JP3385643B2 - Method for producing vinyl chloride polymer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a composition for producing a vinyl chloride polymer, and in particular, it is possible to obtain a molded article which is excellent in thermal stability, has less fish eyes, and is substantially non-toxic. The present invention relates to a method for producing a vinyl chloride polymer and a composition for the vinyl chloride polymer obtained by the method.

[0002]

2. Description of the Related Art Vinyl chloride polymers (hereinafter referred to as PVC) have been used in various fields because of their excellent physical and mechanical properties.

PVC is used in combination with various stabilizers for the purpose of suppressing decomposition during molding and processing. Typical stabilizers such as composite metal soap stabilizers and organotin stabilizers are food products. Suitable for applications that require no toxicity such as packaging materials, medical instruments, and pharmaceutical packaging materials, or applications that require strict regulation of lead elution such as water pipes and fittings and that are substantially non-toxic. Used for. However, in any of the applications, there is a tendency to reduce the amount of the stabilizer containing a metal component used from the viewpoint of hygiene, which inevitably lowers the thermal stability of the PVC composition.
Therefore, in that case, a compound for promoting the effect of the stabilizer (hereinafter referred to as a stabilizing aid) may be added to the PVC composition. As such a stabilizing aid, a polyol and / or an ester thereof, Phosphite compounds, epoxy compounds, sulfur-containing compounds, sterically hindered phenols and the like have been conventionally known, and are used in the compounding and kneading steps prior to PVC production or processing.

Polyvinyl alcohol (hereinafter referred to as PVA) known as a general dispersion stabilizer for suspension polymerization of PVC.
Is described as being classified into the above-mentioned polyols and having an effect as a stabilizing aid, Polymer Papers, Vol. 47, N
o. 6, pp. 509 (June, 1990) and the like.

However, when PVA is used for the purpose of improving the thermal stability of PVC and is used in the mixing and kneading steps, PVA having a high saponification degree (particularly,
With PVA having a saponification degree of 70 mol% or more, PVA and PV
As a result of poor compatibility with C, the transparency of the molded product is reduced, and mechanical strength is reduced due to poor dispersion. When PVA having a low degree of saponification is used, PVA must be used in a large amount because of its poor ability as a stabilizing aid, resulting in a decrease in transparency and a decrease in mechanical strength. There was a problem of doing.

Furthermore, when PVA is used as a dispersion stabilizer at the start of suspension polymerization of PVC, the vinyl chloride monomer is graft-polymerized with PVA, resulting in improved compatibility with PVC and a decrease in transparency. , The deterioration of strength due to poor dispersion does not occur, but a large amount of PVA is required for better thermal stability.
When PVC is used, the dispersion stability of the vinyl chloride monomer decreases and PVC is not obtained, or the obtained PVC is
Another problem is that a satisfactory composition cannot be obtained from such a polymer due to a decrease in plasticizer absorbability, an increase in fish eyes, or an increase in vinyl chloride monomer remaining in PVC.

[0007]

DISCLOSURE OF THE INVENTION The object of the present invention is to provide a method for producing PVC having high heat stability and plasticizer absorbability and good fish eye characteristics, and a composition of PVC obtained by the method. To provide.

[0008]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that in a method for producing PVC by suspension polymerization in an aqueous medium, a specific PVA and cellulose are used. It has been found that PVC having good properties can be obtained by using the combination of the above as a dispersion stabilizer, and that the obtained polymer is mixed with a complex soap stabilizer and / or an organotin stabilizer. The present invention has been completed by finding that a composition having good characteristics can be obtained.

That is, the present invention provides a method for producing PVC by suspension polymerization of a vinyl chloride-based monomer in an aqueous medium in the presence of an oil-soluble initiator and a dispersion stabilizer. A) PVA having a saponification degree of 70 to 90 mol% and an average degree of polymerization of 1500 to 3000, and (B) a saponification degree of 7
P of 0 to 90 mol% and an average degree of polymerization of 300 to 1000
VA, (C) secondary dispersion stabilizer and (D) water-soluble cellulose ether are used in combination (provided that (A) saponification degree is 70-9).
PVA with 0 mol% and average degree of polymerization of 1500-3000
Excluding addition at a polymerization conversion rate of 5 to 60%. ) Is carried out, it is a manufacturing method of PVC. Hereinafter, the present invention will be described in detail. In the present invention, the dispersion stabilizer (A),
Two types of PVA having a specific degree of saponification and an average degree of polymerization as (B), a secondary dispersant as the dispersion stabilizer (C), and a water-soluble cellulose ether as the dispersion stabilizer (D) in an aqueous medium. Suspension polymerization of vinyl chloride monomer with P
VC is produced, and the amount of the dispersion stabilizer used is 0.01 to 0.5 parts by weight of the dispersion stabilizer (A) and 100 parts by weight of the vinyl chloride-based monomer. Is 0.0
It is preferable that the amount of the component (5) is 5 to 1 part by weight, and the amount of (D) is 0.01 to 0.5 part by weight.

As the secondary dispersant (C) used in the present invention, oil-soluble PVA or a surfactant having a saponification degree of 20 to 70 mol% and an average degree of polymerization of 100 to 1000 should be used. You can

When oil-soluble PVA is used as the secondary dispersant, the amount of the secondary dispersant used is preferably 0.005 to 0.1 part by weight based on 100 parts by weight of the vinyl chloride monomer. The total amount of the dispersion stabilizers (A) to (C) used is preferably 0.1 parts by weight or more and 1.6 parts by weight or less, more preferably 100 parts by weight of the vinyl chloride monomer. The range is 0.1 part by weight or more and 0.3 part by weight or less. The total amount of dispersion stabilizers (A) to (C) used is 0.1.
If it is less than 1.6 parts by weight, a sufficient effect of improving thermal stability may not be obtained, and if it is more than 1.6 parts by weight, the transparency of the final molded product may be deteriorated, or fish eyes and residual monomers may be inferior in weight. Sometimes you can only get coalesced.

When oil-soluble PVA is used as the secondary dispersant, the dispersion stabilizers (A), (B), (C),
The amount of (D) used depends on the weight ratio of each amount.
Its preferable range is defined, and among these, (A) :( B)
The use amount ratio (weight ratio) of 1: 2 to 1:15, (B):
The amount ratio (weight ratio) of (C) is preferably 5: 1 to 20: 1. If the amount of (B) is less than twice the amount of (A), the fish eyes, the plasticizer absorption amount, and the residual vinyl chloride monomer level of the resulting PVC may be inferior.
If the amount is more than twice the amount, the dispersion stability of the vinyl chloride monomer may be poor, and polymer particles may not be obtained, or the obtained particles may become coarse. Also, (C) is (B)
If the amount is more than 1/5 of the above amount, foaming may occur in the steps of recovering unreacted vinyl chloride monomer, removing unreacted vinyl chloride, etc. If the amount is less than the above range, only a polymer having poor fish eye, plasticizer absorbability and residual monomer level may be obtained.

On the other hand, the surfactant used when the surfactant is used as the secondary dispersion stabilizer (C) may be a nonionic surfactant, a cationic surfactant or an anionic surfactant. Alkyl ester, alkyl ether of polyoxyethylene, allyl ether of polyoxyethylene, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, block copolymer of polyoxyethylene and polyoxypropylene, glycerin fatty acid ester, polysiloxane polyoxy Nonionic surfactants such as alkylene block copolymers and polyoxyethylene alkylamines; cations such as aromatic ammonium salts, alkylamine salts, quaternary ammonium salts and alkylimidazoline quaternary salts There are anionic surfactants such as alkyl sulfonates, alkyl allyl sulfonates, alkyl phosphates, polyoxyethylene alkyl phosphates, polyoxyethylene alkyl allyl sulfonates, etc. They can be used together or in combination of two or more. Of these, the surfactant preferably has a hydrophilic-hydrophobic balance of 15 or less. If it exceeds 15, only particles having poor fish eyes, plasticizer absorption, and residual monomer level may be obtained. . The preferred amount of the surfactant used is 0.05 to 2.0 parts by weight. If the amount is less than 0.05 parts, the amount of fisheye, the amount of plasticizer absorbed, and the residual monomer level are insufficient, and the amount is 2.0 parts by weight. If the amount exceeds the above range, the resulting PVC particles may contain many fine particles, which may make it difficult to handle the powder and may reduce the transparency. Further, the dispersion stabilizer (A) used at this time
The total amount of (B) used is preferably 0.1 parts by weight or more and 1.5 parts by weight or less, more preferably 0.1 parts by weight or more and 0 parts by weight, based on 100 parts by weight of the vinyl chloride-based monomer. If the amount is less than 0.1 part by weight, a sufficient heat stability improving effect may not be obtained, and if it is more than 1.5 parts by weight, the transparency of the final molded product may be insufficient. Or
The polymer may have a poor fisheye and residual monomer level.

The dispersion stabilizer (D) is a water-soluble cellulose ether, and any known water-soluble cellulose ether such as methyl cellulose or hydroxypropyl cellulose can be used, but hydroxypropyl methyl cellulose is preferably used. Further, the degree of hydroxypropoxyl group substitution is 0.1 per 1 glucose unit.
5 to 0.25, and the degree of methoxyl group substitution is 1.
It is desirable to use 4- to 1.9 hydroxypropylmethylcellulose.

The preferred amount of the water-soluble cellulose ether (D) used is (A) in a weight ratio with the dispersion stabilizer (A):
(D) is 1: 1 to 5: 1. If the amount is more than the same amount as in (A), the resulting polymer particles will contain many fine particles, which may make it difficult to handle the powder.
When the amount is less than the double amount, the dispersion stability of the vinyl chloride monomer is poor and polymer particles cannot be obtained, or the obtained particles tend to be coarse.

The above dispersion stabilizer may be used by adding the entire amount thereof to the polymerization system before the initiation of the polymerization, and may be added in a divided or continuous manner after the initiation of the polymerization and before the termination of the polymerization. May be used (provided that (A) saponification degree is
70-90 mol% and average degree of polymerization of 1500-3000
Excluding the addition of PVA at a polymerization conversion rate of 5 to 60%. ) .
Further, it may be added and used before the dehydration of the slurry after the termination of the polymerization, but it is preferably added and used all at once before the start of the polymerization.

Further, in the production method of the present invention, a compound having a mercapto group and a hydroxyl group and / or a carboxyl group may be used as a molecular weight modifier in suspension polymerization in addition to the above dispersion stabilizer. Examples of the molecular weight regulator include 2-mercaptoethanol, 3-mercaptopropanol, 4-mercaptobutanol, thioglycerin, thiopropylene glycol and thioacetic acid, but 2-mercaptoethanol is preferably used.

The vinyl chloride-based monomer to be polymerized by the method of the present invention includes vinyl chloride alone and a monomer mixture mainly containing vinyl chloride (50% by weight or more of vinyl chloride). Examples of the monomer copolymerizable with vinyl chloride to be used for vinyl acetate, vinyl ester such as vinyl propionate, acrylic ester or methacrylic ester such as methyl acrylate and ethyl acrylate, olefin such as ethylene and propylene , Maleic anhydride, acrylonitrile, styrene, vinylidene chloride and the like.

As the oil-soluble polymerization initiator used in the present invention, diisopropyl peroxydicarbonate,
Percarbonate compounds such as di-2-ethylhexyl peroxydicarbonate and diethoxyethyl peroxydicarbonate; t-butyl peroxy neodecaneate, α-cumylperoxy neodecaneate, t-butyl peroxyneodecanate, etc. Perester compounds such as acetylcyclohexyl sulfonyl peroxide: Azo compounds such as azobis-2.4-dimethylvaleronitrile and azobis- (4-methoxy-2,4-dimethylvaleroneto); There are hydrogen oxides,
These may be used alone or in combination of two or more.

The method for producing PVC of the present invention is not particularly limited, and it is carried out under the conditions of known suspension polymerization. For example, the amount of the aqueous medium, the amount of the polymerization initiator, the polymerization temperature, and the like used per monomer may be in the range conventionally used. Also, if necessary, known protective colloids, pH adjusters and the like may be used as long as they do not affect the effects of the present invention.

As described above, PVC obtained by the method of the present invention
Since it has a high thermal stability in itself, the composition of the present invention in which this PVC is mixed with a complex metal soap-based stabilizer and / or an organotin-based stabilizer can be used without using a large amount of a stabilizer. The composition has the thermal stability required during processing.

The type of the composite metal soap-based stabilizer used as the stabilizer in the present invention may be a combination of an organic acid salt of zinc and an organic acid salt of an alkali metal and / or an alkaline earth metal. Examples of the alkaline earth metal and / or lithium, sodium, potassium, magnesium, calcium, and the like,
Of these, a combination of calcium and zinc is preferable. Examples of the organic acid include, but are not limited to, carboxylic acids such as formic acid, acetic acid, propionic acid, caprylic acid, lauric acid, palmitic acid, and stearic acid. The amount of the composite metal soap-based stabilizer used is preferably 0.5 to 5 parts by weight, and more preferably 1 to 3 parts by weight, per 100 parts by weight of the vinyl chloride polymer. If it is less than 0.5 part by weight, the thermal stability of the composition may be insufficient, and the resulting molded article may be colored. If it exceeds 5 parts by weight, thermal stability commensurate with the amount added is not expected and it is not practical.

On the other hand, the type of the organotin stabilizer is the usual P
An organotin stabilizer for VC is used and is not particularly limited, but when nontoxic or low toxicity is desired, di-
Octyltin mercaptide system represented by n-octyltin-S, S'-bis (isooctylmercaptoacetate); di-n-octyltin-S, S'-bis (isooctylmaleate), n-octyltin Examples thereof include, but are not limited to, octyltin malate-based typified by a maleate polymer, or an organic tin-based stabilizer mainly containing octyltin mercaptide and / or octyltin malate. The amount of the organotin stabilizer used is 0.5 to 5 per 100 parts by weight of the vinyl chloride polymer.
The amount is preferably 1 part by weight, more preferably 1 to 3 parts by weight. If it is less than 0.5 part by weight, the thermal stability of the composition may be insufficient, and the resulting molded article may be colored. When it exceeds 5 parts by weight, thermal stability commensurate with the amount used is not expected and it is not practical.

Further, phosphites, epoxy compounds, polyols such as dipentaerythritol and derivatives thereof, antioxidants, zeolites, perchlorates, β-diketones, keto acid esters, β-aminocrotonic acid esters and the like are included. Stabilization aids such as nitrogen compounds, sulfur-containing compounds such as thiol carboxylic acid anhydrides, and usual additions of processing aids, plasticizers, lubricants, pigments, fillers, light stabilizers such as sterically hindered amines and salicylates. The combined use of the agent and the resin other than the vinyl chloride-based resin may be within a range not affecting the effects of the present invention.

[0025]

EXAMPLES The production method and composition of the present invention will be described below based on Examples and Comparative Examples, but the present invention is not limited thereto.

The following physical properties were measured by the following methods.

(Amount of plasticizer absorbed) German Industrial Standard (DI
N) From 53417/1.

(Thermal stability) Using a Brabender Plastograph tester, 60 g of the following composition was charged at a mixer rotation speed of 60 rpm, and the torque decreased from the time (a) when the maximum torque was reached. After a lapse of a state in which a constant torque was exhibited, the time until the point (b) at which the torque started to rise again due to the decomposition of the resin was taken as the thermal decomposition time. Pyrolysis time (HDT, minutes) = (b)-(a) The chamber temperature was 160 ° C. in the formulation 1 and 190 ° C. in the formulation 2.

(Preparation of Composition) <Compound 1> Vinyl chloride resin 100 parts by weight Dioctyl phthalate 3 parts by weight Epoxidized soybean oil 3 parts by weight Stearic acid 0.2 parts by weight Ca-Zn complex metal soap-based stabilizer 2 Parts by weight <Compound 2> Vinyl chloride resin 100 parts by weight Dioctyl phthalate 5 parts by weight Acrylic processing aid 5 parts by weight Butyl stearate 0.5 parts by weight Montanoic acid wax 0.3 parts by weight Organotin stabilizer 3 parts by weight (N-2000E / Nitto Kasei) After measuring the above, use an Ishikawa type stirring and crushing machine to 120 ° C.
Mix for 10 minutes to obtain the composition.

(Fish Eye) Vinyl Chloride Polymer 1
After mixing 00 parts by weight, 40 parts by weight of di-2 ethylhexyl phthalate, 3 parts by weight of a stabilizer, and a small amount of ultramarine blue, 1
The number of FEs per 50 cm ^{2 of the} sheet obtained by kneading with a roll at 60 ° C. for 5, 7, and 9 minutes was counted.

Example 1 450 kg of deionized water, 400 kg of vinyl chloride monomer, and Table 1 were placed in a stainless steel polymerization container having an internal volume of 1 cubic meter.
The type and amount of the dispersant shown in the above are charged as an aqueous solution or a mixed solution of methyl alcohol and water, and as an initiator, t
Using 0.04 parts by weight of -butylperoxypivalate, the reaction was carried out at a temperature of 65 ° C. and 2-mercaptoethanol as a chain transfer agent to a conversion rate of 85%. The water-soluble cellulose ether had a hydroxypropoxyl group substitution degree of 0.25 and a methoxyl group substitution degree of 1.9, and the viscosity of a 2% by weight aqueous solution at 20 ° C. was 50 cps. Hydroxypropyl methylcellulose (HPMC) was used.

After the polymerization, the unreacted vinyl chloride monomer is recovered, the system is evacuated and replaced with nitrogen, and the vinyl chloride polymer slurry is taken out and dehydrated and dried to obtain a polymer. The analysis was carried out according to the method described in 1 above, and a part of the compositions of Formula 1 and Formula 2 were prepared according to the above-mentioned method and evaluated.

Example 2 A polymer and a composition were obtained in the same manner as in Example 1 except that the amount of PVA (A) used was increased to 0.05 parts by weight.

Examples 3 to 5 The amount of PVA (C) used was increased to 0.02 parts by weight, or hydroxypropylmethyl cellulose (H in Table 1 was used).
PMC) was increased to 0.05 parts by weight, or PVA (A) was 0.03 parts by weight and PVA (B) was 0.15 parts by weight. A coalescence and composition was obtained.

Example 6 A polymer and a composition were obtained in the same manner as in Example 2 except that the amount of PVA (C) used was reduced to 0.005 parts by weight.

Example 7 The same procedure as in Example 1 was carried out except that 0.2 parts by weight of polyoxyethylene sorbitan monostearate as a surfactant was used as the secondary dispersant instead of PVA (C). A coalescence and composition was obtained.

Example 8 Except that the type of PVA (A) was changed to the type shown in Table 1,
A polymer and a composition were obtained in the same manner as in Example 1.

Example 9 Except that the type of PVA (B) was changed to the type shown in Table 1,
The same procedure as in Example 8 was carried out to obtain a polymer and a composition.

Example 10 Except that the type of PVA (C) was changed to the type shown in Table 1,
A polymer and a composition were obtained in the same manner as in Example 9.

Comparative Examples 1 to 4 PVA (A) to (B), secondary dispersant (C) or HPM
The same procedure as in Example 1 was performed without using any one of C (D).

The dispersant formulations of Examples and Comparative Examples are shown in Table 1, and the measurement results of Examples and Comparative Examples are shown in Table 2.

[0042]

[Table 1]

[0043]

[Table 2]

In Comparative Examples 1 and 4, blocks were formed and polymer particles could not be obtained. In Comparative Example 2, the composition prepared from the obtained polymer was inferior in thermal stability and fisheye characteristics. In Comparative Example 3, the obtained polymer was a polymer having poor plasticizer absorption and fish eye characteristics. In Examples 1 to 10, the polymers and compositions were excellent in thermal stability, fisheye characteristics, and plasticizer absorption without various problems as seen in Comparative Examples.

[0045]

As described above, the PVC obtained by the method of the present invention has excellent properties, and the composition of the present invention using this PVC has excellent thermal stability. From the product, it is possible to obtain a molded product having little fish eyes and being substantially non-toxic.

Front page continuation (51) Int.Cl. ⁷ identification code FI C08L 27/06 C08L 27/06 (58) Fields investigated (Int.Cl. ⁷ , DB name) C08F 2/00-2/60

Claims (6)

(57) [Claims] 1. A mixture of vinyl chloride or a monomer copolymerizable with vinyl chloride (hereinafter referred to as vinyl chloride monomer).
In the presence of an oil-soluble polymerization initiator and a dispersion stabilizer in the aqueous medium for suspension polymerization to produce a vinyl chloride polymer, wherein the dispersion stabilizer (A) has a saponification degree of 70-
90 mol% and partially saponified polyvinyl alcohol (hereinafter referred to as PVA) having an average degree of polymerization of 1500 to 3000,
(B) Saponification degree is 70 to 90 mol% and average degree of polymerization is 3
0 to 1000 PVA, (C) secondary dispersant and (D)
Water-soluble cellulose ether used in combination (however, (A) Ken
Degree of conversion is 70 to 90 mol% and average degree of polymerization is 1500 to 3
000 PVA at a conversion of 5 to 60% is excluded.
Ku. ) The method for producing a vinyl chloride polymer characterized by the following. 2. The amount of the dispersion stabilizer (A) used is 0.01 to 0.5 per 100 parts by weight of the vinyl chloride-based monomer.
Parts by weight, the amount of (B) used is 0.05 to 1 parts by weight, (D)
The method for producing a vinyl chloride-based polymer according to claim 1, wherein the amount used is 0.01 to 0.5 part by weight. 3. The secondary dispersion stabilizer (C) has a saponification degree of 20.
Is 70 to 70 mol% and the average degree of polymerization is 100 to 1000, and it is 0.005 to 0.1 part by weight based on 100 parts by weight of the vinyl chloride monomer. The method for producing a vinyl chloride polymer according to claim 1 or 2, which is characterized in that. 4. The amount ratio (weight ratio) of the dispersion stabilizer (B) :( C) is 5: 1 to 20: 1, and the amount ratio (weight ratio) of (A) :( B) is used. 1: 2 to 1:15, and the amount ratio (weight ratio) of (A) :( D) is 1: 1 to 5: 1.
The method for producing a vinyl chloride polymer according to claim 3, wherein 5. The process for producing a vinyl chloride polymer according to any one of claims 1-4, characterized by using a compound having a mercapto group and a hydroxyl group and / or a carboxyl group as a molecular weight modifier. 6. A vinyl chloride resin composition obtained by mixing a vinyl chloride polymer with a composite metal soap stabilizer and / or an organic tin stabilizer, wherein the vinyl chloride polymer is a vinyl chloride polymer. A vinyl chloride resin composition, which is a vinyl chloride polymer obtained by the method according to any one of 1 to 5 .