JPS631993B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a crosslinkable rubber or plastic composition using an alkoxysilane composite in which hydrolysis of the alkoxy group of an alkoxysilane compound is suppressed. BACKGROUND ART In recent years, a so-called water crosslinking method has been proposed for crosslinking polymeric compounds, such as rubber or plastic, by using an alkoxysilane compound and bringing it into contact with water or moisture. According to this method, rubber or plastic can be crosslinked without using various large-scale equipment unlike other conventional methods. As alkoxysilane compounds used in this method, for example, vinyl group-containing alkoxysilanes, amino group-containing alkoxysilanes, mercapto group-containing alkoxysilanes, etc. are known. Specifically describing each of these silane compounds, vinyl group-containing alkoxysilane compounds include alkoxyvinylsilane and methalylalkoxysilane, and in the case of these silanes, organic peroxides such as dicumyl peroxide or benzoyl peroxide are This method uses an oxide as a grafting initiator to graft it onto a polyolefin such as polyethylene, polypropylene, or ethylene/vinyl acetate copolymer, and then causes a silanol condensation reaction to cause crosslinking. In addition, amino group-containing alkoxysilane compounds include γ-aminopropyltrialkoxysilane and N-B-(aminoethyl)-γ-aminopropyltrialkoxysilane. It is almost impossible to graft polyolefins, which mainly have active halogen atoms in the molecule, such as chlorosulfonated polyethylene or polychloroprene, and then crosslink by causing a silanol condensation reaction. is being developed. Furthermore, as a mercapto group-containing alkoxysilane compound, γ-mercaptopropylalkoxysilane is known, and in the case of this silane, after grafting chlorinated polyethylene, polyvinyl chloride, etc. that do not have an active halogen atom in the molecule, Similarly, a method of crosslinking by causing a silanol condensation reaction has been developed. However, the rate of hydrolysis of each of the above alkoxysilane compounds is different; for example, those containing a mercapto group have a higher hydrolysis rate than those containing a vinyl group or an amino group.
In the case of mercapto group-containing alkoxysilanes, there is a particular problem in that the grafted polymer obtained by grafting, that is, a crosslinkable composition, undergoes a silanol condensation reaction due to moisture in the composition during storage, making it unusable. It was hot. This tendency exists to a greater or lesser extent in other alkoxysilane compounds as well. Therefore _, as a result of various studies on methods to solve these problems, the inventors of the present invention discovered that an alkoxy compound represented by the general formula R-Si(OR _' ) It has been found that hydrolysis of the grafted polymer can be suppressed by impregnating a silane compound into a metal oxide obtained by thermally decomposing a metal hydroxide and adsorbing it to the surface of the particles. The present invention has been made with attention to such points, and its gist is that the general formula R-Si
(OR') _o Y _3-o (where n = 1 to 3), an alkoxysilane compound containing a vinyl group, an amino group, or a mercapto group is mixed with aluminum hydroxide,
A metal oxide obtained by thermally decomposing zinc hydroxide or magnesium hydroxide is impregnated to create an alkoxysilane composite that suppresses hydrolysis, and this is mixed with rubber or plastic. A crosslinkable rubber or plastic composition that suppresses hydrolysis during storage. In the following, experimental progress on alkoxysilane composites and examples of crosslinkable rubber or plastic compositions will be described. <Experimental Example 1> After suspending 0.05 mole of various metal oxide powders in 0.05 mole of γ-mercaptopropyltrimethoxysilane, the suspension was heated at 24°C, 100% relative humidity,
Hydrolysis was carried out under the condition of 100 mmHg. The conversion rate was calculated by removing the generated methanol under reduced pressure and calculating the amount of methanol volatilized. In a reaction system where water vapor is present in a significant excess compared to the concentration of alkoxysilane, the reaction rate is thought to be linearly proportional to the concentration of alkoxysilane. −dC _A /dt=kC _A , logC _A0 /C _A =k/2.303t However, C _A0 is the initial concentration of alkoxysilane C _A is the concentration of alkoxysilane after t minutes Based on the above formula, logC _A0 /C _A : When the relationship of t was plotted, a linear relationship was obtained. The reaction rate constant was determined from the slope of this straight line. The results are shown in Table 1 and FIG.

[Table] Aluminum oxide As is clear from Table 1 and Figure 1 above, the protective effect is greatest when aluminum oxide obtained by thermally decomposing aluminum hydroxide is used, followed by zinc oxide and aluminum oxide. It was also found that magnesium etc. are effective. Note that the aluminum oxide in Figure 1 is obtained by mixing aluminum hydroxide in nitrogen gas.
It is thermally decomposed at 220℃. <Example 2> Aluminum oxide obtained by thermally decomposing aluminum hydroxide (particle size 0.5 to 5μ) in nitrogen gas at a temperature of 210 to 220°C was used, and this was combined with the general formula R-Si
An alkoxysilane compound represented by (OR′) _o Y _3-o was impregnated to obtain an alkoxysilane composite.
The effect of water vapor content on this complex was then investigated. The reaction was carried out at room temperature and under normal pressure. The results are shown in FIG. 2, and it was found that hydrolysis of the alkoxy group of the alkoxysilane hardly occurs in an atmosphere with a relative humidity of 30% or less. Next, a crosslinkable rubber or plastic composition obtained using the alkoxysilane composite thus obtained will be described. <Example 2> Aluminum hydroxide with a particle size of 0.5 to 5μ is
Mercaptoalkoxy obtained by suspending 0.026 mole of aluminum oxide obtained by thermal decomposition at 220°C in nitrogen gas in 0.026 mole of mercaptoalkoxysilane and leaving it at 25°C and 0% relative humidity for 24 hours. The silane complex was mixed with 100 parts by weight of chlorinated polyethylene (chlorine content 40%) and carbon black.
30 parts by weight were kneaded at 80° C. for 10 minutes, and then 0.026 mole of hexamethylene diamine was added and kneaded for an additional 15 minutes to effect grafting to prepare a grafted polymer sample. This was left at 25° C. and 0% RH, and the insolubilization rate was measured by a conventional method. The amount of the alkoxysilane composite added to the rubber or plastic is preferably at least about 0.02 mole per 100 parts by weight of the rubber or plastic. If the amount is less than this,
It is not possible to obtain a sufficient degree of crosslinking. <Comparative Example 1> Silicon dioxide with a particle size of 5 to 20μ (12
Time drying) 0.026 mole was suspended in 0.026 mole of mercaptoalkoxysilane, left at 25℃ and 0% relative humidity for 24 hours, then added to 100 parts by weight of chlorinated polyethylene and 30 parts by weight of carbon black at 80℃ for 10 minutes. After kneading, hexamethylene diamine
0.026 mole was added and mixed for an additional 15 minutes to allow grafting to produce a sample of grafted polymer. The insolubilization rate was measured under the same conditions as above. <Comparative Example 2> 100 parts by weight of chlorinated polyethylene, 30 parts by weight of carbon black, and 3 parts by weight of anhydrous magnesium sulfate were kneaded at 80°C for 10 minutes, and left at 25°C and 0% relative humidity for 10 days to dehydrate. After processing, 80
Add 0.026 mole of mercaptoalkoxysilane and 0.026 mole of hexamethylene diamine at
A sample was prepared by kneading for an additional 10 minutes. The insolubilization rate was also measured in the same manner as above. <Comparative Example 3> 100 parts by weight of chlorinated polyethylene, 30 parts by weight of carbon black, mercaptoalkoxysilane
Knead 0.026 mole at 80℃ for 10 minutes, then
0.026 mole of hexamethylene diamine was added and kneaded for an additional 5 minutes to allow grafting to produce a sample of grafted polymer. The insolubilization rate was also measured in the same manner as above. When the time-dependent changes in the insolubilization rate of each sample thus obtained were measured, the results were as shown in FIG.
In addition, each code|symbol A, B, C, and D in the figure corresponds to Example 2 of this invention, Comparative Examples 1, 2, and 3 in order. According to this, in the case of Comparative Example 3 in which no measures were taken to suppress the silanol condensation reaction of the grafted polymer,
After about 3 days, the insolubilization rate reached a high rate of about 80%,
The insolubilization rate becomes quite high over time even in Comparative Example 1, which was protected by other silicon dioxide, and Comparative Example 2, which was protected by dehydration method. In contrast, in the case of Example 2 of the present invention, the insolubilization rate hardly changed even after 90 days, indicating that the protective effect was tremendous. As is clear from the above explanation, according to the present invention, the general formula R-Si(OR') _o Y _3-o (where n=1 to
A metal oxide obtained by thermally decomposing a metal hydroxide of aluminum hydroxide, zinc hydroxide, or magnesium hydroxide from an alkoxysilane compound containing a vinyl group, an amino group, or a mercapto group represented by 3). Since the rubber or plastic is mixed with an alkoxysilane complex impregnated with the rubber or plastic to inhibit hydrolysis, this crosslinkable rubber or plastic composition is hydrolyzed during storage and undergoes a silanol condensation reaction, making it unsuitable for practical use. It is extremely effective in handling and use.

[Brief explanation of the drawing]

Figure 1 shows logC _A0 / when various metal oxide powders are suspended in alkoxysilane compounds.
C _A : A graph showing the relationship between t. Figure 2 is logC showing the influence of the water vapor amount when protected with aluminum oxide (white dots) and when not protected (black dots) according to Example 2 for explaining the present invention. _A0 /C _A :
The graph of t, FIG. 3 is a graph showing the relationship between the insolubilization rate and elapsed time in the case of the present invention example and each comparative example.

Claims (1)

[Scope of Claims] 1. 100 parts by weight of rubber or plastic and a vinyl group, an amino group, or a mercapto group represented by the general formula R-Si(OR') _o Y _3-o (where n=1 to 3). A crosslinkable rubber or plastic composition comprising an alkoxysilane composite obtained by impregnating a group-containing alkoxysilane compound with a metal oxide obtained by thermally decomposing a metal hydroxide. 2. A patent that uses aluminum oxide, zinc oxide, or magnesium oxide obtained by thermally decomposing aluminum hydroxide, zinc hydroxide, or magnesium hydroxide as a metal oxide obtained by thermally decomposing the metal hydroxide. A crosslinkable rubber or plastic composition according to claim 1.