JPS6176345A - Production of heat-shrinkable tube - Google Patents

Abstract

PURPOSE:To enable a heat-shrinkable tube with a high draw ratio to be produced without requiring expensive equipment, by adding vinyl trimethoxysilane and triallyl isocyanurate to a base resin consisting of an ethylene-alpha-olefin copolymer. CONSTITUTION:A compound prepared by bringing 100pts.wt. of an ethylene-alpha- olefin copolymer comprising 70-95mol% of ethylene and 30-5mol% of an alpha-olefin and having a melt index of 1-10g/10min into reaction with 1-10pts.wt. of vinylmethoxysilane and 0.01-5pts.wt. of triallyl isocyanurate at 120 deg.C in the presence of a free radical forming compound having a half-life at the reaction temperature of not longer than 6min, is molded into a tubular form, which is hydrolyzed with water in the presence of a hydrolysis catalyst, the hydrolyzed resin is stretched at a temperature not higher than the softening point of the resin, and is cooled as it is. The free radical forming compound is preferably dicumyl peroxide, 1, 3-bisbenzene or the like, and an optimum amount thereof is 0.01-0.7pts.wt.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention can be used without installing expensive equipment such as a pressure cooker.
The present invention relates to a method for producing a heat-shrinkable tube mainly composed of an ethylene-α-olefin copolymer and having a high draw ratio.

(Prior art) Ethylene-α olefin copolymer as a hese resin,
A heat-shrinkable chain was produced by crosslinking this with a crosslinking material made of a peroxide such as dicumyl peroxide, stretching the chain at a temperature higher than the melting point of the resin, and cooling it in that state.

(Problems to be Solved by the Invention) However, in the conventional manufacturing method, it is necessary to crosslink the chain under high temperature and high pressure, which requires expensive equipment such as a pressure cooker.

It is also a method that does not require expensive equipment.

For example, there is a method disclosed in Japanese Patent Publication No. 19459/1983, but since the chip obtained by this method has a small elongation rate at temperatures above its softening point,
If the stretching ratio was too large, the chain would tear, so it was not possible to increase the stretching ratio.

The present invention eliminates the conventional drawbacks, namely, "installation of expensive equipment" and "small draw ratio", and provides a method for manufacturing heat-shrinkable chips with a large draw ratio without requiring expensive equipment. It has a particular purpose.

(Means for Solving the Problems) That is, the resin contains 70 to 95 moles of ethylene and 30 to 5 moles of α-olefin having 6 to 8 carbon atoms.

Ethylene with a melt index of 1 to 109/10 minutes
α-olefin copolymer or terpolymer with ethylidenenorbornene or dicyclobencdiene having a wax value of 5 to 20.
) with 1 to 10 parts (by weight) of vinyltrimethoxysilane (
Preferably 2 to 5 parts (by weight)) and 0.01 to 5 parts (by weight)
The compound obtained by reacting the compound in the presence of a free radical generator such as dicumyl peroxide having a half-life of 6 minutes or less at a temperature of 0C or higher is formed into a tube shape, and then a hydrolysis catalyst such as dibutyl is formed into a tube. Chape obtained by hydrolysis with water in the presence of tin dilaurate,
The heat-shrinkable chain 1 is produced by stretching the material above its softening point using a known method and cooling it in that state.

(Function) In the present invention, triallylisocyanurate is essential. Even without this, a heat-shrinkable chave can be obtained, but the elongation rate above the softening point is low, and therefore the stretching rate cannot be increased. Triallylic socyanurate is essential for improving the drawing ratio.

The appropriate amount to add is 0.01 to 5 parts, preferably LO5 to 1 part (weight); too little will not contribute to improving the elongation rate, and too much will lead to an increase in cost. Economical - The amount of vinyltrimethoxysilane added is 1 to 10
part (weight 11) is appropriate, and if it is too low,
It is undesirable because it inhibits shrinkage and causes an increase in cost if it is too large.

As a free radical generating compound, dicumyl peroxide, 1
, 3-bis(t-butylperoxyisopropyl)benzene, etc. are suitable, and the optimum addition amount is 0.01 to α7
part (heavy Q).

Note that if it is too small, the shrinkability of the tube will be poor, and if it is too large, it will be difficult to mold the tube and the chain will lose its luster.

In addition, after a mixture of resin, vinyltrimethoxysilane, and triallylisocyanurate is treated with a free radical generator, it is made into a pellet, and when it is molded into a tube, a hydrolysis catalyst such as diptyltin dilaurate is added to the resin in a separate process. A so-called catalyst masterbatch, which is dispersed at a high concentration, may be mixed and formed into a chape, which may be hydrolyzed with water, or after being formed into a nine-chip.

Hydrolysis may proceed by bringing the hydrolysis catalyst into contact with water.

If necessary, e.g. calcium carbonate, clay.

An inorganic surface agent such as talc or aerosil may be added.

In the conventionally known silane graftomer production process, a silanizing agent such as vinyltrimethoxysilane is added to the radical position of the polymer generated by abstracting hydrogen radicals from the polymer, and the radical position moves to the vinyl position, and the adjacent polymer It is generally explained that hydrogen is extracted from the molecule and radicals are rearranged.

During this process, the polymer passes through a form in which vinyl radicals are added, but at this time, the main chain of the polymer is likely to be cleaved, so radical rearrangement and cleavage proceed competitively, and this is thought to be the cause of the decrease in high-temperature elongation.

On the other hand, when F-allylisocyanurate is present in the system as in the present invention, triallylisocyanurate is added to the polymer radical, and vinyltrimethoxysilane is further added to the added triallylisocyanurate. It is thought that this process is less likely to cause main chain scission and that the resulting tube has a high high temperature elongation rate.

(Example) Next, two examples of implementation of the present invention will be shown below.

The composition shown in the following table was formed into a heat-shrinkable cheese by stretching and forming a heat-shrinkable cheese, and the properties of the mixture were compared. It was cut into pellets using a cutter.

The L/D is 22. Extruded with an extruder with a diameter of 65mm and an inner diameter of 1
Form into a tube of Qm.

Further, it was immersed in 2% diptyltin dilaurate 80'l: 2% M water for 24 hours to effect crosslinking. This tube 1
After heating to 20 t, it was stretched and cooled in that state to obtain a heat-shrinkable tube.

As a result, the results shown in the first table were obtained.

(Effects of the Invention) Since the present invention is constructed as described above, it has the following effects.

(1) Since high temperature and high pressure crosslinking is not required, there is no need for expensive equipment like in the past.

(2) Since the high-temperature elongation rate after the cheese molding is higher than that of conventional products, it is possible to obtain a heat-shrinkable cheese with a high elongation rate. Conventionally, the stretching ratio of this type of tube is at most 2 to 2.5.
However, as can be seen from the examples, the present invention can produce products with a magnification of 3 times or more.

(3) Therefore, the applicable range of tube sizes can be expanded compared to the past, and this makes it possible to reduce the cost of handling and the number of sizes to stock.

As mentioned above, its industrial utility value is remarkable.

Claims (1)

[Claims] 70 to 95 mol% ethylene, 30 to 5 mol% alpha olefin having 3 to 8 carbon atoms, melt index 1 to 1
0g/10min ethylene-α olefin copolymer 100
parts (by weight) of 1 to 10 parts of vinyltrimethoxysilane (
(by weight) and triallyl isocyanurate in the presence of 0.01 to 5 parts (by weight) at a temperature of 120°C or higher in the presence of a free radical-generating compound having a half-life of 6 minutes or less at the reaction temperature. The resulting compound is formed into a tube, hydrolyzed with water in the presence of a hydrolysis catalyst, and then stretched at a temperature above the softening point of the resin.
A method for manufacturing a heat-shrinkable tube, which is characterized by cooling the tube in its original state.