JP2003151347A - Conductive paste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a one-pack type conductive paste free of cracked gas even in the case of long service in a gas-sealed condition, flexible and heat resistant as well as superior in storage stability and usable as a conductive adhesive for a crystal piece of a quartz resonator, e.g. SOLUTION: The conductive paste comprises a resin having at least two hydroxyl groups contained in each molecule, a curing agent having a ureshodione structure and a conductive particulates. In details, the curing agent having the ureshodione structure has a melting temperature of 70 deg.C or higher. Furthermore, a dissociation promoting catalyst contained therein is used for the curing agent having the ureshodione structure.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention does not generate decomposition gas even when used for a long time in an airtight state, has flexibility (flexibility) and heat resistance, and has excellent storage stability. , For example, relates to a one-component conductive paste used as a conductive adhesive for a crystal piece in a crystal resonator.

[0002]

2. Description of the Related Art Conventionally, as a conductive paste for forming a circuit on a flexible printed circuit board or for adhering a crystal piece on a crystal resonator, for example, JP-A-61-91802 and JP-A-62-72749 disclose. Can be seen. And
The inventions described in these publications particularly improve the flexibility as a urethane polymer, a polyhydric alcohol, a conductive paste composed of a conductive powder, and further, in this conductive paste, a petroleum resin having a hydroxyl group. Is a conductive paste to which is added. The urethane polymer is blocked with an active hydrogen compound and treated so as to maintain stability. Specifically, it is a polyester or polybutadiene having a terminal active isocyanate group blocked with a blocking agent such as acetoacetic acid ester, cyclohexanone oxime, or phenol. However, in a urethane resin using such a blocked isocyanate, when used for a long time in an airtight state, it is difficult to completely separate the isocyanate blocking agent, which is the precursor of the urethane resin, so that the residual blocking agent decomposes. As a result, decomposed gas such as water is generated, and when the gas is in a low temperature state, the water and the like are solidified to impair the frequency stability of the crystal unit.

[0003]

SUMMARY OF THE INVENTION Therefore, the problem to be solved by the present invention is that no decomposition gas is generated even when used in an airtight state for a long time, and heat resistance and appropriate flexibility are provided. It has excellent impact resistance and storage stability, and does not impair the frequency stability of the oscillator even when used as, for example, a conductive adhesive for a quartz piece in a quartz oscillator. It is to provide a one-pack type conductive paste.

[0004]

[Means for Solving the Problems] In order to solve the above problems, one molecule contains two or more hydroxyl group-containing resins, a curing agent having a uretdione structure, and conductive fine powder. The NCO / OH molar ratio of the number of the hydroxyl group-containing resins and the curing agent having the uretdione structure is 1.
The problem is solved by using a conductive paste that is 0 to 2.0. More preferably, the curing agent having the uretdione structure (hereinafter referred to as “uretdione curing agent”) has a melting temperature of 70 ° C. or higher, and further, a dissociation promoting catalyst for the uretdione curing agent in the conductive paste. It is a one-component type electroconductive paste containing.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.
The invention described in claim 1 comprises two or more hydroxyl group-containing resins (hereinafter referred to as “hydroxyl group-containing resin”) in one molecule, the uretdione curing agent and conductive fine powder, and the hydroxyl group-containing resin and uretdione. It is a conductive paste in which the NCO / OH molar ratio of the hardener having a structure is 1.0 to 2.0. The conductive paste having such a composition does not generate decomposed gas (especially moisture) even if the cured product after being heat-cured is used in a sealed state for a long period of time, and the cured product has an appropriate flexibility. It has resistance and heat resistance, and has impact resistance. Since this conductive paste can be used as a one-pack type, it is convenient to handle. Therefore, such a conductive paste is preferable as a conductive adhesive for various applications used in a sealed state.

As the hydroxyl group-containing resin, polyester resin, polyether resin, acrylic resin, polycaprolactone polyol resin, polycarbonate resin, polybutadiene resin having a hydroxyl group at the terminal, hydrogenated isoprene rubber having a terminal hydroxyl group. And the like. Specific examples of these resins include, as a polyester-based resin, Nippon Polyurethane Co., Ltd., trade name Nipporan 8
00, made by Kuraray Co., Ltd., trade name CLAPOL P-4010, CLAPOL F-3010, etc., Sanyo Kasei Co., Ltd., trade name Sannix PP-3000, etc. as polyether resin, Dainippon Ink and Chemicals Inc. as acrylic resin Kogyo Co., Ltd., trade name Acridic A-801, etc., as a polycaprolactone polyol resin, Daicel Chemical Industry Co., Ltd., trade name Praxel L312AL, Praxel L23.
0AL and the like are polycarbonate resins such as those manufactured by Daicel Chemical Industries, Ltd. under the trade name Praxel CD220PL,
As the polybutadiene resin having a hydroxyl group at the terminal, Idemitsu Petrochemical Co., Ltd., trade name poly-bdR-45HT and the like,
Examples of hydrogenated isoprene rubber having a terminal hydroxyl group include Epol, manufactured by Idemitsu Petrochemical Co., Ltd. These resins preferably have a glass transition temperature lower than 20 ° C., and among them, those which are liquid at room temperature are more preferable.

As the curing agent for the hydroxyl group-containing resin, a curing agent having a uretdione structure is preferable. For example, it is sold under the trade name of Clerant TPLS2147 (Sumitomo Bayer Urethane Co., Ltd.) and is represented by the following chemical formula (1). By using the uretdione curing agent having such a structure, the isocyanate blocking agent is not liberated, so that even if it is used in a sealed state for a long time, no decomposition gas or the like (particularly moisture) is generated, and By using a polyester resin having a molecular weight of 1000 or more as the hydroxyl group-containing resin, the flexibility (flexibility) and heat resistance also become excellent. The uretdione curing agent preferably has a melting temperature of 70 ° C. or higher in view of the conductive adhesive which is the application of the present invention. That is, by using such a curing agent, it becomes stable without reaction at the storage temperature.

A solvent is generally used for adjusting the viscosity of the conductive paste. In the present invention, a solvent having no active hydrogen is preferable, for example, isobutyl acetate, ethyl carbitol, isophorone and the like. Can be mentioned.

[0009]

[Chemical 1]

The conductive fine powder used in the present invention is not particularly limited, but nickel,
Metal powder such as silver, copper, brass, stainless steel, zinc, tin, etc.,
Flake powder is carbon black, graphite,
A conductive carbon material such as carbon fiber is used alone or as a mixture. The size is preferably 30 μm or less. This is because when a dispenser is used for coating, the needle may be clogged if there is a powder component larger than 30 μm.

Further, it is preferable to add a dissociation promoting catalyst for the uretdione curing agent to the above-mentioned conductive paste. This dissociation promoting catalyst is preferable because it can reduce the curing reaction temperature of the uretdione curing agent from about 1800 ° C. to about 150 ° C., which improves productivity. As such a dissociation promoting catalyst, 1,5-diazabicyclo (4,4
3,0) Nonene-5,1,5-diazabicyclo (4,4
3,0) -Nonene-7,1,8-diazabicyclo (5,5)
4,0) Undecene-7,6-dibutylamino-1,8
-Diazabicyclo (5,4,0) undecene-7 and the like. In the present invention, 1,5-diazabicyclo (4,3,0) nonene-5 is preferably used.

When the above-mentioned conductive paste thus obtained is used as the conductive wiring of the crystal piece of the crystal unit in the standard timepiece, which is the application of the present invention, the blending ratio of the conductive paste is set. , Like this: That is, two or more hydroxyl groups (-OH) in one molecule
The compounding ratio of the resin having uretdione compound and the uretdione compound is such that 1 mol of uretdione functional group is 2 mol of isocyanate group (--NC
O) is to be regenerated, in molar ratio, NCO / OH =
1.0 to 2.0 is desirable. The number of moles of hydroxyl group and the number of moles of isocyanate group were determined by the following formulas (1) and (2). Formula (1) Number of moles of hydroxyl group = resin weight (g) × hydroxyl number × 1000 / 56.1 Formula (2) Number of moles of isocyanate group = curing agent weight (g) × isocyanate group content (%) ÷ 100 ÷ 42

When the NCO / OH molar ratio is less than 1.0, the conductive paste is liable to be incompletely cured, and when it is more than 2.0, the resulting cured product loses flexibility and has drop impact resistance. There is a risk of becoming weak. Also,
If the molecular weight of the resin having a hydroxyl group is 1000 or less,
The obtained cured product may lose flexibility and drop impact resistance may deteriorate. The weight ratio of the resin component comprising the hydroxyl group-containing resin and the uretdione curing agent to the conductive fine powder is preferably 75/25 to 90/10. When the weight ratio of the resin component composed of the hydroxyl group-containing resin and the curing agent to the conductive fine powder is less than 75/25, the conductivity of the conductive paste obtained may be insufficient, which is not preferable. Further, if the weight ratio of the resin component composed of the hydroxyl group-containing resin and the curing agent to the conductive fine powder exceeds 90/10, the adhesive force of the conductive paste obtained may be reduced, which is not preferable.

Further, the cured product of the conductive paste thus obtained does not generate any decomposed gas at all even if it is used in an airtight state for a long period of time. There is no problem such as loss of stability.
Further, also for conductive wiring, a conductive paste having excellent flexibility that can withstand impact resistance due to dropping and excellent heat resistance can be obtained. Further, if the addition amount of the dissociation-accelerating catalyst for the uretdione curing agent is less than 0.5%, the temperature required for curing may not be lowered sufficiently. Further, since the dissociation accelerating catalyst is not incorporated in the curing reaction system, it does not improve the performance even if it is added in an amount more than necessary, and usually the amount added is preferably 3% or less.

As described above, the conductive paste of the present invention is composed of two or more hydroxyl group-containing resins in one molecule, a curing agent having a uretdione structure, and conductive fine powder, and therefore has storage stability. The cured product does not generate decomposition gas or the like even if it is used in a sealed state for a long period of time, and has heat resistance and excellent flexibility even when used as a conductive adhesive. Therefore, it is also excellent in impact resistance.
Further, the melting temperature of the curing agent having the uretdione structure is 70
The use of the one having a temperature of about 0 ° C. further improves the storage stability and is therefore preferable for producing a one-pack type conductive paste.
In addition to the above-mentioned characteristics, a curing reaction due to the dissociation of the uretdione curing agent can be performed by adding a dissociation promoting catalyst for the curing agent having a uretdione structure, for example, a conventional 180
It is possible to lower the temperature from about 150 ° C to about 150 ° C, which is preferable because the productivity is improved. In addition, a filler, an antioxidant, a coloring agent, a fluidity adjusting agent, and the like can be added to the conductive paste, if necessary.

The effects of the present invention will be clarified by showing examples below.

[Example 1] 6.0 parts of polyester polyol (manufactured by Daicel Chemical Industries, Ltd .: Praxel L312AL, molecular weight 1250), butyl cellosolve acetate 1
0.5 part, non-blocked polyisocyanate (Sumitomo Bayer Urethane Co .: TPLS2147, melting temperature about 7
Non-block aliphatic polyuretdione at 0-80 ℃)
7.2 parts, uretdione dissociation promoting catalyst (Sumitomo Bayer Urethane Co., Ltd .: DBN) 1.4 parts, nickel powder (Nikko Rica Ni # 255) 11.0 parts, carbon black (Tokai Carbon Co., Ltd. Toka Black # 4500) ) 1.5
Part, flaky silver powder (FA-6-7 manufactured by Dowa Mining Co., Ltd.) 6
2.3 parts were kneaded three times with a three-roll to obtain a one-pack type conductive paste.

The conductive paste had an NCO / OH ratio of 1.5 and a viscosity of 390 dPas. This is 30
The viscosity after standing at 90 ° C. for 90 days is 400 dPas, which is a one-component type conductive paste having a long pot life. Then paste this paste at 150 ℃
Then, the elastic modulus of the thin film produced by performing the curing treatment for 60 minutes was measured. Rheometer (Rheometric Co .: R
When evaluated by SA-II), 7.2 × 10 8 Pa (30
C.), and the pencil hardness of the cured thin film was as flexible as B. Moreover, the pencil hardness after aging this thin film at 125 ° C. for 500 hours maintained B and the initial hardness. Further, with respect to a cured product produced by curing the conductive paste at 150 ° C. for 60 minutes, the water content after curing and after aging at 125 ° C. for 500 hours was 0.043%.
Was 0.047% and there was almost no change in the amount. Also,
This conductive paste is used as a conductive wiring for a crystal unit and incorporated into a substrate, and after dropping from a height of 1 meter 5 times to give an impact, the resistance of the crystal piece changes due to cracking or cracking. Was measured, but no abnormality was found.

Example 2 The polyester polyol described in Example 1 (Placcel L3 manufactured by Daicel Chemical Industries, Ltd.)
12AL, molecular weight 1250) 7.0 parts, non-blocked polyisocyanate (Sumitomo Bayer Urethane Co .: TPL
S2147, 6.2 parts of non-blocking aliphatic polyuretdione having a melting temperature of about 70 to 80 ° C) was obtained in the same manner as in Example 1 to obtain a one-component type conductive paste.

This conductive paste has an NCO / OH ratio of 1.2.
The viscosity was 395 dPas. The viscosity after leaving it at 30 ° C. for 90 days is 390 dPa.
s, which has a long pot life as a one-pack type conductive paste. Then paste this paste 15
The pencil hardness of the cured thin film produced by the curing treatment at 0 ° C for 60 minutes is as flexible as B, and is 500 at 125 ° C.
The pencil hardness after aging for a period of time also maintained B and the initial hardness. Furthermore, by using this conductive paste as a conductive wiring for a crystal unit and incorporating it into a board, it is dropped 5 times from a height of 1 meter to give a shock, and then the resistance value due to cracking or cracking of the crystal piece occurs. I measured the change,
No abnormality was found.

[Example 3] The polyester polyol described in Example 1 (manufactured by Daicel Chemical Industries, Ltd .: Praxel L3)
12AL, molecular weight 1250, 5.3 parts, non-blocked polyisocyanate (Sumitomo Bayer Urethane Co .: TPL
S2147, non-block aliphatic polyuretdione having a melting temperature of about 70 to 80 ° C.) was 7.9 parts to obtain a one-component type conductive paste in the same manner as in Example 1.

This conductive paste has an NCO / OH ratio of 2.0.
The viscosity was 395 dPas. The viscosity after leaving it at 30 ° C. for 90 days is 385 dPa.
s, which has a long pot life as a one-pack type conductive paste. Then paste this paste 15
The pencil hardness of the cured thin film produced by curing at 0 ° C for 60 minutes is HB and is flexible.
As for the pencil hardness after aging for 0 hour, B and the initial hardness were almost maintained. Also, by using this conductive paste as a conductive wiring for a crystal unit and incorporating it into a substrate, it is dropped 5 times from a height of 1 meter and given a shock, and then the resistance value due to cracking or cracking of the crystal piece occurs. Was measured, but no abnormality was found.

[Example 4] A one-pack type conductive paste was obtained in the same manner as in Example 1, except that the uretdione dissociation promoting catalyst (DBN manufactured by Sumitomo Bayer Urethane Co., Ltd.) was omitted from Example 1.

The viscosity of this conductive paste is 390 dP.
was as. The viscosity of this after left to stand at 30 ° C. for 90 days is 400 dPas, and it has a long pot life as a one-pack type conductive paste. Moreover, the pencil hardness of the cured thin film prepared by curing this paste at 180 ° C. for 60 minutes is B, and the pencil hardness after aging at 125 ° C. for 500 hours is also:
B and initial hardness were almost maintained. Then, by using this conductive paste as a conductive wiring for a crystal unit and assembling it on a substrate, it was dropped 5 times from a height of 1 meter to give a shock, Changes were measured, but no abnormalities were found. This conductive paste is an example in which a dissociation promoting catalyst for a curing agent having a uretdione structure is not used, but it is a flexible adhesive that does not generate decomposition gas as a conductive adhesive and has impact resistance.

[Comparative Example 1] Polyester polyol of Example 1 (manufactured by Daicel Chemical Industries: Praxel L312A)
L, molecular weight 1250) 7.9 parts, non-blocked polyisocyanate (Sumitomo Bayer Urethane Co .: TPLS21
47, non-block aliphatic polyuretdione having a melting temperature of about 70 to 80 ° C.) of 5.3 parts was obtained in the same manner as in Example 1 to obtain a one-component type conductive paste.

This conductive paste has an NCO / OH ratio of 0.9.
The viscosity is 385 dPas, which is 3
The viscosity after standing for 90 days at 0 ° C. is 390 dPas, and it has a long pot life as a one-pack type conductive paste. However, this paste
The cured thin film prepared by curing treatment for 60 minutes was too soft with an initial pencil hardness of 3B due to lack of curing agent, and after aging at 125 ° C for 500 hours, the pencil hardness was deteriorated due to polyester deterioration. Fell further to 6B.

[Comparative Example 2] Polyester polyol of Example 1 (Placcel L312A manufactured by Daicel Chemical Industries, Ltd.)
L, molecular weight 1250) 5.0 parts, non-blocked polyisocyanate (Sumitomo Bayer Urethane Co .: TPLS21
47, a non-block aliphatic polyuretdione having a melting temperature of about 70 to 80 ° C.) of 8.2 parts was obtained in the same manner as in Example 1 to obtain a one-pack type conductive paste.

This conductive paste has an NCO / OH ratio of 2.2.
The viscosity is 400 dPas, which is 3
The viscosity after standing at 0 ° C. for 90 days is 380 dPas, which also has a long pot life as a one-pack type conductive paste. But this paste 1
The cured thin film produced by curing at 50 ° C for 60 minutes
The initial pencil hardness was B, which was flexible, but 125 ° C
After aging for 500 hours, the pencil hardness increased to H due to the excessive amount of the curing agent. In addition, when this conductive paste was used as a conductive wiring for a crystal unit and incorporated into a substrate, it was dropped 5 times from a height of 1 meter and shocked. changed.

Comparative Example 3 3.2 parts of polyester polyol (Kuraray Co., Ltd .: Kurapol F3010), polyester polyol (Kuraray Co., Ltd .: Kurapol P4010)
7.0 parts, butyl cellosolve acetate 4.7 parts, blocked isocyanate (Sumitomo Bayer Urethane Co., Ltd .: Desmodur 3370MPA) 6.1 parts, flake silver powder (Dowa Mining Co., FA-6-7) 78. Five parts were kneaded three times with a three-roll to obtain a one-pack type conductive paste.

Since this conductive paste uses blocked isocyanate, the cured product produced by curing treatment at 150 ° C. for 60 minutes is 500 after curing and at 125 ° C.
The water content after time aging was 0.091%, 0.360%, which was about four times increased, which was not preferable.

[0031]

As described above, the conductive paste of the present invention is composed of one or more hydroxyl group-containing resin in one molecule, a curing agent having a uretdione structure, and conductive fine powder, so that it can be stored. The stability is excellent, and even if the cured product is used in a sealed state for a long period of time, no decomposed gas is generated, and the frequency stability of the crystal unit is not impaired. Even when used as a conductive adhesive, it has excellent heat resistance and excellent flexibility (flexibility), and is also excellent in impact resistance such as dropping. Furthermore, as a curing agent having a uretdione structure,
The use of one having a melting temperature of about 70 ° C. is excellent in storage stability and is preferable for producing a one-pack type conductive paste. Further, by adding a dissociation promoting catalyst for a curing agent having a uretdione structure, the curing reaction due to the dissociation of a curing agent having a uretdione structure can be lowered from the usual 180 ° C. to about 150 ° C. It becomes possible, and it also has the effect of improving productivity.

Continued front page    F-term (reference) 4J034 BA01 BA03 DA01 DB03 DB07                       DC01 DC02 DC50 DF01 DF02                       DG00 DL01 DP18 DP19 GA01                       GA51 HA01 HC32 HC33 HC34                       HD00 RA08                 4J040 EF111 EF131 EF181 EF251                       HA026 HA036 HA066 JA05                       JB10 KA03 KA14 KA32 LA07                       LA08 MA01                 5G301 DA53 DA60

Claims (3)

[Claims] 1. A curing agent comprising two or more hydroxyl group-containing resins and a curing agent having an uretdione structure in one molecule, and conductive fine powder, and curing having two or more hydroxyl group-containing resins and an uretdione structure in each molecule. The conductive paste, wherein the NCO / OH molar ratio of the agent is 1.0 to 2.0. 2. The conductive paste according to claim 1, wherein the curing agent having the uretdione structure has a melting temperature of 70 ° C. or higher. 3. The conductive paste according to claim 1, wherein a dissociation promoting catalyst for the curing agent having the uretdione structure is added to the conductive paste.