KR940001065B1 - Copolymers for molding of heating plastic pipe - Google Patents

Abstract

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Description

Copolymer for Heating Plastic Pipe Forming

The present invention relates to a propylene copolymer for heating plastic pipe having excellent durability.

Polyvinyl chloride, crosslinked polyethylene, polypropylene copolymers (notice 89-37), etc. have been used as a molding material used for the plastic pipe for heating until now.

The polyvinyl chloride has the disadvantage that the pipe can be ruptured at low temperature, the process is complicated in construction and the pipe life at high temperature is not long. On the other hand, the crosslinked polyethylene is difficult to solve the problem of poor workability due to the connection problem of plastic pipes because of the difficulty of production due to the control of the degree of crosslinking during molding and the thermal fusion during construction. In addition, the conventionally used polypropylene copolymer does not have the characteristics of a pipe alone by the copolymer of propylene and ethylene alone, so melt mixing of ethylene-propylene elastomers (EPR, EPDM) is essential. Was the problem.

Therefore, the present invention not only possesses high heat resistance of propylene homopolymer, impact resistance of ethylene polymer, pressure creep resistance, and stiffness property of butylene polymer, but also compared with conventional polypropylene copolymer pipe. To produce a polypropylene copolymer pipe molding material having excellent productivity and economy, durability and transparency of the product without the need for melt mixing process for the additive of the elastomer. In the present invention, a molding material is prepared by copolymerizing propylene, ethylene, and butylene. Got.

Detailed description of the invention is as follows.

The resin of the present invention consists of a propylene block copolymer (A) a propylene-ethylene copolymer block (B) a propylene-butylene copolymer block, and (C) a propylene homopolymer block, at least two of which comprise (A) The above block is made.

The order of copolymerization used in the present invention does not matter much, but is usually formed in the order of (A) (B) (C) or (A) (C) (B), and the portion to be polymerized later is formed in the presence of the previously polymerized portion do. Some of the monomers that had been used for the polymerization first in the copolymerization remain and can be used for later polymerization, but this allows.

The composition of the polymer used in the present invention is (A) when (B) (C) blocks are all present, (A) block 70-98%, (B) block 1-10%, (C) block 1-29% (A) (B) blocks only (A) 70-99%, (B) blocks 1-30%, (A) (C) blocks only (A) It is necessary to have 70-98% of blocks and 2-30% of (C) blocks.

Meanwhile, the content of ethylene and butylene in (A) and (B) is 1-30% for ethylene and 1-30% for butylene. If the composition of the monoma exceeds the above range, the stiffness is lowered, and if the composition is insufficient, the impact strength is lowered, thereby degrading the characteristics of the pipe. The polymer resin of the present invention has a specific gravity of 0.90-0.93, MI of 0.1-3, and an average molecular weight in the range of 100,000-300,000.

The copolymer of the composition is produced by the following method. The catalyst used in this production consists of a titanium component and an organic aluminum compound. In order to obtain high catalyst activity and stereoregularity, it is preferable to use titanium tetrachloride supported on magnesium chloride.

As an organic aluminum compound, triethyl aluminum (TEAL), diethylammonium chlorate (DEAC), etc. are preferable.

The polymerization may be continuous or batchwise. In the case of a continuous system, one or more reactors are used for each polymerization process, and each reactor is reacted in a steady state. In the case of batch type, the reaction is carried out in each process, and after the reaction is completed, unreacted monomers are removed and polymerization is performed.

In the present invention, the polymerization temperature is carried out in the range of 50-150 ° C. and the pressure of 10-50 kg / cm ² , and the molecular weight is controlled by hydrogen.

Usually, the polymerization is carried out by gas phase polymerization, but also by suspension polymerization in inert hydrocarbon or solution polymerization, and solvent-free liquid polymerization in liquid propylene is also possible.

Antioxidants, acid acceptors, and / or ultraviolet stabilizers may be used as the additive in the present invention.

As antioxidants, for example, phenolic antioxidants, phosphite antioxidants, thiodipropionate synergists and the like are used, and as acid acceptors, for example, calcium stearate and zinc peroxide are used.

0.01-5% by weight of antioxidant, 0.01-5% by weight of acid acceptor, and 3% by weight or less of UV stabilizer are preferable.

In order to investigate the properties and workability of the molding materials manufactured as described above, tensile strength, impact strength, flexural strength, heat deformation temperature, elongation, hardness, etc. were measured. Flexural strength test and high temperature dimensional stability test were performed. Specific matters are described in the following examples.

Example 1

A titanium tetrachloride catalyst supported on triethylammonium (TEAL) and magnesium chloride was injected in a 4: 1 autoclave to which a helical ribbon type stirrer was attached. Next, the temperature was adjusted to 67 ° C., and propylene and ethylene were supplied at 96% by weight and 4% by weight, respectively, to carry out copolymerization.

Then, the supply of ethylene was stopped, and propylene and butylene were supplied at 98% by weight and 2% by weight, respectively, to polymerize. Next, the supply of butylene was stopped and only propylene was continuously maintained at a gauge pressure of 20 kg / cm ² to supply and polymerize.

After carrying out a series of copolymerizations over the above three steps, a small amount of the particles of the obtained copolymer, antioxidants and other additives were added and extruded to form molded particle materials. The following shows the composition of the resin used.

Such a composition is melt mixed in a twin screw extruder and poured into a barrel at 200 ° C. The barrel temperature is 210/230/240/220/220 and the rpm is also 150 to form a granular material for molding. The physical properties of the molded particle material made of such a resin are shown in Table 1.

TABLE 1

Example 2

In the same reactor as in Example 1, the temperature was changed to 80 ° C. and the polymerization was performed at a pressure of 30 kg / cm ₂ . The content of ethylene and butylene in the copolymer is the same as in Example 1, but the composition of the copolymer block is as follows.

Example 3

In the same reactor as in Example 1-2, the temperature was changed to 70 ° C. and the pressure was 25 kg / cm ^2. The content of ethylene and butylene in the copolymer was 7% by weight and 4% by weight, respectively. The composition was as follows.

Example 1-3 A pipe made of a polymeric resin was passed in for 1 hour Griffith pressure test conducted under a pressure of 20 ℃, 16N / mm ² 1,000Hr pressure conducted under a pressure of 95 ℃, 1.9N / mm ² The creep test also passed. This performance represents 50 years of durability at 65 ° C. Moreover, it passed both the low temperature impact strength test and high temperature numerical stability test (KS M3362) performed at 0 degreeC.

As described above, the present invention can obtain a copolymer for heating plastic pipe having a long pipe life, good workability and good transparency without degrading productivity and economy.

Claims (5)

(a) 70-98% by weight of propylene-ethylene copolymer block having 1-30% ethylene content, (b) 1-10% by weight of propylene-butylene copolymer block having 1-30% butylene content and (c A copolymer for heating plastic pipe forming comprising 1-29% by weight of propylene homopolymer block. (a) 70-99% by weight of propylene-ethylene copolymer block having 1-30% ethylene content and (b) 1-30% by weight of propylene-butylene copolymer block having 1-30% butylene content Copolymer for heating plastic pipe forming. A copolymer for forming a heating plastic pipe, comprising (a) 70-98% by weight of a propylene-ethylene copolymer block having an ethylene content of 1-30%, and (b) 2-30% by weight of a propylene homopolymer block. The composition for heating plastic pipe molding which added 13% or less of additive to the copolymer of any one of Claims 1-3. The composition for forming a heating plastic pipe according to claim 4, wherein the additive is an antioxidant of 5 wt% or less on a copolymer basis, an acid acceptor of 5 wt% or less on a copolymer basis and an ultraviolet stabilizer of 3 wt% or less on a copolymer basis.