KR101002760B1 - Preparation method of high-density polyethylene - Google Patents

Abstract

PURPOSE: A high density polyethylene resin is provided to prepare products with small thickness deviation and excellent falling shock resistance in blow molding of medium-to large-sized products due to high melt tension and excellent parison stability. CONSTITUTION: A method for preparing a high density polyethylene resin comprises the steps of: extruding high density polyethylene resin powder to prepare a partially crosslinked high-density polyethylene resin; mixing low density polyethylene powder, peroxide and at least one selected from the group consisting of an antioxidant and a neutralizing agent; extruding the mixed product to form a low density polyethylene master batch; and extruding the mixture of the partially crosslinked high-density polyethylene resin and the low density polyethylene master batch.

Description

Manufacturing method of high density polyethylene resin {PREPARATION METHOD OF HIGH-DENSITY POLYETHYLENE}

The present invention relates to a method for producing a high-density polyethylene resin, and more particularly, exhibits high melt tension and excellent parison stability, and has a very small portion thickness variation and excellent drop impact strength even when a medium to large blow molding of 20 liters or more. A method for producing a high density polyethylene resin capable of producing a product.

High-density Polyethylene (HDPE) is a polymer composed of carbon and hydrogen only, and it is possible to produce a final product having high mechanical and chemical properties and high molecular weight even through a simple process using a catalyst. Is being applied.

Various molded products, for example, various containers are manufactured by using high density polyethylene. When blow molding a large-capacity molded product, the thickness variation of the upper and lower parts of the final molded product is decreased due to the low melt tension of the high density polyethylene. Will be created. As the thickness variation of each part of the final molded product becomes larger, the drop impact resistance is lowered and the quality of the final product is lowered. Therefore, efforts have been made to increase the melt tension or the weight average molecular weight of the high density polyethylene.

Thus, attempts have been made to increase the melt tension by adding peroxides to high density polyethylenes prepared using chromium-based catalysts, but these techniques are difficult to apply to high density polyethylenes prepared using Ziegler-Natta catalysts, The melt tension of the resin does not improve to the extent that it is suitable for molded products. In addition, a technique has been proposed in which a peroxide is added to a high density polyethylene mixture of low molecular weight and high molecular weight prepared by a Ziegler-Natta catalyst to improve processability and improve impact strength. However, two types of high density polyethylene should be used. However, there is a problem that a complicated process must be applied. In addition, although a method for producing parison stability has been proposed by reaction extrusion of a mixture of high density polyethylene powder and peroxide and high density polyethylene, the peroxide used as a crosslinking agent is not easily dispersed, resulting in a rough surface of the final product. There is a problem that the melt tension of the resin is not sufficient.

The present invention is to provide a method for producing a high-density polyethylene resin exhibiting a high melt tension and excellent parison stability, to produce a product having a small portion thickness variation and excellent drop impact strength during the medium-large blow molding of 20 liters or more .

The present invention comprises the steps of: extruding a high density polyethylene resin powder prepared using a Ziegler-Natta catalyst and having a density of 0.930 to 0.965 g / cc to form a partially crosslinked high density polyethylene resin; And kneading the low density polyethylene resin powder having a density of 0.900 to 0.925 g / cc, at least one additive selected from the group consisting of peroxides, antioxidants and neutralizing agents; Extruding the result of the kneading step to form a low density polyethylene masterbatch; And extruding a mixture of the partially crosslinked high density polyethylene and low density polyethylene masterbatch.

Hereinafter, a method of manufacturing a high density polyethylene resin according to a specific embodiment of the invention will be described in detail.

According to one embodiment of the invention, by using a Ziegler-Natta-based catalyst and extruding a high density polyethylene resin powder having a density of 0.930 to 0.965g / cc to form a partially cross-linked high density polyethylene resin; And kneading the low density polyethylene resin powder having a density of 0.900 to 0.925 g / cc, at least one additive selected from the group consisting of peroxides, antioxidants and neutralizing agents; Extruding the result of the kneading step to form a low density polyethylene masterbatch; And extruding a mixture of the partially crosslinked high density polyethylene and low density polyethylene masterbatch.

When the inventors of the present invention provide a method of manufacturing the method comprising the step of mixing and exposing the partially crosslinked high density polyethylene resin and the low density polyethylene masterbatch, it can be confirmed that a high density polyethylene resin having excellent parison stability and high melt tension can be produced. And completed the invention. Accordingly, according to the manufacturing method of the high-density polyethylene resin of one embodiment of the invention, it is possible to produce a product having a very small portion of the thickness variation and excellent drop impact strength even when medium-large blow molding of 20 liters or more.

The partially crosslinked high density polyethylene resin may be prepared using a Ziegler-Natta based catalyst and formed by extruding a high density polyethylene resin powder having a density of 0.930 to 0.965 g / cc. When heat is injected into the high-density polyethylene, crosslinking occurs in the polymer. As the high-density polyethylene resin powder is extruded without including an additive such as a crosslinking agent, a partially crosslinked high-density polyethylene resin may be formed. As the partially crosslinked high density polyethylene resin is crosslinked again by reacting with the peroxide included in the low density polyethylene masterbatch, the melt tension of the finally produced high density polyethylene resin is increased.

The partially crosslinked high density polyethylene resin means a state in which a part of the high density polyethylene resin is crosslinked by heating without applying a crosslinking agent such as a peroxide. In this case, the degree of crosslinking of the high density polyethylene resin may be measured through molecular weight distribution (Mz / Mn) through GPC (Gel permeation Chromatography) analysis. The molecular weight distribution (Z-average molecular weight / number average molecular weight, Mz / Mn) value can show the distribution of the high molecular weight component, but the molecular weight distribution (Mz / Mn) value in one compound is high molecular weight component, That is, the proportion of the component having a large degree of crosslinking is relatively increased. Therefore, it can be confirmed that partial crosslinking occurred by heating through increasing the molecular weight distribution (Mz / Mn) of the high density polyethylene resin.

In one embodiment of the invention, the increase rate of the molecular weight distribution (Mz / Mn) of the partially crosslinked high density polyethylene resin may be 1 to 50%. The rate of increase in this molecular weight distribution (Mz / Mn) can be defined by the following general formula (1):

[Formula 1]

Increase rate of molecular weight distribution (Mz / Mn) = (molecular weight distribution (Mz / Mn) of partially crosslinked high density polyethylene resin after extrusion-molecular weight distribution (Mz / Mn) of high density polyethylene resin powder before extrusion) / high density polyethylene resin before extrusion Molecular weight distribution of powder (Mz / Mn)

Application of a partially crosslinked high density polyethylene resin having an increase in the molecular weight distribution defined by this formula of 1 to 50% increases the high molecular weight component ratio and the melt tension of the high density polyethylene resin, and thus the low density polyethylene masterbatch and In the step of mixing and extruding, only a small amount of crosslinking agent (peroxide) may increase the melt tension of the final molded product.

When the increase rate of the molecular weight distribution (Mz / Mn) is less than 1%, the ratio of the high molecular weight component in the high-density polyethylene resin is not high enough to be applied to the excess peroxide when cross-linking in the future, and thus the degree of dispersion of the crosslinking agent Lowering may not facilitate the molding of the final molded product. In addition, when the increase rate of the molecular weight distribution (Mz / Mn) exceeds 50%, the high-density polyethylene resin is excessively cross-linked, an excessive load may be applied to the molding machine in the manufacture of the final molded product.

On the other hand, the partially crosslinked high density polyethylene resin in one embodiment of the invention has a higher melt tension than the non-crosslinked high density polyethylene resin because of the high proportion of high molecular weight components in the resin, and the high density polyethylene crosslinked as a whole using a crosslinking agent. The difference is that the foreign matter content is very low compared to the resin and easy to recrosslink.

The partially crosslinked high density polyethylene resin may have a melt index (ASTM D 1238, 190 ° C., load 2.16 Kg) of 0.01 to 10.0 g / 10 minutes, preferably 0.02 to 5.0 g / 10 minutes. If the melt index exceeds 10.0g / 10 minutes, the melt tension of the finally crosslinked high density polyethylene is too low to be suitable for the production of medium and large blow molded products, and if the melt index is less than 0.01g / 10 minutes, the final crosslinked high density The flowability of polyethylene resins is so low that they are not suitable for the production of blow molded articles.

In addition, the partially crosslinked high density polyethylene resin may have a weight average molecular weight of 50,000 to 1,000,000, preferably 100,000 to 800,000. When the weight average molecular weight is less than 50,000, the drop impact strength of the final product is low due to the low molecular weight, and when the weight average molecular weight is more than 1,000,000, the processability is lowered when forming the final product.

The partially crosslinked high density polyethylene resin may have a density of 0.935 to 0.965 g / cc. If the density is less than 0.935g / cc, there is a disadvantage that the bending strength of the molded product is low and difficult to load, if the density exceeds 0.965 g / cc is reduced environmental stress resistance and low temperature impact resistance.

Meanwhile, in one embodiment of the present invention, the forming of the partially crosslinked high density polyethylene resin is performed using the Ziegler-Natta-based catalyst, and the high density polyethylene resin powder having a density of 0.930 to 0.965 g / cc is 150 to 250. It may include the step of extruding at 0.5 ℃ for 6 minutes. If the temperature in the extrusion step is less than 150 ℃ or the residence time is less than 0.5 minutes, the degree of crosslinking of the high-density polyethylene resin powder is insignificant, and when the temperature is more than 250 ℃ or residence time is more than 6 minutes the high density Polyethylene resin powders are excessively crosslinked and are not suitable for producing high density polyethylene with adequate melt tension. At this time, the type of extruder used to extrude the high-density polyethylene resin powder is not particularly limited, it is possible to use a conventional single- or twin-screw extruder.

On the other hand, the step of kneading the low density polyethylene resin powder having a density of 0.900 to 0.925g / cc, peroxide, at least one additive selected from the group consisting of antioxidants and neutralizing agents using a mixer at 1 to 90 to 120 ℃ It can be done for 15 minutes. When kneading while rotating at a high speed using a mixer within the temperature and time ranges, a kneaded body in which the low density polyethylene resin powder, the peroxide, and the additives are uniformly dispersed may be formed. In this kneading step, a conventionally used mixer can be used without particular limitation, and preferably a Henschel mixer can be used. On the other hand, the result of the kneading step is 60 to 99.98% by weight of a low density polyethylene resin powder; 0.01-20.00 wt% peroxide; And 0.01 to 20.00% by weight of one or more additives selected from the group consisting of antioxidants and neutralizing agents.

If the content of the peroxide is less than 0.01% by weight crosslinking of the finally produced high-density polyethylene does not occur properly, the desired melt tension is not obtained, if it exceeds 20.00% by weight after the low density polyethylene master batch is mixed with the partially crosslinked high-density polyethylene resin Melting does not occur well during the extrusion process, which is undesirable for product molding.

When the content of the antioxidant or neutralizing agent is less than 0.01% by weight, when forming the final cross-linked high-density polyethylene, the peroxide, which is a crosslinking agent, does not uniformly cause crosslinking reaction, thereby lowering the physical properties of the final product, and when the content is more than 20.00% by weight. The crosslinking reaction of the peroxides is inhibited and the final crosslinked high density polyethylene product is unable to obtain high melt tension.

The low density polyethylene resin powder may have a melt index (ASTM D 1238, 190 ° C., load 2.16 Kg) of 0.08 to 70.0 g / 10 minutes, preferably 0.15 to 20.0 g / 10 minutes. If the melt index exceeds 70.0 g / 10 minutes, the melt tension of the finally produced high density polyethylene is low, which is not suitable for the production of hollow molded products, if less than 0.08 g / 10 minutes in the process of manufacturing a low density polyethylene master batch Due to pressure limitations on the reactor, it is not suitable for producing low density polyethylene masterbatches.

In addition, the low density polyethylene resin powder may have a density of 0.900 to 0.925 g / cc. If the density is less than 0.900 g / cc, it is difficult to load the molded product due to the low bending strength, when the density exceeds 0.925 g / cc it becomes low environmental stress resistance of the final product.

In addition, the low density polyethylene resin powder may have a weight average molecular weight of 50,000 to 500,000, preferably 100,000 to 300,000. If the weight average molecular weight is less than 50,000, it is not preferable due to the low melt tension of low density polyethylene when forming the final product, and if it is more than 500,000, it is not preferable because it may cause kneading problems when mixing the low density polyethylene master batch.

The peroxide is uniformly dispersed through an extruder together with an additive such as an antioxidant or a neutralizing agent to form a low density polyethylene master batch, and mixed with a partially crosslinked high density polyethylene resin to form a radical to crosslink the crosslinked high density polyethylene again to melt it. It increases the tension. It is preferable that such a peroxide has a half-life temperature of 120 ° C. or higher at atmospheric pressure, for example, di-isobutyl peroxide, di-isopropyl-peroxydicarbonate, 1,1,3,3-tetramethylbutyl peroxynedode Decanoate, di-n-propyl peroxydicarbonate, t-amyl peroxyneododecanoate, di- (4-t-butyl-cyclohexyl) peroxydicarbonate, di- (2-ethylhexyl) peroxydicarbonate , t-butyl peroxy neododecanoate, di-n-butyl peroxydicarbonate, dicetyl peroxydicarbonate, t-butyl peroxyneheptanoate, di- (3,5,5-trimethylhexanoyl) per Oxide, dilauryl peroxide, didecanoyl peroxide, 2,2-diazobutylonitrile, 2,2-azodi- (2-methylbutylnitrile), 2,5-dimethyl-2,5-di (2-ethylhexanoyl peroxy) -hexane, 1,1,3,3-tetramethylbutyl peroxy 2-ethylhexanoate, t-amyl Oxy-2-ethylhexanoate, dibenzoyl peroxide, t-butyl peroxy-2-ethylhexanoate, t-butylperoxydiethyl acetate, t-butyl peroxyisobutylate, 1,1, -di -(t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-di- (t-butylperoxy) -cyclohexane, t-amyl peroxy-2-ethylhexylcarbonate, t- Butylperoxy-3,5,5-trimethylhexanoate, 2,2-di- (t-butylperoxy) -butane, t-butylperoxyisopropylcarbonate, t-butylperoxy-ethylhexylcarbonate, t-butylperoxy acetate, t-butylperoxybenzoate, di-t-amylperoxide, dicumylperoxide, hexabromocyclododecane, di- (2-t-butylperoxy-isopropyl) -benzene , 2,5-dimethyl-2,5-di- (t-butylperoxy) hexane, t-butylcumylperoxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3 , Di-t-butyl peroxide, 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonane, di-isopropyl Lofilbenzene-monohydroperoxide, p-mentane hydroperoxide, cumyl hydroperoxide, 1,1,3,3-tetramethylbutylhydroperoxide, t-butylhydroperoxide, t-amylhydroperoxide, 2 , 3-dimethyl-2,3-diphenylbutane or mixtures thereof.

The antioxidant is 2,6-di-tert-butylbutyl-hydroxy toluene, tetrakis methylene (3,5-di-thi-butyl-4-hydroxy-hydrocinnamate) methane, 1,2-bis (3,5-di-tert-butyl-4-hydroxyhydrocinamoli) hydrazine, octadecyl 3- (3,5-di-thi-butyl-4-hydroxyphenyl) propionate, tris (4- Tertiary butyl 2,6 dimethyl 3-hydroxybenzyl) isocyanurate, 4,4-thiobis- (3-methyl-6-thi-butylphenol), 1,3,5-tris (3,5- Di-tert, butyl-4-hydroxybenzyl) -triazine-2,4,6 (1H, 3H, 5H) trione, tris (2,4-di-thi-butyl phenyl) phosphite, bis (2 , 4-di-butylphenyl) pentatritriol diphosphite, 2,4,6-tri-thi-butylphenyl2-butyl-2ethyl-1,3-propanediol phosphite, trisnonyl phenyl phosphite, Dilauryl-3,3-thio-di-propionate, dissteryl-3,3-thio-di-propionate, mixtures thereof, and the like. .

The neutralizing agent may include calcium stearic acid, zinc stearic acid, magnesium aluminum hydroxy carbonate, zinc oxide, magnesium hydroxy stearic acid or mixtures thereof.

Meanwhile, the low density polyethylene master batch may refer to a compound in a pellet form in which the low density polyethylene resin powder, the peroxide, and the additive are concentrated to a high concentration and uniformly dispersed. In one embodiment of the invention, since the 10-hour half-life temperature is 120 ° C. or more, the low density polyethylene master batch may be present as a substantially uncrosslinked state.

Since the peroxides and additives are uniformly kneaded in the low-density polyethylene masterbatch, the improvement of the melt tension of the high-density polyethylene resin by the peroxide can be maximized, and additives such as antioxidants and neutralizers are suitable for high-density polyethylene resins. Can be given.

The forming of the low density polyethylene masterbatch may include extruding the result of the kneading step at 90 to 120 ° C. for 1 to 6 minutes. The extrusion processability of the low density polyethylene resin powder is lowered when the temperature is less than 90 ° C. or the residence time is less than 1 minute in the extrusion step, and when the temperature is more than 120 ° C. or the residence time is more than 6 minutes, the peroxide is subjected to the crosslinking reaction. Participating more than necessary, the crosslinking reaction may not occur smoothly in the forming step of the final high density polyethylene resin. At this time, the type of extruder used is not particularly limited, it is possible to use a single- or twin-screw extruder commonly used.

Meanwhile, the mixture of the partially crosslinked high density polyethylene resin and the low density polyethylene masterbatch may be formed by dry mixing 60 to 90% by weight of the partially crosslinked high density polyethylene resin and 1 to 40% by weight of the low density polyethylene masterbatch. Through such dry mixing, the partially crosslinked high density polyethylene and the low density polyethylene masterbatch can be evenly mixed, whereby crosslinking by peroxide occurs uniformly in the whole resin, and a high density polyethylene resin having high melt tension can be produced. . In the dry mixing step, a commonly used mixer such as a tumbler mixer may be used without particular limitation. When the content of the partially crosslinked high density polyethylene resin is less than 60% by weight, the density of the resin to be produced is low, so that the rigidity is low, so it is not suitable for medium and large blow molding, and when the content is more than 99% by weight, the content of the low density polyethylene master batch This lowers the degree of crosslinking of the resin, thereby lowering the melt tension of the final high density polyethylene resin.

Extruding the mixture of the partially crosslinked high density polyethylene resin and the low density polyethylene masterbatch may be performed at 150 to 250 ° C. for 0.5 to 6 minutes. If the temperature in the extrusion step is less than 150 ℃ or the residence time is less than 0.5 minutes, the degree of crosslinking of the finally produced high-density polyethylene resin is insignificant, it may be difficult to process due to the pressure load of the extruder during extrusion processing, the temperature If is higher than 250 ℃ or residence time is more than 6 minutes, the final high-density polyethylene resin is decomposed to obtain a proper melt tension. At this time, the type of extruder used is not particularly limited, it is possible to use a single- or twin-screw extruder commonly used.

Meanwhile, the partially crosslinked high density polyethylene resin and low density polyethylene masterbatch may be in the form of a pellet. When the partially crosslinked high-density polyethylene resin and low-density polyethylene masterbatch are mixed and extruded in the form of pellets, they are well dispersed in a molten state and crosslinking reaction occurs easily, thereby increasing the melt tension of the high-density polyethylene produced.

In the manufacturing method of an embodiment of the present invention, additives such as UV stabilizer, anti static agent, slip agent, or anti blocking agent may be additionally added depending on the field in which the final product is applied. Applicable

According to the present invention, there can be provided a method for producing a high-density polyethylene resin exhibiting a high melt tension and excellent parison stability, which can produce a product having a small portion thickness variation and excellent impact resistance strength during medium-large blow molding of 20 liters or more. have.

< Example : Manufacturing of High Density Polyethylene Resins>

Example  One

 A high-density polyethylene resin powder prepared using a Ziegler-Natta catalyst and having a density of 0.950 g / cc and a weight average molecular weight of 299,600 was set to a twin screw extruder (SMPLATEK TEK 40-MHS, Screw diameter 40 mm) and extruded while staying in the extruder for an average of 1.8 minutes to produce partially crosslinked high density polyethylene resin pellets.

At this time, the increase ratio of the molecular weight distribution (Mz / Mn) measured using GPC (Gel Permeation Chromoatography, PolyLaboratories) was 20.0%, and the melt index (ASTM D 1238-65T, 190 ° C, load) of the partially crosslinked high density polyethylene resin 2.16 Kg) was 0.04, the density was 0.947 g / cc and the weight average molecular weight was 431,600.

Low density polyethylene resin powder prepared by high pressure autoclave process with melt index (ASTM D 1238-65T, 190 ° C, load 2.16Kg) 0.3g / 10min, density 0.920g / cc, weight average molecular weight 350,000 % And 3% by weight of peroxide di-t-butylperoxide and 1.5% by weight of antioxidant octadecyl 3- (3,5-di-thi-butyl-4-hydroxyphenyl) propionate were added to the Henschel mixer. The mixture was uniformly kneaded at room temperature for 3 minutes.

The kneaded compound was pelletized by a single screw extruder (EMS HSE40-32X, screw diameter 40mm) set at an extrusion temperature of about 110 ° C. and a screw rotation speed of 50 rpm, and extruded while remaining in the extruder for an average of 2.5 minutes. Pelletized low density polyethylene master batches were prepared.

80% by weight of the partially crosslinked high density polyethylene pellets and 20% by weight of the low density polyethylene master batch pellets were dry mixed by spinning for about 20 minutes through a tumbler mixer.

The partially crosslinked high-density polyethylene and low-density polyethylene master batch dry mixture was put into a twin screw extruder (SMPLATEK TEK 40-MHS, screw diameter 40mm) set at an extrusion temperature of 210 ° C. and a screw rotation speed of 60 rpm, and extruded while staying for 1.8 minutes to pellet A high density polyethylene resin was prepared.

Example  2

97% by weight of low density polyethylene, 1.5% by weight of peroxide di-t-butylperoxide and 1.5% by weight of antioxidant octadecyl 3- (3,5-di-thi-butyl-4-hydroxyphenyl) propionate Except for the use, pelletized high density polyethylene resin was prepared in the same manner as in Example 1.

Example  3

97.5% by weight of low density polyethylene, 1% by weight of peroxide di-t-butylperoxide and 1.5% by weight of antioxidant octadecyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate Except for the use, pelletized high density polyethylene resin was prepared in the same manner as in Example 1.

< Comparative example : Manufacturing of High Density Polyethylene Resins>

Comparative example  One

A high density polyethylene resin prepared using a Ziegler-Natta catalyst, having a melt index (ASTM D 1238-65T, 190 ° C., load 2.16 Kg) of 0.035 g / 10 min, a density of 0.950 g / cc, and a weight average molecular weight of 394,000. 99.4 wt% of the powder was impregnated with 0.6 wt% of di-t-butylperoxide. At this time, the impregnation was performed by rotating for about 5 minutes at a high speed at 120 ℃ using a Henschel mixer. The impregnated compound was dry mixed by rotating for about 20 minutes through a tumbler mixer at room temperature.

The high-density polyethylene powder resin impregnated with the peroxide was introduced into a twin screw extruder (SMPLATEK TEK 40-MHS, screw diameter 40mm) set at an extrusion temperature of 210 ° C. and a screw rotation speed of 60 rpm, and extruded while staying for 1.8 minutes to pellet high density. Polyethylene resins were prepared.

< Experimental Example >

Experimental Example 1 : Melt Tension Measurement Experiment

Melt tension of the high density polyethylene resin pellets prepared in Examples 1 to 3 and Comparative Example 1 was measured using a Melten Rheometer (Toyose, Japan, Toyoseki DILAMATC 8E), the results are shown in FIG.

Experimental Example 2 : Drop impact measurement experiment

The high-density polyethylene resin pallets prepared in Examples 1 to 3 and Comparative Example 1 were blow molded (using BLOMA's BM45D-E80 product) to prepare containers, and these containers were filled with an antifreeze solution and then stored at -40 ° C for 24 hours. Frozen. By dropping the frozen container at a height of 6m to observe how many times the container was broken to measure the impact resistance, and the results are shown in Table 1 below.

Table 1

division Example 1 Example 2 Example 3 Comparative Example 1 Volume of the container (L) 20 20 20 20 Low temperature drop impact strength 7 or more times 7 or more times 7 or more times Ruptured after 4 times Exterior Good Great Great Bad

As shown in Figure 1, the high density polyethylene resin according to the embodiment shows a higher melt tension than the high density polyethylene resin according to the comparative example, the melt tension is changed according to the content of the peroxide.

In addition, since the high-density polyethylene resin according to an embodiment of the present invention has a high melt tension, the parison is excellent in stability even in a large-capacity blow molding (20L), there is almost no thickness variation for each part of the manufactured molded article. As the thickness variation of each part of the molded part is smaller, the shock is more evenly absorbed and the drop impact resistance is increased. As shown in Table 1, the container manufactured using the high density polyethylene resins of Examples 1 to 3 is Comparative Example 1 As compared with the container manufactured using the high-density polyethylene resin of this, the drop impact resistance is large and it can confirm that the thickness of each part of the molded article by an Example is uniform.

As a result of observing the appearance of the container prepared above, the container prepared using the high-density polyethylene resin of Examples 1 to 3 showed good surface condition as the peroxide was uniformly dispersed and prepared, whereas Comparative Example 1 The surface condition was found to be poor.

Figure 1 shows the results of measuring the melt tension with time of the high density polyethylene resin according to Examples 1 to 3 and Comparative Example 1.

Claims (11)

Extruding a high density polyethylene resin powder prepared using a Ziegler-Natta based catalyst and having a density of 0.930 to 0.965 g / cc to form a partially crosslinked high density polyethylene resin; And Kneading a low density polyethylene resin powder having a density of 0.900 to 0.925 g / cc, at least one additive selected from the group consisting of peroxides, antioxidants and neutralizing agents; Extruding the result of the kneading step to form a low density polyethylene masterbatch; And Extruding the mixture of the partially crosslinked high density polyethylene and low density polyethylene masterbatch. The method of claim 1, A method for producing a high density polyethylene resin having an increase ratio of the molecular weight distribution (Mz / Mn) of the partially crosslinked high density polyethylene resin is 1 to 50%. The method of claim 1, The partially crosslinked high density polyethylene resin has a melt index of 0.01 to 10.0 g / 10 minutes (ASTM D 1238, 190 ° C., load 2.16 Kg), a density of 0.935 to 0.965 g / cc and a weight average molecular weight of 50,000 to 1,000,000 Method for producing polyethylene resin. The method of claim 1, The forming of the partially crosslinked high density polyethylene resin includes extruding the high density polyethylene resin powder at 150 to 250 ° C. for 0.5 to 6 minutes. The method of claim 1, The kneading step is a method for producing a high density polyethylene resin is made for 1 to 15 minutes at 90 to 120 ℃ using a mixer The method of claim 1, The result of the kneading step is 60 to 99.98% by weight of a low density polyethylene resin powder having a density of 0.900 to 0.925g / cc; 0.01-20.00 wt% peroxide; And 0.01 to 20.00% by weight of one or more additives selected from the group consisting of antioxidants and neutralizing agents. The method of claim 1, The low density polyethylene resin powder has a melt index (ASTM D 1238, 190 ° C., load 2.16 Kg) of 0.08 to 70.0 g / 10 minutes and a weight average molecular weight of 50,000 to 500,000. The method of claim 1, Forming the low density polyethylene masterbatch comprises the step of extruding the result of the kneading step for 1 to 6 minutes at 90 to 120 ℃. The method of claim 1, The mixture of the partially crosslinked high density polyethylene resin and the low density polyethylene masterbatch is formed by dry mixing 60 to 99% by weight of the partially crosslinked high density polyethylene resin and 1 to 40% by weight of the low density polyethylene masterbatch. The method of claim 1, Extruding the mixture of the partially crosslinked high density polyethylene resin and the low density polyethylene masterbatch at a temperature of 150 to 250 ° C. for 0.5 to 6 minutes. The method of claim 1, Wherein said partially crosslinked high density polyethylene resin and low density polyethylene masterbatch are in the form of a pellet.

Images