JP2985788B2 - Manufacturing method of long fiber reinforced thermoplastic resin molding material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a long fiber reinforced thermoplastic resin molding material (L-FRTP) obtained by impregnating a continuous inorganic fiber bundle with a thermoplastic resin and cutting it into a predetermined length.

[0002]

2. Description of the Related Art A long-fiber reinforced thermoplastic resin molding material has a longer fiber length than a molding material obtained by kneading a chopped strand and a thermoplastic resin into pellets. Excellent in reinforcing effect of plastic resin molded products.

As disclosed in Japanese Patent Publication No. 52-10140, for example, a long fiber reinforced thermoplastic resin molding material is prepared by supplying a continuous inorganic fiber bundle to an impregnation die (a molten resin tank) to melt the thermoplastic resin. The resin is applied or impregnated, the excess thermoplastic resin is removed through a nozzle of a predetermined diameter, a slit or a die provided at the outlet of the impregnation die to obtain a predetermined fiber content and shaped into a predetermined shape, and cooled. Thereafter, it is manufactured by cutting into a predetermined length to obtain a cut product having a shape such as a pellet shape.

The long-fiber-reinforced thermoplastic resin molding material thus obtained is mixed with a thermoplastic resin containing no inorganic fiber so as to have a desired fiber content, and if necessary, a coloring agent, other additives, etc. Is added and molded into a desired shape by a method such as injection molding to obtain a molded article. In addition, in order to transfer the long fiber reinforced thermoplastic resin molding material at the time of molding or the like, a conveying means using a fluid such as an air flow is often used.

However, the long-fiber-reinforced thermoplastic resin molding material manufactured by the above-described conventional method is difficult to impregnate the inorganic fiber bundle with the thermoplastic resin sufficiently, and it is difficult to impregnate the single fiber constituting the fiber bundle. In many cases, voids were formed or inorganic fibers were exposed on the outer peripheral surface of the cut material, and the inorganic fibers on the end face of the cut material were also exposed by cutting. Therefore, when such a long-fiber-reinforced thermoplastic resin molding material is transported by placing it on a fluid such as an air stream, the inorganic fibers are likely to fall off from the outer peripheral surface or the end surface of the cut product, and fluff is likely to be generated. , Hindering transfer, reducing productivity,
In addition, there is a problem that the appearance of the molded product is deteriorated.

Further, since the inorganic fiber bundle is not sufficiently impregnated with the thermoplastic resin, the inorganic fibers are difficult to be uniformly dispersed in the thermoplastic resin at the time of molding, and the mechanical properties of the obtained molded product are deteriorated and the appearance is reduced. There was a problem of getting worse.

To solve such a problem, for example, US Pat.
P4,439,387, JP-A-63-264326, JP-A-6-2548
No. 56, etc., the inorganic fiber bundle introduced into the impregnation die,
A long fiber reinforced thermoplastic resin molding material that is opened by applying tension to the protrusions, rollers, etc. provided inside the impregnation die to improve the impregnation of the inorganic fiber bundle with the thermoplastic resin. Is disclosed.

[0008]

[Problems to be solved by the invention] However, USP4,4
No. 39,387, JP-A-63-264326, JP-A-6-254856, etc., the method disclosed in Japanese Patent Application Laid-Open No. 6-254856 discloses that the inorganic fiber bundle is brought into contact with a projection, a roller or the like to open the fiber under tension, so that the friction is caused by friction. A part of the single fiber constituting the inorganic fiber bundle is cut and becomes fluff, and the fluff is clogged by a nozzle or the like of the impregnation die, which in turn blocks the nozzle and the like, and the tensile resistance of the inorganic fiber bundle increases, and the inorganic fiber bundle However, there was a problem that the rupture occurred and production stopped. In addition, there is a problem that the fiber is not sufficiently opened when the tension at the time of contact with the protrusion, the roller, or the like is weak, and therefore, the impregnation property of the thermoplastic resin is not sufficiently improved. The glass fiber content of the glass long fiber reinforced thermoplastic resin molding material using glass long fibers as the inorganic fibers is generally 20 to 80% by weight. The problem caused by the generation of fluff is likely to occur particularly when glass fibers are contained at a high ratio of 50% by weight or more.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to reduce the generation of fluff during production and transfer, and to produce a thermoplastic resin molded article by a method such as injection molding. To provide a method for producing a long-fiber-reinforced thermoplastic resin molding material that has excellent dispersibility of inorganic fibers in a thermoplastic resin as a matrix and can improve the mechanical properties and appearance of the resulting thermoplastic resin molded product. Is to do.

[0010]

In order to achieve the above object, a first aspect of the present invention is to coat or impregnate a continuous inorganic fiber bundle with a thermoplastic resin and cut it into a predetermined length to obtain a cut product. Thereafter, in a state in which the cut pieces are dispersed so as not to substantially contact with each other, the cut pieces are heated to a melting temperature of the thermoplastic resin or higher to melt the thermoplastic resin applied or impregnated to the cut pieces, and then cooled. It is intended to provide a method for producing a long-fiber-reinforced thermoplastic resin molding material, characterized in that:

A second aspect of the present invention is the first aspect of the present invention, wherein
An object of the present invention is to provide a method for producing a long-fiber-reinforced thermoplastic resin molding material in which the cut material is placed on a conveyor and the conveyor is vibrated to disperse the cut material so that the cut material is not substantially in contact with the cut material.

A third aspect of the present invention is the method of the first or second aspect of the present invention, wherein a glass fiber bundle is used as the inorganic fiber bundle and the fiber content is 50% by weight or more. It provides the law.

In the present invention, the state in which cut pieces are dispersed so that they do not substantially come into contact with each other means that when the thermoplastic resin applied or impregnated to the cut pieces is melted, most of the cut pieces stick to each other. , But dispersed in such a way that they can be kept individually separated.

According to the first aspect of the present invention, the thermoplastic resin applied or impregnated to the cut material is heated by heating the thermoplastic resin to a temperature not lower than the melting temperature of the thermoplastic resin in such a state that the cut material is dispersed so as not to come into contact with the thermoplastic resin. Melts and oozes into the outer peripheral surface and the end surface of the cut material, and penetrates between the single fibers of the cut material. In this case, the inorganic fiber bundle in the cut material has a significantly lower binding force as a fiber bundle compared to the state of the continuous inorganic fiber bundle before cutting, and the single fiber is relatively thin due to the surface tension of the molten thermoplastic resin. It is thought that the molten resin easily penetrates between the single fibers because there is free movement in the cut material, voids between the single fibers are eliminated, and impregnation of the inorganic fiber bundle with the resin is improved.

Therefore, in the step of applying or impregnating the thermoplastic resin to the continuous inorganic fiber bundle, the inorganic fiber bundle is brought into contact with the projections and rollers in order to open the inorganic fiber bundle and enhance the impregnation of the resin. Even without applying strong tension,
Since the impregnating property of the resin can be increased in the subsequent heating step, the generation of fluff in the step of applying or impregnating the thermoplastic resin can be reduced, and the productivity can be improved.

Further, since the obtained long fiber reinforced thermoplastic resin molding material is coated with a molten thermoplastic resin on the outer peripheral surface and the end surface, the inorganic fiber can be transferred even by being carried on a fluid such as an air flow. Does not fall off and generates less fluff. Further, when producing a thermoplastic resin molded article, the inorganic fibers are uniformly dispersed in the thermoplastic resin as a matrix, whereby the mechanical properties of the molded article can be improved and the appearance can be improved.

According to the second aspect of the present invention, the cut objects are placed on a conveyor, and the conveyed objects are vibrated to disperse the cut objects so that they are not substantially in contact with each other. In addition, the thermoplastic resin can be melted by heating in a state where the cut pieces are dispersed so as not to come into contact with each other, so that the cut pieces can be prevented from being joined to each other.

According to the third aspect of the present invention, the glass fiber bundle is used as the inorganic fiber bundle, and the fiber content is set to 50% by weight or more, so that the impregnation of the inorganic fiber bundle with the thermoplastic resin is improved. Effects such as reduction of generation can be more remarkably obtained.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION As the continuous inorganic fiber bundle in the present invention, those usually used for a long fiber reinforced thermoplastic resin molding material can be used. For example, inorganic fibers such as glass fiber and carbon fiber can be used. It is preferable to use a bundle that is pulled out from a wound body that is wound into a predetermined shape, for example, a drum shape or a cylindrical shape. It is more preferable to use glass fiber as the inorganic fiber because it is advantageous in terms of cost.

The number of bundles of the single fibers as the inorganic fiber bundle is preferably about 100 to 20,000 because it is easy to apply or impregnate the thermoplastic resin. In addition, a plurality of inorganic fiber bundles having a relatively small number of bundles may be aligned and used.

In general, glass fibers are used to improve handling properties by suppressing generation of fluff and static electricity during use, and to improve adhesiveness with a thermoplastic resin to be applied or impregnated. Although various binders are provided, it is preferable to select the type of the binder according to the type of the thermoplastic resin to be applied or impregnated.

In the present invention, the thermoplastic resin is not particularly limited. For example, polyethylene, polypropylene, polyamide, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyacrylonitrile, polyacetal, polyetherimide, polycarbonate and the like are preferably used. . These resins may be used alone or as a mixture or copolymer of two or more. In addition, the thermoplastic resin may be blended with known additives such as a coloring agent, a modifying agent, and a filler other than inorganic fibers, depending on the application and molding conditions, etc., according to a conventional method. Can be kneaded and used.

In the present invention, the fiber content of the long fiber reinforced thermoplastic resin molding material is not particularly limited,
To make the effect of the present invention remarkable, the fiber content should be 50% by weight.
It is preferable to make the above. That is, the fiber content is 50
When the content is more than 50% by weight, problems such as a decrease in the impregnating property of the thermoplastic resin and the generation of fluff are likely to occur. This is because fluffing can be reduced.

The method for producing a long fiber reinforced thermoplastic resin molding material of the present invention can be carried out, for example, by a production line as shown in FIG. That is, a continuous inorganic fiber bundle 1 drawn from a wound body (not shown) is introduced into the impregnation die 4. The molten thermoplastic resin 2 is supplied to the impregnation die 4 from the extruder 3, and the inorganic fiber bundle 1 is impregnated with the thermoplastic resin. Inorganic fiber bundle impregnated with thermoplastic resin 1
Is drawn out through a die 5, whereby excess thermoplastic resin 2 is removed to have a predetermined fiber content and shaped into a predetermined shape, thereby forming a long fiber reinforced thermoplastic resin 6.

Next, the long-fiber-reinforced thermoplastic resin 6 thus obtained is cooled in a cooling tank 7, taken up by a take-up machine 8, and cut into pellets by a pelletizer 9 to obtain a cut product 10a. The steps up to this point are the same as those of a conventional general long-fiber-reinforced thermoplastic resin molding material, and this cut product 10a corresponds to a conventional general long-fiber-reinforced thermoplastic resin molding material. I do.

In the present invention, subsequently, the cut material 10a obtained as described above is sent onto a conveyor 11 connected to the pelletizer 9, and the conveyor 11 is vibrated by a vibrator (not shown) to cut the material. Object 10a is conveyor 11
The resin is dispersed to such a degree that it hardly contacts each other, and is passed through a heating tank 13 provided with a heater 12 and heated to a temperature higher than the melting temperature of the thermoplastic resin 2. As a result, the cut material 1
The thermoplastic resin 2 impregnated with Oa is melted and cut 10
In addition to the leaching on the outer periphery and the end face of the cut material 10a, it also permeates between the single fibers of the inorganic fiber bundle in the cut material 10a. After that, cut 10
is cooled by the cooler 14 and scraped from the conveyor 11 by the scraper 15 to obtain the long fiber reinforced thermoplastic resin molding material 10b. The long fiber reinforced thermoplastic resin molding material 10b is in a state in which the thermoplastic resin 2 covers almost the entire outer peripheral surface and end surface of the cut material 10a.

The method of transporting the cut material 10a from the pelletizer 9 to the heating tank 13 may be any method other than the method using the conveyor 11, such as a method in which the cut material 10a is loaded on a fluid such as an air flow, a method by free fall, and the like. Is also good. When the method using the conveyor 11 is adopted, the conveyor 1
1 If the surface is treated with a silicone resin, a fluororesin, or the like, the thermoplastic resin 2 of the cut material 10a is heated and melted, and then cooled to obtain a long fiber reinforced thermoplastic resin molding material 10b. 11 because it is easy to scrape from above.

The heater 12 of the heating tank 13 is not particularly limited, but for example, a hot air generator, an infrared heater or the like is preferably employed. The heating temperature and the time are
0a is impregnated with the thermoplastic resin 2,
It is preferable that the temperature and time be sufficient to cover the outer periphery and the end face of Oa and to penetrate between the single fibers therein, and to such a degree that the thermoplastic resin does not deteriorate. The inside of the heating tank 13 may be an air atmosphere, but may be an inert gas atmosphere such as a nitrogen gas in order to prevent deterioration of the thermoplastic resin 2.

The method of cooling by the cooler 14 may be any method that can cool at least a temperature at which the cut pieces do not fuse together when collected. For example, a method using cold air or cold water is preferably employed. . Cooler 1
Instead of the forced cooling in step 4, a method of cooling at room temperature may be used.

In the above example, as a method of applying or impregnating the thermoplastic resin 2 to the continuous inorganic fiber bundle 1, a melt impregnation method of impregnating the inorganic fiber bundle 1 with the molten thermoplastic resin 2 is employed. , And other methods can be adopted. For example, a thermoplastic resin emulsion, a slurry obtained by dispersing a thermoplastic resin powder in water or another solvent, or a solution obtained by dissolving a thermoplastic resin in a solvent is impregnated into an inorganic fiber bundle, or applied with a roll coater or the like. After that, a method of evaporating the dispersion medium or the solvent or the like can be adopted. In addition, after the thermoplastic resin powder is attached to the inorganic fiber bundle, a method in which the resin is heated, melted, and cooled as necessary can be employed. However, the melt impregnation method is preferred from the viewpoints of handleability and cost.

[0031]

【Example】

Example 1 According to the method described above using the production line shown in FIG.
A long fiber reinforced thermoplastic resin molding material was manufactured. The continuous inorganic fiber bundle 1 has a fiber diameter provided with a binder containing a silane coupling agent and a modified polypropylene as main components.
Eighty 13 μm E glass single fibers are bundled, and a bundle of eight such fiber bundles is used. The thermoplastic resin 2 is made of polypropylene, the impregnation die 4, the cooling tank 7,
The take-off machine 8 and the pelletizer 9 are the same as those conventionally used, and the die 5 at the outlet of the impregnation die 4 is used.
A cut product 10a was obtained with a diameter of 2.0 mm, a take-up speed of 30 m / min, and a cut length of 6 mm with a pelletizer 9.

Next, the obtained cut pieces 10a were placed on a conveyor 11 having a surface subjected to a fluororesin processing, and the conveyer 11 was vibrated to disperse the cut pieces 10a so that the cut pieces 10a did not substantially contact each other. In this state, the cut material 10a is introduced into a heating tank 13 at an atmospheric temperature of 200 ° C. provided with a heater 12 composed of an infrared heater, and is heated while being retained for one minute. After cooling to about 40 ° C. by blowing cool air, the scraper 15 scraped off the conveyor 11 to obtain a long fiber reinforced thermoplastic resin molding material 10b. The glass content of the long fiber reinforced thermoplastic resin molding material 10b is 51% by weight.
Met.

This long fiber reinforced thermoplastic resin molding material is
Almost the entire outer peripheral surface and the end surface were covered with polypropylene, and the inorganic fibers were held so as not to be easily dispersed.

Example 2 In Example 1, as the continuous inorganic fiber bundle, ten glass fiber bundles similar to those in Example 1 were used.
After that, in the same manner as in Example 1, a long fiber reinforced thermoplastic resin molding material having a glass content of 60% by weight was obtained.

This long fiber reinforced thermoplastic resin molding material is also
Almost the entire outer peripheral surface and the end surface were covered with polypropylene, and the inorganic fibers were held so as not to be easily dispersed.

Example 3 In Example 1, 13 continuous glass fiber bundles similar to those in Example 1 were used as continuous inorganic fiber bundles.
After that, in the same manner as in Example 1, a long fiber reinforced thermoplastic resin molding material having a glass content of 73% by weight was obtained.

This long fiber reinforced thermoplastic resin molding material is also
Almost the entire outer peripheral surface and the end surface were covered with polypropylene, and the inorganic fibers were held so as not to be easily dispersed.

Comparative Example 1 In Example 1, the steps up to the step of obtaining the cut piece 10a were performed in the same manner, and the steps of heating the cut piece 10a were not performed.
A long fiber reinforced thermoplastic resin molding material having a glass content of 51% by weight was obtained.

This long fiber reinforced thermoplastic resin molding material is
Glass fiber was exposed in a part of the outer peripheral surface and a large part of the end surface.

Comparative Example 2 In Example 2, the steps up to the step of obtaining the cut object 10a were performed in the same manner, and the steps of heating the cut object 10a were not performed.
A long fiber reinforced thermoplastic resin molding material having a glass content of 60% by weight was obtained.

This long fiber reinforced thermoplastic resin molding material is also
Glass fiber was exposed in a part of the outer peripheral surface and a large part of the end surface.

Comparative Example 3 In Example 3, the steps up to the step of obtaining the cut object 10a were performed in the same manner, and the steps of heating the cut object 10a were not performed.
A long fiber reinforced thermoplastic resin molding material having a glass content of 73% by weight was obtained.

This long fiber reinforced thermoplastic resin molding material is also
Glass fiber was exposed in a part of the outer peripheral surface and a large part of the end surface.

Test Example Each of the long-fiber-reinforced thermoplastic resin molding materials obtained in Examples 1 to 3 and Comparative Examples 1 to 3 was mixed with a predetermined amount of polypropylene, and then injection-molded to obtain a glass content of about 20%. A weight percent test specimen was obtained.

With respect to the obtained test pieces, the dispersion state of the glass fibers was visually observed, and the number of glass fiber bundles which looked like bundles was counted as non-dispersed. Further, as mechanical properties of each test piece, tensile strength and flexural strength were measured according to ASTM D 638 and ASTM D 790.

Using a hopper loader (trade name "BS-700", manufactured by Kato Riki Co., Ltd.), 10 kg of each of the long fiber reinforced thermoplastic resin molding materials obtained in Examples 1 to 3 and Comparative Examples 1 to 3 was used. With an air flow of 20m / s, the inner diameter is 38mm
The powder was transported 3 m in a φ vinyl chloride tube, and the fluff generated during the transport was collected by a 100-mesh wire mesh provided at the suction port of the hopper loader, and its weight was measured. Table 1 shows the results.

[0047]

[Table 1]

From the results shown in Table 1, when the long fiber reinforced thermoplastic resin molding materials of Examples 1 to 3 and Comparative Examples 1 to 3 were transferred by an air flow, the amount of fluff generated was the same in both Examples and Comparative Examples. The higher the glass content, the higher the glass content. However, comparing the same glass content, it can be seen that the example is considerably less than the comparative example.

Further, in the test pieces in which polypropylene was mixed with the long fiber reinforced thermoplastic resin molding material of Examples 1 to 3 and Comparative Examples 1 to 3 so that the glass content was almost the same, Comparing the undispersed number, Example 1
Comparative Examples 1 to 3 are all 0.
All three have undispersed ones, and the higher the glass fiber content as a long fiber reinforced thermoplastic resin molding material, the more undispersed ones. Further, it can be seen that the test pieces of Examples 1 to 3 are superior to the test pieces of Comparative Examples 1 to 3 in both tensile strength and bending strength.

[0050]

As described above, according to the method for producing a long fiber reinforced thermoplastic resin molding material of the present invention, a continuous inorganic fiber bundle is coated or impregnated with a thermoplastic resin, and cut into predetermined lengths. After being cut into cut pieces, the cut pieces are heated to a temperature higher than the melting temperature of the thermoplastic resin in a state of being dispersed so as not to substantially contact, and the resin applied or impregnated to the cut pieces is melted and then cooled. Therefore, there is little generation of fluff when transferred by a fluid such as an air flow, and the dispersibility of the inorganic fibers in the thermoplastic resin that serves as a matrix during molding is improved, resulting in a molded article with improved mechanical properties and appearance. Obtainable.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a production line for implementing a method for producing a long fiber reinforced thermoplastic resin molding material of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inorganic fiber bundle 2 Thermoplastic resin 3 Extruder 4 Impregnation die 5 Dice 6 Long fiber reinforced thermoplastic resin 7 Cooling tank 8 Pickup machine 9 Pelletizer 10a Cut material 10b Long fiber reinforced thermoplastic resin molding material 11 Conveyor 12 Heater 13 Heating Vessel 14 Cooler 15 Scraper

Claims (3)

(57) [Claims] 1. A continuous inorganic fiber bundle is coated or impregnated with a thermoplastic resin, cut into predetermined lengths to obtain cut pieces, and the cut pieces are dispersed so as not to come into contact with each other. A method for producing a long-fiber-reinforced thermoplastic resin molding material, comprising heating the thermoplastic resin at a temperature not lower than the melting temperature of the thermoplastic resin to melt the thermoplastic resin applied or impregnated to the cut product, and then cooling. 2. The method for producing a long-fiber-reinforced thermoplastic resin molding material according to claim 1, wherein the cut material is placed on a conveyor, and the cut material is dispersed so as not to come into contact with the conveyor by vibrating the conveyor. . 3. The method for producing a long fiber reinforced thermoplastic resin molding material according to claim 1, wherein a glass fiber bundle is used as the inorganic fiber bundle, and a fiber content is 50% by weight or more.