JPH05104613A - Manufacture and device of bent blow molded product - Google Patents

Abstract

(57) [Summary] (Modified) [Objective] To provide a method capable of favorably manufacturing a flex blow molded product having a complicated shape and having a certain length. A suction device having a pair of molds 1 each having an opening at an upper end and a lower end and forming a bent cylindrical cavity 12, and a lower shutter mechanism 5 connected to a lower end of the mold 1. And a shutter mechanism provided on the upper end opening of the cavity 12 of the mold 1 and having a heated air supply port, the temperature of the mold is adjusted according to the melting point of the resin used for extrusion blow molding. The temperature of the cylindrical parison 8 is controlled by controlling the temperature to a suitable temperature, further blowing heated air of 80 ° C. or more into the cavity 12 from the heated air supply port, and sucking it from the lower end side of the mold 1 with a suction device. Is guided according to the bending of the cavity 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a bending blow-molded product and an apparatus used therefor, and more particularly to a method for manufacturing a bending blow-molded product having a complicated shape and having a certain length and an apparatus used therefor.

[0002]

2. Description of the Related Art Conventionally, a fuel tank of a vehicle is made of a metal such as a steel plate, but recently, the purpose is to reduce the weight of the vehicle and improve the space utilization rate. So, plastic fuel tanks have come into use.

On the other hand, in connection with tubes for connecting heaters for automobiles, radiators, etc., tubes for general-purpose air conditioners, pipes, etc., the usable space has been limited due to the recent demand for improvement of space utilization rate. , It has become necessary to process it into a rather complicated shape. Conventionally, such tubes and pipes having a complicated shape are manufactured by bending a straight metal pipe, and there is a problem that it takes time to make a complicated shape.

For this reason, the merits of easy workability and weight saving of plastics have been receiving more attention, and the above-mentioned various pipes, tubes, etc. are manufactured by blow molding. Further, in applications such as automobiles, heat resistance, heat resistance strength properties, etc. are important requirements, and therefore it is necessary to use a resin having a somewhat high melting point. However, when producing a pipe or the like having a complicated shape by blow molding, when a resin having a relatively low melting point such as polyolefin is used as a material resin, molding is possible, but a resin having a high melting point such as polyamide is used. When engineering plastics are used or when the content of inorganic fillers such as glass fiber is high, the cylindrical parison comes into contact with the mold during complicated bending and the resin temperature decreases, causing the parison to It becomes easy to solidify. For this reason, the parison solidifies and does not reach the end, or even if it reaches the end, the parison is insufficiently stretched and bursts, or the surface of the molded product is roughened. The problem is that it is difficult to manufacture things.

Therefore, various methods have been proposed in which an airflow flowing from the insertion hole of the parison of the mold to the opening at the lower end is generated so that the parison is smoothly guided (Japanese Patent Publication No. 58/58).
-47337, JP-A-61-287709, JP-A-61-287717,
JP-A-61-287718).

However, in each of the above-mentioned methods, the induction of the parison is smooth, and the curing of the parison due to contact with the mold is not remarkable, but especially when an engineering plastic having a high melting point such as polyamide is used, Since the parison is cooled by the sucked air, the parison is likely to be hardened while the cylindrical parison is being bent in a complicated manner, and the elongation tends to be poor during blow molding. Therefore, it is still difficult to manufacture a product having a length of 300 mm or more. Furthermore, since there is a large variation in the temperature distribution of the parison during stretching, the surface of the obtained molded product is rough and voids are likely to occur in the cross section. In addition, if a flange for sealing etc. is provided at the end of the pipe,
Depending on the temperature, viscosity, etc. of the resin, there are problems in that a smooth surface required for sealing may not be obtained, or the flange may not be formed properly.

[0007] Therefore, an object of the present invention is to provide a method capable of favorably producing a bend blow molded product having a complicated shape and having a certain length.

Another object of the present invention is to provide an apparatus for producing the above-mentioned bent blow-molded article.

[0009]

As a result of earnest research in view of the above objects, the present inventors have found that when manufacturing a bent pipe-shaped blow-molded product, it has openings at the upper end and the lower end, A pair of molds forming a cylindrical cavity, a suction device having a lower shutter mechanism connected to the lower end of the mold, and a heating air supply port provided on the upper end opening of the mold cavity. Using a device with a shutter mechanism having a, the temperature of the mold is controlled to an appropriate temperature according to the melting point of the resin used for extrusion blow molding, and heating air of 80 ° C or higher is further supplied from the heating air supply port. When the cylindrical parison is guided in accordance with the bending of the cavity by blowing into the cavity and sucking from the lower end side of the mold with a suction device, the resin component is not cured. Can be a parison complicated bent shape, it found that bending blow-molded article is obtained having good appearance and strength, and conceived the present invention.

That is, the method for producing a bend blow-molded article of the present invention comprises: (A) a pair of dies having openings at the upper end and the lower end to form a bent cylindrical cavity; (B) Extruded from the extruder by using the upper shutter mechanism provided on the upper opening of the cavity of No. 1 and having the heated air supply port and the suction device having the lower shutter mechanism connected to the lower end of the mold. The cylindrical parison that has been heated is introduced into the cavity of the mold heated to 120 to 200 ° C, and heated air of 80 ° C or higher is blown into the cavity from the upper shutter mechanism, (C) the lower end of the mold. By sucking the heated air from the opening side with a suction device, the cylindrical parison is guided according to the bending of the cavity, and (D) the tip of the cylindrical parison is more than the lower end opening. Now that protrudes by a required length, and closing the upper and lower shutters to seal the distal end portion of the parison, and performing blow molding blowing air into the (E) the parison.

Further, the manufacturing apparatus of the bending blow-molded product of the present invention used in the above method is (a) having an opening at the upper end and the lower end, forming a bent cylindrical cavity, and providing a heating device. A pair of built-in molds, (b) a heating air supply device having an upper shutter mechanism installed on the upper end opening of the cavity and having a heating air supply port, and (c) a cavity of the mold. And a suction device having a lower shutter mechanism connected to the lower end, the temperature of the mold is heated to 120 to 200 ° C. by the heating device, and the cylindrical parison extruded from the extruder is transferred to the mold. Into the cavity, blow heated air of 80 ° C. or higher into the cavity from the heated air supply port of the heated air supply device, and suck the heated air by the suction device at the lower end of the mold. According to the method, the cylindrical parison is guided in accordance with the bending of the cavity, the upper and lower shutters are closed, and then blow molding is performed.

The present invention will be described in detail below. The resin for blow molded articles to which the method of the present invention can be applied is not particularly limited, and polyolefins, polyamides, polycarbonates, polyesters (polyethylene terephthalate, polybutylene terephthalate, etc.), blends of polyphenylene oxide and polystyrene, etc. Can be used. The molded product made of these resins may be either a single resin or a composition composed of a combination of two or more kinds, and may be a single-layer molded product or a multi-layer molded product. .. It is particularly preferable for high melting point resins such as polyamide and resin compositions based on the same. For example, it is preferable when it is formed from a composition of polyamide and polyolefin in consideration of heat resistance and refrigerant resistance, such as a tube of a radiator of an automobile or the like.

As the polyolefin in the composition of the polyamide and the polyolefin, a homopolymer of α-olefin such as ethylene, propylene, butene-1, hexene-1, 4-methylpentene-1, ethylene and propylene or other Copolymers with α-olefins, or copolymers of two or more of these α-olefins, or homopolymers thereof, copolymers with each other, or blends of homopolymers and copolymers The thing etc. can be used. Further, the above polyolefin modified with an unsaturated carboxylic acid or an anhydride thereof can also be used. Of these, polypropylene is particularly preferable.

The above polypropylene is a crystalline polymer obtained by polymerizing a propylene monomer as a main component, and is not limited to a homopolymer, but other α such as propylene and ethylene.
Includes block or random copolymers with olefins. In the case of copolymers, propylene-ethylene random copolymers are preferred. In this case, the ethylene content is preferably 1 to 10% by weight. Such polypropylenes usually have a melt flow rate (MFR) of 0.01 to 100 g / 10 min.
, JIS K7210, load 2.16 kg, 230 ° C).

Further, in the present invention, as the polyamide,
Hexamethylenediamine, decamethylenediamine, dodecamethylenediamine, 2,2,4- or 2,4,4, -trimethylhexamethylenediamine, 1,3- or 1,4-bis (aminomethyl) cyclohexane, bis (p -Aminocyclohexylmethane), aliphatic, alicyclic or aromatic diamines such as m- or p-xylylenediamine and adipic acid, suberic acid, sebacic acid, cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid Polyamides produced from various aliphatic, alicyclic or aromatic dicarboxylic acids, polyamides produced from aminocarboxylic acids such as 6-aminocaproic acid, 11-aminoundecanoic acid and 12-aminododecanoic acid, ε- Caprolactam, polyamides made from lactams such as ω-dodecalactam, and these components Copolyamide or mixtures of these polyamides, and the like. Specifically, nylon 6 (polyamide 6), nylon 66 (polyamide 66), nylon 610, nylon 9, nylon 6/6
6, nylon 66/610, nylon 6/11, nylon 6/1
2, nylon 12, nylon 46, amorphous nylon and the like. Of these, nylon 6 and nylon 66 are preferable in terms of good rigidity and heat resistance.

Although the molecular weight is not particularly limited, a polyamide having a relative viscosity η _r (JIS K6810, measured in 98% sulfuric acid) of 0.5 or more is usually used, and among them, those having a relative viscosity of 2.0 or more are excellent in mechanical strength. Is preferred.

In order to improve heat resistance and mechanical strength, it is preferable to add glass fiber to the above resin component (polyolefin + polyamide). The glass fiber is not particularly limited, and chopped strands, rovings and the like can be used. The fiber diameter is preferably about 5 to 30 μm. Further, those subjected to a surface treatment in consideration of the adhesiveness with the resin serving as the matrix are preferable.

When the composition comprising the above-mentioned polyolefin, polyamide and glass fiber is used as a heat pipe or a radiator tube, the mixing ratio of each component is such that polyamide is 30 to 60% by weight and polypropylene is 20 to 40% by weight. %, And the glass fiber content is preferably 10 to 35% by weight. However, the content of glass fiber is related to the length of the moldable product and the temperature of the mold during blow molding, which will be described later.The higher the content, the shorter the length of the moldable product. Moreover, since the die temperature must be raised, the content is appropriately set according to the desired product length.

In the present invention, each of the above resins is
Other additives such as a filler, a heat stabilizer, a light stabilizer, a flame retardant, a plasticizer, an antistatic agent, a release agent, a foaming agent, and a nucleating agent can be appropriately added for the purpose of modification. ..

Next, the blow molding apparatus of the present invention for performing blow molding using the above resin component will be described.

FIG. 1 is a schematic diagram showing an apparatus of the present invention for producing a bend blow molded product. In FIG. 1, a bending blow-molded article manufacturing apparatus of the present invention comprises a mold 1 having a bent cylindrical cavity as indicated by a broken line in the drawing.
An upper shutter mechanism 2 having a heating air supply port that opens and closes in accordance with the supply of heating air, and a shutter (shown by a broken line), a flow path 3 for supplying heating air, and a heating air generator (not shown). ), A suction port 4 connected to the lower end opening of the mold 1, and a lower shutter mechanism 5 (not shown). An extrusion blow molding machine (composed of an extruder 6 and a die 7) is installed above it, and a cylindrical parison 8 is extruded from the die 7.

In the above apparatus, it is preferable that the heated air supply apparatus and the suction apparatus are connected so that the air circulates, because the energy efficiency is good.
In this case, the upper shutter mechanism 2 and the lower shutter mechanism 5 are preferably controlled so as to be opened and closed at the same time by an electromagnetic valve or the like.

FIG. 2 shows a front view of the mold 1 of such a bending blow-molded product manufacturing apparatus, and FIG. 3 shows a side view with the mold opened. The mold 1 has a mating surface 11 corresponding to the bending of the desired pipe shape in the width direction (Y-axis direction, left-right direction in FIG. 2).
have. Further, as shown in FIG. 3, the cavity 12 of this mold has a desired pipe shape in the depth direction (Z-axis direction,
It is bent in the left-right direction in FIG.

The mold 1 as described above has openings 13 and 14 at the upper and lower ends thereof, and is formed with a cylindrical cavity 12 which is bent according to a desired pipe shape. Flange portions 12a, 12b, 12c are formed at the corresponding portions. A suction port 4 is connected to the lower end opening 14 as described later, and the heated air is sucked from here. A heating device 15 is built in the mold 1. It is preferable that the heating device 15 is installed especially at the bent portion of the cavity where the cylindrical parison is likely to contact.

The suction device has a suction port 4 and a lower shutter mechanism 5, and a punch plate (not shown) or the like is provided below the lower shutter mechanism 5 of the suction port to form a parison. Has stopped here, and the tip is being sealed.

In the mold 1 as described above, it is preferable that the mating surface 11 of the mold has as little bending as possible. Therefore, depending on the desired shape of the bent pipe,
It may be designed so that the bending of the die mating surface is small.

The method of the present invention in which blow molding is carried out from a composition comprising, for example, polyamide / polyolefin / glass fiber using such an apparatus will be described. First,
The resin component is melted and extruded into a cylindrical shape from an extrusion blow molding machine. As this extrusion blow molding machine, those of ordinary accumulator type, screw type and the like can be used.

At this time, the mold 1 is closed and the temperature is
It is heated to 120 to 200 ° C, preferably 150 to 180 ° C. At this time, the upper shutter and the lower shutter are opened. If the mold temperature is less than 120 ° C, the parison will be hardened by contact with the mold at the bend, and the blow moldability described below will not be good. If it exceeds 200 ° C, the molding time and shape after mold removal will be low. Retention is deteriorated. However, the temperature of the mold 1 is preferably set according to the melting point of the resin used, the content of the filler such as glass fiber, and the like,
Polyamide 66 30-60% by weight, polypropylene 20
When a resin composition consisting of -40% by weight and 10-35% by weight of glass fiber is used, the temperature is preferably 150-180 ° C.

Subsequently, the cylindrical parison 8 is lowered from the upper end opening 13 of the mold 1, and heated air is fed from the shutter mechanism 2 and blown into the cavity 12. The temperature of heated air must be at least 80 ° C or higher. If the temperature of the heated air is lower than 80 ° C., the parison is likely to harden near the outlet of the mold 11. However, the temperature of the heated air is preferably set according to the melting point of the resin used, the content of the filler such as glass fiber, etc., and when the resin composition is used, it is set to 80 to 100 ° C. Is good. The amount of heated air fed varies depending on the size of the blow-molded product to be manufactured, but is preferably about ^{3 to 5} Nm ³ / min.

At the same time, by a suction device from the lower end opening 15,
By sucking heated air, the upper opening 13
To generate an airflow flowing from the cavity through the cavity 12 to the lower end opening 14 to guide the cylindrical parison according to the bending of the cavity.

After that, when the front end of the cylindrical parison protrudes from the lower end opening 14 by a required amount, the supply of heated air is stopped and the upper and lower shutters are closed. At this time, the tip is sealed by a punch plate or the like.

An example of the bending blow-molded article obtained by the method of the present invention is shown in FIG. In FIG.
(a) shows the front surface of the bending blow-molded product 16, and (b) shows the side surface thereof. As described above, the method of the present invention is suitable for manufacturing a product having a plurality of bends and the directions thereof are two or more directions (three-dimensional). Furthermore, the product length (calculated with the bending extended) is 500 mm or more, and it is suitable for producing a molded product having an average wall thickness of about 2 mm. It is also suitable for forming a sealing flange portion at the end portion of the pipe with a surface roughness suitable for sealing as in this embodiment. The bending blow-molded product thus obtained has a smooth appearance (surface), and its cross-section has almost no air inclusions or poor drawing points.

[0033]

In the present invention, the suction has a pair of molds having openings at the upper and lower ends and forming a bent cylindrical cavity, and a lower shutter mechanism connected to the lower end of the molds. A device having a device and a shutter mechanism provided on the upper end opening of the cavity of the mold and having a heated air supply port was used, and the temperature of the mold was determined according to the melting point of the resin used for extrusion blow molding. By controlling the temperature to an appropriate level, blowing heated air of 80 ° C or more into the cavity from the heated air supply port, and sucking it from the lower end of the mold, the cylindrical parison is adjusted to the bending of the cavity. By inducing the parison into a complicated bent shape without curing the resin component, and then blow molding it, bending blow molding with good appearance and strength It is obtained.

The reason why such an effect is obtained is not necessarily clear, but by controlling the temperature of the mold to an appropriate temperature and inducing the parison with heated air of 80 ° C. or more, a cylindrical shape is obtained. The parison does not harden in the process of bending in the cavity, and therefore blow molding is performed under the same conditions regardless of the site of the molded body, so that air or the like is mixed in the cross section or uneven stretching or the like occurs. It is thought that this is because it cannot be seen.

[0035]

The present invention will be described in more detail by the following examples. Example 1 34 parts by weight of polypropylene (a composition comprising 30 parts by weight of Tonen Polypro E200X (manufactured by Tonen Kagaku KK) and 5 parts by weight of Tonen CMP C910X (manufactured by Tonen Kagaku KK) and 34 parts by weight of polyamide 66 (T300). 15 parts by weight of glass fiber was mixed with 51 parts by weight of a resin component, which was manufactured by Ems Co., Ltd., and an extrusion blow molding apparatus (manufactured by Ishikawajima Harima Heavy Industries Ltd., IP
B-10) is used to mold with a resin temperature during extrusion of 270 ° C., a mold temperature of 150 ° C., and a temperature of heated air to be fed at 100 ° C., as shown in FIG. Length 700 mm, outer diameter 20 mmφ, average wall thickness 2 mm, height at both ends
A plastic bent pipe with a 3.5 mm flange was manufactured.

The appearance and the cross section of the molded product of the pipe thus obtained were visually observed. The results are shown in Table 1.

Comparative Example 1 In Example 1, the mold was not heated (mold temperature 25 ° C.),
Example 1 except that the temperature of the heated air to be fed was 100 ° C
A plastic bent pipe was manufactured in the same manner as in.

The appearance of the pipe thus obtained and the cross section of the molded product were visually observed. The results are shown in Table 1.

Example 2 26 parts by weight of polypropylene (composition comprising 20 parts by weight of Tonen Polypro E200X (manufactured by Tonen Chemical Co., Ltd.) and 5 parts by weight of Tonen CMP C910X (manufactured by Tonen Chemical Co., Ltd.)) and polyamide 35 parts by weight of glass fiber is mixed with 39 parts by weight of 66 (manufactured by T300 Ems Co., Ltd.), and an extrusion blow molding device (manufactured by Ishikawajima Harima Heavy Industries Ltd., IP
B-10) is used and the temperature of the resin during extrusion is 270 ° C., the mold temperature is 180 ° C., and the temperature of the heated air to be fed is 100 ° C. Length 700 mm, outer diameter 20 mmφ, average wall thickness 2 mm, height at both ends
A plastic bent pipe with a 3.5 mm flange was manufactured.

The appearance of the pipe thus obtained and the cross section of the molded product were visually observed. The results are shown in Table 1.

Comparative Example 2 A plastic bent pipe was manufactured in the same manner as in Example 2 except that the mold temperature was 180 ° C. and the temperature of the heated air fed was 25 ° C.

The appearance of the pipe thus obtained and the cross section of the molded product were visually observed. The results are shown in Table 1.

Table 1 Example 1 Example 2 Comparative Example 1 Comparative Example 2 Appearance ⁽¹⁾ ○ ○ × × Cross-section of molded product ⁽²⁾ ○ ○ × ×

(1) Appearance: The appearance of the pipe was visually observed, the surface was smooth, and the surface roughness of the flange portion was 10
When the surface roughness is less than μm, the surface is roughened, or when the surface roughness of the flange is more than 10 μm, it is evaluated as x. (7 ² Cross-section of molded product: A solid and uniform cross-section was evaluated as ○, and a cross-section that was not uniform and was observed due to mixing of air etc. was evaluated as ×.

As is clear from Table 1, the pipes of Examples 1 and 2 produced by the method of the present invention had a smooth surface, the roughness of the flange portion serving as the seal portion was small, and the cross section thereof was uniform. It was uniform. On the other hand, the pipes of Comparative Examples 1 and 2 produced by the conventional method had a roughened surface, the flange portion was unsuitable as a seal portion, and the cross section thereof contained "". ..

[0046]

As described above in detail, in the present invention,
A pair of molds having openings at the upper end and the lower end and forming a bent cylindrical cavity, a suction device having a lower shutter mechanism connected to the lower end of the mold, and a cavity of the mold. Using a device having a shutter mechanism having a heating air supply port provided on the upper end opening of the, the temperature of the mold is controlled to an appropriate temperature according to the melting point of the resin used for extrusion blow molding, Furthermore, by blowing heated air of 80 ° C or more into the cavity from the heated air supply port and sucking it from the lower end side of the mold, the parison is made into a complicated curved shape, and then blow molding is performed to obtain a blow molded product. Since it is manufactured, a flex blow molded product having a good appearance and strength can be obtained.

The blow-molded article obtained by the method of the present invention is suitable for a tube for connecting a heater for automobiles, a radiator, etc., or a tube, a pipe, etc. for a general-purpose air conditioner.

[Brief description of drawings]

FIG. 1 is a schematic view showing an apparatus for manufacturing a bending blow-molded product according to an embodiment of the present invention.

FIG. 2 is a front view of a mold in the apparatus of FIG.

FIG. 3 is a side view of the apparatus of FIG. 1 with a mold opened.

FIG. 4 is a plan view showing an example of a pipe that can be manufactured by the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Mold 2 ... Upper shutter mechanism 3 ... Heated air supply flow path 4 ... Suction port 5 ... Lower shutter mechanism 6 ... Extruder 7 ... Die 8 ...・ Parison 11 ・ ・ ・ Attached surface 12 ・ ・ ・ Cavities 13, 14 ・ ・ ・ Opening 15 ・ ・ ・ Heating device 16 ・ ・ ・ Bending blow molding

Claims (2)

[Claims] 1. (A) An opening is provided at an upper end portion and a lower end portion,
A pair of molds forming a bent cylindrical cavity,
Using an upper shutter mechanism provided on the upper opening of the cavity of the mold and having a heated air supply port, and a suction device having a lower shutter mechanism connected to the lower end of the mold, (B) Extrusion The cylindrical parison extruded from the machine, 120
Introduced into the cavity of the mold heated to ~ 200 ℃, blow the heated air of 80 ℃ or more from the upper shutter mechanism into the cavity, (C) the suction device from the lower end opening side of the mold, By sucking heated air, the cylindrical parison is guided in accordance with the bending of the cavity, and (D) where the tip of the cylindrical parison protrudes from the lower end opening by a required length, the upper portion and A method for producing a bent blow-molded product, characterized in that the lower shutter is closed to seal the front end of the parison, and (E) blow-molding is performed by blowing air into the parison. 2. A pair of molds having: (a) an opening at the upper end and the lower end, and forming a bent cylindrical cavity and incorporating a heating device; and (b) an upper end opening of the cavity. A heating air supply device provided on the upper shutter mechanism having a heating air supply port, and (c) a suction device having a lower shutter mechanism connected to the lower end of the cavity of the mold, The temperature of the mold is heated to 120 to 200 ° C. by the heating device, the cylindrical parison extruded from the extruder is introduced into the cavity of the mold, and the heating air supply port of the heating air supply device is used. By blowing heated air of 80 ° C. or higher into the cavity and sucking the heated air by the suction device at the lower end of the mold,
An apparatus for manufacturing a bent blow-molded article, which comprises guiding the cylindrical parison according to the bending of the cavity, closing the upper and lower shutters, and subsequently blow-molding the cylindrical parison.