JP6296341B2 - Preform, plastic bottle and manufacturing method thereof - Google Patents

Description

  The present invention relates to a preform, a plastic bottle, and a method for producing a plastic bottle.

  Conventionally, a plastic bottle has been manufactured by biaxially stretch blow molding a preform (preliminary molded body) made of PET or the like produced by injection molding. There are various types of such plastic bottles, and examples thereof include a pressure-resistant plastic bottle filled with a carbonated beverage or the like.

  In general, a synthetic resin such as PET increases in strength by being stretched. When an internal pressure is applied to such a plastic bottle made of synthetic resin, the plastic bottle receives a force expanding in the radial direction and expands. For example, when a plastic bottle is filled with a carbonated beverage and sealed, after a certain period of time has elapsed, the full column capacity of the plastic bottle after opening is greater than the full column capacity before filling with the carbonated beverage. There is a case. Thus, the phenomenon that the plastic bottle swells due to the internal pressure of the plastic bottle is called creep deformation.

  However, when creep deformation occurs in a plastic bottle, for example, in a plastic bottle filled with a carbonated beverage, there arises a problem that carbon dioxide in the beverage is likely to escape. For this reason, in general, plastic bottles are required to have improved durability against creep deformation (creep resistance). Further, when a preform is blow-molded to produce a plastic bottle, it is required that the blow-moldability is good.

Special table 2008-540185 gazette

  The present invention has been made in consideration of such points, and provides a preform, a plastic bottle, and a method for manufacturing the same, which can reduce creep deformation and can improve blow moldability. With the goal.

The present invention includes a preform having a mouth portion having a support ring and a body portion connected to the mouth portion, the body portion including a neck portion on the support ring side and a body middle portion connected to the neck portion. And a bottom part connected to the middle part of the trunk, where T is the thickness of the middle part of the trunk, L is the length of the trunk part, and D is the diameter of the middle part of the trunk. The value of D is equal to or greater than 12.7, and the torso neck distance, which is a ratio of the distance from directly below the support ring to the entire length of the torso, is X, and the torso neck distance is X. The cross-sectional area ratio of the body portion at the position is Y, and the cross-sectional area ratio Y at the portion having the smallest cross-sectional area of the body portion is 0%, and the cross-sectional area ratio Y at the portion having the largest cross-sectional area is 100%. when, in 16% ≦ X ≦ 22% of the range, Y ≧ -0.0088X + A preform, characterized in that the relationship of 0.7276X ³ -22.656X ² + 316.6X-1586.9 is established.

  The present invention is the preform characterized in that the thickness T of the middle part of the trunk is 3.8 mm or less.

  The present invention is the preform characterized in that the trunk neck lower distance X at the location where the cross-sectional area ratio Y is 95% is 18.8% to 20.2%.

  The present invention is the preform characterized in that the trunk neck lower distance X at the location where the cross-sectional area ratio Y is 90% is 16.9% to 17.8%.

  In the present invention, the difference between the trunk neck lower distance X at a location where the cross-sectional area ratio Y is 100% and the trunk neck lower distance X at a location where the cross-sectional area ratio Y is 90% is 5.6% to 8%. A preform characterized by being 0.0%.

  The present invention is a plastic bottle produced by blow-molding a preform.

The present invention includes a mouth portion having a support ring, and a body portion connected to the mouth portion, the body portion including a neck portion on the support ring side, a body middle portion connected to the neck portion, A bottom part connected to the middle part of the trunk, where T is the thickness of the middle part of the trunk, L is the length of the trunk part, and D is the diameter of the middle part of the trunk. Is equal to or greater than 12.7, and the body neck length below X is the ratio of the distance from directly below the support ring to the overall length of the body, and the position at the position where the body neck length is X. When the cross-sectional area ratio of the body portion is Y, the cross-sectional area ratio Y at the portion having the smallest cross-sectional area of the body portion is 0%, and the cross-sectional area ratio Y at the portion having the largest cross-sectional area is 100%. in% ≦ X ≦ 22% of the range, Y ≧ -0.0088X ⁴ + 0.7276X ³ Preparing a preform which satisfy the relationship of 22.656X ² + 316.6X-1586.9, plastic bottles, characterized in that the preform and a process for producing a plastic bottle by blow molding It is a manufacturing method.

According to the present invention, the value of T × L / D is 12.7 or more, where T is the thickness of the middle part of the trunk, L is the length of the trunk, and D is the diameter of the middle part of the trunk. And the torso neck distance is X, the torso section cross-sectional area ratio at the position at which the torso neck distance is X is Y, and the torso section ratio Y at the smallest cross-sectional area of the torso is Assuming that the cross-sectional area ratio Y at the location where the cross-sectional area is 0% is 100%, Y ≧ −0.0088X ⁴ + 0.7276X ³ −22.656X ² +316. The relationship 6X-1586.9 is established. Thereby, it is possible to suppress the occurrence of creep deformation in the plastic bottle, and it is possible to improve the blow moldability when the preform is blow-molded to produce the plastic bottle.

FIG. 1 is a cross-sectional view showing a preform according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a preform according to an embodiment of the present invention. FIG. 3 is a front view showing a plastic bottle manufactured using a preform according to an embodiment of the present invention. FIG. 4 is a schematic sectional view showing a state in which the preform is heated. FIG. 5 is a graph showing a relationship between the value of the thickness T × the length L of the trunk portion / the diameter D of the trunk middle portion and the increase amount of the full capacity of the plastic bottle. FIG. 6 is a graph showing the relationship between the wall thickness of the preform middle part and the cooling time of the preform during injection molding. FIG. 7 is a graph showing a change in the neck portion of a preform according to an example and a comparative example. FIG. 8 is a graph showing a change in the neck of a preform according to an example and a comparative example (partially enlarged view of FIG. 7). FIG. 9 is a front view showing a plastic bottle (square bottle). FIG. 10 is a front view showing a plastic bottle (round bottle).

  Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 are views showing an embodiment of the present invention. In the following drawings, the same portions are denoted by the same reference numerals, and some detailed description may be omitted.

  First, an outline of a preform according to the present embodiment will be described with reference to FIGS. FIG. 1 and FIG. 2 are sectional views showing a preform according to an embodiment of the present invention, and show the same preform.

  As shown in FIG. 1, the preform 10 includes a mouth part 11 having an opening 15 and an annular support ring 12, and a body part 20 connected to the mouth part 11.

  Among these, on the outer periphery of the mouth portion 11, there is provided a screw portion 13 for screwing a cap (not shown) after the preform 10 is biaxially stretch blow-molded to produce a plastic bottle 40 (FIG. 3). . The shape of the mouth portion 11 may be a conventional one (for example, one corresponding to the PCO1810 standard).

  The body portion 20 is a portion that is inflated to form a bottle by blow molding, and includes a neck portion 21 on the support ring 12 side, a body middle portion 22 coupled to the neck portion 21, and a bottom portion 23 coupled to the body middle portion 22. And have.

  The neck portion 21 has a shape in which the thickness and the body diameter change in the length direction. In this case, the neck portion 21 has a shape that gradually decreases in diameter from the mouth portion 11 side toward the body middle portion 22 side. However, the present invention is not limited to this, and the diameter of the neck portion 21 may gradually increase from the mouth portion 11 side toward the trunk middle portion 22 side.

  The trunk middle portion 22 has a substantially cylindrical shape, and has a shape in which the trunk diameter and the wall thickness hardly change. Note that when the preform 10 is manufactured by injection molding, the barrel middle portion 22 is made so that the barrel diameter on the bottom portion 23 side is slightly thinner than the neck portion 21 side in order to provide a draft for easy removal from the mold. It may be done. The wall thickness may be slightly changed by the same logic.

  The bottom 23 is substantially hemispherical in the example of FIG. 1, but may be conical, cylindrical with rounded corners, or other shapes. In addition, although the gate at the time of producing the preform 10 by injection molding is provided in the bottom part 23, the shape which abbreviate | omitted the gate is shown in FIG.

  In FIG. 1, it is preferable that the wall thickness T in the trunk middle part 22 of the trunk part 20 is 3.8 mm or less. By making the wall thickness T 3.8 mm or less, it is possible to prevent the distance until the heat of the molten synthetic resin is transferred to the blow molding die when the plastic bottle 40 is produced by blow molding, and cooling. Time can be shortened. Thereby, the malfunction that manufacturing cycle time becomes long and manufacturing efficiency falls can be prevented. In addition, when the wall thickness in the trunk middle part 22 changes in the length direction, the wall thickness T is defined by the wall thickness in the longitudinal center part of the trunk middle part 22.

  Moreover, the length L of the trunk | drum 20 is the distance between the bottom face of the support ring 12, and the front-end | tip part of the bottom part 23, and it is preferable to set it as 40 mm or more and 135 mm or less.

  Furthermore, the diameter D of the trunk portion 20 of the trunk portion 20 is the diameter at the thickness center of the trunk middle portion 22 and is preferably 13 mm or more and 31 mm or less. In addition, when the diameter in the trunk | drum middle part 22 changes to a length direction, the diameter D is defined by the thickness center diameter in the longitudinal direction center part of the trunk | drum middle part 22. FIG.

  In this case, a relationship of T × L / D ≧ 12.7 is established among the thickness T of the barrel middle portion 22, the length L of the barrel portion 20, and the diameter D of the barrel middle portion 22. By setting the value of T × L / D to 12.7 or more, the preform 10 is blow-molded and the plastic bottle 40 is manufactured, and then the plastic bottle 40 is subjected to creep deformation (deformation due to increase in the full capacity). Occurrence can be suppressed.

  The reason why the creep deformation is suppressed by setting the value of T × L / D to 12.7 or more is as follows. Generally, it is known that the strength of a synthetic resin such as PET increases when it is stretched. When an internal pressure is applied to the plastic bottle, the plastic bottle receives a force that expands in the radial direction and expands (crepes). In order to suppress this, a preform made of synthetic resin such as PET may be stretched greatly in the radial direction during blow molding. This is because when the P preform is greatly stretched in the radial direction during blow molding, the plastic bottle after blow molding is restrained from being stretched in the radial direction by internal pressure. For that purpose, if the thickness T of the trunk middle part 22 of the preform 10 is increased, the stretching in the radial direction is increased. On the contrary, when the diameter D of the trunk middle portion 22 is increased, the radial stretching is reduced. Further, the preform 10 is extended not only in the radial direction but also in the height direction of the bottle at the time of blow molding. However, when the preform 10 is extended in the height direction, the thickness of the preform 10 is reduced, and thus the extension in the radial direction is small. Become. Therefore, the stretching in the height direction is small, that is, if the length L of the body portion 20 is long, the stretching in the radial direction becomes large. In this way, the preform is greatly stretched in the radial direction at the time of blow molding by increasing the thickness T of the barrel middle portion 22, increasing the length L of the barrel portion 20, and decreasing the diameter D of the barrel middle portion 22. The plastic bottle after blow molding can be prevented from stretching in the radial direction.

  Further, in FIG. 2, the trunk neck distance, which is the ratio of the distance from directly below the support ring 12 to the total length of the trunk section 20, is X, and the trunk section at a position where the trunk neck distance is X. Let the cross-sectional area ratio be Y. That is, the torso neck distance X is the support of the neck portion 21 when the position of the neck portion 21 directly below the support ring 12 in the neck portion 21 is 0% and the position of the tip of the bottom portion 23 is 100%. The distance from directly below the ring 12 (X = 0% position) is expressed as a ratio (0% ≦ X ≦ 100%). Further, the cross-sectional area ratio Y is defined as Smin, where the horizontal cross-sectional area of the body 20 is the smallest when the body neck length X is 0% to 100%, and the value at the largest area. Smax is obtained by the formula (SM−Smin) / (Smax−Smin) where SM is the value of the cross-sectional area when the trunk neck distance X = M. In addition, the value of the cross-sectional area SM can be obtained by calculation from the body diameter (DM) and the wall thickness (TM) at the location. That is, the cross-sectional area ratio Y in the portion having the smallest cross-sectional area in the body portion 20 is 0%, and the cross-sectional area ratio Y in the portion having the largest cross-sectional area is 100%.

In this case, in the range of 16% ≦ X ≦ 22%, the relationship Y ≧ −0.0088X ⁴ + 0.7276X ³ −22.656X ² + 316.6X−1586.9 is established (0 ≦ X ≦ 100). When the above relationship is established, the blow moldability can be improved when the preform 10 is blow-molded to produce the plastic bottle 40. Specifically, when the preform 10 is blow-molded, it becomes easy to appropriately extend the neck portion 21 of the preform 10, so that the adjustment allowance for the wall thickness distribution of the plastic bottle 40 depending on the blow-molding conditions becomes wider. A high-quality plastic bottle 40 can be produced, and blow molding defects can be reduced.

  The reason why the blow moldability of the preform 10 can be improved when the above relationship is established is as follows. That is, the region where the trunk neck distance X is about 20% is a region below the neck 21 and its cross-sectional area expands toward the trunk middle portion 22. Y does not satisfy the above relational expression. While it changes rapidly, two regions of the neck portion 21 of the preform 10 that are easily stretched by blow molding and a portion that is difficult to stretch are generated. On the other hand, if the above relational expression is satisfied, Y gradually changes. This is because the ease of elongation also changes gradually.

  Furthermore, the trunk neck lower distance X at the location where the cross-sectional area ratio Y is 95% is 18.8% to 20.2%, and the trunk neck lower distance X at the location where the cross-sectional area ratio Y is 90%. It is preferable that it is 16.9%-17.8%. Furthermore, the difference between the trunk neck lower distance X at the location where the cross-sectional area ratio Y is 100% and the trunk neck lower distance X at the location where the cross-sectional area ratio Y is 90% is 5.6% to 8. It is preferably 0%.

  In addition, it is preferable to use a thermoplastic resin, especially PE (polyethylene), PP (polypropylene), PET (polyethylene terephthalate), PEN (polyethylene naphthalate) as the main material of the preform 10, and a biomass-based plastic derived from plants. For example, PLA (polylactic acid) can also be used.

  Next, an example of a plastic bottle produced by biaxially stretching blow molding such a preform 10 will be described with reference to FIG. Needless to say, the plastic bottle manufactured using the preform 10 is not limited to this. However, the present invention is not limited to this, and there are also bottles as shown in FIGS.

  In FIG. 3, the plastic bottle 40 includes a mouth part 41, a cylindrical body part 42 provided below the mouth part 41, and a bottom part 43 provided continuously to the body part 42. A neck portion 44 is provided between the mouth portion 41 and the body portion 42. A shoulder portion 48 is formed between the neck portion 44 and the trunk portion 42.

  Further, a screw portion 46 (corresponding to the screw portion 13 of the preform 10 described above) for screwing a cap (not shown) is provided on the outer periphery of the mouth portion 41, and the screw portion 46 below the outer periphery of the mouth portion 41. Is formed with an annular support ring 47 projecting outward (corresponding to the support ring 12 of the preform 10 described above).

  The bottom 43 has a so-called petaloid bottom shape. That is, the bottom 43 has a plurality of petaloid legs 45 that are arranged at equal intervals in the circumferential direction and project downward. The number of petaloid legs 45 is preferably 5 to 9 from the viewpoint of stably erecting the plastic bottle 40 and improving the moldability of the lightweight bottle.

  The size (capacity) of the plastic bottle 40 is not limited, and may be any size bottle, but may be 500 ml to 600 ml, for example. The thickness of the plastic bottle 40 can be 0.15 mm to 0.50 mm at the petaloid leg 45 of the bottom 43.

  Next, the operation (method for manufacturing a plastic bottle) of the present embodiment having such a configuration will be described.

  First, pellets made of thermoplastic resin such as PET (polyethylene terephthalate) are put into an injection molding machine (not shown), and the pellets are heated and melted by the injection molding machine. Thereafter, the pellets become molten plastic and are injected and pressed into an injection mold having an internal shape corresponding to the preform 10.

  After the elapse of a predetermined time, the molten plastic is cooled and solidified in the injection mold, and the preform 10 is formed. Thereafter, the injection mold is separated, and the preform 10 shown in FIGS. 1 and 2 is taken out from the injection mold.

  Next, the preform 10 is heated in a heating section in the blow molding machine (heating process: see FIG. 4). In this heating step, the preform 10 is heated to a temperature of, for example, 90 ° C. to 130 ° C. by the heaters L1 to L7 of the heating unit.

  After the heating step, the heated preform 10 is sent to a blow molding unit (not shown) by a transport device (not shown). The preform 10 sent to the blow molding part is inserted into the blow molding die of the blow molding part. Thereafter, the stretch rod is elongated, and the preform 10 is stretched by supplying high-pressure air into the preform 10 to perform biaxial stretch blow molding (blow molding step). The plastic bottle 40 shown in FIG. 3 is obtained by such blow molding.

  The plastic bottle 40 molded in the blow molding process is transported from a blow molding unit into a filling machine (not shown) by an air transport unit or a neck transport unit. Alternatively, the plastic bottle 40 is temporarily stored and transported from the bottle molding factory to the filling factory, where it is transported into the filling machine.

  Thereafter, the beverage (contents) is filled into the plastic bottle 40 in the filling machine. After the beverage is filled in this way, it is sealed with a cap (not shown) and further labeled. It is more preferable that each process until the cap is sealed is aseptic. In this way, a product bottle composed of the plastic bottle 40, the contents, and the cap is manufactured.

Thus, according to the present embodiment, when the thickness of the trunk middle portion 22 is T, the length of the trunk portion 20 is L, and the diameter of the trunk middle portion 22 is D, the value of T × L / D Is 12.7 or more. Thereby, after preform 10 is blow-molded and plastic bottle 40 is produced, it can control that creep deformation occurs in this plastic bottle 40. Further, according to the present embodiment, when the trunk neck distance is X and the sectional area ratio of the trunk portion at the position where the trunk neck distance is X is Y, 16% ≦ X ≦ 22% In the range, the relationship of Y ≧ −0.0088X ⁴ + 0.7276X ³ −22.656X ² + 316.6X−1586.9 is established. Thereby, when the preform 10 is blow-molded to produce the plastic bottle 40, the blow moldability can be improved.

  Next, specific examples of the present embodiment will be described.

  First, the following eight types of preforms 10 (Examples 1 to 4 and Comparative Examples 1 to 4) were produced by injection molding. The thickness T of the body middle portion 22 of each preform 10, the weight of the body portion 20 (body weight), the length of the body portion 20 (body length) L, the diameter (body diameter) D of the body middle portion 22, and the meat The values of the thickness T × the length L of the trunk portion 20 / the diameter D of the middle barrel portion 22 are as shown in Table 1, respectively. As the shape of the mouth portion 11 of each preform 10, a shape corresponding to the conventional general PCO1810 standard was used.

[Creep resistance]
Using each preform 10 shown in Table 1, a petaloid-shaped plastic bottle 40 (see FIG. 3) having an internal volume of 500 ml was blow molded. In the plastic bottle 40, the height of the body part 42 of the bottle excluding the mouth part 41 was 184.57 mm, and the maximum body diameter φ was 67 mm. About each plastic bottle 40, after measuring the full capacity, the plastic bottle 40 was filled with carbonated water so that the gas volume was 4, and sealed. The plastic bottle 40 was stored at 22 ° C. for 24 hours and subsequently stored at 38 ° C. for 24 hours. Thereafter, the carbonated water in the plastic bottle 40 was discharged, and the full capacity of the plastic bottle 40 was measured. Creep resistance was evaluated based on the increase in full capacity at this time (see Table 1).

  Here, as a result of plotting the value of the thickness T × the length L of the trunk portion / the diameter D of the trunk portion and the increase amount of the above-mentioned full capacity, a negative correlation (correlation coefficient: −0. 91) was observed (see FIG. 5).

  Since the increase amount of the full capacity mentioned above is preferably within 5% of the internal capacity (500 ml) of the plastic bottle 40, the criterion for creep deformation is whether the increase amount of the full capacity has increased by 25 ml or more. Set to. Those satisfying the creep deformation criteria were Example 1, Example 2, Example 3, Example 4, and Comparative Example 1 and Comparative Example 3. Based on the approximate straight line shown in FIG. 5, the value of thickness × body length / body diameter (T × L / D) satisfying an increase in full volume of 25 ml or less was 12.7 or more.

[Production efficiency]
Next, each preform 10 was evaluated in terms of manufacturing efficiency. In general, the preform 10 is manufactured by injection molding. At the time of injection molding, the melted PET flows into the mold and is cooled and solidified in the mold. At this time, if the thickness (T) of the preform middle portion 22 of the preform 10 is large, the cooling time becomes long (see FIG. 6) because the distance until the heat of the molten PET is transferred to the mold is long. There is a possibility that the cycle time becomes long and the production efficiency is lowered. Since the cooling time of the preform 10 at the time of injection molding is preferably 13 seconds or less, the thickness (T) is preferably 3.8 mm or less from this viewpoint. In this case, Example 1, Example 2, Example 3, Example 4, and Comparative Example 2 and Comparative Example 4 apply.

[Blow moldability]
Next, the blow moldability of each preform 10 was evaluated. Specifically, six types of preforms 10 (Examples 1 to 4 and Comparative Examples 1 to 2) are blow-molded to form a petaloid-shaped plastic bottle 40 having an internal volume of 500 ml (see FIG. 3). ) Was produced. In the plastic bottle 40, the height of the body part 42 of the plastic bottle 40 excluding the mouth part 41 was 184.57 mm, and the maximum body diameter φ was 67 mm.

  In this case, a one-piece blow molding machine (Germany, SIG Corp., LB01) was used. Each preform 10 was heated from approximately 90 ° C. to 130 ° C. with a plurality of rod-shaped heaters L1 to L7 provided in the blow molding machine. In addition, the heaters L1-L7 were arrange | positioned at intervals along the height direction of the preform 10, as shown in FIG. The outputs of the heaters L1 to L7 are 2500W for the heater L1 and 2000W for the heaters L2 to L7. During blow molding, the conditions of the heaters L1 to L7 were adjusted so that the thickness of the shoulder 48 of the plastic bottle 40 was 90 to 110% of the thickness of the barrel 42. The heating time by the heaters L1 to L7 is all 17 seconds. Table 2 shows the outputs of the heaters L1 to L7 at this time.

  For the preforms 10 of Examples 1 to 4, even if the output of the heaters L1 to L7 was the highest, it was suppressed to 62%, so that there was a large margin for increasing the outputs of the heaters L1 to L7 in order to shorten the heating time. However, for the preforms of Comparative Examples 1 and 2, the output of the highest heaters L1 to L7 is 76% to 92%, and it has been found that there is little room for increasing the output of the heaters L1 to L7 and shortening the heating time. . Further, the maximum and minimum difference (max-min of L1 to L3) of the outputs of the heaters L1 to L3 is 13% to 16% for Examples 1 to 4, whereas for Comparative Examples 1 to 2. It was found that the difference was large between 34% and 56%. This is because the output of the heater L1 or L2 is particularly high for the preforms of Comparative Examples 1 and 2, which is caused by the neck of the preform being difficult to stretch. From the above, it can be said that the preforms 10 of Examples 1 to 4 have good blow moldability, and the preforms of Comparative Examples 1 and 2 have poor blow moldability.

  Next, the shape of the neck portion 21 of the preform 10 was investigated for each of the preform 10 of Examples 1 to 4 and the preforms of Comparative Examples 1 and 2. The graph showing the change of the neck part 21 of each preform 10 is shown in FIGS.

  7 and 8, the horizontal axis “bottom neck lower distance X” in the graphs, as described above, the position of the body 20 directly below the support ring 12 is 0%, and the position of the tip of the bottom 23 is 100. %, The distance from the position directly below the support ring 12 is represented by a ratio (see FIG. 2). In addition, as described above, the “cross-sectional area ratio Y” means that the cross-sectional area at the portion where the cross-sectional area is the smallest is between 0% and 100%, and the cross-sectional area is the smallest. When the cross-sectional area at a large portion is Smax and the cross-sectional area value when the trunk neck distance is M is SM, it is obtained by the formula (SM−Smin) / (Smax−Smin).

FIG. 8 is a partially enlarged view of FIG. 7, and is an enlarged view showing a range where the trunk neck distance X is 12% to 27% and a cross-sectional area ratio Y is 75% to 100%. As shown in FIG. 8, the preform 10 of Examples 1 to 4 having good blow moldability was in a range of 16% ≦ X ≦ 22% with respect to the trunk neck length X and the cross-sectional area ratio Y. The relationship of Y ≧ −0.0088X ⁴ + 0.7276X ³ −22.656X ² + 316.6X−1586.9 was established.

  In addition, the preform 10 of Examples 1 to 4 having good blow moldability had a trunk neck length X at a position where the cross-sectional area ratio Y was 95% was 18.8% to 20.2%, The trunk neck lower distance X at the location where the cross-sectional area ratio Y is 90% is 16.9% to 17.8%, and the trunk neck lower distance X and the cross-sectional area ratio at the location where the cross-sectional area ratio Y is 100%. The difference from the neck length X at the portion where Y was 90% was 5.6% to 8.0%. On the other hand, the preforms of Comparative Examples 1 and 2 which were not good in blow moldability had a body neck lower distance X value of 22.2% to 23.1% at a cross-sectional area of 95%. The value of the trunk neck lower distance X at the location where the ratio Y is 90% is 20.5% to 21.9%, and the value of the trunk neck lower distance X at the location where the cross-sectional area ratio Y is 100% The difference from the torso neck distance X at the area where the area ratio Y was 90% was 4.5% to 4.7%.

  The results of creep resistance, production efficiency, and blow moldability of the preforms according to Examples 1 to 4 and Comparative Examples 1 and 2 described above are summarized in Table 3.

  Thus, while the preforms 10 of Examples 1 to 4 had good creep resistance, production efficiency, and blow moldability, the preforms of Comparative Examples 1 and 2 were creep resistant and manufactured. At least one of efficiency and blow moldability was not good.

[Blow moldability 2]
Next, the blow moldability of the preform 10 of Example 1 and the preform of Comparative Example 2 was evaluated by a method different from the above.

  In this case, the preforms of Example 1 and Comparative Example 2 were used, and a 500 ml plastic bottle (square bottle) 60 shown in FIG. 9 and a 500 ml plastic bottle (round bottle) 70 shown in FIG. 10 were blow-molded. It was produced by. Here, the blow molding machine was set so as to optimize the respective strengths, and the plastic bottles 60 and 70 were obtained.

(1) Buckling After filling each plastic bottle 60, 70 with 500 ml of water and closing the bottle, a load is applied vertically downward at a speed of 0.8 mm / second to the upper part of the plastic bottle 60, 70. The buckling strength was evaluated using the magnitude of the load when the plastic bottles 60 and 70 were displaced by 3 mm. It can be said that the higher the buckling strength, the stronger.

(2) Side wall After filling each plastic bottle 60, 70 with 500 ml of water and closing the bottle, each plastic bottle 60, 70 is tilted sideways and placed on the collapsed plastic bottle 60, 70 in parallel with the longitudinal direction of the bottle. A 1 cm wide iron rod was placed. A load was applied to this iron bar at a speed of 0.8 mm / second, and the strength of the side wall was evaluated based on the amount of deformation of each plastic bottle 60, 70 when the load reached 58.8N. It can be said that the strength of the plastic bottles 60 and 70 is higher as the deformation amount of the side wall is smaller.

  Table 4 shows the results of evaluating the strength of the plastic bottles 60 and 70.

  In Table 4, the opposite side of the side wall is an evaluation in which a plastic bottle (square bottle) 60 is placed so that one side 61 thereof faces downward and an iron rod is placed on the opposite side 61. It is. Similarly, the diagonal side of the side wall is evaluated by placing a plastic bottle (square bottle) 60 with one corner 62 facing downward and placing an iron rod on the opposite corner 62. It is what.

  In Table 4, the column surface side of the side wall is evaluated by placing a plastic bottle (round bottle) 70 so that one column surface 71 faces downward and placing an iron rod on the opposite column surface 71 side. It is a thing. The panel surface side of the side wall is similarly evaluated by placing a plastic bottle (round bottle) 70 with its panel surface 72 facing downward and placing an iron rod on the opposing panel surface 72. It is.

  Further, the weight distribution (g) means that the bottles are cut at a predetermined distance from the ground contact surface of the plastic bottles 60 and 70, and the respective parts (207 mm to 140 mm, 140 mm to 105 mm, 105 mm to 70 mm, 70 mm to 70 mm 35 mm, 35 mm to 0 mm). If this weight is large, it can be said that the thickness of the bottle of the part is thick.

  The plastic bottles 60 and 70 produced using the preform of Example 1 were superior in strength to the plastic bottles 60 and 70 produced using the preform of Comparative Example 2. The reason for this is that the thickness of the plastic bottles 60 and 70 having sufficient strength can be reduced, and the thickness of the weaker portion can be increased accordingly.

DESCRIPTION OF SYMBOLS 10 Preform 11 Mouth part 12 Support ring 13 Screw part 15 Opening part 20 Body part 21 Neck part 22 Body center part 23 Bottom part 40 Plastic bottle

Claims (6)

In the polyethylene terephthalate preform that is an injection molded product ,
A mouth having a support ring;
A trunk connected to the mouth,
The trunk includes a neck on the support ring side, a trunk middle connected to the neck, and a bottom coupled to the trunk middle,
When the thickness of the trunk middle part is T, the length of the trunk part is L, and the diameter of the trunk middle part is D, the value of T × L / D is 12.7 or more,
The distance below the trunk neck, which is a ratio of the distance from directly below the support ring to the total length of the trunk, is X,
The cross-sectional area ratio of the body portion at a position where the body neck length is X is Y, and the cross-sectional area ratio Y at the position directly below the support ring is 0% and the cross-sectional area is the largest among the body portions When the cross-sectional area ratio Y is 100%,
In the range of 16% ≦ X ≦ 22%, the relationship Y ≧ −0.0088X ⁴ + 0.7276X ³ −22.656X ² + 316.6X−1586.9 is established ,
The preform characterized in that the cross-sectional area ratio Y is 95% in a part of the section where the trunk neck distance X is 18.8% to 20.2% . In the polyethylene terephthalate preform that is an injection molded product,
A mouth having a support ring;
A trunk connected to the mouth,
The trunk includes a neck on the support ring side, a trunk middle connected to the neck, and a bottom coupled to the trunk middle,
When the thickness of the trunk middle part is T, the length of the trunk part is L, and the diameter of the trunk middle part is D, the value of T × L / D is 12.7 or more,
The distance below the trunk neck, which is a ratio of the distance from directly below the support ring to the total length of the trunk, is X,
The cross-sectional area ratio of the body portion at a position where the body neck length is X is Y, and the cross-sectional area ratio Y at the position directly below the support ring is 0% and the cross-sectional area is the largest among the body portions When the cross-sectional area ratio Y is 100%,
In the range of 16% ≦ X ≦ 22%, Y ≧ −0.0088X ⁴ + 0.7276X ³ -22.656X ² + 316.6X-1586.9 is established,
The preform characterized in that the cross-sectional area ratio Y is 90% in a part of the section where the trunk neck distance X is 16.9% to 17.8%. The preform according to claim 1 or 2, wherein a thickness T of the middle portion of the trunk is 3.8 mm or less. The difference between the trunk neck lower distance X of the section where the cross-sectional area ratio Y is 100% and the trunk neck lower distance X of the section where the cross-sectional area ratio Y is 90% is 5.6% to 8.0%. The preform according to any one of claims 1 to 3 , wherein the preform is provided. It has a mouth part having a support ring, and a body part connected to the mouth part, and the body part is connected to the neck part on the side of the support ring, a body middle part connected to the neck part, and the body middle part. T × L / D is 12.7, where T is the thickness of the barrel middle portion, L is the length of the barrel portion, and D is the diameter of the barrel middle portion. As described above, the trunk neck distance, which is the ratio of the distance from directly below the support ring to the total length of the trunk section, is X, and the trunk section is cut off at a position where the trunk neck distance is X. When the area ratio is Y, the cross-sectional area ratio Y at the position directly below the support ring is 0%, and the cross-sectional area ratio Y at the largest cross-sectional area is 100%, 16% ≦ X ≦ in 22% of the ^{range, Y ≧ -0.0088X 4 + 0.7276X 3} -2 .656X ² + 316.6X-1586.9 relationship is satisfied, a step of preparing a polyethylene terephthalate preform is an injection molded article,
Heating the preform to a temperature of 90 ° C. to 130 ° C .;
A step of producing a plastic bottle by biaxially stretching blow molding the preform in a blow mold ,
The method for producing a plastic bottle, wherein a cross-sectional area ratio Y is 95% in a part of a section where the trunk neck distance X is 18.8% to 20.2% . It has a mouth part having a support ring, and a body part connected to the mouth part, and the body part is connected to the neck part on the side of the support ring, a body middle part connected to the neck part, and the body middle part. T × L / D is 12.7, where T is the thickness of the barrel middle portion, L is the length of the barrel portion, and D is the diameter of the barrel middle portion. As described above, the trunk neck distance, which is the ratio of the distance from directly below the support ring to the total length of the trunk section, is X, and the trunk section is cut off at a position where the trunk neck distance is X. When the area ratio is Y, the cross-sectional area ratio Y at the position directly below the support ring is 0%, and the cross-sectional area ratio Y at the largest cross-sectional area is 100%, 16% ≦ X ≦ In the range of 22%, Y ≧ −0.0088X ⁴ + 0.7276X ³ -22.656X ² A step of preparing a polyethylene terephthalate preform which is an injection-molded product, wherein the relationship of + 316.6X-1586.9 is established;
Heating the preform to a temperature of 90 ° C. to 130 ° C .;
A step of producing a plastic bottle by biaxially stretching blow molding the preform in a blow mold,
A method for producing a plastic bottle, characterized in that a cross-sectional area ratio Y is 90% in a part of a section in which the body neck length X is 16.9% to 17.8%.

Images