JP2020111697A - Method for producing polyolefin resin foamed particle - Google Patents

Abstract

To provide a method for producing a polyolefin resin foamed particle having excellent productivity and production cost.SOLUTION: A method for producing polyolefin resin foamed particles includes the steps of: mixing polyolefin resin particles, a dispersion medium, a silicate, a compound having a specific number of amino groups, and an inorganic foaming agent in a container, to prepare a dispersion; and releasing the dispersion to a zone of lower pressure than the container internal pressure.SELECTED DRAWING: None

Description

The present invention relates to a method for producing expanded polyolefin resin particles.

The polyolefin resin in-mold foam molded article (hereinafter, also simply referred to as a molded article) has features such as shape arbitrariness, energy absorption, light weight, and heat insulating property, which are advantages of the in-mold foam molded article. The molded body is produced by an in-mold foam molding method using foamed polyolefin resin particles (hereinafter also simply referred to as foamed particles) made of a polyolefin resin. Since the molded product has the characteristics described above, it is used in various applications such as automobile interior members, cushioning packaging materials, returnable boxes, heat insulating materials, and construction members.

As a method for producing expanded particles, conventionally, there is a method of preparing a dispersion liquid containing a polyolefin-based resin particle and a foaming agent in a container, and releasing the dispersion liquid under an atmosphere at a pressure lower than the internal pressure of the container to obtain expanded particles. Are known.

Here, in the method for producing expanded particles, a specific dispersion medium, a dispersant, and a dispersion aid are used for the purpose of preventing the polyolefin resin particles from adhering to each other in the dispersion prepared in the container. It is known to use agents and the like (Patent Documents 1 to 3).

Patent Document 1 discloses a mode in which a nonionic surfactant having an HLB value of 5 to 15 is used as a dispersion aid.

Patent Document 2 discloses a mode in which an aqueous medium having an electric conductivity of 0.00 mS/m to 20.00 mS/m is used as the aqueous medium (dispersion medium).

Patent Document 3 discloses an embodiment in which polypropylene resin particles contain an HN type hindered amine compound and kaolin is used as a dispersant.

JP, 10-130421, A International Publication WO2002/100929 JP-A-11-147972

However, the above-mentioned conventional techniques have a large amount of the dispersion medium with respect to the polyolefin resin particles, and there is room for further improvement from the viewpoint of productivity. Further, the above-described conventional technology has room for further improvement in terms of production cost.

One embodiment of the present invention has been made in view of the above problems, and an object thereof is to provide a novel method for producing expanded polyolefin resin particles, which is excellent in productivity and production cost.

As a result of intensive studies to solve the above problems, the present inventors have found that productivity is improved by mixing polyolefin resin particles, a dispersion medium, a silicate, a compound having an amino group and an inorganic blowing agent in a container. Further, they have found that a novel method for producing expanded polyolefin resin particles, which is excellent in production cost, can be provided, and completed the present invention.

That is, the present invention is as follows.
[1] A step of mixing a polyolefin resin particle, a dispersion medium, a silicate, a compound having an amino group and an inorganic foaming agent in a container to prepare a dispersion liquid, and a pressure lower than the internal pressure of the container. And the amount of the compound having an amino group is 0.0001 parts by weight or more and 0.5000 parts by weight or less with respect to 100 parts by weight of the polyolefin resin particles in the dispersion liquid. A method for producing expanded polyolefin resin particles.
[2] The method for producing expanded polyolefin resin particles according to [1], wherein the compound having an amino group is a hindered amine compound.
[3] The amount of the dispersion medium is 100 parts by weight or more and 250 parts by weight or less with respect to 100 parts by weight of the polyolefin resin particles in the dispersion liquid, [1] or [2]. Method for producing expanded resin particles.

According to one embodiment of the present invention, there is an effect that the productivity and the production cost are excellent.

One embodiment of the present invention will be described below, but the present invention is not limited to this. The present invention is not limited to each configuration described below, and various modifications can be made within the scope of the claims. Further, embodiments or examples obtained by appropriately combining the technical means disclosed in the different embodiments or examples are also included in the technical scope of the present invention. Furthermore, a new technical feature can be formed by combining the technical means disclosed in each embodiment. In addition, all the academic documents and patent documents described in this specification are incorporated as a reference in this specification.

Unless otherwise specified in the present specification, “A to B” representing a numerical range means “A or more (including A and larger than A) and B or less (including B and smaller than B)”.

Further, unless otherwise specified in the present specification, as the structural unit, a structural unit derived from the X ₁ monomer, a structural unit derived from the X ₂ monomer,... And an X _n monomer (n is And an integer of 2 or more) is also referred to as an X ₁ /X ₂ /... /X _n copolymer. The X ₁ /X ₂ /... /X _n copolymer is not particularly limited in the polymerization mode, unless otherwise specified, and may be a random copolymer or a block copolymer. Or a graft copolymer. Further, unless otherwise specified in the present specification, as the structural unit, a structural unit derived from the X ₁ monomer, a structural unit derived from the X ₂ monomer,... And an X _n monomer (n is An elastomer containing 2 or more) is also referred to as X ₁ /X ₂ /... /X _n rubber.

[1. Technical idea of one embodiment of the present invention]
As a result of diligent studies by the present inventors, they have found that the techniques described in the above-mentioned prior art documents 1 to 3 have room for improvement or problems as described below.

The technique described in Patent Document 1 has problems in production cost and environment, and there is room for improvement. Specifically, in Examples and Comparative Examples of Patent Document 1, tricalcium phosphate is used as the inorganic dispersant. Tricalcium phosphate is expensive compared to silicates. In addition, when tribasic calcium phosphate is used as the dispersant, a larger amount of the secondary resin is used to prevent the coalescence of the polyolefin-based resin particles in the dispersion (a), as compared with the case of using the silicate. The present inventor has uniquely found that calcium triphosphate is required, and that the amount of sludge generated in (b) wastewater treatment increases.

The techniques described in Patent Documents 1 and 3 have a problem in terms of productivity, and there is room for further improvement. Specifically, in Examples and Comparative Examples of Patent Documents 1 and 3, 300 parts by weight of water is used with respect to 100 parts by weight of polypropylene resin particles. Thus, when the amount of the dispersion medium with respect to the polyolefin-based resin particles is large, the amount of the polyolefin-based resin particles (raw material) that can be supplied into the container having a constant volume decreases, so that one batch cycle (per production) The number of foamed polyolefin resin particles that can be produced is reduced. Therefore, the manufacturing method has room for improvement in productivity.

In the prior art, the present inventors have uniquely found that when the amount of the dispersion medium with respect to the polyolefin resin particles is simply reduced, the polyolefin resin particles in the dispersion liquid coalesce. "The coalescence of the polyolefin resin particles in the dispersion liquid" can be said to be "the dispersibility of the polyolefin resin particles in the dispersion liquid becomes poor".

The technique described in Patent Document 2 requires an aqueous medium prepared by a special purification method. Therefore, the technique described in Patent Document 2 has room for further improvement in terms of productivity and production cost.

An object of one embodiment of the present invention is to provide a novel method for producing expanded polyolefin resin particles, which is excellent in productivity and production cost. An object according to an embodiment of the present invention is, even when the amount of the dispersion medium with respect to the polyolefin resin particles is reduced, without causing the coalescence of the polyolefin resin particles in the dispersion liquid, the polyolefin resin foam particles It can be said that it is to provide a novel method for producing expanded polyolefin resin particles, which is capable of producing

As a result of intensive studies for solving the above problems, the present inventors have completed the present invention based on a technical idea that can be most avoided by those skilled in the art. Specifically, the present inventors have uniquely found that, by adding a hindered amine-based compound to a dispersion medium containing polyolefin-based resin particles, the above-mentioned problems can be surprisingly achieved. This will be described below.

In Patent Document 3, "a specific hindered amine compound has a property of being easily adsorbed by an inorganic substance, and when the specific hindered amine compound is contained in the resin particles, the inorganic substance added as a dispersant is Adheres hindered amine compounds in the vicinity and surely adheres to the resin particle surface." In other words, the hindered amine-based compound and the polyolefin-based resin are melt-kneaded, and the hindered amine-based compound is kneaded into the polyolefin-based resin particles, so that the hindered amine-based compound that is easily compatible with the dispersant attracts the dispersant to the resin particle surface. Can also be said. That is, conventionally, a person skilled in the art could think of the following two technical ideas:
(1) The idea that it is important to adhere a large amount of a dispersant to the polyolefin resin particles in order to prevent coalescence of the polyolefin resin particles in the dispersion liquid; and (2) the polyolefin resin. The idea that it is necessary to knead a hindered amine-based compound, which tends to be compatible with the dispersant, into the polyolefin-based resin particles in order to attach a large amount of the dispersant to the particles.

Based on these conventional technical ideas, when a hindered amine compound (a compound having an amino group in one embodiment of the present invention) is added to a dispersion medium containing polyolefin resin particles, a dispersant (for example, It is assumed that the silicate in one embodiment) has an affinity with the hindered amine-based compound in the dispersion liquid and is less likely to adhere to the polyolefin-based resin particles. Therefore, it can be said that the technical idea of adding a hindered amine compound to a dispersion medium containing polyolefin resin particles has hitherto been the technical idea that should be avoided most, or at least the technical idea that cannot be recalled by those skilled in the art.

Further, when a large amount of the used dispersant (silicate) adheres to the surface of the obtained expanded particles, in-mold expansion molding using the expanded particles, the fusion bonding property between the expanded particles is obstructed. In addition, the present inventor has found out uniquely. A molded product having inferior fusion bonding properties between foamed particles can be easily broken by impact or the like, and therefore tends to be inferior in energy absorption and buffering properties. In addition, a molded product having inferior fusion bonding properties between expanded particles cannot easily be used repeatedly because it is easily broken.

Therefore, in one embodiment of the present invention, the amount of silicate adhered to the surface of the expanded beads is reduced, and it is possible to provide polyolefin-based resin expanded beads having good fusion properties, and production of novel polyolefin-based resin expanded beads. It may be intended to provide a method.

[2. Method for producing expanded polyolefin resin particles]
A method for producing expanded polyolefin resin particles according to an embodiment of the present invention is a method in which a polyolefin resin particle, a dispersion medium, a silicate, a compound having an amino group and an inorganic foaming agent are mixed in a container to form a dispersion liquid. There is a step of preparing and a step of releasing the dispersion liquid to a pressure region lower than the internal pressure of the container, and the amount of the compound having an amino group is 100 parts by weight of the polyolefin resin particles in the dispersion liquid. Therefore, it is 0.0001 parts by weight or more and 0.5000 parts by weight or less.

In the present specification, the “method for producing expanded polyolefin resin particles according to one embodiment of the present invention” is also simply referred to as “the present production method”.

According to this manufacturing method, the amount of the dispersion medium with respect to the polyolefin resin particles can be reduced. Therefore, this manufacturing method has an advantage of being excellent in productivity. Further, according to the present production method, even when the compound having an amino group is used in a smaller amount as compared with the conventional technique, the coalescence of the polyolefin resin particles in the dispersion liquid can be prevented. Therefore, this manufacturing method has an advantage of being excellent in production cost. It should be noted that the fact that the polyolefin-based resin particles in the dispersion can be prevented from adhering to each other means that the dispersibility of the polyolefin-based resin particles in the dispersion can be improved. Even if the degree of coalescence of the obtained expanded particles is evaluated, the degree of coalescence of the polyolefin resin particles in the dispersion liquid (that is, the degree of dispersibility) can be evaluated. A method for evaluating the degree of coalescence of expanded particles will be described in detail in the following examples.

(2-1. Polyolefin resin particles)
(2-1-1. Polyolefin resin)
Examples of the polyolefin resin include polypropylene resin and polyethylene resin, and these may be used alone or in combination.

The base resin of the polypropylene resin is not particularly limited, polypropylene homopolymer, ethylene/propylene random copolymer, 1-butene/propylene random copolymer, ethylene/1-butene/propylene random copolymer, Examples thereof include ethylene/propylene block copolymers, 1-butene/propylene block copolymers, propylene/chlorinated vinyl copolymers and propylene/maleic anhydride copolymers. These may be used alone or in combination of two or more.

As the base resin for the polyethylene-based resin, a resin containing 50% by weight or more of a simple ethylene component is preferable. Examples of the base resin of the polyethylene resin include high-density polyethylene, low-density polyethylene, linear low-density polyethylene, ethylene/vinyl acetate copolymer, ethylene/propylene copolymer, ethylene/1-butene copolymer. , Ethylene/1-butene/propylene copolymer, ethylene/hexene copolymer, ethylene/4-methyl 1-pentene copolymer and the like. These may be used alone or in combination of two or more.

A copolymer such as an ethylene/propylene copolymer has, as a constitutional unit, a constitutional unit derived from an ethylene monomer (also referred to as an ethylene unit) and a constitutional unit derived from a propylene monomer (also referred to as a propylene unit). A case including and will be described. In this case, a copolymer containing more ethylene units than propylene units is called a polyethylene resin, and a copolymer containing more propylene units than ethylene units is called a polypropylene resin.

The polyolefin-based resin may contain a thermoplastic resin component and/or an elastomer component other than the polyolefin-based resin as long as the effect of the present invention is not impaired. Examples of the thermoplastic resin other than the polyolefin resin include vinyl acetate resin, thermoplastic polyester resin, acrylic ester resin, styrene resin, and polyamide resin. Examples of the elastomer other than the polyolefin resin include ethylene/propylene rubber and ethylene/propylene/butadiene rubber.

(2-1-2. Additive)
The polyolefin-based resin particles may contain various additives, if necessary, in addition to the polyolefin-based resin.

Examples of various additives that may be contained in the polyolefin resin particles include, for example, hydrophilic compounds, antioxidants, heat stabilizers, ultraviolet absorbers, flame retardants, antistatic agents, metal deactivators, carbon black, pigments, dyes. , Nucleating agents, bubble control agents and the like.

Examples of the hydrophilic compound include polyethylene glycol, glycerin, glycerin fatty acid ester, melamine and isocyanuric acid.

Examples of the antioxidant include hindered phenolic antioxidants. IRGANOX1010, IRGANOX3114, etc. can also be used as a hindered phenolic antioxidant.

Examples of the heat stabilizer include phosphorus-based heat stabilizers and sulfur-based heat stabilizers. IRGAFOS 168 or the like can also be used as the phosphorus-based heat stabilizer. IRGANOX PS802 and the like can also be used as the sulfur-based heat stabilizer.

Examples of the ultraviolet absorber include benzotriazole-based ultraviolet absorbers and triazine-based ultraviolet absorbers. TINUVIN234, TINUVIN316, etc. can also be used as a benzotriazole type ultraviolet absorber. TINUVIN 1600 or the like can be used as the triazine-based ultraviolet absorber. The ultraviolet absorber may be used in combination with HALS and/or a hindered amine light stabilizer. TINUVIN123 etc. can also be used as HALS. As the hindered amine light stabilizer, Chimassorb 2020 or the like can be used.

Examples of the flame retardant include phosphate ester flame retardants and melamine flame retardants. As the phosphate ester flame retardant, ADKSTAB FP-600 or the like can be used. MELAPUR MC25 or the like can be used as the melamine-based flame retardant. FLAMESTAB NOR116 or the like can be used as the flame retardant.

Examples of the antistatic agent include alkyldiethanolamide, alkyldiethanolamine, hydroxyethanolamine, fatty acid monoglyceride, fatty acid diglyceride, polyether/polyolefin resin block copolymer and the like.

IRGANOX MD1024 or the like can be used as the metal deactivator.

Examples of the cell regulator include talc, zinc borate, calcium carbonate, borax, aluminum hydroxide and the like.

Examples of carbon black include furnace black, channel black, acetylene black, thermal black and the like.

Examples of pigments include cyanine pigments, azo pigments, quinacridone pigments, penylene pigments, anthraquinone pigments, chromium oxide, and iron oxide.

The total amount of all the additives is preferably 25 parts by weight or less, more preferably 10 parts by weight or less, still more preferably 5 parts by weight or less, based on 100 parts by weight of the resin. When the total amount of the various additives is 25 parts by weight or less per 100 parts by weight of the resin, there is no fear that the dispersibility of the polyolefin-based resin particles in the dispersion will deteriorate in the step (a) of producing the expanded particles, b) the average cell diameter of the obtained expanded particles does not become too fine, (c) the expanded particles can provide a good molded product in the molding step, and (d) the resulting molded product has a reduced mechanical strength. It has the advantage that it does not.

(2-1-3. Method for producing polyolefin resin particles)
The step of producing the polyolefin-based resin particles is also referred to as a granulation step. The present manufacturing method may further include a granulation step.

As a method for producing the polyolefin resin particles, for example, (i) an extruder, a kneader, a Banbury mixer, a roll or the like is used to melt-knead the polyolefin-based resin composition to prepare a melt-kneaded product, and then (ii) By cooling the melt-kneaded product and (iii) forming the melt-kneaded product into a desired shape such as a cylindrical shape, an elliptical shape, a spherical shape, a cubic shape, a rectangular parallelepiped shape, or a cylindrical shape (straw shape). , A method of obtaining polyolefin resin particles.

The method for producing the polyolefin-based resin particles will be specifically described below by taking the case of using an extruder as an example. For example, the polyolefin-based resin particles can be produced by the following methods (1) to (5): (1) The polyolefin-based resin and, if necessary, other resins and various additives are blended. A blend is prepared, (2) the blend is put into an extruder and melt-kneaded to prepare a polyolefin-based resin composition, and (3) the polyolefin-based resin composition is extruded from a die included in the extruder, 4) The extruded polyolefin-based resin composition is solidified by cooling it by passing it through water, etc., and (5) the solidified polyolefin-based resin composition is shaped into a cylinder, an ellipse, a sphere, or a cube with a cutter. Shred into a desired shape such as a rectangular parallelepiped shape. Alternatively, in the above (3), the melt-kneaded polyolefin resin composition may be extruded directly into water from a die provided in an extruder, and immediately after that, it is shredded into a particle shape, cooled, and solidified. Thus, by melt-kneading the blended product, more uniform polyolefin resin particles can be obtained.

In the above (1), when other resins and various additives are used as needed, a mixture (resin composition) containing these other resins and various additives is granulated before blending with the polyolefin resin. You may have. That is, (i) another resin and various additives are blended to prepare a blend, and the blend is put into an extruder and melt-kneaded to prepare a resin composition, and (ii) the blend. Is added to an extruder to melt-knead to prepare a resin composition, (iii) the resin composition is extruded from a die included in the extruder, and (iv) the extruded resin composition is cooled or cooled. At the same time, the particles may be cut into desired particle shapes. In the above (2), instead of the blended product, the particles of the other resin and the various additives thus granulated and the polyolefin-based resin are put into an extruder and melt-kneaded to form a polyolefin-based resin composition. It can also be prepared.

Alternatively, in the above (1) and (2), after only the polyolefin-based resin is charged into the extruder, other resins and various additives are supplied from the middle of the extruder, if necessary, and they are fed in the extruder. It is also possible to mix and melt-knead to obtain a polyolefin-based resin composition, and then perform the subsequent steps (3) and thereafter.

Various additives used as necessary may be masterbatched. That is, a masterbatch resin in which an additive is contained in another resin at a high concentration may be prepared in advance. In this case, the masterbatch can be added as an additive. The resin used when preparing the masterbatch resin is preferably a polyolefin-based resin, and from the viewpoint of good compatibility, it may be masterbatched using the same type of polyolefin-based resin as the polyolefin-based resin of the base resin. Most preferred.

(2-1-4. Weight)
The weight of one particle of the polyolefin resin particles is preferably 0.2 mg/particle or more and 10 mg/particle or less, more preferably 0.5 mg/particle or more and 5 mg/particle or less. When the weight per particle of the polyolefin-based resin particles is (a) 0.2 mg/particle or more, there is no possibility that the handling property and the cutting property are deteriorated, and (b) 10 mg/particle or less, the polyolefin In the in-mold foam molding using the foamed particles obtained from the resin particles, there is no possibility that the filling property of the foamed particles into the mold is lowered.

(2-2. Silicate)
In the present production method, the silicate that is a silicate mixed with the polyolefin resin particles and that is used to prepare the dispersion has a function of preventing the polyolefin resin particles from aggregating in the dispersion. .. It can be said that the silicate is a dispersant. It can be said that this manufacturing method uses a silicate as a dispersant.

The polyolefin resin particles may contain silicate. For example, silicate may be used as a cell adjuster among various additives optionally contained in the polyolefin resin particles. In the present specification, any one of various additives contained in the polyolefin-based resin particles is a silicate, or when the additive contains a silicate, the additive is a polyolefin-based resin in the present production method. It should not be regarded as a silicate mixed with resin particles. In other words, in the present production method, the dispersion liquid contains a silicate as a substance other than the various additives contained in the polyolefin resin particles, and in the section (2-2. Silicate), The silicate will be described.

The silicate is not particularly limited, but examples thereof include clay minerals such as kaolin, talc, and clay. These silicates may be used alone or in combination of two or more.

The amount of silicate used varies depending on the type of silicate used, the type (composition) of polyolefin resin particles used and the amount used, and is not particularly limited. The amount of silicate used is preferably 0.01 parts by weight or more and 1.00 parts by weight or less with respect to 100 parts by weight of the polyolefin resin particles. The amount of the silicate used may be 0.50 parts by weight or less, may be less than 0.50 parts by weight, and may be 0.30 parts by weight or less with respect to 100 parts by weight of the polyolefin resin particles. May be less than 0.30 parts by weight, may be less than 0.20 parts by weight, may be less than 0.20 parts by weight, may be less than 0.10 parts by weight The amount may be less than 0.10 parts by weight, or may be 0.05 parts by weight or less. The amount of silicate used may be 0.03 parts by weight or more, may be 0.05 parts by weight or more, and may be 0.10 parts by weight or more with respect to 100 parts by weight of the polyolefin resin particles. It may be present, or may be 0.50 parts by weight or more. When the amount of the silicate used is (a) 0.01 part by weight or more based on 100 parts by weight of the polyolefin resin particles, the more the amount of the silicate used is, the more the polyolefin is used in the production of the expanded beads. When the possibility that the resin particles will adhere to each other is small and (b) is 1.00 part or less, the amount of silicate remaining on the surface of the obtained expanded particles decreases as the amount of silicate used decreases. Is less, and as a result, the meltability of the molded product produced using the obtained expanded particles tends to be good.

In the present production method, a dispersant other than silicate may be used. As the dispersant other than the silicate, a known dispersant can be used.

In the present production method, coalescence of the polyolefin resin particles in the container can be prevented in the production of expanded particles without using a component other than silicate as a dispersant. As described as a problem related to the technique described in Patent Document 1, in the case of using a silicate as a dispersant, as compared with the case of using tricalcium phosphate as a dispersant, the cost such as the addition amount and the It is excellent in environmental aspects such as sludge volume.

In addition, calcium phosphate (for example, tricalcium phosphate) may be used as a bubble control agent among various additives optionally contained in the polyolefin resin particles. This production method may be an aspect in which calcium phosphate is not substantially used in the step of preparing the dispersion liquid. In other words, in the present production method, the dispersion liquid may be substantially free of calcium phosphate as a substance other than various additives contained in the polyolefin resin particles. The term "substantially free of calcium phosphate" and "substantially free of calcium phosphate" means that the amount of calcium phosphate in the dispersion is the amount of polyolefin resin particles, excluding various additives contained in the polyolefin resin particles. Is intended to be 10 ppm or less.

(2-3. Compound having amino group)
In the present specification, the compound having an amino group is also simply referred to as “amino group-containing compound”. In the present production method, the amino group-containing compound that is mixed with the polyolefin-based resin particles, and the amino group-containing compound used for the preparation of the dispersion liquid is used in combination with the silicate to form a polyolefin-based compound in the dispersion liquid. It has a function of preventing coalescence of resin particles. The amino group-containing compound can also be said to be a dispersion aid. It can be said that the present production method uses an amino group-containing compound as a dispersion aid.

The polyolefin resin particles may contain an amino group-containing compound. For example, an amino group-containing compound may be used as a light stabilizer among various additives optionally contained in the polyolefin resin particles. In the present specification, any one of various additives contained in the polyolefin-based resin particles is an amino group-containing compound, or when containing an amino group-containing compound, the additive is used in the present production method. It is not regarded as an amino group-containing compound mixed with polyolefin resin particles. In other words, in the present production method, the dispersion liquid contains an amino group-containing compound as a substance other than the various additives contained in the polyolefin-based resin particles, and the dispersion of (2-3. In the section, such an amino group-containing compound will be described.

The amino group-containing compound is not particularly limited, and examples thereof include hindered amine compounds, ethanolamine compounds, nonionic surfactants, and cationic surfactants. These amino group-containing compounds may be used alone or in combination of two or more.

Examples of the hindered amine compound include bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate and dimethyl-1-(2hydroxyethyl)-4-hydroxy-2,2,6 succinate. ,6-Tetramethyl-4-piperidine polycondensate, 2-[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]-2-butylpropanedioic acid bis[1,2] , 2,6,6-Pentamethyl-4-piperidinyl], bis-(N-methyl-2,6,6,6-tetramethyl-4-piperidinyl) sebacate, tetrakis(2,6,6,6-tetra- Methyl-4-piperidyl)1,2,3,4-butanetetracarboxylate, poly{[6-[(1,1,3,3-tetramethylbutyl)imino]-1,3,5-triazi-2 , 4-diyl][(2,6,6,6-tetramethyl-4-piperidyl)imino]hexamethyllene[(2,2,6,6,-tetramethylmethyl-4-piperidyl)iminol]} etc. Are listed.

Examples of the ethanolamine compound include stearyldiethanolamine, lauryldiethanolamine, myristyldiethanolamine, pentadecyldiethanolamine, palmityldiethanolamine, margaryldiethanolamine, arachidyldiethanolamine, behenyldiethanolamine, lignoceryldiethanolamine, and the like.

Examples of the nonionic surfactant that can be used as the amino group-containing compound include polyoxyethylene alkylamine and amine oxide.

Examples of the cationic surfactant that can be used as the amino group-containing compound include aliphatic quaternary ammonium salts such as alkyl chloride (C16 to C18) trimethyl ammonium, aliphatic amine salts, and hydroxyalkyl monoethanolamine salts. Can be mentioned. In the present specification, “alkyl (C16 to C18)” means having an alkyl group having 16 to 18 carbon atoms.

The compound having an amino group is preferably a hindered amine compound. According to the above configuration, in the production of expanded particles, the possibility that the polyolefin-based resin particles will adhere to each other is further reduced.

The amount of the amino group-containing compound used depends on the type of the compound used, the type (composition) of the polyolefin resin particles used, the amount used, and the like, and is not particularly limited. The amount of the amino group-containing compound used is preferably 0.0001 parts by weight or more and 0.5000 parts by weight or less with respect to 100 parts by weight of the polyolefin resin particles. The amount of the amino group-containing compound used may be 0.1000 parts by weight or less, may be less than 0.1000 parts by weight, or may be 0.0500 parts by weight or less, based on 100 parts by weight of the polyolefin-based resin particles. May be less than 0.0500 parts by weight, may be less than 0.0200 parts by weight, may be less than 0.0200 parts by weight, and may be less than 0.0100 parts by weight. May be less than 0.0100 parts by weight, 0.0050 parts by weight or less, 0.0030 parts by weight or less, or 0.0010 parts by weight or less. Well, it may be less than 0.0010 parts by weight, 0.0008 parts by weight or less, or 0.0005 parts by weight or less. The amount of the amino group-containing compound used may be 0.0003 parts by weight or more, may be 0.0005 parts by weight or more, and may be 0.0007 parts by weight or more with respect to 100 parts by weight of the polyolefin resin particles. , May be 0.0010 parts by weight or more, may be 0.0050 parts by weight or more, may be 0.0100 parts by weight or more, and may be 0.0500 parts by weight or more. Or may be 0.1000 parts by weight or more. When the amount of the amino group-containing compound used is 0.0001 parts by weight or more with respect to 100 parts by weight of the polyolefin-based resin particles, the more the amount of the amino group-containing compound used increases in the production of the expanded beads, the polyolefin-based resin. The particles are less likely to coalesce. When the amount of the amino group-containing compound used is 0.5000 parts by weight or less with respect to 100 parts by weight of the polyolefin-based resin particles, the smaller the amount of the amino group-containing compound used is, (a) the surface of the obtained expanded particles. The amount of kaolin remaining in the powder is reduced, and as a result, the meltability of the molded product produced by using the obtained expanded particles is improved, and (b) the production cost can be suppressed, resulting in cost performance. It has the advantage of being superior.

In this production method, a dispersion aid other than the amino group-containing compound may be used. The dispersion aid other than the compound having an amino group is not particularly limited, and examples thereof include an anionic surfactant. Examples of the anionic surfactant include (a) carboxylate type, (b) alkyl sulfonate, n-paraffin sulfonate, alkylbenzene sulfonate, alkylnaphthalene sulfonate, sulfosuccinate, and other sulfonates. Type, (c) sulfated oil, alkyl sulfates, alkyl ether sulfates, alkyl amide sulfates, and other sulfate ester types, (c) alkyl phosphates, polyoxyethylene phosphates, alkyl allyl ether sulfates, etc. The phosphoric acid ester type surfactant of These dispersion aids may be used alone or in combination of two or more.

(2-4. Inorganic foaming agent)
Examples of the inorganic foaming agent include air, nitrogen, carbon dioxide, water and the like. These inorganic foaming agents may be used alone or in combination of two or more. Among these foaming agents, carbon dioxide gas is particularly preferable because the effect according to the embodiment of the present invention is great.

The amount of the foaming agent used varies depending on the type of the polyolefin resin used, the type of the foaming agent, the target expansion ratio, etc., and cannot be specified unconditionally, but it is 2 parts by weight with respect to 100 parts by weight of the polyolefin resin particles. It is preferably 60 parts by weight or more and 60 parts by weight or less.

(2-5. Dispersion medium)
The dispersion medium is preferably an aqueous dispersion medium, and it is preferable to use only water as the dispersion medium. In the present production method, a dispersion medium obtained by adding methanol, ethanol, ethylene glycol, glycerin or the like to water can be used as the dispersion medium as long as the effect according to one embodiment of the present invention is not impaired.

The amount (use amount) of the dispersion medium is preferably 100 parts by weight or more and 250 parts by weight or less with respect to 100 parts by weight of the polyolefin resin particles in the dispersion liquid. The amount of the dispersion medium used is more preferably 130 parts by weight or more based on 100 parts by weight of the polyolefin resin particles in the dispersion liquid. The amount of the dispersion medium used is more preferably 220 parts by weight or less, further preferably less than 220 parts by weight, particularly preferably 200 parts by weight or less, based on 100 parts by weight of the polyolefin resin particles in the dispersion liquid. The amount of the dispersion medium used may be less than 200 parts by weight, or 150 parts by weight or less with respect to 100 parts by weight of the polyolefin resin particles in the dispersion liquid. When the amount of the dispersion medium used is 100 parts by weight or more based on 100 parts by weight of the polyolefin resin particles in the dispersion, the dispersion amount of the polyolefin resin particles in the dispersion increases as the amount of the dispersion medium used increases. The quality is good. Therefore, during heating of the temperature in the container, it is difficult for the polyolefin resin particles in the dispersion liquid to adhere to each other, and the amount of the dispersant used and/or the amount of the dispersion aid used is not increased, and good adhesion is achieved. It becomes possible to secure dispersibility. When the amount of the dispersion medium used is 250 parts by weight or less with respect to 100 parts by weight of the polyolefin resin particles in the dispersion liquid, the smaller the amount of the dispersion medium used, the more excellent the productivity of the present production method becomes. ..

In the present production method, when the hydrophilic compound is contained in the polyolefin resin particles and the dispersion medium contains water, the water in the dispersion medium can act as a foaming agent. As a result, the expansion ratio of the resulting expanded beads can be improved.

(2-6. Method for producing expanded polyolefin resin particles)
Next, each step will be described.

In the step of preparing the dispersion liquid, polyolefin-based resin particles, a dispersion medium, a silicate, a compound having an amino group and an inorganic foaming agent in the container, and optionally other dispersants and dispersion aids are added. It can be carried out by mixing these. The order of adding the polyolefin resin particles, the dispersion medium, the silicate, the compound having an amino group and the inorganic foaming agent, and optionally other dispersants and dispersion aids and the like to the container is not particularly limited. The mode of mixing is not particularly limited, and examples thereof include a method of stirring using a stirring blade or the like provided in the container.

The step of releasing the dispersion liquid to a pressure range lower than the internal pressure of the container may be performed, for example, by increasing the internal pressure of the container to a pressure higher than the atmospheric pressure in advance and releasing the dispersion liquid under the atmospheric pressure. .. The pressure lower than the internal pressure of the container is preferably atmospheric pressure.

The temperature inside the container when the dispersion liquid is discharged into a pressure range lower than the pressure inside the container is also referred to as the foaming temperature. The pressure inside the container when the dispersion liquid is discharged into a pressure range lower than the pressure inside the container is also referred to as foaming pressure. The present manufacturing method further comprises the step of heating (increasing) the temperature in the container containing the dispersion liquid to the foaming temperature, and/or increasing the pressure in the container containing the dispersion liquid to the foaming pressure. You may have a process.

Preferred embodiments of the present production method include, for example, the following embodiments: (1) Polyolefin resin particles, a dispersion medium, a silicate, a compound having an amino group, and an inorganic material in a container equipped with a stirring blade. A foaming agent, and optionally other dispersants and dispersion aids, etc. are added to prepare a dispersion liquid. (2) The polyolefin resin in the dispersion liquid is stirred by stirring the dispersion liquid using a stirring blade. Disperse the particles in the container; (3) After or with stirring, the temperature in the container is adjusted to a foaming temperature (at least the softening point temperature of the polyolefin-based resin particles) and a foaming pressure (foaming pressure described later). (4) After that, if necessary, the inside of the container is kept at the foaming temperature and the foaming pressure for a certain period of time; (5) After that, the pressure is lower than the internal pressure of the container (for example, under atmospheric pressure). The dispersion liquid in the container is discharged and the polyolefin resin particles are foamed to obtain polyolefin resin expanded particles.

The following aspects are also preferable aspects. That is, (1) a polyolefin-based resin particle, a dispersion medium, a silicate, a compound having an amino group and an inorganic foaming agent, and optionally other dispersants and dispersion aids, etc., in a container equipped with a stirring blade. Charge, (2) After that, any one of the following (A) to (C) is performed while stirring the obtained dispersion using a stirring blade:
(A) If necessary, the inside of the container is evacuated, a foaming agent is introduced at 0.3 MPa·G or more and 2.5 MPa·G or less, and the temperature in the container is heated to a temperature not lower than the softening temperature of the polyolefin resin. .. By heating, the pressure in the container rises to about 1.0 MPa·G or more and 5.0 MPa·G or less. If necessary, near the foaming temperature, the pressure in the container is adjusted to a desired foaming pressure by adding a foaming agent, and after the temperature in the container is adjusted to a desired foaming temperature, The temperature and pressure in the container are maintained at the foaming temperature and the foaming pressure for a certain period of time, and then the dispersion liquid is discharged into a pressure range lower than the internal pressure of the container to obtain foamed polyolefin resin particles;
(B) If necessary, the inside of the container is evacuated, and the foaming agent is appropriately introduced while heating the temperature in the container to a temperature near the foaming temperature of the polyolefin resin so that the pressure in the container becomes a desired foaming pressure. After that, the temperature in the container is maintained around the foaming temperature for a certain period of time, and then the dispersion liquid is discharged to a pressure range lower than the internal pressure of the container to obtain polyolefin resin foamed particles; or (C) up to around the foaming temperature After the temperature inside the container is heated, the foaming agent is further introduced so that the pressure inside the container becomes a desired foaming pressure. After that, the temperature inside the container is maintained near the foaming temperature for a certain period of time, and then the dispersion liquid is discharged into a pressure region lower than the internal pressure of the container to obtain polyolefin resin foamed particles.

Before discharging the dispersion liquid to a region lower than the pressure inside the container, pressurizing the substance used as the foaming agent into the container to increase the internal pressure inside the container, and the pressure during foaming (at the time of discharging). The opening speed can also be adjusted (controlled). Further, the pressure used at the time of foaming (at the time of discharging) can be adjusted (controlled) by introducing the substance used as the foaming agent into the container even while the pressure is released to a region lower than the pressure inside the container. As described above, the expansion ratio can also be adjusted by adjusting the pressure at the time of foaming (at the time of discharging).

(2-7. Container)
The container is not particularly limited, but is preferably one that can withstand the foaming temperature and the foaming pressure during the production of expanded particles, and more preferably a pressure resistant container. Examples of the container include an autoclave-type pressure resistant container.

As described above, the dispersion liquid prepared in the container can be heated to the foaming temperature under agitation and pressurized to the foaming pressure, and then held at the foaming temperature and the foaming pressure for a certain period of time. The certain period of time is usually 5 to 180 minutes, preferably 10 to 60 minutes. The dispersion liquid, which has been kept at a predetermined temperature and pressure for a certain period of time, can then be released under a low pressure atmosphere (usually under atmospheric pressure) by opening a valve provided at the bottom of the container, whereby a polyolefin resin Expanded particles can be produced.

(2-8. Temperature)
The foaming temperature varies depending on the type of the polyolefin resin used and/or the additives (used) kneaded (used) and cannot be unconditionally specified. The foaming temperature is preferably Tm−30 (° C.) or higher and Tm+10 (° C.) or lower, where [Tm (° C.)] is the melting point of the polyolefin resin particles.

The melting point of the polyolefin resin particles mentioned here is a value measured by using a differential scanning calorimeter. The specific operation procedure is as follows: (1) After heating 4 to 6 mg of the polyolefin resin from 40° C. to 220° C. at a heating rate of 10° C./min to melt; (2) 10 After the temperature is decreased from 220° C. to 40° C. at a temperature decreasing rate of° C./min for crystallization; (3) Further, the temperature is increased from 40° C. to 220° C. at a temperature increasing rate of 10° C./min. The temperature of the peak (melting peak) of the DSC curve obtained during the second temperature rise (that is, when (3)) can be determined as the melting point of the polyolefin resin particles.

(2-9. Pressure)
The foaming pressure varies depending on the desired expansion ratio of the polyolefin resin pre-expanded particles and cannot be specified unconditionally. The foaming pressure is, for example, preferably 0.50 MPa·G or more and 6.0 MPa·G or less, and more preferably 1.0 MPa·G or more and 4.5 MPa·G or less. When the foaming pressure is (a) 0.50 MPa·G or more, there is no fear that the expansion ratio will be extremely low, and (b) when it is 6.0 MPa·G or less, the average bubbles of the obtained foamed particles. There is no fear that the diameter will become finer and there is no fear that the moldability will deteriorate.

When a dispersion containing polyolefin-based resin particles is discharged from the container to a pressure range lower than the internal pressure of the container, dispersion is performed for the purpose of adjusting the discharge amount (flow rate), reducing the magnification variation of the obtained expanded particles, etc. The liquid can also be discharged through an open orifice of 2-10 mmφ. The "pressure range lower than the container internal pressure" is also referred to as a low pressure atmosphere. In this production method, the temperature of the low-pressure atmosphere may be adjusted when the dispersion liquid in the container is discharged into the low-pressure atmosphere for the purpose of increasing the expansion ratio.

(2-10. Expanded polyolefin resin particles)
(Amount of deposited silicate)
In the polyolefin resin expanded particles obtained by the above-described manufacturing method, the amount of silicate adhering to the surface of the expanded particles is determined by the fusion of the expanded particles in the in-mold expanded molded article using the expanded particles. The smaller the number, the better the adhesion. In the polyolefin resin expanded particles obtained by the above-described manufacturing method, the amount of silicate adhering to the surface of the expanded particles is preferably less than 1800 ppm, more preferably 1500 ppm or less, based on the weight of the expanded particles, It is more preferably 1300 ppm or less, even more preferably 1000 ppm or less, particularly preferably 800 ppm or less.

[3. Polyolefin resin foamed particles, polyolefin resin in-mold foam molding
This manufacturing method, that is, [2. The method for producing expanded polyolefin resin particles] is also within the scope of the present invention.

This manufacturing method, that is, [2. Method for producing expanded polyolefin resin particles] by in-mold foam molding of the expanded polyolefin resin particles produced by the method for producing expanded polyolefin resin particles described in the section, a polyolefin resin in-mold foam molded article. Obtainable. The polyolefin resin in-mold foam molded product thus obtained is also within the scope of the present invention.

Examples of the method for producing a polyolefin resin in-mold foam molded article (in-mold foam molding method) include:
(A) Foamed polyolefin resin particles are pressure-treated with an inorganic gas such as air, nitrogen, carbon dioxide, etc. to impregnate the foamed polyolefin resin particles with an inorganic gas to give a predetermined internal pressure, and then filled in a mold. Then, a method of heating and fusing with steam,
(B) A method of compressing polyolefin resin expanded particles with a gas pressure to fill a mold, and heating and fusing with steam by utilizing the recovery force of the polyolefin resin expanded particles,
(C) A method such as a method of filling the foamed polyolefin resin particles in a mold without pretreatment and heating and fusing with steam may be used.

The density of the polyolefin resin in-mold foamed article of the present invention is not particularly limited, but it is preferably 15 g/L or more and 350 g/L or less, and more preferably 20 g/L or more and 300 g/L or less.

In addition, in order to adjust the bulk density of the polyolefin resin expanded particles, a two-stage foaming step may be performed between the production of the polyolefin resin expanded particles and the in-mold foam molding using the polyolefin resin expanded particles. .. In that case, the foamed polyolefin resin particles are pressurized with an inorganic gas such as air before the second-stage foaming to impregnate the foamed particles with the gas, and then heated by steam to obtain a desired bulk density. ..

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

The substances used in the examples and comparative examples are as follows.
<Polyolefin resin>
-Ethylene/1-butene/propylene random copolymer [MFR=7.5 g/10 minutes, melting point 142° C.]
<Resin additive>
-Hindered amine compound: ADEKA Corporation, ADEKA STAB LA-77G
・Talc: Hayashikasei Co., Ltd., talcan powder PK-S
・Glycerin: <Silicate> manufactured by Lion Corporation
・Kaolin: ASP-170 manufactured by BASF
<Amino group-containing compound>
-Hindered amine compound: ADEKA Corporation, ADEKA STAB LA-77G
Stearyldiethanolamine: manufactured by Kao Corporation, Electrostripper TS-15B
・Polyoxyethylene alkylamine: Amate 102, manufactured by Kao Corporation
Alkyl chloride (C16-C18) trimethylammonium: Lion Specialty Chemicals Co., Ltd., Lipocard T-28
<Other dispersion aids>
・Sodium dodecylbenzene sulfonate: Kao Corporation, Neoperex G-15
The evaluation in Examples and Comparative Examples was performed by the following methods.

<Melting point _{t m} measured polyolefin resin>
Measurement of melting point _{t m} of the polyolefin-based resin, a differential scanning calorimeter DSC [METTLER TOLEDO N. V. Manufactured by DSC822e]. Specifically, (1) after heating 5 to 6 mg of the sample to be measured by heating from 40°C to 220°C at a heating rate of 10°C/min to melt; (2) 10 After the temperature is decreased from 220° C. to 40° C. at a temperature decreasing rate of° C./min for crystallization; (3) The temperature is further increased from 40° C. to 220° C. at a temperature increasing rate of 10° C./min. During the second heating temperature (i.e. (3) when the) peak (melting peak) of the DSC curves obtained was the melting point t _m of the polyolefin resin.

<Evaluation of dispersion stability>
From the obtained polyolefin resin foamed particles, 5 L was sampled and evaluated based on the following criteria. ⊚ indicates that the dispersion stability is very good, ∘ indicates that the dispersion stability is good, Δ indicates that the dispersion stability is satisfactory (not defective), and x indicates the dispersion stability. It shows that the stability is poor.
⊚: There are no foam particles that are adhered (cohered) to each other ○: There are less than 5 foam particles that adhere to each other Δ: There are 5 or more foam particles that adhere to each other × : Foaming did not occur due to poor dispersion.

<Measurement of amount of silicate adhering to the surface of polyolefin resin expanded particles (adhered silicate amount)>
First, the resin particle ash content A1 was measured by the following method: (1) The obtained polyolefin-based resin particles were dried in an 80° C. dryer for 24 hours or more; (2) Next, the polyolefin-based resin after drying was dried. The resin particles were heated at 150° C. for 1 hour to completely remove water; (3) Then, the water-free polyolefin resin particles were cooled at 23° C. for 1 hour in a desiccator; (4) Next The cooled polyolefin resin particles were placed in a crucible and burned at 750° C. for 1 hour or more, and then the polyolefin resin particles were cooled at 23° C. for 1 hour in a desiccator; (5) The following formula The value obtained by 1 was taken as the resin particle ash content A1 (unit: ppm).
W1: crucible weight W2: crucible before combustion+resin particle weight W3: crucible after combustion+resin particle weight A1=(W3-W1)*1000000/(W2-W1)...Equation 1.

Next, the resin particle ash content A2 was measured by the following method: (1) The obtained polyolefin-based resin expanded particles were dried in an 80° C. dryer for 24 hours or more; (2) Next, after drying. The polyolefin-based resin expanded particles were heated at 150° C. for 1 hour to completely remove the water content. (3) After that, the water-free polyolefin-based resin expanded particles were cooled at 23° C. in a desiccator for 1 hour; (4) Next, the cooled polyolefin resin expanded particles were put into a crucible and burned at 750° C. for 1 hour or more, and then the polyolefin resin expanded particles were cooled at 23° C. in a desiccator for 1 hour; (5) The ash content A2 (unit: ppm) of the resin particles was determined by the following formula 1.
W4: crucible weight W5: crucible before combustion+pre-expanded particle weight W6: crucible after combustion+pre-expanded particle weight A2=(W6-W4)*1000000/(W5-W4)...Equation 2.

Based on the following formula, the difference between A2 and A1 was defined as the amount of adhered silicate (unit: ppm).
Amount of adhered silicate (ppm)=A2-A1.

When the amount of the deposited silicate obtained was less than 1800 ppm, it was evaluated as ◯ (good) and when it was 1800 ppm or more, as × (poor).

Hereinafter, examples and comparative examples of the present invention will be described.

(Examples 1-8, Comparative Examples 1-9)
[Preparation of polyolefin resin particles]
An ethylene/1-butene/propylene random copolymer, which is a polyolefin resin, was hand blended with the additives shown in Table 1 and melt-kneaded at a resin temperature of 220° C. using a twin-screw extruder. Then, the melt-kneaded product was extruded into a strand form from an extruder, and the obtained strand was water-cooled and cut to obtain polyolefin resin particles A, B or C having an average weight of 1.0 mg.

[Production of expanded polyolefin resin particles]
In an autoclave of 0.01 m ³ , 100 parts by weight of polyolefin resin particles A, B or C, and water, a silicate, an amino group-containing compound and other dispersion aids were added in the amounts shown in Tables 2 and 3. Was charged and sealed. Then, 4.0 parts by weight of carbon dioxide gas was charged, and the inside of the container was heated while stirring the charged raw materials. After the temperature inside the container reached the foaming temperature −1.0° C. shown in Tables 2 and 3, carbon dioxide gas was added so that the pressure inside the container became the foaming pressure shown in Tables 2 and 3. Then, the temperature in the container was raised over 20 minutes until the temperature in the container reached the foaming temperature shown in Tables 2 and 3. Next, one end of the autoclave was opened, and the dispersion liquid in the container was passed through a φ3.6 mm orifice plate and discharged into a non-closed (under atmospheric pressure) cylindrical container to obtain foamed polyolefin resin particles. Foaming temperature, by the method described above to determine the melting point t _m of the polyolefin resin, and appropriately set based on the results obtained. In addition, the dispersion stability was evaluated by the method described above, and the results are shown in Tables 2 and 3.

With respect to the obtained polyolefin resin foamed particles, the amount of deposited silicate was measured by the method described above, and the results are shown in Tables 2 and 3.

It can be seen that Examples 1 to 8 have excellent dispersion stability. Further, it can be seen that the polyolefin resin expanded particles having a small amount of deposited silicate were obtained.

In Comparative Example 1, the amount of the amino group-containing compound used is larger than the range of the present invention. In Comparative Example 1, it can be seen that the amount of silicate adhering to the surface of the obtained polyolefin resin expanded particles is large. The expanded polyolefin resin particles obtained in Comparative Example 1 are not suitable for use as a material for in-mold foam molding.

In Comparative Example 2, the amount of the amino group-containing compound used is less than the range of the present invention. In Comparative Example 2, it can be seen that the dispersion stability is poor.

In Comparative Examples 3 to 5, no amino group-containing compound is used. As a result, in Comparative Examples 3 to 5, it can be seen that the dispersion stability is not good or is poor.

In Comparative Examples 6 to 9, at the time of producing the polyolefin resin particles, the amino group-containing compound was melt-kneaded together with the polyolefin resin to produce polyolefin resin particles. Then, in Comparative Examples 6 to 9, no amino group-containing compound other than the amino group-containing compound already contained in the polyolefin-based resin particles was used during the production of the polyolefin-based resin expanded particles. As a result, it can be seen that in Comparative Examples 6 to 9, the dispersion stability is not good or is poor.

According to one embodiment of the present invention, it is possible to provide a method for producing expanded polyolefin resin particles, which is excellent in productivity and production cost. Therefore, one embodiment of the present invention is a polyolefin resin used as a material for a polyolefin resin in-mold foam molded article that can be used in various applications such as automobile interior members, cushioning packaging materials, returnable boxes, heat insulating materials, and building members. It can be suitably used for the production of expanded beads.

Claims (3)

In the container, a polyolefin-based resin particle, a dispersion medium, a silicate, a step of mixing a compound having an amino group and an inorganic foaming agent to prepare a dispersion liquid,
Discharging the dispersion liquid to a pressure range lower than the container internal pressure,
The amount of the compound having an amino group is 0.0001 parts by weight or more and 0.5000 parts by weight or less with respect to 100 parts by weight of the polyolefin resin particles in the dispersion, and a method for producing expanded polyolefin resin particles. .. The method for producing expanded polyolefin resin particles according to claim 1, wherein the compound having an amino group is a hindered amine compound. The amount of the dispersion medium is 100 parts by weight or more and 250 parts by weight or less with respect to 100 parts by weight of the polyolefin-based resin particles in the dispersion liquid. Method.