JPH0326220B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an alkoxysilane-based crosslinkable composition prepared by adding a condensation catalyst for a compound containing an alkoxysilane bond, such as a synthetic resin grafted with vinylalkoxysilane, to the compound. Conventionally, polyethylene-silane graft polymers grafted with vinyl alkoxysilanes, modified polymers such as alkoxysilane copolymerized polyethylene, and polypropylene have been crosslinked to impart higher-order performance, such as heat resistance. ing. As condensation catalysts for condensing alkoxysilanes to produce this crosslinking, amines, acids, alkyltin carboxylates, organometallic catalysts such as organic titanium compounds are known. However, when these condensation catalysts are used, the condensation reaction is very slow, and for practical use, water treatment must be performed by immersion in hot water, etc., or hydrated salts, deliquescent salts, etc. must be mixed into the composition. It has been attempted to speed up the condensation reaction by increasing the amount of water introduced into the composition, but adopting water treatment requires new equipment such as a water tank and a water treatment process. Furthermore, the addition of hydrated salts, deliquescent salts, etc. tends to deteriorate the physical properties of the composition, and is therefore not very desirable. In view of the above-mentioned current situation, the present invention has developed an alkoxysilane-based crosslinkable composition in which the condensation reaction of alkoxysilane can proceed simply by heating in the air, and the condensation reaction can be completed without special supply of moisture. This was done as a result of research with the aim of providing a product with the general formula: (R ₁ and R ₂ are hydrocarbon groups) An alkoxysilane-based crosslinkable composition characterized by containing a tin compound represented by: In the above tin compound used in the present invention,
R ₁ and R ₂ are each a hydrocarbon group, for example, an alkyl group, a phenyl group, an aralkyl group, etc., but preferably a straight-chain alkyl group, especially when R ₁ and R ₂ have 1 carbon number. -8 straight chain alkyl groups are preferred. Examples of the tin compound suitably used in the present invention include dimethyltin phthalate, dibutyltin phthalate, dioctyltin phthalate, and the like. Next, the compound containing an alkoxysilane bond in the present invention refers to a compound having a molecular structure in which an alkoxy group is bonded to silicon in the molecule, such as a vinylalkoxysilane graft polymer in which vinylalkoxysilane is grafted to a polymer such as polyethylene. Examples include polymeric substances such as copolymers of vinyl alkoxysilane and other monomers, such as alkoxyvinylsilane-ethylene copolymers, and low-molecular substances having alkoxysilane bonds such as silane coupling agents. To prepare the crosslinkable composition of the present invention, the compound containing the alkoxysilane bond and the tin compound may be added together, and if necessary, other polymer substances, fillers, and other additives may be added and mixed. The amount used is usually 0.005 parts by weight of the latter for every 100 parts by weight of the former.
It is preferable to use ~1 part by weight. When the crosslinkable composition is a polymeric material such as a vinyl alkoxysilane graft polymer, when molded using an appropriate molding means such as an extruder or an injection molding machine, it is possible to remove heat during molding or in the atmosphere after molding. By reaction with water, silane crosslinking between the polymers progresses due to the catalytic action of the tin compound contained therein, improving heat resistance and other properties, resulting in a molded product with improved quality. In addition, in order to further increase the crosslinking rate, it is possible to perform treatments such as immersion in hot water or contact with water vapor, but the In both cases, the composition of the present invention has a significantly faster crosslinking speed than when conventional condensation catalysts are used, and crosslinking can be completed in a short time, resulting in excellent workability. In addition, since there is no need for additives such as hydrated salts and deliquescent salts to improve the crosslinking rate, which degrade the physical properties of the composition or molded product, good physical properties can be obtained. Furthermore, the composition of the present invention can be effectively used for materials other than polymers by taking advantage of the characteristic that the composition can be quickly crosslinked. For example, the composition can be effectively used with silane coupling agents containing alkoxysilane bonds. The above-mentioned tin compound can be used for surface treatment of glass fibers and other reinforcing materials or fillers, for example, by kneading them into resin together with the above-mentioned reinforcing materials and fillers for the purpose of improving bondability with resin etc. Furthermore, when the composition of the present invention is in liquid form, it can be applied and then cured by crosslinking to form a coating, so that it can also be used as a coating agent. Since the alkoxysilane-based crosslinkable composition of the present invention has the above-mentioned structure, the crosslinking speed is extremely high compared to conventional compositions due to the action of the tin compound contained therein, and crosslinking occurs in a short time. It has excellent workability because it completes the crosslinking process, and there is no need to add hydrated salts or deliquescent substances that may cause deterioration of physical properties to promote crosslinking. It is something that will never come. Furthermore, when used for the purpose of improving the bond between the resin and reinforcing material or filler, the bond becomes excellent and a synthetic resin molded article with improved physical properties such as impact resistance can be obtained. The following will be explained based on examples. Example 1 100 parts by weight of polyethylene, 1 part by weight of vinyltrimethoxysilane, 1 part by weight of benzoyl peroxide
Add parts by weight and mix the mixture uniformly to 180 to 220
Polyethylene grafted with vinyltrimethoxysilane was prepared by kneading and extrusion at ℃. The grafted polyethylene was further purified by immersing it in acetone to remove peroxide and unreacted vinyltrimethoxysilane. Separately, prepare pellets by adding 5 parts by weight of dibutyltin phthalate (Example) or 5 parts by weight of dibutyltin dilaurate (Comparative example) to 100 parts by weight of polyethylene, and add 15 parts by weight of each pellet to 85 parts by weight of the grafted polyethylene. In addition, the mixture was roll-kneaded at 150°C to form a sheet, which was then pressed at 150°C for 10 minutes to form a pressed sheet with a thickness of 5 mm. Table 1 shows the results of cutting a sample piece from the sheet and measuring the crosslinked gel content as it is, and measuring the crosslinked gel content after immersing the sample piece in hot water at 95°C for 24 hours. Ta. The crosslinked gel content was determined by immersing the sample in xylene at 120°C for 24 hours, then measuring the weight of the insoluble content.
The weight ratio of insoluble matter to the sample is expressed in %.

[Table] Example 2 A mixture of 100 parts by weight of powdered polyethylene, 50 parts by weight of mica, 1 part by weight of propyltrimethoxysilane and 0.01 part by weight of dibutyltin phthalate was prepared.
Roll kneading at 150℃ for 10 minutes, press it in a press for 5 minutes at 130℃ to create a sheet,
When a sample piece was prepared from this and subjected to an Izot impact test, the impact value was 16±3 Kg/cm ² . Next, for comparison, an Izot test was conducted in the same manner as in the above Example except that 0.01 part by weight of dibutyltin dilaurate was used in place of 0.01 part by weight of dibutyltin phthalate, and the Izot impact value was 7±. 2Kg/ ^cm2 ,
In addition, after creating a sheet with a press, it is soaked in hot water at 95℃ for 24 hours.
After immersion for a time and hot water treatment, a sample piece was prepared and the Izod impact value was measured, and the result was 9 ± 3.
It was Kg/ ^cm2 .

Claims (1)

[Claims] 1. A compound containing an alkoxysilane bond made of a synthetic resin grafted with an alkoxysilane, and a compound having the general formula (R ₁ and R ₂ are hydrocarbon groups) An alkoxysilane crosslinkable composition characterized by containing a tin compound represented by the following. 2. The alkoxysilane crosslinkable composition according to item 1, wherein R ₁ and R ₂ in the general formula are both linear alkyl groups. 3. The alkoxysilane crosslinkable composition according to item 2, wherein R ₁ and R ₂ in the general formula are alkyl groups having 8 or less carbon atoms.