JPS59145242A - Impact resistance improved propylene copolymer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION A traditional problem experienced with polypropylene it impact copolymers is the existence of a typical alternative relationship between impact strength and melt flowability. That is, as melt flowability increases, impact strength decreases.

As a result, products with high dawn resistance but low melt flowability are difficult to injection mold into thin parts, such as battery cases.

The prior art discloses several methods of improving the melt flow versus impact strength relationship by oxidative decomposition methods. Kutoe Japanese Publication No. 21731/73 discloses improved results by heat treating ethylene-propylene block copolymers in the presence of peroxides. Also, U.S. Patent No. 3.9
No. 40.379 and No. 4.061.694 disclose methods for the oxidative decomposition of several types of substantially crystalline propylene polymers. An essential feature of the latter two methods is that the oxidative decomposition must be carried out in the presence of oxygen and peroxide.

Although these prior art methods provide considerable improvements in melt flow rates, they produce resins suitable for injection molding of rigid thin-walled products with high impact strength and tensile tolerance, especially at low temperatures. That has not become possible.

In accordance with the present invention, a high impact strength polypropylene copolymer #I composition with controlled rheological properties is prepared by the following method.

I (a) about 70 to about 99 parts by weight of a block copolymer containing about 70 to about 90 parts by weight of propylene polymer parts and about 10 to about 30 parts by weight of ethylene-propylene copolymer blocks; and (b) about 1 ethylene-propylene elastomer component.
The total content of ethylene derived units in the resin mixture ranges from about 5 to about 20 parts.

) and (2) treating the resin mixture with a free radical generating compound under controlled oxidative decomposition conditions at a temperature of about 400F to about 550F without the addition of oxygen.

During this process, both the block copolymer and the polypropylene fraction of the elastomer undergo chain cleavage, making them more melt-flowable, and the ethylene polymer fraction of these components is cross-linked to form higher molecular weight molecules. , it is thought that it forms a very tough fraction.

Also, because propylene and ethylene polymer groups are formed simultaneously, some of these groups react with each other to form branching that improves impact resistance.

The predominant reaction is the shearing of the bonded steel, i.e. an increase in melt fluidity, while the impact y! & loss of elasticity is due to graft (gra
(Nng) and cross-1 inking
), which is compensated by the larger amount of rubbery part'' produced by the polymer, and by the rubbery part of the polymer.

The present process provides a resin product in which the melt comb flow properties are increased considerably, while largely retaining the physical properties of the original low melt flow resin.

The propylene polymer portion of the block copolymer component, which accounts for 0 to 90% by weight of the muff, is a propylene homopolymer'! or a random copolymer of propylene and a small amount of ethylene. Up to 8% by weight of units derived from ethylene may be present in this propylene portion. The amount of ethylene derived units within the total block copolymer is preferably limited to a total range of about 4 to about 15 units.

This type of block copolymer can be produced by any known catalytic polymerization method and is also available in a number of polymers. Although the block copolymer was defined as a single compound for the purpose of the present invention7, in fact, in the KB 1.7" rock copolymerization process, the block copolymer and a small amount of ethylene and propylene homopolymers were used. It is to be understood that mixtures with polymers and random copolymers are produced.

The ethylene-propylene elastomer component may be any known commercially available EP rubber.

It is a copolymer of ethylene and propylene, typically containing about 30 to about 70% by weight polymerized ethylene. If desired, a third monomer can be added to the ethylene-propylene rubber to enhance the crosslinking ability of the rubber.

The third monomer typically contains a non-conjugated diene containing 6 to 8 carbon atoms and having one terminal double bond and one non-terminal double bond, such as 1.4 -hexadiene, 1,5-hebutadiene, etc. The resulting terpolymer is known in the art as EPDM rubber and is commercially available.

To facilitate processing and blending, the nidistomer is sometimes blended with V30-50 grade polypropylene or polyethylene.

Whether it is EP rubber, EPDM rubber or a mixture of one of these compounds with either polypropylene or mesh polyethylene, the amount of the nidistomer component is determined by the resin components (a) and (b) of the composition according to the invention. The concentration should not exceed about 30% by weight, based on the total of 1 weight percent, and preferably the concentration is kept from about 3% to about 15% by weight.

The resin before oxidative decomposition treatment is usually 230℃, about 2,]6K.
It has a melt flow rate of about 0.1 to about 5 g per 10 minutes at pK.

The free radical initiator used in the controlled oxidative decomposition treatment of the resin mixture is one that decomposes normally, i.e., about 400°
It should have a half-life of at least 3 to 6, but preferably no more than about 15, under typical extrusion conditions at 55' to 55'OFK.

Many organic peroxides are used alone or in combination for this purpose. For example, dicumyl peroxide, di-t-butyl peroxide, t-butyl hydroperoxide, t-butyl perbenzoate, 2,5-dimethyl-2,5-di-t-
-butylperoxyhexane, 2,5-dimethyl-2,
5-di-t-butylperoxyhexine and the like. The concentration of peroxide will vary depending on the initial melt flow and desired final melt flow, but will generally range from about 100 to about 15
00 ppm, preferably about 300 to 11000 ppm
must be within the range.

Controlled oxidative decomposition is carried out in an extruder or in a pelletizing system.

The extruder operates under normal pelletizing conditions from about 400"F' to about 550F. A typical #!
IF! IA residence time ranges from about 0.5 minutes to about 3 minutes. During the oxidative decomposition process, the extrusion operation is carried out in an inert atmosphere, ie, with no oxygen or air entering the extruder. The extruded resin is pelletized using conventional commercially available equipment.

The process is easy to control and has high melt flow rates, such as in the range of 10 to about 7,577 per minute for 10 minutes at 230°C, even higher, with a high melt flow rate at room temperature or below. A product is obtained which is particularly suitable for injection molding of thin-walled articles with good odor strength.

This resin is completely homogeneous and is particularly suitable for the manufacture of battery cases, gun cases, trunk lines, fender liners, etc.

The examples below further illustrate the invention.

Example 1 NOldel® NDG4167 EPDM elastomer introduction composition obtained from Dubonde.
(33% by weight of high-density polyethylene, 67 parts by weight of a terpolymer consisting of #1v equivalents of ethylene and propylene and a small amount of 1,4-hexadiene) 5 parts by weight and 8 parts by weight
6% by weight propylene homopolymer and 14% ethylene-propylene rear (ρo,st) block (the ethylene content in this block is up to about 40 parts).
Using pellets of a resin mixture composed of 95 parts by weight of a polypropylene block copolymer consisting of
A series of experiments were conducted at several levels of peroxide concentration ranging from 0 to 11,000 pp. In both experiments, the resin mixture was further mixed with the oxidizer of the number shown in Table 1, followed by 2.5 inch Prodex
) It was extruded into pellets using an extruder at 500F. The experimental results are summarized in Table 1.

As can be seen from the data, the physical properties are almost unchanged at 26MF''+.
C has no loss at all, and even at 668σF there is only a slight loss in impact strength.

Di-t-butyl peroxide, ppm.

#F melt flow-g/10 min, 230'C4 tensile strength, p
si At yield point 3460 At break point 2560 Elongation, g 4o.

Tensile modulus, 10' psi 1.4
5 bending modulus, IQ'psi 1.4
1 distortion, 7? (66 psi smell) 96 Izod impact, ft-1b/in 3.3 Gardner impact, 1n-1b OF 〉32〇-40F at 57 *-2 of 5 samples showed different elongations i.

Table 1 300 400 500]
000] ] ] 5 26
663200 3150
3200 31002450 253
8 2570 2235>575
* 140 >670 >575 1.46 1.5] 1.56
1.441.24 1.24
1.24 1.15101 102
106 1072, 7 2
．． s2. s 2.532
0 208-256 156-256
17390 73 56
Example 2 A resin pellet of similar composition to that of Example 1, except that the block #polymer/elastomer mixing ratio was 90:10, was prepared in 5007 in the presence of 50 Q ppm of di-1-butyl peroxide. Subjected to controlled decomposition in a 25 inch Prodex extruder. Table 2 shows the compared data.
It was shown to.

-Table 2 3 500 11.4 4.4 24
6. Controlled minute wIFI provides a resin with the desired high melt flow rate and extremely high Gardner impact value that is almost the same as the starting low melt flow resin.

It will be apparent to those skilled in the art that many variations and modifications can be made to the compositions and methods of manufacture described herein.

All such developments from the above description are considered to be within the scope of the invention as defined by this specification and the appended claims.

Patent Applicant L.Pan Polyolefins Company Procedural Amendment March 21, 1980 Patent Office ν Hunting Wakasugi 7 "1" Husband 1, Incident Indication u+14t159 Yearly Publication Tekisou No. 1428 2, Title of Invention 1lilf +IIIJn741 King's) = v-ku a,
rt Globi V7 Kyori script 3, relationship with the case of the person making the amendment Patent applicant 4, agent 〒107h, H entry q no 1u9 ゛＼The first contribution to the specification. ” before 11 dredging decomposition treatment. 4 fat
The melt flow excitation velocity has a 10-minute value of about 0.1 to 1 fJ5F at a test temperature of R l 6 Kf and a test load of R l 6 Kf. "I" pressure.

Claims (1)

[Claims] 1, 1 (a) About 70 to about 90 parts by weight of propylene polymer portion and about 10 to about 30 parts by weight! a block copolymer containing about 70 to 99 parts by weight of an ethylene-propylene copolymer block, and (b) about 1 part of an ethylene-propylene elastomer component.
Prepare a resin mixture of from about 30 to about 30 ethylene-derived units (wherein the total number of ethylene-derived units in the resin mixture ranges from about 5 to about 201 units); High rM1 strength with controlled rheological properties produced by a process comprising treatment at temperatures from about 400F to about 550F with free radical generating compounds under controlled oxidative decomposition conditions without additives. A propylene copolymer silk composition. 2. The composition according to claim 1, wherein the propylene polymer portion is a propylene monofii polymer. 3. The propylene polymer portion of component (a) is propylene and 8
The composition according to claim 1, which is a random copolymer with ethylene not exceeding the weight ratio. 4. The composition of claim 1, wherein the copolymer block of component (a) contains about 4 to about 15 weight percent polymerized ethylene units. 5. The composition of claim 1, wherein the nidistomer is an ethylene-propylene rubber component containing from about 30 to about 70% by weight of polymerized ethylene. 6. Claims characterized in that the ethylene-propylene rubber is a terpolymer of ethylene-propylene and a non-conjugated diene having one terminal double bond for every 6 to 8 carbon atoms. Composition of the fifth apex memorization. 7. The composition according to claim 5, wherein one cystomer component is a mixture of ethylene-propylene rubber and a compound selected from polyethylene or polypropylene. □8. Ethylene-propylene elastomer component; d! The composition of claim 1, wherein the amount is about 3 to about 15% by weight of the resin in step (2). 9. The composition according to claim 1, wherein the melt flow rate of the resin in step (i) is from 0.1 to about 52 yen per 10 minutes at 230'C. 10. The free radical polymerization initiator is peroxidized (cumyl, di-t-butyl peroxide, t-butylhydroperoxy)*,
3fS t-butyl benzoate, 2.5-cy)1tyl-2,
5-di-t-butylperoxyhexane and 2.5-
A composition according to claim 1, characterized in that dimethyl-2,5-di is selected from monobutylperoxyhexine. 11. The composition of claim 1, wherein the peroxide concentration is maintained between about 100 pI)m and about 1500 ppm. 12. The peroxide immersion degree is about 300 to about 1000 pp
@ Box No. 11 of the patent claim characterized in that it is maintained at rn.
Compositions as described in Section. 13. The composition according to claim 1, wherein the free radical polymerization initiator is di-t-butyl peroxide. 14. The composition according to claim 1, wherein #' after treatment has a fat melt flow rate in the range of about 10 to about 759 in 10 minutes at 230°C.