JPH05202055A - Method for stabilizing dibenzylidene sorbitol and its composition - Google Patents

Abstract

PURPOSE:To extremely suppress increase in benzaldehydes during preservation and to stabilize the subject compound by adding a fixed amount of sorbic acid and/or potassium sorbate to a dibenzylidene sorbitol. CONSTITUTION:100 pts.wt. dibenzylidene sorbitol of the formula (R and R<1> are H, halogen, 1-8C alkyl or 1-8C alkoxy; n and m are 1-3) is blended with 0.05-20 pts.wt., preferably 0.2-20 pts.wt. sorbic acid and/or potassium sorbate dibenzylidene sorbitol. The prepared dibenzylidene sorbitol composition is added to a polyolefin resin to give a molded article, a product having transparency of resin and slight smell. 1,3- or 2,4-Dibenzylidene sorbitol may be cited as the compound.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for stabilizing dibenzylidene sorbitols and a composition thereof.

More specifically, it relates to a method for stabilizing dibenzylidene sorbitols, which suppresses an increase in benzaldehydes over time, a composition thereof, and a molded article to which the composition is added.

[0003]

BACKGROUND OF THE INVENTION Dibenzylidene sorbitols have the effect of improving the transparency of polyolefin resins, especially polyethylene, polypropylene, or copolymers containing them as a main component, by adding a small amount thereof to improve the transparency of the resin. It is a compound that is useful as an additive for resins in the field of molding such as various containers that require high properties. It is also a compound useful as a gelling agent for various organic solvents.

[0004] However, dibenzylidene sorbitols are relatively poor in stability, liberate benzaldehydes during storage or processing to give off a bad odor, and sometimes give an aldehyde odor or coloring to a molded article, which is large depending on the use. It became an obstacle and hindered the growth of demand.

Further, even when the odor is purified to such an extent that the odor cannot be noticed, the decomposition of dibenzylidene sorbitols occurs due to the effects of temperature and moisture during storage,
It was a cause of odor.

Conventionally, the following methods have been studied and disclosed for solving the above-mentioned problems.

JP-A-53-5165 or JP-A-57-185287 discloses a method of thermally mixing dibenzylidene sorbitols with a lower aliphatic alcohol or a lower aliphatic ketone, and JP-A-60-32791. JP-A No. 60-42385 or JP-A No. 60-42385 describes a method of treating with hydroxylamine or phenylhydrazines. However, all of these methods are methods for removing benzaldehydes contained as impurities and do not improve the stability against decomposition during storage.

Japanese Unexamined Patent Publication No. 62-5289 discloses a sorbitol derivative composition having improved thermal stability, which is obtained by adding a non-aromatic organic amine to a sorbitol derivative. However, in the field where these compositions are used as additives for resins and used in food containers and the like, stability due to amines is a concern.

JP-A-57-21440 and JP-A-1-126352 disclose a composition in which the surface of a solid powder of dibenzylidene sorbitol or a di-substituted benzylidene sorbitol derivative is coated with a saturated higher fatty acid such as behenic acid. Has been done. In this case, it is described that the effect is small when it is simply added, and it is necessary to coat the surface with a surfactant or the like. Therefore, the manufacturing process becomes complicated, and it is necessary to use a relatively large amount of 5 to 50 parts by weight of higher fatty acid with respect to 95 to 50 parts by weight of dibenzylidene sorbitols.

In addition, a method of blending about 0.1 part by weight of a carboxylic acid metal salt such as calcium stearate with 100 parts by weight of the resin is generally adopted at the time of processing the polyolefin resin, but it imparts transparency. Therefore, it is not possible to improve the odor of molded articles when dibenzylidene sorbitols are added.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for stabilizing dibenzylidene sorbitols and a composition thereof, which can markedly suppress the increase of benzaldehydes during storage.

The present inventors have found that the aldehyde odor and coloration of molded articles are correlated with the amount of benzaldehydes contained in dibenzylidene sorbitols before being used for processing, and dibenzylidene sorbitols are found. We conducted extensive studies on the method for removing the benzaldehyde contained in and the method for inhibiting increase during storage. As a result, it was confirmed that the increase of benzaldehydes can be prevented by adding a specific amount of sorbic acid and / or potassium sorbate to dibenzylidene sorbitols, and the present invention has been completed.

[0013]

That is, the first aspect of the present invention
The invention of the general formula (1)

[0014]

[Chemical 2] [In the formula, R and R ′ are each independently a hydrogen atom,
Halogen atom, C1-C8 alkyl group, C1-C1
8 represents an atom or a group selected from the group consisting of 8 alkoxy groups, and n and m each represent an integer of 1 to 3. ] The sorbic acid and / or potassium sorbate 0.
The present invention provides a method for stabilizing dibenzylidene sorbitols, which comprises adding 05 to 20 parts by weight. The second invention also provides a composition obtained by adding sorbic acid and / or potassium sorbate to dibenzylidene sorbitols.

A third aspect of the present invention is to provide a product having an extremely low odor as well as imparting transparency to a molded product by using a stabilizing composition of dibenzylidene sorbitols as an additive for resins such as polyolefin.

The dibenzylidene sorbitols of the general formula (1) used in the present invention include 1,3-2,4-dibenzylidene sorbitol and 1,3-2,4-di (p-
Methylbenzylidene) sorbitol, 1,3-2,4-
Di (p-ethylbenzylidene) sorbitol, 1,3-
2,4-di (p-chlorobenzylidene) sorbitol,
Compounds having the same benzylidene group such as 1,3-2,4-bis (dimethylbenzylidene) sorbitol;
1,3-benzylidene-2,4-p-methylbenzylidene sorbitol, 1,3-benzylidene-2,4-p-
Ethylbenzylidene sorbitol, 1,3-benzylidene-2,4-p-chlorobenzylidene sorbitol,
1,3-p-methylbenzylidene-2,4-benzylidenesorbitol, 1,3-p-methylbenzylidene-
2,4-p-chlorobenzylidene sorbitol, 1,3
-P-methylbenzylidene-2,4-p-ethylbenzylidene sorbitol, 1,3-p-ethylbenzylidene-2,4-benzylidene sorbitol, 1,3-p-ethylbenzylidene-2,4-p-methylbenzylidene sorbitol , 1,3-p-ethylbenzylidene-2,4
Examples thereof include compounds having different benzylidene groups such as -p-chlorobenzylidene sorbitol.

The sorbic acid and / or potassium sorbate used in the composition of the present invention is known as a food preservative, has an effect of suppressing the growth of microorganisms such as bacteria and bacteria, and Although it is prevented from decaying, the effect of preventing decomposition of dibenzylidene sorbitols is not known and is the effect confirmed for the first time by the present invention.

The composition of the present invention is prepared by adding 0.05 to 20 parts by weight, preferably 0.2 to 20 parts by weight of sorbic acid and / or potassium sorbate to 100 parts by weight of dibenzylidene sorbitol. can get.
If the amount is less than 0.05 parts by weight, the desired effect is not sufficiently obtained, and if it is 20 parts by weight or more, there is an effect of suppressing the aldehyde. Alternatively, the transparency of the molded product is lowered, which is not preferable.

In the method of adding sorbic acid and / or potassium sorbate to dibenzylidene sorbitols, both may be directly mixed, but alcohols such as methanol and ethanol are mixed as a solvent, and then the solvent is added. You may distill off. Further, a method of forming an aqueous emulsion using a surfactant and coating the surface of dibenzylidene sorbitol may be used, but the above-mentioned method is sufficient.

Examples of the polyolefin resin to which the composition of the present invention is used as an additive include polypropylene, low density polyethylene, high density polyethylene, ethylene-propylene copolymer and the like. The amount used as an additive in such use is in the range of 0.05 to 1 part by weight based on 100 parts by weight of the polyolefin resin.

The composition of the present invention can significantly suppress the change with time during storage, as compared with the prior art, and
Surprisingly, a molded product obtained by injection or extrusion molding of a polyolefin resin with transparency obtained by using dibenzylidene sorbitols, which suppresses aging and extremely reduces the benzaldehyde content in this way, also has extremely low odor. It turns out that it will be a product.

[0022]

EXAMPLES The present invention will be described in more detail below with reference to examples.

Synthesis Example 1 Synthesis of dibenzylidene sorbitol: The dibenzylidene sorbitols used in the following examples were synthesized by the following procedure.

2 molar equivalents of benzaldehyde per 1 molar amount of sorbitols were heated in benzene with vigorous stirring in the presence of p-toluenesulfonic acid, and dehydration was carried out under reflux for 8 hours. Next, after adding an aqueous solution of sodium carbonate dissolved in water, heating was continued and benzene and water were azeotropically distilled. When benzene was almost completely distilled, a powder was deposited. Acetone was added to the white powder obtained by filtering the reaction solution, and the mixture was heated under reflux for 2 hours and then hot filtered. This process was repeated twice. After that, it was dried and used in the following examples.

Example 1 A sample was prepared by mixing 100 parts by weight of 1,3-2,4-dibenzylidene sorbitol and 15 parts by weight of potassium sorbate in a ball mill at room temperature for 3 hours.

Example 2 50 parts by weight of 1,3-2,4-di (p-ethylbenzylidene) sorbitol, 1 part by weight of potassium sorbate and 80 parts by weight of methanol were placed in a flask and mixed at room temperature for 2 hours. After that, methanol was removed under reduced pressure. After taking out from the flask, it was further dried to prepare a sample.

Example 3 100 parts by weight of 1,3-2,4-di (p-methylbenzylidene) sorbitol, 0.2 parts by weight of sorbic acid and 120 parts by weight of methanol were placed in a flask and mixed at room temperature for 4 hours. After that, methanol was removed under reduced pressure. After taking out from the flask, it was further dried to prepare a sample.

Example 4 A sample was prepared in the same manner as in Example 2 except that 1.5 parts by weight of sorbic acid and 1.5 parts by weight of potassium sorbate were used instead of 1 part by weight of potassium sorbate.

Comparative Examples 1 to 3 Dibenzylidene sorbitols prepared in Examples 1 to 3 without the addition of potassium sorbate or sorbic acid were prepared.

Comparative Example 4 In Example 2, a sample was prepared using 0.005 part by weight of potassium sorbate.

Comparative Example 5 A sample was prepared in the same manner as in Example 1, except that 22 parts by weight of stearic acid was used instead of potassium sorbate.

Comparative Example 6 1,3-2,4-dibenzylidene sorbitol synthesized according to the above-mentioned synthesis example was subjected to hydroxylamine hydrochloride treatment according to the description of Examples in JP-A-60-32791.

That is, 0.5 part by weight of hydroxylamine hydrochloride was dissolved in a small amount of water in a flask, and 0.6 part by weight of sodium carbonate was added thereto for neutralization. After adding 500 parts by weight of methanol and stirring well, 1,3-2,
50 parts by weight of 4-dibenzylidene sorbitol was added, and the mixture was stirred so that it was well dispersed in a milky or creamy form.

While stirring on a hot water bath at 65 ° C., 2
After warming for 1000 hours, 1000 parts by weight of water was added, and this was filtered and washed twice with water. The obtained cake was dried in an 85 ° C dryer for 6 hours.

Stability test: Table 1 shows the results of the stability test conducted using the above sample.

The stability test is carried out by subjecting the sample to a temperature of 25 to 30 ° C.
After storing in a room with humidity of 50-60% RH for 1 month,
The content of benzaldehydes was analyzed by liquid chromatography.

[0037]

[Table 1]

[0038]

EFFECTS OF THE INVENTION It is clear that the composition containing sorbic acid and / or potassium sorbate in a specified amount remarkably suppresses the production of benzaldehyde even during storage for one month.

Claims (5)

[Claims] 1. The following general formula (1): [In the formula, R and R ′ are each independently a hydrogen atom,
Halogen atom, C1-C8 alkyl group, C1-C1
8 represents an atom or a group selected from the group consisting of 8 alkoxy groups, and n and m each represent an integer of 1 to 3. ] With respect to 100 parts by weight of dibenzylidene sorbitols represented by the above formula, sorbic acid and / or potassium sorbate 0.
A method for stabilizing dibenzylidene sorbitols, which comprises adding 05 to 20 parts by weight. 2. The method according to claim 1, wherein the amount of sorbic acid and / or potassium sorbate is 0.2 to 20 parts by weight. 3. The method according to claim 1, wherein a mixture of dibenzylidene sorbitols and sorbic acid and / or potassium sorbate is mixed in the presence of a solvent, and then the solvent is distilled off. 4. A stabilized composition of dibenzylidene sorbitols, which is obtained by adding 0.05 to 20 parts by weight of sorbic acid and / or potassium sorbate to 100 parts by weight of dibenzylidene sorbitols according to claim 1. 5. A dibenzylidene sorbitol composition obtained by adding 0.05 to 20 parts by weight of sorbic acid and / or potassium sorbate to 100 parts by weight of the dibenzylidene sorbitol according to claim 1 is added to a polyolefin resin. , A molded product formed by molding.