JP4781998B2 - Method for producing polyolefin pre-expanded particles using water as a foaming agent - Google Patents
Method for producing polyolefin pre-expanded particles using water as a foaming agent Download PDFInfo
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- JP4781998B2 JP4781998B2 JP2006510180A JP2006510180A JP4781998B2 JP 4781998 B2 JP4781998 B2 JP 4781998B2 JP 2006510180 A JP2006510180 A JP 2006510180A JP 2006510180 A JP2006510180 A JP 2006510180A JP 4781998 B2 JP4781998 B2 JP 4781998B2
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- polyolefin
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- 239000002245 particle Substances 0.000 title claims description 159
- 229920000098 polyolefin Polymers 0.000 title claims description 79
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims description 33
- 238000004519 manufacturing process Methods 0.000 title claims description 17
- 239000004088 foaming agent Substances 0.000 title claims description 16
- 229920005672 polyolefin resin Polymers 0.000 claims description 61
- JYEUMXHLPRZUAT-UHFFFAOYSA-N 1,2,3-triazine Chemical group C1=CN=NN=C1 JYEUMXHLPRZUAT-UHFFFAOYSA-N 0.000 claims description 31
- 239000012298 atmosphere Substances 0.000 claims description 21
- 238000005187 foaming Methods 0.000 claims description 21
- 229920005989 resin Polymers 0.000 claims description 19
- 239000011347 resin Substances 0.000 claims description 19
- 239000011256 inorganic filler Substances 0.000 claims description 17
- 229910003475 inorganic filler Inorganic materials 0.000 claims description 17
- 239000002612 dispersion medium Substances 0.000 claims description 16
- 150000001875 compounds Chemical class 0.000 claims description 13
- 239000006185 dispersion Substances 0.000 claims description 13
- 239000002270 dispersing agent Substances 0.000 claims description 10
- 238000010438 heat treatment Methods 0.000 claims description 4
- 238000007599 discharging Methods 0.000 claims 1
- 238000000034 method Methods 0.000 description 25
- 230000000694 effects Effects 0.000 description 20
- 238000002844 melting Methods 0.000 description 16
- 230000008018 melting Effects 0.000 description 16
- ZFSLODLOARCGLH-UHFFFAOYSA-N isocyanuric acid Chemical compound OC1=NC(O)=NC(O)=N1 ZFSLODLOARCGLH-UHFFFAOYSA-N 0.000 description 12
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 description 12
- 230000000704 physical effect Effects 0.000 description 11
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 10
- -1 polyethylenes Polymers 0.000 description 10
- 229920000877 Melamine resin Polymers 0.000 description 9
- 229910001872 inorganic gas Inorganic materials 0.000 description 9
- 239000003570 air Substances 0.000 description 8
- 239000006260 foam Substances 0.000 description 8
- 239000000126 substance Substances 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- 239000007789 gas Substances 0.000 description 7
- 239000012188 paraffin wax Substances 0.000 description 7
- QORWJWZARLRLPR-UHFFFAOYSA-H tricalcium bis(phosphate) Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O QORWJWZARLRLPR-UHFFFAOYSA-H 0.000 description 7
- 235000019731 tricalcium phosphate Nutrition 0.000 description 7
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 6
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 5
- 229910052757 nitrogen Inorganic materials 0.000 description 5
- 239000011734 sodium Substances 0.000 description 5
- 229910052708 sodium Inorganic materials 0.000 description 5
- BDHFUVZGWQCTTF-UHFFFAOYSA-M sulfonate Chemical compound [O-]S(=O)=O BDHFUVZGWQCTTF-UHFFFAOYSA-M 0.000 description 5
- 239000000454 talc Substances 0.000 description 5
- 229910052623 talc Inorganic materials 0.000 description 5
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 4
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 4
- 125000000217 alkyl group Chemical group 0.000 description 4
- 238000001938 differential scanning calorimetry curve Methods 0.000 description 4
- 229920001477 hydrophilic polymer Polymers 0.000 description 4
- 239000011342 resin composition Substances 0.000 description 4
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 description 3
- 239000004604 Blowing Agent Substances 0.000 description 3
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 3
- 239000007983 Tris buffer Substances 0.000 description 3
- 125000004432 carbon atom Chemical group C* 0.000 description 3
- 239000001569 carbon dioxide Substances 0.000 description 3
- 229910002092 carbon dioxide Inorganic materials 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 229920005604 random copolymer Polymers 0.000 description 3
- 229920006395 saturated elastomer Polymers 0.000 description 3
- 239000004094 surface-active agent Substances 0.000 description 3
- 150000003918 triazines Chemical class 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 230000002411 adverse Effects 0.000 description 2
- 239000000872 buffer Substances 0.000 description 2
- 239000001273 butane Substances 0.000 description 2
- 229910000019 calcium carbonate Inorganic materials 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 239000011162 core material Substances 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000000113 differential scanning calorimetry Methods 0.000 description 2
- 229920005674 ethylene-propylene random copolymer Polymers 0.000 description 2
- 229920001903 high density polyethylene Polymers 0.000 description 2
- 239000004700 high-density polyethylene Substances 0.000 description 2
- 229920001519 homopolymer Polymers 0.000 description 2
- 238000005470 impregnation Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 229920000092 linear low density polyethylene Polymers 0.000 description 2
- 239000004707 linear low-density polyethylene Substances 0.000 description 2
- 229920001684 low density polyethylene Polymers 0.000 description 2
- 239000004702 low-density polyethylene Substances 0.000 description 2
- HQKMJHAJHXVSDF-UHFFFAOYSA-L magnesium stearate Chemical compound [Mg+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O HQKMJHAJHXVSDF-UHFFFAOYSA-L 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229920001179 medium density polyethylene Polymers 0.000 description 2
- 239000004701 medium-density polyethylene Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 2
- OFBQJSOFQDEBGM-UHFFFAOYSA-N n-pentane Natural products CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 2
- 239000002736 nonionic surfactant Substances 0.000 description 2
- 239000005022 packaging material Substances 0.000 description 2
- 239000001294 propane Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- BPXVHIRIPLPOPT-UHFFFAOYSA-N 1,3,5-tris(2-hydroxyethyl)-1,3,5-triazinane-2,4,6-trione Chemical compound OCCN1C(=O)N(CCO)C(=O)N(CCO)C1=O BPXVHIRIPLPOPT-UHFFFAOYSA-N 0.000 description 1
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 description 1
- GZVHEAJQGPRDLQ-UHFFFAOYSA-N 6-phenyl-1,3,5-triazine-2,4-diamine Chemical compound NC1=NC(N)=NC(C=2C=CC=CC=2)=N1 GZVHEAJQGPRDLQ-UHFFFAOYSA-N 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 206010049040 Weight fluctuation Diseases 0.000 description 1
- NJYZCEFQAIUHSD-UHFFFAOYSA-N acetoguanamine Chemical compound CC1=NC(N)=NC(N)=N1 NJYZCEFQAIUHSD-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 150000001336 alkenes Chemical group 0.000 description 1
- YSKUZVBSHIWEFK-UHFFFAOYSA-N ammelide Chemical compound NC1=NC(O)=NC(O)=N1 YSKUZVBSHIWEFK-UHFFFAOYSA-N 0.000 description 1
- MASBWURJQFFLOO-UHFFFAOYSA-N ammeline Chemical compound NC1=NC(N)=NC(O)=N1 MASBWURJQFFLOO-UHFFFAOYSA-N 0.000 description 1
- 239000003945 anionic surfactant Substances 0.000 description 1
- 239000003963 antioxidant agent Substances 0.000 description 1
- 230000003078 antioxidant effect Effects 0.000 description 1
- 239000002216 antistatic agent Substances 0.000 description 1
- 239000012752 auxiliary agent Substances 0.000 description 1
- AGXUVMPSUKZYDT-UHFFFAOYSA-L barium(2+);octadecanoate Chemical compound [Ba+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O AGXUVMPSUKZYDT-UHFFFAOYSA-L 0.000 description 1
- 229920001400 block copolymer Polymers 0.000 description 1
- 125000000484 butyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 239000001506 calcium phosphate Substances 0.000 description 1
- CJZGTCYPCWQAJB-UHFFFAOYSA-L calcium stearate Chemical compound [Ca+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O CJZGTCYPCWQAJB-UHFFFAOYSA-L 0.000 description 1
- 235000013539 calcium stearate Nutrition 0.000 description 1
- 239000008116 calcium stearate Substances 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 239000003093 cationic surfactant Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000004581 coalescence Methods 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 230000002301 combined effect Effects 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- GVGUFUZHNYFZLC-UHFFFAOYSA-N dodecyl benzenesulfonate;sodium Chemical compound [Na].CCCCCCCCCCCCOS(=O)(=O)C1=CC=CC=C1 GVGUFUZHNYFZLC-UHFFFAOYSA-N 0.000 description 1
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 1
- 239000003063 flame retardant Substances 0.000 description 1
- 238000010097 foam moulding Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 150000002484 inorganic compounds Chemical class 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 description 1
- 239000001095 magnesium carbonate Substances 0.000 description 1
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 1
- 235000019359 magnesium stearate Nutrition 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- ZQKXQUJXLSSJCH-UHFFFAOYSA-N melamine cyanurate Chemical compound NC1=NC(N)=NC(N)=N1.O=C1NC(=O)NC(=O)N1 ZQKXQUJXLSSJCH-UHFFFAOYSA-N 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229920001083 polybutene Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000000344 soap Substances 0.000 description 1
- 229940080264 sodium dodecylbenzenesulfonate Drugs 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 229910000391 tricalcium phosphate Inorganic materials 0.000 description 1
- 229940078499 tricalcium phosphate Drugs 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
- 239000004711 α-olefin Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
- C08J9/12—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a physical blowing agent
- C08J9/125—Water, e.g. hydrated salts
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/16—Making expandable particles
- C08J9/18—Making expandable particles by impregnating polymer particles with the blowing agent
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2203/00—Foams characterized by the expanding agent
- C08J2203/06—CO2, N2 or noble gases
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
- C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Description
本発明は、緩衝包装材、通函、断熱材、自動車のバンパー芯材などに用いられるポリオレフィン系樹脂の型内発泡成形体の製造に好適に使用しうるポリオレフィン系予備発泡粒子の製造方法に関する。 The present invention relates to a method for producing a polyolefin-based pre-expanded particle that can be suitably used for the production of an in-mold foam-molded product of a polyolefin-based resin used for buffer packaging materials, boxes, heat insulating materials, automobile bumper core materials, and the like.
従来より、ポリオレフィン系樹脂粒子を発泡剤とともに水系分散媒に分散させ、昇温して一定圧力、一定温度としてポリオレフィン系樹脂粒子中に発泡剤を含浸したのち、低圧雰囲気下に放出して予備発泡粒子を得る方法が知られている。発泡剤としては、プロパン、ブタンといった揮発性有機発泡剤を使用する方法（特開昭５２−７７１７４号公報）、炭酸ガス、窒素、空気などの無機ガスを使用する方法（特開昭６０−２４５６５０号公報）が開示されている。
しかしながら、プロパン、ブタンなどの揮発性有機発泡剤は、高価でありコスト高となる。また、揮発性有機発泡剤は、ポリオレフィン系樹脂粒子を可塑化する作用があり、高発泡倍率を得やすい反面、その可塑化作用のため、ポリオレフィン系予備発泡粒子の発泡倍率および結晶状態のコントロールが難しいといった欠点を有している。
炭酸ガス、窒素、空気などの無機ガスを使用する場合は、ポリオレフィン系樹脂粒子への含浸能が低いため、一般に３〜６ＭＰａ程度の高い圧力で含浸させる必要がある。このため発泡剤をポリオレフィン系樹脂粒子に含浸させるための含浸槽は高い耐圧性能が必要となり、設備コスト高となる欠点を有している。
これらの欠点を解決し、型内発泡成形体の製造に好適に使用しうるポリオレフィン系樹脂発泡粒子を経済的に製造する方法として、分散媒に使用する水を発泡剤として利用する方法が提案されている。
密閉容器内で親水性ポリマーおよび無機充填剤を含有するポリオレフィン系樹脂粒子を水に分散させ、この樹脂粒子の軟化温度以上に加熱して含水ポリオレフィン系樹脂粒子とした後、この分散液を低圧域に放出させてポリオレフィン系予備発泡粒子を製造する方法が提案されている（特開平１１−１０６５７６号公報）。この方法では、炭酸ガス、窒素、空気などの無機ガスを発泡剤として使用する場合に比べて低い容器内圧でポリオレフィン系予備発泡粒子を得ることができる。しかしながら、発泡倍率が要求水準に満たない場合も多く、更に親水性ポリマーとポリオレフィン系樹脂の混合性が悪いため、発泡粒子に色むらが発生することや、発泡粒子の倍率ばらつき悪化など悪影響が発生する。
また親水性重合体と界面活性剤を含有するポリオレフィン系樹脂粒子を有機ガスまたは無機ガスからなる発泡剤ともに密閉容器内に導入し発泡する方法が提案されている（特開２０００−２９０４２１号公報）。この親水性重合体と界面活性剤を含有するポリオレフィン系樹脂粒子を水を発泡剤とする方法で製造した場合、上記例と同様に発泡粒子に色むらが発生することや、発泡粒子の倍率ばらつき悪化など悪影響が発生するため、改良が求められている。
またポリオレフィン系樹脂粒子に添加する界面活性剤としてノニオン系界面活性剤を用いて、有機ガスまたは無機ガスからなる発泡剤ともに密閉容器内に導入し発泡する方法も提案されている（特開平３−３３２３９号公報）。このポリオレフィン系樹脂粒子を、水を発泡剤とする方法で製造した場合、ノニオン系界面活性剤の含水効果が小さいため発泡倍率が要求水準に満たない場合も多く、高い発泡倍率を達成できる方法の開発が求められている。
更に倍率ばらつきが大きい場合型内発泡成形体としたときの重量変動が大きくなる問題が発生する。近年、製品の品質規格がより厳しくなっており、そのため倍率ばらつきの要求水準が高くなっているため、従来よりも倍率ばらつきの小さいポリオレフィン系予備発泡粒子が求められている。Conventionally, polyolefin resin particles are dispersed in an aqueous dispersion medium together with a foaming agent, heated to a constant pressure and constant temperature, impregnated with a foaming agent in a polyolefin resin particle, then released into a low-pressure atmosphere and pre-foamed. Methods for obtaining particles are known. As the foaming agent, a method using a volatile organic foaming agent such as propane or butane (Japanese Patent Laid-Open No. 52-77174), a method using an inorganic gas such as carbon dioxide, nitrogen or air (Japanese Patent Laid-Open No. 60-245650). No. Gazette) is disclosed.
However, volatile organic blowing agents such as propane and butane are expensive and expensive. In addition, the volatile organic foaming agent has the effect of plasticizing the polyolefin resin particles, and it is easy to obtain a high expansion ratio. On the other hand, because of the plasticizing action, the expansion ratio and crystal state of the polyolefin pre-expanded particles can be controlled. It has the disadvantage of being difficult.
When using an inorganic gas such as carbon dioxide, nitrogen, or air, it is generally necessary to impregnate at a high pressure of about 3 to 6 MPa because the impregnation ability of the polyolefin resin particles is low. For this reason, the impregnation tank for impregnating the polyolefin resin particles with the foaming agent requires a high pressure resistance, and has the disadvantage of increasing the equipment cost.
As a method for solving these drawbacks and economically producing polyolefin resin expanded particles that can be suitably used for the production of in-mold foam molded articles, a method using water used as a dispersion medium as a blowing agent has been proposed. ing.
In a closed container, polyolefin resin particles containing a hydrophilic polymer and an inorganic filler are dispersed in water, heated to a temperature equal to or higher than the softening temperature of the resin particles to obtain water-containing polyolefin resin particles, and then the dispersion is reduced to a low pressure region. A method for producing polyolefin-based pre-expanded particles by being discharged into a liquid has been proposed (Japanese Patent Laid-Open No. 11-106576). In this method, polyolefin-based pre-expanded particles can be obtained at a lower container internal pressure than when an inorganic gas such as carbon dioxide, nitrogen, or air is used as a foaming agent. However, there are many cases where the expansion ratio is less than the required level, and furthermore, since the mixing of the hydrophilic polymer and the polyolefin resin is poor, there is an adverse effect such as color unevenness in the expanded particles and deterioration in the expanded dispersion of expanded particles. To do.
Further, a method has been proposed in which polyolefin resin particles containing a hydrophilic polymer and a surfactant are introduced into an airtight container together with a foaming agent composed of an organic gas or an inorganic gas and foamed (Japanese Patent Laid-Open No. 2000-290421). . When polyolefin resin particles containing this hydrophilic polymer and a surfactant are produced by a method using water as a foaming agent, color unevenness occurs in the foamed particles as in the above example, and variation in magnification of the foamed particles. Since adverse effects such as deterioration occur, improvement is required.
Further, there has been proposed a method in which a nonionic surfactant is used as a surfactant to be added to the polyolefin resin particles, and a foaming agent composed of an organic gas or an inorganic gas is introduced into a hermetic container and foamed (Japanese Patent Laid-Open No. Hei 3- No. 33239). When the polyolefin resin particles are produced by a method using water as a foaming agent, the water content effect of the nonionic surfactant is small, so the foaming ratio is often less than the required level. Development is required.
Further, when the variation in magnification is large, there arises a problem that the weight fluctuation when the in-mold foam-molded product is obtained becomes large. In recent years, the quality standards of products have become more stringent, and as a result, the required level of variation in magnification has increased. Therefore, polyolefin-based pre-expanded particles having a smaller variation in magnification than before have been demanded.
本発明は、ポリオレフィン系樹脂粒子中に含水させた水を有効な発泡剤とするポリオレフィン系予備発泡粒子の製造方法において、高い発泡倍率のポリオレフィン系予備発泡粒子を経済的に提供することを目的とする。更には、倍率ばらつきが少ないポリオレフィン系予備発泡粒子を提供することを目的とする。
本発明者は、鋭意研究の結果、ヒドロキシアルキルエタノールアミンと、トリアジン骨格を有し単位トリアジン骨格あたりの分子量が３００以下の化合物を含有させたポリオレフィン系樹脂粒子を基材樹脂として用いることにより、ポリオレフィン系樹脂粒子内に水を効率的に含水させることができ、上記課題を解決しうることを見出し、本発明を完成するに至った。
すなわち本発明の第１は、ポリオレフィン系樹脂に対し、ヒドロキシアルキルエタノールアミンと、トリアジン骨格を有し単位トリアジン骨格あたりの分子量が３００以下の化合物を含有させたポリオレフィン系樹脂粒子を、密閉容器内で水系分散媒に分散させ前記ポリオレフィン系樹脂粒子の軟化温度以上の温度に加熱し、密閉容器内の内圧を高めたのち、分散媒として使用した水を発泡剤として内圧よりも低圧の雰囲気中に放出して発泡させることを特徴とするポリオレフィン系予備発泡粒子の製造方法に関する。
好ましい態様としては、前記ポリオレフィン系樹脂粒子が無機充填剤を含むことを特徴とする、前記記載のポリオレフィン系予備発泡粒子の製造方法に関する。
別の好ましい態様としては、前記ポリオレフィン系樹脂粒子を密閉容器内で水系分散媒に分散させる際に、ポリオレフィン系樹脂粒子１００重量部に対して分散剤０．２重量部以上１重量部以下、分散助剤０．０３重量部以上０．１５重量部以下を配合することを特徴とする前記記載のポリオレフィン系予備発泡粒子の製造方法に関する。
更に別の好ましい態様としては、前記ポリオレフィン系予備発泡粒子を密閉容器内から、内圧よりも低圧の雰囲気中に放出する際の低圧の雰囲気が６０℃以上の気体であり、かつ、放出させる際に衝突板もしくは容器壁に衝突角度５度以上９０度以下で衝突させることを特徴とする前記記載のポリオレフィン系予備発泡粒子の製造方法に関する。
本発明では水を発泡剤とするポリオレフィン系予備発泡粒子の製造方法において、高い発泡倍率の予備発泡粒子を製造することが出来る。更には、倍率ばらつきの少ないポリオレフィン系予備発泡粒子を製造することができる。
このポリオレフィン系予備発泡粒子は通函、断熱材、自動車のバンパー芯材、特に帯電防止性能が求められる電化製品の緩衝包装材などに用いられる、ポリオレフィン系樹脂の型内発泡成形体の製造に用いられる。
本発明に用いられるポリオレフィン系樹脂とは、オレフィン単位を５０重量％以上、好ましくは８０重量％以上、より好ましくは９０重量％以上含む樹脂のことであり、その具体例としては、例えば高密度ポリエチレン（ＨＤＰＥ）、中密度ポリエチレン（ＭＤＰＥ）、低密度ポリエチレン（ＬＤＰＥ）、直鎖状低密度ポリエチレン（Ｌ−ＬＤＰＥ）、低分子量ポリエチレンなどのポリエチレン類、プロピレンホモポリマー、α−オレフィン−プロピレンランダム共重合体、α−オレフィン−プロピレンブロック共重合体などのポリプロピレン類、ポリブテンなどのその他のポリオレフィンホモポリマー類などが挙げられる。これらは、単独で用いてもよく、２種以上併用してもよい。特に、エチレン−プロピレンランダム共重合体、エチレン−プロピレン−１−ブテンランダム共重合体、プロピレン−１−ブテンランダム共重合体が良好な発泡性を示すため、好適に使用し得る。
前記ポリオレフィン系樹脂は、発泡性、成形性に優れている。型内発泡成形体としたときに機械的強度、耐熱性に優れるポリオレフィン系予備発泡粒子を得るには、ポリオレフィン系樹脂の融点は、１１０℃以上１６５℃以下であることが好ましく、更に好ましくは１１５℃以上１６０℃以下である。ポリオレフィン系樹脂のメルトインデックス（以下、ＭＩ値）は、０．５ｇ／１０分以上３０ｇ／１０分以下であることが好ましく、更に好ましくは０．５ｇ／１０分以上１５ｇ／１０分である。
前記融点が１１０℃以上１６５℃以下のポリオレフィン系樹脂を用いた場合、十分な耐熱性、機械的強度と、型内発泡成形時の融着を確保することできる。前記ＭＩ値が０．５ｇ／１０分以上３０ｇ／１０分以下のポリオレフィン系樹脂を用いた場合、発泡セルが破泡しにくく、高発泡倍率のポリオレフィン系予備発泡粒子が得られる傾向にある。
ここで、前記融点とは、示差走査熱量計によってポリオレフィン系樹脂１〜１０ｍｇを４０℃から２２０℃まで１０℃／分の速度で昇温し、その後４０℃まで１０℃／分の速度で冷却し、再度２２０℃まで１０℃／分の速度で昇温した時に得られるＤＳＣ曲線における吸熱曲線のピーク温度をいう。また、前記ＭＩ値とはＪＩＳ Ｋ７２１０に準拠し、温度２３０℃、荷重２．１６Ｋｇで測定した値である。
本発明に用いられるヒドロキシアルキルエタノールアミンとは、特殊カチオン界面活性剤であり、次に示す組成式で表される物質である。
このヒドロキシアルキルエタノールアミンは、ポリオレフィン系樹脂粒子の含水率を高め、高発泡倍率のポリオレフィン系予備発泡粒子を与える効果がある。使用量は特に限定されないが、通常、ヒドロキシアルキルエタノールアミンの使用量の上限は、ポリオレフィン系樹脂１００重量部に対して、５重量部が好ましく、３重量部がより好ましい。ヒドロキシアルキルエタノールアミンの使用量の下限は、０．０１重量部が好ましく、０．５重量部がより好ましい。ヒドロキシアルキルエタノールアミンを０．０１重量部以上５重量部以下添加することによって、生産コストがあまり上昇することなく、またポリオレフィン系樹脂粒子への含水効果が充分であるため、高い発泡倍率のポリオレフィン系予備発泡粒子を製造することができる。
本発明においては、トリアジン骨格を有し単位トリアジン骨格あたりの分子量が３００以下の化合物（以下、「トリアジン類化合物」と称する場合がある）を用いる。ここで単位トリアジン骨格あたりの分子量とは、１分子中に含まれるトリアジン骨格数で分子量を除した値である。このトリアジン類化合物は、ポリオレフィン系樹脂粒子の含水率を高め、高発泡倍率のポリオレフィン系予備発泡粒子を与えるとともに、発泡倍率バラツキ、セル径バラツキを抑える効果がある。単位トリアジン骨格あたりの分子量が３００を超えると、含水率を高める効果、発泡倍率バラツキ、セル径バラツキを抑える効果が十分に発揮されない。
本発明に用いるヒドロキシアルキルエタノールアミンと、トリアジン骨格を有し単位トリアジン骨格あたりの分子量が３００以下の化合物はそれぞれに含水効果があり、ポリオレフィン系予備発泡粒子の発泡倍率を大きくすることができるが、ポリオレフィン系樹脂にヒドロキシアルキルエタノールアミンとトリアジン骨格を有し単位トリアジン骨格あたりの分子量が３００以下の化合物を併用して添加することによって、両者の含水効果を足し合わせた以上の含水効果が見られ、両者の効果を足し合わせた以上の高い発泡倍率を有するポリオレフィン系予備発泡粒子を製造することができる。
本発明に用いるトリアジン骨格を有し単位トリアジン骨格あたりの分子量が３００以下の化合物としては、例えば、メラミン（化学名：１，３，５−トリアジン−２，４，６−トリアミン）、アンメリン（化学名：１，３，５−トリアジン−２−ヒドロキシ−４，６−ジアミン）、アンメリド（化学名：１，３，５−トリアジン−２，４−ヒドロキシ−６−アミン）、シアヌル酸（化学名：１，３，５−トリアジン−２，４，６−トリオール）、イソシアヌル酸（化学名：１，３，５−トリアジン−２，４，６（１Ｈ，３Ｈ，５Ｈ）−トリオン）、アセトグアナミン（化学名：１，３，５−トリアジン−２，４−ジアミン−６−メチル）、ベンゾグアナミン（化学名：１，３，５−トリアジン−２，４−ジアミン−６−フェニル）、トリス（メチル）イソシアヌレート、トリス（エチル）イソシアヌレート、トリス（ブチル）イソシアヌレート、トリス（２−ヒドロキシエチル）イソシアヌレート、メラミン・イソシアヌル酸縮合物などが挙げられる。これらは単独で用いてもよく、２種以上併用してもよい。特に、含水率を高める効果、発泡倍率バラツキ、セル径バラツキを抑える効果が高いことから、メラミン、イソシアヌル酸、メラミン・イソシアヌル酸縮合物が好適に使用し得る。
以下、本発明においては、トリアジン骨格を有し単位トリアジン骨格あたりの分子量が３００以下の化合物を、トリアジン類化合物ということもある。
これらトリアジン類化合物は、より均一で良好なセル構造を得るのに、通常、平均粒子径０．１〜８００μｍ、更には１〜１００μｍのものが好ましく、粒子径は均一であるほど好ましい。また、固結防止のためにステアリン酸マグネシウム、ステアリン酸バリウム、ステアリン酸カルシウムなどの金属セッケンを０．１〜１重量％配合したものでもかまわない。
さらに、これらトリアジン類化合物は、ポリオレフィン系樹脂組成物とする際の加工温度で固体粒子として存在するものがより好ましい。融点を持つ場合は、融点が１８０℃以上のものが好ましい。融点を持たず分解する場合は、分解温度が２３０℃以上のものが好ましい。
これらトリアジン類化合物の使用量は、特に限定されないが、通常、使用量の上限はポリオレフィン系樹脂１００重量部に対して、８重量部が好ましく、５重量部がより好ましい。一方、使用量の下限はポリオレフィン系樹脂１００重量部に対して、０．０５重量部が好ましく、０．０８重量部がより好ましい。０．０５重量部以上８重量部以下で使用すると、含水率を高める効果、発泡倍率バラツキおよびセル径バラツキの抑制効果がより一層発揮され、更にポリオレフィン系予備発泡粒子のセル径が微細化及び破泡しにくく、より良好な成形性を発揮することができる。
本発明で用いられるポリオレフィン系樹脂粒子には、気泡が均一で高い発泡倍率のポリオレフィン系予備発泡粒子を得ることができるという点から、無機充填剤を含有せしめるのが好ましい。
前記無機充填剤の具体例としては、例えば、タルク、炭酸カルシウムなどが挙げられる。これらの無機充填剤の中では、タルクを使用すると倍率ばらつきが小さく、気泡が均一で、比較的高い発泡倍率のポリオレフィン系予備発泡粒子を与える点から好ましい。
前記無機充填剤の平均粒子径は、特に限定されないが、気泡が均一であるポリオレフィン系予備発泡粒子を得ることができる、また該ポリオレフィン系予備発泡粒子から機械的強度や柔軟性などに優れた成形体を得ることができる点から、無機充填剤の平均粒子径の上限は５０μｍが好ましく、さらには１０μｍであることが好ましい。また、２次凝集や取扱作業性の点から、無機充填剤の平均粒子径の下限は０．１μｍが好ましく、さらには０．５μｍであることが好ましい。
前記無機充填剤を使用する場合の使用量は、特に限定されないが、比較的高い発泡倍率のポリオレフィン系予備発泡粒子を得る点から、ポリオレフィン系樹脂１００重量部に対して０．００１重量部以上であることが好ましく、またポリオレフィン系予備発泡粒子を用いて成形する際に、優れた融着性を発現させ、該ポリオレフィン系予備発泡粒子から機械的強度や柔軟性などに優れた成形体を得る点から、５重量部以下さらには２重量部以下であることが好ましい。
本発明のポリオレフィン系樹脂粒子は、通常、押出機、ニーダー、バンバリーミキサー（商標）、ロール等を用いて溶融し、円柱状、楕円柱状、球状、立方体状、直方体状等のような所望の粒子形状で、その粒子の１粒の重量が、好ましくは、０．２ｍｇ以上１０ｍｇ以下、更に好ましくは０．５ｍｇ以上６ｍｇ以下の樹脂粒子に加工される。この際、ヒドロキシアルキルエタノールアミン及びトリアジン骨格を有し単位トリアジン骨格あたりの分子量が３００以下の化合物を添加し、更に必要に応じて無機充填剤を添加し、更にカーボンブラックなどの着色剤、帯電防止剤、難燃剤、酸化防止剤、耐候剤などの添加剤を添加することで、ポリオレフィン系樹脂粒子を得ることができる。
本発明におけるポリオレフィン系予備発泡粒子は、前記ポリオレフィン系樹脂粒子を、密閉容器内で水系分散媒に分散させ前記ポリオレフィン系樹脂粒子の軟化温度以上の温度に加熱し、密閉容器内の内圧を空気または窒素等によって高めたのち、内圧よりも低圧の雰囲気中に放出して発泡させる方法によって製造される。
さらに、密閉容器内容物を放出させる際の拡がりを抑制する流れ制御板を使用し、放出物を衝突板または容器壁などに衝突角度５度以上９０度以下で衝突させると、より発泡倍率バラツキの小さいポリオレフィン系予備発泡粒子を得ることができるので好ましい。使用する密閉容器には特に限定はなく、予備発泡粒子製造時における容器内圧力、容器内温度に耐えられるものであればよいが、例えばオートクレーブ型の耐圧容器が挙げられる。
前記ポリオレフィン系樹脂粒子を分散させる水系分散媒としては、前記ポリオレフィン系樹脂粒子を溶解させない溶媒であればよく、通常、環境面、経済性から水が好ましく、水系分散媒の使用量としては、前記樹脂粒子の水中での分散性を良好なものにするために、通常ポリオレフィン系樹脂粒子１００重量部に対して１００重量部以上５００重量部以下が好ましい。
分散剤として、例えば、塩基性第三リン酸カルシウム、塩基性炭酸マグネシウム、炭酸カルシウム等の難水溶性無機化合物等が挙げられ、中でも、塩基性第三リン酸カルシウムが良好な分散性を得るために好ましい。分散助剤としては、例えば、ドデシルベンゼンスルホン酸ソーダ、ｎ−パラフィンスルホン酸ソーダ、α−オレフィンスルホン酸ソーダ等のアニオン系界面活性剤が挙げられ、中でもｎ−パラフィンスルホン酸ソーダの使用が良好な分散性を得る上で好ましい。これら分散剤の使用量は、前記樹脂粒子の水系分散媒中での分散性を良好なものにするために、ポリオレフィン系樹脂粒子１００重量部に対して、０．２重量部以上１重量部以下であることが好ましく、更に好ましくは０．３重量部以上０．７重量部以下である。分散助剤の使用量は、前記樹脂粒子の水系分散媒中での分散性を良好なものにするために、０．０３重量部以上０．１５重量部以下であることが好ましく、更には０．０５重量部以上０．１２重量部以下を配合することが好ましい。
密閉容器内に、前記ポリオレフィン系樹脂粒子、分散剤および分散助剤を含む水系分散媒を仕込んだ後、攪拌しながら昇温してポリオレフィン系樹脂粒子の軟化温度以上の一定温度に昇温させ、更に、窒素または空気等で密閉容器内の内圧を高め、所定圧力に保持した後、内圧よりも低圧の雰囲気中に放出させる。この際、２〜１０ｍｍφの開口部を有する流れ制御板を通して放出させることが好ましい。
前記流れ制御板とは、一般に放出時間の調整、発泡倍率の均一化のために使用されるものであるが、オリフィス板に筒体を付けた筒付き絞り盤を用いることにより、放出された水系分散物の飛散角度を小さくすることができ、均一な大きさのポリオレフィン系予備発泡粒子に発泡させて、倍率ばらつきを少なくすることができる。前記オリフィス板とは、オリフィス型、ノズル型、ベンチュリ型などを含む概念であり、またこれらを組み合わせて使用できるが、オリフィス型が流出速度を一定に保持でき、高い倍率かつ倍率ばらつきが少ないポリオレフィン系予備発泡粒子を得ることができ、構造が簡単である点から好ましい。
前記オリフィス板に取り付けられる該筒体とは、オリフィスの放出側に一体的に取り付けられる。該筒体の材質は特に限定されるものではないが、一般的には金属が用いられ、オリフィス板と一体化されるのであるが、一体化する方法は溶接、接着等を問わないし、場合によっては同一物として作られても差し支えはない。
該筒体がオリフィス板に取り付けられる反対側の開口面積は、筒体の大きさや長さによっても一概には言えないが、一般的にはオリフィス開口面積の１．３倍以上あれば充分である。１．３倍未満の場合は、放出されるポリオレフィン系予備発泡粒子の凝集や詰まりが起こる場合がある。筒体の長さが短ければ上記のような問題は起こらないが、筒体の効果が得られない場合がある。
本発明でいう衝突板もしくは容器壁とは、放出部から放出されるポリオレフィン系予備発泡粒子の飛散方向を変化させるために設置する装置であり、通常、予備発泡時にはポリオレフィン系予備発泡粒子の軟化温度以下になると樹脂が硬化して発泡は終了する。しかし、本発明のように水系分散物を衝突板もしくは容器壁に衝突させた場合、発泡雰囲気の温度、湿度がより均一になるためと考えられるが、ポリオレフィン系予備発泡粒子個々が均一に発泡し、倍率ばらつきが小さくなるのに加え、樹脂粒子中の殆ど全ての水が衝撃で瞬間的に蒸発して有効な発泡剤になるため、衝突させない場合に比べて、倍率を上げることができる。
本発明でいう衝突角度とは、衝突板もしくは容器壁に真正面から衝突する場合を９０度、衝突板もしくは容器壁と平行に飛散して衝突しない場合を０度とする角度のことであり、０度から９０度の間の値をとりうる。
衝突角度はポリオレフィン系予備発泡粒子が衝突できる角度であればよく、特に限定されないが５度以上９０度以下が好ましく、さらには１０度以上４５度以下であることが好ましい。
前記密閉容器内圧より低圧雰囲気中とは、密閉容器内の内圧よりも低い圧力であればよく、通常は大気圧付近の圧力が選ばれる。また、前記雰囲気とは、放出された水系分散物（ポリオレフィン系予備発泡粒子及び水系分散媒）の飛散軌跡を包含する空間を意味するが、一般には、パイプ、ダクト状のもので外気と遮断した装置内をいう。また、発泡倍率をより高くするために低圧雰囲気は高温に保持されていることが好ましく、該雰囲気温度は６０℃以上であることが、発泡倍率が高くなり、倍率バラツキが低減されるためより好ましく、特には水蒸気により９０℃以上１１０℃以下に保持されていることが好ましい。
かくして得られたポリオレフィン系予備発泡粒子は示差走査熱量測定によって得られるＤＳＣ曲線において、２つの融解ピークを有するものが好ましい。さらに、この２つの融解ピーク温度の差が１０℃以上あることが好ましい。２つの融解ピークを有するポリオレフィン系予備発泡粒子の場合、型内発泡成形性が良く、機械的強度や耐熱性の良好な型内発泡成形体が得られる。
ここで、ポリオレフィン系予備発泡粒子の示差走査熱量測定によって得られるＤＳＣ曲線とは、ポリオレフィン系予備発泡粒子１〜１０ｍｇを示差走査熱量計によって１０℃／分の昇温速度で４０℃から２２０℃まで昇温したときに得られるＤＳＣ曲線のことである。
前記のごとく２つの融解ピークを有するポリオレフィン系予備発泡粒子は、予備発泡時の密閉容器内温度を適切な値に設定することにより容易に得られる。通常、該密閉容器内温度は、下限が、ポリオレフィン系樹脂粒子の主成分であるポリオレフィン系樹脂の軟化点であることが好ましく、更に好ましくは融点、より好ましくは融点＋５℃であり、また上限が、好ましくは融点＋２０℃、さらに好ましくは融点＋１５℃の範囲から選定される。
上記のようにして得たポリオレフィン系予備発泡粒子は、従来から知られている方法により、型内発泡成形体にすることができる。例えば、イ）ポリオレフィン系予備発泡粒子を無機ガスで加圧処理して粒子内に無機ガスを含浸させ所定の粒子内圧を付与した後、金型に充填し、蒸気等で加熱融着させる方法、ロ）ポリオレフィン系予備発泡粒子をガス圧力で圧縮して金型に充填し粒子の回復力を利用して、蒸気等で加熱融着させる方法、ハ）特に前処理することなく金型に充填し、蒸気等で加熱融着させる方法、などの方法が利用しうる。
また、前記ポリオレフィン系予備発泡粒子を無機ガスで加圧処理して粒子内に無機ガスを含浸させ所定の粒子内圧を付与した後、蒸気等で加熱軟化し、より高い発泡倍率のポリオレフィン系予備発泡粒子を作製した（２段発泡法）後に、型内発泡成形体にしてもよい。An object of the present invention is to economically provide polyolefin pre-expanded particles having a high expansion ratio in a method for producing polyolefin pre-expanded particles using water contained in polyolefin resin particles as an effective blowing agent. To do. It is another object of the present invention to provide polyolefin pre-expanded particles with little variation in magnification.
As a result of diligent research, the present inventor has used a polyolefin resin particle containing a hydroxyalkylethanolamine and a compound having a triazine skeleton and a molecular weight of 300 or less per unit triazine skeleton as a base resin. It has been found that water can be efficiently contained in the resin particles and the above-mentioned problems can be solved, and the present invention has been completed.
That is, according to the first aspect of the present invention, polyolefin resin particles containing a hydroxyalkylethanolamine and a compound having a triazine skeleton and a molecular weight per unit triazine skeleton of 300 or less are contained in a sealed container. Disperse in an aqueous dispersion medium and heat to a temperature higher than the softening temperature of the polyolefin resin particles to increase the internal pressure in the sealed container, then release the water used as the dispersion medium into the atmosphere at a lower pressure than the internal pressure as a foaming agent. It is related with the manufacturing method of the polyolefin-type pre-expanded particle characterized by making it foam.
As a preferred aspect, the present invention relates to the above-mentioned method for producing polyolefin-based prefoamed particles, wherein the polyolefin-based resin particles contain an inorganic filler.
As another preferred embodiment, when the polyolefin resin particles are dispersed in an aqueous dispersion medium in a closed container, the dispersant is 0.2 parts by weight or more and 1 part by weight or less dispersed with respect to 100 parts by weight of the polyolefin resin particles. The present invention relates to a method for producing polyolefin pre-expanded particles as described above, wherein 0.03 part by weight or more and 0.15 part by weight or less of an auxiliary agent is blended.
In another preferred embodiment, the low-pressure atmosphere when releasing the polyolefin-based pre-expanded particles from the sealed container into an atmosphere having a pressure lower than the internal pressure is a gas of 60 ° C. or higher, and when releasing the gas. The present invention relates to the above-mentioned polyolefin-based pre-expanded particle production method, wherein the collision is made to collide with a collision plate or a container wall at a collision angle of 5 ° to 90 °.
In the present invention, pre-expanded particles having a high expansion ratio can be produced in a method for producing polyolefin-based pre-expanded particles using water as a foaming agent. Furthermore, polyolefin pre-expanded particles with little variation in magnification can be produced.
These polyolefin-based pre-expanded particles are used for the production of in-mold foam molded products of polyolefin-based resins that are used for boxing, insulation, bumper core materials for automobiles, especially buffer packaging materials for electrical appliances that require antistatic performance. It is done.
The polyolefin resin used in the present invention is a resin containing 50% by weight or more of olefin units, preferably 80% by weight or more, more preferably 90% by weight or more. Specific examples thereof include, for example, high density polyethylene. (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (L-LDPE), polyethylenes such as low molecular weight polyethylene, propylene homopolymer, α-olefin-propylene random copolymer Examples thereof include polypropylenes such as coalescence, α-olefin-propylene block copolymer, and other polyolefin homopolymers such as polybutene. These may be used alone or in combination of two or more. In particular, an ethylene-propylene random copolymer, an ethylene-propylene-1-butene random copolymer, and a propylene-1-butene random copolymer can be suitably used because they exhibit good foaming properties.
The polyolefin resin is excellent in foamability and moldability. In order to obtain polyolefin-based pre-expanded particles having excellent mechanical strength and heat resistance when formed into an in-mold foam molded product, the melting point of the polyolefin-based resin is preferably 110 ° C. or higher and 165 ° C. or lower, more preferably 115. It is at least 160 ° C. The melt index (hereinafter referred to as MI value) of the polyolefin-based resin is preferably 0.5 g / 10 min or more and 30 g / 10 min or less, more preferably 0.5 g / 10 min or more and 15 g / 10 min.
When a polyolefin resin having a melting point of 110 ° C. or higher and 165 ° C. or lower is used, sufficient heat resistance, mechanical strength, and fusion during in-mold foam molding can be ensured. When the polyolefin resin having the MI value of 0.5 g / 10 min or more and 30 g / 10 min or less is used, the foamed cells are less likely to break, and polyolefin pre-foamed particles having a high expansion ratio tend to be obtained.
Here, the melting point is a temperature of 10 to 10 ° C./min from 40 ° C. to 220 ° C., and then cooled to 40 ° C. at a rate of 10 ° C./min with a differential scanning calorimeter. The peak temperature of the endothermic curve in the DSC curve obtained when the temperature is increased again to 220 ° C. at a rate of 10 ° C./min. The MI value is a value measured at a temperature of 230 ° C. and a load of 2.16 kg according to JIS K7210.
The hydroxyalkylethanolamine used in the present invention is a special cationic surfactant and is a substance represented by the following composition formula.
This hydroxyalkylethanolamine has the effect of increasing the water content of the polyolefin resin particles and providing polyolefin pre-expanded particles having a high expansion ratio. Although the amount of use is not particularly limited, usually, the upper limit of the amount of hydroxyalkylethanolamine used is preferably 5 parts by weight and more preferably 3 parts by weight with respect to 100 parts by weight of the polyolefin resin. The lower limit of the amount of hydroxyalkylethanolamine used is preferably 0.01 parts by weight, and more preferably 0.5 parts by weight. By adding 0.01 to 5 parts by weight of hydroxyalkylethanolamine, the production cost does not increase so much and the water-containing effect on the polyolefin resin particles is sufficient. Pre-expanded particles can be produced.
In the present invention, a compound having a triazine skeleton and a molecular weight per unit triazine skeleton of 300 or less (hereinafter sometimes referred to as “triazine compound”) is used. Here, the molecular weight per unit triazine skeleton is a value obtained by dividing the molecular weight by the number of triazine skeletons contained in one molecule. This triazine compound has an effect of increasing the water content of the polyolefin resin particles, giving polyolefin pre-expanded particles having a high expansion ratio, and suppressing variation in expansion ratio and cell diameter. When the molecular weight per unit triazine skeleton exceeds 300, the effect of increasing the water content, the variation of the expansion ratio, and the effect of suppressing the variation of the cell diameter are not sufficiently exhibited.
The hydroxyalkylethanolamine used in the present invention and the compound having a triazine skeleton and a molecular weight per unit triazine skeleton of 300 or less each have a water-containing effect, and can increase the expansion ratio of the polyolefin-based pre-expanded particles. By adding a hydroxyalkylethanolamine and a compound having a triazine skeleton to a polyolefin resin and having a molecular weight per unit triazine skeleton of 300 or less in combination, a water-containing effect more than the sum of the water-containing effects of both is seen, Polyolefin-based pre-expanded particles having a higher expansion ratio than the sum of both effects can be produced.
Examples of the compound having a triazine skeleton used in the present invention and having a molecular weight per unit triazine skeleton of 300 or less include melamine (chemical name: 1,3,5-triazine-2,4,6-triamine), ammelin (chemical) Name: 1,3,5-triazine-2-hydroxy-4,6-diamine), ammelide (chemical name: 1,3,5-triazine-2,4-hydroxy-6-amine), cyanuric acid (chemical name) : 1,3,5-triazine-2,4,6-triol), isocyanuric acid (chemical name: 1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione), acetoguanamine (Chemical name: 1,3,5-triazine-2,4-diamine-6-methyl), benzoguanamine (chemical name: 1,3,5-triazine-2,4-diamine-6-phenyl), tris ( Chill) isocyanurate, tris (ethyl) isocyanurate, tris (butyl) isocyanurate, tris (2-hydroxyethyl) isocyanurate, and the like melamine-isocyanuric acid condensate. These may be used alone or in combination of two or more. In particular, melamine, isocyanuric acid, and a melamine / isocyanuric acid condensate can be suitably used because of the high effect of increasing the moisture content, the effect of suppressing variation in foaming ratio, and variation in cell diameter.
Hereinafter, in the present invention, a compound having a triazine skeleton and having a molecular weight per unit triazine skeleton of 300 or less may be referred to as a triazine compound.
In order to obtain a more uniform and good cell structure, these triazine compounds usually have an average particle diameter of 0.1 to 800 μm, more preferably 1 to 100 μm, and the more uniform the particle diameter is. Further, in order to prevent caking, 0.1 to 1% by weight of metal soap such as magnesium stearate, barium stearate, calcium stearate may be blended.
Furthermore, it is more preferable that these triazine compounds exist as solid particles at the processing temperature when making the polyolefin resin composition. When it has a melting point, it preferably has a melting point of 180 ° C. or higher. When decomposing without having a melting point, a decomposition temperature of 230 ° C. or higher is preferable.
Although the usage-amount of these triazine compounds is not specifically limited, Usually, the upper limit of the usage-amount is 8 weight part with respect to 100 weight part of polyolefin resin, and 5 weight part is more preferable. On the other hand, the lower limit of the amount used is preferably 0.05 parts by weight and more preferably 0.08 parts by weight with respect to 100 parts by weight of the polyolefin resin. When used in an amount of 0.05 parts by weight or more and 8 parts by weight or less, the effect of increasing the water content, the effect of suppressing the variation in expansion ratio and the variation in cell diameter are further exhibited, and the cell diameter of the polyolefin-based pre-expanded particles is further reduced and broken. It is hard to foam and can exhibit better moldability.
The polyolefin resin particles used in the present invention preferably contain an inorganic filler from the standpoint that polyolefin pre-foamed particles having uniform foam and high expansion ratio can be obtained.
Specific examples of the inorganic filler include talc and calcium carbonate. Among these inorganic fillers, the use of talc is preferable from the viewpoint of providing polyolefin-based pre-expanded particles having a small ratio variation, uniform bubbles, and a relatively high expansion ratio.
The average particle diameter of the inorganic filler is not particularly limited, but it is possible to obtain polyolefin-based prefoamed particles having uniform bubbles, and molding having excellent mechanical strength and flexibility from the polyolefin-based prefoamed particles. From the viewpoint of obtaining a body, the upper limit of the average particle diameter of the inorganic filler is preferably 50 μm, and more preferably 10 μm. From the viewpoint of secondary aggregation and handling workability, the lower limit of the average particle diameter of the inorganic filler is preferably 0.1 μm, and more preferably 0.5 μm.
The amount used when the inorganic filler is used is not particularly limited, but is 0.001 part by weight or more with respect to 100 parts by weight of the polyolefin resin from the viewpoint of obtaining polyolefin-based prefoamed particles having a relatively high expansion ratio. It is preferable that when molding using polyolefin-based pre-expanded particles, excellent fusing property is exhibited, and a molded article having excellent mechanical strength and flexibility is obtained from the polyolefin-based pre-expanded particles. From 5 parts by weight, further preferably 2 parts by weight or less.
The polyolefin-based resin particles of the present invention are usually melted using an extruder, kneader, Banbury mixer (trademark), roll, etc., and desired particles such as cylindrical, elliptical columnar, spherical, cubic, rectangular parallelepiped, etc. In terms of shape, the weight of one of the particles is preferably processed into resin particles of 0.2 mg to 10 mg, more preferably 0.5 mg to 6 mg. At this time, a compound having a hydroxyalkylethanolamine and a triazine skeleton and a molecular weight per unit triazine skeleton of 300 or less is added, an inorganic filler is further added as necessary, and a colorant such as carbon black, an antistatic agent is added. By adding additives such as an agent, a flame retardant, an antioxidant and a weathering agent, polyolefin resin particles can be obtained.
The polyolefin-based pre-expanded particles in the present invention are prepared by dispersing the polyolefin-based resin particles in an aqueous dispersion medium in a sealed container and heating the polyolefin-based resin particles to a temperature equal to or higher than the softening temperature of the polyolefin-based resin particles. It is manufactured by a method in which it is increased by nitrogen or the like and then released into an atmosphere having a pressure lower than the internal pressure and foamed.
Furthermore, if a flow control plate that suppresses the spread when the contents of the sealed container are discharged is used, and the discharged material collides with the collision plate or the container wall at a collision angle of 5 degrees or more and 90 degrees or less, the variation in the expansion ratio is further reduced. It is preferable because small polyolefin-based pre-expanded particles can be obtained. The sealed container to be used is not particularly limited as long as it can withstand the pressure in the container and the temperature in the container at the time of producing the pre-foamed particles, and examples thereof include an autoclave type pressure resistant container.
The aqueous dispersion medium for dispersing the polyolefin-based resin particles may be any solvent that does not dissolve the polyolefin-based resin particles. Usually, water is preferable from the viewpoint of environment and economy. The amount of the aqueous dispersion medium used is as described above. In order to improve the dispersibility of the resin particles in water, it is usually preferably 100 parts by weight or more and 500 parts by weight or less with respect to 100 parts by weight of the polyolefin resin particles.
Examples of the dispersant include sparingly water-soluble inorganic compounds such as basic tribasic calcium phosphate, basic magnesium carbonate, and calcium carbonate. Among them, basic tribasic calcium phosphate is preferable for obtaining good dispersibility. Examples of the dispersion aid include anionic surfactants such as sodium dodecylbenzenesulfonate, sodium n-paraffin sulfonate, and sodium α-olefin sulfonate. Among them, n-paraffin sulfonic acid soda is preferably used. It is preferable for obtaining dispersibility. These dispersants are used in an amount of 0.2 parts by weight or more and 1 part by weight or less based on 100 parts by weight of the polyolefin resin particles in order to improve the dispersibility of the resin particles in the aqueous dispersion medium. It is preferable that it is 0.3 to 0.7 part by weight. The amount of the dispersion aid used is preferably 0.03 parts by weight or more and 0.15 parts by weight or less in order to improve the dispersibility of the resin particles in the aqueous dispersion medium. It is preferable to blend 0.05 parts by weight or more and 0.12 parts by weight or less.
In an airtight container, after charging the aqueous dispersion medium containing the polyolefin resin particles, the dispersant and the dispersion aid, the temperature is raised while stirring and the temperature is raised to a constant temperature equal to or higher than the softening temperature of the polyolefin resin particles. Further, the internal pressure in the sealed container is increased with nitrogen or air, and is held at a predetermined pressure, and then released into an atmosphere having a pressure lower than the internal pressure. At this time, it is preferable to discharge through a flow control plate having an opening of 2 to 10 mmφ.
The flow control plate is generally used for adjusting the discharge time and making the foaming ratio uniform. By using a squeezed plate with a cylinder attached to the orifice plate, the discharged water system The scattering angle of the dispersion can be reduced, and the polyolefin pre-foamed particles having a uniform size can be expanded to reduce the magnification variation. The orifice plate is a concept including an orifice type, a nozzle type, a venturi type, and the like, and these can be used in combination. However, the orifice type can maintain a constant outflow speed, and has a high magnification and a small variation in magnification. Pre-foamed particles can be obtained, which is preferable from the viewpoint of simple structure.
The cylinder attached to the orifice plate is integrally attached to the discharge side of the orifice. The material of the cylindrical body is not particularly limited. Generally, a metal is used and is integrated with the orifice plate. However, the integration method is not limited to welding, adhesion, or the like. Can be made as the same thing.
The opening area on the opposite side to which the cylinder is attached to the orifice plate cannot be generally described depending on the size and length of the cylinder, but in general, it is sufficient if it is 1.3 times or more the orifice opening area. . When the ratio is less than 1.3 times, the released polyolefin-based pre-expanded particles may be aggregated or clogged. If the length of the cylinder is short, the above problem does not occur, but the effect of the cylinder may not be obtained.
The impingement plate or container wall as used in the present invention is an apparatus installed to change the scattering direction of the polyolefin-based pre-expanded particles released from the discharge part. Usually, during pre-expansion, the softening temperature of the polyolefin-based pre-expanded particles When it becomes below, resin hardens and foaming ends. However, when the aqueous dispersion is collided with the collision plate or container wall as in the present invention, it is considered that the temperature and humidity of the foaming atmosphere become more uniform. In addition to reducing the variation in magnification, almost all of the water in the resin particles is instantaneously evaporated by impact and becomes an effective foaming agent, so that the magnification can be increased as compared with the case where no collision occurs.
The collision angle referred to in the present invention is an angle that makes 90 degrees when colliding with the collision plate or the container wall from the front, and makes 0 degree when it collides with the collision plate or the container wall and does not collide. It can take values between degrees and 90 degrees.
The collision angle is not particularly limited as long as the polyolefin pre-expanded particles can collide, but is preferably 5 degrees or more and 90 degrees or less, and more preferably 10 degrees or more and 45 degrees or less.
The atmosphere having a pressure lower than the internal pressure of the closed container may be a pressure lower than the internal pressure in the closed container, and a pressure in the vicinity of atmospheric pressure is usually selected. In addition, the atmosphere means a space including the scattering trajectory of the released aqueous dispersion (polyolefin-based pre-expanded particles and aqueous dispersion medium), but is generally blocked from the outside air by pipes or ducts. In the device. In order to further increase the expansion ratio, the low-pressure atmosphere is preferably maintained at a high temperature, and it is more preferable that the atmospheric temperature is 60 ° C. or higher because the expansion ratio is increased and the variation in magnification is reduced. In particular, it is preferably maintained at 90 ° C. or higher and 110 ° C. or lower with water vapor.
The polyolefin pre-expanded particles thus obtained preferably have two melting peaks in the DSC curve obtained by differential scanning calorimetry. Further, the difference between the two melting peak temperatures is preferably 10 ° C. or more. In the case of polyolefin-based pre-expanded particles having two melting peaks, an in-mold foam-molded article having good in-mold foam moldability and good mechanical strength and heat resistance is obtained.
Here, the DSC curve obtained by differential scanning calorimetry of polyolefin-based pre-expanded particles refers to 1-10 mg of polyolefin-based pre-expanded particles from 40 ° C. to 220 ° C. at a rate of temperature increase of 10 ° C./min with a differential scanning calorimeter. It is a DSC curve obtained when the temperature is raised.
As described above, the polyolefin-based pre-expanded particles having two melting peaks can be easily obtained by setting the temperature in the closed container at the time of pre-expansion to an appropriate value. Usually, the lower limit of the temperature in the closed container is preferably the softening point of the polyolefin resin that is the main component of the polyolefin resin particles, more preferably the melting point, more preferably the melting point + 5 ° C., and the upper limit. The melting point is preferably selected from the range of melting point + 20 ° C., more preferably melting point + 15 ° C.
The polyolefin-based pre-expanded particles obtained as described above can be formed into an in-mold expanded molded article by a conventionally known method. For example, a) a method in which polyolefin pre-foamed particles are pressurized with an inorganic gas, impregnated with inorganic gas in the particles to give a predetermined internal pressure, filled in a mold, and heat-sealed with steam or the like; B) A method of compressing polyolefin-based pre-expanded particles with gas pressure and filling them into a mold, and using the resilience of the particles to heat-fuse them with steam, etc. c) Filling the mold without any pretreatment A method such as heating and fusing with steam or the like can be used.
In addition, the polyolefin pre-expanded particles are pressurized with an inorganic gas, impregnated with inorganic gas in the particles to give a predetermined internal pressure, and then softened by heating with steam, etc., and polyolefin pre-expanded with a higher expansion ratio After the particles are produced (two-stage foaming method), an in-mold foam molded product may be used.
次に本発明を実施例及び比較例に基づき説明するが、本発明はこれら実施例に限定されるものではない。なお、以下の実施例及び比較例中の「低圧の発泡雰囲気」における「低圧」とは、大気圧付近の圧力をいう。 Next, although this invention is demonstrated based on an Example and a comparative example, this invention is not limited to these Examples. The “low pressure” in the “low pressure foaming atmosphere” in the following examples and comparative examples refers to a pressure near atmospheric pressure.
ポリオレフィン系樹脂としてエチレン−プロピレンランダム共重合体（融点：１４５℃、ＭＩ値：７ｇ／１０分）１００重量部を使用し、ヒドロキシアルキルエタノールアミンとして炭素数１０のアルキル基を含むヒドロキシアルキルエタノールアミンと、炭素数１２のアルキル基を含むヒドロキシアルキルエタノールアミンをそれぞれ５０重量％ずつ配合した混合物（商品名：ダスパー１２５Ｂ、ミヨシ油脂（株）製）を１重量部、及びトリアジン類化合物として単位トリアジン骨格あたりの分子量が１２６であるメラミン（商品名：メラミン、ＢＡＳＦ社製）を０．１重量部配合し５０ｍｍφ単軸押出し機で溶融混錬し、直径２．２ｍｍφの円筒ダイよりストランド状に押出し、水冷後、カッターで切断し１．８ｍｇ／粒の樹脂粒子を得た。
得られた樹脂粒子１００重量部、水２００重量部と、分散剤として塩基性第三リン酸カルシウム０．５重量部、分散助剤としてｎ−パラフィンスルフォン酸ソーダ０．１重量部をオートクレーブ中に仕込み、攪拌下、オートクレーブ内容物を１５５℃まで加熱した。その後オートクレーブ内圧を圧縮空気で３．０ＭＰａまで昇圧し、該容器内温度で３０分保持した後、オートクレーブ下部のバルブを開き、直径７．０ｍｍφ、長さ３０ｍｍの筒付き絞り盤を付けた３．６ｍｍφの開口オリフィスを通して、オートクレーブ内容物を低圧の発泡雰囲気を２５℃の空気として、容器壁に衝突角度０度（衝突させない）で放出してポリオレフィン系予備発泡粒子を得た。得られたポリオレフィン系予備発泡粒子の物性として、発泡倍率、倍率ばらつき、含水率を測定した。結果を表１に示す。100 parts by weight of an ethylene-propylene random copolymer (melting point: 145 ° C., MI value: 7 g / 10 min) is used as a polyolefin-based resin, and hydroxyalkylethanolamine containing an alkyl group having 10 carbon atoms as hydroxyalkylethanolamine; 1 part by weight of a mixture (trade name: Dasper 125B, manufactured by Miyoshi Oil & Fats Co., Ltd.) containing 50% by weight of hydroxyalkylethanolamine containing an alkyl group having 12 carbon atoms per unit triazine skeleton as a triazine compound Melamine with a molecular weight of 126 (trade name: Melamine, manufactured by BASF) was blended in 0.1 parts by weight, melted and kneaded with a 50 mmφ single screw extruder, extruded into a strand from a cylindrical die with a diameter of 2.2 mmφ, and water-cooled Then, it was cut with a cutter to obtain 1.8 mg / grain of resin particles. .
100 parts by weight of the obtained resin particles, 200 parts by weight of water, 0.5 parts by weight of basic tribasic calcium phosphate as a dispersant, and 0.1 parts by weight of sodium n-paraffin sulfonate as a dispersion aid were charged in an autoclave. Under stirring, the autoclave contents were heated to 155 ° C. Thereafter, the internal pressure of the autoclave was increased to 3.0 MPa with compressed air and maintained at the internal temperature for 30 minutes, and then the valve at the bottom of the autoclave was opened and a diaphragm with a cylinder having a diameter of 7.0 mmφ and a length of 30 mm was attached. Through the opening orifice of 6 mmφ, the autoclave contents were discharged at a collision angle of 0 ° (not to collide) with the low pressure foaming atmosphere at 25 ° C. air to obtain polyolefin-based prefoamed particles. As physical properties of the obtained polyolefin-based pre-expanded particles, expansion ratio, variation in magnification, and water content were measured. The results are shown in Table 1.
実施例１において、オートクレーブから内容物を放出させる際に、低圧の発泡雰囲気を１００℃の飽和水蒸気とし、容器壁に衝突角度２０度で衝突させながら放出してポリオレフィン系予備発泡粒子を得、物性測定を行った。結果を表１に示す。 In Example 1, when the contents were released from the autoclave, the low-pressure foaming atmosphere was saturated steam at 100 ° C., and released while colliding with the container wall at a collision angle of 20 ° to obtain polyolefin-based pre-expanded particles. Measurements were made. The results are shown in Table 1.
実施例１において、樹脂粒子を作製するにあたり、無機充填剤としてタルク（平均粒径：８μｍ）０．３重量部を配合して溶融混錬し、かつ、オートクレーブから内容物を放出させる際に、容器壁に衝突角度２０度で衝突させながら放出してポリオレフィン系予備発泡粒子を得、物性測定を行った。結果を表１に示す。 In Example 1, in preparing resin particles, 0.3 parts by weight of talc (average particle size: 8 μm) was blended and melt kneaded as an inorganic filler, and the contents were released from the autoclave. It was discharged while colliding with the container wall at a collision angle of 20 degrees to obtain polyolefin pre-expanded particles, and the physical properties were measured. The results are shown in Table 1.
実施例１において、無機充填剤としてタルク（平均粒径：８μｍ）０．３重量部を使用し、かつ、オートクレーブの内容物を放出する際の低圧の発泡雰囲気を１００℃の飽和水蒸気としてポリオレフィン系予備発泡粒子を得、物性測定を行った。結果を表１に示す。 In Example 1, 0.3 part by weight of talc (average particle size: 8 μm) was used as the inorganic filler, and the low-pressure foaming atmosphere when releasing the contents of the autoclave was used as a saturated steam at 100 ° C. Pre-expanded particles were obtained and measured for physical properties. The results are shown in Table 1.
実施例１において、無機充填剤としてタルク（平均粒径：８μｍ）０．３重量部を使用し、かつ、オートクレーブの内容物を放出する際の低圧の発泡雰囲気を１００℃の飽和水蒸気として、容器壁に衝突角度２０度で衝突させながら放出してポリオレフィン系予備発泡粒子を得た。
得られたポリオレフィン系予備発泡粒子の物性として、発泡倍率、倍率ばらつき、含水率を測定した。結果を表１に示す。In Example 1, 0.3 parts by weight of talc (average particle size: 8 μm) was used as the inorganic filler, and the low-pressure foaming atmosphere when releasing the contents of the autoclave was saturated steam at 100 ° C. It was discharged while colliding with the wall at an impact angle of 20 degrees to obtain polyolefin pre-expanded particles.
As physical properties of the obtained polyolefin-based pre-expanded particles, expansion ratio, variation in magnification, and water content were measured. The results are shown in Table 1.
実施例１において、トリアジン類化合物として単位トリアジン骨格あたりの分子量が１２６であるメラミン（商品名：メラミン、ＢＡＳＦ社製）を０．５重量部配合したこと以外は、実施例１と同様の方法によりポリオレフィン系予備発泡粒子を得、物性測定を行った。結果を表１に示す。 In Example 1, the same method as in Example 1 except that 0.5 part by weight of melamine (trade name: melamine, manufactured by BASF) having a molecular weight per unit triazine skeleton of 126 as a triazine compound was blended. Polyolefin pre-expanded particles were obtained and measured for physical properties. The results are shown in Table 1.
実施例１において、トリアジン類化合物として単位トリアジン骨格あたりの分子量が１２６であるメラミン（商品名：メラミン、ＢＡＳＦ社製）を０．５重量部配合したこと以外は、実施例５と同様の方法によりポリオレフィン系予備発泡粒子を得、物性測定を行った。結果を表１に示す。
（比較例１）
トリアジン類化合物を添加しないこと以外は、実施例１と同様の方法によりポリオレフィン系予備発泡粒子を得、物性測定を行った。結果を表１に示す。
（比較例２）
ヒドロキシアルキルエタノールアミンを添加しないこと以外は、実施例１と同様の方法によりポリオレフィン系予備発泡粒子を得、物性測定を行った。結果を表１に示す。
（比較例３）
ヒドロキシアルキルエタノールアミンを添加しないこと以外は、実施例６と同様の方法によりポリオレフィン系予備発泡粒子を得、物性測定を行った。結果を表１に示す。ポリオレフィン系予備発泡粒子の物性評価法を以下に示す。
ポリオレフィン系予備発泡粒子の物性評価法を以下に示す。
〔発泡倍率〕
ポリオレフィン系予備発泡粒子の重量測定後、１００ｍＬのメスシリンダー中でエタノールに浸漬した時の体積を測定して真の密度を求め、ポリオレフィン系樹脂組成物樹脂粒子の密度をポリオレフィン系予備発泡粒子の真の密度で除すことによって算出した。
〔倍率ばらつき〕
得られたポリオレフィン系予備発泡粒子０．３〜１ＬをＪＩＳ Ｚ８８０１標準篩（３．５、４、５、６、７、８、９、１０メッシュの８種）で篩い分けしたときの各篩に残ったポリオレフィン系予備発泡粒子の重量分率Ｗｉ、発泡倍率Ｋｉから加重平均倍率Ｋａｖ、倍率標準偏差σｍを
Ｋａｖ＝Σ（Ｋｉ×Ｗｉ）
σｍ＝√［Σ｛Ｗｉ×（Ｋａｖ−Ｋｉ）２｝］
により算出し、これらの値を用いて倍率ばらつきＶを
Ｖ（％）＝（σｍ／Ｋａｖ）×１００
により算出した。Ｖが小さいほど倍率ばらつきが小さいことを示す。
〔ポリオレフィン系予備発泡粒子の含水率〕
予備発泡直後のポリオレフィン系予備発泡粒子表面の水を空気気流で脱水した後、その重量（Ｗ１）を測定した。さらに、そのポリオレフィン系予備発泡粒子を８０℃のオーブン中で１２時間乾燥させたときの重量（Ｗ２）を測定し、
含水率（％）＝（Ｗ２−Ｗ１）／Ｗ２×１００
により算出した。
また、無機充填剤を添加した場合（実施例２と５を対比）、無機充填剤を添加した方が発泡倍率の向上、倍率ばらつきの低下が見られた。
また低圧の発泡雰囲気を６０℃以上の気体に接触させた場合（実施例３と５を対比）、或いは、容器壁に衝突させた場合（実施例４と５を対比）、低圧の雰囲気が６０℃以上である或いは容器壁に衝突させた方が、発泡倍率が大きくなり、倍率ばらつきが小さくなった。両者を併用した場合（実施例１と２）も然りである。
また、トリアジン骨格を有し単位トリアジン骨格あたりの分子量が３００以下の化合物を０．５重量部配合した場合についても、無機充填剤を添加し、低圧の発泡雰囲気を６０℃以上の気体に接触させ、容器壁に衝突させた方が、発泡倍率が大きくなり、倍率ばらつきが小さくなった（実施例６と７を対比）。
次に、オートクレーブ内の分散性の評価を行った。分散性の評価の指標として、オートクレーブ内で水系分散媒に分散させたポリオレフィン系樹脂粒子をポリオレフィン系樹脂粒子の軟化温度以上の温度に加熱したときに、オートクレーブ内が攪拌不可能となり予備発泡できなくなった状態を×、予備発泡できた場合について、予備発泡を行った後にオートクレーブ内に残ったポリオレフィン系樹脂粒子の状態を観察し、２個以上の樹脂粒子が接着した状態であれば分散性△、全ての樹脂粒子どうしが接着してない状態にあれば分散性良好で○とした。In Example 1, the same method as in Example 5 except that 0.5 part by weight of melamine (trade name: melamine, manufactured by BASF) having a molecular weight per unit triazine skeleton of 126 as a triazine compound was blended. Polyolefin pre-expanded particles were obtained and measured for physical properties. The results are shown in Table 1.
(Comparative Example 1)
Except not adding a triazine compound, polyolefin pre-expanded particles were obtained in the same manner as in Example 1 and measured for physical properties. The results are shown in Table 1.
(Comparative Example 2)
Except for not adding hydroxyalkylethanolamine, polyolefin pre-expanded particles were obtained in the same manner as in Example 1, and physical properties were measured. The results are shown in Table 1.
(Comparative Example 3)
Except for not adding hydroxyalkylethanolamine, polyolefin pre-expanded particles were obtained in the same manner as in Example 6 and measured for physical properties. The results are shown in Table 1. The physical property evaluation method of polyolefin pre-expanded particles is shown below.
The physical property evaluation method of polyolefin pre-expanded particles is shown below.
[Foaming ratio]
After measuring the weight of the polyolefin-based pre-expanded particles, the volume when immersed in ethanol in a 100 mL graduated cylinder is measured to determine the true density, and the density of the polyolefin-based resin composition resin particles is determined as the true density of the polyolefin-based pre-expanded particles. It was calculated by dividing by the density.
[Magnification variation]
For each sieve when 0.3 to 1 L of the polyolefin-based pre-expanded particles obtained were sieved with a JIS Z8801 standard sieve (8 types of 3.5, 4, 5, 6, 7, 8, 9, 10 mesh). The weighted average magnification Kav and magnification standard deviation σm are calculated from the weight fraction Wi and the expansion ratio Ki of the remaining polyolefin-based pre-expanded particles. Kav = Σ (Ki × Wi)
σm = √ [Σ {Wi × (Kav−Ki) 2 }]
Using these values, the magnification variation V is calculated as follows: V (%) = (σm / Kav) × 100
Calculated by A smaller V indicates a smaller variation in magnification.
[Moisture content of polyolefin pre-expanded particles]
Water on the surface of the polyolefin-based pre-foamed particles immediately after the pre-foaming was dehydrated with an air stream, and the weight (W1) was measured. Furthermore, the weight (W2) when the polyolefin-based pre-expanded particles were dried in an oven at 80 ° C. for 12 hours was measured,
Moisture content (%) = (W2-W1) / W2 × 100
Calculated by
In addition, when an inorganic filler was added (comparing Examples 2 and 5), the addition of the inorganic filler showed an improvement in the expansion ratio and a reduction in the variation in the magnification.
Further, when the low pressure foaming atmosphere is brought into contact with a gas of 60 ° C. or higher (comparing Examples 3 and 5) or when colliding with the container wall (Comparing Examples 4 and 5), the low pressure atmosphere is 60 The foaming magnification increased and the variation in magnification decreased when the temperature was higher than or equal to 0 ° C. or was made to collide with the container wall. The same is true when both are used together (Examples 1 and 2).
Also, in the case where 0.5 parts by weight of a compound having a triazine skeleton and a molecular weight per unit triazine skeleton of 300 parts by weight or less is added, an inorganic filler is added and a low-pressure foaming atmosphere is brought into contact with a gas of 60 ° C. or higher. The foaming magnification was increased and the variation in magnification was reduced by colliding with the container wall (compare Examples 6 and 7).
Next, the dispersibility in the autoclave was evaluated. As an index for evaluation of dispersibility, when polyolefin resin particles dispersed in an aqueous dispersion medium in an autoclave are heated to a temperature higher than the softening temperature of the polyolefin resin particles, the inside of the autoclave cannot be stirred and pre-foaming becomes impossible. X, the state of the polyolefin resin particles remaining in the autoclave after prefoaming was observed, and if two or more resin particles were adhered, dispersibility Δ, If all the resin particles are not adhered to each other, the dispersibility is good and the result is ◯.
オートクレーブ内に、塩基性第三リン酸カルシウム（分散剤）を０．２重量部、ｎ−パラフィンスルフォン酸ソーダ（分散助剤）を０．０６重量部仕込んだこと以外は、実施例５と同様の方法によりポリオレフィン系予備発泡粒子を得、オートクレーブ内の分散性の評価を行った。結果を表２に示す。 The same method as in Example 5 except that 0.2 parts by weight of basic tribasic calcium phosphate (dispersant) and 0.06 parts by weight of sodium n-paraffin sulfonate (dispersion aid) were charged in the autoclave. Thus, polyolefin pre-expanded particles were obtained, and the dispersibility in the autoclave was evaluated. The results are shown in Table 2.
オートクレーブ内に、塩基性第三リン酸カルシウム（分散剤）を０．５重量部、ｎ−パラフィンスルフォン酸ソーダ（分散助剤）を０．１２重量部仕込んだこと以外は、実施例５と同様の方法によりポリオレフィン系予備発泡粒子を得、実施例６と同様の方法によりオートクレーブ内の分散性の評価を行った。結果を表２に示す。 The same method as in Example 5 except that 0.5 parts by weight of basic tribasic calcium phosphate (dispersing agent) and 0.12 parts by weight of n-paraffin sulfonic acid soda (dispersing aid) were charged in the autoclave. Thus, polyolefin pre-expanded particles were obtained, and the dispersibility in the autoclave was evaluated in the same manner as in Example 6. The results are shown in Table 2.
オートクレーブ内に、塩基性第三リン酸カルシウム（分散剤）を０．５重量部、ｎ−パラフィンスルフォン酸ソーダ（分散助剤）を０．０２重量部仕込んだこと以外は、実施例５と同様の方法によりポリオレフィン系予備発泡粒子を得、実施例６と同等の方法によりオートクレーブ内の分散性の評価を行った。結果を表２に示す。 The same method as in Example 5 except that 0.5 parts by weight of basic tribasic calcium phosphate (dispersant) and 0.02 parts by weight of sodium n-paraffin sulfonate (dispersion aid) were charged in the autoclave. Then, polyolefin pre-expanded particles were obtained, and the dispersibility in the autoclave was evaluated by the same method as in Example 6. The results are shown in Table 2.
オートクレーブ内に、塩基性第三リン酸カルシウム（分散剤）を０．５重量部、ｎ−パラフィンスルフォン酸ソーダ（分散助剤）を０．１６重量部仕込んだこと以外は、実施例５と同様の方法によりポリオレフィン系予備発泡粒子を得、実施例６と同等の方法によりオートクレーブ内の分散性の評価を行った。結果を表２に示す。実施例８〜１１に示す配合量では、分散性は概ね良好であった。
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| JPH0812798A (en) * | 1994-06-28 | 1996-01-16 | Kanegafuchi Chem Ind Co Ltd | Pre-expanded polyolefin resin particles having antistatic property and method for producing the same |
| JPH10219019A (en) * | 1997-02-06 | 1998-08-18 | Kanegafuchi Chem Ind Co Ltd | Method for producing polypropylene resin pre-expanded particles having antistatic properties |
| JPH1192599A (en) * | 1997-09-25 | 1999-04-06 | Kanegafuchi Chem Ind Co Ltd | Polyolefin resin composition, pre-expanded particles comprising the same, and method for producing the same |
| JP2003171516A (en) * | 2001-09-28 | 2003-06-20 | Kanegafuchi Chem Ind Co Ltd | Expandable polypropylene-based resin composition and pre-expanded particles composed thereof |
| JP2003192820A (en) * | 2001-12-27 | 2003-07-09 | Kanegafuchi Chem Ind Co Ltd | Method for producing polyolefin-based pre-expanded particles and pre-expanded particles obtained by the method |
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| JPH0812798A (en) * | 1994-06-28 | 1996-01-16 | Kanegafuchi Chem Ind Co Ltd | Pre-expanded polyolefin resin particles having antistatic property and method for producing the same |
| JPH10219019A (en) * | 1997-02-06 | 1998-08-18 | Kanegafuchi Chem Ind Co Ltd | Method for producing polypropylene resin pre-expanded particles having antistatic properties |
| JPH1192599A (en) * | 1997-09-25 | 1999-04-06 | Kanegafuchi Chem Ind Co Ltd | Polyolefin resin composition, pre-expanded particles comprising the same, and method for producing the same |
| JP2003171516A (en) * | 2001-09-28 | 2003-06-20 | Kanegafuchi Chem Ind Co Ltd | Expandable polypropylene-based resin composition and pre-expanded particles composed thereof |
| JP2003192820A (en) * | 2001-12-27 | 2003-07-09 | Kanegafuchi Chem Ind Co Ltd | Method for producing polyolefin-based pre-expanded particles and pre-expanded particles obtained by the method |
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