JPH0474161B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for adhering fritches.

Conventionally, when creating laminated timber, lumber core, etc. by gluing fritchi (in the present invention, thick pieces of wood called fritchi, lamina, sawn board, strip, etc. in the wood industry are collectively referred to as fritchi). In addition, the moisture content of the fritsch has a significant effect on adhesive performance. For example, if the moisture content is high, dilution, diffusion, permeation, etc. of the adhesive will be excessively accelerated during compaction.
It is well known that if the moisture content is not appropriate, adhesion cannot be achieved as desired, as there is a risk of deterioration of adhesion performance. Moisture content 8-15%
After finishing it to a certain degree, apply adhesive to the adhesive surface,
A common method of adhesion is to bring the adhesive surfaces into contact and press them together.

However, as mentioned above, the moisture content of Fritsch was reduced to 8.
It takes a considerable amount of time and money to achieve an appropriate moisture content of ~15%, and it is extremely difficult to make the moisture content of many frits uniform. The reality is that there are many inherent problems, such as a decrease in yield due to corrections such as warping and twisting, and an increase in adhesive costs due to the need to increase the amount of adhesive to accommodate uneven moisture content. be.

Furthermore, in recent years, synthetic raw wood has been formed by forming appropriately shaped frits from small-diameter wood such as stripped core of veneer lace or thinned wood, and combining and gluing them into an approximately circular or other appropriate shape. By cutting logs, it is possible to create a veneer of small-diameter wood that is difficult to cut alone, or to form a composite frit by combining and gluing appropriately shaped small frits in a desired arrangement. Techniques for obtaining decorative veneers with various patterns by cutting the veneer have been proposed, and are expected to further develop in the future.

However, as is well known, the machinability of wood deteriorates in proportion to the decrease in moisture content. If they are glued together to form synthetic logs or laminated fritches, it becomes extremely difficult to cut them, and the resulting veneers are likely to have defects such as chipping and rough skin, which is extremely unreasonable in practical terms. It was hot.

Therefore, on the other hand, an adhesive that hardens even in high humidity (hereinafter referred to as a high humidity curing adhesive) is used to bond the fritches with a high moisture content to form synthetic logs or laminated fritches. Methods have also been attempted, but this type of adhesive is generally expensive, so it has the disadvantage of increasing the bonding cost, and the strength of the adhesive itself after curing is low, such as with polyurethane resin adhesives. Those with a weak friction were not necessarily very practical as they had a somewhat poor degree of fritch bonding and had a negative effect on cutting.

The present invention was developed to solve the above-mentioned conventional problems, and by providing an adhesion technique that is not significantly affected by the moisture content of the flitches, at least one of the flitches to be bonded can Not dried to the moisture content appropriate for adhesion, that is, semi-dry (in the present invention, a state that has been dried but has not reached the conventional appropriate moisture content is called semi-dry) Even if it is not dried or not, it is possible to bond with adhesives other than high-humidity curing adhesives, simplifying flitch drying, improving flitch yield, improving the machinability of synthetic logs, and reducing bonding costs. The aim is to contribute to the development of the wood industry by reducing the amount of wood used.

That is, specifically, the primary adhesive is applied to the adhesive surface of the frit whose adhesive surface has not been dried to a moisture content appropriate for adhesion, and the primary adhesive is moderately applied by forced curing or natural curing. An adhesion method characterized by applying a secondary adhesive to at least one of the adhesion surface of the frit and the adhesion surface of another frit after curing, and then bringing the adhesion surfaces into contact with each other and pressing. For example, as illustrated in FIG. 1, a small amount of primary adhesive 3 made of urea resin adhesive or the like is applied to the adhesive surface of the undried frit 1 using a gluing machine 2, and a hot air ventilation method is applied. A hardened film of the primary adhesive 3 is formed on the adhesion surface of the frit 1 by pressing it with a heating roll 5 while passing through the heating chamber 4, and then using a gluing machine 6. After applying a secondary adhesive 7 made of urea resin adhesive or the like to the adhesive surface of the fritch 1 on which the cured film of the primary adhesive 3 has been formed,
The adhesive surface of the treated flitch 1 is brought into contact with the adhesive surface of another similarly treated flitch 1 or the adhesive surface of another untreated flitch 1, and is pressed and bonded by an appropriate means.

According to the bonding method configured as described above, a cured film of the primary adhesive is first formed on the bonding surface of the desired fritch. Unlike the hardening of
There is no need to apply high pressure to the adhesive surface, and the adhesive surface remains exposed.
Since direct and rapid forced curing as in the above embodiment is possible, mutual interference between the moisture contained in the frit and the primary adhesive is significantly suppressed or reduced, and dilution, diffusion, and permeation of the primary adhesive are prevented. It is possible to form a thin cured film using a small amount of an inexpensive general-purpose primary adhesive while preventing excessive acceleration of the phenomenon.

The cured film of the primary adhesive prevents mutual interference between the secondary adhesive and the moisture contained in the flitch in the next bonding process, and allows the moisture content of the flitch and the properties or application of the secondary adhesive to be controlled. This prevents a direct negative effect on adhesion and allows semi-dry to wet frits to be bonded using a small amount of inexpensive general-purpose adhesive, so it is not necessary to bring the frits to the conventional proper moisture content. There is no need for drying, and as a result, it is possible to simplify flitch drying, improve flitch yield, improve the machinability of synthetic logs, and reduce bonding costs.

Incidentally, according to experiments, a few grams of urea resin primary adhesive per square meter was applied to each adhesive surface of a semi-dry Fritsch, and the mixture was heated in a heating chamber at 150°C for about 1 minute and 30 seconds. By heating and press-drying at a feeding speed of 2 m/min using heated rolls heated to 150°C, a hardened film of the urea resin primary adhesive is formed on the adhesive surfaces of both flits, and the urea resin primary adhesive is Experimental example in which a urea resin secondary adhesive was applied to the adhesive surface of one of the treated flits and bonded by pressure, with the amount applied limited so that the total amount applied with the adhesive did not exceed at least the conventional example described below. and,
A comparison was made with a conventional example in which 25 to 30 grams of urea resin adhesive was applied per square meter to one adhesion surface of the Fritsch, which had the conventional appropriate moisture content as a whole, and was then pressed and bonded. In each example, it was possible to obtain adhesive strength equal to or higher than that of the conventional example.

In addition to the urea resin adhesives mentioned in the examples, examples of the primary adhesive include thermosetting adhesives such as phenol resin adhesives, melamine resin adhesives, and resorcinol resin adhesives, or vinyl acetate resins. Adhesives other than high-humidity curing adhesives traditionally used for adhering frits can be used, such as thermoplastic adhesives such as adhesives and hot melt adhesives, and even known room temperature curing adhesives. In addition to the roll-type gluing machine mentioned in the example, the application method may also be a spray type, or, for example, a brush or spatula coating. There is no problem if adhesive can be applied to the surface.

The specific means for curing the primary adhesive will be selected depending on the properties of the adhesive used; heating is used for thermosetting adhesives, and cooling is used for thermoplastic adhesives. , each serves as the original curing means, and if it is a room temperature curing adhesive, it will be left to cure naturally, but for example, even if it is thermosetting or thermoplastic, it will naturally harden by leaving it. For materials that are room temperature curable but can be effectively cured by heating, the curing method is not necessarily limited to the original curing method and may be changed as appropriate, and the curing mode is not limited to complete curing. In fact, a semi-cured state with a slight stickiness may be more effective for adhesion in the next process, so it is preferable to select it in accordance with the properties of the secondary adhesive and the application conditions. Depending on the situation, it may be hardened under some pressure in order to promote the anchoring effect.

In addition, as the curing means by heating, in addition to the means of exposing to hot air in a heating chamber and the means of press heating with heating rolls as in the above embodiment, infrared lamps and
Radiant heating using electric heaters, high frequency heating,
Another option is flat press heating using a hot press, but in any case, if air bubbles are generated inside the adhesive, there is a risk that the strength will deteriorate, so it is desirable to avoid too rapid high-temperature heating, and it is also necessary. Depending on the situation, it is also effective to perform adhesion prevention treatment such as fluorine resin coating or plating on the heating member that comes into direct contact with the adhesive.

On the other hand, as the secondary adhesive, various adhesives similar to those mentioned in the explanation of the primary adhesive can be used without particular restrictions, including the application means, and they are not necessarily the same as the primary adhesive. Not limited to adhesives,
For example, a phenolic resin adhesive with excellent water resistance after curing may be used as the primary adhesive, a cheaper urea resin adhesive may be used as the secondary adhesive, or a thermosetting adhesive may be used as the primary adhesive. ,
It is possible to selectively use different types of secondary adhesives, such as room-temperature curing adhesives, as the secondary adhesive, and the secondary adhesive does not necessarily need to be applied to the adhesive surfaces of both flits; It is enough to apply it to the adhesive surface of one of the fritches, so consider the effects of various conditions such as the properties of the secondary adhesive, the deposition time until compression, and the presence or absence of a film of the primary adhesive.
There is no problem if it is selected experimentally.

Incidentally, since the steps after pressing are outside the characteristic requirements of the present invention, a detailed explanation will be omitted. Of course, depending on the properties of the secondary adhesive, forced curing means such as heating or cooling may be used in combination with pressing.

On the other hand, the dry condition of fritchi can vary widely from completely semi-dry to completely undried, but undried ones with an extremely high moisture content are the result of a primary adhesive. Since there is a significant tendency to inhibit the formation of a good film, it is appropriate to carry out the treatment after preferably performing a drying treatment to bring the surface layer to a semi-dry state.

That is, as illustrated in FIG. 2, for example, an undried frit 1a is carried into a hot air ventilation type heating chamber 8, and a drying treatment is performed to bring the surface layer of the frit 1a to a semi-dry state. If a series of bonding methods according to the present invention explained based on FIG. 1 are carried out,
Even if the entire fritch 1a has an extremely high water content, upon curing of the primary adhesive,
This is effective because excessive interference between the water contained in the frit and the primary adhesive is prevented during the night, and a good cured film can be stably formed.

Furthermore, if the drying process is heat drying and the primary adhesive is thermosetting, curing can be expected to be accelerated by residual heat, and similarly, if the drying process is heat drying and the primary adhesive is hot melt type. In some cases, the residual heat can be expected to promote the anchoring effect, so it is preferable to make the drying process and the primary adhesive application process continuous, but in any case, the entire frit is semi-dry by drying. Since this is not necessary, it is possible to apply not only conventional drying means but also rapid local heating at an extremely high temperature, which is not suitable for ordinary drying, as long as burns do not occur on the adhesive surface.

As a secondary step related to the bonding method according to the present invention, sanding treatment is performed on the adhesive surface of the fritchi or the hardened film of the primary adhesive in order to adjust the surface roughness and smooth the surface. There is no problem in applying it, and if necessary, to improve the adhesion performance with other materials such as decorative paper, decorative veneer, cloth, etc., or to improve the water resistance, weather resistance, etc. of Fritsch. In addition to forming a hardened film of the primary adhesive on the adhesive surface of the flitch, it is also possible to form a hardened film of the primary adhesive on a surface other than the adhesive surface of the fritch.

[Brief explanation of the drawing]

The drawings are for explaining the present invention, and FIG. 1 is a process explanatory diagram of the process of implementing the bonding method according to the present invention, and FIG. It is a process explanatory diagram in which a drying process is interposed. 1, 1a... Fritsch, 2, 6... Gluing machine, 3
...Primary adhesive, 4, 8...Hot air ventilation type heating chamber, 5...Heating roll, 7...Secondary adhesive.

Claims (1)

[Claims] 1 A method of adhering the adhesion surfaces of frits, at least one of which has not been dried to an appropriate moisture content for adhesion, using an adhesive other than a high-humidity curing adhesive, which A primary adhesive is applied to the adhesive surface that has not been completely dried, and the primary adhesive is appropriately cured by forced curing or natural curing, and then a secondary adhesive is applied to at least one adhesive surface of the fritsch. A method for adhering a fritsch, which comprises: after applying an adhesive, the adhesion surfaces are brought into contact with each other and pressed together.