JP2010280186A - Manufacturing method for fiber board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a fiber board, capable of preventing easily a fiber mat from being adhered to a conveyer when pressurized heatedly, even when containing an acid-modified thermoplastic resin. <P>SOLUTION: This manufacturing method for the fiber board includes a fiber mat forming process for forming the fiber mat by mixing a vegetable fiber and a thermoplastic resin fiber containing the acid-modified thermoplastic resin, an aqueous dispersion applying process for spray-applying an aqueous dispersion of the thermoplastic resin, on both faces of the fiber mat, and a heating pressurizing process for obtaining the fiber board by heating-pressurizing the fiber mat applied with the aqueous dispersion between the pair of conveyers. The aqueous dispersion is applied preferably to bring 1-15 pts.mass of thermoplastic resin contained in the aqueous dispersion with respect to 100 pts.mass of the fiber mat, in the aqueous dispersion applying process. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a fiber board. More specifically, the present invention relates to a method for producing a fiber board containing a large amount of vegetable fiber.

  In recent years, plant resources such as kenaf that have grown in a short period of time and have a large amount of carbon dioxide absorption have attracted attention from the viewpoint of reducing carbon dioxide emissions and fixing carbon dioxide. Moreover, the utilization as a composite material using the material which compounded this plant resource with the thermoplastic resin is anticipated, and the manufacturing method of the fiber board using such a plant resource is known (following Patent Document 1).

JP 2006-95918 A

A fiber board using vegetable fibers is manufactured by heating and pressing a fiber mat obtained by mixing vegetable fibers and thermoplastic resin fibers with a double belt type hot plate. Further, for the purpose of improving the mechanical properties of the fiber board, the thermoplastic resin fiber may be blended with an acid-modified thermoplastic resin. When this acid-modified thermoplastic resin is blended, the heating At the time of pressurization, the compressed fiber mat may stick to a metal conveyor. In this case, there is a problem that if the surface is forcibly peeled off, the surface of the fiber board is damaged, or the fiber board itself is broken so that the design is deteriorated. Furthermore, this causes a reduction in production efficiency and a cost load. In order to prevent such sticking to a conveyor, conventionally, a method is known in which a fiber mat is sandwiched between release sheets having excellent release properties such as tetrafluoroethylene during heating and pressurization.
However, since the release sheet is a consumable item, there are inconveniences that it is necessary to stop the line at the time of replacement, and there is a cost problem that the release sheet itself is expensive.

  The present invention solves the above-described conventional problems, and even when an acid-modified thermoplastic resin is contained, the fiber can easily prevent the fiber mat from sticking to the conveyor during heating and pressurization. An object is to provide a method for manufacturing a board.

The present invention is as follows.
(1) A method for producing a fiber board having a structure in which plant fibers are bound together by a thermoplastic resin,
A fiber mat forming step in which a vegetable mat and a thermoplastic resin fiber containing an acid-modified thermoplastic resin are mixed to form a fiber mat;
An aqueous dispersion application step of spray-applying an aqueous dispersion of a thermoplastic resin on both surfaces of the fiber mat;
And a heating and pressurizing step of heating and pressurizing the fiber mat coated with the water dispersion between a pair of conveyors to obtain a fiber board.
(2) The fiber mat according to (1), wherein the fiber mat is 30 to 95% by mass when the total of the vegetable fiber and the thermoplastic resin fiber is 100% by mass. Board manufacturing method.
(3) In the aqueous dispersion application step, the aqueous dispersion is applied so that the thermoplastic resin contained in the aqueous dispersion is 1 to 15 parts by mass with respect to 100 parts by mass of the fiber mat. The manufacturing method of the fiber board as described in (1) or (2).
(4) The thermoplastic resin fiber contains the acid-modified thermoplastic resin and a non-acid-modified thermoplastic resin, and when the total is 100% by mass, the acid-modified thermoplastic resin is 0. The manufacturing method of the fiber board in any one of said (1) thru | or (3) which is 5-15 mass%.
(5) The said thermoplastic resin fiber and the said water dispersion are both the manufacturing methods of the fiber board in any one of said (1) thru | or (4) containing polyolefin.
(6) The fiber board manufacturing method according to any one of (1) to (5), wherein the vegetable fiber is a kenaf fiber.

According to the fiber board manufacturing method of the present invention, even when an acid-modified thermoplastic resin is contained, the fiber mat can be easily prevented from sticking to the conveyor during heating and pressurization. Thereby, the fiber board provided with the outstanding mechanical characteristic and design property can be manufactured efficiently and at low cost.
When the total amount of plant fiber and thermoplastic resin fiber is 100% by mass, when the plant fiber is 30 to 95% by mass, excellent mechanical properties and A fiber board having design properties can be manufactured efficiently and at low cost.
When the aqueous dispersion is applied so that the thermoplastic resin contained in the aqueous dispersion is 1 to 15 parts by mass with respect to 100 parts by mass of the fiber mat in the aqueous dispersion application step, a particularly excellent release effect is obtained. can get. Therefore, a fiber board having excellent mechanical properties and design properties can be manufactured more efficiently and at low cost.
When the thermoplastic resin fiber contains an acid-modified thermoplastic resin and a non-acid-modified thermoplastic resin, and the total is 100% by mass, the acid-modified thermoplastic resin is 0.5 to 15% by mass. In this case, excellent releasability by using the method of the present invention can be obtained particularly effectively.
When both the thermoplastic resin fiber and the aqueous dispersion contain polyolefin, a fiber board having particularly excellent mechanical properties and design properties can be obtained.
When plant fiber is kenaf fiber, kenaf is an annual plant that grows in a short period of time and has excellent carbon dioxide absorption, etc., so it reduces the amount of carbon dioxide in the atmosphere and effectively uses forest resources. Can contribute.

It is a schematic diagram which shows an example of the fiber board manufacturing apparatus which manufactures a fiber board according to the process of this invention.

The present invention will be described in detail below.
The method for producing a fiber board of the present invention is a method for producing a fiber board having a structure in which plant fibers are bound together by a thermoplastic resin, and includes a fiber mat forming step, an aqueous dispersion coating step, and a heating treatment. And a pressing step.

<Fiber mat forming process>
The “fiber mat forming step” is a step of mixing a vegetable fiber and a thermoplastic resin fiber containing an acid-modified thermoplastic resin to form a fiber mat.

  The “vegetable fiber” is not particularly limited as long as it is a fiber made of a plant-derived material. These plant fibers include kenaf, jute hemp, manila hemp, sisal hemp, husk, cocoon, cocoon, banana, pineapple, coconut palm, corn, sugar cane, bagasse, palm, papyrus, cocoon, esparto, sabaigrass, wheat, rice, bamboo , Fibers made of plants such as various conifers (cedar, cypress, etc.), various hardwoods, and cotton. Only 1 type of this vegetable fiber may be used and it may use 2 or more types together. Of these, kenaf fibers are preferred. Kenaf is an annual plant that grows in a short period of time and has excellent carbon dioxide absorbency. Therefore, when kenaf fiber is used, it contributes to the reduction of the amount of carbon dioxide in the atmosphere and the effective use of forest resources. Can do.

  Moreover, the site | part of the plant body used as plant fiber is not specifically limited, Any site | parts which comprise plant bodies, such as a non-wood part (bast etc.), a wood part, a leaf part, a stem part, and a root part, may be sufficient. Furthermore, only a specific part may be used and two or more different parts may be used in combination. In particular, in the kenaf, kenaf fibers obtained from bast are particularly preferable.

  The kenaf in the present invention is a kenaf that is a fast-growing annual grass having a woody stem. This kenaf is a plant classified into the mallow family, and includes hibiscus cannabinus and hibiscus sabdariffa in scientific names, and further, red linseed, cuban kenaf, western hemp, taykenaf, mesta, bimli, ambali hemp, etc. Is included. Moreover, as a vegetable fiber used for this invention, a jute fiber other than the said kenaf fiber can also be used preferably. Jute fiber is a fiber obtained from jute hemp. Examples of jute hemp include jute (Chorus, Cors capsularis L.), hemp (Tunaso), hemp containing Shimana and Morohaya, and linden plants.

The average fiber length and the average fiber diameter of the vegetable fiber are not particularly limited, but the average fiber length is preferably 10 mm or more. If the average fiber length is 10 mm or more, it is easy to obtain a fiber mat by mixing with thermoplastic resin fibers (especially, entanglement between fibers is easily formed), and the mechanical properties of the resulting fiber board are improved. Can be made.
The average fiber length of the vegetable fiber is 10 to 150 mm, particularly 20 to 100 mm, and more preferably 30 to 80 mm. Within this fiber length range, mixing for obtaining a fiber mat is easier, and the mechanical properties of the resulting fiber board can be further improved. In addition, this average fiber length is based on JIS L1015, takes out the single fiber one by one at random by the direct method, straightly stretches it without extending | stretching, measures a fiber length on a measuring scale, about 200 in total It is the average value of the measured values.

  Moreover, it is preferable that the average fiber diameter of a vegetable fiber is 1 mm or less. If the average fiber diameter is 1 mm or less, the mechanical properties of the fiber board can be improved. The average fiber diameter is 0.001 to 0.5 mm, particularly 0.01 to 0.2 mm, and more preferably 0.02 to 0.1 mm. In addition, this average fiber diameter is an average value of the values measured by observing the fiber diameter in the central part in the length direction of the vegetable fiber whose fiber length was measured with an optical microscope.

  The “thermoplastic resin fiber” contains an acid-modified thermoplastic resin (hereinafter also referred to as “acid-modified resin”) and a non-acid-modified thermoplastic resin (hereinafter also referred to as “non-acid-modified resin”). To do. This thermoplastic resin fiber is usually obtained by melt spinning an acid-modified resin and a non-acid-modified resin together.

  The “acid-modified thermoplastic resin” is a thermoplastic resin into which an acid group has been introduced. Although the kind of this acid group is not specifically limited, Usually, they are a carboxylic anhydride residue (-CO-O-OC-) and / or a carboxylic acid residue (-COOH). The acid group may be introduced by any compound, and the acid group-introducing compound includes maleic anhydride, itaconic anhydride, succinic anhydride, glutaric anhydride, an adipic anhydride and the like, and maleic acid. Examples thereof include carboxylic acids such as acid, itaconic acid, fumaric acid, acrylic acid and methacrylic acid. These may be used alone or in combination of two or more. Of these compounds, acid anhydrides are preferred, maleic anhydride and itaconic anhydride are more preferred, and maleic anhydride is particularly preferred.

  Furthermore, the kind of thermoplastic resin (hereinafter referred to as “skeleton resin”) which is a skeleton constituting the acid-modified resin is not particularly limited, and various thermoplastic resins can be used. Examples of the skeleton resin include polyolefin, polyester, polystyrene, acrylic resin (resin using methacrylate and / or acrylate), polyamide, polycarbonate, polyacetal, and ABS resin. Examples of the polyolefin include polypropylene, ethylene-propylene copolymer resin, and polyethylene. Examples of the polyester include aliphatic polyesters such as polylactic acid, polycaprolactone, and polybutylene succinate, and aromatic polyesters such as polyethylene terephthalate, polytrimethylene terephthalate, and polybutylene terephthalate. Among these, polyolefin is preferable.

  Specific examples of the acid-modified resin include a product name “Yumex” (particularly “Umex 1001” and “Yumex 1010”, etc.) manufactured by Sanyo Chemical Industries, Ltd., a product name “Admer” manufactured by Mitsui Chemicals, Inc. (Especially “Admer QE800” and the like are preferable), trade name “Modic” (particularly “Modic-AP P908” and the like are preferable) manufactured by Mitsubishi Chemical Corporation, and product name “Toyo Tack” manufactured by Toyo Kasei Kogyo Co., Ltd. ("Toyotac H-1100P-P" and the like are particularly preferable).

  The amount of the acid group introduced into the acid-modified resin is not particularly limited, but when the acid value is used as an index, the acid value may be 5 or more (usually 80 or less), and the acid value is preferably 15 or more. That is, an acid-modified resin having a relatively high acid value is preferable. With such an acid-modified resin, plant fibers can be sufficiently bound together while suppressing the content of the acid-modified resin. Furthermore, it is easy to produce a thermoplastic resin fiber having a suitable fineness. The acid value is preferably 15 to 70, more preferably 20 to 60, and even more preferably 23 to 30. This acid value can be measured according to JIS K0070.

  Further, the molecular weight of the acid-modified resin is not particularly limited, but the weight average molecular weight is preferably 10,000 to 200,000, particularly preferably 10,000 to 100,000. That is, an acid-modified resin having a relatively small molecular weight is preferable. By using such an acid-modified resin, plant fibers can be sufficiently bound together while suppressing the amount of the acid-modified resin used. Moreover, it is easy to produce a thermoplastic resin fiber having a suitable fineness. The lower limit value of the weight average molecular weight is particularly preferably 15000, particularly 25000, and more preferably 35000, and the upper limit value of the weight average molecular weight is particularly preferably 200000, particularly 150,000, more preferably 100,000. The acid-modified resin preferably has a weight average molecular weight of 35,000 to 60,000. The weight average molecular weight is measured by GPC method (standard polystyrene conversion).

  Furthermore, the melt viscosity of the acid-modified resin is not particularly limited, but is preferably 4000 to 30000 mPa · s at 160 ° C. By using such an acid-modified resin, vegetable fibers can be sufficiently bound together while suppressing the content of the acid-modified resin. Moreover, it is easy to produce a thermoplastic resin fiber having a suitable fineness. The melt viscosity is preferably 4000 to 25000 mPa · s, more preferably 5000 to 20000 mPa · s, and even more preferably 10,000 to 20000 mPa · s. The melt viscosity is measured at 160 ° C. with a B-type viscometer (using No. 4 rotor based on JIS K7117).

  Examples of the acid-modified resin having the above-mentioned preferred acid value, weight average molecular weight and melt viscosity include the above-mentioned Sanyo Kasei Kogyo Co., Ltd., trade name “Yumex”, particularly “Yumex 1001” and / or trade name. “Yumex 1010” is more preferable.

  The kind of the non-acid-modified resin (thermoplastic resin not acid-modified among the resins constituting the thermoplastic resin fiber) is not particularly limited, and various thermoplastic resins can be used. Examples of the non-acid-modified thermoplastic resin include polyolefin, polyester, polystyrene, acrylic resin (resin using methacrylate and / or acrylate), polyamide, polycarbonate, polyacetal, and ABS resin. Examples of the polyolefin include isotactic propylene homopolymer (hereinafter referred to as “PP homopolymer”), ethylene-propylene block copolymer resin (hereinafter referred to as “EP block copolymer resin”), polyethylene, and the like. Can be mentioned. Examples of the polyester include aliphatic polyesters such as polylactic acid, polycaprolactone, and polybutylene succinate, and aromatic polyesters such as polyethylene terephthalate, polytrimethylene terephthalate, and polybutylene terephthalate. This non-acid-modified resin may be used alone or in combination of two or more.

  The acid-modified resin and the non-acid-modified resin may be the same type of resin or different resins, but are preferably the same type, more preferably polyolefin. Polyolefin is easy to handle and has excellent flexibility and formability and can improve the productivity of fiberboard. As this polyolefin, PP homopolymer, EP block copolymer resin, polyethylene and the like are preferable (skeleton resin in acid-modified resin). Further, it is more preferable that the acid-modified resin and the non-acid-modified resin are PP homopolymer and / or EP block copolymer resin, or a skeleton resin, and the acid-modified resin is maleic anhydride. Particularly preferred is a modified PP homopolymer and / or EP block copolymer resin, and the non-acid-modified resin is a PP homopolymer and / or EP block copolymer resin.

  The amount ratio of the acid-modified resin and the non-acid-modified resin contained in the thermoplastic resin fiber is not particularly limited, but the acid-modified resin is 0 when the total of the acid-modified resin and the non-acid-modified resin is 100% by mass. It is preferably 5 to 15% by mass, more preferably 1 to 10% by mass, and particularly preferably 2 to 7% by mass.

  In addition, the acid-modified resin is 1 to 10 parts by mass when the total of the vegetable fiber and the thermoplastic resin fiber is 100% by mass, regardless of whether or not the second thermoplastic resin fiber described later is used. It is preferably 1 to 8 parts by mass, particularly 1 to 5 parts by mass, and more preferably 1 to 3 parts by mass. When the ratio of the acid-modified resin is 1 to 10 parts by mass, particularly 1 to 5 parts by mass, the fibers of the vegetable fibers are sufficiently bound together, and a fiber board having excellent mechanical properties can be obtained.

  Furthermore, although the fineness etc. of a thermoplastic resin fiber are not specifically limited, It is preferable that a fineness is 1-100 dtex. When the fineness is within this range, mixing with vegetable fibers is easy, and each fiber can be more uniformly dispersed. The fineness is preferably 1 to 50 dtex, particularly 1 to 20 dtex, and more preferably 3 to 10 dtex. The average fiber diameter of the thermoplastic resin fibers having a fineness of 3 to 10 dtex is obtained by using maleic anhydride-modified PP homopolymer and / or maleic anhydride-modified EP block copolymer resin as the acid-modified resin, and non-acid-modified resin. When PP homopolymer and / or EP block copolymer resin is used, it becomes about 3.8 to 37.5 μm. This fineness is represented by the mass (unit: g) of a fiber having a length of 10,000 m. Moreover, the measuring method of an average fiber diameter is the same as that of the case of vegetable fiber.

  In this fiber mat forming step, the method of mixing the vegetable fiber and the thermoplastic resin fiber is not particularly limited and can be mixed by various methods, but can be usually mixed by a dry method or a wet method. Of these, the dry method is preferred. In the production method of the present invention, since vegetable fibers having hygroscopicity are used, when mixed by a wet method such as a papermaking method, an advanced drying step is required, and therefore, mixing can be performed more easily. A dry method is preferred. Examples of the dry method include an air lay method and a card method, but an air lay method capable of efficiently mixing with a simpler apparatus is preferable. In this air-lay method, each fiber is floated by an air current, and then deposited on a conveyor belt or the like, so that a fiber mat in which vegetable fibers and thermoplastic resin fibers are dispersed and deposited can be produced. .

  When the airlay method is used, the form of the fiber mat is not particularly limited, and a fiber mat in which only one layer of mixed fibers is deposited may be used as the fiber mat, and fibers in which two or more layers of mixed fibers are deposited. A mat (laminated fiber mat) may be used as the fiber mat. The thickness of the fiber mat can be adjusted by the number of deposited layers, and the basis weight of the resulting fiber board can be adjusted. Further, the fiber mat may be entangled so that the deposited layers are better entangled and integrated. The method of entanglement processing is not particularly limited, and examples thereof include a needle punch method, a stitch bond method, and a water punch method. These methods may use only 1 type and may use 2 or more types together.

  Further, the fiber mat may be composed of only two kinds of fibers, the vegetable fiber and the thermoplastic resin fiber, but may contain fibers other than these two kinds. Examples of the fibers other than these two types include second thermoplastic resin fibers made only of non-acid-modified resins. This second thermoplastic resin fiber is a non-acid-modified resin that can be contained in the thermoplastic resin fiber (a thermoplastic resin fiber containing an acid-modified resin, hereinafter also referred to as “first thermoplastic resin fiber”). Can be applied as they are, but among these, fibers made of a non-acid-modified resin having a melting point lower than that of the non-acid-modified resin constituting the first thermoplastic resin fiber are preferable. The melting point of the non-acid-modified resin constituting the second thermoplastic resin fiber should be lower than the melting point of the non-acid-modified resin constituting the first thermoplastic resin fiber, and the temperature difference is not particularly limited. It is preferably -50 ° C, particularly 15-45 ° C, more preferably 20-40 ° C.

  Non-acid-modified resins constituting the second thermoplastic fiber include polyolefin, polyester, polystyrene, acrylic resin (resin using methacrylate and / or acrylate), polyamide, polycarbonate, polyacetal, and ABS resin. Can be used. In particular, it is preferable to use various random copolymer resins having a relatively low melting point, and ethylene-propylene random copolymer resins (hereinafter referred to as “EP random copolymer resins”) are particularly preferable. Furthermore, it is preferable that melting | fusing point of this EP random copolymer resin is 120-140 degreeC. In addition, if it has melting | fusing point of this range, a high density polyethylene etc. can also be used, for example.

  Among these, when the second thermoplastic resin fiber is used, acid-modified polypropylene is used as the acid-modified resin that forms the first thermoplastic resin fiber, and non-acid-modified that forms the first thermoplastic resin fiber. It is preferable to use an EP block copolymer resin as the resin and an EP random copolymer resin as the thermoplastic resin constituting the second thermoplastic resin fiber in combination. Further, the acid-modified polypropylene skeleton resin as the acid-modified resin is more preferably an EP block copolymer resin. If it is such a combination, the fiber board which has the outstanding mechanical characteristic can be manufactured.

  When the second thermoplastic resin fiber is used, the form of the second thermoplastic resin fiber is not particularly limited, but the fineness is preferably 1 to 100 dtex. When the fineness is in this range, mixing with the vegetable fiber and the first thermoplastic resin fiber is easy, and each fiber can be more uniformly dispersed. The fineness is preferably 1 to 50 dtex, particularly 1 to 20 dtex, and more preferably 3 to 10 dtex. The average fiber diameter of the second thermoplastic resin fiber having a fineness of 3 to 10 dtex is about 3.8 to 37.5 μm when an EP random copolymer resin is used. This fineness is represented by the mass (unit: g) of a fiber having a length of 10,000 m. Moreover, the measuring method of an average fiber diameter is the same as that of the case of vegetable fiber.

The basis weight, thickness, and density determined by the basis weight and thickness of the “fiber mat” are not particularly limited, but the basis weight is usually 400 to 3000 g / m ² , preferably 600 to 2000 g / m ² . The thickness is preferably 5 mm or more (usually 50 mm or less), more preferably 8 to 40 mm, and particularly preferably 10 to 30 mm. Furthermore, the density is 0.3 g / cm ³ or less (typically, 0.05 g / cm ³ or higher). The density can be measured according to JIS K7112 (Plastic—Method for measuring density and specific gravity of non-foamed plastic).

The amount ratio of the vegetable fiber and the thermoplastic resin fiber used for forming the fiber mat is not particularly limited, but when the total amount of the vegetable fiber and the thermoplastic resin fiber is 100% by mass, the vegetable fiber is 30 to 95% by mass. % Is preferred. In this range, it is possible to provide a fiber board having excellent formability and excellent mechanical properties. The vegetable fiber content is preferably 40 to 85% by mass, and more preferably 45 to 75% by mass. Within these ranges, the formability and mechanical properties are further improved.
As the thermoplastic resin fiber, the first thermoplastic resin fiber (containing an acid-modified resin and a non-acid-modified resin) and the second thermoplastic resin fiber (not containing an acid-modified resin and a non-acid-modified resin). The same applies to the case of using both fibers. Furthermore, the mass of the vegetable fiber in this invention shall be a measured value in 10% of an equilibrium moisture content.

The average fiber length of the thermoplastic resin fibers is not particularly limited, but is preferably 10 mm or more. When the average fiber length is 10 mm or more, mixing with vegetable fibers is easy (particularly, entanglement between the fibers is easily formed), and the mechanical properties of the fiber board are easily improved. The average fiber length is 10 to 150 mm, particularly 20 to 100 mm, and more preferably 30 to 70 mm. In this fiber length range, mixing is easier and the mechanical properties of the fiber board can be further improved. Furthermore, it is preferable that the thermoplastic resin fiber has a shorter average fiber length than the vegetable fiber.
Moreover, it is preferable that the average fiber diameter of a thermoplastic resin fiber is 1 mm or less. If it is 1 mm or less, the mechanical properties of the fiber board can be improved. The average fiber diameter is 0.001 to 0.5 mm, particularly 0.01 to 0.2 mm, and more preferably 0.02 to 0.1 mm.
In addition, the measuring method of average fiber length and average fiber diameter is the same as that of the case of vegetable fiber.

<Water dispersion application process>
The “water dispersion coating step” is a step of spray-coating an aqueous dispersion of a thermoplastic resin on both surfaces of the fiber mat.

  The “water dispersion” is a dispersion in which a thermoplastic resin is used as a dispersoid and water is a main component of a dispersion medium. Examples of the thermoplastic resin contained in the aqueous dispersion include polyolefin, polyester, polystyrene, acrylic resin (resin using methacrylate and / or acrylate, etc.), polyamide, polycarbonate, polyacetal, and ABS resin. it can. Of these, the same kind as the acid-modified resin and the non-acid-modified resin constituting the thermoplastic resin fiber is preferable, and polyolefin is particularly preferable. That is, it is preferable that both the thermoplastic resin fiber and the aqueous dispersion contain polyolefin. In other words, both the acid-modified resin and non-acid-modified resin constituting the thermoplastic resin fiber and the thermoplastic resin contained in the aqueous dispersion are preferably polyolefin.

The presence or absence of modification of the polyolefin used as the dispersoid is not particularly limited, and unmodified polyolefin may be used, or modified polyolefin may be used. Examples of the case where the modified polyolefin is used include a polyolefin obtained by neutralizing an acid group of an acid-modified polyolefin (polyolefin having an acid group) (that is, an acid group-neutralized polyolefin). In this case, as the acid-modified polyolefin (polyolefin resin before neutralization), the acid-modified polyolefin used for the thermoplastic resin fiber can be used.
Specific water dispersions that can be used in the present invention include trade name Chemipearl WP100 (PP water dispersion manufactured by Mitsui Chemicals), trade name Chemipearl W401 (PE water dispersion manufactured by Mitsui Chemicals), Product name Chemipearl W4005 (PE water dispersion manufactured by Mitsui Chemicals), Product name Chemipearl W900 (PE water dispersion manufactured by Mitsui Chemicals), Product name Chemipearl W905 (PE water dispersion manufactured by Mitsui Chemicals) And trade name Chemipearl WH201 (PE water dispersion manufactured by Mitsui Chemicals, Inc.).

  Furthermore, the form of the thermoplastic resin contained in the aqueous dispersion is not particularly limited, but is preferably in the form of particles. That is, an aqueous dispersion containing thermoplastic resin particles as a dispersoid is preferable. When using these thermoplastic resin particles, the average particle diameter and the like are not particularly limited, but are preferably 0.1 to 15 μm, more preferably 0.3 to 5 μm, and still more preferably 0.5 to 2 μm. In this range, it is excellent in spray coatability, and adhesion of the fiber mat to the conveyor can be better suppressed in the heating and pressing step. The average particle diameter is determined by a microtrack method using a laser diffraction / scattering particle size distribution measuring apparatus.

Furthermore, the solid content concentration of the aqueous dispersion is not particularly limited, but is preferably 5 to 55%, more preferably 10 to 50%, and still more preferably 15 to 45%. In this range, it is excellent in spray coatability, and adhesion of the fiber mat to the conveyor can be better suppressed in the heating and pressing step.
The viscosity of the aqueous dispersion is preferably 1000 mPa · s or less (usually 50 mPa · s or more), more preferably 700 mPa · s or less, and even more preferably 500 mPa · s or less. In this range, it is excellent in spray coatability, and adhesion of the fiber mat to the conveyor can be better suppressed in the heating and pressing step.
The aqueous dispersion may contain other components as long as the function is not impaired.

  In this aqueous dispersion application step, it is preferable to apply the aqueous dispersion such that the thermoplastic resin contained in the aqueous dispersion is 1 to 15 parts by mass with respect to 100 parts by mass of the fiber mat. In this range, a uniform and small amount can be applied to the surface of the fiber mat, and the fiber mat is effectively attached to the conveyor in the heating and pressing step without greatly changing the blending ratio of the vegetable fiber and the thermoplastic resin. Can be suppressed. The coating amount is more preferably 1 to 14 parts by mass, more preferably 2 to 13 parts by mass, more preferably 2 to 12 parts by mass of the thermoplastic resin contained in the aqueous dispersion. It is particularly preferable that the amount be part.

<Heating and pressing process>
The “heating and pressing step” is a step of obtaining a fiber board by heating and pressing a fiber mat coated with an aqueous dispersion between a pair of conveyors. By this heating and pressing, the thermoplastic resin fibers contained in the fiber mat are melted, and the plant fibers are bound by the melted thermoplastic resin fibers.

The heating temperature in this heating and pressing step is not particularly limited as long as it is a temperature at which the thermoplastic resin fiber can be melted, but is usually 150 to 280 ° C.
In particular, when polypropylene is used for any of the backbone resin of the acid-modified resin, the non-acid-modified resin, and the thermoplastic resin constituting the dispersoid of the aqueous dispersion, 170 to 250 ° C. is preferable, and 180 to 240 ° C. Is more preferable, and 190-230 degreeC is still more preferable.
This temperature is a value obtained by measuring the temperature in the fiber mat with a contact temperature sensor.

Moreover, although the pressurization pressure in a heating-pressing process is not specifically limited, 0.5-8 MPa is preferable, 0.7-5 MPa is more preferable, 1-4 MPa is still more preferable. By compressing by this pressurization, plant fibers can be bound more firmly than when not compressed.
This pressure is a value obtained by a pressure sensor built in the pressurizer.

In this heating and pressing step, heating and pressing may be performed simultaneously, or pressing may be performed as a post-heating step. Furthermore, heating and pressurization can be performed continuously.
In addition, although the heat pressurization process in this invention is a process for manufacturing a fiber board using a conveyor, although it is not included in this invention, forming a fiber mat directly in a heat pressurization process. You can also. That is, by compressing using a mold, it can be formed into various other shapes (product shapes) instead of the fiber board.
Furthermore, the vegetable fiber and the thermoplastic resin contained in the fiber board produced by the method of the present invention maintain the proportions of the vegetable fiber and the thermoplastic resin used in the fiber mat forming step.

Further, the fiber board is not particularly limited as long as the fiber mat is heated and pressed, and the fiber mat has a basis weight of, for example, 400 to 3000 g / m ² (preferably 600 to 2000 g). / ^m 2), more thickness 5 mm (typically, 50 mm or less, preferably 8 to 40 mm, more preferably 10 to 30 mm), a density 0.3 g / cm ³ or less (typically, 0.05 g / cm ³ or higher), in The fiber board preferably has a basis weight of 380 to 2880 g / m ² (preferably 580 to 1920 g / m ² ) and a thickness of less than 5 mm (usually 1 mm or more, preferably 1.5 to 4 mm, More preferably, it is preferably 2 to 3 mm) and a density exceeding 0.3 g / cm ³ (usually 1.0 g / cm ³ or less).

In the method of the present invention, other steps can be provided in addition to the steps described above. Other processes include a drying process for drying and removing the medium of the water dispersion before heating and pressurizing the fiber mat coated with the water dispersion, and a fiber board obtained by heating and pressing to a desired size. The cutting process etc. which cut | deviate to are mentioned. These processes may use only 1 type and may use 2 or more types together.
Furthermore, the fiber board obtained by the method of the present invention can be formed into a molded product having a more complicated shape through a shaping process (main molding process) as necessary.

<Fiber board manufacturing equipment>
FIG. 1 is a schematic diagram showing an example of a fiber board manufacturing apparatus 1 for manufacturing a fiber board according to the process of the present invention. The fiber board manufacturing apparatus 1 includes a fiber mat forming unit 10, a water dispersion applying unit 20, and a heating and pressing unit 30. In this apparatus 1, the said fiber mat formation process, the said water dispersion application | coating process, and the said heating-pressing process can be performed.

<Fiber mat forming means>
In the fiber mat forming means 10, a rotating rotator 11, an air blowing device 13 that blows and blows compressed air to raw material fibers (vegetable fibers and thermoplastic resin fibers) supplied to the surface of the rotator 11, In addition, the fiber mat forming step in the steps of the present invention can be performed.
In the fiber mat forming means 10, raw material fibers (vegetable fibers and thermoplastic resin fibers) are supplied to the back portion (left side in FIG. 1) of the rotating body 11. A wire called a garnet wire (not shown) on which a number of protrusions are formed is wound around the surface of the rotating body 11, and two large and small rollers are provided in the range from the back to the top of the rotating body 11. A plurality of roller pairs 12 composed of (vodka and stripper) are arranged. When the raw fiber is supplied to the fiber mat forming means 10, the raw fiber adheres to the surface of the rotating body 11 by the garnet wire, is transported by the rotation of the rotating body 11, is wound around the roller pair 12, and is loosened. However, the surface of the rotating body 11 is conveyed. Then, the raw material fibers are blown off by the compressed air blown from the air blowing device 13 disposed on the front side (right side in FIG. 1) of the rotating body 11 and are deposited to form a fiber mat at the position.

  Usually, as illustrated in FIG. 1, the fiber mat forming means 10 is connected to a conveying means 41 on the upstream side and a conveying means 42 on the downstream side. The conveying means 41 includes a small-diameter roller 411 and a resin belt 412 having elasticity, and the belt 412 is stretched around the small-diameter roller 411 and circulates in the direction of the arrow in the drawing as the small-diameter roller 411 rotates. Driven. Similarly, the conveying means 42 includes a small-diameter roller 421 and an elastic resin belt 422. The belt 422 is stretched around the small-diameter roller 421 in a tensioned state, and the arrow in the drawing indicates the rotation of the small-diameter roller 421. Driven in the direction.

  Then, after the raw material fibers are supplied from the left side of FIG. 1 to the fiber mat forming means 10 by the conveying means 41, a fiber mat forming step is performed in the fiber mat forming means 10 and blown off by the air blowing device 13. The raw material fibers are deposited on the belt 422 of the conveying means 42 as a fiber mat and are conveyed to the water dispersion applying means 20 by the conveying means 42.

  A plurality of fiber mat forming means 10 may be mounted on the fiber board manufacturing apparatus 1. When a plurality of fiber mat forming means 10 are mounted, each fiber mat is formed from each fiber mat forming means 10, but these can be formed as a single layer fiber mat by stacking and interlacing them. .

<Water dispersion application means>
The water dispersion coating means 20 can perform the water dispersion coating process of the processes of the present invention. The water dispersion applying means 20 includes an injection unit 21 for spraying the water dispersion supplied to the means 20, and the water dispersion is applied to the surface of the fiber mat that has been conveyed by the conveying means such as the conveying means 42. Apply spray. At this time, the method for applying the aqueous dispersion to both surfaces of the fiber mat is not particularly limited. For example, (1) the two water dispersion applying means 20 are provided, the fiber mat is turned upside down on the line of the conveying means 42, and the water dispersion is made of the fiber mat by the first water dispersion applying means. Application on both the front and back surfaces can be achieved by applying to the front side and then applying the aqueous dispersion to the back side of the fiber mat by the second aqueous dispersion application means. Furthermore, for example, (2) Application to both front and back surfaces can be achieved by applying the aqueous dispersion with a brush.

<Heating and pressing means>
The heating / pressurizing means 30 illustrated in FIG. 1 is a double belt type heating / pressurizing apparatus, and can perform the heating / pressing step of the steps of the present invention.
The heating and pressurizing means 30 includes two pairs of drums 311 and 312 arranged at regular intervals in the vertical direction, and a stainless steel endless belt (that is, a conveyor) 321 hung on each drum pair in tension. And 322. The endless belts 321 and 322 are rotated around the drum pair 311 and 312 in the direction of the arrow in FIG. 1 at a constant vertical speed (that is, a roll press). A fiber mat is sandwiched between the endless belts 321 and 322 and conveyed from the left side of FIG. 1 to the right side of FIG.

  Openings of the heating and pressurizing chambers 331 and 332 and the cooling and pressurizing chambers 341 and 342 are arranged opposite to each other on the back surfaces of the endless belts 321 and 322, that is, the side not in contact with the fiber mat. Yes. Further, a heating and pressurizing fluid is circulated and supplied to the heating and pressurizing chambers 331 and 332, and a cooling and pressurizing fluid is circulated and supplied to the cooling and pressurizing chambers 341 and 342. Then, the fiber mat is pressurized with a uniform surface pressure via the endless belts 321 and 322 by these fluids supplied from the outside.

  In such a configuration, the fiber mat is sandwiched between the endless belts 321 and 322 and pressed while being conveyed rightward in FIG. That is, each fluid injected into the heating and pressurizing chambers 331 and 332 and the cooling and pressurizing chambers 341 and 342 pressurizes each endless belt with a uniform surface pressure while circulating in each chamber, and this force causes the fiber mat. Can be pressed with uniform surface pressure. The fiber mat is heated when passing between the heating and pressurizing chambers 331 and 332, and cooled when passing between the cooling and pressurizing chambers 341 and 342, and is sent out from the heating and pressurizing means 30. As a result, a fiber board in which the fiber mat is heated and pressed can be obtained.

  In the heating and pressurizing means 30, the presence or absence of the cooling and pressurizing chambers 341 and 342 is not limited, and these may not be provided. In this case, it can also be cooled by natural cooling. Further, a heat transfer type pressure roller can be used in place of the heating and pressure chambers 331 and 332. Similarly, a heat transfer type pressure roller can be used in place of the cooling and pressure chambers 341 and 342.

  Furthermore, as illustrated in FIG. 1, a conveying unit 43 can be connected to the downstream side of the heating and pressing unit 30. The conveying means 43 includes a small-diameter roller 431 and an elastic resin belt 432, and the belt 432 is stretched around the small-diameter roller 431 and rotates in the direction of the arrow in the drawing as the small-diameter roller 431 rotates. Driven. Thereby, the fiber board sent out from the heating and pressurizing means 30 can be further conveyed as required.

  There are no particular restrictions on the dimensions and thickness of the fiberboard produced by the method of the present invention. Moreover, the use is not specifically limited, For example, it can use as interior materials, exterior materials, structural materials, etc., such as a motor vehicle, a rail vehicle, a ship, and an airplane. Among these, for automobiles, they can be used as automotive interior materials, automotive instrument panels, automotive exterior materials, and the like. Specifically, door base material, package tray, pillar garnish, switch base, quarter panel, armrest core material, door trim, seat structural material, console box, dashboard, various instrument panels, deck trim, bumper, spoiler And cowling. Furthermore, the fiber board manufactured by the method of the present invention can be used as, for example, interior materials such as buildings and furniture, exterior materials, and structural materials. That is, it can be used as a door cover material, a door structure material, a cover material of various furniture such as a desk, a chair, a shelf, and a basket, and a structural material. In addition, it can also be used as a packaging material, a storage material such as a tray, a protective member such as a cushioning material, and a partition member.

Hereinafter, the present invention will be described specifically by way of examples.
[1] Production of fiber board Example 1
(1) Fiber mat forming step Acid-modified thermoplastic resin {Acid-modified polypropylene, manufactured by Sanyo Chemical Industries, trade name "Yumex 1001"("Acid-modified PP resin" in Table 1) (acid value: 26, weight average molecular weight; 40000, melt viscosity at 160 ° C .; 16000 mPa · s)}, and thermoplastic resin {EP block copolymer resin, manufactured by Nippon Polypro Co., Ltd., trade name “NOVATEC SA01” (“PP resin” in Table 1)}} The mixture was dry blended so that the composition of 1 was obtained to obtain a mixed thermoplastic resin. Thereafter, the mixed thermoplastic resin was melt-spun and then cut to produce a plastic resin fiber (fineness: 6.6 dtex, average fiber length: 51 mm). Thereafter, two layers of kenaf fibers (average fiber length; 70 mm) and the thermoplastic resin fibers are formed on the resin belt of the conveying means 42 using two fiber mat forming means 10 (air lay apparatus) shown in FIG. Then, fibers were entangled using a needle punch device (not shown in FIG. 1) to produce a fiber mat having a basis weight of 1200 g / m ² and a thickness of 10 mm (density 0.13 g / cm ³ ).

(2) Aqueous dispersion coating step Polypropylene aqueous dispersion (Mitsui Chemicals, product name “Kemipearl WP100”, solid content concentration 40%, viscosity 400 mPa · s on both sides of the fiber mat obtained in (1) above. , Dispersoid average particle size 1 μm). The coating amount of the polypropylene aqueous dispersion was 3 parts by mass (a mass ratio of only polypropylene as a dispersoid) with respect to 100 parts by mass of the fiber mat. That is, an aqueous dispersion corresponding to a polypropylene amount of 1.5 parts by mass on the front surface and 1.5 parts by mass on the back surface was applied.

(3) Heating and pressing step The fiber mat obtained up to the above (2) is sandwiched between stainless steel plates (thickness: 1.2 mm), and using a hot plate press at 235 ° C., pressing pressure 1. Heating and pressing was performed at 37 MPa (14 kgf / cm ² ) for 40 seconds (the fiber mat internal temperature during heating and pressing was up to 200 ° C. as measured by a contact-type temperature sensor (manufactured by Keyence Corporation, model “NR-1000”). Next, a cooling press (stainless steel plate, thickness 150 mm) was applied at 3.92 MPa (40 kgf / cm ² ) for 60 seconds, and the temperature inside the fiber mat was lowered to 25 ° C. to obtain a fiber board. .
In addition, all the obtained fiber boards were 2.3 mm in thickness. Moreover, basis weight, Example 1 1180 g / ^{m 2,} Example 2 1200 g / ^{m 2,} Example 3 1220 g / ^{m 2,} Example 4 1260 g / ^{m 2,} Example 5 1300 g ^{/ m} 2, The comparative example 1 was 1140 g / m < ² >.

[2] Evaluation of fiber board and sticking In the above [1] and (3), the presence or absence of sticking of the sandwiched material to the press plate in each of the “hot plate press” and “cooling press” performed was examined visually. As a result, when sticking occurred, “x” was shown in the presence / absence column of Table 1, and when there was no sticking, “○” was shown in the presence / absence column of Table 1. .

Furthermore, these maximum bending loads were measured using the fiber boards obtained in the examples and comparative examples, and the results are also shown in Table 1.
The maximum bending load was 2.3 mm thick, 50 mm wide, and 150 mm long test pieces with a rectangular planar shape. The test piece was divided into two fulcrums with a fulcrum distance of 100 mm (the radius of curvature of the upper end was 3). .2 mm), and the maximum bending load when a load was applied at a speed of 50 mm / min from the central point of action between the fulcrums (the radius of curvature of the upper end portion was 3.2 mm) was measured (in accordance with JIS K7171). ).

表１の結果から、水分散体を塗布することにより、繊維マット（又は繊維ボード）がプレス板へ張り付くことを確実に防止することができた。更に、最大曲げ荷重を大きくできるという観点から、その塗布量は１３質量部未満が好ましいことが分かる。特に、実施例１及び実施例２では、高い最大曲げ荷重が得られることから、７質量部未満がより好ましいことが分かる。
尚、本発明においては、上記の具体的実施例に示すものに限られず、目的、用途に応じて本発明の範囲内で種々変更した実施例とすることができる。

From the results in Table 1, it was possible to reliably prevent the fiber mat (or fiber board) from sticking to the press plate by applying the aqueous dispersion. Furthermore, from the viewpoint that the maximum bending load can be increased, it is understood that the coating amount is preferably less than 13 parts by mass. In particular, in Example 1 and Example 2, since a high maximum bending load is obtained, it can be seen that less than 7 parts by mass is more preferable.
In addition, in this invention, it can restrict to what is shown to said specific Example, It can be set as the Example variously changed within the range of this invention according to the objective and the use.

  DESCRIPTION OF SYMBOLS 1; Fiber board manufacturing apparatus, 10; Fiber mat formation means, 11; Rotating body, 12; Roller pair, 13; Air blow apparatus, 20; Water dispersion application means, 21; Injection part, 30; And 312; drum pairs, 321 and 322; endless belts, 331 and 332; heating and pressurizing chambers, 341 and 342; cooling and pressurizing chambers, 41, 42, and 43; conveying means, 411, 421, and 431; 422 and 432; resin belt

Claims (6)

A method for producing a fiber board having a structure in which plant fibers are bound together by a thermoplastic resin,
A fiber mat forming step in which a vegetable mat and a thermoplastic resin fiber containing an acid-modified thermoplastic resin are mixed to form a fiber mat;
An aqueous dispersion application step of spray-applying an aqueous dispersion of a thermoplastic resin on both surfaces of the fiber mat;
And a heating and pressurizing step of heating and pressurizing the fiber mat coated with the water dispersion between a pair of conveyors to obtain a fiber board.   The method for producing a fiber board according to claim 1, wherein the fiber mat is 30 to 95% by mass when the total of the vegetable fiber and the thermoplastic resin fiber is 100% by mass. .   The water dispersion is applied so that the thermoplastic resin contained in the water dispersion is 1 to 15 parts by mass with respect to 100 parts by mass of the fiber mat in the water dispersion application step. The manufacturing method of the fiber board of 2.   The thermoplastic resin fiber contains the acid-modified thermoplastic resin and a non-acid-modified thermoplastic resin, and when the total is 100% by mass, the acid-modified thermoplastic resin is 0.5 to 15%. The method for producing a fiber board according to any one of claims 1 to 3, wherein the fiber board is mass%.   The said thermoplastic resin fiber and the said water dispersion are both the manufacturing methods of the fiber board in any one of Claims 1 thru | or 4 containing polyolefin.   The said vegetable fiber is a kenaf fiber, The manufacturing method of the fiber board in any one of Claims 1 thru | or 5.

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