JP2023048312A - Fiber-reinforced resin molded article and producing method thereof - Google Patents

Abstract

To provide a fiber-reinforced resin molded article which achieves both mechanical properties and weight reduction by laminating and integrating reinforcing fibers on a surface of a substrate even in the case of a three-dimensional molded article having varied geometry, and a manufacturing method of stably and efficiently manufacturing the fiber-reinforced resin molded article.SOLUTION: A three-dimensional fiber-reinforced resin molded article 100 in which a chopped prepreg sheet material 2, in which a matrix resin 23 made of a thermoplastic resin is impregnated with reinforcing fibers 22, and a substrate 1 made of thermoplastic resin are integrally molded in layers, is configured that the thermoplastic resin of the substrate 1 is melted and solidified so as to be integrally molded in layers with the chopped prepreg sheet material 2.SELECTED DRAWING: Figure 1

Description

The present invention achieves both strength and weight reduction by laminating and integrating reinforcing fibers and a base material in a molded body having a shape with a large shape change such as tall ribs and deep depressions manufactured by injection molding of resin. The present invention relates to a fiber-reinforced resin molded article and a method for producing the same.

The resin injection molding technology is widely used because it is highly mass-producible because it can produce a molded product of a certain quality in a short time even if it has a complicated shape. In addition, as the development of thermoplastic resins has progressed, the number of resins that have strength comparable to that of metals while taking advantage of the characteristics of lightweight resins is increasing.
However, since these special engineering plastics are expensive, they are not widely used, and the resins mainly used for injection molding are still general engineering plastics.

Therefore, with the aim of improving the mechanical strength, especially the tensile strength, of ordinary resins, the technique of injection molding by mixing reinforcing fibers such as glass fibers and carbon fibers as fillers into resins is spreading. are doing. The fiber-reinforced resin molded in this way can improve the strength of the entire molded body by taking advantage of the light weight characteristic of the base resin and the high tensile strength of the mixed short fiber reinforcing fibers. can.

However, the reinforcing fibers mixed with the thermoplastic resin must have a very short fiber length in order to ensure the fluidity of the resin into the mold and to avoid molding defects. There are several problems with such a resin in which short fibers are mixed. For example, the mechanical strength is lowered at the portions where the fibers are discontinuous. In addition, the reinforcing fibers are oriented along the direction of flow as the resin flows along a certain path in the mold. In this case, the mechanical strength is different between the direction in which the reinforcing fibers face and the direction orthogonal thereto, and it is originally difficult to evenly distribute the reinforcing fibers throughout the molded article. Therefore, the mechanical strength of the fiber-reinforced resin mixed with short fibers as a filler is anisotropic.

In this respect, conventionally, a technique has been developed to reinforce a molded product by attaching a fiber reinforced sheet in which long reinforcing fibers are arranged vertically and horizontally to a base material made of a thermoplastic resin. A three-dimensional molded body can be adopted as well as a planar molded body to be attached. In particular, as a technique for easily molding even a complicated shape, a technique for integrally molding a fiber-reinforced sheet and a thermoplastic resin as a base material during injection molding has been disclosed.

For example, in Patent Document 1, there is a plastic frame technology characterized by forming an FRP reinforcing layer made of a reinforcing fiber sheet along the length direction on the outer peripheral surface of a rod-shaped plastic frame that serves as a frame base material for a structure. disclosed.

To summarize the technique of Patent Document 1, the plastic frame is composed of a resin layer made of a thermoplastic resin such as PE or PP, and an FRP reinforcing layer made by impregnating a reinforcing fiber sheet with a resin. The overall shape is a rod-like shape with a V-shaped cross section, and a curved surface is formed on the outer peripheral surface with the top as a curved point.
For the reinforcing fiber sheet, for example, a plain-woven carbon fiber sheet or a laminated sheet obtained by stacking a plurality of UD sheets in which reinforcing fibers are arranged in one direction and integrated in different directions is used. This reinforcing fiber sheet is impregnated with the same thermoplastic resin as the material of the resin layer as a matrix resin to form an FRP reinforcing layer.
The FRP reinforcing layer is formed along the longitudinal direction of the curved surface formed on the entire outer peripheral surface of the plastic frame.

It is said that such a configuration makes it possible to reduce the weight of the substrate without impairing the mechanical strength.
In addition, since the base material can be molded simply by injecting the thermoplastic resin into the mold after inserting the reinforcing fiber sheet into the mold, complicated manufacturing processes such as cutting are not required. It is said that molding can be easily performed even if the base material is small and has a complicated shape.

Japanese Patent Application Laid-Open No. 2021-45865

However, the reinforcing fiber sheet used in the technique of Patent Document 1 is obtained by plain-weaving long-fiber reinforcing fibers or alternately laminating UD sheets. A reinforcing fiber sheet having fiber directions perpendicular to each other has high flexural rigidity in the perpendicular direction. Therefore, even if the thermoplastic resin is injected at high temperature and high speed (or high pressure) in injection molding, the rigidity of the reinforcing fiber will reduce the shape of the mold for shapes that change greatly, such as deep dents and high ribs. difficult to follow.

Generally, in order to improve moldability, the molding conditions are tightened by further increasing the resin temperature or increasing the injection speed during injection molding. As a result, the reinforcing fibers are easily deformed. However, sharply deformed corners and the like may cause molding defects such as wrinkling and peeling of reinforcing fibers after cooling.

Therefore, it has been difficult to obtain a molded body having a shape with a large change in shape, in which a reinforcing fiber resin sheet is attached to the entire surface of the base material without causing molding defects, and it has been possible to manufacture it. However, the yield was poor and there was a problem in profitability.

The present invention has been made in view of the above-mentioned problems, and the object of the present invention is to provide a three-dimensional molded article having a shape with a large change in shape, by adding reinforcing fibers to the surface of the base material. It is an object of the present invention to provide a fiber-reinforced resin molded article which is laminated and integrated into two layers to achieve both mechanical properties and weight reduction, and to provide a manufacturing method for stably and efficiently manufacturing the fiber-reinforced resin molded article.

Means adopted by the inventors to solve the above problems will be described below.
The fiber-reinforced resin molded article (hereinafter simply referred to as "molded article") of the present invention comprises a fiber-reinforced resin sheet in which reinforcing fibers are impregnated with a matrix resin made of a thermoplastic resin, and a base material made of a thermoplastic resin. It is a three-dimensional molded body integrally formed by lamination.

Here, various thermoplastic resins can be used for the matrix resin in the thermoplastic resin and the thermoplastic resin in the base material. It is possible. Further, the reinforcing fibers referred to here are not limited to those that enhance mechanical strength, and include fibers that have properties capable of imparting some physical properties to the molded article. Furthermore, the term "three-dimensional" as used herein does not mean that the molded article is flat, but it is sufficient that even a portion of the entire molded article has a three-dimensional shape.
In addition, the impregnation of the reinforcing fibers with the matrix resin includes complete impregnation in which the reinforcing fibers are completely impregnated with the matrix resin, as well as those including an unimpregnated portion, which will be described later.

Such a fiber reinforced resin sheet is configured to be laminated integrally with the fiber reinforced resin sheet by melting and solidifying the thermoplastic resin of the base material.
Here, the fiber-reinforced resin sheet and the base material are laminated and integrated by injection molding. The integration is not limited to the case where the matrix resin of the fiber reinforced resin sheet melts and solidifies together when the thermoplastic resin of the base material melts, and is not limited to the case where the fiber reinforced resin sheet and the base material are integrated. A separate adhesive layer or resin sheet material is provided on the base material, which melts and solidifies together with the thermoplastic resin of the base material.

Among the means adopted by the present invention to solve the above-mentioned problems, the means based on the basic configuration are as described above, but the following means can also be used in the present invention.

The fiber-reinforced resin sheet may include a portion not impregnated with the reinforcing fibers and the matrix resin.
The non-impregnated portion refers to a state in which the thermoplastic resin is not impregnated into the reinforcing fibers, and there are some bundled portions in the fiber-reinforced resin sheet itself to the extent that the reinforcing fibers are impregnated with the thermoplastic resin. It also includes a state in which there is a part of the resin portion that has not penetrated between the reinforcing fibers.

When the reinforcing fibers and the matrix resin are completely mixed and impregnated, the rigidity of the fiber-reinforced resin sheet is increased. In addition, in the impregnated state, the thermoplastic resin enters between the reinforcing fibers, so the area occupied by the resin between the reinforcing fibers is reduced.
On the other hand, by configuring the fiber reinforced resin sheet so that there is an unimpregnated portion, in the bundled portion where the thermoplastic resin does not permeate, the reinforcing fibers are not integrated with the resin, so the fiber reinforced resin sheet is easily deformed to follow the shape of the mold more easily. In addition, the fiber-reinforced resin sheet has flexibility due to the presence of only the thermoplastic resin portion without reinforcing fibers, and the strength that does not easily tear in the fiber direction due to the increase in the portion occupied by the resin. be prepared.

Also, a resin layer made of a thermoplastic resin may be laminated on at least one of the surfaces of the fiber-reinforced resin sheet.
The resin layer is not limited to being the same resin as either the matrix resin of the fiber-reinforced resin sheet or the thermoplastic resin of the base material, and may be a resin different from either.
In addition, the resin layer may be laminated on only one side of the fiber-reinforced resin sheet, or may be laminated on both sides.

By laminating another resin layer on the surface of the fiber-reinforced resin sheet, a sufficient resin layer is formed on the surface of the fiber-reinforced resin sheet, so that the reinforcing fibers are prevented from fluffing and being exposed from the surface of the molded article. be able to. In addition, when it is laminated on the joint surface with the base material, it is sufficiently melted with the base material in the injection molding, and the strength between the layers is improved.

Further, the fiber-reinforced resin sheet may employ a UD sheet material in which reinforcing fibers are aligned in a single direction. Alternatively, a chopped prepreg sheet material may be obtained by laminating a plurality of chopped prepregs obtained by cutting the UD sheet material into strips so that the direction of the reinforcing fibers is quasi-isotropic.
Here, quasi-isotropy refers to the property of having no directionality in physical properties by orienting reinforcing fibers that are unidirectionally oriented by themselves in all directions in a plane direction.

When the shape of the molded article is mainly a three-dimensional shape in one direction, it is sufficient if the fiber-reinforced resin sheet is easily deformed only in that direction. Therefore, when the UD sheet material is used as a fiber-reinforced resin sheet, by arranging the fibers in parallel in the direction of deformation, even if the force from the injected resin is slight, it can be easily deformed into a mold shape. can be followed.

On the other hand, when a quasi-isotropic chopped prepreg sheet material is used, the reinforcing fibers of the strip-shaped chopped prepreg are oriented in all directions and laminated, so that the strength of the molded body is uniform in the direction. That is, it exhibits uniform strength against forces such as bending, torsion and tension in all directions.
In addition, since the chopped prepreg is cut into strips and laminated in a pseudo-isotropic manner, the fiber is longer than the filler mixed in the resin, so it has excellent strength. The discontinuous portion easily deforms as a fiber-reinforced resin sheet. Therefore, it is easy to follow the shape of the mold while ensuring sufficient strength, and even if the molded body has a complicated shape, the fiber-reinforced resin sheet can be evenly arranged over the entire surface.

Here, when a chopped prepreg sheet material composed of a thermoplastic resin film and a thin layer of reinforcing fibers is used as the fiber-reinforced resin sheet, the volume content Vf of the reinforcing fibers is set to 20% or more and 80% or less. It is also possible to set the thickness of the chopped prepreg sheet material to 40 μm or more and 3000 μm or less.

As described above, since the fiber-reinforced resin sheet includes non-impregnated portions, it has a strength that does not easily tear in the fiber direction. Therefore, in general fiber-spreading means, many bundles of reinforcing fibers are laminated and become thick. The layers are laminated so as to be quasi-isotropic. At this time, the volume content Vf of the reinforcing fibers is set to 20% or more and 80% or less. As a result, a very thin chopped prepreg sheet material having sufficient strength can be obtained. As a result, it becomes possible to more easily follow the mold shape by injecting the resin in the injection molding.

The molded article as described above can be produced by injection molding as described above, and as a specific means thereof, the following means can also be adopted.
As one of the means, first, the mold is closed in a state where a fiber-reinforced resin sheet composed of the reinforcing fiber and the matrix resin including the non-impregnated portion is stretched in a plane in advance, and then the sheet becomes the base material. Means for injecting a thermoplastic resin into the mold and shaping the fiber-reinforced resin sheet to integrally laminate it with the base material can be employed.

The fiber-reinforced resin sheet is pre-stretched flat and sandwiched between molds, softened by the heat during injection and deformed by the force of the resin, so only the mold for injection molding is required. Cost can be reduced and the manufacturing process can be simplified. Here, as described above, when using a fiber-reinforced resin sheet containing a flexible non-impregnated portion, the fiber-reinforced resin sheet that is planar before molding is subjected to heat, injection speed, and pressure during injection of thermoplastic technology. It can be easily formed by following the shape of the mold with the force from the mold. When the fiber-reinforced resin sheet is flattened in advance, the fiber-reinforced resin sheet may be clamped to close the mold.

As another method for producing a molded article, first, a fiber-reinforced resin sheet composed of the reinforcing fiber and the matrix resin is three-dimensionally molded in advance to form an insert member, and then the mold for injection molding is filled with the above-described insert member. It is possible to adopt means for inserting an insert member and then molding the fiber-reinforced resin sheet and the base material into a laminated body by injecting a thermoplastic resin serving as the base material.

By molding the fiber-reinforced resin sheet three-dimensionally in advance, it is possible to further improve the accuracy of reproducibility of the shape after injection molding. In addition, in the three-dimensionalization performed on the fiber reinforced resin sheet, it is not limited to the case where the whole is molded so as to have the same shape as the final product, but only a part of the shape that has a large shape change is molded. It includes the case and the case of preliminarily molding to a halfway shape.

In the present invention, a fiber-reinforced resin sheet made of reinforcing fibers and a thermoplastic resin is three-dimensionally laminated together with a base material. It is possible to obtain a molded body having both.
Here, since the fiber-reinforced resin sheet is melted and solidified in lamination and integration with the base material, it can be flexibly deformed and a three-dimensional molded article can be obtained.
As a result, even in the case of a three-dimensional molded article having a shape with a large change in shape, it is possible to obtain a fiber-reinforced resin molded article that achieves both mechanical properties and weight reduction by laminating and integrating reinforcing fibers on the surface of the base material. It has the effect of being able to
In particular, when the fiber-reinforced resin sheet includes a portion not impregnated with the reinforcing fibers and the matrix resin, it can be deformed more flexibly to form a three-dimensional molded article.

In addition to the above, in the production of the molded product, the fiber-reinforced resin sheet is stretched flat in advance, the mold is closed, and the thermoplastic resin is injected to integrally mold it with the base material. The fiber-reinforced resin sheet can be continuously molded by feeding the sheet each time it is molded.
On the other hand, by inserting a three-dimensionally molded fiber-reinforced resin sheet in advance into the mold and molding it integrally with the base material by injecting thermoplastic resin, molding with high shape reproducibility can be a body.
As a result, there is an effect that a fiber-reinforced resin molded article can be produced stably and efficiently.

1 is a perspective view and a partial cross-sectional view showing a fiber-reinforced resin molded article of the present invention; FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is the top view which shows the chopped prepreg sheet material of this invention, and explanatory drawing which shows a laminated state. BRIEF DESCRIPTION OF THE DRAWINGS It is the top view showing the chopped prepreg of this invention, and explanatory drawing showing a laminated state. FIG. 2 is an explanatory diagram showing the apparatus for manufacturing a molded article of the present invention; It is explanatory drawing showing the manufacturing method of the molded object of this invention. FIG. 3 is a perspective view showing a fiber-reinforced resin molded article of Modification 1 of the present invention. FIG. 3 is a plan view showing a UD sheet material of Modification 1 of the present invention and an explanatory diagram showing a lamination state. FIG. 10 is an explanatory view showing a manufacturing method of Modification 1 of the present invention; FIG. 10 is a plan view showing a chopped prepreg of Modification 2 of the present invention and an explanatory view showing a lamination state.

A mode for carrying out the present invention will be described below based on FIGS. 1 to 5. FIG.
In addition, the laminated state in each drawing is schematically shown for explanation.

The fiber-reinforced resin molded body 100 (hereinafter also referred to as "molded body") of the present invention is a cover body that encloses equipment and parts, and has a three-dimensional shape with a predetermined thickness as shown in FIG. ing. In particular, the molded body 100 is thin but has a shape with a large change in shape, such as a deep depression and small rounded corners.
A molded body 100 is formed by laminating and integrating a chopped prepreg sheet material 2 (hereinafter simply referred to as "chopped sheet material"), which is a fiber-reinforced resin sheet, over the entire surface of a base material 1 made of polyamide.

As shown in FIG. 2, the chopped sheet material 2 used in the molded body 100 is composed of a plurality of chopped prepregs 21, 21... (hereinafter simply referred to as "chopped material") cut into strips with a uniform thickness. It is configured by laminating a plurality of layers so as to become. At this time, the fiber direction of the chopped material 21 is randomly oriented in the two-dimensional direction, thereby providing pseudo-isotropy.

The chopped sheet material 2 is laminated so that the thickness of the chopped sheet material 2 is 40 μm or more and 3000 μm or less. By setting the thickness within this range, the molded article 100 can be flexibly deformed during molding, and sufficient strength can be ensured.

Also, the volume content Vf of the reinforcing fibers 22 in the chop sheet material 2 is adjusted to be 20% or more and 80% or less. The lower limit of the volume content Vf is preferably 35% or more, more preferably 40% or more. On the other hand, the upper limit of the volume content Vf is preferably 60% or less, more preferably 55% or less.
If the volume content Vf is less than 20%, the reinforcing fibers 22 cannot be expected to significantly improve the strength, and if it exceeds 80%, the ratio of the matrix resin 23 is relatively decreased and the flexibility is lowered.

The chop material 21 is obtained by cutting a fiber-reinforced resin sheet material in which reinforcing fibers 22 made of carbon fibers are impregnated with a matrix resin 23 made of a polyamide resin similar to that of the base material 1 and cut into strips as shown in FIG. Obtainable.

In the embodiment of FIG. 3, polyamide is used for the base material 1, but the resin used for the base material 1 may be other thermoplastic resins such as polycarbonate, polyethersulfone, polyphenylene ether, and polyphenylene. Sulfide, polyether ether ketone, polyether ketone, polyimide, polytetrafluoroethylene, polyether, polyolefin, liquid crystal polymer, polyarylate, polysulfone, polyacrylonitrile styrene, polystyrene, polyacrylonitrile, polymethyl methacrylate, ABS, AES, ASA , polyvinyl chloride, polyvinyl formal resin, block polymer, and the like. In addition, a reinforcing material or a fiber-containing resin can be used as a filling or reinforcing material. These thermoplastic resins can be used singly or in combination of two or more.

As the reinforcing fibers 22, in addition to carbon fibers, various inorganic or organic fibers such as aramid fibers, nylon fibers, high-strength polyester fibers, glass fibers, boron fibers, alumina fibers, silicon nitride fibers, and basalt fibers are used. be able to.

In the method of manufacturing the chopped material 21, first, a thermoplastic resin film made of polyamide, which serves as the matrix resin 23, is placed between the bundles of the reinforcing fibers 22 opened into thin layers, and heated and sandwiched between the bundles by rollers.
As an example of the thin-layer spreading method, the fibers can be spread using a special spreading device (not shown). In this fiber-spreading device, a fluid is passed through the conveyed fiber bundle so that the fibers are bent and moved in the width direction to spread the fibers. Further, when opening the fibers, there is a step of bringing the contact member into contact with the conveyed fiber bundle. At the time of contact, after the fiber bundle is rotated in a direction inclined to the conveying direction to push a part of the fiber bundle into a tensioned state, the contact member is separated from the fiber bundle in the tensioned state to temporarily relax the fiber bundle. do.
By allowing fluid to pass through the fiber bundle when it is in a relaxed state, it is possible to spread the fibers into a thin layer. In addition, in the generation of tension and relaxation, damage to the fiber bundle can be reduced by rotating the contact member in a direction that is inclined with respect to the conveying direction.

More specifically, the thin layer opening reduces the number of reinforcing fibers 22 arranged in the thickness direction to an average of 10 or less. For example, when a 12K carbon fiber bundle is spread to a width of 20 mm, about 2,000 to 2,500 are arranged in the width direction, about 4 to 6 are arranged in the thickness direction, and when spread to a width of 40 mm, about About 5,000 to 5,500 lines are lined up, and it is thought that about 2 to 3 lines are lined up in the thickness direction. Furthermore, when the 50K carbon fiber bundle is spread to a width of 42mm, it is considered that about 8 to 10 fibers are lined up in the thickness direction.

The lower limit of the thickness of the thermoplastic resin film that serves as the matrix resin 23 is not particularly limited, but the thickness is preferably 5 μm or more so that the shape of the film can be easily maintained during film molding. Also, the upper limit of the thickness of the thermoplastic resin film is preferably 50 μm or less, more preferably 45 μm or less, still more preferably 40 μm or less, and even more preferably 30 μm or less.
By setting the thickness of the thermoplastic resin film to 50 μm or less, the chopped material 21 in which the plurality of reinforcing fibers 22 opened in the thermoplastic resin film are laminated can be made thinner.

Here, in manufacturing the sheet material to be the chopped material 21, unimpregnated portions 24 and 24' in which the matrix resin 23 is not impregnated are formed in part of the reinforcing fiber 22. As shown in FIG. In the example of FIG. 3, in the non-impregnated portion 24, the reinforcing fiber 22 does not exist and the portion of only the matrix resin 23 exists in the substantially central region of the thickness. In addition, as other non-impregnated portions 24', portions where the matrix resin 23 does not exist and only the reinforcing fibers 22 exist exist in the front and back regions. Note that the reinforcing fibers 22 are impregnated with the matrix resin 23 between the non-impregnated portion 24 and the other non-impregnated portion 24'.

By providing the non-impregnated portions 24 and 24', the chop sheet material 2 has flexibility due to the presence of only the matrix resin 23 without the reinforcing fiber 22, and has the strength not to easily tear in the fiber direction. be able to. In addition, by making the chopped material 21 thicker than the impregnated state in which the reinforcing fibers 22 and the matrix resin 23 are completely mixed and having a thickness of not more than twice that, the randomly laminated chopped sheet material 2 The thickness can be made very thin, and even if it is made thin, problems such as the chop material 21 tearing are less likely to occur.

In the production of the chopped material 21 having such a non-impregnated portion, the sheet material before cutting is heated in a state in which the reinforcing fibers 22 spread into a thin layer and the thermoplastic resin film serving as the matrix resin 23 are arranged, and then heated by a roller. Manufactured by sandwiching between
First, both side ends of the reinforcing fibers 22 opened into a thin layer are placed outside the both side ends of the thermoplastic resin film and overlapped. By arranging both side ends of the reinforcing fibers 22 outside the both side ends of the thermoplastic resin film, it is possible to prevent the resin from adhering to the conveying belt, thereby preventing the reinforcing fibers 22 from winding around the conveying belt. is avoided, and the sheet material can be continuously obtained in a stable impregnated state.
Then, in this state, the film is passed through the plurality of heating rolls and the plurality of cooling rolls while being tensioned. At this time, the temperature and pressure are adjusted so that the sheet material has a non-impregnated portion and has a thickness of 20 μm or more and 70 μm or less.

The lower limit of the thickness of the sheet material is preferably 25 μm or more, more preferably 30 μm or more, even more preferably 35 μm or more, and even more preferably 40 μm or more. Also, the upper limit of the thickness of the sheet material is preferably 65 μm or less, more preferably 60 μm or less, and even more preferably 55 μm or less. Specifically, by making the thickness of the sheet material to be the chopped material 21 as thin as possible within the above range, the polyamide resin and the reinforcing fibers 22 are mostly fused and laminated, so that the reinforcing fibers 22 It becomes possible to fully demonstrate the strength of In addition, when stress is applied, the chopped sheet material 2 made of the chopped material 21 is less likely to undergo delamination, and is excellent in fatigue characteristics. Furthermore, the moldability when using the chopped material 21 is more excellent.

The sheet material manufactured in this way is cut into strips of a predetermined size to obtain the chopped material 21 . The dimensions of the chopped material 21 can be appropriately determined in consideration of the shapeability of the chopped sheet material 2 and the fiber-reinforced resin molded body 100 manufactured using the chopped material 21 . Specifically, it is preferably formed in a rectangular shape with a short side length of 2 mm or more and 50 mm or less and a long side length of 2 mm or more and 80 mm or less. The lower limit of the length of the short side is preferably 2 mm or longer, more preferably 3 mm or longer, still more preferably 4 mm or longer, and even more preferably 4.5 mm or longer. Also, the upper limit of the length of the short side is preferably 50 mm or less, more preferably 40 mm or less, still more preferably 30 mm or less, still more preferably 20 mm or less, 15 mm or less, or 10 mm or less. On the other hand, the lower limit of the length of the long side is preferably 2 mm or longer, more preferably 4 mm or longer, still more preferably 6 mm or longer, and still more preferably 8 mm or longer or 10 mm or longer. Also, the upper limit of the length of the long side is preferably 80 mm or less, more preferably 70 mm or less, even more preferably 60 mm or less, and even more preferably 50 mm or less or 45 mm or less.

By reducing the length of the short side and the long side of the chopped material 21, it is possible to increase the density of the chopped material 21 in the chopped sheet material 2 and the fiber reinforced resin molding 100 manufactured using it. can. Therefore, the strength of the chop sheet material 2 and the fiber-reinforced resin molded body 100 can be increased more effectively. On the other hand, when manufacturing the chopped sheet material 2 and the fiber-reinforced resin molded body 100 with large dimensions, the length of the short side and the long side is increased to the extent that the strength of the chopped material 21 is not extremely impaired. The sheet material 2 and the fiber-reinforced resin molding 100 can be efficiently manufactured in a short time.

The molded body 100 obtained by laminating and integrating the chop sheet material 2 and the base material 1 as described above can be manufactured using a manufacturing apparatus 4 as shown in FIG.
FIG. 4 is a diagram schematically showing an injection molding machine 3 to which a feeder 4 is attached for so-called in-mold molding.

Fixed side molds 31 and 31' and a movable side mold 32 are attached to the injection molding machine 3. Polyamide resin pellets, which will be the base material 1, are put into a hopper 33 and heated and melted. Inject into the mold from 35. The injected resin stays in the space formed by closing the fixed side molds 31 and 31' and the movable side mold 32, and is cooled and taken out from the molds to obtain a molded product that conforms to the shape of the molds. be able to. The fixed side molds 31 and 31' are composed of two plates for removing the molded runners from the molds.

Here, in a state before injection, the chop sheet material 2 is arranged between the fixed side molds 31 and 31' and the movable side mold 32 so as to be stretched two-dimensionally. The chop sheet material 2 is configured so that it can be sequentially fed out by a feeder 4 from a state wound around upper and lower rolls.
The chop sheet material 2 is attached to the feeder 4 in a state in which a continuous release sheet material 41 is provided on one side.

The method of manufacturing the molded body 100 will be described with reference to FIG. 5. First, as shown in FIG. Between the molds 31 and 31' and the movable mold 32, the chop sheet material 2 provided with the release sheet material 41 is arranged in a planarly stretched state.

Next, the movable mold 32 is moved and the molds are closed so that the chop sheet material 2 is sandwiched between the fixed molds 31 and 31'. At this time, the air inside the mold is sucked by a vacuum pump (not shown) from the intake ports 36 provided in the movable mold 32 . As a result, as shown in FIG. 5(b), the chop sheet material 2 is deformed so as to stick to the movable mold 32. As shown in FIG.

Then, the polyamide resin to be the base material 1 is injected while the chop sheet material 2 is being sucked. Since the polyamide resin at this time is injected at high temperature and high speed, the matrix resin 23 forming the chop sheet material 2 receives a force that presses it against the movable mold 32 while softening. As a result, as shown in FIG. 5(c), the chop sheet material 2 is deformed following the shape of the movable side mold 32, and the matrix resin 23 and the polyamide resin forming the base material 1 are melted and integrated. .

In this state, P/V switching is performed, holding pressure is applied, and after cooling for a predetermined time, as shown in FIG. The body 100 is removed from the mold. The molded body 100 can be manufactured by the above method.

By adopting in-mold molding in this way, the chopped sheet material 2 can be continuously molded by being fed out by the feeder 4 each time it is molded. Here, the chop sheet material 2 includes the non-impregnated portion 24 in which the reinforcing fibers 22 and the matrix resin 23 are not mixed and is laminated very thinly, so that the chop sheet material 2 and the base material 1 are laminated. In the integration, the chop sheet material 2 can be flexibly deformed to form a three-dimensional molded body. Therefore, even in a shape with a large change in shape such as a tall rib or a deep recess, the chop sheet material 2 spreads over the entire shape, and the yield is good, so that the compact 100 can be efficiently manufactured.

"Modification 1"
Next, a molded body 101 of a modified example of the present invention will be described with reference to FIGS. 6 to 8. FIG. In the description below, the same reference numerals are used for the same parts, and overlapping descriptions are omitted.

In this modified example, as shown in FIG. 6, the frame is a structure in which the base material 1 is molded into a bar shape with a V-shaped cross section, and the fiber direction is set in a single direction on the outer peripheral surface excluding both longitudinal end surfaces. A UD sheet material 5, which is a fiber-reinforced resin sheet material arranged in a uniform pattern, is used.

The UD sheet material 5 of this modified example uses carbon fibers as the reinforcing fibers 51, and as shown in FIG. The matrix resin 52 is placed and heated and sandwiched between rollers. At this time, the average number of reinforcing fibers 51 in the thickness direction is set to be in the range of 2 to 10.
Also in this modification, the volume content Vf of the reinforcing fibers 22 in the UD sheet material 5 is adjusted to be 20% or more and 80% or less. Also, the thickness of the UD sheet material 5 is set to 20 μm or more and 70 μm or less. By setting the thickness within this range, the molded article 101 can be flexibly deformed at the time of molding, and sufficient strength can be ensured.

Here, an unimpregnated portion 53 in which the matrix resin 52 is not impregnated is formed in a portion of the reinforcing fiber 51 . In this modified example, a portion in which only the reinforcing fibers 52 exist without the matrix resin 52 exists in the middle region of the thickness.

On one side of the UD sheet material 5, an additional resin sheet material 6, which is a resin layer made of the same polyamide resin as the matrix resin 52, is laminated. The additional resin sheet material 6 can be laminated at the same time as the reinforcing fibers 51 are impregnated with the matrix resin 52 .
By providing the additional resin sheet material 6 in this way, when the molded body 101 is formed, the reinforcing fibers 51 can be prevented from becoming fuzzy and exposed from the surface.
The resin layer may be formed by laminating sheet materials as in this modified example, or may be formed by coating a resin material.

The molded body 101 obtained by laminating and integrating the UD sheet material 5 and the base material 1 as described above can be manufactured by the method shown in FIG. First, as shown in FIG. 8(a), the UD sheet material 5 including the additional resin sheet material 6 is previously processed into a three-dimensional shape by the press machine 7. Then, as shown in FIG. The press machine 7 heats and presses the UD sheet material 5 with an upper die 71 and a lower die 72 to obtain an insert member 8 . At this time, it is preferable to configure such that unnecessary portions are automatically trimmed, but trimming may be performed by pressing using another cutting die.

Next, as shown in FIG. 8(b), the insert member 8 is inserted into a fixed side mold 31 of the mold attached to the injection molding machine 3 and fixed. In this state, as shown in FIG. 8(c), the fixed side mold 31 and the movable side mold 32 are closed, and the polypropylene resin that becomes the base material 1 is injected into the formed space.

Since the insert member 8 has already been three-dimensionally molded, the insert member 8 receives such a force as to be pressed against the stationary mold 31 by the injected polypropylene. Thereby, as shown in FIG. 8(c), the matrix resin 52 and the polypropylene serving as the base material 1 are melted and integrated.

In this state, P/V switching is performed, holding pressure is applied, and after cooling for a predetermined time, as shown in FIG. Remove from mold. The molded body 101 can be manufactured by the above method.

By adopting film insert molding in this way, the molded body 101 with high reproducibility of shape can be obtained, and molding defects in three-dimensional UD sheet material 5 can be reduced. Here, the UD sheet material 5 includes a non-impregnated portion 53 in which the reinforcing fibers 51 and the matrix resin 52 are not mixed, and is laminated very thinly, so that the UD sheet material 5 is pressed during the press working of the UD sheet material 5. can be flexibly deformed to form a three-dimensional molded body. Therefore, the UD sheet material 5 can be formed in an accurate shape even in a shape with a large shape change such as a tall rib or a deep recess, and the shape accuracy after injection molding is improved. Note that the insert member 8 may be inserted into the working mold 32 .

"Modification 2"
Next, another modified example of the present invention will be described with reference to FIG. This modified example is an example in which the molded body 100 using the chopped sheet material 2 shown in FIG. 1 is different from the chopped material 21 shown in FIG.

As shown in FIG. 9, the chopped sheet material 2 of this modified example is constructed by stacking a plurality of chopped materials 21, 21... cut into strips randomly in two-dimensional directions so as to have a uniform thickness. ing. This chopped material 21 has non-impregnated portions 24 and 24' in which the matrix resin 23 is not impregnated in part of the reinforcing fiber 22, as in the form of FIG.

Here, in the embodiment of FIG. 2 described above, as a manufacturing method, first, a film material serving as a matrix resin 23 is arranged between bundles of reinforcing fibers 22 spread to a predetermined width by various methods. It was supposed to be heated and sandwiched between rollers. Although the chopped sheet material 2 is sandwiched between rollers and formed into a sheet, only a pressure is applied to the chopped sheet material 2 to obtain a predetermined thickness. Therefore, when the fiber volume content Vf is high, some of the reinforcing fibers 22 may be exposed on the surface in a fuzzy manner.

On the other hand, in the modified example, the chop sheet material 2 molded to a predetermined thickness by rollers is press-processed while applying pressure with a heated flat plate-shaped mold or rollers, so that resin layers are formed on the front and back surfaces. are formed.

By additionally applying heat compression in this manner, the reinforcing fibers 22 are flatly pressed and the surfaces of the reinforcing fibers 22 are covered with the softened matrix resin 23 . As a result, the front and back surfaces of the chop sheet material 2 become smooth surfaces, and the reinforcing fibers 22 are not exposed. Therefore, it is possible to prevent the reinforcing fibers 22 from peeling off, and the appearance of the design surface is beautiful.

The present invention is not limited to the above embodiments. For example, in the non-impregnated portion, a powdery or short fibrous matrix resin is dispersed between reinforcing materials, and then heated and pressed to melt the matrix resin. Also, the matrix resin may exist discretely inside the bundled reinforcing fibers.

The reinforcing fiber resin sheet may be a UD sheet material, a chopped sheet material, a sheet material obtained by plain weaving reinforcing fibers, or a sheet material obtained by laminating and integrating UD sheet materials in the orthogonal direction.

100,101 Fiber-reinforced resin molding 1 Base material 2 Chopped prepreg sheet material
21 Chopped prepreg
22 reinforcing fibers
23 Matrix Resin
24 Unimpregnated part
25 Heating compression surface 3 Injection molding machine
31 Fixed side mold
32 Movable mold
33 Hopper
34 screw
35 nozzles
36 Inlet 4 Feeder
41 Release sheet material 5 UD sheet material
51 reinforcing fiber
52 Matrix Resin
53 Non-impregnated portion 6 Additional resin sheet material 7 Press machine
71 upper mold
72 Lower mold 8 Insert member

Claims (7)

A three-dimensional fiber-reinforced resin molded article in which a fiber-reinforced resin sheet in which reinforcing fibers are impregnated with a matrix resin made of a thermoplastic resin and a base material made of a thermoplastic resin are laminated and integrally molded,
A fiber-reinforced resin molded article characterized by being formed integrally with the fiber-reinforced resin sheet by melting and solidifying the thermoplastic resin of the base material. 2. The fiber-reinforced resin molded article according to claim 1, wherein the fiber-reinforced resin sheet includes a portion not impregnated with the reinforcing fibers and the matrix resin. 3. The fiber-reinforced resin molded article according to claim 1, wherein a resin layer made of a thermoplastic resin is laminated on at least one surface of the fiber-reinforced resin sheet. The fiber-reinforced resin sheet is a UD sheet material having reinforcing fibers aligned in a single direction or a plurality of chopped prepregs obtained by cutting the UD sheet material into strips so that the directions of the reinforcing fibers are pseudo-isotropic. 4. The fiber-reinforced resin molded article according to any one of claims 1 to 3, which is a laminated chopped prepreg sheet material. The fiber-reinforced resin sheet is a chopped prepreg sheet material made of a thermoplastic resin film and thin-layered reinforced fibers,
The volume content Vf of the reinforcing fibers in the chopped prepreg sheet material is 20% or more and 80% or less,
5. The fiber-reinforced resin molded article according to claim 4, wherein the chopped prepreg sheet material has a thickness of 40 μm or more and 3000 μm or less. In the method for producing a three-dimensional fiber-reinforced resin molded product according to any one of claims 1 to 5,
The mold is closed while the fiber-reinforced resin sheet composed of the reinforcing fibers and the matrix resin is stretched in a plane in advance,
A method for producing a fiber-reinforced resin molded article, characterized by injecting a thermoplastic resin as a base material into the mold, shaping the fiber-reinforced resin sheet, and molding the sheet integrally with the base material by lamination. In the method for producing a three-dimensional fiber-reinforced resin molded product according to any one of claims 1 to 5,
A fiber-reinforced resin sheet composed of the reinforcing fibers and the matrix resin is three-dimensionally molded in advance to form an insert member;
inserting the insert member into a mold for injection molding,
A method for producing a fiber-reinforced resin molded article, characterized in that the fiber-reinforced resin sheet and the base material are integrally laminated by injection of a thermoplastic resin as a base material.

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