末端官能基として水酸基をもつ液状ポリブタジエンを架橋する際, 補強性充てん剤を加えジイソシアナートにて鎖延長及び架橋を行わせるのが一般的であるが, この際, イソシァナートは空気中並びに充てん剤中の水分により消費される可能性がある.本研究は, 充てん剤中の水分及び充てん剤自身がどのようにイソシアナートを消費するかについて検討した.その結果, 次のことがわかった.1.極性溶媒中, 充てん剤の吸着水に対するイソシアナートの反応率は, 水に対するイソシアナートの反応率にほぼ近い.2.非極性溶媒中, 充てん剤の吸着水に対するイソシアナートの反応率並びに水に対するイソシアナートの反応率は, 極性溶媒中でのそれぞれの反応率より小さい.水とイソシアナートの反応では, 電子求引型触媒の添加効果は大きいが, 電子供与型触媒の添加効果は小さい.充てん剤の吸着水とイソシアナートとの反応では, 電子求引型触媒でもその添加効果は小さい.3.非極性溶媒中で, , ISAF-HSブラック, HAF-LSブラック, リードクレー並びに軽微性炭酸カルシウムなどはイソシアナートを消費する.

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Ultra-fine precipitated calcium carbonate (UFPCC) can be used not only as “Filler” but also as “Functional additive”. A small dosage of UFPCC together with reinforcing fillers (such as precipitated silica, carbon black which are difficult to mix or disperse) can act like a dispersing agent or processing aid, and to shorten the mixing time/to improve the dispersibility of reinforcing fillers can be expected.
In addition, UFPCC can improve the tackiness and elongation of unvulcanized rubber and it is supposed that these advantages may accelerate the mixing of fillers/rubber and extension of rubber together with filler which results to shorten the mixing time and to improve the dispersibility of reinforcing fillers.

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The author summarizes Synthetic Calcium Carbonate, especially Ultra-fine precipitated calcium carbonate (UF-PCC) and its function as Rubber Additive as follows: within Rubber formulation where Precipitated Silica was applied, the small amount of UF-PCC accelerated integration between Rubber and Precipitated Silica.
Also UF-PCC provided the better properties such as dispersion, tear strength and heat build-up to Rubber Compoundas well.
In the case of Carbon Black applied above formulation instead of Precipitated Silica, UF-PCC reduced BIT in mixing the rubber compound.
We also found that UF-PCC played a role of acid acceptor in the halogenated rubber utilizing UF-PCC and its alkaline property.

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Calcium carbonate, which is made from limestone available in all over Japan, has widely been used as fillers for various fields like rubber, plastics and paint, etc. In this paper, function and role of calcium carbonate, especially the ultrafine synthetic calcium carbonate, applied for rubber is reviewed.
In this report, ultrafine synthetic calcium carbonate is focused and its function & role applied for rubber is introduced.

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Calcium carbonate, which is made from limestone available in all over Japan, has widely been used as fillers for various fields like rubber, plastics, sealant, paint, and so on. In this paper, the ultrafine synthetic calcium carbonate applied to rubber compounding is reviewed.
Ultrafine synthetic calcium carbonate has various particle size and surface properties. Therefore, ultrafine synthetic calcium carbonate improves various properties; for example, reinforcement, dispersibility, tackiness, processability, hardness, and so on.

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末端官能基として水酸基を持つ液状ポリブタジェンゴム (以下, HT-PBと略称) をジイソシァナートで架橋する際の基礎データを得るために, 充てん剤の含水率測定を行うとともに各種含水率の充てん剤及び水を配合したHT-PBの混練前後での含水率変化とそれらの粘度との関係を調べた.含水充てん剤及び水を配合したHT～PBの含水率は手かきまぜではほとんど変わらない.しかし, ペイントミル混練によってこれらの値は変化し, 通し回数が増えるにつれて作業ふん囲気での平衡含水率に近づくことがわかった.配合物を4～8回ペイントミルに通すと、水及びカーボンブラック配合物では, 含水率が小さくなり, 実用上の影響は少なくなる.一方, 乾燥したシリカ配合物では1.1～1.3%程度まで吸水する傾向がみられた.HT-PB及びその充てん剤配合物の含水率の粘度に及ぼす影響は, HT-PB及びそのカーボンブラック・クレー, 並びに炭酸カルシウム配合物では小さい.しかし, シリカ配合HT-PBの含水率の粘度に与える影響は大きく, 更に, 同一含水率のシリカ配合物でも水分の分散状態によって粘度が大きく変わることがわかった.

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The state of filler dispersion in rubbers has been, in general, observed by means of a transmission electron microscopy (TEM). In the case of silicone rubber, however, TEM has seldom been applicable to such an observation, which may be attributable to the fact that the ultramicrotome method is difficult to apply for preparation of the specimens for reasons of its very low glass transition point.
In this paper, the specimens of silica-dispersed silicone rubber were prepared by the modified well-known freeze fracture, and a scanning electron microscopy (SEM) was successfully applied to observation of the despersion of silidca. The aggregates of silica with the diameter of over 10μm were observed clearly in shape. Further, it was found that the rubber areas with no silica filler existed around the aggregate in case of the surface-untreated silica dispersed, while such areas could not be noticed in case of the surface-treated silica dispersed.

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水酸基末端液状ポリブタジエン (以下, HT-PBと略記する) 充てん剤などを配合し, ジイソシアナートを用いて架橋する際, 充てん剤中の水分が架橋ゴムの物性に与える影響は, その充てん剤の種類により異なる. すなわち, 水分を無視して末端水酸基とイソシアナートを等量比で架橋して得られた. HT-PB純ゴム及びカーボンブラック配合架橋物の物性は, 含水率の少ない0.1%以下で変化が大きく, それ以上のところではあまり変化がないことがわかった. 一方, シリカ配合架橋物は含水率の高いところで変化が大きい. また水分を考慮した水酸基に対するイソシアナート基の比, r(=[NCO]/([OH] +H₂O)) が1.0から1.3にかけて, 純ゴム及びカーボンブラック配合架橋物の物性が最高を示めすが, シリカ配合物ではr=0.8のところに最高点があることが明らかとなった.

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溶液法²⁹Si NMRは,ポリオルガノシロキサンの微細な構造解析に極めて有効であり,近年活発に応用研究がなされているが,一方,固体 NMR は有機ケイ素系ポリマーに対してはポリシランのコンホメーション解析への応用等ごく一部を除いては,構造解析に応用された例はほとんど報告されていなかった.固体²⁹Si NMRの各種有機ケイ素ポリマーへの応用を図る中で,今回,従来測定が困難であったシリコーンゴム中のシリカの同定及び適当な分析方法がなく全くのブラックボックスの中にあったシリカ-シロキサン界面分析への応用を検討した結果,シリカの構造に起因するケイ素核の緩和時問の差を利用した²⁹Si DD/MAS法によって,湿式・乾式シリカの判別を,又²⁹Si CP/MASによって,シリコーンゴムの主成分である運動性の大きなジメチルシロキサンポリマーとシリカのバルク部を完全に除外して,シリカによって運動が制約されているシロキサン単位とシロキサンによって増感されている,まさにシリカ-シロキサン界面を選択的に測定しうることを見いだした.本分析法の確立により,シリコーンゴムの物性を左右する大きな因子であるが従来測定困難とされていたシリカ-シロキサンの界面情報を初めて明らかにすることができ,今後シリコーンエラストマーの高機能化,品質安定化・向上への活用ができるものと考えている.又,今回明らかにできた知見より,シリコーンゴムの劣化機構解明,架橋構造の解明をはじめ,更に多方面での応用が期待される.

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Development of bound rubber phase in silica filled rubber compounds was discussed in connection with filler-polymer interactions. The amount of bound rubber increased with increasing the averaged size of agglomerate formed by silica particles, independent of chemical structure of rubber molecules. In addition, no trace of bound rubber was found in silica-filled rubber compounds in which no agglomerate existed. This suggests that the bound rubber phase corresponds to the entrapped rubber phase in the agglomerate. NMR results revealed that chemical interactions were negligible between silanol groups and non-polar rubber molecules such as IR and SBR. In that case, the averaged size of agglomerate was dependent on the silanol number per unit surface area of silica particles. For polar rubber molecules such as NBR, infra-red spectra suggested the existence of hydrogen bonding between silanol groups and nitrile groups of NBR. With increasing the nitrile group content of NBR, the averaged size of agglomerate as well as the amount of bound rubber decreased. The hydrogen bonding suppressed the development of agglomerate in the compound, leading to the decrease in the amount of bound rubber entrapped in the agglomerate. Further, the hydrogen bonding had no effect on the formation of bound rubber on the silica particles. Such formation mechanism of bound rubber in silica filled rubber compound is quite different from the case of carbon black filled rubber compounds.

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Today's rising demand for paper copy machines require components of even higher reliability, stability and performance.
Heat roller, a component used in the final stage of copying process, directly affects quality and fixing of copied materials. The roller is required to provide a stable performance under severe operating conditions including load and a constant exposure to heat.
Thermal analysis, deterioration test and operative evaluation of paper feed test were conducted by the researchers. A closer correlation was found between life and design and/or degree of material deterioration of the roller. Accelerated life test was used to est imate life of the roller within the laboratory.

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Effects of silica on the vulcanization reaction by sulfur/N-cyclohexyl-2-benzothiazolylsulfenamide (CBS) in isoprene rubber were studied by FT-IR and ESR. It was found that the induction time of vulcanization reaction was shortened by the addition of silica. However, the efficiency of vulcanization at the final stage of reaction was lower for silica filled sample than for unfilled one. The structure of CBS in the vulcanization system was investigated by the FT-IR at a crosslinking temperature. It was found that by the addition of silica in the system new peaks appeared at 1541 and 1598cm^-1,suggesting a decomposition of CBS by silica. Further, the concentration of sulfur radical during the vulcanization was decreased by the addition of silica. However, the decomposition was suppressed by the removal of water molecules absorbed directly on silica surface. These results indicated that at an initial stage of vulcanization, most of CBS was decomposed by silanol groups which were covered with the adsorbed water, leading to the fast vulcanization reaction by sulfur, however, the concentration of CBS dropped quickly at the initial stage of vulcanization, resulting in the low efficiency of vulcanization. These results were explained by the decomposition of CBS by acid catalyst ability of silanol groups.

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An examination was carried out on the quantitative analysis of bound rubber in silica-filled rubber systems by a thermal gravimetric analyzer (TGA), transmission electron microscopy (TEM) and pulsed NMR. The bound rubbers in solution mixed composites were primarily composed of filler gel which corresponded to the entrapped rubber phase in the agglomerate of silica particles. The amounts were well correlated with the averaged size of agglomerate of silica particles (Sagg) in the composites. The Sagg for mechanically mixed composites was 10^-1 to 10^-2 of Sagg for solution mixed composites. Thus, most of the bound rubbers in the mechanically mixed composites were composed of rubber gel which corresponded to the chemically cross-linked rubber phase in the composites. The difference of segmental mobility between filler gel and rubber gel was detected by pulsed NMR. The mobility was higher for rubber gel than for filler gel.

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溶融亜鉛メッキ鋼板 (HDG板) の表面処理剤として, 無機超微粒子 (100nm以下) 含有アクリル複合樹脂 (複合樹脂) を適用し, 鋼板に対する耐食性, 塗装下地性について検討した。皮膜厚さ1～0μmの複合樹脂被覆鋼板およびアミノアルキド塗料塗装鋼板の塩水噴霧試験, 乾湿サイクル腐食試験, 沸水浸せきによる湿潤試験の結果, SiO₂複合樹脂皮膜は, 他の無機超微粒子のA1₂O₃, BaSO₄, CaCO₃, Fe₂O₃, TiO₂, ZnO複合樹脂皮膜に比べて, 耐食性および付着性とも著しい効果を示すことが判明した。
このSiO₂超微粒子は, その製造履歴, 粒子の比表面積, 表面層の水酸基 (≡SiOH) が耐食性に関係し, 乾式法より湿式法で製造された粒子, 比表面積が大きく水酸基の多い, 親水性の粒子が有効であった。また, 複合樹脂皮膜の膜厚が厚いほど, 耐食性は良好であった。
クロメート処理HDG板に対する複合樹脂皮膜の効果は, クロメート皮膜との相乗効果によって, 上記の皮膜処理HDG板に比べて, いずれの複合樹脂皮膜とも, その耐食性が塩水噴霧試験で数十倍に達し, この系でもSiO₂複合樹脂皮膜が効果的であった。SiO₂微粒子の種類, 膜厚の効果は, 上記の皮膜処理HDG板と同じ傾向を示した。
これらの結果から, SiO₂複合樹脂皮膜はHDG板との付着性が良く, HDG板の塗膜下腐食を抑制する効果を有することが予想される。

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