KR20130055167A - High density polyethylene resin composition and molded article prepared therefrom - Google Patents

Abstract

PURPOSE: A high density polyethylene resin composition is provided to improve regeneration ratio of a resin and to have similar physical properties with a high density polyethylene resin, by including a large amount of recycled polyethylene resin. CONSTITUTION: A high density polyethylene resin composition comprises 70-99wt% of a crystalline high density polyethylene resin with a density of 0.935-0.980 g/cc and 1-30wt% of a re cycled high density polyethylene resin. The crystalline high density polyethylene resin has a weight average molecular weight(Mw) of 50,00-1,000,000. The melt index(ASTM D1238, 190 deg. C, 2.16kgf) is 0.1-40 g/10mins and crystallinity is 65-90%. The regeneration number of the high density polyethylene resin is 1-10.

Description

High-density polyethylene resin composition and molded article produced therefrom {HIGH DENSITY POLYETHYLENE RESIN COMPOSITION AND MOLDED ARTICLE PREPARED THEREFROM}

The present invention relates to a high density polyethylene resin composition and a molded article produced therefrom, and more particularly, to a high density polyethylene resin composition containing a regenerated high density polyethylene resin.

High-density polyethylene (HDPE) is a high-density polyethylene (HDPE) polymer, which is applied to various fields because it can produce a final product having high mechanical and chemical properties and high molecular weight through a simple process using a catalyst. have.

Recently, legislation on resource measures, such as the Enactment of the Law on Saving and Recycling of Resources, has been promoted, and the recycling of products, reuse of resources, and coping with waste reduction have been actively promoted. Recovery and regeneration of the products provided is an important challenge.

For example, packaging materials, disposable containers, pallets, etc. are mostly applied to the general-purpose plastic materials in consideration of moldability, light weight, price competitiveness, etc. In this field, it is necessary to reclaim waste molded products and establish a resin composition using the same. It is true. Among the general-purpose resins, the polyolefin resin may be deformed by applying heat again after being heated and molded with a thermoplastic resin, and has an advantage of facilitating extrusion and injection molding. Among these polyolefin resins, high-density polyethylene has been widely applied to household goods due to its excellent toughness and impact strength, and it is urgently required for recycling in terms of environmental pollution or recycling, but it is difficult to apply due to deterioration of physical properties and processability generated during resin recycling. There are disadvantages.

As a prior art for regenerating polyethylene-based resins, Korean Patent No. 0192887 discloses a resin recycling method of mixing waste low density polyethylene resins, waste polyethylene terephthalate resins and waste nylon resins with waste high density polyethylene resins. In the one-time limited, there is a problem that it is difficult to further recycle the multi-component combination.

In addition, non-patent literature (Polymer Degradation and Stability, Vol. 96, 1125-1133, 2011) confirms the change in physical properties according to the number of re-extrusion by molecular weight of the high-density polyethylene resin, It does not mention.

In addition, Korean Patent Application Publication No. 2010-0122303 discloses a resin composition containing a certain amount of a regenerated thermoplastic resin, but is not limited to ABS resin and does not mention the application to general polyethylene-based resin.

Accordingly, research on the development of a high-density polyethylene resin composition having the same physical properties as that of a new high-density polyethylene resin as a resin composition including the recycled high-density polyethylene resin will be required.

Accordingly, the present invention has been made to solve the above problems, to provide a high-density polyethylene resin composition having the same physical properties as the new high-density polyethylene resin while improving the regeneration rate of the resin by including a proper amount of the recycled high-density polyethylene resin.

Another object of the present invention is to provide a molded article including the recycled high density polyethylene resin.

As one embodiment for solving the above problems, the present invention is a high-density polyethylene resin composition comprising 70 to 99% by weight crystalline high-density polyethylene resin having a density of 0.935 ~ 0.970g / 및 and 1 to 30% by weight recycled high density polyethylene resin To provide.

In addition, the crystalline high density polyethylene resin provides a high density polyethylene resin composition, characterized in that the weight average molecular weight (Mw) is 50,000 ~ 1,000,000.

In addition, the crystalline high density polyethylene resin provides a high density polyethylene resin composition, characterized in that the weight average molecular weight (Mw) is 100,000 to 500,000.

In addition, the crystalline high density polyethylene resin provides a high density polyethylene resin composition, characterized in that the melt index (ASTM D1238, 190 ℃, 2.16kgf) is 0.1 ~ 40g / 10min.

In addition, the crystalline high density polyethylene resin provides a high density polyethylene resin composition, characterized in that the crystallinity is 65 ~ 90%.

In addition, the regenerated high density polyethylene resin provides a high density polyethylene resin composition, characterized in that the number of regeneration is 1 to 10 times.

As another embodiment for solving the above problems, the present invention, 50 to 99% by weight crystalline high-density polyethylene resin having a density of 0.935 ~ 0.970g / 및 and 1 to 50% by weight regenerated high density polyethylene resin having 1 to 4 regeneration times It provides a high density polyethylene resin composition comprising a.

In order to solve the another problem, the present invention provides a molded article manufactured using the high-density polyethylene resin composition.

In addition, the molded article provides a molded article, characterized in that any one selected from the group consisting of packaging materials, containers and pallets.

According to the present invention, by using an appropriate amount of regenerated high density polyethylene resin mixed with the crystalline high density polyethylene resin, it is possible to provide a high density polyethylene resin composition having the same physical properties as that of the new high density polyethylene resin while improving the recycling rate of the regenerated resin.

In addition, the high-density polyethylene resin composition can be effectively used in the field of molded products, such as plastic packaging materials, containers, pallets using injection molding.

Hereinafter, the present invention will be described in detail with reference to preferred embodiments. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims and their equivalents. It is to be understood that various equivalents and modifications may be substituted for those at the time of the present application.

According to one aspect of the present invention, there is disclosed a high density polyethylene resin composition comprising 70 to 99% by weight of a crystalline high density polyethylene resin having a density of 0.935 to 0.970 g / dl and 1 to 30% by weight of a regenerated high density polyethylene resin.

MEANS TO SOLVE THE PROBLEM In the high density polyethylene resin currently applied by various field | areas, in connection with the monocomponent high density polyethylene resin composition which does not contain components other than a high density polyethylene resin for the regeneration, the optimal composition of a new material is still Faced with the unestablished reality regarding the relationship between the optimum content of the compound and the effective number of regenerations, and after a thorough study, a regenerated high density polyethylene resin having an appropriate content and a constant regeneration number in a crystalline high density polyethylene resin having specific physical and chemical properties The present invention has been found to be able to provide a high-density polyethylene resin composition having the same physical properties as the new high-density polyethylene resin by mixing.

The crystalline high density polyethylene resin used in the present invention can be prepared using a Ziegler-Natta catalyst, and has a density of 0.935 to 0.970 g / cc. When the density of the crystalline high density polyethylene resin is less than 0.935g / ㏄, the molded article used as a container may be difficult to load when the molded article is used as a low flexural strength, if it exceeds 0.970g / 할 it may be disadvantageous in terms of low temperature impact properties Can be. In consideration of such bending strength and low temperature impact resistance, the crystalline high-density polypropylene resin more preferably has a density in the range of 0.950 to 0.965 g / 0.9.

In addition, it was confirmed that the crystalline high-density polyethylene resin is preferably to have a weight-average molecular weight (Mw) in the appropriate range in terms of molding processability, in addition to having equivalent physical properties to the high-density polyethylene resin is a new material of the desired resin composition. . That is, the weight average molecular weight of the crystalline high density polyethylene resin is preferably 50,000 ~ 1,000,000. However, compared to the range outside the weight average molecular weight of 100,000 ~ 500,000, the drop impact and molding processability is significantly improved, the most preferred range is 300,000 ~ 400,000. When the weight average molecular weight is less than 50,000, the low-temperature drop impact characteristics of the final molded product may be lowered due to the low molecular weight, and when the weight average molecular weight exceeds 1,000,000, it may be disadvantageous in terms of processability during final molding.

In addition, the crystalline high density polyethylene resin is preferably a melt index (ASTM D1238, 190 ℃, 2.16kgf) of 0.1 ~ 40g / 10min, more preferably 1 ~ 30g / 10min, It is still more preferable to use 2-20 g / 10min, and it is most preferable to use 5-10 g / 10min. When the melt index is less than 0.1g / 10min, the flowability of the final high density polyethylene resin composition may be too low to be suitable for the manufacture of injection molded articles, and when the melt index exceeds 40g / 10min, the impact strength of the final high density polyethylene resin composition is exceeded. May be slightly lower and not suitable for the manufacture of injection molded articles.

In addition, the crystalline high density polyethylene resin is not limited as long as it is a crystalline high density polyethylene resin in the above-described density range, the degree of crystallization by differential scanning calorimeter (DSC) analysis is preferably 65 to 90%, It is more preferable that it is 75 to 85%. When the degree of crystallinity is in the range of 65 to 90%, it can be made to exhibit the physical properties equivalent to that of the new high density polyethylene resin in terms of toughness, elongation and impact resistance of the high density polyethylene resin composition prepared.

Regenerated high density polyethylene resin used in the present invention is included 1 to 30% by weight compared to the final high density polyethylene resin composition. When the regenerated high density polyethylene resin is used alone, equivalent physical properties cannot be secured compared to the high density polyethylene resin, which is new when applied to a real product such as a plastic household goods container, and when excessively mixed with the new high density polyethylene resin. It was confirmed that it was difficult to secure satisfactory physical properties. That is, when using the regenerated high density polyethylene resin recycled up to 10 times in relation to the number of times of regeneration of the high density polyethylene resin to be described later, as compared to the final high density polyethylene resin composition as described above up to 30% by weight, ensures the same physical properties as the new high density polyethylene resin can do.

Therefore, when the content of the regenerated high density polyethylene resin used in the present invention is 1 to 30% by weight relative to the final high density polyethylene resin composition, it is preferable that the number of regenerations is 1 to 10 times.

In this regard, when the number of times of regeneration is smaller, even if the content of the regenerated high density polyethylene resin mixed with the high density polyethylene resin is increased, the physical properties equivalent to those of the new high density polyethylene resin may still be satisfied.

Therefore, according to another aspect of the present invention, 50 to 99% by weight of the crystalline high density polyethylene resin having a density of 0.935 ~ 0.970g / 및 and 1 to 50% by weight of the regenerated high density polyethylene resin having 1 to 4 regeneration times A high density polyethylene resin composition is disclosed.

Here, the density, the weight average molecular weight, the melt index, the crystallinity, and the like of the crystalline high density polyethylene resin are the same as in the case of one embodiment of the present invention described above, and a detailed description thereof will be omitted.

In the high-density polyethylene resin composition according to the present invention, as an additive in the range which does not impair the characteristics of the present invention, as an additive, a neutralizer, an antistatic agent, an antiblocking agent, a slip agent, a weathering / lightfast stabilizer, a pigment, an inorganic agent, an antioxidant, UV stabilizers and the like can be added. Such additives may be added when producing pellets from the high density polyethylene resin composition, and may be added when forming a molded body after pellet molding.

There is no restriction | limiting in particular as a method of manufacturing the high density polyethylene resin composition which concerns on this invention, The normal polyethylene resin composition manufacturing method can be used. For example, a method in which a crystalline high density polyethylene resin and a regenerated high density polyethylene resin are simultaneously added and uniformly mixed and then melt kneaded may be mentioned.

As a method of obtaining the homogeneous mixture, there is a method using, for example, a Henschel mixer, a ribbon blender, a blender, and the like. As the melt kneading method, there is a method using, for example, a Banbury mixer, a single screw or twin screw extruder. .

The shape of the high density polyethylene resin composition which concerns on this invention is a strand form, a sheet form, a flat form, a pellet form etc. are mentioned, for example.

The present invention provides a molded article manufactured using the high-density polyethylene resin composition, injection molding, compression molding, injection compression molding, gas injection injection molding, foam injection molding, inflation method, T-die method, calender so as to be suitable for the molded article use Method, blow molding, vacuum molding, pressure molding, or the like.

The molded article made of the high density polyethylene resin composition may have the same toughness, elongation and impact resistance as the high density polyethylene resin, which is a new material, and may be effectively used in the field of molded articles such as plastic packaging materials, containers, and pallets.

Hereinafter, the present invention will be described in more detail with reference to specific examples and comparative examples.

Example  One

Ethylene and Ziegler-Natta catalysts were charged to the polymerization reactor, slurry polymerization was carried out, and the melt index was adjusted by hydrogen to determine crystalline high density polyethylene resin (melt index 5.0 g / min (190 ° C, 2.16 kgf), density 0.965). g / dl, crystallinity 80%). 70 parts by weight of the crystalline high density polyethylene resin and 30 parts by weight of a new high density polyethylene resin were re-extruded, mixed for 1 minute in a Henschel mixer, and extruded at a reaction temperature of 170 to 250 ° C. using a twin screw extruder for pellets. High density polyethylene resin composition was obtained. The obtained pelletized resin composition was injected into a UBE 180-ton injection molding machine to prepare a physical property measurement specimen.

Example  2

A specimen was prepared in the same manner as in Example 1, except that the resin, which was re-extruded four times the high-density polyethylene resin of Example 1, was used.

Example  3

A specimen was prepared in the same manner as in Example 1, except that a resin obtained by re-extruding the new high-density polyethylene resin six times in Example 1 was used.

Example  4

A specimen was prepared in the same manner as in Example 1, except that a resin obtained by re-extruding the high-density polyethylene resin, which was a new material in Example 1, was used 8 times.

Example  5

A specimen was prepared in the same manner as in Example 1, except that a resin obtained by re-extruding the new high density polyethylene resin 10 times in Example 1 was used.

Example  6

A specimen was prepared in the same manner as in Example 1 except that 50 parts by weight of the crystalline high density polyethylene resin and 50 parts by weight of the new high density polyethylene resin were mixed.

Example  7

A specimen was prepared in the same manner as in Example 1, except that the resin, which was re-extruded four times a high-density polyethylene resin in Example 6, was used.

Comparative example  One

A specimen was prepared in the same manner as in Example 6, except that a resin obtained by re-extruding the new high density polyethylene resin six times in Example 6 was used.

Comparative example  2

A specimen was prepared in the same manner as in Example 6, except that a resin obtained by re-extruding the new high density polyethylene resin 8 times in Example 6 was used.

Comparative example  3

A specimen was prepared in the same manner as in Example 6, except that a resin obtained by re-extruding the new high density polyethylene resin 10 times in Example 6 was used.

Comparative example  4

A specimen was prepared in the same manner as in Example 1 except that only the crystalline high density polyethylene resin was added in Example 1.

The components and compositions according to the Examples and Comparative Examples are summarized in Table 1 below.

division A (part by weight) B1 (part by weight) B2 (part by weight) B3 (part by weight) B4 (part by weight) B5 (part by weight) Example 1 70 30 - - - - Example 2 70 - 30 - - - Example 3 70 - - 30 - - Example 4 70 - - - 30 - Example 5 70 - - - - 30 Example 6 50 50 - - - - Example 7 50 - 50 - - - Comparative Example 1 50 - - 50 - - Comparative Example 2 50 - - - 50 - Comparative Example 3 50 - - - - 50 Comparative Example 4 100 - - - - - * Note
A: crystalline high density polyethylene resin
-B1 to B5: High-density polyethylene resin which re-extruded new high-density polyethylene resin (A) 2, 4, 6, 8, 10 times

Evaluation of the physical properties as described below for the high-density polyethylene resin composition according to the above Examples and Comparative Examples, and the measurement results are shown in Table 2 below.

[Property evaluation]

(1) yield point stress

Injection specimens were measured at 23 ° C. and 50% relative humidity according to ASTM D638.

(2) elongation at break

Injection specimens were measured at 23 ° C. and 50% relative humidity according to ASTM D638.

(3) Falling impact strength (Du-Pont impact strength)

It carried out by the method used by Honam Petrochemical Co., Ltd. That is, the energy required for fracture of the specimen was measured when a rod defined in the specimen having a thickness of 2 mm was installed and the predetermined load was dropped at a certain height.

division Yield point stress
(Kgf / cm2) Breaking point elongation
(%) Falling Impact Strength
(Kgcm) Example 1 266 500 200 Example 2 267 500 200 Example 3 266 500 200 Example 4 266 500 200 Example 5 267 500 200 Example 6 270 500 200 Example 7 274 500 200 Comparative Example 1 289 437 170 Comparative Example 2 289 332 170 Comparative Example 3 290 308 170 Comparative Example 4 267 500 200

As shown in Table 2, the high-density polyethylene resin composition (Examples 1 to 5) containing 30% by weight of a regenerated high-density polyethylene resin in the crystalline high-density polyethylene resin according to the present invention is equivalent to the new material (Comparative Example 4) It can be seen that the physical properties are shown, and the equivalent physical properties are maintained even when using a recycled high density polyethylene resin having 10 regeneration times.

On the other hand, the high-density polyethylene resin composition containing 50% by weight of the regenerated high-density polyethylene resin is increased yield point showing the curing characteristics of the resin when using a high-density polyethylene resin having a number of regeneration more than four times (Comparative Examples 1 to 3), Elongation rate decrease and impact strength fall. On the other hand, even when 50% by weight of regenerated high density polyethylene resin is used, when the number of regeneration is 4 or less (Examples 6 and 7), the yield point stress is equivalent to that of the new material (Comparative Example 4) except that the yield point stress is slightly increased. It can be seen that the physical properties are maintained.

As described above, by using an appropriate amount of a regenerated high density polyethylene resin having an appropriate number of regeneration times in the crystalline high density polyethylene resin according to the present invention, a high density polyethylene having the same physical properties as a new high density polyethylene resin while improving the recycling rate of the regenerated resin It can be confirmed that the resin composition can be provided.

Claims (9)

A high density polyethylene resin composition comprising 70 to 99% by weight of a crystalline high density polyethylene resin having a density of 0.935 to 0.970 g / dl and 1 to 30% by weight of a regenerated high density polyethylene resin. The method of claim 1,
The crystalline high density polyethylene resin has a weight average molecular weight (Mw) of 50,000 to 1,000,000 high density polyethylene resin composition. The method of claim 1,
The crystalline high density polyethylene resin has a weight average molecular weight (Mw) of 100,000 to 500,000, characterized in that the high density polyethylene resin composition. The method of claim 1,
The crystalline high density polyethylene resin has a melt index (ASTM D1238, 190 ℃, 2.16kgf) is 0.1 ~ 40g / 10min, characterized in that the high density polyethylene resin composition. The method of claim 1,
The crystalline high density polyethylene resin is a high density polyethylene resin composition, characterized in that the crystallinity is 65 ~ 90%. The method of claim 1,
The regenerated high density polyethylene resin is a high density polyethylene resin composition, characterized in that the number of regeneration of 1 to 10 times. A high density polyethylene resin composition comprising 50 to 99% by weight of a crystalline high density polyethylene resin having a density of 0.935 to 0.970 g / g and 1 to 50% by weight of a regenerated high density polyethylene resin having 1 to 4 regeneration times. The molded article manufactured using the high density polyethylene resin composition of any one of Claims 1-7. 9. The method of claim 8,
The molded article is a molded article, characterized in that any one selected from the group consisting of packaging materials, containers and pallets.