JPH0891164A - Manufacture of air bag housing module cover - Google Patents

Abstract

PURPOSE: To provide a manufacturing method of an air bag housing module cover by which a filler is uniformly dispersed in a molding module cover and can be continuously molded under accurate and stable material supply without requiring preliminary kneading and palletization by an extruder. CONSTITUTION: This is related to a manufacturing method of an air bag housing module cover having a tear line composed of at least thermoplastic resin or thermoplastic elastomer and a filler. From at least two or more supply devices 33 and 34, at least the filler among molding materials of thermoplastic resin or thermoplastic elastomer and a filler is quantitatively inputted to an injection molding machine 31 having a screw 35 in a heating cylinder 32 through a regulating member having plural holes or notch parts to regulate a passing quantity of the molding materials on the material discharge side of a material supply passage 44 in which a feed screw 45 is inserted, and is melted, kneaded and plasticized in the heating cylinder 32, and is injected into metal molds 1 and 2, and is directly molded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pad cover used for an airbag device for protecting an occupant mounted on a steering wheel of a driver's seat, an instrument panel of a passenger's seat, a door trim, etc. of a vehicle such as an automobile. The present invention relates to a module cover for storing an airbag, which is characterized in that a composite material composed of a thermoplastic resin or a thermoplastic elastomer and a filler is directly molded without pre-kneading with an extruder or the like. The present invention relates to a method of manufacturing a module cover for storing an airbag.

[0002]

2. Description of the Related Art A steering wheel of a vehicle such as an automobile, an instrument panel of a passenger seat, for protecting an occupant,
Airbag devices attached to door trims and the like have been widely put into practical use. In general, an airbag device inflates an airbag composed of a bag when an unexpected impact or a sudden deceleration occurs on a vehicle and cushions the impact with an occupant and a body part to which the airbag is attached. To form between. An airbag device is generally configured as an in-vehicle unit called an airbag module or an airbag unit, and is used as an inflator (gas generator) that generates relatively high-pressure gas and the device in a folded state. An airbag housed inside and a module cover facing the vehicle compartment are provided (see, for example, Japanese Examined Patent Publication No. 61-44708, Japanese Unexamined Patent Publication No. 3-167045, and Japanese Utility Model Laid-Open No. 2-91051). .

The module cover is generally referred to as a pad cover, a storage pad, a lid, a cover door, a deployment door or the like, and usually functions as a case for accommodating an airbag, a housing or a cushioning material to prevent collision or the like. In the event of an abnormality, the airbag is inflated to relatively easily tear and deploy, thereby ensuring a rapid and smooth inflation of the airbag. To ensure a reliable and rapid tearing and unfolding of the module cover, a tear portion or tear line that facilitates relatively easy tearing of the module cover is provided at a predetermined portion of the module cover. The tear line is generally formed by forming a slit or groove for cleavage on the back surface of the module cover and locally thinning a part of the module cover. A conventionally known module cover for accommodating an air bag, which uses urethane foam having a three-layer structure in which a reinforcing material such as a net or a base cloth is embedded as an insert material, a skin layer of a soft resin and a core layer of a hard resin. There is a two-layer structure in which and are integrally injection-molded. As such a module cover, for example, in JP-A-1-202550,
A module cover in which a skin layer made of a soft resin and a core layer made of a hard resin are integrally injection-molded by a two-color molding method and a tear line is formed in the core layer is disclosed. However, in the urethane foam airbag module cover, it takes time and difficulty to embed the reinforcing material at a desired position, so that not only the productivity is low, but also the reinforcing material is embedded at a desired position. There was a problem that the non-defective rate of the air bag module cover was low. In addition, in manufacturing the module cover for storing the airbag by the two-color molding method, there is a problem that molding takes time and molds for the skin layer and the core layer are required, resulting in high manufacturing cost. .

Recently, a single-layer injection molding module cover using an ester-based thermoplastic elastomer or an olefin-based thermoplastic elastomer is also known. When manufacturing these module covers by injection molding,
It was necessary to form a thin tear line having a thickness of 0.4 to 1.4 mm, which promotes the cleavage, in the central portion and side portions of the top surface of the module cover, usually in an H-shaped pattern. An example of such a device is shown in FIG.
To briefly explain this, an airbag device attached to a steering wheel or the like is
And the gas generator 21 and the like are housed in the module cover 2
The second side wall 23 is attached and fixed to the attachment portion 25 of the base plate 24 by rivets or screws. A tear line 26 is provided at the center and side of the top surface of the module cover 22 to promote tearing when the airbag is activated. In addition, 27 is an airbag 20.
Is a ring-shaped retainer for fixing the to the base plate 24.

[0005]

By the way, in the above-described air bag device using the module cover, the time required for the air bag to be fully deployed at a low temperature such as in winter is completely different from that at a normal temperature in other seasons. It has been pointed out that it will be significantly delayed compared to the deployment time. The inventors of the present invention have conducted extensive studies on the complete deployment time of the injection-molding type air bag storage module cover, which is relatively easy to manufacture. As a result, the cause is that the gas generation rate of the inflator is low at low temperatures. However, the tear line part is composed mainly of a soft resin consisting of urethane foam or olefinic thermoplastic elastomer, so that the material strength of the material itself that constitutes the module cover increases. As a result, the strength of the tear line portion is increased and the strength of the tear line portion is easily affected by the temperature, and as a result, it has been found that the influence of the factor that it takes time to cleave at a low temperature is very strong. As a result of further earnest studies, the inventors of the present invention have found that at least a cleavage portion of a module cover made of a thermoplastic resin or a thermoplastic elastomer and a filler has an average particle size of 1
By using a module cover made of a thermoplastic resin or a thermoplastic elastomer containing 1 to 50% by volume of a filler of 00 μm or less, rapid and reliable cleavage and expansion are possible regardless of changes in environmental temperature, and occupant protection performance We have completed an airbag device that stabilizes the vehicle.

The module cover used in the airbag device of the present invention only needs to satisfy the above conditions and does not depend on a one-layer structure, a two-layer structure or the like. In order to obtain the module cover, a method has been used in which a thermoplastic resin or a thermoplastic elastomer and a filler are preliminarily melted, kneaded, pelletized by an extruder or the like and injection-molded in a mold. FIG. 5 shows a mold for a module cover formed by such injection molding. Briefly explaining with FIG. 4, the upper surface of the inner mold 1 is formed inside the top surface of the module cover 22. Tear line forming protrusions 1A for forming the tear line 26 such as an H pattern are formed. The outer mold 2 is provided outside the inner mold 1 with a gap of the thickness of the module cover 22.
Is placed in the space 9 formed by the core 3 on the outer surface of the inner mold 1 and the cavity 4 on the inner surface of the outer mold 2, and the thermoplastic resin or thermoplastic elastomer and the filler are preliminarily melted by the extruder or the like. The molten and kneaded and pelletized molten resin 6 is injection molded through the injection gate 5. F
Reference numeral 1 shows the flow of the molten resin.

However, in such a method of preliminarily melting, kneading and pelletizing the thermoplastic resin or thermoplastic elastomer and the filler, the thermoplastic resin or thermoplastic elastomer is subjected to heat history by the extruder,
Since heat history is again received by injection molding, strength reduction is caused by a decrease in molecular weight of the thermoplastic resin or the thermoplastic elastomer, particularly the urethane-based, polyamide-based, polyester-based thermoplastic resin or the thermoplastic elastomer. As a result, the extruder has no heat history, and the filler is uniformly dispersed in the module cover for rapid and reliable opening and deployment of the airbag that is not affected by the temperature environment. From the point of view, there has been a strong demand for a manufacturing method that enables continuous injection molding. Further, from the viewpoint of energy saving, it has been desired to eliminate the extrusion process economically.

However, in the usual injection molding, the material can be stored in the hopper, but in the manufacture of this module cover, the diameter is 1.5 to 2.5 mm and the height is 4.5 to 5.5 mm. Columnar or diameter 1.5-2.
A thermoplastic elastomer pellet having a spherical shape of 5 mm and a specific gravity of about 0.9 to 1.1 and an average particle diameter of several μm to several hundred μ
Since the fillers of m, having a specific gravity of 0.2 to 5.0 are significantly different in size, shape and specific gravity, even if they are weighed, mixed and stored in the hopper in advance, the materials are separated from each other and gradually. Since the mixing ratio changes, there is a problem that continuous injection molding cannot be performed while supplying the material accurately and stably. Therefore, the present invention, as described above, solves various problems in the method for producing a module cover having a tear line that promotes cleavage, pre-kneading by an extruder, without requiring pelletization, Provided is a method for manufacturing an airbag-containing module cover, in which a filler is uniformly dispersed in the module cover and can be continuously molded under a reliable and stable supply of a material.

[0009]

For this reason, as a result of intensive studies, in a method of manufacturing a module cover for accommodating an air bag made of a thermoplastic resin or a thermoplastic elastomer and a filler, an injection molding machine is provided between plasticizing steps. The thermoplastic resin or the thermoplastic elastomer and the filler are quantitatively charged from each hopper from the hopper opening at the rear of the heating cylinder in, and melt-kneaded and plasticized,
A thermoplastic resin or a thermoplastic elastomer can be injected directly into the mold by molding or by a single hopper from the hopper opening at the rear of the heating cylinder, and the A single supply device, for example, a vent-type injection molding machine, is used to quantitatively inject a filler, melt-knead, plasticize, and inject directly into a mold for direct molding to ensure accurate and stable supply of materials. In addition, it is found that the module cover for storing the air bag in which the filler is uniformly dispersed can be continuously molded, and in the present invention, as a means for solving the above problems, at least a thermoplastic resin or a thermoplastic elastomer and a filler are formed. In the method for manufacturing a module cover for storing an airbag provided with a tear line, at least two or more supplies are provided. A plurality of holes or notches for regulating the amount of the molding material passing through at least the filler out of the molding material of the thermoplastic resin or the thermoplastic elastomer and the filler on the material discharge side of the material supply passage in which the feed screw is inserted. It was put into an injection molding machine in which a screw was placed in a heating cylinder through a regulating member having a constant amount, melt-kneaded in the heating cylinder, plasticized, and injected into a mold for direct molding. It is characterized by.
And the present invention, in the measurement plasticizing step of injection molding,
It is characterized in that the supply device is operated by interlocking with the rotation of the screw of the main body of the injection molding machine to perform molding.
In addition, the present invention is characterized in that one of the supply devices is installed in an opening provided in a part of a heating cylinder of an injection molding machine main body, and the filler is quantitatively supplied and molded, In the above, the thermoplastic resin or the thermoplastic elastomer is completely melted.

[0010]

According to the present invention, with the above-described structure, the injection of the thermoplastic resin or the thermoplastic elastomer is started from the supply device 33 installed in the hopper port 32A provided at the rear part of the injection molding machine, and the middle of the injection molding machine is started. 32B (for example, a vent port of a vent type injection molding machine) provided in the section
From the supply device 34 installed in the filler (for example, a glass balloon). During the plasticizing and metering process of the injection molding, that is, the screw 35 of the main body of the injection molding machine is rotated, the thermoplastic resin or the thermoplastic elastomer is transferred to the tip of the heating cylinder 32 while being plasticized, and a constant amount is measured. Then, when the charging of the thermoplastic resin or the thermoplastic elastomer and the filler is started, and each of them is quantitatively charged at a constant ratio, the material is discharged from the material supply passage 44 in which the feed screw 45 is inserted. Since the regulating member 50 having a plurality of holes 51 or notches for regulating the passing amount of the molding material delivered from the feed screw 45 is provided on the side, the filler in various forms is supplied in a lump. However, the particles are dispersed uniformly and moderately, and the supply control is performed accurately and stably, so that the filler is uniformly mixed in the molded product. Further, when the opening 32B provided in the substantially middle portion of the heating cylinder is introduced, since the thermoplastic resin or the thermoplastic elastomer is sufficiently melted in the opening 32B, the shape destruction of the filler is suppressed. In addition, as a charging method, it is preferable to start at the same time and end at the same time, but the method is not limited to this. Subsequent molding steps are carried out in the same manner as ordinary injection molding, and a module cover in which a filler is uniformly blended with a thermoplastic resin or a thermoplastic elastomer is continuously obtained. In another embodiment of the present invention, the thermoplastic resin or the thermoplastic elastomer and the filler are charged through a hopper port 42A provided at the rear portion of the heating cylinder 32. Basically, the first material supply part 33A into which the thermoplastic resin or the thermoplastic elastomer is charged is the hopper port 42A.
And the discharge side of the second material supply section 34A in which the filler is charged is joined and connected to the upper part of the discharge side of the first material supply section 33A. In the present embodiment as well, since the second material supply unit 34A into which the filler is charged is provided with the regulating member, the particles are dispersed evenly and moderately and the supply control is performed accurately and stably, and the filler is added to the molded product. Blended evenly. In this way, the plasticizing and injection process of injection molding, that is, the screw 35 of the injection molding machine body rotates,
The resin material is transferred to the tip of the heating cylinder 32 while being plasticized. The subsequent molding steps can be carried out in the same manner as in ordinary injection molding, and the module cover in which the filler is uniformly blended with the thermoplastic resin or the thermoplastic elastomer is continuously obtained, which is the same as the above-mentioned embodiment. In this way, the module cover of the present invention does not undergo the preliminary melt-kneading step using an extruder, so there is no need to pelletize the resin material, and damage due to heat history can be minimized, It is economically advantageous, and the dispersibility of the filler in the thermoplastic resin or thermoplastic elastomer is uniform and good, and it is fast and surely cleaved in a wide temperature environment from low temperature to high temperature regardless of the temperature environment. A deployable airbag cover module cover is provided.

[0011]

EXAMPLES Examples of the present invention will be described below. (1) Thermoplastic resin or thermoplastic elastomer. The thermoplastic resin or thermoplastic elastomer used in the present invention is not particularly limited as long as it can be used in the range of -40 to 90 ° C, but the shore indentation hardness 55D which is good as a touch for the interior of the passenger compartment is 55D. The following are preferred. Mainly urethane-based elastomers containing urethane as a main component, styrene-based elastomers containing styrene as a main component or hydrogenated products thereof, vinyl chloride-based elastomers containing vinyl chloride as a main component, ester-based elastomers containing polyester as a main component, and polyamide. One type of elastomer or a mixture of two or more types of elastomers selected from the group consisting of a polyamide-based elastomer containing as a component, an olefin-based elastomer containing polyethylene, polypropylene or the like as a main component can be mentioned. Further, as the thermoplastic resin, nylon 11, nylon 12, nylon 6/12, ABS (acrylonitrile butadiene styrene), etc. are preferably used. Also,
You may mix and use these thermoplastic elastomers and thermoplastic resins in an appropriate ratio. As the urethane elastomer, ether type, ester type and polycarbonate type are preferably used. In the present invention, the thermoplastic resin or the thermoplastic elastomer, if necessary,
Various additives such as a flame retardant, an antioxidant, an antistatic agent, a colorant, an ultraviolet absorber, a plasticizer and a foaming agent can be added. Examples of the flame retardant include inorganic flame retardants such as antimony trioxide, aluminum hydroxide, magnesium hydroxide, antimony pentoxide, and zirconium oxide, phosphoric acid ester flame retardants, and phosphoric acid flame retardants such as halogen-containing phosphoric acid ester flame retardants. Examples of the flame retardant include bromine flame retardants, chlorinated paraffin, and chlorine flame retardants such as perchlorocyclodecane. Antioxidants include light stabilizers, metal deactivators, chain initiation inhibitors such as antiozonants, phenolic antioxidants, radical scavengers such as amine antioxidants, sulfur antioxidants, phosphorus. Examples thereof include peroxide decomposers such as system antioxidants. Examples of the antistatic agent include various surfactants and polymers having a functional group. As the colorant, any of pigments and dyes can be used, and as the pigment, azo organic pigments such as poorly soluble azo lakes, phthalocyanine organic pigments such as phthalocyanine blue, and anthraquinone-based slene organic pigments, basic pigments Dye-based dyeing lake organic pigments, other organic pigments, titanium-based oxide inorganic pigments, chromic molybdate-based inorganic pigments such as yellow lead, sulfides such as cadmium yellow, selenide-based inorganic pigments, Examples include ferrocyan-based inorganic pigments such as dark blue and other inorganic pigments, and usable dyes include azo-based, anthraquinone-based, quinophthalone-based oil-soluble dyes and water-soluble dyes. Examples of the ultraviolet absorber include salicylate-based, benzophenone-based, benzotriazole-based, cyanoacrylate-based, and nickel chelate-based ultraviolet absorbers. Examples of the plasticizer include phthalic acid plasticizers, fatty acid plasticizers, phosphoric acid plasticizers, adipic acid plasticizers, polyester plasticizers, and epoxy plasticizers.

(2) Filler. The filler used in the present invention has an average particle size of 10
There is no particular limitation as long as it is 0 μm or less, but calcium carbonate (heavy calcium carbonate, chalk, chalk), aluminum silicate (carion clay, wax stone clay), magnesium silicate (talc), silica (silica sand, Diatomaceous earth, amorphous silica, wet white carbon, dry white carbon), basic magnesium carbonate, aluminum hydroxide (alumina hydrate), precipitated barium sulfate, zinc oxide, aluminum oxide, carbon black, mica,
Glass sphere, wood powder, recycled rubber, Evo powder, modified melamine resin, glass fiber, milled fiber, carbon fiber, specific gravity 1
The following lightweight fillers (glass balloons, shirasu balloons, fly ash balloons, pearlite balloons, silica balloons and other silicic acid type inorganic balloons, non-silicic acid type inorganic balloons, thermosetting organic balloons, thermoplastic organic balloons) and the like can be mentioned. . Among them, glass spheres, which are smooth and uniform, and whose particle surface easily wets, and lightweight fillers having a specific gravity of 1 or less are preferable. Further, among these fillers, a lightweight filler having a true specific gravity of 1 or less, which has an effect of reducing the specific gravity of the compound, is preferable. Further, among these lightweight fillers, glass balloons having an excellent effect of reducing specific gravity and excellent pressure resistance are most preferable. Furthermore, the true specific gravity is 0.28 to 0.7
A glass balloon having a porosity of the particle surface of 0, a smooth and uniform particle surface, and a particle surface which is easily wetted can be most preferably used. If the true specific gravity is less than 0.28,
The pressure resistance of glass balloons is often less than 50 kgf / cm ^2, and when melt-kneading with a thermoplastic resin or a thermoplastic elastomer, the glass balloon is destroyed in the process and the specific gravity of the module cover for storing the airbag is increased. Is high, which is not preferable, while the true specific gravity is 0.7
If it exceeds 0, the effect of reducing the specific gravity of the airbag-covering module cover is not always sufficient. The average particle diameter of the filler is preferably 100 μm or less. If the average particle diameter exceeds 100 μm, the surface of the module cover, particularly the surface of the tear line portion that is a thin portion becomes uneven, which is not preferable in appearance. As the compounding amount of the filler, it is necessary that the compounding amount in the thermoplastic resin or the thermoplastic elastomer is 1 to 50% by volume based on the entire compound. Below 1% by volume, if an airbag device is used,
The complete development time at 40 ° C is slower than at room temperature (room temperature), and the effect of rapid cleavage expansion is not sufficient.
When the content is more than the volume%, the tensile strength of the compound is too low to be practical.

(3) Coating. The surface of the module cover can be painted to improve texture and durability. As the paint, it is preferable to use urethane-based paint.

(4) Method of manufacturing module cover. In the embodiment of the present invention, as shown in FIG. 1, the injection molding machine includes an injection device 31 and molds 1 and 2, and the injection device 31 includes a heating cylinder 32 into which a screw 35 is inserted. An injection nozzle 36 is provided at the front end of the heating cylinder 32, and a screw drive device 37 for rotating and advancing the screw 35 is provided at the rear end. Reference numeral 48 indicates a drive motor for rotating the screw. A first material supply unit 33, which is a supply device for supplying a thermoplastic resin or a thermoplastic elastomer, which is a first molding material, is provided at the rear of the heating cylinder 32.
In the material supply part 33, a hopper 38 for accommodating pellets of the first thermoplastic resin or thermoplastic elastomer, a horizontal transfer path 39 communicating with a drop port of the hopper 38, and a horizontal transfer path 39 are provided. Feed screw 40
A drive motor unit 41 for rotating the feed screw 40, and a vertical drop path 42 communicating with the tip of the horizontal transfer path 39 and communicating with the inside of the heating cylinder 32 are provided. By this, the horizontal transfer path 3 from the hopper 38
The first thermoplastic resin or thermoplastic elastomer that has dropped to 9 is transferred by the feed screw 40 that is rotated by the drive motor unit 41, drops in the vertical drop path 42, and is supplied into the heating cylinder 32. At this time, if the rotation speed of the drive motor unit 41 is controlled,
The supply amount of the first thermoplastic resin or the thermoplastic elastomer can be variably controlled. On the other hand, an opening 32B which constitutes, for example, a vent port of a vent type injection molding apparatus is provided at an intermediate portion of the heating cylinder 32, preferably at a substantially central portion, and is a supply device for supplying a filler which is a second molding material. The second material supply unit 34 is installed. The second material supply unit 34 has the same configuration as the first material supply unit 33, a hopper 43, a horizontal transfer path 44, a feed screw 45, a drive motor unit 46, and a vertical drop path 47.

In the embodiment of the present invention, as shown in FIG.
In order to supply the filler to the heating cylinder 32 at least accurately and stably, the following configuration is adopted. As shown in detail in FIG. 2 (A), in the case where a glass balloon that is a filler Ma is used in the second material supply unit 34, the glass balloon has an internal hollow with a diameter of about 0.03 to 0.06 mm. It is a granular sphere of and has a function of reducing the weight of a molded product. On the other hand, the support mechanism 52 having the restriction member 50 and the closing member 49 are attached to the device block 34A. The closing member 49 has the mounting hole 5
3 is inserted into the horizontal transfer path 44 for supplying the material, and the support mechanism 52 is attached to the attachment hole 53 and attached to the device block 34A by the fixing bolt. On this occasion,
The shaft of the feed screw 45 is inserted into the bearing portion of the support mechanism 52 and engaged with the rotation detection rod 54. Also,
The tip end of the regulating member 50 is brought into contact with the closing member 49, and in this state, the closing member 49 is fixed by a fixing bolt to the device block 34.
Fix to A.

In another embodiment of the present invention, as shown in FIG. 3, the thermoplastic resin or the thermoplastic elastomer and the filler are charged through a hopper port 42A provided at the rear portion of the heating cylinder 32. A first material supply part 33A into which a thermoplastic resin or a thermoplastic elastomer is added is installed in the hopper port 42A, and a second material supply part 3 into which a filler is added to the upper part of the discharge side of the first material supply part 33A.
The discharge side of 4A is joined and connected. A hopper 38A into which a thermoplastic resin or a thermoplastic elastomer is charged is supplied to the first material supply section 33A, and a second material supply section 34 is provided.
Each A is provided with a hopper 43A into which a filler is put. In this embodiment as well, although not described in detail, as in the above-described embodiment, since the second material supply unit 34A into which the filler is charged is provided with the regulating member 50, the filler particles are dispersed evenly and appropriately. Stable supply control is performed and the filler is uniformly mixed in the molded product. Thus, the plasticizing and metering process of injection molding, that is, the screw 35 of the injection molding machine body rotates, and the resin material is transferred to the tip of the heating cylinder 32 while plasticizing. The subsequent molding steps can be carried out in the same manner as in ordinary injection molding, and the module cover in which the filler is uniformly mixed with the thermoplastic resin or the thermoplastic elastomer is continuously obtained, which is the same as the above-mentioned embodiment.

With the above construction, when the feed screw 45 is rotated by the drive motor unit 46, the filler Ma supplied from the hopper 43 is transferred by the feed screw 45. At this time, the filler Ma is the same as in FIG.
Since it moves through a plurality of holes (notches) 51 provided in the regulation member 50 as shown in FIG.
The passing amount of the filler Ma that passes through is regulated and limited by the size and number of the holes 51. Further, the gap S between the feed screw 45 and the horizontal transfer path 44 is closed by the closing member 4
Since it is blocked by 9, there is no problem that the filler Ma passes through the gap S and directly flows down to the heating cylinder 32 side.
In addition, the thermoplastic resin or the thermoplastic elastomer is the first
The material is supplied from the material supply unit 33 into the heating cylinder 32. Thus, on the material discharge side of the material supply path in which the feed screw is inserted, a regulating member having a plurality of holes or notches for regulating the passage amount of the molding material delivered from the feed screw is provided, so that various forms of filler can be used. On the other hand, since accurate and stable supply control can be performed, the plasticizing and metering process of the injection molding, that is, the screw 35 of the injection molding machine main body is rotated from the two supply devices 33 and 34 installed at the hopper mouth of the injection molding machine. , The resin material is transferred to the tip of the nozzle 36 while being plasticized, and during the process of measuring a fixed amount, the introduction of the thermoplastic resin or the thermoplastic elastomer and the filler are simultaneously started, and each of them is quantitatively fixed at a fixed ratio. Throw in,
Turn on at the same time. Subsequent molding steps can be carried out in the same manner as ordinary injection molding, and a module cover in which a filler is uniformly blended with a thermoplastic resin or a thermoplastic elastomer can be continuously obtained under a reliable and stable material supply. It will be. Further, when a screw having a dullage structure, a subflight structure, or a multi-row structure at a part of the screw 35 of the main body of the injection molding machine, in particular, at the tip end is used, the uniformity of mixing is further improved.

Further, in the present invention, in the metering plasticizing step of injection molding, the above-mentioned feeding device is operated by interlocking with the rotation of the screw of the main body of the injection molding machine to perform molding, that is, the feeding amount of each material in the feeding device is Since it depends on the rotation speed of the feed screw of the feeding device, it is properly controlled according to the type of material that feeds it, and the screw rotation of the injection molding machine body, that is, the progress of plasticization of the material in the heating cylinder. It operates in conjunction with this depending on the condition.

Further, according to the present invention, one of the above-mentioned feeding devices is installed in an opening provided in substantially the middle part of the heating cylinder of the main body of the injection molding machine, and only the filler is quantitatively fed from the feeding device to perform molding. By the rotation of the screw in the heating cylinder, the thermoplastic resin or the thermoplastic elastomer material charged from another supply device is plasticized and seems to be completely melted by the time it reaches the opening. It is composed of. Then, the filler is uniformly blended in the thermoplastic resin or the thermoplastic elastomer material by the rotation of the screw in the heating cylinder, downstream of the feeder into which the filler is charged. As described above, the module cover of the present invention does not go through the preliminary melt-kneading step using an extruder, so damage due to heat history can be minimized, which is economically advantageous, and the filler The dispersibility in a thermoplastic resin or a thermoplastic elastomer is uniform and good, and the module cover for accommodating an airbag can be rapidly and surely cleaved and deployed without being influenced by the temperature environment.

The dispersibility and shape destruction rate of the lightweight filler were determined by the following methods. As for dispersibility, 100 molded module covers are manufactured, each of them is visually inspected, and if there is even one dispersion failure in this one module cover, it is regarded as a defective product, and there is absolutely nothing. Good product. From this result, the total number of non-defective products checked is 10
The percentage of good products was obtained by dividing by 0 and multiplying by 100. Therefore, if the percentage value is 100, it means that there are no defective products. As for the shape destruction rate, 10 pieces were sampled from one predetermined manufactured module cover from different predetermined locations, the specific gravities of the respective pieces were measured, and the average value of the measured values was obtained. On the other hand, when the shapes of the thermoplastic elastomer and the lightweight filler do not break, and the specific gravity at the time of breaking is known, and since the blending volume% of the lightweight filler to the thermoplastic elastomer is also known, for example, the lightweight filler The calculated specific gravity of the manufactured product when the shape of is not destroyed at all is required. From the results of these specific gravities, relative to the time when the blending volume% of the lightweight filler to the thermoplastic elastomer is regarded as 100 volume%,
The% shape break volume is calculated. The higher the volume% of shape destruction is, the more the shape destruction of the lightweight filler occurs.

[0021] <Comparative Example 1> Shore durometer 79A, a specific gravity of 1.09, tensile strength 290kgf / cm ² of urethane-based thermoplastic elastomer (ether) and a true specific gravity of 0.38, a glass of compression strength 281kgf / cm ² The balloon was charged into a twin-screw extruder at a heating cylinder temperature of 160 to 210 ° C. and a screw rotation speed of 100 rpm and melted and kneaded to prepare pellets. The temperature of the heating cylinder 32 is 180 ° C. to 200 ° C.
The structure of the rpm and the screw 45 is a general-purpose full flight structure, injection molding is performed at a maximum pressure of 80 kgf / cm ² , and a groove for tearing, that is, a tear line having a wall thickness of 0.6 mm is partially formed in a part thereof as shown in FIG. A module cover for accommodating an airbag having an overall top surface thickness of 4.0 mm (26 in FIG. 4) was molded. Furthermore, the surface was painted with urethane paint. At this time, the content of the glass balloon in the module cover for storing the airbag is 19% by volume.
Met. At this time, the specific gravity was 1.09, the dispersion rate of the glass balloon was 100%, and the shape destruction rate of the glass balloon was 30%, but the pelletization was performed by the twin-screw extruder, and thus the production efficiency was poor. .

<Comparative Example 2> A urethane type thermoplastic elastomer (ether type) having a Shore indentation hardness of 79 A, a specific gravity of 1.09 and a tensile strength of 290 kgf / cm ² was installed at a hopper mouth provided at the rear of the heating cylinder. A glass balloon having a true specific gravity of 0.38 and a compressive strength of 281 kgf / cm ² is heated from a supply device that does not have the regulating member 50 and the closing member 49 installed in the opening provided at the center of the heating cylinder. 180 between cylinder temperature hopper mouth and opening
~ 230 ° C, 220 ~ 230 ° between opening and nozzle
C. The above materials were directly charged in the injection molding machine during the measurement of the screw rotation speed of 50 rpm and the plasticizing process in synchronism with the operation of the screw, and continuous molding was performed. At this time, the elastomer was completely melted at the opening. Maximum pressure 80kg
An airbag having an overall top surface thickness of 4.0 mm, which is injection-molded at f / cm ² and has a cleavage groove or tear line having a thickness of 0.6 mm in a part thereof as shown in FIG. Molded storage module cover. Furthermore, the surface was painted with urethane paint. Since the glass balloon was supplied by the supply device without the regulating member 50, the glass balloon was solidified and charged, the kneading was insufficient, and the dispersibility of the module cover was 0%.

Example 1 A urethane thermoplastic elastomer (ether type) having a Shore indentation hardness of 79 A, a specific gravity of 1.09 and a tensile strength of 290 kgf / cm ² and a glass balloon having a true specific gravity of 0.38 were heated at a heating cylinder temperature of 180. ~ 20
Two feeding devices are installed in the hopper mouth provided at the rear part of the heating cylinder of the injection molding machine equipped with 0 ° C, full flight screw (general-purpose screw structure), and the screw rotation speed is 50 rpm, and the plasticizing process is performed. In the meantime, the material was directly charged quantitatively at a constant speed in conjunction with the operation of the screw, and continuously molded. Maximum pressure 80kgf / cm ²
5, the module cover for accommodating an air bag having an overall top surface thickness of 4.0 mm, which has a tear groove or tear line with a thickness of 0.6 mm in a part thereof as shown in FIG. Was molded. Furthermore, the surface was painted with urethane paint. At this time, the content of the glass balloon in the module cover for storing the airbag is 19
It was% by volume. At this time, the specific gravity is 1.01, the dispersion rate of the glass balloon is 100%, and the shape destruction rate of the glass balloon is 7%. When the tear line and the thick portion were visually observed by enlarging it 350 times with an electron microscope, the glass balloons were uniformly dispersed.

[0024] <Example 2> Shore durometer 79A, a specific gravity of 1.09, tensile strength 290kgf / cm ² of urethane-based thermoplastic elastomer (ether) and a true specific gravity of 0.38, a glass of compression strength 281kgf / cm ² The balloon is heated to a temperature of 180 to 200 ° C, and two supply devices are installed at the hopper mouth provided at the rear of the heating cylinder of the injection molding machine in which the screw having the dullage structure (multi-blade screw structure) is installed at the tip. Screw speed 50
During the measuring process of rpm and the plasticizing process, the above materials were directly charged quantitatively at a constant speed in synchronism with the operation of the screw, and continuously molded. Injection molding was carried out at a maximum pressure of 80 kgf / cm ² , and a part of it had a wall thickness of 0.
A module cover for accommodating an air bag having an overall top surface thickness of 4.0 mm having a cleavage groove of 6 mm, that is, a tear line, was molded. Furthermore, the surface was painted with urethane paint. At this time, the content of the glass balloon in the module cover for storing the airbag is 19% by volume.
Met. At this time, the specific gravity is 1.03, the dispersion rate of the glass balloon is 100%, and the shape destruction rate is 10%.
When the tear line and the thick portion were visually observed by enlarging it 350 times with an electron microscope, the glass balloons were uniformly dispersed.

<Embodiment 3> A urethane type thermoplastic elastomer (ether type) having a Shore indentation hardness of 79 A, a specific gravity of 1.09 and a tensile strength of 290 kgf / cm ² is installed at a hopper port provided at the rear of the heating cylinder. , A glass balloon having a true specific gravity of 0.38 and a compressive strength of 281 kgf / cm ² was installed in the opening provided in the central portion of the heating cylinder, and from the feeding device, the heating cylinder temperature between the hopper mouth and the opening was 1
80-230 ° C, 220-230 between opening and nozzle
° C, measuring the screw rotation speed of 50 rpm in the injection molding machine,
During the plasticizing step, the materials were directly charged quantitatively at a constant speed in synchronism with the operation of the screw, and continuously molded. At this time, the elastomer was completely melted at the opening. Injection-molded at a maximum pressure of 80 kgf / cm ² , and a part of it has a wall thickness of 0.6 m, as shown in FIG.
A module cover for accommodating an air bag having an overall top surface thickness of 4.0 mm having a groove for cleavage of m, that is, a tear line, was molded. Furthermore, the surface was painted with urethane paint. At this time, the content of the glass balloon in the airbag-covered module cover was 19% by volume. At this time, the specific gravity is 1.00, the dispersion rate of the glass balloon is 100%, and the shape destruction rate is 5%. When the tear line and the thick portion were visually observed by enlarging it 350 times with an electron microscope, the glass balloons were uniformly dispersed.

Example 4 An olefin thermoplastic elastomer having a Shore indentation hardness of 80 A, a specific gravity of 0.97, and a tensile strength of 117 kgf / cm ² was obtained from a feeder installed at a hopper port provided at the rear of the heating cylinder. From a supply device in which a glass balloon having a pressure resistance of 281 kgf / cm ² of 0.38 was installed in the opening provided in the center of the heating cylinder,
180-230 ° between the hopper mouth and the opening of the heating cylinder temperature
C, the temperature between the opening and the nozzle is 220 to 230 ° C, the screw rotation speed is 50 rpm in the injection molding machine, and the material is quantitatively operated at a constant speed in association with the operation of the screw during the plasticizing process. It was directly charged into the mold and continuously molded. At this time, the elastomer was completely melted at the opening. Injection molded at a maximum pressure of 80 kgf / cm ² , and as shown in FIG. 5, an overall top surface thickness having a cleavage groove or tear line with a wall thickness of 0.6 mm as shown in FIG.
A 0 mm air bag housing module cover was molded. Furthermore, the surface was painted with urethane paint.
At this time, the content of the glass balloon in the airbag-covered module cover was 12% by volume. The specific gravity at this time was 0.91, and the dispersion ratio of the glass balloon was 10
0%, shape destruction rate is 7%. 35 by electron microscope
When the tear line and the thick portion were visually observed by enlarging it to 0 times, the glass balloons were uniformly dispersed.

Although the respective embodiments have been described above, the rotation speed of the feed screw in each of the supply devices 33 and 34, the rotation speed of the screw 35 in the heating cylinder 32, and the rotation speed of the screw 35 and the feed screw in each of the supply devices. That is, the relationship with the supply amount of each thermoplastic resin or thermoplastic elastomer is appropriately selected depending on the feeding mode of the material into each supply device, the selected material, and the like. Further, within the scope of the present invention, thermoplastic resins or thermoplastic elastomers and fillers other than those exemplified above can also be used, and the shape, type and shape of the injection molding machine, that is, the shape of the mold, that is, the module cover for storing the airbag. Needless to say, an appropriate shape can be adopted.

[0028]

As described above in detail, according to the present invention, in the method of manufacturing a module cover for storing an air bag having a tear line that promotes cleavage, at least a thermoplastic resin or a thermoplastic elastomer and a filler are used. In the method of manufacturing a module cover for storing an airbag provided with a tear line, a material in which a feed screw is inserted from at least two or more supply devices, at least a filler among molding materials of the thermoplastic resin or the thermoplastic elastomer and the filler. The heating cylinder is quantitatively charged into an injection molding machine having a screw inside the heating cylinder through a regulation member having a plurality of holes or cutouts for regulating the amount of the molding material passed on the material discharge side of the supply passage. Since it was melt-kneaded and plasticized in the mold and injected into the mold to directly mold it, Relative filler condition is not made supplied it becomes loaf, so that the filler in the molded product is carried out accurately and stable supply control is Barasa to moderately particles uniformly is uniformly mixed. Also, when the filler is charged through the opening provided in the substantially middle portion of the heating cylinder,
Since the thermoplastic resin or the thermoplastic elastomer is sufficiently melted in the opening, the shape destruction of the filler is suppressed, and the filler is uniformly blended with the thermoplastic resin or the thermoplastic elastomer by the reliable and stable supply of the molding material. The obtained module covers are continuously obtained. As described above, in the method for manufacturing the airbag-cover module cover of the present invention, since the pre-melting and kneading step using the extruder is not performed, it is not necessary to pelletize the resin material, and damage due to thermal history is caused. It can be minimized, it is lightweight and economically advantageous, and the dispersibility of the filler in the thermoplastic resin or thermoplastic elastomer is uniform and good, regardless of the temperature environment, from low temperature to high temperature. (EN) Provided is a module cover for accommodating an air bag, which is capable of rapidly and reliably cleaving and expanding under a wide temperature environment.

[Brief description of drawings]

FIG. 1 is an overall view of an injection molding machine used in an embodiment of the present invention.

FIG. 2 is a detailed view of a second material supply unit in the injection molding machine of FIG.

FIG. 3 is an overall view of another embodiment of an injection molding machine used in the present invention.

FIG. 4 is an explanatory view of a module cover for storing an airbag.

FIG. 5 is a diagram showing how resin is extruded into a mold.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inner mold 1A Tearline forming protrusion 2 Outer mold 3 Core 4 Cavity 5 Injection gate 6 Molten resin 9 Molding space 20 Airbag 21 Gas generator 22 Module cover 23 Side wall 24 Base plate 25 Mounting part 26 Tearline 27 Retainer 31 Injection device 32 Heating cylinder 32A Hopper port 32B Opening 33 First material supply part 33A First material supply part 34 Second material supply part 34A Second material supply part 35 Screw 36 Injection nozzle 37 Screw drive device 38 Hopper 38A Hopper 39 Horizontal transfer path 40 Feed screw 41 Drive motor unit 42 Vertical drop path 42A Hopper mouth 43 Hopper 43A Hopper 44 Horizontal transfer path 45 Feed screw 46 Drive motor unit 47 Vertical drop path 49 Closing member 50 Restricting member Flow of first hole portion 52 supporting mechanism F molten resin

Front page continuation (72) Haruo Okada Inventor Haruo Nagano Pref., Shiroki-cho, Nanjo 2110, Nanjo, Nissei Plastic Industry Co., Ltd. In the company

Claims (4)

[Claims] 1. A method of manufacturing a module cover for storing an air bag, comprising a tear line made of at least a thermoplastic resin or a thermoplastic elastomer and a filler, wherein the thermoplastic resin or the thermoplastic elastomer is supplied from at least two or more supply devices. And at least a filler of the molding material of the filler, in the heating cylinder through a regulating member having a plurality of holes or notches for regulating the amount of passage of the molding material on the material discharge side of the material supply path into which the feed screw is inserted. A method for manufacturing an air bag storage module cover, which comprises quantitatively charging into an injection molding machine in which a screw is arranged, melt-kneading and plasticizing in a heating cylinder, and injecting into a mold to directly mold. 2. The module for storing an air bag according to claim 1, wherein in the measurement plasticizing step of injection molding, the supply device is molded by operating in synchronization with screw rotation of an injection molding machine body. Cover manufacturing method. 3. One of the supply devices is installed in an opening provided in a substantially middle part of a heating cylinder of an injection molding machine main body, and a filler is quantitatively supplied by the supply device to perform molding. The method of manufacturing a module cover for storing an airbag according to claim 1. 4. The method of manufacturing a module cover for accommodating an airbag according to claim 3, wherein the thermoplastic resin or the thermoplastic elastomer is completely melted in the opening.