JPH08218050A - Epoxy-based adhesive composition - Google Patents

Abstract

PURPOSE: To obtain a composition extremely low in viscosity variation among respective production lots and viscosity-rising rate with time, useful as the chief agent of epoxy adhesives, by blending an epoxy resin with an inorganic filler and inorganic moisture absorbent in specified proportions. CONSTITUTION: This composition is obtained by blending (A) 100 pts.wt. of an epoxy resin with (B) 50-300 (pref. 100-200) pts.wt. of an inorganic filler consisting of calcium carbonate pref. 1-100μin average particle size and (C) 5-100 (pref. 10-50) pts.wt. of an inorganic moisture absorbent consisting of lime pref. <=100μ in particle size. For curing this composition, a curing agent such as amine or polyamide resin is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition which is used as a main component of an epoxy adhesive and has excellent viscosity stability during storage.

[0002]

2. Description of the Related Art Conventionally, two-component room temperature curing type epoxy adhesives used for bonding industrial materials such as metal decorative plywood, plastic decorative plywood, metal composite plates, honeycomb sandwich panels, etc. From the viewpoint of heat resistance, viscosity adjustment and economy, calcium carbonate, kaolin clay,
Inorganic fillers such as talc and titanium oxide were blended.

[0003]

An epoxy adhesive composition (hereinafter, simply referred to as an adhesive composition) in which an epoxy resin is mixed with an inorganic filler, which is used as a main component of a two-component room temperature curing type epoxy adhesive. In the case of (), there was a problem in that the dispersion of the viscosity at the time of production and the viscosity increased with time, and in some cases, the gelling state became difficult to apply. When the cause of this was examined, it was found that the water content in the inorganic filler markedly changed the viscosity during production and the viscosity with time. That is, the one produced in the rainy season showed a water content of 1.0% or more as measured by the Karl Fischer method, and the main ingredient using this had a high viscosity at the time of production,
Moreover, the viscosity changes significantly with time, and 0.1% by heat treatment
It was found that the one using the inorganic filler adjusted to have a water content of a certain degree has a low viscosity during production and has a slight change over time. However, the water content of inorganic fillers, which are natural products, is not constant throughout the year, and it is inevitable that the water content of the hot and humid summer is 5 to 10 times that of the winter. High water content fillers can be reduced by heating or vacuum heat treatment, but require expensive drying equipment.

[0004]

Means for Solving the Problems As a result of intensive studies, the inventors of the present invention have studied as a means for reducing a change in viscosity of an adhesive agent, which can be easily manufactured without being affected by the water content of an inorganic filler. The inventors have found that the combined use of the agents is the most effective and also have a great effect from the economical aspect, and have completed the present invention. That is, the present invention is: 1. An epoxy adhesive composition obtained by mixing 50 to 300 parts by weight of an inorganic filler and 5 to 100 parts by weight of an inorganic moisture absorbent with 100 parts by weight of an epoxy resin. 1. The inorganic hygroscopic agent is a powder or particles. The epoxy-based adhesive composition described above.

Epoxy resins are bisphenol type, chain type epoxy resin type, dimer acid type diglycidyl ester type,
Polyalkylene ether type, novolac type epoxy resin type, cycloaliphatic epoxy resin type, brominated epoxy type, polyglycidyl ether type, diglycidyl ester type, diglycidyl amine type, polymer type epoxy resin type, and the like. The most general-purpose liquid bisphenol system having a medium epoxy equivalent of 170 to 200 and a viscosity of 14 to 700 poise / 25 ° C. is preferable.

Examples of the inorganic filler include calcium carbonate, kaolin clay, titanium oxide, silica sand, magnesium oxide, talc, slate powder, etc. Calcium carbonate is preferred from the economical viewpoint, and the average particle size usually used is 1 to 1. 100
It is a relatively small value of μ. The amount of the inorganic filler compounded is in the range of 50 to 300 parts by weight, preferably 100 to 200 parts by weight, based on 100 parts by weight of the epoxy resin. If it is less than 50 parts by weight, heat resistance and economical efficiency will be problematic, and if it exceeds 300 parts, the viscosity will be remarkably high and the coating properties will be impaired, and the adhesive strength will also be reduced.

Examples of the inorganic hygroscopic agent include quick lime, silica gel, zeolite and other powders or particles. The most preferable of these is quick lime, which has a high hygroscopic effect, and because quick lime reacts with water to transform into calcium hydroxide, and further reacts with carbon dioxide in the air to transform into calcium carbonate used as a filler. Most convenient. By the way, when using a granular material, it is preferable that the particle size is 100 μm or less, and if it exceeds 100 μm, the uniform coating property of the adhesive is hindered.

The blending amount of the inorganic hygroscopic agent is epoxy resin 10
It is in the range of 5 to 100 parts by weight, preferably 10 to 50 parts by weight, relative to 0 parts by weight. If the amount is less than 5 parts by weight, the viscosity at the time of production using an inorganic filler having a high water content and the viscosity cannot be stabilized over time, and if it exceeds 100 parts by weight, the viscosity becomes high and the coatability is impaired. If necessary, the adhesive composition of the present invention may contain a dispersant, a colorant, a plasticizer, an organic solvent, a silane coupling agent and the like in combination within a range that does not hinder the adhesive performance.

To cure the adhesive composition of the present invention, a curing agent represented by amine, polyamide resin and the like is used. In actual blending, it is preferable to use calcium carbonate as an inorganic filler in such an amount that the blending ratio of the main agent and the curing agent becomes 1: 1 by weight based on the epoxy equivalent.

The adhesive composition of the present invention has a very small variation in the viscosity at the time of production for each production lot and an extremely low rate of increase in viscosity with the passage of time. Therefore, the adhesive composition is excellent in viscosity stability without providing an expensive drying facility. An epoxy adhesive is obtained, which is a very useful adhesive composition.

[0011]

The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited thereto.
Further, unless otherwise specified, parts represent parts by weight.

Examples 1 to 5 and Comparative Examples 1 to 2 Epoxy resins in the proportions shown in Table 1 (Yukaka Shell Co., Ltd.)
Manufactured, trade name Epikote 828, viscosity 120-150 poise / 25 ° C, epoxy equivalent 184-194) is placed in a 1-liter poly container and stirred with a turbine stirrer.
Quick lime (made by Maruo Calcium Co., Ltd., as an inorganic moisture absorbent,
Powdered quick lime, average particle size 5 μ) was mixed, and then calcium carbonate (manufactured by Nitto Koka Kogyo Co., Ltd., trade name NS-100, average particle size 2 to 3 μ) was mixed as an inorganic filler, and the adhesion of the present invention was added. An agent composition was obtained. The viscosity of the adhesive composition immediately after its production and the viscosity after leaving it in a thermostatic bath at 35 ° C. for a predetermined time were measured with a BH type rotational viscometer at a liquid temperature of 25 ° C. and shown in Table 1.

[0013]

[Table 1]

[0014]

As is clear from Table 1, the viscosity of the adhesive composition of the present invention is such that the water content in the inorganic filler is absorbed by the chemical reaction of the inorganic hygroscopic agent during the production. There is little variation in viscosity without being affected by, and the change in viscosity is extremely small even with the passage of time. Therefore, a stable epoxy adhesive can be obtained without providing expensive drying equipment,
Practical value is extremely high.

Claims (2)

[Claims] 1. An inorganic filler of 50 to 300 parts by weight and an inorganic hygroscopic agent of 5 to 100 relative to 100 parts by weight of an epoxy resin.
An epoxy adhesive composition containing 1 part by weight. 2. The epoxy adhesive composition according to claim 1, wherein the inorganic hygroscopic agent is a powder or particles.