JPH02258243A - Manufacture of panel of honeycomb sandwich structure - Google Patents

Abstract

PURPOSE:To improve the working efficiency such as workability of conveyance and superposition on a surface sheet, lowering of a temperature of a heating press and shortening of a heating period of time, by a method wherein sticking is performed with the heating press by making use of a moisture setting urethane hot melt adhesive agent which is nonadhesive at the normal temperature. CONSTITUTION:A moisture-setting urethane hot melt adhesive agent which is free from adhesion at the normal temperature is selected appropriately so that physical property values setting up a polyisocyanate compound and at least one or two kinds of polyol possessing at least one preferably 2-3 pieces of active hydrogen within one molecule are obtained. Then the moisture-setting urethane hot melt adhesive agent consists mainly of a urethane prepolymer obtainable by reacting for several hours under heating by deciding a compounding ratio. Although a roll coater method is good as a coating method, a spraying method also is adopted in some cases. Since the same is of a hot melt properties, the same is thickened suddenly through cooling from directly after coating, loses flowability, remains on the surface of a honeycomb and does not drop on an unnecessary part. The same is solidified in a several seconds to several minutes and becomes nonadhesive properties. The coated honeycomb is conveyed to a site where superposing work is performed with a roller conveyor or a hanger conveyer and heat-pressed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing honeycomb sandwich construction panels. More specifically, the present invention relates to a method for manufacturing a sandwich structure panel in which a surface plate is heat bonded using a moisture-curing urethane hot melt adhesive that is non-tacky at room temperature.

(Description of Prior Art) Honeycomb sandwich structure panels are lightweight and have excellent strength, heat insulation, and soundproofing functions, so they are used as building materials such as indoor and outdoor partitions, doors, furniture, blackboards, and housings for office equipment. It is widely used. Its structure uses a so-called honeycomb sheet as a core material, which is a rolled core made by forming paper, plastic sheet, or metal foil into a complex shape other than a honeycomb shape or a hexagonal shape. It is manufactured by bonding a surface plate, for example, a metal plate, a plastic plate, or a wood plate.

The adhesive is applied to either the honeycomb core side or the surface plate side, or both. As the coating method, spray and roll coater methods are usually adopted.

Typical adhesives used for this have traditionally been solution-based adhesives such as chloroprene, but they do not cause pollution due to solvents.
and there is a risk of fire outbreak.

Adhesives that do not have these drawbacks include hot melt adhesives whose main components are ethylene-vinegar copolymer and styrene-butadiene-styrene copolymer. However, this adhesive requires a high temperature of 140 to 200 degrees Celsius during application and bonding, and because it is essentially thermoplastic, its heat resistance as a sandwich structure panel is insufficient at 60 to 80 degrees Celsius.
The adhesion strength rapidly decreases, and the material failure of the honeycomb, which is required in the case of paper honeycombs, cannot be achieved.

So-called moisture-curing adhesives and thermosetting adhesives such as various types of adhesives such as one-component urethane adhesives, two-component urethane adhesives, and epoxy adhesives, which are liquid at room temperature, have been proposed as durable adhesives. has been done.

Since these are liquid at room temperature, the coating equipment can be as inexpensive as chloroprene adhesives, but on the other hand, they are very difficult to handle after coating. That is, after applying the adhesive to both sides of the honeycomb core, the adhesive on the lower side adheres to the working equipment, which requires time to clean.

Usually, it is held using a pin-shaped support and transported to the work site where it will be overlapped with the surface plate in the next process, but it is unstable and may fall or vibrate during transportation, resulting in accuracy in the positioning of the overlay. It is difficult and time consuming to correct the problem due to the stickiness.

These points are major obstacles to streamlining and automating coating and bonding operations.

Furthermore, in order to cure thermosetting adhesives, heat pressing is performed to shorten the time, but usually it is done at 100°C or higher in 1 to 2 minutes to complete the process in 4 to 5 minutes. requires a temperature of 140°C or higher.

Pressing at a high temperature inevitably requires an extended cooling time, softens the surface of the surface material, and tends to cause loss of embossing and change in gloss.

For this reason, when the surface plate is used for a plastic plate, a painted metal plate, and especially a PVC steel plate, the curing process must be performed at a low temperature of 100''C or less, which requires a long time for curing and reduces work efficiency.

(Problems to be Solved by the Invention) Therefore, as a result of intensive efforts and repeated research, the present invention has achieved the above-mentioned results by using a moisture-curing urethane-based hot melt adhesive that is not sticky at room temperature as an adhesive. This product has made it possible to solve all of the numerous problems.It has extremely good transport workability after hot application to the honeycomb and workability of overlaying it with the surface plate, and lowers the temperature of the hot press and shortens the time. The present invention provides an innovative method for manufacturing a honeycomb sandwich structure panel that achieves the following and has higher heat resistance and durability than conventional techniques.

(Means for Solving Problem n) Moisture-curable urethane-based hot melt adhesive that is not sticky at room temperature and used in the present invention (hereinafter referred to as the adhesive of the present invention)
is a polyisocyanate compound (diphenylmethane diisocyanate, dimethylcyphelmethane diisocyanate, cyclohexylmethane diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate,
xylene diisocyanate, P-)22 diisocyanate, etc.) and one or more, preferably 2 to 3, per molecule.
In order to obtain physical property values that set one or more types of polyols (rubber-based polyols such as polyoxyalkylene ether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, etc., castor oil derivatives, etc.) having active hydrogen. The main component is a urethane prepolymer obtained by appropriately selecting and determining the blending ratio, and reacting them under heating at 60° C. to 130° C. for several hours.

If necessary, add conventional compounding agents such as thermoplastic polymers (polyurethane, ethylene copolymers, propylene copolymers, vinyl chloride copolymers, various rubbers, acrylic copolymers), tackifiers, etc. Resin (coumarone resin, ketone resin, styrene resin, modified styrene resin, terpene resin, modified terpene resin, hydrogenated petroleum resin, xylene resin, epoxy resin, various esterified rosins, etc.) Plasticizer (dioctyl phthalate, butyl benzyl phthalate) , dinonyl phthalate, diethylene glycol dibenzoate, alkyl polycyclic aromatic hydrocarbons, chlorinated paraffin, etc.), fillers (calcium carbonate, clay, talc, etc.), pigments, catalysts (dibutyltin dilaurate, dibutyltin dilaurate, dimethyl cyclohexylamine, dimethylbenzylamine), adhesion agents (silane compounds, etc.), chicken tropism agents, antioxidants,
It is composed of a system containing UV absorbers, etc.

In the synthesis of the above urethane prepolymer, the polyisocyanate compound and the polyol are
The reaction is carried out in a proportion larger than 100%, and the NCO groups in the resulting urethane prepolymer are usually set at 0.5 to 10% by weight.

Further, when preparing the adhesive of the present invention, the blending ratio of additives is usually 0 to 30 parts of thermoplastic polymer and 0 parts of tackifier resin to 100 parts of urethane prepolymer.
~100 parts, 0 to 10 parts of a plasticizer, 0 to 50 parts of a filler, and other compounding agents in appropriate amounts. These additives should be dehydrated and dehumidified in advance by heating and vacuum drying, etc., and mixed at 80°C to 130°C using a heatable mixer.
This is done while separating it from air by purging with nitrogen gas.

It is normal to mix all the ingredients, but for pot life and work efficiency, it is better to divide the ingredients into two or more parts and mix them using a mixer immediately before coating, or mix them using a roll coater. - etc. may be mixed on a coating machine.

(Function) The adhesive of the present invention is non-adhesive at room temperature, but in order to obtain this non-adhesive property, it is necessary to take into account the manufacturing equipment and workability, such as adhesive application workability, hot press temperature, time, etc. It is determined by comprehensively considering the characteristics, heat resistance, durability, and price of the panel.

The method is to first raise the melting point of the prepolymer to 40° C. or higher; in this case, non-stick properties can be achieved using the prepolymer alone without using any other additives.

Another method is to blend TG or materials with high melting points, such as thermoplastic polymers and tackifier resins, to lower the melting point of the compound to 40°C even if the melting point of the prepolymer is 40°C or lower.
There is also a method of making it non-adhesive by heating it to 0°C or higher.

The adhesive of the present invention prepared in this way has a viscosity suitable for application by heating.

That is, 1,000-50.0O at 90℃-140℃
OCPS level can be obtained.

In the case of the adhesive of the present invention, the required adhesive properties can be obtained only on the honeycomb core side, where the least amount of adhesive is required.

A roll coater method is preferred as the coating method, but a spray method may also be used in some cases.

Since it is hot-melt, it rapidly thickens and loses fluidity upon cooling immediately after application, stays on the honeycomb surface, and does not drip onto unnecessary areas.

In addition, it solidifies within a few seconds or minutes and becomes non-adhesive by simply allowing a short cooling time after applying the coating on one side.
It can be reversed and the other side can be coated continuously. Also,
It is also possible to coat both sides at the same time by holding it with a pin-like holder for a short distance (or time) after application.

The coated honeycomb is conveyed by a roller conveyor, hanger conveyor, etc. to a stacking work place and heated and pressed. A temperature slightly above the melting point is sufficient for this press, and the time required for adhesion to the surface material is 0.5 to 2.
A time of about 1 minute is sufficient, and then the press is cooled as it is to 40° C. or less, or it is transferred to another press exclusively for cooling and cooled. Although the adhesive is in an uncured state at this stage, it has sufficient strength to allow the resulting panel products to be stacked, packaged, and transported.

The curing of the adhesive progresses due to moisture in the air or moisture at the adhesive interface between the honeycomb and the surface plate.
When the panel is subjected to a destructive test in about 2 to 3 days during winter, sufficient adhesive strength can be obtained.

(Example) Next, the present invention will be specifically explained with reference to Examples.

Production example 1゜ (adhesive preparation) Polyester polyol whose main components are adipic acid and 1.4-butanediol (number of functional groups: 2.0, molecular weight: 4,000
0) 4,000g and diphenylmethane diisocyanate)
A urethane prepolymer (viscosity at 100°C, 10.0
OOCPS, active NCO group content 1.8% by weight) was obtained.

A moisture-curable urethane hot-melt adhesive was obtained by mixing 100 g of calcium carbonate and 1 g of dibutyltin dilaurate, which had been heat-dried in advance, with the entire amount of the obtained prepolymer.

This adhesive had a melting point of 65° C. and had no tackiness at room temperature.

Production example 2 (adhesive preparation) Polyethylene-propylene ether diol (molecular weight 1
000) 1.000g, hydrogenated polybutadiene diol (
1.000 g of molecular weight 1000) and 800 g of diphenylmethane diisocyanate were mixed and reacted at 80° C. for 2 hours with stirring to obtain a urethane prepolymer (NCO content 3.5%) in the form of a paste that was viscous at room temperature. This total amount is 1
Polystyrene-based petroleum resin (melting point 1
20℃) 800g and 0.5g of dibutyltin dilaurate
g and further mixed and stirred for 2 hours to obtain a moisture-curable urethane hot melt adhesive.

This adhesive had a viscosity of 7.0OOCPS at 100°C, a melting point of 50°C, and no tackiness at room temperature.

Example 1 Paper honeycomb core (thickness 25-1 width 900 m, length 1,
The adhesive of Production Example 1 was applied at 120° C. at 50 g/ry11 on one side of the 800 mm.

After 30 seconds, the other surface was coated in the same manner, and the work was completed without any problems.

Next, the coated honeycomb core was placed at a predetermined position on the coated steel plate, and another coated steel plate was placed on top of it, and a press adjusted to 80°C was used to weigh 0.5 kg//
The sample was heated and pressurized for 1 minute at a pressure of 0.5 kg/cs/cm, and then immediately cooled by applying a pressure of 0.5 kg/cs/ in a press through which cooling water was passed.

During this time, handling of the honeycomb core was easy due to its non-adhesive nature, and alignment was also easy. The peel strength of the sandwich structure panel at 20° C. immediately after being taken out from the cooling press was 0.8 kg/cn, and material failure of the honeycomb was partially included. The strength of this bond at 20℃ when left for one day under 20"C-65%RH is 1.5kg/cm.
As a result, the material of the honeycomb core was completely destroyed.

A similar test was conducted at 80℃, but the weight was 1.2kg/. This resulted in material failure on the entire surface of the honeycomb core.

(Note) Method for measuring peel strength: Cut the panel into 150m wide and 100mm long pieces, and remove the steel plates on both sides by 20mm. It was peeled off and bent at 90 degrees, both sides of this part were grasped, and the strength was measured by peeling it off at a speed of 200 mm/min using an autograph.

Example 2 A honeycomb sandwich structure panel was obtained using the same machine as Example 1, except that the adhesive of Production Example 2 was used as the adhesive and a PVC steel plate was used as the surface material.

Workability is good, with a temperature of 1.0 during bonding at 20°C immediately after.
kg/c+m, it was almost material failure of the honeycomb core,
1.5kg/cn or more after 1 day, 1.2 at 80℃
kg/am, material failure occurred over the entire surface of the honeycomb core.

Comparative Example Adhesive mainly composed of SBS (styrene-butadiene-styrene) (softening point 60°C 1180"C viscosity 20,
A panel was manufactured in the same manner as in Example-1 using 0OOCPS). As a result, a panel could be obtained at a coating temperature of 190°C and a heating press temperature of 170''C.

In this case, the honeycomb core coated with adhesive had good handling properties, but the cooling press required 3 minutes.

In addition, the peel strength of the obtained panel was as shown in Example-1 at 20°C.
The results were similar to those of
. This was cohesive failure of the adhesive.

(Effects of the present invention) As described above, the method for manufacturing a honeycomb sandwich structure panel of the present invention solves all the problems of the prior art related to this matter, and as a result, improves transport workability and stacking workability with the surface plate. In addition, it has become possible to provide an innovative honeycomb sandwich structure panel that can be formed at a lower heat press temperature and has significantly improved heat resistance and durability.

Above procedure amendment (method) % formula %! , Indication of the case 1999 Patent Application No. 78124 2 Title of the invention Method for manufacturing honeycomb sandwich structure panels Relationship with the case Patent applicant Address: 1-13 Uchikanda, Chiyoda-ku, Tokyo 101 No. 7 name FA! L↓Akina 67- Co., Ltd. Representative 4 Urana 4, Representative Address: 1-13-7 Uchikanda, Chiyoda-ku, Tokyo 101 HIuna 67-
Inside the company, ``Written WIJ (self-motivated) stating that matters in the specification are to be amended'' ``Correction of 2 and a half days from the left on page 1, line 3 of the specification.

Below Up

Claims (4)

[Claims] (1) When manufacturing a sandwich structure panel consisting of a honeycomb core as a core material and surface plates bonded to the top and bottom of the core, a moisture-curing urethane-based hot melt adhesive that is non-tacky at room temperature is used as the adhesive and heated. Method for manufacturing a honeycomb sandwich structure panel characterized by bonding by pressing (2) The method for manufacturing a honeycomb sandwich structure panel according to claim 1, wherein the moisture-curable urethane hot melt adhesive has a melting point of 40°C or higher. (3) The method for manufacturing a honeycomb sandwich structure panel according to claim 1, wherein the coating temperature of the moisture-curing urethane hot melt adhesive is 90°C to 140°C. (4) The method for manufacturing a honeycomb sandwich structure panel according to claim 1, wherein the heating press temperature is 100° C. or lower. (5) The surfaces to which the moisture-curing urethane hot melt adhesive is applied are both surfaces of the honeycomb core. A method for manufacturing a honeycomb sandwich structure panel according to claim 1.