JP2900827B2 - Molding method, molded product and molding material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the blowing of thermoplastic resin.
It relates to a molding method . More specifically, the present invention relates to a blow molding method capable of transferring a molding surface of a mold to a molded product well even when molding at a low pressure, and having excellent molding stability.

[0002]

2. Description of the Related Art As a method for obtaining a resin molded product, an injection molding method and a blow molding method have been used. In the injection molding method, the molten resin is placed under high pressure (200 to 1000 kg) in a closed mold.
/ Cm ² ) to transfer the molding surface of the mold to resin. Because of the high pressure, the transfer of the molding surface is performed accurately. Therefore, it is suitable for obtaining a molded product having a mirror surface or a grained surface. However, since a mold that can withstand high pressure is required, the structure of the mold is complicated and the cost is high, which is not suitable for high-mix low-volume production. In addition, since a special device is required for molding a hollow product, the production process is complicated. Blow
In the molding method, a parison (a hollow cylindrical resin in a molten and softened state) is supplied between the molds, the mold is clamped, and the outer surface of the parison is pressed against the molding surface of the mold by pumping fluid into the hollow portion. Transfer method. Since it is pressed by the pressure of the fluid, the pressure is relatively low (4 to 10 kg / cm ² ), so that the molding surface is not transferred cleanly, which is not suitable for obtaining a molded product having a mirror surface or a grain surface. However, it is widely used because it is suitable for mass production of hollow articles.

[0003] Japanese Patent Application Laid-Open No. 58-102732 discloses a hollow molding die having a thin molding inner die and a cooling outer die capable of contacting / isolating the molding inner die. In this mold, the inner mold for molding is heated before the parison is supplied for the purpose of improving the surface gloss of the hollow molded product,
After the parison comes into contact with the molding surface of the inner mold for molding, the inner surface of the outer mold for cooling is brought into contact with the outer surface of the inner mold for molding to quickly cool the inner mold for molding to obtain a molded product. ing.

Japanese Patent Application Laid-Open No. Hei 4-77231 discloses that, when a parison is brought into contact with a molding surface of a mold, the temperature of the mold is adjusted from a temperature near a temperature at which the crystallization speed of the parison becomes maximum to a melting point. The die line and the weld line are prevented from remaining on the surface of the molded product by holding it during the molding process, and the refrigerant is circulated through the hollow part of the parison during molding, thereby prolonging the molding cycle time. A method of preventing blow molding is disclosed.

[0005]

There is a demand for obtaining a resin molded product having a mirror surface or a grain surface using a mold having a relatively simple structure, in other words, at a relatively low molding pressure. There is also a demand for producing a hollow resin molded product having a mirror surface or a grain surface (eg, an air spoiler of an automobile) by a simple process.

In the mold for hollow molding described in Japanese Patent Application Laid-Open No. 58-102732, the molding surface is clearly transferred by heating the molding inner mold. Since the resin is cooled by being relatively displaced and brought into contact with the resin, the structure of the mold may be complicated and weakened, and the cooling time may be prolonged. Further, there is no mention of the optimum range of the heating temperature and the cooling temperature for cleaning the surface of the resin molded product and shortening the entire cycle time of the molding.

[0007] The blower disclosed in Japanese Patent Application Laid-Open No. 4-77231 is disclosed.
In the molding method, the molding surface is cleaned by heating and maintaining the temperature of the molding die at the above-mentioned temperature, but since the heating is maintained at that temperature even during cooling, the effect of shortening the cooling time is not so large. . Further, since the parison is cooled from the inside by circulating the refrigerant, temperature control for heating and maintaining the temperature of the mold at the above-mentioned temperature becomes complicated.

[0008] The present invention solves the problems that occur when molding a resin molded article at a relatively low molding pressure. It is an object of the present invention to provide a molding method capable of molding with high productivity in a simple process, a molded product obtained from the molding method, and a molding material used in the molding method.

[0009]

According to the first aspect of the present invention, there is provided a molding method.
Any of the following molds (1) to (4)
Using a mold, under the condition of Vicat softening temperature (T) + 100 ° C
Longitudinal elastic modulus of 0.01 to 20 [kg / cm ² ]
The thermoplastic resin is used as a hollow parison in a molten state,
The hollow parison is supplied between the molds, and the outer surface of the hollow parison is formed into a mold.
Pressed against the surface with a pressure of 100 kg / cm ² or less,
Simultaneously with or after adhesion, the molded surface is
Temperature (T) ° C. or higher, then the Vicat softening
Temperature (T) Cool down to -10 ° C or lower and solidify
This is a blow molding method in which a molded product is taken out . (1) 100 kg / cm of molten thermoplastic resin
² ] A molding die which is brought into close contact with a molding surface of a mold under the following pressure to be solidified, wherein the molding surface is simultaneously or simultaneously adhered to the molding surface, and the Vicat softening temperature (T) of the thermoplastic resin.
A heating means for heating to a temperature of not less than 0 ° C .; a cooling means for cooling the molding surface to a temperature of not more than the Vicat softening temperature (T) -10 ° C. after completion of the close contact; A molding die having a space between itself and the die main body. If the heating temperature by the above heating means is not more than the Vicat softening temperature (T) + 5 ° C., more preferable results can be obtained. (2) In the above (1), the molding surface is formed by a mold body.
Formed on the surface of a metal body
Mold. (3) In the above (1) or (2), the heating means
Is for molding, which is means selected from the following (A) to (C)
Mold. (A) supplying a heated liquid and / or gas to the space;
Means for heating the molding surface. (B) provided in the space so as to face the opposite surface.
Heating element and abutting / isolating the heating element against the opposite surface
And a heating mechanism for heating the molding surface.
The body is heated and brought into contact with the opposite surface to cool the molding surface
Sometimes means for isolating the heating element from the opposite surface. (C) provided in the space so as to face the opposite surface.
Radiates heat toward the opposite surface when the molding surface is heated .
Means. (4) In the above (1) or (2), the cooling means
Is the Vicat softening temperature (T)-
Supply liquid and / or gas at a temperature of 10 ° C or less to the space
Mold having a cooling means.

According to a second aspect of the present invention , there is provided a molding method using the method of the first aspect.
It is a molded article. Further, the invention of claim 3 is the invention of claim
Examples of suitable thermoplastic resins are given as molding materials used in the blow molding method 1 .

The molding method of the present invention can be used for molding various thermoplastic resins. Vicat softening temperature (T) +
The preferred longitudinal elastic modulus of the thermoplastic resin at 100 ° C. is 0.01 to 20 [kg / cm ² ], more preferably 0.05 to ² [kg / cm ² ], and particularly preferably 0.1 to 1 [kg / cm ² ]. [Kg / cm ² ]. If the longitudinal elastic modulus is in this range, molded articles that have a more excellent mirror surface or embossed surface, which is an object of the present invention can be obtained, and excellent in blow moldability. Examples of the thermoplastic resin include AS resin, polystyrene, high impact polystyrene, a graft copolymer (ABS resin) composed of acrylonitrile-butadiene rubber-styrene, and a graft copolymer composed of acrylonitrile-butadiene rubber-styrene-α-methylstyrene. Polymer (heat-resistant ABS resin), graft copolymer (AES resin) composed of acrylonitrile-ethylene-propylene rubber-styrene and / or methyl methacrylate, acrylonitrile-hydrogenated diene rubber-styrene and / or methyl methacrylate Graft copolymer, polyethylene, polypropylene, polycarbonate, polyphenylene ether, polyoxymethylene, nylon, methyl methacrylate polymer, polyether sulfone, polyarylate, etc., and Composite of these can be mentioned, also include resins obtained by adding fillers thereto.

[0012]

The thermoplastic parison in the molten state is simultaneously or closely adhered to the molding surface of the mold, and then the molded surface is heated to a temperature higher than the Vicat softening temperature (T) ° C. of the thermoplastic resin, so that the molding surface is removed from the molding surface. In the case of blowing, the parison comes into close contact before heating, so that the needle for blowing gas into the parison is smoothly inserted. As a result, it is possible to stably mold a molded article having excellent mirror and grain surfaces and excellent dimensional accuracy. The preferred temperature of the molding surface when the parison is in close contact with the molding surface is in the range of the Vicat softening temperature (T) -20 ° C to (T) -60 ° C. Further, after the adhesion is completed, the molded surface is cooled to the Vicat softening temperature (T) -10 ° C. or lower, whereby the molded product is solidified.

[0013]

EXAMPLES Examples of the present invention and comparative examples will be described below.
The thermoplastic resin used in the following Examples and Comparative Examples is ABS
Resin was used. The ABS resin is JSR ABS45A manufactured by Japan Synthetic Rubber Co., Ltd., and has a Vicat softening temperature of 105.
Longitudinal modulus at 0.3 ° C and 205 ° C 0.3 [kg / cm ² ]
It is. In the following Examples and Comparative Examples, ABS resin (JS
(R ABS45A) is obtained by blow molding to obtain a box-shaped molded product. That is, in each of the examples and comparative examples, as shown in FIG. 11, the ABS resin is melted by the extruder 81 and fed to the accumulator die 82, and the hollow cylindrical parison 90 is formed by the accumulator die 82 so that the parison 90 is moved downward. The parison 90 is blown out and blow-molded by one of the following molds 3 (each mold of Examples A to C and Comparative Examples a to e).

Here, the screw diameter of the extruder 81 is 5
5 mm, maximum extrusion capacity is 2000 cc. The parison 90 delivered from the accumulator die 82 has a diameter of 100 mm, a temperature of 200 ° C., and a delivery time to each mold 3 of 2 seconds. Also, each mold
3 is 250mm wide, 600mm high and 50m thick
m, and the maximum clamping force is 15 TON. The molding surface of each mold 3 is a mirror surface.

At the start of blow molding, in each case, the gap between the parison 90 and the molding surface of the mold 3 is maintained at a vacuum of 30 mmHg for 10 seconds, whereby the outer surface of the parison 90 is maintained. When the outer surface of the parison contacts or approaches the molding surface of the mold 3 by suction, the needle for sending air into the parison provided in the molding surface cavity enters the parison. Further, the outer surface of the parison 90 is brought into close contact with the molding surface of the mold 3 by continuously feeding air at a pressure of 7 kg / cm ² into the parison 90 until the end of the blow molding. That is, molding is performed with a molding pressure of 7 kg / cm ² . The mold clamping force of the mold 3 is 15 TON.

Next, conditions and the like that differ depending on each mold will be described.

* Example A This mold is heated by the method of FIG. 4 and cooled by the method of FIG. That is, the outer surface of the parison 90 is brought into close contact with the molding surfaces of the metal bodies 1a and 1b having a molding surface temperature of 50 ° C. as described above. Then, as shown in FIG.
Each space between the back side of the metal body 1a, 1b and the mold body 3a, 3b
Heating element (electric heating heater) 50 provided in each of 4a and 4b
a, 50b respectively generate heat, and the heating elements 50a, 50b are pushed forward through the rods 50a2, 50b2 by the action of the hydraulic cylinders 50a1, 50b1 to abut against the back surfaces of the metal bodies 1a, 1b. Each of the molding surfaces on the front side of the metal bodies 1a and 1b is
Heated to 20 ° C. Further, each of the heating elements 50a, 50b
Are cooled to their original positions by the action of the hydraulic cylinders 50a1 and 50b1 during cooling. In addition, in FIG. 4, 2a and 2b are heat insulators.

The outer surface of the parison 90 is made of a metal body 1a, 1b.
After being brought into close contact with the molding surface of, cooling water (pressurized water) is passed through the liquid supply pipes 61a and 61b to the respective spaces 4a and 4b as shown in FIG.
Is injected. The flow rate is 100 cc / sec. Further, the injection direction is a direction toward the back surfaces of the metal bodies 1a and 1b, whereby heat exchange is performed on the back surfaces, the cooling water is evaporated, and the metal bodies 1a and 1b are cooled. You. The cooling time is 30 seconds. The steam is sucked and discharged through the exhaust pipes 61a1 and 61b1 by the vacuum pumps 61a2 and 61b2. That is, the pressure in the spaces 4a and 4b is reduced, thereby promoting the evaporation.

After cooling, the molded product was vented, the mold was opened, and the molded product was taken out. The transfer of the mirror surface was good, and the molded product had no warp and was excellent in dimensional accuracy. The time required for removal was 60 seconds, and the total cycle time was 70 seconds. In addition, when similarly molded with a mold having a textured surface, similar results were obtained.

* Embodiment B In this mold, heating is performed by the method of FIG. 5 and cooling is performed by the method of FIG. That is, the metal body 1 having a molding surface temperature of 50 ° C.
The outer surface of the parison 90 is brought into close contact with the molding surfaces a and 1b as described above. And, as shown in FIG.
Heat is radiated to the back side of the metal bodies 1a and 1b by the line concentrating heaters 51a and 51b provided in the spaces 4a and 4b, respectively, so that the molding surfaces on the front side are each 120 mm. Heat to ° C. This heating was stopped 2 seconds after the start of air supply into the parison 90.

After the heating by the line concentrating heaters 51a and 51b is stopped, as shown in FIG.
b into the air through the air supply pipes 6a and 6b.
/ Min. This infeed is for metal body 1
This is performed through a diffusion nozzle so that air is injected toward the back surface of a, 1b, whereby heat exchange is performed on the back surface, and the metal bodies 1a, 1b are cooled from the back surface side . The air sent into each of the spaces 4a and 4b is
After the heat exchange, the gas is discharged through the exhaust pipes 6a1 and 6b1.

After cooling, the molded product was vented, the mold was opened, and the molded product was taken out. The transfer of the mirror surface was good, and the molded product had no warp and was excellent in dimensional accuracy. The time required for removal was 110 seconds, and the total cycle time was 130 seconds. In addition, when similarly molded with a mold having a textured surface, similar results were obtained.

* Example C In this mold, heating is performed by the method of FIG. 3 and cooling is performed by the method of FIG. That is, the outer surface of the parison 90 is brought into close contact with the molding surfaces of the metal bodies 1a and 1b having a molding surface temperature of 50 ° C. as described above. And, as shown in FIG.
Heated steam of 150 ° C. is injected into the respective spaces 4a, 4b through the air supply pipes 5a, 5b toward the back surfaces of the metal bodies 1a, 1b.
As a result, heat exchange was performed on the back surface, and the heated steam was condensed into droplets, and the front side (molding side) of the metal bodies 1a and 1b was heated to 120 ° C. The droplets are discharged from the drainage pipes 5a1 and 5b1 via the pressure control valves 5a2 and 5b2.

After the heating by the heating steam at 150 ° C. is stopped, the metal members 1a, 1b
Was cooled to 80 ° C. or lower.

After cooling, the molded product was degassed, the mold was opened, and the molded product was taken out. The transfer of the mirror surface was good, and the molded product was excellent in dimensional accuracy without warping.
The time required for removal was 65 seconds, and the total cycle time was 75 seconds. In addition, when similarly molded with a mold having a textured surface, similar results were obtained.

* Comparative Examples Each of the molds of Comparative Examples a to e has a structure in which the molding surface is integral with the mold body, and therefore does not have a heat insulator. Therefore, when the mold is heated to cleanly transfer the molding surface, it takes a long time to cool the mold.

The temperature at the time of molding each mold was 50% in Comparative Example a.
Comparative Example b is 120 ° C., Comparative Example c is 170 ° C., Comparative Example d is 30 ° C., and Comparative Example e is 150 ° C. That is, Comparative Example a and Comparative Example d were at low temperatures, Comparative Example b, Comparative Example c, and Comparative Example e.
Have been at high temperatures. For this reason, the state of the mirror surface of the molded product is generally good for the comparative example a at the medium temperature, good for the high-temperature comparative example b, the comparative example c and the comparative example e, and not good for the low-temperature comparative example d. However, the time required for removing the molded article and the total cycle time of molding are as follows:
ec and 70 sec, Comparative Example b of high temperature was 150 sec and 1
Comparative example c of 70 sec and high temperature was 290 sec and 310 s
ec, low temperature comparative example d is 45 sec and 55 sec, and high temperature comparative example e is 250 sec and 280 sec. In other words, the higher the temperature, the longer the time required for removal and the cycle time, and the result was the opposite of the mirror surface condition. As described above, in the mold of the comparative example, by raising the temperature at the time of molding, the mirror surface can be satisfactorily transferred to the molded product, but the time required for removal and the total cycle time of molding are increased. A problem has occurred. Note that the same result was obtained in the transfer in the case of the grained surface. In Comparative Example f, the molding method was the same as that of Example A, except that after the molding surface was heated to 120 ° C., the parison was brought into close contact with the molding method, and otherwise the molding method was performed. The obtained molded product was inferior to Example A in terms of mirror surface transferability, warpage resistance, dimensional accuracy, and molding stability.

* Other Embodiments In the above-described embodiments A to C, FIGS. 3, 4, 5, 9, and 1
Although the method 0 is described, heating by the methods of FIGS. 6 to 8 is also possible. FIG. 6 shows a case where the heating gas is supplied through the air supply pipes 52a and 52b for heating, and the gas after the heat exchange is supplied to the exhaust pipe 52a.
1, 52b1 is exhausted. FIG. 7 shows the metal bodies 1a, 1b.
This is a method in which the line condensing heaters 51a and 51b enter the molding surface side temporarily and are heated. FIG. 8 shows a metal body.
In this method, the air supply pipes 53a and 53b are temporarily inserted into the molding surfaces 1a and 1b to heat them.

FIG. 1 shows that the heat capacity of the metal bodies 1a, 1b is reduced by insulating the metal bodies 1a, 1b, on which the mold bodies 3a, 3b and the molding surfaces are formed, with heat insulators 2a, 2b. FIG. 2 shows that the spaces 4a, 4b are provided between the back surfaces of the metal bodies 1a, 1b and the mold bodies 3a, 3b.
FIGS. 4a and 4b show how a heating medium and a cooling medium can be supplied.

In addition to the heating method described above, a method of heating at a high frequency or a method of heating with a far-infrared heater can be adopted. Further, as a method for obtaining the heating steam, for example, a dielectric heating method can be adopted.

[0031]

By molding a molded article by the molding method of the present invention, a molded article having excellent mirror and grain surfaces, having no warp, and having excellent dimensional accuracy can be molded. In the molding, since the molding stability is excellent, there is no occurrence of a defective rate, the molding cycle time is short, and the molding can be performed by a relatively simple mold and molding process.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a state in which a metal body having a molding surface of a mold is insulated from a mold body.

FIG. 2 is a schematic sectional view showing a mold according to claim 2;

FIG. 3 is a schematic sectional view showing a mold corresponding to (A) of claim 3;

FIG. 4 is a schematic sectional view showing a mold corresponding to (B) of claim 3;

FIG. 5 is a schematic sectional view showing a mold corresponding to (C) of claim 3;

FIG. 6 is a schematic cross-sectional view showing a state in which a metal body having a molding surface formed by the mold of FIG. 2 is heated from the space side.

FIG. 7 is a schematic sectional view showing a mold corresponding to (D) of claim 5;

FIG. 8 is a schematic sectional view showing a mold corresponding to (E) of claim 5.

FIG. 9 is a schematic cross-sectional view showing how a metal body having a molding surface formed by the mold of FIG. 2 is cooled from the space side.

FIG. 10 is a schematic sectional view showing a mold according to claim 4;

FIG. 11 is a schematic view showing the entire configuration of blow molding.

[Explanation of symbols]

 1a, 1b Metal body with formed surface 2a, 2b Heat insulator 3 Mold 3a, 3b Mold main body 4a, 4b Space 5a, 5a1, 5a2 Heating means 6a, 6a1 Cooling means 81 Extruder 82 Accumulator die 90 Parison

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI B29L 22:00 (72) Inventor Fumio Kurihara 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd. (56) Reference Document JP-A-7-1459 (JP, A) JP-A-62-130762 (JP, A) JP-A-62-63111 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B29C 33/02-33/04 B29C 33 / 38,49 / 04,49 / 48 B29C 49/64

Claims (3)

(57) [Claims] 1. A molding die,The following (1) to (4)
Any ofVicat softening temperature (T)
The longitudinal elastic modulus under the condition of + 100 ° C is 0.01 to 20.
[Kg / cm^Two ] The molten thermoplastic resin
The hollow parison is fed between the molds as
100 kg / cm^Two ]
Pressing with the lower pressure, simultaneous with or after close contact,
Heating the surface above the Vicat softening temperature (T) ° C.
After that, the Vicat softening temperature (T) ℃ -10 ℃ or less
The molded product is taken out after being cooled and solidified.
Low molding method.(1) 100 kg / cm of molten thermoplastic resin
^Two ] The following pressure adheres to the molding surface of the mold and solidifies
A molding die, At the same time as the close contact, after the close contact, the molding surface is
Heats to a temperature above the Vicat softening temperature (T) ° C of the conductive resin
Heating means, After the adhesion is completed, the molding surface is heated to the Vicat softening temperature.
(T) a cooling means for cooling to a temperature of -10 ° C or lower, and
On the opposite side of the molding surface, a space
A molding die having: (2) In the above (1), the molding surface is formed by a mold body.
Formed on the surface of a metal body
Mold. (3) In the above (1) or (2), the heating means
Is for molding, which is means selected from the following (A) to (C)
Mold. (A) supplying a heated liquid and / or gas to the space;
Means for heating the molding surface. (B) provided in the space so as to face the opposite surface.
Heating element and abutting / isolating the heating element against the opposite surface
And a heating mechanism for heating the molding surface.
The body is heated and brought into contact with the opposite surface to cool the molding surface
Sometimes means for isolating the heating element from the opposite surface. (C) provided in the space so as to face the opposite surface.
Radiates heat toward the opposite surface when the molding surface is heated.
Means. (4) In the above (1) or (2), the cooling means
During cooling of the molding surface , Vicat softening temperature (T)-
Supply liquid and / or gas at a temperature of 10 ° C or less to the space
Mold having a cooling means. 2. A molded article formed by the method of claim 1 . 3. The longitudinal elastic modulus under the condition of Vicat softening temperature (T) + 100 ° C. is 0.01 to 20 kg / cm.
Molding material used in the molding method according to claim 1, wherein a thermoplastic resin is ^2].