JPS6222809A - Production of vinyl chloride polymer - Google Patents

Abstract

PURPOSE:To obtain a vinyl chloride polymer which can give a plastisol of excellent gelation property, by performing the polymerization while adding a compound terminated with an ethylenically unsaturated double bond to the reaction system in the production of a vinyl chloride polymer by, for example, an emulsion polymerization process. CONSTITUTION:In the production of a vinyl chloride polymer by polymerizing vinyl chloride by an emulsion polymerization process or a fine-suspension polymerization process, the purpose vinyl chloride polymer is obtained by performing said polymerization while intermittently or continuously adding a compound terminated with an ethylenically unsaturated double bond to the polymerization system after the desired polymerization temperature is reached. Examples of the ethylenically unsaturated double bond-terminated compounds which can be suitably used include diallyl phthalate, diallyl maleate and divinylbenzene. With respect to the time of addition, it is suitable that the addition is stared after the polymer conversion reaches 5% and it is stopped before the conversion reaches 40%.

Description

Detailed Description of the Invention "Industrial Application Field" The present invention provides a method for producing plastisol that has good gelling properties without sacrificing properties such as mechanical properties, viscosity stability, and thermal stability. The present invention relates to a method for producing a vinyl chloride polymer that can be obtained.

``Prior art'' Vinyl chloride polymers for paste are usually produced by emulsion polymerization using an emulsifier and a water-soluble catalyst, or by homogenization treatment in the presence of an oil-soluble catalyst using an emulsifier* or a suspending agent in combination with this. Vinyl chloride polymer latex is produced by a fine suspension polymerization method in which the polymer is then polymerized, and the latex is then spray-dried.

The vinyl chloride polymer for paste produced in this way is mixed with plasticizers, diluents, stabilizers, etc., and made into paste dispersions such as plastisols or organosols, which can be used by coating methods, dipping methods, sludge molding, etc. In either case, the amount of plastisol in processing is also an important factor in ensuring good deltability.

As means for improving the deltability of vinyl chloride polymers for pastes, it is known to lower the average degree of polymerization or to copolymerize with other monomers that can be copolymerized with vinyl chloride. However, although it is possible to improve gelling properties to some extent by lowering the average degree of polymerization of the polymer, the mechanical properties such as tensile strength and elongation of molded products obtained using this polymer deteriorate. I can't avoid that.

From this point of view, various methods have been introduced for producing vinyl chloride homopolymers for pastes with improved deltability.

For example, when emulsion polymerizing vinyl chloride, as in Japanese Patent Publication No. 46-18483, by increasing the polymerization temperature during the polymerization, the average polymer of the polymer molecules constituting the unit particles is dispersed from the center to the periphery. There is a method of forming a composite structure in which the decrease in the direction is intermittent or continuous, and a method of emulsion polymerization of vinyl chloride, as in Japanese Patent Publication No. 48-2221, uses a chain transfer agent to increase the degree of polymerization within the unit particles. A method for creating a composite structure with 700 or more is introduced. However, in the case of the above-mentioned Japanese Patent Publication No. 46-18483, if the temperature difference between the temperature at the start of polymerization and the polymerization temperature after increasing the polymerization temperature is small, the effect of improving gelation property cannot be expected much. In the case of increasing the polymerization temperature, there are troublesome operations in the polymerization operation due to changes in the polymerization temperature and difficulties in controlling the reaction rate. Also special public service in 1977
-2221, compared to a polymer having almost the same average degree of polymerization obtained by adjusting the degree of polymerization using a normal polymerization method, it is 8! In order to obtain a polymer that maintains the same level of mechanical properties without reducing its mechanical properties, it is necessary to perform the polymerization at a temperature lower than the usual polymerization temperature, and it is necessary to use a large amount of a chain transfer agent. This is economically disadvantageous because it causes a decrease in the polymerization temperature and a decrease in the 8!1 mechanical stability of the latex.

On the other hand, if a copolymer is used, for example, a copolymer with vinyl acetate, the deltability will improve as the content of the comonomer increases, but on the other hand, if it is made into a plastisol, the viscosity will be too high and it will not change over time. It has the drawback that the heat stability is deteriorated, making it difficult to mold and process.

[Problems to be Solved by the Invention] As a result of intensive research in order to improve the above-mentioned drawbacks of vinyl chloride polymers for pastes, the present inventors found that the 8!1 mechanical properties, viscosity stability, thermal stability A vinyl chloride polymer for paste made of a vinyl chloride homopolymer with good deltability without sacrificing properties such as properties! ! ! The present invention has been achieved by discovering a method to utilize this technology.

That is, the purpose of the present invention is to improve mechanical properties, viscosity stability,
The object of the present invention is to provide a method for producing a vinyl chloride polymer with improved gelling properties without sacrificing properties such as thermal stability.

Therefore, the gist of the present invention is to provide a method for producing a vinyl chloride polymer by adding salt, after reaching a desired polymerization temperature, to add an ethylenic polymer to the end. The present invention relates to a method for producing a vinyl chloride polymer, characterized in that polymerization is carried out while adding a compound having a double bond intermittently or continuously.

To explain the present invention in detail, the method of the present invention employs an emulsion polymerization method or a microsuspension polymerization method, which is normally used when producing a vinyl chloride polymer for paste. The emulsion polymerization method or the fine suspension polymerization method may be polymerization in the presence of a seed polymer prepared in advance, so-called seed polymerization. The emulsifier used during polymerization is not particularly limited as long as it is an emulsifier normally used in vinyl chloride polymerization, and examples include anionic surfactants such as fatty acid ammonium salts, alkyl sulfate ester salts, alkylaryl sulfonate salts, etc. At least one type of emulsifying agent is used, and emulsifying aids such as higher fatty acids, higher alcohols, and nonionic surfactants may also be used in combination.

Polyvinyl alcohol and protein molecules are used as the suspending agent.

The compound having an ethylenic double bond at the end used in the method of the present invention is a compound that acts to crosslink vinyl chloride or vinyl chloride polymer molecules with each other during polymerization of vinyl chloride, and has a ethylenic double bond at the end of the compound. It is desirable to use one having two or more II- ethylenic double bonds.

Specifically, phthalic acid diallyl ester, maleic acid diallyl ester, heptamalic acid noallyl ester, triallyl cyanurate, diallyl anobate, diallyl ether, noallyl carbonate Y1 diallyl diglycol carbonate, diallyl, divinyl ether, divinyl ketone , novinylbenzene, etc., and at least one of these is used. The amount of these compounds (hereinafter referred to as crosslinking agents) used is 0.001% by weight or more based on the monomers charged, and 0.2% by weight or more based on the monomers charged.
The amount is preferably 0.15% by weight or less, preferably 0.15% by weight or less, and these crosslinking agents have relatively high reactivity with vinyl chloride or vinyl chloride polymers, and unreacted substances remain free in the polymer. Since there is little possibility of this occurring and the amount used is small, the three-dimensionalization of the vinyl chloride polymer due to the crosslinking reaction will not proceed too much. In the method of the present invention, it is most preferable to use diallyl heptalate in terms of crosslinking reactivity, ease of handling, and availability.

Specifically, heptatalic acid diallyl ester is relatively highly reactive, and as long as it is not in an extremely excessive amount and as long as the addition rate of heptatalic acid noallyl ester during polymerization is appropriate, It is unlikely to remain in the polymer. If a large amount is used, the concentration of heptatalic acid diallyl ester in the monomer will increase, resulting in too much three-dimensionalization due to crosslinking reaction, and the delta content (insoluble content of vinyl chloride polymer in solvent) will increase. This does not meet the purpose of the present invention.

The method of the present invention consists in adding a crosslinking agent intermittently or continuously during emulsion polymerization or fine suspension polymerization of vinyl chloride. Continuous addition is particularly preferred in order to carry out the crosslinking reaction as uniformly as possible during the addition period. The crosslinking agent may be added at any time after the start of polymerization, but if it is added early, such as immediately after the start of polymerization, it tends to have a negative effect on the generation of vinyl chloride polymerization dead particles, and the crosslinked polymer may be added to the center of the formed unit particles. As a result, it is difficult to maximize the effect of improving gelling properties, so it is desirable to start addition after the polymerization conversion rate is 5% by weight, preferably 10% by weight or more. It is effective to finish adding the monomer by the time the polymerization conversion rate of the monomer reaches 40%, preferably 35%. If the crosslinking agent is added after the polymerization conversion reaches 40% by weight or more, the molecular-like layer that constitutes the outer shell of the unit particle becomes thinner, and the PIi of the resulting polymer decreases.
Mechanical and sexual nature tends to cause deterioration.

Thus, the process of the present invention may be performed at any temperature used in the polymerization of vinyl chloride, but in particular from 30 to 770.
The temperature may be appropriately selected within the range of °C depending on the use of the vinyl chloride polymer.

[-Effects of the Invention] The method of the present invention comprises adding a compound having a terminal ethylenic double bond intermittently and intermittently during the polymerization of vinyl chloride.
) without significantly changing the mechanical properties, viscosity stability, thermal stability, etc. of the vinyl chloride polymer for Beef L of It can improve the gelation properties and the processability of vinyl chloride polymers, and has extremely high industrial utility value.

"Examples" Next, the method of the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

Example-1 (A) Production of seed polymer In a 2001 volume premix tank equipped with an agitator, 100 kg of ion exchange water and lauroyl peroxide (hereinafter referred to as LPO) were added.
), 400 g of sodium lauryl sulfate, and 200 g of lauryl alcohol were added, then the premix tank was degassed, and 60 kg of vinyl chloride monomer was added, and the temperature was maintained at 35°C with stirring.

200 equipped with a stirrer that had been degassed in advance while being uniformly stirred and dispersed to the desired droplet size using an emulsifier.
Transferred to a 1 volume reaction tank. 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 particle diameter of the seed polymer particles in the latex obtained by setting the emulsification pressure of the emulsifier to 250 kg/can2 is 0.4.
It was μ.

Next, the seed polymer particles were held at 60°C for 2 hours to decompose the excess amount of LPO in order to produce a vinyl chloride polymer with an average particle diameter of μ. adjusted.

(B) Production of vinyl chloride polymer Seed polymerization was carried out using the T4-adjusted seed polymer as described above.

80 ml of ion-exchanged water in a 200+ volume polymerization tank equipped with a stirrer
kg, seed latex with an average particle diameter of 0.4 μ and an average degree of polymerization of 1400 after adjusting the amount of LPO is used as a polymer.
, 6 kg, and 20 g of sodium hydrogen carbonate were degassed, and 75.4 kg of vinyl chloride monomer was charged.
The temperature was raised to 55°C, and a 0.3% aqueous solution of sodium bisulfite, which had been dissolved in advance, was continuously added little by little to the polymerization tank to initiate polymerization. A constant reaction rate was controlled by adding sodium bisulfite. In addition, sodium lauryl sulfate was added as an emulsifier to the total amount of vinyl chloride monomer and seed polymer at a rate of 0.08% by weight per hour from the time the polymerization conversion rate reached 10% to the end of polymerization. was added continuously. Furthermore, when the polymerization conversion rate of the cross-linking agent 7-talic acid diallyl ester is 10%, the total amount is 0°1 from α to the total amount of the monomer charged and the seed polymer.
% was added continuously at a constant flow rate until a predetermined polymerization conversion rate was reached.

Polymerization pressure is 1kHz/1kHz from vinyl chloride saturation pressure at 55℃
When am2 decreased, polymerization was stopped and unreacted monomers were collected.

Table 1 shows the average particle diameter of the obtained latex, the average degree of polymerization of the polymer obtained by spray-drying and pulverizing this latex in a conventional manner, and the delta temperature of plastisol prepared using this polymer. Ta.

Note that the average degree of polymerization was measured in accordance with JIS K6721. The gelling temperature is vinyl chloride polymer 100if
The viscosity of the plastisol consisting of i part, no 2-ethylhexyl 7 thale) was measured with a B-type viscometer (B-8R) while the temperature was slowly raised externally, and the temperature when a constant viscosity was reached. I showed it. (The same applies to the following Examples) Example-2, Comparative Example 1 In the same manner as No. 2 of Example-1, 7
Polymerization was carried out using the same recipe except that the amount of diallyl talate added was changed. The average particle of the latex obtained (
The average degree of polymerization of a polymer obtained by spray-drying and pulverizing this latex in a conventional manner and the plastisol prepared using this polymer are shown in Table 2.

For comparison, Table 2 also shows the delta temperature of plastisol of a polymer in which the degree of polymerization was controlled by the polymerization temperature without using any diallyl 7-talate ester.

Example-3 80k of ion-exchanged water was placed in a 200I capacity polymerization tank equipped with a stirrer.
g, average particle size 0.5μ, average degree of polymerization 1450 vinyl chloride polymer seed latex as a polymer 4,8k
g, formaldehyde sodium sulfochelate 60g
After charging, 75.2 kg of vinyl chloride monomer was added and the temperature was raised to 55°C to start polymerization and the total amount was 0.035% by weight (based on the vinyl chloride monomer and seed polymer). A total amount of hydrogen peroxide was added continuously throughout the entire polymerization time. In addition, from the time the polymerization conversion rate reached 10%,
Until the end of the polymerization, add sodium lauryl sulfate as an emulsifier per hour to the total amount of vinyl chloride monomer and seed polymer.
．． It was added continuously at a rate of 0.8% by weight. Further, from a polymerization conversion rate of 10%, 7-talic acid noallyl ester as a crosslinking agent was continuously added at a constant flow rate in a total amount of 0.1% by weight based on the total amount of the monomer charged and the seed polymer.

1 k from the saturation pressure of vinyl chloride at a polymerization pressure of 55°C
The polymerization was stopped when the drop was 0.0 g/0 m2, and the unreacted monomer was collected. The average particle diameter of the obtained latex was 0.8μ
Met. This late Nox was spray-dried and ground in a conventional manner to obtain a vinyl chloride polymer for paste. Table 3 shows the average degree of polymerization of this polymer and the gelation temperature of plastisol prepared using this polymer.

Comparative Example-2 The polymerization temperature was set at 45.5°C in the same manner as in Comparative Example-1, and the degree of polymerization was adjusted without adding any diallyl 7-talate as a crosslinking agent. The average degree of polymerization of polymers having almost the same degree of polymerization, the average particle diameter of the polymer latex, and the delta temperature of plastisol prepared using this polymer are also listed in Table 3 for comparison.

] So, knee 1 25. '.

Ippaji

Claims (5)

[Claims] (1) In a method for producing vinyl chloride polymer by vinyl chloride emulsion polymerization method or fine suspension polymerization method, after reaching the desired polymerization temperature, a compound having an ethylenic double bond at the end is added intermittently or continuously. A method for producing a vinyl chloride polymer, characterized in that the polymerization is carried out while adding a vinyl chloride polymer. (2) The method for producing a vinyl chloride polymer according to claim 1, wherein the compound having an ethylenic double bond at the terminal is added while the polymerization conversion rate reaches 40%. (3) The method for producing a vinyl chloride polymer according to claim 1 or 2, wherein addition of the compound having an ethylenic double bond at the terminal is started after the polymerization conversion rate reaches 5%. (4) Claim 1, wherein the compound having an ethylenic double bond at the terminal is diallyl phthalate;
A method for producing a vinyl chloride polymer according to item 2 or 3. (5) The method for producing a vinyl chloride polymer according to claim 1, wherein the desired polymerization temperature is in the range of 30 to 70°C.