JPS62246701A - 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 plywood, and particularly aims to provide plywood that can be effectively used for formwork used in concrete and mortaring for house construction, civil engineering work, etc. It is something to do.

<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. provided.

<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 affects not only the surface layer but also several tens of depths,
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 the Problems> - The present inventor has conducted various studies on the existing rods in which components eluted from the plywood formwork inhibit the hydration reaction of the cement, resulting in poor curing. Extracted components such as water-soluble cellulose, lignin, tannin, humic acid, and sugar contained in the cement slurry are dissolved at the interface with the cement by the water in the cement slurry, and these extracted components are released from the cement.
It was found that the hydration reaction of the cement was suppressed as a result of the cement particles being covered by the salts, which inhibited the cement from curing normally. The dried mortar contains 2SO.

Although there are large amounts of Na2SO4 and Ca(OH)2,
In the case of a mortar with poor hardening, the amount of these mixed together decreased, 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 Na'', K'', and Ca2+, which should be dissolved into the liquid phase during cement hydration and crystallized as 2SO4, NazSO<, and Ca(Oll)2, are adsorbed by the above extract components eluted from the wood, or It is presumed that the excess 5042- crystallized into ettringite because it could not be crystallized because it could not be crystallized because it could not be crystallized.

The present invention has been devised through further study based on the above findings, and provides a plywood in which a veneer on at least one surface of the plywood is coated or impregnated with powder or aqueous solution of a metal compound. It is.

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.

In the present invention, at least one surface of the plywood is coated and impregnated with metal compound powder or aqueous solution using a coating device. There are no particular restrictions on the means for applying or impregnating it, but in the case of a metal compound, it is desirable to use a coating device to spray it on the surface of the plywood, and then rub it into the conduit grooves of the surface veneer with a blade or the like. Alternatively, the powder may be dispersed in latex or the like and applied.

In the case of an aqueous metal compound solution, it can be applied using a known coating device such as a roll coater, spray, or flow coater. The aqueous metal compound solution applied in this way partially penetrates into the veneer on the surface of the plywood to form an impregnated layer, so that the sufficient effect of the present invention can be obtained by applying the impregnated layer to a certain degree of thickness. Further, by applying the aqueous solution while the temperature of the plywood obtained by hot pressing is still high, penetration into the veneer becomes even better.

The application or impregnation of the metal compound is not limited to the surface of the plywood, but may be applied to both the front and back surfaces and/or to the wood end.

The metal compound used in the present invention is one that forms a highly stable complex by combining with extracted components such as cellulose, lignin, tannin, and sugars in the wood of plywood. When using plywood formwork, the present invention prevents the wood extract components from combining with free ions from the cement to form complex salts in the presence of water, and instead replaces them with more stable metal ions. Since the desired effect is to be achieved through bonding, the metal compound used elutes metal ions that are soluble in water and have a higher stability than cement free ions.
It must be able to combine with wood extract components to form poorly soluble complex salts. That is, the metal ions dissolved in the water in the wood and/or the water in the cement slurry combine with wood extract components to form chemically stable complex salts. 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.

<Function> Since the plywood surface is coated or impregnated with metal compound powder or aqueous solution, when this is used as a formwork material for concrete pouring, the extracted wood components such as cellulose, tannins, lignin, and sugars are removed from the plywood. It combines with ions eluted from the metal compound on the surface to form a stable complex salt. 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.

A mixture of cement and standard sand at a ratio of 1:2 was mixed with various solutions at a water/cement ratio of 0.65 to prepare various green mortars.
x4 C1) and cured for one day in a constant temperature bath at a temperature of 20° C. and a humidity of 7.8° C., and then cured in water at 20° C. for a predetermined period to obtain various mortar specimens. The mixed solution was made by soaking 18 pieces of lOxlOx1cm plywood in a saturated Ca(OH)2 solution for 48 hours, then adding various copper compounds, zinc compounds, lead compounds, etc. to the wood extract obtained.
0.1% and 0.1% aluminum compound and iron compound, respectively.
They were added in proportions of 3%, 0.51% and 1.0%. 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 ◎ 0 0 (0,3~
0.5) Copper sulfate ◎ ○ O(0,1
~1.0) Copper hydroxide O○ × Zinc chloride O× × Zinc sulfate ◎ ◎ ◎(0,1
~0.3> (0,1~0.3) (0,3~0.
5) Zinc hydroxide Ox X Lead chloride ◎ ◎ ◎ (0,1
~1.0) (0,3~1.0) (0,3~1.
0) Lead sulfate ○ ◎ ◎(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 ◎ ◎ O(0
,1~1.0) (0,3~1.0) Aluminum hydroxide
○ × ×ferric chloride ◎
◎ ◎In terms of compressive strength in Table 1, X marks indicate that no increase in strength was observed compared to mortar prepared using a solution containing no metal compounds, and ○ marks indicate that a slight increase in strength was observed. The marks ◎ indicate those in which the strength increased significantly. Moreover, the numerical value shown in parentheses under the mark ◎ is the amount of metal compound added when the strength development reaches the maximum.

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 chloride and copper sulfide are prominent in copper compounds, zinc sulfate in zinc compounds, lead chloride and lead sulfate in lead compounds, aluminum chloride and aluminum sulfate, and iron chloride in aluminum compounds. It was found to have an inhibitory effect.

Furthermore, when we examined the fine structure of the mortar specimens in which these remarkable inhibitory effects were obtained using a scanning electron microscope, we found that in all cases, gel-like particles were adsorbed and polymerization occurred due to chemical bonding. Fibrous or granular
A lumpy product was observed. This is Fe, which has greater stability than the ions Ca2., K", 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 produced by combining with wood extract components.

<Example> Copper sulfate, zinc chloride, aluminum chloride, alum, and ferric chloride were used as metal compounds on the surface of a plywood board made of 3 x 6 x 12 mm thick merape material, and these were applied in a 10π aqueous solution and a 20% aqueous solution, respectively. Adjusted as
Using a roll coater, 4h/shoulder”, 100g#+
It was applied at a coating weight of 2. Next, these plywoods were dried to prepare various treated plywoods. For comparison, we also prepared untreated plywood 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.

2nd surface plywood Metal compound concentration Application amount Concrete
To hardening inhibition depth 7 Type-Ichibu ELuz #Riichi-side Q・
'(i+shoulder untreated plywood -- Dark throughout 2-4 treated plywood Copper sulfate 1040
Some slight brown 0.2-0.3100) Horn 1 20 40 71
tno IQQ rr
〃Zinc chloride 10 40 HnIQQ
77 n20 40
II t
No IQQ II 77 Aluminum chloride 1040 None 0-0.210
0 horn n20
40 n 71100 no I alum 10 40 II
l110Q rr
n2040 Tsuno n 100 II 77 Ferric chloride 1040 Not nQQj
Jn 20 40 u rr As is clear from the results shown in Table 2, concrete cured in a form made of untreated plywood to which no metal compound has been applied has a depth of 2 to 4131 mm from its surface. Curing inhibition was detected and the entire surface exhibited a deep dark brown color, whereas those coated with the metal compound aqueous solution according to the present invention showed almost no curing inhibition and the surface color was generally uncontaminated. there were.

<Effects of the Invention> According to the present invention as described above, extracted components such as cellulose, lignin, tannin, and sugars in the plywood material combine with the metal compound coated or impregnated on the surface of the plywood material 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, when plywood is used as concrete formwork,
Extractable components from this material do not elute even when water penetrates into the cement slurry, and even if they do, they combine with the metal compounds coated and impregnated into the veneer and prevent their elution. Therefore, curing inhibition caused by the extracted components can be effectively suppressed without impairing the design.

Therefore, the present invention can be effectively utilized particularly in the case of interior wall construction and repainting construction.

Claims (2)

[Claims] (1) A plywood characterized in that at least one surface of the veneer is coated or impregnated with a powder or aqueous solution of a metal compound. (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;
Plywood according to claim 1.