JPH0785901B2 - Method for producing thermoformable composite material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention mainly relates to an inorganic fiber as a skeleton, and a thermoformable composite material in which the inorganic fiber is bonded with a binder containing a thermoplastic resin as a main component. The present invention relates to a method for producing a thermoformable composite material that can continuously obtain

(Prior Art) Conventionally, in order to produce a thermoformable composite material, a plastic material is melted by heating a sheet-like material made of a reinforcing fiber having a high elasticity and a thermoplastic material to melt the above-mentioned reinforcing fiber. A method has been proposed in which the sheet-like material is expanded by removing the stress of (1) and then compression-molded (JP-A-62-161529).

According to this method, the thickness of the sheet-like material can be increased by utilizing the elastic restoring force of the reinforcing fiber, so that the composite material can be molded with good moldability during compression molding.

(Problems to be solved by the invention) However, in the conventional method, in order to recover the thickness of the sheet-like material, since only the restoring force of the reinforcing fiber is used, in the product due to the condition of heat, Alternatively, there is a drawback that the thickness of each product is different, and moreover, the porosity of the sheet-like material could not be further increased.
Therefore, if the obtained sheet-like material is used as it is, for example, as a sound absorbing member, a heat insulating member, or the like, the properties thereof are insufficient, and further reduction in weight cannot be achieved.

The present invention has been made in view of the above-mentioned drawbacks, and it is possible to continuously obtain a thermoformable composite material that can control the thickness and reduce variations in the thickness, and that has a higher porosity. It is an object of the present invention to provide a method for producing a thermoformable composite material, which is capable of

(Means for Solving the Problem) The method for producing a thermoformable composite material according to the present invention comprises a member having a property that a thermoplastic resin adheres in a molten state and peels in a solid state, and moves intermittently, A step of supplying a mat-like material having a binder containing a thermoplastic resin as a main component and an inorganic fiber between a pair of transfer belts that repeatedly stop and heating to a temperature equal to or higher than the melting point of the thermoplastic resin, and transferring A step of separating the transfer belt while the belt is moving, and a step of compressing both transfer belts from the outside during stop, by compressing the stop transfer belt from both outer surface sides thereof, A pair of suction devices, which are arranged outside the transfer belts in front of the compression device in the transfer direction, are sucked onto the outer surfaces of the compressed transfer belts while the transfer belts are stopped. The gap between the pair of suction devices to expand the gap between the pair of transfer belts, and then stop the suction to release the suction of the transfer belt by the suction device, and cool the transfer belt to cool the mat-like material. Is separated from the inner surfaces of both transfer belts, thereby achieving the above object.

[Creation of mat-like material]

The mat-like material has a binder containing a thermoplastic resin as a main component and an inorganic fiber.

Examples of the inorganic fiber used in the present invention include one kind or two or more kinds of glass fiber, rock wool, ceramic fiber, carbon fiber and the like, and among them, glass fiber is preferable. The inorganic fiber is preferably obtained by, for example, defibrating an inorganic fiber strand in which a large number of filaments are bundled. The length of the inorganic fiber is preferably 5 to 200 mm, more preferably 10 to 100 mm from the viewpoint of easy formation of the mat-like material. In particular, it is preferable that 70% by weight of a material having a length of 50 mm or more is contained. Further, when the thickness becomes thin, the mechanical strength decreases, and when the thickness becomes thick, the bulk density becomes large and the bulk density increases, so that the range of 5 to 30 μm is preferable,
More preferably, it is 7 to 20 μm.

The binder that partially bonds the inorganic fibers is polyethylene,
The main component is a thermoplastic resin such as polypropylene, saturated polyester, polyamide, polystyrene, polyvinyl butyral, and polyurethane. The form of this binder can be any form such as fiber, powder, film,
They are each used in a suitable form depending on the method for producing the thermoformable composite material.

When the binder is used as the fiber, it is mixed with the inorganic fiber to form a mat-like material. For example, an inorganic fiber strand is supplied to a card machine, the strand is defibrated into filaments, and the fibers are mixed with a thermoplastic resin resin fiber to produce a mat-like material. The length of the thermoplastic resin fiber is 5 in view of the formability of the mat-like material.
~ 200 mm is preferable, more preferably 20 ~ 100 mm,
The thickness is preferably 3 to 50 μm, more preferably 20 to 40 μm.
m.

When the binder is used as a powder, it is used together with the inorganic fibers in the same manner as the fibrous binder to form a mat-like material, or air is formed after the mat is formed from the inorganic fibers. The mat-like material is formed by being pressed into the mat by jetting or the like to be held. Alternatively, after forming a mat from the inorganic fibers or the inorganic fibers and the thermoplastic resin fibers, a dispersion liquid or emulsion of the thermoplastic resin powder may be sprayed on the mat and dried. The diameter of the thermoplastic resin powder is preferably 50-100 mesh when it is added in powder form. Also, the diameter may be smaller when the powder is dispersed or added as an emulsion.

When the binder is used as a film, a mat-like material is formed by laminating it on a mat mainly composed of inorganic fibers.

Binders having different forms may be used together. For example, a mat is formed from the inorganic fiber alone or from the inorganic fiber and a fibrous and / or powdery thermoplastic resin binder,
One or a plurality of thermoplastic resin films may be laminated on at least one surface of the mat to form a mat-like material. When the binders having different forms are mixed and used, it is preferable that the melting temperatures of the binders be as close as possible.

The ratio of the inorganic fiber and the binder, the mechanical strength of the thermoformable composite material is reduced when the amount of the binder is reduced and the bonding portion is reduced, and conversely, when the amount is increased, the porosity is reduced,
When a thermoplastic resin film is used as the binder, the weight ratio is preferably 1/10 to 2/1 of the total weight of the mat-like material, and 1 / when the thermoplastic resin fiber or powder is used as the binder. 5 to 4/1 is preferable.

When the density of the mat-like material obtained in this way becomes heavier as the density increases, and as the density decreases, the mechanical strength decreases,
0.01 ~ 0.2 g / cm ³ is preferred, more preferably 0.03 ~ 0.07
It is g / cm ³ . The overall porosity is preferably 70 to 98%. Further, needle punching may be performed to increase the strength, and needle punching is preferably performed at 5 to 30 points per cm ² .

[Production of thermoformable composite material]

Next, a method for producing the thermoformable composite material of the present invention will be described.

The present invention can be carried out using the apparatus shown in FIG.

This device consists of a pair of upper and lower endless belt-shaped transfer belts.
A transfer device 1 having 1a and 1b, a heating device 2, a compression device 3, a suction device 4, and a cooling device 5 are provided.

Each of the transfer belts 1a and 1b is wound around a drive roll 10 and a plurality of guide rolls 11, 11 ...
The pair of transfer belts 1a and 1b are configured to be repeatedly moved and stopped at predetermined intervals by driving and stopping 10. Each transfer belt 1a, 1b has a substantially linear transfer portion 12a, 12b
Are provided so as to face each other, and a mat-like material supply unit 13 is formed between the transfer units 12a and 12b of the pair of transfer belts 1a and 1b. The transfer sections 12 and 12 move in the same direction (direction of arrow A), and the movement and stop are repeated at the same time.

The transfer belts 1a and 1b are formed of a member to which a molten thermoplastic resin adheres and a solidified thermoplastic resin does not adhere to each other. For example, a polytetrafluoroethylene (trade name "Teflon": registered trademark) belt or , Glass fiber, carbon fiber, aramid fiber, etc. coated with polytetrafluoroethylene (trade name "Teflon": registered trademark), aluminum plate, iron plate polytetrafluoroethylene (trade name "Teflon" : A product coated with (registered trademark) can be used.

The heating device 2 sets the heating temperature at or above the melting temperature of the thermoplastic resin used for the mat-like material so that it can heat the matte-like thermoplastic resin supplied into the transfer device 1. Has been done. The heating device 2 may be of a type that heats the whole with hot air of a dryer or the like, or may be of a radiant heating type such as a far infrared heater or an infrared heater.

The compression device 3 is a fixed press having a flat press surface.
3b and a movable press 3a that can be vertically driven. The fixed press 3b is arranged on the lower surface side of the moving part 12b of the lower transfer belt 1b, and the movable press 3a is the transfer part of the upper transfer belt 1a.
The movable press 3a is disposed on the upper surface side of 12a, and the movable press 3a is lowered toward the transfer belt 1a side by the operation of a hydraulic device or the like to compress both the transfer belts 1a and 1b from above and below with the fixed press 3b, and It is configured to rise and release compression. The lowering and raising of the movable press 3a are configured to be driven at predetermined intervals in accordance with the movement and stop of the transfer belts 1a and 1b,
The movements of the transfer belts 1a and 1b and the drive of the movable press 3a are interlocked with each other so that the transfer belts 1a and 1b descend and compress when they are stopped.

The suction device 4 is arranged at a front position of the compression device 3 in the transfer direction. The suction device 4 has a fixed suction device 4b having a flat suction surface and a movable suction device 4a. The fixed suction device 4b is arranged on the lower surface side of the straight portion 12b of the lower transfer belt 1b, and the movable suction device 4a is arranged on the upper surface side of the straight portion 12a of the upper transfer belt 1a. Each suction device 4 is connected to a pump, and on the suction surface of each suction device 4, as shown in FIG. 2, for example, a large number of suction holes 40 having a diameter of 3 mm are formed in a grid pattern of 10 mm × 10 mm pitch. It is provided so that the external air can be sucked from the suction hole 40 by driving the pump.

The movable suction device 4a is also configured to repeat the descending and ascending at predetermined intervals, and the movable suction device 4a is the transfer belt 1a.
The upper surface of the transfer belt 1a is a movable suction device when approaching
The upper transfer belt 1a is attracted to the suction surface of 4a, and then the movable suction device 4a rises so that the upper transfer belt 1a moves upward together with the movable suction device 4a, so that the distance between the pair of transfer belts 1a and 1b is widened. It has become.

Attraction force of the fixed suction device 4b and a movable suction unit 4a, for example preferably the average 0.01~0.3Kg / cm ^2, not sufficient attraction force is less than 0.01 kg / cm ^2, especially when more than 0.3 Kg / cm ² Although there is no problem with the suction force, it is not economical because it is necessary to provide a large number or large number of suction holes 40 on the suction surface. The transfer belts 1a and 1b are stopped even when the movable suction device 4a descends to perform suction.

Next, a time chart of the manufacturing apparatus will be described with reference to FIG.

In FIG. 3, A is the compression start time of the movable press 3a (at the start of driving), B is the compression point arrival time of the movable press 3a (at the end of driving), and C is the decompression start time of the movable press 3a (at the start of driving). , D indicate the timing (at the end of driving) when the movable press 3a reaches the standby point. Therefore, for example, regarding the movable press 3a on the upper side of the transfer belt 1a, A to B are movable presses.
3a shows a state in which the transfer belt 1a is descending,
B to C are in a compressed state, and in C to D, the movable press 3a is a transfer belt.
It shows a state of being separated from 1a and rising.
Now, as shown in the figure, the transfer belts 1a and 1b intermittently repeat the movement and the stop. The stop time (i) is completed by the time B, and the movement time (j) starts after the time C. Similarly, the movable press 3a intermittently repeats the standby state and the compressed state. The driving time is as described above.

Similarly, the movable suction device 4a also intermittently repeats the suction standby state and the suction state. The starting point (e) from the ascending standby state to the descending state is completed by the time B, and the suction timing (f) is A.
After that, the rising start time (g) is from B to C and the rising waiting time (h) is completed by D.

Next, a method for manufacturing the thermoformable composite material of the present invention will be described using the apparatus having the above configuration.

The mat-like material obtained above is supplied to the supply unit 13 between the pair of transfer belts 1a and 1b shown in FIG. Both transfer belts 1
The mat-like material is transferred with the movement of a and 1b, and stops at the compression device 3. While the mat-like material is transferred to the compression device 3, the mat-like material is heated by the heating device 2. The heating temperature of the heating device 2 is preferably a temperature at which all of the thermoplastic resin of the mat-like material is melted, and for example, heating at a temperature 10 to 70 ° C. higher than the melting temperature of the thermoplastic resin is preferably 1 to 10 minutes. In addition, the mat-like material is transferred to the transfer device 1
It may be preheated before being supplied to.

In this way, the mat-like material in which the binder is in a molten state is compressed by the compression device 3 at a temperature equal to or higher than the melting temperature of the thermoplastic resin. By this compression, the binder is sufficiently impregnated between the fibers of the mat-like material. The temperature here is not lower than the melting temperature of the thermoplastic resin, and the compressive force is preferably 0.5 to 30 kg / cm ² . If the pressure is lower than the above range, impregnation of the resin will be insufficient, and if the pressure is higher than the above range, the inorganic fiber may be damaged by the pressure.

Next, the mat-like material is transferred to the suction device 4 as the transfer belts 1a and 1b move. And the transfer belt
When the 1a and 1b are stopped, the movable suction device 4a descends and its suction surface comes into contact with the upper surface of the upper transfer belt 1a to start suction, and the lower fixed suction device 4b also starts suction.
Next, as the movable suction device 4a rises, the upper transfer belt 1a is pulled upward, resulting in a pair of transfer belts.
The distance between 1a and 1b widens. Here, since the binder of the mat-like material is in a molten state and adheres to the inner surfaces of both transfer belts 1a and 1b, the thickness of the mat-like material increases as the distance between both transfer belts 1a and 1b increases. To be made.

After expanding the thickness of the mat-like object by a predetermined amount, both suction devices 4a,
While stopping the suction of 4b, the transfer belts 1a and 1b are moved to cool the transfer belts 1a and 1b and the mat-like material by the cooling device 5. By cooling the transfer belts 1a and 1b, the binder of the mat-like material solidifies and does not adhere to the transfer belts 1a and 1b, and the solidified mat-like material can be peeled off from the transfer belts 1a and 1b. The thermoformable composite material is taken out.

In the obtained thermoformable composite material, the inorganic fibers are bonded to each other by a binder at the intersections thereof, have a large number of voids throughout the mat-like material, and the interior of the mat-like material is internal. A large number of pores communicating with the voids are formed. This thermoformable composite material has good heat shapeability, and can be easily formed into a desired shape by a simple processing means such as a press, thereby obtaining a formed body having a curvature that closely follows the curvature of the mold. You can The thickness of the thermoformable composite material may be appropriately determined depending on the application, but is generally 4 to 200 mm, and particularly preferably 4 to 12 mm when used as a ceiling material for automobiles.

(Example) Hereinafter, the present invention will be described in detail based on examples.

Example The mat-like material and apparatus shown below were used.

Matte: Glass fiber (diameter 11 μm, length 50 mm) and polypropylene fiber (diameter 18 μm, length 50 mm, melting point 165)
℃) is supplied to the card machine at a weight ratio of 4: 1 and defibration,
The fibers were mixed and needle punched (20 places / cm ² ) to make a mat (thickness 8 mm, width 1800 mm). The density of this mat is 0.5 g / cm ² , of which the density of glass fiber is 0.4 g / c.
The density of m ² and PP fiber was 0.1 g / cm ² . Next, a 110 μm thick polyethylene film (melting point 1
35 ° C.) was laminated on each to obtain a mat-like material.

Heating device: a hot-air oven heated to 220 ° C., which heated the transfer belt and the mat-shaped material sandwiched between the transfer belts.

Transfer belt: A glass cloth with polytetrafluoroethylene (trade name "Teflon": registered trademark) baked (manufactured by Chukoh Kasei Co., Ltd., P2000 mm) was used.

Compressor: Both movable and fixed presses are made of iron and are formed into a flat plate with a width of 1900 mm and a length of 1500 mm. 20
Heated to 0 ° C. The movable press is configured to be lifted and lowered by hydraulic pressure, and when it is lowered, the pressure is 2 Kg / cm ² (57 to
Pressurized in n).

Suction device: The main body is shaped like a rectangular parallelepiped, and the suction surface that contacts the transfer belt has one ventilation hole with a diameter of 3 mm per 1 cm ^2.
Individually provided, the main body is sucked by a vacuum pump to suck the main body.

Cooling device: Air-cooled (outside temperature 25 ° C).

Next, a method for producing a thermoformable composite material using the above mat-like material and apparatus will be specifically described.

The mat-shaped material is supplied between a pair of transfer belts, and the mat-shaped material is sandwiched between the transfer belts so that the transfer belt is 1.4 m.
The mat was moved to the compression device.
The time required to move is 90 seconds, and the mat-like material is almost 200
Had reached ℃. Next, the transfer belt was stopped for 5 seconds. While the transfer belt was stopped, the movable press was lowered to compress the mat-like material for 3 seconds. It took one second to vertically move the transfer belt.

Next, the transfer belt was moved by 1.4 m to transfer the mat-like material to the location of the suction device, and the movable suction device was lowered to be adsorbed to the outer surface of the upper transfer belt. 1 movable suction device
It descended in seconds and contacted the transfer belt for 1 second. After that, it took 2 seconds to rise until the thickness of the mat-like material reached 7 mm. Then, the suction force was weakened by supplying air to the main body of the suction device in 1 second (total 5 seconds). Next, transfer belt
After moving for 1.4 m and stopping again, the above operation was repeated.

In this way, a strip-shaped thermoformable composite material was continuously produced. The resulting thermoformable composite material had a width of 1800 mm and a length of 1400 mm. The thickness of the thermoformable composite material was 7 mm, the density was 0.1 g / cm, and the porosity was 93%. When the thickness variation was measured with a caliper, it was 2
The measured values at 0 point were all included in the range of 6.6 to 7.2 mm.

Comparative Example A mat-like material similar to that of the example was supplied to a press and heated at 220 ° C.
After being heated and compressed to 25 ° C., a composite material having a thickness of about 0.4 mm was obtained. This cooling press is 1900 × 1400mm, pressure
It was 3 Kg / cm ² . Next, this was heated to 200 ° C. for press molding, and a thermoformable composite material having an increased thickness was obtained. When the thickness of thermoformable composite material was measured at 20 points, the maximum was 5.3 mm and the minimum was 3.1 mm.
The average thickness at 20 points was 4.4 mm. The thermoformable composite material had a density of 0.16 g / cm ³ and a porosity of 89%.

As described above, it was confirmed that the thermoformable composite material of the present invention has a constant product thickness and little variation.

(Effects of the Invention) As described above, according to the present invention, since the mat-like material in the molten state of the thermoplastic resin is forcibly expanded by the suction device, a thermoformable composite material having a high porosity can be obtained. While you can
Since the thickness is regulated to the extent that the suction device is expanded, it is possible to continuously obtain a thermoformable composite material having a small variation in thickness.

The obtained thermoformable composite material has sufficient strength and heat resistance because the inorganic fibers are partially bonded by the thermoplastic resin binder, and achieves a higher porosity than conventional ones. Moreover, the weight can be further reduced.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus used in the present invention, FIG. 2 is a schematic view of a suction device portion of the apparatus, and FIG. 3 is a timing chart of the apparatus. 1 ... Transfer device, 1a, 1b ... Transfer belt, 2 ... Heating device, 3 ... Compressor, 3a ... Movable press, 3b ... Fixed press, 4 ... Suction device, 4a ... Movable suction device , 4b ... Fixed suction device.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display area B29L 7:00

Claims (1)

[Claims] 1. A thermoplastic resin containing a thermoplastic resin as a main component between a pair of transfer belts which are formed of a member having a property of adhering in a molten state and peeling in a solid state, and intermittently moving and stopping. A step of supplying a mat-like material having a binder and inorganic fibers to heat the thermoplastic resin to a temperature equal to or higher than the melting point of the thermoplastic resin, and separating the transfer belt from the transfer belt while the transfer belt is moving, and both transfer belts when the transfer belt is stopped. A step of compressing the mat-like material by compressing the stopped transfer belt from both outer surfaces thereof with a compression device for compressing the transfer belt from the outside, and a step of compressing the transfer belt in front of the transfer device in the transfer direction of the transfer belt. While the transfer belt is stopped, the pair of suction devices disposed on the outside are respectively adsorbed on both outer surfaces of the pair of compressed transfer belts to widen the gap between the pair of suction devices to transfer the pair of transfer devices. The steps of stopping suction after expanding the distance between the belts and releasing suction of the transfer belt by the suction device, and cooling the transfer belt to separate the mat-like material from the inner surfaces of both transfer belts are included. Method for producing thermoformable composite material.