JPH07149911A - Production of modified polyolefin resin - Google Patents

Abstract

PURPOSE:To obtain a modified polyolefin resin which exhibits a high grafting efficiency in a wide range of mixing condition, has no cross-link between polyolefin main chains, retains high mechanical strengths inherent in a polyolefin resin, and is excellent in processibility. CONSTITUTION:A modified polyolefin resin is prepd. by melt mixing 100 pts.wt. 2-20C alpha-olefin homopolymer or copolymer with 0.1-20 pts.wt. maleic anhydride polymer having a number average mol.wt. of 200-2,000 at 120-300 deg. in the presence of a radical polymn. initiator.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention provides a modified polyolefin resin having high acid modification efficiency, no gelation between polyolefin main chains, no sublimation of acid component during processing, and excellent workability and safety. Regarding the method.

[0002]

2. Description of the Related Art Conventionally, as a method for introducing an acidic group into a polyolefin resin, for example, a method has been proposed in which maleic anhydride is heated and kneaded in the presence of a radical initiator in an extruder and grafted (US). Japanese Patent No. 3236917, Japanese Patent Publication No. 52-43677, Japanese Patent Publication No. 55-44108).

However, the above method has the following problems. That is, maleic anhydride has a too low melting point and is poorly compatible with the polyolefin resin, so that it is difficult to control the dispersion and the grafting reaction, and when the maleic anhydride vaporizes and produces a pungent odor during kneading. However, there was a problem in the working environment such as corrosion of metal parts.

[0004]

The object of the present invention is to produce an acid-modified polyolefin resin having a high grafting efficiency even under a wide range of kneading conditions, no cross-linking between polyolefin main chains, and excellent in the working environment. To provide a way to do.

[0005]

According to the present invention, (A)
With respect to 100 parts by weight of a homopolymer of an α-olefin having 2 to 20 carbon atoms or a copolymer thereof, (B) the number average molecular weight is 200
To 2000 parts by weight of maleic anhydride polymer is melt-kneaded at a temperature of 120 to 300 ° C. in the presence of a radical polymerization initiator in a proportion of 0.1 to 20 parts by weight. To be done.

The present invention will be described in more detail below. In the present invention, a modified polyolefin resin is produced by melt-kneading a homo- or copolymer of α-olefin with a polymer of maleic anhydride in the presence of a radical polymerization initiator to cause a grafting reaction. The α-olefin homopolymer or copolymer used in the present invention is a known radical polymerization, ionic polymerization or metal distribution method in which a homopolymer or a mixture of olefins having 2 to 8 carbon atoms or a mixture with another vinyl monomer is used. It is produced by position polymerization. Examples of the α-olefin homopolymer include polyethylene, polypropylene and polybutene. As the α-olefin copolymer, ethylene-propylene polymer, ethylene-propylene-diene copolymer, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-glycidyl methacrylate copolymer. Polymers and the like can be preferably mentioned.

The maleic anhydride polymer used in the present invention can be obtained by the known solution polymerization or bulk polymerization of maleic anhydride in the presence of a radical polymerization initiator. Specifically, the method described in JP-B-57-57482, for example, 10 to 20% of di-t-butyl peroxide as a radical polymerization initiator is added to maleic anhydride in an aromatic solvent such as xylene. At a polymerization temperature of 130-140 ° C for 3-8
It is produced by carrying out a polymerization reaction for a period of time. During polymerization, the molecular weight of the maleic anhydride polymer obtained varies depending on the type and amount of solvent used, the type and amount of polymerization initiator used, and the polymerization temperature, but the number average molecular weight is in the range of 200 to 2000. preferable. If the number average molecular weight is less than 200, it is not preferable because it does not meet the purpose of the present invention in terms of acid modification effect and volatility. or,
When the number average molecular weight exceeds 2,000, the production of the maleic anhydride polymer itself becomes difficult, the coloring also increases, and further, the dispersion of the acid component in the polyolefin becomes non-uniform, and the acid-modifying effect decreases, which is also preferable. Absent.

In the present invention, the blending ratio of the maleic anhydride polymer is such that the α-olefin homopolymer or copolymer is 100%.
It is in the range of 0.1 to 20 parts by weight, preferably in the range of 0.3 to 5 parts by weight, based on parts by weight. If the amount is less than 0.1 part by weight, the modifying effect is not observed, and if it exceeds 20 parts by weight, a crosslinking reaction occurs or the resin is colored, which is not preferable.

In the present invention, when the maleic anhydride polymer is grafted onto the homopolymer or copolymer of the α-olefin, for example, di-t-butylperoxide, t-butylperoxybenzoate, dicumyl peroxide, 2,2'-bis-t-butylperoxy-p
-Diisopropylbenzene and 2,5-dimethyl 2,5-
It is carried out in the presence of a radical polymerization initiator such as di-t-butylperoxyhexane. The mixing ratio of the radical polymerization initiator is 0.05 to 100 parts by weight of the maleic anhydride polymer.
A range of 10 parts by weight is preferred. If it is less than 0.05 parts by weight, the grafting reaction will be insufficient, and if it exceeds 5 parts by weight, a crosslinking reaction will occur, which is also not preferable. In the present invention, as the method of carrying out the grafting reaction, for example, a powder or pellets of an α-olefin homo- or copolymer is blended with a maleic anhydride polymer at a predetermined ratio using a Henschel mixer or the like. Then, the method of melt kneading in the presence of the above-mentioned radical polymerization initiator with a kneading machine such as a Banbury mixer or a single-screw or multi-screw extruder can be preferably mentioned. The grafting reaction is preferably carried out in the temperature range of 120 to 300 ° C. If it is lower than 120 ° C, the reaction is delayed, and if it exceeds 300 ° C, the thermal decomposition of the polyolefin becomes remarkable, which is not preferable. The kneading time is preferably in the range of 0.5 to 30 minutes, and the rotation speed at that time is preferably 10 to 400 rpm.

[0010]

EFFECTS OF THE INVENTION According to the production method of the present invention, the grafting efficiency is high under a wide range of kneading conditions, there is no cross-linking between polyolefin main chains, and the mechanical strength of the polyolefin resin does not decrease, and the workability is further improved. It has become possible to produce excellent modified polyolefin resins. Since the modified polyolefin resin obtained by the present invention contains a functional group which is a carboxyl group, it can be easily surface-modified and can be used in various applications such as films, sheets, fibers and containers.

[0011]

EXAMPLES The contents of the present invention will be described below in more detail by reference examples and examples. Parts in the examples indicate parts by weight. Reference Example 1 (Production of Maleic Anhydride Polymer by Solution Polymerization) 3.1 kg of maleic anhydride and 6.2 kg of xylene containing 40% ortho-xylene were charged into a four-necked flask made of stainless steel equipped with a stirrer with an internal volume of 10 liters. , Under nitrogen gas flow
The temperature was raised to 130 ° C. Then, with stirring, 0.62 kg of di-t-butyl peroxide was added dropwise over 2 hours. The stirring was continued for 3 hours at 130 ° C. Then, when cooled to 20 ° C., a pale yellow polymer was precipitated. After separating the upper xylene, it was dried under reduced pressure to obtain 5.02 kg of a pale yellow solid. The number average molecular weight of this solid was 732 from GPC, and the acid value was 596 mg KOH / g.

Example 1 High-density polyethylene (melt index 5.0), maleic anhydride polymer (number average molecular weight 730) produced in Reference Example and dicumyl peroxide were mixed in the proportions shown in Table 1 and biaxially kneaded. Kneading was performed at 230 ° C. for 3 minutes using an extruder. The polymer taken out was cooled to obtain pellets. At this time, the odor during the work was measured. Next, the “graft effect”, “gel fraction”, and “coloring degree” of the pellets were measured by the following measuring methods. The results are shown in Table 2.

"Measurement of Grafting Efficiency" 5 parts by weight of a kneaded and pelletized sample was subjected to acetone extraction for 24 hours with a Soxhlet extractor, and then the maleic anhydride polymer was quantified by SEC (size elution chromatography). Grafting efficiency was calculated. "Measurement of gel fraction" 1 g of crushed polymer powder was put into a washed and dried 200-mesh stainless steel wire net, and the wire net was extracted with 60 ml of boiling xylene for 12 hours. Then, the wire net was taken out, subjected to a centrifugal separator, dried in vacuum, the amount of the insoluble polymer attached to the wire net was determined from the weight, and the gel fraction was calculated by the following formula.

[0014]

[Equation 1]

"Measurement of Coloring Degree" The modified polyolefin was molded into a sheet having a thickness of 1 mm, and the yellowness YI value was measured with a color difference meter ("Color Ace TC-8600" manufactured by Tokyo Denshoku Co., Ltd.). I asked. Examples 2 to 9 Using the polyolefins shown in Table 1, the maleic anhydride polymer synthesized by the method according to Reference Example 1, and the radical polymerization initiator, the grafting reaction was performed using the reaction apparatus and reaction conditions shown in Table 1. It was The modified polyolefin obtained was used in Example 1.
"Grafting efficiency", "gel fraction", "coloring degree" and odor during reaction were measured in the same manner as in.

Comparative Examples 1 to 3 As shown in Table 1, Comparative Example 1 uses a maleic anhydride polymer having a number average molecular weight of 3000 as a grafting agent, and Comparative Example 2
For 3 and 3, the grafting reaction was performed in the same manner as in Example 1 except that maleic anhydride was used. With respect to the obtained polymer, "grafting efficiency", "gel fraction", "coloring degree" and odor during reaction were measured by the same method as in Example 1. The results are shown in Table 2.

From the results shown in Table 2, according to the production method of the present invention, the work environment is more hygienic than the comparative example, the grafting efficiency is high, there is no crosslinking reaction between the main chains, and the coloring is small. I knew that.

[0018]

[Table 1]

[0019]

[Table 2] * MI: Melt index g / 10 minutes * DCP: Dicumyl peroxide * 25B: 2,5-Dimethyl 2,5-di-t-butylperoxyhexyne

Claims (1)

[Claims] 1. A maleic anhydride polymer having (B) a number average molecular weight of 200 to 2,000 per 100 parts by weight of (A) an α-olefin homopolymer having 2 to 20 carbon atoms or a copolymer thereof. A method for producing a modified polyolefin resin, which comprises melt-kneading at 0.1 to 20 parts by weight in the presence of a radical polymerization initiator at a temperature of 120 to 300 ° C.