JP2018141031A - Resin for foam molding, foam molding and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin for foam molding having excellent foam molding properties and low-temperature impact resistance.SOLUTION: A resin for foam molding contains component A, component B, and component C. The component A is a long-chain branched homo polypropylene, the component B is long-chain branched polypropylene, and the component C is polyethylene elastomer. When the total of the components A-C is 100 pts.mass, the content of the component A is 20-70 pts.mass, preferably 40-50 pts.mass, the content of the component B is 20-70 pts.mass, preferably 40-60 pts.mass, and the content of the component C is 1-20 pts.mass, preferably 5-10 pts.mass. According to a method for producing a foam molding by blow molding, the resin for foam molding and a foaming agent (raw material resin 11) are melted and mixed with an extruder 13 for extrusion, to form a foamed parison 23, and mold it in a mold, thereby obtaining a foam molding.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a foam molding resin, a foam molded article, and a method for producing the same.

  For example, various air-conditioning ducts that are mounted in an instrument panel of an automobile are known as foam blow molded products. For these air conditioning ducts, foam ducts formed by molding a foamed resin material are widely used. The foam duct is lightweight and can be easily manufactured by, for example, adding a foaming agent to a resin material such as polyolefin resin, melt-kneading, and blow-molding a foam parison extruded from a die of an extruder.

  Polyolefin resins are widely used as resin materials used for foam blow molded products, and polypropylene resins are generally used (Patent Document 1).

  In Patent Document 1, a foaming agent is added to a mixed resin obtained by mixing a foam main material composed of a propylene homopolymer, a diluent composed of block polypropylene, and a modifier composed of a polyethylene-based elastomer, and blow molded for an automobile. A duct is disclosed.

WO2013 / 111692

  By the way, when this inventor examined in detail about the foam moldability of the mixed resin currently disclosed by patent document 1, when content of the foam main material in mixed resin is 80 mass parts or more, foam molding is carried out. However, when the content of the foam main material is less than 80 parts by mass, it has been found that the foam moldability is rapidly impaired as the content of the foam main material is reduced.

  On the other hand, it was found that when the content of the foam main material in the mixed resin is too large, the low-temperature impact resistance is lowered, so that the duct may be damaged during transportation.

  This invention is made | formed in view of such a situation, and provides the resin for foam molding excellent in foam moldability and low temperature impact resistance.

  According to the present invention, component A, component B and component C are contained, said component A is a long-chain branched homopolypropylene, said component B is a long-chain branched block polypropylene, and said component C is When the total of the components A to C is 100 parts by mass, the content of the component A is 20 to 70 parts by mass and the content of the component B is 20 to 70 parts by mass. There is provided a resin for foam molding in which the content of component C is 1 to 20 parts by mass.

  As a result of intensive studies, the present inventor has found that the foaming moldability and the low-temperature impact resistance can be improved by blending the components A to C at a specific ratio, and the present invention has been completed. It was.

Hereinafter, various embodiments of the present invention will be exemplified. The following embodiments can be combined with each other.
Preferably, when the total of the components A to C is 100 parts by mass, the content of the component A is 40 to 50 parts by mass, the content of the component B is 40 to 60 parts by mass, and the component The C content is 5 to 10 parts by mass.
Preferably, the long chain branched homopolypropylene is a peroxide-modified long chain branched homopolypropylene, and the long chain branched block polypropylene is a polymerized long chain branched block polypropylene.

  According to another aspect of the present invention, a foamed parison is formed by extruding a foamed resin formed by melting and kneading the foam molding resin and the foaming agent in the foamed extruder from the foamed extruder, and forming the foamed parison. There is provided a method for producing a foamed molded product, comprising a step of molding to obtain a foamed molded product.

  According to still another aspect of the present invention, there is provided a foam-molded article formed by using the above-mentioned foam-molding resin, and a falling ball breakage height when a 500 g ball is dropped at an environmental temperature of -10 ° C is 40 cm. The foamed molded body is provided as described above.

1 shows an example of a foam molding machine 1 that can be used in a method for producing a foam molded body according to an embodiment of the present invention. It is a perspective view which shows the foaming duct 10 which is an example of a foaming molding. It is a graph which shows the relationship between the ratio of the component A, and a foaming magnification retention.

  Hereinafter, embodiments of the present invention will be described. Various characteristic items shown in the following embodiments can be combined with each other. In addition, the invention is independently established for each feature.

1. Foam Molding Resin The foam molding resin of one embodiment of the present invention contains Component A, Component B, and Component C. Hereinafter, each component will be described in detail. In the following description, polypropylene is denoted by PP, polyethylene is denoted by PE, and ethylene propylene rubber is denoted by EPR.

<Component A: Long-chain branched homo PP>
Component A is a long chain branched homo PP. The long-chain branched homo PP is a homo PP having a long-chain branched structure, and is excellent in foam moldability but has a low temperature impact resistance. The long-chain branched homo PP preferably has a weight average branch index g of 0.9 or less.

  MT (melt tension) of the long-chain branched homo PP is preferably 100 to 500 mN, specifically, for example, 100, 150, 200, 250, 300, 350, 400, 450, 500 mN, and the numerical values exemplified here It may be within the range between any two.

  The MFR (melt flow rate) of the long chain branched homo PP is preferably 0.5 to 7 (g / 10 min), specifically, for example, 0.5, 1, 2, 3, 4, 5, 6, 7 (g / 10 minutes), and may be within a range between any two of the numerical values exemplified here.

  The long chain branched homo PP is preferably formed by peroxide modification (that is, peroxide modified long chain branched homo PP). Peroxide modification means forming a long chain branch by melt-extruding a mixture of linear homo PP and peroxide with a twin screw kneader.

  When the total of components A to C is 100 parts by mass, the content of component A is 20 to 70 parts by mass, preferably 40 to 50 parts by mass, specifically, for example, 20, 25, 30, 35. , 40, 45, 50, 55, 60, 65, 70 parts by mass, and may be in a range between any two of the numerical values exemplified here. If there is too little component A, foam moldability will become inadequate, and if there is too much component A, low temperature impact resistance will become inadequate.

<Component B: Long-chain branched block PP>
Component B is a long chain branched block PP. The long chain branch block PP is a block PP having a long chain branch structure. The long-chain branched block PP usually contains a rubber component, and has a feature that the low-temperature impact resistance is high, although the foam moldability is inferior to that of the long-chain branched homo PP. The block PP is a block copolymer in which a PE block and an EPR block are dispersed in a homo PP block.

  In Patent Document 1, a foamed resin containing a long-chain branched homo PP and a linear block PP is used. However, in such a formulation, if the proportion of the linear block PP is increased, the low-temperature impact resistance is improved, but foaming is performed. There was a problem that the moldability deteriorated rapidly. On the other hand, the long-chain branched block PP used in the present embodiment has a lower degree of foam moldability than the straight-chain block PP. It is possible to improve the low temperature impact resistance while suppressing.

  The long chain branch block PP preferably has a weight average branch index g of 0.9 or less.

  The MT (melt tension) of the long-chain branched block PP is preferably 50 to 500 mN, specifically, for example, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500 mN, exemplified here It may be within a range between any two of the numerical values.

  The MFR (melt flow rate) of the long-chain branched block PP is preferably 1 to 7 (g / 10 minutes), specifically, for example, 1, 2, 3, 4, 5, 6, 7 g / 10 minutes) There may be a range between any two of the numerical values exemplified here.

  The long-chain branched block PP is preferably one produced by polymerizing homo PP produced by macromer copolymerization and ethylene (that is, polymerized long-chain branched block PP). The macromer copolymerization is composed of a first reaction (production of propylene macromer by polymerization of propylene monomer (a substance obtained by reacting a plurality of propylene)) and a second reaction (polymerization of propylene monomer and propylene macromer). In the second reaction, propylene monomers react in a linear form, and propylene macromer reacts on the side of the linear chain to form a long chain branch. By polymerizing homo PP obtained by macromer copolymerization and ethylene, a part of PP and ethylene are polymerized to generate EPR. Therefore, compared with peroxide-modified long chain branched homo PP, low temperature impact resistance is improved. high. In addition, since no peroxide is used, changes in MFR and MT during recycling are small compared to peroxide-modified long-chain branched homo PP.

  When the total of components A to C is 100 parts by mass, the content of component B is 20 to 70 parts by mass, preferably 40 to 60 parts by mass, specifically, for example, 20, 25, 30, 35. , 40, 45, 50, 55, 60, 65, 70 parts by mass, and may be in a range between any two of the numerical values exemplified here. When the component B is too small, the low-temperature impact resistance becomes insufficient, and when the component B is too large, the foam moldability becomes insufficient.

<Component C: PE elastomer>
Component C is a PE elastomer. PE elastomer is a fine dispersion of olefin rubber in a matrix of PE resin. It has excellent compatibility with PP resin, and gives rubber elasticity to resin material to improve impact resistance. It has the feature of being able to. In addition to the PP resin, the PE elastomer is used in combination to improve the impact resistance and achieve both foam moldability and impact resistance.

  The MT of the PE-based elastomer is preferably 10 to 100 mN, specifically, for example, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 mN, and any of the numerical values exemplified here is 2 It may be within a range between the two.

  The MFR of the PE elastomer is preferably from 0.1 to 5 (g / 10 minutes), specifically, for example, 0.1, 0.5, 1, 2, 3, 4, 5 (g / 10 minutes) It may be within the range between any two of the numerical values exemplified here.

  When the total of components A to C is 100 parts by mass, the content of component C is 1 to 20 parts by mass, preferably 5 to 10 parts by mass, specifically, for example, 1, 2, 3, 4 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 parts by mass, the range between any two of the numerical values exemplified here It may be within. When the content of Component C is 5 parts by mass or more, the impact resistance improving effect is particularly remarkable. The greater the proportion of PE-based elastomer, the more advantageous for impact resistance improvement, but when the proportion of PE-based elastomer is too large, the proportion of PP-based resin is relatively reduced, such as foam moldability, It becomes difficult to maintain the excellent physical properties of the PP resin. From such a viewpoint, the proportion of the PE elastomer is preferably 10% by mass or less. That is, the proportion of the PE elastomer is preferably 5 to 10% by mass.

2. Method for Producing Foam Molded Body A method for producing a foam molded body according to an embodiment of the present invention is to extrude a foam resin obtained by melting and kneading the above foam molding resin and a foaming agent in a foam extruder from the foam extruder. Forming a foamed parison, and forming the foamed parison by molding the foamed parison.

The method of this embodiment can be implemented using the foam molding machine 1 illustrated by FIG. 1, for example. The foam molding machine 1 includes a resin supply device 2, a head 18, and a split mold 19. 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.
Hereinafter, each configuration will be described in detail.

<Hopper 12, Extruder 13>
The hopper 12 is used for charging the raw resin 11 into the cylinder 13 a of the extruder 13. Although the form of the raw material resin 11 is not specifically limited, Usually, it is a pellet form. The raw material resin is the resin for foam molding described above. In the case of molding using only the virgin resin, a modifying material is added to the above-described foam molding resin as necessary. When the recovered resin material is used, virgin resin is added to the pulverized recovered resin material in a predetermined ratio. The virgin resin can be added so that the mass ratio in the raw material resin 11 is, for example, 10 to 30%.

  The raw material resin 11 is poured into the cylinder 13a from the hopper 12 and then melted by being heated in the cylinder 13a to become a molten resin. Moreover, it is conveyed toward the front-end | tip of the cylinder 13a by rotation of the screw arrange | positioned in the cylinder 13a. A screw is arrange | positioned in the cylinder 13a and conveys molten resin by kneading | mixing by the rotation. A gear device is provided at the base end of the screw, and the screw is driven to rotate by the gear device. The number of screws arranged in the cylinder 13a may be one or two or more.

<Injector 16>
The cylinder 13a is provided with an injector 16 for injecting a foaming agent into the cylinder 13a. Examples of the foaming agent injected from the injector 16 include physical foaming agents, chemical foaming agents, and mixtures thereof, but physical foaming agents are preferred. As physical foaming agents, inorganic physical foaming agents such as air, carbon dioxide, nitrogen gas, and water, and organic physical foaming agents such as butane, pentane, hexane, dichloromethane, dichloroethane, and their supercritical fluids are used. be able to. Among these, it is preferable to use air, carbon dioxide gas, or nitrogen gas as the foaming agent. By using these, mixing of organic substances can be prevented, and deterioration of durability and the like can be suppressed. By using a supercritical fluid, foaming can be performed uniformly and reliably. As the supercritical fluid, carbon dioxide, nitrogen or the like is preferably used. If nitrogen, the critical temperature is 149.1 ° C. and the critical pressure is 3.4 MPa or more. If carbon dioxide, the critical temperature is 31 ° C., the critical pressure. It is obtained by setting it to 7.4 MPa or more. Examples of the chemical foaming agent include those that generate carbon dioxide by a chemical reaction between an acid (eg, citric acid or a salt thereof) and a base (eg, sodium bicarbonate). The chemical foaming agent may be supplied from the hopper 12 instead of being injected from the injector 16.

<Accumulator 17, head 18>
The foamed resin obtained by melt-kneading the raw material resin and the foaming agent is extruded from the resin extrusion port of the cylinder 13 a and injected into the accumulator 17 through the connecting pipe 25. The accumulator 17 includes a cylinder 17a and a piston 17b that can slide inside the cylinder 17a, and foamed resin can be stored in the cylinder 17a. Then, by moving the piston 17b after a predetermined amount of foamed resin is stored in the cylinder 17a, the foamed resin is pushed down from the slit provided in the head 18 through the connecting pipe 27 to form the foamed parison 23. . The shape of the foam parison 23 is not particularly limited, and may be a cylindrical shape or a sheet shape. The extrusion speed of the foam parison 23 is set to 700 kg / hour or more, for example. The accumulator 17 can also be built in the head 18 and may push down the piston 17b in the vertical direction.

<Split mold 19>
The foam parison 23 is guided between the pair of split molds 19. A foamed molded article is obtained by molding the foamed parison 23 using the split mold 19. The method of molding using the split mold 19 is not particularly limited, and may be blow molding in which air is blown into the cavity of the split mold 19, and the inside of the cavity from the inner surface of the cavity of the split mold 19 may be used. May be vacuum forming in which the foamed parison 23 is formed under reduced pressure, or a combination thereof. In the case of blow molding, air is blown in a pressure range of 0.05 to 0.15 MPa, for example.

  After molding, portions other than the finished product in the resin material that has been cooled and solidified can be pulverized into a recovered resin material, which can be used again for the production of a foam molded article.

3. Foam Molded Body An example of the foam molded body is a foam duct 10 as shown in FIG. The foam duct 10 is configured to circulate conditioned air supplied from an air conditioner unit (not shown) through an internal flow path, and to ventilate a desired part. In addition, as a shape of the foam duct 10, it is not limited to what is shown in FIG. 2, It can be set as arbitrary shapes according to a use, an installation place, etc.

  The foam duct 10 of the present embodiment is obtained by blow molding by sandwiching a foam parison formed by extruding a foam resin from a die of an extruder with a mold. In addition, the duct immediately after blow molding is in a state where both ends are closed, and both ends are cut into an open shape by trimming after blow molding.

  The foam duct 10 of the present embodiment is formed of a hollow foamed resin molded product whose tube wall is constituted by a foam layer. By adopting a configuration in which the foam layer has a closed cell structure, it is possible to obtain a duct that is lightweight and excellent in heat insulation. The closed cell structure is a structure having a plurality of independent cell cells, and means a cell having at least a closed cell ratio of 70% or more. With such a configuration, even when cooling air is circulated in the foam duct 10, the possibility of dew condensation can be almost eliminated.

  As described above, since the foam duct 10 of the present embodiment is formed using the mixed resin containing the components A to C at a specific ratio, it is possible to achieve both foam moldability and impact resistance. For example, it is possible to mold a foam duct having a foaming ratio of 2.5 times (2 to 3 times) and an average wall thickness of 2 mm (1.5 to 2.5 mm).

1. Production of Foam Duct A foam duct 10 was produced using the foam molding machine 1 shown in FIG. The inner diameter of the cylinder 13a of the extruder 13 was 50 mm, and L / D = 34. As the raw material resin, one containing components A to C and linear block PP shown in Table 1 in a mixing ratio (parts by mass) shown in Table 1 was used. In addition, with respect to 100 parts by mass of resin, an LDPE base masterbatch (produced by Dainichi Seika Kogyo Co., Ltd., trade name “Fine Cell Master P0217K”) containing 20 wt% sodium hydrogen carbonate-based blowing agent as a nucleating agent is 1.0. 1.0 part by weight of LLDPE base masterbatch containing parts by weight and 40 wt% carbon black as a colorant was added. The temperature of each part was controlled so that the temperature of the foamed parison 23 was 190 to 200 ° C. The number of rotations of the screw was 60 rmm, and the amount of extrusion was 20 kg / hr. The blowing agent was injected through the injector 16 using N ₂ gas. The injection amount is 0.4 [wt. %] (N ₂ injection amount / resin extrusion amount). The foamed parison 23 controlled the head 18 so that the thickness was 2 mm.

  After disposing the foamed parison 23 formed under the above conditions between the split molds 19, the split mold 19 was clamped to obtain the foam duct 10.

2. Evaluation About the produced foaming duct, the expansion ratio retention rate and low temperature impact resistance were evaluated by the following methods.

<Foaming ratio retention>
The expansion ratio retention was calculated based on the following formula. The reason why the expansion ratio in Comparative Example 1 was used as a reference is that, in Comparative Example 1, the ratio of WB140, which is a resin having excellent foam moldability, is 100%. The case where the expansion ratio retention rate was 90% or more was rated as ◯, and the case where it was less than 90% was rated as x.

(Formula 1) Foaming ratio retention [%] = {(foaming ratio in each example / comparative example) / (foaming ratio in comparative example 1)} × 100

<Low temperature impact resistance>
The low temperature impact resistance test was performed by dropping a 500 g sphere on the foam duct 10 at an environmental temperature of −10 ° C. The case where the falling ball breakage height was less than 40 cm was evaluated as x, and the case where it was 40 cm or more was evaluated as ◯.

The details of each component in Table 1 are as follows.
・ Long-chain branched homo-PP: manufactured by Borealis, trade name WB140 (introduced long-chain branched structure by peroxide modification, MT is 239.4 mN, MFR is 1.62 g / 10 min)
・ Long chain branched homo-PP: manufactured by Kaneka, trade name SLB047N (introduced long chain branched structure by peroxide modification, MT is 200 mN, MFR is 1.2 g / 10 min)
・ Long-chain branched block PP: manufactured by Nippon Polypro, trade name EX6000 (long-chain branched structure is introduced during polymerization, MT is 144.4 mN, MFR is 2.12 g / 10 min)
-PE elastomer (TPE): manufactured by Mitsui Chemicals, trade name DF605 (MT is 31.6 mN, MFR is 0.47 g / 10 min)
Linear block PP: Nippon Polypro, trade name BC4BSW (MT is 5.4 mN, MFR is 4.7 g / 10 min)

  MT uses a melt tension tester (manufactured by Toyo Seiki Co., Ltd.) for a long-chain branched homo PP, a long-chain branched block PP, and a linear block PP at a preheating temperature of 230 ° C. and an extrusion rate of 5.7 mm / min. This shows the tension when a strand is extruded from an orifice having a diameter of 2.095 mm and a length of 8 mm, and the strand is wound around a roller having a diameter of 50 mm at a winding speed of 100 rpm. MT is a value when the preheating temperature is 210 ° C. for the PE elastomer.

  MFR is a value measured for a long-chain branched homo PP, long-chain branched block PP, and linear block PP at a test temperature of 230 ° C. and a test load of 2.16 kg according to JIS K-7210. MFR is a value obtained by measuring PE elastomer at a test temperature of 190 ° C. and a test load of 2.16 kg according to JIS K-6922-1.

3. Discussion In all examples, when the total of components A to C is 100 parts by mass, the content of component A is 20 to 70 parts by mass, the content of component B is 20 to 70 parts by mass, Since the C content was 1 to 20 parts by mass, the expansion ratio retention and the low temperature impact resistance were good.
Since Comparative Examples 1, 3, 4, 11, 13, and 14 did not contain Component C, the low-temperature impact resistance was low.
In Comparative Examples 2 and 12, the component B was too little, so the low temperature impact resistance was low.
In Comparative Examples 5 to 7 and 15, since the component A was too small, the expansion ratio retention rate was low.
Although the comparative examples 8 and 16 contain the linear block PP instead of the component B, since the ratio is too small, low temperature impact resistance was low.
Comparative Examples 9 and 17 include linear block PP instead of Component B, and the foaming ratio retention rate is greatly increased despite the relatively small amount of the linear block PP being 20 to 30 parts by mass. Declined.
Comparative Example 10 contained only the linear block PP, and the expansion ratio was extremely small.

4). Preliminary experiment showing effect of using long-chain branched block PP Here, a preliminary experiment showing that the deterioration of foam moldability is suppressed by using the long-chain branched block PP instead of the linear block PP is shown. .

  Except for changing the composition of the raw material resin to that shown in Table 2, a foam duct was produced under the same conditions as in “1. Production of foam duct”, and the expansion ratio retention rate was calculated.

  In series A and C in Table 2, component A and component B are used together, and in series B and D, component A and linear block PP are used together. In series A and B, WB140 was used as component A, and in series C and D, SLB047N was used as component A. A graph plotting Table 2 is shown in FIG.

  As shown in Table 2 and FIG. 3, in the series B and D, when the ratio of the component A was reduced to 70%, the expansion ratio retention ratio became 90% or less. On the other hand, in series A and C, even when the proportion of component A was reduced to 40%, the expansion ratio retention rate was higher than 90%. This result indicates that the long-chain branched block PP as the component B has a smaller degree of worsening foam moldability than the linear block PP.

1: Foam molding machine 2: Resin feeder 10: Foam duct 11: Raw resin 12: Hopper 13: Extruder 13a: Cylinder 16: Injector 17: Accumulator 17a: Cylinder 17b: Piston 18: Head 19: Split mold 23: Foam parison 25: connecting pipe 27: connecting pipe

Claims (5)

Containing component A, component B, and component C;
Component A is a long chain branched homopolypropylene,
Component B is a long chain branched block polypropylene,
The component C is a polyethylene elastomer,
When the total of the components A to C is 100 parts by mass, the content of the component A is 20 to 70 parts by mass, the content of the component B is 20 to 70 parts by mass, and the content of the component C Resin for foam molding whose amount is 1 to 20 parts by mass.   When the total of the components A to C is 100 parts by mass, the content of the component A is 40 to 50 parts by mass, the content of the component B is 40 to 60 parts by mass, and the content of the component C The resin according to claim 1, wherein the amount is 5 to 10 parts by mass. The long chain branched homopolypropylene is a peroxide-modified long chain branched homopolypropylene,
The resin according to claim 1 or 2, wherein the long-chain branched block polypropylene is a polymerized long-chain branched block polypropylene.   A foamed parison is formed by extruding a foamed resin obtained by melt-kneading the foam molding resin according to any one of claims 1 to 3 and a foaming agent in a foaming extruder to form a foamed parison. A method for producing a foamed molded product, comprising a step of forming a parison to obtain a foamed molded product. A foam molded article formed using the foam molding resin according to any one of claims 1 to 3,
A foamed molded article having a falling ball breakage height of 40 cm or more when a 500 g ball is dropped at an environmental temperature of −10 ° C.