JPH04173331A - Preparation of sandwich-structural panel - Google Patents

Abstract

PURPOSE:To obtain a sandwich-structural panel within a short time by simple bonding work using a specific one-pack type moisture-curable urethane adhesive in the bonding of surface materials and a core material. CONSTITUTION:In preparing a sandwich-structural panel by using a weighed base material as a core material and bonding surface plates to the core material, an one- pack type moisture-curable urethane adhesive containing 0.1-6wt.% of isocyanate as the solid conversion value of an entire adhesive also compounded with various additives, having a mean MW of 8000-50000 and showing heat activity at 70 deg.C or higher is applied to the single surfaces of the surface plates and the surface plates are pressed to the core material for several sec by a heating press and for several sec by a cooling press to be bonded thereto. When a prepolymer whose mean MW is less than 8000-50000 is applied, it runs off without being sufficiently bonded and, when the prepolymer whose mean MW is more than 8000-50000 is applied, coating workability is bad because of high solution viscosity and low solid content. When isocyanate content is less than 1-6wt.% as the solid conversion value in the entire adhesive, sufficient crosslinking curing is not performed and, when said content is larger than 1-6wt.%, sufficient curing is not performed only by the moisture in the base material.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to the production of sandwich structures by short-time pressing with single-sided application of a special one-component moisture-curing urethane adhesive.

<Prior Art and Problems> Sandwich structure panels have high strength, excellent dimensional stability, and heat insulation and soundproofing functions, so they are widely used for house frames, indoor partition panels, blackboards, etc. Traditionally, sandwich structures have been manufactured using honeycomb, plasterboard, etc. as the core material, and various surface plates (plywood, painted steel plate, surface-treated steel plate, plastic plate, aluminum alloy plate, etc.).
are manufactured by bonding them together with adhesive at a factory. The adhesives used include epoxy resin type, chlorobrene solvent type or latex type, vinyl acetate type solvent type or emulsion type, hot melt type, and urethane resin type. Among these, the chloroprene solvent type requires coating on both surfaces of the surface material, core material, and frame material in order to achieve contact adhesion, and also has the disadvantage that it cannot be smoothed after lamination. . Additionally, hot melt systems require a special applicator and have problems with heat resistance. Furthermore, adhesives such as epoxy, vinyl acetate, and urethane adhesives that take time to harden (solidify) require a long press process, which takes a long time to manufacture, resulting in poor production efficiency.

<Object of the Invention> An object of the present invention is to provide a method for manufacturing a sandwich structure panel in which the work of adhering the surface material and the core material is simple and can be manufactured in a short time.

<Disclosure of the Invention> The gist of the present invention is as described above, and the core material and the surface plate are the well-known conventional products as described above. The one-component moisture-curing urethane adhesive used as an adhesive contains an excessive amount of polyisocyanate compounds (diphenylmethane diisocyanate, dimethyldiphenylmethane diisocyanate, cyclohexylmethane diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, xylene diisocyanate, p-phenylene diisocyanate, etc.). and one or more polyols (polyoxyalkylene ether polyols, polyester polyols, acrylic polyols, butadiene polyols, castor oil derivatives, etc.) having two or more (preferably 2 to 3) active hydrogens in one molecule. Select and use these 6 as appropriate.
The main component is a urethane prepolymer obtained by reacting for several hours under heating at 0 to 100°C, and if necessary, ordinary additives such as plasticizers (DBP, DOP, etc.), tackifiers (alkylphenol resins) are added. , ketone resins, rosin, petroleum resins, etc.), chlorinated olefins (chlorinated polyethylene, chlorinated polypropylene, chlorinated rubber, etc.), adhesion agents (silane compounds such as aminosilane, vinylsilane, organic titanate compounds), solvents (toluene, xylene, esters, ketones, chlorine, etc.), catalysts (dibutyltin dilaurate, dibutyltin dioctate, tin octoate, dioctyltin dilaurate, dimethylcyclohexylamine, tributylamine, triethylenediamine, dimethylbenzylamine, etc.), etc. Consists of a blended system.

Next, the one-component moisture-curable urethane adhesive is a prepolymer of polyol and isocyanate with an average molecular weight of 8,000 to 50o○0, and prepolymers with a smaller molecular weight than this are sufficient when applied. They tend to drip without adhesion, and large ones have high solution viscosity and low solid content, making coating workability poor. In addition, the isocyanate content is 1 to 6% by weight in terms of solid content in the total adhesive.
If the amount is smaller than this, sufficient crosslinking and curing will occur, but if the amount is larger than this, the moisture in the equipment alone will not sufficiently cure the resin. It is also required to be thermally activated, preferably softened at a temperature of 70° C. or higher, and to have the ability to adhere to the side to which the adhesive is not applied. In addition, as for the properties, the solid content is 25
% or more, and diluted with an organic solvent to have a viscosity of 1000 cps/25°C or less, it is acceptable in terms of spray coating performance.

Next, the adhesive is applied to the top plate using a spray device. In addition, adhesive is applied to the periphery of the surface plate, and after forced drying, it is heat-activated using a heat press.
This is an adhesion method in which fusion is performed and solidification is performed using a cold press.

<Effects of the Invention> The adhesive used in the present invention is a one-component type that is cured by the reaction between active isocyanate groups and moisture in the air, so it is not necessary to mix the main ingredient and curing agent like conventional epoxy resin adhesives. The work is easy as there is no need to do so.

Furthermore, since an adhesive having specific properties as described above is used, the manufacturing apparatus can be simplified and the manufacturing process can be carried out in a short period of time by coating on one side and pressing for a short period of time.

This will be explained by the following example.

Example 1 When bonding a 25 m/m thick honeycomb core between 1.2 m/m thick steel plates, the solid content was 36% and the viscosity was 3.
50 c p s / 25 °C, isocyanate content O,S wt%, average molecular weight 45000, thermal activation temperature 70
Aika Aibon W-651 (manufactured by Aikanigyo Co., Ltd.), a one-component moisture-curing urethane adhesive at °C, was applied to the steel plate surface using an airless spray at approximately 150 g/n ((solid content equivalent value: approximately 549/r+( ) After coating and drying, hot press 9
Bonding was carried out at 0° C. and 2 kgf/cnl for 2 seconds, and then by cold press 2 at 9 f/all for 5 seconds.

Comparative Example 1 The same base material as in Example 1 was coated with 250 g/rrt of Aika Aibon RC-ET (manufactured by Aikani Gyo Co., Ltd.), which is a solvent-based chloroprene adhesive, on both sides.
After drying, it was pressed and bonded using a pinch roll (I! pressure 5 to 9 f).

Comparative Example 2 The adhesive was applied to the same base material as in Example 1 using hot melt Aikamelt HX-604 (manufactured by Aikanigyo Co., Ltd.).
Sandwich the sheet type between the base materials and hot press at 150℃.
Bonding was performed at 13 kgf/ant for 3 minutes.

Comparative Example 3 Using the same base material as in Example 1, a two-component poxy adhesive, Aika Aibon E-5320 (manufactured by Aikani Gyo Co., Ltd.), was applied to the steel plate side at 25o9/product. kg
/ crA, pressure was applied for 18 hours and bonded.

Next, the normal strength and hot strength (80°C) of the adhesive processed products obtained in Example 1 and Comparative Example 1.2.3 were determined by JIs A-5.
Table 1 shows the results measured by the test and adhesion method specified in 536.

Table 1 Patent applicant: Aikanigyo Co., Ltd.

Claims (1)

[Claims] When manufacturing a sandwich structure panel consisting of a lightweight base material as a core material and a surface plate adhered to it, the isocyanate content is 0.1 to 0.1 in terms of solid content in the total adhesive that also contains various additives. 6% by weight, average molecular weight 8000-50
000 and which is thermally active at 70°C or higher, is coated on one side with a one-component moisture-curing urethane adhesive, and the sandwich structure panel is bonded using a hot press for several seconds and a cold press for several seconds. Production method.