JPS60264232A - Manufacture of vinyl chloride group resin foamed body including inorganic particles - Google Patents

Abstract

PURPOSE:To improve productivity and economical property by filling a closed mold with foaming component of kneaded mixture of PVC, inorganic particles and a foaming agent and heating the mold under pressure and opening it at the temperature which is higher than the softening temperature of PVC and by having the component foam. CONSTITUTION:A fixed amount of vinyl chloride resin, inorganic particles and foaming agent is well kneaded by a ribbon blender, a double arm type kneader, etc. and the foaming material, thus prepared, is put into a closed mold made of aluminum alloy, etc. and set by a hydraulic driven heating press and heated under pressure. A temperature, time and pressure suitable for the foaming material is selected at this time. Then, while the mold is kept under pressure, the temperature of a pressure heating plate of the press is lowered with a cooling medium like water etc. to the foaming point and the pressure of the mold is removed for the content of the mold to be released to the atmosphere. The temperature suitable for foaming should be lower than the pressure heating temperature and higher than the softening temperature of PVC and it should be the one under which cell collapse does not occur.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a polyvinyl chloride resin foam containing inorganic particles.
Regarding the law. More specifically, the present invention relates to a method for easily and inexpensively producing a foam that contains a large amount of inorganic particles and has low calorific value, smoke emission, and gas toxicity during combustion.

[Prior Art] Conventionally, as a method for manufacturing polyvinyl chloride resin (hereinafter referred to as PVC) foam, for example, ■ a composition consisting of PVC, a blowing agent, a stabilizer, etc. is used as it is or as a preformed product such as a roll sheet. After filling a closed mold and heating it under pressure, the mold is cooled under pressure to below the softening concentration of PVC, the contents (primary foam) are removed, and the mold is reheated with hot air or hot water. Heat it 2
The so-called high-pressure two-stage method for subsequent foaming: ■ A composition consisting of PVC1 decomposition type blowing agent, isocyane-1~, acid anhydride, etc. is made into a primary foam in the same manner as the high-pressure two-stage method, and then hot water or A so-called crosslinking method in which secondary foaming is achieved by reheating with steam and causing a three-way crosslinking reaction between isocyanate, acid anhydride, and water ■Composition consisting of PVC, acrylic processability improver, nucleating agent, etc. The so-called extrusion method involves supplying the material to an extruder and foaming the composition by pressurizing an evaporative foaming agent into the composition heated and melted in the extruder.■ PVC plastisol is cooled and heated with an inert gas such as carbon dioxide. There is a so-called elastomer method in which a gas-absorbing plastisol that has been mechanically stirred and absorbed under pressure is foamed by heating with high frequency or the like.

However, if a large amount of inorganic particles are included in a foam, moldability becomes extremely poor, so it is difficult to economically obtain a good foam using either method. .

For example, as an application of the high-pressure two-stage method,
No. 76 and Japanese Patent Publication No. 53-7944 disclose a method for producing a PVC foam containing a large amount of inorganic particles.

However, in these methods, the mold is cooled and the primary foam is taken out according to the procedure of the normal high-pressure two-stage method, and then reheated to perform the secondary foaming. There is a temperature distribution in which the temperature near the surface is high and gradually decreases toward the center, which causes a difference in the foaming speed between the near surface and the center, causing shrinkage in the foam.
In extreme cases, the surface layer may even peel off. Furthermore, in order to cool the primary foam to near room temperature, that is, below the softening temperature of PVC, a large amount of cooling medium is required, and the mold and press pressure plate become cold. The amount of energy used to reheat the water also increases. This also means that it takes time to cool down the mold and raise the temperature, which lengthens the production cycle and reduces productivity. Moreover, the amount of heat required for secondary foaming is considerable.

In this way, Japanese Patent Publication No. 52-26776 and Japanese Patent Publication No. 52-26776,
The method disclosed in Publication No. 3-7944 has drawbacks in terms of product quality, productivity, and economy.

[Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned circumstances, and when producing a foam from a PvC foamable composition containing a large amount of inorganic particles, This was done in order to eliminate problems such as poor productivity and economy caused by the method, and shortcomings in the quality of the resulting foam.

Means for Solving Problem E] The present invention involves filling a foamable composition in which PVC1 inorganic particles and a foaming agent are kneaded into a closed vine mold and heating it under pressure.
The above drawbacks are solved by opening the mold at a temperature higher than the softening temperature of PVc to cause foaming.

That is, in the present invention, the mold is opened at a temperature higher than the softening temperature of PvC, and the foaming force of the foaming agent contained in the molded object is used to cause foaming to occur from deep within the molded object, eliminating the need for secondary foaming. In addition, since the mold and press pressure plate do not have to be completely cooled, the cooling time is shortened, reducing the amount of energy used to reheat them during subsequent production, and shortening the temperature rise time. Regarding the method for producing PVC foam containing inorganic particles, the resulting foam contains a large amount of inorganic particles, so the amount of heat generated during combustion, the amount of smoke emitted,
It is characterized by low toxicity of generated gas.

-4- [Example] The PVC used in the present invention has a vinyl chloride content of 50
% (by weight, hereinafter the same) or more, such as polyvinyl chloride, vinyl chloride and vinyl acetate,
Examples include copolymers with vinylidene chloride, acrylic esters, methacrylic esters, and the like. These P
Any of the VCs can be used alone or in combination, but among these, those called base resins, for example those with an average particle size of 01'2 to 5 mm, preferably 0.5 to 2.0 mm, are particularly suitable. ing. When a paste resin is mixed with a resin other than the above-mentioned base resin, it is preferable that the paste resin is contained in an amount of 50% or more.

The inorganic particles used in the present invention have average particle diameters o, oi
There is no particular restriction as long as the particles are inorganic particles of ~150 ρ, but from the viewpoint of price and availability, hollow particles such as calcium carbonate, talc, aluminum hydroxide, magnesium hydroxide, asbestos, rock wool, or shirasu balloons are preferred. These are preferably used alone or in combination. It is preferable to treat these inorganic particles with a silane-based, titanate-based, fatty acid-based, or other surface treatment agent because they have good affinity with PvC. The ratio of PVC/inorganic particles used is 70/30 to 5/95, preferably 50/50 to 5/95, more preferably 30/95 by weight.
Selected in the range of 70 to 5/95.

Examples of the blowing agent used in the present invention include evaporative blowing agents and decomposable blowing agents.

The evaporative foaming agent may be one having a boiling point lower than the softening temperature of PVC in the foamable composition, such as propane, n-butane, 1-butane, n-pentane, i-pentane, neopentane, n- -Aliphatic hydrocarbons such as hexane, aliphatic halogenated hydrocarbons such as methyl chloride, methylene chloride, trichloroethylene, trichlorofluoromethane, difluoromethane, etc.
8a, f, 3ゎ.

Examples of the decomposable blowing agent include azodicarbonamide, azobisisobutyronitrile, diazoaminobenzene, N,N''-dinitrosopentamethylenetetramine, and p-toluenesulfonylhydrazide.

The amount of the blowing agent used varies depending on the desired expansion ratio and the type of blowing agent, but usually the total amount of PvC and inorganic particles is 1
00 parts (by weight, the same applies hereinafter), 2 to 60 parts when using an evaporative blowing agent, preferably 5 to 40 parts when using a decomposable blowing agent, and 0.1 to 50 parts when using a decomposable blowing agent. , preferably 1 to 30 parts, and when an evaporative blowing agent and a decomposable blowing agent are used together, the evaporative blowing agent is 2 to 50 parts, preferably 5 to 30 parts, and the decomposable blowing agent is 0. It is preferred to use it in a range of 1 to 30 parts, preferably 0.1 to 10 parts.

Note that when a decomposable foaming agent is used, it may be used in combination with a foaming aid.

In the present invention, it is of course possible to use solvents, plasticizers, stabilizers, pigments, etc. that have a swelling effect on PvC as necessary.

Specific examples of the solvent include benzene, toluene, 0-xylene, p-xylene, and chlorobenzene, which may be used alone or in combination of two or more. . The amount of the solvent used is usually 0 to 100 parts, preferably 30 to 60 parts, based on 100 parts of the total amount of PVC and inorganic particles.

Next, the present invention will be explained in detail.

A foamable composition is prepared by blending predetermined amounts of each raw material and thoroughly kneading the mixture using a ribbon blender, a double-arm kneader-1 pressure kneader, a Banbury mixer, or the like.

The prepared foamable composition is filled into a closed mold made of aluminum alloy or the like, and the mold is set in a hydraulically driven heating press to heat the composition under pressure.

Pressure and heating conditions vary depending on the content of the composition, but when using a decomposition type foaming agent and an evaporation type foaming agent together, PVC
It is necessary to substantially complete the melting of the foaming agent and the decomposition of the decomposable foaming agent.
The pressure is selected, and then, while the mold remains pressurized, the humidity of the pressure heating plate of the press is lowered to a temperature suitable for foaming using a cooling medium such as water.

The temperature suitable for foaming varies depending on the composition, but it is lower than the above-mentioned pressure heating temperature, higher than the softening temperature of PVC, and melting of PvC that does not cause foaming gas to escape due to tearing of the cell membrane during foaming. It is necessary that the temperature is such that it gives a viscous mark, for example, about 50 to 170°C.

Once the mold temperature has fallen to a predetermined foaming temperature, the mold is depressurized and the mold contents are released to atmospheric pressure.

Since the mold contents have the foaming power of the foaming agent and the PVC has a temperature higher than the softening temperature, the mold contents expand and foaming is completed in a short time.

When only a decomposable blowing agent is used as a blowing agent, the pressure and heating conditions must be such that the melting of PVC and the decomposition of the decomposable blowing agent are substantially completed, and then the foaming temperature exceeds the softening point of PVC. After adjusting the temperature to the appropriate temperature, the mold is depressurized,
The contents may be foamed.

In addition, using only an evaporative foaming agent as a foaming agent 7-1
0 - If the PvC is melted, the temperature is adjusted to a temperature suitable for foaming, which is higher than the boiling point of the blowing agent and higher than the softening point of PVC, and the mold is depressurized to foam the contents. That's fine.

According to the method of the present application, a desired foam can be easily produced by only secondary foaming, but the primary foam obtained by the present invention may be subjected to secondary heating as an auxiliary method.

The foam thus obtained has an expansion ratio of about 5 to 50 times, and a density of 0.5 to 0.05 g/ci3, depending on the cloudiness of the inorganic particles contained in the foamable composition.
It is a trace of progress.

Next, the manufacturing method of the present invention will be explained based on Examples, but the present invention is not limited to these Examples.

Examples 1 to 3 The raw materials shown in Table 1 were mixed in the proportions shown in Table 2 so that the total amount was 500 g, and the effective capacity was 112 g.
The mixture was kneaded for 55 minutes using a closed double-arm kneader.

During this time, cold water was passed through the kneader jacket to maintain the temperature of the composition in the range of 15 to 20°C. The mixed composition was filled into a sealed aluminum alloy mold with a cavity size of 170 x 90 x 15 g+a, set in a hydraulically driven heating press machine, and heated from room temperature to 175° C. in 5 minutes. The clamping pressure of the press is approximately 250ko per mold area I CD12.
Met.

After holding at 175°C for 40 minutes, cold water was passed through the press cooling plate to lower the mold temperature to 100°C in 6 minutes.
The temperature was maintained at 100° C. for 10 minutes.

When the clamping pressure of the press was then released, the contents of the mold completed foaming in about 4 seconds.

Visual appearance (shrinkage) of the resulting foam, cell uniformity on cut surfaces, and apparent density were measured by the following method. The results are shown in Table 2.

(Apparent density) Cut out a 20 ui square cube from the molded product, measure the volume and weight, and calculate the weight/volume.

Comparative Examples 1-2 Hold at 175°C for 40 minutes using a heating press machine -11
- After that, it was cooled to 25°C over 30 minutes. Next, a primary foam was obtained using the same raw materials and processing conditions as in Example 1, except that the press clamping pressure was released, the mold was opened, and the contents (primary foam) were taken out.

In Comparative Example 1, when the primary foam was reheated for about 30 minutes using hot air in an oven at 110°C, it foamed non-uniformly and then shrank, resulting in a shape that made it difficult to measure the apparent density. .

In Comparative Example 2, when the primary foam was reheated in hot water at 97°C for about 10 minutes, it rapidly foamed non-uniformly and then rapidly shrunk, and part of the surface layer peeled off, resulting in no commercial value at all. The result was a foam with no foam.

The results are shown in Table 2.

Margin below E 1 - 12 - [Effects of the Invention] According to the manufacturing method of the present invention, a PVC foam having a good shape and containing a large amount of inorganic particles can be manufactured easily, efficiently, and economically. can.

-16- 180-

Claims (1)

[Claims] 1 A foamable composition obtained by kneading a vinyl chloride resin, inorganic particles, and a blowing agent is filled into a sealable mold and heated under pressure, and the mold is heated at a temperature higher than the softening temperature of the vinyl chloride resin. A method for producing a vinyl chloride resin foam containing inorganic particles, which is characterized by foaming by opening a mold.