JPS629606B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a paste composition for obtaining a cured coating film with excellent workability and heat resistance. That is, powdered polyamino bismaleimide resin and/or novolac type phenolic resin obtained from 4,4'-diaminodiphenylmethane and bismaleimide, which are reactive with epoxy resins and have a melting point of 150°C or lower in the resin state. A paste in which the resin is uniformly dispersed in powder form in an epoxy resin that is liquid at room temperature, or an epoxy resin solution that is dissolved in a solvent that is a poor solvent for heat-resistant resins and a good solvent for epoxy resins. The present invention relates to a type of composition.

Conventionally, as a coating agent for obtaining a cured coating film of epoxy resin type with excellent heat resistance, it is necessary to dissolve both the epoxy resin and the heat-resistant resin that is reactive with the epoxy resin in a solvent that is a good solvent for both. It is common to use the resulting homogeneous solution or paste. However, although the varnish or paste obtained in this manner is widely used, it has the following drawbacks. That is, (1) The solvent must be a good solvent for both resins, so there are significant restrictions on the solvent.

In particular, a special solvent is required to dissolve heat-resistant resins. For example, in the case of polyamino bismaleimide (a product obtained from bismaleimide and 4,4'-diaminodiphenylmethane), a high boiling point solvent such as N-methylpyrrolidone must be used as a good solvent, and the final solvent Removal requires high temperatures, which causes some of the reaction to proceed, making it extremely difficult to control the curing reaction, and since it is a dangerous solvent, there are safety issues, and it is expensive. be.

(2) Since both resins are completely dissolved, resulting in molecular dispersion, they tend to react, have poor storage stability, and have to be mixed before use, resulting in very poor work efficiency.

(3) Heat-resistant resin, which is a relatively high molecular weight substance, exhibits high viscosity when dissolved, so a large amount of solvent must be used. For this reason, a thick coating film cannot be obtained.

(4) Since it is a high boiling point solvent, high temperatures are required to remove the solvent, resulting in large energy consumption.

etc. The present inventors carried out extensive studies to overcome the drawbacks of these conventional resin systems and arrived at the present invention. That is, polyamino bismaleimide resin and/or
Alternatively, we have discovered a method of dispersing the novolak type phenolic resin in a powdered state without dissolving it. Conventionally, a technique of dispersing a non-reactive filler in a resin system is generally used.
However, the idea of dispersing a reactive resin in a liquid resin or a resin solution using exactly the same method as filler dispersion has hitherto never been considered. This made it possible to overcome all of the above drawbacks. That is, (1) it is not necessary to dissolve the polyamino bismaleimide resin and/or the novolak type phenol resin, and therefore no special solvent is required.

(2) Since it is a powder dispersion of polyamino bismaleimide resin and/or novolac-type phenolic resin, the probability of contact with epoxy resin molecules is reduced, and storage stability can be greatly improved.

(3) Since it is a powder dispersion, there is no increase in viscosity. Therefore, a highly concentrated resin paste is obtained. When liquid epoxy is used, a solvent-free paste can also be obtained.

(4) Since high-boiling point solvents are not required, solvent removal can be performed at low temperatures, resulting in energy savings.

etc. Further, since a polyamino bismaleimide resin and/or a novolak type phenol resin having a melting point of 150° C. or lower is used, the resin powder melts upon heating and causes a crosslinking reaction with the epoxy resin. Since these resins have good compatibility with each other, a uniform reaction system is formed. Therefore, a uniform cured product is obtained without layer separation, and the physical properties of the cured product are no different from those using a complete solution.

The details of the present invention will be described below.

The particle size of the powdered resin used in the present invention is preferably as fine as possible from the viewpoint of dispersibility. Such resins include polyamino bismaleimide resins and/or novolac type phenolic resins, and polyamino bismaleimide resins are particularly preferred. In addition, if the melting point of the resin used in the present invention is 150°C or higher, in order to achieve mixed melting with the epoxy resin after removing the solvent,
Since a temperature of 150°C or higher is required, it becomes difficult to control the reaction.

These powdered resins can be dispersed as is if the epoxy resin is in a liquid state, or in a solution prepared by dissolving it in an arbitrary solvent if the epoxy resin is solid at room temperature. Various methods are used for dispersion, but
Ball mill mixing, colloid mill mixing, and triple ink roll mixing are common, and ink roll mixing is particularly preferred for the purpose of achieving uniform dispersion in a short time.

Furthermore, if necessary, fillers, thixotropic agents, reaction accelerators, pigments, surfactants, flame retardants, and the like may be optionally mixed.

Furthermore, when using a solvent, it is possible in principle to use any solvent that can dissolve the epoxy resin.
When applying the paste of the present invention to various coating applications, carbitols such as ethyl carbitol and butyl carbitol are generally preferred because they have appropriate volatility.

The pastes obtained in this way are excellent as coating agents, and after coating various substrates and removing the solvent by drying, the Crosslink and cure at high temperature. The resulting coating film is uniform and has excellent heat resistance.

Furthermore, it is also possible to obtain a heat-resistant laminate by coating it on a glass cloth or the like, drying it, and then heat-pressing it.

Examples are shown below.

Example 1 30 parts by weight of bisphenol-type liquid epoxy resin (manufactured by Ciel Corporation, Epicoat 828), 70 parts by weight of polyamino bismaleimide resin powder (manufactured by Mitsui Petrochemicals, Ltd., Kelimide 601) The above mixture was kneaded using three ink rolls. Got the paste. The obtained paste was applied onto an alumina substrate to a thickness of 100 μm using an applicator. Then put it in the dryer set at 170℃ for 2 hours.
It was heated and cured for a period of time. The obtained cured coating film was a uniform coating film with a smooth surface, and when a varnish obtained by dissolving the composition with the above blending ratio in 100 parts by weight of N-methylpyrrolidone was used (curing temperature
The coating film was comparable in comparison to the coating film prepared at 250°C for 1 hour).

Further, while it took 7 hours for the viscosity at 25°C of the varnish used in the comparative example to double the initial viscosity, it took 1 week for the composition of Example 1.

Example 2 Bisphenol type epoxy resin (manufactured by Ciel Corporation,
Epicote 1001) 40 parts by weight of butyl carbitol
It was dissolved in 50 parts by weight.

Next, 60 parts by weight of polyamino bismaleimide resin powder and fine powdered silica were added to this system as in Example 1.
0.5 parts by weight and 3 parts by weight of pigment (cyanine blue) were mixed. Thereafter, kneading was performed using three ink rolls to obtain a paste composition. The paste obtained was a screen printable paste.
The resulting paste was selectively printed on desired areas on a polyimide circuit board on which a copper foil circuit was fabricated. After printing, it was cured at 170°C for 2 hours to form an excellent solder resist layer, and no defects occurred even when immersed in a 300°C solder bath for 10 seconds.

Example 3 The paste obtained in Example 2 was coated on a glass cloth using a doctor knife, and
A prepreg was obtained by heating at ℃ for 1 hour. The obtained prepreg was heated and pressurized (170℃, 60℃
Kg/cm ² , 2 hours), a laminate with excellent heat resistance was obtained.

Claims (1)

[Claims] 1 Melting point that has crosslinking reactivity with epoxy resin
Powdered resin of polyamino bismaleimide resin obtained from 4,4'-diaminodiphenylmethane and bismaleimide and/or novolac type phenolic resin at 150°C or less, liquid epoxy resin or epoxy resin, and a solvent capable of dissolving the same. A paste-like composition characterized in that the powdered resin is uniformly dispersed as a powder without being dissolved in an epoxy resin system by kneading a liquid mixture with a solvent that is a poor solvent for the powdered resin. .