JPH08118506A - Net-like fiber reinforced plastic porous body and manufacture thereof - Google Patents

Abstract

PURPOSE: To obtain a net-like fiber reinforced plastic porous body having excellent water absorption power, high rigidity, high ventilating property, which is optimal as a water absorbing sheet whose pressure loss is only a little. CONSTITUTION: A reinforcing short filament of 5-500 pts.wt. having an average fiber length of 1-50mm is connected to 100 pts.wt. of matrix resin in a uniformly dispersed manner. A large number of narrow slender pieces 2 consisting of porous plastic having continuous pores form a zigzagged snaking shape and connect with the adjacent narrow slender pieces integrally at converting points 3 of the snaking directions so as to form a net-like shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a net-shaped fiber reinforced plastic porous body and a method for producing the same.

[0002]

2. Description of the Related Art As one method of humidifying with a humidifier, tension is applied firmly so that a water-absorbent sheet such as a non-woven fabric that is wet with water does not flutter, and wind is vertically applied to it from behind. A means of spraying and humidifying is adopted.

[0003]

However, when a conventional water-absorbent sheet such as a nonwoven fabric is wetted with water, it is often clogged and the ventilation is remarkably reduced, resulting in a high pressure loss and a large air volume. It was necessary to put a high load on the power to generate the wind. Further, a water-absorbent sheet such as a non-woven fabric that is wet with water flutters under wind pressure, so it must be firmly fixed.

An object of the present invention is to obtain a net-shaped fiber-reinforced plastic porous body which is optimal as a water-absorbent sheet having excellent water-absorbing ability, high rigidity, high ventilation and low pressure loss.

[0005]

The present invention achieves the above object. First, 5 to 500 parts by weight of reinforcing short fibers having an average fiber length of 1 to 50 mm are uniformly added to 100 parts by weight of a matrix resin. A large number of narrow strips made of porous plastic that are connected in a dispersed state and have continuous pores meander in a zigzag shape, and are adjacent to each other at a point where the direction of the meander is changed. The gist is a net-shaped fiber-reinforced plastic porous body characterized in that it is integrally bonded to form a net.

A second aspect of the present invention is directed to a method for producing a net-shaped fiber-reinforced plastic porous body, which is characterized by comprising the following four steps. (1) A step of dispersing and mixing 100 parts by weight of matrix resin powder and 5 to 500 parts by weight of reinforcing short fibers having an average fiber length of 1 to 50 mm in water to form a sheet, (2) heating the sheet Step of pressing and densifying under cooling, (3) Row A of a plurality of slits having a constant length a and arranged in a row at regular intervals d, and row 1 at a regular interval d And a row of a plurality of slits having a constant length a arranged in parallel with each other, and a row B in which the positions of the slits are laterally displaced from each other by (a + d) / 2, are alternately arranged in parallel at regular intervals. A step of cutting slits in a dense sheet so that they are lined up,
(4) The slit-cut sheet is heated to a temperature equal to or higher than the melting point of the matrix resin in a state of being stretched by applying tension in a direction perpendicular to the slit, whereby the sheet is thermally expanded to be a porous body and the sheet has a net shape. The process of forming into a shape.

Hereinafter, the present invention will be described in detail. The net-shaped fiber-reinforced plastic porous body 1 according to the present invention is shown in FIG.
As shown in FIG. 7, a large number of narrow strips 2, ... Form a zigzag meandering shape, and are integrally connected to adjacent strips at each direction change point 3 ,. It has a net shape. This narrow strip is made of a porous plastic having continuous pores. Here, the term "porous plastic having continuous pores" refers to the proportion of continuous pores in which ethanol is sucked into the porous plastic within 10 seconds when a 1 cc ethanol solution is dropped on the surface of the porous plastic with a pipette. Highly porous plastic.

The porous plastic used in the present invention preferably has a porosity of 20 to 90% by volume, particularly 50 to 85% by volume. Here, the porosity is determined by the following method. That is, when the theoretical density of the plastic forming the porous plastic of the present invention when it does not have pores is Ag / cm ³ and the apparent density of the porous plastic of the present invention is Bg / cm ³ , the porosity is [( AB)
/ A] × 100 (%).

In the porous plastic of the present invention, the reinforcing short fibers are bonded to the matrix resin in a uniformly dispersed state, and have a large number of small holes at the interface between the reinforcing short fibers and the matrix resin. .

As the matrix resin used in the present invention, a thermofusible polymer which is normally solid can be used. Thermofusible means that the polymer particles can be deformed under heating to bond into a unitary structure, and the fusible polymer is either a thermoplastic or thermosetting resin. Here, the heat-fusible polymers include water-insoluble addition polymers, which are preferably hydrophobic, and these polymers can be used in the form of powder or dispersion. Suitable heat fusible organic polymers include addition polymers and condensation polymers such as polyethylene, ultra high molecular weight polyethylene, chlorinated polyethylene, polycarbonate, binary polymers of ethylene and acrylic acid, polypropylene, nylon, phenylene oxide. resin,
Phenylene sulfide resin, polyoxymethylene, polyesters, terpolymers of acrylonitrile and butadiene and styrene, polyvinyl chloride, a major proportion of vinylidene chloride and at least one other α, β-ethylene copolymerizable therewith Examples thereof include a binary polymer with a polyunsaturated monomer, a homopolymer or copolymer of styrene, a phenol resin and a polyimide resin.

The reinforcing short fibers used in the present invention include:
Organic or inorganic fibers are used, preferably pitch-based, polyacrylonitrile-based carbon fibers, glass fibers, meta- or para-based aramid fibers, alumina fibers, activated carbon fibers, polyethylene fibers, polyolefin fibers such as polypropylene fibers. Fibers and the like are used alone or in combination. In particular, a fiber having a high elastic modulus is desirable because it has a large rate of thermal expansion due to the action of the reinforcing fiber during the production of the sheet described below. The average fiber length of reinforcing fibers is 1
A material having a thickness of up to 50 mm is used, and a thickness of 3 to 25 mm is particularly preferable. If the average fiber length is shorter than 1 mm, the sheet will not have sufficient strength, and the thermal expansion due to the action of the reinforcing fibers during the production of the sheet will also be insufficient, making it difficult to obtain a porous body. Even if it exceeds 50 mm, the thermal expansion due to the action of the reinforcing fibers during the production of the sheet is insufficient, and
Sufficient homogeneity between fibers and matrix resin cannot be obtained.
The reinforcing fibers have an average fiber diameter of 2 to 100 μm, preferably 5 to 50 μm.

The mixing ratio of the matrix resin and the reinforcing fibers in the porous plastic of the present invention should be 5 to 500 parts by weight, preferably 10 to 300 parts by weight, with respect to 100 parts by weight of the matrix resin. Parts by weight, particularly preferably 20 to 200 parts by weight. If the mixing ratio of the reinforcing fibers is less than 5 parts by weight with respect to 100 parts by weight of the matrix resin, thermal expansion will be insufficient,
It is difficult to secure continuous pores. If it exceeds 500 parts by weight, it is difficult to cut slits in the sheet and stretch it in a mesh shape.

Further, the porous plastic of the present invention may contain various other components. For example 10-3
It is also possible to incorporate 3% by weight of filler. Examples of the filler include silicon dioxide (Novacite),
Examples include CaCO ₃ , MgO, CaSiO ₃ (wollastonite) and mica. Pigments or dyes can also be added to impart opacity or color to the porous plastic. Further, various chemical additives such as antioxidants, ultraviolet stabilizers, foaming agents, bactericides, adsorbents such as activated carbon and zeolite, and dechlorinating agents such as calcium sulfite can also be added.

The porous plastic of the present invention can be manufactured, for example, by the following method. First, with respect to 100 parts by weight of the matrix resin powder and granules, reinforcing fibers 5-5
00 parts by weight are dispersed and mixed in water to form a sheet. As a result, the matrix resin and the reinforcing fibers are sufficiently dispersed and mixed, and the reinforcing fibers are uniformly dispersed in the matrix resin to form a composite state. The matrix resin is preferably used in the form of powder, and the particle size of the powder is preferably 48 mesh or less according to JIS standard.

When the matrix resin powder and the reinforcing fibers are dispersed and mixed in water, for example, a binder is preferably used, and the binder is a solid component in an amount of 0.1 to 10% by weight, particularly 0.1. It is preferable to add 2 to 5% by weight.
Such binders include, for example, acrylic polymers or styrene / butadiene polymers containing bound sulfonium groups, isothiouronium groups, pyridinium groups, quaternary ammonium groups, sulfate groups, sulfonate groups or carboxylate groups. Polymer latices consisting of a substantially water-insoluble organic polymer having a bound anionic or cationic charge.

In addition, in a preferred method in which the matrix resin granules and the reinforcing fibers are dispersed in water to form a composite, starch, particularly natural starch or enzymatic starch containing linear starch such as corn starch and cationic starch, or Starches, including chemically modified starches, are used as binders.
Furthermore, as a preferable method of using this binder, an organic coagulant is used in combination. Suitable organic coagulants include various organic coagulants such as aluminum polychloride (aluminum hydroxychloride), partially hydrolyzed polyacrylamide, modified cationic polyacrylamide, diallyldiethylammonium chloride. The amount of coagulant added is less than about 3% by weight of the composite sheet, preferably less than 1% by weight. In addition, a thickener such as xanthan gum may be used to improve dispersibility. The amount of such thickener added is 1 for the composite sheet.
It is preferably less than wt%.

In this way, after the reinforcing fiber and the matrix resin powder are compounded in water, a sheet is formed. To form a sheet, it is desirable to perform solid-liquid separation using a paper machine or the like in the same manner as in papermaking, so that the solid content in water becomes a sheet. The obtained wet sheet is dried and then hot pressed in the state of one sheet or in the state of two or more laminated sheets. At this time, the temperature for hot pressing is preferably in the range of 10 to 50 ° C. higher than the melting point of the matrix resin,
The pressure is preferably 5 to 100 kg / cm ² .

After hot pressing, cooling pressing is performed.
This has the same pressure as the heating press, and a temperature of 10-50
It is desirable to perform cold pressing at ℃. By performing the heating press and the cooling press in this manner, the thickness is 0.1 to
With a thickness of about 1 mm, a densified sheet having a weight of about 100 to 1000 g / m ² can be obtained. The continuous porosity of the sheet at this time is preferably 30% by volume or less, and particularly preferably 20% by volume or less.

When the densified sheet is heated above the melting point of the matrix resin and thermally expanded by the action of the reinforcing fibers, the porous plastic of the present invention is obtained. In this case, in the densified sheet, the reinforcing fibers that were randomly oriented are fixed in the matrix resin in a bent and entangled state, but when the resin is melted by the heating, the fibers are released. The recovery elasticity causes the sheet to expand and become a porous body.

In the method for forming the net-like fiber-reinforced plastic porous material of the present invention into a net-like shape, the densified sheet before the heating of the matrix resin is subjected to the following treatment, and then the matrix resin is heated. First, a large number of slits are cut into the densified sheet. As shown in FIG. 2, the array of slits is a row A of a plurality of slits having a constant length a and arranged in a row in the sheet at a constant interval d, as shown in FIG.
A row of a plurality of slits having a constant length a arranged in a row at a constant interval d and a row B in which the positions of the slits are laterally displaced by (a + d) / 2 from the row A, They are arranged alternately in parallel at a constant interval h. However, since it is necessary to stretch the sheet into a net shape later, it is desirable that both ends of the sheet in the lateral direction are cut to the ends by slits in the row A. Therefore, as a matter of course, among the slits belonging to the row A, the slits located at both ends in the lateral direction of the sheet are
The length is less than a. Alternatively, after the slits are cut, both lateral ends of the sheet may be cut so as to intersect the slits belonging to the row A.

As a method of cutting the above slit,
For example, a method of producing a cutting die in which a Thomson blade is arranged at the position of the slit and placing the sheet on the blade and further pressing from the upper surface is conceivable, but it is not particularly limited to this method and other methods are appropriately used. good. Then, the slit sheet is fixed in a mesh-like state by stretching it with tension applied in the direction perpendicular to the slit, and the heat is set to the melting point of the matrix resin or higher, preferably 10 to 50 ° C. higher than the melting point. When placed in an oven and held for 10 to 300 minutes, thermal expansion occurs in the thickness direction of the sheet due to the action of the reinforcing fibers. This expansion is caused by the elastic recovery of the reinforcing fibers when the fibers bent in the dense sheet soften the resin. Then, remove from the oven and cool. In this way, the sheet becomes a porous body due to thermal expansion, and is heat-fixed in a net-like shape so that the net-like shape is maintained even if the fixing is released. In this way, the net-shaped fiber-reinforced plastic porous body of the present invention is obtained.

Moreover, since the thickness of the sheet is increased by thermal expansion, it is possible to obtain the net-like fiber-reinforced plastic porous body according to the present invention having high rigidity. When the net-like fiber-reinforced plastic porous body produced by the present invention is insufficient in hydrophilicity, a treatment for increasing hydrophilicity may be performed, for example, by adding colloidal silica.

[0023]

The net-shaped fiber-reinforced plastic porous body of the present invention has a shape in which a large number of narrow strips meander in a zigzag shape, and is integrated with the narrow strips adjacent to each other at each turning point of the meandering. Since they are connected together to form a net shape, there is a gap between each narrow strip, which makes it extremely easy for the wind to pass through, and has good ventilation and water absorption with little pressure loss. It can be suitably used as a sheet.
The net-shaped fiber-reinforced plastic porous body in the present invention has reinforcing fibers randomly dispersed therein,
It has a bulky structure with very many continuous pores at the interstices between the fibers and at the interface between the fibers and the matrix resin.
Due to the continuous pores, the water absorbency is extremely excellent. In addition, the bulkiness of the porous material of the reinforcing fibers makes the entire net highly rigid, and is suitable for use as a water absorbent sheet that withstands wind pressure. Is possible. The net-shaped fiber-reinforced plastic porous body of the present invention comprises 100 parts by weight of matrix resin powder and short fiber for reinforcement 5 having an average fiber length of 1 to 50 mm.
Disperse and mix ~ 500 parts by weight in water to form a sheet, then press under heat to densify, at regular intervals d
A row of a plurality of slits having a constant length a arranged side by side in a row and a row of a plurality of slits having a constant length a arranged in one row at a constant interval d The slits are cut in the densified sheet so that the rows B in which the positions of the slits are laterally displaced by (a + d) / 2 are alternately arranged in parallel at regular intervals, and tension is applied in the direction perpendicular to the slits. The sheet is thermally expanded to a temperature above the melting point of the matrix resin to thermally expand the sheet into a porous body, and the sheet is molded into a net shape. Is possible.

[0024]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example 1 0.25 g of xanthan gum was added to 17.5 liters of water while stirring, and glass fibers having an average fiber length of 6 mm were used as reinforcing fibers (415 BB manufactured by Owens Corning Fiberglass). 87.5 g was added to this water and stirred for 5 minutes to disperse well. Next, 87.5 g of high-density polyethylene powder (manufactured by Sumitomo Seika [Co.]] as a matrix resin powder and 3.5 g of a solid acrylic polymer latex as a binder were added to this dispersion, and then 0.5 Wt% Cation Flocculant (Betz Laboratorie
s company make, trade name: Betz 1260) 63 g was gradually added to cause agglomeration to obtain a slurry.

This slurry was added to a sheet machine containing 17.5 liters of water (manufactured by Kumagai Riki Kogyo Co., Ltd.),
Glass fiber reinforced high density polyethylene composite sheet having a basis weight of 325 g / m ² by dewatering on a 0.18 mm screen to obtain a moist sheet, then lightly compressing the sheet and drying at 110 ° C. Got At this time, the glass fiber was 100 parts by weight with respect to 100 parts by weight of polyethylene. A compressed sheet was obtained by heating this sheet under pressure of 20 kg / cm ² under pressure at 170 ° C. and then cooling under pressure at 40 ° C. The compressed sheet had a thickness of 0.3 mm, an apparent density of 1.13 g / cm ³ , and a porosity of 18.7% by volume.

A slit having a length of 20 mm was cut parallel to the entire surface of the above compressed sheet cut into a rectangle having a length of 132 mm and a width of 148 mm. However, the positions of the slits are as shown in FIG. 2, the interval between the slits adjacent in the lateral direction was 4 mm, and the interval between the slits adjacent in the vertical direction was 3 mm. Then, this sheet is stretched in the vertical direction to form a net having a length of 234 mm and a width of 133 mm,
Hang the end of the nail on the wood board and fix it, 170 ℃
After keeping it in the oven set for 10 minutes, taking it out and cooling it sufficiently, the sheet maintains the above net shape even if the fixing nails are removed, and the sheet thermally expands to triple its thickness. In addition, a highly rigid net could be molded. The porosity of the thermally expanded sheet forming the net is 75
% Was calculated.

EXAMPLE 2 0.25 g of xanthan gum was added to 17.5 liters of water while stirring, and then glass fibers having an average fiber length of 6 mm were used as reinforcing fibers (415 BB manufactured by Owens Corning Fiberglass). Add 61 g to this water,
Stir for 5 minutes to disperse well. Next, 114 g of polypropylene powder (manufactured by Mitsui Toatsu Chemicals, Inc.) as a matrix resin powder and 3.5 g of solid acrylic polymer latex were added to this dispersion, and then 0.5% by weight of a cationic coagulant was added. (Betz Laboratories, product name: Be
tz 1260) 63 g was gradually added to cause agglomeration to obtain a slurry.

This slurry was added to a sheet machine containing 17.5 liters of water (manufactured by Kumagai Riki Kogyo Co., Ltd.),
A glass sheet reinforced with glass fiber reinforced polypropylene having a basis weight of 325 g / m ² was obtained by dewatering on a 0.18 mm screen to obtain a wet sheet, then lightly compressing the sheet and drying at 110 ° C. It was At this time, the glass fiber was 53.5 parts by weight with respect to 100 parts by weight of polypropylene. 20kg / cm ^{2 of} this sheet
After heating under pressure at 180 ° C. and pressure cooling at 40 ° C., a compressed sheet was obtained. The compressed sheet had a thickness of 0.24 mm, an apparent density of 1.04 g / cm ³ , and a porosity of 11.1% by volume.

A slit having a length of 20 mm was cut in the same manner as in Example 1 on the entire surface of the above compressed sheet cut into a rectangle having a length of 132 mm and a width of 148 mm. Next, this sheet is stretched in the vertical direction to have a vertical length of 234 mm and a horizontal width of 133 mm.
After making it into a net shape, hook the end part to a nail hit on a wooden board to fix it, hold it in an oven set to 200 ° C for 15 minutes, take it out and cool it sufficiently, even if it is removed from the fixing nail, the sheet Maintained the above net shape, and the sheet was thermally expanded to increase the thickness 2.5 times, and a highly rigid net could be formed. The porosity of the thermally expanded sheet forming the net was calculated to be 65%.

Example 3 A compressed sheet of glass fiber reinforced polypropylene composite sheet, the same as that produced in Example 2, was vertically set to 132 mm,
A length of 1 on the entire surface of a sheet cut into a rectangle with a width of 158 mm
A 0 mm slit was cut parallel to the lateral direction. However, the positions of the slits are as shown in FIG. 2, the interval between the slits adjacent in the lateral direction is 2 mm, and the interval between the slits adjacent in the vertical direction is 1.5 mm. Then, this sheet is stretched in the vertical direction to have a vertical length of 206 mm and a horizontal length of 150 mm.
After making it into a net shape, hook the end part to a nail hit on a wooden board to fix it, hold it in an oven set to 200 ° C for 15 minutes, take it out and cool it sufficiently, even if it is removed from the fixing nail, the sheet Maintained the above net shape, and the sheet was thermally expanded to increase the thickness 2.5 times, and a highly rigid net could be formed. The porosity of the thermally expanded sheet forming the net was calculated to be 65%.

[0032]

As is apparent from the above description, in the net-shaped fiber-reinforced plastic porous body of the present invention, since a large number of narrow width long pieces form a strong net-like shape, the net moves due to wind. Since a stable net shape can be maintained without doing so, a large gap is always maintained and ventilation is good. In addition, the narrow strip itself has high porosity with continuous pores, and can be suitably used as a water-absorbent sheet with little pressure loss and withstanding wind pressure. The net-shaped fiber-reinforced plastic porous body of the present invention is easy to manufacture and can be mass-produced inexpensively.

[Brief description of drawings]

FIG. 1 is a plan view showing an example of a net-shaped fiber-reinforced plastic porous body according to the present invention.

FIG. 2 is an explanatory diagram illustrating a method of slitting.

[Explanation of symbols]

 1 Net-shaped fiber reinforced plastic porous body 2 Narrow strip 3 Direction conversion point

Claims (2)

[Claims] 1. A large number of porous plastics having 5 to 500 parts by weight of reinforcing short fibers having an average fiber length of 1 to 50 mm bonded to 100 parts by weight of a matrix resin in a uniformly dispersed state and having continuous pores. The narrow strip has a zigzag meandering shape, and is integrally connected to adjacent narrow strips at each direction change point of the meander to form a net. Fiber reinforced plastic porous body. 2. The following four steps, (1) 100 parts by weight of matrix resin powder and 5 to 500 parts by weight of reinforcing short fibers having an average fiber length of 1 to 50 mm are dispersed and mixed in water to form a sheet. And (2) pressing the sheet under heating and then pressing it under cooling to densify, (3) a row of a plurality of slits having a constant length a and arranged in a row at a constant interval d. The row A is a row of a plurality of slits having a constant length a and arranged in a horizontal row at a constant distance d, and the position of each slit is laterally displaced from the row A by (a + d) / 2.
A step of cutting a slit into a densified sheet so that the rows and the rows are alternately arranged in parallel at regular intervals, (4) the matrix in the state where the slit-cut sheet is stretched by applying tension in the direction perpendicular to the slits A method for producing a net-shaped fiber-reinforced plastic porous body, comprising the steps of thermally expanding the sheet to a porous body by heating the sheet to a melting point of the resin or higher and forming the sheet into a net-like shape.