JPH08208942A - Propylene resin composition and molding made therefrom - Google Patents

Abstract

PURPOSE: To obtain a propylene resin compsn. excellent in low-temp. flowability, softness, and stampability. CONSTITUTION: This compsn. comprises 100 pts.wt. propylene-α-olefin block copolymer (A) having a ratio (η1 /η2 ) of the melt viscosity (η1 ) measured by the slit die method under a shear rate of 10<1> sec<-1> to that (η2 ) under a shear rate of 10<2> sec<-1> of 3.5-8, 5-150 pts.wt. rubbery polymer (B), and 0.005-2 pts.wt. org. peroxide (C) is dynamically heat treated to give a propylene resin compsn. which has a melt flow rate (measured according to JIS K 7210 at 230 deg.C under 2.16kg-load) of 50-300g/10min, a main endothermic peak temp. (Tmp) of the melting temp. measured with a differential scanning calorimeter of 120-150 deg.C, a main exothermic peak temp. (Tcp) of the crystallization temp. of 85-105 deg.C, and a half-value width of Tcp of 5 deg.C or higher.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a propylene-based resin composition having excellent low-temperature fluidity, flexibility and stampable moldability, which is preferably used in fields such as automobile parts and electric / electronic parts.

[0002]

2. Description of the Related Art The hot stampable molding method is a method of directly molding a semi-molten sheet extruded from a die of a sheet molding machine to obtain a molded product. Unlike the conventional molding method, the molding method is advantageous in terms of cost because it is not necessary to reheat the once solidified sheet raw fabric, and is a molding method that has been drawing attention in recent years. As a resin suitable for this molding method, for example, a highly fluid polypropylene resin (Japanese Patent Laid-Open No. 8021/1990)
No. 8, etc.) or olefinic thermoplastic elastomer (JP-A-4-73112, JP-A-4-73142)
Have been proposed.

[0003]

However, in any of the resins of the above methods, the crystallization rate is high, so that the solidification progresses immediately after being extruded from the die, which is inferior to the stampable molding method, or the obtained molded article is flexible. There was a problem of poor sex. The present invention has been made in view of such circumstances, and an object of the present invention is to provide a propylene resin composition having a low crystallization rate, excellent low-temperature fluidity, flexibility and stampable moldability.

[0004]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the above object can be achieved by a propylene-α-olefin block copolymer having specific physical properties. Based on this, the present invention has been completed. That, (A) the ratio of the melt viscosity eta ₂ in the melt viscosity eta ₁ and a shear rate of 10 ² sec ^-1 at a shear rate of 10 ¹ sec ^-1 as measured by a slit die method (eta ₁ /
100 parts by weight of a propylene-α-olefin block copolymer having η ₂ ) of 3.5 to 8, 5 to 150 parts by weight of a rubber-like polymer (B) and 0.0) of an organic peroxide (C).
A melt flow rate (measured according to JIS K7210 at a temperature of 230 ° C. and a load of 2.16 kg) obtained by dynamically heat-treating a blended product consisting of 05 to 2 parts by weight is 50 to 300 g / 10 min. The prepared endothermic peak temperature Tmp of the melting temperature by differential scanning calorimeter was 120.
~ 150 ° C, the main exothermic peak temperature Tc of the crystallization temperature
p is 85 to 105 ° C., and the full width at half maximum of Tcp is 5 ° C.
The above-mentioned propylene resin composition is provided. Hereinafter, the present invention will be specifically described.

(A) Propylene-α-olefin block copolymer used in the present invention (hereinafter referred to as "BPP")
Is a polypropylene block and propylene and other α-
It is a block copolymer composed of a copolymer block with an olefin. Preferred examples of the BPP of the present invention include a polypropylene block, propylene and 1 to 12 carbon atoms.
Examples of the block copolymer include a copolymer block with (but excluding 3) α-olefin. The α-
Examples of the olefin include ethylene, 1-butene, 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 4-dimethyl-1-pentene, vinylcyclopentane and vinylcyclohexane. Can be mentioned. These α-olefins may be used alone or in combination of two or more. The proportion of the copolymer rubber block in the total copolymer is generally 30 to 70% by weight, preferably 35 to 68% by weight, and more preferably 40% by weight.
~ 65 wt% is preferred.

The BPP of the present invention has a melt viscosity η ₁ at a shear rate of 10 ¹ sec ^-1 measured by the slit die method.
And the melt viscosity η ₂ at a shear rate of 10 ² sec ^-1 (η ₁ / η ₂ ) must be 3.5 to 8.
The melt viscosity ratio (η ₁ / η ₂ ) is preferably 4.0 to 7.5, and particularly preferably 4.5 to 7.0. If the melt viscosity ratio is less than 3.5, the drawdown is large and the sheet formability is poor. On the other hand, when it exceeds 8, the stampable moldability is deteriorated, which is not preferable.

The slit die method is a method of measuring melt viscosity at a temperature of 170 ° C. using a slit die having a width of 20 mm, a height of 1.5 mm and a length of 60 mm. See CDHan; Rheology in
Polymer Processing, Academic, New York (1976) and
JLWhite; Principles of Polymer Engineering Rheolo
gy, John Wiley, New York (1990) have detailed description.
Specifically, the viscosity can be measured using a commercially available viscometer having a slit die (Toyo Seiki Seisakusho Labo Plastomill D20-20 type).

Further, as the BPP having excellent stampable sheet moldability, those having the following physical properties (a) and (b) are preferable. That is, (a) the para-xylene insoluble content at a temperature of 25 ° C is in the range of 25 to 65% by weight, and (b) the para-xylene soluble content at a temperature of 25 ° C is (i) an average propylene content based on a 2-site model. (FP) 20 to 80 mol%, (ii) propylene content (P _P) of the copolymer to produce a propylene active sites polymerized preferentially in 2 site model (P _H) 65 to
90 mol% and (iii) the proportion of P _H occupied in the copolymer (P _f1) is in the range of 0.40 to 0.90. (A) Paraxylene insoluble matter means BPP at a temperature of 130 ° C.
It is an insoluble component when it is dissolved in para-xylene at about 1% by weight and then cooled to 25 ° C., and the BPP of the present invention is 25 to 6
5% by weight is preferable, and 30 to 60% by weight is particularly preferable. Further, the (b) para-xylene soluble component is a component dissolved by the above-mentioned operation, and the properties obtained by the two-site model are preferably within the above range.

Here, 2 of propylene-α-olefin
The site model will be described by taking a propylene-ethylene copolymer as an example. An example of a nuclear magnetic resonance ( ¹³ C-NMR) spectrum of isotope carbon of a propylene-ethylene copolymer is shown in FIG. The spectra are shown in (1) to (10) due to the difference in the chain distribution (the arrangement of ethylene and propylene).
0 peaks appear. The name of this chain is Carman, C,
J, et al; Macromolecules, Vol. 10, p536-544 (1977), and the name is shown in Fig. 2. Such a chain is
Assuming the reaction mechanism of copolymerization, it can be expressed as a reaction probability (P), and when the overall peak intensity is 1.
The relative intensities of the peaks (1) to (10) can be expressed as a probability equation based on Bernoulli statistics with P as a parameter. For example, in the case of (1) Sαα, assuming that the propylene unit is the symbol p and the ethylene unit is the symbol e, the possible chains are [pppp], [pppe], and [eppe].
And each of them is represented by a reaction probability (P),
Add up. The remaining peaks (2) to (10) can be obtained by formulating equations in a similar manner and optimizing P so that the peak intensity actually measured and those 10 equations are closest to each other. .

The two-site model is a model that assumes this reaction mechanism. HNCHENG; Jounal of Applied Polymer
Sience, Vol.35 p1639-1650 (1988). That is, in the model of copolymerizing propylene and ethylene using a catalyst, propylene content of the copolymer generated at the active sites of polymerization preferentially propylene _{(P H)} (P P)
Assuming two of the propylene content (P ' _P ) of the copolymer formed at the active site where ethylene and ethylene are preferentially polymerized,
_{When the} ratio of _H in the copolymer (P _f1 ) is used as a parameter, the probability equation shown in Table 1 below is obtained.

[0011]

[Table 1]

[0012] Therefore, the relative intensity of the ¹³ C-NMR spectrum as described above, P _P so that the probability equations shown in Table 1 are the same, by optimizing three parameters P _'P and P _f1 Desired.

The (i) average propylene content (FP) of the para-xylene solubles in the BPP of the present invention is determined by the following equation using the above three parameters. _{FP = P P × P f1 +} P 'P × (1-P f1) ( mol%) FP obtained by the above formula is preferably from 20 to 80 mol%, more preferably from 30 to 70 mol%. Also,
Among the above parameters, (ii) P _P is 65 to 90 mol%
Is preferable, and 70 to 85 mol% is particularly preferable.

Further, (iii) P _f1 is 0.40 to 0.90.
Is preferable, and 0.48 to 0.82 is particularly preferable. The polymerization of BPP of the present invention is carried out by using an inert hydrocarbon such as hexane, heptane, kerosene, or a liquefied α such as propylene
-The temperature is from room temperature to 13 by a slurry method performed in the presence of an olefin solvent, a gas phase polymerization method without a solvent, or the like.
0 ° C, preferably 50 to 90 ° C, pressure 2 to 50 kg / c
It is performed under the condition of m ² . As the reactor in the polymerization step, those usually used in the technical field can be appropriately used, and examples thereof include a stirred tank reactor, a fluidized bed reactor, a circulation reactor, and a continuous type, a semi-batch type, or a batch type. Either method may be used.

Specifically, it can be obtained by using a known multistage polymerization method. That is, after polymerizing propylene and / or propylene-α-olefin copolymer in the first stage reaction,
This is a method of copolymerizing propylene and α-olefin in the second-stage reaction, and is disclosed in, for example, JP-A-3-97747 and JP-A-3-97747.
3-205439, JP-A-4-153203, JP-A-4-2614
23 and Japanese Patent Laid-Open No. 5-93024. JIS K7210 of BPP obtained by the above method
The melt flow rate (hereinafter referred to as “MFR”) measured at a temperature of 230 ° C. and a load of 2.16 kg in accordance with
It is 0 g / 10 minutes or less.

The rubbery polymer (B) used in the present invention is not particularly limited and includes, for example, natural rubber (NR); butadiene rubber (BR), isoprene rubber (IR), chloroprene rubber (CR), styrene. -Butadiene rubber (S
BR), isobutene-isoprene rubber (IIR), acrylonitrile-butadiene rubber (NBR), ethylene-
Propylene copolymer rubber (EPR), ethylene-propylene-non-conjugated diene copolymer rubber (EPDM), propylene-butene rubber, butyl rubber, silicone rubber, fluorosilicone rubber, nitrile rubber, epichlorohydrin rubber and other synthetic rubbers; styrene / isoprene-styrene Block copolymer (SIS), styrene-ethylene / isoprene-styrene block copolymer (SEPS), styrene /
Examples thereof include various thermoplastic elastomers such as styrene-based elastomers such as butadiene-styrene block copolymer (SBS) and styrene-ethylene / butylene-styrene block copolymer (SEBS), olefin elastomers and ester elastomers. Furthermore, low molecular weight rubbers such as polybutene, artic polypropylene (APP); liquid BR, liquid IR, liquid CR
Liquid rubbers such as; chlorinated polyethylene such as chlorinated polyethylene and chlorinated ethylene-propylene copolymer rubber; and chlorosulfonated polyethylene. Among these, EPR, EPDM, hydrogenated SBR, S
EPS or the like is preferably used. Many grades of the above various rubbery polymers are sold as commercial products, and in the present invention, these commercial products can be appropriately used. Further, two or more kinds may be mixed and used.
The blending ratio of the component (B) with respect to 100 parts by weight of BPP of the present invention is 5 to 150 parts by weight, preferably 10 to 140 parts by weight, and particularly preferably 15 to 130 parts by weight.
If the blending ratio of the component (B) is less than 5 parts by weight, the flexibility is poor. On the other hand, if it exceeds 150 parts by weight, mechanical strength is lowered, which is not preferable.

The (C) organic peroxide used in the present invention is not particularly limited, but the decomposition rate of BPP at the melting temperature is more than 1 second as the half-life and the decomposition at 300 ° C. A speed of 10 minutes or less is preferable. Specifically, t-butyl hydroperoxide, dicumyl peroxide, 1,3-bis (t-butylperoxyisopropyl) benzene, benzoyl peroxide, methyl isobutyl ketone peroxide,
Examples thereof include t-butyl perbenzoate, diisopropyl peroxydicarbonate, vinyl tris (t-butyl peroxy) silane and the like. The mixing ratio of these organic peroxides is 0.005-2 with respect to 100 parts by weight of BPP.
0.01 to 1.8 parts by weight is preferable, and 0.02 to 1.5 parts by weight is particularly preferable. If the blending ratio is less than 0.005 part by weight, the fluidity will be insufficient. On the other hand, 2
If the amount is more than parts by weight, problems such as coloring of the molded article and surface stickiness occur.

The MFR of the composition of the present invention can be prepared by dynamically heat treating a blend of the above components. As the heat treatment method, a conventionally known melt kneading method can be adopted. For example, a method of kneading using a mixer such as an open roll, a Banbury mixer, a kneader, or an extruder can be used. The treatment temperature is generally 170 to 280 ° C, preferably 190 to 260 ° C. As the blending method, in addition to the method of heat-treating the blend of the components (A), (B) and (C) as described above, the blend of the components (A) and (C) is heat-treated in advance. After that, a method of blending the component (B) may be used. The latter method is a preferable method when the component (B) may undergo a crosslinking reaction by heat treatment. The MFR of the resin composition of the present invention thus prepared is 50-
Must be in the range of 300g / 10 minutes, 60
~ 270 g / 10 min is preferred, especially 70-250
g / 10 minutes is preferred. When the MFR is less than 50 g / 10 minutes, the stampable moldability is deteriorated. On the other hand, 300 g /
If it exceeds 10 minutes, the mechanical strength becomes insufficient, which is not preferable.

The composition of the present invention has a main endothermic peak temperature Tmp measured by using a differential scanning calorimeter (DSC).
Is 120 to 150 ° C, the main exothermic peak temperature Tcp of the crystallization temperature is 85 to 105 ° C, and the full width at half maximum of Tcp is 5 ° C or more. Tmp is 125
-148 degreeC is preferable and 130-145 degreeC is especially suitable. If Tmp is less than 120 ° C, mechanical strength and heat resistance are poor. On the other hand, when it exceeds 150 ° C, the stampable moldability is poor. Tcp is preferably 87 to 100 ° C, and particularly preferably 88 to 98 ° C. If Tcp is less than 85 ° C, the molding cycle becomes long. On the other hand, if it exceeds 105 ° C, the flexibility is poor. The full width at half maximum of Tcp is preferably 6 ° C or more. When the full width at half maximum is less than 5 ° C., the stampable moldability is poor, which is not preferable.

The measuring method of Tmp and Tcp using a differential scanning calorimeter (DSC) is as follows: the sample is heated to 250 ° C. and melted, and then cooled to −30 ° C. at a cooling rate of 20 ° C./min. The main exothermic peak temperature Tcp is obtained from the obtained exothermic peak curve, and the peak width at 50% height of the peak is the half width. Next, after holding at -30 ° C for 5 minutes, the main endothermic peak temperature Tmp is obtained from the endothermic peak curve obtained when the temperature is raised to 250 ° C at a temperature rising rate of 20 ° C / minute.

The composition of the present invention having the above physical properties can be used not only as a single substance but also as a laminate with other materials. Further, the composition of the present invention contains additives commonly used by those skilled in the art, such as antioxidants, weathering stabilizers,
An antistatic agent, a lubricant, an antiblocking agent, an antifogging agent, a pigment, a filler and the like may be appropriately added within a range that does not impair the object of the present invention.

[0022]

The present invention will be described in more detail with reference to the following examples. In addition, the measuring method of each physical property is shown below. (Analysis of para-xylene solubles by a two-site model ( ^13C -NMR spectra of para-xylene solubles were measured with the following equipment and measurement conditions, and the respective signals were A. Zambelli et al; Macromolecules, 13 ,
It was assigned according to the method described in p267 (1980). Measuring device: JNM-GSX40 manufactured by JEOL Ltd.
0 Measurement mode: Proton decoupling method Pulse width: 8.0 μs Pulse repetition time: 5.0 s Number of integrations: 20000 times Solvent: 1,2,4-Trichlorobenzene /
Mixed solvent of deuterated benzene (75/25% by volume) Internal circulation: Hexamethyldisiloxane Sample concentration: 300 mg / 3.0 ml Solvent measurement temperature: 120 ° C. Next, a two-site model is analyzed to determine FP, _PP and P. _{Find f1} .

(MFR) In accordance with JIS K7210,
The measurement was performed under the conditions of a temperature of 230 ° C. and a load of 2.16 kg. (Tmp, Tcp, Tcp full width at half maximum) Device: DSC measuring device manufactured by PERKIN-ELMER Sample: 3-5 mg Measuring method: by the above method (fluidity) Hot stamping molded article was visually observed and evaluated in the following three stages. . 〇 ・ ・ ・ No short shot or thick portion at all △ ・ ・ ・ There is some thick portion × ・ ・ ・ Many thick portions and short shot (Sheet appearance) Surface of hot stamping molded product Was visually observed and evaluated according to the following four grades. ◎ ・ ・ ・ ・ Very smooth 〇 ・ ・ ・ ・ Sufficiently smooth △ ・ ・ ・ ・ No smoothness and wrinkle or pockmark pattern × ・ ・ ・ ・ No smoothness, wrinkle or pockmark pattern (Surface hardness) Measured with Shore A according to ASTM D2240.

Further, as a propylene-α-olefin block copolymer, polypropylene block and ethylene-
A block copolymer composed of a propylene copolymer block was used. The type (BPP1～7) and properties shown (melt viscosity ratio, the proportion of the copolymer block, paraxylene-insoluble component, and para-xylene solubles of FP, _{P P, P f1)} in Table 2.

[0025]

[Table 2]

SEPS (Kuraray Co., Septon 2043), which is a styrene elastomer as a rubber-like polymer
(Hereinafter referred to as "ST"), APP (manufactured by Chiba Fine Chemical Co., Sun Attack L) (hereinafter referred to as "AP") and ethylene-propylene rubber (manufactured by Japan Synthetic Rubber Co., EP).
07) (hereinafter referred to as “EP”) was used. 2,5-Dimethyl-2,5-di (t-butylperoxy) hexane was used as the organic peroxide.

Examples 1 to 8 and Comparative Examples 1 and 2 Pentaerythrityl-tetrakis [3-] as components and additives whose types and amounts are shown in Table 3.
(3,5-di-t-butyl-4-hydroxyphenyl)
Propionate] 0.1 parts by weight, 0.1 parts by weight of tris (2,4-di-t-butylphenyl) phosphite and 0.05 parts by weight of calcium stearate are mixed, and a super mixer (SMV20 type) manufactured by Kawata Manufacturing Co., Ltd.
After mixing using a twin screw extruder (KTX manufactured by Kobe Steel, Ltd.
-37 type) was used and pelletized under the conditions of a cylinder temperature of 210 ° C. MFR, T for each obtained pellet
mp and Tcp were measured.

Further, a test piece having a thickness of 2 mm was prepared from each pellet using an injection molding machine (IS-170FII manufactured by Toshiba Machine Co., Ltd.), and the surface hardness was measured. Furthermore, each of the above pellets is processed by a hot stamping molding machine (FSM4 manufactured by Takahashi Industry Co., Ltd.
50), die temperature 220 ℃, mold clamping pressure 200
Tonnage and mold temperature 70 ° C. Extruded and stamped onto polypropylene resin substrate (thickness 3.5 mm) and container (length 600 mm, width 800 mm, height 5 mm)
A thickness of 3 mm) was obtained. The fluidity and surface appearance of each container were visually evaluated.

Example 9 BPP, organic peroxide and the above additives were preliminarily pelletized in the same manner and in the amounts shown in Table 3 in the same manner as above. Then, a rubbery polymer was added and blended using a tumbler, and then pelletized again by the above method. MFR, Tmp and Tcp for the resulting pellets
And the molded articles were evaluated for fluidity and surface appearance. The above results are shown in Table 3.

[0030]

[Table 3]

[0031]

Since the resin composition of the present invention is excellent in low temperature fluidity, flexibility and stampable moldability, it is useful in the fields of automobile parts, electric / electronic parts and the like.

[Brief description of drawings]

FIG. 1 is an example of a nuclear magnetic resonance spectrum of isotope carbon of an ethylene-propylene copolymer.

FIG. 2 is a diagram showing names of carbons derived from a chain distribution in polyolefin.

Claims (5)

[Claims] 1. A (A) a shear rate of 10 ¹ sec as measured by a slit die method ^- the ratio of the melt viscosity eta ₂ at a melt viscosity at ¹ eta ₁ and a shear rate of _{^{10 2 sec -1 (η 1 /}} η
₂ ) 100 to 100 parts by weight of a propylene-α-olefin block copolymer having 3.5-8, (B) a rubbery polymer 5
To 150 parts by weight and (C) organic peroxide 0.00
Melt flow rate obtained by dynamically heat-treating a blend consisting of 5 to 2 parts by weight (measured in accordance with JIS K7210 at a temperature of 230 ° C. and a load of 2.16 kg)
Was prepared at 50 to 300 g / 10 minutes, and the main endothermic peak temperature Tmp of the melting temperature by the differential scanning calorimeter was 120 to 1
A propylene resin composition having a temperature of 50 ° C., a main exothermic peak temperature Tcp of the crystallization temperature of 85 to 105 ° C., and a full width at half maximum of Tcp of 5 ° C. or more. 2. A treated product obtained by dynamically heat treating a blend comprising 100 parts by weight of the component (A) and 0.005 to 2 parts by weight of the component (C), and A melt flow rate of 150 parts by weight (measured according to JIS K7210 at a temperature of 230 ° C. and a load of 2.16 kg) was adjusted to 50 to 300 g / 10 min. A propylene-based resin composition having an endothermic peak temperature Tmp of 120 to 150 ° C, a main exothermic peak temperature Tcp of crystallization temperature of 85 to 105 ° C, and a full width at half maximum of Tcp of 5 ° C or more. 3. The component (A) is a polypropylene block, propylene and 2 to 12 carbon atoms (excluding 3).
Of the α-olefin copolymer block, and the copolymer block accounts for 30% of the total copolymer.
The propylene-based resin composition according to claim 1 or 2, wherein the propylene-based resin composition is about 70% by weight. 4. The propylene resin composition according to claim 1, wherein the component (A) has the following physical properties (a) and (b). (A) Para-xylene insoluble matter at a temperature of 25 ° C.
65% by weight (b) Para-xylene solubles at a temperature of 25 ° C is (i)
Average propylene content (FP) of 2 site model is 2
0 to 80 mol%, (ii) a copolymer (P) formed at an active site that preferentially polymerizes propylene in a two-site model
Percentage propylene content (P _P) is 65 to 90 mol% and the (iii) P _H of _H) occupied in the copolymer (P _f1) is zero.
40 to 0.90 5. A sheet molded body obtained by molding the propylene-based resin composition according to any one of claims 1 to 4.