KR0177308B1 - Thermoplastic polyolefin resin containing very low density polyethylene - Google Patents

Abstract

The present invention (A) 60 to 80% by weight propylene polymer; (B) A thermoplastic material containing a rubbery material and (C) an ultra low density polyethylene obtained by mixing (B) + (C) with 20 to 40% by weight of an ultra low density polyethylene having a density of 0.85 to 0.95 g / cm 3. It relates to a polyolefin resin. This resin is particularly useful for automobile exterior materials because of its excellent mechanical properties and low temperature impact strength.

Description

Thermoplastic Polyolefin Resin Containing Ultra Low Density Polyethylene

The present invention relates to thermoplastic polyolefin resins containing ultra low density polyethylene (VLDPE).

Typical thermoplastic polyolefin resin compositions used as automotive exterior materials consist of polypropylene, ethylene propylene (diene) rubber and fillers. Of these, some or all of the ethylene propylene (diene) rubber component is made of ultra low density polyethylene, thereby exhibiting excellent material properties. In particular, the composition containing ultra low density polyethylene has excellent physical properties, mechanical strength, and heat deformation resistance, compared to general polypropylene and olefin resin compositions made of ethylene propylene rubber, and is very easy to handle during extrusion and injection, and also has various fluidity levels. The advantage is that ultra low density polyethylene can be selected.

There are many examples of modifying physical properties by mixing characteristic materials with thermoplastic polyolefin resins.

Japanese Patent No. 5-51498 has 50-75 parts by weight of polypropylene, 15-30 parts by weight of ethylenebutene and ethylene propylene rubber, and 5-20 parts by weight of talc, thereby providing high low temperature impact strength, rigidity and low linear expansion characteristics. In addition, Japanese 4-372637 is a thermoplastic polymer composition, which has good processability, good appearance, and good surface strength and impact resistance during injection molding by ethylene propylene rubber, ethylene copolymer and propylene polymer. The composition for automobile parts excellent in paintability is proposed. Japanese Patent 5-98097 proposes a composition having excellent physical properties such as impact resistance, stiffness, and hardness, including 80 to 60 parts by weight of polypropylene component and 20 to 40 parts by weight of pretrained rubber component. Japanese Patent No. 5-295224 has excellent moldability due to high flow propylene-ethylene block copolymer, ethylene propylene rubber, high flow ethylene butene monomer, high flow polyethylene, and fine talc, and has excellent impact resistance, mechanical strength, heat deformation hardness, etc. This excellent automotive resin composition is presented. Japanese Patent 5-98124 discloses 50-65 parts by weight of propylene ethylene block copolymer having a melt index of 40 g / 10 min or more, 5-15 parts by weight of ethylene propylene rubber, and an ethylene butene monomer having a melt index of 15-30 g / 10 min. 5-20 parts by weight, polyethylene with a melt index of 15-30 g / 10 min, 5-25 parts by weight, and 7-15 parts by weight of talc having an average particle diameter of 1.5 μm or less, and excellent paintability and formability. The present invention provides a resin composition for automobile exteriors having excellent impact properties and hardness, and having low molding shrinkage and linear expansion coefficient. Japanese Patent 5-59251 has 45-70 parts by weight of impact polypropylene, 10-20 parts by weight of ethylene propylene rubber with 70-90 parts by weight of ethylene, 5-15 parts by weight of ethylene a-olefin copolymer ethylene butene monomer The resin composition which has the outstanding moldability, high hardness, and high impact by 1-10 weight part and 8-15 weight part of talc whose average particle diameter is 1-3 micrometers is proposed. The above-mentioned patents commonly show that ethylene butene monomer is added to the existing thermoplastic resin composition to increase rigidity and form fine morphology, thereby exhibiting excellent low temperature impact strength, excellent paintability, and low linear expansion properties.

In the present invention, by adding a filler, which is one of the most important compositions in the above-mentioned resin composition, and containing the ultra-low density polyethylene of the trade name Exact produced by a metallocene catalyst in Exxon Chemical, It provides a thermoplastic olefin resin composition having excellent low-temperature impact strength, excellent flexural strength, flexural modulus, excellent heat resistance, excellent moldability compared to the existing olefin resin composition.

Metallocene catalyst refers to a complex of B metals in Group 4 of the Periodic Table of the Elements as shown in US Patent 5055438, in particular a combination of titanocene and zirconocene. These mean a transition metal as a catalyst system used for the polymerization of a polyolefin and an ethylene-a-olefin copolymer. These catalysts have a high activity when using a promoter called alumosein to polymerize the polyolefin. Therefore, the metallocene system is also called a catalyst catalyzed by allomosein. If aluminum alkyl is used as a cocatalyst, it becomes a general Ziegler-Natta catalyst system. In this case, the metallocene has a very low activity. Polyolefins polymerized by metallogen catalysts in which alumoxane is used as a promoter are characterized by having a very narrow molecular weight distribution and having a very large weight average molecular weight and thus providing high rigidity. On the other hand, the polyolefin produced by the existing Ziegler-Natta catalyst system has a high molecular weight but a wide molecular weight distribution. The propylene polymer contains about 6 to 12 parts by weight of homopolypropylene polymer characterized by isotactic and impact propylene polymer in the case of impact propylene. The rubber resin is selected from the group consisting of ethylene propylene monomer and ethylene propylene diene monomer rubber. Ethylene in the ethylene propylene monomer makes up about 40 to 75 parts by weight. Viscosity includes from about 10 to 70 based on 125 ℃ as the pattern viscosity. The ethylene propylene diene monomer rubber is configured in the form of only diene added to the ethylene propylene monomer rubber. The ultra low density polyethylene was polymerized by a metallocene catalyst and the molecular weight distribution was about 2.0 by polydispersity index. It contains about 20 to 30 parts by weight of butene comonomer, and the fluidity includes about 0.1 to 5.0 g / 10 min at 2.16 kg load at 190 ° C.

In the present invention, by using some or all of the rubbery material in the general composition without the filler as the ultra low density polyethylene (trade name Exact) produced by Exxon Chemical, excellent low-temperature impact properties, excellent mechanical strength, heat deformation and excellent molding processability are obtained. It is noteworthy that it could.

That is, the present invention (A) 60-80% by weight propylene polymer; A thermoplastic polyolefin resin composition comprising (B) a rubbery substance and (C) an ultra low density polyethylene in an amount of 20-40% by weight in sum ((B) + (C)).

Hereinafter, the present invention will be described in detail.

The thermoplastic polyolefin resin composition containing the ultra low density polyethylene according to the present invention comprises about 60 to 80 parts by weight, more preferably about 65 to 75 parts by weight of the (crystalline) propylene polymer. The propylene polymer consists of homopropylene and impact propylene and the impact propylene comprises about 6 to 12 parts by weight of an ethylene portion that is randomly or block polymerized to isotactic homo propylene. The apparent melting point of crystalline propylene is from 140 ° C to 180 ° C. More preferably, it is 160-170 degreeC. In addition, the crystalline moiety need not be fully crystalline (ie fully isotactic polymer). Examples of commercially useful propylene polymers include Hyprene H-540 (Hophopropylene polymer available from Honam Refinery), H-670, Hyprene M-530 (High Impact Propylene Copolymer available from Honam Refinery), M- 540, M-560, M-570, M-580 and SH-682 (high impact propylene copolymers available from Deoksan Procurement). The average molecular weight number of the propylene polymer component in the polyblend according to the invention is preferably at least about 10,000, more preferably at least about 100,000. The propylene polymer preferably has a fluid flow rate in the range of about 4 g / 10 min to about 60 g / 10 min, with particular choice of propylene polymer and fluid flow rate depending on the desired physical properties. The properties of propylene polymers in polyolefin blends are more than half the degree of crystallinity (usually around 50%), indicating that they can exhibit stiffness. Based on this, they have strong physical properties such as tensile strength, flexural strength, flexural modulus, and heat deflection temperature. It can be called an advantage. The effect of the molecular weight of the propylene polymer is to improve the impact strength aspect and the dispersion effect of the entire composition of the polyolefin blend when the molecular weight is large, on the contrary, when the molecular weight is low, the fluid flow rate of the composition is easy, but the impact strength or dispersion of the composition There seems to be some lack of sex.

In the present invention, the propylene polymer is preferably used 30g / 10min or more in order to improve the fluid flow rate of the entire composition, and the sacrificial impact strength can be compensated from rubbery resin or ultra low density polyethylene. The rubbery material in the composition of the present invention includes a rubbery material selected from rubber made of ethylene propylene monomer and rubber made of ethylene propylene diene monomer (EPPM, Ethylene-Propylene-Diene Monomer). Rubber composed of ethylene propylene monomer is classified into amorphous type and crystalline type according to the weight ratio of ethylene. Generally, when ethylene contains 65 parts by weight or more, the crystalline type becomes crystalline type. There is this. Ethylene propylene diene monomer rubbers are well known and ethylene is an irregular copolymer, at least one C ₃ -Ca-olefin (preferably propylene) and at least one unconjugated diene. Unconjugated dienes are linear aliphatic dienes having two or more carbon atoms having two terminal double bonds or one terminal double bond and one internal double bond. Or unconjugated dienes are cycline dienes in which one or two double bonds form part of a carbon ring. The structure of the EPDM rubber can be selected according to the branched structure, if desired, by selecting a non-conjugated characteristic diene. Particularly preferred non-conjugated dienes include 1,4-hexadiene, dichloropentadiene, vinyl norbornene, norbornadiene light 5-ethylidene-2-norbornene. Preferably, the EPDM rubber comprises about 40 to 90 mole percent ethylene and 0.1 to 7.5 mole percent unconjugated diene with a surplus agent that is propylene. Additional information relating to EPDM is described in this reference, ethylene-propylene elastomer, Polymer Science and Engineering Encyclopedia, Second Edition, Willy Science, Vol. 6, page 522 (1956). Commercially suitably useful ethylene propylene monomer rubbers (EPRs) include Vistalon 606 (product of Exxon Chemical, Vistalon 503K. Vistalon 878, MDV 91-9, Suprene 201 [porous rubber products], KEP-02P [Kumho skin products], and KEP-07P. Examples of commercially available EPDM rubbers include Vistalon® (trade name, Vistalon) 2200K (product of Exxon Chemical), Vistalon 3708, Vistalon 2504, Suprene 505A [porous rubber product], There is a Spren 567. The aforementioned viscosity of the rubbery material (Mooney viscosity) is in the range of 10 to 70 when measured at 125 ℃ and the distribution of molecular weight is present in a narrow range over a wide range. Ultra low density polyethylene in the composition of the present invention is an Exact (Exact) having a polydispersity index of about 2.0 polymerized by a metallocene catalyst in Exxon Chemical. Exact contains about 20 to 25 parts by weight of butene monomer in the ethylene main chain and the density is determined according to the degree of crystallization of ethylene. The density ranges from about 0.85 g / cm 3 to 0.95 g / cm 3 and the degree of fluidity ranges from 0.1 to 5.0 at 190 ° C., 2.16 kg load. The characteristics of the thermoplastic polyolefin resin composition may be determined according to the selected type, and in particular, the thermoplastic polyolefin resin composition may be selected according to properties to be emphasized in physical properties such as impact strength, mechanical strength, and moldability. Commercially suitably useful ultra low density polyethylenes include Exact 3033 (product of Exxon Chemical), Exact 3035, 4041, 4042, 4033.

The polyolefin resin containing the ultra low density polyethylene according to the present invention comprises the rubbery material and the ultra low density polyethylene such that the sum thereof is about 20 to 40% by weight, more preferably 25 to 35% by weight based on the total resin composition. The role of the rubbery material and the ultra low density polyethylene is most importantly the expression of impact strength, especially the low temperature impact strength. At the same time, the ultra low density polyethylene inherent in the rubbery material forms a dispersed phase, thereby playing a large role in the reinforcing of the rubbery phase. Therefore, when looking at the overall balance of properties, it is possible to express the advantage that the mechanical strength or heat resistance is excellent while the physical properties of the impact strength surface are equal or higher than those of the conventional ethylene propylene-based rubber alone. The polyolefin resin composition containing the ultra low density polyethylene according to the present invention has ethylene propylene-based rubber and ultra low density polyethylene in the form of a dispersed phase in the polypropylene continuous phase in the macroscopic aspect, but the micromorphological aspect and the crystallization part and the amorphous part According to simple mathematical calculations, it can be said that the amorphous portion of the polypropylene, the ethylene propylene rubber system, and the ultra low density polyethylene phase form a continuous phase in the overall composition, and the crystal region of the polypropylene forms a dispersed continuous amorphous phase. Therefore, the amorphous part of the continuous phase maintains excellent impact strength, while the rigid side compensation is sufficiently maintained by the ultra low density polyethylene contained in the crystal part and the amorphous part of the polypropylene.

The fusion of the propylene polymer, the rubbery material, the ultra low density polyethylene is carried out in a manner to form a blended polyblend. The resulting fused polyblends do not undergo phase separation in shaping and subsequent use. This is because they are mixed kindly using shear mixing at high temperatures. More friendly mixing is preferably achieved by a high performance shear extrusion mixer, such as a single screw or twin screw mixing extruder or a thermoplastic extruder having an L / D ratio of at least 20: 1 and a pressure ratio of about 3 or 4: 1.

The polyblend is fed directly into the forming machine or converted into granules for another process. The mixing temperature is selected according to the specific component to be fused. For example, it is generally desirable to select a melt melting temperature above the melting point or softening point of the component having the highest melting point or softening point, and thermal denaturation of any component below that temperature is not critical. In general, the fusion temperature is suitable between about 170 ℃ to 250 ℃. The order of fusion is not important. For example, all components of the polyblend are combined in one step or the rubbery material, ultra low density polyethylene, is first mixed with the propylene polymer. Or a rubbery material, ultra low density polyethylene, added during the production of the polyblend. Examples of such step variations are well known to those skilled in the art.

The polyolefin resin composition containing the ultra low density polyethylene according to the present invention may also be combined with standard thermoplastic additives such as fillers, reinforcing agents, colorants, lubricants, stabilizers, fire retardants, antioxidants, antiblocking agents and the like.

By the above description, those skilled in the art will be able to easily understand the essential features of the present invention, and changes and modifications suitable for various uses, conditions and embodiments can be made without departing from the spirit and scope of the present invention. It should be noted that.

Hereinafter, the polyolefin resin composition containing the ultra low density polyethylene according to the present invention will be described by examples which do not limit the scope of the present invention.

[Example 1-13]

As shown in Table 1, a mixture having a different composition was prepared to test physical properties.

Polypropylene polymer A-1 is Hi-prene H-670 homopropylene and has a flow rate of 35 g / min with a load of 2.16 kg at 230 ° C. The latent enthalpy (ΔH) indicating crystallinity is 85 J / g. Propylene Polymer A-2 is SH-682, commercially available from Deoksan Procurement, Japan, and is impact propylene, with a flow rate of about 30 to 35 g / 10 min and a potential enthalpy of 85 J / g at a load of 2.16 kg at 230 ° C. Propylene Polymer A-3 is Hyprene M-570 with a fluid flow rate of about 45-50 g / 10 min and a potential enthalpy of 76 J / g. The rubbery substance B-1 is Kumho Rubber, KEP-07P. The properties of B-1 are 73 parts by weight of ethylene, a pattern viscosity of 47 at 125 ° C., and an ethylene propylene monomer rubber. The rubbery material B-2 is KEP-02P as Kumho Rubber. The characteristic of B-2 is ethylene content of 74 parts by weight, pattern viscosity at 14C and ethylene propylene monomer rubber. Ultra Low Density Polyethylene C-1 is Exact 4033 in which 20 parts by weight of butene high monomer is branched onto the ethylene main chain molecule. C-1 exhibits a fluid flow characteristic of 0.8g / 10min at 190 ° C and 2.16kg load, density 0.88g / cm3, and forms natural pellets. Ultra Low Density Polyethylene C-2 is an exec 3033 with 20 parts by weight of butene branched ethylene backbone polymer with a flow rate of 1.2 g / 10 min and a density of 0.9 g / cm 3. Ultra Low Density Polyethylene C-3 is exec 4041 with 20 parts by weight of butene branched ethylene polymer with a fluid flow rate of 3.0 g / 10 min and a density of 0.878 g / cm 2.

Convergence Process

Polyblends are prepared by melting and fusing the components of Table-1 using a WP 25Φ twin-screw / two-hole extruder (L / D: 40) under the following conditions.

-RPM: 200

Vacuum degree: 65kg

Hopper inlet: cooling water cooling

Zone temperature (℃)

1-2: 180 degreeC

3 to 7: 200 ° C

Die: 210 ℃

Feedrate: 11kg / hr

Samples for evaluating the basic physical properties were obtained by injection molding under the following conditions using 75 tons of Venus injection molding machines.

-Nozzle temperature: 190 ~ 210 ℃

Injection pressure: (primary) 100kg / ㎠

(2nd) 60kg / ㎠

Back pressure: 10kg / ㎠

Injection time: 15 seconds

Molding machine temperature: 52 ℃

-rpm: 100

Melting Point Temperature: 210 ℃

Physical properties of the obtained specimens were measured after 48 hours at room temperature.

The polyolefin resin composition containing ultra low density polyethylene according to the present invention polymerizes some or all of ethylene propylphene monomer rubber or ethylene propylene diene monomer rubber from exon chemical to metallocene catalyst, and has very narrow molecular weight distribution and excellent stiffness. Polyethylene (trade name: Exact) is characterized by excellent mechanical strength, impact strength and fluid flow characteristics. Looking at Examples 1 to 5, the amount of the ethylene propylene monomer rubber system and the ultra low density polyethylene is fixed at 33 wt%, and the overall physical properties are excellent as the ratio of the ultra low density polyethylene is increased at the fixed amount. . In particular, the stiffness and the excellent low temperature impact strength can be said to have a great advantage to be applied to automotive exterior materials. Comparing Examples 6 to 9, when the ethylene propylene monomer rubber is replaced with the total amount of ultra low density polyethylene in the same composition, it can be seen that all of them exhibit excellent physical properties and there are some differences in physical properties depending on the type selected. In Examples 10 and 11, the propylene polymer was fixed and showed overall good performance even when some of the rubbery material was replaced with ultra low density polyethylene. Comparing Examples 12 and 13, the propylene polymer consists of homopropylene and impact propylene, and shows excellent overall properties when ultra low density polyethylene is used when used as ethylene propylene monomer rubber and ultra low density polyethylene.

In the above embodiment, when the ultra low density polyethylene is used, the overall physical properties were superior to that of the ethylene propylene rubber. This is due to the physical properties of the ultra low density polyethylene produced by the metallocene catalyst in Exxon Chemical, that is, it has excellent rigidity with a very narrow molecular weight distribution (polydispersity index: 2.0) and a wide selection range of the melt flow chart. do. In addition, the excellent properties of ultra-low density polyethylene are expressed in the form of macromolecular morphology and micro-arranged dispersed and continuous phases, and the amorphous part forms a continuous phase, and the crystalline part of the propylene polymer forms a powder phase. It means well.

Claims (6)

(A) 60 to 80 weight percent propylene polymer; (B) a polyolefin containing a rubbery material and (C) an ultra low density polyethylene obtained by mixing an ultra low density polyethylene having a density of 0.85 to 0.95 g / cm < 3 > Resin composition. The resin composition according to claim 1, wherein the propylene polymer is an isotactic homopropylene or an isotactic homopropylene in which ethylene is polymerized randomly or in blocks. The resin composition according to claim 1, wherein the rubbery material is ethylene propylene monomer rubber or ethylene propylene diene monomer rubber. The resin composition according to claim 1, wherein the ultra low density polyethylene is produced using a metallocene catalyst and a co-catalyst of alomosine. The resin composition according to claim 4, wherein the ultra low density polyethylene has a polydispersity index of about 2.0. The resin composition according to claim 1, wherein the sum of the rubbery material and the ultra low density polyethylene is 25 to 35% by weight.