JP3910906B2 - Emulsion composition for silicone rubber sponge and method for producing silicone rubber sponge - Google Patents
Emulsion composition for silicone rubber sponge and method for producing silicone rubber sponge Download PDFInfo
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- JP3910906B2 JP3910906B2 JP2002311470A JP2002311470A JP3910906B2 JP 3910906 B2 JP3910906 B2 JP 3910906B2 JP 2002311470 A JP2002311470 A JP 2002311470A JP 2002311470 A JP2002311470 A JP 2002311470A JP 3910906 B2 JP3910906 B2 JP 3910906B2
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- silicone rubber
- rubber sponge
- water
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- 229920002379 silicone rubber Polymers 0.000 title claims description 91
- 239000004945 silicone rubber Substances 0.000 title claims description 74
- 239000000203 mixture Substances 0.000 title claims description 47
- 239000000839 emulsion Substances 0.000 title claims description 42
- 238000004519 manufacturing process Methods 0.000 title claims description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 31
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 25
- 229920003169 water-soluble polymer Polymers 0.000 claims description 19
- 239000004944 Liquid Silicone Rubber Substances 0.000 claims description 17
- 229920001296 polysiloxane Polymers 0.000 claims description 15
- 238000007259 addition reaction Methods 0.000 claims description 13
- 239000003995 emulsifying agent Substances 0.000 claims description 12
- 229910052697 platinum Inorganic materials 0.000 claims description 12
- 125000003342 alkenyl group Chemical group 0.000 claims description 11
- 238000002156 mixing Methods 0.000 claims description 11
- 239000003054 catalyst Substances 0.000 claims description 10
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical group [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 8
- 229910052710 silicon Inorganic materials 0.000 claims description 8
- 239000010703 silicon Substances 0.000 claims description 8
- 229920005645 diorganopolysiloxane polymer Polymers 0.000 claims description 7
- 125000004435 hydrogen atom Chemical group [H]* 0.000 claims description 7
- 239000002736 nonionic surfactant Substances 0.000 claims description 6
- 229920000058 polyacrylate Polymers 0.000 claims description 4
- 159000000000 sodium salts Chemical class 0.000 claims description 4
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 claims description 3
- 229920000193 polymethacrylate Polymers 0.000 claims description 3
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 claims description 3
- -1 3,3,3-trifluoropropyl Chemical group 0.000 description 20
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 12
- 239000002253 acid Substances 0.000 description 9
- 239000004088 foaming agent Substances 0.000 description 6
- 229920000642 polymer Polymers 0.000 description 6
- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 5
- 229920006136 organohydrogenpolysiloxane Polymers 0.000 description 5
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 4
- 125000000217 alkyl group Chemical group 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 229920001971 elastomer Polymers 0.000 description 4
- 150000002148 esters Chemical class 0.000 description 4
- 239000000194 fatty acid Substances 0.000 description 4
- FFUAGWLWBBFQJT-UHFFFAOYSA-N hexamethyldisilazane Chemical compound C[Si](C)(C)N[Si](C)(C)C FFUAGWLWBBFQJT-UHFFFAOYSA-N 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 239000000377 silicon dioxide Substances 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 3
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 3
- DNIAPMSPPWPWGF-UHFFFAOYSA-N Propylene glycol Chemical compound CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 description 3
- 238000004132 cross linking Methods 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 239000002683 reaction inhibitor Substances 0.000 description 3
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 3
- JNYAEWCLZODPBN-JGWLITMVSA-N (2r,3r,4s)-2-[(1r)-1,2-dihydroxyethyl]oxolane-3,4-diol Chemical compound OC[C@@H](O)[C@H]1OC[C@H](O)[C@H]1O JNYAEWCLZODPBN-JGWLITMVSA-N 0.000 description 2
- OZAIFHULBGXAKX-UHFFFAOYSA-N 2-(2-cyanopropan-2-yldiazenyl)-2-methylpropanenitrile Chemical compound N#CC(C)(C)N=NC(C)(C)C#N OZAIFHULBGXAKX-UHFFFAOYSA-N 0.000 description 2
- 229910002012 Aerosil® Inorganic materials 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- 125000003118 aryl group Chemical group 0.000 description 2
- FSIJKGMIQTVTNP-UHFFFAOYSA-N bis(ethenyl)-methyl-trimethylsilyloxysilane Chemical compound C[Si](C)(C)O[Si](C)(C=C)C=C FSIJKGMIQTVTNP-UHFFFAOYSA-N 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000000748 compression moulding Methods 0.000 description 2
- LIKFHECYJZWXFJ-UHFFFAOYSA-N dimethyldichlorosilane Chemical compound C[Si](C)(Cl)Cl LIKFHECYJZWXFJ-UHFFFAOYSA-N 0.000 description 2
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 2
- 239000000945 filler Substances 0.000 description 2
- 230000008014 freezing Effects 0.000 description 2
- 238000007710 freezing Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000009775 high-speed stirring Methods 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- NNPPMTNAJDCUHE-UHFFFAOYSA-N isobutane Chemical compound CC(C)C NNPPMTNAJDCUHE-UHFFFAOYSA-N 0.000 description 2
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 2
- 125000000962 organic group Chemical group 0.000 description 2
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 2
- 229920001495 poly(sodium acrylate) polymer Polymers 0.000 description 2
- 229920001843 polymethylhydrosiloxane Polymers 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 125000001436 propyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])[H] 0.000 description 2
- 239000012763 reinforcing filler Substances 0.000 description 2
- NNMHYFLPFNGQFZ-UHFFFAOYSA-M sodium polyacrylate Chemical compound [Na+].[O-]C(=O)C=C NNMHYFLPFNGQFZ-UHFFFAOYSA-M 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 150000005846 sugar alcohols Polymers 0.000 description 2
- 238000010257 thawing Methods 0.000 description 2
- 125000003944 tolyl group Chemical group 0.000 description 2
- 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
- 125000003903 2-propenyl group Chemical group [H]C([*])([H])C([H])=C([H])[H] 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 description 1
- NKSOSPOXQKNIKJ-CLFAGFIQSA-N Polyoxyethylene dioleate Polymers CCCCCCCC\C=C/CCCCCCCC(=O)OCCOC(=O)CCCCCCC\C=C/CCCCCCCC NKSOSPOXQKNIKJ-CLFAGFIQSA-N 0.000 description 1
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 1
- 229920002125 Sokalan® Polymers 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 150000001336 alkenes Chemical class 0.000 description 1
- 150000005215 alkyl ethers Chemical class 0.000 description 1
- 125000005037 alkyl phenyl group Chemical group 0.000 description 1
- 229910000323 aluminium silicate Inorganic materials 0.000 description 1
- 239000001273 butane Substances 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000000084 colloidal system Substances 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000006482 condensation reaction Methods 0.000 description 1
- 239000003431 cross linking reagent Substances 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 235000014113 dietary fatty acids Nutrition 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004945 emulsification Methods 0.000 description 1
- RTZKZFJDLAIYFH-UHFFFAOYSA-N ether Substances CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 229930195729 fatty acid Natural products 0.000 description 1
- 239000003063 flame retardant Substances 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000005187 foaming Methods 0.000 description 1
- 239000003517 fume Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000003349 gelling agent Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- JEGUKCSWCFPDGT-UHFFFAOYSA-N h2o hydrate Chemical compound O.O JEGUKCSWCFPDGT-UHFFFAOYSA-N 0.000 description 1
- 238000007602 hot air drying Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000001746 injection moulding Methods 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 239000001282 iso-butane Substances 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 1
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 1
- OFBQJSOFQDEBGM-UHFFFAOYSA-N n-pentane Natural products CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 1
- HMMGMWAXVFQUOA-UHFFFAOYSA-N octamethylcyclotetrasiloxane Chemical compound C[Si]1(C)O[Si](C)(C)O[Si](C)(C)O[Si](C)(C)O1 HMMGMWAXVFQUOA-UHFFFAOYSA-N 0.000 description 1
- JRZJOMJEPLMPRA-UHFFFAOYSA-N olefin Natural products CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 description 1
- 150000003961 organosilicon compounds Chemical class 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 150000002941 palladium compounds Chemical class 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 239000004014 plasticizer Substances 0.000 description 1
- 239000004584 polyacrylic acid Substances 0.000 description 1
- 229940088417 precipitated calcium carbonate Drugs 0.000 description 1
- 125000004368 propenyl group Chemical group C(=CC)* 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 150000003284 rhodium compounds Chemical class 0.000 description 1
- 239000011734 sodium Chemical class 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000008399 tap water Substances 0.000 description 1
- 235000020679 tap water Nutrition 0.000 description 1
- 239000004408 titanium dioxide Substances 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
- 235000020681 well water Nutrition 0.000 description 1
- 239000002349 well water Substances 0.000 description 1
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- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明はシリコーンゴムスポンジ用エマルションとシリコーンゴムスポンジの製造方法に関する。
【０００２】
【従来の技術】
シリコーンスポンジゴムは、耐熱性、耐候性に優れ、軽量であることから、かかる特性を活かして、パッキング、ガスケット、Ｏリング等の自動車部品；複写機ロールの表面被覆材；各種シール材などとして使用されている。従来、かかるシリコーンゴムスポンジ形成性組成物としては、以下のとおり数多くの組成物が提案されている。
【０００３】
例えば、アゾビスイソブチロニトリルに代表される熱分解型発泡剤を配合してなるシリコーンゴムスポンジ用組成物が知られている（例えば、特許文献１、２参照）。オルガノポリシロキサン、乳化剤、水、粘欄剤からなるエマルションを発泡剤組成物としてシリコーンゴムに配合し、水の蒸発、膨張を利用して発泡させる組成物が提案されている（特許文献３参照）。また、殻がプラスチックで、ブタンやイソブタンのような揮発性物質が内包されたバルーン等を配合したシリコーンゴムスポンジ組成物が提案されている（特許文献４参照）。しかし、発泡時に熱分解型発泡剤が分解して発生するガスや水の蒸発、膨張した水蒸気を発泡剤としたり、また、熱膨張性のバルーンを発泡剤としたりしているために、単純形状の成形品には向いているものの、複雑な形状を有する成形品用途には不向きという問題点があり、その用途は限定されていた。
【０００４】
また、ヒドロキシ末端封鎖ジオルガノポリシロキサンと有機錫触媒からなる縮合反応硬化型のシリコーンエマルションを凍結して硬化し、解凍後に水を除去してシリコーンゴムスポンジを作製する方法が知られているが（特許文献５参照）、この方法では凍結、解凍に多くのエネルギーを必要とし、また成形体完成までに長時間を要し、生産性が悪いという問題点があった。さらに、アルケニル基含有ジオルガノポリシロキサンとオルガノハイドロジェンポリシロキサンとを白金系触媒の存在下にヒドロシリル化させる反応機構により、架橋してゴム状弾性体を得る際に、水を共存させて、該オルガノハイドロジェンポリシロキサンと水との反応で発生した水素ガスによってシリコーンゴムスポンジを形成される組成物（特許文献６参照）、あるいは水の代りに液状アルコールを用いた組成物（特許文献７参照）が提案されている。
【０００５】
さらには、アルケニル基含有ジオルガノポリシロキサンを、オルガノハイドロジェンポリシロキサンとの付加反応によって硬化させる系で、オルガノハイドロジェンポリシロキサンを過剰に用い、かつ水と1価または多価アルコールを用いるシリコーンゴムスポンジ組成物が知られている（特許文献８参照）。これら付加反応硬化型シリコーンゴムスポンジ組成物はいずれも硬化する際に、水素ガスならびに水を発泡剤とするものであり、圧縮成形やインジェクション成形においてはキャビティへの材料仕込み量によってセル構造が不均一になったり、金型の部品寸法と成形後の部品寸法が異なり寸法精度が悪くなったりするという問題点があった。しかもこれら特許文献には付加反応硬化型シリコーンエマルションからシリコーンゴムスポンジを作製するためのエマルション組成物およびエマルション組成物からシリコーンゴムスポンジを製造する方法は記載されていない。
【０００６】
また、付加反応硬化型シリコーンエマルション組成物からシリコーンゴムスポンジを作製するためのエマルション組成物およびシリコーンゴムスポンジを製造する方法が提案されており（特許文献９参照）、ここではエマルション安定化のために、ゲル化剤として吸水性ポリマーを使用しているのが特徴で、圧縮成形用途に好適で、成形品であるスポンジ成形体の寸法精度に優れるものの、セルの細かさやセルの均一性に欠けるという問題点があった。
【０００７】
【特許文献１】
特公昭４４−４６１号公報（特許請求の範囲）
【特許文献２】
特開平７−２４７４３６号公報（請求項１および［００１１］）
【特許文献３】
特公平７−１２２０００号公報（請求項１、［００６３］など）
【特許文献４】
特開平５−２０９０８０号公報（請求項１〜３）
【特許文献５】
特開昭５９−１２８３２号公報（特許請求の範囲）
【特許文献６】
特開昭５４−１３５８６５号公報（請求項１１）
【特許文献７】
特開平５−７０６９２号公報（請求項１、６など）
【特許文献８】
特開平１１−１３０９６３号公報（請求項１、２）
【特許文献９】
特開２００２−１１４８６０号公報（請求項１〜１１、［００１４］など）
【０００８】
【発明が解決しようとする課題】
本発明の目的は、付加反応硬化型シリコーンゴムスポンジ用エマルションを架橋硬化し、水を除去した後に均一かつ細かなセルを有し、しかも寸法精度のよいシリコーンゴムスポンジを得るためのシリコーンゴムスポンジ用エマルション組成物とシリコーンゴムスポンジの製造方法を提供することにある。
【０００９】
【課題を解決するための手段】
本発明者らは上記問題点を解消すべく研究した結果、本発明に到達した。すなわち、本発明は、以下のシリコーンゴムスポンジ用エマルションとシリコーンゴムスポンジの製造方法を提供するものである。
１）（Ａ）（ａ）１分子中に少なくとも２個のアルケニル基を有するジオルガノポリシロキサン、（ｂ）１分子中に少なくとも２個のケイ素原子結合水素を有するオルガノポリシロキサンおよび（ｃ）白金系触媒を含有してなる付加反応硬化型液状シリコーンゴム組成物、（Ｂ）水溶性ポリマーを含有する水、および（Ｃ）乳化剤を含有し、（Ｂ）成分の水溶性ポリマーが、ポリアクリレートあるいはポリメタクリレートのナトリウム塩、または、カルボキシメチルセルロースのナトリウム塩であり、（Ｃ）成分の乳化剤が、非イオン界面活性剤であり、
前記（Ａ）における（ａ）、（ｂ）および（ｃ）の合計量１００重量部に対し、前記（Ｂ）を５０〜２５０重量部、前記（Ｃ）を０．１〜１０重量部の割合で含むことを特徴とするシリコーンゴムスポンジ用エマルション組成物。
【００１０】
２）（Ｂ）成分中の水に対する水溶性ポリマーの配合量が０．１〜５重量％であることを特徴とする上記１）項記載のシリコーンゴムスポンジ用エマルション組成物。
３）上記１）または２）項に記載のシリコーンゴムスポンジ用エマルション組成物を硬化して湿潤のシリコーンゴムスポンジ様成形体を形成し、次いで前記成形体から水を除去してシリコーンゴムスポンジとなすことを特徴とするシリコーンゴムスポンジの製造方法。
【００１１】
４）硬化する前のシリコーンゴムスポンジ用エマルション組成物が気泡を含まないことを特徴とする上記３）項記載のシリコーンゴムスポンジの製造方法。
【００１２】
【発明の実施の形態】
本発明に使用される(Ａ)成分の付加反応硬化型液状シリコーンゴム組成物は、常温にて液状を呈し、硬化してゴム状弾性を有するシリコーンゴムであり、かかる液状シリコーンゴム組成物としては、アルケニル基含有ジオルガノポリシロキサンとケイ素原子結合水素原子含有オルガノハイドロジェンポリシロキサンとからなり、白金系触媒により硬化してシリコーンゴムとなる付加反応硬化型液状シリコーンゴム組成物である。
【００１３】
かかる付加反応硬化型液状シリコーンゴム組成物としては、具体的には、(a)1分子中に少なくとも２個のアルケニル基を有するジオルガノポリシロキサン、(b)1分子中に少なくとも２個のケイ素原子結合水素原子を有するオルガノポリシロキサンおよび(c)白金系触媒からなる液状シリコーンゴム組成物である。
この組成物について説明する。まず、(a)成分のオルガノポリシロキサンは1分子中に少なくとも２個のケイ素原子結合アルケニル基を有しており、アルケニル基としてはビニル基、アリル基、プロぺニル基などが例示される。また、アルケニル基以外の有機基としては、メチル基、エチル基、プロピル基などのアルキル基;フェニル基、トリル基などのアリール基；３，３，３−トリフロロプロピル基、３−クロロプロピル基などのハロゲン化アルキル基などが挙げられる。本成分の分子構造は直鎖状、分枝を含む直鎖状のいずれであってもよい。本成分の分子量は特に限定されないが、２５℃における粘度が１００ｍＰａ・ｓ以上、１００，０００ｍＰａ・ｓ以下であることが好ましい。本発明においては上記オルガノポリシロキサンを２種以上組み合わせてもよい。
【００１４】
次に、(b)成分のオルガノポリシロキサンは架橋剤であり、(c)成分の白金系触媒の存在下に本成分のケイ素原子結合水素原子が、(a)成分中のオルガノポリシロキサンのケイ素原子結合アルケニル基に付加反応して架橋、硬化させるものである。本成分は1分子中に少なくとも２個、好ましくは３個以上のケイ素原子結合水素原子を有することが必要である。(b)成分中のケイ素原子結合有機基としては、メチル基、エチル基、プロピル基などのアルキル基；フェニル基、トリル基などのアリール基；３，３，３−トリフロロプロピル基、３−クロロプロピル基などのハロゲン化アルキル基などが挙げられる。本成分も分子構造は、直鎖状、分枝状、環状、網目状のいずれでもよい。本成分の分子量は特に限定されないが、２５℃における粘度が３〜１０，０００ｍＰａ・ｓであることが好ましい。
【００１５】
（Ａ）成分中の配合量は、（ｂ）成分中のケイ素原子結合水素原子と(a)成分中のケイ素原子結合アルケニル基のモル比が(０．５：１)〜(５０：１)となるような量であり、これは、このモル比が０．５より小さいと良好な硬化性が得られず、５０より大きいと硬化物であるシリコーンゴムスポンジの硬度が高くなり過ぎるからである。また、(c)成分の白金系触媒は付加反応により硬化させるための触媒であり、例えば、白金微粉末、白金黒、塩化白金酸、塩化白金酸のオレフイン錯体、塩化白金酸のアルケニルシロキサンとの錯化合物、ロジウム化合物、パラジウム化合物が例示される。これらは、触媒としての適当量を用いる。
【００１６】
この液状シリコーンゴム組成物には、流動性を調節したり、硬化物の機械強度を向上させるために各種の充填剤を配合してもよく、このような充填剤としては、沈降シリカ、ヒュームドシリカ、カーボンブラック、焼成シリカ、コロイド状炭酸カルシウム、ヒユームド二酸化チタンなどの補強性充填剤；石英粉末、珪素土、アルミノケイ酸、酸化マグネシウム、沈降法炭酸カルシウムなどの非補強性充填剤；これらの充填剤をジメチルジクロロシラン、へキサメチルジシラザン、オクタメチルシクロテトラシロキサンなどの有機ケイ素化合物で疎水化処理したものが挙げられる。さらに、必要に応じてアルコール類、顔料、付加反応抑制剤、耐熱剤、難燃剤、可塑剤、接着性付与剤などを配合してもよい。
【００１７】
本発明に使用される（Ｂ）成分中の水は、シリコーンゴムスポンジ用エマルションの作製に必要な成分であり、清浄であればよく、その種類は制限されない。水道水、井戸水、イオン交換水、蒸留水が例示される。（Ｂ）成分の配合量は、（Ａ）成分における（ａ）、（ｂ）および（ｃ）の合計量１００重量部当たり５０〜２５０重量部であり、好ましくは７０〜２００重量部である。５０重量部より少ないと形成されるシリコーンゴムスポンジの発泡倍率が小さく、２５０重量部を超えると、形成されるシリコーンゴムスポンジの強度が損なわれるからである。（Ｂ）成分中に含有する水溶性ポリマーは、水に溶解した際の水性物の粘性が高く、低乳化剤量で安定なエマルションを調製するために配合される。その水に対する配合量は０．１〜５重量％、好ましくは０．５〜３重量％である。その量が０．１重量％より低いときは水溶性ポリマーが溶解した水性物の粘性が低く、安定なエマルションが得難く、５重量％を超えるときは粘性が高過ぎてエマルションからの脱気が困難となり、いずれも好ましくない。
【００１８】
（Ｂ）成分中の水溶性ポリマーとしては、カルボキシメチルセルロースのナトリウム塩、ポリアクリレートあるいはポリメタクリレートのナトリウム塩が使用される。
【００１９】
本発明に使用される（Ｃ）成分の乳化剤は、安定なエマルションを形成するために配合され、非イオン性の乳化剤が使用される。非イオン性の乳化剤としての非イオン界面活性剤は、ポリオキシエチレンアルキルエーテル、ポリオキシエチレンアルキルフェニールエーテル、エチレングリコールモノ脂肪酸エステル、プロピレングリコールモノ脂肪酸エステル、ソルビタンモノ脂肪酸エステル、ソルビタントリ脂肪酸エステル、ポリオキシエチレンソルビタントリ脂肪酸エステル、ポリオキシエチレンモノ脂肪酸エステル、ポリオキシエチレンジ脂肪酸エステル、ポリオキシエチレンプロピレングリコール脂肪酸エステルあるいはＰＯＥ多価アルコール類などが例示され、１種または２種以上を併用してもよい。用いる乳化剤のＨＬＢ値は６〜１４のものが好ましく、２種以上併用することがより好ましい。（Ｃ）成分の配合量は、（Ｂ）成分の粘性により大幅に減量が可能で、（Ａ）成分における（ａ）、（ｂ）および（ｃ）の合計量１００重量部に対して０．１〜１０重量部、好ましくは０．５〜７重量部である。０．１重量部より少ないと安定なシリコーンゴムスポンジ用エマルションとはなり難く、１０重量部を超えるとシリコーンゴムスポンジの耐熱後の物理特性が著しく低下するので、いずれも好ましくない。
【００２０】
かかる(Ａ)成分、(Ｂ)成分、(Ｃ)成分から成るシリコーンゴムスポンジ用エマルションは、例えば次のような方法で製造することができる。所定量の(Ａ)液状シリコーンゴム組成物と所定量の(Ｂ)水溶性ポリマーを含有する水と所定量の(Ｃ)乳化剤を高速攪拌ミキサーに投入し、所定時間攪拌混合するか、あるいは(Ａ)成分中の(a)成分、(Ｂ)水溶性高分子を含有する水、(Ｃ)乳化剤の各所定量を高速攪拌ミキサーに投入し、所定時間攪拌混合した後に、所定量の(Ａ)成分中の(ｂ)成分、(c)成分を攪拌混合してもよい。ここで使用するミキサーとしてはホモミキサー、パドルミキサー、へンシェルミキサー、ホモデイスパー、コロイドミキサー、真空混合攪拌ミキサーあるいは２軸押出機等が例示されるが、安定なエマルションが得られるものであれば、特に限定されない。
【００２１】
かかるシリコーンゴムスポンジ用エマルションが、混合時に気泡を巻き込んでいる時は脱気後、例えば、圧縮成形金型で、常温〜１２０℃、好ましくは５０〜１００℃の温度で硬化して湿潤状態のシリコーンゴムスポンジ様成形体を形成させ、次に１５０〜２５０℃の２次加熱処理で湿潤状態のシリコーンゴムスポンジ成形体から水を除去することにより、セルが均一でしかも細かく、寸法精度のよいシリコーンゴムスポンジを得ることができる。また、シリコーンゴム用エマルションをロッド状にノズルから押出して、例えば８０〜１００℃の熱水中で硬化させ、それを熱風乾燥して紐状のシリコーンゴムスポンジを作製することもできる。
【００２２】
【実施例】
以下、本発明を実施例、比較例により詳細に説明する。以下の記載において、部とあるのは重量部を、％とあるのは重量％をそれぞれ意味し、また粘度は２５℃での値を示す。シリコーンゴムスポンジ用エマルションならびにシリコーンゴムスポンジの各特性は下記の条件で測定した。
・乳化状態； 所定の時間攪拌混合後、目視により外観で乳化の状態を判定した。
・スポンジの密度； シリコーンゴムスポンジ用エマルションをシート状に成形硬化した後に熱風乾燥し、得られた成形シートを一定直径のポンチで打ち抜き、その打ち抜いたゴム片の重量と厚みを測定し、重量／体積(ｇ／ｃｍ3)を密度として算出した。
・寸法精度； 熱風乾燥後の成形シート厚さ(ｍｍ)を熱風乾燥前の硬化成形シート厚さ(ｍｍ)で割った寸法比を寸法精度として算出した。
・セル径； 拡大鏡により観察した。
【００２３】
実施例１〜３
分子鎖両末端がジメチルビニルシロキシ基で封鎖された粘度１０，０００ｍＰａ・ｓのジメチルポリシロキサン(ビニル基含有量０．１４％)［（ａ）成分］１００部、比表面積２００ｍ2／ｇのヒュームドシリカ２０部、シリカ処理剤としてヘキサメチルジシラザン５部、水1部を加えて混合機で均一に混合し、１８０℃、減圧下で２時間熱処理を行い、流動性のある液状シリコーンゴムベースを調製した。このべース１００部に、両末端トリメチルシロキシ基封鎖ジメチルシロキサン／メチルハイドロジェンシロキサン共重合体(ケイ素原子結合水素含有量０．８％)［（ｂ）成分］０．５部と塩化白金酸とジビニルテトラメチルジシロキサンとの白金錯体［（ｃ）成分］０．１部(白金濃度０．４％)と反応抑止剤として３，５−ジメチル−1−へキシル−３オール０．１部を加えて均一に混合して液状シリコーンゴム組成物を得た。この液状シリコーンゴム組成物に水溶性ポリマーであるポリアクリル酸ソーダを含有する水(水溶性ポリマー含有量１．０％)、非イオン界面活性剤としてＨＬＢ値６．６のポリオキシエチレンジラウレート、ＨＬＢ値１０．４のポリオキシエチレンジオレエートを表1に示す配合比［前記液状シリコーンゴム組成物中の（ａ）、（ｂ）および（ｃ）成分の合計量１００部に対する配合比］で、市販のアビテックスミキサー((株)マツバラ社製)に投入し、回転数９０００ｒｐｍで１０分間混合して、それぞれシリコーンゴムスポンジ用エマルションを調製した。
【００２４】
次に、これら気泡混入のシリコーンゴムスポンジ用エマルションから気泡を除くため真空ポンプで脱気した後に、厚さ２ｍｍのシート状金型に流し込み、９０℃、１０分間かけて硬化し、湿潤状態のシリコーンゴムスポンジ様成形シートを得た。これら成形シートを１５０℃の熱風式オーブンに入れ、1時間かけて熱風乾燥し、それぞれシート状のシリコーンゴムスポンジを得た。その密度、寸法精度およびセル径を測定し、表1に示した。この結果から、本発明によるシリコーンゴムスポンジはセルの均一性もよく、寸法精度に優れるものであった。
【００２５】
比較例１〜２
水溶性ポリマーを含まない以外はすべて実施例１、２の手順に従い、表1の配合比でシリコーンゴムスポンジ用エマルションの調製を行ったが、安定なエマルションが作製できず、湿潤状態のシリコーンゴムスポンジ様成形体を得ることができなかった。
比較例３
実施例１〜３の液状シリコーンゴム組成物１００部、吸水性ポリマー(三洋化成工業社製のアクリル酸塩重合体部分ナトリウム塩架橋物)を含有する水(吸水性ポリマー２．０％)１２０部、ポリオキシエチレンジラウレート７部を加えて混合し、シリコーンゴムスポンジ用エマルションを調製し、実施例1〜３の方法で硬化、熱風乾燥し、シリコーンゴムスポンジを作製した結果を表1に示した。
【００２６】
【表１】
実施例４
分子鎖両末端がジメチルビニルシロキシ基で封鎖された粘度４０，０００ｍＰａ・ｓのメチルビニルポリシロキサンポリマー(ビニル基含有量０．１４％)［（ａ）成分］１００部に、ジメチルジクロロシランで表面処理したアエロジルＲ−９７２(日本アエロジル社製)２０部を加えて均一に混合し、１８０℃で２時間熱処理を行って、流動性のある液状シリコーンベースを調製した。このべース１００部に、両末端トリメチルシロキシ基封鎖ジメチルシロキサン／メチルハイドロジェンシロキサン共重合体(ケイ素原子結合水素含有量０．８％)［（ｂ）成分］０．５部と塩化白金酸とジビニルテトラメチルジシロキサンとの白金錯体［（ｃ）成分］０．１部(白金濃度０．４％)と反応抑止剤として３，５−ジメチル−1−へキシル−３オール０．１部を加えて均一に混合して液状シリコーンゴム組成物を得た。この液状シリコーンゴム組成物に前記の（ａ）、（ｂ）および（ｃ）の合計量１００部に対する配合比として、水溶性ポリマーであるポリアクリル酸ソーダを含有する水(水溶性ポリマー含有量２％)１２０部、高級アルコール系非イオン界面活性剤としてＨＬＢ１０．５のサンノニツクＳＳ−５０(三洋化成工業社製)２．５部、ＨＬＢ１２．８のサンノニックＳＳ−７０(三洋化成工業社製)２．５部を容器に計量し、Ｔ．Ｋ．ホモミクサーＭＡＲＫII２．５型(特殊機化工業社製)を使用して、回転数５０００ｒｐｍで５分間かけて混合し、シリコーンゴムスポンジ用エマルションを調製した。
【００２８】
このシリコーンゴムスポンジ用エマルションを真空ポンプで脱気した後に、厚さ２ｍｍのシート状金型に流し込み、９０℃で１５分かけて硬化し、湿潤状態のシリコーンゴムスポンジ様成形シートを得た。これら成形シートを実施例1と同様な方法で熱風乾燥し、シリコーンゴムスポンジを得た。その密度、寸法精度およびセル径を測定した。その結果、密度は０．５９、寸法精度は０．９８、セル径は０．０５〜０．１ｍｍであった。
【００２９】
比較例４
実施例４において、水溶性ポリマーの替わりに吸水性ポリマーとしてアクリル酸塩重合体部分ナトリウム塩架橋物でゲル化させた水（吸水性ポリマー含有量０．３％）１２０部を使用する以外は全て実施例４と同条件で実施した結果、密度は０．５８、寸法精度は０．９８、セル径は０．２〜１．０ｍｍであった。
実施例５
沈降シリカ系の液状シリコーンゴム組成物ＤＹ３５−７００Ａ／Ｂ（東レ・ダウコーニング・シリコーン社製）１００部に、水溶性ポリマーとしてポリアクリル酸ソーダを含有する水（水溶性ポリマー含有量２％）１２０部、高級アルコール系非イオン界面活性剤としてサンノニックＳＳ−５０ ２．５部、サンノニックＳＳ−７０ ２．５部を容器に計量し、Ｔ．Ｋ．ホモミクサーを使用し、回転数５０００ｒｐｍで５分間かけて混合し、シリコーンゴム用エマルションを調製した後、実施例４と同様な方法で、脱気、硬化、熱風乾燥し、シリコーンゴムスポンジを得た。測定の結果、寸法精度は０．９９、セル径は０．１ｍｍ以下であった。
【００３０】
【発明の効果】
本発明のシリコーンゴムスポンジ用エマルション組成物は(Ａ)成分〜(Ｃ)成分を含み、エマルションの状態で硬化して、湿潤状態のシリコーンゴムスポンジ様成形体を形成できるという特徴を有する。また本発明のシリコーンゴムスポンジの製造方法は湿潤状態のシリコーンゴムスポンジ様成形体を熱風乾燥してシリコーンゴムスポンジとなるので、金型形状の追従性も良く、かつ寸法精度も良好で、セルの均一性に優れ、しかもセルの細かいシリコーンゴムスポンジを効率よく製造できるという特徴を有する。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an emulsion for a silicone rubber sponge and a method for producing a silicone rubber sponge.
[0002]
[Prior art]
Silicone sponge rubber is excellent in heat resistance and weather resistance, and is lightweight, so it can be used as an automotive part such as packing, gasket and O-ring; surface coating material for copier rolls; Has been. Conventionally, as the silicone rubber sponge-forming composition, many compositions have been proposed as follows.
[0003]
For example, a composition for a silicone rubber sponge formed by blending a pyrolytic foaming agent typified by azobisisobutyronitrile is known (see, for example, Patent Documents 1 and 2). There has been proposed a composition in which an emulsion composed of an organopolysiloxane, an emulsifier, water, and an adhesive is blended with silicone rubber as a foaming agent composition and foamed by utilizing evaporation and expansion of water (see Patent Document 3). . In addition, a silicone rubber sponge composition has been proposed in which a balloon is incorporated with a plastic shell and a volatile substance such as butane or isobutane (see Patent Document 4). However, since the pyrolytic foaming agent decomposes during foaming, the gas and water are evaporated, the expanded water vapor is used as the foaming agent, and the thermally expandable balloon is used as the foaming agent. However, it has a problem that it is not suitable for a molded product having a complicated shape, and its use is limited.
[0004]
Further, there is known a method for producing a silicone rubber sponge by freezing and curing a condensation reaction curing type silicone emulsion comprising a hydroxy-end-capped diorganopolysiloxane and an organotin catalyst, and removing water after thawing ( In this method, there is a problem that a lot of energy is required for freezing and thawing, and it takes a long time to complete a molded body, resulting in poor productivity. Furthermore, when a rubbery elastic body is obtained by crosslinking by a reaction mechanism in which an alkenyl group-containing diorganopolysiloxane and an organohydrogenpolysiloxane are hydrosilylated in the presence of a platinum-based catalyst, A composition in which a silicone rubber sponge is formed by hydrogen gas generated by a reaction between an organohydrogenpolysiloxane and water (see Patent Document 6), or a composition using liquid alcohol instead of water (see Patent Document 7) Has been proposed.
[0005]
Further, a silicone rubber using a system in which an alkenyl group-containing diorganopolysiloxane is cured by an addition reaction with an organohydrogenpolysiloxane, an excess of the organohydrogenpolysiloxane, and water and a monovalent or polyhydric alcohol. A sponge composition is known (see Patent Document 8). These addition reaction curable silicone rubber sponge compositions use hydrogen gas and water as foaming agents when they are cured, and in compression molding and injection molding, the cell structure is uneven depending on the amount of material charged into the cavity. There is a problem that the dimensional accuracy is deteriorated due to the difference in the part dimension of the mold and the part dimension after molding. Moreover, these patent documents do not describe an emulsion composition for producing a silicone rubber sponge from an addition reaction curable silicone emulsion and a method for producing a silicone rubber sponge from the emulsion composition.
[0006]
In addition, an emulsion composition for producing a silicone rubber sponge from an addition reaction curable silicone emulsion composition and a method for producing a silicone rubber sponge have been proposed (see Patent Document 9). It is characterized by the use of a water-absorbing polymer as a gelling agent, which is suitable for compression molding applications and has excellent dimensional accuracy of a sponge molded product, but lacks cell fineness and cell uniformity. There was a problem.
[0007]
[Patent Document 1]
Japanese Patent Publication No. 44-461 (Claims)
[Patent Document 2]
JP-A-7-247436 (Claims 1 and [0011])
[Patent Document 3]
Japanese Patent Publication No. 7-122000 (Claim 1, [0063], etc.)
[Patent Document 4]
JP-A-5-209080 (Claims 1 to 3)
[Patent Document 5]
JP 59-12832 A (Claims)
[Patent Document 6]
JP 54-135865 A (Claim 11)
[Patent Document 7]
JP-A-5-70692 (Claims 1, 6 etc.)
[Patent Document 8]
JP-A-11-130963 (Claims 1, 2)
[Patent Document 9]
JP 2002-114860 A (Claims 1-11, [0014], etc.)
[0008]
[Problems to be solved by the invention]
An object of the present invention is for a silicone rubber sponge for obtaining a silicone rubber sponge having uniform and fine cells and having good dimensional accuracy after crosslinking and curing an emulsion for addition reaction curing type silicone rubber sponge and removing water. An object of the present invention is to provide a method for producing an emulsion composition and a silicone rubber sponge.
[0009]
[Means for Solving the Problems]
The inventors of the present invention have arrived at the present invention as a result of studies to solve the above problems. That is, the present invention provides the following emulsion for a silicone rubber sponge and a method for producing the silicone rubber sponge.
1) (A) ( a) a diorganopolysiloxane having at least two alkenyl groups in one molecule, (b) an organopolysiloxane having at least two silicon atom-bonded hydrogens in one molecule, and (c) platinum An addition reaction curable liquid silicone rubber composition comprising a system catalyst, ( B) water containing a water-soluble polymer, and (C) an emulsifier, and the water-soluble polymer of component (B) is polyacrylate or A sodium salt of polymethacrylate or a sodium salt of carboxymethylcellulose, and the emulsifier of component (C) is a nonionic surfactant,
The ratio of (B) to 50 to 250 parts by weight and (C) to 0.1 to 10 parts by weight with respect to 100 parts by weight of the total amount of (a), (b) and (c) in (A). An emulsion composition for a silicone rubber sponge, comprising:
[0010]
2) The emulsion composition for a silicone rubber sponge as described in 1) above, wherein the amount of the water-soluble polymer based on water in the component (B) is 0.1 to 5% by weight .
3 ) The emulsion composition for a silicone rubber sponge described in the above 1) or 2) is cured to form a wet silicone rubber sponge-like molded product, and then water is removed from the molded product to obtain a silicone rubber sponge. A method for producing a silicone rubber sponge.
[0011]
4 ) The method for producing a silicone rubber sponge as described in 3 ) above, wherein the emulsion composition for a silicone rubber sponge before curing does not contain bubbles.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The addition reaction curable liquid silicone rubber composition of component (A) used in the present invention is a silicone rubber that exhibits a liquid state at room temperature and is cured to have rubber-like elasticity. As such a liquid silicone rubber composition, An addition reaction curable liquid silicone rubber composition comprising an alkenyl group-containing diorganopolysiloxane and a silicon-bonded hydrogen atom-containing organohydrogenpolysiloxane, which is cured with a platinum catalyst to form a silicone rubber.
[0013]
Specifically, the addition reaction curable liquid silicone rubber composition includes (a) a diorganopolysiloxane having at least two alkenyl groups in one molecule, and (b) at least two silicons in one molecule. A liquid silicone rubber composition comprising an organopolysiloxane having atom-bonded hydrogen atoms and (c) a platinum-based catalyst.
This composition will be described. First, the organopolysiloxane of component (a) has at least two silicon atom-bonded alkenyl groups in one molecule, and examples of the alkenyl group include a vinyl group, an allyl group, and a propenyl group. Examples of organic groups other than alkenyl groups include alkyl groups such as methyl, ethyl and propyl; aryl groups such as phenyl and tolyl groups; 3,3,3-trifluoropropyl and 3-chloropropyl And halogenated alkyl groups. The molecular structure of this component may be either linear or branched. The molecular weight of this component is not particularly limited, but the viscosity at 25 ° C. is preferably 100 mPa · s or more and 100,000 mPa · s or less. In the present invention, two or more of the above organopolysiloxanes may be combined.
[0014]
Next, the organopolysiloxane of component (b) is a cross-linking agent, and the silicon atom-bonded hydrogen atom of this component in the presence of the platinum-based catalyst of component (c) becomes the silicon of the organopolysiloxane in component (a). An addition reaction to an atomic bond alkenyl group causes crosslinking and curing. This component needs to have at least 2, preferably 3 or more silicon-bonded hydrogen atoms in one molecule. Examples of the silicon-bonded organic group in component (b) include alkyl groups such as methyl group, ethyl group, and propyl group; aryl groups such as phenyl group and tolyl group; 3,3,3-trifluoropropyl group, 3- And halogenated alkyl groups such as chloropropyl group. The molecular structure of this component may be linear, branched, cyclic, or network. The molecular weight of this component is not particularly limited, but the viscosity at 25 ° C. is preferably 3 to 10,000 mPa · s.
[0015]
The blending amount in component (A) is such that the molar ratio of silicon atom-bonded hydrogen atoms in component (b) to silicon atom-bonded alkenyl groups in component (a) is (0.5: 1) to (50: 1). This is because when this molar ratio is less than 0.5, good curability cannot be obtained, and when it is greater than 50, the hardness of the cured silicone rubber sponge is too high. . In addition, the platinum-based catalyst of component (c) is a catalyst for curing by addition reaction. For example, platinum fine powder, platinum black, chloroplatinic acid, chloroplatinic acid olefin complex, chloroplatinic acid alkenylsiloxane and Examples include complex compounds, rhodium compounds, and palladium compounds. These are used in an appropriate amount as a catalyst.
[0016]
This liquid silicone rubber composition may be blended with various fillers in order to adjust the fluidity and improve the mechanical strength of the cured product. Examples of such fillers include precipitated silica, fumed Reinforcing fillers such as silica, carbon black, calcined silica, colloidal calcium carbonate, fumed titanium dioxide; non-reinforcing fillers such as quartz powder, silicon earth, aluminosilicate, magnesium oxide, precipitated calcium carbonate; The agent may be hydrophobized with an organosilicon compound such as dimethyldichlorosilane, hexamethyldisilazane, and octamethylcyclotetrasiloxane. Furthermore, you may mix | blend alcohols, a pigment, an addition reaction inhibitor, a heat-resistant agent, a flame retardant, a plasticizer, an adhesive imparting agent, etc. as needed.
[0017]
The water in the component (B) used in the present invention is a component necessary for preparing an emulsion for a silicone rubber sponge and may be clean, and the type thereof is not limited. Examples are tap water, well water, ion exchange water, and distilled water. The amount of component (B) is 50 to 250 parts by weight, preferably 70 to 200 parts by weight, per 100 parts by weight of the total amount of (a), (b) and (c) in component (A). This is because if the amount is less than 50 parts by weight, the expansion ratio of the formed silicone rubber sponge is small, and if it exceeds 250 parts by weight, the strength of the formed silicone rubber sponge is impaired. The water-soluble polymer contained in the component (B) is blended in order to prepare an emulsion that has a high viscosity of an aqueous material when dissolved in water and is stable with a low emulsifier amount. The compounding quantity with respect to the water is 0.1 to 5 weight%, Preferably it is 0.5 to 3 weight%. When the amount is less than 0.1% by weight, the viscosity of the aqueous material in which the water-soluble polymer is dissolved is low and it is difficult to obtain a stable emulsion. When the amount exceeds 5% by weight, the viscosity is too high and degassing from the emulsion occurs. It becomes difficult and neither is preferable.
[0018]
The water-soluble polymer in component (B), sodium salt of carboxymethyl cellulose, sodium salt of Po Li acrylate or polymethacrylate are used.
[0019]
Used in the present invention component (C) of the emulsifier is blended in order to form a stable emulsion, nonionic emulsifiers are used. Nonionic surfactants as nonionic emulsifiers include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, ethylene glycol monofatty acid ester, propylene glycol monofatty acid ester, sorbitan monofatty acid ester, sorbitan trifatty acid ester, Examples include oxyethylene sorbitan tri-fatty acid ester, polyoxyethylene mono-fatty acid ester, polyoxyethylene di-fatty acid ester, polyoxyethylene propylene glycol fatty acid ester, or POE polyhydric alcohols. Good. The HLB value of the emulsifier used is preferably 6 to 14, and more preferably 2 or more types are used in combination. The blending amount of the component (C) can be significantly reduced by the viscosity of the component (B), and is 0. 1 to 10 parts by weight, preferably 0.5 to 7 parts by weight. If the amount is less than 0.1 parts by weight, a stable emulsion for a silicone rubber sponge is unlikely to be obtained. If the amount exceeds 10 parts by weight, the physical properties of the silicone rubber sponge after heat resistance are remarkably lowered.
[0020]
The silicone rubber sponge emulsion comprising the component (A), the component (B) and the component (C) can be produced, for example, by the following method. A predetermined amount of (A) a liquid silicone rubber composition, a predetermined amount of (B) water containing a water-soluble polymer, and a predetermined amount of (C) an emulsifier are charged into a high-speed stirring mixer and stirred for a predetermined time, or ( A) A component, (B) water containing a water-soluble polymer, and (C) a predetermined amount of emulsifier are charged into a high-speed stirring mixer, and after stirring for a predetermined time, a predetermined amount of (A) Component (b) and component (c) may be mixed with stirring. Examples of the mixer used here include a homomixer, a paddle mixer, a Henschel mixer, a homodisper, a colloid mixer, a vacuum mixing and stirring mixer, or a twin screw extruder, but if a stable emulsion can be obtained, There is no particular limitation.
[0021]
When the silicone rubber sponge emulsion entrains air bubbles during mixing, it is degassed, and is cured, for example, at a temperature of room temperature to 120 ° C., preferably 50 to 100 ° C., in a compression mold. By forming a rubber sponge-like molded body, and then removing water from the wet silicone rubber sponge molded body by secondary heat treatment at 150 to 250 ° C., the silicone rubber is uniform, fine, and has good dimensional accuracy. A sponge can be obtained. Alternatively, the silicone rubber emulsion can be extruded from a nozzle into a rod shape and cured in hot water at 80 to 100 ° C., for example, and dried with hot air to produce a string-like silicone rubber sponge.
[0022]
【Example】
Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. In the following description, “part” means “part by weight”, “%” means “% by weight”, and the viscosity is a value at 25 ° C. Each characteristic of the silicone rubber sponge emulsion and the silicone rubber sponge was measured under the following conditions.
-Emulsified state: After stirring and mixing for a predetermined time, the state of emulsification was judged by visual observation.
-Sponge density: The silicone rubber sponge emulsion was molded and cured into a sheet and then dried with hot air. The resulting molded sheet was punched with a punch having a constant diameter, and the weight and thickness of the punched rubber piece were measured. The volume (g / cm 3 ) was calculated as the density.
Dimensional accuracy: A dimensional ratio obtained by dividing the thickness (mm) of the molded sheet after drying with hot air by the thickness (mm) of the cured molded sheet before drying with hot air was calculated as the dimensional accuracy.
-Cell diameter: Observed with a magnifying glass.
[0023]
Examples 1-3
A fume having a molecular surface of both ends blocked with dimethylvinylsiloxy groups and having a viscosity of 10,000 mPa · s and having a viscosity of 10,000 mPa · s (vinyl group content 0.14%) [component (a)] 100 parts, specific surface area 200 m 2 / g Add 20 parts of silica, 5 parts of hexamethyldisilazane as a silica treating agent, and 1 part of water, mix uniformly with a mixer, heat-treat at 180 ° C. under reduced pressure for 2 hours, and have a fluid liquid silicone rubber base Was prepared. To 100 parts of this base, 0.5 parts of trimethylsiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer (silicon-bonded hydrogen content 0.8%) [component (b)] and chloroplatinic acid Of platinum complex of divinyltetramethyldisiloxane [component (c)] (platinum concentration 0.4%) and 0.1 part of 3,5-dimethyl-1-hexyl-3-ol as a reaction inhibitor And uniformly mixed to obtain a liquid silicone rubber composition. This liquid silicone rubber composition contains water containing polyacrylic acid soda which is a water-soluble polymer (water-soluble polymer content 1.0%), polyoxyethylene dilaurate having an HLB value of 6.6 as a nonionic surfactant, HLB Polyoxyethylene dioleate having a value of 10.4 in a blending ratio shown in Table 1 [blending ratio with respect to 100 parts of the total amount of the components (a), (b) and (c) in the liquid silicone rubber composition] The mixture was put into a commercially available Avitex mixer (manufactured by Matsubara Co., Ltd.) and mixed at a rotation speed of 9000 rpm for 10 minutes to prepare silicone rubber sponge emulsions.
[0024]
Next, in order to remove bubbles from the foamed silicone rubber sponge emulsion, after deaeration with a vacuum pump, it was poured into a sheet-shaped mold having a thickness of 2 mm, cured at 90 ° C. for 10 minutes, and wet silicone. A rubber sponge-like molded sheet was obtained. These molded sheets were placed in a hot air oven at 150 ° C. and dried with hot air for 1 hour to obtain respective sheet-like silicone rubber sponges. The density, dimensional accuracy, and cell diameter were measured and shown in Table 1. From this result, the silicone rubber sponge according to the present invention has good cell uniformity and excellent dimensional accuracy.
[0025]
Comparative Examples 1-2
Except for not containing a water-soluble polymer, the silicone rubber sponge emulsion was prepared in accordance with the procedure of Examples 1 and 2 at the blending ratio shown in Table 1, but a stable emulsion could not be produced and the silicone rubber sponge was in a wet state. A shaped article could not be obtained.
Comparative Example 3
100 parts of the liquid silicone rubber composition of Examples 1 to 3, 120 parts of water (2.0% of water-absorbing polymer) containing a water-absorbing polymer (cross-linked acrylate polymer sodium salt manufactured by Sanyo Chemical Industries) 7 parts of polyoxyethylene dilaurate were added and mixed to prepare an emulsion for a silicone rubber sponge. The results of curing and hot-air drying by the methods of Examples 1 to 3 are shown in Table 1.
[0026]
[Table 1]
Example 4
Methylvinylpolysiloxane polymer with a viscosity of 40,000 mPa · s blocked at both ends of the molecular chain with dimethylvinylsiloxy groups (vinyl group content 0.14%) [component (a)] 100 parts with dimethyldichlorosilane uniformly mixed with the treated (manufactured by Japan Aerosil Co.) Aerosil R-972 20 parts, by performing heat treatment for 2 hours at 180 ° C., to prepare a liquid silicone base having fluidity. To 100 parts of this base, 0.5 parts of trimethylsiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer (silicon-bonded hydrogen content 0.8%) [component (b)] and chloroplatinic acid Of platinum complex of divinyltetramethyldisiloxane [component (c)] (platinum concentration 0.4%) and 0.1 part of 3,5-dimethyl-1-hexyl-3-ol as a reaction inhibitor And uniformly mixed to obtain a liquid silicone rubber composition. In this liquid silicone rubber composition, water containing sodium polyacrylate as a water-soluble polymer (water-soluble polymer content 2) as a blending ratio with respect to 100 parts of the total amount of the above (a), (b) and (c). %) 120 parts, HLB 10.5 Sannonik SS-50 (manufactured by Sanyo Kasei Kogyo Co., Ltd.) 2.5 parts as a higher alcohol nonionic surfactant, HLB 12.8 Sannonic SS-70 (manufactured by Sanyo Kasei Kogyo Co., Ltd.) 2 Weigh 5 parts into a container. K. Using a homomixer MARKII2.5 type (manufactured by Tokushu Kika Kogyo Co., Ltd.), the mixture was mixed at a rotational speed of 5000 rpm for 5 minutes to prepare an emulsion for silicone rubber sponge.
[0028]
This silicone rubber sponge emulsion was degassed with a vacuum pump, then poured into a 2 mm thick sheet mold and cured at 90 ° C. for 15 minutes to obtain a wet silicone rubber sponge-like molded sheet. These molded sheets were dried with hot air in the same manner as in Example 1 to obtain a silicone rubber sponge. The density, dimensional accuracy and cell diameter were measured. As a result, the density was 0.59, the dimensional accuracy was 0.98, and the cell diameter was 0.05 to 0.1 mm.
[0029]
Comparative Example 4
In Example 4, all except using 120 parts of water (water-absorbing polymer content 0.3%) gelled with a crosslinked sodium salt of an acrylate polymer as the water-absorbing polymer instead of the water-soluble polymer. As a result of carrying out under the same conditions as in Example 4, the density was 0.58, the dimensional accuracy was 0.98, and the cell diameter was 0.2 to 1.0 mm.
Example 5
Precipitated silica-based liquid silicone rubber composition DY35-700A / B (manufactured by Toray Dow Corning Silicone Co., Ltd.), water containing sodium polyacrylate as a water-soluble polymer (water-soluble polymer content 2%) 120 2.5 parts of Sannonic SS-50 and 2.5 parts of Sannonic SS-70 as higher alcohol nonionic surfactants were weighed in a container. K. A homomixer was used and mixed at a rotational speed of 5000 rpm for 5 minutes to prepare an emulsion for silicone rubber, and then degassed, cured and dried with hot air in the same manner as in Example 4 to obtain a silicone rubber sponge. As a result of the measurement, dimension accuracy was 0.99, the cell diameter was 0.1mm or less.
[0030]
【The invention's effect】
The emulsion composition for a silicone rubber sponge of the present invention comprises the components (A) to (C) and is characterized in that it can be cured in the form of an emulsion to form a wet silicone rubber sponge-like molded product. Further, the method for producing the silicone rubber sponge of the present invention is obtained by drying a wet silicone rubber sponge-like molded body with hot air to obtain a silicone rubber sponge. Therefore, the mold shape has good followability and dimensional accuracy is good. It is characterized by excellent uniformity and efficient production of a silicone rubber sponge with fine cells.
Claims (4)
（Ｂ）成分の水溶性ポリマーが、ポリアクリレートあるいはポリメタクリレートのナトリウム塩、または、カルボキシメチルセルロースのナトリウム塩であり、
（Ｃ）成分の乳化剤が、非イオン界面活性剤であり、
前記（Ａ）における（ａ）、（ｂ）および（ｃ）の合計量１００重量部に対し、前記（Ｂ）を５０〜２５０重量部、前記（Ｃ）を０．１〜１０重量部の割合で含むことを特徴とするシリコーンゴムスポンジ用エマルション組成物。(A) ( a) a diorganopolysiloxane having at least two alkenyl groups in one molecule, (b) an organopolysiloxane having at least two silicon atom-bonded hydrogens in one molecule, and (c) a platinum-based catalyst An addition reaction curable liquid silicone rubber composition comprising: ( B) water containing a water-soluble polymer; and (C) an emulsifier.
The water-soluble polymer of the component (B) is a sodium salt of polyacrylate or polymethacrylate, or a sodium salt of carboxymethyl cellulose,
The emulsifier of component (C) is a nonionic surfactant,
The ratio of (B) to 50 to 250 parts by weight and (C) to 0.1 to 10 parts by weight with respect to 100 parts by weight of the total amount of (a), (b) and (c) in (A). An emulsion composition for a silicone rubber sponge, comprising:
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