measuring distance The sample is fixed to the 100 mm ball initial adhesive force measuring device so that the adhesive-coated surface is upward, and the material is made of high carbon chromium bearing steel (KS D3525) from 1/32 inch (No.1) to 32/32 inch ( The distance the ball was rolled was measured by rolling a steel ball up to NO.32) (see FIG. 4).

retention

Based on the holding force test method described in JIS Z 0237, the test method was as follows. First, the coating film was cut into a size of 25 × 55 mm to make a measurement sample. In the case of the product, the surface of the stainless steel sheet (SUS 304) used as the adherend was polished and washed 20 times in a uniform direction using a standard × 55 mm abrasive paper (sand paper No. 280). The sample was attached to the dried SUS plate in a size of 25 × 25 mm and then reciprocally compressed twice using a 2 kg rubber roller. After an hour, a fixed load of 1 kg was applied to the bottom of the sample, and the time taken for the sample to fall off the SUS plate was measured (see FIG. 5).

[Results and Discussion]

Polymerization of Copolymers

The monomer used as the main component in the acrylic pressure sensitive adhesive is relatively low in Tg and a flexible monomer is suitable. If a small amount of Tgrk high and solid monomer is added to the copolymer, cohesion and cohesion can be balanced.

In the present invention, two main monomers selected are 2-EHA and n- BA. However, the homopolymer of the above two monomers has high initial adhesive strength at room temperature due to long functional group with low polarity and low Tg, but it has the disadvantage of low holding force and adhesive strength and poor anchoring force when applied to adhesive tape. It was difficult. As a result, copolymerization with relatively high Tg and rigid comonomers was inevitable and VAc, NVP, and AA were selected. In order to increase the viscosity, polymerization was performed using GMA and HEMA capable of internal crosslinking to adjust monomer input ratio. Derivative 1 represents the acrylic copolymer prepared.

6 shows the IR spectra of the copolymers, wherein the CH3 stretching vibration of the alkyl group and the -CH ₂ -variable vibration exist around 1450cm ^-1 at 2960cm ^{- 1} and 2873cm ^-1 , respectively, and the C = O stretching vacuum of the carboxylic acid of AA. It was confirmed that it exists at 1734 cm ^-1 .

7 shows an NMR spectrum of a copolymer. Multiple peaks attributable to aliphatic CH ₃ at δ 0.9 to 1.0 ppm and acrylate ester groups at δ 2.0 to 2.5 ppm, as well as = C—CH ₂ —O— of 2-EHA, n -BA at δ 4.0 ppm Absorption peak of the 7-membered copolymer could be confirmed.

Structural Formula of Acrylic PSA

8 is an IR spectrum for confirming the crosslinking of the copolymer, and the NMR spectrum was not found because no solvent was dissolved after crosslinking. In FIG. 8, it was confirmed that the peak of 1553 cm ₋₁ was increased as the curing agent was added, compared to FIG. 6, which appeared as the NH peak in the urethane bond was reacted according to the addition of isocyanate. = 0 appears redundant at 1734 cm ₋₁ .

As in Induction Formula 2, the crosslinking reaction of the copolymer is a three-dimensional crosslinking by urethane bonding of the OH group and the curing agent NCO group in the adhesive. In order to accelerate the unreacted reaction, the cells were stored at 50 ° C. for 48 hours to mature.

[Structure Formula showing Crosslinking Reaction of Acrylic PSA]

Copolymer Thermal analysis

Tg, one of the major factors affecting the adhesion properties, has a mutually opposite effect on the initial adhesion and retention. Therefore, proper Tg control is essential for the optimal physical properties of the pressure-sensitive adhesive for the application conditions. Such Tg control is possible by the amount, the mixing ratio and the like of the type of monomer used in the polymerization.

In general, when a perfect random copolymer is obtained by copolymerization, the Tg of the copolymer can be theoretically calculated using the Fox equation. Of course, the Fox equation is proposed in the binary system, but when the ratio of the main monomer occupies 90%, it is extended to the 3 to 4 component system.

9 measured the Tg of the polymer using DSC. Schematically comparing the calculated theoretical Tg values,

1 / Tg = W ₁ / Tg ₁ + W ₂ / Tg ₂ + W ₃ / Tg ₃ + W ₄ / Tg ₄ + W ₅ / Tg ₅ + W ₆ / Tg ₆ + W ₇ / Tg ₇

Where Tg: glass transition temperature of the copolymer

Tg _{1 ,} Tg _{2 ,} Tg _{3 ,} Tg _{4 ,} Tg _{5 ,} Tg _{6 ,} Tg ₇ : 2-EHA (-70 ° C), n -BA (-55 ° C)

                             VAc (32 ° C), NVP, AA (106 ° C)

                             Glass transition temperature of GMA, HEMA (55 ° C) homopolymer

W ₁ (0.5719), W ₂ (0.3), W ₃ (0.09), W ₄ (0.01), W ₅ (0.023), W ₆ (0.005), W ₇ (0.0001) It is the weight fraction of each composition.

Although somewhat different from the results in FIG. 9, the Fox equation is in good agreement with the theoretical Tg. In view of these results, it can be seen that the acrylic 7-membered copolymer polymerized in this study is a disordered copolymer, and Tg can be arbitrarily controlled by changing the input ratio of the monomer, and only by theoretical calculation, It was found that the adhesive could be designed.

Physical Properties of Synthesized Copolymer

10 is a result of measuring the adhesiveness of the synthesized copolymer using a 180 ° peel test method according to the amount of the curing agent added. As a result, it can be seen that the pressure-sensitive adhesive was 350g.f / 10mm level at 0.4 part of the curing agent and about 230g.f / 10mm pressure-sensitive adhesive was synthesized at 1.0 part. In the case of the initial adhesion in Figure 11 the larger the value means that the initial adhesion is not good. In the case of one part of the curing agent is also less than 30mm synthesized copolymer was found to be excellent in the initial adhesive strength. Figure 12 is a holding force data, in the case of 25mm hardener 0.4 part shows the results of experiments with a width of 10mm did not fall for 1 week from the weight of 1kg.

When the acrylic adhesive is used for the adhesive tape, when the curing agent is thermosetting, there is a lot of difficulty in product productivity due to the proper maturation period. Therefore, Desmodus RF, which is an unstrained type at room temperature, is used. In order to determine the progress of aging, the changes in cohesion and initial cohesion according to aging time were measured and shown in FIG. 13 and FIG. 14, and the results within the margin of error were judged to be sufficient for three days. It is desirable to confirm by dropping toluene.

TABLE 2

Table 2 looks at the characteristics of OPP and PI. Compared to OPP, PI is expensive, so domestic companies rarely use PI adhesive tape and import Japanese products with good heat resistance among OPP adhesive tape.

It is sectional drawing of the polyimide adhesive tape for electrolytic capacitors which concerns on this invention. Adhesive tape 100 according to the present invention is a polyimide film substrate 104; And an acrylic adhesive 102 applied to one side of the polyimide film substrate 104. Here, it is preferable that the polyimide film base material 104 has a thickness of 20-25 micrometers. It is preferable that the acrylic adhesive 106 has a thickness of 20-30 micrometers. It is preferable that both surfaces of the polyimide film base material 104 are corona-treated. It is preferable that the corona treatment of both surfaces of the polyimide film base material 104 is 40-60 dyne / cm. It is preferable that the other surface of the polyimide film base material 104 is coated with the silicon layer 106.

16 and 17 are PI and OPP spectra. 18 is a TGA spectrum of 0.4 part of a crosslinking agent added to the synthesized copolymer.

[Table 3] Chemical resistance test results by coating backing agent and acrylic adhesive on PI fabric

Table 3 shows the results of the chemical resistance test by applying a double-sided corona treatment on the PI fabric, one side coated with a backing agent, and a coated acrylic adhesive on one side. The backing agent was composed of a fatty acid organic compound and melted at 100 ° C. or higher, thus causing annealing to hinder the role of the adhesive tape.

[Table 4] Chemical resistance test according to the type of curing agent

Table 4 shows the chemical resistance test according to the type of curing agent. The epoxy and melamine type used as the curing agent in the synthesized copolymer had a lower chemical resistance in the GBL type compared to the isocyanate, and some isocyanate and epoxy type. When mixed with the NMF system showed the best results, but the three-component form was complicated to manage, many companies mainly use the EG and GBL system was used isocyanate alone.

Pot life in acrylic adhesives is very important in the process. Hardening of the acrylic adhesive during production greatly affects the basic properties of the adhesive, such as separation of the substrate and the adhesive after coating. When the mixture was mixed with 0.4% of the curing agent in the acrylic pressure-sensitive adhesive, all solidified after 30 minutes. Thus, methanol was used to adjust the pot life, and the pot life is shown in FIG.

Methanol has many difficulties in defining the reaction mechanism, such as forming a complex by hydrogen bonding with an isocyanate curing agent and affecting the reaction rate. It is affected by the dielectric constant of the urethane solvent in the solution. The higher the dielectric constant is, the more difficult the nucleophilic alcohol attack is. Therefore, the reaction is slow and the mechanism that alcohol acts as a catalyst when there is no acid or base acting as a catalyst.

According to the research of Baker et al., The urethane formation reaction shows that the step k1 in which R-NCO and R-NCO and R-ON form a complex is a rate determining step, and the reaction proceeds in the second order.

Induction 3 examined the structure of the main impregnation solution used in the chemical resistance test. Addition of additives such as triethyleneamine, boric acid, water, and the like is known to make an electrolytic capacitor impregnation solution, the chemical resistance is weaker than pure GBL, NMF reagent.

Structural Formula of Main Impregnation Solution

The synthesized copolymers were synthesized by 2-EHA, n-BA, VAc, NVP, AA, GMA, HEMA 7-way copolymer adhesive in Lab and Pilot, the viscosity was 2700cps at 40% solids, the yield was 93%.

The synthesized acrylic pressure sensitive adhesive was prepared using an isocyanate crosslinking agent and a two-component pressure sensitive adhesive. At this time, the physical properties of the peel strength (Peel strength) 320g.f / 10mm, the initial adhesive strength 30mm or less, the holding force was 0.1mmm / 4320min or more. Salinity of 5 ppm or less was detected as a result of salinity measurement, and the result of the impregnation solution test was excellent in EG system, GBL system and NMF system. Thermal analysis showed that it was able to withstand up to 160 ° C.

[Table 5] Properties of Adhesive Tapes Coated by PI

Table 5 shows the physical properties of the adhesive tape prepared by coating on PI. It was suitable as an adhesive tape of an aluminum electrolytic capacitor.

20 is a photograph showing an example in which the adhesive tape produced according to the present invention is applied.

1 is a view of an experimental apparatus equipped with a stirrer, a thermometer and a reflux condenser in a four-necked flask used in the present invention;

2 is a wiring diagram of a pilot device used in the present invention;

3 is a perspective view of a Peel test apparatus used in the present invention;

4 is a perspective view of the initial adhesion test apparatus used in the present invention;

5 is a perspective view of the holding force test apparatus used in the present invention;

6 is an IR spectrum of the acrylic adhesive according to the present invention;

7 is an NMR spectrum of an acrylic pressure sensitive adhesive according to the present invention;

8 is an IR spectrum of the curing agent added to the acrylic pressure-sensitive adhesive according to the invention;

9 is a DSC spectrum of the acrylic pressure sensitive adhesive according to the present invention;

10 is a graph showing the change in viscosity with temperature of acrylic PSA according to the present invention;

11 is a graph showing a change state of the adhesive force according to the amount of the curing agent added to the acrylic adhesive according to the present invention;

12 is a graph showing a state of change in the initial adhesive strength according to the amount of the curing agent added acrylic adhesive according to the present invention;

13 is a graph showing a change state of the holding force according to the amount of the curing agent of the acrylic pressure-sensitive adhesive according to the present invention;

14 is a graph showing a change in the peel strength (Peel strength) according to the curing time of the acrylic adhesive according to the present invention;

15 is a cross-sectional view of a polyimide adhesive tape for an electrolytic capacitor according to the present invention;

16 is a DSC spectrum of PI which is a substrate of the polyimide adhesive tape for an electrolytic capacitor according to the present invention;

17 is a DSC spectrum of OPP which is a base material of the polyimide adhesive tape for an electrolytic capacitor according to the present invention;

18 is a TGA spectrum in which a crosslinking agent is added to an acrylic pressure sensitive adhesive according to the present invention;

19 is a graph of Pot life showing viscosity versus time of an acrylic pressure sensitive adhesive according to the present invention; And

20 is a product to which the acrylic adhesive according to the present invention and a polyimide adhesive tape for an electrolytic capacitor using the same.

Explanation of symbols on the main parts of the drawings

100: polyimide adhesive tape

102: acrylic adhesive

104: polyimide film base material

106: silicon layer

Claims (7)

delete delete When 2-ethylhexyl acrylate (2-Ethylhexylacrylate) and n - butyl acrylate (n -Buthylacrylate) of the main monomer, 50 to 90%, vinyl acetate (Vinyl acetate) as coagulation component and 1-vinyl-2-pyrrolidone 10-40% of monomers of dinon (1-Vinyl-2-Pyrrolidinone) and monomers of acrylic acid, glycidyl methacrylate and hydroxyethyl (Hydroxyethyl methacrylate) as functional components An acrylic pressure-sensitive adhesive made of ˜20% is provided, and the polyimide pressure-sensitive adhesive tape for an electrolytic capacitor using the acrylic pressure-sensitive adhesive, Polyimide film substrates; And The acrylic pressure sensitive adhesive layer applied to one side of the polyimide film substrate; It is made, including Said polyimide film base material has thickness of 20-25 micrometers, The polyimide adhesive tape for electrolytic capacitors characterized by the above-mentioned. The polyimide adhesive tape for electrolytic capacitor according to claim 3, wherein the acrylic pressure sensitive adhesive layer has a thickness of 20 to 30 µm. The polyimide adhesive tape for electrolytic capacitor according to claim 3, wherein both sides of the polyimide film base material are corona treated. The polyimide adhesive tape for electrolytic capacitors of Claim 5 whose corona treatment of both surfaces of the said polyimide film base material is 40-60 dyne / cm. The polyimide adhesive tape for electrolytic capacitor according to claim 3, wherein the other side of the polyimide film base material is coated with a silicon layer.

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