FIREPROOFING CHEMICAL-CONTAINING WOOD MATERIAL AND PRODUCTION METHOD THEREFOR

Abstract

The present invention improves the reliability of fire-resistance performance, and suppresses a drop in strength and a drop in Young's modulus for bending, with regard to a structural LVL containing a fireproofing chemical for fire-resistant structural wood material-use. The present invention is the LVL 61 for structural use comprising a plurality of raw material veneers 51 layered in the front-back thickness direction via adhesive layers therebetween. Each of the raw material veneers 51 is a wood material having a fireproofing chemical injected to the interior thereof and is constituted from a site of sapwood part alone, a site of heartwood part alone, or, a site wherein a sapwood part and a heartwood part are mixed. Injection holes 62 are provided, each having a circular cross section and extending in the thickness direction from each of the front surface and the back surface of the LVL 61. The injection holes 62 traverse through the plurality of raw material veneers 51 and the adhesive layers. On the front surface and the back surface, respectively, plurality of the injection holes 62 are aligned while leaving an interval therebetween in the width direction and in the length direction of the LVL 61. The injection holes 61(U) from the front surface and the injection holes 61(D) from the back surface are disposed at different positions from one another in the width direction and in the length direction.

Claims

1. Wood containing a fireproofing chemical which comprises wood injected with a fireproofing chemical inside, wherein the wood is structural LVL in which multiple layers of raw material veneers constituted by a section of only sapwood section, a section of only heartwood section or a mixed section of the sapwood section and the heartwood section are laminated in a front and back thickness direction via an adhesive layer, wherein the raw material veneer is a rotary veneer provided with lathe checks, wherein the longitudinal direction of the wood is substantially coincided with a fiber direction and a lengthwise direction of the lathe checks, wherein the wood has injection holes with circular cross section extending in the thickness direction from each of the front and back surfaces of the LVL, wherein the injection holes penetrate a plurality of the raw material veneers and an adhesive layer between the raw material veneers, wherein each of the injection holes on the front and back surfaces is arranged in plural numbers at intervals in a width direction and a lengthwise direction of the LVL, wherein among the injection holes, injection holes from the front surface and injection holes from the back surface are arranged at different positions in the width direction and the lengthwise direction, and wherein all the raw material veneers are provided with the injection holes from at least one of the injection holes from the front surface and the injection holes from the back surface.

2. The wood containing a fireproofing chemical according to claim 1, wherein each of the injection holes from the front surface and the injection holes from the back surface are arranged at equal intervals in both the lengthwise direction and the width direction of the LVL, wherein each row of injection holes adjacent to each other in the lengthwise direction of the LVL are arranged at different positions in the width direction, wherein each row of the injection holes adjacent to each other in the width direction of the LVL are arranged at different positions in the lengthwise direction, and wherein the tips of the injection holes from the front surface and the injection holes from the back surface overlap in the thickness direction.

3. The wood containing a fireproofing chemical according to claim 1, wherein the raw material veneer around the injection holes from the surface has areas on surface-side infiltration where the fireproofing chemical has infiltrated from each of the injection holes in the width direction and lengthwise direction, wherein the infiltration areas on the surface side are arranged on the surface side of the wood in the width direction and lengthwise direction and overlap each other so that no areas remains where the fireproofing chemical is not infiltrated between adjacent infiltration areas, wherein the raw material veneer around the injection holes from the back side has infiltration areas on the back side where the fireproofing chemical has infiltrated from each of the injection holes in the width and lengthwise directions, wherein the infiltration areas on the back side are arranged on the back side of the wood in the width direction and lengthwise direction and overlap each other so that no areas remains where the fireproofing chemical is not infiltrated between adjacent infiltration areas, and wherein the infiltration areas on the front surface side and the infiltration areas on the back side are configured so as to overlap each other so that no areas remains where the fireproofing chemical is not infiltrated between the infiltration areas in the thickness direction.

4. The wood containing a fireproofing chemical according to claim 1, wherein the wood has: a width (W): 45 mm to 900 mm, a thickness (T): 30 mm to 210 mm, and a length (L): 1,800 mm to 9,000 mm.

5. The wood containing a fireproofing chemical according to claim 1, wherein the injection holes have: a diameter of injection holes is 3 mm to 15 mm, an interval L1 between the injection holes in the fiber direction is 100 mm to 300 mm, an interval W1 between the injection holes in the orthogonal direction to fiber is 25 mm to 60 mm, and a ratio of the interval L1 between the injection holes in the fiber direction to the interval W1 between injection holes in the orthogonal direction to fiber is 4:1 to 12:1.

6. The wood containing a fireproofing chemical according to claim 2, wherein the raw material veneer around the injection holes from the surface has areas on surface-side infiltration where the fireproofing chemical has infiltrated from each of the injection holes in the width direction and lengthwise direction, wherein the infiltration areas on the surface side are arranged on the surface side of the wood in the width direction and lengthwise direction and overlap each other so that no areas remains where the fireproofing chemical is not infiltrated between adjacent infiltration areas, wherein the raw material veneer around the injection holes from the back side has infiltration areas on the back side where the fireproofing chemical has infiltrated from each of the injection holes in the width and lengthwise directions, wherein the infiltration areas on the back side are arranged on the back side of the wood in the width direction and lengthwise direction and overlap each other so that no areas remains where the fireproofing chemical is not infiltrated between adjacent infiltration areas, and wherein the infiltration areas on the front surface side and the infiltration areas on the back side are configured so as to overlap each other so that no areas remains where the fireproofing chemical is not infiltrated between the infiltration areas in the thickness direction.

7. The wood containing a fireproofing chemical according to claim 2, wherein the wood has: a width (W): 45 mm to 900 mm, a thickness (T): 30 mm to 210 mm, and a length (L): 1,800 mm to 9,000 mm.

8. The wood containing a fireproofing chemical according to claim 2, wherein the injection holes have: a diameter of injection holes is 3 mm to 15 mm, an interval L1 between the injection holes in the fiber direction is 100 mm to 300 mm, an interval W1 between the injection holes in the orthogonal direction to fiber is 25 mm to 60 mm, and a ratio of the interval L1 between the injection holes in the fiber direction to the interval W1 between injection holes in the orthogonal direction to fiber is 4:1 to 12:1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0075] FIG. 1(A) is an explanatory drawing of cross-sectional structure of logs for obtaining wood of LVL for structure according to the embodiment of the present invention, and FIG. 1 (B) is an explanatory drawing of cross-sectional structure of logs for obtaining wood of LVL for structure according to another embodiment.

[0076] FIG. 2 shows the structure of LVL for structure according to the embodiment of the present invention, FIG. 2(A) shows a plan view, FIG. 2(B) shows a front view, FIG. 2(C) shows a side view, and FIG. 2(D) shows a bottom view.

[0077] FIG. 3 is an enlarged view of the main part of FIG. 2(A).

[0078] FIG. 4 is a longitudinal sectional view of the main part of the LVL for structure of the present invention.

[0079] FIG. 5(A) is a longitudinal sectional view of the main part showing the infiltration area of the LVL for structure of the present invention, and FIG. 5(B) is a three-dimensional explanatory drawing showing the infiltration area of the LVL for structure of the present invention.

[0080] FIG. 6 is to explain the infiltration area of the LVL for structure of the present invention, FIG. 6(A) is a three-dimensional explanatory drawing in which the infiltration area on the front surface side and the infiltration area on the back surface side are drawn separately, and FIG. 6(B) is a three-dimensional explanatory drawing in which the infiltration area on the front surface side and the infiltration area on the back surface side are drawn superimposed.

[0081] FIG. 7 is an enlarged view of the main part of according to another embodiment.

EMBODIMENT TO CARRY OUT THE INVENTION

[0082] Hereinafter, the embodiments of the present invention will be explained by referring to the drawings.

(Overview)

[0083] The wood containing the fireproofing chemical for wood materials for fire-resistant structure in this embodiment is a LVL 61 for structure in which a plurality of sheets of raw material veneers 51 are laminated together via an adhesive layer.

[0084] As shown in FIG. 1(A), the raw material veneer 51 may be a material in which a sapwood section A, white line band B, heartwood aged section C and heartwood unaged section D of a coniferous tree such as Japanese cedar or diffused porous broad-leaved tree are mixed, or as shown in FIG. 1(B), may be a material constituted only by a sapwood section A of a coniferous tree such as Japanese cedar or diffused porous broad-leaved tree. The raw material veneers 51 are all arranged so that their fibers extend along the longitudinal direction (arrow direction) of the LVL 61 for structure shown in FIG. 2 and FIG. 3.

(Production of LVL 61 for Structure)

[0085] In general, lumber is often broadly classified into a sapwood section and a heartwood section, it is said that the sapwood section is referred to be the whitish colored area around the periphery in the cross section of a log, while the heartwood section is referred to be the reddish colored area in the center in the cross section of a log, and more specifically, the heartwood section can be distinguished into two areas of the immature area and the mature area in the center, and there may also be a case where a white line band in the boundary region between the sapwood section and the heartwood section may exist. Accordingly, as shown in FIG. 1, it can be divided into four areas from the outside: the sapwood section A, the white line band B, the heartwood aged section C and the heartwood unaged section D, and in the present invention, the terms the heartwood section simply refer to the area including the white line band B, heartwood aged section C and heartwood unaged section D.

[0086] In the present invention, as shown in FIG. 1(A), not only the sapwood section A, which has good fluid movement, but also the heartwood section, which has relatively poor fluid movement may be used, or may be a mixture of them, or, as shown in FIG. 1(B), only the sapwood section A may be used, where fluid movement of the liquid is well performed in the direction of fiber extending inside the wood.

(Raw Material Veneer 51)

[0087] The raw material veneer 51 is obtained from these parts, and the LVL 61 for structure is produced by arranging the raw material veneer 51 with the direction of extending fiber (longitudinal direction of the standing timber) in the longitudinal direction and laminating.

[0088] The raw material veneer 51 is produced by cutting the standing timber as raw material into a predetermined thickness using a rotary lathe that allows for lathe checks. In this process, in FIG. 1(B), it is necessary to distinguish only the sapwood section A from the remaining the white line band B, the heartwood aged section C and the heartwood unaged section D from the sapwood section A, but in FIG. 1(A), it is not necessary to distinguish them so that it is advantageous in terms of collection of the material.

[0089] The raw material veneer 51 is processed into LVL 61 for structure of specified dimensions through processes such as cutting, drying, adhesion, lamination and cutting, the processes thereof can be conducted in the same manner as in the normal LVL producing process. Also, since LVL 61 for structure is generally thick and has a large cross section, adhesion and lamination may be repeated over multiple times. For example, when obtaining a LVL 61 for structure of 100 mm thickness from raw material veneers having about 2 to 4 mm thickness (in some cases, 1 mm or less), approximately 25 sheets to 100 sheets or more raw material veneers are laminated, but, instead of adhering and laminating the desired number of raw material veneers at one time, it may produce LVL 61 for structure having a thickness of 100 mm by making a lamination thickness of 50 mm in a first lamination and adhering them together in a second lamination.

[0090] Since FIG. 2 and FIG. 4 are drawings for explaining the structure, the raw material veneer 51 is shown to be a larger thickness and several sheets less than they actually are, but as understood from the above explanation, in practice, a large number of thin raw material veneers 51 are laminated and implemented.

[0091] Alternatively, the LVL 61 for structure may be compacted laminates that are compressed in the thickness direction. This LVL 61 for structure is made of a plurality of raw material veneers 51 laminated in the thickness direction (T) and can be implemented with [0092] width (W): 45 mm to 900 mm, [0093] thickness (T): 30 mm to 210 mm, [0094] length (L): 1,800 mm to 9,000 mm,
and the raw material veneers 51 and the adhesive between the raw material veneers 51 form at least one of the top and bottom injection holes 62.

(With Regard to Injection Hole 62)

[0095] In the LVL 61 for structure on which the raw material veneers 51 are laminated, many injection holes 62 are formed.

[0096] In the following explanation, the thickness direction of lamination of the raw material veneer 51 will be explained as (T), the width direction will be as (W) and the length direction will be as (L), respectively.

[0097] As shown in FIG. 2(A), FIG. 2(B) and FIG. 3, many injection holes are formed by drilling process on the flat grain surfaces of front and back of the LVL 61 for structure (flat grain surface 11 on the front side and flat grain surface 21 on the back side).

[0098] Assuming that the chemical liquid such as fireproofing chemical 31 moves fluidly mainly in the fiber direction, injection holes 62 having substantially circular in cross section which extends across the fibers of the LVL 61 for structure, are formed with a drilling tool such as a drill. The diameter of the injection holes 62 can be drilled deeper when the size is larger, but the larger the hole, the lower the mechanical performance such as strength, bending Young's modulus so that it is determined by taking the drilling depth into consideration and, in general, it is preferably about 3 mm to 15 mm.

[0099] The injection holes 62 are holes having circular in cross section extending from the front and back plate flat grain surfaces toward the thickness (T) direction and can be implemented as holes having a depth of a half the plate thickness or more. The injection holes 62 (upper injection holes 62(U) from front surface and lower injection holes 62(D) from back surface) are arranged in a plurality of rows on the front and back flat grain surfaces (flat grain surface 11 at front side and flat grain surface 21 at back side) and are arranged in multiple in the width direction (W) in each row, respectively.

[0100] The upper injection holes 62(U) and lower injection holes 62(D) can be implemented, for example, when the cross-sectional dimension of the LVL is 150 mm×150 mm, with a hole diameter of about 3 mm to 15 mm (preferably 5 mm to 10 mm) and a depth of 75 mm. The depth of the injection holes 62 may be greater than 75 mm in consideration of variations during processing.

[0101] In short, it is sufficient if all the raw material veneers 51 are reached by either one of the injection holes 62 of the upper injection holes 62(U) or lower injection holes 62(D), and the lengths of the upper injection holes 62(U) and lower injection holes 62(D) may be different.

(Arrangement Form of Injection Holes 62)

[0102] As shown in FIG. 3, the injection holes 62 of the front and back (the upper injection holes 62(U) or lower injection holes 62(D)) are so formed that the interval in the fiber direction (lengthwise direction=L) in each row of, for example, L1=200 mm to 300 mm for LVL mixed with Japanese cedar sapwood section, and the interval between each row in the direction perpendicular to the fiber (width direction=W) W1=30 mm to 60 mm in the direction perpendicular to the fiber (width direction=W).

[0103] These intervals can be implemented by changing, and it is preferable to use that: [0104] an interval L1 between injection holes in the fiber direction is 100 mm to 300 mm, and [0105] an interval W1 between injection holes in the direction perpendicular to the fiber is 25 mm to 60 mm.

[0106] Incidentally, in this embodiment, in each row of injection holes 62 on the front and back surfaces adjacent to each other in the lengthwise direction L, the interval in the fiber direction (lengthwise direction=L) is shifted by half a pitch (in this example, W1/2=10 mm). Also, in each row of injection holes 62 on the front and back surfaces adjacent to each other in the width direction W, the interval in the fiber direction (lengthwise direction=L) is shifted by half a pitch (in this example, L1/2=100 mm). According to this, each of the injection holes 62 (upper injection hole 62(U) and lower injection hole 62(D)) of this LVL 61 for structure are arranged in a staggered manner on the front side and back side, respectively.

[0107] In addition, the arrangement of the upper injection holes 62(U) from the front surface and the lower injection holes 62(D) from the back surface is arranged in a grid pattern by shifting them by half a pitch in the lengthwise direction (L) and the width direction (W). That is, the upper injection hole 62(U) from the front surface and the lower injection hole 62(D) from the back surface are set to as L2=100 mm in the fiber direction (interval in the lengthwise direction (L)). The interval between each row in the direction perpendicular to the fiber (interval in the width direction (W)) is set to as W2=10 mm.

[0108] The above interval between each row in the direction perpendicular to the fiber (width direction=W) is the distance between the centers of adjacent holes.

[0109] When chemical agents are injected into adhered wood materials such as LVL and a laminated lumber, the adhesive layer formed by solidifying the adhesive between the raw material veneers form a wall, whereby infiltration of the chemical aqueous solution is prevented. Therefore, infiltration of the aqueous solution in the direction of the flat grain (W) perpendicular to the fiber is possible, but in the lamination direction, infiltration beyond the thickness of the veneer becomes difficult because the wall of solidified adhesive prevents infiltration. Thus, in order to achieve levelling of chemical agent infiltration into the LVL, it is necessary to infiltrate in the fiber direction by injecting through the injection holes formed in the lamination direction penetrating through the veneer and adhesive layer from the flat grain surface.

[0110] It is appropriate to determine the interval between the injection holes 62 with sufficient margin for infiltration in a preliminary test of staining solution injection, taking into consideration the item of wood material, the difference between the sapwood section and the heartwood section, the type of tree, and the regional differences where the tree has grown, etc.

[0111] It is advantageous in that the drilling process can easily form the injection holes 62 having a substantially circular cross section, and that the injection holes 62 having a substantially circular cross section can distribute the external load more uniformly than openings having polygonal in a cross section.

(Other Arrangement Forms)

[0112] Incidentally, as shown in FIG. 7, an arrangement form of the upper injection holes from the front surface is made a grid pattern, an arrangement form of the lower injection holes from the back side is made a grid pattern, and the arrangement of the injection holes on the front and back is formed by shifting sides by half a pitch to make a staggered manner as a whole. However, in this case, when focusing on each of the front side and the back side, the positions of injection holes in each row and each column coincide in the width direction and the lengthwise direction, so that the arrangement form shown in FIG. 3 is more advantageous from the viewpoint of suppressing lowering in mechanical performance.

(Injection of Chemical Agent)

[0113] The injection processing of the chemical agent is a step of injecting a fireproofing chemical into the LVL 61 for structure. Specifically, wood is completed by injecting an aqueous solution such as noncombustible, semi-incombustible or flame-retardant agents to the LVL 61 for structure using a decompression-pressurization injection can.

[0114] The injection amount of the chemical agent may be set according to the thickness of the raw material veneer 51 of the LVL 61 for structure, the type of tree and the regional differences in growth, and in the standard for Japanese cedar, it is appropriate to set about 150 kg/m 3 for the LVL 61 for structure with thickness of 150 mm.

[0115] Unlike lumber and laminated wood, there are no major differences in veneer laminates, but since the state of impregnation of the chemical liquid varies depending on the species and growth conditions, it is preferable to conduct and implement preliminary experiments using water-soluble colorants to confirm the depressurization conditions and time, pressurization conditions and time, and the number of repetitions.

[0116] Also, as for the injection amount for process control it is preferable to measure weights before and after injection and manage the differences as the average injection amount of the lot.

[0117] The fireproofing chemical 31 that enters the injection hole 62 through the openings provided on the front and back flat grain surfaces moves fluidly in the fiber direction, thereby infiltrating the fireproofing chemical 31 into the center portion of the thickness of the LVL 61 for structure.

[0118] When the wood is composed only of the heartwood section, as previously mentioned, fluid movement through the cells is hardly executed since the cell membrane of fine pores are closed in softwoods and fillers such as tylose is filled in hardwoods, however since the lathe checks of rotary veneers generate relatively large and numerous, the chemical agent infiltrates through the lathe checks of the rotary veneers as a passage, so that it is confirmed by the research by the inventor of the present application that when injection holes 62 are provided at intervals of 100 mm to 300 mm in the longitudinal direction, the fireproofing chemical 31 can infiltrate almost uniformly.

[0119] On the other hand, when the wood is composed only of the sapwood section, the lathe checks of the rotary veneer are relatively small and occur less frequently, since the cell membrane of fine pores are opened in softwoods and fillers such as tylose is not filled in hardwoods, fluid movement through the membrane pores and cell lumen easily occurs. Therefore, the chemical agent infiltrate through the membrane pores and cell lumen as a passage, so that it is confirmed by the research by the inventor of the present application that when the injection holes 2 are provided at the above-mentioned intervals, the fireproofing chemical 31 can infiltrate almost uniformly.

[0120] Therefore, by aligning the longitudinal direction of all the raw material veneers 51 constituting the LVL 61 for structure substantially with the fiber direction and the lengthwise direction of the lathe checks, regardless of whether the wood is composed only of the sapwood section, the wood is composed only of the heartwood section, or the wood is composed of mixture of the heartwood section and the sapwood section, when the injection holes 62 are provided at intervals of 100 mm to 300 mm in the longitudinal direction, the fireproofing chemical 31 can be almost uniformly infiltrated.

[0121] As shown in FIG. 4, it is appropriate to set the depth of the inside of the injection holes 62 of the LVL 61 for structure so as not to be spaced in the left-right width direction, preferably to be a half or more of the length in the width direction to the extent that parts thereof overlap. Further, as shown in FIG. 3 and FIG. 5, in a plane view of the LVL 61 for structure, it is preferable to provide the injection holes 62 in a staggered pattern alternating left and right in a position where they do not overlap each other on each of the front surface side and the back surface side, in the point of maintaining the strength of the finished wood.

[0122] More preferably, as shown in FIG. 3, those injection holes 62 are alternately provided left and right in a staggered pattern on each of the front surface side and the back surface side as well.

[0123] As shown in FIG. 5 and FIG. 6, by introducing and infiltrating the fireproofing chemical 31 to the LVL 61 for structure through the upper injection holes 62(U) on the surface of the LVL 61 for structure, infiltration areas 31 on the front surface side in which fireproofing chemical is infiltrated in the width direction and lengthwise direction from each of the injection holes are formed on each of laminated veneer around the upper injection hole 62(U). The infiltration areas 31 on the front surface side are arranged on the front surface side of the wood in the width direction and the lengthwise direction and overlap each other such that no areas remain between adjacent infiltration areas 31 that are not infiltrated with the fireproofing chemical.

[0124] Similarly, on each of the veneers around the lower injection hole 62(D) from the back surface, infiltration areas 41 on the back surface side in which the fireproofing chemical is infiltrated in the width direction and the lengthwise direction from each of the lower injection holes 62(D) are formed.

[0125] The infiltration areas 41 on the back surface side are arranged on the back surface side of the wood in the width direction and the lengthwise direction and overlap each other such that no areas remain between adjacent infiltration areas 41 that are not infiltrated with the fireproofing chemical.

[0126] The infiltration area 31 on the front surface and the infiltration area 41 on the back surface side are arranged overlapping each other such that no areas remain between the infiltration areas in the thickness direction that are not infiltrated with the fireproofing chemical.

[0127] According to this, the entire area of the wood becomes infiltration areas with the fireproofing chemical.

(Steps after Injection)

[0128] Curing: It is preferable to carry out curing for leveling the injected chemical agents inside the wood, and the curing period is determined by preliminary experiments.

[0129] Drying: in order to meet the quality of the product as determined by agreement with the customer, moisture content is controlled. From viewpoint of improvement of quality, it is preferable to carry out artificial drying.

[0130] Finish processing: In order to satisfy the prescribed requirements of a product, the product is subjected to finish processing such as rip-sawing or band-sawing for the width of the board, cross-cut-sawing for the length, and a sander or planer for the surface.

[0131] Inspection: In order to satisfy the quality of a product, necessary inspection is carried out. For example, the thickness and the width are measured with a caliper or a tape measure made of steel, the length is measured with a tape measure made of steel, and appearance and surface quality are checked visually and by touch.

[0132] Packing: The products are subjected to necessary packing such as covering on six sides to keep out moisture from outside air or covering with kraft paper and fixing with tape to prevent damage from the cargo.

[0133] The wood according to this embodiment can exhibit substantially uniform and good fire-resistance performance as a fire-resistant modified wood material as a whole. When wood material in which chemical agent is insufficiently injected in a part of areas is heated, flammable gases are generated from the wood tissue of the insufficiently injected areas by reaching a high temperature range of around 200° C. or higher, and the said gases ignite. As a result, although the fire-resistance performance thereof is greatly impaired, the wood of the present invention is impregnated substantially entire areas with a sufficient amount of fire-resistant agent, so that flammable gas generation from the wood tissue is suppressed and the carbonized layer of chemical agent on the wood surface blocks the air, thereby achieving a stable fire-resistance performance.

EXAMPLES

[0134] Hereinafter, Examples will be shown in order to enhance the understanding of the invention, but the present invention should not be understood as restricted to this Examples.

Example 1

[0135] Species of raw material veneer: cypress [0136] Thickness of raw material veneer: 3 mm

[0137] The raw material veneers were laminated through a water-soluble adhesive to prepare LVL for structure having the following dimensions. The number of samples was made 30 (Examples 1-1 to 1-30). [0138] Width of LVL for structure: 90 mm [0139] Thickness of LVL for structure: 45 mm [0140] Length of LVL for structure: 1,200 mm

[0141] Injection holes were formed in the form shown in FIG. 3 on the obtained “before processing” LVL for structure from the flat grain surface of the front side and the flat grain surface of the back side, respectively, according to the following conditions in order to obtain “after processing” LVL for structure. [0142] w1: 60 mm [0143] L1: 200 mm [0144] Length (depth) in thickness direction: 25 mm [0145] Diameter: 5 mm

Example 2

[0146] Species of raw material veneer: Poplar [0147] Thickness of raw material veneer: 2 mm

[0148] The raw material veneers were laminated through a water-soluble adhesive to prepare LVL for structure with the following dimensions. The number of samples was made 30 (Examples 2-1 to 2-30). [0149] Width of LVL for structure: 110 mm [0150] Thickness of LVL for structure: 40 mm [0151] Length of LVL for structure: 1,200 mm

[0152] Injection holes were formed in the form shown in FIG. 3 on the obtained “before processing” LVL for structure from the flat grain surface of the front side and the flat grain surface of the back side, respectively, according to the following conditions in order to obtain “after processing” LVL for structure. [0153] W1: 60 mm [0154] L: 200 mm [0155] Length (depth) in thickness direction: 20 mm [0156] Diameter: 5 mm

[0157] The following bending tests were carried out on LVL for structure “before processing” and LVL for structure “after processing” of Example 1 and Example 2, and the obtained bending Young's modulus is shown in Table 1. The tests were conducted in accordance with the test method of the Japanese Agricultural Standard JAS 0701-1 Bending Test 4.9, using the following method.

Bending Test

[0158] In the test, the upper limit of load and the lower limit of load, the corresponding deflection, and the maximum load were measured in the proportional range under the relevant temperature and humidity conditions, and the bending Young's modulus was calculated based on the measurement results.

[0159] For each of Example 1 (1-1 to 1-30) and Example 2 (2-1 to 2-30), the bending Young's modulus “before processing”, the bending Young's modulus “after processing”, and the ratio of both are shown in Table 1. In Table 2, the maximum value (max), minimum value (min), average value (ave), standard deviation (σ), and lower limit standard (ave-3σ) of the number of 30 samples, and the ratio of the average value of “before processing” to the average value of “after processing” are shown.

TABLE-US-00001 TABLE 1 Example 1 Example 2 1/ 2/ 1/ 2/ Before After Before After Exam- pro- pro- Exam- pro- pro- ple cessing cessing 2/1 ple cessing cessing 2/1 1-1 11.46 10.78 0.94 2-1 11.16 10.72 0.96 1-2 11.47 10.84 0.95 2-2 11.15 11.06 0.99 1-3 11.41 10.87 0.95 2-3 12.23 11.85 0.97 1-4 11.81 11.31 0.96 2-4 12.09 11.84 0.98 1-5 11.22 10.85 0.97 2-5 12.16 11.76 0.97 1-6 11.85 11.31 0.95 2-6 12.12 11.79 0.97 1-7 10.9 10.55 0.97 2-7 11.42 10.99 0.96 1-8 11.48 10.89 0.95 2-8 11.93 11.27 0.94 1-9 11.39 10.90 0.96 2-9 11.87 11.43 0.96 1-10 11.48 10.91 0.95 2-10 11.67 11.27 0.97 1-11 12.02 11.39 0.95 2-11 12.07 11.5 0.95 1-12 11.14 10.62 0.95 2-12 11.98 11.44 0.95 1-13 11.68 11.15 0.95 2-13 11.2 10.66 0.95 1-14 12.06 11.39 0.94 2-14 11.39 11.03 0.97 1-15 11.15 10.77 0.97 2-15 11.74 11.38 0.97 1-16 11.46 10.94 0.95 2-16 11.53 11.15 0.97 1-17 11.46 11.04 0.96 2-17 11.31 10.84 0.96 1-18 11.63 11.14 0.96 2-18 11.42 11.19 0.98 1-19 11.48 11.17 0.97 2-19 10.90 10.61 0.97 1-20 11.64 10.93 0.94 2-20 10.77 10.41 0.97 1-21 11.01 10.58 0.96 2-21 11.29 10.95 0.97 1-22 11.93 11.14 0.93 2-22 10.68 10.34 0.97 1-23 11.83 11.17 0.94 2-23 10.73 10.34 0.96 1-24 11.36 10.88 0.96 2-24 12.74 12.18 0.96 1-25 11.88 11.06 0.93 2-25 12.7 12.42 0.98 1-26 11.48 10.68 0.93 2-26 12.26 11.97 0.98 1-27 11.19 10.33 0.92 2-27 12.19 11.93 0.98 1-28 11.48 11.1 0.97 2-28 11.93 11.91 1.00 1-29 11.59 10.86 0.94 2-29 11.57 11.08 0.96 1-30 11.74 10.52 0.90 2-30 11.85 11.87 1.00

TABLE-US-00002 TABLE 2 Example 1 Example 2 Before After Before After processing processing processing processing max 12.06 11.39 max 12.74 12.42 min 10.9 10.33 min 10.68 10.34 ave 1/11.52 2/10.94 ave 1/11.67 2/11.31 σ 0.28485 0.261466 σ 0.540075 0.553839 ave-3σ 10.67 10.15 ave-3σ 10.05 9.64 2/1 0.949 2/1 0.969

[0160] As is clear from the results in Table 1 and Table 2, the change in bending Young's modulus between “before processing” and “after processing” was limited to around 0.95, intending that the effect of the reduction in bending Young's modulus due to cross-sectional defects could be suppressed, and it was confirmed that appropriate quality control could be performed after setting the lower limit standard. In addition, as mentioned above, a fireproofing chemical injected from the injection holes 62 is uniformly present in this LVL for structure, so that it exhibits the prescribed noncombustible performance. Therefore, it was possible to provide a LVL for structure that achieves both uniform injection of the fireproofing chemical and suppression of the effect of the reduction in bending Young's modulus due to cross-sectional defects.

EXPLANATION OF REFERENCE NUMERALS

[0161] 11 . . . Flat grain surface of front side [0162] 21 . . . Flat grain surface of back side [0163] 31 . . . Infiltration area on front surface side [0164] 41 . . . Infiltration area on back surface side [0165] 51 . . . Raw material veneer [0166] 61 . . . LVL for structure [0167] 62 . . . Injection hole [0168] 62(U) . . . Upper injection hole [0169] 62(D) . . . Lower injection hole [0170] A . . . Sapwood section [0171] B . . . White line band [0172] C . . . Heartwood aged section [0173] D . . . Heartwood unaged section