JPS60927A - Crystallizing method of mouth part of bottle - Google Patents

Abstract

PURPOSE:To crystallize the titled mouth part without generating deformation of of mouth part and moreover effectively, by making the mouth part of a bottle heat and crystallize by raising a heating temperature of the same successively after the mouth part of the bottle has been heated at a lower heating temperature at a first step. CONSTITUTION:At the time of making the mouth part of a preform for molding a blown bottle made of polyester resin or said blown bottle heat and crystallize, heating is divided into a plurality of steps, the foregoing matter is heated gradually at a low heating temperature at a first step (it is desirable to make a temperature of the mouth part itself arrive at the temperature of 100-120 deg.C in 15-40sec) and heated and crystallized by raising the heating temperature at a second step in succession to the above step (it is desirable that the mouth part arrives at the temperature of 160-180 deg.C in 20-40sec). EFFECT:An internal distortion of a mouth part is eliminated without deforming the mouth part at a first step and the same is crystallized rapidly at a sufficient crystallizing speed at a second step.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of heating and crystallizing the spout of a polyester resin blow bottle or preform.

In order to impart heat resistance to the spout of a polyester resin blow bottle, the spout is heated to crystallize it during the blow bottle or the preform stage for molding the blow bottle. . However, with conventional heating methods, when heated at a high heating temperature, the internal strain remaining during preform molding recovers, causing the top surface and threaded portion of the spout to become wavy, resulting in incomplete sealing with the cap. There was a problem. On the other hand, lowering the heating temperature to avoid deformation increases the time required for crystallization.
Manufacturing efficiency decreases.

The purpose of the present invention is to solve the above-mentioned problems and to efficiently crystallize the spout without deformation. In a method of crystallizing a spout by heating it, the heating is divided into multiple stages.
By gradually heating at a low heating temperature in the second stage, and then increasing the heating temperature to crystallize in the second stage, by gradually heating at a low heating temperature in this stage, the internal strain is reduced without deforming the spout. It has the effect of being removed. Then, in the second stage, the heating temperature is increased by 7, so that combined with the preliminary temperature increase in the first stage, it is possible to quickly crystallize at a sufficient crystallization rate, and as a result, internal strain is removed in the first step, so the spout does not deform.

The heating temperature in the first stage varies depending on the molding conditions of the preform, the wall thickness, etc., but the temperature of the spout made of polyethylene terephthalate resin at approximately room temperature is 100~15~15%. A degree that can be gradually reached in 30 seconds is preferable because the spout does not deform and is sufficient as preliminary heating.

In the λth stage, following the first stage, the heating temperature is increased and
It is preferable to allow the spout to reach a temperature of /60 to igo°C in 0 to 10 seconds. Under such heating conditions, the degree of crystallinity of the spout reaches 30% usually within 100 seconds from the start of the first stage heating, and the heat resistance is improved.

In the present invention, a purine or blow bottle made of polyester resin is a preform made of polyester resin such as polyethylene terephthalate or a copolymer having ethylene terephthalate as a main repeating unit into a tubular shape by injection molding, extrusion molding, etc. centre.

Renovate the glass transition temperature of polyester resin or higher,
A bottle biaxially stretched and blow-molded at a temperature below the melting temperature is preferably used. This bottle may be heat-fixed in advance in parts other than the spout.

Next, referring to the accompanying drawings, FIG. 1 is a schematic plan view showing an example of a heating device for carrying out the method of crystallizing a bottle cap of the present invention, and FIG. It is an enlarged view of the U-t+ cross section.

As shown in Figures 1 to λ, the entire heating device has three sections a
, b, and C, and each section has a pair of rod-shaped near-infrared heaters /a, /b, and IC facing each other.
is installed. A mandrelco that moves in the direction of arrow A while rotating between these heaters is arranged.

Furthermore, a heat shield plate 3 is installed above the heater to prevent heat from being applied to areas other than the spout. Heater /a, /b,
Each IC can independently adjust the current to control the heating temperature. As shown in FIG. 2, the mandrel λ has a diameter equal to the inner diameter of the spout l of the preform, etc., and is transported while being inserted into the preform.

This is to prevent deformation of the spout from the inside during heating. The mandrel λ is made of heat-resistant plastic such as polypropylene, fluoride, ethylene, polyacetal, polyamide, polycarbonate, polypropylene, etc. The surface of the mandrel λ is more slippery than that of metal, and it is suitable for preforms, etc. Insertion and withdrawal are smooth. Further, a support rod 2/ may be provided above the mandrel, in contact with the inner bottom surface of the preform, etc., to support the weight of the preform.

As heaters /a, /b, /a-, in addition to rod-shaped heaters such as infrared heaters as shown in the figure, there are also heaters that substantially reduce the heating temperature, such as induction heating using circumferential temporary electrodes, hot air heating, contact heating, or a combination of these. Any suitable method can be used as long as it can be controlled.

As explained above, according to the present invention, the spout of the JtbfJ Soliester resin blow bottle or its brimstone is heated at a low heating temperature in the first step. After doing so,
Raise the heating temperature and add, q! 5. Since the crystals are allowed to immerse, the plug gIS is not deformed, and moreover, it is quickly crystallized.

This will be explained in more detail below using experimental examples.

Experimental Example: The heating device arranged as shown in Figure 1 was heated to the length of the stopper part. : -121Inun, thread diameter 2gIII
jI+, a polyethylene terephthalate preform with an inner diameter core of 6 cities was heated. Heater /a, /b, /
c is a near-infrared heater (λOOV, /Klv)
, length 33 cm).

The time taken for each section of the preform to be transferred by the mandrelco is 30 seconds.

In this device, as shown in Table 1 A/~10, the heater current is set in section C to L/ampere~3, S ampere, b
The heating temperature is controlled by adjusting the section A in the range of 3.5 amperes, C section 1, θ ~ ko, θ ampere, insert the preform into the mandrelco and pass through the 3 sections,
The spout was crystallized until it became sufficiently white in appearance (crystallinity of 30% or more).

For the preform that has been crystallized, the unevenness of the top surface of the spout part G is observed using a reading microscope, and if the difference between the concave part and the convex part is θ/ntIn or more, it is judged as defective, and the results are shown in Table 1. 200 pieces were tested under each condition of 47 to /θ shown in , and the number of defective pieces was displayed.

Table 1 Ratio As is clear from Table 1, as shown by jib, / ”'-9, the heat was heated at a relatively low heating setting (-?, , ? ampere or higher) in section C, that is, in the first stage. The number of defective pieces is θ~36 pieces, which is less deformed than the one heated from the beginning at high temperature (JS ampere) (number of defective pieces: 93 pieces).Also, let the heater current in section C be la, and the heater current in section b be lb. When the heating capacity P for section b of section C is expressed as Ia2/Ib2 x 10O (%), P is 3
In the flat 3-70 condition between 0% and 70%, the number of defective pieces is 0.
It is particularly small with ~3 pieces, which is particularly preferable.

The purpose of adjusting the heater electric bit in section C is to suppress the rise in temperature of the spout and keep it at a substantially constant temperature so that the surface of the spout does not melt due to overheating.

Also, the heater currents in each section of a, , and C are all J,
? When a similar test was conducted with the same heating capacity as ampere, the number of defective wires was 0, but only a slight cloudy whitening occurred after passing through section C, and the degree of crystallization was small.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view showing an example of an apparatus for carrying out the method of crystallizing a bottle cap according to the present invention, and FIG. 2 is an enlarged cross-sectional view taken along line 1-1 in FIG.

Claims (1)

[Claims] In a method of heating and crystallizing the spout of a polyester resin blow bottle or a preform for molding the flow bottle, heating is divided into multiple stages, and in the seventh stage, heating is gradually performed at a low heating temperature, A method for crystallizing a spout portion, which is characterized in that the heating temperature is subsequently increased in a second step to perform heating crystallization.