JPS62253402A - Manufacture of flitch - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for manufacturing plywood, and particularly to a method for manufacturing plywood that can be effectively used for formwork used in concrete and mortaring for house construction, civil engineering work, etc. This is what we are trying to provide.

<Prior art> Conventional formwork is known to use plywood as is, but the concrete and mortar poured into the formwork adheres to the plywood surface of the formwork, making it difficult to remove the formwork. Because of this drawback, tar or paraffin/silicone-based release agents are applied to the plywood surface at construction sites to improve removability. In addition, in recent years, in order to prevent this concrete/mortar from adhering to the plywood surface, painted formwork has been manufactured by applying synthetic resin such as acrylic resin or urethane resin at the factory to form a coating layer on the plywood surface. (For example, Japanese Patent Publication No. 45-15064, Japanese Patent Publication No. 53-38728, Japanese Utility Model Publication No. 47-3)
Publication No. 0639).

<Problems to be solved by the invention> It is known from experience that when plywood is used as a formwork for pouring concrete, dark-colored poorly cured areas are formed at the concrete interface after the mold is released. . Since such concrete materials are unfavorable in appearance, when a wall is constructed by pouring concrete, it not only reduces the design of the wall but also significantly reduces its strength due to poor curing. In some cases, this poorly cured area may not only affect the surface layer but also extend to a depth of several inches.
If you touch that part with your hand or an object, it turns into particles and falls off.

In addition, in the case of joint painting construction on a concrete surface, the joint mortar applied to the surface, the spraying material, etc.
The finishing coating material, tiling, etc., had the disadvantage of peeling off from poorly cured areas after construction, lifting up, and sometimes peeling off.

The formation of these poorly hardened areas is thought to be due to harmful substances contained in the formwork plywood leaching out of the wood and inhibiting the hydration reaction of cement, but the detailed mechanism is still not fully understood. Not yet.

In conventional painted forms, a synthetic resin coating layer is formed on the surface, so the elution of harmful substances from the wood is suppressed to some extent in the early stages of use, but the elution of harmful substances through pinholes in the coating layer is suppressed to some extent. This is unavoidable, and elution is likely to occur due to cracks in the coating layer due to deterioration of the coating layer, damage to the coating layer due to external forces, etc. Therefore, it could not be a means to fundamentally solve the problem of contamination of the concrete surface and inhibition of hardening due to the elution of harmful substances from the wood.

Means for Solving Problems〉 The present inventor has conducted various studies on the phenomenon in which components eluted from plywood formwork inhibit the hydration reaction of debris and lead to poor curing. Extracted components such as water-soluble cellulose, lignin, tannin, humic acid, and sugars are dissolved at the interface with the cement by the water in the cement slurry, and these extracted components release Ca'' from the cement.
, K", and Na' combine to form a salt, which covers the cement particles and suppresses the subsequent hydration reaction of the cement. In other words, it hardens normally. The dried mortar is SO.

Although there are large amounts of Na2SO4, C, a(0■)2,
In the case of a mortar with poor hardening, the amount of these mixed together was reduced, and in the mortar with a markedly poor hardening, these were hardly present, and instead, a large amount of ettringite was observed. This is because 2S04. Na'', K'', and Ca2°, which should be crystallized as Na25On, Ca(Oll)z, cannot be crystallized because they are adsorbed or chemically combined with the above extract components eluted from the wood to form complex salts. It is presumed that the excess so,'- crystallized into ettringite.

The present invention was created based on the above-mentioned findings after further study, and includes the steps of: obtaining at least one treated veneer by coating or impregnating the surface of at least one side of the veneer with a powder or aqueous solution of a metal compound; The treated veneer and one or more untreated veneers are laminated with an arbitrary adhesive so that the treated surface of the treated veneer constitutes at least one surface, and then pressure bonded. The present invention provides a method for manufacturing plywood characterized by the following.

That is, in view of the fact that in the above-mentioned conventional technology, attempts were made to prevent the elution of harmful components from the wood by forming a coating layer on the surface of the form plywood, but the results were insufficient, formation of a coating layer, etc. We have moved away from the technical concept of physically preventing the elution of wood extract components, and from a chemical standpoint, we have developed methods for preventing wood extract components from combining with free ions from cement to form complex salts. I thought about it a lot.

By pre-bonding wood extract components with metal ions that generate complex salts that are more stable than these free ions, the wood extract components will more stably chelate with the metal ions, resulting in free ions. The present invention was achieved based on the discovery that it is possible to prevent the bonding with.

The configuration of the present invention will be explained below.

First, at least one surface of the material veneer obtained by cutting it to a desired thickness is impregnated with a metal compound. While the discharged continuous veneer is being wound up on a reel, at least one surface of the veneer is sprayed with an aqueous solution of a metal compound, using a roll coater,
It is practical to apply with a flow coater or the like or to sprinkle powder of a metal compound. As the veneers sequentially coated with an aqueous solution of a metal compound are wound onto a reel, the surface of the veneer opposite to the coated surface comes into contact with the coated surface of the veneer that has already been wound. An aqueous solution of a metal compound is also applied to the surface of the veneer on the opposite side. The metal compound thus applied to the surface penetrates and becomes impregnated into the veneer. Also, when powder of a metal compound is sprinkled on the surface of the veneer, the metal compound is dissolved by the moisture in the veneer and permeates into the veneer.

In some cases, a plurality of veneers may be stacked after coating an aqueous solution of a metal compound or scattering powder of a metal compound on at least one surface of a veneer that has been cut or side-stripped to an arbitrary width. When impregnating the metal compound with the metal compound, an injection device that uses pressurization, depressurization, etc. may be used to impregnate the metal compound.

The metal compound used in the present invention is a compound that combines with extracted components such as cellulose, lignin, tannin, and sugars in the wood of plywood to form a highly stable complex. When used, it prevents the wood extract components from combining with free ions of the cement bones in the presence of water to form complex salts, which instead combine with more stable metal ions to achieve the desired effect. Therefore, the metal compound used elutes metal ions that are soluble in water and have higher stability than cement free ions.
It must be able to combine with wood extract components to form a sparsely soluble complex salt. In other words, the metal ions dissolved in the water contained in or permeated into the veneer must combine with the wood extract components. This creates a chemically stable complex salt inside the veneer.

For example, one or more selected from sulfides, chlorides, hydroxides, etc. of iron, copper, zinc, lead, aluminum, etc. can be used alone, in combination, or in a mixture.

The treated veneer impregnated with the metal compound is then dried and adjusted to a constant moisture content in a drying device to obtain a treated veneer.

Next, the treated veneer is used as a veneer on at least one side of the plywood, and this and one or more untreated veneers are laminated with an adhesive of your choice, and then hot pressed using a hot press. Any required number of veneers laminated in zero plywood to obtain a veneer according to the present invention can be formed as a treated veneer, and in some cases, all of the veneers, such as 3-ply, 5-ply, etc., can be treated. Although it is possible to use a veneer, since the present invention aims to prevent the elution of wood extract components from the plywood surface by intervening a metal compound, at least one surface of the plywood should be the treated surface of the treated veneer. is required.

Through the above steps, a plywood is obtained in which at least one surface of the plywood is treated with a treated veneer that has been impregnated with a metal compound.

Note that the impregnation treatment of the metal compound into the veneer can also be carried out by impregnating the dried material veneer with an aqueous solution of the compound using dipping or an injection device, but it is necessary to dry it again after this impregnation treatment. must be done,
This is not preferable because it reduces productivity.

Effect> Since the plywood surface is coated or impregnated with metal compound powder or aqueous solution, wood extract components such as cellulose, tannin, lignin, and sugars are stabilized by binding with ions eluted from the metal compounds on the plywood surface. Forms complex salts. Therefore, the formation of complex salts due to the combination of these wood extract components and free ions from cement is suppressed.

Test Example> The effects of various metal compounds on the inhibition of cement hardening by wood extract components were tested.

Cement: standard sand mixed in a ratio of 1: 2,
Various solutions were mixed and kneaded at a water/cement ratio of 0.65 to prepare various green mortars, and these were placed in an iron formwork (1x
lx4 cm), temperature 20℃, temperature approx.
After curing for one day in a constant temperature bath of 20° C., various mortar specimens were obtained by curing in water at 20° C. for a prescribed period. The mixed solution was made of 18 sheets of lOxlOx1cm plywood with saturated Ca
Various copper compounds, zinc compounds, lead compounds, and aluminum compounds were added to the wood extract obtained after soaking in the (Oll)z solution for 48 hours at 0.1$, 0.3LO, 5%, and 1.0$, respectively. It is added in proportion. For comparison, mortar specimens prepared by blending solutions to which these metal compounds were not added were also prepared.

Table 1 summarizes the results of measuring the compressive strength of these mortar specimens after curing and hardening for a predetermined period of time.

Copper chloride ◎ ○ O(0,3
~0.5) Copper sulfate ◎ O○ (0.1~1.0) Hydroxide fRo ox Zinc chloride
O × × Zinc sulfate ◎ ◎ ◎ (0,1
~0.3) (0,1~0.3) (0,3~0.
5) Zinc hydroxide O× × Lead chloride ◎ ◎ ◎(0,1
~1.0) (0,3~1.0) (0,3~1.
0) [Acid lead O◎ ◎ (0,1~0.5> (0,1~0.5) Lead hydroxide
OO× Aluminum chloride ◎ ◎ ◎(0,1
~1.0) (0,1~0.5) (0,3~0.
5) Aluminum sulfate ◎ ◎ ○(0
,1~1.0) (0,3~1.0) Aluminum hydroxide
○ × ×Ferric chloride ◎
◎0O21~1.00.1~0,50
．． 3 to 0.5 Regarding the compressive strength in Table 1, the X mark indicates no increase in strength compared to the mortar prepared using a solution without the addition of metal compounds, and the O mark indicates a slight increase in strength. The ◎ marks indicate those where an increase in strength was observed, and the numbers shown in parentheses under the ◎ marks are the amount of metal compound added when the strength development reached the maximum. be.

From the results shown in Table 1, although the effects are not necessarily constant depending on the type of metal compound and the amount added, it is generally possible to suppress the cement hardening inhibiting effect of wood extract components by incorporating these metal compounds. It is known that it is possible.

In particular, copper compounds include chloride steel and sulfide steel, zinc compounds include zinc sulfate, lead compounds include lead chloride and acid lead, aluminum compounds include aluminum chloride and aluminum sulfate, and iron compounds include iron chloride. It has been found that each of these has a significant suppressive effect.

In addition, when we investigated the microstructure of the mortar specimens in which these remarkable suppressive effects were obtained using a scanning electron microscope, we found that in all cases, gel-like particles were adsorbed and chemical bonds were observed. Polymerized fibrous or granular
A lumpy product was observed. This is Fe, which has greater stability than the ions Ca'', Ni, Na+, etc. released from cement into the liquid phase.

Metal ions such as Cu, Zn, Pb, and ^1 were eluted from the added metal compound, and it was determined that these metal ions were complex salts that were not produced by combining with wood extract components.

<Example> Copper sulfate, zinc chloride, aluminum chloride, alum, and ferric chloride were used as metal compounds on one surface of a 2zz-thick Melabi wood veneer, and a 1oz aqueous solution of each of these was added.
01 aqueous solution was coated using a roll coater in a coating amount of 40g71, 100g12. Five-ply plywood was prepared using these treated veneers as a top plate. For comparison, we also prepared plywood prepared using untreated veneer that was not coated with an aqueous solution of these metal compounds.

These treated plywood and untreated plywood were used as concrete molds, and the molds were removed three days after concrete pouring, and the conditions of the concrete surfaces were comparatively observed to examine the effects of applying the metal compound aqueous solution. The results are shown in Table 2 below.

Table 2: Untreated plywood --Dark throughout 2-4
Treated plywood Copper sulfate 104〇 Some slight browning
0.2~0.320 40 77
l11G0 77 11 Zinc chloride 10 40 77
ノ11G0 77 n20
40 71 jtlGo
/7) 1 aluminum chloride 10
4G None 0~0.2100
77 n20 40 77
tsloo 77
77 alum 10 40 11
771G0 n
77100 n nferric chloride 10 40 77 n10
0 // /J20 40
II tslooo
77 nAs is clear from the results shown in Table 2, concrete cured in a plywood formwork obtained using untreated veneer to which no metal compound has been applied has a depth of 2 to 4 u from the surface. On the other hand, curing inhibition was detected and the entire surface exhibited a deep dark brown color, whereas in the case of the material coated with the metal compound aqueous solution according to the present invention, there was almost no curing inhibition and the surface color was generally stained. It was something that had not been done yet.

<Effects of the Invention> According to the present invention as described above, extracted components such as cellulose, lignin, tannin, and sugars in the veneer combine with the metal compound coated or impregnated on the surface of the veneer to form a highly stable insoluble material. Since the complex is formed, the elution of the extracted components can be sufficiently suppressed.

In addition, these wood extract components combine with the metal ions eluted into the water contained in the wood to form an internal insoluble complex, so the extract components are not dissolved by subsequent moisture adhesion due to rainwater, etc. Furthermore, even if it is dissolved, it binds to the metal compound coated or impregnated within the veneer to prevent its elution, and the surface of the plywood is not contaminated by the extracted component.

Furthermore, even when the plywood according to the present invention is used as concrete formwork, the extractable components from the wood will not be eluted even if water penetrates into the cement slurry, and even if they are dissolved, they will not be applied to the veneer. - Since it binds to the impregnated metal compound and prevents its elution, it is possible to effectively suppress curing inhibition caused by the extracted component and does not impair the design. Therefore, the present invention is particularly useful for inner walls. It can also be effectively used for construction and repainting work.

Patent applicant: Noda Plywood Co., Ltd. Agent Patent Attorney Fumihito Higashihara Same as Yoshibe Takeda

Claims (2)

[Claims] (1) At least one treated veneer is obtained by coating or impregnating the surface of at least one side of the veneer with a powder or aqueous solution of a metal compound, and the treated veneer and one or more untreated veneers are subjected to the treatment. A method for producing plywood, which comprises laminating the veneers using an arbitrary adhesive so that the treated surface constitutes at least one surface, and then press-bonding the veneers. (2) The metal compound is characterized in that it consists of one or more substances selected from sulfides, chlorides, and hydroxides of iron, copper, zinc, lead, and aluminum;
A method for manufacturing plywood according to claim 1.