JPS5830902B2 - Stabilization method for chlorine-containing resins - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improving the thermal stability of chlorine-containing resins.

More specifically, by blending lightly acetylated dipentaerythritol as a stabilizing agent with calcium-zinc or barium-zinc stabilizers, which are used in general processing formulations of chlorine-containing resins, chlorine-containing resins can be processed. This is a chlorine-containing resin composition that prevents thermal deterioration and thermal coloring and has improved stability during processing.

Chlorine-containing resins have been processed by adding various stabilizers such as cadmium-based and lead-based stabilizers because they change color due to heat and light, but recently, environmental and hygienic contamination due to heavy metals has become a problem. The use of cadmium-based and lead-based stabilizers is either not permitted or is extremely limited.

Furthermore, tin-based stabilizers are expensive and have economical limitations.

Therefore, in consideration of these circumstances, calcium-zinc or barium-zinc based stabilizers have come to be used as inexpensive, low or non-toxic stabilizers to replace them.

However, calcium-zinc or barium-zinc stabilizers have a major drawback in that they are considerably inferior in heat resistance compared to the lead-based or cadmium-based stabilizers mentioned above.

In order to improve this drawback, research has been carried out, and various heat stabilizing aids such as epoxy-based, amine-based, polyol-based, and ring phosphoric acid-based agents have been proposed.

However, these are not necessarily satisfactory.

As a result of pursuing and examining these issues more deeply, the inventors found that
It has been discovered that a compound in which some of the six hydroxyl groups of dipentaerythritol are acetylated, or a mixture containing them appropriately, exhibits excellent effects as a stabilizing agent for calcium-zinc or barium-zinc stabilizers. , which led to the completion of the present invention.

Dipentaerythritol has six hydroxyl groups in one molecule, and is known to be effective in improving the thermal stability of chlorine-containing resins during processing.

Some theories suggest that this effect is due to its high hydroxyl group content, but this is not certain.

However, dipentaerythritol has drawbacks such as poor compatibility with chlorine-containing resins, poor transparency, and the formation of fish eyes.

It is possible to chemically acetylate each of the six hydroxyl groups of dipentaerythritol to obtain a six-step acetyl compound, but highly acetylated products are thermally stable even though they have good compatibility with chlorine-containing resins. It becomes difficult to give sex.

The partially acetylated dipentaerythritol IJ t-ol that can be used in the present invention refers to one having an acetylation rate of 3 equivalents or less, and includes dipentaerythritol monoacetate, dipentaerythritol diacetate, and dipentaerythritol triacetate. This serves the purpose of the present invention.

In addition, dipentaerythritol having an average acetylation rate of 3 equivalents or less according to the present invention is not necessarily limited to the use of these pure compounds alone, but also various acetylated products of dipentaerythritol including free dipentaerythritol. A mixture may be used, including all those having an average acetylation rate of 3 equivalents or less.

As the most extreme example, it may be a simple mixture of dipentaerythritol and its hexaacetate in appropriate amounts, with a calculated acetylation rate within the relevant range.

However, it is more preferable to use a mixture that has been sufficiently homogenized by melting the mixture at an appropriate temperature and aging for an appropriate time to partially transesterify the mixture.

The preferred average acetylation rate of the present invention is in the range of 0.1 to 3 equivalents per mole of dipentaerythritol; when it is too low, it is no different from dipentaerythritol itself, and when it is too high, it has a thermal stabilizing effect. is not so specific, particularly preferred is 0.2 to 1.5 equivalents.

The amount of the stabilizing aid of the present invention to be added depends on the type and amount of the calcium-zinc or barium-zinc stabilizer, but it is effective from 0.1 part by weight to 100 parts by weight of the chlorine-containing resin. Although the time required for coloring and blackening with increasing heat increases, in practice up to 10 parts by weight is sufficient and a large amount is not required.

The chlorine-containing resins of the present invention include not only polyvinyl chloride, which is a homopolymer of vinyl chloride, but also compounds containing vinyl chloride and ethylene, propylene, vinyl acetate, maleic acid, fumaric acid, acrylic acid, methacrylic ester, vinyl ether, etc. Polymers, polymers obtained by graft-polymerizing vinyl chloride onto ethylene-vinyl acetate copolymers, other graft polymers, and chlorinated polyvinyl chloride obtained by chlorinating polyvinyl chloride may be mentioned.

Calcium-zinc or barium-zinc stabilizers include calcium or barium salts of fatty acids such as calcium stearate, calcium laurate, calcium ricinoleate, barium stearate, barium laurate, and barium ricinoleate, zinc stearate, and lauric acid. It is a mixture with fatty acid zinc salts such as acid zinc and ricinoleic acid.

In addition to these zinc stabilizers, other stabilizers such as lead-based, cadmium-based, and tin-based stabilizers may be used in combination, and the combined use of tin-based stabilizers is particularly preferred as a low-toxicity formulation.

As a heat resistance test method, we observed the discoloration and deterioration of chlorine-containing resins over time according to the method actually used in processing chlorine-containing resins, and found that those to which the sample of the present invention was not added quickly turned black and became opaque. However, when the stabilizing agent of the present invention was added, the blackening time was significantly extended, the photoselectivity of the sheet surface was not lost, and the compatibility was excellent. It was found that

In addition, compared to conventionally used polyols such as monopentaerythritol and dipentaerythritol, it has excellent not only heat resistance but also excellent compatibility and lubricity. It is also an extremely important stabilizing agent in industry.

Moreover, it is of course possible that the stabilizing aid in the present invention can be used in combination with other additives such as stabilizers against heat and light, solubilizing agents, and pigments.

The present invention will be specifically described below with reference to comparative examples and examples, but the present invention is not limited to these examples unless it departs from the gist of the present invention.

Example 100 parts by weight of polyvinyl chloride powder, 3 parts by weight of calcium-zinc composite stabilizer, 3 parts by weight of epoxy soybean oil, 1 part by weight of lubricant (Calcol 86) and various stabilizing aids shown in Table 1 were mixed. A 1-thick sheet was prepared by kneading on a roll for 5 minutes at the kneading temperature shown in Table 1, and the color change of the sheet over time was observed in a gear oven at 190° C. every 10 minutes.

The results are shown in Table 2.

As is clear from this table, Examples 1 to 6 in which the stabilizing aid of the present invention was added had better coloring properties than Comparative Examples 1 and 2, and also had better compatibility than dipentaerythritol. He also excels in points.

Claims (1)

[Claims] 1. A chlorine-containing resin containing fatty acid zinc, fatty acid calcium, or fatty acid barium as stabilizers, and dipentaerythritol acetylated to an average acetylation rate of 3 equivalents or less as a stabilizing aid. A stabilized chlorine-containing resin composition. 2. The dipentaerythritol acetylated to an average acetylation rate of 3 equivalents or less is a dipentaerythritol acetate selected from the group consisting of dipentaerythritol monoacetate, dipentaerythritol diacetate, and dipentaerythritol triacetate. A composition according to scope 1. 3. The composition according to claim 1, wherein the dipentaerythritol acetylated to an average acetylation rate of 3 equivalents or less is a mixture of dipentaerythritol and dipentaerythritol acetates. 4. The composition according to claim 1, wherein the dipentaerythritol acetylated to an average acetylation rate of 3 equivalents or less is obtained by partially transesterifying a mixture of dipentaerythritol and dipentaerythritol acetates at high temperature. thing. 5. The composition according to claim 3 or 4, wherein the dipentaerythritol acetate is dipentaerythritol hexaacetate. 6 A mixture of dipentaerythritol and dipentaerythritol acetates is partially transesterified at high temperature, and a mixture of dipentaerythritol and dipentaerythritol hexaacetate is mixed at 5=1 (molar ratio) from 195 to
Melting point 90-150 obtained by heating and melting at 200°C for 3 hours
5. The composition according to claim 4, which is a composition containing dipentaerythritol and dipentaerythritol partial acetate. 7. The composition according to claim 6, wherein the fatty acid zinc and the fatty acid calcium are zinc stearate and calcium stearate, respectively.