JP2904513B2 - Forming method for mouth and bottom of preform - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for forming a preform for bottle molding.

[Conventional technology]

Conventionally, a single polyethylene terephthalate preform or the like is generally formed by injection molding.

Then, as a preform molding method for a multilayer bottle having gas barrier properties and the like, a pipe formed of a multilayer resin layer is molded by extrusion molding or the like, and then, a screw, a flange, and the like are formed at one end of the pipe. A preform molding method is adopted in which the preform is formed into a mouthpiece portion, and the other end of the pipe is closed to form a bottom portion.

In general, the mouth portion of the preform is formed by pressurizing one end of a heated and softened pipe with high-pressure air in a mold provided with a concave portion for molding such as a screw or a flange. Molding is performed.

In addition, the bottom of the preform is generally formed by pressing the other end of the heated and softened pipe between a concave mold and a convex mold and pressing the other end of the pipe in the cavity into a hemisphere. Compression molding for forming a closed bottom such as a shape is employed.

[Problems to be solved by the invention]

In the conventional method of forming the mouthpiece portion of the preform, it is difficult to accurately project the screw or flange portion to the outside, and the inside of the projecting portion of the screw or flange has an annular shape. The concave portion was generated, and the concave portion might buckle due to the pressing force at the time of capping.

In addition, the conventional method of forming the bottom of the preform includes:
Due to the compression molding method, if the wall thickness is too thin or too thin to be molded to size, or if the excess resin overflows to avoid the problem, cut it after molding Additional steps that must be removed.

Further, when the bottom is formed into a hemispherical shape or the like, radial wrinkles are generated at the bottom, and the wrinkles remain even after being formed in the bottle and are unsightly.

The present invention has been made in view of the above-mentioned circumstances, and an accurate mouthpiece portion, and a preform having no concave portion formed therein can be molded, and an accurate bottom portion of the preform without excess resin overflowing. It is an object of the present invention to make it possible to mold a preform into a bottom without wrinkles or the like.

[Means for solving the problem]

The invention according to claim 1 is characterized in that one end portion 2 of a cylindrical body 1 made of a thermoplastic polyester having ethylene terephthalate as a main repeating unit, or a multilayer structure in which a layer made of the polyester is a main component,
The cylindrical body 1 is heated to a temperature equal to or higher than the glass transition temperature and equal to or lower than the crystallization temperature, and the heated one end 2 of the cylindrical body 1 is provided with a forming recess 11 such as a screw or a flange on the inner surface and formed as a split mold. The male mold 12 for the cylindrical part is inserted into the female mold 10 for the cylindrical part, and the other end 3 of the cylindrical body 1 is then inserted into the cylindrical pressing tool. At 13, a method of forming a mouthpiece portion of a preform in which the mouthpiece portion 30 formed with a screw, a flange, or the like at one end 2 of the cylinder body 1 by pressing in the axial direction of the cylinder body 1 is used.

The invention according to claim 2 is characterized in that the female mold 10 for a mouth portion is heated to a temperature higher than a crystallization temperature of a thermoplastic polyester having ethylene terephthalate as a main repeating unit and lower than a melting point temperature, thereby forming a male mold 12 for a mouth portion. The method according to claim 1, wherein the one end portion (2) is formed into the barrel portion (30) while maintaining the temperature below the crystallization temperature of the thermoplastic polyester containing ethylene terephthalate as a main repeating unit.

The invention according to claim 3 is that the other end portion 3 of the cylindrical body 1 made of thermoplastic polyester containing ethylene terephthalate as a main repeating unit, or a layer made of the polyester, is a glass transition point temperature or higher. To a temperature below the crystallization temperature and only the tip to the melting temperature, and heat the other end 3 of the cylinder 1 to a female mold for bottom.
20 and a male mold 22 for the bottom
Is inserted, and with the tip of the male mold for bottom 22 being spaced from the inner bottom surface of the female mold for bottom 20, the mouthpiece 30 of the cylinder 1 is pressed into the cylinder pressing tool 13. Thus, a method of forming the bottom of the preform in which the other end 3 of the cylinder 1 is pressed into the bottom 31 by pressing in the axial direction of the cylinder 1.

(Operation)

The invention according to claim 1 is characterized in that one end 2 of a multilayer body 1 made of a thermoplastic polyester having ethylene terephthalate as a main repeating unit or a layer made of the polyester is mainly used as a glass transition point temperature ( About 70 ℃)
By heating to a temperature below the crystallization temperature (approximately 170 ° C.) and softening the above, one end 2 of the heated and softened cylindrical body 1 is provided with a concave portion 11 for molding such as a screw or a flange on the inner surface, and is split. The other end 3 of the cylinder 1 is pressed into the cylinder 1 by inserting the male mold 12 for the cylinder into the cylinder 1 while inserting it into the female mold 10 for the cylinder formed as a mold. When the tool 13 is pressed in the axial direction of the cylinder 1, the softened one end 2 of the cylinder 1 is pushed into the recessed portion 11 of the sealed female mold 10 for a mouthpiece, and outside the one end 2, Screws, flanges, etc., formed in the female mold 10 for the barrel portion are accurately formed, and the inside of one end 2 is a male mold for the barrel portion.
According to the outer surface of the front end portion of the twelve, the mouthpiece portion 30 formed is formed.

According to a second aspect of the present invention, there is provided the mouthpiece according to the first aspect.
At the time of molding, the female mold 10 for the barrel is heated to a temperature (about 170 ° C. to about 260 ° C.) above the crystallization temperature of the thermoplastic polyester having ethylene terephthalate as a main repeating unit and below the melting point. Since the male die 12 is formed while maintaining the temperature below the crystallization temperature (about 170 ° C.) of thermoplastic polyester using ethylene terephthalate as a main repeating unit, the outside of the cylindrical portion 30 is completely Crystalline, and the inside becomes amorphous.

The invention according to claim 3 is characterized in that the other end portion 3 of the cylindrical body 1 made of a thermoplastic polyester having ethylene terephthalate as a main repeating unit, or a layer composed of the polyester, is used as a glass transition point temperature. (70 ° C.) or higher and softened by heating to a temperature lower than the crystallization temperature (about 170 ° C.), and only the tip is heated and melted to a temperature higher than the melting point (about 260 ° C.). The other end 3 is inserted into the bottom female mold 20 and the bottom male mold is inserted into the cylindrical body 1.
In a state in which a space is maintained between the tip of the female mold 22 and the inner bottom surface of the female mold 20 for the bottom part, the cylindrical part 30 of the cylindrical body 1 is
When the cylindrical body 1 is pressed in the axial direction, the heated other end 3 of the cylindrical body 1 is pushed into the gap between the inner bottom surface of the female mold 20 for the bottom part and the tip of the male mold 22 for the bottom part. , And a bottom portion 31 having a correct shape is formed.

The thermoplastic polyester having ethylene terephthalate as a main repeating unit as referred to in the present invention is usually terephthalic acid in which 80% by mole or more, preferably 90% by mole or more of the acid component, and 80% by mole, preferably 90% by mole of the glycol component. The above means a polyester that is ethylene glycol,
Isophthalic acid, diphenyl ether 4,4'-dicarboxylic acid, naphthalene 1,4- or 2,6
-Dicarboxylic acid, adipic acid, sebacic acid, decane 1,10
Dicarboxylic acid, hexahydroterephthalic acid, and other glycol components such as propylene glycol, 1,4-butanediol, neopentyl glycol, diethylene glycol, 1,6-hexylene glycol, cyclohexanedimethanol, 2,2-bis (4 -Hydroxyphenyl) propane, 2,2-bis (4-hydroxyethoxyphenyl) propane, or a polyester containing P-oxybenzoic acid, P-hydroethoxybenzoic acid, or the like as an oxyacid.

Incidentally, the polyester in the present invention is a coloring agent, an ultraviolet absorber, an antistatic agent, a thermooxidative deterioration inhibitor, if necessary,
Additives such as antibacterial agents and lubricants can be contained in an appropriate ratio.

The thermoplastic polyester of the present invention needs to have an intrinsic viscosity of 0.55 or more, preferably 0.6 or more, more preferably 0.7 to 1.4. The intrinsic viscosity is an intrinsic viscosity measured at 30 ° C. of a solution in which a polyester is dissolved in a phenol / tetrachloroethane mixed solvent (6/4 weight ratio). When the intrinsic viscosity is less than 0.55, it is difficult to obtain a transparent amorphous molded product at the time of parison molding, and the mechanical strength becomes insufficient.

〔Example〕

FIG. 1 to FIG. 9 are diagrams for explaining an embodiment of the invention according to claims 1 to 3, and the cylindrical body 1 used in the embodiment of the invention according to claim 1 is extruded into five layers. A molded pipe is used, the first innermost layer is polyethylene terephthalate, the next second layer is an adhesive layer made of adhesive polyolefin, and the next third layer is ethylene vinyl acetate copolymer The next fourth layer is the same adhesive layer as the second layer, and the fifth outermost layer is the same polyethylene terephthalate as the first innermost layer.

And this cylinder 1 has an inner diameter of 19 mm, an outer diameter of 25 mm, and a length of
It is formed to 106mm.

Then, one end 2 of the cylindrical body 1 is inserted into an annular recess of the one end heating device 7 shown in FIG. 2 having an electric heater to heat the cylindrical body 1 from inside and outside. The heating temperature is above the glass transition temperature of polyethylene terephthalate (about 70 ° C.) and below the crystallization temperature (about 170 ° C.), preferably about 90 ° C. to about 150 ° C. .

Further, what is important here is the amount of the heated portion of the one end portion 2, and the amount of the heated portion is determined when the female portion 10 is inserted into the female die 10 for the next step. The amount required to fill the gap left in the female mold 10 for use, and the amount required to fill this gap is the amount of screw formed in the female mold 10 for the mouthpiece. In any case, the amount is preferably slightly larger than that of the gap layer.

Next, the one end 2 heated as described above is provided with a recess 11 for forming a screw and a flange on the inner surface shown in FIG.
In addition, the male die 12 for a cylindrical portion formed in the cylindrical body 1 is inserted into the female die 10 for a cylindrical portion formed as a split mold, and the distal end of the male die 12 for a cylindrical portion is formed. Insert so that it contacts the bottom of mold 10.

Next, the end face of the other end 3 of the cylindrical body 1 is
Then, the cylindrical body 1 is pressed in the axial direction of the cylindrical body 1 toward the female mold 10 for the cylindrical section, and the cylindrical section 30 of the preform on which the screws and flanges are formed as shown in FIGS. Molded.

The embodiment of the invention according to claim 2 heats the one end 2 of the cylindrical body 1 in the same manner as the embodiment of the invention according to claim 1, and at the same time, simultaneously performs the female mold 10 for the mouth section. At a temperature above the crystallization temperature of polyethylene terephthalate and below the melting point (about 170 ° C. to about 260 ° C.), preferably about 200 ° C. to about 250 ° C.
Then, the male mold 12 for the mouth portion is kept at a temperature lower than the crystallization temperature of polyethylene terephthalate (about 170 ° C.). Thus, a mouthpiece portion 30 of a preform was formed.

In the embodiment of the invention described in claim 3, the other end 3 of the cylindrical body 1 shown in FIG. 5 formed by the embodiment of the invention described in claim 1 is provided with an electric heater. Is inserted into the annular recess of the other end heating device 17 shown in FIG.
Heat from inside and outside.

The range of the possible heating temperature of the other end 3 is the same as the range of the heating temperature of the one end 2 of the cylindrical body 1 in the above-described embodiment, except that the tip of the other end 3 is fused. Bottom 31
In this embodiment, the tip of the other end 3 is set at 270 ° C., which is about 260 ° C. or higher.

The fact that the amount of heating of the other end 3 is important here is the same as in the molding of the mouthpiece section 30 described above. When inserted into the female mold 20, the amount required to fill the gap left between the female mold 20 for the bottom and the male mold 22 for the bottom is required. The amount varies depending on the shape of the bottom portion 31, that is, a shape such as a hemispherical shape, an elliptical shape, a flat bottom shape, or the like, but is preferably an amount slightly larger than the amount of the gap.

Next, the heated other end 3 of the cylindrical body 1 is inserted into a female mold 20 for the bottom, which has a semi-spherical inner bottom surface as shown in FIG. This cylinder 1
The male mold 22 for the bottom is inserted into the inside, and the gap required for forming the bottom 31 of the preform between the tip of the male mold 22 for the bottom and the inner bottom surface of the female mold 20 for the bottom. Is held, the end face of the mouthpiece portion 30 of the cylinder 1 is pressed in the axial direction of the cylinder 1 toward the bottom female mold 20 by the cylinder pressing tool 13 so that the bottom 31 is hemispherical. Was molded.

And the outer diameter of the threaded portion of the mouthpiece 30 of the molded preform is 28 mm, the thickness of the bottom 31 is 3 mm, the total length is 100 mm,
This preform is for a 350 ml bottle.

FIG. 10 shows a preform formed in another embodiment. The bottom 31 is the same as that in FIG. 9, but the mouthpiece 30 has only a flange formed therein. is there.

Further, the pressing of the cylinder 1 in the axial direction may be performed by stopping the cylinder pressing tool 13 and pressing down the female mold 10 for the mouth portion and the female mold 20 for the bottom.

〔The invention's effect〕

The present invention relates to a method for forming a cylindrical structure made of a thermoplastic polyester having ethylene terephthalate as a main repeating unit or a layer formed of the polyester into a cylindrical body 1 and then forming one end 2 of the cylindrical body 1 and other components. The end 3 is heated, and the inside of the female mold 10 for the mouth section and the inside of the female mold 20 for the bottom are
Each of the molds and the cylinder 1 are pressed in the axial direction of the cylinder 1 to form a mouthpiece portion 30 of the preform, and a bottom portion, respectively.
31 is accurately formed, and even in the case of a multilayer preform, the barrel portion 30 and the bottom portion 31 can be molded without greatly disturbing each layer of the multilayer, and the inside of the barrel portion 30 can be formed. No annular recesses occur on the bottom
It is possible to prevent wrinkles from occurring in the base material 31 and to prevent excess resin from overflowing during molding.

Further, in the invention of claim 2, in the molding of the barrel portion 30, a thermo-crystalline (whitening) process for improving the heat resistance of the barrel portion 30 which has been conventionally performed in a separate process is simultaneously performed. In addition to being able to do this, the entire mouth of the mouthpiece 30 is made crystalline and the inside is made non-crystalline, instead of being crystallized as if the conventional mouthpiece 30 was crystallized. It was possible to improve the impact resistance and the heat resistance.

[Brief description of the drawings]

1 to 9 are views for explaining one embodiment of the invention according to claims 1 to 3, wherein FIG. 1 is a view showing a cylindrical body,
FIG. 2 is a diagram showing a heating process of one end portion, FIGS. 3 and 4 are diagrams showing a process of forming one end portion into a mouthpiece portion, and FIG. FIG. 6, FIG. 6 is a diagram showing a heating process of the other end, FIGS. 7 to 8 are diagrams showing a process of molding the other end to the bottom, FIG. 9 is a diagram showing a molded preform, FIG. 10 is a view showing a preform formed according to another embodiment. DESCRIPTION OF SYMBOLS 1 ... Cylindrical body, 2 ... One end part, 3 ... Other end part, 10 ... Female mold for mouthpiece part, 11 ... Recess, 12 ... Male mold for mouthpiece part, 13 ... Cylinder Body pressing tool, 20: female mold for bottom part, 22: male mold for bottom part, 30: mouthpiece part, 31: bottom part.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B29C 49/00-49/80 B29B 11/10 B29C 57/00-57/12

Claims (3)

(57) [Claims] An end portion 2 of a cylindrical body 1 made of a thermoplastic polyester having ethylene terephthalate as a main repeating unit or a layer made of the polyester is mainly crystallized at a temperature equal to or higher than a glass transition temperature. Heated to a temperature equal to or lower than the temperature, and the heated one end 2 of the cylindrical body 1 is
A concave portion 11 for forming a screw, a flange or the like is provided on the inner surface, and is inserted into a female mold 10 for a barrel portion formed as a split mold, and a male mold 12 for a barrel portion is inserted into the cylindrical body 1. Then, the other end 3 of the cylindrical body 1 is pressed in the axial direction of the cylindrical body 1 by the cylindrical body pressing tool 13 so that the one end 2 of the cylindrical body 1 is formed with a screw, a flange or the like. A method for forming a mouth section of a preform for forming the section 30. 2. A male mold for a mouth portion is heated to a temperature higher than a crystallization temperature of a thermoplastic polyester having ethylene terephthalate as a main repeating unit and lower than a melting point temperature.
2. A method for molding a barrel portion of a preform according to claim 1, wherein the one end portion 2 is molded into the barrel portion 30 while maintaining the temperature at or below the crystallization temperature of a thermoplastic polyester containing 12 as a main repeating unit of ethylene terephthalate. 3. The other end 3 of a cylindrical body 1 made of a thermoplastic polyester having ethylene terephthalate as a main repeating unit, or a layer made of the polyester, is crystallized at a glass transition temperature or higher. Heated to a temperature not higher than the temperature, and only the front end is heated to the melting temperature. The heated other end 3 of the cylindrical body 1 is inserted into the female mold 20 for the bottom, and the bottom is inserted into the cylindrical body 1. The male mold 22 for the bottom is inserted, and with the tip of the male mold 22 for the bottom being spaced from the inner bottom surface of the female mold 20 for the bottom, the mouthpiece 30 of the cylindrical body 1 is removed. A method of forming the bottom of a preform in which the cylindrical body 1 is pressed in the axial direction of the cylindrical body 1 to form the other end 3 of the cylindrical body 1 into a bottom 31.