JPH0593020A - Modification of polypropylenic composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition resistant to the lowering of molecular weight, having high graft ratio, effective for suppressing the formation of gel and useful as a compatibilizing agent, etc., by graft-polymerizing a specific amount of a monomer having an electron attracting group and an unsaturated bond to a specific PP-based composition and modifying the graft polymer. CONSTITUTION:The objective composition is produced by modifying a polymer obtained by the graft-polymerization of (A) 100 pts.wt. of a PP-based composition containing (i) 1-99wt.% of a propylene-nonconjugated diene random copolymer containing >=1mol% of a nonconjugated diene comonomer expressed by formula (R1 to R3 are H or 1-6C alkyl, excluding the case that both R2 and R3 are H or all of R1 to R3 are alkyl; (n) is 1-20) (e.g. 1,4-hexadiene) and (ii) 99-1wt.% of PP with (B) 0.1-10 pts.wt. of a monomer having an electron attracting group and an unsaturated bond (e.g. acrylamide).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for suitably modifying a polypropylene composition as a compatibilizing agent for various resin compositions, and in particular, the reduction in molecular weight due to graft polymerization is small and the grafting ratio of the modifying monomer is high. At the same time, it relates to a method for modifying a polypropylene composition capable of suppressing the generation of gel.

[0002]

2. Description of the Related Art Polypropylene is a low-cost, moldable,
Since it has excellent insulation, chemical resistance, mechanical strength, etc., it is widely used for various purposes such as films, fibers, and molded products.

However, polypropylene is inferior in chemical properties such as adhesiveness, paintability, printability and hydrophilicity due to its structure, and various unsaturated compound monomers are graft-polymerized in order to improve those properties. Research is being conducted.

In order to graft-polymerize an unsaturated compound monomer onto polypropylene, usually, the unsaturated compound monomer is reacted by treating the polypropylene with radiation such as electron beam or ultraviolet ray or ozone to form a radical, or Alternatively, the unsaturated compound monomer is reacted in the presence of a radical generator such as an organic peroxide (for example, JP-A-48-28092, 48-62887, 48-46689).
No.).

However, according to such a conventional method, the polypropylene main chain is cleaved in the course of radical formation, so that the molecular weight is lowered and only a low graft ratio can be obtained. Therefore, problems such as smell and coloring of the unreacted monomer occur, and desired characteristics cannot be obtained. Furthermore, since the molecular weight becomes too small, there is a problem that the strength of the molded product containing the compound is low.

On the other hand, in view of the poor reactivity of propylene itself, various attempts have been made to introduce a double bond. For example, JP-A-56-36508 discloses that propylene and a general formula:

[Chemical 2]

[0007] (wherein, R ₁ represents an alkyl group, R _2, R ₃ is a hydrogen atom or more than 8 an alkyl group having a carbon of 8 or less carbon atoms, excluding the case R ₂ and R ₃ are both hydrogen atoms , A branched 1,4-diene represented by the formula (1) is copolymerized in the presence of a Ziegler-Natta catalyst to produce an unsaturated copolymer. Similar copolymers are also disclosed in JP-A Nos. 62-115007 and 62-115008.

However, even if the above-mentioned unsaturated copolymer is used, when an unsaturated compound monomer is graft-copolymerized by using a radical generator such as an organic peroxide, the main chain is cleaved and the molecular weight is also reduced. There is a problem in that

Therefore, the present inventors have made a graft polymerization of a monomer having an electron-withdrawing group and an unsaturated bond on a propylene random copolymer containing a non-conjugated diene comonomer as a modified polypropylene which has solved these problems. Proposals (Japanese Patent Application No. 1-89221, Japanese Patent Application 1-8922)
No. 2).

[0010]

However, during the modification step of the propylene random copolymer containing the above-mentioned non-conjugated diene comonomer, the copolymer itself may be crosslinked, which results in generation of a large amount of gel. However, it has been found that it becomes unsuitable as a compatibilizer for polymer alloys and causes problems such as deterioration in appearance when used for applications such as films.

Accordingly, it is an object of the present invention to provide a method for modifying a polypropylene composition, in which a decrease in molecular weight due to graft polymerization is small, a grafting ratio of a modifying monomer is high, and gel generation can be suppressed.

[0012]

As a result of earnest research in view of the above object, the present inventors have found that a propylene random copolymer containing a non-conjugated diene comonomer having at least one alkyl group at the terminal carbon of one double bond. Polymer and polypropylene-based composition containing polypropylene, by modifying the polypropylene by graft-polymerizing a monomer having an electron-withdrawing group and an unsaturated bond such as a polar vinyl monomer, a decrease in molecular weight due to graft polymerization is small. The inventors have found that the graft ratio is high and the generation of gel is suppressed, and the present invention has been made.

That is, the method for modifying the polypropylene composition of the present invention comprises (a) (i) the following general formula:

[Chemical 3] (In the formula, R ₁ to R ₃ are H or an alkyl group having 1 to 6 carbon atoms.
(However, when R ₂ and R ₃ are both H, and R ₁ to R
₃ is all alkyl groups), and n is 1 to 20.
Represents the integer. ) 1 to 99% by weight of a propylene-nonconjugated diene random copolymer containing 1 mol% or more of a nonconjugated diene comonomer represented by the formula (ii), and (ii) polypropylene 99 to 1
And 100 parts by weight of a polypropylene-based composition containing (b) a monomer having (b) an electron-withdrawing group and an unsaturated bond.
It is characterized in that 10 parts by weight is graft-polymerized.

The present invention will be described in detail below. In the present invention, the non-conjugated diene comonomer in the propylene random copolymer (i) has the general formula:

[Chemical 4]

(In the formula, R _{1 to} R ₃ are H or 1 to C
6, preferably 1 to 3 alkyl groups (provided that R ₂ , R _2
3 is H, and R _{1 to} R ₃ are all alkyl groups), and n is 1 to 20, preferably 2 to 5
Represents the integer. ).

Examples of the non-conjugated diene comonomer include 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 1,5-heptadiene,
5-methyl-1,5-heptadiene, 6-methyl-1,5-heptadiene, 5-ethyl-1,5-heptadiene, 6-ethyl-1,5-heptadiene, 1,6-octadiene, 6-methyl- 1,6-octadiene, 7-methyl-1,6-octadiene and the like can be mentioned. Of these, 7-methyl-1,6-octadiene and 1,4-hexadiene are particularly preferable. Two or more kinds of these non-conjugated diene comonomers may be mixed and used.

In order to randomly copolymerize propylene and the above-mentioned non-conjugated diene comonomer, an ordinary copolymerization method using a Ziegler-Natta catalyst may be applied. In this case, the proportion of the non-conjugated diene is 1 mol% or more. When the content of the non-conjugated diene is less than 1 mol%, a high graft ratio cannot be obtained in the graft reaction described later. The preferred content of non-conjugated dienes is 1.5 to 2.5 mol%.

The propylene-non-conjugated diene random copolymer may contain other unsaturated monomers such as ethylene and butene-1 in an amount of 5 mol% or less. The molecular weight of such a propylene-non-conjugated diene random copolymer is usually 100,000 to 1,000,000.

In the present invention, the polypropylene to be mixed with the propylene-non-conjugated diene random copolymer is not limited to a propylene homopolymer, but may be a block copolymer or a random copolymer of propylene and another α-olefin such as ethylene or butene-1. Including a copolymer. A copolymer with ethylene is particularly preferable. In the case of copolymers, other α-
The content of olefin is 10% by weight or less. Such polypropylene usually has a melt flow rate (MFR, JIS K7210, load 2.16 kg, 230 ° C.) of 0.5 to 80 g / 10 minutes.

The mixing ratio of the propylene-non-conjugated diene random copolymer as described above and polypropylene is
The propylene-non-conjugated diene random copolymer is 1 to 99% by weight, preferably 5 to 80% by weight, and the polypropylene is 99 to 1% by weight, preferably 95 to 20% by weight. When the propylene-non-conjugated diene random copolymer is less than 1% by weight (when the polypropylene exceeds 99% by weight), a high graft ratio cannot be obtained in the graft reaction. Further, when the propylene-non-conjugated diene random copolymer exceeds 99% by weight (when the polypropylene is less than 1% by weight), a large amount of gel is formed during the graft reaction.

In the present invention, the monomer to be graft-polymerized on the polypropylene composition has an electron-withdrawing group and an unsaturated bond. Examples of the electron-withdrawing group include a nitro group, a carbonyl group, a carboxyl group and a nitrile group. The unsaturated bond includes a vinyl bond or an acetylene bond. Such compounds are
Specifically, acrylamide, N, N-dimethylacrylamide, methacrylamide, N, N-diethylmethacrylamide, 2-vinylpyridine, glycidyl acrylate, glycidyl methacrylate, vinyl isocyanate, vinyldiphenylamine, N-vinylphthalimide, methyl vinyl sulfide. , Vinyl sulfonic acid, acrylic acid, maleic anhydride, vinyltriethylsilane, allyltriethoxysilane, methyl vinyl ketone, acrolein, acrylonitrile, ethyl vinyl ether, vinyl formate, vinyl acetate, vinyl trifluoroacetate, vinyl benzoate, allyl stearate, Examples thereof include vinyl chloride, vinylidene chloride, styrene, α-methylstyrene and the like.
Of these, maleic anhydride, acrylamide, glycidyl methacrylate and the like are preferable.

Next, a modification method (graft polymerization) using such a grafting monomer will be described. Graft polymerization can be performed by either a solution method or a melt-kneading method. In the case of the melt kneading method, polypropylene, propylene-non-conjugated diene random copolymer, a monomer having an electron-withdrawing group for modification and a monomer having an unsaturated bond, and optionally a catalyst, in an extruder or a twin-screw kneader. It is charged and heated to a temperature not lower than the melting point of the resin component, preferably 180 to 300 ° C., and kneaded for 0.1 to 20 minutes while melting. In the case of the solution method, the above starting materials are dissolved in an organic solvent such as xylene,
Stir for 0.1 to 100 hours at a temperature of ~ 200 ° C. In any case, it is possible to use a normal radical polymerization catalyst as a catalyst, for example, benzoyl peroxide, lauroyl peroxide, ditertiary butyl peroxide, acetyl peroxide, tert-butyl peroxybenzoic acid, dicumyl peroxide, Peroxybenzoic acid, peroxyacetic acid, tert-butyl peroxypivalate, 2,5-dimethyl-
Peroxides such as 2,5-ditertiarybutylperoxyhexyne, diazo compounds such as azobisisobutyronitrile and the like are preferable. The amount of catalyst added is 100
It is about 0.01 to 1 part by weight with respect to parts by weight. In the present invention, a phenolic antioxidant may be added during the above graft reaction. However, when the radical polymerization catalyst is not added, it is preferable not to add it.

Total of polypropylene composition (propylene-non-conjugated diene random copolymer + polypropylene)
The blending ratio of the graft comonomer to 100 parts by weight is 0.1 to 10 parts by weight (grafting rate 0.1 to 10% by weight). Particularly, the method of the present invention has a graft ratio of 1 to 10
It is suitable when it is as high as wt%.

The polypropylene-based composition (graft copolymer composition) modified in this way has a very small rate of decrease in molecular weight, which makes it a modified polypropylene composition of high molecular weight which cannot be obtained by the conventional method. be able to. In addition, it is well balanced in terms of gel fraction, grafting ratio of modifying monomer, and the like.

[0025]

In the method for modifying a polypropylene resin composition of the present invention, a polypropylene containing polypropylene and a propylene random copolymer containing a non-conjugated diene comonomer having an alkyl group at the terminal carbon of one double bond Since the polypropylene resin composition is modified by graft-polymerizing a monomer having an electron-withdrawing group and an unsaturated bond such as a polar vinyl monomer into the system-based composition, there is little decrease in molecular weight due to graft polymerization, and the graft ratio is In addition to being high, the generation of gel is suppressed.

The reason why such an effect is obtained is not necessarily clear, but it is considered as follows. That is, a non-conjugated diene comonomer having at least one alkyl group on the terminal carbon of one double bond is polymerized on the other side with propylene to produce propylene-
On the side having an alkyl group at the terminal carbon of the double bond that is introduced into the main chain of the non-conjugated diene random copolymer and becomes a side chain, gelation due to cross-linking between them is less likely to occur. However, an electron-withdrawing group such as a polar vinyl monomer and a monomer having an unsaturated bond are easily graft-polymerized. In the present invention, since the composition of such a propylene-non-conjugated diene random copolymer and polypropylene is modified, further reduction of the molecular weight is suppressed, and improvement of the grafting ratio of the modifying monomer is achieved. Thus, it becomes suitable as a compatibilizing agent for various resin compositions.

[0027]

The present invention will be described in more detail with reference to the following specific examples. The following materials were used as raw materials and additives in each example and comparative example. [1] Polypropylene ・ HPP: Propylene homopolymer [melt flow rate (MFR 230 ℃ 2.16kg load) 1.5g / 10min] [2] Non-conjugated diene ・ 7-Methyl-1,6-octadiene: MOD [3] Radical Generator ・ Perhexin 2-5B: POX [Nippon Oil & Fats Co., Ltd.]

Examples 1-7, Comparative Examples 1-5 Propylene-Nonconjugated Diene Random Copolymer (PPDM)
Is propylene and 7-methyl-1,6-octadiene (MO
And (D) were obtained by random copolymerization at 70 ° C. using a Ziegler-Natta catalyst (catalyst for propylene polymerization containing titanium trichloride as a main component). The comonomer copolymerization amount and melt flow rate of the obtained random copolymer (PPDM) were as shown in Table 1.

This random copolymer, homopolypropylene (HPP), maleic anhydride (MAH) in the amount shown in Table 1 as a modifying monomer, and the radical generator (POX) in the amount shown in Table 1 were used. And were dry blended with a Henschel mixer, and then with a 45 mmφ twin-screw extruder.
Graft polymerization was carried out by melt-kneading at 200 rpm at the temperature shown in the table. Comparative Example 5 is an example obtained by modifying homopolypropylene (HPP) alone.

The melt flow rate of the modified polypropylene thus obtained, the graft ratio of maleic anhydride, and the gel fraction were measured. The results are also shown in Table 1.

Table 1 Organization Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Content of non-conjugated diene in PPDM (mol%) 2.1 2.1 2.1 2.1 2.1 2.1 MFR (g / 10 min)⁽¹⁾ 2.0 2.0 2.0 2.0 2.0 2.0 Amount of PPDM (parts by weight) 70 50 30 10 50 30 Amount of HPP (parts by weight) 30 50 70 90 50 70 Denaturing conditions Temperature (° C) 200 200 200 200 200 200 200 Amount of POX added (parts by weight) 0.2 0.2 0.2 0.2 0.5 0.5 Amount of MAH added (parts by weight) 3 3 3 3 5 5 Physical properties of graph copolymer MFR (g / 10 minutes)⁽¹⁾ 20 42 63 100 58 122 MAH content (wt%)⁽²⁾ 2.6 2.2 1.7 1.2 3.3 2.3 Gel fraction (wt%)⁽³⁾ 22.0 12.0 1.6 0 20.7 6.8

Table 1 (continued)Organization Example 7 Comparative Example 1 Comparative example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Content of non-conjugated diene in PPDM (mol%) 1.2 2.1 2.1 1.2 0.6-MFR (g / 10 min)⁽¹⁾ 44 1.3 1.3 44 8.2 − Amount of PPDM (parts by weight) 70 100 100 100 50 − Amount of HPP (parts by weight) 30 − − − 50 100 Denaturing conditions Temperature (℃) 200 200 200 200 200 200 POX addition amount (part by weight) 0.5 0.2 0.5 0.5 0.1 0.5 MAH addition amount (part by weight) 5 3 5 5 3 5 Physical properties of graph copolymer MFR (g / 10 minutes)⁽¹⁾ 89 3.8 5.4 3.2 107 300 or more MAH content (% by weight)⁽²⁾ 2.9 2.6 3.5 3.0 0.7 0.5 Gel fraction (wt%)⁽³⁾ 1.5 35.7 47.9 25.3 0 0

(1) MFR: A value measured according to JIS K7210. (2) Maleic anhydride content: The modified polypropylene composition was pressed to a thickness of about 50 μm, and the IR spectrum was measured. The peak of stretching of the C═O bond of maleic anhydride (1780
cm ^-1 ), one of the peaks specific to isotactic PP (840 cm ^-1 ), and one of the peaks specific to PPDM (cm
^-1 ) and the ratio. (3) Gel fraction: Modified polypropylene was press-molded to a thickness of 0.5 mm, about 4 g of this was immersed in boiling xylene for 24 hours, and then the insoluble matter was weighed to determine the gel fraction = xylene insoluble matter. Calculated by weight / initial weight x 100 (%).

As is clear from Table 1, the modified polypropylene composition according to the method of the present invention does not increase the melt flow rate after modification too much and can increase the graft ratio of maleic anhydride. The gel fraction was also low.

On the other hand, the modified polypropylene compositions of Comparative Examples 1 to 3 modified with only PPDM have a gel fraction of
The modified polypropylene composition of Comparative Example 4, which has a MOD content in PPDM of less than 1 mol% and is too high as 25% by weight or more, has a too low maleic anhydride content and is further modified with homopolypropylene. In Comparative Example 5, the content of maleic anhydride was too low, and the melt flow rate increased too much.

[0036]

As described in detail above, according to the method of the present invention, a propylene random copolymer containing a non-conjugated diene comonomer having at least one alkyl group at the terminal carbon of one double bond, and polypropylene. Since the polypropylene resin composition is modified by graft-polymerizing a monomer having an electron-withdrawing group and an unsaturated bond, such as a polar vinyl monomer, to the polypropylene-based composition containing, a decrease in molecular weight due to graft polymerization The number is low, the graft ratio is high, and the generation of gel is suppressed.

Therefore, the concentration of the functional group introduced by the graft monomer is increased, which greatly contributes to the improvement of chemical properties such as adhesiveness, paintability, printability and hydrophilicity, and moreover, is caused by the unreacted monomer. Smell and color problems are also greatly reduced. Further, since the decrease in the molecular weight is small, the deterioration of the resin composition self-exhaustion is small.

The modified polypropylene composition of the present invention is suitable as a compatibilizing agent to be added to resin compositions such as automobile parts, home electric appliance parts, industrial material parts and packaging materials.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuji Fujita 1-3-1 Nishitsurugaoka, Oi-cho, Iruma-gun, Saitama Tonen Co., Ltd.

Claims (1)

[Claims] 1. (a) (i) The following general formula: (In the formula, R _{1 to} R ₃ are H or an alkyl group having 1 to 6 carbon atoms.
(However, when R ₂ and R ₃ are both H, and R _{1 to} R
₃ is all alkyl groups), and n is 1 to 20.
Represents the integer. ) A polypropylene-based composition 100 containing 1 to 99% by weight of a propylene-nonconjugated diene random copolymer containing 1 mol% or more of a nonconjugated diene comonomer represented by the formula (ii) and 99 to 1% by weight of polypropylene (ii). In parts by weight, (b) the monomer having an electron-withdrawing group and an unsaturated bond 0.1 to
A method for modifying a polypropylene composition, which comprises graft-polymerizing 10 parts by weight.