JPH09278806A - Process for suspension polymerization of vinyl chloride monomer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To conduct the suspension polymn. of a vinyl chloride monomer by using a combination of specified dispersing agents to obtain a high productivity of a polymer excellent in antistatic properties and reduced in fisheyes with only a slight adhesion of scales. SOLUTION: 100 pts.wt. vinyl chloride monomer or a monomer mixture thereof with a monomer copolymerizable therewith is suspension-polymerized in an aqueous medium by using a combination of four kinds of dispersing agents, i.e., (A) 0.005 to 0.1 pt.wt. partially saponified polyvinyl alcohol having a degree of saponification of 65 to 85 molar % and an average degree of polymn. of 1000 to 1400, (B) 0.001 to 0.1 pt.wt. partially saponified polyvinyl alcohol having a degree of saponification of 60 to 85 molar % and an average degree of polymn. of 500 to 900, (C) 0.005 to 0.5 pt.wt. partially saponified polyvinyl alcohol having a degree of saponification of 35 to 55 molar % and an average degree of polymn. of 200 to 500, and (D) 0.001 to 0.01 pt.wt. water-soluble cellulose ether in a wt. ratio of A/B of 1/1 to 5/1, a wt. ratio of (A+B)/C of 1/2 to 2/1, and a wt. ratio of D/C of 1/20 to 1/1.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a suspension polymerization method for vinyl chloride-based monomers, and more specifically, to excellent antistatic properties,
The present invention also relates to a suspension polymerization method for vinyl chloride-based monomers, which has less fish eyes and less scale adhesion.

[0002]

2. Description of the Related Art Usually, a vinyl chloride polymer is subjected to suspension polymerization, and then the polymer particles obtained by separating and drying are pneumatically transported and stored or packed as a product. The polymer particles are likely to be charged with static electricity in the drying process and the air transporting process, so that the polymer particles are less likely to drop from the raw material hopper due to charging. In addition, the apparent bulk specific gravity due to charging is reduced, which causes a problem such as a reduction in the discharge amount of the extruder.

As a method for preventing the electrification of such polymer particles, Japanese Patent Laid-Open No. 172419/1994 has disclosed that a vinyl chloride monomer is suspension polymerized in an aqueous medium and then a polyhydric alcohol is added to a slurry. A method for preventing a decrease in bulk specific gravity due to charging by adding is described. Further, in JP-A-2-110109, by adding a water-absorbing synthetic resin when polymerizing a vinyl chloride-based monomer,
A method for producing a resin having excellent antistatic properties is described.

[0004]

However, in the method of adding the drug having the antistatic effect as described above,
A sufficient effect cannot be obtained unless it is evenly attached to the vinyl chloride polymer, and the addition of such a chemical may affect COD and BOD in the wastewater. Recently, it has become difficult to balance the physical properties of the obtained polymer with the enlargement of the polymerization vessel.

An object of the present invention is to provide a method for polymerizing a vinyl chloride polymer which is excellent in antistatic properties, has less fish eyes, and has less scale attached, with high productivity.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above problems, and as a result, there is a method for producing a vinyl chloride polymer by suspension polymerization in an aqueous medium. The inventors have found that a vinyl chloride polymer having excellent properties can be obtained by using a specific combination of partially saponified polyvinyl alcohol and cellulose ether as a dispersant, and have completed the present invention.

That is, according to the present invention, when suspension polymerization of a vinyl chloride monomer or a monomer mixture containing a vinyl chloride-copolymerizable monomer in an aqueous medium is carried out, (A) Ken is used as a dispersant. Degree of conversion 65-85 mol%, average degree of polymerization 1000
~ 1400 partially saponified polyvinyl alcohol, (B)
Saponification degree 60-85 mol%, average degree of polymerization 500-900
Partially saponified polyvinyl alcohol, (C) saponification degree 3
A vinyl chloride monomer or a monomer copolymerizable with vinyl chloride, in which 4 kinds of partially saponified polyvinyl alcohol having 5 to 55 mol% and an average degree of polymerization of 200 to 500 and (D) water-soluble cellulose ether are used in combination. The amount of (A) per 100 parts by weight of the monomer mixture containing 0.005 to 0.1 parts by weight,
The amount of (B) is 0.001 to 0.1 parts by weight, the amount of (C) is 0.005 to 0.5 parts by weight, and the amount of (D) is 0.00.
1 to 0.01 parts by weight, (A) / (B) weight ratio of 1/1 to 5/1, and {(A) + (B)} / (C) weight ratio of 1/2 ~ 2/1, (D) / (C) weight ratio is 1 /
The method is a suspension polymerization method of a vinyl chloride-based monomer, wherein the method is 20 to 1/1. Further, the present invention is characterized in that 10 to 100 ppm of oxygen is present in the polymerization system after charging a monomer mixture containing a vinyl chloride monomer or a monomer copolymerizable with vinyl chloride to perform polymerization. And the suspension polymerization method of a vinyl chloride-based monomer as described above.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of monomers copolymerizable with vinyl chloride used in the present invention include vinyl esters such as vinyl acetate and vinyl propionate, methyl acrylate, ethyl acrylate, methyl methacrylate and Acrylic acid or methacrylic acid ester such as ethyl methacrylate, olefin such as ethylene and propylene,
Examples thereof include vinyl ethers such as lauryl vinyl ether and isobutyl vinyl ether. Further, copolymerizable ones such as maleic anhydride, acrylonitrile, styrene, vinylidene chloride and the like can be mentioned. These can be used alone or in combination of two or more.

Among the four kinds of dispersants (A) to (D) used in the present invention, first, (A) saponification degree is 65 to 8
Partially saponified polyvinyl alcohol having 5 mol% and an average degree of polymerization of 1000 to 1400 (hereinafter referred to as a dispersant (A)).
Preferred are those having a saponification degree of 70 to 80 mol% and an average degree of polymerization of 1000 to 1300, more preferably 75 to 80 mol% and an average degree of polymerization of 1100 to 12.
50 can be mentioned. If the amount out of these ranges is used, the powder fluidity of the polymer is deteriorated due to electrification, the bulk specific gravity is lowered, and the fish eye is deteriorated.

Next, (B) the saponification degree is 60 to 85 mol%,
Partially saponified polyvinyl alcohol having an average degree of polymerization of 500 to 900 (hereinafter, referred to as a dispersant (B)) can be mentioned, preferably saponification degree of 65 to 80 mol%, and average degree of polymerization of 600.
~ 800, more preferably 70-75 saponification degree
Those having a mol% and an average degree of polymerization of 600 to 750 may be mentioned. If it is out of these ranges, the fish eye will be deteriorated.

And (C) a degree of saponification of 35 to 55 mol%,
Partially saponified polyvinyl alcohol having an average degree of polymerization of 200 to 500 (hereinafter referred to as a dispersant (C)) may be mentioned, and preferably, the degree of saponification is 40 to 55 mol% and the average degree of polymerization is 200.
To 400, more preferably a saponification degree of 45 to 55.
Examples thereof include those having a mol% and an average degree of polymerization of 200 to 350. Use outside of these ranges causes deterioration of fish eyes.

Further, (D) known water-soluble cellulose ethers (hereinafter referred to as dispersants (D)) such as methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, hydroxypropoxymethyl cellulose, carboxymethyl cellulose, etc. may be mentioned. Then, hydroxypropoxymethyl cellulose is preferably used.

Amount of the dispersant (A) based on 100 parts by weight of a vinyl chloride monomer or a monomer mixture containing a vinyl chloride copolymerizable monomer (hereinafter referred to as a vinyl chloride monomer mixture). Is 0.005 to 0.1 part by weight, preferably 0.01 to 0.05 part by weight, more preferably 0.02 to
0.04 parts by weight. If it is less than 0.005 part by weight, the bulk specific gravity is lowered by electrification, coarse particles are likely to be generated due to deterioration of dispersion stability of the suspension, and fish eyes are deteriorated. On the other hand, if it exceeds 0.1 parts by weight, charging is prevented, but the particle size becomes fine and the bulk specific gravity decreases.

The amount of the dispersant (B) based on 100 parts by weight of the vinyl chloride monomer mixture is 0.001 to 0.1 part by weight,
The amount is preferably 0.005 to 0.05 parts by weight, more preferably 0.01 to 0.03 parts by weight, and if less than 0.001 parts by weight, coarse particles are generated due to deterioration of dispersion stability of the suspending agent,
Fish eye gets worse. On the other hand, if the amount exceeds 0.1 parts by weight, the adhesion of scale increases and the productivity decreases.

Similarly, the vinyl chloride monomer mixture 100
The amount of the dispersant (C) is 0.005 to 0.5 with respect to parts by weight.
The amount is preferably 0.01 to 0.1 part by weight, more preferably 0.02 to 0.08 part by weight. If the amount is less than 0.005 parts by weight, the fish eyes are deteriorated, and if the amount is more than 0.5 parts by weight, the fish eyes are improved but the bulk specific gravity is lowered.

The amount of the dispersant (D) based on 100 parts by weight of the vinyl chloride monomer mixture is 0.001 to 0.01.
Parts by weight, preferably 0.002 to 0.008 parts by weight, more preferably 0.004 to 0.006 parts by weight.
If it is less than 0.001 part by weight, the dispersion stability of the suspension becomes poor and it becomes difficult to control the particle size. Even if it exceeds 0.01 parts by weight, it becomes difficult to control the particle size, and the number of fine particles increases.

Further, a preferable range of these dispersants (in this paragraph, each dispersant is simply referred to as (A), (B), (C), and (D)) is defined by a weight ratio, and (A) / ( The weight ratio of B) is 1/1 to 5/1, preferably 1/1 to 4/1,
More preferably 1/1 to 1/3, and the weight ratio is 1/1
If it is less than 1, the bulk specific gravity is lowered by charging, and if it exceeds 5/1, the polymer is less likely to be charged but the fish eye is deteriorated. The weight ratio of {(A) + (B)} / (C) is 1/2 to 2/1, preferably 3/4 to 3/2, and more preferably 3/4 to 5/4. If the weight ratio is less than 1/2, the fish eye is improved, but the bulk specific gravity is lowered by charging, and if it exceeds 2/1, the fish eye is deteriorated. Further, the weight ratio of (D) / (C) is 1/20 to 1/1, preferably 1/15 to 1/2, and more preferably 1/15 to 1 /.
5 If the weight ratio is less than 1/20, it is difficult to control the particle size. If it exceeds 1/1, the particle size increases,
It causes an increase in scale.

The above-mentioned dispersants may be added all at once or in portions, and the addition timing is not limited. Further, there is no obstacle to using a conventionally known dispersant in combination with these dispersants.

Examples of the oil-soluble polymerization initiator used in the present invention include diisopropyl peroxydicarbonate, dioctyl peroxydicarbonate, dilauryl peroxydicarbonate, dimyristyl peroxydicarbonate and dicetyl peroxydicarbonate. Carbonate, ditertiarybutyl peroxydicarbonate, di (ethoxyethyl) peroxydicarbonate, di (methoxyisopropyl) peroxydicarbonate, di (3methoxybutyl) peroxydicarbonate, di (3methoxy3methylbutyl) peroxy Dicarbonate, di (butoxyethyl) peroxydicarbonate,
Di (2 isopropoxyethyl) peroxydicarbonate, di (2ethylhexyl) peroxydicarbonate, di (2isopropoxyethyl) peroxydicarbonate, dibenzylperoxydicarbonate, dicyclohexylperoxydicarbonate, ditertiary butyl Percarbonate initiators such as cyclohexyl peroxy dicarbonate, tertiary butyl peroxy neodecanoate, tertiary hexyl peroxy neodecanoate, amyl peroxy neodecanoate,
Tertiary octyl peroxy neodecaneate, α-
Cumyl peroxyneodecanate, 1-cyclohexyl-1-methylethyl peroxyneodecanate, tert-butyl peroxypivalate, amyl peroxypivalate, tertiary octyl peroxypivalate, tertiary hexyl peroxypivalate , Α-
Cumyl peroxypivalate, perhexyl oxalate, ditertiary butyl peroxy oxalate, acetylcyclohexylsulfonyl peroxide,
1.1.3.3. Perester initiators such as tetramethylbutylperoxyphenoxyacetate, lauroyl peroxide, diisobutyl peroxide, 2ethylhexanoyl peroxide, 3.5.5 diacyl peroxide initiators such as trimethylhexanoyl peroxide, 2 .2 'azobisisobutyronitrile,
2.2 'azobis-2.4 dimethylvaleronitrile,
2.2 Azo-based initiators such as 2 'azobis-4methoxy-2.4 dimethylvaleronitrile; water-soluble peroxides such as potassium persulfate and ammonium persulfate; 2.2'-azobis (2-amidinopropane) hydrochloride 2.
Water-soluble azo compounds such as 2'-azobis (NN'-dimethyleneisobutylamidine) hydrochloride and the like are mentioned. In order to make the polymerization reaction rate uniform, a polymerization initiator having a different half-life of 10 hours is used. It may be used in combination of more than one kind. These polymerization initiators may be used as they are, may be used as a water emulsion or a water suspension, or may be used after being dissolved in a solvent such as toluene.

In the present invention, the amount of oxygen present in the polymerization system after charging the vinyl chloride monomer mixture is 10 to 100 ppm with respect to the weight of the vinyl chloride monomer mixture,
Preferably 15 to 80 ppm, more preferably 20 to 6
It is 0 ppm. The oxygen amount here is controlled in consideration of the oxygen content in the vinyl chloride-based monomer mixture and water, and when the oxygen amount is small, it is preferable to add air. . When the amount of oxygen is less than 10 ppm, the bulk specific gravity of the polymer is lowered and the particles are coarsened. Also, 10
When it exceeds 0 ppm, the thermal stability of the polymer is deteriorated.

The polymerization time in the present invention is preferably 2 to 8 hours. If the polymerization time is less than 2 hours, it is necessary to increase the amount of the oil-soluble polymerization initiator to carry out the polymerization. In that case, the control of the polymerization temperature becomes unstable due to the generation of heat value exceeding the heat removal capacity of the polymerization vessel. There is. Further, the hue of the polymer tends to be deteriorated as the amount of the oil-soluble polymerization initiator is increased, and if it exceeds 8 hours, it is not preferable from the viewpoint of productivity improvement. In the present invention, the polymerization time means the time from when the internal temperature of the polymerization vessel is started to be raised until the reaction is stopped.

The suspension polymerization method of the vinyl chloride monomer mixture in the present invention is carried out by a conventionally known suspension polymerization method,
Additives such as an antioxidant and a chain transfer agent may be added as needed, and the amount of addition, the order of charging to the polymerization vessel, and the like are not particularly limited. The polymerization temperature is set according to the type of oil-soluble polymerization initiator used, but is usually 40
~ 70 ° C.

[0023]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The physical properties of the vinyl chloride polymer were measured by the following methods.

[Evaluation of Charging Properties] (1) Measurement of Bulk Specific Gravity: The bulk specific gravity of the polymer is measured according to JIS-K672.
It measured according to 1. Further, in order to examine the change in powder fluidity due to charging, the bulk specific gravity was measured by the same method as above after stirring for 20 seconds with a glass mixer. At this time, it is determined that the smaller the change in bulk specific gravity, the smaller the effect of charging. (2) Drop time measurement: 70 g of the powder dropped from the hopper of the bulk specific gravity measuring device according to JIS-K6721 was measured. In addition, stirring was performed for 20 seconds in the same manner as in the measurement of the bulk specific gravity, and then the dropping time was measured. At this time, it is determined that the smaller the change in the drop time is, the less the influence of charging is.

[Measurement of physical properties] (3) Average particle size: JIS standard 60, 80, 100, 1
Sieve analysis using wire mesh of 50, 200, 270 mesh
Thus, the 50% passing diameter was defined as the average particle diameter. (4) Fish eye: diameter 8 after mixing the following ingredients well
Inch, rotation speed 15 / 21rpm 2 rolls 145
Heat to ℃ and knead for 5 minutes.
Take out the sheet. Then in the area of 15 × 10 cm
The number of existing fish eyes was counted. (Resin: 100
g, plasticizer DOP: 50 g, Cd-Ba based stabilizer: 3
g, carbon black made by Dainichiseika Co., Ltd .: 1 g) (5) Thermal stability measurement:
After kneading with a ℃ roll for 10 minutes, 176 ℃ for 30 minutes
Pressed into a sheet, this sheet is 1mm^ThreeBelow
Cut into 2 pieces, put into a test tube, and then Congo Red
Attach the test paper to the top of the test tube and heat it in an oil bath at 180 ℃
Then, the time for the test paper to change color was measured. (Resin: 100
Parts by weight, DOP: 50 parts by weight, lead-based stabilizer: 0.5 parts by weight
Parts, barium-based stabilizer: 1 part by weight) (6) Scale adherence state: Visual observation inside the polymerization vessel after polymerization
The following expression was used. (○: Almost no adhesion
Yes, △: Partially adhered, ×: Entirely adhered) (7) Productivity: In batch polymerization cycle time,
Miscellaneous time other than polymerization time (raw material charging time, slurry discharge
(Interval, etc.) for 2.5 hours, the inner volume of the polymerization vessel is 1 m ^ThreeOf 1
PVC production amount per month is t / m^Three・ Indicated as the month
Was.

Example 1 In a polymerization vessel having an internal volume of 120 m ³ equipped with a Faudler blade,
42 t of water and (A) saponification degree of 77 mol% as a dispersant,
0.035 parts of partially saponified polyvinyl alcohol having an average degree of polymerization of 1200 (weight per 100 parts of vinyl chloride monomer, the same applies hereinafter), (B) saponification degree of 73 mol%, partially saponified polyvinyl alcohol having an average degree of polymerization of 800 0 .025
Parts, (C) saponification degree 48 mol%, partially saponified polyvinyl alcohol having an average degree of polymerization of 300 0.06 parts, (D) methoxy group substitution degree 28% by weight, hydroxypropoxyl group substitution degree 10% by weight hydroxypropoxy 0.005 parts of methyl cellulose was charged. After removing the internal air from the degassing line with a vacuum pump, 35 t of vinyl chloride monomer was charged while stirring the polymerization vessel. 1-cyclohexyl-1-methylethyl peroxyneodecanate 0.03
5 parts and 0.03 part of cumyl peroxy neodecanoate were added, and the temperature in the polymerization vessel was set to 50.5 ° C. to carry out polymerization. When the internal pressure reached 6.0 kg / cm ² -G, the reaction was stopped, unreacted vinyl chloride monomer was recovered, and then the slurry was dehydrated and dried to obtain a vinyl chloride polymer. The polymerization time was 4.5 hours. When the amount of oxygen in the polymerization system after charging the vinyl chloride monomer was measured, 65 ppm of oxygen was present based on the weight of the vinyl chloride monomer. The obtained vinyl chloride polymer had small changes in bulk specific gravity and dropping time before and after mixing, and showed little deterioration in powder fluidity. The results are shown in Table 1.

Examples 2 to 4 Polymerization was carried out under the same conditions as in Example 1 except that the combination of dispersants, the amount of dispersant and the amount of oxygen shown in Table 1 were changed. The results are shown in Table 1.

Examples 5 to 8 Polymerization was carried out under the same conditions as in Example 1 except that the combination of dispersants, the amount of dispersant and the amount of oxygen shown in Table 2 were changed. Table 2 shows the results.

[0029]

[Table 1]

[0030]

[Table 2] Comparative Example 1 As a dispersant, (A) saponification degree 77 mol%, average degree of polymerization 1
Polymerization was carried out under the same conditions as in Example 1 except that the combination of dispersants, the amount of dispersant and the amount of oxygen shown in Table 3 were changed without using 200 partially saponified polyvinyl alcohol. The charging of the polymer made it impossible to measure the bulk specific gravity and the drop time after mixing. The results are shown in Table 3.

Comparative Example 2 As a dispersant, (B) a saponification degree of 73 mol% and an average degree of polymerization of 8
Polymerization was carried out under the same conditions as in Example 1 except that the combination of dispersants, the amount of dispersant and the amount of oxygen shown in Table 3 were changed without using the partially saponified polyvinyl alcohol of No. 00. I have more fish eyes. The results are shown in Table 3.

Comparative Example 3 As a dispersant, (C) saponification degree 48 mol%, average degree of polymerization 3
Polymerization was carried out under the same conditions as in Example 1 except that the combination of dispersants, the amount of dispersant and the amount of oxygen shown in Table 3 were changed without using the partially saponified polyvinyl alcohol of No. 00. I have more fish eyes. The results are shown in Table 3.

Comparative Example 4 The combination of the dispersants shown in Table 3 and the dispersant shown in Table 3 were used without using (D) hydroxypropoxymethylcellulose having a methoxy group substitution degree of 28% by weight and a hydroxypropoxyl group substitution degree of 10% by weight. Polymerization was carried out under the same conditions as in Example 1 except that the amount and the amount of oxygen were changed. The average particle size was increased and fish eyes were increased. Further, the scale adhesion after the polymerization was increased, and the productivity was lowered due to the necessity of work for removing it. The results are shown in Table 3.

[0034]

[Table 3] Comparative Example 5 Polymerization was carried out under the same conditions as in Example 1 except that the combination of dispersants, the amount of dispersant, and the amount of oxygen shown in Table 4 were changed. Changes in bulk specific gravity and drop time before and after mixing both increased, the polymer was charged, and powder fluidity decreased.
The results are shown in Table 4.

Comparative Example 6 Polymerization was carried out under the same conditions as in Example 1 except that the combination of dispersants, the amount of dispersant and the amount of oxygen shown in Table 4 were changed. The average particle size became large and fish eyes increased. The results are shown in Table 4.

Comparative Example 7 Polymerization was carried out under the same conditions as in Example 1 except that the combination of dispersants, the amount of dispersant and the amount of oxygen shown in Table 4 were changed. The average particle size became large and fish eyes increased. The results are shown in Table 4.

Comparative Example 8 Polymerization was carried out under the same conditions as in Example 1 except that the combination of dispersants, the amount of dispersant and the amount of oxygen shown in Table 4 were changed. The thermal stability has deteriorated. The results are shown in Table 4.

[0038]

[Table 4]

[0039]

EFFECTS OF THE INVENTION According to the present invention, a vinyl chloride polymer having excellent antistatic properties, less fish eyes, and less scale attached can be polymerized with high productivity, which is industrially advantageous. Is.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Hideaki Takahara, 1-6 Takasago, Takaishi, Osaka Prefecture Mitsui Toatsu Kagaku Co., Ltd. (72) Inventor, Yasuyuki Hatakeyama, 1-6 Takasago, Takaishi, Osaka Mitsui Toatsu Kagaku Within the corporation

Claims (2)

[Claims] 1. A saponification degree of (A) of 65 as a dispersant when suspension-polymerizing a vinyl chloride monomer or a monomer mixture containing a vinyl chloride-copolymerizable monomer in an aqueous medium. ~ 8
5 mol%, partially saponified polyvinyl alcohol having an average degree of polymerization of 1000 to 1400, (B) saponification degree of 60 to 85 mol%, partially saponified polyvinyl alcohol having an average degree of polymerization of 500 to 900, and (C) saponification degree of 35. 55 mol%, partially saponified polyvinyl alcohol having an average degree of polymerization of 200 to 500, and (D) water-soluble cellulose ether are used in combination.
The amount of (A) is 0.005 to 0.1 part by weight, and the amount of (B) is 100 parts by weight per 100 parts by weight of a monomer mixture containing the vinyl chloride monomer or a monomer copolymerizable with vinyl chloride. 0.00
1 to 0.1 parts by weight, the amount of (C) is 0.005 to 0.5 parts by weight, the amount of (D) is 0.001 to 0.01 parts by weight, and (A) / (B) The weight ratio of 1/1 to 5/1,
The weight ratio of {(A) + (B)} / (C) is 1/2 to 2 /
1. The method for suspension polymerization of vinyl chloride-based monomers, wherein the weight ratio of (D) / (C) is 1/20 to 1/1. 2. Polymerization is carried out in the presence of 10 to 100 ppm of oxygen in the polymerization system after charging a monomer mixture containing a vinyl chloride monomer or a monomer copolymerizable with vinyl chloride. The method for suspension polymerization of a vinyl chloride monomer according to claim 1.