JPH10325072A - Joining of composite fiber mat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for joining composite fiber mats of reinforced fiber and thermoplastic resin fiber including the steps of placing the edge of one mat over the edge of another mat to overlap for a predetermined area and then subjecting the overlapped area to needle punching to thereby allow the joined portions to become identical in form to the rest of the formation and be free of any peculiar point of strength. SOLUTION: A mat is fabricated by air-blending a reinforced fiber such as carbon fiber and a thermoplastic resin fiber such as polyethylene terephthalate and then treated for needle punching to cause the fibers to interlace with each other to obtain a mat of composite fiber. To join two pieces of composite fiber mat at the respective ends, portions near the mat end are reduced in thickness for a given area or torn or left intact during the needle punching treatment, and the two ends are overlapped and needle punched to integrally join the two pieces of mat.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for joining a mixed fiber mat obtained by mixing a reinforcing fiber and a thermoplastic resin fiber.

[0002]

2. Description of the Related Art A mixed fiber mat comprising a reinforcing fiber and a thermoplastic resin fiber is known as a raw material for obtaining a fiber reinforced thermoplastic resin sheet by heating and pressurizing a thermoplastic resin in the mat (for example, as a raw material). JP-A-61-1
No. 30345).

When a long fiber-reinforced thermoplastic resin sheet is continuously formed by using such a mixed fiber mat, it is necessary to join the mixed fiber mat. This is because, in the state of the mixed fiber mat, it cannot be made long when it is wound around a paper core or the like because of its thick thickness, and it is necessary to obtain a continuous molded product of the fiber reinforced thermoplastic resin sheet. This is because it is necessary to join a plurality of mats at their ends.

Conventionally, as a method of joining the ends of such a mixed fiber mat, as shown in FIG. 7, the ends of the mats M1 and M2 are joined to each other, and organic fibers or glass fibers are sewn using a sewing machine or the like. And a method of sewing and joining with a thread F made of the same.

[0005]

When the mixed fiber mat is spliced by using the conventional joining method as described above, the tensile strength of the joint portion is caused by the strength of the thread used for suturing, and the mixed fiber mat is In the process of continuously forming the sheet into sheets, there is a problem that the sheet is broken by a tensile force acting on the mat.

In addition, according to the above-mentioned joining method, when the joined mixed fiber mat is continuously formed into a sheet, the joining portion is thinned or transparent (a hole is formed).
Such a problem has also arisen.

The present invention has been made in view of the above circumstances, and has a problem that a joining portion is broken by a tensile force in a sheet forming process, or that the obtained sheet is thinned or transparent near the joining portion. It is an object of the present invention to provide a splicing method of a mixed fiber mat which does not cause the occurrence of cracks.

[0008]

In order to achieve the above object, a method of joining a mixed fiber mat according to the present invention comprises the steps of: needle-punching ends of a mixed fiber mat comprising a reinforcing fiber and a thermoplastic resin fiber. It is characterized by inheriting by.

Here, in the present invention, when performing the needle punch to join the ends of the mixed fiber mat, the ends of the mixed fiber mat are overlapped, and the overlap is performed by applying a needle punch to the overlapped portion. In the method (Claim 2), the thickness of the predetermined region near the end of the mixed fiber mat is reduced, and the ends are overlapped with each other at the portion where the thickness is reduced. (Claim 3), a predetermined area near the end of the mixed fiber mat is torn, and the ends are overlapped with each other at the torn portion.
A method in which the overlapping portion is joined by applying a needle punch (Claim 4), and in the production of the mixed fiber mat, a predetermined region near the end is left in a state where the needle punch is not applied, and the needle punch is not applied. It is possible to adopt a method in which the ends are overlapped at the portions and the overlapped portions are joined by needle punching (claim 5).

According to the present invention, since the ends of the mixed fiber mat are joined by needle punching, the form of the spliced portion is equivalent to that of the portion other than the spliced portion. It does not become a singular point, and there is no problem of breaking or see-through due to tensile force.

In the present invention, the ends of the mixed fiber mat to be needle-punched may be in abutted state or in an overlapped state. Is preferred because

When ends are simply overlapped with each other (see FIG. 1), the weight of the spliced portion increases, but there is no particular problem if the thickness does not change when the mixed fiber mat is continuously formed into a sheet. Further, even if the thickness of the sheet is locally thick at the joint portion of the mat, there is no problem in forming.

When the end portions of the mixed fiber mat are overlapped with each other, they may be simply overlapped as described above or may be overlapped after the thickness of the end portion is reduced.
The thickness can be reduced by splitting the mixed fiber mat at the end to be joined into about half in the thickness direction and overlapping the split ends (see FIG. 2), or by using a jig for tearing the end of the mat. A method of substantially loosening the mat of the part by tearing and overlapping the part (see FIG. 3) can be adopted.

Further, in the present invention, when joining the end portions of the mixed fiber mat, the joint portion is needle-punched, so that the mixed fiber mat to be joined by applying the present invention is needle-punched. In the case of, at the time of its manufacture, the ends are matted without being subjected to a needle punch, and as illustrated in FIG. 4, the ends where the needle punch is not applied are overlapped at the time of joining, Or, after reducing the thickness of the end and superimposing, or after tearing and unraveling the end and superimposing, it is better to apply a needle punch, so that the fibers are more entangled with each other, so that the strength can be exhibited more .

Here, the mixed fiber mat for joining the ends by applying the present invention has the following material and form. (1) Reinforcing fiber It is thermally stable at the melting temperature of the thermoplastic resin. For example, inorganic fiber such as glass fiber, carbon fiber, and ceramic fiber, organic fiber such as polyamide fiber and polyester fiber, or metal fiber. For example, any fiber having a tensile modulus of 10 GPa or more can be used.

The diameter of the monofilament of the fiber is from 1 to 5
0 μm is preferable, and 2 to 30 μm is particularly preferable. When the diameter is less than 1 μm, the strength of the obtained fiber reinforced thermoplastic resin sheet is not sufficient, and when it exceeds 50 μm, it becomes difficult to penetrate the resin between the fibers and connect the fibers with the resin. , The strength cannot be developed.

(2) Thermoplastic resin fiber Any fiber can be used as long as it can be obtained in fibrous form. For example, olefin resins such as polyethylene and polypropylene, nylon, acrylonitrile, polyethylene terephthalate and the like can be mentioned.

The above-mentioned thermoplastic resins may be used alone or in combination, and may be used as heat stabilizers, plasticizers, lubricants, antioxidants, ultraviolet absorbers, pigments, inorganic fillers, reinforcing short fibers and the like. Additives, fillers, processing aids, modifiers and the like may be added.

(3) Mixed Fiber Mat Made of Thermoplastic Resin Fiber and Reinforcement Fiber The method for producing the mat is not particularly limited. For example, the thermoplastic resin fiber and the reinforcement fiber are cut into appropriate lengths, mixed, and air-mixed. After lamination, a method of forming a mat by needle punching can be exemplified.

[0020]

EXAMPLES Examples in which the present invention is applied and mixed fiber mats are actually applied will be described together with comparative examples.

Here, the mixed fiber mat used in each of the following Examples and Comparative Examples was manufactured as follows. A carbon fiber (CF) having a diameter of about 10 μm and an average length of about 50 mm and a polyethylene terephthalate (PET having a diameter of about 20 μm and an average length of about 50 mm (PET, melting temperature 255)
° C) The fibers were mixed with air to form a mat, and the fibers were entangled with each other by a needle punch to obtain a mixed fiber mat.

The obtained mixed fiber mat has a basis weight of about 4
50 k / m ² , each fiber is CF: P
ET = 45: 55. The mixed fiber mat had a thickness of 7 mm and a length of 100 m and was wound around a paper core.

Example 1 As shown in FIG. 1, a mixed fiber mat M having a needle punched to the end of the mat.
By simply superimposing the ends of M1 and M2 and applying a needle punch NP to the superimposed portion, 2
The mats M1 and M2 were succeeded.

Example 2 As shown in FIG. 2, a mixed fiber mat M having a needle punched to the end of the mat.
By dividing each end of M1 and M2 in the thickness direction, about 1
/ 2, and the cracked portions were overlapped and needle-punched NP and joined.

Example 3 As shown in FIG. 3, a mixed fiber mat M having a needle punched to the end of the mat.
Each end of 1, M2 was torn in half in the longitudinal direction over 15 mm, and the torn portions were overlapped and connected with a needle punch NP. In addition, as shown in FIG. 5, the end tearing step uses a tearing jig J in which a plurality of blades B are arranged in parallel, and a mat M1,
A method was adopted in which the mats M1 and M2 were pulled in the longitudinal direction after the end of M2 was placed and penetrated.

(Embodiment 4) As shown in FIG. 4, mixed fiber mats M1 'and M2' having an area U on which no needle punch is applied at the end of the mat are manufactured.
1 ′ and M2 ′ were overlapped in the area U where the needle punch was not applied, and the portion was connected by applying the needle punch NP.

(Comparative Example) As shown in FIG. 7, the ends of the mixed fiber mats M1 and M2 were butted together and stitched with a glass thread F.

(Evaluation by Sheeting Mixed Fiber Mats Spliced in Each Example) In order to evaluate the splicing methods shown in the above Examples and Comparative Examples, spliced portions were formed at 10 m intervals by each splicing method. Mixed fiber mats each having a total length of 100 m were prepared. Then, a fiber-reinforced thermoplastic resin sheet S was formed from each of the mats M by the apparatus shown in FIG.

In the apparatus shown in FIG. 6, a mixed fiber mat M fed from a mat feeder 61 is supplied to a heating furnace 6.
2. The fiber reinforced thermoplastic resin sheet S formed in this order is led to a heating roll 63 and a cooling roll 64 in order, and the fiber reinforced thermoplastic resin sheet S thus formed is taken up by a take-up machine 65 and wound up by a take-up machine 66. A reinforced thermoplastic resin sheet S is obtained.

The molding conditions of the apparatus shown in FIG. 6 are as follows. The heating furnace 62 was provided with upper and lower six far-infrared heaters, and the atmosphere temperature of the mat passage portion in the furnace was set at 285 ° C.

The diameter of the heating roll 63 was 250 mm, the surface temperature of the roll was set to 100 ° C., and the heating pinch pressure was set to a linear pressure of 20 kgf / cm. Cooling roll 64
Is 250 mm in diameter, the roll surface temperature is set to 30 ° C., and the cooling pinch pressure is a linear pressure of 20 kgf.
/ Cm.

The line speed is 1.5 m / min, and the width 5
A 00 mm fiber-reinforced thermoplastic resin sheet S was continuously obtained. The mixed fiber mat M having ten joints formed in each of the examples and the comparative examples was continuously formed into a sheet under the above-mentioned molding conditions, and the obtained fiber-reinforced thermoplastic resin S was observed to check the joints. Inspect for see-through,
[Table 1] shows the result of investigation of the presence or absence of breakage during molding.

[0033]

[Table 1]

As is apparent from Table 1, when the mixed fiber mats joined according to the embodiments of the present invention are used,
While no see-through of the joint and no breakage during molding were observed, when the mixed fiber mat joined according to the comparative example was used, see-through of the joint occurred at four places, and at the time of molding, It was broken at two places, confirming the effectiveness of the joining method of each example.

[0035]

As described above, according to the present invention, the end portions of the mixed fiber mat are joined by needle punching, so that the form at the spliced portion is equivalent to the form other than the spliced portion and the strength is improved. Singularities or defects, and the problem of breakage or see-through due to tensile force in the sheeting step or the like could be solved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a splicing method of a mixed fiber mat in Example 1 of the present invention.

FIG. 2 is an explanatory view of a splicing method of a mixed fiber mat in Example 2 of the present invention.

FIG. 3 is an explanatory view of a splicing method of a mixed fiber mat in Example 3 of the present invention.

FIG. 4 is an explanatory view of a splicing method of a mixed fiber mat in Example 4 of the present invention.

FIG. 5 shows a mixed fiber mat M in Example 3 of the present invention.
Explanatory drawing of the example of the tearing process of the edge part of 1 and M2.

FIG. 6 is an explanatory view of an apparatus formed into a sheet for evaluation of a mixed fiber mat spliced by each method.

FIG. 7 is an explanatory view of a splicing method of a mixed fiber mat in a comparative example.

[Explanation of symbols]

M1, M2 Mixed fiber mat M1 ', M2' Mixed fiber mat with no needle punch at the end M Mixed fiber mat with splice S Fiber reinforced thermoplastic resin sheet NP Needle punch U Area without needle punch 61 Mat feeding machine 62 Heating furnace 63 Heating roll 64 Cooling roll 65 Take-up machine 66 Winding machine

Claims (5)

[Claims] 1. A method for joining end portions of a mixed fiber mat comprising a reinforcing fiber and a thermoplastic resin fiber, wherein the end portions of the mat are joined by applying a needle punch. Mat splicing method. 2. The splicing method for a mixed fiber mat according to claim 1, wherein the end portions of the mixed fiber mat are overlapped with each other, and the overlapped portion is joined by applying a needle punch. 3. The mixed fiber mat is characterized in that the thickness of a predetermined area near the end of the mixed fiber mat is reduced, the ends are overlapped at a portion where the thickness is reduced, and the overlap is performed by applying a needle punch to the overlapped portion. The method of splicing a mixed fiber mat according to claim 1, wherein 4. The mixed fiber mat according to claim 1, wherein a predetermined region near the end of the mixed fiber mat is torn, the ends are overlapped at the torn portion, and the overlap is performed by applying a needle punch. The method for splicing a mixed fiber mat according to the above. 5. A method of manufacturing a mixed fiber mat according to claim 1, wherein a predetermined region near an end is manufactured without a needle punch, and ends are overlapped with each other at a portion where no needle punch is applied. The splicing method of the mixed fiber mat according to claim 1, wherein the splicing is performed by applying a needle punch to the portion.