JPH0321574B2 - - Google Patents

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 heat colorability is significantly improved by adding a specific substance to the acidic slurry after the chlorination reaction. "Problems to be solved by conventional technology/invention" Chlorinated vinyl chloride resin (hereinafter referred to as CPVC)
is made by chlorinating vinyl chloride resin (hereinafter referred to as PVC). CPVC has a higher softening temperature and superior heat resistance than PVC.
Furthermore, CPVC is known as a unique industrial material because it maintains the excellent 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 the major drawback of being colored yellow-brown by heat during molding, which limits its uses. Various methods have been proposed in the past in order to improve the disadvantage of large thermal coloring. For example, in Tokuko Sho 59-46962,
When polymerizing PVC before chlorination, chlorination can be carried out by adding 0.03 parts or more of an alkyl ester of a compound having a 3,5-ditertiarybutyl-4-hydroxyphenyl group to 100 parts of vinyl chloride monomer. A method to improve the thermal colorability of subsequent CPVC is presented. However, with this method
Although the level of thermal colorability of CPVC has been improved compared to that of past CPVC, the actual situation is that the improvement is small and the difference is still significant when compared to that of PVC. "Means for Solving the Problems" In view of the above-mentioned circumstances, the present invention provides an effective method for significantly suppressing thermal coloring of CPVC 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 dehydrated and dried it.
As a result of investigating the thermal coloring properties of CPVC, we discovered that a certain substance significantly suppresses the thermal coloring of CPVC, providing a remarkable effect comparable to that of PVC, and completed the present invention. . That is, the present invention adds an alkali metal salt of a fatty acid to an acidic slurry of CPVC after a chlorination reaction.
The content includes a method for producing CPVC, characterized in that 0.1 to 1.5 parts by weight are added per 100 parts by weight of CPVC. PVC, the raw material used in the present invention, is a polymer belonging to the so-called vinyl chloride family, and is a vinyl chloride homopolymer or a monomer copolymerizable with it (e.g., ethylene, propylene, chloride). It is a copolymer with a minor amount of vinylidene, acrylic esters, methacrylic esters, etc.). What polymerization methods (e.g.
Although the effects of the present invention can be exhibited even when the polymer is obtained by a suspension polymerization method, a bulk polymerization method, an emulsion polymerization method, etc., the additives used during the polymerization (for example, a polymerization initiator, a dispersant, etc.) In particular, in order to maximize the effects of the present invention, it is necessary to use a polymer with as little contamination as possible (emulsifiers, emulsifiers, etc.) and to have many voids inside the particles of the polymer. In addition, although the degree of polymerization of PVC does not affect the effect of the present invention, ordinary molding methods (for example, extrusion, injection,
range that can be used for calender rolls, etc.), i.e.
Degree of polymerization measured by JISK-6712 method is 400~
1500 is preferable. The chlorination method employed in the present invention is not particularly limited, but generally an aqueous suspension photochlorination method is used. The method is to use ion exchange water.
PVC is slurried, oxygen is removed from the system in a corrosion-resistant reactor, chlorine is supplied, and ultraviolet or visible light is irradiated under normal or slightly pressurized conditions to chlorinate the slurry. The progress of the chlorination reaction is monitored by measuring the concentration of by-product HCl 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. The present invention provides a solution after performing the above chlorination reaction.
This is a method for producing CPVC in which 0.1 to 1.5 parts by weight of an alkali metal salt of a fatty acid is added per 100 parts by weight of CPVC to an acidic slurry of CPVC. 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 an -OH group in the molecule. The alkyl group in the molecule exhibits the same effect whether it is linear or branched. The amount of alkali metal salts of fatty acids added is
The amount 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 thermochromic properties will be small, and if it exceeds 1.5 parts by weight, it will not only impair the transparency and surface properties of the molded product, but also significantly lower the high softening temperature that is characteristic of CPVC. There is a correlation between the amount added and the effect of improving thermal coloring properties up to 1.5 parts by weight, but no further improvement in the effect is seen above 1.5 parts by weight. The addition of alkali metal salts of fatty acids is carried out in an acidic slurry. What is the acidic slurry referred to here?
This is a slurry that exhibits acidity with a pH of 7 or less. Alkali metal salts of fatty acids generally give weak alkalinity when dissolved in water, but when added to the acidic slurry in the present invention, the pH is constantly maintained at 7 or less, preferably 4 or less, from the start of addition to the end of addition. It is necessary to do so. Slurry PH is 7
If the acidity exceeds this value, 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. Although the ratio of CPVC in the slurry is not particularly specified, a resin concentration of 10 to 40 wt% is desirable in consideration of sufficient stirring and economical efficiency during the subsequent dehydration. Also, the temperature of the slurry is 50 to 80
It is desirable to keep it within the range of ℃. 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 properties. As a result, it was found that the thermal coloring of the molded product was much greater than that of CPVC without the addition of CPVC, and that the thermal coloring property deteriorated. Alkali metal salts of fatty acids change into fatty acids under acidic conditions, and when dry-blending these fatty acids into dried CPVC and investigating its effect, a slight improvement in thermal coloring was observed, but this study A significant improvement in heat colorability as achieved in the invention was not achieved. "Action/Effect" In the present invention, the mechanism by which the alkali metal salt of fatty acid improves the thermal colorability of CPVC in the acidic slurry is unknown;
The thermal colorability of CPVC is greatly improved. The present invention is completely new and industrially extremely useful. "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 the Examples and Comparative Examples, the properties of chlorine content, heat colorability, transparency, and Vicatto softening temperature are listed, and these were measured as follows. Further, in the following, all cases where "part" is simply written mean parts by weight. The chlorine content was measured based on the ISO-1158-1978 method by burning CPVC in an oxygen flask.
Expressed as wt% relative to CPVC. Thermal colorability was measured as follows.
100 parts of CPVC and tin-based stabilizer (Nitto Kasei Co., Ltd.)
TVS8813/TVS8831 = 1/1 mixture) 2.0 parts, stearic acid (NOF Corporation, Sakura) 1 part, Hostalb H-4 (Hoechst Japan Co., Ltd. 0.7 parts), MBS resin (Kanebuchi Chemical Co., Ltd.) , Kane Ace B-22) were mixed and kneaded for 3 minutes on a roll at 190°C to make a roll sheet with a thickness of 0.8 mm.The roll sheets were overlapped and preheated on a press at 195°C for 5 minutes. Press molding was carried out for 5 minutes at a pressure of 100 kg/cm ² to obtain a pressed plate with a thickness of 3 mm.This pressed plate was subjected to a color difference meter Σ80 manufactured by Nippon Denshoku Industries to determine the color difference (L value, a value, b value). For transparency, use the above press plate and
Haze (cloudiness %) was determined using a meter. The Vikatsuto softening point is determined using the JIS press plate mentioned above.
-Measured using the method of K-7206 with a load of 5 kg. Example 1 Average particle diameter 120μm, porosity 20vol%, degree of polymerization 700
1,100 g of PVC powder based on the suspension polymerization method described above and 5,010 g of ion-exchanged water were charged into a Pyrex glass reactor with an internal capacity of 8 and equipped with a stirrer, and thoroughly stirred to form a slurry. Next, while heating the reactor from the outside to maintain the internal temperature at 50° C., nitrogen gas was blown into the reactor at a flow rate of 1/min for 20 minutes to replace oxygen in the reaction system. After that, chlorine gas was introduced into this slurry to saturate the reaction system with chlorine, and then a 100W high-pressure mercury lamp was irradiated from the outside while chlorine gas was supplied in excess to start the chlorination reaction. Internal temperature 50℃
After 2.6 hours, the chlorination reaction was completed by stopping the high-pressure mercury lamp irradiation and chlorine supply. Subsequently, nitrogen gas was blown at a flow rate of 1/min for 30 minutes to drive out the chlorine in the system. Furthermore, 10 g of hydroxylamine hydrochloride was added to this slurry and stirring was continued for 10 minutes to completely remove chlorine adsorbed on the particles. A part of the slurry at this time was sampled and its acidity was measured.
The acidity was 1.4N. Next, 11 g of sodium stearate, a first-class reagent, was added to the acidic slurry after the reaction with stirring. After continued stirring for 10 minutes at a slurry temperature of 50°C, the slurry was removed from the reactor and filtered.
At this time, the filtrate showed acidity. The cake on the filter cloth was washed with 20 ml of ion-exchanged water, and then this cake was made into a slurry with ion-exchanged water, and the slurry was neutralized using sodium hydroxide at a slurry temperature of 50° C. so that the slurry pH was 7. 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. After drying, the CPVC product weighed 1295 g. In addition to measuring the chlorine content of this product, a 200g sample was taken and dry blended according to the test formulation described above, then molded using a roll or press under the above conditions, and the heat colorability, transparency, and Vikatsu softening temperature were measured. did. The measurement results are shown in Table-1. Comparative Examples 1-2 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 a dried CPVC resin was obtained in the same manner except that sodium stearate was not added. . The product quantity of dry resin is
It was 1290g. The chlorine content of this product was measured, and 200g of it was taken in Example 1.
Comparative Example 1 was prepared by dry blending in the same manner as in Example 1, then molding with a roll and press. Separately, 200 g was taken, 2 g of sodium stearate powder was added, and then dry blended in the same manner as in Example 1, followed by roll, Comparative Example 2 was prepared by molding with a press, and the heat 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 pH was adjusted to 7 using sodium hydroxide at a slurry temperature of 50°C. It was neutralized to become To this slurry having a pH of 7, 11 g of sodium stearate, a first-grade reagent, was added while stirring. 10 after addition
The PH of the slurry was measured after 1 minute had passed.
It was 8.5. This slurry is dehydrated and washed with water,
The resulting cake was left to dry in a hot air dryer at 50°C for 12 hours. The amount of CPVC product after drying was 1298g. In addition to measuring the chlorine content of this product, a 200g sample was taken and the heat colorability was determined in the same manner as in Example 1.
Transparency and Vikato softening temperature were measured. The measurement results are shown in Table-1.

[Table] As is clear from Table 1, the thermal colorability in Example 1 based on the method of the present invention is superior to any of Comparative Examples 1 to 3. 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.
Wash the cake with 20ml of ion-exchanged water to obtain 1610g of CPVC undried resin (hereinafter referred to as wet resin).
I got it. 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)
Take 5 samples of each (equivalent amount) and 2 samples each.
A slurry was prepared using 1000 g of ion-exchanged water in a beaker, and heated to 50° C. from the outside while stirring. The pH of these slurries was 2.0 to 2.2. During this stirring, 0.5, 1.25, 2.5, 3.75 and 5 g of first grade sodium stearate were added to each of the slurry reagents, 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 a pH of 7. Each slurry was then dehydrated and washed with water, and the resulting cake was
It was left to dry in a hot air dryer at ℃ for 12 hours. The five products after drying were named Examples 2, 3, 4, 5 and Comparative Example 4 according to the increase in the amount of sodium stearate added. A 200 g sample was taken from each product, molded and processed in the same manner as in Example 1, and the heat colorability, transparency, and Vikato softening temperature were measured. Table 2 shows the amount of sodium stearate added to the slurry and each measured value.

[Table] From Table 2, it can be seen that as the number of sodium stearate added increases, the thermal colorability improves. However, as shown in Comparative Example 4,
When the amount exceeds 1.5 parts and exceeds 2.0 parts, a significant decrease in transparency and a significant decrease in the 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 of CPVC dry resin was prepared in the same manner without adding sodium stearate. I got it. When we sampled a portion of this product and measured the chlorine content, it was found to be 65.3wt.
It was in %. We took four samples of 200g each from this product.
0.4, 1, and 100% of reagent first-grade stearic acid, respectively.
Comparative Examples 5, 6, 7 and 8 were prepared by adding 2 and 3 g, and each was molded in the same manner as in Example 1.
Thermal colorability, transparency, and Vikato softening temperature were measured. The results are shown in Table-3. Table 3 shows that the dry blend addition of stearic acid slightly improves CPVC thermal coloring properties, but the degree of improvement is smaller than in Examples 2 to 5, and the degree of decrease in Vicat softening point is large. , it turns out that this is an undesirable method. 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, the results are shown in Figures 1 and 2, respectively.

[Table] Examples 6 to 10 Using the same PVC as in Example 1, chlorination reaction was carried out for 2.6 hours in the same manner as in Example, the slurry was dehydrated without adding sodium stearate, and the cake was soaked in ion-exchanged water. 20 to obtain 1620 g of CPVC wet resin. When the moisture content in this wet resin was measured, it was 20.1 wt% (wet resin base). 313g from this wet resin (250g dry resin)
Five samples (equivalent amount) were taken, and 1000 g of ion-exchanged water was added to the slurry in a beaker 2, and the slurry was 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 sodium laurate, which is a first-class reagent, and another one contains sodium oleate, which is also a first-class reagent.The remaining three parts contain sodium ricinoleate, sodium isostearate, and the like. Examples 6, 7, 8, and 9 were prepared by adding 2 g of potassium laurate each.
and 10, and stirring was continued for an additional 10 minutes. The pH of each slurry after stirring was in the range of 2.2 to 2.5. Next, an aqueous solution of sodium hydroxide was added dropwise to each slurry to neutralize it to a pH of 7. After that, each slurry was dehydrated and washed with water, and the resulting cake was heated to 50°C.
It was left to dry in a hot air dryer for 12 hours. After drying, 200 g samples were taken from each product, molded in the same manner as in Example 1, and heat colorability, transparency, and Vikato softening temperature were measured. The results are shown in Table 4. From Table 4, when the five fatty acid alkali metal salts used were added in the acidic slurry, all
It is understood that this has the effect of significantly improving the thermal colorability of CPVC.

【table】 [Brief explanation of drawings]

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 a graph showing the relationship between the number of additives added and Vikatsu softening temperature. This is a graph showing.

Claims (1)

[Scope of Claims] 1. A process in which an alkali metal salt of a fatty acid is added to a chlorinated vinyl chloride resin after a chlorination reaction in an acidic aqueous suspension (hereinafter referred to as slurry) of the resin.
A method for producing a chlorinated vinyl chloride resin, which comprises adding 0.1 to 1.5 parts by weight per 100 parts by weight. 2. The manufacturing method according to claim 1, wherein the alkali metal salt of a fatty acid is an alkali metal salt of a _C2 to _C32 fatty acid. 3. The manufacturing method according to claim 1 or 2, wherein the slurry has a pH of 4 or less.