Palm trunk veneer laminate and its manufacturing method

Abstract

To realize a palm trunk laminated veneer that can be used for wooden structures by making full use of the composition of palm trunks that is not suitable for boards. [Solution] The palm tree trunk veneer laminate 5 is made by compactly stacking multiple veneers 1 impregnated with phenolic resin obtained from palm tree trunks, and in the compacted stacked state, the veneers 1 are firmly self-adhered to each other by the interaction between the phenolic resin and the adhesive components originally contained in the veneers 1. On the front and back of the laminated veneers 1, veneers 4 impregnated with phenolic resin obtained from sources other than palm tree trunks are compactly joined by self-adhesion.

Description

[Technical Field]

[0001] The present invention relates to a palm trunk laminated veneer sheet and a method for producing the same. [Background technology]

[0002] Patent Document 1 proposes a laminated veneer sheet that can be used in wooden structures in harsh environments in order to effectively utilize thinned wood and other conventional hardwood materials. This laminated veneer sheet is made by laminating inner layer veneers made of multiple hardwood sheets impregnated with a preservative with an adhesive, and then laminating surface layer veneers impregnated with phenolic resin on both sides of the laminated inner layer veneers with an adhesive, resulting in a laminated veneer sheet with excellent preservative effect and dimensional stability. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 11-105005 Summary of the Invention [Problem to be solved by the invention]

[0004] Palm wood, such as the trunk of an oil palm (hereafter referred to as palm trunk), is composed of 71-76% by weight of vascular bundles and 24-29% by weight of parenchyma, and also has a high moisture content. Furthermore, the parenchyma is said to contain approximately 10% by weight of free sugars such as sucrose, glucose, and fructose, and approximately 5% by weight of starch. Veneers obtained by drying such palm trunks contain voids and have low density and mechanical strength, as measured by bending strength and bending modulus. This makes it difficult to obtain laminated veneer that can be used in wooden structures, as is the case with conventional hardwoods.

[0005] The present invention aims to solve these problems by making full use of the above-mentioned composition of palm tree trunks, which is not suitable for boards, to realize a palm tree trunk veneer laminate that can be used for wooden structures. [Means for solving the problem]

[0006] In order to achieve the above object, the palm tree trunk laminated veneer body (5) of the first invention is obtained from palm tree trunks, low molecule Phenolic resin Fully impregnated A plurality of veneers (1) are compactly stacked, and each veneer (1) is in the compacted stacked state. low molecule The phenolic resin and the adhesive components originally contained in the veneer (1) interact to form a strong self-adhesion. , flexural strength 60.1-89.1MPa, flexural modulus 9.0-12.6GPa .

[0007] In this first invention, the phenolic resin liquid penetrates the porous palm trunk veneers extremely efficiently by capillary action, and the veneers are strongly self-adhered to each other during consolidation due to interaction with adhesive components such as free sugars and starch originally contained in the veneers. The mechanical strength of this veneer laminate is sufficiently high, for example, a bending strength of approximately 60 MPa and a bending modulus of approximately 9.0 GPa, making it suitable for use in wooden structures. Incidentally, the mechanical strength of veneers not impregnated with phenolic resin is, for example, approximately 20 MPa in bending strength and approximately 3.0 GPa in bending modulus.

[0008] In the second invention, the laminated veneers (1) are provided on the front and back sides thereof with: Palm tree trunk The veneer (4) impregnated with phenolic resin obtained from sources other than palm tree trunks is consolidated by self-adhesion. Here, the veneer (4) obtained from sources other than palm tree trunks refers to veneer obtained from wood such as chestnut, cypress, and cedar, and includes sawn boards.

[0009] In the second invention, the mechanical strength of the laminate is further improved, for example, with a bending strength in the range of 60.0 to 90.0 MPa and a bending modulus in the range of 9.0 to 13.0 GPa, and the water resistance is improved, resulting in good weather resistance.

[0010] In the method for producing the palm tree trunk laminated veneer (5) of the third invention, the veneer (1) obtained from the palm tree trunk is whole10 to 50 parts by weight of the veneer low molecule Phenol resin aqueous solution Impregnation by capillary action After that, the laminate is dried until the moisture content reaches 5 to 15%, and then a plurality of the dried veneers are stacked and compacted in the stacking direction at a temperature of 120 to 180°C and a pressure of 2.0 to 5.0 MPa for 5 to 60 minutes.

[0011] In the manufacturing method of the palm tree trunk laminated veneer body (5) of the fourth invention, the above-mentioned veneer is applied to the front and back of the dried and laminated veneer (1), respectively. Palm tree trunk The board material obtained from other than the above is treated with an aqueous solution of phenolic resin in the same proportion as the veneer. Impregnation The laminated sheets are then stacked to form a veneer (4), and compacted in the stacking direction at a temperature of 120 to 160°C and a pressure of 3.0 to 3.5 MPa for 5 to 30 minutes.

[0012] The symbols in parentheses above indicate, for reference, the correspondence with specific means described in the embodiments to be described later. [Effects of the Invention]

[0013] As described above, the palm trunk veneer laminate of the present invention makes full use of the composition of palm trunks, which is not suitable for boards, and can realize a palm trunk veneer laminate that can be used for wooden structures. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic cross-sectional view showing the manufacturing process of a palm tree trunk laminated veneer body. FIG. [Figure 2] 1 is a schematic cross-sectional view showing the manufacturing process of a palm tree trunk laminated veneer body. FIG. [Figure 3] 1 is a schematic cross-sectional view showing the manufacturing process of a palm tree trunk laminated veneer body. FIG. [Figure 4] 1 is a schematic cross-sectional view showing the manufacturing process of a palm tree trunk laminated veneer body. FIG. [Figure 5] 1 is a schematic cross-sectional view showing the manufacturing process of a palm tree trunk laminated veneer body. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] The embodiments described below are merely examples, and various design improvements made by those skilled in the art without departing from the gist of the present invention are also included in the scope of the present invention.

[0016] Palm trunks are stripped to a thickness of approximately 4–5 mm using a rotary lathe and cut to a predetermined length. The veneers 1 are then dried to a moisture content of 5–15%. As shown in Figure 1, these veneers are stacked with battens 2 sandwiched between them (batten stacking). As shown in Figure 2, these veneers are then immersed in a liquid tank 3 filled with phenolic resin L to impregnate the veneers 1 with the phenolic resin L (hot-dip dipping). Because palm trunk veneers 1 have numerous voids, simple hot-dip dipping allows for efficient impregnation with the phenolic resin through capillary action. The preferred phenolic resin is an aqueous low-molecular-weight phenolic resin with a molecular weight of 50–300 and a solids content of 10–50%. The impregnation amount is 10–50 parts by weight per 100 parts by weight of veneer, i.e., 10–50%.

[0017] After impregnation with phenolic resin L, the stacked veneers 1 are lifted out of the liquid tank 3 and the resin is removed (Figure 3), and then dried in a drying device until the moisture content of each veneer 1 reaches 5 to 15%.

[0018] Next, a predetermined number of veneers 1 are stacked, and if weather resistance is required, as shown in Figure 4, veneer sheets 4 about 2 mm thick made from wood other than palm trunks, such as cypress, chestnut, or cedar, each impregnated with phenolic resin in the same proportion as the veneers 1, are layered on top of each other, and the resulting laminated veneer sheet 5 is obtained by hot pressing for 5 to 60 minutes at a temperature of 120 to 180°C and a pressure of 2.0 to 5.0 MPa (Figure 5). The veneer sheets 4 can be impregnated with phenolic resin using a vacuum press or by hot-dip dipping each sheet in the same manner as papermaking.

[0019] The palm trunk laminated veneer 5 obtained in this way is strongly self-adhered to each other due to the interaction between the impregnated phenolic resin and the adhesive components originally contained in the veneers 1, which greatly improves the mechanical strength. Furthermore, if sliced ​​veneers 4 are self-adhesively joined to the front and back of the laminated veneers 1, it will exhibit excellent water resistance and it will be possible to further improve the mechanical strength of the laminated veneer 5.

[0020] (Examples and Comparative Examples) Examples of the present invention and comparative examples are shown below in Table 1. Note that the bending strength of untreated (not impregnated with phenolic resin) unlaminated veneers obtained by peeling palm tree trunks is about 20 MPa, and the bending modulus is about 3.0 GPa.

[0021] [Table 1]

[0022] In Example 1, three sheets of treated veneer 1 impregnated with 20% phenolic resin were laminated (20% ph-3ply) and hot-pressed at a temperature of 160°C and a pressure of 3.5 MPa for five minutes without any veneer. The resulting laminated veneer body 5 had poor water resistance, but a flexural strength of 65.0 MPa and a flexural modulus of 9.0 GPa, greatly improving its mechanical strength. Therefore, the laminated veneer body 5 can be effectively used as an interior structural material where weather resistance is not required.

[0023] On the other hand, as shown in Comparative Example 1, when three untreated veneers 1 were stacked together without any veneer, even after heat pressing at a temperature of 180°C and a pressure of 3.5 MPa for 18 minutes, i.e., at a higher temperature for a longer period of time, the veneer laminate 5 had a bending strength of 44.0 MPa and a bending modulus of 7.9 GPa, which means that the mechanical strength was insufficient and the water resistance of JAS Class 1 was not satisfied.

[0024] Furthermore, as shown in Comparative Example 2, when five untreated veneers 1 were stacked together without any veneer, even after being heated and pressed for a long period of time (30 minutes) at a temperature of 120°C and a pressure of 3.0 MPa, the veneer laminate 5 had a bending strength of 23.7 MPa and a bending modulus of 5.3 GPa, significantly reducing its mechanical strength. When immersed in room temperature water for 15 hours, the laminate peeled off and had no water resistance whatsoever.

[0025] In Example 2, three sheets of treated veneers 1 impregnated with 20% phenolic resin were laminated together, and chestnut veneer 4 impregnated with 20% phenolic resin was placed on each side of the laminated veneers 1, followed by heat pressing at a temperature of 160°C and a pressure of 3.5 MPa for 10 minutes. The resulting laminated veneer body 5 exhibited high mechanical strength (flexural strength of 72.1 MPa and flexural modulus of elasticity of 9.3 GPa) as well as good water resistance. Therefore, the laminated veneer body 5 can be effectively used as an exterior structural material that requires weather resistance.

[0026] In Example 3, three laminated veneers each impregnated with 20% phenolic resin were stacked together, and chestnut veneers impregnated with 20% phenolic resin were placed on both sides of the laminated veneers. The laminated veneer assembly 5 was then heated and pressed at 160°C and 3.5 MPa for 20 minutes. The resulting laminated veneer assembly 5 exhibited high mechanical strength (flexural strength: 60.1 MPa, flexural modulus: 9.1 GPa) and also exhibited good water resistance. Therefore, it can be effectively used as an exterior structural material that requires weather resistance.

[0027] In Example 4, three sheets of treated veneers 1 impregnated with 30% phenolic resin were laminated together, and then two pieces of cypress veneer 4 impregnated with 30% phenolic resin were placed on the front and back of each laminated veneer 1, followed by heat pressing at a temperature of 120°C and a pressure of 3.0 MPa for 30 minutes. The resulting laminated veneer body 5 exhibited even greater mechanical strength, with a bending strength of 89.1 MPa and a bending modulus of elasticity of 12.0 GPa, as well as good water resistance. Therefore, the laminated veneer body 5 can be effectively used as an exterior structural material that requires weather resistance.

[0028] In Example 5, five sheets of treated veneers 1 impregnated with 30% phenolic resin were laminated together, and then two pieces of cypress veneer 4 impregnated with 30% phenolic resin were placed on the front and back of each laminated veneer 1, followed by heat pressing at a temperature of 120°C and a pressure of 3.0 MPa for 30 minutes. The resulting laminated veneer body 5 exhibited sufficient mechanical strength (flexural strength of 78.0 MPa and flexural modulus of elasticity of 12.6 GPa) as well as good water resistance. Therefore, the laminated veneer body 5 can be effectively used as an exterior structural material that requires weather resistance.

[0029] As shown in Comparative Example 3, when five untreated veneers 1 were stacked together without any veneer, the veneer laminate 5 had a bending strength of 6.8 MPa and a bending modulus of 3.3 GPa even after being heated and pressed for a long period of 30 minutes at a temperature of 120°C and a pressure of 3.0 MPa.

[0030] As shown in Comparative Example 4, when five untreated veneers 1 were stacked and untreated veneer 4 was placed on the front and back of each of the stacked veneers 1, the veneer 4 did not adhere to the stacked veneers 1 even after being heated and pressed at a temperature of 120°C and a pressure of 3.0 MPa for 30 minutes. [Explanation of symbols]

[0031] 1... veneer, 2... crosspiece, 3... liquid tank, 4... veneer, 5... laminated veneer body.

Claims

1. A palm tree trunk veneer laminate is formed by compacting and laminating multiple veneers obtained from palm tree trunks, each of which is entirely impregnated with a low molecular weight phenolic resin. In the compacted and laminated state, the veneers are firmly self-adhered to one another by the interaction between the low molecular weight phenolic resin and an adhesive component originally contained in the veneers. The laminate exhibits a bending strength of 60.1 to 89.1 MPa and a bending modulus of elasticity of 9.0 to 12.6 GPa.

2. The palm tree trunk veneer laminate according to claim 1, wherein veneers impregnated with phenolic resin obtained from sources other than the palm tree trunk are self-adhesively consolidated on the front and back of the laminated veneers.

3. A method for producing a palm trunk veneer laminate, comprising: impregnating an entire veneer obtained from palm tree trunks with an aqueous solution of low molecular weight phenolic resin in a ratio of 10 to 50 parts by weight per 100 parts by weight of the veneer through capillary action; drying the veneer until the moisture content reaches 5 to 15%; stacking multiple dried veneers; and compacting the stacked veneers in the stacking direction at a temperature of 120 to 180°C and a pressure of 2.0 to 5.0 MPa for 5 to 60 minutes.

4. The method for producing a palm tree trunk veneer laminate according to claim 3, wherein a veneer made from a material other than the palm tree trunk, which has been impregnated with a phenolic resin aqueous solution in the same proportion as the veneer, is further laminated on the front and back of the dried and laminated veneer, and the laminate is then compacted in the lamination direction at a temperature of 120 to 180°C and a pressure of 2.0 to 5.0 MPa for 5 to 60 minutes.

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