JP2021105115A - Foam molded body - Google Patents

Abstract

To provide a foam molded body excellent in fire retardancy.SOLUTION: The invention provides a foam molded body formed by foam molding of a resin composition including a base resin and a flame retardant. An expansion ratio of the foam molded body is 1.1-9.0 times. The base resin includes polyolefin. A blending quantity of the flame retardant in the resin composition is 0.1-10 mass%.SELECTED DRAWING: Figure 1

Description

The present invention relates to an effervescent molded product.

Ducts are installed on the dashboard and ceiling of automobiles to allow air from the air conditioner to pass through. A foam molded product may be used for such a duct in consideration of heat insulation and quietness (Patent Document 1).

Japanese Unexamined Patent Publication No. 2015-124380

By the way, the foam molded product may be required to have flame retardancy, and in order to enhance the flame retardancy, a flame retardant may be added to the resin composition constituting the foam molded product. However, depending on the blending amount of the flame retardant, the flame retardancy may not be sufficiently exhibited.

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

According to the present invention, it is a foam molded product formed by foam molding a resin composition containing a base resin and a flame retardant, and the foaming ratio of the foam molded product is 1.1 to 9.0 times. A foamed molded product is provided, wherein the base resin contains polyolefin and the amount of the flame retardant in the resin composition is 0.1 to 10% by mass.

The present inventor has determined that in a foam molded product having a specific foaming ratio and a specific base resin, a foamed molded product having excellent flame retardancy can be obtained by setting the content of the flame retardant within a specific range. The heading has led to the completion of the present invention.

Hereinafter, various embodiments of the present invention will be illustrated. The embodiments shown below can be combined with each other.
Preferably, it is the foam-molded article described above, wherein the foaming ratio is 3.0 to 6.0 times.
Preferably, it is the foam-molded article described above, and the foam-molded article is a hollow or sheet-like foam-molded article.
Preferably, the foam-molded product according to the above description is a foam-molded product having an average cell diameter of 100 to 1000 μm in the thickness direction.
Preferably, it is the foam-molded article described above, and the foam-molded article is a foam-molded article in which the foaming agent contains carbon dioxide gas.

An example of a cross-sectional photograph of the foam molded body 1 is shown. The configuration of the molding machine 10 that can be used for manufacturing the foam blow molded article is shown. It is an enlarged view of the vicinity of the head 18 and the molds 21 and 22 of FIG. It is a figure corresponding to FIG. 3 which shows the head 18 and the molds 21 and 22 which can be used for manufacturing a foam sheet molded article. A state in which the molds 21 and 22 of FIG. 4 are closed is shown.

Hereinafter, embodiments of the present invention will be described. The various features shown in the embodiments shown below can be combined with each other. In addition, the invention is independently established for each feature.

1. 1. Foam molded product 1
As shown in FIG. 1, the foam molded product 1 of the embodiment of the present invention is formed by foam molding a resin composition containing a base resin and a flame retardant.

<Base resin>
The base resin contains polyolefin. Examples of the polyolefin include polyester, polypropylene, ethylene-propylene copolymer and a mixture thereof. The base resin may be composed of only polyolefin or may contain other thermoplastic resins. Examples of other thermoplastic resins include polyamide resins and polyester resins. The content of the polyolefin in the base resin is, for example, 50 to 100% by mass, specifically, for example, 50, 60, 70, 80, 90, 99, 100% by mass, and the numerical values exemplified here are used. It may be within the range between any two.

<Flame retardant>
The flame retardant is composed of any compound that enhances the flame retardancy of the base resin. Examples of the flame retardant include a phosphorus-based flame retardant, a halogen-based flame retardant, and a hindered amine-based flame retardant. A hindered amine-based flame retardant is particularly preferable from the viewpoint of improving the flame retardancy of polyolefin.

The blending amount of the flame retardant in the resin composition is 0.1 to 10% by mass. This is because if the blending amount is too small, the effect of improving flame retardancy may be insufficient, and if the blending amount is too large, the moldability may be lowered. Specifically, the blending amount is, for example, 0.1, 0.5, 1, 1.5, 2, 3, 4, 5, 6, 7, 8, 9, and 10% by mass, and is exemplified here. It may be within the range between any two of the given numerical values.

<Effervescent molded product 1>
Examples of the foam molded product 1 include a foam blow molded product formed by foam blow molding and a foam sheet molded product formed by foam sheet molding. Examples of the foam blow molded product include foam ducts used in automobiles and the like. Examples of the foam sheet molded body include automobile interior members (eg, door trim).

The foaming ratio of the foam molded product 1 is 1.1 to 9.0 times, preferably 3.0 to 6.0 times. If the foaming ratio is too small, the heat insulating property and lightness may be insufficient, and if the foaming ratio is too large, the rigidity may be insufficient. Specifically, the foaming ratio is, for example, 1.1, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, It is 6.0, 7.0, 8.0, 9.0 times, and may be within the range between any two of the numerical values exemplified here. The foaming ratio is a value obtained by [density of resin composition before foaming / density of resin composition after foaming (bulk density)].

The foam molded product 1 is preferably hollow or sheet-shaped. In this case, since the foamed molded product 1 is easily burned, the technical significance of imparting flame retardancy is particularly great.

The wall thickness of the wall constituting the foam molded product 1 is, for example, 1.0 to 6.0 mm. If the wall thickness is too thin, the rigidity of the foam molded body 1 may be insufficient, and if the wall thickness is too large, the weight of the foam molded body 1 may become excessive. The wall thickness is preferably 2.0 mm or more, and more preferably 3.0 mm or more. This is because the larger the wall thickness, the better the flame retardancy of the foam molded product 1. Specifically, the wall thickness is, for example, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5. , 6.0 mm, which may be within the range between any two of the numerical values exemplified here.

The foam molded product 1 preferably has an average bubble diameter of 100 to 1000 μm in the thickness direction. If the average cell diameter is too small, the heat insulating property and lightness may be insufficient, and if the average cell diameter is too large, the rigidity may be insufficient. The average cell diameter is preferably 200 μm or more, and more preferably 400 μm or more. This is because the larger the average cell diameter, the more remarkable the effect of improving the flame retardancy by adding the flame retardant. Specifically, the average bubble diameter is, for example, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000 μm, and is within the range between any two of the numerical values exemplified here. You may.

The average cell diameter is measured by the following method.
-First, as shown in FIG. 1, a cross-sectional photograph is taken at a magnification of 50 times.
-Next, in the cross-sectional photograph, five reference lines R1 to R5 extending in the thickness direction are drawn. The distance between the reference lines is 500 μm.
-For each reference line, count the number of bubbles that the reference line passes through.
-Measure the maximum length in the thickness direction (the length at the part where the length in the thickness direction is the longest) for each bubble.
-Calculate the tentative average bubble diameter for each reference line according to Equation 1. Further, the average cell diameter is calculated by arithmetically averaging the tentative average cell diameters calculated for each reference line.
(Equation 1) Temporary average bubble diameter = total maximum length of all counted bubbles / number of counted bubbles

Examples of the foaming agent for foaming the resin composition constituting the foamed molded product 1 include a physical foaming agent, a chemical foaming agent, and a mixture thereof, and a physical foaming agent is preferable. As the physical foaming agent, inorganic physical foaming agents such as air, carbon dioxide, nitrogen gas, and water, organic physical foaming agents such as butane, pentane, hexane, dichloromethane, and dichloroethane, and their supercritical fluids are used. be able to. Examples of the chemical foaming agent include those that generate carbon dioxide gas by a chemical reaction between an acid (eg, citric acid or a salt thereof) and a base (eg, baking soda). The foaming agent preferably contains carbon dioxide gas. In this case, the average cell diameter becomes large, and the flame retardant improving effect of the flame retardant tends to be high.

2. Method for Manufacturing Foam Mold 1 Here, the method for manufacturing the foam molded body 1 will be described by taking a foam blow molded body and a foam sheet molded body as examples.

2-1. Foam blow molded article 2-1-1. Configuration of Molding Machine 10 The molding machine 10 that can be used for manufacturing a foam blow molded article will be described with reference to FIGS. 2 to 3. The molding machine 10 includes a resin supply device 20, a head 18, and first and second molds 21 and 22. The resin supply device 20 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.
Hereinafter, each configuration will be described in detail.

<Hopper 12, extruder 13>
The hopper 12 is used to put the raw material resin 11 into the cylinder 13a of the extruder 13. The form of the raw material resin 11 is not particularly limited, but is usually in the form of pellets. The raw material resin 11 is composed of the above-mentioned resin composition. In one example, the raw material resin 11 includes pellets of the base resin and pellets of a masterbatch containing a flame retardant in the base resin. The blending amount of the flame retardant can be adjusted by changing the blending ratio of the pellets of the base resin and the pellets of the masterbatch. The raw material resin 11 is charged into the cylinder 13a from the hopper 12 and then heated in the cylinder 13a to be melted into a molten resin. Further, it is conveyed toward the tip of the cylinder 13a by the rotation of the screw arranged in the cylinder 13a.

<Injector 16>
The cylinder 13a is provided with an injector 16 for injecting a foaming agent into the cylinder 13a. As the foaming agent, those described above can be used. The physical foaming agent is usually charged from the injector 16. The chemical foaming agent is usually charged from the hopper 12.

<Accumulator 17, head 18>
The molten resin 11a, which is obtained by melt-kneading the raw material resin and the foaming agent, is extruded from the resin extrusion port of the cylinder 13a and injected into the accumulator 17 through the connecting pipe 25. The accumulator 17 includes a cylinder 17a and a piston 17b slidable inside the cylinder 17a, and the molten resin 11a can be stored in the cylinder 17a. Then, 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 pushed out from the die slit provided in the head 18 through the connecting pipe 27 and hung down to form a cylinder. The foamed parison 23 is formed.

<1st and 2nd molds 21 and 22>
The foamed parison 23 is guided between the molds 21 and 22. As shown in FIG. 3, the molds 21 and 22 have cavities 21a and 22a, and pinch-off portions 21b and 22b are provided so as to surround the cavities 21a and 22a. The cavities 21a and 22a are configured to have the shape of the foam molded body 1 when the molds 21 and 22 are closed.

2-1-2. Method for Producing Foam Blow Molded Body The method for producing a foam blow molded article includes a molding step.

The molding step includes, for example, an extrusion step, a mold closing step, and a blowing step.

In the extrusion process, the foamed parison 23 is extruded between the molds 21 and 22. In the mold closing step, a part of the foamed parison 23 is confined in the cavities 21a and 22a between the molds 21 and 22 by closing the molds 21 and 22 after the extrusion step. Of the foamed parison 23, the portions confined in the cavities 21a and 22a form a bag shape. In the blowing process, air is blown into the bag-shaped foamed parison 23. At this time, the foamed parison 23 is shaped along the surface shapes of the cavities 21a and 22a to form a foamed blow molded article. After that, the molds 21 and 22 are opened, the foam blow molded product is taken out, and post-treatment such as deburring is performed to obtain a desired molded product.

2-2. Foam sheet molded product 2-2-1. Configuration of Molding Machine 10 A molding machine 10 that can be used for manufacturing a foamed sheet molded body will be described with reference to FIG. The configuration of the molding machine 10 is the same as that described in "2-1-1. Configuration of the molding machine 10" except that the configurations of the head 18 and the molds 21 and 22 are different, and thus the description will not be repeated.

In foamed sheet molding, as shown in FIG. 4, a sheet-shaped foamed parison 23 (hereinafter, referred to as “foamed resin sheet 23a”) is extruded from the head 18. Therefore, a T-die is usually used as the head 18.

The mold 21 has a convex portion 21c, and the mold 22 has a concave portion 22c. As shown in FIG. 5, with the molds 21 and 22 closed, the convex portion 21c is housed in the concave portion 22c, and the cavity C is provided between the convex portion 21c and the concave portion 22c.

2-2-2. Method for Manufacturing Foam Sheet Molded Body The method for manufacturing a foamed sheet molded body includes a molding step.

The molding step includes, for example, an extrusion step, a mold closing step, and a blowing step.

In the extrusion process, the foamed resin sheet 23a is extruded between the dies 21 and 22. In the mold closing step, a part of the foamed resin sheet 23a is confined in the cavity C between the convex portion 21c and the concave portion 22c by closing the molds 21 and 22 after the extrusion step.

Preferably, the thickness of the foamed resin sheet 23a is smaller than the thickness of the cavity C. In this case, even when the foamed resin sheet 23a is confined in the cavity C, there is a gap in the cavity C. In this state, decompression suction is performed with the molds 21 and 22. As a result, the foamed resin sheet 23a expands in the cavity C, and a foamed sheet molded body in the shape of the cavity C is obtained. According to such a method, the bubbles of the foamed resin sheet 23a are expanded by the reduced pressure suction after closing the molds 21 and 22, so that a foamed molded product having a large foaming ratio and a large bubble diameter can be obtained. After that, the molds 21 and 22 are opened, the foamed sheet molded product is taken out, and post-treatment such as deburring is performed to obtain a desired molded product.

The foamed sheet molded product may be manufactured by molding the foamed resin sheet 23a by another method. For example, it may be manufactured by molding using one mold (eg, vacuum forming). Further, two foamed resin sheets 23a may be vacuum-formed with separate molds, and the peripheral edges thereof may be welded to each other to form a hollow foamed molded product.

1. 1. Preparation of Samples Samples of foam blow molded article, foam sheet molded article, and non-foamed blow molded article were prepared according to the methods shown below and the conditions shown in Tables 1 and 2.

The numerical values of the formulations in Table 1 are mass ratios, and the details of various components in Table 1 are as follows.
WB140: Metallocene-based high melt tension polypropylene, manufactured by Borealis AG, trade name "Daple WB140"
BC4BSW: Polypropylene, manufactured by Japan Polypropylene Corporation, product name "Novatec PP / BC4BSW"
AH561: Polypropylene, manufactured by Sumitomo Chemical Co., Ltd., trade name "Sumitomo Noblen AH561"
NF325N: Gas phase method metallocene polyethylene, manufactured by Japan Polyethylene Corporation, trade name "Harmorex NF325N"
PEX999017: Carbon Black Master Batch, manufactured by Tokyo Ink Co., Ltd. CF40EJ: Chemical foaming agent, manufactured by Tokyo Ink Co., Ltd.

1-1. Foam blow molded article (No. 1-8)
Using the molding machine 10 shown in FIGS. 2 to 3, a foam blow molded article was produced by the following method.

As the raw material resin, a flame retardant (manufactured by Tokyo Ink Co., Ltd., hindered amine-based flame retardant, PEX-FRJ-91) in the amount shown in Table 2 is added to the raw material compound shown in Tables 1 and 2. Using.

The temperature of each part was controlled so that the temperature of the foamed parison 23 was 190 to 200 ° C. The physical foaming agent was injected via the injector 16. The injection amount of the foaming agent and the gap between the die slits of the head 18 were set so that the foaming ratio and the wall thickness of the molded product after cooling were the values shown in Table 2.

The foamed parison 23 was formed by extruding the molten resin 11a obtained under the above conditions at the basis weight shown in Table 2, and the foamed parison 23 was blow-molded using dies 21 and 22 to obtain No. Foam blow molded articles 1 to 8 were obtained.

1-2. Foam sheet molded product (No. 9 to 12)
Using a molding machine 10 having the same configuration as that of FIG. 2 except that the head (T die) 18 and the dies 21 and 22 having the shape shown in FIG. 5 are provided, under the same conditions as in “1-1. Foam blow molded article”. A foamed resin sheet was produced by extruding a molten raw material resin from the head 18, and the foamed resin sheet was molded to obtain No. 9 to 12 foam sheet molded products were obtained.

1-3. Non-foam blow molded article (No. 13-14)
Under the same conditions as in "1-1. Foam blow molded article" except that a foaming agent is not used, No. 13-14 non-foam blow molded articles were obtained.

2. Measurement of average cell diameter in the thickness direction For each sample, the average cell diameter in the thickness direction was measured. The results are shown in Table 2.

As shown in Table 2, the average bubble diameter in the thickness direction was about the same between the sample with 0% flame retardant and the sample with 1% flame retardant.

3. 3. Evaluation of combustion rate No. For samples 1-14, FMVSS No. The burning rate was measured according to the 302 flammability test. The results are shown in Table 2.

Table 2 also shows the delay effect calculated based on the following equation.
Delay effect (%) = 100 × {1- (combustion rate at 1% flame retardant) / (combustion rate at 0% flame retardant)}

The following can be seen from Table 2.
No. No. 13 to 14 than the non-foam blow molded article. The foam blow molded article or the foam sheet molded article of 1 to 12 had a larger delay effect. This result indicates that the foamed molded product has a greater effect of improving the flame retardancy by adding the flame retardant than the non-foamed molded product.

No. 1-4 and No. Comparing 5 to 8, the average bubble diameter in the thickness direction was larger and the delay effect was larger when the physical foaming agent was carbon dioxide gas than when the physical foaming agent was nitrogen gas. This result shows that the effect of the flame retardant can be remarkably exhibited by using carbon dioxide gas as the physical foaming agent or increasing the average cell diameter in the thickness direction.

No. Looking at 9 to 12, it can be seen that in the foamed sheet molded product, the combustion rate before the addition of the flame retardant is low, and the flame retardancy is remarkably improved by the addition of the flame retardant.

1: Foam molded body 10: Molding machine 11: Raw material resin 11a: Molten resin 12: Hopper 13: Extruder 13a: Cylinder 16: Injector 17: Accumulator 17a: Cylinder 17b: Piston 18: Head 20: Resin supply device 21: No. 1 Mold 21a: Cavity 21b: Pinch-off portion 21c: Convex portion 22: Second mold 22a: Cavity 22b: Pinch-off portion 22c: Recessed portion 23: Foamed parison 23a: Foamed resin sheet 25: Connecting pipe 27: Connecting pipe C: Cavity

Claims (5)

A foam molded product formed by foam molding a resin composition containing a base resin and a flame retardant.
The foaming ratio of the foamed molded product is 1.1 to 9.0 times.
The base resin contains polyolefin and
A foamed molded product in which the amount of the flame retardant compounded in the resin composition is 0.1 to 10% by mass. The foamed molded product according to claim 1.
A foamed molded product having a foaming ratio of 3.0 to 6.0 times. The foamed molded product according to claim 1 or 2.
The foamed molded product is a hollow or sheet-shaped foamed molded product. The foamed molded product according to claim 3.
The foam molded product is a foam molded product having an average cell diameter of 100 to 1000 μm in the thickness direction. The foamed molded product according to any one of claims 1 to 4.
The foamed molded product is a foamed molded product in which the foaming agent contains carbon dioxide gas.

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