JP5102424B2 - Sealants and potting formulations containing mercapto-terminated polymers prepared by reaction of polythiols with polyvinyl ether monomers - Google Patents

Description

強い臭いを有していたポリマー3を除いて、上記の液状ポリチオエーテルは、すべて殆ど臭気が無いか中度の臭いしか有してなかった。
【００３５】
その後、実施例1〜8の各ポリマーを硬化させた。硬化は、硬化剤とDABCO促進剤を含む未配合樹脂を使用して行った。硬化剤は、下記の組成を有する：
エポキシノボラック¹(当量175.5) 22質量％
ヒダントインエポキシ²(当量132) 34質量％
炭酸カルシウム 34質量％
カーボンブラック 5質量％
シラン接着促進剤 5質量％
¹ミシガン州ミッドランドのDow Chemical社から入手し得るDEN-431
エポキシノボラック
²Ciba-Geigy社から入手し得るARACAST XU A4 238ヒダントインエポキシ
【００３６】
各硬化樹脂を、上述の手順に従って臭気について評価した。JRFタイプ1中に室温および常圧で1週間浸漬した後のTgおよび％質量獲得も、各硬化樹脂において測定した。体積膨張および質量獲得パーセントは、各硬化樹脂において、下記のようにして決定した：
w₁ = 空気中の初期質量
w₂ = H₂O中の初期質量
w₃ = 空気中の最終質量
w₄ = H₂O中の最終質量
％体積膨張 = 100×[(w₂ + w₃)‐(w₁ + w₄)]/(w₁‐w₂)
％質量獲得 = 100×(w₃‐w₁)/w₁
結果を表1に示す：
【表２】
表1

比較として、対照ポリマーは、硬化させたときに1〜2の臭気を有していた。
【００３７】
実施例 9
2100の数平均分子量と2.1の平均SH官能性Fを有するポリチオエーテル類をジビニルエーテルとジチオールを表2に示すようにして混合し、前述したようにしてこれら物質を反応させることによって調製した。その後、未配合の各ポリチオエーテルを15 gの上述の硬化剤と0.30 gのDABCOを使用して硬化させた。そのようにして調製した各ポリチオエーテルにおいて、下記の諸性質を測定した：粘度(未硬化物、ポイズp)；ショアーA硬度(硬化物、Rexジュロメーター値)；JRFタイプ1中140°F(60℃)および大気圧での1週間後%獲得質量(硬化物)；およびTg(硬化物、℃)。結果は、下記のとおりである：
【表３】
表2

^a PLURIOL^R E-200ジビニルエーテル
^bブタンジオールジビニルエーテル
^cポリテトラヒドロフランジビニルエーテル
^dヘキサンジチオール
【００３８】
上記の表から、ジビニルエーテルとジチオールの次の組合せが良好な耐燃料性と低温可撓性を硬化させたときに有するポリチオエーテルを生じていることが明らかである：PLURIOL^R E-200/DMDO；およびDEG-DVE/DMDO。他の潜在的に有用な組合せとしては、DEG-DVE/ECHDT；DEG-DVE/HDT；PLURIOL^R E-200/ECHDT；PLURIOL^R E-200/HDT；およびポリ-THF/DMDOがある。PLURIOL^R E-200/DMDSも優れた耐燃料性と低温可撓性を硬化させたときに有するが、未配合物は長時間液状のままではない。
【００３９】
実施例 10： PLURIOL^R/DMDOポリマーへのDMDSの付加
4種の液状ポリチオエーテルポリマーを前述したようにして調製した。各ポリマーは、下記の組成を有する(示した数値は、モル当量である)：
【表４】

これらのポリマーの各々に、0.2モル当量のTACを加えて、約3000の数平均分子量と2.2のSH官能性Fを与えた。得られた各未配合ポリマーを実施例9におけるようにして硬化させた(15 gの硬化剤組成物および0.30 gのDABCO)。各ポリマーにおいて、次の諸特性を測定した：Tg(樹脂、℃)；Tg(硬化物、℃)；粘度(p)；JRFタイプ1中での%膨張；JRFタイプ1中での%質量獲得；および水中での%質量獲得。結果は、表3に示す。
【表５】
表3

上記の各ポリマーは、すべて優れた耐燃料性を示した。ポリマー1と2は、とりわけ、AMS 3267§4.5.4.7に従って試験したときに優れた低温可撓性も示した。
【００４０】
実施例 11： PLURIOL^R/DMDOポリマーへのECHDTの付加
4種の液状ポリチオエーテルポリマーを前述したようにして調製した。各ポリマーは、下記の組成を有する(示した数値は、モル当量である)：
【表６】

これらのポリマーの各々は、約3000の数平均分子量と2.2のSH官能性Fを有していた。得られた各未配合ポリマーを実施例10におけるようにして硬化させた。各ポリマーにおいて、次の諸特性を測定した：Tg(樹脂、℃)；Tg(硬化物、℃)；粘度(p)；JRFタイプ1中での%膨張；JRFタイプ1中での%質量獲得；および水中での%質量獲得。結果は、表4に示す。
【表７】
表4

上記の各ポリマーは、すべて優れた耐燃料性と低温可撓性を示した。
【００４１】
実施例 12
撹拌器、温度計およびコンデンサーを備えた250mLの3口フラスコ内で、87.7 g (0.554モル)のDEG-DVEと112.3 g (0.616モル)のDMDOとを混合し、77℃(約170°F)に加熱する。得られた混合物に、0.8g (4.2ミリモル)のVAZO^R67触媒を添加する。反応混合物を82℃(約180°F)で約6時間反応させて、1625のチオール当量と2.0のSH官能性Fを有する200 g (0.06モル、収率100％)の低粘度液状ポリチオエーテル樹脂を得る。
実施例 13
撹拌器、温度計およびコンデンサーを備えた250mLの3口フラスコ内で、26.7g (0.107モル)のTAC、56.4 g (0.357モル)のDEG-DVEおよび117.0 g (0.642モル)のDMDOを混合し、77℃(約170°F)に加熱する。得られた混合物に、0.8g(4.2ミリモル)のVAZO^R67触媒を添加する。反応混合物を82℃(約180°F)で約6時間反応させて、800の当量と約3.5のSH官能性Fを有する200 g (0.07モル、収率100％)の高粘度液状ポリチオエーテル樹脂を得る。
【００４２】
実施例 14： シーラント組成物
実施例1のDMDO/DEG-DVEポリチオエーテルポリマーを含むシーラント組成物を下記のように配合した(量は質量部による)。
DMDO/DEG-DVEポリチオエーテル 100
炭酸カルシウム 60
酸化マグネシウム 1
フェノール樹脂³ 1
DMP-30 1
イソプロピルアルコール 3
³Occidental Chemical社から入手し得るMETHYLON 75128フェノール樹脂
上記の配合ポリマーを実施例９〜１１のエポキシ樹脂硬化剤と質量比10：1で充分混合し、周囲温度および周囲湿度で硬化させた。引張強度および伸びをASTM 3269およびAMS 3276に従って評価した。試験サンプルを作成するのに使用するダイは、ASTM D412に記載されている。引裂強度試験用の試験サンプルを作成するのに使用するダイは、ASTM D1004に記載されている。下記の物理的諸特性が硬化組成物において得られた：
25℃での硬化硬度 60ショアーA
破壊時引張強度 379.0 Pa (550psi)
破壊時伸び 600％
切込み引裂強度 17.86 kg/cm (100 p/i)
低温可撓性 合格
(AMS 3267§4.5.4.7)
【００４３】
実施例 15： シーラント組成物
実施例9のECHDT/DEG-DVEポリチオエーテルポリマーを含むシーラント組成物を下記のように配合した(量は質量部による)。
ECHDT/DEG-DVEポリチオエーテル 100
炭酸カルシウム 54
水和酸化アルミニウム 20
酸化マグネシウム 1
実施例14のフェノール樹脂 1
水素化ターフェニル可塑剤 6
DMP-30 1
イソプロピルアルコール 3
上記の配合ポリマーを実施例9〜12のエポキシ樹脂硬化剤と質量比10：1で充分混合し、周囲温度および周囲湿度で硬化させた。柿野の物理的諸特性が硬化組成物において得られた：
25℃での硬化硬度 72ショアーA
破壊時引張強度 379.0Pa (550psi)
破壊時伸び 450％
切込み引裂強度 15.18 kg/cm (85p/i)
低温可撓性 合格
【００４４】
実施例 16：OH-端末化封鎖型ポリチオエーテル
500mLのフラスコ内で、275.9 g (1.09モル)のPLURIOL^R E-200ジビニルエーテル、174.7 g (0.95モル)のDMDO、28.7 g (0.30モル)の3-メルカプトプロパノールおよび1.83 g (7.3ミリモル)のTACを混合した。混合物を70℃に加熱し、2.3 g (12ミリモル)のVAZO^R 67をゆっくり添加した。反応混合物を撹拌し、85〜90℃で4時間加熱して、1670のOH当量を有する480 g (0.15モル、収率100％)のポリマー(数平均分子質量＝3200、OH官能性F＝2.05)を得た。
実施例 17：OH-端末化封鎖型ポリチオエーテル
250mLのフラスコ内で、104.72 g (0.57モル)のDMDO、80.73 g (0.51モル)のDEG-DVEおよび14.96 g (0.13モル)のブタンジオールモノビニルエーテルを混合し、75℃に加熱した。加熱した混合物に、0.60 g (3ミリモル)のVAZO^R 67をゆっくり添加した。反応混合物を撹拌し、75〜85℃で6時間加熱して、200 g (0.064モル、収率100％)の極めて低い臭気と20℃で79ポイズの粘度を有する透明で殆ど無色のポリマーを得た。OH当量1570(数平均分子質量＝3200、OH官能性F＝2.00)。
【００４５】
実施例 18： シーラント組成物
実施例1のDMDO/DEG-DVEポリチオエーテルポリマーを含むシーラント組成物を下記のように配合した(量は質量％)。

⁴Air Products & Chemical社から入手し得るDABCOトリエチルアミン、ジアザビシクロ(2,2,2)オクタン。
⁵Occidental Chemical社から入手し得るMETHYLON 75108フェノール樹脂。
⁶上記フェノール/ポリスルフィド接着促進剤は、約31％のVARCUM 29202フェノール樹脂、66％のThiokol LP-3ポリスルフィドおよび3％の米国特許第4,623,711号の実施例4に従って調製したポリマー(1モルのポリスルフィドに対して1モルのジチオールの比)を約150°F(65℃)の温度で45分間反応させ、次いで230°F(110℃)に45〜60分間に亘って加熱し、その後、230°F(110℃)で165分間加熱することによって調製した。
⁷E.I.duPont de Nemours Company社から入手し得るTYZOR TBTチタネート。
⁸OSi Specialities, Inc 社から入手し得るA-1100アミノ官能性シラン。
【００４６】

⁹Shell Chemical社から入手し得るEPON 828 ビスフェノールAジグリシジルエーテル。
¹⁰Dow Chemical社から入手し得るDEN431エポキシノボラック。
¹¹Monsanto Co社から入手し得るHB-40可塑剤。
¹²Cabot Corp社から入手し得るFerbam76% WDGカルバミド酸塩。
¹³OSi Specialities,Inc社から入手可能なエポキシ官能性シランA-187。
ベース組成物の成分各々を列挙した順序で順次混合した。別の容器内で、促進剤の成分各々を列挙した順序で順次混合した。本発明発明に従うシーラント配合物を、100gのベース組成物を18.5gの上記促進剤と混合することによって調製した。
【００４７】
（産業上の利用性）
本発明発明の組成物は、燃料タンク用の航空宇宙シーラントおよびライニング剤のような航空宇宙用途において、また、電気注封または封入コンパウンドとして有用である。本発明発明に従う航空宇宙シーラント材料は、極端な温度性能、耐燃料性および可撓強度のような諸特性を示し得る。本発明の配合物は、温度極端性、化学的に苛酷な環境および機械的振動を経験し得る電気および電子コンポーネントを封入する注封コンパウンドとしてのしように良好に適している。
上記の説明は、本発明の特定の実施態様を例示するものであり、その実施に限定する積りはない。すべての等価物を包含する特許請求の範囲によって、本発明の範囲は、限定されるものとする。
【図面の簡単な説明】
【図１】 公知タイプのシーラント組成物における押出速度曲線と比較した本発明のシーラント組成物における時間(T)に対する押出速度(E)の線グラフである。
【図２】 本発明のポリチオエーテルシーラント組成物(◆)および従来技術のポリスルフィドシーラント組成物(■)の押出速度曲線の半対数グラフである。[0001]
(Technical field to which the invention belongs)
The present invention relates to a sealant or potting formulation having good low temperature flexibility and fuel resistance prepared from a mercapto-terminated polymer produced by reaction of polythiols with polyvinyl ether monomers.
[0002]
(Background technology)
Commercially available polymeric materials that have sufficient sulfur content and exhibit desirable sealing properties and fuel resistance as aerospace sealants and electroporation compounds are described, for example, in US Pat. No. 2,466,963 Polysulfide polyformal polymers and alkyl side chain containing polythioether polyether polymers described, for example, in US Pat. No. 4,366,307 to Singh et al. Materials useful in this concept also have the desirable properties of low temperature flexibility characterized by a low glass transition temperature (Tg) and fluidity at room temperature.
The desired combination of additional properties in an aerospace sealant that is much more difficult to obtain is a long application time (i.e., the time that the sealant can be used) and a short cure time (the time required to reach a given strength). It is a combination. U.S. Pat. No. 4,366,307 to Singh et al. Discloses such a material. Singh et al. Disclose acid-catalyzed condensation of hydroxyl functional thioethers. The hydroxyl group is in the β position relative to the sulfur atom due to increased condensation reactivity. The Singh et al. US patent also teaches the use of such hydroxyl functional thioethers having pendant methyl groups to obtain polymers with good flexibility and fluidity. However, the disclosed condensation reaction has a yield of up to about 75% of the desired condensation product. Furthermore, the acid-catalyzed reaction of β-hydroxysulfide monomers is a thermally stable and highly malodorous cyclic byproduct such as 1-thia-4-oxa-cyclohexane that limits the proper application of the desired polymers. This produces a significant amount of aqueous solution.
[0003]
Another desirable feature of polymers suitable for use in aerospace sealants is high temperature resistance. Although the high temperature performance is generally enhanced by the introduction of sulfur-carbon bonds into the polymer, the polysulfide polyformal polymers disclosed in US Pat. No. 2,466,963 have multiple -SS-bonds in the polymer backbone. It has only compromised heat resistance. In the polymers of US Pat. No. 4,366,307 to Singh et al., Enhanced thermal stability is achieved by replacing polysulfide bonds with polythioether (—S—) bonds. However, the heat resistance of these polythioethers is limited as a result of the residual acid condensation catalyst.
U.S. Pat. No. 4,609,762 to Mrris et al. Describes reacting dithiols with secondary or tertiary alcohols to obtain liquid polythioethers that do not contain oxygen in the polymer backbone. However, curable polymeric materials formed from these polymers have the disadvantage of reduced fuel resistance due to the large number of pendant methyl groups present. Moreover, the disclosed method also generates undesirable aqueous acidic waste.
[0004]
Cameron US Pat. No. 5,225,472 discloses the preparation of polythioether polymers by acid-catalyzed condensation of dithiols with active carbonyl compounds such as HCOOH. This process also generates undesirable aqueous acidic waste.
Addition polymerization of aromatic or aliphatic dithiols with diene monomers has been described in the literature. For example, Klemm, E. et al., J. Macromol. Sci. -Chem., A28 (9), pp. 875-883 (1991); Nuyken, O. et ai., Makromol. Chem., Rapid Commun. 11, 365-373 (1990). However, both Klemm et al. And Nuyken have selected specific starting materials that are liquid at room temperature and have excellent low temperature flexibility (low Tg) and high resistance to fuel (ie, hydrocarbon liquid) when cured. Does not suggest to prepare. Klemm et al does not suggest the production of polymers that can be cured at temperatures below room temperature. Furthermore, the reaction disclosed by Klemm et al. Also produces undesirable cyclic by-products.
In sealant technology, there is a need for coatings and electroporation formulations or compositions that can have good shelf life as well as good performance characteristics (such as fuel resistance, flexibility strength, heat resistance and long-term use). ing.
[0005]
(Disclosure of the Invention)
The present invention provides: (a) at least one ungelled mercapto-terminated polymer prepared by reacting a reactant comprising at least one polyvinyl ether monomer and at least one polythiol substance; (b) the mercapto-terminated polymer Prepared from components comprising at least one curing agent reactive with the mercapto group of the polymer; and (c) at least one additive selected from the group consisting of fillers, adhesion promoters, plasticizers and catalysts. Sealant or potting formulation.
Another aspect of the present invention is: (a) at least one ungelled mercapto-terminated polymer prepared from a reactant comprising diethylene glycol divinyl ether and dimercaptodioxaoctane; (b) a mercapto group of the mercapto-terminated polymer. At least one curing agent that is reactive with; and (c) a sealant prepared from components comprising at least one additive selected from the group consisting of fillers, adhesion promoters, plasticizers and catalysts, or It is a potting formulation.
The above sealant formulations are useful in various applications such as aerospace applications or electropotting compounds.
Unless otherwise stated in the examples or unless otherwise specified, the amounts of components, reaction conditions, etc. used in the specification and claims of the present invention should be understood in all cases to be provided with “about”. . Also, as used herein, the term “polymer” is meant to denote oligomers, homopolymers and copolymers. The present invention can also be easily understood by referring to the attached drawings.
[0006]
The sealant and potting formulations of the present invention comprise one or more ungelled mercapto-terminated polymers or polythioethers. Surprisingly, polythioethers prepared from a combination of polythiol (one or more) and polyvinyl ether monomer (one or more) according to the present invention are liquid at room temperature and atmospheric pressure and have the desired physical and rheological properties. It has been found to produce ungelled mercapto-terminated polymers that have various properties and are substantially free of malodorous cyclic by-products. In addition, these materials of the present invention are substantially free of harmful catalyst residues and exhibit excellent heat resistance characteristics.
Mercapto-terminated polymers useful in the sealants and potting formulations of the present invention are preferably liquid at room temperature and normal pressure, and cured sealants comprising such polymers have low temperature flexibility and fuel resistance. As used herein, the term “room temperature and pressure” refers to conditions of approximately 77 ° F. (25 ° C.) and 1 atmosphere (101.1 kPa: 760 mm Hg).
The mercapto-terminated polymer is ungelled, ie substantially free of cross-linking. The term “ungelled” means that the mercapto-terminated polymer is substantially free of crosslinks and has an intrinsic viscosity when dissolved in a suitable solvent, for example as measured according to ASTM-D1795 or ASTM-D4243. means. The intrinsic viscosity of the mercapto-terminated polymer is an indicator of its finite molecular weight. On the other hand, the gelled reaction product will have an intrinsic viscosity that is too high to measure because it has an essentially infinite high molecular weight.
[0007]
The mercapto-terminated polymer preferably has a glass transition temperature (Tg) not higher than −50 ° C., more preferably not higher than −55 ° C., most preferably not higher than −60 ° C. Generally, the glass transition temperature of the mercapto-terminated polymer is in the range of −85 ° C. to −50 ° C., more preferably −70 ° C. to −50 ° C., as measured by differential scanning calorimetry (DSC). .
The low temperature flexibility is determined by a known method, for example, the method described in Aerospace Material Specification (AMS) 3267 §4.5.4.7, MIL-S (Military Specification) -8802E §3.3.12 and MIL-S-29574. Further, it can be measured by a method similar to the method described in ASTM (American Society for Testing and Materials) D522-88. A cured formulation with good low temperature flexibility results in aerospace applications because the formulation is subject to wide variations in environmental conditions such as temperature and pressure and physical conditions such as joint compression and vibration. Is desirable.
An advantage of the inventive formulation is that the inventive formulation exhibits highly desirable fuel resistance properties when cured, based at least in part on the use of the mercapto-terminated polymer. The fuel resistance of a cured sealant can be measured by the percent volume expansion after prolonged exposure of the cured sealant to a hydrocarbon fuel, which is a method similar to that described in ASTM D792 or AMS 3269. Can be measured quantitatively. In the fuel resistance test, a cured sealant can be prepared from 100 parts by weight of mercapto-terminated polymer, 50 parts by weight of precipitated calcium carbonate and a 1: 1 equivalent ratio of mercapto groups to epoxy groups. The epoxy curing agent can be prepared from a 60:40 mass ratio of EPON 828 bisphenol A diglycidyl ether (available from Shell Chemical) to DEN 431 bisphenol A novolac resin (available from Dow Chemical).
[0008]
In a preferred embodiment, the cured sealant of the present invention is not higher than 40% after being immersed in Jet Reference Liquid (JRF) Type 1 at 140 ° F. (60 ° C.) and ambient pressure for 1 week, preferably 25 Having a percent volume expansion not higher than%. More preferably, the volume expansion percentage of the cured polymer of the present invention is not higher than 20%, more preferably in the range of 0-20%. Jet Reference Liquid JRF Type 1 as used herein for the measurement of fuel resistance has the following composition (available from SAE (Society of Automotive Engineers, Warendal, Pa.) July 1989) See AMS 2629 § 3.1.1 or later issued daily]:
Toluene 28 ± 1% by volume
Cyclohexane (industrial grade) 34 ± 1% by volume
Isooctane 38 ± 1% by volume
Tertiary dibutyl disulfide
(Doctor Sweet) 1 ± 0.005% by volume
Tertiary butyl mercaptan 0.015 of the above 4 other ingredients
± 0.0015 mass%
[0009]
The ungelled mercapto-terminated polymer preferably has a number average molecular weight of about 500 to about 20,000, more preferably about 1,000 to about 10,000, and most preferably about 2,000 to about 5,000 g / mol, the molecular weight being polystyrene. Measure by gel permeation chromatography using a standard.
Liquid mercapto-terminated polymers within the scope of the present invention are difunctional, i.e. linear polymers having two end groups, or polyfunctional, i.e. branched polymers having three or more end groups. obtain.
The mercapto-terminated polymer is prepared by reacting a reactant comprising one or more polyvinyl ether monomers and one or more polythiol materials. Useful polyvinyl ether monomers include divinyl ethers having the following formula (V):
CH₂= CH-O-(-R²-O-) m-CH = CH₂            (V)
(Where R²C₂~ C₆ n-alkylene, C₂~ C₆Branched alkylene, C₆~ C₈Cycloalkylene or C₆~ C_TenAn alkylcycloalkylene group or-[(CH₂-)_p-O-]_q-(-CH₂-)_rM is a rational number ranging from 0 to 10; p is an individually chosen integer ranging from 2 to 6; q is an individually chosen integer ranging from 1 to 5 And r is an individually chosen integer in the range of 2-10).
[0010]
The substance of formula V is a divinyl ether. Such divinyl ether monomers described in this invention are compared to prior art polymers prepared from alkenyl ethers and conjugated dienes (such as 1,3-butadiene copolymerized with dithiols such as DMDS). In this case, a polymer having excellent fuel resistance and low temperature performance is provided. Divinyl ether (m = 0) is effective in the present invention. Preferred divinyl ethers include compounds having at least one oxyalkylene group, more preferably 1 to 4 oxyalkylene groups (such as compounds wherein m is an integer from 1 to 4). More preferably, m is an integer of 2-4. Commercially available divinyl ether mixtures can also be used in the preparation of mercapto-terminated polymers according to the present invention. Such a mixture is characterized by a non-integer average number of alkoxy units per molecule. That is, m in formula V can also have a rational value of 0 to 10.0, preferably 1.0 to 10.0, very preferably 1.0 to 4.0, especially 2.0 to 4.0.
Suitable polyvinyl ether monomers include divinyl ether, ethylene glycol divinyl ether (EG-DVE) (R² = Ethylene, m = 1), butanediol divinyl ether (BD-DVE) (R² = Butylene, m = 1), Hexanediol divinyl ether (HD-DVE) (R² = Hexylene, m = 1), diethylene glycol divinyl ether (DEG-DVE) (R² = Ethylene, m = 2) (preferred), triethylene glycol divinyl ether (R² = Ethylene, m = 3), tetraethylene glycol divinyl ether (R² = Ethylene, m = 4), divinyl ether monomers such as cyclohexanedimethanol divinyl ether, polytetrahydrofuryl divinyl ether; trivinyl ether monomers such as trimethylolpropane trivinyl ether; tetrafunctionality such as pentaerythritol tetravinyl ether Monomers; and mixtures thereof. The polyvinyl ether material may have one or more pendant groups selected from the group consisting of alkyl groups, hydroxyl groups, alkoxy groups and amine groups.
[0011]
R²Is C₂~ C₆Useful divinyl ethers that are branched alkylenes can be prepared by reacting a polyhydroxy compound with acetylene. Examples of this type of compound include R²-CH- (CH_Three)-Compounds that are alkyl-substituted methylene groups (e.g., PLURIOL^R “PLURIOL like E-200 divinyl ether^R"Blends (BASF, Pasipanee, NJ), R² = Ethylene, m = 3.8) or alkyl-substituted ethylene (eg, -DPE polymer blends such as DPE-2 and DPE-3 (International Specislty Products, Weine, NJ) -CH₂CH (CH_ThreeThere is a compound that is)-).
Other useful divinyl ethers include R²Are polytetrahydrofuryl (poly-THF) or polyoxyalkylene, preferably fluorinated compounds or compounds having an average of about 3 monomer units.
Two or more polyvinyl ethers of the above formula V can be used in the above method. That is, in a preferred embodiment of the invention, two polythiols of formula IV (described below) and one polyvinyl ether monomer of formula V, one polythiol of formula IV and two polyvinyl ether monomers of formula V , Two polythiols of formula IV and two polyvinyl ether monomers of formula V, and three or more compounds of one or both formulas can be used to prepare various polymers according to the present invention. All combinations of such compounds shall fall within the scope of the present invention.
Generally, the polyvinyl ether monomer constitutes less than 20-50 mol%, preferably less than 30-50 mol% of the reaction used to prepare the mercapto-terminated polymer.
[0012]
Suitable polythiol materials for preparing the mercapto-terminated polymers include compounds, monomers or polymers having at least two thiol groups. Useful polythiols include dithiols having the following formula (IV):
HS-R¹―SH (IV)
(Where R¹C₂~ C₆ n-alkylene; C having one or more pendant groups which can be, for example, a hydroxyl group, an alkyl group (such as a methyl or ethyl group) or an alkoxy group_Three~ C₆Branched alkylene group; C₆~ C₈Cycloalkylene; C₆~ C_TenAlkylcycloalkylene group;-[(CH₂)_p-X]_q-(-CH₂)_r-; Or at least one -CH2- unit is replaced by a methyl group-[(-CH₂)_p-X]_q-(-CH₂)_rP can be an individually chosen integer in the range 2-6; q can be an individually chosen integer in the range 1-5; r can be in the range 2-10 Individually selected integer).
More preferred dithiols include one or more heteroatom substituents in the carbon backbone, ie, X is a heteroatom such as O, S or other divalent heteroatom group; Tertiary amine group, ie -NR⁶-(R⁶Are hydrogen or methyl groups); or other dithiols containing substituted trivalent heteroatoms. In preferred embodiments, X is O or S, thus R¹-[(-CH₂-)_p-O-]_q-(-CH₂-)_r-Or-[(-CH₂-)_p-S-]_q-(-CH₂-)_r-That's it. Preferably p and r are equal, most preferably both have a value of 2.
[0013]
Useful polythiols include, but are not limited to, 1,2-ethanedithiol, 1,2-propanedithiol, 1,3-propanedithiol, 1,3-butanedithiol, 1,4-butanedithiol, 2 , 3-butanedithiol, 1,3-pentanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, 1,3-dimercapto-3-methylbutane, dipentene dimercaptan, ethylcyclohexyldithiol (ECHDT), dimercapto There are dithiols such as diethyl sulfide, methyl substituted dimercaptodiethyl sulfide, dimethyl substituted dimercaptodiethyl sulfide, dimercaptodioxaoctane, 1,5-dimercapto-3-oxapentane and mixtures thereof. The polythiol material can have one or more pendant groups selected from lower alkyl groups, lower alkoxy groups and hydroxyl groups. Suitable alkyl pendant groups include C₁~ C₆Linear alkyl, C_Three~ C₆There are branched alkyls, cyclopentyl and cyclohexyl.
Preferred dithiols include dimercaptodiethyl sulfide (DMDS) (p = 2, q = 2, r = 2, X = S), dimercaptodioxaoctane (DMDO) (p = 2, q = 2, r = 2, X = O), and 1,5-dimercapto-3-oxapentane (p = 2, r = 2, q = 1, X = O). Dithiols containing both heteroatom groups in the carbon main chain and pendant groups such as alkyl groups can also be used. Such compounds include HS-CH₂CH (CH_Three) -S-CH₂CH₂-SH, HS-CH (CH_Three) CH₂-S-CH₂CH₂Methyl-substituted DMDS such as -SH, and HS-CH₂CH (CH_Three) -S-CH (CH_Three) CH₂-SH and HS-CH (CH_Three) CH₂-S-CH₂CH (CH_ThreeThere are dimethyl-substituted DMDS such as) -SH.
Two or more different polythiols can also be used as desired to prepare useful polythioethers.
Preferably, the polythiols have a number average molecular weight in the range of 90 to 1000 grams / mole, preferably 90 to 500 grams / mole.
[0014]
The relative amounts of dithiol and divinyl ether materials used to prepare the mercapto-terminated polymer are selected to obtain mercapto end groups (—SH). These mercapto-terminated polymers may further contain thiol end groups that do not react (“capped”) or react with other substances to react or react with non-reactive end or pendant groups (“capped”). It may contain one or more thiol groups giving ")". By capping the polymers of the present invention, it is possible to introduce additional terminal functionality, eg, hydroxyl or amine groups, into the polymer or terminal groups that are resistant to further reactions such as terminal alkyl groups. Preferably, the stoichiometric ratio of polythiol to divinyl ether material is less than 1 equivalent of polyvinyl ether material to 1 equivalent of polythiol resulting in a mercapto-terminated polymer. More preferably, the stoichiometric ratio is selected so that the polymer is fully terminated with mercapto groups.
Hydroxyl- or amino-functional terminated polymers can be obtained, for example, by reacting vinyl terminated materials with mercapto alcohols such as 3-mercaptopropanol or mercaptoamines such as 4-mercaptobutylamine, respectively, or by converting mercaptan terminated materials. It can be prepared by reacting with a vinyl terminated material having a hydroxyl functionality such as butanediol monovinyl ether or an amine functionality such as aminopropyl vinyl ether.
The mercapto-terminated polymer preferably constitutes 30-90%, more preferably 30-60% by weight of the sealant formulation of the present invention, based on the total mass of the sealant formulation of the present invention.
[0015]
The reactants that prepare the mercapto-terminated polymer can further include one or more free radical catalysts. Preferred free radical catalysts include azo compounds, for example azobis-nitrile compounds such as azo (bis) isobutyronitrile (AIBN); organic peroxides such as benzoyl peroxide and t-butyl peroxide; There are inorganic peroxides and similar free radical generators. The reaction can also be carried out by UV irradiation in the presence or absence of a cationic photoinitiating component. Ion-catalyzed processes using inorganic or organic bases such as triethylamine can also provide materials useful in the concept of the present invention.
Mercapto-terminated polymers within the scope of the present invention can be prepared by a number of methods. According to a first preferred method, (n + 1) moles of the following formula IV:
HS-R¹―SH (IV)
Or a mixture of at least two different compounds of formula IV with n moles of the following formula V:
CH₂= CH-O-(-R²-O-) m-CH = CH₂            (V)
Or a mixture of at least two different compounds of formula V in the presence of a catalyst. This method results in mercapto-terminated bifunctional polymers that are not blocked.
As noted above, compounds of formulas IV and V having pendant alkyl groups such as pendant methyl groups are useful according to the present invention, but surprisingly, formulas IV and V that do not contain pendant methyl groups or other alkyl groups. Was found to yield a mercapto-terminated polymer that did not gel at room temperature and atmospheric pressure.
[0016]
The mercapto-terminated polymer-blocked analogs comprise a substance having formula IV in a stoichiometric ratio of less than 1 equivalent of dithiol per equivalent of vinyl of formula V or a mixture of at least two different compounds having formula IV and formula V From about 0.05 to about 2 moles of the following formula VI: or a mixture of at least two different compounds of formula V:
CH₂= CH- (CH₂)_s-O―R^Five                (VI)
Or a mixture of at least two different compounds having the formula VI in the presence of a suitable catalyst.
The materials of formula VI are alkyl ω-alkenyl ethers having terminal ethylenically unsaturated groups that react with terminal thiol groups to sequester polythioether polymers.
In formula VI, s is an integer from 0 to 0, preferably 0 to 6, more preferably 0 to 4; R^FiveIs at least one -OH or -NHR⁷Group (R⁷Is H or C₁~ C₆Unsubstituted or substituted alkyl group, preferably C₁~ C₆N-alkyl group. Useful R^FiveExamples of groups are alkyl groups such as ethyl, propyl and butyl; hydroxyl substituents such as 4-hydroxybutyl; amine substituents such as 3-aminopropyl, and the like.
[0017]
Particularly preferred materials of formula VI are amino- and hydroxyalkyl vinyl ethers such as 3-aminopropyl vinyl ether and 4-hydroxybutyl vinyl ether (butanediol monovinyl ether), and unsubstituted alkyl vinyl ethers such as ethyl vinyl ether. Monovinyl ethers (S = 0). Further preferred materials of formula VI include allyl ethers (s = 1) such as 4-aminobutyl allyl ether, 3-hydroxypropyl allyl ether, and the like. Although materials with s greater than 6 can be used, the resulting polymer has a lower fuel resistance than polymers with s of 6 or less.
Use of an equivalent amount of the Formula VI material relative to the thiol group present in Formula IV results in a well-blocked mercaptopolymer, while use less than equivalent results in a partially blocked polymer.
Preferably, an equivalent amount of polyvinyl ether is reacted with the dithiol or polythiol mixture.
[0018]
Preferred linear structured mercapto-terminated polymers useful in the sealants and potting formulations of the present invention have the structure of the following formula (I):
HS-R¹-[-S- (CH₂)_p-O-(-R²-O-)_m-(CH₂)_q-S-R¹-]_n-SH (I)
(Where R¹C₂~ C_TenN-alkylene, C₂~ C₆Branched alkylene group, C₆~ C₈Cycloalkylene or C₆~ C_TenAlkylcycloalkylene group, heterocyclic,-[(-CH₂)_p-X]_q-(-CH₂)_r-Or at least one -CH₂-The unit is substituted with a methyl group-[(-CH₂)_p-X]_q-(-CH₂-)_r-Indicates;
R²C₂~ C_TenN-alkylene, C₂~ C₆Branched alkylene group, C₆~ C₈Cycloalkylene or C₆~ C₁₄Alkylcycloalkylene group, heterocyclic,-[(-CH₂)_p-X]_q-(-CH₂)_r-Indicates;
X is O, S and NR⁶-Indicates one selected from the group consisting of;
R⁶Represents H or methyl;
m represents an individually selected rational number from 1 to 50;
n represents an individually selected integer from 1 to 60;
p represents an individually selected integer ranging from 2 to 6;
q represents an individually selected integer ranging from 1 to 5;
r represents an integer selected from 2 to 10).
In a more preferred embodiment of the polymer, R¹Is C₂~ C₆Alkyl and R²Is C₂~ C₆Alkyl.
[0019]
In a preferred embodiment, the polythioether has the following formula (II):
A ― (― [R^Three]_y-R^Four)₂          (II)
Wherein A represents a structure having formula I;
y is 0 or 1;
R^ThreeIs a single bond when y = 0, and --S- (CH₂)₂― [― O―R²―]_mIndicates -O-;
R^FourIs -SH or -S-(-CH when y = 0₂-)_{2 + s}―O―R^FiveWhen y = 1, -CH = CH₂Or-(CH₂-)₂―S―R^FiveIndicates;
S represents an integer of 0 to 10;
R^FiveIs at least one -OH or -NHR⁷C not substituted or substituted with groups₁~ C₆Represents an alkyl group;
R⁷H or C₁~ C₆N-alkyl group of
That is, the polythioethers of formula II are linear bifunctional polymers that may be blocked without blocking. When y = 0, the polymer contains a terminal thiol group or a sequestered derivative thereof. In another embodiment, when y = 1 (not preferred), the polymer comprises a terminal vinyl group or a capped derivative thereof.
[0020]
According to a preferred embodiment, the polythioether of the present invention is a bifunctional thiol-terminated (unblocked) polythioether. That is, in Formula II, y = 0, R^FourIs -SH. That is, the polythioether of the present invention has the following structure:
HS-R¹― [― S― (CH₂)₂―O ― [― R²―O-]_m-(CH₂)₂―S―R¹-]_n-SH
In a preferred embodiment, R¹ =-[(-CH₂)_p-X]_q-(-CH₂)_r-(p = 2, X = O, q = 2 and r = 2), R²Is an ethylene group, m = 2 and n is about 9.
The polymer is prepared, for example, by reacting divinyl ether or a mixture thereof with excess dithiol or a mixture thereof as described in detail below.
In another embodiment of the above polythioether, m = 1, R in formula II² = when n-butylene, R¹Is not ethylene or n-propylene. Also preferably, m = 1, p = 2, q = 2, r = 2 and R² X is not O when = ethylene.
Although not preferred, the polythioethers according to the present invention may also comprise bifunctional vinyl-terminated polythioethers. That is, in Formula II, y = 1, R^Four-CH = CH₂It is. These polymers are prepared, for example, by reacting dithiols or mixtures thereof with excess divinyl ether or mixtures thereof as described in detail below. Similar capped polythioethers have terminal- (CH₂-)₂-S-R_Fiveincluding.
[0021]
Preferably, the mercapto-terminated polymer is essentially free of sulfone, ester or disulfide bonds, more preferably free of such bonds. The absence of these bonds results in good fuel resistance and temperature characteristics and good hydrolytic stability. As used herein, “essentially free of sulfone, ester or disulfide linkages” means that less than 2 mol% of the linkages of the mercapto-terminated polymer are sulfone, ester or disulfide linkages. Disulfide bonds are particularly susceptible to thermal degradation and sulfone bonds are particularly susceptible to hydrolytic degradation.
Mercapto-terminated polymers useful in the formulations of the present invention have at least two mercapto functional groups. The multifunctional analog of the above bifunctional mercapto-terminated polymer is obtained by reacting one or more compounds of formula IV and one or more compounds of formula V in an appropriate amount with a multifunctional agent. Can be prepared.
The term “multifunctional agent” as used herein refers to —SH and / or —CH═CH.₂A compound having three or more components that are reactive with the group. The polyfunctionalizing agent preferably comprises 3 to 6 such components and thus represents a “z-valent” polyfunctionalizing agent, where z is such a polyfunctionalizing agent contained in the polyfunctionalizing agent. The number of components (preferably 3-6), ie the number of individual branches that the multifunctional mercapto-terminated polymer comprises.
The polyfunctionalizing agent can be represented by the following formula:
B- (R⁸)_z
(Where R⁸-SH or -CH = CH₂Represents one or several components reactive with the group; B is a z-valent residue of the polyfunctionalizing agent, ie a reactive component R⁸Other than the above polyfunctionalizing agent).
[0022]
That is, the multifunctional mercapto-terminated polymer according to the present invention preferably has the following formula:
B- {R⁸-CH₂CH₂-O- (R₂-O)_mCH₂CH₂-S-R¹-[-S-CH₂CH₂-O- (R²-O)_m-CH₂-S-R¹]_n-SH}_zOr
B- {R⁸-S-R¹-[-S-CH₂CH₂-O- (R²-O)_m-CH₂-S-R¹]_n-SH}_z
Where B is the z-valent residue of the polyfunctionalizing agent;
R¹, R², N and m represent the structures and values described above in Formula I;
R⁸Indicates a component that is reactive with a terminal vinyl group or a mercapto group;
z represents an integer of 3 to 6).
The polyfunctional polythioether according to the invention may preferably have the following formula (III):
B― (A― [R^Three] y-R^Four)_z            (III)
Wherein A represents a structure having formula I;
y is 0 or 1;
R^ThreeIs a single bond when y = 0, and --S- (CH₂)₂-[-O―R²-]_mIndicates -O-;
R^FourIs -SH or -S-(-CH when y = 0₂-)_{2 + s}-O―R^FiveWhen y = 1, -CH = CH₂Or-(CH₂-)₂-S-R^FiveIndicates;
R^FiveIs at least one -OH or -NHR⁷C not substituted or substituted with groups₁~ C₆Represents an alkyl group;
R⁷H or C₁~ C₆N-alkyl group of
s is an integer from 0 to 10;
z is an integer from 3 to 6;
B is the z-valent residue of the multifunctional agent).
[0023]
As with the bifunctional embodiment described above, the polyfunctional polythioethers of the present invention are terminal-SH or CH = CH₂Groups are optionally included or blocked, i.e. terminal-S-(-CH₂-)_{2 + s}-O-R^FiveOr-(CH₂-)₂-S-R^FiveContains groups. Partially blocked polyfunctional polymers, ie polymers in which some but not all of the branches are blocked, also belong to the scope of the present invention.
Specific polyfunctionalizing agents include trifunctionalizing agents, ie compounds with z = 3. Preferred trifunctional agents include triallyl cyanurate (TAC) reactive with dithiol and 1,2,3-propanetrithiol reactive with polyvinyl ether. Agents with mixed functionality may also be used, i.e. agents containing each component, which is typically a separate component that reacts with both thiol and vinyl groups.
Other useful polyfunctionalizing agents include trimethylolpropane trivinyl ether and the polythiols described in US Pat. No. 4,366,307, US Pat. No. 4,609,762 and US Pat. No. 5,225,472. Mixtures of multifunctional agents can also be used.
Multifunctional agents having more than three reactive components (ie, z> 3) yield “star” polymers and hyperbranched polymers. For example, 2 moles of TAC can be reacted with 1 mole of dithiol to obtain a substance having an average functionality of 4. This material can then be reacted with diene and dithiol to obtain a polymer which can then be mixed with a trifunctionalizing agent to obtain a polymer blend having an average of 3 to 4 functionality.
The inventive polymers as described above have a wide range of average functionality. For example, the trifunctionalizing agent yields an average functionality of about 2.05-3.0, preferably about 2.1-2.6. A wider range of average functionality can be achieved by using tetrafunctional or higher polyfunctionalizing agents. Functionality can also be affected by factors such as stoichiometry, as is known to those skilled in the art.
[0024]
It is also contemplated that other functional groups can be used as substituents for the thiol groups described above and reacted with curing agents to prepare the multifunctional materials of the present invention. These functional groups include, for example, hydroxyl functional groups and amine groups. These thiol substituents can be used in reaction chemistry by those skilled in the sealant formulation art based on the examples below and the methodology described herein.
That is, according to one method of preparing the polyfunctional polymer of the present invention, (n + 1) moles of one or more compounds having formula IV, (n) moles of one or more compounds having formula V, And a z-functional polyfunctional agent are mixed in an amount sufficient to obtain a given molecular weight and functionality to prepare a reaction mixture. The mixture is then reacted in the presence of a suitable catalyst as described above to obtain a mercapto-terminated multifunctional polymer. The mercapto-terminated polyfunctional polymer capped analog is prepared by including about 0.05 to (z) moles of one or more suitable capping compounds VI in the starting reaction mixture. (z) The use of moles results in a well-sealed multifunctional polymer, while the use of lower amounts results in a partially blocked polymer.
[0025]
The polymer of the present invention preferably comprises at least one compound of formula IV and at least one compound of formula V, optionally with one or more suitable blocking compounds VI and / or VII, and Prepared by mixing with / or polyfunctionalizing agent and then adding the appropriate catalyst and conducting the reaction at a temperature of about 50 to about 120 ° C. for about 2 to about 24 hours. Preferably, the reaction is carried out at a temperature of about 70 to about 90 ° C. for about 2 to about 6 hours.
Since the reaction of the present invention is an addition rather than a condensation reaction, the reaction typically proceeds substantially completely, ie, the mercapto-terminated polymer of the present invention is prepared in approximately 100% yield. . Undesirable by-products are not produced at all or substantially. In particular, the reaction of the present invention does not result in appreciable amounts of malodorous cyclic by-products that are characteristic of some known methods for producing polythioethers. Furthermore, the polymers prepared according to the present invention are substantially free of residual catalyst.
The method for preparing the above-mentioned multifunctional original polymer is described in detail below.
[0026]
Preferably, the mercapto-terminated polymer is from about 500 poise at a temperature of about 25 ° C. and a pressure of about 101.1 kPa (760 mm Hg) when measured according to ASTM D-2849 § 79-90 using a Brookfield viscometer. Also have a low viscosity.
The mercapto-terminated polymer or mercapto-terminated polymer mixture as detailed herein is preferably from about 30% to about 90%, more preferably from about 40% to about 90% by weight in the polymerizable sealant composition of the present invention. It is present in an amount of 80% by weight, very preferably about 45% to 75% by weight, which is calculated on the basis of the total solid content of the composition.
The sealant or potting formulation of the present invention further comprises one or more suitable curing agents such as polyolefins, polyacrylates, metal oxides, polyepoxides and mixtures thereof. Curing agents useful in the polymerizable sealant composition of the present invention include polyepoxides or epoxy functional resins such as hydantoin diepoxide, bisphenol-A obtained epoxides, bisphenol-F epoxides. There are novolak type epoxides, aliphatic polyepoxides, and optional epoxidized unsaturated phenolic resins. Other useful curing agents include unsaturated compounds such as acrylic or methacrylic esters of commercially available polyols, unsaturated synthetic or naturally occurring resin compounds, TAC, and olefinic ends of the compounds of the present invention. There are derivatives. In addition, useful curing agents include organic and inorganic peroxides known to those skilled in the art (e.g., MnO₂) Can be obtained by oxidative coupling of thiol groups. The selection of a particular curing agent can affect the Tg of the cured composition. For example, a curing agent having a Tg significantly lower than the Tg of the polythioether of the present invention will lower the Tg of the cured composition.
Depending on the nature of the mercapto-terminated polymer (s) used in the composition of the present invention, the composition of the present invention will have about 90% to about 90% of its stoichiometric amount of the selected curing agent, based on -SH equivalents. 150%, preferably about 95 to about 125%.
[0027]
Useful fillers in the polymerizable composition of the present invention in aerospace applications include carbon black and calcium carbonate (CaCO_ThreeThere are fillers commonly used in the art, such as Examples of potting compound fillers include high band gap materials such as zinc sulfide and inorganic barium compounds. Preferably, the compositions of the present invention comprise from about 10 to about 70%, more preferably from about 10 to 50% by weight of the selected filler or filler mixture, based on the total weight of the composition.
The sealant and potting composition of the present invention may include one or more adhesion promoters. Suitable adhesion promoters include phenolic materials such as METHYLON phenolic resin available from Occidental Chemicals, epoxy, mercapto or amino functional silanes such as A-187 and A-1100 available from OSi Specialities. There are organosilanes such as Preferably, the adhesion promoter is used in an amount of 0.1 to 15% by weight, based on the total weight of the formulation of the present invention.
Typical substrates to which the sealant composition of the present invention is applied include titanium, stainless steel, aluminum; these anodized, primed, organic and chromate coated forms; epoxy, urethane, graphite, glass fiber composites, KEVLAR^RThere are acrylics and polycarbonates.
Preferably, the plasticizer is present in the sealant formulation of the present invention in an amount ranging from 1 to 8% by weight, based on the total weight of the formulation. Plasticizers useful in the polymerizable composition of the present invention include phthalate esters, chlorinated paraffins, hydrogenated terphenyls and the like.
The formulations of the present invention further comprise one or more solvents, such as isopropyl alcohol, in an amount of 0-15% by weight, preferably less than 15% by weight, more preferably less than 10% by weight, based on the total weight of the formulation. Can be included.
A typical sealant formulation is shown in Example 18.
[0028]
The cure time of the polymerizable sealant composition is significantly shortened by using an organic amine catalyst having a pKb of 10 or higher. Preferred organic amine catalysts are organic tertiary amines. Specific catalysts useful in the present invention are triethylenediamine, diazabicyclo (2,2,2) octane (DABCO) (preferred), diazabicycloundecene (DBU), 2,4,6-tri (dimethylaminomethyl). Phenol (DMP-30) and tetramethylguanidine (TMG). The reaction time when using an organic amine catalyst, especially an organic tertiary amine catalyst, is generally about 1 hour to about 20 hours, and this reaction time is significantly different from that when no amine catalyst is used. .
In general, the catalyst amount range is 0.05% to 3% by weight, based on the total weight of the starting reaction.
The sealant or potting formulation of the present invention is preferably cured at ambient temperature and pressure, although the formulations of the present invention can generally be cured at temperatures ranging from about 0 ° C to about 100 ° C.
In addition to the components described above, the polymerizable sealant composition of the present invention can optionally include one or more of the following components: pigments, thixotropic agents, retarders, and masking agents.
Useful pigments include conventional pigments in the art such as carbon black and metal oxides. The pigment is preferably present in an amount of about 0.1 to about 10% by weight, based on the total weight of the formulation.
A thixotropic agent such as fumed silica or carbon black is preferably used in an amount of about 0.1 to about 5% by weight, based on the total weight of the formulation.
[0029]
A further advantage of the sealant formulation according to the invention is its improved curing behavior. The degree of cure as a function of time for a sealant formulation is difficult to measure directly, but can be estimated by measuring the extrusion rate of the formulation as a function of time. Extrusion speed is the speed at which a mixed sealant formulation, ie, a sealant formulation that includes an accelerator system, is extruded from an applicator device. As the sealant formulation is mixed with the accelerator system, curing begins and the extrusion rate varies with time. That is, the extrusion speed correlates inversely with the degree of cure. When the degree of cure is low, the viscosity of the mixed ungelled sealant formulation is low and therefore the extrusion rate is fast. As the reaction approaches the end, the viscosity becomes very high and, therefore, the extrusion rate decreases. The extrusion rate can be measured according to AMS Method 3276 (section 4.5.10).
With reference to FIG. 1, the viscosity of certain known types of sealant formulations remains low during the extrusion time as the composition cures slowly. Such a blend has an extrusion curve that is quantitatively similar to curve A. Other known types of sealant formulations cure very rapidly and thus their viscosity increases rapidly. As a result, the extrusion rate decreases rapidly, as shown by curve B. Desirably, the mixed sealant formulation should have a low viscosity, i.e., a high extrusion rate, for a length of time sufficient to allow uniform application of the sealant formulation to the area requiring sealing. However, it should then be cured rapidly after application, i.e. its extrusion rate should be reduced rapidly. The sealant formulation according to the present invention is characterized by this desirable extrusion curve, as shown quantitatively by curve C.
[0030]
Sealant formulations according to the present invention, depending on the specific formulation, may have a high initial extrusion rate of 500 g / min or more, and at the same time about 5-10 g / min after a curing time of about 1 hour or It can have a lower extrusion rate of a lower level.
As shown in FIG. 2, the initial extrusion rate of the sealant containing the polymer of the present invention (Example 1, cured with an epoxy curing agent as described below) is about 550 g / min, followed by 70 minutes. Later it drops rapidly to about 20 g / min. As a comparison, a known polysulfide sealant (MnO₂) Has an initial extrusion rate of about 90 g / min and slowly decreases to about 20 g / min after 70 minutes.
Another preferred curable sealant formulation combines one or more plasticizers with the above-described mercapto-terminated polymer (one or more), a curing agent (one or more) and a filler (one or more). The use of plasticizers allows the polymerizable formulations of the present invention to include a mercapto-terminated polymer having a higher Tg than would normally be useful in aerospace sealants or potting compounds. The use of this would effectively reduce the Tg of the formulation of the present invention, and thus the low temperature flexibility of the cured polymerizable formulation was expected based on the Tg concept of the mercapto-terminated polymer alone. It is much more than wax low temperature flexibility.
[0031]
(Best Mode for Carrying Out the Invention)
The invention is illustrated in detail by the following non-limiting examples, which are presently representative of preferred embodiments. These examples are illustrative and do not limit the scope of the invention as claimed.
Example
In Examples 1-8, liquid polythioethers were prepared by stirring one or more dithiols together with one or more divinyl ethers and a trifunctional agent. The reaction mixture was then heated and a free radical catalyst was added. All reactions proceeded to substantial completion (approximately 100% yield).
Example 1
In a 2 L flask. 524.8 g (3.32 mol) diethylene glycol divinyl ether (DEG-DVE) and 706.7 g (3.87 mol) dimercaptodioxaoctane (DMDO) were mixed with 19.7 g (0.08 mol) triallyl cyanurate (TAC), Heated to 77 ° C. To the heated reaction mixture, 4.6 g (0.024 mol) of azobisnitrile free radical catalyst [VAZO^R 67 (2,2′-azobis (2-methylbutyronitrile)), commercially available from DuPont. The reaction proceeded to substantial completion after 2 hours, 1250 g (0.39 mol, yield) with a Tg of -68 ° C, a viscosity of 65 poise, a number average molecular weight of about 3165 grams / mole and a thiol functionality of 2.2. 100%) liquid polythioether resin was obtained. The resulting polymer was light yellow and had a low odor.
[0032]
Example 2
404.4 g (1.60 mol) PLURIOL in a 1 L flask^R E-200 divinyl ether and 355.88 g (1.94 mol) DMDO were mixed with 12.1 g (0.049 mol) TAC and reacted as in the examples. The reaction proceeded to substantial completion after 5 hours, yielding 772 g (0.024 mol, 100% yield) of resin having a Tg of −66 ° C. and a viscosity of 48 poise. The resulting polymer was yellow and had a low odor.
Example Three
In a 100 mL flask, 33.2 g (0.21 mol) DEG-DVE and 26.48 g (0.244 mol) 1,2-propanedithiol were mixed with 0.75 g (0.003 mol) TAC and heated to 71 ° C. 0.15 g (0.8 mmol) VAZO was added to the heated reaction mixture.^R 67 was added. The reaction proceeded to substantial completion after 7 hours, yielding 60 g (0.03 mol, 100% yield) of resin having a Tg of −61 ° C. and a viscosity of 22 poise. The resulting polymer had a noticeable PDT (propanedithiol) odor.
Example Four
In a 100 mL flask, 33.3 g (0.136 mol) of tripropylene glycol divinyl ether (DPE-3) and 27.0 g (0.170 mol) of dimercaptodiethyl sulfide (DMDS) were mixed with 0.69 g (0.003 mol) of TAC. And heated to 77 ° C. 0.15 g (0.8 mmol) VAZO was added to the heated reaction mixture.^R 67 was added. The reaction proceeded to substantial completion after 6 hours, yielding 61 g (0.028 mol, 100% yield) of polymer having a Tg of −63 ° C. and a viscosity of 26 poise.
[0033]
Example Five
113.01 g (0.447 mol) PLURIOL in a 250 mL flask^R E-200 divinyl ether and 91.43 g (0.498 mol) DMDO were mixed with 1.83 g (0.013 mol) 1,2,3-propanetrithiol (PTT) and reacted exothermically for 72 hours. The mixture was then heated to 80 ° C. 0.2 g (1 mmol) of VAZO was added to the heated reaction mixture.^R 67 was added. When the reaction mixture was maintained at 80 ° C., the reaction proceeded to substantial completion after 3 hours, yielding 200 g (0.06 mol, 100% yield) of polymer having a Tg of −66 ° C. and a viscosity of 55 poise. It was.
Example 6
14.0 g (0.055 mol) PLURIOL in a small jar^R E-200 divinyl ether, 6.16 g (0.0336 mol) DMDO and 5.38 g (0.0336 mol) DMDS were mixed with 0.42 g (0.017 mol) TAC (TAC heated briefly to melt) and 82 ° C. Heated. 0.2 g (0.001 mol) VAZO in the heated reaction mixture^R 67 was added. The reaction proceeded to substantial completion after 18 hours, yielding 26 g (8.4 mmol, 100% yield) of polymer having a Tg of −63 ° C. and a viscosity of 80 poise.
Example 7
13.55 g (0.054 mol) PLURIOL in a small jar^R E-200 divinyl ether, 10.44 g (0.057 mol) DMDO and 1.44 g (8.1 mmol) ethylcyclohexanedithiol (ECHDT) mixed with 0.40 g (1.6 mmol) TAC (TAC heated briefly and melted) And heated to 82 ° C. 0.2 g (0.001 mol) VAZO in the heated reaction mixture^R 67 was added. The reaction proceeded to substantial completion after 5 hours, yielding 26 g (8.1 mmol, 100% yield) of polymer having a Tg of −66 ° C. and a viscosity of 58 poise.
[0034]
Example 8
9.11 g (0.036 mol) PLURIOL in a small glass jar^R E-200 divinyl ether, 5.71 g (0.031 mol) DMDO, 1.52 g (7.8 mmol) ECHDT, 5.08 g (0.031 mol) DMDS and 4.11 g (0.024 mol) hexanediol divinyl ether (HD-DVE). It was mixed with 0.39 g (1.6 mmol) TAC (TAC heated briefly and dissolved) and heated to 82 ° C. To the heated reaction mixture 0.6 g (3.1 mmol) VAZO^R 67 was added. The reaction proceeded to substantial completion after about 45 hours, yielding 2.6 g (7.8 mmol, 100% yield) of polymer having a Tg of −66 ° C. and a viscosity of 304 poise. The resulting polymer had a cloudy appearance.
Each of the above polymers was evaluated for odor. The following scale was used: 3 = strong unpleasant odor; 2 = moderate odor; 1 slight odor; 0 virtually odorless.
The polymer described in Example 3 of US Pat. No. 4,366,307 was used as a control. This polymer (“control polymer”) had an odor of 3.
The results are as follows:
[Table 1]

With the exception of polymer 3, which had a strong odor, all of the above liquid polythioethers had almost no odor or only a moderate odor.
[0035]
Then, each polymer of Examples 1-8 was hardened. Curing was performed using an unblended resin containing a curing agent and a DABCO accelerator. The curing agent has the following composition:
Epoxy novolac¹(Equivalent 175.5) 22% by mass
Hydantoin epoxy²(Equivalent 132) 34% by mass
34% by mass of calcium carbonate
Carbon black 5% by mass
Silane adhesion promoter 5% by mass
¹DEN-431 available from Dow Chemical, Midland, Michigan
Epoxy novolac
²ARACAST XU A4 238 hydantoin epoxy available from Ciba-Geigy
[0036]
Each cured resin was evaluated for odor according to the procedure described above. Tg and% mass gain after 1 week immersion in JRF type 1 at room temperature and atmospheric pressure was also measured for each cured resin. Volume expansion and percent mass gain were determined for each cured resin as follows:
w₁ = Initial mass in air
w₂ = H₂Initial mass in O
w_Three = Final mass in air
w_Four = H₂Final mass in O
% Volume expansion = 100 x [(w₂ + w_Three)-(W₁ + w_Four)] / (w₁-W₂)
% Mass gain = 100 × (w_Three-W₁) / w₁
The results are shown in Table 1:
[Table 2]
table 1

As a comparison, the control polymer had an odor of 1-2 when cured.
[0037]
Example 9
Polythioethers having a number average molecular weight of 2100 and an average SH functionality F of 2.1 were prepared by mixing divinyl ether and dithiol as shown in Table 2 and reacting these materials as described above. Each unblended polythioether was then cured using 15 g of the above curing agent and 0.30 g DABCO. For each polythioether so prepared, the following properties were measured: viscosity (uncured product, poise p); Shore A hardness (cured product, Rex durometer value); 140 ° F. in JRF type 1 ( 60%) and% gain after 1 week at atmospheric pressure (cured); and Tg (cured, ° C). The results are as follows:
[Table 3]
Table 2

^a PLURIOL^R E-200 divinyl ether
^bButanediol divinyl ether
^cPolytetrahydrofuran divinyl ether
^dHexanedithiol
[0038]
From the table above it is clear that the following combination of divinyl ether and dithiol yields a polythioether having good fuel resistance and low temperature flexibility when cured: PLURIOL^R E-200 / DMDO; and DEG-DVE / DMDO. Other potentially useful combinations include DEG-DVE / ECHDT; DEG-DVE / HDT; PLURIOL^R E-200 / ECHDT ； PLURIOL^R E-200 / HDT; and poly-THF / DMDO. PLURIOL^R E-200 / DMDS also has excellent fuel resistance and low temperature flexibility when cured, but the unblended product does not remain liquid for a long time.
[0039]
Example Ten: PLURIOL^ROf DMDS to DMDM polymer
Four liquid polythioether polymers were prepared as described above. Each polymer has the following composition (numbers shown are molar equivalents):
[Table 4]

To each of these polymers, 0.2 molar equivalents of TAC were added to give a number average molecular weight of about 3000 and SH functionality F of 2.2. Each resulting unblended polymer was cured as in Example 9 (15 g hardener composition and 0.30 g DABCO). For each polymer, the following properties were measured: Tg (resin, ° C); Tg (cured, ° C); viscosity (p);% expansion in JRF type 1;% mass gain in JRF type 1 And% mass gain in water. The results are shown in Table 3.
[Table 5]
Table 3

Each of the above polymers showed excellent fuel resistance. Polymers 1 and 2 also exhibited excellent low temperature flexibility, especially when tested according to AMS 3267 § 4.5.4.7.
[0040]
Example 11: PLURIOL^ROf ECHDT to / DMDO polymer
Four liquid polythioether polymers were prepared as described above. Each polymer has the following composition (numbers shown are molar equivalents):
[Table 6]

Each of these polymers had a number average molecular weight of about 3000 and an SH functionality F of 2.2. Each resulting unblended polymer was cured as in Example 10. For each polymer, the following properties were measured: Tg (resin, ° C); Tg (cured, ° C); viscosity (p);% expansion in JRF type 1;% mass gain in JRF type 1 And% mass gain in water. The results are shown in Table 4.
[Table 7]
Table 4

Each of the above polymers exhibited excellent fuel resistance and low temperature flexibility.
[0041]
Example 12
In a 250 mL 3-neck flask equipped with a stirrer, thermometer and condenser, 87.7 g (0.554 mol) DEG-DVE and 112.3 g (0.616 mol) DMDO were mixed and 77 ° C (about 170 ° F) Heat to. To the resulting mixture, 0.8 g (4.2 mmol) of VAZO^R67 catalyst is added. The reaction mixture is reacted at 82 ° C. (about 180 ° F.) for about 6 hours to yield 200 g (0.06 mol, 100% yield) low viscosity liquid polythioether resin having a thiol equivalent of 1625 and an SH functionality F of 2.0. Get.
Example 13
In a 250 mL 3-neck flask equipped with a stirrer, thermometer and condenser, mix 26.7 g (0.107 mol) TAC, 56.4 g (0.357 mol) DEG-DVE and 117.0 g (0.642 mol) DMDO, Heat to 77 ° C (about 170 ° F). To the resulting mixture, 0.8 g (4.2 mmol) of VAZO^R67 catalyst is added. The reaction mixture is reacted at 82 ° C. (about 180 ° F.) for about 6 hours to give 200 g (0.07 mol, 100% yield) of a highly viscous liquid polythioether resin having an equivalent weight of 800 and an SH functionality F of about 3.5. Get.
[0042]
Example 14: Sealant composition
A sealant composition containing the DMDO / DEG-DVE polythioether polymer of Example 1 was formulated as follows (amount based on parts by weight).
DMDO / DEG-DVE Polythioether 100
Calcium carbonate 60
Magnesium oxide 1
Phenolic resin^Three                                  1
DMP-30 1
Isopropyl alcohol 3
^ThreeMETHYLON 75128 phenolic resin available from Occidental Chemical
The above blended polymers were thoroughly mixed with the epoxy resin curing agents of Examples 9 to 11 at a mass ratio of 10: 1 and cured at ambient temperature and ambient humidity. Tensile strength and elongation were evaluated according to ASTM 3269 and AMS 3276. The die used to make the test sample is described in ASTM D412. The die used to make test samples for tear strength testing is described in ASTM D1004. The following physical properties were obtained in the cured composition:
Hardness at 25 ° C 60 Shore A
Tensile strength at break 379.0 Pa (550 psi)
Elongation at break 600%
Infeed tear strength 17.86 kg / cm (100 p / i)
Low temperature flexibility passed
(AMS 3267§4.5.4.7)
[0043]
Example 15: Sealant composition
A sealant composition containing the ECHDT / DEG-DVE polythioether polymer of Example 9 was formulated as follows (amount based on parts by weight).
ECHDT / DEG-DVE polythioether 100
Calcium carbonate 54
Hydrated aluminum oxide 20
Magnesium oxide 1
Phenolic resin of Example 14 1
Hydrogenated terphenyl plasticizer 6
DMP-30 1
Isopropyl alcohol 3
The above blended polymers were thoroughly mixed with the epoxy resin curing agents of Examples 9-12 at a mass ratio of 10: 1 and cured at ambient temperature and ambient humidity. Sagano's physical properties were obtained in the cured composition:
Hardness at 25 ° C 72 Shore A
Tensile strength at break 379.0Pa (550psi)
Elongation at break 450%
Cutting tear strength 15.18 kg / cm (85p / i)
Low temperature flexibility passed
[0044]
Example 16: OH-terminated blocked polythioether
275.9 g (1.09 mol) PLURIOL in a 500 mL flask^R E-200 divinyl ether, 174.7 g (0.95 mol) DMDO, 28.7 g (0.30 mol) 3-mercaptopropanol and 1.83 g (7.3 mmol) TAC were mixed. The mixture is heated to 70 ° C. and 2.3 g (12 mmol) of VAZO^R 67 was added slowly. The reaction mixture was stirred and heated at 85-90 ° C. for 4 hours to give 480 g (0.15 mol, 100% yield) polymer (number average molecular mass = 3200, OH functionality F = 2.05) with an OH equivalent weight of 1670. )
Example 17: OH-terminated blocked polythioether
In a 250 mL flask, 104.72 g (0.57 mol) DMDO, 80.73 g (0.51 mol) DEG-DVE and 14.96 g (0.13 mol) butanediol monovinyl ether were mixed and heated to 75 ° C. To the heated mixture, 0.60 g (3 mmol) of VAZO^R 67 was added slowly. The reaction mixture is stirred and heated at 75-85 ° C. for 6 hours to give a clear, almost colorless polymer with a very low odor of 200 g (0.064 mol, 100% yield) and a viscosity of 79 poise at 20 ° C. It was. OH equivalent 1570 (number average molecular mass = 3200, OH functionality F = 2.00).
[0045]
Example 18: Sealant composition
A sealant composition containing the DMDO / DEG-DVE polythioether polymer of Example 1 was formulated as follows (amount is% by mass).

^FourDABCO triethylamine, diazabicyclo (2,2,2) octane, available from Air Products & Chemical.
^FiveMETHYLON 75108 phenolic resin available from Occidental Chemical.
⁶The phenol / polysulfide adhesion promoter was a polymer prepared according to Example 31 of about 31% VARCUM 29202 phenolic resin, 66% Thiokol LP-3 polysulfide and 3% US Pat. No. 4,623,711 (based on 1 mole of polysulfide 1 mole of dithiol) at a temperature of about 150 ° F. (65 ° C.) for 45 minutes, then heated to 230 ° F. (110 ° C.) for 45-60 minutes, then 230 ° F. ( 110 ° C.) for 165 minutes.
⁷TYZOR TBT titanate available from E.I.duPont de Nemours Company.
⁸A-1100 amino-functional silane available from OSi Specialities, Inc.
[0046]

⁹EPON 828 bisphenol A diglycidyl ether available from Shell Chemical.
^TenDEN431 epoxy novolac available from Dow Chemical.
¹¹HB-40 plasticizer available from Monsanto Co.
¹²Ferbam 76% WDG carbamate available from Cabot Corp.
¹³Epoxy functional silane A-187 available from OSi Specialities, Inc.
Each component of the base composition was mixed sequentially in the order listed. In a separate container, each of the accelerator components were mixed sequentially in the order listed. A sealant formulation according to the present invention was prepared by mixing 100 g of the base composition with 18.5 g of the above accelerator.
[0047]
(Industrial utility)
The compositions of the present invention are useful in aerospace applications such as aerospace sealants and lining agents for fuel tanks, and as electropotting or encapsulating compounds. The aerospace sealant material according to the present invention may exhibit properties such as extreme temperature performance, fuel resistance and flexibility strength. The formulations of the present invention are well suited as potting compounds that encapsulate electrical and electronic components that can experience temperature extremes, chemically harsh environments and mechanical vibrations.
The above description is illustrative of specific embodiments of the present invention and is not limited to the implementation thereof. It is intended that the scope of the invention be limited by the claims, including all equivalents.
[Brief description of the drawings]
FIG. 1 is a line graph of extrusion rate (E) versus time (T) for a sealant composition of the present invention compared to the extrusion rate curve for a known type of sealant composition.
FIG. 2 is a semi-log graph of the extrusion rate curve of the polythioether sealant composition (♦) of the present invention and the prior art polysulfide sealant composition (■).

Claims (6)

(a) a base composition comprising DMDO / DEG-DVE polythioether prepared by reacting diethylene glycol divinyl ether (DEG-DVE), dimercaptodioxaoctane (DMDO) and triallyl cyanurate (TAC) ; and ,
(b) an accelerator composition comprising a curing agent comprising a combination of bisphenol A diglycidyl ether and an epoxy novolac ;
A formulation prepared from ingredients including The formulation of claim 1, wherein the molar ratio of reactants in the base composition (a) is DEG-DVE: DMDO: TAC = 3.32 mol: 3.87 mol: 0.08 mol. The formulation of claim 1, wherein the base composition comprises 55.466% by weight of the polythioether, based on the total weight of the base composition. The formulation of claim 1, wherein the accelerator composition comprises 26.525 wt% bisphenol A diglycidyl ether and 17.684 wt% epoxy novolac, based on the total weight of the accelerator composition. . The formulation of claim 1, wherein the weight ratio of the base composition (a) to the accelerator composition (b) is 100: 18.5. The formulation according to any one of claims 1 to 5, which is a sealant formulation.

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