JPS5841163B2 - Sliced tanbanoseizohou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing sliced veneers, and the present invention relates to a method for manufacturing sliced veneers, in which the edges of the sliced veneers in the wood direction are strengthened so that they can be used during slicing and transportation.
The purpose is to reduce cracking, chipping, splitting, etc. at the butt end of sliced veneer during drying and various other types of drying.

Sliced veneer is generally made from flitch wood (often wet wood) using a slicer or...-Floatary lace.
2. It is produced by slicing it into several millimeters, but the flitch material may already have cracks in it, the sliced veneer is thinner than board material, and the area is smaller than the thickness of the veneer. Must be wide (width 10~40crrL, length 2~47cm)
n), etc., cracks appear at the butt end of the veneer during slicing and subsequent processes, which causes the veneer to split or partially chip, resulting in a decline in the quality of the veneer. .

The inventors previously invented a method of reinforcing the end of the log with a cured urethane resin when cutting the raw wood for plywood over a rotary lace to obtain veneer (Japanese Patent Application No. 32,496/1986).
, Japanese Unexamined Patent Publication No. 50-125007).

Although this method can be fully put into practical use in the production of sliced veneers, the present invention is a further improvement of the above-mentioned application, and in particular, even if the thickness of the sliced veneer is extremely thin, the effect of edge reinforcement is fully exhibited. It has characteristics.

Traditionally, to strengthen the end of a veneer, glue or paper tape coated with polyvinyl alcohol glue has been pasted near the end of the veneer. This is limited to cases where veneer can be obtained continuously and can be rolled up endlessly with a reeling machine (because the tape is stuck together by wrapping the tape together when winding the veneer), for example, if the log is cracked. This method is difficult to use if only a narrow veneer can be obtained and reeling is not possible.

In this type of reeling tape method, the tape is attached to the surface of the veneer, although it is near the end of the veneer, so when it is processed into plywood, the adhesive strength of the tape part is weak, which poses a problem.

In addition, if the thickness of ordinary sliced veneer is extremely thin (<0.2 to 0.3 mm), when it is processed into a decorative board, if the tape is interposed between the veneer and the base plate, a bulge will appear on the decorative surface and the decorative surface will be damaged. value will be halved.

For this reason, when applying tape to the veneer surface to prevent veneer cracking, efforts are made to apply the tape as close to the end of the wood as possible, but usually the tape is applied closer to the end of the wood. It has been common practice to lengthen the veneer and then cut it off at the same time when cutting the ends of plywood products.Therefore, a method has been awaited to solve this problem in terms of loss of wood resources and increase in product costs.

By applying a urethane resin with wet surface adhesion to the end surface of the raw wood in advance to strengthen it, the inventors were able to strengthen the process by applying a urethane resin that has wet surface adhesion to the end surface of the raw wood. Of course, if you can reel with
We have invented a method to obtain veneers with reinforced wood end edges, and now we have come up with a method that is even more effective for producing extremely thin slices of veneer of around 0.2 □.

That is, the present invention provides fiber-reinforced thermosetting, flexible, It is coated with hydrophilic polyurethane resin and then sliced.

In detail, strong cloth or paper is bonded and cured with urethane resin on the wood end surface, or natural or artificial fibers are mixed with urethane resin and then applied and cured. This is a method to obtain a veneer whose wood end is reinforced with a layer of urethane resin that has been previously reinforced with these fibers by coating the wood with a thermosetting, flexible, hydrophilic polyurethane resin and then slicing it.

In addition, in order to strengthen the coating on the end surface of flitch wood, when stocking the end surface of flitch wood after coating, it is effective to prevent discoloration, rot, contamination, and cracking of the end surface of flitch wood, and no treatment is required. It is highly valuable as a flitch material because it is more effective than wood.

The reinforcing fibers of the present invention include so-called natural fibers such as pulp, cotton, wool, and silk, so-called artificial fibers such as nylon, vinylon, rayon, and Tetron, and inorganic natural or artificial fibers such as rock wool, asbestos, and glass fibers. etc. can be used.

These may be in the form of short fibers or long fibers, such as paper, nonwoven fabric,
It may be in the form of cloth, mat, etc.

The thickness of the reinforcing sheet is not determined in part by the strength of the fibers, but generally a thickness equivalent to or thicker than shoji paper gives good results.

The size of the reinforcing sheet should be about the size of the end area of the flitch material, and even if a size larger than the end area is used, the results will not change and it is meaningless.

The fiber direction of the reinforcing sheet is preferably oriented in the direction of slicing when adhering to the flitch material and slicing.

Therefore, for example, it is more effective to use paper whose tear strength differs vertically and horizontally so that the slicing direction and the paper's strength direction match, rather than just paper.

The resin used in the reinforcing sheet of the present invention generally has a strong property that adheres well to a wet surface because the flitch material for slicing is in a wet state, does not crack or chip when sliced, and has a fibrous material as much as possible. It is preferable to use a material that penetrates well between the wood and the wet wood end surface and has a strong foothold.

The reinforcing liquid resins that are usually used for FRP include unsaturated polyester, epoxy,
Any resin such as phenol-based, urethane-based, resorcinol-based resin can be used as long as it satisfies the above conditions, but especially for the purpose of the present invention, it is possible to use resins such as phenol-based, urethane-based, and resorcinol-based resins. It has excellent penetration into parts and reinforcing fibers, has a strong mutually reinforcing effect, and has large rubber elasticity.It can fully adapt to the expansion and contraction of sliced veneers during repeated wetting and drying, and has fast curing properties. Thermosetting flexible, hydrophilic polyurethane resin is suitable because it has excellent void filling properties even if the end surface of the flitch is quite rough and uneven.

The thermosetting flexible, hydrophilic polyurethane resin used in the present invention may be either a -liquid type or a two-liquid type, but a moisture-curable one-liquid type is preferable in terms of workability. is preferred.

The polyurethane resin of the present invention has a cured product structure in which aliphatic polyether chains or polyester chains with a molecular weight of several hundred to several thousand form a somewhat coarse network bond and exhibit strong rubber elasticity. It is necessary that

In this case, by using a hydrophilic polyether chain or polyester chain as a main component, the urethane resin composition used in the present invention has appropriate hydrophilic properties, has good compatibility with wet wood surfaces, and Diffusion of water into the resin layer becomes easy, and even if water is cured while being dispersed in the resin layer, the physical properties are hardly deteriorated, and wet surface adhesion becomes possible.

That is, the polyurethane resin used in the present invention may be a general polyether polyol, a polyester polyol, a prepolymer obtained by reacting these with a polyisocyanate and mainly having an OH group at the end, or a mixture thereof. A prepolymer made by reacting a so-called polyol component as the main component with a normal polyisocyanate compound, or a polyol component with -NCO at the end.
It is a two-component type consisting of a so-called polyisocyanate component mainly having a polyisocyanate component or a mixture thereof.

More preferably, it is a one-component type polymer mainly composed of a long chain or branched long chain flexible hydrophilic polyurethane polymer whose terminal ends are mostly --NCO groups.

It can be bonded to wet surfaces and has a shelf life of several months at room temperature if kept moisture-free, but once applied to a wet surface, moisture will diffuse into the resin layer, and this water will act as a crosslinking agent. This effect results in rapid curing even at room temperature.

As such polyurethane prepolymers whose terminals are -NGO groups, those whose main chain consists of polyalkylene ether bonds have good hydrophilicity and are suitable for the purpose of the present invention.

Furthermore, if the water resistance is slightly inferior due to only polyethylene ether chains, it is preferable to partially replace the polyethylene ether chains with polypropylene ether chains, and those having block copolymer chains of both are particularly preferable.

It is also desirable to partially replace the polyalkylene ether chains with polyester chains in order to improve water resistance.

In addition to these prepolymers, TDI,
It is also preferable to contain low-molecular compounds such as MDI, MXDI, and Desmodur L (trade name of Sumitomo Bayer Urethane Co., Ltd.) in order to improve curability.

If necessary, organometallic compounds such as organotin compounds, polyamine compounds (mainly tertiary amines), or mixtures thereof may be used as curing agents for these resins.

In addition, compounds having active hydrogen such as primary or secondary amines, low-molecular polyhydric alcohols, or mixtures thereof may be used as crosslinking aids.

A curing retarder may also be used.

Furthermore, adding water during use will not only accelerate the curing process, but also be effective because when the veneer is dried after slicing, the cured resin will also exhibit shrinkage and will synchronize with the drying shrinkage of the veneer. Moreover, due to its foamability, it also has excellent gap-filling properties.

In addition, it may be possible to use an inert solvent that does not react with -NCO groups such as ketones, esters, aromatic hydrocarbons, etc. in an anhydrous state to facilitate the reaction and adjust the viscosity. For the purpose of the invention, it is preferable to use a solvent mainly composed of hydrophilic solvents.

Furthermore, in the present invention, fillers such as wood flour, cork powder, wheat flour, etc. are used, or Erosil (Nippon Aerosil, K.
, dehiscence product name), thixotropic agent such as bentonite to impart thixotropic properties to the composition, or modification with a thermosetting resin containing active hydrogen such as epoxy resin, amino resin, phenolic resin, etc. Sometimes I do.

Further, in this case, it is desirable to add a water-containing filler such as this powder immediately before use, since water as a hardening agent can be uniformly dispersed and the hardened resin layer can be reinforced.

It may also be colored with a suitable facial dye.

Examples will be explained below.

Example 1 Plug material flitch with a moisture content of 60 to 80% boiled in a boiling tank (
For the rainwater opening of the butt end (length: 40 cIrL, width: 30 CrrLo, total length: 200 cm), use a 0.3 mm thick kraft paper that has been pre-spread by spraying water using the adhesive composition of the formulation shown in Table 1. After gluing and curing the adhesive, it was sliced into 0.4 mL pieces using a slicer with a sharp knife to obtain a veneer with a reinforced butt end.

The edges of this veneer are sufficiently reinforced with kraft paper and urethane resin, so the edges do not tear when handled in the usual way, and there are no abnormalities at the edges even after drying in a roll dryer at 175℃ for 20 minutes. There were no defects at all, such as cracks, tears, and chips, compared to the same veneer without edge treatment.

Example 2 A flitch made of lauan material with a moisture content of 40 to 70% (vertical end shape: 50 cIn, width: 100 cIrL, total length 120 cr)
Il) Using the adhesive composition shown in Table 2 on the rainwater outlet, glue a piece of kraft paper with a thickness of 0.4 □ that has been pre-stretched by spraying water on it, then use a sharp knife to glue it. A lauan veneer with a reinforced butt end was obtained by slicing it into 3.5 mm thick pieces using a slicer equipped with the following.

The edges of this veneer are reinforced with kraft paper and urethane resin, so the edges will not tear when handled using standard methods, and there will be no abnormality at the edges even after drying in a roll dryer at 180℃ for 45 minutes. Compared to the same veneer without edge treatment, there were significantly fewer defects such as cracks, splits, and chips.

Example 3 When the kraft paper used in Example 2 was replaced with cotton cloth that had not been subjected to shrinkage treatment, results equivalent to or better than those of Example 2 were obtained.

Example 4 A composition prepared by blending the adhesive composition of Example 1 with cotton fibers, rayon fibers, nylon fibers, or asbestos fibers cut into lengths of 2 to 10 □ to form a paste was added to the wet flitch material using rainwater. It was applied to the mouth surface to a thickness of about 2 square meters and cured to obtain a butt end reinforced flitch material.

The end-reinforced flitch material was sliced into various thicknesses of 0.2 to 1.6 mm by a conventional method to obtain sliced veneers with reinforced ends.

The sliced veneer had no abnormalities at the end end during normal handling, and even after drying in a dryer, there were significantly fewer cracks and chips at the end end than in the untreated veneer.

If the end of the flitch material is dry, the applied composition will not cure sufficiently, so wetting the end of the flitch with water or adding water to the composition will give better results. Ta.

(However, in the case of Examples 1.2.3, the paper and cloth are moistened with water, so even if the end part is dry, there is no need to wet the end part or use a composition containing water).

Claims (1)

[Claims] 1. A slice with a reinforced butt end, which is characterized by slicing the flitch material after obtaining a flitch material whose end surface is pre-coated and reinforced with a fiber-reinforced thermosetting, flexible, hydrophilic polyurethane resin. Method of manufacturing veneer.