JPS60186558A - Method of crosslinking of polyolefin resin - Google Patents

Abstract

PURPOSE:To obtain a silane-crosslinked polyolefin resin in an extremely shortened crosslinking time, by adding a specific polyfunctional silane compound to a composition containing a silane grafted polyolefin resin and a silanol condensation catalyst. CONSTITUTION:Polyolefin resin is blended with 0.5-10wt% organosilane compound such as vinyltrimethyoxysilane, etc., 0.05-1wt% organic peroxide such as dicumyl peroxide, and 0.1-20wt% compound shown by the formula I , II, III, IV, or V having two or more organic groups bondable to silicon and hydrolyzable in the molecule, containing no fatty unsaturated group, kneaded by an extruder, to give silane grafted polyolefin pellets. 100pts.wt. pellets are blended with 0.01-1pt.wt. silanol condensation catalyst such as dibutyltin laurate, etc., molded by an extruder, etc., and the molded article is exposed to water and crosslinked.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides silane crosslinking with improved productivity, J? The present invention relates to a method for producing IJ olefin thread resin.

The method for crosslinking polyolefins using silane crosslinking has a wider selection range of materials to be crosslinked than the chemical polyolefin crosslinking method using organic peroxides or the method of producing crosslinked molded products by irradiating polyolefin molded products with radiation. It is extremely advantageous industrially because it is wide and the equipment for crosslinking is significantly simplified, and has been widely applied to polyolefin resins in recent years.

As a method for obtaining a silane-crosslinked polyolefin resin, for example, the method disclosed in Japanese Patent Publication No. 1711-1988 is well known. (1) A polyolefin resin is mixed with an organic non-silicon compound such as VTMO8 (vinylmethoxysilane) and a free radical generating substance such as DCP (dicumyl oxide) in a tumbler or the like.

(2) The above-mentioned mixture is mixed in an extruder or the like to obtain a thermoplastic pellet 9 into a Lang-shifted polyolefin pellet.

(3) Add the necessary silanol-delivery catalyst to this Dan Red and mold it using an extruder or the like.

(4) This molded product is crosslinked by exposing it to an atmosphere containing moisture.

The above method can be avoided as a so-called two-stage process method, but as a more economical method, the silanol-feeding catalyst in the step (3) above is replaced by the TMO catalyst in the step (1).
A one-step process method has also been developed in which the silane grafting process and the molding process are reduced to one process by mixing 8 or DCP at the same time.

In this way, the silane crosslinking method is faster at producing molded products than the conventional crosslinking method, but the crosslinking process is a patch method, which results in an extremely long cycle time, which is a bottleneck during the manufacturing process. Met. That is, as a crosslinking treatment step, the material was placed in a hot water bath at 80 to 95 DEG C. or in a high temperature, high humidity room for several hours to several days. This processing time varies depending on processing temperature and humidity, but
It is also greatly influenced by the wall thickness of the object to be crosslinked. For example, a crosslinked body with a wall thickness of 1 to 2 may be treated in hot water at 80° C. for several hours, but a body with a wall thickness of 10 to 100 will require about one week.

In the present invention, a novel silane crosslinking method has been developed as a result of intensive study on shortening the crosslinking treatment time. In a method for producing a silane-crosslinked polyolefin resin by exposing a silane-grafted polyolefin resin to moisture in the presence of a silanol combination catalyst, molecules of It is characterized by adding 0.1 to 20.0% by weight of a compound having two or more organic groups capable of bonding to silicon and hydrolyzing it and not containing an aliphatic unsaturated group. .

The reason why the crosslinking treatment time can be significantly shortened in the method of the present invention is that the silane crosslinking method for polyethylene is generally carried out in the same phase state below the melting point of the polymer. On the other hand, the crosslinking point is the alphukidisilane grafted to the polyethylene chain, and the crosslinking point is generated by the coupling of these alphukidisilanes together, but as mentioned above, since it is in a solid phase state, it is not possible to graft it onto the polyethylene chain. The range of motion of Alfukidisilane is severely limited. Therefore, it is thought that due to the above-mentioned hindrance caused by the al-; However, by blending a polyfunctional silane compound as in the method of the present invention, it is believed that this acts as a crosslinking aid and dramatically improves the crosslinking rate of the silane grafted polyolefin resin.

In the method of the present invention, the following compounds can be mentioned as the above-mentioned compounds.

(1) 1,6-bis(tritoxysilyl)hexane (13,P161℃)(n1eO)5Sr(CH2
)6S+ (OMe)3(2) Hegiza 1 Toxidisilokylene (B, P230-2℃) OEt 0FJt l 0Et, 0Et (3) Tetraethoxysilane (B, P169℃) h:
t, o ogt \ / t / \ gt, o ogt (4) Tetrapropoxysilane (B, P224.-5
°C) (5) 1. t, a, s, 5- and intaethoxy 1
, 3.5-trinotyltrisiloxane (B, P250
℃) MeSi -0-8t-OSiMe IO rise Me MiEt These silane compounds are silane grafts, l? It plays the role of accelerating the crosslinking rate of cryolefin resin. The amount added varies depending on the molecular weight of the silane compound, etc. is added in a range of 0.1 to 20% by weight,
Preferably i is in the range of 0.5 to 5% by weight. The reason for this is that if it is less than 0.1%, it will not have any effect on improving the crosslinking speed, and if it exceeds 20%, it will not only be economical but also have a negative effect on the crosslinking properties during the molding process.

The silane compound may be added at either step (1) or step (3).

In the method of the present invention. 191J olefin resin is polyethylene, ethylene-chloropylene rubber.

It is a general term for ethylene-vinyl acetate copolymer, ethylene ethyl-notarylate copolymer, polypropylene, chlorinated polyethylene, etc., and single or blended mixtures of these.

In addition, in the method of the present invention, as a compound that generates a free radical site in an organic silane compound and an olefin polymer, it is desirable that the compound has a half-life in as short as 6 minutes at a temperature of 140°C or higher. -1711
It is stated in the No. For example, examples of silane compounds include vinyltriethoxysilane and vinyltrimethoxysilane.

Examples of organic peroxides include nocumilno-R-oxide, perbenzoyl peroxide, and di-tert-butyl peroxyisoprobyl benzenato.

The amount of these compounds added is 0.5 to 10% by weight in the case of an organic silane compound, and 0.05 to 1.0% by weight in the case of an organic peroxide, based on the resin component.

In addition, in the method of the present invention, a silanol condensation catalyst is added and mixed, and the amount added is 1jiJ (grafted pellets in step (3))], OO]L i3. i
.

0.01~1. It is preferable to blend ONN, and specific examples thereof include subbutyltin laurylate, diptyltin noacetate, dibutyltin nooctoate, and the like.

Further, in the method of the present invention, a carbon bra is included in the composition.

filler such as clay, talc, calcium carbonate, etc., blowing agent, foam nucleating agent, and organic or inorganic flame retardant.

A lubricant, a UV stabilizer, a heavy metal deterioration inhibitor, and a coloring agent may be added.

Next, examples of the present invention will be described.

Example (1) and Comparative Examples (1) to (2) Crosslinkable mixed first products were obtained with the compositions shown in Table 1.

Table 1 Notes (1) Catalyst master patch Low density polyethylene (density 0.92, M, I 3,
0 (g/io min)), 1 part of dibutyltin silaurylate, 5 parts of antioxidant Irganox 1010 (manufactured by Ciba Geigy), and kneaded with a mill roll to form a pellet. D: 28, D: 30
Cylinder temperature set at 150-210 in a twin-screw extruder with φ
A silane-grafted polyethylene sheet with a thickness of 1 inch was obtained at ℃.

It should be noted that an attempt was made to make a sheet of the mixture of Comparative Example (2) by extrusion processing in the same manner as above, but the extrusion processability was extremely poor and a sheet could not be obtained.

Next, this sheet was completely crosslinked by dipping in hot water at 50°C for 1° to obtain crosslinked polyethylene, tyrene according to the present invention and crosslinked polyethylene according to the comparative method.

Comparing the processing time required to quickly reach a dull fraction of 65%, it was 10 hours in the method of the present invention, but in the comparative example (
Method 1) required about three times as much time.

As described in detail above, according to the method of the present invention, the crosslinking treatment time is significantly shortened and the productivity is improved by crosslinking PoIJ and rufin resins with silane.

[Brief explanation of the drawing]

The drawing is a relationship curve diagram between crosslinking treatment time and dull fraction according to the method of the present invention and the method of a comparative example.

Claims (1)

[Claims] In a method for producing a silane-crosslinked polyolefin resin by exposing a silane-grafted polyolefin resin to moisture in the presence of a silanol condensation catalyst, silicon is present in the molecule in a composition containing a silane-grafted polyolefin resin and a silanol-bonded catalyst. Crosslinking of a polyolefin resin characterized by adding a compound having two or more organic groups that can be hydrolyzed by bonding with the compound and having no aliphatic unsaturated group (l:O61-26.OJij) in an amount of qb Method 0