JP7299494B2 - Foam molded article and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a foam molded article and a method for producing the same.

In Patent Document 1, a duct (referred to as an "instrument panel duct") is provided on the dashboard of an automobile for ventilating air from an air conditioner. As such a duct, a foam duct made of a foam molding is sometimes used in consideration of heat insulation and quietness (Patent Document 1).

JP 2015-124380 A

A foam duct as disclosed in Patent Document 1 has the advantage of being excellent in heat insulation and light weight, but does not have high mechanical strength. For this reason, it is difficult to use the foamed duct of Patent Document 1 for applications such as foot ducts, which are susceptible to mechanical loads, and it is desired to increase the mechanical strength.

The present invention has been made in view of such circumstances, and provides a foam molded article having excellent mechanical strength.

According to the present invention, there is provided a foam-molded article having a base wall and an opposing wall spaced apart from each other, the foam-molded article having an inner rib between the base wall and the opposing wall, wherein the inner rib is , a foam molded body extending from the base wall toward the opposing wall, and the tips of the inner ribs being welded to the opposing wall.

Since the foam molded article of the present invention has inner ribs, it has excellent mechanical strength. Moreover, since it is a foam molding, it is excellent also in heat insulation and lightness.

Various embodiments of the present invention are illustrated below. The embodiments shown below can be combined with each other.
Preferably, in the foam-molded article described above, the inner rib has a shape in which the width increases toward the tip.
Preferably, in the foam molded article described above, the distance between the inner surface of the base wall and the inner surface of the opposing wall is D, and the distance from the inner surface of the base wall is 0.1D. The foam molded article has a ratio of W2/W1 of 1.5 or more, where W1 is the width of the inner rib and W2 is the width of the inner rib at a position 0.9D from the inner surface of the base wall. .
Preferably, in the foam-molded article described above, the inner rib is a foam-molded article configured such that the expansion ratio increases toward the tip.
Preferably, in the foamed molded article described above, the distance between the inner surface of the base wall and the inner surface of the opposing wall is D, and the distance from the inner surface of the base wall is 0.0D to 0.2D. Let P1 be the foaming ratio of the inner rib at the portion within the range of and P2 be the expansion ratio of the inner rib at the portion within the range of 0.8D to 1.0D from the inner surface of the base wall, It is a foam molded article having a P2/P1 ratio of 1.2 or more.

Preferably, it is a method for manufacturing a foam molded article using first and second molds configured to be openable and closable, wherein the first mold is configured such that the projection length from the cavity surface of the first mold is variable. an arranging step, a mold closing step, and a blowing step, wherein the arranging step places a foamed parison between first and second molds; A base portion facing a mold and a facing portion facing the base portion are provided, and in the mold closing step, the first and second molds are closed while the slide core protrudes from the cavity surface. By forming a recess that is recessed from the base portion toward the facing portion, the tip of the recess is welded to the facing portion, and in the blowing step, the slide core is retracted and placed in the first and second molds. applying a blow pressure within said foamed parison of.
Preferably, in the method described above, the time from the completion of mold closing of the first and second molds to the start of retraction of the slide core is 1 to 5 seconds.
Preferably, the method described above, wherein the blow pressure is 2 to 6 kgf/cm ² .

BRIEF DESCRIPTION OF THE DRAWINGS It is a perspective view which shows the foaming molding 10 of one Embodiment of this invention. 2A is a cross-sectional view of FIG. 1 in a cross section perpendicular to the weld trace 3a of the inner rib 3, and FIG. 2B is an enlarged view of area B in FIG. 2A. An example of a molding machine 1 that can be used to manufacture a foam molded article 10 according to one embodiment of the present invention is shown. 4 is an enlarged view of the vicinity of molds 21 and 22 in FIG. 3. FIG. FIG. 5 is a cross-sectional view showing a state after the molds 21 and 22 are closed from the state shown in FIG. 4; 6 is an enlarged view of area A in FIG. 5; FIG. FIG. 6 is a cross-sectional view showing a state after blow pressure is applied to the interior of the foam parison 23 while retracting the slide core 24 from the state of FIG. 5 ; It is an enlarged photograph of the inner rib 3 vicinity in the foaming molding 10 in an Example.

Embodiments of the present invention will be described below. Various features shown in the embodiments shown below can be combined with each other. In addition, the invention is established independently for each characteristic item.

1. Configuration of Foam Mold 10 The foam mold 10 shown in FIGS. 1 and 2 has a base wall 10a and an opposing wall 10b which are separated from each other. The base wall 10a and the opposing wall 10b are connected by a peripheral wall 10c surrounding the circumference, and a space is formed inside the foam molded body 10. As shown in FIG. The foam molding 10 has inner ribs 3 between the base wall 10a and the opposing wall 10b. The inner rib 3 extends from the base wall 10a toward the opposing wall 10b, and the tip 3b of the inner rib 3 is welded to the opposing wall 10b. According to such a configuration, it is excellent in heat insulation, light weight, and mechanical strength.

The foam molded body 10 is made of a foamed resin obtained by foaming a resin such as polyolefin. The expansion ratio of the foam molded article 10 is preferably 1.2 to 5.0 times, more preferably 1.5 to 4.0 times. If the foaming ratio is too low, the heat insulating properties may become insufficient. On the other hand, if the expansion ratio is too high, the strength of the foam molded article 10 may be insufficient. Specifically, the expansion ratio is, for example, 1.2, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0 times. may be within a range between any two of the numerical values exemplified in .

The foam molded article 10 is suitably used for any application that requires heat insulation, light weight, and mechanical strength. As an example, the foam molded article 10 is used as a duct, and is preferably used as a foot duct that particularly requires high mechanical strength. In order to improve the mechanical strength of the foam molded article 10, for example, there is a means of providing groove-like ribs on the side surface, but such means greatly reduces the cross-sectional area of flow, resulting in a significant decrease in duct performance. On the other hand, since the inner ribs 3 can have a smaller cross-sectional area than the grooved ribs, it is possible to improve the mechanical strength while minimizing adverse effects on the duct performance.

As shown in FIGS. 4 to 7, the inner ribs 3 are formed by welding opposing side surfaces of groove-shaped recesses 23c formed in the foam parison 23. As shown in FIG. 2, a welding mark 3a is normally formed that is exposed on the base wall 10a side.

As shown in FIG. 2B, it is preferable that the inner rib 3 has a shape in which the width increases toward the tip 3b (tip widening shape). Thereby, the mechanical strength of the opposing wall 10b can be improved. From the viewpoint of improving the mechanical strength of the foam molded article 10, it is desirable to narrow the pitch of the inner ribs 3 as much as possible, but narrowing the pitch of the inner ribs 3 is technically not easy. This is because if the pitch of the inner ribs 3 is narrowed, the pitch of the slide cores 24 (see FIG. 4) must also be narrowed. This is because there is a limit to narrowing the pitch of the core 24 . On the other hand, as shown in FIG. 2B, if the inner ribs 3 are configured so that the width increases toward the tip 3b, the distance between the adjacent inner ribs 3 becomes narrower on the opposing wall 10b. The same mechanical strength improvement effect as narrowing can be obtained.

As shown in FIG. 2B, the distance between the inner surface of the base wall 10a and the inner surface of the opposing wall 10b is D, and the width of the inner rib 3 at the position 0.1D from the inner surface of the base wall 10a is Assuming that W1 is W1 and W2 is the width of the inner rib at a distance of 0.9D from the inner surface of the base wall 10a, W2/W1 is preferably 1.5 or more. This is because in this case, the effect of improving the mechanical strength is remarkable. W2/W1 is, for example, 1.5 to 6.0, specifically, for example, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5 , 5.0, 5.5, 6.0, and may be in the range between any two of the numbers exemplified herein.

In one example, as shown in FIGS. 5 to 7, when the slide core 24 is retracted, the degree of expansion of the air bubbles in the portion closer to the bottom of the concave portion 23c increases, and the foaming ratio increases. Formed by growing. In this case, the expansion ratio of the inner rib 3 increases toward the tip 3b.

As shown in FIG. 2B, P1 is the expansion ratio of the inner rib 3 at a portion within the range of 0.0D to 0.2D from the inner surface of the base wall 10a, and 0 is the distance from the inner surface of the base wall 10a. P2/P1 is preferably 1.2 or more, where P2 is the foaming ratio of the inner rib in the region within the range of 0.8D to 1.0D. In this case, the weight reduction of the foam molded article 10 is remarkable. P2/P1 is, for example, 1.2 to 4.0, specifically, for example, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4 , 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0 and within a range between any two of the numerical values exemplified herein. There may be.

2. Configuration of Molding Machine 1 First, a molding machine 1 that can be used to manufacture a foam molded article 10 according to an embodiment of the present invention will be described with reference to FIG. A molding machine 1 includes a resin supply device 2 , a head 18 , and first and second molds 21 and 22 . The resin supply device 2 includes a hopper 12 , an extruder 13 , an injector 16 and an accumulator 17 . The extruder 13 and the accumulator 17 are connected via a connecting pipe 25 . The accumulator 17 and the head 18 are connected via a connecting pipe 27 .
Each configuration will be described in detail below.

<Hopper 12, Extruder 13>
The hopper 12 is used to charge the raw material resin 11 into the cylinder 13 a of the extruder 13 . Although the form of the raw material resin 11 is not particularly limited, it is usually in the form of pellets. The raw material resin 11 is, for example, a thermoplastic resin such as polyolefin. The raw material resin 11 is fed from the hopper 12 into the cylinder 13a, and then heated in the cylinder 13a to be melted into a molten resin. In addition, it is conveyed toward the tip of the cylinder 13a by the rotation of the screw arranged in the cylinder 13a. The screw is arranged in the cylinder 13a, and conveys the molten resin while kneading it by its rotation.

<Injector 16>
The cylinder 13a is provided with an injector 16 for injecting a foaming agent into the cylinder 13a. The blowing agent injected from the injector 16 includes physical blowing agents, chemical blowing agents, and mixtures thereof, but physical blowing agents are preferred. As the physical foaming agent, inorganic physical foaming agents such as air, carbon dioxide gas, nitrogen gas and water are preferred.

<Accumulator 17, Head 18>
A molten resin 11 a obtained by melt-kneading a raw material resin and a foaming agent is extruded from a resin extrusion port of a cylinder 13 a and injected into an accumulator 17 through a connecting pipe 25 . The accumulator 17 has a cylinder 17a and a piston 17b slidable inside the cylinder 17a, and the molten resin 11a can be stored in the cylinder 17a. By moving the piston 17b after a predetermined amount of the molten resin 11a is stored in the cylinder 17a, the molten resin 11a is extruded through the connecting pipe 27 from the die slit provided in the head 18 and suspended to form the foamed parison 23. to form The shape of the foamed parison 23 is not particularly limited, and may be cylindrical or sheet-like.

<First and second molds 21, 22>
A foamed parison 23 is guided between molds 21 and 22 configured to be openable and closable. By molding the foamed parison 23 using the molds 21 and 22, the foamed molded article 10 as shown in FIG. 1 is obtained.

As shown in FIG. 4, the molds 21, 22 have cavity surfaces 21a, 22a. When the molds 21 and 22 are closed, the cavity surfaces 21a and 22a are combined to form the outer surface of the cavity. Pinch-off portions 21b and 22b are provided around the cavity surfaces 21a and 22a. A plurality of slide cores 24 are provided in the mold 21 . The plurality of slide cores 24 are connected to each other by a connecting portion 28 so that they can slide simultaneously. The slide core 24 is configured such that the length of protrusion from the cavity surface 21a is variable.

3. Method for Manufacturing Foamed Duct The method for manufacturing a foamed duct according to the present embodiment includes an arrangement step, a mold closing step, a blowing step, and a post-treatment step.

(a) Placement Step In the placement step, the foamed parison 23 is placed between the molds 21 and 22, as shown in FIGS. The explanation of the expansion ratio of the foamed parison 23 is the same as the explanation of the expansion ratio of the foam molded article 10 . The foamed parison 23 includes a base portion 23a facing the first mold 21 and a facing portion 23b facing the base portion 23a. The outer surface of the base portion 23a faces the first mold 21, the outer surface of the facing portion 23b faces the second mold 22, and the inner surfaces of the base portion 23a and the facing portion 23b face each other.

(b) Mold Closing Step In the mold closing step, as shown in FIGS. 5 and 6, the molds 21 and 22 are closed with the slide core 24 protruding from the cavity surface 21a, so that the molds 21 and 22 are opposed from the base portion 23a. A recess 23c recessed toward the portion 23b is formed, and the tip 23c1 of the recess 23c is welded to the opposing portion 23b. The slide core 24 protrudes so that a gap is formed between the tip 24a and the cavity surface 22a. By providing the gap, the wall thickness of the inner rib 3 near the tip 3b is increased to improve the mechanical strength. Assuming that the distance between the tip 24a and the cavity surface 22a is S, and the thickness of the foamed parison 23 is Tp (see FIG. 4), Tp/S is, for example, 0.5 to 4.0. is, for example, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, and between any two of the values exemplified here. may be within the range.

Assuming that the thickness of the slide core 24 is Ts, Ts/Tp is, for example, 0.1 to 4.0, specifically for example, 0.1, 0.2, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, and may be in the range between any two of the values exemplified herein.

(c) Blowing Step In the blowing step, as shown in FIG. 7, blow pressure is applied to the bag-shaped foamed parison 23 in the molds 21 and 22 while retracting the slide core 24 . As a result, the opposing side surfaces of the recesses 23c are welded together to form the inner ribs 3. As shown in FIG. Further, when the slide core 24 is quickly retracted, the space between the tip 24a of the slide core 24 and the bottom of the recess 23c is decompressed, and the bubbles contained in the foam parison 23 are expanded. Therefore, the inner ribs 3 are formed so that the foaming ratio increases toward the tip 3b. In addition, since the width of the inner ribs 3 increases as the foaming ratio increases, the inner ribs 3 having a shape in which the width increases toward the tip 3b can be obtained. It is preferable that the foamed parison 23 is vacuum-sucked through the vacuum suction hole provided in the mold 22 so that the bottom of the recess 23c does not move together with the slide core 24 when the slide core 24 is retracted.

The time from the completion of mold closing of the molds 21 and 22 to the start of retraction of the slide core 24 is preferably 1 to 5 seconds, more preferably 2 to 4 seconds. If this time is too short, the welding at the tip 23c1 becomes insufficient, and the inner rib 3 tends to be distorted. On the other hand, if this time is too long, the inner ribs 3 may not be formed because the opposing inner surfaces of the recesses 23c are not welded together. Specifically, this time is, for example, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or 5 seconds. may be within the range of

The blow pressure is preferably 2-6 kgf/cm ² , more preferably 3-5 kgf/cm ² . If the blow pressure is too low, the inner ribs 3 may crack. Specifically, the blow pressure is, for example, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6 kgf/cm ² , and any one of the numerical values exemplified here is 2 It may be within a range between two.

(d) Post-treatment Step In the post-treatment step, the burrs 23d formed outside the pinch-off portions 21b and 22b are removed to obtain the foam molded body 10 having the structure shown in FIG.

A final product can be obtained by subjecting the foam molded article 10 to various treatments. For example, when the final product is a duct, the bag portion of the foam molded body 10 can be cut to form an opening for circulating air.

Using the molding machine 1 shown in FIG. 3, a foam molded article 10 having the configuration shown in FIG. 1 was produced. For the raw material resin, a propylene homopolymer (manufactured by Borealis AG, trade name "Daploy WB140") and long-chain branched polypropylene (manufactured by Japan Polypropylene Corporation, trade name "EX6000K") were used at a mass ratio of 30:70. and LDPE base masterbatch containing 20 wt% sodium hydrogen carbonate foaming agent as a nucleating agent (manufactured by Dainichiseika Kogyo Co., Ltd., trade name "Fine Cell Master P0217K") for 100 parts by mass of resin. .0 parts by weight and 1.0 parts by weight of an LLDPE base masterbatch containing 40 wt% carbon black as a colorant. The temperature of each part was controlled so that the temperature of the foamed parison 23 was 190 to 200.degree. The blowing agent was injected through injector 16 using _N2 gas.

The foamed parison 23 formed under the above conditions was placed between the molds 21 and 22 and subjected to blow molding to produce the foamed molded article 10 shown in FIG.

Detailed conditions are as follows.
Expansion ratio of the entire foam molded article 10: 2 Average thickness of the entire foam molded article 10: 2 mm
Distance S between tip 24a and cavity surface 22a: 4 mm
Thickness Ts of slide core 24: 4 mm

A cross-sectional photograph of the foam molded article 10 is shown in FIG. In the photograph of FIG. 8, W2/W1=2.84 and P2/P1=1.52.

REFERENCE SIGNS LIST 1: Molding machine 2: Resin supply device 3: Inner rib 3a: Welding mark 3b: Tip 10: Foam molding 10a: Base wall 10b: Opposing wall 10c: Surrounding wall 11: Raw material resin 11a: Molten resin 12: Hopper 13: Extruder 13a: Cylinder 16: Injector 17: Accumulator 17a: Cylinder 17b: Piston 18: Head 21: First mold 21a: Cavity surface 21b: Pinch-off part 22: Second mold 22a: Cavity surface 22b: Pinch-off part 23: Foamed parison 23a: base portion 23b: facing portion 23c: concave portion 23d: flash 24: slide core 24a: tip 25: connecting pipe 27: connecting pipe 28: connecting portion

Claims (6)

A foam molded body having a base wall and an opposing wall spaced apart from each other,
The foam molded body has an inner rib between the base wall and the opposing wall,
The inner rib extends from the base wall toward the opposing wall, and a tip of the inner rib is welded to the opposing wall,
The foam-molded article, wherein the inner rib is configured such that the expansion ratio increases toward the tip . A foam molded body having a base wall and an opposing wall spaced apart from each other,
The foam molded body has an inner rib between the base wall and the opposing wall,
The inner rib extends from the base wall toward the opposing wall, and a tip of the inner rib is welded to the opposing wall,
Let D be the distance between the inner surface of the base wall and the inner surface of the opposing wall,
Let P1 be the foaming ratio of the inner rib at a portion within the range of 0.0D to 0.2D from the inner surface of the base wall,
Assuming that the expansion ratio of the inner rib at a portion within the range of 0.8D to 1.0D from the inner surface of the base wall is P2,
A foam molded article, wherein P2/P1 is 1.2 or more . The foam molded article according to claim 1 or claim 2 ,
The foam-molded article, wherein the inner rib has a shape in which the width increases toward the tip. The foam molded article according to any one of claims 1 to 3 ,
Let D be the distance between the inner surface of the base wall and the inner surface of the opposing wall,
W1 is the width of the inner rib at a position 0.1D from the inner surface of the base wall,
Assuming that the width of the inner rib at the position of 0.9D from the inner surface of the base wall is W2,
A foam molded article, wherein W2/W1 is 1.5 or more. A method for manufacturing a foamed molded product using first and second molds that can be opened and closed,
The first mold has a slide core whose projection length from the cavity surface of the first mold is variable,
Equipped with an arrangement process, a mold closing process, and a blow process,
In the arranging step, the foamed parison is arranged between the first and second molds,
The foamed parison has a base portion facing the first mold and a facing portion facing the base portion,
In the mold closing step, the first and second molds are closed while the slide core protrudes from the cavity surface, thereby forming a concave portion recessed from the base portion toward the facing portion, and welding the tip of the concave portion to the facing portion;
In the blowing step, blow pressure is applied to the foamed parison in the first and second molds while retracting the slide core ,
The method , wherein the time from the completion of mold closing of the first and second molds to the start of retraction of the slide core is 1 to 5 seconds . 6. The method of claim 5 , wherein
The method, wherein the blow pressure is 2 to 6 kgf/cm ² .

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