JP2016037004A - Method for producing base material for fiber-reinforced plastic formed body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a base material for a fiber-reinforced plastic formed body including the uniformly dispersed reinforced fibers.SOLUTION: There is provided a method of producing a base material for a fiber-reinforced plastic formed body including a reinforced fiber and a thermoplastic resin. The method comprises a process of obtaining a dispersion liquid including the reinforced fiber, thermoplastic resin and dispersion solvent, and a process of making the sheet of the dispersion liquid. The dispersion liquid-obtaining process includes at least first and second processes. The first process comprises dispersing the reinforced fiber in the dispersion solvent having a viscosity of 0.95 mPa s or less to obtain a first dispersion liquid, and the second process comprises conditioning the first dispersion liquid so that the viscosity of the dispersion solvent becomes 1.01 mPa s or higher and further dispersing the reinforced fiber to obtain a second dispersion liquid.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a substrate for a fiber-reinforced plastic molded body. Specifically, the present invention relates to a method for producing a substrate for a fiber-reinforced plastic molded body containing reinforcing fibers and a thermoplastic resin, and the fiber-reinforced plastic molding using a dispersion having good dispersibility of the reinforcing fibers The present invention relates to a method for producing a body substrate.

  A fiber reinforced plastic molded body obtained by heat-pressing a non-woven fabric (hereinafter also referred to as a base material for a fiber reinforced plastic molded body) containing a reinforced fiber such as carbon fiber or glass fiber and a thermoplastic resin is already used in sports, It is used in various fields such as leisure goods and aircraft materials. As a typical method for producing a substrate for a fiber-reinforced plastic molded body, a papermaking method using a wet papermaking technique is known.

  For example, Patent Documents 1 and 2 disclose a production process for producing a nonwoven web by dispersing reinforcing fibers and a thermoplastic resin in an aqueous solvent, supplying the dispersion to a mesh belt, and dehydrating the dispersion. ing. In Patent Documents 1 and 2, a base material for a fiber-reinforced plastic molded body is formed using reinforcing fibers having a fiber length of several millimeters to several tens of millimeters.

JP 60-158227 A JP-A-9-136969

In Patent Documents 1 and 2, various devices have been made in the process of making a dispersion, and a method for producing a homogeneous web has been studied. However, when trying to produce a substrate for fiber-reinforced plastic molded bodies using a conventional manufacturing method, the dispersibility of the reinforcing fibers may deteriorate in the step of obtaining a dispersion, which has been a problem.
Moreover, when the conventional dispersion | distribution method was used, after dispersing reinforcing fiber, it became clear by examination of the present inventors that reinforcing fiber may reaggregate. In such a case, the re-agglomeration lump will remain in the substrate for fiber reinforced plastic molded body, and the reinforcing fibers will not be uniformly dispersed in the substrate for fiber reinforced plastic molded body. Deteriorates and causes problems such as poor design.

  In order to solve the problems of the prior art, the present inventors have studied for the purpose of providing a substrate for a fiber-reinforced plastic molded body in which reinforcing fibers are uniformly dispersed. Furthermore, the present inventors have studied for the purpose of developing a production method capable of enhancing the dispersibility of the reinforcing fibers and suppressing the reaggregation of the reinforcing fibers in the production process of the substrate for the fiber reinforced plastic molded body. Proceeded.

As a result of intensive studies to solve the above problems, the present inventors have provided at least two steps for obtaining a dispersion containing reinforcing fibers and a thermoplastic resin, and the viscosity of the dispersion in each step is determined. It has been found that by controlling within a predetermined range, the dispersibility of the reinforcing fibers in the dispersion can be improved, and further the reaggregation of the reinforcing fibers can be suppressed. Thereby, it discovered that the base material for fiber reinforced plastic molded objects in which the reinforced fiber was disperse | distributed uniformly can be obtained, and came to complete this invention.
Specifically, the present invention has the following configuration.

[1] A method for producing a base material for a fiber-reinforced plastic molded body containing reinforcing fibers and a thermoplastic resin, the step of obtaining a dispersion containing the reinforcing fibers, the thermoplastic resin and a dispersion solvent; and the dispersion And the step of obtaining the dispersion includes at least a first step and a second step, and the first step disperses the reinforcing fibers in a dispersion solvent having a viscosity of 0.95 mPa · s or less. The first dispersion is obtained, and the second step is prepared by using the first dispersion so that the dispersion solvent viscosity is 1.01 mPa · s or more, and the reinforcing fiber is prepared. A method for producing a substrate for a fiber-reinforced plastic molded body, which is a step of further dispersing to obtain a second dispersion.
[2] The second step includes a second step A and a second step B. In the second step A, the dispersion solvent viscosity is 1.01 to 1.20 mPa · s using the first dispersion. s is prepared to further disperse the reinforcing fibers to obtain a second dispersion A. In the second process B, the dispersion solvent viscosity is 1 using the second dispersion A. The method for producing a base material for a fiber-reinforced plastic molded body according to [1], which is a step of preparing the second dispersion liquid B by preparing the liquid so as to be 30 mPa · s or more and further dispersing the reinforcing fibers.
[3] The method for producing a base material for a fiber-reinforced plastic molded article according to [1] or [2], wherein the reinforcing fiber is carbon fiber or glass fiber.
[4] The method for producing a base material for a fiber-reinforced plastic molded body according to any one of [1] to [3], wherein the fiber length of the reinforcing fiber is 10 mm or more.
[5] The method for producing a base material for a fiber-reinforced plastic molded body according to any one of [1] to [4], wherein a viscous agent is added to the second step.
[6] In the first step, the second step A, and the second step B, stirring is performed using a stirrer equipped with a stirring blade, and the shape of the stirring blade used in the second step B is the stirring blade used in the first step. The method for producing a base material for a fiber-reinforced plastic molded body according to any one of [2] to [5], which is different from any of the shapes of the stirring blades used in the second step A.

  According to the production method of the present invention, since the dispersibility of the reinforcing fibers can be increased in the dispersion liquid containing the reinforcing fibers and the thermoplastic resin, the base material for the fiber-reinforced plastic molded body in which the reinforcing fibers are uniformly dispersed. Can be obtained.

FIG. 1 is a schematic diagram for explaining a step of obtaining a dispersion. FIG. 2 is a schematic diagram illustrating a preferred embodiment of the step of obtaining a dispersion.

  Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be made based on representative embodiments and specific examples, but the present invention is not limited to such embodiments. In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

(Manufacturing method of base material for fiber reinforced plastic molding)
The present invention relates to a method for producing a base material for a fiber-reinforced plastic molded body containing reinforcing fibers and a thermoplastic resin. The manufacturing method of the base material for fiber-reinforced plastic molded bodies includes a step of obtaining a dispersion containing reinforcing fibers, a thermoplastic resin, and a dispersion solvent, and a step of making the dispersion. Here, the step of obtaining the dispersion includes at least a first step and a second step. The first step is a step of obtaining a first dispersion by dispersing reinforcing fibers in a dispersion solvent having a viscosity of 0.95 mPa · s or less. The second step is a step of adjusting the dispersion solvent viscosity to be 1.01 mPa · s or more using the first dispersion, further dispersing the reinforcing fibers, and obtaining the second dispersion. The viscosity of the dispersion solvent in the first step may be 0.95 mPa · s or less. The viscosity of the dispersion solvent in the second step may be 1.01 mPa · s or more.

  The second step preferably includes a second step A and a second step B. Here, in the second step A, the first dispersion is used so that the dispersion solvent viscosity is 1.01 to 1.20 mPa · s, the reinforcing fibers are further dispersed, and the second dispersion is used. This is a step of obtaining A. The second step B is a step of preparing the second dispersion B by adjusting the dispersion solvent viscosity to be 1.30 mPa · s or more using the second dispersion A, further dispersing the reinforcing fibers. is there. The step of obtaining the dispersion preferably includes the first step, the second step A, and the second step B in this order.

  Here, the dispersion solvent in each step is an aqueous dispersion solvent using water or an organic solvent dispersion solvent using an organic solvent such as alcohol. In the present invention, an aqueous dispersion that is inexpensive and easy to manage is preferably used as the dispersion solvent. The aqueous dispersion solvent is a dispersion solvent containing at least water, and may consist of water alone, or may contain a solvent other than water, a surfactant, or the like as long as the stability of the aqueous dispersion solvent is not impaired. As water used for the dispersion solvent, distilled water or purified water can be used in addition to normal industrial water. In this water, a surfactant can be mixed as necessary.

  The dispersion solvent used in the present invention specifically refers to a filtrate obtained by filtering the dispersion with an 80 mesh filter (fluid). That is, the viscosity of the dispersion solvent in the first step and the second step refers to the viscosity of a liquid obtained by removing solids such as reinforcing fibers, thermoplastic fibers, and binders from the dispersion. The viscosity of the dispersion solvent can be measured by collecting the filtrate obtained by filtering the dispersion with an 80 mesh filter (fluid) and measuring according to JIS Z 8803 “Method for measuring viscosity of liquid”.

The reinforcing fibers are usually bundled with a sizing agent so as to form a bundle of 12000 to 48000. In the first step, the bond between the bundled reinforcing fibers is weakened. Here, the reinforcing fiber bundle may be dispersed in the reinforcing fibers one by one, but the reinforcing fibers converged in part may remain.
The second step is a step of further dispersing the reinforcing fibers so as to become one reinforcing fiber at a time, and at the same time maintaining the dispersion state of the reinforcing fibers dispersed one by one. When the second step includes the second step A and the second step B, the second step B is preferably a step of maintaining the dispersion state of the reinforcing fibers dispersed one by one.

The first step and the second step may be performed in one dispersion tank. In the case where the first step and the second step are performed in one dispersion tank, after the first process is completed, liquid preparation is performed in the same dispersion tank so that a predetermined dispersion solvent viscosity is obtained.
Moreover, it is good also as performing a 1st process and a 2nd process with a separate dispersion tank, and performing a 1st process and a 2nd process A with the same dispersion tank, and performing only the 2nd process B with another dispersion tank. Alternatively, all three steps of the first step, the second step A, and the second step B may be performed in different dispersion tanks.

  FIG. 1 shows a schematic diagram of a step of obtaining a dispersion when the first step and the second step are performed in separate dispersion tanks. In the step of obtaining the dispersion, at least two dispersion steps (first step and second step) are provided, and each step is preferably performed using each dispersion tank. For example, as shown in FIG. 1, the first step is performed in the first dispersion tank 10, and the second step is performed in the second dispersion tank 20. The first dispersion P containing reinforcing fibers can be obtained by dispersing reinforcing fibers in a dispersion solvent containing water as a main component in the first dispersion tank 10. The first dispersion tank 10 is equipped with a first stirrer 12, and the reinforcing fibers are dispersed by the first stirrer 12. Further, the first dispersion tank 10 is provided with a reinforcing fiber supply device 14, and the reinforcing fibers are fed into the first dispersion tank 10 through the reinforcing fiber supply device 14. The first dispersion tank 10 may be charged with additives such as a sticking agent, but it is preferable that no sticking agent is added in order to enhance the dispersibility of the reinforcing fibers.

  The first dispersion tank 10 and the second dispersion tank 20 are connected by a flow path 18, and the first dispersion P is transferred to the second dispersion tank 20 through the flow path 18. The second dispersion tank 20 is provided with a second stirrer 22, and the reinforcing fibers are further dispersed by the second stirrer 22 to obtain a second dispersion liquid Q. Further, the second dispersion tank 20 is provided with a supply device 24, and the second dispersion tank 20 contains a sticking agent or a sticking agent so that the second dispersion liquid Q has a predetermined viscosity. A dispersion solvent is charged. In FIG. 1, the flow path 18 is connected to the bottom of the first dispersion tank 10, but the connection part may be either the side or the top.

  In the present invention, as described above, at least two dispersion steps are provided, and in each dispersion step, the dispersibility of the reinforcing fibers can be improved by controlling the viscosity of the dispersion solvent to be in a specific range. it can. Furthermore, in this invention, it can suppress that a reinforced fiber reaggregates by disperse | distributing a reinforced fiber on said conditions. Here, the reaggregation of reinforcing fibers means that the reinforcing fibers once dispersed again become aggregated aggregates.

  In the second step, a desired viscosity can be obtained by adding a sticking agent to the dispersion tank. Examples of the sticking agent include polyacrylamide and polyethylene oxide. Among them, it is preferable to use polyacrylamide, and it is more preferable to use polyacrylamide having a weight average molecular weight of 1000 to 24 million. The polyacrylamide is particularly preferably anionic.

  It is preferable that the sticky powder is dissolved in advance and added in the form of an aqueous solution. For example, when using polyacrylamide, it is preferable to add it by dissolving in 0.01 to 0.3% by mass in advance.

  In the first step, it is preferable not to add polyacrylamide to the dispersion solvent in which the reinforcing fibers are dispersed. Also. In the second step, it is preferable to add 4 to 11 ppm of polyacrylamide having a weight average molecular weight of 1500 to 20 million to the first dispersion.

  In the first step, it is preferred that less than 2 ppm of the sticky agent is added, and it is more preferred that no sticky agent is added. In the second step, 4 ppm of polyacrylamide having a weight average molecular weight of 1500 to 20 million is preferably added, more preferably 6 ppm or more, and even more preferably 11 ppm or more. When the second step includes the second step A and the second step B, it is preferable that 4 to 11 ppm of polyacrylamide having a weight average molecular weight of 1500 to 20 million is added in the second step A, More preferably, 11 ppm is added. In the second step B, polyacrylamide having a weight average molecular weight of 1500 to 20 million is preferably added in an amount of 15 to 100 ppm, more preferably 20 to 70 ppm, and further preferably 25 to 50 ppm.

  In the second step, the thermoplastic resin may be charged into the second dispersion tank 20, or may be mixed with a dispersion of reinforcing fibers after being dispersed in another dispersion tank.

  In the step of obtaining the dispersion, at least two dispersion steps may be provided, and three or more steps are preferably provided. That is, in the step of obtaining the dispersion, it is preferable to provide two or more dispersion tanks, and more preferably three or more tanks.

  FIG. 2 shows a schematic diagram of a dispersion process in which three dispersion tanks are provided. As shown in FIG. 2, in the step of obtaining the dispersion liquid, it is preferable that three dispersion steps are provided. As shown in FIG. 2, the first process is performed in the first dispersion tank 10, the second process A is performed in the second dispersion tank 20, and the second process B is performed in the second dispersion tank 20. This is performed in the dispersion tank 30. The first dispersion P containing reinforcing fibers is obtained by dispersing reinforcing fibers in the first dispersion tank 10. The first dispersion tank 10 is equipped with a first stirrer 12, and the reinforcing fibers are dispersed by the first stirrer 12. Further, the first dispersion tank 10 is provided with a reinforcing fiber supply device 14, and the reinforcing fibers are fed into the first dispersion tank 10 through the reinforcing fiber supply device 14.

  The first dispersion tank 10 and the second dispersion tank 20 are connected by a flow path 18, and the first dispersion P is transferred to the second dispersion tank 20 through the flow path 18. The second dispersion tank 20 is provided with a second stirrer 22, and the reinforcing fibers are further dispersed by the second stirrer 22. In addition, the second dispersion tank 20 is provided with a supply device 24, and the second dispersion tank 20 has a viscous agent so that the dispersion liquid Q (second dispersion liquid A) has a predetermined viscosity. Alternatively, a dispersion solvent containing a sticking agent is added.

  The second dispersion tank 20 and the second dispersion tank 30 are connected by a flow path 28, and the second dispersion liquid Q is transferred to the second dispersion tank 30 through the flow path 28. The second dispersion tank 30 is provided with a second stirrer 32, and the reinforcing fibers are further dispersed by the second stirrer 32. Further, the second dispersion tank 30 is provided with a supply device 34, and the second dispersion tank 20 has a viscous agent so that the dispersion liquid R (second dispersion liquid B) has a predetermined viscosity. Alternatively, a dispersion solvent containing a sticking agent is further added.

In a plurality of dispersion tanks, it is preferable that the rotation speed of the stirrer is different from each other. Specifically, the rotation speed in the first step is preferably 200 to 3600 rpm, more preferably 300 to 3300 rpm, and further preferably 350 to 3000 rpm. The rotation speed in the second step is preferably less than 300 rpm. Furthermore, the rotation speed of the second step A is more preferably 200 rpm or more and less than 300 rpm, and the rotation speed of the second step B is more preferably less than 200 rpm.
In the present invention, in the first step, stirring is performed for a short time and at a high rotational speed, so that the bundled reinforcing fibers become familiar with water and are easily dispersed into each one. Thus, the 1st dispersion liquid containing the fiber which became the state which is easy to disperse | distribute is transferred to a 2nd process. Preferably, after being transferred to the second step A, it is transferred to the second step B. In the second step A, the fibers are dispersed one by one. Here, the reinforcing fiber once dispersed has a property of being easily re-aggregated. In particular, reaggregation tends to occur when the stirring time of the dispersion becomes long. However, in the present invention, the re-aggregation of the reinforcing fibers can be suppressed by providing a plurality of dispersion steps and defining the viscosity of the dispersion liquid in each step.

  In a plurality of dispersion tanks, stirring is performed using a stirrer equipped with stirring blades. Here, the shape of the stirring blade used in the second step B is preferably different from both the shape of the stirring blade used in the first step and the shape of the stirring blade used in the second step A. When stirring blades having the same shape are used, it is preferable to reduce the rotational speed in the second process A and the second process B, and the rotational speed in the second process B is lower than that in the first process and the second process A. It is more preferable.

In the first step and the second step A, it is preferable to use a stirring blade capable of generating a shearing force by performing strong stirring. From such a viewpoint, a pulper for disaggregating pulp for papermaking, waste paper, and the like can also be preferably used. Moreover, a propeller type and a turbine type can also be used preferably.
In the 2nd process B, since it stirs for prevention of sedimentation of a fiber and maintenance of a dispersed state, the strong stirring power like the 1st process and the 2nd process A is unnecessary. On the other hand, in this step, since stirring is continued for a long time, there is a problem that a molecular chain such as polyacrylamide is cut and the viscosity is lowered with time. From such a viewpoint, an agitator having a weak shearing force is preferable, and a double ribbon type, a screw type, a gate paddle type, or the like is preferably used. A propeller type can also be used. In this case, it is preferable that the rotational speed be lower than those in the first step and the second step A.

A dispersing agent, a binder component, a pigment, a colorant, a filling amount, and the like may be further added to the dispersing tank used in each dispersing step.
As the dispersant, generally used surfactants can be used, and examples thereof include polyether, polyester, alkylbetaine, and stearic acid.
As the binder component, acrylic resin, styrene-acrylic resin, polyester resin, modified polyester resin, polyethylene resin, polypropylene resin, EVA resin, urethane resin, PVA resin and the like can be used. In addition, these binder components may be used individually by 1 type, and may be used in combination of 2 or more types.

  It is preferable to add the reinforcing fiber to the dispersion tank 10 so as to be 0.1 to 2.0% by mass with respect to the total mass of the dispersion P. Moreover, it is preferable to add a thermoplastic resin so that it may become 0.1-2.0 mass%. The content of the reinforcing fiber and the thermoplastic resin may be within the above range in the dispersion Q and the dispersion R, but more preferably the content of the reinforcing fiber and the thermoplastic resin is 0.1 to 10, respectively. More preferably, it is 0.5 mass%.

The stirring time in the dispersion tank 10 is preferably 10 to 300 seconds, and the stirring time in the dispersion tank 20 is preferably 10 to 300 seconds. Further, the dispersion layer 30 can maintain a good dispersion state for 120 minutes or more. For this reason, continuous production can be performed stably.
Further, the stirring time in all the dispersion steps is preferably within 10 hours, and preferably within 5 hours. In the present invention, even when the dispersion process takes 2 hours or more, the reinforcing fibers can be kept in good pores without causing reaggregation of the reinforcing fibers.

(Reinforced fiber)
The reinforcing fiber supply device 14 supplies the reinforcing fibers to the dispersion tank 10. Examples of the reinforcing fibers include inorganic fibers such as glass fibers and carbon fibers. Among these, carbon fibers are preferably used. In addition, these inorganic fibers may use 1 type and may use multiple types. Furthermore, in the present invention, the reinforcing fibers may contain organic fibers excellent in heat resistance such as aramid fibers and PBO (polyparaphenylene benzoxazole) fibers in addition to such inorganic fibers.

The reinforcing fibers are preferably chopped strands cut to a certain length. By setting it as such a form, a reinforced fiber can be mixed uniformly. Moreover, the production efficiency of the fiber-reinforced plastic molded body can be increased. When cutting the reinforcing fibers into a certain length, it is preferable to cut the reinforcing fibers in a bundled form having a width of about 10 to 100 mm with a sizing agent. Thereby, cut length can be made uniform and the production efficiency of a chopped strand can be improved.
As the sizing agent, a general one such as an epoxy type or a PVA type can be used, and a preferable addition amount is 2% by mass or less with respect to the total mass of the reinforcing fiber.

  The fiber length of the reinforcing fiber is preferably 10 mm or more, more preferably 20 mm or more, further preferably 30 mm or more, and further preferably 50 mm or more. Thus, in the present invention, it is possible to use a reinforcing fiber having a long fiber length, and the dispersibility of such a reinforcing fiber can also be improved.

  Although it does not specifically limit as a fiber diameter of a reinforced fiber, 3-25 micrometers is preferable. By making the fiber diameter of the reinforcing fiber within the above range, it can be prevented from being taken into the human body during the manufacturing process or during use, and sufficient strength can be obtained.

  When the reinforcing fiber is carbon fiber, the single fiber strength of the carbon fiber is preferably 4500 MPa or more, and more preferably 4700 MPa or more. Single fiber strength refers to the tensile strength of a monofilament. When such a carbon fiber is used, the strength is greatly improved. The single fiber strength can be measured according to JIS R7601 “Test method for carbon fiber”.

(Thermoplastic resin)
The thermoplastic resin forms a binding point at the intersection of the matrix or the fiber component during the heat and pressure treatment of the substrate for a fiber-reinforced plastic molded body.

  The thermoplastic resin is preferably fibrous. This thermoplastic resin fiber maintains the fiber form until the heating and pressurizing treatment is performed on the substrate for fiber reinforced plastic molding, and it is preferable that voids exist in the substrate. Such a substrate for a fiber-reinforced plastic molded body has the characteristics that it is flexible and has a drape property, can be stored and transported in a wound form, and has excellent handling properties.

  As thermoplastic resins, polycarbonate (PC), polyetheretherketone (PEEK), polyamideimide (PAI), polyphenylene sulfide (PPS), polyetherimide (PEI), polyetherketoneketone (PEKK), polyamide, polypropylene, etc. Can be illustrated. One type of these thermoplastic resins may be used alone, or two or more types may be used in combination. Of these thermoplastic resins, polycarbonate, polyetherimide, polyamide (nylon), and polypropylene are preferably used in order to obtain a high-strength fiber-reinforced plastic molded product. Furthermore, the thermoplastic resin is preferably a fiber, and it is preferable to use polycarbonate fiber, polyetherimide fiber, polyamide (nylon) fiber, or polypropylene fiber having good fiber dispersibility.

When the thermoplastic resin is a fiber, the fiber length of the thermoplastic fiber is preferably 2 to 100 mm, more preferably 5 to 50 mm, and still more preferably 10 to 25 mm. By setting the fiber length of the thermoplastic fiber within the above range, it is possible to prevent the thermoplastic fiber from dropping off from the base material for the fiber-reinforced plastic molded body, and the fiber has excellent bending strength and impact resistance. A reinforced plastic molded body can be molded. Moreover, the dispersibility of a thermoplastic fiber can be made favorable by making the fiber length of a thermoplastic fiber into the said range. Thereby, the fiber reinforced plastic molding after heat-press molding has good strength and appearance.
The thermoplastic fibers are preferably chopped strands cut to a certain length. With such a form, the thermoplastic fiber can be uniformly mixed in the substrate for a fiber-reinforced plastic molded body. Moreover, the cross-sectional shape of the fiber is not limited to a circular shape, and an elliptical shape or a modified cross-sectional shape can also be used.

(Substrate for fiber reinforced plastic molding)
In the base material for fiber-reinforced plastic molded bodies produced by the production method as described above, the reinforcing fibers are uniformly dispersed. In addition, when the manufacturing method as described above is used, the reinforcing fibers are well dispersed in the dispersion step and the dispersed state is maintained, so that the reinforcing fibers are uniformly dispersed in the substrate for the fiber reinforced plastic molded body. be able to. For this reason, the fiber reinforced plastic molded object obtained by heat-press-molding such a base material for fiber reinforced plastic molded objects has the outstanding intensity | strength.

  The base material for a fiber-reinforced plastic molded body obtained by the production method of the present invention can contain fibers having a fiber length of 10 mm or more, preferably 50 mm or more. By containing the reinforcing fiber having such a fiber length, the strength of the fiber-reinforced plastic molded body obtained by heat-press molding the substrate for fiber-reinforced plastic molded body can be further increased.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

Example 1
500 L of water was introduced into a waste paper disintegrating pulper equipped with a propeller type agitator (Aikawa Tekko Co., Ltd., capacity 600 L), and 1.0 kg of carbon fiber having a fiber length of 12 mm (CS815, manufactured by Taiwan Plastics Co., Ltd.) was introduced. Furthermore, 1 kg of 0.5% aqueous solution of Emanon (registered trademark) 3199V (manufactured by Kao Corporation) was added as a dispersant, and the propeller type agitator was stirred at 90 rpm for 90 seconds (first step).

Next, 2.5 kg of a 0.2% solution of a polyacrylamide-based adhesive (FA-40 manufactured by MT Aquapolymer, weight average molecular weight: 17 million) was added. Furthermore, 1 kg of polycarbonate fiber (Daiwabo Polytech, fiber diameter 30μ, fiber length 15 mm) and 0.04 kg of PVA fiber (VPB105-2, Kuraray Co., Ltd.) as a binder are soaked in 60 L of water in advance. I put it in. Then, stirring was continued with the rotation speed of the propeller-type agitator set at 250 rpm (second step). Then, when 10 minutes have passed, 60 minutes have passed, and 120 minutes have passed, the fiber dispersion is supplied to the inclined wire type paper machine at a speed of 5.5 L / min, and the width is 50 cm and the basis weight is 22 g / m ² . A substrate for a fiber-reinforced plastic molded body was obtained.

(Example 2)
500 L of water was introduced into a waste paper disintegrating pulper equipped with a propeller type agitator (Aikawa Tekko Co., Ltd., capacity 600 L), and 1.0 kg of carbon fiber having a fiber length of 12 mm (CS815, manufactured by Taiwan Plastics Co., Ltd.) was introduced. Furthermore, 1 kg of 0.5% aqueous solution of Emanon (registered trademark) 3199V (manufactured by Kao Corporation) was added as a dispersant, and the propeller-type agitator was stirred at 90 rpm for 90 seconds to stop stirring (first step) ).

  Next, 2.5 kg of a 0.2% solution of a polyacrylamide-based adhesive (FA-40 manufactured by MT Aquapolymer, weight average molecular weight: 17 million) was added. Furthermore, 0.96 kg of polycarbonate fiber (Daiwabo Polytech, fiber diameter 30 μ, fiber length 15 mm) and 0.04 kg of PVA fiber (VPB105-2, Kuraray), which is a binder, are previously immersed in 60 L of water. I put it in the pulper. Then, the rotation speed of the propeller-type agitator was stirred at 250 rpm for 20 seconds (second step A).

Thereafter, 4 kg of a 0.2% solution of a polyacrylamide-based viscosity agent (FA-40 manufactured by MT Aquapolymer Co., Ltd., weight average molecular weight 17 million) was added, and stirring was continued at 100 rpm (second step B). When 10 minutes, 60 minutes and 120 minutes have passed, the fiber dispersion is supplied to the inclined wire type paper machine at a speed of 5.5 L / min, and the fiber having a width of 50 cm and a basis weight of 22 g / m ² A base material for reinforced plastic molding was obtained.

(Example 3)
500 L of water was introduced into a waste paper disintegrating pulper equipped with a propeller-type agitator (Aikawa Tekko Co., Ltd., capacity 600 L), and 2.5 kg of carbon fiber having a fiber length of 12 mm (CS815, Taiwan Plastic Co., Ltd.) was introduced. Furthermore, 2.5 kg of 0.5% aqueous solution of Emanon (registered trademark) 3199V (manufactured by Kao Corporation) was added as a dispersant, and the propeller type agitator was stirred at 90 rpm for 90 seconds (first step).

  Next, 1.0 kg of a 0.2% solution of a polyacrylamide-based viscosity agent (FA-40 manufactured by MT Aquapolymer Co., Ltd., weight average molecular weight 17 million) was added and stirred for 60 seconds (second step A). All of the dispersion in the pulper was transferred to a 2800 L container having a propeller-type agitator.

Separately from the first step and the second step A described above, 500 L of water is again introduced into the above-mentioned waste paper disaggregation pulper, and polycarbonate fiber (manufactured by Daiwabo Polytech Co., Ltd., fiber diameter 30 μ, fiber length 15 mm), 2.4 kg, 0.1 kg of PVA fiber (VPB105-2 manufactured by Kuraray Co., Ltd.) as a binder was added. Then, 2.5 kg of 0.5% aqueous solution of Emanon (registered trademark) 3199V (manufactured by Kao Corporation) was added as a dispersant, and the propeller-type agitator was stirred at 90 rpm for 90 seconds. Then, 1.0 kg of a 0.2% solution of a polyacrylamide-based viscosity agent (FA-40 manufactured by MT Aquapolymer Co., Ltd., weight average molecular weight 17 million) was added to the pulper and stirred for 60 seconds. Then, the dispersion liquid containing this polycarbonate fiber etc. was transferred to the 2800L container which has said propeller type agitator. At this time, the 2800L container is in a state where a dispersion of carbon fiber and polyacrylamide-based viscous agent and a dispersion of polycarbonate fiber and PVA fiber are charged.
Next, water was added to the 2800 L container to make 2500 L, thereby obtaining a dispersion having a dispersion solid content concentration of 0.2% by mass.

Furthermore, 40 kg of a 0.2% solution of a polyacrylamide-based viscosity agent (FA-40 manufactured by MT Aquapolymer Co., Ltd., weight average molecular weight 17 million) was added to the obtained dispersion, and stirring was continued at 300 rpm ( Second step B) When 10 minutes have passed, 60 minutes have passed and 120 minutes have passed, this fiber dispersion is supplied to the inclined wire type paper machine at a speed of 5.5 L / min, and the width is 50 cm and the basis weight is 22 g. A base material for a fiber-reinforced plastic molded body having an area of / m ² was obtained.

Example 4
A substrate for a fiber-reinforced plastic molded body was obtained in the same manner as in Example 3 except that the agitator used in the second step 2B in Example 3 was changed to a paddle type.

(Comparative Example 1)
A base material for a fiber-reinforced plastic molded article was obtained in the same manner as in Example 1 except that a 0.2% solution of a polyacrylamide-based adhesive (FA-40, manufactured by MT Aquapolymer Co., Ltd., weight average molecular weight: 17 million) was not added. .

(Comparative Example 2)
500 L of water was added to a waste paper disaggregation pulper (Aikawa Tekko Co., Ltd., capacity 600 L), and 1.0 kg of carbon fiber having a fiber length of 12 mm (CS815 manufactured by Taiwan Plastics Co., Ltd.) was added. Next, 1 kg of 0.5% aqueous solution of Emanon (registered trademark) 3199V (manufactured by Kao Corporation) was added as a dispersant, and 0 of polyacrylamide-based adhesive (FA-40, MT Aquapolymer, weight average molecular weight 17 million) was added. 2.5 kg of 2% solution was added. Then, it stirred at 600 rpm for 90 seconds, and stirring was stopped.
Furthermore, 0.96 kg of polycarbonate fiber (Daiwabo Polytech, fiber diameter 30 μ, fiber length 15 mm) and 0.04 kg of PVA fiber (VPB105-2, Kuraray), which is a binder, are previously immersed in 60 L of water. I put it in the pulper. And it stirred for 20 minutes at 100 rpm.
Thereafter, the fiber dispersion was added at a speed of 5.5 L / min at the time of 10 minutes, 60 minutes, and 120 minutes, respectively, while stirring was continued at 100 rpm without adding a sticky agent. It supplied to the inclined wire type | mold paper machine, and obtained the base material for fiber reinforced plastic moldings of width 50cm and basic weight 22g / m < ² >.

(Viscosity measurement)
The viscosity of the dispersion solvent in each step was measured as follows.
First, 500 g of the dispersion liquid in each step was collected and filtered through an 80 mesh sieve, and the filtrate was collected. Next, the viscosity of this filtrate was measured with a Canon-Fenske viscometer in accordance with the viscosity measurement method of JIS-Z8803: 2011 liquid.

(Slurry concentration)
The slurry concentration in each step is the concentration of fibers in the dispersion. Specifically, the total concentration of solids (reinforced fibers, thermoplastic fibers, binder fibers, etc.) contained in the dispersion was taken as the slurry concentration.
Slurry concentration (mass%) = dry weight of solid content / mass of dispersion × 100

(Evaluation)
Fiber bundles having a width of 0.5 mm or more present in a 10 cm square of the substrate for fiber-reinforced plastic molded body formed using the dispersion for each stirring time were counted visually. The width of the fiber bundle is defined as the longer one (the length in the width direction and the thickness direction) of the two lengths excluding the length direction of the fiber bundle (an arbitrary length in the case of the same).
A: The base material contains 0 to 10 fiber bundles having a width of 0.5 mm or more B: The base material contains 11 to 80 fiber bundles having a width of 0.5 mm or more C: The base material contains 81 to 150 fiber bundles having a width of 0.5 mm or more D: The base material contains 151 or more fiber bundles having a width of 0.5 mm or more Table 1 shows the evaluation results. Show.

  As shown in Table 1, by adjusting to a predetermined viscosity in each dispersion step, carbon fibers are dispersed well, aggregation of carbon fibers is prevented, and a dispersion in which carbon fibers are well dispersed is obtained. Can do. It can also be seen that the dispersion state of the carbon fibers is well maintained even in the dispersion liquid that has passed for a long time after the start of dispersion. When paper is made using such a dispersion, a substrate for a fiber-reinforced plastic molded body in which carbon fibers are uniformly dispersed can be obtained. When this base material for fiber reinforced plastic molding is heated and pressed, a fiber reinforced plastic molding excellent in strength and appearance can be obtained.

DESCRIPTION OF SYMBOLS 10 1st dispersion tank 12 1st stirrer 14 Reinforcing fiber supply apparatus 18 Flow path 20 2nd dispersion tank 22 2nd stirrer 24 Supply apparatus 28 Flow path 30 2nd dispersion tank 32 2nd stirrer 34 Supply device P First dispersion Q Second dispersion A
R Second dispersion B

Claims (6)

A method for producing a base material for a fiber-reinforced plastic molded body comprising reinforcing fibers and a thermoplastic resin,
Obtaining a dispersion containing the reinforcing fiber, the thermoplastic resin and a dispersion solvent;
Including the step of making the dispersion.
The step of obtaining the dispersion includes at least a first step and a second step,
The first step is a step of obtaining the first dispersion by dispersing the reinforcing fibers in a dispersion solvent having a viscosity of 0.95 mPa · s or less,
The second step is a step of preparing a second dispersion by adjusting the dispersion solvent viscosity to be 1.01 mPa · s or more using the first dispersion and further dispersing the reinforcing fibers. A method for producing a substrate for a fiber-reinforced plastic molded article, which is characterized in that: The second step includes a second step A and a second step B,
In the second step A, the dispersion liquid viscosity is adjusted to 1.01 to 1.20 mPa · s using the first dispersion liquid, and the reinforcing fibers are further dispersed, and the second dispersion liquid. A step of obtaining A,
In the second step B, the dispersion liquid viscosity is adjusted to be 1.30 mPa · s or more using the second dispersion liquid A, and the reinforcing fibers are further dispersed to obtain the second dispersion liquid B. The method for producing a substrate for a fiber-reinforced plastic molded body according to claim 1, which is a process.   The method for producing a substrate for a fiber-reinforced plastic molded body according to claim 1 or 2, wherein the reinforcing fibers are carbon fibers or glass fibers.   The fiber length of the said reinforced fiber is 10 mm or more, The manufacturing method of the base material for fiber reinforced plastic moldings of any one of Claims 1-3.   The method for producing a base material for a fiber-reinforced plastic molded body according to any one of claims 1 to 4, wherein a sticky agent is added to the second step. In the first step, the second step A and the second step B, stirring is performed using a stirrer equipped with stirring blades,
The shape of the stirring blade used in the second step B is different from any of the shape of the stirring blade used in the first step and the shape of the stirring blade used in the second step A according to any one of claims 2 to 5. The manufacturing method of the base material for fiber reinforced plastic molding of description.

Images