CA2050283A1

CA2050283A1 - Polypropylene-polyester graft copolymer and production method thereof

Info

Publication number: CA2050283A1
Application number: CA002050283A
Authority: CA
Inventors: Tadashi Sezume; Akira Kobayashi; Kikuo Inamori
Original assignee: Individual
Current assignee: Tonen General Sekiyu KK
Priority date: 1989-04-12
Filing date: 1990-04-11
Publication date: 1990-10-13
Also published as: EP0467958A1; KR920701312A; AU5422290A; EP0467958A4; JPH0347844A; WO1990012054A1

Abstract

ABSTRACT
POLYPROPYLENE-POLYESTER GRAFT COPOLYMER
AND PRODUCTION METHOD THEREOF
The invention described relates to an effective compatibilizing agent for resin compositions of a polycarbonate and a polyolefin wherein the compatibilizing agent is a graft copolymer of modified polypropylene containing functional groups reacted with a polyester having an intrinsic viscosity of 0.5 to 1.8 and terminal carboxyl group present in an amount ranging from 10 to 100 meq/Kg.

Description

2~28~

Field of the Invention 1 The present invention relates to a 2 polypropylene-polyester graft copolymer which is effective as a 3 compatibilizing agent for both of ingredients in a resin 4 composition comprising a polycarbonate and a polyolefin, in particular, a polypropylene, and a production process for the 6 graft copolymer. More in particular, it relates to a graft 7 copolymer of a polyester having specific intrins1c viscosity and 8 concentration of terminal carboxyl group and a modified 9 polypropylene having a specific melt flow rate (MFR), as well as a production process thereof.

11 Descri~tion of the Related Art 12 Aromatic polycarbonates have excellent impact resistance, 13 heat resistance, rigidity and dimensional stability, but they 14 involve a drawback of insufficient solvent resistance and moldability. For obtaining a composition of well-balanced 16 mechanical properties while compensating these drawbacks, various 17 studies have been made on blends with polyolefin. However, since 18 the compatibility between a polyolefin and a polycarbonate is 19 poor, it has been attempted to add various third ingredients for improving the compatibility.

21 As the third ingredient added to the composition of a 22 polycarbonate resin and a polyolefin resin, Japanese Patent Laid 23 Open Sho 57-108151 discloses a butyl rubber, Japanese Patent Laid 24 Open Sho 57-108152 discloses an ethylene-propylene copolymer and/or ethylene-propylene-diene copolymer, and Japanese Patent 26 Laid Open Sho 57-111351 discloses an isoprene rubber and/or methyl 27 pentene polymer.

2~283 1 There is, thus, a continuing need for an improved 2 compatibilizing agent for the polycarbonate resin and the 3 polyolefin, in particular, polypropylene, wherein the impact 4 resistance of the molding product is not reduced and the problem of surface peeling as the amount of the polyolefin is increased is 6 diminished. In view of the above, the present inventors have 7 previously proposed a process for producing a polyolefin-polyester 8 graft copolymer that can be used as a satisfactory compatibilizing 9 agent for a polycarbonate resin and a polyolefin by reacting from to 85 parts by weight of a polyester having an intrinsic 11 viscosity [~ ] of 0.30 and l.2 and a concentration of terminal 12 carboxyl group of 15 to 200 meg/ 9, and from 85 to l5 parts by 13 weight of a modified polyolefin containing 0.2 to 5 mol% of epoxy 14 groups and having a weight average molecular weight of 8,000 to 140,000 in a twin screw extruder at 260 - 320C (Japanese Patent 16 Application Sho 63-258883). However, in the course of further 17 studies, it has been found that when a polypropylene is used as a 18 polyolefin in a blend of a polyolefin and a polycarbonate, the 19 affinity is not sufficient between the polyethylene-polyester graft copolymer obtained by the process described above and 21 polypropylene and that reaction less occurs between high Mw 22 molecules of the modified polypropylene and the polyester even 23 when it is intended to produce the polypropylene-polyester 24 copolymer by the process described above.

It is, accordingly, an object of the present invention to 26 provide a polypropylene-polyester graft copolymer capable of 27 functioning as a compatibilizing agent for a polycarbonate resin 28 and a polyolefin, particularly, a polypropylene.

29 Another object of the present invention is to provide a process for producing such a propylene-polyester graft copolymer.

32 The present inventors have made earnest studies for 33 attaining the foregoing objects and, as a result, have ..

2~2~

1 accomplished the present invention based on the finding that a 2 graft copolymer of a polyester and a functional group-containing 3 modified polypropylene is effective as a compatibilizing agent for 4 a polycarbonate resin and a polyolefin, particularly, a polypropylene and that a desired polypropylene-polyester graft 6 copolymer can be obtained through grafting reaction by defining 7 the intrinsic viscosity and the concentration of the terminal 8 carboxyl group of the polyester and the functional group content 9 and the melt flow rate (MFR) of the modified polypropylene to respective specific ranges.

11 That is, a polypropylene-polyester graft copolymer 12 according to the present invention comprises from lO to 90 parts 13 by weight of a polyester having an intrinsic viscosity [~ ] of 0.5 14 to 1.8 and a concentration of terminal carboxyl group of lO to lOOO meq/Kg, and 90 to lO parts by weight of a modified 16 polypropylene containing 0.2 to 5.0 % by weight of functional 17 groups and a melt flow rate (MFR) measured at 230C under the load 18 of 2160 9~ of 0.5 to 80 g/lO min.

19 Further, a process for producing a polypropylene-polyester graft copolymer according to the present invention21 comprises reacting:
22 (a) from lO to 90 parts by weight of a polyester having an 23 intrinsic viscosity [~ ~ of 0.5 to 1.8 and a concentration of 24 terminal carboxyl groups of from lO to lOO meq/Kg, and (b) from 90 to lO parts by weight of a modified polypropylene containing O.l 26 to 2.0% by weight of functional group and a melt flow rate (MFR, 27 measured at 230C under the load of 2160 g) of 0.5 to 80 g/lO min, 28 by using a twin screw extruder at 240 - 300DC.

The polyester used in the present invention is, 31 generally, a thermoplastic resin comprising a saturated 32 dicarboxylic acid and a saturated difunctional alcohol and there 33 can be mentioned, for example, polyethylene terephthalate, _4 2~028~

1 polypropylene terephthalate, polytetramethylene terephthalate 2 (polybutylene terephthalate), polyhexamethylene terephthalate, 3 polycyclohexane-l,4-dimethylol terephthalate and polyneopentyl 4 terephthalate. Among them, polyethylene terephthalate and polybutylene terephthalate are particularly preferred.

6 It is necessary that the polyester has an intrinsic 7 viscosity [ ~ 0f 0.5 to 1.8 and a concentration of terminal 8 carboxyl group of l0 to l00 meq/Kg. The intrinsic viscosity ~y ]
9 (dl/g) is determined from a solution viscosity measured in an o-chlorophenol solvent at 25C.

11 If the intrinsic viscosity [~ ] of the polyester is less 12 than 0.5, the effect for improving the compatibility is 13 insufficient. On the other hand9 if it exceeds 1.8, the melt 14 viscosity of the reaction product is increased to bring about a difficulty in fabrication. Meanwhile, if the concentration of the 16 terminal carboxyl group is less than lO meq/Kg, reactivity with 17 the modified polypropylene is poor. On the other hand, if it 18 exceeds l00 meq/Kg, the reactivity with the modified polypropylene 19 is excessively high tending to form a gel.

Particularly, in the case of polyethylene terephthalate, 21 the intrinsic viscosity [~ ] is from 0.5 to l.O and the 22 concentration of the terminal carboxyl group is from l0 to l00 23 meq/kg. If the intrinsic viscosity [~ ] exceeds l.0, the melt 24 viscosity of the graft polymer is increased to cause gelation.
Further, the terephthalic acid ingredient in the polyethylene 26 terephthalate may be substituted with alkyl group, halogen group, 27 etc., and the glycol ingredient may contain, in addition to 28 ethylene glycol, up to about 50% by weight of other glycol, for 29 example, 1,4-butylene glycol, propylene glycol, hexamethylene glycol, etc.

31 In the case of polybutylene terephthalate, it is 32 sufficient that the intrinsic viscosity [~ ] is from 0.5 to 1.8 33 and the concentration of the terminal carboxyl group is from l0 to 34 l00 meq/Kg. Also in this case, the terephthalic acid ingredient 2 ~ 8 3 may be substituted with alkyl group, halogen group, etc. Further.
2 the glycol, up to about 50% by weight of other glycol, for 3 example, ethylene glycol, propylene glycol and hexamethylene 4 glycol.

S Furthermore, the modified polypropylene used in the 6 present invention is a polypropylene containing an unsaturated 7 monomer having a functional group.

8 The functional group contained in the modified 9 polypropylene is at least one such group that is reactive with the terminal carboxyl group or hydroxyl group of the polyester and it ll can include for example carboxyl group, epoxy group, hydroxyl 12 group and amino group. The unsaturated monomer having carboxyl 13 group is an unsaturated carboxylic acid or anhydride thereof and 14 it can include, for example, monocarboxylic acid such as acrylic acid or methacrylic acid, dicarboxylic acid such as maleic acid, 16 humaric acid or itanconic acid, dicarboxylic acid anhydride such 17 as maleic acid anhydride or itaconic acid anhydride, the 18 dicarboxylic acid and anhydride thereof being particularly 19 preferred. Further, as the unsaturated monomer having epoxy group, there can be mentioned glycidyl ester of metacrylic acid or 21 glycidyl ester of acrylic acid. Other unsaturated monomers, 22 including those having hydroxyl or amino groups, are known in the 23 art ~nd will be effective within the scope of this invention where 24 reactive as described.

The backbone for the functional group-containing modified 26 polypropylene may be any of block copolymer, graft copolymer, 27 random copolymer or intercopolymer of, e.g., propylene and it is, 28 particularly preferably, a propylene random copolymer containing a 29 non-conjugated diene comonomer represented by the general formula:
CH2 = C (CH2)n C = C - R4 31 Rl R2 R3 2~28~

1 where Rl - R4 each represents H or an alkyl group with 1 to 6 2 carbon atoms and n represents an integer of 1 to 20.

3 As the non-conjugated diene, there can be mentioned, for 4 example, 1,4-hexadiene, 7-methyl-1,6-octadiene, 5-methyl-1,4-hexadiene, l,9-decadiene, 4-methyl-1,4-heptadiene, 4-ethyl-6 1,4-hexadiene and 1,13-tetradecadiene. Among them, 1,4-hexadiene, 7 7-methyl-1,6-octadiene, 5-methyl-1,4-hexadiene and 1,9 decadiene 8 are particularly preferred. Two or more of the non-conjugated 9 diene comonomers may be used in admixture.
For the random copolymerization of propylene and the 11 non-conjugated diene comonomer, usual copolymerization process 12 using a Ziegler-Natta catalyst may be applied. In this case, it 13 is desirable that the ratio of the non-conjugated diene is from 14 0.05 to 10 mol~O. If the content of the non-conjugated diene is less than 0.05 mol%, high grafting rate can not be obtained in the 16 subsequent grafting reaction. On the other hand, if it exceeds 10 17 mol%, crystallinity of the copolymer is remarkably reduced. More 18 preferred content of the non-conjugated diene is from 0.1 to 3 19 mol%.

Further, propylene copolymerized with the unsaturated 21 monomer having the functional group as described above may be 22 incorporated as required, with less than 10% by weight of olefin 23 such as ethylene, butene-l or pentene-l, monomers such as vinyl 24 acetate, isoprene, chloroprene or butadiene.

The unsaturated monomer having the functional group may 26 be reacted with the polypropylene-non conjugated dlene random 27 copolymer by the following methods. That is, it is possible to 28 employ methods such as solution method of dissolving a random 29 copolymer into an organic solvent such as xylene or toluene, and adding to react a monomer and a radical generator to the solution, 31 or a melt-kneading method of melt-kneading a random copolymer, a 32 monomer and a radical generator using an extruder or the like 33 thereby causing reaction, etc. Particularly, the melt-kneading 1 method is suitable since the continuous reaction is easy. In the 2 case of the melt-kneading method, the reaction time is preferably 3 from lO sec to 20 min.

4 As the radical generator (reaction initiator), peroxides such as benzoyl peroxide, lauroyl peroxide, ditertiary 6 butylperoxide, acetyl peroxide, tertiary butyl peroxybenzoic acid, 7 dicumyl peroxide, peroxybenzoic acid, peroxyacetic acid, tertiary 8 butyl peroxypivalate, or diazo compounds such as 9 azobisisobutylonitrile are preferred. The blending ratio is desirably within a range from O.l to lO parts by weight based on 11 lOO parts by weight of the radical polymerizable monomer. It is 12 also possible to cause grafting reaction by kneading under heating 13 without using the radical generator.

14 It is necessary that the melt flow rate (MFR) of the modified polypropylene be from 0.5 to 80 g/lO min and the amount 16 of the functional group in the modified polypropylene be from O.l 17 to 2.0% by weight. The melt flow rate (MFR) was measured at 230C
18 under the load of 2l60 g and represented by the unit of g/lO min.
19 The functional group content was determined from the analytical value for elemental oxygen. If the melt flow rate (MFR) exceeds 21 80 g/lO min (that is, if the molecular weight is too low), 22 reaction with polyester minimally occurs, bringing about a 23 difficulty in the snythesis of the graft copolymer. If it is less 24 than 0.5 g/lO min (if the molecular weight is excessively high), the melt viscosity is increased such that moldability properties 26 are adversely affected. Generally, the average molecular weight 27 (Mw) of the modified polypropylene having MFR from 0.5 to 80 g/lO
28 min is about from 70,000 to 300~000. Further, if the functional 29 group is less than 0.1% by weight, the reactivity with the polyester is so poor that graft copolymer is minimally formed. On 31 the other hand, if it exceeds 2.00/D by weight, the melt viscosity 32 of the reaction product is increased due to the excess reaction, 33 tending to result in gel-like material.

2 ~ 3 1 For graft reacting the polyester and the modified polyolefin, 2 both of them are dry blended and then melt-kneaded at 240 - 300C, 3 for polypropylene, and at 260 - 320C for other polyolefins. The 4 melt-kneading is preferably conducted in an extruder, partlcularly, in a twin screw extruder. If the reaction 6 temperature is lower than described, the grafting is not 7 sufficient. On the other hand, if it exceeds that described, 8 excess reaction occurs and the melting temperature of the reaction 9 product is increased, tending to cause blocking in the extruder.
Further, the modified polypropylene adversely tends to be degraded 11 more easily. The time for the grafting reaction is typically from 12 about 0.5 to 15 min although it may vary depending on the reaction 13 conditions.

14 The blending amount of the polyester and the modified polypropylene is from lO to 90 parts by weight, preferably, from 16 20 to 80 parts by weight from the former and from 90 to lO parts 17 by weight and, preferably, from 80 to 20 parts by weight for the 18 latter. If the polyester is less than lO parts by weight or 19 greater than 90 parts by weight, the amount of the graft copolymer formed is reduced.

21 The thus obtained polypropylene-polyester graft copolymer 22 is useful as a compatibilizing agent for a polycarbonate resin and 23 a polyolefin, particularly a polypropylene and, generally, it is 24 added at a ratio of l to 30 parts by weight based on lOO parts by weight of the sum of both of them.

26 By defining the intrinsic viscosity [~( ] and the 27 concentration of the terminal carboxyl group of the polyester, and 28 the functional group content, and the melt flow rate (MFR) of the 29 modified polypropylene used in the graft polymerizing reaction to respective specific ranges, the grafting reaction proceeds easily, 31 a graft copolymer of sufficient grafting ratio can be obtained and 32 formation of gel due to excess reaction can be prevented. Thus 33 providing a satisfactory compatibilizing agent.

2~283 1 Exam~les 2 The present invention is to be described more in details 3 referring to the following examples.

4 In each of the examples and comparative examples, characteristics values were measured as described below.

6 (l) Intrinsic viscosity [~ ]:
7 determined from a solution viscosity measured in an 8 o-chlorophenol solvent at 25C.

9 (2) Concentratlon of terminal carboxyl group:
determined by diluting a benzyl alcohol solution of a 11 polyester with chloroform and titrating with a solution 12 of O.l N sodium hydroxide benzyl alcohol using a 0.l%
13 alcohol solution of phenol red as an indicator.

14 (3) Melt flow rate (MFR):
determined at 230C under the load of 2l60 9.

16 (4) Grafting rate:
17 grafting rate was determined by isolating ingredients 18 insoluble to both of m-cresol (lO0C) and xylene (100C).

19 (5) Gel formation:
a film of about lO0 um thickness was prepared by 21 press-molding and presence or absence of gel was judged 22 with naked eyes.

23 (6) Clogging of extruder with resin:
24 presence or absence of clogging in the die portion with gel was observed upon reaction for one hour by using 26 a twin screw extruder of 45 mm at a discharge amount of 27 30 kg/hr.

2 g 3 - lo -1 Examples l - 6~ Comparative Examples l - 3 2 As shown in Table l, after blending polyethylene 3 terephthalate or a polybutylene terephthalate each having various 4 intrinsic viscosities [ ] and concentrations of terminal carboxyl group and modified polypropylene (graft copolymer of propylene 6 non-conjugated diene random copolymer and maleic acid anhydride or 7 glycidyl methacrylate) having various functional group contents 8 and melt flow rates (MFR) at a ratio of 20/80 (by weight), they 9 were supplied to a twin screw extruder of 45 mm~ and a melt-kneaded at 280C at 200 rpm to proceed grafting reaction.
11 The residence time in the extruder was about l min.

12 The grafting rates of the reacting products were as shown 13 in Table l. In the examples, neither the gel formation nor the 14 clogging of the extruder was observed.

Example 7 16 A copolymer was produced and measured in the same manner 17 as in Example l except for using, as a polyester, a mixture of 50%
18 by weight of a polyethylene terephthalate having an intrinsic 19 viscosity t ~ of 0.72 and a concentration of terminal carboxyl group of 30 meq/Kg, and 50% by weight of a polybutylene 21 terephthalate having an intrinsic viscosity [~ ] of 0.85 and a 22 concentration of terminal carboxyl group of 52 meq/Kg. The 23 results are also shown in Table l. Also in this example, neither 24 the gel formation nor the clogging of the extruder was observed.

Examples 8~ 9 26 Copolymers were produced in the same manner as in Example 27 l except for changing the ratio (by weight) of the polybutylene 2~028~

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-13- 2$~283 1 terephthalate and the modified polypropylene to 50/50 (in Example 2 8) and 80/20 (in Example 9). The results are also shown in table 3 l. Also in this example, neither the gel formation nor the 4 clogging in the extruder was observed.

As apparent from the results of Table l, the 6 polypropylene-polyester copolymer according to the present 7 invention has high grafting ratio and, in addition, formation of 8 gel due to excess reaction can be prevented and resin clogging in 9 the extruder can also be prevented. On the other hand, it can be seen that the grafting ratio is O and grafting reaction did not 11 proceed in the copolymers of the Comparative Examples.

12 As has been described above in the present invention, 13 since polyester having an intrinsic viscosity [7~ ] and a 14 concentration of terminal carboxyl group each within a predetermined range, and a modified polypropylene having a 16 functional group content and a melt flow rate (MFR) each in a 7 predetermined range are reacted, a copolymer can be obtained at a 18 high grafting ratio.

19 The polypropylene-polyester graft copolymer according to the present invention thus obtained is extremely effective as a 21 compatibilizing agent for a polycarbonate resin and a polyolefin, 22 particularly, a polypropylene.

23 Although the invention herein has been described with 24 reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and 26 applications of the present invention. It is therefore to be 27 understood that numerous modifications may be made to the 28 illustrative embodiments and that other arrangements may be 29 devised without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims

CLAIMS:

1. A polypropylene-polyester graft copolymer comprising from 10 to 90 parts by weight of a polyester having an intrinsic viscosity of 0.5 to 1.8 and a concentration of terminal carboxyl group of 10 to 100 meq/kg, and from 90 to 10 parts by weight of a modified polypropylene containing 0.1 to 2.0 % by weight of functional groups and a melt flow rate measured at 230°C under the load of 2160 g of 0.5 to 80 9/10 min.

2. A polypropylene-polyester graft copolymer as defined in claim 1, wherein the modified polypropylene is a propylene random copolymer containing a non-conjugated diene comonomer represented by the general formula:
where R1 - R4 each represents H or an alkyl group with 1 to 6 carbon atoms and n represents an integer of 1 to 20.

3. A polypropylene-polyester graft copolymer as defined in claim 1 or 2, wherein the polyester is a polyethylene terephthalate having an intrinsic viscosity of 0.5 to 1.0 and a concentration of terminal carboxyl group of 10 to 100 meq/Kg, polybutylene terephthalate having an intrinsic viscosity of 0.5 to 1.8 and a concentration of terminal carboxyl group of 10 to 100 meq/kg, or a blend thereof.

4. A polypropylene-polyester graft copolymer as defined in any one of claims 1 to 3, wherein the functional group of the modified polypropylene is carboxyl, acid anhydride or epoxy group.

5. A process of producing a polypropylene-polyester graft copolymer comprised of reacting:
(a) from 15 to 85 parts by weight of a polyester having an intrinsic viscosity of 0.5 to 1.8 and a concentration of terminal carboxyl group of 10 to 100 meq/kg; and (b) from 85 to 15 parts by weight of a modified polypropylene containing 0.1 to 2.0% by weight of functional groups and a melt flow rate measured at 230°C under the load or 2160 g of 0.5 to 80 g/10 min.

6. The process as defined in claim 5, wherein the polyester is a polyethylene terephthalate having an intrinsic viscosity of 0.5 to 1.0 and a concentration of terminal carboxyl group of 10 to 100 meq/kg, a polybutylene terephthalate having an intrinsic viscosity of 0.5 to 1.8 and a concentration of terminal carboxyl group of 10 to 100 meq/kg, or a blend thereof.

7. The process as defined in claim 5 or 6, wherein the functional group of the modified polypropylene is carboxyl group, acid anhydride or epoxy group.

8. The process defined in claim 5 wherein said reacting is accomplished in a twin-screw extruder at 240-300°C.

9. The use of the graft copolymer of claim 1 as a compatibilizing agent for blend compositions comprising polycarbonate resin and polypropylene wherein said graft co-polymer is present in a weight ratio of 1 to 30 parts to 100 parts of said polycarbonate resin plus said polypropylene.