JPH111513A - Production of chlorinated vinyl chloride-based resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce the subject resin having improved gelling properties, and capable of being gelled by a comparatively low energy by using a raw material comprising a specific vinyl chloride-based resin (PVC). SOLUTION: A PVC having only one peak in a polymerization degree distribution curve, >=2.8 polymerization degree distribution width (Q) and 500-1,500 average polymerization degree (P) is chlorinated in the method for producing the objective resin excellent in flame resistance, weather resistance, chemical resistance and thermal resistance. The chlorination is carried out in any state of a suspension, a solution and a solid, and promoted by heating and irradiation of ultraviolet rays. When the chlorination is carried out in the suspension state, water is used as a medium, and optionally, a small amount of ketones and, if necessary, hydrochloric acid or a chlorine-based solvent can be added thereto. The degree of the chlorination is regulated so that the chlorine content of the objective vinylic resin may be 60-75 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a chlorinated vinyl chloride resin, and more particularly to a method for producing a chlorinated vinyl chloride resin which has improved gelling properties and can be gelled with relatively low energy. And a method for producing a chlorinated vinyl chloride resin.

[0002]

2. Description of the Related Art Chlorinated vinyl chloride resin (hereinafter referred to as CPVC) is produced by chlorinating vinyl chloride resin (hereinafter referred to as PVC). CPVC retains properties that are said to be advantages of PVC, and is an improvement over properties of PVC that are said to be disadvantageous. More specifically, CPVC has excellent properties such as flame retardancy, weather resistance, chemical resistance and the like, which are said to be advantages of PVC. On top of that, CPVC is P
Heat deformation temperature is higher by 20 to 40 ° C. than VC. Therefore P
Although VC cannot be used at 60-70 ° C or higher, CPVC
Can be used even at around 100 ° C., which is an improvement over the disadvantage that PVC has poor heat resistance. Thus, CPVC can be used to make heat-resistant pipes, heat-resistant joints, heat-resistant valves, etc. that could not be made with PVC.

[0003] As described above, CPVC has a higher heat distortion temperature than PVC. Therefore, in order to form a molded body by processing normal CPVC, it is necessary to heat the gel to a temperature higher than that of PVC. However, when CPVC is heated at a high temperature, it is immediately decomposed and colored. Therefore, C
PVC is more difficult to gel by heating than PVC. For this reason, when CPVC is heated to form a molded body, the molded body is formed in a state where it is not sufficiently gelled, and the CPVC molded body cannot sufficiently exhibit the impact strength inherent in CPVC. As a result, the impact strength is inferior to PVC, and as a result, the range of use of CPVC has been narrowed.

[0004] Therefore, a method for improving the thermal stability of CPVC has been devised so that CPVC is not decomposed even when molded at a high temperature. However, when attempting to mold CPVC at a high temperature, it is necessary to add a large amount of an additive such as a lubricant at the time of molding, and the resulting molded article has another problem such as increased distortion. Therefore, according to this proposal, a good molded body from CPVC could not be obtained.

As a method for improving the gelling property of CPVC, not as a method for improving the thermal stability of CPVC,
There has been known a method of improving the gelling property by using PVC having a polymerization degree distribution curve having two peaks as a raw material for chlorination. (JP-A-7-76608). In this method, when producing CPVC, the polymerization degree distribution curve has two peaks, and the polymerization degree between the two peaks is 300 to 80.
There is a difference of 0, and when divided by the degree of polymerization intermediate between the two peaks on the degree of polymerization distribution, PVC in which the number of molecules having a low degree of polymerization accounts for 25 to 75% of the whole is used as the chlorinated raw material. It is described that when used, the gelling property of the obtained CPVC is improved. However, when this method is used, there is a problem that the melt viscosity at the time of molding becomes uneven, and as a result, the appearance of the molded product becomes defective.

[0006] In the above-mentioned method, as a cause of appearance defects, there are two CPVCs having a large difference in the degree of polymerization, and therefore, there are two melts having a large viscosity difference in the molten state of the CPVC during molding. Therefore, it is considered that the flowability of the molten material at the time of molding is biased, and this causes a defect in the appearance of the molded body.

Therefore, CPVC which is easily gelled,
There is a demand for the appearance of CPVC which gives a molded article having a high impact strength by processing and does not cause any trouble in the appearance of the molded article.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in response to the above demands. That is,
The present invention retains the advantages of PVC as it is, and is also easy to gel at the time of molding, so that a molded article having high impact strength can be obtained, and the appearance of the molded article is good.
It is intended to provide a method for producing C.

[0009]

According to the method for producing CPVC of the present invention, when producing PVC by chlorinating PVC, the polymerization degree distribution curve has only one peak, and the polymerization degree distribution width (Q) is obtained. Is characterized by using a PVC of Q ≧ 2.8 as a raw material.

The raw material PVC of the conventional CPVC has an average degree of polymerization of 500 to 1500, and the degree of polymerization distribution is a degree of polymerization distribution curve having one peak, and the degree of polymerization degree distribution (Q) is about Q ≦
2.0 PVC is commonly used.

[0011] PVC, which is a raw material of CPVC, is a high molecular compound produced by a polymerization reaction, and contains various degrees of polymerization. Therefore, the degree of polymerization of PVC has a distribution, and the degree of polymerization is generally expressed with the average value of all the compounds, and is indicated by the average degree of polymerization (P). Further, the polymerization degree distribution width (Q) is defined by the following equation. Weight average degree of polymerization (Pw) Pw = Σni · Pi ² / Σni · Pi Number average degree of polymerization (Pn) Pn = Σni · Pi / Σni Polymerization degree distribution width (Q) Q = Pw / Pn where Pi is PVC Where ni is the number of molecules of the i-th polymer.

In general, the shape of the polymerization degree distribution curve of PVC is obtained by plotting the molecular weight of PVC on the horizontal axis and the number of molecules corresponding to the polymerization degree on the vertical axis, and drawing the polymerization degree distribution curve. The curve is chevron. This chevron has a single peak (peak), and has a shape that rapidly descends on both sides from this peak and approaches horizontal.

In the present invention, in order to eliminate defects in the appearance of the molded article, a method for obtaining a CPVC having excellent gelling property without causing a deviation in melt viscosity during molding and kneading has been devised.

According to this method, the degree of polymerization distribution of the raw material PVC used for chlorination is determined such that the degree of polymerization distribution curve has only one peak, and PVC having a low degree of polymerization to a high degree of polymerization has two sides around the average degree of polymerization. PVC having a degree of polymerization distribution such that it exists widely, ie, the degree of polymerization distribution width (Q) is Q ≧
This is a method in which PVC having a viscosity of 2.8 is used as a raw material for chlorination, and it has been found that CPVC obtained by this method has good gelling properties and good appearance of a molded article.

In the PVC used in the present invention, the polymerization degree distribution curve has only one peak, and those having a low polymerization degree to a high polymerization degree are within ± 500 of the average polymerization degree (P) on both sides. Those having a wide range and, as a result, a polymerization degree distribution width (Q) of 2.8 or more are preferable. In practice, it is preferable to use PVC having an average degree of polymerization (P) of 500 to 1500.

The PVC used in the present invention is obtained from P
By blending two or more kinds of PVC having an average degree of polymerization within a range of ± 500 with respect to the average degree of polymerization of VC,
It is preferable that the polymerization degree distribution width (Q) is adjusted to 2.8 or more. When blending, the polymerization degree distribution curve is only 1
In order to have two peaks, the average degree of polymerization of PVC used for blending and the proportion of the blend must be considered. For example, the average polymerization degree is 1,000, and the polymerization degree distribution width is 2.
In order to obtain a PVC of 8 or more, the polymerization degree distribution curve of PVC obtained by blending ordinary PVC having an average degree of polymerization of 500 and PVC having an average degree of polymerization of 1500 in a ratio of 1: 1 is 2
It has a shape having two peaks, and when CPVC obtained by chlorinating this PVC is used, there is a problem in appearance of the molded article.

In the PVC used in the present invention, the polymerization conditions are adjusted at the polymerization stage so that the polymerization degree distribution width (Q) is 2.8.
The PVC described above may be used.

The following methods are known as methods for adjusting the polymerization degree distribution width in the polymerization stage, and any of these methods may be used. (A) A method of adding a regulator when the polymerization conversion rate of PVC is 20 to 70% by weight. (B) A method in which a regulator is added during the polymerization of PVC and the polymerization temperature is changed stepwise. (JP-A-60-7290
(Claim 6) (C) A method in which the polymerization of PVC is performed in a plurality of times, and the polymerization temperature is changed at that time to gradually reduce the degree of polymerization. (Japanese Patent Publication No. 4-28723) (D) During the polymerization of PVC, the polymerization conversion rate is 5 to 60% by weight.
A method of adding a chain transfer agent at the time of (JP-A-3-223
No. 307)

In the present invention, the polymerization degree distribution width (Q) of PVC used as a raw material is limited to the above-mentioned range, but there is no particular limitation in chlorinating this into CPVC. For example, chlorination can be suspended or in solution,
This can be done even in the solid state. At this time, chlorination can be promoted by heating or irradiating ultraviolet rays. Further, when the suspension is carried out, water may be used as a medium, and a small amount of ketones such as acetone and methyl ethyl ketone may be added to the water, and hydrochloric acid may be added if necessary. Further, a chlorinated solvent such as trichlorethylene and carbon tetrachloride may be added. The degree of chlorination is preferably such that the resulting CPVC has a chlorine content of 60 to 75% by weight.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples and comparative examples are given below.
The advantages of the present invention will be specifically described. Also,
In the examples and comparative examples, the physical properties and the degree of polymerization distribution of CPVC obtained therefrom were measured, and the measurements were performed as follows.

(1) Gelation energy (J / g) A blend consisting of 100 parts by weight of CPVC, 2 parts by weight of dibutyltin mercapto, 5 parts by weight of MBS resin, and 1 part by weight of wax was mixed with 60 g of a compound manufactured by Toyo Seiki Co., Ltd. Put into a rotor and rotate at 40 rpm. Kneading was performed at a temperature of 200 ° C., and the energy required until the kneading torque reached the maximum was defined as the gelling energy.

(2) Average Degree of Polymerization The specific viscosity was measured according to JIS K-6721 to calculate the average degree of polymerization. (3) Polymerization degree distribution The polymerization degree distribution width (Q) of the PVC polymer was calculated as Pw / Pn by generally performed gel permeation chromatography. Specifically, a sample in which 0.1% by weight of PVC was dissolved in tetrahydrofuran was 1 × 1.
A degree of polymerization distribution curve is drawn through a column composed of polystyrene gel capable of sieving molecules in the range of 0 ² to 1 × 10 ⁸ , and then a degree of polymerization distribution Pw is calculated using a calibration curve.
/ Pn was calculated. (4) Appearance Using the above composition, using a test extruder,
Using a φ pipe mold, molding was performed at a temperature of 200 to 205 ° C., and the appearance of the obtained molded body was evaluated by visual observation.

(Example 1) As PVC, various PVCs having an average degree of polymerization in the range of 800 to 1200 are blended so that the degree of polymerization distribution curve has only one peak. The one having a polymerization degree distribution width (Q) of 2.8 was used. In a 300 liter glass-lined autoclave, place the above PVC
100 parts by weight and 500 parts by weight of ion-exchanged water are added,
With good stirring, PVC was dispersed in water to obtain a suspended state. Next, the suspension was heated to 70 ° C., the inside of the autoclave was degassed under reduced pressure to remove oxygen, nitrogen gas was blown into the autoclave, chlorine was blown, and PVC was chlorinated while irradiating ultraviolet rays from a mercury lamp. It has become. The concentration of hydrochloric acid in the autoclave was measured to check the progress of the chlorination reaction, and the resulting CPVC had a chlorine content of about 6%.
When the amount of chlorine gas reaches 6.5% by weight, the supply of chlorine gas is stopped.
The chlorination reaction was completed. Thereafter, unreacted chlorine was expelled by blowing nitrogen gas, and the obtained dispersion was neutralized with an alkali, washed with water, dehydrated, and dried to obtain CPVC.

The energy required for gelation of the thus obtained CPVC was measured by the method described above, and was found to be 150 J / g. The appearance of the molded article was also good.

(Example 2) The average degree of polymerization was from 600 to 140.
Various PVCs within the range of 0 are blended such that the polymerization degree distribution curve has only one peak, and the average degree of polymerization is 1
000, and the chlorination was carried out in the same manner as in Example 1 except that the polymerization degree distribution width (Q) was 3.4, to obtain CPVC having a chlorine content of 66.5% by weight.

The energy required for gelation of the obtained CPVC was measured and found to be 110 J / g. The appearance of the molded article was also good.

Example 3 A chain transfer agent was added to the polymerization,
PVC having an average degree of polymerization of 1,000 and a degree of polymerization degree distribution (Q) of 3.0 was used. Specifically, 99 kg of ion-exchanged water, 1.4 kg of a 3% by weight solution of polyvinyl alcohol, and 60 g of lauroyl peroxide were supplied to a polymerization tank having a capacity of 216 liters, and a vacuum operation was performed. Thereafter, 66 kg of a vinyl chloride monomer was added, and polymerization was started at 50 ° C. When the polymerization conversion was about 40% by weight, 0.2 g of mercaptoethanol was added. When the polymerization conversion reached 85% by weight, the reaction was stopped, unreacted vinyl chloride monomer was recovered, and the produced PVC was taken out of the polymerization tank and dried to obtain PVC. This PVC was chlorinated in the same manner as in Example 1 to obtain a CPV having a chlorine content of 66.5% by weight.
C was obtained.

The energy required for gelation of the obtained CPVC was measured and found to be 140 J / g. The appearance of the molded article was also good.

(Example 4) A chain transfer agent was added to the polymerization,
PVC having an average polymerization degree of 1000 and a polymerization degree distribution width (Q) of 3.6 was used. Specifically, 99 kg of ion-exchanged water, 1.4 kg of a 3% by weight solution of polyvinyl alcohol, and 60 g of lauroyl peroxide were supplied to a polymerization tank having a capacity of 216 liters, and a vacuum operation was performed. Thereafter, 66 kg of a vinyl chloride monomer was added, and polymerization was started at 50 ° C. When the polymerization conversion was about 40% by weight, 0.5 g of mercaptoethanol was added. When the polymerization conversion reached 85% by weight, the reaction was stopped, unreacted vinyl chloride monomer was recovered, and the produced PVC was taken out of the polymerization tank and dried to obtain PVC. This PVC was chlorinated in the same manner as in Example 1 to obtain a CPV having a chlorine content of 66.5% by weight.
C was obtained.

When the energy required for gelation of the obtained CPVC was measured, it was 110 J / g. The appearance of the molded article was also good.

Example 5 A chain transfer agent was added to the polymerization,
The average polymerization degree is 800, and the polymerization degree distribution width (Q) is 3.
Zeroed PVC was used. Specifically, 99 kg of ion-exchanged water, 1.4 kg of a 3% by weight solution of polyvinyl alcohol, and 60 g of lauroyl peroxide were supplied to a polymerization tank having a capacity of 216 liters, and a vacuum operation was performed. Thereafter, 66 kg of a vinyl chloride monomer was added, and polymerization was started at 54 ° C. When the polymerization conversion was about 40% by weight, 0.2 g of mercaptoethanol was added. When the polymerization conversion reached 85% by weight, the reaction was stopped, unreacted vinyl chloride monomer was recovered, and the produced PVC was taken out of the polymerization tank and dried to obtain PVC. This PVC was chlorinated in the same manner as in Example 1 to obtain a CPVC having a chlorine content of 66.5% by weight.

The energy required for gelation of the obtained CPVC was measured and found to be 120 J / g. The appearance of the molded article was also good.

(Comparative Example 1) The degree of polymerization was 1,000, the degree of polymerization distribution curve obtained by the conventional polymerization method had only one peak, and the degree of polymerization distribution (Q) was 2.0.
Was used. Specifically, 99 kg of ion-exchanged water, 1.4 kg of a 3% by weight solution of polyvinyl alcohol, and 60 g of lauroyl peroxide were supplied to a polymerization tank having a capacity of 216 liters, and a vacuum operation was performed. Thereafter, 66 kg of a vinyl chloride monomer was added, and polymerization was started at 57 ° C. When the polymerization conversion reached 85% by weight, the reaction was stopped, unreacted vinyl chloride monomer was recovered, and the produced PVC was taken out of the polymerization tank and dried to obtain PVC.
This PVC was chlorinated in the same manner as in Example 1 to obtain a CPVC having a chlorine content of 66.5% by weight.

The energy required for gelation of the obtained CPVC was measured and found to be 200 J / g. Further, the appearance of the molded article was good.

Comparative Example 2 PVC having an average degree of polymerization of 600
And PVC of 1400 are blended at a ratio of 1: 1 and the average degree of polymerization is 1000, but a polymerization degree distribution curve having two peaks is used. Otherwise, chlorination is performed in the same manner as in Example 1, CPVC having a chlorine content of 66.5% by weight was obtained.

The energy required for gelation of the obtained CPVC was measured and found to be 110 J / g. However, unevenness occurred in the molten state during molding, and the appearance of the molded body was deteriorated.

Comparative Example 3 A chain transfer agent was added to the polymerization.
The one having an average polymerization degree of 1,000 and a polymerization degree distribution width (Q) of 2.5 was used. Specifically, 99 kg of ion-exchanged water, 1.4 kg of a 3% by weight solution of polyvinyl alcohol, and 60 g of lauroyl peroxide were supplied to a polymerization tank having a capacity of 216 liters, and a vacuum operation was performed. Thereafter, 66 kg of a vinyl chloride monomer was added, and polymerization was started at 55 ° C. When the polymerization conversion was about 40% by weight, 0.1 g of mercaptoethanol was added. When the polymerization conversion reached 85% by weight, the reaction was stopped, unreacted vinyl chloride monomer was recovered, and the produced PVC was taken out of the polymerization tank and dried to obtain PVC. This PVC was chlorinated in the same manner as in Example 1 to obtain a CPV having a chlorine content of 66.5% by weight.
C was obtained.

The energy required for gelation of the obtained CPVC was measured and found to be 200 J / g. Further, the appearance of the molded article was good.

(Comparative Example 4) The polymerization degree was 800, and the polymerization degree distribution curve obtained by the ordinary polymerization method was only 1
PVC having two peaks and having a polymerization degree distribution width (Q) of 1.9 was used. Specifically, 99 kg of ion-exchanged water, 1.4 kg of a 3% by weight solution of polyvinyl alcohol, and lauroyl peroxide 6 were placed in a polymerization tank having a capacity of 216 liters.
0 g, and a vacuum operation was performed. Thereafter, 66 kg of a vinyl chloride monomer was added, and polymerization was started at 54 ° C. When the polymerization conversion reached 85% by weight, the reaction was stopped, unreacted vinyl chloride monomer was recovered, and the produced PVC was taken out of the polymerization tank and dried to obtain PVC.
Otherwise chlorinating was carried out in the same manner as in Example 1 to obtain CPVC having a chlorine content of 66.5% by weight.

The energy required for gelation of the obtained CPVC was measured and found to be 180 J / g. Further, the appearance of the molded article was good.

(Comparative Example 5) PVC having an average degree of polymerization of 300
And 1300 PVC are blended at a ratio of 1: 1 and the average degree of polymerization is 800, but a polymerization degree distribution curve having two peaks is used. Otherwise, chlorination is performed in the same manner as in Example 1, CPVC having a chlorine content of 66.5% by weight was obtained.

The energy required for gelation of the obtained CPVC was measured and found to be 100 J / g. However, unevenness occurred in the molten state during molding, and the appearance of the molded body was deteriorated.

[0043]

According to the present invention, the degree of polymerization distribution curve has only one peak, and the degree of polymerization distribution width (Q) of 2.8 or more is used as a chlorination raw material.
In C, there are many molecules having a low degree of polymerization.
Gelation of CPVC obtained by chlorinating VC can be performed with relatively low energy.

The polymerization degree is widely distributed around the average polymerization degree, and the polymerization degree distribution curve has a distribution shape having only one peak. Is obtained by chlorinating PVC such that the degree of polymerization distribution curve has two peaks.
As described above, there is no unevenness in the melt viscosity during molding and kneading.

That is, the CP obtained by the present invention
When VC is formed into a molded article, the molded article retains the properties of CPVC, is easily gelled, has high impact resistance, and has a good appearance. Therefore, the present invention provides a CPVC suitable for manufacturing heat-resistant pipes and heat-resistant joints.
In that it can provide significant benefits.

Claims (3)

[Claims] In producing a chlorinated vinyl chloride resin by chlorinating a vinyl chloride resin, a polymerization degree distribution curve has only one peak, and the polymerization degree distribution width (Q) is Q ≧ 2. 8. A method for producing a chlorinated vinyl chloride resin, comprising using the vinyl chloride resin as a raw material. 2. A method of blending two or more vinyl chloride resins having an average degree of polymerization within a range of ± 500 with respect to the average degree of polymerization of the vinyl chloride resin. , The polymerization degree distribution width (Q) is Q ≧ 2.
The method for producing a chlorinated vinyl chloride resin according to claim 1, wherein the polymerization degree distribution curve is adjusted to 8, and the polymerization degree distribution curve has only one peak. 3. The vinyl chloride resin used for chlorination is characterized in that the polymerization degree distribution width (Q) is adjusted to Q ≧ 2.8 in the polymerization step, and the polymerization degree distribution curve has only one peak. The method for producing a chlorinated vinyl chloride resin according to claim 1.