TW588057B - Method for shortstopping polymerization processes in the manufacture of synthetic rubbers - Google Patents

Abstract

This invention is related to a new shortstopping combination for use in stopping free radical and redox initiated polymerization is the combination of hydroxylamine (free base) (HA) and i-propylhydroxylamine (IPAH). It is more effective as related N-alcylated-hydroxylamines with regard to mooney stability. The combination is not corrosive to metals used in commercial equipment for emulsion polymerization and prevents the rust formation and the formation of nitrosamines, coagulate and precipitate.

Description

588057 V. Description of the invention (1) The present invention relates to an improved method for quick-stop polymerization when manufacturing synthetic rubber (such as a butadiene-styrene-acrylidine copolymer). Latex polymerization initiated by free radicals or redox is usually terminated by mixing latex and shortstop, which is used to prevent free radical or oxygen reduction reaction from continuing. The polymerization must be terminated to obtain a product having the desired characteristics. The properties of the produced polymer are the same according to its monomer conversion rate. Free radical or redox polymerization is mainly used in latex polymerization to make elastic materials, such as styrene-butadiene rubber (sbr), butadiene rubber (BR), and acrylonitrile-butadiene rubber (NBR). Many studies hope to find good shortstops, and many useful compounds have been found. However, the compounds currently used have certain disadvantages and are generally not suitable for all polymerization systems. Some conventional traditional short-stop agents such as carbamate, hydroquinone, hydracine, polysulfide, nitrate Compounds, N · alicyclic hydroxylamine and / or others (us 5.348 372 us 3.296.m; EP 656 371; EP-AO 437 293; DE-A-15 95 177) and the like. N-monobutylhydroxylamine is suggested as a shortstop, especially isopropylhydroxylamine (IPHA) (in US 5.384.372; WO 98/51714). In this example, no nitrosoamine and its precursors were present in the final rubber. The disadvantage of this method is that this process is not a complete quick stop because it has a drift in Mooney viscosity and forms agglomerates and precipitates in the recovery tank. Another problem is the formation of secondary amines when N, N-dialicyclic hydroxylamines and / or carbamates are used. This problem has been caused by the use of hydroxylamine (HA) (free base) and isopropyl amine mixed paper size applicable to Chinese National Standard (CNS) A4 specifications (210X297 mm) 588057 A7 ____B7 _ V. Invention ^ ~ 'Compound as Quick stop agent. In this way, latexes without agglutinates and precipitates, and rubbers without nitrosoamines and their precursors can be made. No shift in Mooney viscosity was found in latex or rubber. The present invention relates to a method for stopping emulsification polymerization initiated by free radicals, which comprises adding a short-stop agent composed of a mixture of isopropylhydroxylamine (IpAH) and hydroxylamine (HA) (free base). According to the present invention, a process for preparing a synthetic rubber is shown. In an aqueous medium, the rubber polymerization of conjugated diene and monoolefin caused by free radicals and redox reactions is performed by adding hydroxylamine (free base) (HA) and isopropyl A shortstop composed of hydroxylamine (IPAH) to neutralize the polymerization reaction. This process is characterized by a mixture of hydroxylamine (free base) (HA) and isopropylhydroxylamine (IPAH) as the short-stop agent, which contains: a) Calculated based on 100 parts of the initial fed monomer as 0.00 1 to 0499 parts by weight of HA, b) 0499 to 001 parts by weight of IPHA per 100 parts of the initially fed monomer. Preferably, a mixture consisting of 0.01 to 0.2 parts by weight of HA and 0.2 to 0.01 parts by weight of IPAH is added. The mixed shortstop is added in an amount of 0.005 to 0.2 parts by weight per 100 parts by weight of the initial monomer (phm), and preferably 0.1 to 0.4 parts by weight of the initial monomer (phm). This shortstop is added using the traditional technique of rubber polymerization. Preferably, the original solution (50% HA, 15% IPHA) and / or an aqueous solution of the shortstop mixture is added when the desired conversion is obtained. Polymerization This paper is sized for China National Standard (CNS) A4 (210X297 mm)

588057 V. Description of the invention (3). The polymerization system used is preferably styrene butadiene polymerization. The practicality of the present invention is further illustrated by adding the following examples, which are provided for illustration only and are not intended to limit the scope of the present invention. The term "parts" in the following examples refers to parts by weight of the short-stopper per 100 parts of the monomer fed into the monomer. In Table 1 of the Examples, we performed the polymerization using could soap styrene ethyl butadiene Free radical or redox-initiated rubber polymerization: Table 1 All polymerization of water fatty acid soap is performed at 5 ° C to achieve a monomer polymer conversion rate of about 60%. 〇Then add a shortstop. Example 1 Dimethyldithiocarbamate in a weight ratio of 90/1 〇 This paper size is applicable to China National Standard (CNS) A4 specifications (21〇 < 297 public love)

..... ......... (Please read the notes on the back before filling out this page), Ke 588057 Description of Invention (4 (dtc), and diethylhydroxylamine ( DEHA) Mix the diluted aqueous solution for quick stop. Examples 2, 3, 4, 5, 6, 7, and 8 use 50% hydroxylamine (HA) and 15% isopropyl (Please read the precautions on the back before filling this page) Propanolamine (IPAH) was mixed into a 22% aqueous solution for quick-stop reaction, and the results are shown in Table 2. The mixture of these two compounds was formed into batches or added online, with or without the original compound and deionized water. Active compounds The preferred concentration in water ranges from 1% to 25%. When the desired degree of polymerization is reached, the shortstop is added directly to the latex. The presence of nitrosoamine is the BGA method, using a thermal energy analyzer, gas Phase analysis method. Table 2 Example DTC / D EHA (phm) HA (phm) IPAH (phm) Nitrosamine * (ppb) Mooney agglomerates / precipitates (% phr) Latex monomers short-stopped Latex recovered 1 0.2-12.7 * 1 48 52 4.5 2-0.1 0.1 nd * 3 48 48 0 3-0.01 0.19 nd 48 49 0 4-0.08 0.12 nd 48 48 0 5-0 .19 0.01 nd 48 47 0 6-0.02 0.02 nd 48 48 0 7-0.001 0.449 nd 48 48 0 8-0.449 0.001 nd 48 48 0 * Detection: N-nitrosodimethylamine, N-nitrosodiamine Ethylamine, N-nitrosodipropylamine, N-nitrosodibutylamine, N-nitrosopiperidine, N-nitrosopyrrolidine 5 N-nitrosomorpholine * 1) N in rubber -Overview of Nitrosodimethylamine and N-Nitrosodiethylamine This paper size applies Chinese National Standard (CNS) A4 (210X297 mm) 588057 5. Description of the invention (5) * 2) After monomer recovery Detect agglutinates / precipitates * 3) Undetectable Add 50% hydroxylamine (free base) (hA) and i 5% isopropylhydroxylamine aqueous solution to the original solution for quick stop reaction. Example 1 The use of a conventional short-stop agent. As a result, a high content of schistolidamine was detected in the rubber, and a high amount of dimethyldithiocarbamate (DTC) and N, N-diethylhydroxylamine ( DEHA) agglutinate (example 丨). Surprisingly, the results of using hydroxylamine (HA), isopropylhydroxylamine (1), and human 11) did not detect nitrosoamine and agglutination, while producing a very stable latex that did not drift (Examples 2-8). The advantage of the present invention is that this is a better quick-stop method, and at the same time, it has a better prevention effect on the block formed in the gas phase and the liquid phase (latex). In addition, the amount of the two compounds that are used to form a short-stop agent is less than the amount of any single compound, indicating that the two compounds have a synergistic effect when the short-stop reaction is performed. This paper size applies to Chinese National Standards (CNs) A4 (210X297 mm)

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Claims (1)

Application for amendment of patent scope VI. Application for patent scope No. 090127176 Patent application amendment date: July 1992 1. A method of quick-stop free radical or oxygen spine, Luodian & human_ X lice reduction reduction polymerization, which A type of mixed δ composed of a worker month (ΗΑ) and isopropylamine (ΙρΑΗ) was added to the polymerization mixture to achieve the expected conversion rate. 2. The method as claimed in the patent application scope, wherein the mixture is added in an amount of 0.005 to 0.2 parts by weight per 100 parts by weight of the initial monomer (Phm). 3. The method as claimed in claim No. β, wherein the mixture is from 0.0000 to 0499 parts by weight of hydroxylamine (VIIA) and 0.499 to 0.001 parts by weight of isopropylhydroxylamine (ΙρΑΗ) based on the initial monomer (phm). ) κ composition. 4. The method according to item 3 of the patent application, wherein the mixture is composed of 0.001 to 0.2 parts by weight of hydroxylamine (VIIA) and 0.2 to 0.1 parts by weight of isopropyl hydroxylamine (based on the initial monomer (phm) IPαη). 5. As in the method of applying for item 1 of the patent scope, the short-stop agents are used at the original concentrations of the following two ingredients, namely 15% IPAΗ in water and 50% ΗΑ in water.