JP2000233421A - Preparation of long fiber-reinforced thermoplastic resin molded body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve mechanical strength of a long fiber-reinforced thermoplastic(LFRTP) molded body obtd. SOLUTION: In this method for preparation, an LFRTP base material is used alone or the base material is diluted with a non-reinforcing resin and a melted article is prepd. by means of a heating delivering machine in such a way that mean length of the fiber in the melted article is held at a length being at least 40% of the length of the original LFRTP base material and the melted article is fed into a mold to perform press molding. The LFRTP base material is an LFRTP base material with a mean diameter or a mean thickness of 0.05-2.5 mm and a fiber content of 15-80 vol.% which is prepd. by impregnating one or a plurality of continuous filament strands with a thermoplastic resin and performing pultrusion thereof from a nozzle and cutting it into a mean length of 10-50 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a long fiber reinforced thermoplastic resin (hereinafter referred to as "LFRTP") suitable for automobile parts, home appliances, industrial materials, civil engineering materials and the like which require surface appearance, high strength and high rigidity. ).

[0002]

2. Description of the Related Art Conventionally, in a method for producing an LFRTP molded article, an LFRTP having a diameter of about 2 to 3 mm obtained by cutting a thermoplastic resin containing reinforcing fibers (hereinafter simply referred to as "fibers") arranged in a specific direction into a predetermined shape. There is known a method in which a base material is heated and melted to produce a molded body by an injection molding method. The LFRTP base material used in this method has a longer fiber length than the conventional short fiber reinforced thermoplastic resin base material obtained by kneading a thermoplastic resin and fibers, and maintains the fiber length in a molded body longer. Since the fiber was previously impregnated with the thermoplastic resin, the molded article formed from the fiber had excellent mechanical strength and surface appearance.

[0003]

However, even when the LFRTP base material having a long fiber length used in the above method is used, a large shear is applied due to the high pressure at the time of kneading or injection by a screw having a high compression ratio, so that the molded product has a large length. The fiber length of the molded article was shortened, and as a result, there was a problem that the mechanical strength such as the impact strength and the tensile strength of the molded article was inferior.

[0004] Further, there is known an LFRTP base material sheet obtained by dispersing the above LFRTP base material, and heat-molding the LFRTP base material. (Japanese Patent Laid-Open No. 9-109)
No. 310). In this method, the preformed L
If a FRTP substrate sheet is prepared, it is a simple method of setting the sheet in a molding die after heating and melting the sheet, and molding the resulting molded article. Although it is possible to obtain a high-strength molded product, the melt-softening of the thermoplastic resin must be performed three times, including the steps of preparing the LFRTP base material, forming the sheet, and pressing the LFRTP substrate. However, there is a problem in terms of energy efficiency and thermal degradation of the resin. Further, in order to improve fluidity during molding, LF
If the inside of the RTP base material sheet is sufficiently heated and melted, the above-mentioned sheet is soft and the handleability is poor, and there is a problem that the work becomes complicated when ordinary flow molding in which a plurality of the sheets are laminated in a mold. Was. Accordingly, an object of the present invention is to solve the above conventional problems and improve the mechanical strength of the obtained LFRTP molded article.

[0005]

The above object is achieved by the present invention described below. That is, the present invention relates to the production of an LFRTP molded article in which an LFRTP substrate is used alone or the substrate is diluted with a non-reinforced resin and melted to produce a melt, and the melt is supplied to a mold and press-molded. In the method, the LF
RTP base material, one or more continuous fiber strands are impregnated with a thermoplastic resin, pulled out from the nozzle, and cut to an average length of 10 to 50 mm and an average diameter or an average thickness of 0.05.
LF with a fiber content of 15 to 80% by volume
An RTP base material, wherein the base material is manufactured and molded by using a heating and conveying machine to produce a melt in which the average length of the fibers in the melt is at least 40% of the original LFRTP base length. L
Provided is a method for producing an FRTP molded article.

In the present invention, when the LFRTP base material is heated and transported, the average length of the fibers in the melt is changed to the original LFRT.
By preparing a melt holding a length of 40% or more of the P base length, the average length of the fibers in the molded body can be maintained long, and the mechanical strength of the molded body can be improved.

Further, in the present invention, since molding is performed without forming a sheet accompanied by a heating step, thermal deterioration of the resin is suppressed, and complicated work of the prior art of moving a plurality of softened molten sheets to a molding die. Is unnecessary.

[0008]

Next, the present invention will be described in more detail with reference to preferred embodiments. The thermoplastic resin used in the present invention is not particularly limited, and various commercially available resins can be used. For example, polyolefin-based resins, polyamide-based resins, polyester-based resins, polycarbonate resins, polyphenylene sulfide resins, polystyrene and the like can be mentioned. Among them, polyolefin-based resins, polyamide-based resins, and polyester-based resins are preferred in the present invention from the viewpoints of impregnation, cost, and physical properties. As the polyolefin resin, for example,
Polypropylene, polyethylene and the like; polyamide resins such as nylon 6,6, nylon 6, nylon 12, and MXD nylon; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; Is particularly preferred in the present invention. These resins may be mixed with additives such as a coloring agent, a denaturant, an antioxidant and an ultraviolet ray-resistant agent, and fillers such as calcium carbonate, talc and mica.

The fibers used for the LFRTP substrate in the present invention include, for example, glass fibers, carbon fibers, aramid fibers, ceramic fibers and the like, and these can be used alone or in combination. Among them, the use of glass fiber is preferable because of its excellent cost performance.

The above fibers usually have an average monofilament diameter of 6 to 23 μm, and more preferably 10 to 17 μm.
It is preferred that Average monofilament diameter is 6
If it is less than μm, the cost of the molded body increases, and L
When the content of the fibers in the FRTP base material is the same, the surface area of the fibers becomes large, and the fluidity during molding is inferior. On the other hand, the average diameter of the monofilament is 23μ.
If it exceeds m, the mechanical properties of the finally obtained LFRTP molded product are inferior, which is not preferable.

[0011] The continuous fibers before cutting preferably have 100 to 12,000 filaments. If the number of filaments is less than 100, a large number of LF
An RTP substrate is required, and the operation becomes complicated. On the other hand, when the number of filaments exceeds 12,000, it becomes difficult to uniformly impregnate the thermoplastic resin even between the monofilaments, and the obtained LFRTP base material becomes thick, and it becomes difficult to obtain the LFRTP base material diameter described later. . Furthermore, when the LFRTP molded article is used, the dispersibility of the fiber is inferior, and the expected strength of the finally obtained LFRTP molded article cannot be exhibited. In addition, LF described later
The average diameter or average thickness of the RTP substrate is 0.05 to 1.5
When the diameter is as thin as mm, the number of filaments is preferably 100 to 6000 in consideration of the fiber content.

Further, the LFRTP substrate used in the present invention comprises:
It is essential that the average diameter or the average thickness is 0.05 to 2.5 mm. If the average diameter or the average thickness of the LFRTP base material is less than 0.05 mm, filament production or feathering may occur when producing the LFRTP base material, resulting in poor productivity. On the other hand, if it exceeds 2.5 mm, the heating efficiency at the time of heating and transporting is inferior, and the obtained LFRTP base material is thicker or thicker, and the dispersibility of the fiber is inferior. The desired mechanical strength cannot be exhibited, which is not preferable. Further, the thickness is preferably 0.05 to 1.5 mm. When the LFRTP base material having a small diameter or thickness in the above range is used, the dispersion of the fibers becomes good during the molding, and a uniform and high-strength molded article can be obtained. In addition, LFRT
By reducing the diameter or thickness of the P base material in the above range, the heating efficiency can be increased, the LFRTP base material can be easily melted, and breakage of the fiber during transportation is reduced.

[0013] The LFRTP substrate used in the present invention comprises:
The fiber content is usually 15 to 80% by volume, and preferably 20 to 70% by volume. When the fiber content is less than 15% by volume, the reinforcing effect of the fiber on the molded article is low. On the other hand, when the fiber content exceeds 80% by volume, the relative amount of the matrix (thermoplastic resin) wrapping the fibers Is too small, it is difficult to secure the impregnation rate of the resin described later at 95% or more. Here, the average diameter is an average of the cross-sectional diameters of five arbitrary LFRTP base materials, with the average diameter of the major and minor diameters of the cross-section of the base material as the cross-sectional diameter.

The LFRTP substrate used in the present invention preferably has an impregnation ratio of 95% or more of the thermoplastic resin. When the impregnation rate of the thermoplastic resin in the obtained LFRTP molded article is less than 95%, generation of fluff or breakage of filaments during plasticization is promoted during production of the LFRTP base material, or the obtained molded article is formed. This is not preferable because the fibers may emerge on the surface of the glass. Here, the impregnation ratio of the resin is defined as follows: When a cross section of the LFRTP base material is observed with an electron microscope of 200 times, a 20 μm mesh is placed, and if any voids (air bubbles) are observed in the cells of the mesh, The cell of the mesh is added as a void area, and it is obtained by the following formula from the observed total cross-sectional area and the void area. ｛(Total cross-section-void area) / total cross-section｝ × 100
(%)

The length of the LFRTP substrate used in the present invention is as follows:
Required to be 10 to 50 mm, 15 to 40 mm
It is preferred that Since the LFRTP substrate of the present invention is obtained by cutting a continuous fiber by impregnating a thermoplastic resin, the length of the LFRTP substrate is substantially equal to the length of the fiber in the substrate. Therefore, when the cut length is less than 10 mm, even if the average length of the fibers in the melt obtained by heating and melting is maintained at 40% or more of the LFRTP base material length before heating and melting, the final length is not obtained. This is not preferred because the mechanical properties of the resulting LFRTP molded article are inferior. On the other hand, when the cutting length is 5
If it exceeds 0 mm, it is not preferable because the handleability at the time of introduction into the heating transfer machine is poor, and the flowability of the LFRTP base material during press molding is poor.

The method for producing the LFRTP base material is as follows. A fiber strand is fed into a resin impregnation tank, a resin is impregnated into the fiber strand by a melt impregnation method, and then one or a plurality of fiber strands are injected with one nozzle. Pull out L
A method for obtaining an FRTP substrate is preferred. Furthermore, if a method of pulling out one bundled fiber strand from one nozzle without applying splitting is adopted, pulling out from the nozzle becomes easy, the fiber content can be increased, and the generation of fluff can be reduced. This is preferable because it can be reduced.

In this method, the smaller diameter LFRTP
A base material is easily obtained. Since the obtained LFRTP base material has a small heat capacity and can be easily softened or solidified, and the heating time can be reduced,
It is possible to minimize the thermal degradation of the resin during heating, and it is possible to lengthen the remaining fiber length of the melt.

The method for producing an LFRTP molded article of the present invention comprises:
The above-mentioned LFRTP base material or a mixture of the base material and a non-reinforced resin (hereinafter, the mixture is also simply referred to as “LFRTP base material”) is used, or a lump obtained by assembling the LFRTP base material is heated and conveyed. The melt is produced by transporting while heating and melting so that the average length of the fibers in the product is maintained at 40% or more, preferably 60% or more, more preferably 80% or more of the original LFRTP base material length, In this method, the melt is supplied to a mold and press-molded. The non-reinforced resin used in the above-mentioned mixture is a thermoplastic resin substantially free of the aforementioned fibers, and the non-reinforced resin used when the same resin as the thermoplastic resin constituting the LFRTP base material is used. Preferably, it is used. In addition, the amount used
It is preferred that the amount of fibers in the mixture be an amount that can maintain 15% by volume or more in the mixture.

In the present invention, in order to supply the LFRTP base material to the molding die, a heating and conveying step is required. In the heating step, by heating the thermoplastic resin to be used at a temperature equal to or higher than the softening point of the thermoplastic resin, the LFRTP base material is provided with flexibility to prevent breakage of the fiber during transportation and to easily fuse the LFRTP base materials together. Can be. In the transport process, LFR
By supplying the TP substrate to the mold without applying as much shearing as possible, breakage of the fiber is prevented.

The above-mentioned length of the LFRTP base material is the average length of ten selected LFRTP base materials. The average length of the fibers in the above-mentioned melt is obtained by burning the melt at 600 ° C., arbitrarily selecting 100 fibers, measuring the fiber length with a universal projector, and expressing the average thereof. It is.

The average length of the fibers in the melt is equal to the original LF
While maintaining 40% or more of the RTP substrate length, LFRTP
Examples of the method of transporting the substrate by heating include a screw extruder, a plunger extruder, and a transport method using a belt conveyor. The following method is particularly preferably used. (A) a cylinder having a diameter equal to or longer than the length of the LFRTP base material, the drawing rate of the extruding port at the tip is 1.0 to 100, preferably 1.0 to 20, and the diameter of the extruding port is LFRTP
This method uses a heating and conveying machine having a plunger extruder having a diameter greater than or equal to the length of the base material and having a shutter function at the extrusion port.If the drawing rate of the extrusion port exceeds 100, breakage of the fiber may occur. Increase.

(B) The heating and conveying machine has a cylinder diameter equal to or greater than the length of the LFRTP base material, and has an in-line screw type injection function having a shutter function at the extrusion port. Compression ratio of 1.1 to 1.8
And the drawing ratio of the extrusion port at the tip is 1.0 to 100, preferably 1.0 to 20, and the diameter of the extrusion port is LFR.
This is a method using a TP base material having a diameter equal to or greater than the length thereof and not having a backflow prevention ring. In this case, if the compression ratio is less than 1.1, the carrying capacity is inferior and exceeds 1.8. In such a case, the shearing force increases, and the fiber breakage increases. When the drawing ratio of the extrusion port exceeds 100, the fiber breakage is increased.

(C) The heating / transporting machine has a cylinder diameter equal to or greater than the length of the LFRTP base material, and has a screw pre-plastic injection function having a shutter function at the extrusion port. The compression ratio is 1.1 to 1.8, the squeezing rate at the tip of the extrusion port is 1.0 to 100, preferably 1.0 to 20, and the diameter of the extrusion port is LFRT.
This is a method using a material having a diameter equal to or greater than the length of the P base material. In this case, if the compression ratio is less than 1.1, the carrying capacity is poor, and if the compression ratio exceeds 1.8, the shearing force becomes large, Increase the breaking of When the drawing ratio of the extrusion port exceeds 100, the fiber breakage is increased. In addition, the squeezing rate of the extrusion port here means the cross-sectional area of the cylinder provided with the extrusion port /
It is expressed by the cross-sectional area of the extrusion port.
In the case of the transfer device, the cylinder cross-sectional area of the plunger section (measuring section) is indicated.

In the case of the method (a) using a plunger extruder for transporting the LFRTP substrate, the LFRTP is quantitatively
The substrate is put into a cylinder and slowly pressed while heating so as not to cut the LFRTP substrate. Further, in plasticizing, it is possible to efficiently plasticize by blowing hot air into the cylinder. Further, it is possible to quantitatively extrude the molten mass from the extruder.

When heating and transporting the LFRTP substrate, (b)
And (c) when used, the screw is preferably uniaxial or biaxial. The form of the screw is not particularly limited, but the pitch of the screw and / or the groove depth of the screw is preferably equal to or longer than the length of the LFRTP base material. The compression ratio here indicates the depth of the groove of the screw by hf, and the depth of the groove at the tip of the screw by hf
It is the value of hf / hm when represented by m.

In the present invention, in the case of the method (c) having a screw pre-plastic injection function in which the plasticizing by the screw and the metering extrusion by the plunger are used in combination,
The LFRTP substrate is conveyed by a screw while being heated, so that the resin of the LFRTP substrate is sufficiently melted and the LFRTP substrate is melted.
It becomes possible to fuse the TP base materials together, measure the molten mass collected by the plunger, and supply it to the mold.

In the present invention, if necessary, LFRTP
It is possible to use a belt conveyor to transport the substrate. In this case, it is preferable to use a belt conveyor provided with a heater and a hot air generator around it, and it is more preferable to use an inert gas atmosphere. As the material of the belt, it is preferable to use a fluorinated resin such as an ethylene tetrafluoride resin or a SUS mesh. It is also possible to use a belt conveyor and plunger extrusion together.

The melt of the LFRTP base material heated and conveyed as described above is measured by a heat conveyer, or weighed after passing through the heat conveyer, and then directly supplied to a molding die after weighing, or melted after weighing. The object is moved to a molding die by a robot or a human hand, for example. These supply methods can be appropriately selected in consideration of the fluidity of the thermoplastic resin used, the surface appearance, and the solidification time.However, in order to improve the molding fluidity, the melt is weighed with a heat transfer machine, A method in which the melt is directly supplied to a mold is preferred.

The melt supplied to the mold is press-molded to flow in the mold, contacted with the mold, and solidified to form a molded body. The temperature of the mold is not more than the melting point of the thermoplastic resin, and is appropriately selected in consideration of the fluidity, surface appearance, and solidification time of the thermoplastic resin used. Since the surface of the molded article obtained by the present invention is smooth and not subjected to much thermal deterioration of the resin, the surface appearance and mechanical strength are extremely good.

[0030]

Next, the present invention will be described more specifically with reference to examples and comparative examples. Example 1 Using a monofilament having an average diameter of 13 μm, a glass fiber strand 1 having 600 filaments (number of bundles) was used.
The book was treated with an acid-modified molten polypropylene having MI = 40 (2
60 ° C.), melt impregnated,
It was pulled out from a 3 mm die nozzle at a speed of 50 m / min, and was further cut to a length of 20 mm with a pelletizer to obtain an LFRTP base material. LFRTP obtained
The average diameter of the substrate is 0.53 mm, and the glass content is 45.5.
The volume% and the resin impregnation rate were 100% as an average value of n = 5. In the above, n represents the number of measurements.

The length of the LFRTP base material was averaged for 10 arbitrarily selected samples to obtain a measured value of 20 mm. First, the glass content was measured by using the obtained LFRTP substrate
After heating in an electric furnace at ℃ to burn off the resin, the weight of the remaining glass was measured to obtain a measured value of a glass content of 70% by weight. From these values, the specific gravity of the resin was 0.91, and the specific gravity of the glass fiber was 2.54, and the values were converted to% by volume.

Next, the obtained LFRTP base material was coated with an inner diameter of 9
The extruder was equipped with a shutter mechanism at the tip of the extruder at 0 mm, the inner diameter of the extruder was 90 mm, and the squeezing ratio of the extruder was 1.0. A molten mass was prepared by pressing the melt with a plunger, the shutter was opened, and the molten mass was taken out by further pressing the plunger. In addition, the measurement of the average length of the fiber in the melt, after burning the melt at 600 ° C., arbitrarily select 100 remaining glass fiber monofilaments,
The average value was measured to obtain a measured value of 19 mm. The average fiber length was 95% of the original LFRTP substrate length.

Next, as shown schematically in FIG. 1, the melt is placed between the upper die and the lower die in a length of 200 mm, a width of 200 mm,
The mold was transferred to a press mold capable of molding a box-shaped cavity having a height of 50 mm and a thickness of 3 mm. Pressing was performed for 1 minute at a pressure of 150 kg / cm ² using a hydraulic press. When the molten material was transferred to a molding die in this molded body, test pieces were cut out from a grounded portion (charged portion) in accordance with ASTM D256 and D790, and each n = 3
Then, the bending strength, the bending elastic modulus and the Charpy (flat wise) impact strength were measured. Table 1 shows the average value.

Example 2 An LFRTP substrate was obtained in the same manner as in Example 1 except that the diameter of the nozzle of the die was changed to 1.0 mm. LFRTP obtained
The average diameter of the substrate was 1.0 mm, the glass content was 19.3% by volume, and the resin impregnation rate was 98% as an average value of n = 5. From the obtained LFRTP base material, a molten mass was produced in the same manner as in Example 1. The average length of the fibers in the melt was measured by burning out the melt at 600 ° C, arbitrarily selecting 100 remaining glass fiber monofilaments, measuring the average value, and measuring the average value of 19 mm. I got The average fiber length was 95% of the original LFRTP substrate length. Thereafter, a molded body was obtained in the same manner as in Example 1, and ASTM D256 and D7
A test piece was cut out in a form conforming to No. 90, and the bending strength, flexural modulus and Charpy (flat wise) impact strength were measured at each n = 3. Table 1 shows the average value.

Example 3 The LFRTP base material obtained in Example 1 and a non-reinforced polypropylene resin (MI = 40) were dry-blended and mixed so that the overall glass content was 19.3% by volume. . This mixture was supplied to a screw pre-plasticizer equipped with a shutter mechanism at the tip of the extrusion port (plasticizer cylinder diameter: 9).
Plasticization was performed with a heating and transporting machine having an injection function of 0 mm, a compression ratio of 1.4, a plunger (measuring unit) cylinder diameter of 150 mm, and an extrusion port diameter of 100 mm) to produce a molten mass.

The average length of the fibers in the melt is measured as follows:
After the melt was burned off at 600 ° C., 100 remaining monofilaments of glass fiber were arbitrarily selected, and the average value was measured to obtain a measured value of 9 mm. The average fiber length was 45% of the original LFRTP substrate length. Thereafter, a molded body was obtained in the same manner as in Example 1, and a test piece was cut out in accordance with ASTM D256 and D790, and the bending strength, the bending elastic modulus, and the Charpy (flat wise) impact strength were measured at each n = 3. Was. Table 1 shows the average value.

Example 4 Using monofilaments having an average diameter of 13 μm, 16 glass fiber strands having 600 filaments (number of bundles) were bundled and introduced into an acid-modified molten polypropylene (260 ° C.) having MI = 40. After performing the melt impregnation,
The LFRTP base material was obtained by pulling out from a die nozzle having an inner diameter of 2.2 mm at a speed of 30 m / min and further cutting with a pelletizer so that the length became 20 mm. L obtained
The average diameter of the FRTP substrate is 2.2 mm and the glass content is 4
5.5% by volume, resin impregnation rate is 98% as an average of n = 5
Met. In the above, n represents the number of measurements. The obtained LFRTP base material and a non-reinforced polypropylene resin (MI = 40) are dry-blended, and the glass content is 1
It mixed so that it might be set to 9.3 volume%.

The mixture was inline screw type (cylinder diameter 90 mm, compression ratio 1.4, extrusion port diameter 90 mm) equipped with a shutter mechanism at the tip and without a backflow prevention ring.
Was plasticized by a heating and conveying machine having an injection function to produce a molten mass. In addition, the measurement of the average length of the fiber in the melt,
After the melt was burned off at 600 ° C., 100 remaining glass fiber monofilaments were arbitrarily selected, and the average value was measured to obtain a measured value of 8.2 mm. The average fiber length was 41% of the original LFRTP substrate length. Example 1 below
A molded product was obtained in the same manner as described above, and ASTM D256 and D79
A test piece was cut out in a form conforming to 0, and each of n = 3, bending strength, bending elastic modulus and Charpy (flat wise)
The impact strength was measured. Table 1 shows the average value.

Comparative Example 1 Using monofilaments having an average diameter of 13 μm, 30 glass fiber strands having a number of filaments (bundling) of 600 were bundled and introduced into an acid-modified molten polypropylene (260 ° C.) having MI = 40. After performing the melt impregnation,
The LFRTP base material was obtained by pulling out from a die nozzle having an inner diameter of 3.0 mm at a speed of 15 m / min and further cutting it with a pelletizer so that the length became 20 mm. L obtained
The average diameter of the FRTP substrate is 3.0 mm and the glass content is 4
5.5% by volume, resin impregnation rate is 94% as an average of n = 5
Met. In the above, n represents the number of measurements.

Next, the obtained LFRTP base material was put into a cylinder having an inner diameter of 90 mm and equipped with a shutter mechanism at the tip of the extrusion port and heated to 230 ° C. to perform plasticization.
A molten mass was prepared by pressing the melt with a plunger, the shutter was opened, and the molten mass was taken out by further pressing the plunger.

Incidentally, the measurement of the average length of the fiber in the melt is as follows.
After the melt was burned off at 600 ° C., 100 remaining monofilaments of glass fiber were arbitrarily selected, and the average value was measured to obtain a measured value of 19 mm. The average fiber length was 95% of the original LFRTP substrate length. Thereafter, a molded product was obtained in the same manner as in Example 1, and ASTM D256 and D790 were obtained.
A test piece was cut out in a form conforming to the above, and the bending strength, the bending elastic modulus, and the Charpy (flat wise) impact strength were measured at each n = 3. Table 1 shows the average value.

Comparative Example 2 The LFRTP base material obtained in Comparative Example 1 and a non-reinforced polypropylene resin (MI = 40) were dry-blended and mixed so that the glass content was 19.3% by volume.

This mixture was plasticized by a heating and conveying machine having an in-line screw type injection function similar to that of Example 4 to produce a molten mass. The average length of the fibers in the melt was measured by burning out the melt at 600 ° C., arbitrarily selecting 100 remaining monofilaments of glass fibers, measuring the average value, and measuring the average length of 7.0 mm. Measurements were obtained. The average fiber length was 35% of the original LFRTP substrate length. Thereafter, a molded product was obtained in the same manner as in Example 1, and ASTM D
Test pieces were cut out in accordance with 256 and D790, and the bending strength, flexural modulus and Charpy (flat wise) impact strength were measured at each n = 3. Table 1 shows the average value.

Comparative Example 3 The LFRTP base material obtained in Comparative Example 1 and a non-reinforced polypropylene resin (MI = 40) were dry-blended and mixed so that the glass content was 19.3% by volume. This mixture was plasticized by a heating and transporting machine having the same screw prepura injection function as in Example 3 to produce a molten mass. The average length of the fibers in the melt was measured by burning out the melt at 600 ° C., arbitrarily selecting 100 remaining glass fiber monofilaments, measuring the average value, and measuring the average value of 6.8 mm. Measurements were obtained. The average length of the fiber is the original L
It was 34% of the FRTP substrate length. Hereinafter, a molded article was obtained in the same manner as in Example 1, and a test piece was cut out in a form in accordance with ASTM D256 and D790.
Flexural modulus and Charpy (flat wise) impact strength were measured. Table 1 shows the average value.

Comparative Example 4 The LFRTP base material obtained in Comparative Example 1 and a non-reinforced polypropylene resin (MI = 40) were dry-blended and mixed so that the glass content was 19.3% by volume. This mixture was in-line type equipped with a backflow prevention ring (cylinder diameter 90 mm, compression ratio 2.4, extrusion port diameter 5.0 mm).
Plasticization using a heated transfer machine with an injection function of
A molten mass was made. The average length of the fibers in the melt was measured at 2.8 mm by burning the melt at 600 ° C., arbitrarily selecting 100 remaining glass fiber monofilaments, and measuring the average value. Value. The average fiber length was 14% of the original LFRTP substrate length. Thereafter, a molded product was obtained in the same manner as in Example 1, and ASTM D256 and D
Specimens were cut out in a form conforming to 790 and each n = 3.
Flexural strength, flexural modulus and Charpy (flat wise) impact strength were measured. Table 1 shows the average value.

Comparative Example 5 The same LFRTP base material as in Example 1 was uniformly dispersed and pressed once with a flat plate press at a pressure of 5 kg / cm ² to form a 3.8 mm thick sheet. 176
mm, a preform in the form of a sheet cut out to a width of 176 mm was prepared, the sheet was heated sufficiently, and two sheets were transferred to the same press molding die used in the examples, and transferred at 150 kg / c.
It was pressed at a pressure of m ² for 1 minute to obtain an LFRTP molded body. A test piece was cut out in accordance with ASTM D256 and D790, and the bending strength, the flexural modulus and the Charpy (flat wise) impact strength were measured for each n = 3. Table 1 shows the average value. In this method, the production efficiency is inferior due to the sheeting step as described above.

[0047]

[0048]

[0049]

According to the present invention, by heating and transporting the LFRTP base material without applying much shearing, it is possible to hold the fibers in the molded body for a long time, and the mechanical strength of the molded body, especially the impact It is possible to improve the strength and to reduce the monofilament of the fiber to improve the fluidity of the melt during molding. Furthermore, in the present invention, since molding is performed without forming a sheet accompanied by a heating step, thermal degradation of the resin is suppressed, and the complicated work of the prior art of moving the softened molten sheet to a plurality of molds is unnecessary. Is what you do.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating a method of the present invention.

Claims (6)

[Claims] 1. A melt is prepared by melting a long fiber reinforced thermoplastic resin (LFRTP) base material alone or by diluting the base material with a non-reinforced resin to form a melt. The melt is supplied to a molding die and pressed. In the method for producing an LFRTP molded article to be molded, the LF
One or more continuous reinforcing fiber strands are impregnated with a thermoplastic resin and pulled out from a nozzle, and the RTP substrate is cut into an average length or thickness of 10 to 50 mm.
An LFRTP base material having a reinforcing fiber content of 15 to 80% by volume and having a reinforcing fiber content of 15 to 80% by volume.
%. A method for producing an LFRTP molded article, comprising producing and molding a molten material having a length of at least 1%. 2. The thermoplastic resin impregnation rate of the LFRTP base material is as follows:
The method for producing an LFRTP molded article according to claim 1, which is 95% or more. 3. The method according to claim 1, wherein the LFRTP substrate has an average diameter or an average thickness of 0.05 to 1.5 mm. 4. A heating and conveying machine has a cylinder having a diameter equal to or greater than the length of an LFRTP base material, and a drawing rate of an extruding port at a tip is 1.
The plunger extruder which is 0 to 100, has a diameter of the extrusion port equal to or longer than the length of the LFRTP base material, and is provided with a shutter mechanism at the tip of the extrusion port. The method for producing an LFRTP molded article of the above. 5. A heating and conveying machine having a cylinder diameter equal to or greater than the length of an LFRTP base material and having an inline screw type injection function having a shutter mechanism at the end of an extrusion port, wherein a screw of a plasticizing section is provided. Compression ratio of 1.1 to 1.8
Wherein the squeezing rate of the extruding port at the tip is 1.0 to 100, and the diameter of the extruding port is equal to or larger than the length of the LFRTP base material, and is not provided with a backflow prevention ring. The method for producing an LFRTP molded article according to any one of 1 to 3 above. 6. A heating and conveying machine having a cylinder diameter equal to or greater than the length of the LFRTP base material and having a screw pre-plastic injection function provided with a shutter mechanism at the end of an extrusion port, wherein a screw of a plasticizing section is provided. Compression ratio of 1.1 to 1.8, the drawing rate of the extrusion port at the tip is 1.0 to 100,
The LF according to any one of claims 1 to 3, wherein the diameter of the extrusion port is equal to or greater than the length of the LFRTP base material.
A method for producing an RTP molded body.