JPH0195106A - Manufacture of chlorinated vinyl chloride resin - Google Patents

Abstract

PURPOSE:To obtain a chlorinated vinyl chloride resin remarkably improved in thermal discoloration, by chlorinating a vinyl chloride resin while irradiating with light in the presence of water and formic acid or oxalic aid. CONSTITUTION:A small amount of formic acid, oxalic acid or a mixture thereof is added to a suspension comprising a vinyl chloride resin as ray material and water in a corrosion-resistant reaction vessel. After the air in the system is replaced with an inert gas, chlorine gas is blown into the vessel with sufficient stirring to carry out chlorination by irradiating with light. It is preferred that the concentration of formic acid and/or oxalic acid in the suspension is in the range of 0.01-2wt.% based on the total feed on the vinyl chloride and water. The chlorination is carried out at 30-80 deg.C under atmospheric pressure or slightly elevated pressure. The progress of the chlorination is monitored by measuring the concentration of a by-product, i.e., HCl, which corresponds to the degree of addition of chlorine, and when the aimed chlorination is attained, the irradiation with light and the supply of chlorine are stopped to complete the reaction.

Description

[Detailed description of the invention] "Industrial application field" The present invention relates to a method for producing chlorinated vinyl chloride resin.

More specifically, the present invention relates to a method for producing a chlorinated vinyl chloride resin in which the thermal colorability of the resulting product is significantly improved by the presence of a specific substance in the chlorination reaction system.

"Prior Art and Problems" Chlorinated vinyl chloride resin (hereinafter referred to as CPVC) is a substance produced by chlorinating vinyl chloride resin (hereinafter referred to as PvC). CPVC has a higher softening temperature and comparable heat resistance than PvC. Furthermore, CPV
C maintains the excellent properties of PVC, such as stiffness, creep resistance, and chemical resistance, even in high-temperature ranges, and is flammable (
It is known as a unique industrial material because it has excellent properties not found in other resins, such as being flexible and emitting little smoke even when placed in a flame.

However, CPVC has a major drawback in that it is colored yellowish brown by heat during molding, so its uses have been limited.

In order to improve this drawback of being easily colored by heat, various improvement measures have been proposed in the past. For example, special public service in 1987-
46962, when polymerizing PVC before chlorination, 3
．． There is a method for improving the heat colorability of CPVC after chlorination by adding 0.03 parts or more of an alkyl ester of a compound having a 5-ditertiarybutyl-4-hydroxyphenyl group to 100 parts of vinyl chloride monomer. Disclosed. Furthermore, in JP-A-61-250047, CP
A method of improving thermal colorability by adding hydroxypolycarboxylic acid to VC is disclosed. However, although the level of thermal colorability of CPVC obtained by these methods has been improved compared to that of past CPVC,
The improvement was small, and when compared with the thermal coloring properties of PVC, one could not help but admit that there was a significant difference.

"Means for Solving the Problems" In view of the above-mentioned circumstances, the present invention provides an effective method for greatly suppressing thermal coloring of CPVC and bringing it closer to the level of thermal coloring of PVC.

The present inventors carried out a reaction in which various substances were present in the chlorination reaction system of chlorinating PVC to produce CPVC,
As a result of examining the thermal coloring property of the obtained cpvcO, it was found that the presence of a certain substance greatly suppressed the thermal coloring of cpvc,
The present invention has been completed based on the discovery that it provides a remarkable effect comparable to that of thermal coloring.

That is, the present invention chlorinates PvC in the presence of water to produce cpv.
When producing c, in the presence of formic acid and/or oxalic acid,
The content is a method for producing CPVC, which is characterized by carrying out a chlorination reaction by irradiating light.

The raw material PvC used in the present invention is a polymer belonging to the so-called vinyl chloride family, and includes a vinyl chloride homopolymer or a predominant amount thereof, and monomers copolymerizable with it, such as olefins such as ethylene and propylene. It is a copolymer with a minor amount of vinylidene chloride, acrylic esters, methacrylic esters, etc. The effects of the present invention can be achieved even if these are obtained by any polymerization method, such as suspension polymerization method, bulk polymerization method, emulsion polymerization method, etc.; In particular, the effects of the present invention can be maximized if the polymer contains as few agents as possible, such as polymerization initiators, dispersants, emulsifiers, etc., and has many voids inside the polymer particles. This is a desirable requirement for Furthermore, the degree of polymerization of PvC does not affect the effect of the present invention, but the degree of polymerization measured in the range used in ordinary molding methods such as extrusion molding, injection molding, calendar molding, etc., that is, the method of JIS K-6712, 4
00 to 1500 is desirable.

In the present invention, when the above-described raw material PvC is chlorinated in the presence of water, formic acid and/or oxalic acid is present in the chlorination reaction system, and light is irradiated in a suspended state to carry out the chlorination reaction. This is a method for producing Cpvc characterized by the following.

The V, acid and oxalic acid used in the present invention are each HCOOH1 (
COOH)! It is a fatty acid represented by the molecular formula: It is a substance that is easily soluble in water and does not have any swelling or dissolving effects on PvC.

In the present invention, a small amount of formic acid, oxalic acid, or a mixture thereof is added to a suspension of raw material PVC and water in a corrosion-resistant reaction vessel, and then the air in the system is evacuated with an inert gas and thoroughly stirred. Chlorine gas is blown into the bottom, and light is irradiated to carry out the chlorination reaction. The concentration of formic acid and/or oxalic acid added in the suspension is 0.01 based on the total amount of vinyl chloride resin and water.
The concentration is preferably in the range of 2% by weight, and more preferably 0.2% by weight.
The content is set in the range of 0.05 to 1% by weight. This is because if the concentration is too low, the effect will be small, and if the concentration is too high, the effect will be saturated, and the industrial value of the present invention will be lost in terms of cost.

The method of chlorinating PVC in the presence of formic acid and/or oxalic acid according to the present invention is similar to the conventional chlorination method of PVC in the presence of a swelling agent (for example, Japanese Patent Publication No. 36-888, Japanese Patent Publication No. 46-439).
Unlike 4), it is simpler and the production cost is relatively low, without making the raw PVC in any swollen state, and therefore without any effort or cost for removing the swelling agent from the obtained CPVC. This method is low and practically advantageous.

In other words, @acid and oxalic acid are substances that are easily soluble in water and do not swell PvC, and most of them exist dissolved in water during and after the chlorination reaction according to the present invention. Most of these substances are separated and removed by filtering the suspension after chlorination and washing with water, and no traces of these substances are found in the CPVC product.

Therefore, the CPVC obtained according to the present invention does not exhibit the foaming phenomenon during thermal processing that occurs when a swelling agent is used.

Formic acid and oxalic acid used in the present invention are known as compounds having a weak reducing action. A method for producing CPVC by chlorinating PVC in the coexistence of a reducing agent and a chlorinated hydrocarbon swelling agent is disclosed in Japanese Patent Publication No. 39-24280. In this method, the coexistence of a reducing agent and a swelling agent is essential, and therefore the complicated labor and cost burden of removing the swelling agent from the chlorinated CPVC particles cannot be avoided. Further, although this method lists many reducing agents, there is no description of formic acid and oxalic acid used in the present invention, nor is there any disclosure of improvement in thermal colorability.

The present inventors selected several representative substances from among the reducing agents described in this Japanese Patent Publication No. 39-24280, and replaced them with formic acid or oxalic acid under the same conditions as the present invention in the absence of a swelling agent. As a result of adding it to the chlorination reaction system to carry out the chlorination reaction and examining the quality of the obtained CPVC, it was found that the thermal coloring was not improved at all but on the contrary deteriorated (see Comparative Example below).

That is, in addition to the advantage that the coexistence of a swelling agent is not required, the present invention is an extremely useful technique in that it can achieve a significant improvement in thermal colorability that cannot be seen in conventional methods.

In the present invention, after adding a small amount of formic acid and/or oxalic acid to a suspension consisting of PVC and water, the air in the reaction system is replaced with an inert gas, and chlorine gas is blown in with sufficient stirring. This is a method in which the chlorination reaction is carried out under light irradiation, and this reaction is carried out at a temperature of 30 to 80° C. and under atmospheric pressure or slightly increased pressure. The progress of the chlorination reaction is tracked by measuring the concentration of by-product HCI corresponding to the addition of chlorine, and when the target chlorination rate is reached, the reaction is terminated by stopping the light irradiation and the supply of chlorine. After the chlorination reaction is complete, it is important to promptly remove the chlorine remaining in the reaction system.
Measures such as expulsion with inert gas and expulsion by heating are taken. Furthermore, the slurry after chlorine was removed was
It is desirable to add a reducing agent described in 820 to reduce chlorine adsorbed within the particles. The suspension from which chlorine has been completely removed is subjected to a filtration or centrifugation process, and c
PVC is collected. Since the recovered CPVC particles contain by-product HCI, it is necessary to remove the HCI in the particles by repeating washing with water or by resuspending and neutralizing with alkali. In this way, chlorine and HCI remaining in the particles are removed, and then dried to obtain CPVC as a product.

"Action/Effect" The mechanism by which the formic acid or oxalic acid used in the present invention acts in the PVC chlorination reaction system is currently unknown.

However, the thermal colorability of the CPVC obtained according to the present invention is greatly improved, and the present invention is extremely useful industrially.

"Examples" Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. In the Examples and Comparative Examples, the characteristics of chlorine content, thermal colorability, and Vicat softening temperature are described, and these characteristics were measured as follows. In addition, all "parts" in the following descriptions mean "parts by weight."

The chlorine content is determined by burning CPVC in an oxygen flask.
Measured based on the method of O-1158-1978, CP
Expressed in weight % relative to VC.

Thermal colorability was measured as follows. TV38831 (Nitto Kasei Co., Ltd.), a tin-based stabilizer, is added to 100 parts of CPVC.
(manufactured by Nippon Oil & Fats Co., Ltd.) 2.0 parts and stearic acid (manufactured by NOF Corporation) 1.
2 parts were added, mixed uniformly, and kneaded for 3 minutes on a roll with a surface temperature of 190°C to prepare a sheet with a thickness of 0.6 mm. Furthermore, these roll sheets are stacked one on top of the other, and the surface temperature is 19.
Pressure 100kg/- after preheating with 5℃ heat press for 5 minutes
Pressure was applied for 5 minutes to obtain a plate with a thickness of 3 dragons. This press plate was subjected to a toning difference meter Σ80 manufactured by Nippon Heavy Industries Co., Ltd. to determine the color difference (L value, a value, L value).

Vicat softening temperature is determined using the above press plate (JIs)
It was measured with a load of 5 kg based on the method of I-7206.

Example 1 Based on a suspension polymerization method with an average particle diameter of 110 μm, a porosity of 20% by volume, and an average degree of polymerization of 700. 1100 g of PVC powder and 5010 g of ion-exchanged water were placed in a Pyrex glass reactor with a capacity of 181 mm and equipped with a stirrer. The mixture was charged and thoroughly stirred to form a suspension. 30g of reagent grade formic acid was added to this suspension.Next, the reactor was heated from the outside to adjust the internal temperature to 50°C, and nitrogen gas was introduced into the reactor at a flow rate of 31/min for 2 hours.
Blow was carried out for 0 minutes to replace oxygen in the reaction system. Thereafter, chlorine gas was introduced into this suspension to saturate the reaction system with chlorine, and then a 100 W high-pressure mercury lamp was externally irradiated to start the chlorine reaction while supplying an excess of chlorine gas. Internal temperature 50
The chlorination reaction was allowed to proceed while maintaining the temperature at °C, and after 2.7 hours, the irradiation with high-pressure mercury and the supply of chlorine were stopped to complete the chlorination reaction. Subsequently, nitrogen gas was blown at a flow rate of 31/min for 20 minutes to drive out the chlorine in the system. Further, 10 g of hydroxylamine hydrochloride was added to the suspension after chlorine had been expelled, and stirring was continued for 10 minutes to completely remove chlorine adsorbed on the particles, and then the suspension was taken out from the reactor and filtered. The cake on the filter cloth was washed with 201 ml of ion-exchanged water, then the cake was resuspended using ion-exchanged water, and the fQl was adjusted to 7 using sodium hydroxide at a temperature of 50° C. with stirring. It was neutralized so that After filtering the neutralized suspension again and washing the cake with ion-exchanged water, the resin on the filter cloth was left to dry at 50° C. for 12 hours using a hot air circulation dryer.

The CPVC product after drying weighed 1260 g.

In addition to measuring the chlorine content of this product, 200 g of this product was sampled, triblended according to the test formulation described above, rolled and pressed, and the heat colorability and Vicat softening temperature were measured. The measurement results are shown in Table 1.

Example 2 Using the same PVC as in Example 1, 30 g of reagent grade oxalic acid was added to a suspension prepared in the same manner as in Example 1. Thereafter, chlorination reaction and post-treatment were carried out under the same conditions and operations as in Example 1 to obtain 1265 g of a CPVC product. The chlorine content, thermal colorability, and Vicat softening temperature of this product were measured in the same manner as in Example 1. The measurement results are shown in Table 1.

Comparative Example 1 Using the same PvC as in Example 1, chlorination reaction and post-treatment were carried out under the same conditions and operations as in Example 1, except that formic acid was not added, to obtain 1260 g of CPVC product. . The chlorine content, thermal colorability, and Vicat softening temperature of this product were measured in the same manner as in Example 1. The measurement results are shown in Table 1.

Comparative Example 2 Using the same PVC as in Example 1, chlorination reaction and post-treatment were carried out under exactly the same conditions and operations as in Example 1, except that 30 g of reagent special grade Na and SO3 were added instead of formic acid. 1263g of cpvcg product was obtained. The chlorine content, thermal colorability, and Vicat softening temperature of this product were measured in the same manner as in Example 1.

The measurement results are shown in Table 1.

Comparative Example 3 The same PVC as in Example 1 was used, except that 30 g of reagent grade thiophenol was added instead of formic acid.
The chlorination reaction and post-treatment were carried out under exactly the same conditions and operations as in 1, to obtain 1265 g of CPVC product. Example 1: Chlorine content, thermal coloring property, and Vicat softening temperature of this product
It was measured in the same manner. The measurement results are shown in Table 1.

Table 1 remarks; 1) Ming Ling: The larger the L value, the brighter and better it is.

2) Reddish: The higher the a value, the more colored the product is, which is bad.

3) Yellowness: The higher the b value, the more discolored and poor the quality.

4) Heat coloring ranking: A from good to good;
5 carvings of B, C, D, and E! (West.

5) Vicat Soft (17 &: Number 1 straight size has better heat resistance 6) NazSOi and thiophenol in Comparative Examples 2 and 3 are reducing agents described in Japanese Patent Publication No. 39-24280.

Examples 3 and 4.5 Using the same PvC as in Example 1, 3 and 10% of reagent grade formic acid were added to a suspension prepared in the same manner as in Example 1, respectively.
．． 60 g each was added. Thereafter, chlorination reaction and post-treatment were performed under the same conditions and operations as in Example 1 to obtain each CPVC product.

The chlorine content, thermal colorability, and Vicat softening temperature of this product were measured in the same manner as in Example 1. The measurement results are shown in Table 2.

Table 2 From the measurement results of thermochromic properties shown in Tables 1 and 2, it is clear that the CPVC products obtained by chlorinating PVC in the presence of formic acid or oxalic acid according to the present invention have a high PV resistance in the absence of both of these substances.
Cpvc obtained by chlorinating c, or Tokuko Sho 39
PVC in the presence of a reducing agent as described in -24280
It is understood that this material exhibits greatly improved thermal coloring properties compared to CPVC etc. obtained by chlorinating.

Patent applicant Kanebuchi Chemical Industry Co., Ltd. Agent: Patent Attorney Kenji Itan

Claims (1)

[Claims] 1. When producing chlorinated vinyl chloride resin by chlorinating vinyl chloride resin in the presence of water, the chlorination reaction is carried out by irradiating light in the presence of formic acid and/or oxalic acid. 1. A method for producing a chlorinated vinyl chloride resin. 2. The manufacturing method according to claim 1, wherein the chlorination reaction temperature is 30 to 80°C. 3. The concentration of formic acid and/or oxalic acid is 0.01 to 2% by weight (
3. The manufacturing method according to claim 1 or 2, wherein the total amount of vinyl chloride resin and water is charged.