JPS62270647A - Production of chlorinated vinyl chloride resin - Google Patents

Abstract

PURPOSE:To obtain a chlorinated vinyl chloride resin having improved properties with respect to heat discoloration, by adding an alkali meal salt of a fatty acid to an acidic slurry of a chlorinated vinyl chloride resin after a chlorination reaction. CONSTITUTION:A chlorinated vinyl chloride resin is produced by adding 0.1-1.5 pts.wt. alkali metal salt of a fatty acid to 100pts.wt. chlorinated vinyl chloride resin in an acidic aq. suspension of the resin after a chlorination reaction. The addition of the alkali metal salt to the aq. suspension is carried out while retaining the suspension at a pH of not higher than 7, pref. 4 during the course of the addition. When the pH of the suspension is higher than 7, the effect of the addition can not be obtd., heat discoloration is promoted and quality is lowered. The concn. of the resin in the suspension is pref. 10-40wt% and it is preferred to keep the temp. at 50-80 deg.C.

Description

[Detailed description of the invention] 3. 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 heat colorability is significantly improved by adding a specific substance to the acidic slurry after the chlorination reaction.

"Prior Art/Problems to be Solved by the Invention" Chlorinated vinyl chloride resin (hereinafter referred to as CPVC) is made by chlorinating vinyl chloride resin (hereinafter referred to as PvC). c.
PVC has a higher softening temperature and excellent heat resistance than PVc. Furthermore, CPVC is known as a unique industrial material because it maintains the excellent rectangular rigidity, creep resistance, and chemical resistance of PVC over a high temperature range, and also has excellent flame resistance and low smoke emission. There is.

However, CPVC has a major drawback in that it is colored yellowish brown by heat during molding, so its uses are limited. Various methods have been proposed to overcome this drawback of large thermal coloring. For example, in Japanese Patent Publication No. 59-46962, when polymerizing PVC before chlorination, an alkyl ester of a compound having a 3,5-ditertiary-butyl-4-bitroxyphenyl group is added to 100 parts of vinyl chloride monomer. A method has been proposed for improving the thermal colorability of CPVC after chlorination by adding 0.03 parts or more. However, cpv by this method
Although the level of thermochromicity of Pvc has been improved compared to that of past cpvc, the improvement range is small and Pv
The reality is that when compared with that of C, there is a significant difference.

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

The present inventors added various substances to the slurry after the chlorination reaction, and as a result of investigating the thermal coloring properties of Cpvc obtained by dehydrating and drying the slurry, it was found that a certain substance significantly improved the thermal coloring of cpvc. The present invention was completed based on the discovery that it suppresses heat coloring and provides a remarkable effect comparable to the level of thermal coloring of PvC.

That is, the present invention includes a method for producing CPVC, which is characterized by adding 0.1 to 1.5 parts by weight of an alkali metal salt of a fatty acid per 100 parts by weight of CPVC to an acidic slurry of CPVC after a chlorination reaction. do.

The raw material PVC used in the present invention is a polymer belonging to the so-called vinyl chloride family, and is a vinyl chloride homopolymer or a predominant amount thereof and monomers copolymerizable with it (e.g., ethylene, propylene, chloride). It is a copolymer with a minor amount of vinylidene, acrylic esters, methacrylic esters, etc.). The effects of the present invention can be achieved even if these are obtained by any polymerization method (for example, suspension polymerization method, bulk polymerization method, emulsion polymerization method, etc.), but the additives used during the polymerization In particular, the effects of the present invention can be maximized if the polymer contains as few agents (e.g., polymerization initiators, dispersants, emulsifiers, etc.) as possible and has many voids inside the polymer particles. This is a necessary requirement for expression.

The degree of polymerization of PVC does not affect the effect of the present invention, but the degree of polymerization measured by the method of JISK-6712 is within the range that can be used in ordinary molding methods (for example, extrusion, injection, calender roll, etc.). 400 to 1500 is desirable.

The chlorination method employed in the present invention is not particularly limited, but
Generally, a water suspension photochlorination method is used. The method involves slurrying PVC using ion-exchanged water, removing oxygen from the system in advance in a corrosion-resistant reactor, supplying chlorine, and exposing it to ultraviolet or visible light under normal or slightly pressurized conditions. It is chlorinated by irradiation. The progress of the chlorination reaction is monitored by measuring the concentration of by-product HCff dissolved in the water in the system. When the degree of chlorination reaches the desired value, the chlorination reaction is stopped by turning off the light source. After the chlorination reaction has stopped, it is important to promptly remove the chlorine remaining in the reaction system, and measures such as expulsion with an inert gas and promotion of expulsion by heating are taken. Furthermore, a reducing agent as described in Japanese Patent Publication No. 45-3820 is added to the slurry after chlorine has been driven out to reduce the chlorine adsorbed in the particles.

In the present invention, alkali metal salts of fatty acids are added to the acidic slurry of CPVC after the above chlorination reaction.
0.1 to 1.5 parts by weight of CPVC added per 0 parts by weight
This is a manufacturing method. The alkali metal salts of fatty acids mentioned herein include sodium salts and potassium salts of monocarboxylic acids, dicarboxylic acids, and tricarboxylic acids of saturated fatty acids or unsaturated fatty acids. It also includes those having 10H group in the molecule. The alkyl group in the molecule exhibits the same effect whether it is linear or branched.

The amount of the alkali metal salt of fatty acid added is set in the range of 0.1 to 1.5 parts by weight per 100 parts by weight of CPVC.

If it is less than 0.1 part by weight, the effect of improving heat colorability is small;
．． Addition of more than 5 parts by weight not only impairs the transparency and surface properties of the molded product, but also greatly reduces the quality (high softening characteristic of CPVC). The amount added and the effect of improving thermal coloring property are as follows: 1.
There is a correlation up to 5 parts by weight, but no further improvement in effect is observed at 1.5 parts by weight or more.

The addition of alkali metal salts of fatty acids is carried out in an acidic slurry. The acidic slurry referred to herein refers to a slurry exhibiting acidity with a pl+ of 7 or less.Alkali metal salts of fatty acids dissolve in water and provide weak alkalinity, but they are not suitable for the acidic slurry in the present invention. It is necessary to constantly maintain the pH at 7 or less, preferably 4 or less, from the start of addition to the end of addition. slurry p
If H exceeds 7 and the product is no longer acidic, the effects of the present invention will not be achieved, and on the contrary, thermal coloring will increase and quality will deteriorate. It is necessary to keep the slurry in a good stirring state during addition. The ratio of CPVC in the slurry is not particularly specified, but considering sufficient stirring and economical efficiency during the subsequent dehydration, a resin concentration of 10 to 40 wt% is desirable, and the temperature of the slurry is in the range of 50 to 80°C. It is desirable that the

The present invention is a manufacturing method in which an alkali metal salt of a fatty acid is added to CPVC in an acidic slurry to improve its thermal coloring property.
When the effect of Hetriblending was investigated, it was found that the thermal coloring of the molded product was much greater than that of CPVC without it, and that the thermal coloring properties were deteriorated. Alkali metal salts of fatty acids change into fatty acids under acidic conditions, and when we investigated the effect of drying this fatty acid in CPVC hetriblend, we found that it slightly improved heat coloring. A significant improvement in thermochromic properties as in the invention was not achieved.

"Action/Effect" In the present invention, the mechanism by which the alkali metal salt of a fatty acid improves the heat colorability of CPVC in an acidic slurry is unknown, but the heat colorability of CPVC is significantly improved. . The present invention' is completely new;
Moreover, it is extremely useful industrially.

"Examples" Hereinafter, the effects of the present invention will be explained in detail with reference to Examples and Comparative Examples, but the present invention is not limited by these. In addition, in the Examples and Comparative Examples, the characteristics of chlorine content, thermal colorability, transparency, and Vikatto softening temperature are entered, but they were measured as follows, respectively. In the following, all references to "part" mean parts by weight.

The chlorine content is +3 by burning CPVC in an oxygen flask.
Measured based on the method of 0-1158-1978, cp
It was expressed as wt% with respect to vc.

Thermal colorability was measured as follows. 100 parts of cpvc plus tin-based stabilizer (Nitto Kasei side, TVS8813/TVS8
831 = 1/1 (7) mixture) 2.0 parts, stearic acid (NOF■, Sakura) 1 part, Hostalb H-4 (Bext Japan-0, F part, MBS resin (Kanebuchi Chemical Co., Ltd.) , 10 parts of Kane Ace B-22) were mixed and kneaded for 3 minutes on a roll at 190°C to make a rolled sheet with a thickness of 0.8. The rolled sheets were overlapped and preheated on a press at 195°C for 5 minutes. After that, it was press-formed for 5 minutes at a pressure of 100 kg/cat to obtain a pressed plate with a thickness of 3 dragons.
value, L value).

Regarding transparency, using the above-mentioned press plate, Haze (cloudiness %) was determined using a Haze meter.

The Vikatsu softening point is determined by using the above press plate.
It was measured by the method of No. 7206 with a load of 5 kg.

Example 1 Based on a suspension polymerization method with an average particle size of 120 μm, a porosity of 20 vol %, and a degree of polymerization of 700. 1100 g of PVC powder and 5010 g of ion-exchanged water were charged into a Pyrex glass reactor with an internal capacity of 81 mm and equipped with a stirrer. It was stirred to form a slurry. Next, heat the reactor from outside to bring the internal temperature to 50℃.
Nitrogen gas was blown into the reactor at a flow rate of 11 parts for 20 minutes to replace oxygen in the reaction system. After that, four people poured chlorine gas into this slurry to saturate the reaction system with chlorine, and while supplying excess chlorine gas,
The chlorination reaction was initiated by irradiation with a 00W high-pressure mercury lamp. The chlorination reaction was allowed to proceed while maintaining the internal temperature at 50°C, and 2
．． After 6 hours, the irradiation with the high-pressure mercury lamp and the supply of chlorine were stopped to complete the chlorination reaction. Subsequently, nitrogen gas was blown at a flow rate of 117 minutes for 30 minutes to drive out the chlorine in the system. Furthermore, 10 g of hydroxylamine hydrochloride was added to this slurry to obtain 1
Stirring was continued for 0 minutes to completely remove chlorine adsorbed on the particles. A part of the slurry at this time was sampled and its acidity was measured, and the acidity was 1.4N.

Next, 1 g of reagent-grade sodium stearate was added to the acidic slurry after this reaction while stirring. After continuing to stir the slurry at a temperature of 50° C. for 10 minutes, the slurry was taken out of the reactor and filtered. At this time, the filtrate showed acidity. The cake on the filter cloth was washed with ion-exchanged water 201, then this cake was made into a slurry with ion-exchanged water, and the slurry pH was adjusted to 7 using sodium hydroxide at a slurry temperature of 50°C.
It was neutralized to become Thereafter, the slurry was filtered again, and the resulting cake was washed with water in the same manner as above, and left to dry in a hot air dryer at 50° C. for 12 hours. The cpvc product after drying is
It was 295g.

In addition to measuring the chlorine content of this product, sample 200
g was taken and triblended according to the test formulation described above, and then molded using a roll or press under the above conditions to obtain heat coloring properties,
Transparency and Vicat softening temperature were measured. The measurement results are shown in Table-1.

Comparative Examples 1 to 2 Using the same PVC as in Example 1, a chlorination reaction was carried out for 2.6 hours in exactly the same manner as in Example 1, and dry resin of CPVC was prepared in the same manner except that sodium stearate was not added. Obtained. The product amount of dried resin was 1290 g.

The chlorine content of this product was measured, and 200g of it was tri-blended in the same manner as in Example 1, and then molded using rolls and presses as Comparative Example 1.
Separately take 200g of sodium stearate powder 2.
Comparative Example 2 was obtained by tri-blending the mixture in the same manner as in Example 1, and molding it by roll and press.Thermal colorability, transparency, and Vicat softening temperature of each were measured. The results are shown in Table-1.

Comparative Example 3 Using the same PVC as in Example 1, a chlorination reaction was carried out in exactly the same manner as in Example 1 for 2.6 hours. Chlorine was expelled using nitrogen gas in the same manner as in Example 1, 10 g of hydroxylamine hydrochloride was added, and the slurry was immediately dehydrated and washed with water, made into a slurry with ion-exchanged water, and the temperature of the slurry was 50°C.
The solution was neutralized to pH 7 using sodium hydroxide.

To this pi 7 slurry was added 1 g of reagent-grade sodium stearate with stirring. The pH of the slurry was measured 10 minutes after the addition and found to be 8.5. This slurry was dehydrated and washed with water, and the resulting cake was
It was left to dry in a hot air dryer at 0° C. for 12 hours. c after drying
The amount of PVC product was 1298g.

In addition to measuring the chlorine content of this product, sample 20
0 g was taken and the thermochromic property, transparency, and Vicat softening temperature were measured in the same manner as in Example 1. The measurement results are shown in Table-1.

Table-1 Notes 1) Brightness The higher the L value, the brighter the better 4)
! Performance ranking AASA, B, C from best to worst
,D,E 5) Transparency For Haze, the higher the number, the more turbidity and poor 6
) As is clear from Table 1, the thermal coloring properties in Example 1 based on the method of the present invention were as follows: Examples 1-3
better than either.

Examples 2 to 5, Comparative Example 4 Using the same PVC as in Example 1, a chlorination reaction was carried out for 2.6 hours in exactly the same manner as in Example, and the slurry was dehydrated without adding sodium stearate. The cake was washed with 201 g of ion-exchanged water to obtain 1610 g of undried CPVC resin (hereinafter referred to as wet resin). When the moisture content in this wet resin was measured, it was 20.2 wt% (wet resin base).

313g from this wet resin (250g dry resin)
Five samples (equivalent amount) were taken, each made into a slurry in 21 beakers using 1000 g of ion-exchanged water, and heated to 50° C. from the outside while stirring. The pH of these slurries was 2.0-2.2.

During this stirring, 0.5, 1, 25, 2, 5, 3.75 and 5 g of each slurry reagent grade sodium stearate were added and stirring was continued for 10 minutes. The pH of each slurry after stirring for 10 minutes was 2.2 to 2.7.

Next, an aqueous solution of sodium hydroxide was added dropwise to each slurry to neutralize it to pH 7. Thereafter, each slurry was dehydrated and washed with water, and the resulting cake was left to dry in a hot air dryer at 50° C. for 12 hours. The five products after drying were treated with Example 2.3 according to the increasing amount of sodium stearate added.
．． 4.5 and Comparative Example 4.

A 200 g sample was taken from each product, molded and processed in the same manner as in Example 1, and the thermochromic properties, transparency, and Vicat softening temperature were measured. Table 2 shows the amount of sodium stearate added to the slurry and each measured value.

From Table 2, it can be seen that as the number of parts of sodium stearate added increases, the thermal colorability improves. However, as shown in Comparative Example 4, more than 1.5 parts and 2.0 parts
%, a significant decrease in transparency and a significant decrease in Vicat softening temperature occur.

Comparative Examples 5 to 8 Using the same PvC as in Example 1, a chlorination reaction was carried out for 2.6 hours in the same manner as in Example 1, and 1290 g CPV was produced in the same manner as in Example 1 without adding sodium stearate.
A dried resin of C was obtained. When a part of this product was sampled and the chlorine content was measured, it was found to be 65.3 wt%.

Four samples of 200 g each were taken from this product, and 0.4, 1.2, and 3 g of reagent-grade stearic acid were added to each sample to form Comparative Examples 5, 6, 7, and 8. Each sample was molded in the same manner, and the thermocolorability, transparency, and Vicat softening temperature were measured. The results are shown in Table-3.

From Table 3, the addition of stearic acid triblend is cp
VC thermal colorability is slightly improved, but the degree of improvement is compared to the cases of Examples 2 to 5.

It can be seen that this is an unfavorable method because the Vicat softening point is small and the degree of decrease in the Vicat softening point is large.

If the b values and Vicat softening temperatures of Examples 2 to 5 and Comparative Examples 5 to 8 are plotted against the number of parts added, FIGS. 1 and 2 are obtained, respectively.

Example 6 ~ IO 2 using the same PVC as Example 1 and the same operation as Example 1
．． The chlorination reaction was carried out for 6 hours, the slurry was dehydrated without adding sodium stearate, and the cake was washed with deionized water for 2 hours.
06 to obtain 1620 g of CPVC wet resin. When we measured the water content in this wet resin, we found that
It was 20.1 wt% (wet resin base).

313g from this wet resin (250g dry resin)
Five samples (equivalent amount) were taken and slurried in 21 beakers with 1000 g of ion-exchanged water, and heated to 50° C. from the outside while stirring. The pH of these slurries was 2.0-2.2.

One of the five parts of the slurry being stirred contains reagent-grade sodium laurate, another one contains reagent-grade sodium oleate, and the remaining three parts contain sodium phosphonolate and isostearate. Example 6 by adding 2 g each of sodium and potassium laurate
．． 7.8.9 and lO and continued stirring for an additional 10 minutes. , the pH of any slurry after stirring is 2.2 to 2.5.
It was within the range of

Next, an aqueous solution of sodium hydroxide was added dropwise to each slurry to neutralize it to a pi of 7. After that, each slurry was dehydrated and washed with water, and the resulting cake was dried in a hot air dryer at 50℃ for 1 hour.
It was left to dry for 2 hours.

Samples of 20 Qg were taken from each product after drying, molded in the same manner as in Example 1, and thermochromic, transparency, and Vicat softening temperature were measured. The results are shown in Table 4.

From Table 4, it is understood that all of the five fatty acid alkali metal salts used have the effect of significantly improving the thermal colorability of CPVC when added in an acidic slurry.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between the number of additives added and thermal colorability (b value) in Examples 2 to 5 and Comparative Examples 5 to 8, and Figure 2 is the relationship between the number of additives added and Vikaft softening temperature. This is a graph showing. -I: 1zu (umbrella t)

Claims (1)

[Claims] 1. After the chlorination reaction, chlorinated vinyl chloride resin is mixed with an alkali metal salt of a fatty acid in an acidic aqueous suspension (hereinafter referred to as slurry) of the resin in an amount of 100 parts by weight. Hit 0.
A method for producing a chlorinated vinyl chloride resin, which comprises adding 1 to 1.5 parts by weight. 2. The manufacturing method according to claim 1, wherein the alkali metal salt of fatty acid is an alkali metal salt of C_2 to C_3_2 fatty acids. 3. Claim 1 in which the pH of the slurry is 4 or less
The manufacturing method described in item 1 or 2.