JP4896366B2 - Adhesive and method for producing the same - Google Patents

Description

  The present invention relates to an adhesive and a method for producing the same, and more particularly to an improvement for extending the usable time of an adhesive including an inorganic filler.

  For example, when connecting various terminals and electrically connecting flexible printed circuit boards (FPC) and TAB and ITO terminals formed on the glass substrate of the liquid crystal panel, anisotropy A conductive adhesive film (ACF) is used. Anisotropic conductive adhesive films have become mainstream from the viewpoints of reliability, convenience in use, etc., and are generally composed of an epoxy resin, a curing agent, and conductive particles. Yes.

  In this type of anisotropic conductive adhesive film, various designs are required depending on the application in terms of usable period, function, etc. For example, the epoxy adhesive constituting the anisotropic conductive adhesive film is a latent It is made to make the usable period (life) and thermal activity compatible with the adhesive curing agent.

In addition, a technique for improving adhesive strength and the like by adding various coupling agents (see, for example, Patent Document 1 and Patent Document 2) and a technique for adjusting viscosity by dispersing filler (for example, Patent Document 3) Etc.) are proposed. Specifically, Patent Document 1 includes a (meth) acryloylated novolak resin having a phenolic hydroxyl group, an organic peroxide, a thermoplastic elastomer, a maleimide, and an aminosilane coupling agent as essential components. A heat curable anisotropic conductive adhesive that can be connected and has excellent adhesion, connection reliability, storage stability, and repairability is disclosed. Patent Document 2 includes an adhesive matrix curable resin, a curing agent, a conductive substance, and a coupling agent, and provides a highly reliable circuit connection by extending the period of use and increasing the reaction rate of the matrix resin. Possible anisotropically conductive adhesive compositions are disclosed. In Patent Document 3, a thickener, a latent curing agent, a liquid epoxy resin, conductive fine particles, and non-conductive organic fine particles are essential components, and a viscosity change is small and an adhesive for circuit connection with excellent connection reliability ( Anisotropic conductive adhesives are disclosed.
Japanese Patent Laid-Open No. 11-209713 JP-A-6-52715 JP 2000-86988 A

  By the way, as described in the above-mentioned Patent Document 3 and the like, a filler may be included in the adhesive for the purpose of improving functions such as viscosity adjustment and adjustment of thermal expansion coefficient. When used, depending on the type and structure of the filler, the potential of the latent curing agent may be reduced, and the usable period (life) may be shortened. This is expected because the inorganic filler acts as a curing catalyst for the epoxy adhesive. Inorganic fillers are generally fine particles of oxide, have a large surface area, and have high surface activity because OH groups are present on the surface. This high surface activity is considered to act as a curing catalyst for the epoxy adhesive.

In addition, as an inorganic filler, alumina (Al ₂ O ₃ ), mullite (Al ₂ O ₃ —SiO ₃ ), etc. are excellent in thermal conductivity, and when blended in an anisotropic conductive adhesive film, etc., heat shock test Although it is particularly good for thermal shock at the same time, it has a tendency to have a great impact on life and there are restrictions on the formulation, so it is the reality that silica (SiO ₂ ) or the like that has little such influence is substituted. It is.

  The present invention has been proposed in view of such a conventional situation. That is, an object of the present invention is to provide an adhesive having a novel formulation that can ensure a predetermined usable period even when an inorganic filler is added for the purpose of adjusting viscosity or adjusting thermal expansion coefficient. . Another object of the present invention is to provide an adhesive that can be freely adjusted in viscosity, adjusted in thermal expansion coefficient, and the like, without any restrictions on the composition of the inorganic filler.

  The inventors of the present invention have made various studies over a long period of time in order to achieve the above-described object. As a result, the inventors have come up with the idea that the curing catalyst can be deactivated by modifying the surface state of the inorganic filler (inorganic particles) with a silane coupling agent. However, the effect could not be confirmed even when the surface treatment was performed with a silane coupling agent having a general structure. This is presumably because the film formed on the surface of the inorganic filler is weak. Therefore, as a result of further earnest research, the inventors have come to know that life can be dramatically improved by modifying the surface of the inorganic filler with a specific silane coupling agent.

The present invention has been completed based on these findings, and the adhesive of the present invention includes a binder component, a curing agent, and an inorganic filler, and has a functional group capable of reacting with the binder component. The binder component contains an epoxy resin, the silane coupling agent is a diaminosilane coupling agent or a triaminosilane coupling agent, and the inorganic filler is Al. And is surface-treated with 15 to 40% by weight of the silane coupling agent with respect to its weight . Here, the functional group capable of reacting with the binder component is a functional group having a nitrogen atom N and an active hydrogen H, specifically an amino group or an isocyanate group. It is preferable to have two or more of these functional groups. Moreover, the manufacturing method of the adhesive agent of this invention is characterized by adding a binder component after surface-treating an inorganic filler previously with the silane coupling agent which has a functional group which can react with a binder component.

  The above-mentioned silane coupling agent binds to the OH group that is the active site of the inorganic filler at the Si site and is adsorbed on the surface of the inorganic filler. At the same time, a functional group such as an amino group is bonded to the binder component, and the surface of the inorganic filler is covered with the binder component. As a result, the inorganic nature of the inorganic filler is lost, and the curing filler-like function of the inorganic filler is inactivated.

  As is clear from the above description, according to the present invention, even when an inorganic filler is added, an adhesive (for example, an anisotropic conductive adhesive) that can maintain a usable period for a long time is provided. Is possible. Therefore, according to the present invention, the viscosity and the thermal expansion coefficient can be freely adjusted according to the use without being restricted by the blending of the inorganic filler, and an optimally designed adhesive can be provided.

Hereinafter, the configuration of the adhesive to which the present invention is applied will be described in detail.
The present invention basically covers all kinds of adhesives mainly composed of a binder component functioning as an adhesive and an inorganic filler added for the purpose of adjusting the viscosity and adjusting the thermal expansion coefficient. However, it is particularly suitable for application to an adhesive containing a latent curing agent. Examples of the adhesive containing the latent curing agent include an anisotropic conductive adhesive. In the case of an anisotropic conductive adhesive, it contains conductive particles in addition to the binder component, inorganic filler, and latent curing agent. The form of the adhesive is arbitrary such as liquid or film, but in the case of the anisotropic conductive adhesive, it is usually a film.

  The binder component used in the adhesive of the present invention may be any component as long as it has a site capable of reacting with a functional group of a silane coupling agent described later, and is used for this type of adhesive. Any known binder component can be used. Specific examples include an epoxy resin. The epoxy resin has a functional group (epoxy group) that can react with a functional group of the silane coupling agent such as an amino group, and contributes to the modification of the inorganic filler by combining with the silane coupling agent.

  In the adhesive using the epoxy resin or the like as described above as a binder component, the usable period (life) and thermal activity are both achieved by the latent curing agent. The adhesive of the present invention may also contain such a latent curing agent. Examples of such latent curing agents include imidazole-based curing agents and amine-based curing agents that correspond to epoxy resins. These latent curing agents may be latentized by microencapsulation.

On the other hand, as the inorganic filler, an inorganic filler of any material can be used according to a desired purpose such as adjustment of viscosity and adjustment of thermal expansion coefficient. Specifically, alumina (Al ₂ O ₃ ), mullite (Al ₂ O ₃ —SiO ₃ ), silica (SiO ₂ ), or the like. Among these inorganic fillers, when an inorganic filler containing Al is used, the effect of the present invention is great.

  In addition, when an adhesive for electric circuit connection, particularly an anisotropic conductive adhesive, contains conductive particles in the adhesive. In this case, the conductive particles used may be a conventional anisotropic conductive adhesive. Any of those having the same structure as that used in the agent can be used. Examples of such conductive particles include solder particles, nickel particles, metal (nickel, gold, etc.) plating-coated resin particles, and particles obtained by insulating coating these. Among these, gold-plated coated resin particles having good connection reliability are preferable.

  If the average particle diameter of the conductive particles used is too small, the conduction reliability is lowered, and if it is too large, the insulation reliability is lowered. Therefore, the average particle diameter is preferably 2 to 6 μm. If the blending amount of the conductive particles in the anisotropic conductive adhesive is too small, the connection reliability is lowered. If the blending amount is too large, the insulation reliability is lowered, and therefore it is preferably 1 to 10% by volume.

  In the adhesive of the present invention, various additives such as a surfactant can be blended as necessary. Moreover, the adhesive of this invention can be easily manufactured by disperse | distributing an inorganic filler and also electroconductive particle etc. uniformly in a binder component by a conventional method.

  The above is the basic composition of the adhesive. In the present invention, the surface of the inorganic filler is modified with a specific silane coupling agent to improve the usable period.

  Here, the specific silane coupling agent is a silane coupling agent having a functional group capable of reacting with the binder component. Examples of the functional group capable of reacting with the binder component include a functional group having a nitrogen atom N and a hydrogen atom (active hydrogen H) bonded to the nitrogen atom, and specifically include an amino group or an isocyanate group. It is. Moreover, it is preferable that the said silane coupling agent has the said functional group 2 or more, Therefore, a diaminosilane coupling agent, a triaminosilane coupling agent, etc. are suitable as said specific silane coupling agent.

（５）Ｈ_２ＮＣＯＮＨＣ_３Ｈ_６Ｓｉ（ＯＣ_２Ｈ_５）_３：日本ユニカー社製、商品名Ａ１１６０
（６）Ｈ_２ＮＣ_２Ｈ_４ＮＨＣ_２Ｈ_４ＮＨＣ_３Ｈ_６Ｓｉ（ＯＣＨ_３）_３：日本ユニカー社製、商品名Ａ１１３０
等である。 Examples of usable silane coupling agents include aminosilane coupling agents such as:
_{(1) H 2 NC 3 H} 6 Si (OC 2 H 5) 3: Nippon Unicar Co., Ltd., trade name A1100
_{(2) H 2 NC 3 H} 6 Si (OCH 3) 3: Nippon Unicar Co., Ltd., trade name A1110
(3) H ₂ NC ₂ H ₄ NHC ₃ H ₆ Si (OCH ₃ ) ₃ : Nippon Unicar Company Limited, trade name A1120

(5) H ₂ NCONHC ₃ H ₆ Si (OC ₂ H ₅ ) ₃ : Nippon Unicar Company Limited, trade name A1160
_{(6) H 2 NC 2 H} 4 NHC 2 H 4 NHC 3 H 6 Si (OCH 3) 3: Nippon Unicar Co., Ltd., trade name A1130
Etc.

As a silane coupling agent having an isocyanate group, for example,
(1) O = C = NC ₃ H ₆ Si (OC ₂ H ₅ ) ₃ : Nippon Unicar Company Limited, trade name A1310
_{(2) O = C = NC} 3 H 6 Si (OCH 3) 3: manufactured by Nippon Unicar Company Limited, trade name Y-5187
Etc.

  The surface of the inorganic filler is modified by the above-mentioned silane coupling agent, and as a method thereof, a method of blending simultaneously with a binder component or an inorganic filler, an integral blend method of mixing together with the inorganic filler in a solution, A method of adding a binder component after dispersing an inorganic filler in an organic solvent in advance and surface-treating with a silane coupling agent may be used. Experiments were conducted by changing the method of adding the organic solvent, the inorganic filler, the silane coupling agent, and the binder component (epoxy resin), and it was confirmed that any of the above methods had an effect of improving life.

Moreover, although it is the processing amount of a silane coupling agent, the surface processing amount in a silane coupling agent is represented by the following formula.
Treatment amount of silane coupling agent (g)
= [Weight of inorganic filler (g) × Specific surface area of inorganic filler (m ² / g)] / [Minimum covering area of silane coupling agent (m ² / g)]

When the inorganic filler weight is about 40 g, the specific surface area of the inorganic filler is about 50 to 100 m ² / g, and the minimum covering area of the silane coupling agent is about 250 to 300 m ² / g, the optimum amount of the silane coupling agent is It becomes about 6 to 16 g per about 40 g of the inorganic filler. However, since a sufficient effect can be obtained even with a treatment amount of about 1 g per about 40 g of the inorganic filler, the treatment amount may be so small that 5 to 15% of the surface of the inorganic filler is covered.

  When the surface of the inorganic filler is modified by the above-described silane coupling agent, as shown in FIG. 1, the silane coupling agent binds to the OH group that is the active site of the inorganic filler A at the Si site, and the surface of the inorganic filler A To form the silane coupling agent layer B. At the same time, a functional group such as an amino group is bonded to the binder component, and the surface of the inorganic filler A is covered with the binder component C. FIG. 2 shows the state in detail. As shown in FIG. 2A, the aminosilane coupling agent B is adsorbed on the surface of the inorganic filler A, and the binder component (epoxy resin) C is shown in FIG. As shown in b), it binds to the amino group of the adsorbed silane coupling agent B.

  Thereby, the inorganic substance property of the inorganic filler A is lost, and the curing catalyst function of the inorganic filler A with respect to the binder component C and the latent curing agent is inactivated. As a result, the life of the adhesive is maintained for a long time.

  Hereinafter, specific examples of the present invention will be described based on experimental results.

Confirmation experiment of effect by kind of silane coupling agent Various silane coupling agents were added to the basic blend A shown in Table 1 to prepare anisotropic conductive adhesive films. In addition, the detail of each component in each basic compounding is as follows.
YP50: Phenoxy resin, HP4032D manufactured by Tohto Kasei Co., Ltd .: Epoxy resin, epoxy equivalent 136-150 g / eq, HP7200H manufactured by Dainippon Ink & Chemicals, Inc .: Epoxy resin, epoxy equivalent 265-300 g / eq, VH4170 manufactured by Dainippon Ink & Chemicals, Inc. : Phenolic resin, active hydrogen equivalent 118 g / eq, VH4150 manufactured by Dainippon Ink & Chemicals, Inc.: Phenolic resin, active hydrogen equivalent 118 g / eq, manufactured by Dainippon Ink & Chemicals Co., Ltd. HX3941HP: Epoxy-dispersed imidazole curing agent, manufactured by Asahi Kasei

  The anisotropic conductive adhesive film was produced as follows. First, a phenoxy resin and an epoxy resin were dissolved in a solvent and mixed to obtain a uniform solution. This is a blend. A silane coupling agent and an inorganic filler were added to this blend and dispersed uniformly with three rolls to obtain a dispersion. Conductive particles and a curing agent were blended into the obtained dispersion to obtain a basic blend. In order to promote the life of the basic blend, it was left at room temperature (25 ± 5 ° C.) for 5 hours. Thereafter, the basic blended product was applied to a release-treated polyethylene terephthalate (PET) film, dried at 80 ° C. for 5 minutes, and an anisotropic conductive adhesive film having a coating thickness of 40 μm (Examples 1 to 5 and Comparative Example 1). To Comparative Example 5).

ＡＺ６１７７：ｎ−Ｃ_６Ｈ_１３Ｓｉ（ＯＣＨ_３）_３（日本ユニカー社製） In addition, the kind of silane coupling agent used by each Example and the comparative example is as follows.
A1130: Aminosilane coupling agent (6)
A1120: Aminosilane coupling agent (3)
A1100: Aminosilane coupling agent (2)
A1110: Aminosilane coupling agent (1)
Y5187: Silane coupling agent having an isocyanate group (2)

_{AZ6177: n-C 6 H 13} Si (OCH 3) 3 ( manufactured by Nippon Unicar Co., Ltd.)

  Evaluation of the produced anisotropic conductive adhesive film was performed as follows. First, the calorific value was measured by differential scanning calorimetry (DSC), and this was used as the initial value. Next, the produced anisotropic conductive adhesive film was cut into 5 cm × 5 cm, left in a heating oven at 55 ° C. for 24 hours, and then the calorific value was measured by DSC (DSC Life-1). Furthermore, the produced anisotropically conductive adhesive film was cut into 5 cm × 5 cm, left in a heating oven at 55 ° C. for 200 hours, and then the calorific value was measured by DSC (DSC Life-2). DSC life-1 / initial value (%) and DSC life-2 / initial value (%) are calculated, ◎ when the calculated value is 95% or more, ◯ when the calculated value is less than 95% and 90% or more, The case of less than 90% and 80% or more was evaluated as Δ, and the case of less than 80% was evaluated as ×. The results are shown in Table 2. The initial value was 155 mJ / mg.

  As is apparent from Table 2, the life is improved only when an aminosilane coupling agent or a silane coupling agent having an isocyanate group is used. In particular, when an aminosilane coupling agent is used, the effect is remarkable.

Confirmation experiment of influence by kind of inorganic filler A silane coupling agent was added to basic blends B and C shown in Table 3, and anisotropic conductive adhesive films (Examples 6 and 7 and Comparative Examples 6 and 7) were produced. . In the basic blends B and C, the kind of the inorganic filler is different from the basic blend A.

  These anisotropic conductive adhesive films were similarly evaluated. The results are shown in Table 4. The initial value was 155 mJ / mg.

  As apparent from Table 4, it was confirmed that the life was improved by using the silane coupling agent regardless of the kind of the inorganic filler.

Confirmation experiment of influence by binder component A silane coupling agent was added to basic blends D and E shown in Table 5 to prepare anisotropic conductive adhesive films (Examples 8 and 9 and Comparative Examples 8 and 9). In the basic blends D and E, the epoxy resin differs from the basic blends A and C.

  These anisotropic conductive adhesive films were similarly evaluated. The results are shown in Table 6. The initial value was 115 mJ / mg.

  As apparent from Table 6, it was confirmed that the life was improved by using the silane coupling agent regardless of the kind of the binder component or the inorganic filler.

It is sectional drawing which shows typically the inorganic filler of the state surface-treated with the silane coupling agent. It is a figure which shows the detail of the inorganic filler of the state surface-treated with the silane coupling agent, (a) shows the adsorption state of a silane coupling agent, (b) shows the bonding state of an epoxy resin.

Explanation of symbols

A inorganic filler, B silane coupling agent, C binder component (epoxy resin)

Claims (7)

An adhesive containing a binder component, a curing agent and an inorganic filler, and containing a silane coupling agent having a functional group capable of reacting with the binder component,
The binder component contains an epoxy resin,
The silane coupling agent is a diaminosilane coupling agent or a triaminosilane coupling agent,
The inorganic filler contains Al and is surface-treated with 15 to 40% by weight of the silane coupling agent with respect to its weight .   The adhesive according to claim 1 is used for electrical circuit connection.   The said adhesive agent of Claim 1 contains electroconductive particle, The adhesive agent characterized by the above-mentioned.   The adhesive according to claim 1 is anisotropically conductive.   The adhesive according to claim 1 is in the form of a sheet. It is the manufacturing method of the said adhesive agent of Claim 1 , Comprising: After surface-treating with the said silane coupling agent which has the said functional group which can react with the said binder component of 15-40 weight% with respect to the said inorganic filler , The manufacturing method of the adhesive agent characterized by adding the said binder component. It is the manufacturing method of the said adhesive agent of Claim 3 or 4, Comprising: An epoxy resin is melt | dissolved in a solvent, a formulation is obtained as a uniform solution , 15-15- with respect to the said inorganic filler and the said inorganic filler in the said formulation. A method for producing an adhesive , wherein 40% by weight of the silane coupling agent is added and dispersed to obtain a dispersion, and the dispersion is mixed with conductive particles and a curing agent.

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