KR890003576B1 - Bridged bonding method for polymer of polyolefin - Google Patents

Abstract

Crosslinking method for polyolefin, olefinic copolymer or their blend resin comprises (A) introducing polyolefin, olefinic copolymer or their blend into the hopper, (B) introducing the mixt. of crosslinking agent, catalyst and antioxidant to be mixed in silane into the mixture reservoir, (C) injecting the mixt. into the extraction device at a certein ratio by using a pump, (D) smelting, extracting and molding olefin, olefinic copolymer or their blend and mixt., and E) crosslinking them by placing in warm water.

Description

Crosslinking method of polyolefin or olefin copolymer

1 is a conventional extruder used to crosslink polyolefins or olefinic copolymers,

2 shows an extruder used according to the process of the invention.

* Explanation of symbols for main parts of the drawings

1: cylinder 2: screw

3: center hopper 4: resin reservoir

5: crosslinker storage container 6: antioxidant storage container

7: Silane + Catalyst Reservoir 8: Weighing Hopper

9 Metering Hopper 11 Pump

12: mixture of resin + additive 13: conductor

14: Nipol 15: Head

16: barrel 17: silane, catalyst, antioxidant, crosslinking agent mixture

18: pump 19: inlet

20 tube 21 polyolefin resin

The present invention relates to a method of performing molding simultaneously with crosslinking by extruding a polyolefin or an olefin copolymer in an extruder using a hydrolyzable silane. In general, the polyolefin or the olefin copolymer has undergone a crosslinking reaction because the melting point is increased to improve the heat resistance and the hardness is increased by the crosslinking reaction.

Such crosslinking methods include crosslinking using peroxides, irradiation crosslinking, or crosslinking methods using silanes. However, silane-based methods have been widely applied due to the advantages of low facility investment and high production speed. As such, a method of preparing a crosslinked polyolefin or olefin copolymer using silane was started by Dow Corning in 1972. The Dow Corning method is used to produce silane to polyethylene or olefin copolymer using a single screw or twin screw extruder. After mixing, grafting and grafting the antioxidant and crosslinking agent, it is made into pellet form and dried. Then, catalyst and antioxidant are mixed with polyethylene or olefin copolymer in the same way to make pellet-shaped catalyst master 'master batch' In addition, the grafted polyethylene or olefin copolymer and the catalyst master batch are mixed and extruded through a extruder to the desired shape, and then the extruded mole is placed in hot water or left to stand in the air for crosslinking.

This method has a storage problem in that crosslinking proceeds when a mixture of polyethylene or olefin-based copolymer and catalyst master batch to be grafted passes for a long time, and there are also many methods for making a grafted polyethylene or olefin copolymer and catalyst master batch. There is a disadvantage in that facility investment is required and process costs are high. In order to solve this problem, a manufacturing method omitting the compounding process has been developed and used by Swiss Miper.

This method feeds polyethylene into the central hopper 3 using the metering hopper 8, as shown in FIG. 1, the crosslinking agent in powder or master batch, the metering hopper 9 and the powdered antioxidant in the metering hopper. (10) is supplied to the central hopper (3), the mixed liquid of silane and catalyst is quantitatively supplied using the pump (11), these are mixed in the central hopper (3) and passed through an extruder to the head (15) Mold to the desired shape.

This method reduces Dow Corning's two-step method to one, eliminating storage problems and reducing formulation costs. However, as shown in FIG. 1, separate reservoirs 4, 5, 6, and 7 for storing polyethylene, crosslinking agents, antioxidants, silanes, and catalysts are required, and in order to quantify them to the central hopper, Three metering hoppers 8, 9, 10 and pump 11 are required.

In general, it is very difficult to quantitatively supply pellets or powdery solids, and the apparatus is much more expensive than quantitatively supplying liquids. This method is a step forward from Dow Corning's method, which solves the storage problem and omits the compounding process, but the investment cost of the solid and liquid metering feeders (8) (9) (10) (11) is still high. There is a management problem that requires a space for a separate reservoir (4) (5) (6) (7), and to supply four substances at a constant rate at the same time.

The present invention omits the solid quantitative supply device for quantitatively supplying resins, crosslinking agents, anti-ignition agents such as powder or pellet-like polyolefin or polyolefin-based copolymers and blends to the central hopper, and thus, the silane-based compound in one step without excessive equipment investment. It aims at bridge | crosslinking a polyolefin or polyolefin type copolymer, and a blend using the said object.

In the present invention, the resin of the polyolefin or polyolefin copolymer and blend is placed in the hopper, and the crosslinking agent, the catalyst, and the anti-burning agent are mixed with the silane in a constant ratio, and a single pump is injected into the bottom of the hopper with the resin in a constant ratio to the polyolefin or It relates to a method of crosslinking an olefin copolymer.

Examples of the polymers that can be crosslinked with the present invention include polyethylene, polypropylene, polyvinyl chloride, ethylene vinyl acetate copolymer, ethylene propylene copolymer, ethylene propylene diene copolymer, ethylene ethyl acrylate copolymer, ethylene vinyl acetate Examples of the silane which can be used are vinyl fluoride copolymers or blends thereof, and examples of the silane which can be used include vinyl trichloro silane, vinyl trimethoxy silane, epoxy silane, vinyltrialkoxy silane, acetoxy silane, vinyl acetoxy silane, amino silane, Mercapto silane and the like.

The crosslinking agent, antioxidant and catalyst which can be used in this method should all be solid or liquid which can be easily dissolved in silane.

As the crosslinking agent, dicumyl peroxide in the form of a powder, liquid dibenzoyl peroxide, dibutyl butyl peroxide, tertiary butyl cumyl peroxide, etc. may be used, and as an antioxidant, 4, 4'-thio- is easily dissolved in silane. Bis (3-methyl-6-t-butylphenol) or liquid bis (2-methyl-4 (3-7alkyl-thiopropionyl oxy) -5-t-butylphenyl) sulfide or the like is used. Can be used as a well-known chopped chopstick catalyst, dibutyltinda urilate is preferred.

The content of the above compounding agent is 0.5 to 10 silanes, 0.01 to 10 crosslinking agents, 0.01 to 10 crosslinking agents, 0.01 to 10 antioxidants, and 0.01 to 10 parts catalysts based on 100 parts by weight of polyolefin resin, depending on the application. On the other hand, the molding together with the crosslinking reaction may include other known additives such as pigments, antioxidants, antistatic agents, egg yolks, thermal conductivity enhancers, thermal stabilizers, fillers, reinforcing agents, adhesion improvers.

2 shows an extruder used in an embodiment of the present invention, where (1) represents an extruder cylinder, (2) represents a screw, (3) a hopper, (21) a polyolefin resin, (17) a silane and It is a mixture of a crosslinking agent, an antioxidant, a catalyst, (16) is a container for storing the mixture, (18) is a pump, and (20) is a tube.

When the polyolefin resin 21 is put into the extruder hopper 3, the resin 21 enters the inside of the cylinder 1 as the screw 2 rotates. On the other hand, in the cylinder 16, a mixed liquid in which a crosslinking agent, an antioxidant, and a catalyst are mixed in a silane is stored, and the mixed liquid is injected into the bottom of the hopper 3 through a pipe 20 using a pump 18. do. The polyolefin resin 21 and the mixed liquid 17 enter the inside of the extruder cylinder 1 at the bottom of the hopper and are kneaded while moving toward the head 15 by the screw 2, and grafting proceeds.

The grafted polyolefin is shaped into a desired shape by passing through the head 15 and crosslinked when it is left in hot water. Any pump that can be used for this method can be supplied in small quantities, especially plunger pumps, diaphragm pumps and gear pumps. The pump should be able to adjust the discharge amount, and the discharge amount may be adjusted manually, and may be linked with the extruder screw speed.

As described above, the polyolefin is cross-linked. This method eliminates the need for a blender or a solid quantitative feeder as compared to the conventional methods, and thus requires much lower capital investment and requires no separate supply of antioxidants, silanes, catalysts and crosslinkers. It is easy to do, it is easy to change the resin and adjust the production, and the operating cost of the solid feeder is reduced.

Claims (5)

In crosslinking polyolefins, olefin copolymers or blend resins thereof, the polyolefins, olefin copolymers or blend resins thereof are placed in a hopper, and a mixed solution in which a crosslinking agent, a catalyst, and an antioxidant is mixed with silane in a constant ratio is placed in a mixed liquid reservoir. And then injecting it into the extruder at a constant rate using one pump to knead the polyolefin, the olefin copolymer or their blended resin with the mixed solution, extrude and shape, and then crosslink by leaving in hot water. The crosslinking method of an olefin or an olefin copolymer. The method of claim 1, with respect to 100 parts by weight of polyolefin or olefin copolymer, 0.5-10 parts by weight of silane, 0.01-10 parts by weight of crosslinking agent, 0.01-10 parts by weight of antioxidant, 0.01-10 parts by weight of catalyst A method for crosslinking a polyolefin or an olefin copolymer characterized by adding an amount within a negative range. The method of crosslinking a polyolefin or an olefin copolymer according to claim 1, wherein the crosslinking agent is a crosslinking agent that is easily soluble in silane. The diolefin is selected from dicumyl peroxide, dibenzoyl peroxide, dit-butyl peroxide and t-butyl cumyl peroxide. . The method of claim 1 wherein the antioxidant is 4, 4-thio-bis (3-methyl-6-t-butylphenol) or bis [2-methyl-4 (3-7 alkyl-thio propionyloxy) that is readily soluble in silane. ) 5-t-butyl phenyl] crosslinking method of polyolefin or olefin copolymer using sulfide. The additive according to claim 1, wherein the polyolefin, the olefin copolymer or the blend resin is an additive selected from the group consisting of an anti-aging agent, an antistatic agent, a flame retardant agent, a thermal conductivity enhancer, a heat stabilizer, a filler, a reinforcing agent, a dispersing agent, an adhesion improving agent, a conductive agent, or A method for crosslinking a polyolefin or an olefin-based copolymer in which two or more complex additives are contained or compounded.

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