JP6084406B2 - Foaming agent composition pellets and method for producing the same - Google Patents

Description

  The present invention relates to a foaming agent composition pellet used for obtaining a molded body obtained by foaming a thermoplastic resin.

Thermoplastic resins are lighter than metals and have excellent properties such as moldability and have been widely used for automobile parts, electronic / electrical parts and the like. As a means for further reducing the weight by utilizing these characteristics, a foam molding technique is known in which a foaming agent is mixed with a thermoplastic resin and molded. In such foam molding, a pyrolytic chemical foaming agent or a thermally expandable microcapsule is used as a foaming agent. However, these are usually powders, which are easily separated when mixed with thermoplastic resin pellets and stable in molding. It tends to cause foaming spots due to lack of sex.
Under such circumstances, attempts have been made to melt and mix a resin (carrier resin) that can be processed in advance at a temperature lower than the decomposition temperature or expansion temperature of the foaming agent and the foaming agent into a master batch.
Such master batches have been widely used because they can be uniformly mixed with thermoplastic resin pellets and can be easily foam-molded.
Patent Document 1 describes a master batch in which polyethylene wax and a foaming agent are kneaded with a polyethylene resin. Patent Document 2 describes a masterbatch composed of an ethylene / α-olefin copolymer having specific properties and a foaming agent. Patent Document 3 describes a method for producing a master batch in which dispersion is performed in the presence of an antistatic agent in order to suppress aggregation of the foaming agent.
By such a method, in the master batches of Patent Documents 1 and 2, a resin (carrier resin) that can be processed in advance at a temperature lower than the decomposition temperature or expansion temperature of the foaming agent is used. A foamed molded article having an excellent balance of mechanical properties could be obtained. In patent document 3, the dispersibility of the foaming agent was improved and the foamability could be improved.
However, even with the methods of Patent Documents 1 to 3, it was difficult to sufficiently improve the mechanical characteristics, particularly the impact resistance. In particular, according to the method using these master batches, since the resin used as the molded body and the carrier resin used in the master batch are different, there is a problem that the compatibility is insufficient and the impact resistance is lowered.

JP 2009-144122 A Japanese Patent Laid-Open No. 2-113035 JP 2006-274212 A

As a result of studies by the present inventor, the method of foaming by directly mixing the foaming agent with the molding resin, that is, the conventional foam molding, without depending on the masterbatch, has the following problems. It was found.
Normally, in injection molding, the mixed resin is weighed in the cylinder as the screw rotates after the mixed resin is charged into the injection molding machine. The mixed resin is transferred from the screw supply unit to the compression unit and mixed by heating the cylinder. The resin melts. At this time, it is ideal that melting of the mixed resin in the compression part and decomposition of the foaming agent contained in the mixed resin occur, and foaming of the molten resin occurs by injecting the molten resin into the mold from the nozzle. is there. However, if the foaming agent is mixed directly into the molding resin, the foaming agent will decompose in the vicinity of the supply section or the hopper port before the screw compression section after the mixed resin is charged into the injection molding machine. It was difficult to exert the effect of the foaming agent. Therefore, when performing foam molding, it is less susceptible to thermal influence so that the foaming agent does not decompose at the hopper port and supply section of the injection molding machine, and it is easy to mix with the molding resin and impair foamability. There is no need to devise anything.
An object of the present invention is to provide a foaming agent composition pellet that solves the above-mentioned conventional problems, improves mechanical properties, particularly impact resistance, and can produce a stable foamed molded article.

The inventors of the present invention have arrived at the present invention as a result of intensive studies to solve the above problems.
That is, the gist of the present invention is as follows.
(1) A molding resin pellet formed by mixing a foaming agent composition pellet and a thermoplastic resin pellet,
The foaming agent composition pellets contain calcium carbonate particles (A) 30 to 80% by mass, foaming agent (B) 3 to 30% by mass and binder component (C) 10 to 50% by mass, (A) to (C ) Is 100% by mass , and only one or more compounds selected from the group consisting of paraffin wax, polyolefin wax, higher fatty acid ester, higher fatty acid metal salt and higher fatty acid bisamide are used as the binder component (C). A resin pellet for molding characterized by the above.
(2) The resin pellet for molding according to (1), wherein the foam specific gravity of the foaming agent composition pellet is 0.5 to 1.0 as measured by JIS K7365.
(3) The resin pellet for molding as described in (1) or (2) , wherein the thermoplastic resin pellet is polyamide.
(4) a blowing agent composition pellets further containing polyamide powder particle body (D) (1) ~ (3) molding resin pellets according to any one of.
(5) Calcium carbonate particles (A), foaming agent (B), binder component (C) and polyamide powder (D) are mixed together and pelletized while heating at a temperature above the melting point of binder component (C). The method for producing resin pellets for molding according to any one of (1) to (4), wherein the foaming agent composition pellets obtained by compression molding into a shape and polyamide resin pellets are mixed.
(6) A molded product obtained by molding the molding resin pellet according to any one of (1) to (4) .

  ADVANTAGE OF THE INVENTION According to this invention, the foaming agent composition pellet which can improve a mechanical characteristic, especially impact resistance, and can produce the stable foaming molding is obtained. Since the foaming agent composition pellet does not use a carrier resin, it can cope with foam molding of any thermoplastic resin without selecting the type of molding resin.

Hereinafter, the present invention will be described in detail.
Examples of the calcium carbonate particles (A) used in the present invention include heavy calcium carbonate, light calcium carbonate, and colloidal calcium carbonate. Heavy calcium carbonate is obtained, for example, by pulverizing natural crystalline limestone or marble. Light calcium carbonate is produced wet by a chemical reaction using a raw material such as limestone. Among them, colloidal calcium carbonate is obtained by controlling colloidal ultrafine particles by controlling production conditions. Since light calcium carbonate has a spindle shape or a rod shape and has a large shape anisotropy and tends to hardly contribute to an improvement in impact resistance, it is preferable to use heavy calcium carbonate or colloidal calcium carbonate in the present invention. In particular, it is preferable to use heavy calcium carbonate. Calcium carbonate is classified as a so-called amorphous filler, and is different in form from a fibrous, needle-like or plate-like filler.

  The average particle diameter of the calcium carbonate particles (A) is preferably from 0.1 to 20 μm, more preferably from 0.5 to 10 μm, and even more preferably from 1 to 5 μm. If the average particle size is less than 0.1 μm, the calcium carbonate particles (A) are likely to aggregate and difficult to uniformly disperse in the molded product, and there is a high tendency to form undesirable aggregates from the viewpoint of improving impact resistance. Become. On the other hand, when the average particle diameter is larger than 20 μm, the impact resistance improving effect due to the particle form is poor, which is not preferable. The particle size distribution of the calcium carbonate particles (A) is not particularly limited, and may be a single peak or a mixture having a plurality of peaks when displayed by a number frequency distribution curve. The average particle diameter is an average value obtained by measuring the particle diameter of 30 randomly extracted primary calcium carbonate particles using a scanning electron microscope (SEM).

  In the present invention, the calcium carbonate particles (A) may be surface-treated with a reactive compound such as a fatty acid, a silane coupling agent, a titanate coupling agent, or an organosiloxane as necessary. In particular, a silane coupling agent can be suitably used. For example, vinyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-mercaptopropyl Examples include trimethoxysilane.

  The blending ratio of the calcium carbonate particles (A) in the foaming agent composition pellets needs to be 30 to 80% by mass, preferably 35 to 75% by mass, and more preferably 40 to 60% by mass. . When the blending ratio is less than 30% by mass, the blocking resistance of the resulting foaming agent composition pellets decreases. Moreover, since foaming performance falls, a moldability becomes unstable and it becomes difficult to raise a foaming ratio. In the case of core back type foam molding, it is difficult to foam while forming a sufficient skin layer, and the impact strength of the foam molded article that can be obtained is lowered. On the other hand, if the blending ratio exceeds 80% by mass, it is difficult to process the foaming agent composition pellets themselves, and even if they can be processed, the foaming agent composition pellets are fragile and have a high bulk specific gravity, so they segregate in the molding resin. It is easy to lack molding stability.

  As the foaming agent (B) in the present invention, an inorganic foaming agent or an organic foaming agent known per se can be used. Specific examples of blowing agents include sodium bicarbonate, ammonium bicarbonate, sodium carbonate, ammonium carbonate, azodicarbonamide, N, N′-dinitrosopentamethylenetetramine, dinitrosotephthalamide, azobisisobutyronitrile, azodicarbon Examples thereof include barium acid, 4,4′-oxybisbenzenesulfonyl hydrazide, toluenesulfonyl hydrazide, and mixtures thereof. Of these, azodicarbonamide, 4,4'-oxybisbenzenesulfonyl hydrazide, and sodium bicarbonate are more preferable.

  The average particle diameter of the foaming agent (B) is not particularly limited, but the average particle diameter is preferably 1 to 40 μm, and more preferably 2 to 30 μm. The present invention is particularly effective when the particle size distribution of the blowing agent substantially includes fine particles having a particle size of 4 μm or less, and the present invention is more effective when the particles substantially include fine particles having a particle size of 2 μm or less. .

The blending ratio of the foaming agent (B) in the foaming agent composition pellet needs to be 3 to 30% by mass, preferably 5 to 25% by mass, and more preferably 10 to 20% by mass. . When the blending ratio is less than 3% by mass, the amount of the foaming agent composition pellets to be added is increased when the foam is molded, so that the impact strength of the resulting foam molded article may be lowered. On the other hand, if it exceeds 30% by mass, in order to obtain a predetermined foaming performance, it is necessary to use a reduced amount of foaming agent composition pellets,
Thereby, molding stability may be inferior.

  Examples of the binder component (C) used in the present invention include water, ethanol, ethylene glycol, glycerin, liquid paraffin, paraffin wax, polyolefin wax, polyalkylene glycol terminal modified product, phosphate ester or phosphite ester, higher fatty acid. Examples thereof include one or more compounds selected from the group consisting of esters, higher fatty acid metal salts, higher fatty acid bisamides, and higher aliphatic amines. In particular, paraffin wax, polyolefin wax, higher fatty acid ester, higher fatty acid metal salt, and higher fatty acid bisamide can be suitably used.

  Liquid paraffin is an oligomer and a polymer that are liquid at room temperature and contain paraffinic hydrocarbons. It is a mixture of paraffin hydrocarbons and alkyl naphthene hydrocarbons. Sometimes called mineral oil.

  Paraffin wax is a wax having 20 to 48 carbon atoms which is solid at normal temperature mainly composed of a linear saturated hydrocarbon, contains n-paraffin as a main component, and contains a small amount of i-paraffin and naphthene. It is. These can use what is generally marketed.

  The polyolefin wax is made of an α-olefin copolymer having 2 to 20 carbon atoms, is a solid at normal temperature, and becomes a low-viscosity liquid at 80 to 120 ° C. For example, a polyethylene wax, a polypropylene wax, etc. are mentioned. Usually, the polyolefin wax is often composed mainly of ethylene. The polyolefin wax may be a copolymer of polyethylene, ethylene and other olefins such as propylene, butylene, 4-methylpentene-1, and the like, and vinyl esters such as vinyl acetate and vinyl propionate. It may be partially modified by copolymerization. Styrene may be grafted. When the wax is an ethylene copolymer, the proportion of the monomer copolymerized with ethylene is, for example, about 1 to 40% by weight, preferably about 5 to 30% by weight. Among the polyolefin waxes, polyethylene wax is particularly preferable.

The terminally modified product of polyalkylene glycol is represented by the following general formula (i) or general formula (ii).
X—R— (O—CH ₂ —CH ₂ ) _m —O—R—X (i)
X—R— [O—CH ₂ —CH (CH ₃ )] _n —O—R—X (ii)
In general formula (i) or general formula (ii), X represents NH ₂ , COOH or a hydrogen atom, R represents a linear or branched alkylene group having 1 to 100 carbon atoms, and m represents 4 to 1200. N represents an integer of 1 to 200.
Examples of the terminal modified product of polyalkylene glycol include a terminal modified product of polyethylene glycol and a terminal modified product of polypropylene glycol, and the terminal is preferably modified with an amino group, a carboxyl group or a methyl group.

The phosphate ester is represented by the following general formula (iii).
(RO) _n PO (OH) _3-n (iii)
In general formula (iii), R represents an alkyl group having 1 to 25 carbon atoms, and n represents 1 or 2. However, two or less RO groups may be the same or different. R is preferably an ethyl group, a butyl group, an octyl group, or an ethylhexyl group.

The phosphite is represented by the following general formula (iv).
(RO) ₃ P (iv)
In general formula (iv), R represents an alkyl group having 1 to 25 carbon atoms, a phenyl group, an aromatic group in which a part of the phenyl group is substituted with a hydrocarbon group, or a hydrogen atom. However, the three RO groups may be the same or different, and three Rs are not hydrogen atoms. R is an aliphatic group such as a decyl group, a lauryl group, a tridecyl group, a stearyl group or an oleyl group, an aromatic group such as a phenyl group or a biphenyl group, an ethyl group, a propyl group, a t-butyl group, or a nonyl group. Aromatic groups having the above substituents are preferred.

  Examples of the phosphoric acid or phosphorous acid ester include aliphatic phosphoric acid or phosphorous acid ester such as di (2-ethylhexyl) phosphate, tridecyl phosphite, tris (tridecyl) phosphite, tristearyl phosphite, Aromatic phosphites such as triphenyl phosphite and diphenyl monodecyl phosphite can be mentioned.

The higher fatty acid ester is represented by the following general formula (v).
R ₁ —COO—R ₂ (v)
In General Formula (v), R ₁ and R ₂ represent an alkyl group having 8 to 40 carbon atoms. R ₁ and R ₂ are preferably an aliphatic group such as a decyl group, a lauryl group, a tridecyl group, a stearyl group, or an oleyl group, and more preferably an ester compound of a higher fatty acid and a higher aliphatic monohydric alcohol.
Examples of the higher fatty acid include myristic acid, palmitic acid, behenic acid, oleic acid, and aragicic acid. Examples of the higher aliphatic monohydric alcohol include myristyl alcohol, behenyl alcohol, oleyl alcohol, stearyl alcohol, Examples include hexyl decyl alcohol. Examples of the higher fatty acid ester include myristyl myristate, stearyl stearate, behenyl behenate, oleyl oleate, hexyldecyl myristate, and the like.

The higher fatty acid and its metal salt are those represented by the following general formula (vi).
CH ₃ (CH ₂ ) _n COOX (vi)
In general formula (vi), X represents a metal atom of Groups I to III of the periodic table, and n represents an integer of 9 to 30.
Examples of the higher fatty acid and the metal salt thereof include higher fatty acids such as stearic acid, palmitic acid, oleic acid, aragydic acid, behenic acid, and montanic acid, and higher fatty acid metals such as magnesium stearate, calcium stearate, and aluminum palmitate. Mention may be made of salts.

The fatty acid bisamide is represented by the following general formula (vii).
R ₁ —CONH— (CH ₂ ) _n —NHCO—R ₂ (vii)
In general formula (vii), R ₁ and R ₂ represent a fatty acid group having 19 to 23 carbon atoms.
Examples of the fatty acid bisamides include methylene bisstearylamide, ethylene bisstearylamide, ethylene bispalmitylamide, and the like.

The higher aliphatic amine is represented by the following general formula (viii).
R ₁ —NR ₂ R ₃ (viii)
In General Formula (viii), R ₁ represents an alkyl group having 8 to 40 carbon atoms, and R ₂ and R ₃ represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. R ₁ is preferably an aliphatic group such as an octyl group, a decyl group, a lauryl group, a tridecyl group, a stearyl group, or an oleyl group.
Examples of the higher aliphatic amine include octylamine, nonylamine, undecylamine, dodecylamine, tridecylamine, 1-tetradecylamine, pentadecylamine, stearylamine, and oleylamine.

  The blending ratio of the binder component (C) in the foaming agent composition pellet needs to be 10 to 50% by mass, preferably 12 to 45% by mass, and more preferably 15 to 40% by mass. . When the blending ratio is less than 10% by mass, the foaming agent composition pellets are likely to be insufficiently hard, so that they are fragile when mixed with a molding resin, and the bulk specific gravity of the foaming agent composition pellets is reduced and molding stability is reduced. May be inferior. On the other hand, if it exceeds 50% by mass, the appearance of the foamed molded product is inferior due to generation of unnecessary gas, and the impact resistance may be inferior.

  The bulk specific gravity measured by JIS K7365 of the foaming agent composition pellets of the present invention is preferably 0.5 to 1.0, more preferably 0.55 to 0.9, and 0.6 to 0. More preferably, it is .8. When the bulk specific gravity is less than 0.5 or exceeds 1.0, the bulk specific gravity difference between the bulk and the resin pellet mixed therewith increases, and the foaming agent composition pellets are segregated, resulting in poor molding stability.

  It is a well-known granulation method as a method of manufacturing the foaming agent composition pellet of this invention, Comprising: It does not specifically limit. Examples thereof include a method in which various raw materials are kneaded with a batch-type kneader and then granulated with a granulator, and a method in which the raw material is produced into a pellet shape with an extruder and a pelletizer. Specifically, various raw materials can be previously heated and mixed and kneaded at 50 to 150 ° C. using a Banbury mixer or the like, and then manufactured into a pellet shape with a compression granulator. In the case of compression granulation, it is possible to process at a set temperature below the melting point of the binder component, but if it is above the melting point, the processing is stable and a foam batch master batch that is difficult to collapse is obtained. Also in molding, the molding stability is increased, which is preferable. The production equipment for these blowing agent composition pellets includes a high-speed mixer (Fukae Powtech), a Henschel mixer (Mitsui Miike), a CF granulator (Freund Sangyo), and a vertical granulator (Powrec). In addition, a flow jet granulator (manufactured by Okawara Seisakusho), a universal stirrer (manufactured by Dalton), a nauta mixer (manufactured by Hosokawa Micron), and the like can be used.

  Since the carrier resin is not added to the foaming agent composition pellet of the present invention, it is possible to obtain a foamed molded product by blending it into various thermoplastic resins without impairing the properties of the resin. Applicable thermoplastic resins are polycaproamide (nylon 6), polytetramethylene adipamide (nylon 46), polyhexamethylene adipamide (nylon 66), polyhexamethylene sebacamide (nylon 610), poly Hexamethylene dodecanamide (nylon 612), polyundecane adipamide (nylon 116), polyundecanamide (nylon 11), polydodecanamide (nylon 12), polytrimethylhexamethylene terephthalamide (nylon TMHT), polyhexa Methylene isophthalamide (nylon 6I), polyhexamethylene terephthalate / isophthalamide (nylon 6T / 6I), polybis (1-aminocyclohexyl) methane dodecamide (nylon PACM12), polybis (3-methyl-4-amino) (Cyclohexyl) methane dodecamide (nylon dimethyl PACM12), polymetaxylylene adipamide (nylon MXD6), polydecamethylene terephthalamide (nylon 10T), polypolyundecamethylene terephthalamide (nylon 11T), polyundecamethylene hexahydroterephthale Polyamide resin such as amide (nylon 11T (H)), polyacetal resin, polypropylene, polyethylene, olefin resin such as ethylene / α-olefin copolymer, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polylactic acid, polybutylene Polyester resins such as succinate, polyphenylene sulfide resin, polyether ether ketone resin, liquid crystal polymer resin, polystyrene, styrene / Acrylonitrile copolymer, acrylonitrile / butadiene / styrene copolymer (ABS resin), methyl methacrylate (meth) acrylate / styrene copolymer, syndiotactic polystyrene and other styrene resins, polymethyl methacrylate, polymethyl acrylate And acrylic resins such as polybutyl acrylate, polycarbonate resins, polyphenylene ether resins, polyarylate resins, polysulfone resins, polyether sulfone resins, and the like.

Conventional foaming agent composition pellets are low melting point resins such as polyethylene, ABS resin, polystyrene, etc., which are melt kneaded with foaming agents, and are not suitable for engineering plastics and other resins that require high melting point and high temperature processing. Therefore, the foaming agent composition pellets of the present invention are effective for use in high-temperature processing resins such as these engineering plastics.
In particular, application to polyamide, polybutylene terephthalate, and polyphenylene sulfide, which have high industrial utility value for the automotive field and electrical equipment, is preferable because of strength and heat resistance when formed into a foamed molded article.

  The foaming agent composition pellet of the present invention is preferable because the dispersibility of the foaming agent can be improved by blending the resin powder (D). The improvement of the dispersibility of the foaming agent has the effect of improving the foaming characteristics and improving the impact resistance of the resulting foamed molded article. Although the average particle diameter of the resin powder (D) is not particularly limited, it is preferably 1 to 500 μm and more preferably 1 to 200 μm for the production stability of the foaming agent master. .

  The resin powder (D) is preferably the same type of resin as the thermoplastic resin in order to improve compatibility with the thermoplastic resin mixed during foam molding and to improve molding stability. For example, as the polyamide resin, the thermoplastic resin is nylon 10T and the resin powder (D) is nylon 6, and as the polyolefin resin, the thermoplastic resin is polypropylene and the resin powder (D) is polyethylene. For example, as the polyester resin, the thermoplastic resin is polybutylene terephthalate and the resin powder (D) is polyethylene terephthalate. The thermoplastic resin is polylactic acid and the resin powder (D) is polybutylene succinate. An example is given. In addition, an example in which the thermoplastic resin is a polyarylate resin and the resin particle (D) is a polycarbonate resin is also exemplified. The same thermoplastic resin and resin powder (D) are most preferable from the viewpoints of compatibility and molding stability.

  When a polyamide resin or a polyamide powder is used as the thermoplastic resin, the foamability can be further improved by setting the relative viscosity of the polyamide resin in a specific range. The relative viscosity of the polyamide resin is preferably 1.5 to 5.0, and more preferably 2.0 to 4.0. If the relative viscosity is less than 1.5, it is difficult to form uniform foam cells, foamability is lowered, and mechanical properties are also lowered, which is not preferable. If the relative viscosity exceeds 5.0, the flowability of the foaming agent composition is lowered, which is not preferable because the moldability is lowered. The relative viscosity of the polyamide resin is a value obtained by using 96% sulfuric acid as a solvent under conditions of a temperature of 25 ° C. and a concentration of 1 g / 100 ml, and is an index of molecular weight.

  Also in resins other than polyamide resin, the same kind of resins can be used in combination, and the molecular weight can be selected. In particular, polyamide, polybutylene terephthalate, and polyphenylene sulfide are preferably used from the viewpoint that the foaming characteristics of the resulting resin and the effect of improving the impact resistance of the foamed molded article are remarkable when foam molding is performed. it can.

  Examples of the method for obtaining the resin powder (D) include a method of freeze-pulverizing various resin pellets and a method of mechanically pulverizing using a rotor-type pulverizer. These can be performed using a single method, but can also be performed by combining various methods. Usually, a resin having a high glass transition point is easy to freeze and pulverize, but a resin having a low glass transition point is difficult to freeze and pulverize, and therefore it is preferable to perform mechanical pulverization rather than freeze pulverization. .

  The thermoplastic resin used in the present invention has glass fiber, carbon fiber, talc, mica, wollastonite, silica, barium sulfate, layered silicate and other reinforcing materials as long as its properties are not significantly impaired, thermal stability Agents, antioxidants, pigments, anti-coloring agents, weathering agents, flame retardants, plasticizers, crystal nucleating agents, thickeners, crosslinking agents, release stabilizers, and the like may be added.

The mixed resin pellet obtained by mixing the foaming agent composition pellet of the present invention and the thermoplastic resin pellet made of the thermoplastic resin can be molded into a foamed molded body by a conventional method.
Furthermore, as a foamed molded article having excellent strength, surface smoothness, and appearance, it is preferable to form a foamed body in which the core part where foamed cells are present is covered with a skin part where foamed cells are not present. Such a foam has a holding pressure of 20 to 100 MPa for 0.2 to 1.0 s, for example, when a molten polyamide resin composition is injected into a mold cavity and the molten resin reaches the vicinity of the flow end. Then, the mold core portion adjacent to the mold cavity can be obtained by an injection core back type injection molding method in which the thickness of the middle mold cavity is retracted at a speed of 10 to 100 mm / s.

  Even when the foaming agent composition pellet of the present invention is used in various resins, it can be made into a foamed molded article excellent in foaming moldability and impact resistance. It is suitably used in the field. In particular, since the effect can be particularly enhanced for polyamide, it can be suitably used as a component having excellent heat resistance, mechanical properties, and light weight as a component around an automobile engine.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples.
The raw materials used in Examples and Comparative Examples are shown.

1. material

1) Calcium carbonate particles a1: Heavy calcium carbonate (“Shiroton P-10” manufactured by Shiroishi Kogyo Co., Ltd.), average particle size 2 μm
a2: Heavy calcium carbonate ("Whiteon P-30" manufactured by Shiroishi Kogyo Co., Ltd.), average particle size 6 μm
a3: Colloidal calcium carbonate (“Shiraka Hana O” manufactured by Shiroishi Kogyo Co., Ltd.), average particle size 30 nm
a4: Light calcium carbonate (“PC-700” manufactured by Shiroishi Kogyo Co., Ltd.), average particle size 1.2 μm

2) Talc a4: “Microace K-1” manufactured by Nippon Talc Co., Ltd., average particle size: 7 μm

3) Blowing agent b1: Azodicarbonamide (Ebina Kasei Kogyo “Binihol AC # 3”)
b2: 4,4′-oxybis (benzenesulfonylhydrazide) (“Neocerbon N # 5000” manufactured by Eiwa Chemical Industry Co., Ltd.)
b3: Sodium hydrogen carbonate (“Selbone SC-K” manufactured by Eiwa Chemical Industry Co., Ltd.)

4) Binder component c1: Paraffin wax (“LUVAX 1266” manufactured by Nippon Seiwa Co., Ltd.), melting point: 69 ° C.
c2: Polyethylene wax (“High Wax 2020E” manufactured by Mitsui Chemicals), melting point 100 ° C.
c3: Montanic acid ester wax (“LICOWAX-E” manufactured by Clariant), softening point 80 ° C.
c4: Ethylene bisstearylamide (“Sripax-E” manufactured by Nippon Kasei Co., Ltd.), melting point 140 ° C.

5) Thermoplastic resin PA1: Polyamide 6 resin ("A1030GFL20" manufactured by Unitika Ltd.), containing 20% glass fiber.
PA2: Polyamide 6 resin ("M1030DG" manufactured by Unitika), layered silicate 4% and glass fiber 6%.
PA3: Polyamide 10T resin (“XG4” manufactured by Unitika Ltd.), containing 20% glass fiber.
PBT: Polybutylene terephthalate resin (“# 3200” manufactured by Polyplastics Co., Ltd.), containing 20% glass fiber.
PPS: Polyphenylene sulfide resin (“A503-X05” manufactured by Toray Industries, Inc.) and 30% glass fiber.

6) Resin granular material d1: Polyamide 6 granular material (“A1012LP-60” manufactured by Unitika Ltd.), average particle size 150 μm
d2: Polyamide 10T powder (“XP” manufactured by Unitika), average particle size 150 μm
d3: Polybutylene terephthalate granular material (polyplastic "2002" pulverized with a rotor type pulverizer), average particle size 150 μm
d4: Polyphenylene sulfide granular material (“FZ-2100” manufactured by DIC was pulverized with a rotor-type pulverizer), average particle size 150 μm

2. Test method

1) Bulk specific gravity of blowing agent composition pellets Measured according to JIS K7365.

2) Disintegration of foaming agent composition pellets 50 g of foaming agent composition pellets were collected through a 20-mesh sieve, placed in a 100 cc glass container, and shaken with a paint shaker for 10 minutes. Thereafter, the powder was sieved through a 20-mesh sieve and collected. And the ratio (henceforth a disintegration rate) of the screened-off powder mass with respect to the extract | collected foaming agent composition pellet mass was computed by following Formula.
Disintegration rate (%) = powder mass (g) / 50 (g) × 100
Practically, the decay rate is preferably 2% or less, and more preferably 1% or less. A disintegration rate of 2% or less is judged to be excellent in disintegration.

3) Blocking resistance of the foaming agent composition pellets 100 g of the foaming agent composition pellets were collected in a glass container having a volume of 100 ml and placed in an oven set at a temperature of 100 ° C. After 1 hour, the glass container was taken out of the oven, cooled sufficiently to room temperature, and then judged by whether or not the foaming agent composition pellets adhered. The foaming agent composition pellets adhered to each other were designated as “blocking”, and those not adhered were designated as “no blocking”.
As for “with blocking”, the biting property of the mixed resin pellet made of the foaming agent composition pellet and the thermoplastic resin into the cylinder in the subsequent injection molding was observed. The thing that the biting was poor and the weighing of the injection molding machine became unstable was defined as “Degradability of workability”.

2) Impact strength of foam A graphic impact tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.) using a disk-shaped foam molded body with a diameter of 100 mm that is foamed so that the thickness before foaming becomes 4 mm after foaming by the injection core back method. The shock absorption energy at the time of destruction was measured with. The value of the impact absorption energy obtained was defined as the impact strength. Those having an impact strength of 1.0 J or more are practically excellent.

3) Stability of foam molding The surface of the above-mentioned foam molding was observed, and it was measured whether the surface had a uniform thickness due to expansion due to foaming. The thickness of 10 sheets was measured and the standard deviation was calculated. The standard deviation is preferably 0.20 or less, and more preferably 0.025 or less.

Production Example 1
60 parts by mass of calcium carbonate particles (a1), 8 parts by mass of the foaming agent (b1) and 32 parts by mass of the binder component (c1) were uniformly blended. This mixture was heated and compressed using a compression granulator at a compression temperature of 100 ° C. to obtain a foaming agent composition pellet (M-1) having a diameter of 3 mm and a length of 2.5 mm. Measurement of bulk specific gravity of the obtained foaming agent composition pellet (M-1), disintegration, and evaluation of blocking resistance were performed. The results are shown in Table 1.

Production Examples 2 to 20
According to the composition of Table 1 or Table 2, foaming agent composition pellets (M-2) to (M-20) were obtained in the same manner as in Production Example 1, and the measurement of bulk specific gravity, evaluation of disintegration, and blocking resistance were performed. went. The results are shown in Table 1 or Table 2.

Production Example 21
Except that talc was used in place of the silica particles, a foaming agent composition pellet (M-21) was obtained in the same manner as in Production Example 1, and measurement of bulk specific gravity, disintegration, and blocking resistance were evaluated. The results are shown in Table 2.

Example 1
98 parts by mass of polyamide 6 resin (PA1) and 2 parts by mass of the foaming agent composition pellet (M-1) prepared in Production Example 1 were dry blended, and an injection molding machine equipped with a shut-off nozzle (S-manufactured by FANUC) 2000i) and injection molded under the conditions of a cylinder temperature of 270 ° C. and a mold temperature of 60 ° C. At this time, it fills to the flow end of the test piece in 0.2 s, then passes through a pressure holding process at 75 MPa for 0.2 second, and immediately after that, the die plate of the injection molding machine is set to double the set foaming ratio at 60 mm / s. Retreated to become. Various evaluation was performed about the obtained foaming molding. The results are shown in Table 3.

Examples 2-5, 8-10
According to the formulation in Table 3, foam molding was performed in the same manner as in Example 1. Various evaluation was performed about the obtained foaming molding. The results are shown in Table 3.

Example 6
97 parts by mass of polybutylene terephthalate resin (PBT) and 3 parts by mass of the foaming agent composition pellet (M-1) prepared in Production Example 1 were dry blended and injected under conditions of a cylinder temperature of 260 ° C and a mold temperature of 80 ° C. Molded. Each characteristic evaluation was performed about the obtained foaming molding. The results are shown in Table 3.

Example 7
97 parts by mass of polyphenylene sulfide resin (PPS) and 3 parts by mass of the foaming agent composition pellets (M-1) prepared in Production Example 1 are dry blended and injection molded under conditions of a cylinder temperature of 310 ° C and a mold temperature of 130 ° C. did. Each characteristic evaluation was performed about the obtained foaming molding. The results are shown in Table 3.

Examples 11-18
According to the formulation shown in Table 4, foam molding was performed in the same manner as in Example 1. Various evaluation was performed about the obtained foaming molding. The results are shown in Table 4.

Example 19
In accordance with the formulation shown in Table 4, foam molding was performed in the same manner as in Example 6. Various evaluation was performed about the obtained foaming molding. The results are shown in Table 4.

Example 20
In accordance with the formulation shown in Table 4, foam molding was performed in the same manner as in Example 7. Various evaluation was performed about the obtained foaming molding. The results are shown in Table 4.

Comparative Examples 1-7
According to the formulation in Table 5, foam molding was performed in the same manner as in Example 1. Various evaluation was performed about the obtained foaming molding. The results are shown in Table 5.

  In Examples 1-20, since the predetermined foaming agent composition pellet of the present application was used, the foamed molded article was excellent in impact resistance and stable in foaming.

  In Comparative Example 1, since the blending of the calcium carbonate particles exceeded the upper limit, the bulk specific gravity was high, and the disintegrating property of the resulting foaming agent composition pellet was inferior. Also, the molding stability was poor.

  In Comparative Example 2, since the blending of calcium carbonate particles was less than the lower limit, the resulting foaming agent composition pellets were inferior in blocking resistance. Further, the molding stability was inferior and the impact resistance was lowered.

  In Comparative Example 3, since the blending of the foaming agent exceeded the upper limit, the molding stability was inferior.

  In Comparative Example 4, since the blending of the foaming agent was less than the lower limit, it was necessary to blend a large amount of foaming agent composition pellets for sufficient foaming, resulting in poor impact resistance.

  In Comparative Example 5, since the blending of the binder component was less than the lower limit, the resulting foaming agent composition pellets had low bulk specific gravity and poor disintegration. Moreover, the molding stability was inferior.

  In Comparative Example 6, since the blending of the binder component exceeded the upper limit, the resulting foaming agent composition pellets were inferior in blocking resistance. Moreover, the molding stability was inferior, and the surface of the molded body was damaged with unnecessary gas generation.

In Comparative Example 7, since calcium carbonate particles were not used, the resulting foaming agent composition pellets had high bulk specific gravity and poor disintegration. Furthermore, the blocking resistance was also inferior. Also, the molding stability was poor.

Claims (6)

A resin pellet for molding formed by mixing a foaming agent composition pellet and a thermoplastic resin pellet,
The foaming agent composition pellets contain calcium carbonate particles (A) 30 to 80% by mass, foaming agent (B) 3 to 30% by mass and binder component (C) 10 to 50% by mass, (A) to (C ) Is 100% by mass , and only one or more compounds selected from the group consisting of paraffin wax, polyolefin wax, higher fatty acid ester, higher fatty acid metal salt and higher fatty acid bisamide are used as the binder component (C). A resin pellet for molding characterized by the above. The resin pellet for molding according to claim 1, wherein the foam specific gravity of the foaming agent composition pellet measured by JIS K7365 is 0.5 to 1.0. The resin pellet for molding according to claim 1 or 2 , wherein the thermoplastic resin pellet is polyamide. Blowing agent composition pellets further molding resin pellets according to claim 1 containing polyamide powder particle body (D). Calcium carbonate particles (A), foaming agent (B), binder component (C) and polyamide powder (D) are mixed together and compressed into a pellet while heating at a temperature above the melting point of the binder component (C). The method for producing molding resin pellets according to any one of claims 1 to 4, wherein the foaming agent composition pellets obtained by molding and polyamide resin pellets are mixed. The molded object formed by shape | molding the resin pellet for shaping | molding in any one of Claims 1-4 .