JPH038641B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for chlorinating polyolefins. Specifically, the present invention relates to a method for stably obtaining rubbery chlorinated polyolefin in the form of fine particles without containing coarse aggregated chlorinated substances in the production of chlorinated polyolefin by an aqueous suspension chlorination method. (Prior art and problems) The fact that chlorinated polyolefin is in the form of fine particles means that it cannot be used with inorganic or organic additives, plasticizers, and stabilizers that are usually used as compounding agents when molding it. It is extremely advantageous for improving the mixability with other polymers, such as polyvinyl chloride, polyethylene, ABS resin, etc., and can be blended extremely smoothly with other polymers such as polyvinyl chloride, polyethylene, ABS resin, etc., and it greatly improves the quality of the compound. This is very desirable because it contributes to Conventionally, when polyolefin is chlorinated in an aqueous suspension at a temperature of 100°C or higher, particles coagulate and stick together as the chlorination progresses, making it extremely difficult to obtain a stable and homogeneous particulate chlorinated product. It was difficult. In order to solve this problem, various attempts have been made to prevent particles from coagulating and adhering to each other during the chlorination process, but a satisfactory particulate chlorinated polyolefin has not yet been obtained. In practice, many attempts have been made to achieve this goal by using protective colloids during chlorination. For example, a method using polyacrylic acid, a copolymer of maleic anhydride and methyl vinyl ether or styrene, or polyacrylamide, poval, polyvinylpyrrolidone, etc. Publication No. 47-7455, etc.) are known. However, in the method of using these protective colloids, even if fine particles are used as raw materials, the chlorinated products obtained are at most about 0.5 mm in diameter, and these chlorinated products are stable against light and heat. However, it contained problems such as coloring. There are also known methods of preventing agglomeration during chlorination using inorganic or organic fine powders such as titanium dioxide, carbon black, talc, silica, and polyvinyl chloride; It is not very effective unless they are added in a considerable amount, and it is difficult to separate and remove them after the reaction, and there are restrictions on the use of the product, so this is not a very practical method. (Objective of the Invention) The present invention provides a method for producing finely powdered rubbery chlorinated polyethylene, which itself has favorable stability and excellent physical properties, and has good kneading properties. (Structure of the Invention) The present invention provides the use of a polymer of acrylic acid or an acrylic acid ester, a copolymer thereof, or a copolymer thereof as a dispersant when chlorinating a powdered polyolefin having a crystal structure under aqueous suspension. Alternatively, a method for producing a chlorinated polyolefin, which comprises using either an alkali metal salt or an ammonium salt of a copolymer and a styrene polymer containing a sulfonic acid group and having anionic activity, and chlorinating with chlorine gas. It is. The polyolefin used in the present invention is α-
Homopolymers or copolymers of polyolefins, such as polyethylene, polypropylene, ethylene-propylene copolymers, ethylene-acrylic acid ester copolymers, ethylene-butene copolymers, propylene-butene copolymers, ethylene-vinyl acetate copolymers A general term for polymers having a crystal structure such as polymers and ethylene-butadiene copolymers. The molecular weight of the polyolefin is usually 40,000 to 1,000,000, preferably 40,000 to 300,000. When the polyolefin used is polyethylene, it is preferable to use the polyethylene of the Ziegler process or the Phillips process in order to obtain fine particulate chlorinated products with good kneadability, which is the object of the present invention, and the former low-medium pressure process is particularly preferred. By using polyethylene, the effects of the present invention can be maximized. There is no particular restriction on the particle size of the polyolefin used, but in order to obtain fine particulate chlorinated polyolefin with good kneadability, it is preferable that the particle size be as fine as possible. However, depending on the purpose, a relatively large particle size may be sufficient, and in the present invention,
This can be carried out using a raw material polyolefin having a diameter of 50 to 1000 μm. In the present invention, polymers of acrylic acid or acrylic esters or copolymers thereof, or alkali metal salts or ammonium salts of these polymers or copolymers (hereinafter collectively referred to as acrylic acid-based As a polymer), the molecular weight is 3000 or more, especially 10000.
The above are preferred. The acrylic ester is preferably an alkyl ester having 1 to 4 carbon atoms. The anionically active styrenic polymer used as a dispersant in the present invention is a copolymer of styrene and an alkali metal styrene sulfonate, or a copolymer of styrene, another comonomer, and an alkali metal styrene sulfonate. An anion-activated styrenic polymer containing 6,000 to 100,000, preferably 20,000 to 60,000 sulfonic acid groups is used. Examples of the comonomer component of the copolymer include maleic anhydride, α-methylstyrene, acrylic acid, vinyl ester, vinyl ether, vinyl ketone, and vinyl acetate. The comonomer component in the copolymer is preferably 15 mol% or less.
Further, the amount of sulfonic acid groups in the anionically active styrenic polymer is suitably in the range of 5 to 50% by weight of the polymer. As the method for chlorinating polyolefin in the present invention, a conventional method for producing rubbery chlorinated polyolefin is employed, in which chlorination is carried out using chlorine gas near the softening temperature of the raw polyolefin. Alternatively, the chlorination reaction can be carried out in two stages, for example, until the chlorine content reaches 15 to 20% by weight, it is carried out at a temperature below 10°C below the melting point of the polyolefin used, and then the final chlorine content is carried out at a temperature above the melting point of the polyolefin to +20°C. A method in which the temperature is within the temperature range can also be adopted. The final chlorine content of the chlorinated polyolefin is 25 to 55% by weight depending on the purpose of use of the chlorinated polyolefin. The amount of dispersant added during the chlorination reaction is 0.1 to 1% by weight based on the raw material polyolefin.
It is preferably in the range of 0.3 to 0.7% by weight. The amount used is determined by taking into account the type of raw material polyolefin used and the chlorination reaction temperature, but if the amount used is less than 0.1% by weight, polymer fusion and agglomeration are likely to occur during the chlorination reaction, and the present invention It is difficult to obtain the desired powdered chlorinated product with homogeneous particles. Moreover, even if the amount used exceeds 1% by weight, there is no problem in practice, but the effect proportional to the amount added cannot be obtained, which is economically disadvantageous. The ratio of the acrylic acid polymer and the anionically active styrene polymer in the dispersant may be arbitrary, but
Usually, the anionically active styrenic polymer is preferably used in a range of 20 to 90% by weight based on the total amount of both.
When only a conventionally known acrylic acid polymer is used as a dispersant (Japanese Patent Publication No. 46-21729)
Although relatively fine particles were used as the raw material polyolefin, the particle size of the obtained chlorinated polyolefin was often around 0.5 mm, which is far below the practically required particle size of 0.3 mm or less. It has been difficult to obtain finer particulate chlorinated polyolefin. According to the present invention, by using a dispersant containing an anionically activated styrenic polymer in the above ratio, a chlorinated polyolefin having a particle size not significantly different from the particle size of the raw material polyolefin used can be obtained. In the present invention, the chlorination reaction can be carried out effectively using only the above-mentioned dispersant, but the reaction can be carried out effectively by using a small amount of a surfactant in combination. Furthermore, in order to more effectively prevent the blocking property of the obtained chlorinated polyolefin, stearic acid or a salt or ester thereof, silicic acid, fine polyvinyl chloride powder, etc. can be added within a range that does not contradict the purpose of use. (Example) Example 1 3.0 kg of polyethylene with an average molecular weight of 8 x 10 ⁴ , a density of 0.934, a melt index of 4.5, an average particle size of 250 μm, and a crystallinity of 70% was placed in a 100 mm glass-lined pressurized reaction vessel equipped with a stirrer and 60 kg of ion-exchanged water was added. Put it with
Add 2 ml of nonionic surfactant to this, and use a copolymer of styrene with a molecular weight of 60,000 and sodium styrene sulfonate (sulfonic acid group content) as a dispersant.
33.2% by weight) and 6g of an acrylic acid polymer aqueous solution (PH 2.0, molecular weight 13000, solid content 30% by weight) were added and chlorinated with chlorine gas at 113°C until the chlorine content became 35% by weight. After washing and drying in a conventional manner, a white powder with an average particle size of 300 μm was obtained. Example 2 3.0 kg of a polyethylene polymer having an average molecular weight of 1.4×10 ⁵ , a density of 0.950, a melt index of 0.8, an average particle size of 220 μm, a crystallinity of 79%, and a propylene content of 3 mol % was placed in the same reaction vessel as in Example 1. with 60% ion-exchanged water, and add 35% molecular weight as a dispersant.
12 g of a copolymer of styrene and sodium styrene sulfonate containing 5 mol% of α-methylstyrene (sulfonic acid group content 25.0% by weight) and an aqueous ammonium salt solution of a copolymer of acrylic acid and methyl acrylate (molecular weight 27,000, solid content 30% by weight) was added and chlorinated with chlorine gas at 118°C until the chlorine content was 20% by weight, then the temperature was raised to 127°C and chlorine was added until the chlorine content was 40% by weight. It became. During the chlorination reaction, a white powder with an average particle size of 280 μm was obtained without agglomeration of the polymer. Example 3 3.0 kg of polyethylene having an average molecular weight of 2.4×10 ⁶ , a density of 0.953, a melt index of 0.5, an average particle size of 140 μm, and a crystallinity of 84% was placed in a reaction vessel similar to that of Example 1 together with 60 g of ion-exchanged water. Add 2ml of ionic surfactant and use it as a dispersant with a molecular weight of 43000.
10 g of a copolymer of styrene and sodium styrene sulfonate (sulfonic acid group content 45.0% by weight) and 1.5 g of polyacrylic acid sodium salt with a molecular weight of 34000 were added at a temperature of 122°C until the chlorine content became 35% by weight. Chlorinated with chlorine gas. After washing and drying in a conventional manner, a white powder with an average particle size of 200 μm was obtained. Comparative Example 1 The chlorine content was determined in the same manner as in Example 1, except that only 15 g of an acrylic acid polymer aqueous solution (PH 2.0, molecular weight 13000, solid content 30% by weight) was used as a dispersant.
It was chlorinated to 35% by weight. After washing and drying in a conventional manner, a white powder with an average particle size of 560 μm was obtained. Comparative Example 2 In Example 2, a dispersant with a molecular weight of 35000
Chlorination was carried out in the same manner until the chlorine content was 40% by weight, except that only 20 g of styrene and sodium styrene sulfonate copolymer containing 5 mol% of α-methylstyrene (sulfonic acid group content: 25.0% by weight) was used. did. The obtained chlorinated product has an average particle size of
It was a white powder with a diameter of 450 μm. Comparative Example 3 In Example 3, molecular weight 2,
Chlorination was carried out in the same manner except that only 40 g of sodium styrene sulfonate of 000 was used until the chlorine content was 35% by weight. The obtained chlorinated product has an average particle size of 2
It was extremely coarse, measuring ~3 mm. 2 parts by weight of tin maleate was added to 100 parts by weight of the chlorinated polyolefin produced in Examples 1 to 3 and Comparative Examples 1 to 3, and the mixture was kneaded for 4 minutes with a roll at 120°C, and a separated sheet was prepared at 160°C and 100 kg/cm ² A sheet with a thickness of 2 mm was produced by pressing for 10 minutes. The above sheet was subjected to various physical property tests shown in Table 1. In Table 1 Hardness: Shore A hardness Thermal stability: The appearance of the sheet after it was left in a gear oven at 190° C. for 45 minutes was shown by color change. ◎No discoloration at all 〇Slight discoloration △Significant discoloration Photostability: Indicated by the presence or absence of cracks on the sheet surface after exposing the sheet to an Atlas Fade-Ometer for 48 hours. ◎No occurrence 〇Slight occurrence △ Occurrence

【table】

[Table] (Effects of the Invention) In the present invention, by using a specific dispersant, a chlorinated polyolefin that is almost equivalent to the raw material polyolefin particles can be obtained without the polymer melting and forming agglomerates during the reaction. Post-treatments such as washing after the reaction can be carried out efficiently. The obtained chlorinated polyolefin also has excellent thermal stability and light stability, and when processed using this chlorinated polyolefin, it significantly improves the kneading properties of the compound and improves the quality of the molded product. can be significantly improved.

Claims (1)

[Claims] 1 When chlorinating a powdered polyolefin having a crystal structure in aqueous suspension, a polymer of acrylic acid or acrylic ester, a copolymer thereof, or an alkali metal salt of these polymers or copolymers is used as a dispersant. or a method for producing a chlorinated polyolefin, which comprises using either an ammonium salt and a styrene polymer containing a sulfonic acid group and having anionic activity, and chlorinating with chlorine gas.