Manufacturing method and manufacturing apparatus of synthetic wood

Abstract

To provide a synthetic wood having a woody pattern similar to that of natural wood.SOLUTION: The present invention is directed to a manufacturing method of a synthetic wood, that coats an outer surface of an inner layer body 11 formed by extruding an inner layer material N using a main extruder 4, with a surface layer body 15 formed by extruding a surface layer material using a sub-extruder 6, to manufacture a synthetic wood 1 having a woody pattern. The surface layer material includes a surface layer base material H, and master batches M1 and M2 for applying color tone. The surface layer base material H is directly fed to an inlet part of the sub-extruder 6, and the master batches M1 and M2 are directly fed to the inlet part of the sub-extruder 6 in a state in which the feeding amount can be varied.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] This invention relates to a method and apparatus for producing synthetic wood with a woody pattern, in which an inner layer body formed by extruding an inner layer material using a main extruder is covered with a surface layer body formed by extruding a surface layer material using a sub-extruder, thereby producing synthetic wood with a woody pattern. [Background technology]

[0002] Synthetic wood (artificial wood), which is made from molded synthetic resins, can effectively utilize by-products such as scrap wood and sawdust, and is also durable and strong.In recent years, thanks to improvements in processability and design, synthetic wood appears comparable to natural wood, and it has attracted attention as an excellent product with high practicality.

[0003] Synthetic wood is, for example, composed of a resin molded product made by two-layer extrusion molding, which has an inner layer placed in the center (inside) and a surface layer covering the outer surface (outer periphery) of the inner layer.

[0004] Well-known methods for producing such synthetic wood include those shown in Patent Documents 1 and 2. These methods use a main extruder that feeds the molding material (inner layer material) that will become the inner layer into a two-layer extrusion mold, and a sub-extruder that feeds the molding material (surface layer material) that will become the surface layer, a surface base material, and a color and pattern material (pigment, masterbatch, etc.), into the two-layer extrusion mold.

[0005] In the method shown in Patent Document 1, the inner layer material fed by the main extruder is molded into an inner layer body using a mold, while the surface layer base material and pigment fed by the sub-extruder are molded into a surface layer body using a mold so as to cover the inner layer body, thereby producing synthetic wood.

[0006] In addition, in the method shown in Patent Document 2, an inner layer body is formed in the same manner as above, while a surface layer base material and a master batch are mixed in a mixing section, and then sent to a sub-extruder where a surface layer body is formed to cover the inner layer body, thereby producing synthetic wood.

[0007] In the synthetic wood produced in this way, the color and pattern material added to the surface material is molded before it is completely mixed, so that the color and pattern material appears on the surface of the surface in streaks with moderate fluctuations and varying shades, forming a wood grain pattern similar to that of natural wood.

[0008] In particular, in the manufacturing apparatus shown in Patent Document 2, the surface layer base material and master batch are mixed in a mixing section, so the mixture stored in the mixing section basically has the same fixed wood grain pattern, and different wood grain patterns cannot be produced unless a mixture with a different mixture is next stored in the tank. Therefore, even if one wants to produce wood grain patterns with more strict variations, the wood grain pattern can only be changed after all the material stored in the mixing section has been used. In other words, the pattern can only be changed in units of the amount of mixture stored in the mixing section (tank), and it is not possible to express finer shades of wood grain patterns. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 5566943 [Patent Document 2] Patent No. 6751216 Summary of the Invention [Problem to be solved by the invention]

[0010] Under such a technical background, there is a current demand in the field of synthetic wood technology to make the color and pattern of synthetic wood products, such as grain patterns, more similar to those of natural wood.

[0011] The present invention has been made in view of the above-mentioned problems, and aims to provide a method and an apparatus for producing synthetic wood that can produce synthetic wood with a grain pattern and other color patterns similar to those of natural wood. [Means for solving the problem]

[0012] In order to solve the above problems, the present invention comprises the following means.

[0013] [1] A method for producing synthetic wood with a woody pattern, in which an inner layer body formed by extruding an inner layer material using a main extruder is coated on the outer surface of the inner layer body formed by extruding a surface layer material using a sub-extruder, The surface layer material includes a surface layer base material and a masterbatch that imparts a color tone, A surface layer base material is directly supplied to the inlet of the sub-extruder, A method for producing synthetic wood, characterized in that the masterbatch is directly supplied to the inlet of the sub-extruder in a variable supply amount.

[0014] [2] The surface base material contains polyolefin resin as its main component, 2. The method for producing synthetic wood according to claim 1, wherein the masterbatch contains a polyolefin resin as a base material.

[0015] [3] The method for producing synthetic wood according to the above item 1 or 2, wherein the amount of masterbatch supplied to the sub-extruder is changed stepwise at predetermined time intervals.

[0016] [4] The method for producing synthetic wood according to any one of the preceding paragraphs 1 to 3, wherein the masterbatch has a melting point higher than that of the surface layer base material.

[0017] [5] The method for producing synthetic wood according to any one of the preceding items 1 to 4, wherein the masterbatch comprises a first masterbatch and a second masterbatch having a different color tone from the first masterbatch.

[0018] [6] When the main color and pattern are expressed by the first masterbatch and the sub-color and pattern are expressed by the second masterbatch, 6. A method for producing synthetic wood as set forth in the preceding paragraph 5, wherein the amount of the first masterbatch supplied relative to the second masterbatch is ensured to be greater than that of the second masterbatch during 80% or more of the time period during which the surface layer material is supplied.

[0019] [7] A synthetic wood manufacturing apparatus for manufacturing synthetic wood with a wood pattern in which a surface layer is coated on the outer surface of an inner layer, a main extruder that extrudes an inner layer material to form an inner layer body; a sub-extruder for extruding a surface layer material containing a surface layer base material and a masterbatch for imparting a color tone to form a surface layer body; a surface layer base material supply means for directly supplying the surface layer base material to an inlet portion of the sub-extruder; a masterbatch supply means for directly supplying masterbatch to the inlet of the sub-extruder; a masterbatch supply amount changing means for arbitrarily changing the supply amount of the masterbatch, A synthetic wood manufacturing apparatus characterized in that no mixing means for mixing the surface layer base material and the master batch is present upstream of the sub-extruder. [Effects of the Invention]

[0020] According to the synthetic wood manufacturing method of invention [1], the surface layer base material and masterbatch are directly fed into the inlet of the sub-extruder, and the amount of masterbatch fed can be adjusted. This allows for the production of synthetic wood with a finer grain pattern and natural, fluctuating color patterns, similar to that of natural wood.

[0021] According to the synthetic wood manufacturing method of invention [2], the main component of the surface base material and the base material of the master batch are both made of polyolefin resin, which improves the compatibility between the surface base material and the master batch. This blurs the boundary between the base material portion of the surface base material and the colored and patterned portion of the master batch, allowing them to connect naturally and seamlessly, making it possible to more reliably form a wood grain pattern that is close to that of natural wood.

[0022] According to the synthetic wood manufacturing method of invention [3], the amount of masterbatch supplied is changed in stages, so that the color and pattern produced by the masterbatch changes continuously, with thick, dark streaks appearing in areas where the amount is high, and thin, light streaks appearing in areas where the amount is low. This results in the formation of a wide variety of irregular, natural color patterns, making it possible to produce a wood grain pattern that is even closer to that of natural wood.

[0023] According to the synthetic wood manufacturing method of invention [4], the base material of the masterbatch has a higher melting point than the surface base material, so the masterbatch can be molded in a mold in a semi-sintered state with a moderate degree of unevenness, making the synthetic wood more similar to natural wood.

[0024] According to the synthetic wood manufacturing method of invention [5], two types of masterbatches with different color tones are used, which makes it possible to more reliably express a naturally occurring wood grain pattern with a wide variety, and more reliably approximate the wood grain pattern of natural wood.

[0025] According to the synthetic wood manufacturing method of invention [6], the supply of the first masterbatch relative to the second masterbatch is ensured to be greater than 80% of the time period during which the surface layer material is supplied, so that the main color and pattern appear more widely and to a greater extent on the surface of the synthetic wood than the secondary color and pattern, ensuring the appearance of the desired wood grain pattern.

[0026] According to the synthetic wood manufacturing device of the invention [7], it is possible to provide a manufacturing device that can carry out the above manufacturing method invention.

[0027] In particular, since this synthetic wood manufacturing device does not have a mixing section for mixing the surface layer base material and master batch, when the blending amounts of the surface layer base material and master batch are changed, the shade of the wood grain pattern changes quickly due to the change in blending amounts. This allows the shade of the wood grain pattern to be changed finely in a short period of time, making it possible to form a wood grain pattern that is even closer to that of natural wood. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a cross-sectional view showing synthetic wood manufactured using an apparatus for manufacturing synthetic wood according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram for explaining the manufacturing apparatus according to the embodiment. [Figure 3] FIG. 3 is a graph showing the appearance and color state of synthetic wood obtained by the manufacturing method of Example 1 related to the present invention. [Figure 4] FIG. 4 is a graph showing the appearance and color state of synthetic wood obtained by the manufacturing method of Example 2 related to the present invention. [Figure 5] FIG. 5 is a graph showing the appearance and color state of synthetic wood obtained by the manufacturing method of Example 3 related to the present invention. [Figure 6] FIG. 6 is a graph showing the appearance and color state of synthetic wood obtained by the manufacturing method of Example 4 related to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] FIG. 1 is a cross-sectional view of synthetic wood 1 manufactured using a manufacturing apparatus according to an embodiment of the present invention. As shown in the figure, synthetic wood 1 is a molded product of synthetic resin formed by multilayer extrusion (two-layer extrusion), and is configured so that the cross-sectional shape perpendicular to the extrusion direction (longitudinal direction) is the same at any position. In this embodiment, synthetic wood 1 includes an inner layer 11 constituting the inside (center) and a surface layer 15 covering the outer surface of inner layer 11. Inner layer 11 includes an outer wall 12 having a rectangular cross section and a plurality of webs 13 bridging the upper and lower walls of outer wall 12, with hollows 14 formed between each of the webs 13 on outer wall 12. Surface layer 15 is formed in the shape of a skin so as to cover the entire outer surface of outer wall 12 of inner layer 11.

[0030] In the synthetic wood material 1 of this embodiment, the inner layer body 11 is composed of a molded body of the inner layer material N, and the surface layer body 15 is composed of a molded body of the surface layer material. The surface layer material is composed of a surface layer base material H and masterbatches M1 and M2.

[0031] Figure 2 is a block diagram showing a manufacturing apparatus of this embodiment that can produce the synthetic wood 1. As shown in the figure, this manufacturing apparatus basically comprises a two-layer extrusion molding die 2, an inner layer material supply section 3, an extrusion screw-type main extruder 4 that feeds the inner layer material N from the inner layer material supply section 3 to the die 2, a surface layer material supply section 5, and an extrusion screw-type sub-extruder 6 that feeds the surface layer material from the surface layer material supply section 5 to the die 2.

[0032] The interior material supply section 3 is provided with an inner layer material container 30 formed of a hopper or the like, and resin pellets as the inner layer material N are stored in the container 30.

[0033] The outlet of the inner layer material container 30 is connected to the inlet of the main extruder 4, and the inner layer material N in the inner layer material container 30 is supplied to the main extruder 4 by its own weight, melted and kneaded, and passes through the inner layer body forming hole of the mold 2 to form the inner layer body 11.

[0034] The surface layer material supply section 5 is equipped with a surface layer base material container 50, a first masterbatch container 51, and a second masterbatch container 52, each of which is constituted by a hopper or the like. The surface layer base material container 50 stores resin pellets as the surface layer base material H. The first and second masterbatch containers 51, 52 store resin pellets as the first and second masterbatches M1, M2, which are color and pattern materials, respectively.

[0035] The outlet of the surface layer base material container 50 is connected to the inlet of the auxiliary extruder 6, so that the surface layer base material H is supplied to the auxiliary extruder 6 by its own weight. A first masterbatch conveyor F1 of a conveying screw type is provided between the outlet of the first masterbatch container 51 and the inlet of the auxiliary extruder 6. This first masterbatch conveyor F1 is of a horizontal input type, and the first masterbatch M1 is supplied directly to the inlet of the auxiliary extruder 6 by this first masterbatch conveyor F1. Furthermore, a second masterbatch conveyor F2 of a conveying screw type is provided between the outlet of the second masterbatch container 52 and the inlet of the auxiliary extruder 6. This second masterbatch conveyor F2 is also of a horizontal input type, and the second masterbatch M2 is supplied directly to the inlet of the auxiliary extruder 6 by this second masterbatch conveyor F2.

[0036] In addition, a mold connection section 61 is provided between the sub-extruder 6 and the mold 2 .

[0037] As described above, the surface layer base material H and the first and second masterbatches M1 and M2 supplied to the sub-extruder 6 are melt-kneaded appropriately and supplied into the mold 2 via the mold connection part 61, and the mixed material passes through the surface layer forming hole of the mold 2 to form the surface layer 15 so as to cover the outer surface of the inner layer 11.

[0038] In the manufacturing apparatus of this embodiment, the surface layer material supply section 5 does not have any mixing means such as a mixer for mixing the materials H, M1, and M2 between each container 50-52 and the sub-extruder 6, and as already mentioned, each material H, M1, and M2 is supplied directly to the inlet of the sub-extruder 6.

[0039] In this embodiment, the outlet of the surface layer base material container 50 is configured as the surface layer base material supply means. Furthermore, the first and second masterbatch conveyors F1, F2 are configured as the masterbatch supply means (first and second masterbatch supply means) and as the masterbatch supply amount changing means (first and second masterbatch supply amount changing means).

[0040] The manufacturing apparatus of this embodiment also includes a control device (not shown), which controls the operation of the main extruder 4, the sub-extruder 5, and the first and second masterbatch conveyors F1 and F2 according to a preset program, thereby appropriately adjusting the extrusion speeds of the extruders 4 and 5 and the conveying speeds (supply amounts) of the masterbatch conveyors F1 and F2, thereby automatically producing synthetic wood 1.

[0041] In this embodiment, one type of masterbatch may be used as the color and pattern material, but it is preferable to use two or more types, as this will result in a more diverse color and pattern, making it possible to more closely resemble the color and pattern of natural wood.

[0042] In this embodiment, it is preferable to appropriately change the supply amount (addition amount) of masterbatches M1 and M2. For example, when extruding approximately 400 g of surface layer base material H per meter at a speed of 0.01 m / s, it is preferable to change the supply amount two to four times within one cycle, for example, approximately 80 to 100 seconds. This allows a wood grain pattern in which the pattern intensity changes continuously two to four times to be produced in a 2-meter synthetic wood product, creating a pattern with excellent design similar to that of natural wood.

[0043] In this embodiment, when approximately 400 g of surface material per meter is extruded at a speed of 0.01 m / s, adding masterbatches M1 and M2 for 10 seconds results in a synthetic wood product with a colored pattern (wood grain pattern) appearing over a range of approximately 25 cm in the longitudinal direction.

[0044] The duration of the masterbatch supply is preferably set to 10 to 50 seconds. That is, if this duration is too short, the changes in color and pattern are difficult to see when viewed on the finished product, and the desired wood grain pattern cannot be expressed, which is undesirable. Conversely, if the supply duration is too long, the changes in color and pattern are not continuous, resulting in an unnatural color and pattern with little variation, which is undesirable. The supply duration may be set to more than 50 seconds, but in this case, if the supply duration exceeding 50 seconds is set to 30% or less of the total time of one cycle, the changes in color and pattern can be formed continuously.

[0045] The amount of masterbatch supplied can be adjusted by the rotational speed and conveyance time of the masterbatch conveyors F1 and F2. In this embodiment, the rotational speed of the masterbatch conveyor F1 is expressed in "%", with the maximum rotational speed being 100% and the minimum rotational speed (stopped state) being 0%. In this embodiment, when approximately 400 g of surface layer material per meter is extruded at a speed of 0.01 m / s, the supply amount at 100% rotational speed corresponds to approximately 0.3 g / s. The rotational speed "%" and the supply amount "g / s" are proportional to each other. Furthermore, the rotational speed of each masterbatch conveyor F1 and F2 can be freely changed within the range of 0% to 100%, allowing for fine speed adjustment (color adjustment).

[0046] The rotation speed of each of the masterbatch conveyors F1 and F2 can be changed at any time interval, thereby allowing the supply rates of the masterbatches M1 and M2 to be appropriately adjusted, as described above. As described above, it is preferable to change the supply rates of the masterbatches M1 and M2 two to four times per cycle. In this embodiment, the supply rate can be changed up to eight times per cycle. The time for a set supply rate can be selected from a range of 0 to 999.9 seconds, allowing for supply over short or long time spans. Furthermore, in this embodiment, up to 10 patterns of rotation speed (supply rate) and supply time can be stored for each of the screw-type conveyors F1 and F2, allowing the operator to easily select a desired pattern and perform the operation efficiently.

[0047] In this embodiment, two types of masterbatches M1 and M2 are transported by individual masterbatch transporters F1 and F2, and the total maximum rotational speed of the two masterbatch transporters F1 and F2 is 200%, and the amount of change in the rotational speed of the two masterbatch transporters F1 and F2 can be changed within the range of 0% to 200%. In this embodiment, it is preferable to set this total rotational speed to 10% to 160%.

[0048] Furthermore, the rotation speed of each of the masterbatch conveyors F1 and F2 can be changed at any time interval.

[0049] In this embodiment, when two types of masterbatches M1 and M2 are used, it is desirable to add a larger amount of the masterbatch of the main color (e.g., M1) than the amount of the masterbatch of the other color or pattern (e.g., M2) (a sub-color or pattern). In this case, it is desirable to ensure that the amount of the masterbatch M1 of the main color or pattern is larger than the amount of the masterbatch M2 of the sub-color or pattern during 80% or more of the time period during which the surface layer material (surface layer base material H) is supplied to the sub-extruder 6.

[0050] The difference in the supply amount of the first masterbatch M1 relative to the second masterbatch M2 is preferably set to 5% or more.

[0051] In this embodiment, even if the supply amount of the masterbatch M1 to be used as the main component is appropriately changed and the masterbatch M2 to be used as the secondary component is supplied at a constant amount, it is possible to continuously create changes in the color and pattern of the synthetic wood product.

[0052] Immediately after the supply rates of masterbatches M1 and M2 are switched from the specified values ​​to 0%, some masterbatch remains in the sub-extruder 6, mold 2, etc., so it takes some time for the color and pattern on the surface of the molded product (synthetic wood) to completely disappear.

[0053] For masterbatches M1 and M2, it is preferable to use a resin with a lower melt flow rate than the surface layer base material H as the base material (base material, matrix), and to use a coloring component such as a pigment or dye, especially a pigment, as appropriate. Resins with a lower melt flow rate have a higher melt viscosity and lower fluidity than resins with a higher melt flow rate, so they are incorporated into the surface layer material in a moderate state that is not completely mixed, which allows for the expression of a natural color and pattern that changes continuously. Furthermore, by using a resin with a higher melting point than the surface layer base material H, masterbatches M1 and M2 can be incorporated into the surface layer material in a moderate state that is not completely mixed.

[0054] When the main component of the surface layer base material H is an olefin-based resin, it is preferable to use a similar olefin-based resin as the base resin for the masterbatches M1 and M2. If the base material of the masterbatches M1 and M2 and the main component of the surface layer base material H are different resins, excessive or insufficient compatibility may cause surface peeling of the masterbatches M1 and M2 or an extreme deterioration in physical properties, which is not preferable.

[0055] Suitable examples of olefin resins include high density polyethylene and polypropylene resins (homopolymer, block copolymer, or random copolymer) which have a relatively high melting point and a wide range of melt flow rate grades.

[0056] The pellet size of the masterbatches M1 and M2 may be the same as that of the surface layer base material H, but it is preferable to use a size larger than that of the surface layer base material H, as this allows for the expression of a wood grain pattern that is closer to that of natural wood.

[0057] It is preferable to use masterbatches M1 and M2 having a melting point higher than that of the surface layer base material H, preferably 20°C or more higher. That is, when the surface layer base material H and the masterbatches M1 and M2 are melt-kneaded by the sub-extruder 6, the masterbatches M1 and M2 are not completely melted and are contained in the surface layer base material H in an uneven, semi-kneaded state. For this reason, when the surface layer base material H is molded using the mold 2, the uneven masterbatches M1 and M2 can form a naturally occurring color and pattern (wood grain pattern) that is not artificial, making it possible to produce synthetic wood 1 that resembles natural wood.

[0058] As with the base materials of the masterbatches M1 and M2, it is preferable to use an olefin resin as the main component of the surface layer base material H. Examples of olefin resins include polyethylene resin, polypropylene resin, ethylene-vinyl acetate copolymer resin, and ethylene-propylene diene, but it is particularly preferable to use high-density polyethylene resin, which is suitable for synthetic wood applications.

[0059] In this embodiment, the surface layer base material H contains a filler such as an organic filler or an inorganic filler.

[0060] Examples of organic fillers include wood flour, kenaf, bamboo flour, straw, paper, etc., with wood flour being the main filler, and finely ground sawdust being preferred. Examples of inorganic fillers include calcium carbonate, talc, mica, etc.

[0061] The fillers may be used alone or in combination of two or more. Needless to say, wood flour may also be used in combination with an inorganic filler or an organic filler.

[0062] The surface layer base material H is preferably granulated in advance as pellets containing the above-mentioned resin as the main component, the above-mentioned filler, and, if necessary, additives, coloring components such as pigments and dyes, etc. Regarding the granulator for granulating the surface layer base material H, it is preferable to use a twin-screw extruder in order to improve the mixing effect.

[0063] The content of filler such as wood flour in the surface layer base material H is about 5 to 20% by weight. Furthermore, the content of the surface layer base material H in the surface layer material is about 85 to 97% by weight, and the content of the masterbatches M1 and M2 is about 3 to 15% by weight, more preferably about 5% by weight.

[0064] The color tones of the surface layer base material H and the masterbatches M1 and M2 can be, for example, four patterns 1 to 4 shown in Table 1 below.

[0065] [Table 1]

[0066] As shown in Table 1, in pattern 1, the surface layer base material H and the first masterbatch M1 are brown, and the second masterbatch M2 is rose brown.

[0067] In pattern 2, the surface layer base material H and the first masterbatch M1 are dark brown, and the second masterbatch M2 is rose brown.

[0068] In pattern 3, the surface layer base material H is white, the first masterbatch M1 is brown beige, and the second masterbatch M2 is light brown.

[0069] In pattern 4, the surface layer base material H is gray, the first masterbatch M1 is dark gray, and the second masterbatch M2 is yellow-beige.

[0070] The color pattern to be used as the main color may be either the first masterbatch M1 or the second masterbatch M2, but in this embodiment it is the first masterbatch M1.

[0071] In this embodiment, it is preferable that one of the masterbatches M1 and M2 has a color similar to that of the surface layer base material H, and the other has a completely different color.

[0072] Specifically, using the color difference represented by ΔE, it is preferable that the ΔE of the first masterbatch M1 is set to 5 or more relative to the surface layer base material H. It is preferable that the ΔE of the second masterbatch M2 is set to 7 or more relative to the surface layer base material H. It is preferable that the ΔE between the first and second masterbatches M1 and M2 is set to 2 or more.

[0073] The general color difference levels are as follows:

[0074] ΔE=1: A level where the difference between two colors can be distinguished when compared side by side ΔE = 2-3: The difference between two colors can be seen even when they are separated by a certain distance ΔE=5: The difference between the two colors can be seen regardless of the viewing conditions. It is preferable to use an olefin resin as the main component of the inner layer material N. Specifically, suitable examples include polyethylene resin and polypropylene resin.

[0075] The inner layer material N is usually made by adding fillers, additives, etc. to the above resin as the main component, as required, and then pelletizing the mixture.

[0076] In this embodiment, the content of the inner layer material N in the entire components of the synthetic wood 1 is about 90% by weight, and the content of the surface layer material (surface layer base material H+master batches M1, M2) is about 10% by weight.

[0077] In this embodiment, the synthetic wood material 1 shown in FIG. 1 is produced by the production apparatus shown in FIG. 2 using the inner layer material N, surface layer base material H, and first and second masterbatches M1 and M2.

[0078] That is, the inner layer material N, the surface layer base material H, and the first and second masterbatches M1 and M2 are stored in the inner layer material container 30, the surface layer base material container 50, and the first and second masterbatch containers 51 and 52. As described above, the inner layer material N supplied from the inner layer material container 30 to the main extruder 4 is melt-kneaded and passed through the mold 2 to form the inner layer body 11, and the surface layer base material H supplied from the surface layer base material container 50 to the sub-extruder 6 and the first and second masterbatches M1 and M2 supplied from the first and second masterbatch containers 51 and 52 to the sub-extruder 6 via the first and second masterbatch conveyors F1 and F2 are appropriately melt-kneaded and passed through the mold 2 to form the surface layer body 15, thereby producing the synthetic wood 1.

[0079] In this embodiment, the masterbatch conveyors F1 and F2 employ screws with a diameter of 6 mm.

[0080] In this embodiment, during the manufacturing process of synthetic wood 1, when the inner layer material N in the inner layer material container 30 decreases and falls below a predetermined amount, the inner layer material N is automatically added to the inner layer material container 30. Similarly, when the surface layer base material H and the first and second masterbatches M1, M2 in the surface layer base material container 50 and the first and second masterbatch containers 51, 52 decrease, the surface layer base material H and the first and second masterbatches M1, M2 are automatically added to the surface layer base material container 50 and the first and second masterbatch containers 51, 52 as appropriate.

[0081] [Table 2]

[0082] Here, in this embodiment, an example of the set temperature of the sub-extruder 6 is shown. For example, as shown in Table 2 and FIG. 2, the set temperature of zone C1 in the supply section, which is located upstream within the cylinder of the sub-extruder 6, is 155°C; the set temperature of zone C2 in the compression section, which is located in the middle region within the cylinder, is 160°C; the set temperature of zone C3 in the metering section, which is located downstream within the cylinder, is 175°C; the set temperature of adapter section AD, which connects the sub-extruder 6 to the mold connection section 61, is 175°C; and the set temperatures of D1 and D2, which are located within the mold connection section 61, are 175°C and 180°C, respectively. Note that if the set temperature is too high, the pattern (masterbatches M1 and M2) will melt and become thinner, which is undesirable. If the set temperature is too low, the masterbatches M1 and M2 that make up the color and pattern will not be evenly dispersed throughout due to insufficient melting, which is undesirable because the material will remain unmelted.

[0083] The screw shape of the sub-extruder 6 is not particularly limited, but a full-flight screw without a kneading section is more preferable than a Dulmage screw with a kneading section. This is because the Dulmage of the Dulmage screw makes it easier for the materials (masterbatches M1 and M2) to melt, and the color pattern tends to be lighter even with normal sub-extruder settings.

[0084] In this embodiment, the synthetic wood 1 obtained by the above-described manufacturing apparatus can be subjected to surface treatment such as sanding to make it more similar to the grain of natural wood. For example, by polishing the surface of the synthetic wood 1 with sandpaper, numerous irregular scratches can be made on the surface of the synthetic wood, making it more similar to natural wood.

[0085] Furthermore, because the masterbatches M1 and M2 are present irregularly in the thickness direction of the surface base material H, the shape and color of the color pattern can be varied by changing the scraping depth and the grit (type) of sandpaper, making it possible to further approximate natural wood. Furthermore, by scraping the surface with sandpaper, fine irregularities are formed, giving the surface a warm wood grain feel and making it even more similar to natural wood.

[0086] As described above, in the synthetic wood manufacturing method of this embodiment, the surface layer base material H and the masterbatches M1 and M2 are supplied directly to the inlet of the sub-extruder 6 without being mixed, and therefore the masterbatches M1 and M2 are melted and kneaded in the sub-extruder 6 and fed into the mold 2 before being completely mixed with the surface layer base material H. As a result, the masterbatches M1 and M2 are not completely melted within the surface layer base material H and are molded in the mold 2 in an uneven semi-molten state, and the masterbatches M1 and M2 appear on the surface of the surface layer 15 as naturally varying colors and patterns, making it possible to produce synthetic wood 1 having a wood grain pattern similar to that of natural wood.

[0087] Furthermore, in this embodiment, when the masterbatches M1 and M2 have a melting point higher than that of the surface layer base material H, the masterbatches M1 and M2 can be molded in the mold 2 in a semi-sintered state with a moderate degree of unevenness, so that the surface of the synthetic wood 1 can be made to more closely resemble natural wood.

[0088] Furthermore, in this embodiment, when the main component of the surface base material H and the base material of the masterbatches M1 and M2 are both made of polyolefin resin, the compatibility between the surface base material H and the masterbatches M1 and M2 is improved, and the boundary between the base material portion of the surface base material H and the colored and patterned portion of the masterbatches M1 and M2 is blurred, allowing the two to blend together naturally and seamlessly, making it possible to more reliably form a wood grain pattern on the surface of the synthetic wood that is similar to that of natural wood.

[0089] Furthermore, when polyolefin resin is used as the surface layer material, synthetic wood 1 can be obtained that is strong, resistant to deterioration, and highly durable.

[0090] Furthermore, in this embodiment, when the supply amounts of the masterbatches M1 and M2 are appropriately changed, the color and pattern patterns produced by the masterbatches M1 and M2 undergo continuous changes, with thick, dark streaks appearing in areas where the supply amount is large and thin, light streaks appearing in areas where the supply amount is small, resulting in the formation of a wide variety of irregular color and patterns, making it possible to produce a wood grain pattern that is even closer to that of natural wood.

[0091] Furthermore, in this embodiment, when two types of masterbatches M1 and M2 with different color tones are used, the different colors change and mix in a variety of ways, thereby producing a naturally occurring wood grain pattern rather than an artificial one, which can more reliably approximate the pattern of natural wood.

[0092] Furthermore, in this embodiment, when the primary color and pattern are expressed by the first masterbatch M1 and the secondary color and pattern are expressed by the second masterbatch M2, if the supply rate of the first masterbatch M1 relative to the second masterbatch M2 is ensured to be large for 80% or more of the time period during which the surface layer material is supplied to the secondary extruder 6, the primary color and pattern will be expressed more than the secondary color and pattern on the surface of the synthetic wood 1, and it is possible to reliably produce a desired color and pattern pattern that is well-balanced in appearance. [Example]

[0093] As the inner layer material N, a resin composition containing wood flour as the main component, high density polyethylene resin, talc, a lubricant, and additives, was pelletized and prepared.

[0094] As the surface layer base material H, a resin composition containing wood flour, talc, a lubricant, and a coloring pigment in a high density polyethylene resin as a main component was pelletized and prepared.

[0095] As the first masterbatch M1, which is the main color and pattern material, a resin composition containing a brown pigment A and a dispersant in a polypropylene resin base material was prepared by pelletizing it.

[0096] As the second masterbatch M2, which is the color and pattern material to be used as a secondary material, a resin composition containing a brown pigment B and a dispersant in a polypropylene resin base material was prepared by pelletizing it.

[0097] These materials N, H, M1, and M2 were stored in the respective containers 30, 50, 51, and 52 of the manufacturing apparatus shown in FIG. 2, and extrusion processing was carried out under the following conditions to manufacture the synthetic wood 1 shown in FIG.

[0098] Example 1 The inner layer material N was supplied to the main extruder 4 and fed into the mold 2 at an extrusion rate of approximately 37.5 g / sec to form the inner layer body 11, while the surface layer material consisting of the surface layer base material H and the first and second masterbatches M1 and M2 was supplied to the sub-extruder 6 and fed into the mold 2 at an extrusion rate of approximately 4 g / sec to form the surface layer body 15 so as to cover the inner layer body 11. In this case, the molding speed of the synthetic wood 1 (the outflow speed of the molded product from the mold 2) was approximately 1.0 cm / sec.

[0099] The amounts of the first and second masterbatches M1 and M2 supplied from the first and second masterbatch containers 51 and 52 to the sub-extruder 6 (the amounts conveyed by the first and second masterbatch conveyors F1 and F2) were set to the following conditions.

[0100] [Table 3]

[0101] [Table 4]

[0102] As shown in Tables 3 and 4, in the first and second masterbatch conveyors F1 and F2, sections (1) to (7) constitute one cycle, and in section (1), the first masterbatch M1 was supplied to the auxiliary extruder 6 at 99.0% rotation speed for 45.0 seconds, and the second masterbatch M2 was supplied to the auxiliary extruder 6 at 70.0% rotation speed. Note that when the rotation speed of the conveyors F1 and F2 is 100%, this corresponds to a conveying amount (supply amount) of approximately 0.6 g / sec of the conveyors F1 and F2.

[0103] In section (2) following section (1), the first masterbatch M1 was fed at 20.0% and the second masterbatch M2 was fed at 15.0% for 30.0 seconds. In section (3), the first and second masterbatches M1 and M2 were supplied at 60% and 40% for 35.0 seconds; in section (4), the first and second masterbatches M1 and M2 were supplied at 20.0% and 15.0% for 30.0 seconds; in section (5), the first and second masterbatches M1 and M2 were supplied at 80.0% and 60.0% for 40.0 seconds; in section (6), the first and second masterbatches M1 and M2 were supplied at 50.0% and 20.0% for 35.0 seconds; and in section (7), the first and second masterbatches M1 and M2 were supplied at 20.0% and 15.0% for 30.0 seconds.

[0104] In Example 1, the supply amount (addition amount) of the first masterbatch M1 is kept greater than the supply amount (addition amount) of the second masterbatch M2 in all sections (all time periods).

[0105] Fig. 3 shows a graph illustrating the appearance color state of the synthetic wood 1 of Example 1 obtained in this manner. In this graph, the horizontal axis represents the length (cm) of the synthetic wood 1, which correlates with the molding time, and the vertical axis represents the amount (%) of color and pattern due to the first and second masterbatches M1 and M2.

[0106] As is clear from the graph in Figure 3, the amount of color and pattern changes continuously, resulting in a naturally occurring color and pattern with fluctuations, and it is clear that a wood grain pattern close to that of natural wood can be expressed.

[0107] <Example 2>

[0108] [Table 5]

[0109] [Table 6]

[0110] As shown in Tables 5 and 6, the supply amounts of masterbatches M1 and M2 were set for each of the sections (1) to (8), which constitute one cycle. Except for this, synthetic wood 1 of Example 2 was produced in the same manner as in Example 1. A graph of the appearance color state of the synthetic wood of Example 2 is shown in Figure 4. As is clear from the graph in Figure 4, although the amount of color and pattern changed periodically, a continuous change was maintained, resulting in a naturally occurring color and pattern with fluctuations, and it was possible to express a wood grain pattern similar to that of natural wood.

[0111] In Example 2 as well, the supply amount (addition amount) of the first masterbatch M1 was kept greater than the supply amount (addition amount) of the second masterbatch M2 in all sections (all time periods).

[0112] Example 3

[0113] [Table 7]

[0114] [Table 8]

[0115] As shown in Tables 7 and 8, the first masterbatch M1 had one cycle consisting of sections (1) to (7), and the second masterbatch M1 had one cycle consisting of sections (1) to (8), and the amounts of masterbatches M1 and M2 supplied were set for each section. Except for this, synthetic wood 1 of Example 3 was produced in the same manner as in Example 1. A graph of the appearance color state of the synthetic wood of Example 3 is shown in Figure 5. As is clear from the graph in Figure 5, the color and pattern amount changed continuously, resulting in a naturally occurring color and pattern with fluctuations, and it can be seen that a wood grain pattern similar to that of natural wood was produced.

[0116] In Example 3, in some sections (time periods) among all the sections, the supply amount of the first masterbatch M1 was greater than the supply amount of the second masterbatch M2, and in the remaining sections (time periods), the supply amount of the first masterbatch M1 was less than the supply amount of the second masterbatch M2.

[0117] Example 4

[0118] [Table 9]

[0119] [Table 10]

[0120] As shown in Tables 9 and 10, the first masterbatch M1 had one cycle consisting of sections (1) to (7), and the second masterbatch M1 had one cycle consisting of sections (1) to (3), and the supply amounts of masterbatches M1 and M2 were set for each section. Except for this, synthetic wood 1 of Example 4 was produced in the same manner as in Example 1. A graph of the appearance color state of the synthetic wood of Example 4 is shown in Figure 6. As is clear from the graph in Figure 6, although the amount of color and pattern changed periodically, a continuous change was maintained, resulting in a naturally occurring color and pattern with fluctuations, and it can be seen that a wood grain pattern similar to that of natural wood was produced.

[0121] In Example 4, the duration of the supply amount exceeding 50 seconds is set to 30% or less of the total time of one cycle. [Industrial Applicability]

[0122] The synthetic wood manufacturing method of the present invention can be suitably used to manufacture synthetic wood having a wood grain or other woody pattern in which the outer surface of an inner layer is covered with a surface layer. [Explanation of symbols]

[0123] 1:Synthetic wood 11: Inner layer 15: Surface body 2:Mold 4: Main extruder 5: Surface material supply section 6: Sub-extruder H: Surface base material M1: 1st masterbatch M2: Second masterbatch N: Inner layer material

Claims

1. A method for producing synthetic wood with a woody pattern, comprising the steps of: forming an inner layer body by extruding an inner layer material using a main extruder; covering the outer surface of the inner layer body with a surface layer body by extruding a surface layer material using a sub-extruder; The surface layer material includes a surface layer base material and a masterbatch that imparts a color tone, A surface layer base material is directly supplied to the inlet of the sub-extruder, A method for producing synthetic wood, characterized in that the masterbatch is directly supplied to the inlet of the sub-extruder in a variable supply amount.

2. The surface base material contains polyolefin resin as its main component, 2. The method for producing synthetic wood according to claim 1, wherein the masterbatch contains a polyolefin resin as a base material.

3. 3. The method for producing synthetic wood according to claim 1, wherein the amount of masterbatch supplied to said sub-extruder is changed stepwise at predetermined time intervals.

4. 3. The method for producing synthetic wood according to claim 1, wherein the master batch has a melting point higher than that of the surface layer base material.

5. 3. The method for producing synthetic wood according to claim 1, wherein the masterbatch comprises a first masterbatch and a second masterbatch having a different color tone from that of the first masterbatch.

6. When the main color and pattern are expressed by the first masterbatch and the secondary color and pattern are expressed by the second masterbatch, 6. The method for producing synthetic wood according to claim 5, wherein the amount of the first masterbatch supplied is greater than the amount of the second masterbatch supplied in 80% or more of the time period during which the surface layer material is supplied.

7. A synthetic wood manufacturing apparatus for manufacturing synthetic wood having a woody pattern in which an outer surface of an inner layer body is covered with a surface layer body, a main extruder that extrudes an inner layer material to form an inner layer body; a sub-extruder for extruding a surface layer material containing a surface layer base material and a masterbatch for imparting a color tone to form a surface layer body; a surface layer base material supply means for directly supplying the surface layer base material to an inlet portion of the sub-extruder; a masterbatch supply means for directly supplying masterbatch to the inlet of the sub-extruder; a masterbatch supply amount changing means for arbitrarily changing the supply amount of the masterbatch, A synthetic wood manufacturing apparatus characterized in that no mixing means for mixing the surface layer base material and the master batch is present upstream of the sub-extruder.

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