JPH0391512A - Production of vinyl chloride copolymer - Google Patents

Abstract

PURPOSE:To obtain the title copolymer low in a comonomer content and excellent in gelation properties, meltability, etc., by performing the emulsion copolymerization or fine suspension copolymerization of a vinyl chloride monomer and a monomer copolymerizable therewith having a copolymerization reactivity ratio >=1 under specified conditions. CONSTITUTION:A process for performing the emulsion copolymerization or fine suspension copolymerization of a vinyl chloride monomer (M1) and a monomer (M2) copolymerizable therewith, wherein the monomer M2 has a copolymerization reactivity ratio gamma2>=1, the addition of this monomer to the reaction system is performed intermittently or continuously, and this operation is started after the monomer conversion reaches 50% and is completed before the reaction is completed. According to the above process, the title copolymer which is relatively low in a comonomer content and therefore has good heat resistance and is nonsticky, and excels in gelation properties, meltability, etc., can be obtained.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing a vinyl chloride copolymer with improved gelling and melting properties. [Prior art 1] The vinyl chloride copolymer for paste, which is made into plastisol or orga/sol, is a mixture of vinyl chloride monomer and a monomer copolymerizable therewith (hereinafter referred to as vinyl chloride monomer mixture). ) is emulsion polymerized using a water-soluble polymerization initiator, or an oil-soluble polymerization initiator that is dissolved in a vinyl chloride monomer mixture is added, and this is mechanically dispersed uniformly and finely in water. It is produced by a slight SMS turbidity polymerization method in which polymerization is carried out after homogenization (homogenization treatment), but these methods usually add copolymerizable monomers, como/mer, to the polymerization system all at once before the start of polymerization. It is often manufactured by the same method as that for manufacturing vinyl chloride homopolymer, except for the process. This is also due to the fact that the comonomer had a copolymerization reactivity ratio r2 of less than 1, mainly with vinyl chloride such as vinyl acetate. The vinyl chloride copolymer for paste thus obtained is prepared by adding, for example, a plasticizer, a diluent, a stabilizer, a leading thermally decomposable blowing agent, and the decomposition temperature of the blowing agent to the copolymer depending on the application. It is manufactured by mixing or kneading a foaming aid called Kitsuka J and others, forming a so-called "plastisol" state, and heating and gelling it for use in flooring materials, wallpaper, ceiling covering materials, leather, sealants, etc. These vinyl chloride copolymers generally have better meltability than vinyl chloride homopolymers, and are often used in applications that take advantage of this feature. However,
In recent years, the range of applications for this layer has expanded, and low-temperature melting properties and high-speed processability are desired. In order to improve meltability in response to this request, it is necessary to increase the content of comonomer, which may result in a decrease in handling properties due to stickiness of the product, or a decrease in processability due to deterioration of thermal stability. However, there have been problems such as a decrease in the amount of comonomer and a decrease in economic efficiency due to the use of a large amount of comonomer. [Problems to be Solved by the Invention] The present inventors have developed a vinyl chloride-based copolymer that does not have the above-mentioned drawbacks, has a minimum content of Como 77, and has good gelling and melting properties. As a result of intensive studies to produce a polymer, we found that when the vinyl chloride monomer is defined as monomer 1 (M) and the copolymerizable monomer is defined as monomer 2 (M2), the copolymerization reactivity ratio r2 of M2 is It has been discovered that by producing a copolymer by adding one or more comonomers under specific conditions, a copolymer with good gelling and melting properties can be obtained with a relatively low amount of comonomer used, and the present invention I have reached the point where I have completed the . That is, an object of the present invention is to provide a method for producing a vinyl chloride copolymer that exhibits good gelling and melting properties with a relatively low comonomer content. [Means for Solving the Problem] Therefore, the gist of the present invention is to provide a method for emulsion copolymerization or fine suspension copolymerization of a vinyl chloride monomer and a monomer copolymerizable therewith. , vinyl chloride monomer M,
And when the copolymerizable monomer is defined as M2, the copolymerization reactivity ratio r2 of the monomer M2 is 1 or more,
and adding it to the polymerization system intermittently or continuously,
The method for producing a vinyl chloride copolymer is characterized in that this operation is started after the polymerization conversion reaches 50% and completed before the reaction is completed. The present invention will be described in detail. The method for producing the vinyl chloride copolymer of the present invention is carried out by the above-mentioned emulsion polymerization method or fine suspension polymerization method.
The monomer (M2) used for copolymerization includes, for example, unsaturated nitriles such as 7-crylonitrile, methyl acrylate,
Methyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, etc. Acrylic acid, esters of tutaacrylic acid, Itacon minomethyl, Itacon 1 ¥1 diethyl, Itacon R
Examples include monomers with a copolymerization reactivity ratio of 2≧1, such as diisopropyl, itaconic acid esters such as dioctyl itafonate, vinylidene chloride, and aromatic vinyl compounds, and one or more of these monomers Monomers copolymerizable with vinyl chloride are not limited to those mentioned above as long as they satisfy the condition r2≧1, but especially acrylic esters and methacrylic esters. In addition, the content of the copolymerizable monomer is preferably 30% by weight or less, preferably 1 to 20%, particularly 2 to 10% by weight of the copolymer. In the polymerization method of the present invention, as a polymerization initiator, for example, persulfates (sodium salts, potassium salts, ammonium salts, etc.), water-soluble peroxides such as hydrogen peroxide, or A water-soluble redox initiator consisting of these and a reducing agent such as sodium sulfite, ammonium sulfite, sodium hydrogen sulfite, ascorbic acid, sodium formaldehyde sulfoquinlate, or azobisinbutyronitrile, azobis-2,4- Known polymerization initiators consisting of monomer-soluble (oil-soluble) initiators such as methylvaleronitrile, lauroyl peroxide, t-butylperoxypivert, and combinations of these and the above-mentioned reducing agents for redox initiators. In addition, as the emulsifier used in the polymerization, known emulsifiers such as higher alcohol sulfate ester alkali metal salts or ammonium salts, 7-alkylbenzenesulfone #iI fluorka I7 metal salts or ammonium salts, and higher fatty acid alkali metal salts or ammonium salts are used. One type or a combination of two or more types of emulsifiers can be mentioned.The amount of emulsifier used is 0.1 to 3
Parts by weight are preferred, especially 0.3 to 1 part by weight. To carry out the method of the present invention, an emulsion polymerization reaction system or a fine suspension polymerization reaction system consisting of water, a vinyl chloride monomer, an emulsifier or a dispersant, a polymerization initiator, etc. is added to the copolymerization reactivity ratio r2≧1. The copolymerizable monomer M2 is added in two or more portions or continuously, and this addition operation is started after the polymerization conversion rate of the vinyl chloride monomer reaches 50%,
It is necessary to complete the reaction before the end of the reaction. In particular, continuous 1' knee addition is preferred. Furthermore, the timing of starting addition of monomer M2 is not particularly limited as long as it is after the polymerization conversion rate reaches 50%, but if addition is started too late in the polymerization reaction, sufficient copolymerization may not occur. Therefore, it is desirable to start the addition before the conversion rate reaches 65%, preferably 60%. Also, the addition should be completed when the liquid vinyl chloride monomer is no longer present and the saturation pressure of vinyl chloride has reached 65%, preferably 60%. It is desirable to complete the process before it is no longer maintained and the pressure begins to drop. In addition, a part of the vinyl chloride monomer M may be added intermittently or continuously during the polymerization reaction. Of course, it is preferable to carry out the reaction according to the progress of the polymerization reaction, but this is done by detecting the reaction heat generated by the polymerization reaction and using that value as an index.
The amount of i-mer M2 added and the V addition rate are adjusted. The calorific value of the polymerization reaction can be estimated from the internal temperature of the reactor and the temperature at which cooling water such as a jacket enters and exits. Furthermore, if the polymerization reaction is carried out twice, if the same method is adopted in each step based on the results of the second time, it will be easy to carry out the next polymerization reaction. ! After the polymerization reaction, a vinyl chloride copolymer powder is obtained by drying by spray drying, freeze drying, or the like. The delification and melting properties of the vinyl chloride copolymer obtained by dividing, sequentially or continuously adding copolymerizable monomer M in the latter half of the reaction, where r2≧1, are the same comonomer/mer content. However, it is not clear why it is better than the vinyl chloride copolymer that was obtained without using the method of the present invention, but the composition of the vinyl chloride copolymer particles obtained by the polymerization reaction is There is a difference between the inner layer and the outer shell, which contains a large amount of comonomer as a copolymer, while the inner layer contains vinyl chloride octapolymer, so the comonomer content is the same throughout. This is presumably because the outer shell has a relatively high affinity for adhesion to the plasticizer. Vinyl chloride-based J when melting and melting
12 Polymer particles do not completely melt, but the outermost shells of the particles absorb the plasticizer, the particles swell, and the particles come into contact with each other, which occurs sequentially, resulting in an increase in the fluidity of the sol. If we consider that delification occurs due to the disappearance of , we can understand that the composition of the outermost shell is the most important. Due to its high reactivity, the copolymerizable monomer M2, which is mini and has r2≧1″c″, undergoes a rapid polymerization reaction and is therefore quickly incorporated into the copolymer particles. When this is adopted, the copolymer particles have a particle structure similar to that of the above-mentioned vinyl chloride homopolymer coated with a highly concentrated copolymer. In addition, when using the method of the present invention with a comonomer in which r2<1, such as vinyl acetate monomer, a large amount of unreacted comonomer remains, and the expected effect cannot be obtained. The vinyl chloride copolymer produced by the method of the present invention is mainly used as plastisol or organosol for flooring materials,
Used for various purposes such as wallpaper, ceiling covering materials, lasers, sealing materials, steel plate covering materials, and gloves. Plastisol, ol ga/sol wo il! To do IgJ,
The vinyl chloride copolymer produced by the method of the present invention is the main resin component, and in addition, plasticizers, stabilizers, other antioxidants, ultraviolet absorbers, fillers, antistatic agents, etc.
Additives such as colorants, antifogging agents, and mold release agents are evenly blended. As a plasticizer, for example, 7-tal di-n-butyl, 7-tal di-n-octyl, 7-talic acid y-2-ethylhexyl, 7-tal di-n-butyl! ! ! Heptallic acid esters such as noisooctyl, diisononyl heptalate, diisodecyl heptalate, octyldecyl heptalate, butylbenzyl heptalate, no-2-ethylhexyl isophthalate, or heptatalic esters of higher alcohols having about 11 to 13 carbon atoms. Acid plasticizer, di-n-octyl-n-decyl trinolift acid, trimeri)
Trinolift acid group plasticizers such as 2-ethylhexyl trinolate, triisodecyl trinolate, to'J-n-octyl trinolate, 7 nopine l! Fatty acid ester plasticizers such as 1C 2-ethylhexyl, 7Y non-n-decyl acetate, diisodecyl anopinate, 2-ethylhexyl azelaate, dibutyl sepacate, di-2-ethylhexyl sepacate, tributyl phosphate, and tributyl phosphate. 2-Ethylhexyl, phosphorus i1! ! - Phosphate plasticizers such as 2-ethylhexylrunophenyl and tricrenol phosphate, epoxy plasticizers such as epoxidized soybean oil, epoxidized linseed oil, epoxidized tall oil fat@-2-ethylhexyl, or liquid Examples include epoxy resin, which may be used alone or in combination of two or more. The amount used is 10% of the resin component such as vinyl chloride copolymer.
The range is 30 to 200 parts by weight per 0 parts by weight. The stabilizers include lead-based, barium-zinc-based, calcium-zinc-based, magnesium-zinc-based, calcium-barium-based, and cadmium-based stabilizers, which are known as stabilizers for vinyl chloride resins.
Barium-based, barium-zinc-tin-based, cadmium-barium-zinc-based, organotin-based, and other stabilizers can be used. The amount of these stabilizers to be used is 0.1 to 5 parts by weight per 100 parts by weight of the resin component such as vinyl chloride copolymer.
Preferably, it is 0.15 to 3 parts by weight. If the content is too small, thermal stability will be insufficient, and even if more than the appropriate amount is used, the effect will not increase commensurate with the added amount, which is not economical.

【Effect of the invention】

According to the method of the present invention, the comonomer content of the produced vinyl chloride copolymer is relatively small, and therefore, it has good thermal stability, is not sticky, and has excellent gelation and melting properties. [Example 1] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited by the following Examples unless the gist thereof is exceeded. In addition, "part J" and "%J" described in the examples are based on weight. In addition, the copolymerizable monomers (comonomers) used and the copolymerization reactivity ratios r1 and r2 are shown in Table 1. <Method for evaluating the produced vinyl chloride copolymer> ■ Dissolve the resin to be evaluated for comonomer content in THF and create a cast film with a thickness of about 1 µm on a slide glass.This film Measure the IR spectrum using an infrared spectrophotometer, and calculate the comonomer content from a separately prepared calibration curve based on the absorbance ratio of carbonyl absorption at 1730 cm'' and notylene absorption at 1430 cse-'' on the spectrum. When using a comonomer that does not contain a carbonyl group, the total chlorine content can be calculated by comparing it with the theoretical chlorine content of vinyl chloride homopolymer using the combustion-based total chlorine measurement method. ■ Gellable/meltable vinyl chloride 100 parts of copolymer, 60 parts of DOP and Ca-
Stir and mix 3 parts of Zn-based stabilizer in a Chemi-Starte,
Coat it on a glass plate so that the film has a thickness of 1. This was maintained at 120°C for 30 minutes and at 140°C for 30 minutes to gel, and the cut portion of the test piece was
Punch out the punched film into dumbbells with a width of This value is used as a measure of delification and melting properties. potassium sulfate,
Add 50 g of sodium pyrosulfite and stir for about 20 minutes to dissolve it.Then, the inside of the polymerization tank was heated to -610 m theoretical H.
A vacuum was applied at g* and held at 55° C. for 50 minutes. Next, 80 kg of vinyl chloride monomer was charged into the polymerization tank, and the temperature inside the tank was raised to 50°C. , after monomer preparation 1
After 5 minutes, a pre-dissolved 0.2% potassium persulfate aqueous solution was gradually added at a rate of about 10 ml/min, and thereafter the potassium persulfate solution was added so as to maintain a constant polymerization rate. The reaction was carried out while controlling the rate, and the polymerization rate was approximately 15
%, start adding the separately dissolved sodium lauryl sulfate aqueous solution and add the same aqueous solution to 80ml/
The sodium lauryl sulfate was added at a rate of about 10 minutes until the total amount of sodium lauryl sulfate added was 360 g. The pressure inside the tank is 2.0 kg/cm from the saturation pressure of vinyl chloride monomer at 50°C.
The reaction was stopped when the monomer had fallen, and the unreacted monomer was collected to obtain a polymer latex. The latex was composed of monodisperse particles with a diameter of 0.49 μ
Stability was good. Example 1 80 ml of deionized water was added to a polymerization tank with a volume of 200 ml equipped with a stirrer.
4.5 kg (solid content equivalent) of seed polymer latex prepared from Seed Polymer WR-1, 70 g of sodium pyrosulfite, and 100 m of 0.03% cupric chloride aqueous solution.
After degassing, 19 kg of vinyl chloride monomer was charged, and the temperature was raised to 50°C. Thereafter, a 0.1% aqueous solution 101 of ammonium persulfate with a total volume of 15° was added continuously for 15 minutes at a rate of 10 sl/win, and then continuously while controlling the addition rate to maintain a constant polymerization rate. 0 polymerization conversion rate added to 1
From the time when 0% was reached until the end of polymerization, 0.5 kg of sodium lauryl sulfate was added to 0.7% as a 10% aqueous solution.
1/hr, and vinyl chloride monomer 351sr was continuously added at a rate of 7 kg/hr. Furthermore, from when the polymerization rate reached 50%, the total amount was 1.5 k.
g (approximately 1.7 1) of butyl acrylate monomer was added to 10
6. Continuous addition was started at a rate of 00 wl/br.The internal pressure of the reaction tank was 1.0 % lower than the saturation pressure of vinyl chloride monomer at 50°C.
The point at which the polymerization was completed was determined to be 6 kg/cm. After adding pbr, small size spray drying I$1 (manufactured by Nir. Production-M 1nor type)
It was dried using This dried resin was processed in a hammer mill to obtain a crumbled copolymer. Table 1 shows the results of eight evaluations using this pulverized resin as an evaluation sample. Example 2 A copolymer was obtained in the same manner as in Example 1 except that Como/mer was replaced with octyl acrylate. Example 3 Co/mer was changed to 2-hydroxypropyl acrylate, and when the polymerization rate was 50, 55, and 60%, 0 and 6 k, respectively, were added from a pressurized addition tank. A copolymer was obtained in the same manner as in Example 1, except that it was added into the reaction system. Comparative Example 1 The total amount of butyl acrylate (com/mer) (1.5 kg
A copolymer was obtained in the same manner as in Example 1, except for the initial addition (added immediately before addition of vinyl chloride monomer). Comparative Example 2 In Example 1, the addition of butyl acrylate was started at a polymerization rate of about 10%, and the addition rate was increased to 350 m1.
A copolymer was obtained in the same manner as in Example 1 except that the amount was changed to /hr. Comparative Example 3 A copolymer was obtained in the same manner as in Example 1, except that the comonomer was changed to vinyl acetate, which has a copolymerization reactivity ratio of less than 1. Preparation of Seed Polymer-2> In a pre-mixing tank with a volume of 2001 and equipped with a stirrer, 100 kg of ion-exchanged water and 600 kg of lauyl peroxide were added. ,
400 g of sodium lauryl sulfate and 200 g of lauryl alcohol were added, and then the preliminary mixing tank was degassed, and 80 g of vinyl chloride monomer was added and maintained at 35° C. with stirring. After stirring uniformly, the mixture was dispersed into a desired droplet size using an emulsifier (homogenizer) and transferred to a 200+ volume reaction tank equipped with a stirrer that had been previously degassed. After the transfer of the dispersion liquid was completed, the temperature of the reaction tank was raised and polymerization was carried out by a known method. The average diameter of the seed polymer particles in the obtained latex was 0.55μ. Example 4 Preparation of Seed Polymer Using the seed polymer prepared in 2, polymerization was carried out as follows. 80 mL of deionized water in a 200 mL polymerization tank equipped with an agitator.
kg, seed polymer latex 5 kg (solid content equivalent),
After adding 200 g of 0.05% cupric chloride aqueous solution and 20 g of sodium hydrogen carbonate, vinyl chloride monomer 2 was added.
After charging 2.6 kg and raising the temperature to 47°C, a 0.5% aqueous solution of sodium formaldehyde sulfoxylate, which had been dissolved in advance, was added little by little and 0.0 of a total amount of 51
Polymerization was started by continuously adding a 2% cupric chloride aqueous solution to the polymerization tank at a rate of 15 ml/sin. After that, the amount of sodium formaldehyde sulfoxylate aqueous solution added was adjusted so that the polymerization reaction rate was constant. ! I arranged it. After the polymerization started, when the polymerization conversion rate reached about 8%, addition of 35 kg of vinyl chloride monomer was started at a rate of 8 kg/br, and when the polymerization conversion rate reached 10%, 8% separately prepared as an emulsifier until the end of polymerization
Sodium dodecylbenzenesulfonate water soluble fi5 1
was added continuously at a rate of 11/br. During the above polymerization reaction, when the polymerization conversion rate reached 50%, a total of 2.4 kg of 7-butyl tacrylate was added to 1
Addition was started at a rate of 200 wl/hr. When the pressure in the polymerization tank dropped by 1.5 kg/am'' from the saturation pressure of vinyl chloride at 47°C, the polymerization was stopped, unreacted monomers were collected, and post-treatment was carried out in the same manner as in Example 1. A sample for evaluation was obtained.The evaluation results are also listed in Table MS1. Comparative Example 4 A copolymer was produced in the same manner as in Example 4, except that the comonomer was added all at once before starting the polymerization reaction. As seen in these Examples and Comparative Examples, the method of the present invention can convert comonomers with r2≧1 to a conversion rate of 5.
Vinyl chloride-based copolymers produced by dividing, sequentially, or continuously adding such that addition starts after 0% and ends by the time the reaction is completed have poor gelling and melting properties. It is easy to obtain physical properties even when gelatinized at low temperature (Examples 1 to 3 and Comparative Example 1.2 and Example 4 and Comparative Example 4). Low comonomer contents are required. (Although the types of comonomers are different, Example 1 and Comparative Example 4 have almost the same EL upon treatment at 140°C, but it is recognized that the comonomer content is lower in Example 1.) In addition, when using the method of the present invention with a como/mer such as vinyl acetate where r2 is 1, sufficient copolymerization does not occur, and only a polymer with a low como/mer content is obtained relative to the amount charged. It is also insufficient in terms of physical properties. (Comparative Example 3) Present Comonomer 12 BA Butyl Niacrylate OA Octyl Niacrylate HPA 2-Hydroxypropyl Niacrylate VAc: Vinyl Acetate BMA: Butyl Methacrylate Book Reactivity Ratio: This value was extracted from the following literature. J, B randrupr E, H, I mme
rHut", Po17merHandbook" (19
66, Interscience Pub,)C1I
, Na55wC0A, Heiberger; Ency
clopedia of PV C* 2nd e
dition (1986, Marcel Dekker
Inc.) Although it may not necessarily correspond to the polymerization temperature in this example, for these comonomers, there are no examples where r2 changes beyond 1 depending on the temperature, so
The values are listed as is. Amount of comonomer/mer charged: The ratio of the comonomer to the vinyl chloride monomer mixture is shown.

Claims (1)

[Claims] (1) When carrying out emulsion copolymerization or fine suspension copolymerization of a vinyl chloride monomer and a monomer copolymerizable therewith, M_1 is the vinyl chloride monomer and M_2 is the monomer copolymerizable therewith.
When defined as, copolymerization reactivity ratio r_2 of monomer M_2
is 1 or more, and it is added to the polymerization system intermittently or continuously, and this operation is carried out until the polymerization conversion rate is 5.
A method for producing a vinyl chloride copolymer, which starts after the reaction reaches 0% and is completed before the reaction is completed.