JPH0220654B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a chlorinated polyvinyl chloride resin (hereinafter abbreviated as CPVC) foam. CPVC foam has excellent properties such as flame retardancy, electrical insulation, and chemical resistance. As a manufacturing method, for example, there is a method as described in Japanese Patent Publication No. 43-12009, but according to the invention, the density
16-24 at a temperature of 80°C when impregnating 0.05-0.07 g/ml of organic volatile blowing agent necessary for foam production.
It takes time, requires large impregnation equipment in the manufacturing process, and consumes a lot of thermal energy for impregnation. Furthermore, since the CPVC used is in powder form and has a very large surface area, the impregnated organic volatile foaming agent scatters heavily and lacks storage stability.
As a result, there were many drawbacks such as loss of foaming agent and variation in foam density. As a result of intensive studies in view of these problems, the inventors of the present invention have found that in a method of impregnating CPVC with an organic volatile blowing agent, chlorinated polyethylene or chloroprene is added as a modifier to CPVC and pelletized. This greatly shortens the impregnation time and suppresses the scattering of the impregnated organic volatile blowing agent, resulting in extremely efficient and stable production of 0.03 to 0.04 g/ml.
We have discovered that a highly foamed CPVC composition can be produced, and have arrived at the present invention. That is, the present invention has an impregnation content of 60 to 75% by weight.
By adding chlorinated polyethylene or chloroprene as a modifier to CPVC and pelletizing it, the composition has a solubility index (SP value) of 7.5 to 7.5.
8.4 and a boiling point of 0°C or higher and 30°C or lower by impregnating the product in a short time with 5 to 50% by weight of an organic volatile blowing agent, suppressing the scattering of the impregnated foaming agent, and efficiently and stably heating and extruding foaming. The content is a method for producing a CPVC composition foam characterized by the following. The details will be explained below. Chlorinated polyethylene or chloroprene as a modifier used in the present invention not only disperses uniformly with CPVC and promotes impregnation of the blowing agent, but also
This has the effect of minimizing the decrease in flame retardancy, which is a characteristic of CPVC. In the present invention, CPVC is pelletized by adding chlorinated polyethylene or chloroprene and impregnated with a blowing agent. twenty three
The residual ratio of the impregnated foaming agent after being left for 20 hours at
It is necessary to select the amount of chlorinated polyethylene or chloroprene added to CPVC with respect to the type of blowing agent used so that it is 0.5 or more, preferably 0.7 or more. Regarding the amount added, if it is too small, the promotion of blowing agent impregnation will not be noticeable, and if it is too large, the scattering of the impregnated blowing agent will increase, so it is preferable that the amount added is in the range of 5 to 30 parts by weight. . In addition to CPVC, additives such as stabilizers, lubricants, and foam regulators may be appropriately mixed into the CPVC composition of the present invention. CPVC used in the present invention refers to a chlorinated polyvinyl chloride resin, and can be easily produced by post-chlorinating a commercially available polyvinyl chloride resin. this
CPVC has an average degree of polymerization of 100-2000 and a chlorine content of 60
~75% by weight, more preferably an average degree of polymerization of 500-1000 and a chlorine content of 63-70
Weight%. As the stabilizer, tin-based stabilizers are preferred, and butyltin laurate, butyltin maleate, and dibutyltin laurate maleate are particularly preferred. As the lubricant, any known lubricant may be used, including fatty acids, fatty acid amides, fatty acid esters, aliphatic ketones, aliphatic alcohols, and the like. Examples of the bubble control agent include inorganic substances such as talc, calcium carbonate, and silica, or those consisting of a combination of an organic acid and sodium or ammonium bicarbonate or carbonate. The mixing and pelletizing of chlorinated polyethylene or chloroprene with CPVC in the present invention involves hot blending the CPVC, chlorinated polyethylene or chloroprene, stabilizers, lubricants, etc.
Thereafter, the mixture is kneaded using an extruder or heated rolls to form pellets, but any known hot blending method or pelletizing method may be used. The blowing agent used in the present invention has a solubility index (SP value) of 7.5 to 8.4 and a boiling point of 0°C or higher and 30°C.
An organic volatile blowing agent selected from the following, preferably trichlorofluoromethane, dichlorofluorometal, etc. When using the blowing agent, it is possible to mix it with other blowing agents as long as the solubility index and boiling point are within the limits. In the present invention, the pellet-like CPVC composition is adjusted by impregnating the foaming agent, and the amount of the foaming agent impregnated into the CPVC composition is determined depending on the density of the foam to be finally obtained. selected in the range of 5 to 50 parts by weight,
Usually 20 to 40 parts by weight. Any known method may be used for impregnating the foaming agent, and the pellets are placed in a pressure-resistant container that can be rotated so as to impart a rolling motion to the pellets, or a pressure-resistant container equipped with a mixing device. A method of introducing a blowing agent and heating is desirable. It is necessary that this heating range does not exceed the melting point of the composition pellets. After impregnating the foaming agent by heating for a certain period of time, the pressure-resistant container is cooled, the pressure inside the container is returned to atmospheric pressure, and the contents are taken out and dried with ventilation at room temperature.
Blowing agent impregnated CPVC composition pellets are obtained. In the present invention, the foaming agent-impregnated CPVC composition pellets obtained as described above are heated and extruded and foamed using an extruder, thereby making it possible to continuously produce a foam having uniform and fine cells.
In this case, the area near the hopper of the extruder is kept at a relatively low temperature, and the tip of the cylinder is kept at a higher temperature than the area near the hopper.
Preferably keep it at 100-200℃, mold temperature 120-200℃
It is preferable to adjust the temperature to 180°C. In addition, the composition of the present invention has a lower melt viscosity than a CPVC composition that does not contain a modifier, so the temperature inside the extruder can be lowered by 5 to 30 °C, preventing thermal decomposition of CPVC, Another major feature is that it provides long-term extrusion stability. As described above, by the method of the present invention, a chlorinated polyvinyl chloride resin foam with a foam density of 0.07 to 0.03 g/ml and a high expansion ratio can be stably produced. Of course, chlorinated polyvinyl chloride resin foams having a relatively low expansion ratio of more than 0.07 g/ml can also be produced easily and stably. Next, the present invention will be explained in more detail with reference to Examples. Examples 1 to 4, Comparative Examples 1 to 2 Chlorinated polyvinyl chloride (chlorine content 66%, degree of polymerization 700) was added with 0 to 30 parts by weight of a modifier, 4.0 parts by weight of a tin-based stabilizer, and 1.0 parts by weight of a lubricant. Then, hot blend at 110℃, feed this to an extruder, and
Cylindrical pellets with a length of 4 mm and a length of 4 mm were prepared. The pellets were placed in a pressure container, trichlorofluoromethane was introduced as a blowing agent, and the
℃ for 4 hours to impregnate the foaming agent. The amount of blowing agent impregnated in the blowing agent-impregnated pellets and 23
The remaining amount after being left at ℃ for 20 hours was examined, and the results are shown in Table 1. Next, 0.5 parts by weight of talc was blended with 100 parts by weight of the CPVC composition pellets impregnated with a foaming agent, and this mixture was extruded to form a round rod-shaped foam. When the density and appearance of this foam were examined, the results shown in Table 1 were obtained.

[Table] W ₀
If the amount of the modifier added is 3 parts by weight, the effect of accelerating the impregnation rate of the blowing agent cannot be obtained, and if the amount is 30 parts by weight or more, the remaining amount of the impregnated blowing agent becomes small, and a suitable foam cannot be obtained. The type of extruder and extrusion conditions are as follows. Screw diameter 40mm Screw length 720mm Screw compression ratio 3.0 Die hole diameter 10mm Cylinder temperature C ₁ = 60 to 150℃ C ₂ = 120 to 150℃ Die temperature D = 130 to 150℃ Rotation speed 10 to 12 times/min Example 5, Comparative Examples 3 to 4 Pellets of the same CPVC composition as in Example 1 were placed in a pressure container, an organic volatile blowing agent was introduced, and the pellets were heated at 80° C. for 4 hours with stirring to impregnate the pellets with the blowing agent. The amount of blowing agent impregnated in the blowing agent-impregnated pellets and
The amount remaining after being left at 23°C for 20 hours was determined, and the results are shown in Table 2.

[Table] Compared to the impregnation rate and residual amount of trichlorofluoromethane with a solubility index of 7.6, the solubility index is
6.8, n-butane has a very slow impregnation rate;
Furthermore, although the impregnation rate of ethyl chloride with a solubility index of 9.2 is higher than that of trichlorofluoromethane, it lacks storage stability, and neither of them satisfies the conditions for obtaining a suitable foam. Example 6, Comparative Examples 5 to 6 The same CPVC composition pellets as in Example 1 and Comparative Example 1 were placed in a pressure container, trichloromonofluoromethane was introduced as a blowing agent, and the pellets were heated at 80°C for 5 hours or at 80°C. , heated for 16 hours to impregnate the blowing agent. 0.5 parts by weight of talc was added to the foaming agent-impregnated pellets, and a sheet-like foam was molded using the extruder shown below. When the density and characteristics of this foam were investigated, the results shown in Table 3 were obtained.

【table】

[Table] Under the same impregnation conditions in a form that does not contain a modifier, the amount of blowing agent impregnated is insufficient, the expansion ratio is low, the melt viscosity in the extruder increases, and the resin decomposes due to self-heating. Burnt resin is more likely to occur. In addition, in order to impregnate the same amount of foaming agent, 3
This method requires more than twice as much time, leading to problems such as an increase in the size of the impregnation equipment and the consumption of thermal energy for impregnation. Furthermore, when comparing the closed cell ratios of the obtained foams, the modifier-added system shows a much higher closed cell ratio than the modifier-free system. The type of extruder and extrusion conditions are as follows. Screw diameter 65mm Screw length 200mm Screw compression ratio 3.0 Die Circular type Cylinder temperature C ₁ = 60 to 200℃ C ₂ to C ₅ = 130 to 220℃ Die temperature D = 150 to 180℃ Discharge rate 60 to 80Kg/hour

Claims (1)

[Claims] 1. A method for producing a chlorinated polyvinyl chloride resin foam, in which a chlorinated polyvinyl chloride resin composition having a chlorine content of 60 to 75% by weight is added as a modifier to chlorinated polyethylene or Add chloroprene to pelletize and add 5-50% by weight of organic volatile blowing agent.
1. A method for producing a chlorinated polyvinyl chloride resin foam, which comprises impregnating the foam with the following materials and then foaming by heating and extruding the foam. 2 The organic volatile blowing agent has a solubility index (SP value)
7.5 to 8.4, and a boiling point of 0°C or more and 30°C or less.