TWI769443B - Polyvinyl chloride powder with ultrahigh bulk density and method for producing the same - Google Patents

Abstract

The present invention relates to a polyvinyl chloride powder with an ultrahigh bulk density and a method for producing the same. An initiator is added into a mixed solution, and then heating the mixed solution to subject to a polymerization reaction. Moreover, polyepoxides are further added into the mixed solution during the polymerization reaction. After the polymerization reaction is completed, a neutralization reaction and a drying process are performed in sequence, therefore obtaining the polyvinyl chloride powder of the present invention with a higher bulk density. Accordingly, the polyvinyl chloride powder has excellent processing properties due to the higher bulk density.

Description

Ultra-high fake specific gravity polyvinyl chloride powder and preparation method thereof

The present invention relates to a polyvinyl chloride powder, in particular to a polyvinyl chloride powder with high bulk density and a preparation method thereof.

With the development of material science, polymer materials with easy processing, light weight and good mechanical properties are widely used. Among them, because polyvinyl chloride has a simple production process, and it can be easily made into various types of objects by general kneading and molding, polyvinyl chloride is a commonly used polymer material.

Generally, polyvinyl chloride is produced by suspension polymerization in order to balance the convenience of production and applicability. Therefore, the obtained polyvinyl chloride is a powdery material. During kneading and molding, if the pseudo specific gravity of the polyvinyl chloride powder is low, the polyvinyl chloride content per unit volume is less, so the extruded amount after kneading is also less, and the production cost of the product is increased. Secondly, when the PVC is kneaded and formed, the formed PVC article has poor processing properties due to the lower dummy specific gravity, which makes it difficult to meet the application requirements.

In view of this, there is an urgent need to provide an ultra-high dummy specific gravity polyvinyl chloride powder and a manufacturing method thereof, so as to improve the defects of the conventional polyvinyl chloride powder.

Therefore, one aspect of the present invention is to provide a manufacturing method of ultra-high pseudo-gravity polyvinyl chloride powder. The manufacturing method controls the agglomeration rate of suspended cells by adding a polyepoxy compound to the polymerization reaction system. The appearance of the prepared PVC powder can be adjusted and its bulk density can be increased.

Another aspect of the present invention is to provide an ultra-high dummy specific gravity polyvinyl chloride powder, which is produced by the above-mentioned production method.

According to an aspect of the present invention, a method for producing ultra-high dummy specific gravity polyvinyl chloride powder is provided. In this manufacturing method, an initiator is firstly added to the mixed solution, and the mixed solution is continuously stirred to carry out a polymerization reaction to form a polyvinyl chloride slurry. Wherein, when the mixed solution is heated to the reaction temperature, the first polyepoxy compound is added to the mixed solution, and the weight ratio of the amount of the first polyepoxy compound to the dispersant is 0.005 to 2.5. Then, neutralize the polyvinyl chloride slurry, so that the pH value of the polyvinyl chloride slurry is not less than 7. After the neutralization reaction, the polyvinyl chloride slurry is dried to obtain the polyvinyl chloride powder with ultra-high dummy specific gravity.

According to an embodiment of the present invention, the aforementioned dispersant comprises polyvinyl alcohol.

According to another embodiment of the present invention, the alkalinity degree of the aforementioned polyvinyl alcohol is 70% to 90%.

According to another embodiment of the present invention, when the conversion of the aforementioned polymerization reaction When the ratio is 5% to 30%, a second polyepoxy compound is added to the mixed solution.

According to another embodiment of the present invention, after the aforementioned polymerization reaction is carried out for a reaction time, the second polyepoxy compound is added to the mixed solution.

According to yet another embodiment of the present invention, the weight ratio of the total amount of the first polyepoxy compound and the second polyepoxy compound to the dispersant is 0.005 to 2.5.

According to yet another embodiment of the present invention, the aforementioned first polyepoxide compound and/or second polyepoxide compound comprise polyethylene oxide.

According to yet another embodiment of the present invention, the molecular weight of the aforementioned polyethylene oxide is 150,000 to 1,000,000.

According to yet another embodiment of the present invention, when performing the aforementioned polymerization reaction, the stirring speed of the operation of stirring the mixed solution is 50 rpm/min to 110 rpm/min, and the stirring tip speed is 5 m/s to 10 m /s.

According to another aspect of the present invention, an ultra-high dummy specific gravity polyvinyl chloride powder is provided. This polyvinyl chloride powder has a pseudo specific gravity of not less than 0.55 g/cm ³ .

Applying the ultra-high pseudo-gravity polyvinyl chloride powder of the present invention and the preparation method thereof, by adding a polyepoxy compound to the mixed solution to inhibit the coagulation rate of suspended cells dispersed in water, the prepared polyvinyl chloride can be obtained. The appearance of ethylene powder is relatively round, and thus has a higher bulk density, so during mixing, it can effectively increase the extruded amount of polyvinyl chloride, and the obtained polyvinyl chloride has good processing properties.

100: Method

110, 121, 123, 130, 140, 150: Operation

120: Polymerization process

In order to have a more complete understanding of the embodiments of the present invention and their advantages, please refer to the following description together with the corresponding drawings. It must be emphasized that the various features are not drawn to scale and are for illustrative purposes only. The contents of the relevant drawings are described as follows: FIG. 1 is a schematic flow chart showing the manufacturing method of the ultra-high pseudo-gravity polyvinyl chloride powder according to some embodiments of the present invention.

The manufacture and use of embodiments of the present invention are discussed in detail below. It should be appreciated, however, that the embodiments provide many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are provided for illustration only, and are not intended to limit the scope of the invention.

Please refer to FIG. 1 , which is a schematic flow chart of a method for producing ultra-high dummy specific gravity polyvinyl chloride powder according to some embodiments of the present invention. In method 100 , the initiator is first added to the mixed solution, as shown in operation 110 . This mixed solution contains vinyl chloride monomer, dispersant and water. The dispersant can be used to promote the dispersion of vinyl chloride monomer in water to form suspended micelles in the organic phase, which can then be used for subsequent polymerization to form polyvinyl chloride powder. In some specific examples, the dispersing agent can include, but is not limited to, alkalized polyvinyl alcohol, hydroxypropyl methylcellulose, other suitable dispersing agents and any mixture of the above materials. Wherein, the alkalization degree of the alkalized polyvinyl alcohol may be 70% to 90%. When the alkalinity of the polyvinyl alcohol used as the dispersant is within the aforementioned range, the vinyl chloride monomer can be easily dispersed in water, thereby improving the falseness of the prepared polyvinyl chloride powder. proportion. In some embodiments, based on 100 parts by weight of vinyl chloride monomer, the amount of dispersant used may be 0.02 parts by weight to 0.2 parts by weight, and preferably 0.04 parts by weight to 0.1 parts by weight. When the amount of the dispersant used is within the aforementioned range, the vinyl chloride monomer is more likely to form suspended micelles and be uniformly dispersed in water, which is helpful for the subsequent suspension polymerization reaction, and can make the prepared polyvinyl chloride The powder has an appropriate particle size. The amount of water used in the present invention is not particularly limited, as long as the vinyl chloride monomer can be dispersed in water by means of a dispersant to form suspended micelles.

The initiator of the present invention is preferably a thermally decomposable initiator. In some embodiments, the initiator may include, but is not limited to, tert-butyl peroxyoctanoate, 3,5,5-trimethylhexene, other suitable initiators, or any combination of the above compounds. In some embodiments, based on 100 parts by weight of vinyl chloride monomer, the amount of initiator used is 0.002 parts by weight to 0.2 parts by weight, and preferably 0.005 parts by weight to 0.1 parts by weight. If the usage amount of the initiator is less than 0.002 parts by weight, the vinyl chloride monomer dispersed in the suspended micelles in the aqueous phase is not easy to produce a polymerization reaction, so that the polyvinyl chloride powder cannot be obtained. If the amount of the initiator used is more than 0.2 parts by weight, although the vinyl chloride monomer in the suspended micelles can produce a polymerization reaction, the reactivity of the polymerization reaction is not easy to control, and the molecular weight of the prepared polyvinyl chloride powder is increased, and further Unable to meet application requirements. In operation 110, the initiator is added to the aforementioned mixed solution in one injection.

After the operation 110 is performed, the polymerization process 120 is performed. Wherein, the mixed solution containing vinyl chloride monomer, initiator, dispersant and water is continuously stirred, and a temperature rise step is performed to heat the mixed solution to the reaction temperature, As shown in operation 121 . It can be understood that the so-called "reaction temperature" refers to the temperature at which the aforementioned initiator begins to decompose to generate free radicals, and the generated free radicals can be used to induce the reaction polymerization of vinyl chloride monomer into polyvinyl chloride. Therefore, the reaction temperature will vary depending on the type of initiator used. For example, the reaction temperature may be 51°C to 53°C. After the operation 121 is performed, when the temperature of the mixed solution reaches the reaction temperature, the first polyepoxy compound is added to the mixed solution, as shown in the operation 123 . When the temperature reaches the reaction temperature, the vinyl chloride monomer dispersed in the suspended micelles in the water starts to polymerize, so the first polyepoxy compound is added to the mixed solution at 0 minutes of reaction. In some embodiments, the first polyepoxide compound may include, but is not limited to, polyethylene oxide, polypropylene oxide, polybutylene oxide, other suitable polyepoxide compounds, or any mixture of the foregoing materials. In other embodiments, the first polyepoxide compound comprises at least polyethylene oxide. When the first polyepoxide compound contains at least polyethylene oxide, the coagulation speed of the suspended cells of the vinyl chloride monomer dispersed in water can be effectively controlled, and the powder of the subsequently formed polyvinyl chloride powder can be adjusted. The appearance of the body is improved, and the false specific gravity of the obtained PVC powder is increased.

The molecular weight of the first polyepoxy compound may be 150,000 to 1,000,000, preferably 1,000,000 to 8,000,000, and more preferably 4,000,000 to 5,000,000. When the molecular weight of the first polyepoxy compound is within the aforementioned range, the first polyepoxy compound can avoid the agglomeration of suspended cells, and can adjust the appearance size of the prepared polyvinyl chloride powder, thereby improving the properties of the polyvinyl chloride powder. False specific gravity.

In some embodiments, the usage amount based on vinyl chloride monomer is 100 In parts by weight, the use amount of the first polyepoxy compound is greater than 0 part by weight and less than or equal to 0.05 part by weight, and preferably 0.001 part by weight to 0.01 part by weight. When the use amount of the first polyepoxy compound is within the aforementioned range, the coagulation speed of the suspended cells can be controlled more easily, and the pseudo-specific gravity of the polyvinyl chloride powder can be increased.

In order to further increase the pseudo-specific gravity of the polyvinyl chloride powder, the weight ratio of the amount of the first polyepoxy compound to the amount of the dispersant can be 0.005 to 2.5, preferably 0.025 to 1.25, and more preferably 0.025 to 0.1. When the ratio of the first polyepoxy compound to the dispersant is within the aforementioned range, in addition to the adjustment of the coagulation speed of the suspended cells, the dispersing effect can be improved, and the pseudo-specific gravity of the polyvinyl chloride powder can be further improved .

In some embodiments, the method 100 of the present invention can selectively add a second polyepoxy compound to the mixed solution after the polymerization reaction is carried out for a period of time. Wherein, when the conversion rate of the polymerization reaction is 5% to 30%, the second polyepoxy compound is added to the mixed solution. When the conversion ratio is within the aforementioned range, the added second polyepoxy compound can further control the aggregation rate of the unreacted suspended micelles, and adjust the appearance of the formed polyvinyl chloride powder, thereby increasing its bulk density. In some embodiments, the second polyepoxy compound may preferably be added at a conversion rate of 5% to 25% in the polymerization reaction, and more preferably may be added at a conversion rate of 5% to 20%. In other embodiments, the second polyepoxy compound may be added to the mixed solution when the reaction time of the polymerization reaction is 30 minutes to 60 minutes. For example, when the polymerization reaction is performed for 30 minutes, 45 minutes or 60 minutes, the second polyepoxy compound is added to the mixed solution.

The aforementioned second polyepoxy compound may be added to the mixed solution at one time or in portions. Preferably, the second polyepoxy compound is added to the mixed solution at one time.

The aforementioned second polyepoxy compound may include, but is not limited to, polyethylene oxide, polypropylene oxide, polybutylene oxide, other suitable polyepoxide compounds, or any mixture of the above materials. In some embodiments, the second polyepoxide compound comprises at least a polyepoxide compound. In some embodiments, the second polyepoxide compound may be the same or different from the aforementioned first polyepoxide compound. In some embodiments, the molecular weight of the second polyepoxy compound may be 150,000 to 1,000,000, preferably 1,000,000 to 8,000,000, and more preferably 4,000,000 to 5,000,000.

Based on 100 parts by weight of the vinyl chloride monomer, the total amount of the first polyepoxy compound and the second polyepoxy compound can be greater than 0 parts by weight and less than or equal to 0.05 parts by weight, and preferably 0.001 parts by weight to 0.01 parts by weight. The weight ratio of the first polyepoxy compound to the second polyepoxy compound is not particularly limited, but in order to further enhance the effect of the first polyepoxy compound and the second polyepoxy compound in inhibiting the aggregation of suspended cells, the first The weight ratio of the first polyepoxide compound to the second polyepoxide compound may be 1:1 to 5:1, preferably 2.5:1 to 5:1, and more preferably 4:1 to 4.5:1.

As mentioned above, in order to increase the false specific gravity of the polyvinyl chloride powder, the weight ratio of the total amount of the first polyepoxy compound and the second polyepoxy compound to the amount of the dispersing agent can be 0.005 to 2.5, preferably is 0.025 to 1.25, and more preferably 0.025 to 0.1.

During the polymerization reaction, the mixed solution was continuously stirred. Wherein, the stirring speed can be 50rpm/min to 110rpm/min, and preferably can be 70rpm/min to 90rpm/min; and the stirring speed can be 5m/s to 10m/s, and preferably 6m/s to 8m/s. When the stirring speed and/or the stirring wing tip speed are within the aforementioned ranges, the shear force on the mixed solution is weak (that is, the mixed solution is in a state of low disturbance), so the applied shear force will not easily affect the dispersion. In addition to the effect of the dispersant and the first polyepoxy compound (and the second polyepoxy compound) on the dispersion of suspended cells and inhibiting agglomeration, the weaker shear force also helps to uniformly mix the dispersant and the first polyepoxy compound. compound (and a second polyepoxy compound).

Please continue to refer to Figure 1. After the polymerization reaction in the polymerization process 120 is completed, the unreacted vinyl chloride monomer is removed, and the formed polyvinyl chloride slurry is subjected to a neutralization reaction, so that the pH value of the polyvinyl chloride slurry is not less than 7. 130 shown. In some embodiments, the completion of the polymerization reaction can be judged by the pressure drop of the system. For example, when the pressure of the system drops to 1.5 kg, it can be judged that the polymerization reaction has been completed.

During the neutralization reaction, the basic compound is added to the PVC slip to adjust the pH of the PVC slip. It can be understood that the prepared PVC slurry may contain PVC powder and a solvent (ie, water), so in some embodiments, in order to effectively separate the PVC powder and the water, and improve the efficiency of the neutralization reaction, the basic compound used in the neutralization reaction is preferably an alkaline aqueous solution. In some specific examples, the basic compound used in the neutralization reaction may include, but is not limited to, ammonia water, sodium hydroxide aqueous solution, other suitable alkaline aqueous solutions, or any of the above compounds mix.

After the neutralization reaction, the polyvinyl chloride slurry is dried to obtain the ultra-high-pseudo-gravity polyvinyl chloride powder of the present invention, as shown in operation 140 and operation 150. During the drying process, the polyvinyl chloride slurry can first be removed by centrifugal dehydration to remove the slurry solvent (ie water), and then the dehydrated wet polyvinyl chloride powder can be dried to improve the efficiency of the drying process. In some embodiments, the temperature of the drying step may be 70°C, and the drying time may be 2 hours.

In some application examples, according to the measurement method of Japanese Industrial Standards (JIS) No. K6721, the polyvinyl chloride powder prepared by the present invention has a false specific gravity of not less than 0.55 g/cm ³ , and can be It has higher extrusion volume and better processing properties when used in back-end applications. In other application examples, the pseudo-specific gravity of the polyvinyl chloride powder of the present invention may be 0.57 g/cm ³ to 0.60 g/cm ³ .

The following examples are used to illustrate the application of the present invention, but it is not intended to limit the present invention. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention.

Preparation of ultra-high dummy specific gravity polyvinyl chloride powder

Example 1

First, mix 8.3 kg of vinyl chloride monomer and 0.007 kg of dispersant (including commercially available products of Synthomer, model ALCOTEX B72; Shin-Etsu Chemical Industry Co., Ltd., hydroxypropyl methylcellulose, model 60SH-50) ; and a commercial product manufactured by Changchun Group, model BC-20) and 16.6 kg of water to form a mixed solution. Then, 0.008 kg of an initiator was added to the mixed solution, and the temperature was raised to 51° C. to 53° C. to carry out a polymerization reaction. When the temperature was raised to 51°C to 53°C (ie, at 0 minutes of reaction), 0.00008 kg of polyethylene oxide was added to the mixed solution. When the pressure drop reaches 1.5 kg, the unreacted vinyl chloride monomer in the formed PVC slurry is removed, and ammonia water is added to the PVC slurry to adjust the pH value to 7. Next, the water of the PVC slurry is removed, and it is dried with a small fluidized bed dryer. After drying at 70° C. for 2 hours, the polyvinyl chloride powder of Example 1 can be obtained, and its bulk density is 0.550 g/cm ³ .

Example 2

Example 2 uses the same preparation method as the production method of the polyvinyl chloride powder in Example 1, the difference is that when the polymerization reaction is carried out for 30 minutes (reaction conversion rate is 10%), an additional 0.0003 kg of polyepoxy is added. Ethane was added to the mixed solution, and the polymerization reaction continued. After the neutralization reaction and drying process, the polyvinyl chloride powder of Example 2 can be obtained, and its bulk density is 0.578 g/cm ³ .

Example 3

Example 3 uses the same preparation method as the preparation method of the polyvinyl chloride powder of Example 1, the difference is that when the polymerization reaction is carried out for 45 minutes (reaction conversion rate is 15%), an additional 0.0003 kg of polycyclic ring is added. Ethylene oxide was added to the mixed solution, and the polymerization reaction continued. After the neutralization reaction and the drying process, the polyvinyl chloride powder of Example 3 can be obtained, and its bulk density is 0.600 g/cm ³ .

Example 4

Example 4 uses the same preparation method as the production method of the polyvinyl chloride powder of Example 1, the difference is that when the polymerization reaction is carried out for 45 minutes (reaction conversion rate is 20%), an additional 0.0003 kg of polycyclic ring is added. Ethylene oxide was added to the mixed solution, and the polymerization reaction continued. After the neutralization reaction and the drying process, the polyvinyl chloride powder of Example 4 can be obtained, and its bulk density is 0.560 g/cm ³ .

Extrusion amount

The amount of extrusion is to mix the polyvinyl chloride powder prepared in Examples 1 to 4 by a method well known to those skilled in the present invention and an extruder, and measure the amount of extrusion in each example. Among them, based on the amount of extrusion in Example 1, the amount of extrusion in Example 2 can be increased by 6%, the amount of extrusion in Example 3 can be increased by 9%, and the amount of extrusion in Example 4 can be increased by 3%.

Accordingly, the polyvinyl chloride powder of the present invention has a higher pseudo-specific gravity, and can have a higher extruded amount during kneading and molding. Secondly, because the obtained polyvinyl chloride powder has a higher pseudo-specific gravity and a denser structure, the polyvinyl chloride material extruded by kneading can have better processing properties.

According to the above description, the polyvinyl chloride powder prepared by the method for producing the polyvinyl chloride powder of the present invention has a bulk density of not less than 0.55 g/cm ³ , and can have better processing properties. Among them, by adding the polyepoxy compound, the agglomeration rate of the suspended cells dispersed in the water can be controlled, so that the appearance of the prepared polyvinyl chloride powder can be rounded, and its bulk density can be increased. Secondly, because the obtained polyvinyl chloride powder has a higher pseudo specific gravity, it has a higher extrusion amount and better processing properties during kneading and molding.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the technical field to which the present invention pertains can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the appended patent application.

100: Method

110, 121, 123, 130, 140, 150: Operation

120: Polymerization process

Claims (8)

A method for producing ultra-high dummy specific gravity polyvinyl chloride powder, comprising: adding a thermal decomposition type initiator to a mixed solution, wherein the mixed solution comprises vinyl chloride monomer, a dispersant and water; adding the thermal decomposition type initiator to a mixed solution After the initiator, the mixed solution is continuously stirred, and a polymerization reaction is carried out to form a polyvinyl chloride slurry, wherein when the mixed solution is heated to a reaction temperature, a first polyepoxy compound is added to the mixed solution, To control the coagulation speed of the vinyl chloride monomer in the mixed solution, and a weight ratio of one of the first polyepoxy compound and one of the dispersing agent is 0.005 to 2.5, and when one of the polymerization reactions is converted The ratio is 5% to 30%, or after the polymerization reaction is carried out for 30 minutes to 60 minutes, a second polyepoxy compound is added to the mixed solution; the polyvinyl chloride slurry is subjected to a neutralization reaction, so that the The pH value of the polyvinyl chloride slurry is not less than 7; and after the neutralization reaction, a drying process is performed on the polyvinyl chloride slurry to obtain the ultra-high-density polyvinyl chloride powder. The method for producing ultra-high pseudo-gravity polyvinyl chloride powder according to claim 1, wherein the dispersant comprises polyvinyl alcohol. The method for producing ultra-high pseudo-gravity polyvinyl chloride powder according to claim 2, wherein the alkalinity of the polyvinyl alcohol is 70% to 90%. The method for producing ultra-high pseudo-gravity polyvinyl chloride powder as claimed in claim 1, wherein the weight ratio of the total usage of the first polyepoxy compound and the second polyepoxy compound to a weight ratio of the dispersant is 0.005 to 2.5. The manufacturing method of the ultra-high pseudo-gravity polyvinyl chloride powder according to claim 1, wherein the first polyepoxide compound and/or the second polyepoxide compound comprise polyethylene oxide. The manufacturing method of the ultra-high pseudo-gravity polyvinyl chloride powder according to claim 5, wherein the molecular weight of the polyethylene oxide is 150,000 to 1,000,000. The method for producing ultra-high pseudo-gravity polyvinyl chloride powder according to claim 1, wherein during the polymerization reaction, a stirring speed of the operation of stirring the mixed solution is 50 rpm/min to 110 rpm/min, and a stirring The tip speed is 5m/s to 10m/s. A kind of ultra-high dummy specific gravity polyvinyl chloride powder, obtained by the manufacturing method as described in any one of the application for patent scope 1 to 7, wherein the ultra-high dummy specific gravity polyvinyl chloride powder has not less than 0.55g Bulk density of /cm ³ .

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