JPS6150484B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a crosslinked vinyl chloride polymer. As is well known, vinyl chloride polymers are inexpensive and flame retardant, and when used in combination with plasticizers such as phthalate esters, they can be used to create molded products with a wide range of physical properties from hard to soft. It is one of the most widely used general-purpose polymers. However, these vinyl chloride polymers have a drawback of having a low softening temperature. For this reason, conventional methods for raising the softening temperature of vinyl chloride polymers and improving their heat resistance include chemical crosslinking using organic peroxides, electron beam crosslinking using electron beams, and organic silanes containing amino groups. Several methods have been proposed and used. However, in the case of crosslinking methods using organic peroxides, the vinyl chloride polymer decomposes at the same time as crosslinking, resulting in problems such as a significant decrease in thermal stability, although heat resistance is slightly improved by crosslinking. occurs, making it difficult to put it into practical use. In addition, in the case of the electron beam crosslinking method, although the performance of the crosslinked product is better than that of the product obtained by the above chemical crosslinking method, there is a limit to the thickness of the molded product that can be crosslinked. ,
In the case of thick molded bodies, sufficient crosslinking may not be possible. Furthermore, in the case of a method using an amino group-containing organic silane, a dehydrochlorination reaction occurs from the vinyl chloride polymer as a result of the reaction between the amino group-containing organic silane and the vinyl chloride polymer. There have been disadvantages such as poor thermal stability of the crosslinked vinyl chloride polymer. Therefore, the present inventors conducted intensive research to find a new crosslinking method for vinyl chloride polymers that can eliminate the drawbacks associated with the above conventional methods. The vinyl chloride polymer can be easily and reliably crosslinked by reacting it with an organic silane having an organic group containing a mercapto group, and then exposing the reaction product to moisture in the presence of a silanol condensation catalyst. It has been found that a crosslinked product having good heat resistance and thermal stability can be obtained. In addition, by adding and blending an organic lead compound, an inorganic lead compound, or a mixture thereof as a stabilizer before or after the reaction between the vinyl chloride polymer and the organic silane, a high degree of crosslinking and high heat resistance and thermal stability can be achieved. It has been found that a crosslinked product with very good properties can be obtained. Based on these findings, we have arrived at the present invention. That is, the present invention relates to (1) a vinyl chloride polymer and a compound having the general formula RR'SiY ₂ (wherein R is an organic group containing at least one mercapto group, Y
is a hydrolyzable organic group, R' is a hydrocarbon group or the same as Y), and the reaction product is then exposed to moisture in the presence of a silanol condensation catalyst to crosslink it. and (2) the vinyl chloride polymer and the general formula RR′SiY ₂ (wherein, R is an organic group containing at least one mercapto group, and Y is an organic group containing at least one mercapto group; Before or after the reaction with an organic silane represented by a hydrolyzable organic group (R' is a hydrocarbon group or the same as Y), an organic lead compound, an inorganic lead compound, or a mixture thereof is added and mixed as a stabilizer, The present invention relates to a method for producing a crosslinked vinyl chloride polymer, which is characterized in that the vinyl chloride polymer mixture is then crosslinked by exposing it to moisture in the presence of a silanol condensation catalyst. The present invention will be explained in detail below. First, a vinyl chloride polymer and the general formula RR'SiY ₂ (where R is an organic group containing at least one mercapto group, Y is a hydrolyzable organic group, and R' is a hydrocarbon group or the same as Y) ) is reacted with an organic silane represented by As the vinyl chloride polymer, a polyvinyl chloride homopolymer or a copolymer of vinyl chloride and a comonomer can be used. Comonomers include vinyl esters such as vinyl acetate and vinyl stearate; vinyl halides such as vinyl bromide and vinyl fluoride; vinylidene halides such as vinylidene chloride; acrylic acid, methacrylic acid,
Acids such as maleic acid and fumaric acid; esters of the various acids mentioned above, such as ethyl acrylate and butyl acrylate; ethylenically unsaturated hydrocarbons such as ethylene and propylene; acrylonitrile and the like can be used. The organic silane used in the present invention is a compound represented by the above general formula, ie, RR'SiY ₂ .
In this formula, R is at least one mercapto group (-
It is an organic group containing SH), which is an appropriate combination of sulfur, hydrogen, carbon, and oxygen. A suitable R is, for example, the HSC ₃ H ₆ group. Moreover, Y is a hydrolyzable organic group. Suitable Y is, for example, an alkoxy group such as a methoxy group, an ethoxy group, a butoxy group;
Acyloxy group such as formyloxyacetoxy group; propionoxy group; -ON=C(CH ₃ ) ₂ ,
-ON=C( _{CH3 ) C2H5} , -ON=C( _C2H5 ) ₂ , etc. oximo group _{; -NHC2H5 ,} etc. alkylamino group; -NH( _{C6H5 )} , etc. An arylamino group, etc. Note that Y in the above general formula may be the same or different. Further, R' is the same as Y or a monovalent hydrocarbon group such as methyl, ethyl, propyl, tetradecyl, octadecyl, phenyl, benzyl, tolyl. Among the above-mentioned organic silanes, compounds in which R' is the same as Y and are in the form of RSiY ₃ are particularly preferred. Further, the reaction between the vinyl chloride polymer and the organic silane can be carried out by bringing both reactants into contact at a temperature of 100°C or higher, preferably 130 to 200°C. The reaction can be carried out using a solvent, but it can also be carried out without using a solvent. It is generally preferred to carry out the reaction without the use of a solvent. If a solvent is not used, the vinyl chloride polymer and the organic silane are intimately mixed using, for example, a heated two-roll kneader or extruder at a temperature higher than the melting point of the vinyl chloride polymer. It is preferable to carry out the reaction simultaneously. Furthermore, the amount of organic silane used in the present invention is
Although it varies depending on the desired degree of crosslinking of the vinyl chloride polymer, it is generally 0.1 to 15 parts by weight, preferably 1 to 7.5 parts by weight, based on 100 parts by weight of the vinyl chloride polymer. By the way, before, during or after the reaction of the vinyl chloride polymer and the organic silane as described above, an organic lead compound or an inorganic lead compound as detailed below may be used.
Or Ba/Zn-based compounds, Ca/Zn-based compounds, Cd/
Stabilizers such as Ba-based compounds, zinc stearate, calcium stearate; Plasticizers detailed below;
Fillers such as chalk, calcite, china clay, lubricants, etc. can be added as appropriate. It is preferable to add an organic lead compound, an inorganic lead compound, or a mixture thereof as a stabilizer before or after the reaction between the vinyl chloride polymer and the organic silane. The organic lead compounds and inorganic lead compounds used in the present invention include lead oxide, red lead, lead sulfate, tribasic lead sulfate, basic lead sulfite, lead silicate, lead phosphite, and dibasic phosphite. Examples include lead, lead carbonate, lead stearate, lead phthalate, lead octylate, lead 2-ethylhexoinate, and tribasic lead sulfate and dibasic lead phosphite are particularly preferred. The amount used is generally 0.1 to 50 parts by weight, preferably 2 to 20 parts by weight, per 100 parts by weight of the vinyl chloride polymer. In addition, examples of the plasticizer for the vinyl chloride polymer used in the present invention include phthalic acid esters such as di-2-ethylhexyl phthalate, di-n-octyl phthalate, and diisodecyl phthalate; aliphatic diesters such as dioctyl adipate; Basic acid esters; phosphate esters such as tricresyl phosphate; epoxidized products such as epoxidized soybean oil; trioctyl trimellitate; chlorinated paraffins, etc.; these compounds can be used alone or in a mixture of two or more. can. Next, a reaction product obtained by the reaction of a vinyl chloride polymer and an organic silane, or an organic lead compound, an inorganic lead compound, or a mixture thereof before or after the reaction of a vinyl chloride polymer and an organic silane. A vinyl chloride polymer mixture mixed with
After shaping by extrusion or other shaping methods, it is crosslinked by exposure to moisture in the presence of a silanol condensation catalyst. The silanol condensation catalyst may be blended with the vinyl chloride polymer before reacting with the organosilane, or may be blended with the vinyl chloride polymer before or during the above-mentioned extrusion or other molding method, or in some cases after the molding. The silanol condensation catalyst can be made to exist in the molded article by a method such as bringing the silanol condensation catalyst into contact with the molded article directly or as an aqueous solution, so that the desired effect can be exerted. As mentioned above, when a silanol condensation catalyst is blended with a vinyl chloride polymer or a reaction product of a vinyl chloride polymer and an organic silane before or during molding by the above extrusion or other molding method. The catalyst may be in the form of a single substance or a master batch in which a large amount is mixed in a vinyl chloride polymer. Also,
Blending a vinyl chloride polymer mixture with an organic lead compound and an inorganic lead compound before or during the reaction of a vinyl chloride polymer and an organic silane before or during molding by the above extrusion or other molding method. The form of the catalyst when blending may be the same. As a method of exposing the molded product to moisture, normally a method of exposing it to the air and crosslinking with the moisture present in the air can be used, but if desired, a method of using an air with increased humidity or a method of using water with increased humidity can be used. Methods of increasing the rate of crosslinking can also be used, such as immersion in water or raising the ambient temperature during exposure to moisture. Incidentally, the silanol condensation catalyst used in the present invention includes commonly known metal salts of carboxylic acids, organometallic compounds such as titanium chelates, alkyltitanates, alkylzirconates, organic bases, and organic acids. Can be mentioned. Typical examples of silanol condensation catalysts include dibutyltin dilaurate, dibutyltin dioctoate, dibutyltin diacetate, stannous octoate, stannous oleate, lead octoate, zinc 2-ethylhexonate, cobalt naphthenate, cobalt octoate, - Iron ethylhexonate, bis(acetylacetonyl) diisopropyl titanate, diisopropoxytitanium di(ethylacetoacetate), tetrabutyl titanate, tetrabutyl zirconate, ethylamine, hexylamine, dibutylamine, piperidine, octodecylamine acetate tartrate, P-toluenesulfonic acid and acetic acid. Preferred catalysts are dibutyltin dilaurate and dibutyltin diacetate. As explained above, in the present invention, a vinyl chloride polymer is reacted with an organic silane having an organic group containing at least one mercapto group, and the reaction product is then reacted in the presence of a silanol condensation catalyst. exposed to moisture. Therefore, according to the present invention, a vinyl chloride polymer can be easily and reliably crosslinked without side reactions such as dehydrochlorination reaction, and a crosslinked product having good heat resistance can be obtained. In addition, when adding an organic lead compound, an inorganic lead compound, or a mixture thereof as a stabilizer before or after the reaction between the vinyl chloride polymer and the organic silane,
A crosslinked product with a high degree of crosslinking and very good heat resistance can be obtained. Furthermore, a sufficiently crosslinked product can be obtained substantially regardless of the thickness of the molded product. Furthermore, the crosslinked polymer obtained by the production method of the present invention has good thermal stability. That is, as is clear from the results of the following examples, the heat resistance (softening temperature) is improved by crosslinking, and the thermal stability of the polymer itself also shows good values. Even if the softening temperature of a polymer increases, if the thermal stability is low, it is virtually impossible to perform thermal processing, etc. However, since the polymer of the present invention has good thermal stability, can be used effectively. EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples. [Example 1] The following ingredients were kneaded at 160°C for 10 minutes using a two-roll kneader, and then formed into pellets using a pelletizer. Polyvinyl chloride powder (=1100) 100 parts by weight Di-2-ethylhexyl phthalate 50 〃 Ba/Zn stabilizer 5 〃 Zinc stearate 1 〃 Add 5 parts of HSC ₃ H ₆ Si (OCH ₃ ) ₃ uniformly to this pellet It was dispersed and extruded using an 18 mm screw extruder. This extruded sample was crosslinked by immersing it in an aqueous solution containing 5% by weight of dibutyltin dilaurate at a temperature of 80° C. for 24 hours. The gel fraction of the crosslinked sample was measured in tetrahydrofuran at 50°C. In addition, a thermal stability test was conducted at 180°C according to the method of JISK6723. [Example 2] The process was carried out in the same manner as in Example 1 except that a Ca/Zn stabilizer was used instead of the Ba/Zn stabilizer, and the gel fraction and thermal stability were changed in the same manner as in Example 1. It was measured. [Example 3] The process was carried out in the same manner as in Example 1 except that a Cd/Ba type stabilizer was used instead of the Ba/Zn type stabilizer, and the gel fraction and thermal stability were changed in the same manner as in Example 1. It was measured. [Comparative Example 1] The same treatment as in Example 1 was carried out except that HSC ₃ H ₆ Si (OCH ₃ ) ₃ was not added, and the gel fraction and thermal stability were measured in the same manner as in Example 1. [Comparative Example 2] NH ₂ C ₃ H ₆ Si instead of HSC ₃ H ₆ Si (OCH ₃ ) ₃
The treatment was carried out in the same manner as in Example 1 except that (OC ₂ H ₅ ) ₃ was used, and the gel fraction and thermal stability were measured in the same manner as in Example 1. The results obtained in Examples 1-3 and Comparative Examples 1-2 are shown in Table 1 below.

[Example 4]

The following ingredients were kneaded at 160°C for 10 minutes using a two-roll kneader, and then formed into pellets using a pelletizer. Polyvinyl chloride powder (=1100) 100 parts by weight Di-2-ethylhexyl phthalate 50 Tribasic lead sulfate 5 Lead stearate 1 ₅ parts of HSC ₃ H ₆ Si (OCH ₃ ) are uniformly dispersed in this pellet This was extruded using an 18 mm screw extruder. This extruded sample was crosslinked by immersing it in an aqueous solution containing 5% by weight of dibutyltin dilaurate at a temperature of 80° C. for 24 hours. The gel fraction of the crosslinked sample was measured in tetrahydrofuran at 50°C. In addition, a thermal stability test was conducted at 180°C according to the method of JISK6723. [Example 5] The same process as in Example 4 was carried out except that dibasic lead phosphite was used instead of tribasic lead sulfate, and the gel fraction and thermal stability were the same as in Example 4. It was measured. The results obtained in Examples 4-5 are shown in Table 2 below.

[Table] As is clear from Table 2 above, in the case of Examples 4 to 5, not only the gel fraction is quite high, but also the thermal stability is not only in the case of Comparative Examples 1 to 2, but also in the case of Example 1. This is much better than the case of ~3.

Claims (1)

[Claims] 1 Vinyl chloride polymer and the general formula RR'SiY ₂ (wherein, R is an organic group containing at least one mercapto group, Y is a hydrolyzable organic group, and R' is a hydrocarbon group) or the same as Y), and the subsequent reaction product is exposed to moisture in the presence of a silanol condensation catalyst to crosslink it. Method. 2. Vinyl chloride polymer and general formula RR'SiY ₂ (However, R is an organic group containing at least one mercapto group, Y is a hydrolyzable organic group, and R' is a hydrocarbon group or the same as Y) Before or after the reaction, an organic lead compound, an inorganic lead compound, or a mixture thereof is added and mixed as a stabilizer to the organosilane represented by the formula, and then the reaction product is exposed to moisture in the presence of a silanol condensation catalyst. 1. A method for producing a crosslinked vinyl chloride polymer, which comprises crosslinking.