JP4692738B2 - Preform molding method, preform and casing - Google Patents

Description

The present invention relates to a method for molding a preform made of a synthetic resin having a colored layer whose layer thickness is changed to a gradation, a preform obtained by the molding method, and a synthetic resin decorated by changing the color density and hue in a gradation It relates to a steelmaking body.

Housings made of polyethylene terephthalate (PET) resin and the like are used in various fields such as beverages, foods, and cosmetics, and various decorating methods are adopted to differentiate them as products. In many cases, the case is decorated with a printed shrink film. However, Patent Document 1 describes a case in which a laminated structure is formed and a preform in which a colored layer is intermittently formed on an intermediate layer is blow-molded.
Japanese Patent Laid-Open No. 2-98409

  The present invention is to form a plurality of colored layers composed of colored resins of different shades in a preform in a preform, and to gradually change the thickness of these colored layers in the vertical direction, Accordingly, it is an object of the present invention to provide a biaxially-stretched blow molded synthetic resin casing that has a high degree of gradation relating to coloring density, hue, or both, and has unprecedented decorating properties.

Of the present invention that solves the above technical problems, claims 1 to 5 relate to a preform molding method, of which the molding method of the invention according to claim 1 is:
A preform molding method for biaxial stretch blow molding that sequentially injects a plurality of resins including at least one colored resin into a cavity of a mold through a gate opposed to the center of the bottom,
In the short shot state, the next resin is flowed in a wedge shape so that the central portion of the previously injected colored resin located in the mold cavity is pushed in a wedge shape, and in the preform, the preform is made of the previously injected colored resin. A gradation area in which the thickness of the colored layer gradually decreases toward the bottom is formed.

  According to the molding method of claim 1, the colored resin previously injected located in the mold cavity in a short shot state has a high resin temperature at the center portion away from the cavity wall surface and a low melt viscosity. The injected resin flows in such a manner as to pierce through the central portion, and as a result, a portion of the colored layer made of the colored resin that gradually decreases in the upstream direction (gate position direction) is formed. .

  And, in the preform molded in this way, it is possible to form a gradation region related to the layer thickness of the colored layer in which the layer thickness of the colored layer made of the previously injected colored resin gradually decreases toward the bottom. it can.

In addition, in the molding method of claim 1, preforms having various laminated structures can be obtained by sequential molding in stages as shown below according to the purpose of decoration. Various colored decorations can be obtained by axial blow molding.
(1) Colored transparent resin / colorless transparent resin (2) Colored transparent resin / colorless transparent resin / transparent colored resin (3) Colored transparent resin / colored transparent resin / colorless transparent resin (4) Colored transparent resin / colored transparent resin / further Different colored transparent resin / colorless transparent resin Of course, not only a transparent resin but also a translucent or opaque resin can be used depending on the purpose. Also, it is possible to change only the color using the same resin, or it is possible to use different resins.

For example, in the example of (3), the first colored transparent resin, the second colored transparent resin colored in a different color from the first, and the third colorless transparent resin are sequentially injected. The second resin advances through the central portion of the first resin, and the third resin advances through the central portion of the second resin. For this reason, the preform is formed so that the gradation regions relating to the thicknesses of the colored layers of the first and second colored transparent resins overlap.
Then, by performing biaxial stretch blow molding of such a preform, it is possible to provide a decorated casing that reveals a gradation in which both the color density and the hue change gradually and continuously.

  Here, the degree of gradation related to the layer thickness of the colored layer, that is, the mode of change in the layer thickness, is the injection amount, injection speed, injection pressure, injection resin temperature, mold temperature, etc. It can be controlled by the conditions and the melt viscosity of the resin used.

  According to a second aspect of the present invention, there is provided a molding method according to the first aspect, wherein the gradation related to the thickness of the colored layer made of the colored resin previously injected is determined by a combination of an injection speed and an injection pressure of the resin to be injected next. To control the degree of.

  According to the above method of the second aspect, it is possible to relatively easily control the gradation level related to the thickness of the colored layer by a combination of the injection speed and the injection pressure among the sequential injection conditions.

  According to a third aspect of the present invention, there is provided the molding method according to the first or second aspect, wherein the resin is sequentially injected in three stages.

The molding method according to claim 3 is a method of sequentially injecting resin in three stages, and can be realized relatively easily from the viewpoint of equipment or process, and as exemplified below depending on the purpose of decoration. In three stages, it is possible to sequentially inject three or two kinds of resins including hues in various modes.
(1) colorless transparent resin / colored transparent resin / colorless transparent resin (2) colored transparent resin / colorless transparent resin / same color transparent resin (3) colored transparent resin / colorless transparent resin / different color transparent resin (4) colored transparent resin / different color Transparent resin / colorless transparent resin (5) colored transparent resin / different color transparent resin / further different color transparent resin The same resin can be used as the base resin excluding the colored components, for example, one resin. In addition, a resin having a low melt viscosity can be used, or a different resin can be used. Depending on the purpose, a translucent or opaque resin, or an opaque colored resin can also be used.

  According to a fourth aspect of the present invention, in the first, second or third aspect of the invention, the melt viscosity of the colored resin to be injected first is set lower than the resin to be injected next. is there.

  In the molding method according to claim 4, the next resin flows so as to pierce through the central portion of the previous colored resin in a short shot state to form a gradation region in the preform, but by making the colored resin low viscosity The effect of forming this gradation region is more effectively exhibited, and the layer thickness of the colored resin can be changed into a string shape.

  According to a fifth aspect of the present invention, there is provided the molding method according to the first, second, third, or fourth aspect, wherein each resin is a resin having transparency.

  By the molding method according to claim 5, it is possible to make the gradation effect related to the color density or hue more effectively by light transmission in the final product casing, which has an unprecedented decoration effect. The body can be provided.

Next, the invention described in claim 6 relates to a preform, and the means thereof is:
A biaxial stretch blow molding preform formed by a sequential injection molding method in which a plurality of resins including at least one colored resin are sequentially injected into a cavity of a mold through a gate opposed to the center of the bottom. There,
In the short shot state, the thickness of the colored layer made of the colored resin is directed toward the bottom by the flow action of the next resin that pushes the central portion of the colored resin that has been injected into the mold cavity in a wedge shape. A gradation area that changes gradually is formed,
It is in.

  The preform having the above-described configuration according to claim 6 can be obtained by the sequential injection molding method according to any one of claims 1 to 5 described above, and this preform is biaxially stretch blow molded and colored by a colored layer made of a colored resin. It is possible to provide a casing having unprecedented decorativeness, in which gradations relating to density, color, or both are highly developed.

Next, the invention according to claim 7 and claim 8 relates to a housing, and the means of the invention according to claim 7 includes:
Molded by a sequential injection molding method of sequentially injecting a plurality of resins including at least one colored resin into a cavity of a mold through a gate opposed to the center of the bottom, and the central portion of the colored resin previously injected is A biaxial stretch blow molding was performed on a preform in which a gradation region in which the layer thickness gradually decreased toward the bottom was formed in the colored layer made of the previous colored resin by the flow action of the next resin proceeding in a wedge shape. A body,
The thickness of the colored layer formed by the previously injected colored resin gradually decreases toward the bottom, and this colored layer produces a gradation in which the color density, hue, or both of these continuously change gradually. It is in being decorated.

  The casing according to claim 7 can be obtained by the biaxial stretch blow molding of the preform according to claim 6, which can be obtained by the molding method according to claims 1 to 5 described above. It is possible to provide a casing having unprecedented decorating properties in which gradations relating to coloring density, hue, or both of these are highly expressed.

According to an eighth aspect of the present invention, there is provided the invention according to the seventh aspect, wherein the color density and the hue are gradually and gradually changed by the three-color colored layer made of PET resin and made of the three-color colored resin. It is in making the gradation to appear.

  The present invention provides a PET resin casing having unprecedented decorativeness, in which a gradation in which the coloring density and the hue change continuously and gradually appears in three colors. Can do.

The present invention is the above-described method and configuration, and has the following effects.
First, claims 1 to 5 relate to a preform molding method, and in the invention according to claim 1, the central portion of the previously injected colored resin is pushed like a wedge. Next, due to the flow action of the resin to be injected, a gradation area is formed in which the thickness of the colored layer made of the colored resin previously injected in the preform changes gradually toward the bottom. A preform having a structure can be obtained, and a bi-axial stretch blow molding of the preform can provide a housing with various coloring decorations that has never been seen before.

  In the second aspect of the invention, the gradation level relating to the thickness of the colored layer can be controlled relatively easily by combining the injection speed and the injection pressure among the sequential injection conditions.

  The invention according to claim 3 is a method of sequentially injecting resin in three stages, which can be realized relatively easily from the viewpoint of equipment or process, and also includes coloring colors according to the purpose of decoration. In addition, three or two kinds of resins can be combined in various modes.

  In the invention described in claim 4, by making the colored resin have a low viscosity, the effect of forming the gradation region becomes more effective, and it becomes possible to change the layer thickness of the colored resin into a string shape.

  According to the fifth aspect of the present invention, the gradation effect can be more effectively revealed by the transmission of light, and a housing having an unprecedented decorative effect can be provided.

  The invention according to claim 6 relates to a preform, and this preform has been biaxially stretch blow-molded, and a coloring layer, a color tone, or a gradation relating to both has been highly developed by the colored layer. It is possible to provide a housing having a decorative property that is not present.

Next, the invention according to claim 7 and claim 8 relates to a housing.
In the invention according to claim 7, it is possible to provide a casing having unprecedented decorating properties in which a coloring layer, a hue, or a gradation relating to both of them is highly expressed by the colored layer.

  In the invention according to claim 8, there is provided a PET resin casing having unprecedented decorativeness, in which a gradation in which the coloring density and hue of the three colors change gradually and continuously appears. be able to.

Hereinafter, embodiments of a preform molding method, a preform, and a casing of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic explanatory view showing an example of a sequential injection pattern applied to the preform molding method of the present invention, and FIGS. 2 and 3 are cross-sectional views showing an example of a mold used in the preform molding method of the present invention. It is.

  2 and 3 includes a core mold 2 and a cavity mold 3, and a cavity 4 corresponding to a test tubular preform is formed. And the gate 5 is formed in the position corresponding to the center part of the bottom part 107 (refer FIG. 5) of the preform 101, The molten resin inject | emitted by the injection pattern shown by FIG. 1 is supplied from this gate 5, The cavity 4 flows toward the portion corresponding to the mouth tube portion 104 to fill the cavity 4.

  The injection pattern schematically shown in FIG. 1 is an example of a sequential injection pattern, and has three stages: primary J1 (time t1 to t2), secondary J2 (time t2 to t3), and tertiary J3 (time t3 to t42). Then, the colored resins 12f, 12c, and 12t are sequentially injected into the cavity 4.

  4 (a), 4 (b), and 4 (c) are schematic explanatory views showing states of the injection pattern at time t2, time t3, and time t4, respectively, and the cavity 4 is colored in a short shot at time t2. The resin 12f is in a state of being filled in a range of about 1/3 from the gate 5 (see FIGS. 2, 3 and 4A).

  Next, at time t2 in the above filling state, the primary injection J1 is stopped and the supply of the colored resin 12f is stopped. Next, the secondary injection J2 is sequentially started, and the colored resin 12s is transferred from the gate 5 into the cavity 4. 4b at the time point t3 when the secondary injection J2 stops by flowing into the cavity 4 and flowing in the cavity 4 toward the portion corresponding to the mouth tube portion 104 so as to push the central portion of the colored resin 12f into a wedge shape. It will be in the state shown in

  As a result of the flow of the colored resin 12s injected in the secondary injection J2, the colored resin 12f of the primary injection J1 becomes a double cylinder in the range Wf1 shown in FIG. 4B, and the colored resin 12f is colored in the range Wf1. The layer thickness of the resin 12f changes gradually in the upstream direction (the gate 5 position direction).

  Next, the third injection J3 is sequentially started, and the colored resin 12t flows into the cavity 4 from the gate 5, and this time, the cavity is pushed through the central portion of the colored resin 12s that has been subjected to the secondary injection J2 in a wedge shape. 4 flows toward the portion corresponding to the mouth tube portion 104, and the state shown in FIG. 4C is reached at the time t4 when the third injection J3 stops.

As a result of the flow of the colored resin 12t injected in the tertiary injection J2, the colored resin 12s of the secondary injection J2 has a double cylindrical shape in the range Ws shown in FIG. 4C, and the colored resin 12s in the range Ws. The layer thickness of the layer gradually decreases in the upstream direction.
At this time, the double cylindrical portion of the colored resin 12f further extends to the range Wf2.

  FIG. 5 is an embodiment of the preform of the present invention, and the same PET resin is used for the primary injection J1, the secondary injection J2, and the tertiary injection J3, and colored transparent resins colored yellow, light blue, and light red, respectively. It is a front view which partially shows the preform 101 shape | molded by the above sequential injection molding methods using 12f, 12s, and 12t.

In order from the top, a yellow colored layer 102f, a light blue colored layer 102s, and a light red colored layer 102t are located. At a height position hf, the colored layer 102f has a double cylindrical shape, and the layer thickness is directed toward the bottom 107. A gradation region 110f having a layer thickness that gradually decreases is formed.
In the height range hs, the colored layer 102 s has a double cylindrical shape, and a gradation region 110 s related to the layer thickness in which the layer thickness gradually decreases toward the bottom 107 is formed.

Next, FIG. 6A shows a casing 201 having a cylindrical body 206 obtained by biaxial stretch blow molding of the preform 101 of FIG. 5, and FIG. 6B shows a laminated structure of a colored layer 202. FIG. 2 is a longitudinal sectional view showing a wall partially enlarged in order to explain the above.
This casing 201 corresponds to the laminated structure of the three colored layers 102f, 102s, and 102t of the preform 101 of FIG. 5 described above, and is formed by stretching them by biaxial stretch blow molding. Blue and light red colored layers 202f, 202s, and 202t are laminated.

The casing 201 is transparent as a whole, but a gradation related to the coloring density and hue appears.
More specifically, first, the portion from the mouth tube portion 204 to the shoulder portion 205a is transparent in yellow, and the shoulder portion 205 has a density-related gradation so that the coloring concentration decreases downward due to wall thickness change due to stretching. It is appearing. Next, the range of the height range h1 is an area where the yellow colored layer 202f and the light blue colored layer 201s overlap and gradually change from green to light blue.

The lower height range h2 corresponds to a portion where the height range hs of the preform 101 in FIG. 5 is extended, and the light blue colored layer 202s and the light red colored layer 202t overlap each other, so It is an area where the degree of red gradually increases toward.
Note that the yellow colored layer 102f extends also in the height range h2, but since the layer thickness is extremely thin, the influence on the hue is small.
Here, when the coloring density of the colored resin 12s and the colored resin 12t is increased,
For example, in the height range h1, the influence of the colored resin 12s becomes large, and the gradation relating to the yellow and blue shades does not appear vividly. Therefore, in the present embodiment, the colored resin 12s and the colored resin 12t are respectively light blue as described above. The color was light red.

  As mentioned above, although embodiment of this invention was described according to the Example, this invention is not limited to these Examples. The synthetic resin to be used is not limited to PET resin, but it is possible to use resins conventionally used for biaxially stretched blow molded casings such as PP resin, and change the melt viscosity of the colored resin according to the purpose. It is also possible to use other types of resins without being limited to the same type.

In the above embodiment, the example in which the resin is sequentially injected in three stages has been described. However, it may be two stages or four or more stages depending on the purpose. Also in the sequential injection in three stages, in addition to the combination of colored transparent resin / different color transparent resin / further different color transparent resin of this embodiment, resins can be combined in various modes as exemplified below.
(1) colorless transparent resin / colored transparent resin / colorless transparent resin (2) colored transparent resin / colorless transparent resin / same color transparent resin (3) colored transparent resin / colorless transparent resin / different color transparent resin (4) colored transparent resin / different color Transparent resin / colorless transparent resin

  According to the preform molding method of the present invention, it is possible to provide a casing having unprecedented decorating properties in which a coloring layer, a gradation relating to both, or a gradation relating to both are highly expressed by the colored layer. Products can be differentiated and a wide range of usage is expected.

It is a schematic explanatory drawing which shows an example of the sequential injection pattern applied to the preform shaping | molding method of this invention. It is a vertical front view which shows an example of the metal mold | die for preform shaping | molding. FIG. 3 is a plan sectional view taken along line AA of the mold of FIG. 2. It is a schematic explanatory drawing which shows the filling process of the molten resin to the metal mold cavity by the injection pattern of FIG. FIG. 2 is a front view showing a part of the preform formed by the injection pattern of FIG. It is the (a) front view of the housing obtained by carrying out biaxial stretch blow molding of the preform of FIG. 5, and (b) the longitudinal cross-sectional view which expands and shows a wall partially in a horizontal direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1; Mold 2; Core mold 3; Cavity mold 4; Cavity 5; Gate 12 (12f, 12s, 12t); Colored resin 12a, 12b; (mold surface) vicinity part 12c; (cavity) center part 101 Preform 102 (102f, 102s, 102t); colored layer 104; mouth 105; neck ring 106; trunk 107; bottom 110 (110f, 110s); gradation area 201; housing 202 (202f, 202s, 202t); Colored layer 204; mouth tube portion 205; neck ring 205a; shoulder portion 206; trunk portion 207; bottom portion Wf1, Wf2, Fs; range hf, hs; height range hf1, hf2; height range h1, h2; Range J1; primary injection J2; secondary injection J3; tertiary injection t1 to t4; time

Claims (8)

Sequential injection method of sequentially injecting a plurality of resins including at least one colored resin (12) into the cavity (4) of the mold (1) through the gate (5) opposed to the center of the bottom (107) In the short shot state, in the mold (1) the cavity (4), the injected resin is flowed and laminated so as to penetrate the central portion (12c) of the previously injected colored resin (12) in a wedge shape. In the preform (101), a gradation region (110) is formed in which the thickness of the colored layer (102) made of the previously injected colored resin (12) gradually decreases toward the bottom (107). A preform molding method for biaxial stretch blow molding. The degree of gradation related to the layer thickness of the colored layer (102) made of the colored resin (12) previously injected is controlled by a combination of the injection speed and injection pressure of the resin to be injected next. Preform molding method The preform molding method according to claim 1 or 2, wherein the resin is sequentially injected in three stages. The preform molding method according to claim 1, 2 or 3, wherein the colored resin (12) injected first has a lower viscosity than that of the next injected resin. The preform molding method according to claim 1, wherein each resin is a resin having transparency. Sequential injection molding in which a plurality of resins including at least one colored resin (12) are sequentially injected into the cavity (4) of the mold (1) through the gate (5) positioned opposite the center of the bottom (107). A preform (101) molded by the method, and in a short shot state, the mold (1) next to the central portion of the colored resin (12) injected into the cavity (4) is pushed like a wedge. In the colored layer (102) composed of the colored resin (12), a gradation region (110) in which the layer thickness gradually decreases toward the bottom (107) is formed by the fluid action of the resin. A preform for biaxial stretch blow molding characterized by Sequential injection molding in which a plurality of resins including at least one colored resin (12) are sequentially injected into the cavity (4) of the mold (1) through the gate (5) positioned opposite the center of the bottom (107). In the colored layer (102) made of the previous colored resin (12), the thickness of the colored resin (12) formed by the method described above is caused by the flow action of the next resin that pushes the central portion of the colored resin (12) injected earlier. Is a biaxial stretch blow-molded body (101) formed with a gradation region (110) that gradually decreases toward the bottom (107), and is formed by the colored resin (12) injected earlier The layer thickness of the colored layer (202) gradually decreases toward the bottom, and the colored layer (202) produces a gradation in which the color density, the hue, or both of these continuously change gradually. Synthetic resin housing.
Claims made of polyethylene terephthalate resin, and a gradation in which the color density and hue change continuously and gradually by the three colored layers (202f, 202s, 202t) made of three colored resins (12) Item 8. A synthetic resin casing according to Item 7.