JPH09249789A - Thermoplastic resin composition and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic resin composition excellent in flowability, mechanical strengths, heat resistance and impact resistance and a process for producing the same. SOLUTION: This composition comprises 100 pts.wt. propylene/ethylene block copolymer containing 70-90wt.% crystalline propylene homopolymer part and 10-30wt.% propylene/ethylene copolymer part having an ethylene content of 30-70wt.% and having a melt flow rate (at 230 deg.C under a load of 2.16kg) in the range of 0.1-20g/10min and 0.01-0.2 pt.wt. peroxide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin composition, and more particularly to a thermoplastic resin composition having excellent fluidity and impact resistance, which is suitable for automobile interior materials, containers, home electric appliances, etc., and a method for producing the same. .

[0002]

BACKGROUND OF THE INVENTION Polypropylene is widely used in various fields because it is lightweight and has excellent mechanical strength and the like. However, since it is inferior in impact resistance and heat resistance, various olefin-based elastomers such as ethylene-propylene rubber (EPR) and inorganic fillers such as talc are added to a propylene-ethylene block copolymer for the purpose of improvement. Has been proposed.

Recently, polypropylene resin compositions have come to be used for parts such as automobile door trims and pillars. However, polypropylene resin compositions used for such applications have higher impact resistance than usual. Is required. As a method of improving the impact resistance, a method of adding rubber such as EPR or EBR to a polypropylene resin composition is generally adopted.

However, in order to improve impact resistance, EP
Addition of a rubber component such as R and / or EBR not only makes it difficult to obtain a thermoplastic resin composition having excellent fluidity, mechanical strength, heat resistance and impact resistance,
High cost. If these problems are solved, it is expected that the range of use of polypropylene-based resin materials will be expanded, the number of parts that can be covered with one material will increase, and that the development will be advantageous in terms of cost.

Therefore, an object of the present invention is to provide a thermoplastic resin composition having excellent fluidity, mechanical strength, heat resistance and impact resistance, and a method for producing the same.

[0006]

As a result of earnest research in view of the above object, the present inventors have found that a propylene-ethylene block copolymer having a high proportion of propylene-ethylene copolymerization moieties and a low MFR has a predetermined amount. The inventors have found that a thermoplastic resin composition having excellent fluidity and impact resistance can be obtained by adding a peroxide, and have arrived at the present invention.

That is, the thermoplastic resin composition of the present invention comprises (A) (a) a crystalline propylene homopolymer portion of 70 to 90% by weight.
And (b) a propylene-ethylene copolymerization portion having an ethylene content of 30 to 70% by weight and 10 to 30% by weight, and a melt flow rate (MFR) of 0.1 to 10 g / 10 min. It is characterized by containing 0.01 to 0.2 parts by weight of (B) peroxide with respect to 100 parts by weight of the ethylene block copolymer.

Further, the method for producing a thermoplastic resin composition of the present invention comprises (1) (a) 70 to 90% by weight of a crystalline propylene homopolymer part, and (b) an ethylene content of 30 to 70% by weight. It contains propylene-ethylene copolymerized portion of 10 to 30% by weight, and has a melt flow rate (230 ° C, load 2.16 kg) of 0.1 to 10%.
100 parts by weight of propylene-ethylene block copolymer powder or pellets in the range of g / 10 minutes, peroxide
It is characterized in that 0.01 to 0.2 parts by weight are mixed and (2) melt-kneaded at a temperature of 180 to 300 ° C.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below. [1] Each component of thermoplastic resin composition (1) Propylene-ethylene block copolymer The propylene-ethylene block copolymer used in the present invention is preferably one synthesized by multistage polymerization. In multi-stage polymerization, propylene is first polymerized in the presence of a Ziegler catalyst, etc. to produce a crystalline propylene homopolymer part (which may contain a small amount of comonomer component), and in the next step, it is switched to ethylene + propylene. To produce a propylene-ethylene copolymerization moiety.

The propylene-ethylene block copolymer synthesized by multistage polymerization is composed essentially of a crystalline homopolypropylene part and a propylene-ethylene copolymer part, and each part is substantially independent. It may be present as a polymer (substantially in the form of a composition) or in a bound state. In addition, it may contain a small amount of a crystalline homopolyethylene part, but it is often not contained. Each of the above-mentioned parts is basically composed of propylene and / or ethylene, but may contain a small amount of other α-olefin, diene-based monomer or the like.

(A) Crystalline propylene homopolymer part The crystalline propylene homopolymer part is substantially a homopolymer of propylene (may contain a trace amount of ethylene to the extent that crystallinity is not impaired). In order to have high mechanical strength and rigidity, it is desirable that the residual amount after the extraction with boiling n-heptane for 6 hours is 90% by weight or more, preferably 95% by weight or more, which is a highly crystalline polypropylene. Especially the melt flow rate (MFR, measured at 230 ℃, 2,160 g) is 0.1
-15g / 10min is preferable. If the MFR is less than 0.1 g / 10 minutes, the thermoplastic resin composition will be poor in moldability.
If it exceeds the limit, the impact strength of the thermoplastic resin composition becomes insufficient. A more preferable MFR is 2.7 to 15 g / 10 minutes.

(B) Propylene-Ethylene Copolymerization Part The melt flow rate of the propylene-ethylene copolymerization part (MFR, measured at 230 ° C., load 2.16 kg) is 0.01 to 1.5.
It is preferably g / 10 minutes. MFR value is 0.01g / 10
When it is less than 1.5 minutes, moldability such as surface property is lowered due to generation of gel of the obtained thermoplastic resin composition, while when it exceeds 1.5 g / 10 minutes, mechanical strength is lowered. More preferable MFR is
It is 0.01 to 0.2 g / 10 minutes.

The intrinsic viscosity [η] (measured in decalin at 135 ° C.) of the propylene-ethylene copolymerized portion is preferably 2 to 5 dl / g, more preferably 3 to 5 dl / g. If the intrinsic viscosity [η] is less than 2 dl / g, the effect of improving impact resistance is not sufficient, while if it exceeds 5 dl / g, the moldability decreases due to an increase in gel component and the appearance of the molded product is poor. There is a risk that

The content of ethylene in the propylene-ethylene copolymerized portion is 30 to 70% by weight. Ethylene content
Below 30% by weight, the mechanical strength and elastic modulus are low, while 70
If it exceeds the weight%, the ductility and impact resistance will decrease. The preferred ethylene content is 50-65% by weight.

(C) Physical properties of propylene-ethylene block copolymer (i) Ethylene content The ethylene content of the whole propylene-ethylene block copolymer is 5 to 13% by weight. When the ethylene content is less than 5% by weight, the mechanical strength and elastic modulus are low, and
If it exceeds 13% by weight, the ductility and impact resistance will decrease. A more preferable ethylene content is 8.5 to 12% by weight.

(Ii) MFR The propylene-ethylene block copolymer has a melt flow rate (MFR, measured at 230 ° C. and a load of 2.16 kg) of 0.1.
-10 g / 10 min, preferably 1-10 g / 10 min. MF
If the value of R is less than 0.1 g / 10 minutes, the moldability of the resulting composition, particularly the injection moldability, will decrease, while if it exceeds 10 g / 10 minutes, the mechanical strength (particularly impact resistance) will decrease.

Ratio of component (d) Regarding the contents of and in the propylene-ethylene block copolymer, the sum of + is 100% by weight,
The crystalline homopolypropylene portion is 70 to 90% by weight, and the propylene-ethylene copolymer portion is 30 to 10% by weight.
When the crystalline propylene homopolymer portion is less than 70% by weight (when the propylene-ethylene copolymer portion exceeds 30% by weight), the resulting thermoplastic resin composition has low mechanical strength (elastic modulus etc.). On the other hand, when the crystalline propylene homopolymer portion exceeds 90% by weight (when the propylene-ethylene copolymer portion is less than 10% by weight), the impact resistance of the thermoplastic resin composition decreases. Preferably, (a) the crystalline propylene homopolymer portion is 75 to 85% by weight, and (b) the propylene-ethylene copolymer portion is 15 to 25% by weight.
Even if a crystalline homopolyethylene portion is further contained, the content thereof is 3% by weight or less with the total of + being 100% by weight.

(2) Peroxide The peroxide used in the present invention is usually used as a radical generator, for example, 1,1-bis (t-
Butylperoxy) -3,3,5-trimethylcyclohexane,
1,1-bis (t-butylperoxy) cyclohexane, 2,2-
Bis (t-butylperoxy) octane, n-butyl-4,4-
Bis (t-butylperoxy) valerate, di-t-butylperoxide, t-butylcumyl peroxide, dicumyl peroxide, α, α ′ bis (t-butylperoxyisopropyl) benzene, 2,5-dimethyl -2,5-di (t-
Butyl peroxy) hexane, 2,5-dimethyl-2,5-di
(t-butylperoxy) hexyne-3, cumylperoxy neodecanoate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane (perhexa25B), t-butylperoxyisopropyl carbonate, etc. Organic peroxides may be mentioned. These peroxides may be used alone or in combination.

The peroxide may be added as it is, but it is preferable to add it after diluting it with a hydrocarbon solvent or an inorganic or organic powder. Examples of the hydrocarbon solvent include liquid paraffin, toluene, benzene and the like, and examples of the inorganic or organic powder include calcium carbonate powder, polypropylene powder, polyethylene powder and the like.

[2] Blending Ratio The blending ratio of each of the above-mentioned components is 0.01 to 100 parts by weight of the propylene-ethylene block copolymer.
0.2 parts by weight, preferably 0.03 to 0.1 parts by weight. When the amount of the peroxide is less than 0.01 part by weight, the fluidity of the thermoplastic resin composition at the time of melt kneading decreases. On the other hand, if it exceeds 0.2 parts by weight, the impact resistance of the resulting thermoplastic resin composition will decrease.

[3] Other Components (1) Antioxidant Since the degradation of the propylene-ethylene block copolymer may occur excessively due to the presence of the peroxide, it is recommended to add the antioxidant. preferable. As an antioxidant,
Examples thereof include hindered phenol-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants and the like.

(A) Hindered Phenolic Antioxidant Examples of hindered phenolic antioxidants include:
6-di-t-butyl-p-cresol, 2,6-diphenyl-4-octadecyloxyphenol, stearyl (3,5-di-t-butyl-4-hydroxyphenyl) propionate, distearyl (3,5 -Di-t-butyl-4-hydroxybenzyl) phosphonate, 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl-6-t-
Butylphenol), bis [3,3-bis (4-hydroxy-3
-t-butylphenyl) butyric acid] glycol ester, 4,4'-butylidene bis (6-t-butyl-m-cresol), 2,2'-ethylidene bis (4,6-di-t-butylphenol), 2,2'-ethylidene bis (4-sec-butyl-6-t
-Butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, bis [2-t-butyl-4-methyl-6- (2-hydroxy-3- t-Butyl-5-methylbenzyl) phenyl] terephthalate, 1,3,5-tris
(2,6-dimethyl-3-hydroxy-4-t-butylbenzyl)
Isocyanurate, 1,3,5-tris (3,5-di-t-butyl-4
-Hydroxybenzyl) isocyanurate, 1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl) -2,4,6
-Trimethylbenzene, 1,3,5-tris [(3,5-di-t-butyl-4-hydroxyphenyl) propionyloxyethyl] isocyanurate, tetrakis [methylene-3- (3,5-
Di-t-butyl-4-hydroxyphenyl) propionate] methane, 2-t-butyl-4-methyl-6- (2'-acryloyloxy-3'-t-butyl-5'-methylbenzyl) phenol, 3 , 9-Bis (1 ', 1'-dimethyl-2'-hydroxyethyl)-
Examples include 2,4,8,10-tetraoxaspiro [5,5] undecane and bis [β- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate. Of these, 1,3,5-tris (2,6-dimethyl-3-hydroxy-4-t-
Examples thereof include butylbenzyl) isocyanurate, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane and the like.

(B) Phosphorus Antioxidant Examples of the phosphorus antioxidant include phosphorus stabilizers such as alkyl phosphite, alkylallyl phosphite, allyl phosphite, alkyl phosphonite and allyl phosphonite. Specifically, distearyl pentaerythritol diphosphite and tris (2,4-di-t
-Butylphenyl) phosphite, tetrakis (2,4-di)
-t-butylphenyl) -4,4'-biphenylene phosphonite, bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite, bis (2,6-di-t-butyl-4-
Examples thereof include methylphenyl) pentaerythritol-diphosphite and 1,1,3-tris (2-methyl-4-ditridecylphosphite-5-t-butylphenyl) butane.

(C) Sulfur-based antioxidant As the sulfur-based antioxidant, thiobis (N-β-naphthol), thiobis (N-phenyl-β-naphthylamine),
Examples thereof include 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, dodecyl mercaptan, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, dilaurylthiodipropionate and distearylthiodipropionate.

(2) Other additives In the thermoplastic resin composition of the present invention, in addition to the components described above, other additives such as a nucleating agent, a light stabilizer, and Additives such as a heat stabilizer, a release agent, an antistatic agent (including a surfactant), a plasticizer, a flame retardant, a foaming agent and a pigment can be added.

[4] Method for Producing Thermoplastic Resin Composition The method for producing the thermoplastic resin composition of the present invention is not particularly limited, but peroxides and other substances may be used during granulation of the propylene-ethylene block copolymer powder. It is preferable to add the additive of. The powder can be compounded by an ordinary mixing device such as a Henschel mixer, a super mixer or a ribbon blender. The obtained mixture was granulated, then uniaxial extruder,
180 ~ with twin-screw extruder, Banbury mixer, kneader, etc.
It is pelletized by melt-kneading in the temperature range of 300 ° C. At this time, in order to prevent deterioration due to peroxide,
It is preferable to incorporate an antioxidant. Incidentally, it is of course possible to blend a peroxide and other additives after the granulation.

Further, pigments and other additives are usually added at the time of melt-kneading, but a masterbatch containing a high concentration of pigments and other additives may be prepared in advance and kneaded at the time of injection molding. Good. [5] Molded Article of Thermoplastic Resin Composition A molded article obtained from the thermoplastic resin composition having the above composition has a viscosity of 10 to 100 g / 10 minutes, preferably 20 to 40 g / min. It has a melt flow rate of 10 minutes.

[0028]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited thereto.

Examples 1 to 10 and Comparative Example 1 1. Raw material (A) Propylene-ethylene block copolymer (BPP) The propylene-ethylene block copolymer having the properties shown in Table 1 was used.

(B) Peroxide (POX) "Perhexa 25B" (manufactured by NOF CORPORATION) was diluted with liquid paraffin ("Cristol" (manufactured by Exxon)) to 40% by weight and used.

2. Kneading and molding method Propylene-ethylene block copolymer (BBP) having the properties shown in Table 1 and perhexa25B (POX) were blended at the blending ratio shown in Table 1, dry blended with a super mixer, and then twin-screw extruder was used. (“PCM-45” manufactured by Ikegai Co., Ltd., L / D
= 32), 200 ℃, screw rotation speed 200 rpm
And kneaded to obtain pellets of the composition. Next, using an injection molding machine, injection molding was performed at a resin temperature of 210 ° C., an injection pressure of 650 kgf / cm ² and a mold temperature of 40 ° C. to obtain a test piece.

3. Physical property measurement For each test piece, each physical property value was measured by the following methods. The results are shown in Table 2 below. MFR (g / 10min): 230 ° C, load according to JIS K7210
It was measured at 2.16 kg. Tensile strength (kgf / cm ² ): Measured at 23 ° C. according to ASTM D638. Tensile elongation at break (%): Measured at 23 ° C according to ASTM D638. Flexural modulus (kgf / cm ² ): Measured at 23 ° C. according to ASTM D790. Bending strength (kgf / cm ² ): Measured at 23 ° C. according to ASTM D790. Izod impact strength (kgf · cm / cm ² ): ASTM D256
Was measured at 23 ° C and -30 ° C using a 3.2 mm thick notched test piece. Heat distortion temperature (° C): Measured according to ASTM D648 at a pressure of 18.5 kgf / cm ² and 4.6 kgf / cm ² . Rockwell hardness (scale R): measured by ASTM D785. Embrittlement temperature (° C.): Measured according to ASTM D746.

Comparative Example 2 Instead of peroxide (Perhexa 25B), ethylene-propylene rubber (EPR, trade name "EP02P", manufactured by Nippon Synthetic Rubber Co., Ltd., MFR: 3.2 g / 10 minutes, ethylene content:
A test piece was prepared under the same conditions as those of the examples except that 83% by weight) was blended in the ratio shown in Table 1 below, and the physical properties were measured. Table 2 shows the results.

Table 1 Example No. BPP properties and blending ratio 1 2 3 4 5 BPP properties Overall MFR (g / 10 min) 3 1 10 3 3 Homopolypropylene partial ratio ⁽¹⁾ 82.5 82.5 82.5 82.5 82.5 Copolymerized partial ratio ⁽¹⁾ 17.5 17.5 17.5 17.5 17.5 Ethylene content ⁽²⁾ 65 65 50 35 70 [η] (dl / g) ⁽³⁾ 3 5 2 3 3 Mixing ratio ⁽⁴⁾ BPP 100 100 100 100 100 POX 0.075 0.1 0.04 0.075 0.075 Note (1) Unit: % By weight (100% by weight of BPP). (2) Unit:% by weight (100% by weight of copolymerized portion). (3) Measured in decalin at 135 ° C. (4) Unit: parts by weight (100 parts by weight of BPP).

Table 1 (continued) Example No. BPP properties and blending ratio 6 7 8 9 10 BPP properties Overall MFR (g / 10 min) 3 3 3 3 1 Homopolypropylene partial ratio ⁽¹⁾ 90 70 82.5 82.5 82.5 Copolymerized partial ratio ⁽¹⁾ 10 30 17.5 17.5 17.5 Ethylene content ⁽²⁾ 65 65 65 65 65 [η] (dl / g) ⁽³⁾ 3 3 3 3 5 Mixing ratio ⁽⁴⁾ BPP 100 100 100 100 100 POX 0.075 0.075 0.03 0.1 0.2 Note (1) ~ ( 4) Same as above.

Table 1 (continued) Comparative Example No. BPP properties and blending ratio 1 2 BPP properties Overall MFR (g / 10 min) 40 32 Homopolypropylene partial ratio ⁽¹⁾ 88 75 Copolymerized partial ratio ⁽¹⁾ 12 25 Ethylene content ⁽²⁾ 50 40 [η] ( dl / g) ⁽³⁾ 33 Mixing ratio ⁽⁴⁾ BPP 85 100 POX --- EPR ⁽⁵⁾ 150 Note (1) to (4) Same as above. (5) Unit: parts by weight (BPP + EPR is 100 parts by weight).

Table 2 Example No. Physical properties 1 2 3 4 5 MFR (g / 10 min) 30 32 30 32 32 Tensile strength (kgf / cm ² ) 220 210 230 210 225 Tensile fracture elongation (%) 600 400 500 600 400 Flexural modulus (kgf / cm ²⁾ 10,400 10,000 10,500 9,900 10,500 flexural strength ^{(kgf / cm 2) 262 255} 275 255 263 Iz impact strength ^{23 ℃ (1) 15 12 12} 13 15 -30 ℃ (2) 4 3.5 3.8 3.8 4 T D at 18.5kgf / cm ^{2 (3)} 60 58 63 58 60 T _D at 4.6kgf / cm ^{2 (4)} 102 99 110 100 102 Rockwell hardness (R) 81 78 83 80 81 Embrittlement temperature (℃) -24.5 -20 -24- 24.5 -24.5 Note (1) Izod impact strength (unit: kgf · cm / cm ² , measured at 23 ° C). (2) Izod impact strength (unit: kgf · cm / cm ² , measured at -30 ° C). (3) Heat distortion temperature (unit: ° C., measured at a load 18.5kgf / cm ^2). (4) Heat distortion temperature (unit: ° C, load 4.6 kgf / cm ² ).

Table 2 (continued) Example No. Physical properties 6 7 8 9 10 MFR (g / 10 min) 35 30 10 45 50 Tensile strength (kgf / cm ² ) 270 190 230 218 205 Tensile elongation at break (%) 250 600 600 300 150 Flexural modulus (kgf / cm ²⁾ 14,000 7,500 11,100 9,900 9,600 flexural strength ^{(kgf / cm 2) 350 180} 265 258 245 Iz impact strength ^{23 ℃ (1) 7 42 18} 11 10 -30 ℃ (2) 3.4 6.5 4.5 3.8 3.6 T D at 18.5kgf / ^{cm 2 (3) 67 56 62} 58 56 T D at 4.6kgf / cm 2 (4) 120 90 105 102 100 Rockwell hardness (R) 90 65 81 80 78 brittle temperature (℃) -5.5 -37.5 -28.5 - 20.5 -18 Note (1) to (4) Same as above.

[0039]

As is clear from Table 2, the thermoplastic resin compositions of Examples 1-10 are excellent in fluidity, mechanical strength, heat resistance and impact resistance. On the other hand, the thermoplastic resin compositions of Comparative Examples 1 and 2 are inferior in at least one of fluidity, mechanical strength, heat resistance and impact resistance.

[0041]

EFFECT OF THE INVENTION The thermoplastic resin composition of the present invention obtained by adding a predetermined amount of peroxide to a propylene-ethylene block copolymer having a high proportion of propylene-ethylene copolymerization moieties and a low MFR. Has excellent fluidity, mechanical strength, heat resistance and impact resistance. Although such a thermoplastic resin composition can be applied to various uses, it is particularly suitable for industrial parts such as automobile interior materials, containers and home electric appliances.

Claims (5)

[Claims] 1. (A) (a) 70 to 90% by weight of a crystalline propylene homopolymer portion, and (b) 10 to 30% by weight of a propylene-ethylene copolymer portion having an ethylene content of 30 to 70% by weight.
Containing and, melt flow rate (230 ℃, load 2.16k
(B) 0.01 to 0.2 part by weight of a peroxide, per 100 parts by weight of a propylene-ethylene block copolymer having a range of 0.1 to 20 g / 10 min. 2. The thermoplastic resin composition according to claim 1, wherein the content of the peroxide is 0.03 to 0.1 part by weight. 3. The thermoplastic resin composition according to claim 1 or 2, further comprising 0.03 to 0.2 part by weight of an antioxidant per 100 parts by weight of the propylene-ethylene block copolymer. Thermoplastic resin composition. 4. (1) (A) (a) 70 to 90% by weight of a crystalline propylene homopolymer part, and (b) an ethylene content of 30 to 70.
It contains 10 to 30% by weight of a propylene-ethylene copolymerization portion, which is a weight%, and has a melt flow rate (230 ° C., a load of 2.
16 kg) is 0.1-10 g / 10 min in the range of propylene-
Powder or pellet 100 of ethylene block copolymer
A method for producing a thermoplastic resin composition, characterized in that 0.01 to 0.2 parts by weight of (B) peroxide is added to parts by weight, and (2) melt kneading is performed at a temperature of 180 to 300 ° C. 5. The method for producing a thermoplastic resin composition according to claim 4, wherein the propylene-ethylene block copolymer powder further comprises 0.03 to 0.2 parts by weight per 100 parts by weight of the propylene-ethylene block copolymer. A method comprising adding the antioxidant of 1.