JPS623865B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a vinyl chloride resin composition, in which a methyl methacrylate-butadiene-styrene graft copolymer (hereinafter referred to as MBS resin) stabilized with the stabilizer composition described in the present invention is added to a vinyl chloride resin. When food, etc. is packaged in a packaging container molded from this vinyl chloride resin composition by mixing, the taste, odor, etc. of the packaged food will not be affected by the packaging container at all, and the food, etc. will retain its original properties. The ability to retain sensory characteristics such as taste or smell (hereinafter referred to as organoleptic properties)
This provides an excellent composition. This composition also has good thermal stability, processability, impact resistance, and transparency, so it shows excellent performance in uses other than food containers. PVC resin has superior transparency, chemical resistance, low air permeability, weather resistance, etc. compared to other general-purpose resins, and has improved impact resistance, which was previously considered a drawback.
With the development of impact-resistant reinforcing agents such as MBS resin, it has been significantly improved and is now widely used as a resin material in packaging containers for foods, cosmetics, and other fields that require impact resistance. However, in order to use vinyl chloride resin compositions as resin materials for packaging containers for foods, cosmetics, etc.
It has traditionally been necessary for packaging containers to pass the sanitary regulations of the country in which they are used, but recently these regulations have become increasingly strict in each country. For example, even if additives are permitted to be used as additives in vinyl chloride resin compositions, the amount of the additives transferred from the packaging container to the contents is also being regulated. The stabilizers that are approved for use in major countries around the world as stabilizers for vinyl chloride resin include mainly calcium stearate-zinc stearate stabilizers and octyltin stabilizers, but the former has no stabilizing effect. Because of their small size, it is necessary to use a combination of various stabilizers, which necessitates an increase in the types and amounts of additives. As a result, there is a disadvantage that a large amount of these additives is transferred from the packaging material to the contents. On the other hand, although the latter has a better stabilizing effect than the former, it has an odor peculiar to octyltin stabilizers (mainly mercabuto compounds), and this odor transfers to the contents and affects the taste and odor of the contents. I end up. On the other hand, MBS resin or ABS resin, which is generally used as an impact-resistance reinforcing agent for vinyl chloride resin, uses polybutadiene-based rubber as the rubber base polymer, and the unsaturated bonds due to the butadiene component in the rubber base polymer are exposed to heat and oxygen. Therefore, it is important to prevent deterioration during the manufacturing process of these reinforcing agents, especially during the drying process, and to prevent the performance of reinforcing agents from deteriorating when they are mixed with vinyl chloride resin and molded by heating and melting. For the purpose of preventing this, a method of adding a stabilizer to the reinforcing agent has been adopted. Conventionally, phenolic compounds having the following general formula, such as 2,6 ditertiary butyl para-cresol (BHT), have been used as stabilizers for MBS resins or ABS resins.

[Formula] R ₁ , R ₂ , and R ₃ are alkyl groups having 1 to 4 carbon atoms. Such stabilizers have poor compatibility with the rubber backbone polymer, and moreover, they volatilize greatly under heating, so they are not sufficiently stable. To obtain the effect, it is necessary to increase the amount added. As a result, when foods, cosmetics, etc. are packaged in a packaging container made from a resin composition obtained by mixing MBS resin or ABS resin with vinyl chloride resin stabilized with such a stabilizer, the stabilizer is transferred from the packaging container to the contents. The transfer of a large amount of PVC has a large effect on the taste and odor of the contents, resulting in a significant decrease in so-called organoreptotic properties, and also poses a major problem in terms of sanitary regulations when PVC resin compositions are used in packaging containers. was. The inventors of the present invention have conducted extensive research into ways to maintain the original characteristics such as taste and odor of the contents packaged in food packaging containers that are melt-molded from a vinyl chloride resin composition mixed with an impact reinforcing agent. As a result, we discovered that a resin composition obtained by mixing MBS resin stabilized with a special stabilizer composition with vinyl chloride resin can provide packaging containers with excellent organoreptotic properties. The present invention has now been completed. That is, in the present invention, 0.001 parts by weight is added to 100 parts by weight of methyl methacrylate-butadiene-styrene graft copolymer.
~2 parts by weight of tocopherols, 0.001 to 2 parts by weight of a sulfur-containing compound represented by the general formula (), and

[Table] Vinyl chloride copolymer 97-97 consisting of 3-30 parts by weight of MBS resin mixture stabilized by adding 0-5 parts by weight of epoxidized vegetable oil and vinyl chloride polymer or at least 70% by weight of vinyl chloride The present invention relates to a vinyl chloride resin composition with excellent impact resistance, transparency, processability, thermal stability and organoreptotic properties obtained by mixing 70 parts by weight of the vinyl chloride resin composition. First, the stabilizer that stabilizes the MBS resin of the present invention will be described. The tocopherols used in the present invention are α,
DL-α is a tocopherol obtained from various β, γ, and δ tocopherols and mixtures thereof, and is easily available and highly effective.
Contains tocopherol, natural vitamin E, etc. Tocopherols have low volatility under heating and have good compatibility with the rubber backbone polymer of MBS resin, so they have an excellent stabilizing effect even when added in small amounts. Furthermore, these tocopherols are widely present in animals and plants, and are ingested on a daily basis, so they have the advantage of being non-toxic. Furthermore, it is essential for the present invention that tocopherols be used in combination with a sulfur-containing compound represented by the general formula (). Examples of the sulfur-containing compound represented by the general formula () include dicaprylthiodipropionate, dilaurylthiodipropionate, dipalmitylthiodipropionate, and distearylthiodipropionate. By using this sulfur-containing compound in combination with tocopherols, the effects obtained when each compound is used are not simply added, but a so-called synergistic effect is obtained in which the effects are further increased, and the stabilizing effect is significantly improved. do. Also, as epoxidized vegetable oil, oxirane oxygen 6
% or more of epoxidized soybean oil, epoxidized linseed oil, etc. can be used. This epoxidized vegetable oil is effective when used in combination with a sulfur-containing compound having a relatively high melting point of 60°C or higher. Packaging containers obtained from vinyl chloride resin compositions reinforced with MBS resin stabilized with stabilizer compositions with excellent effects as described above show no migration to the contents when filled with foods, etc. . As a result, it has become possible to maintain the original taste and odor of the contents. Furthermore, the resin composition of the present invention has excellent impact resistance, transparency, processability, and thermal stability, and therefore has excellent properties for uses other than the field of packaging materials such as food containers. In the present invention, the amount of stabilizer added is 0.001 to 2 parts by weight for tocopherols per 100 parts by weight of MBS resin. If it is less than 0.001 part by weight, a sufficient stabilizing effect cannot be obtained, and if it is more than 2 parts by weight, it cannot be expected that the stabilizing effect will improve in proportion to the amount added, and organoreptotic properties will also deteriorate. For this reason, the preferable addition amount is 0.01 to 1 part by weight per 100 parts by weight of MBS resin. On the other hand, the amount of the sulfur-containing compound represented by the general formula () used in combination with this tocopherol is MBS
The amount is 0.001 to 2 parts by weight per 100 parts by weight of the resin.
If it is less than 0.001 part by weight, there will be no sufficient stabilizing effect, and no effect of combined use will be obtained. Furthermore, even if 2 parts by weight or more is added, the stabilizing effect will not improve in proportion to the amount added.
MBS resin produces an unpleasant odor characteristic of sulfur-containing compounds. For this reason, the preferred amount to be added is 0.01 to 1 part by weight per 100 parts by weight of the MBS resin. A good synergistic effect can be obtained when tocopherols and sulfur-containing compounds are used in combination at a ratio of 1 part by weight of the former to 1 to 25 parts by weight of the latter. Epoxidized vegetable oil is used in combination with tocopherols and sulfur-containing compounds in an amount of 0 to 5 parts by weight based on 100 parts by weight of MBS resin. The stabilizer of the present invention may be mixed with the MBS resin in a wet or dry state by an appropriate method. For example, a stabilized MBS resin can be obtained by mixing using a Henschel mixer or the like. Furthermore, from the viewpoint of the manufacturing process, it is preferable to convert the stabilizer composition into a latex and add this latex to a latex containing the MBS resin for co-acid precipitation. That is, the stabilizer composition of the present invention can be used at a concentration of 10μ or less, preferably 2μ.
Add the following stabilizer latex emulsified and dispersed into uniform fine particles to the latex containing the MBS resin that has completed polymerization, and stir both thoroughly so that the fine particles of the stabilizer composition are evenly adsorbed onto the MBS resin. A preferred method is to carry out co-acid precipitation. The MBS resin used in the present invention is
No. or Special Publication No. 1972-22629 or Special Publication No. 1971-
As shown in No. 49191, styrene and methyl methacrylate are used as monomers to be grafted to the rubber backbone polymer, and these graft monomers are mixed with methyl methacrylate mainly consisting of styrene, methyl methacrylate alone or A monomer mixture containing methyl methacrylate and styrene is first added and polymerized in the presence of a rubber latex containing unagglomerated or aggregated particles of polybutadiene or butadiene-styrene copolymer, and then the latter is added and polymerized. Furthermore, those obtained by adding these graft monomers and adding a crosslinking monomer at the same time during polymerization are preferable. The vinyl chloride resin used in the present invention is a vinyl chloride homopolymer obtained by a known method such as emulsion polymerization or suspension polymerization, or ethylene that can be copolymerized with vinyl chloride containing 70% by weight or more of vinyl chloride.
Copolymers with unsaturated ethylenic monomers represented by propylene, vinyl acetate, methyl methacrylate, etc., post-chlorinated polyvinyl chloride polymers, and mixtures thereof can be used. It can be used by mixing with 3 to 30 parts by weight of MBS resin stabilized with the stabilizer composition of the present invention. The two are mixed using a Henschel mixer, ribbon blender, Banbury mixer, etc.
Furthermore, it can be molded using a known method such as an extruder or an injection molding machine. Stabilizers, if necessary at this time,
Known additives such as processing aids and lubricants may also be added. Examples are shown below, where parts are by weight. Example 1 The following ingredients were placed in a pressure-resistant container with a stirrer and heated at 50°C.
The reaction was carried out for 16 hours to complete the polymerization. Crosslinked trunk copolymer rubber component Butadiene 50 parts Styrene 15 parts Divinylbenzene 0.65 parts Diisopropylbenzene hydroperoxide
0.065 part ferrous sulfate (FeSO _{4.7H 2} O) 0.002 part ethylenediaminetetraacetate disodium salt 0.0035 part formaldehyde sodium sulfoxylate
0.03 parts Potassium oleate 0.75 parts Sodium pyrophosphate 0.1 parts Distilled water 150 parts Polymerization yield is approximately 99% or more, solid content is approximately 30%, PH
A rubber latex of 9.0 was obtained. After sufficiently stabilizing the latex by adding 0.065 part of sodium sulfosuccinate dioctyl ester to the total amount of the latex,
30 parts of 0.2% hydrochloric acid aqueous solution was gradually added to effect flocculation. It was observed that the average particle diameter of the rubber particles in the latex increased from 0.08μ to 0.18μ due to this agglomeration. Latex pH 9.5 with sodium hydroxide aqueous solution
The mixture was reconstituted, and the following first-stage graft components were added thereto, and polymerization was continued at 60°C for 4 hours. 1st stage graft component Styrene 15 parts Methyl methacrylate 12.5 parts Divinylbenzene 0.09 parts Diisopropylbenzene hydroperoxide
0.02 parts formaldehyde sodium sulfoxylate
Further, 0.02 parts of the following second-stage graft component was added to this latex, and polymerization was similarly carried out at 60°C for 7 hours. Second stage graft component Methyl methacrylate 7.5 parts Divinylbenzene 0.038 parts Diisopropylbenzene hydroperoxide
0.0038 parts formaldehyde sodium sulfoxylate
0.0038 parts The obtained latex contained approximately 35% solids, indicating that the polymerization was almost complete. A stabilizer latex with an average particle size of 1.3μ obtained by emulsifying the stabilizer components shown below is mixed with the obtained latex, and after co-acid precipitation, it is dehydrated and dried to obtain a stabilized MBS resin powder. Ta. Stabilizer component DL-α-tocopherol 0.03 parts Dilauryl thiodipropionate 0.5 parts Epoxidized soybean oil 2.0 parts 15 parts of this MBS resin was mixed with vinyl chloride resin (polymerization degree
700) and 6.4 parts of a calcium-zinc composite stabilizer were added to the mixture and kneaded for 3 minutes using a test roll with a surface temperature of 160°C. This was molded at a press temperature of 195° C. and a press pressure of 150 Kg/cm ² to produce a press sheet with a thickness of 1 mm. Cut three test pieces of 4 cm x 10 cm from this breath sheet and place them in a glass container with a stopper containing 300 ml of pre-boiled ion exchange water.
Soak for 20 hours in a thermostat at ℃. When we compared the taste and odor of this immersion solution with an immersion solution made using a sheet made in exactly the same way except without the addition of MBS resin, there was almost no significant difference, and no influence of MBS resin was observed. Furthermore, the amounts of DL-α-tocopherol and dilaurylthiodiprobionate eluted from this immersion solution were measured using gas chromatography, but no detection was found. Furthermore, the isot strength (measurement method) of the vinyl chloride resin composition to which this stabilized MBS resin was added
JIS-K7110) is 114 Kg·cm/cm ² , which is a dramatic improvement in impact strength compared to 4 Kg·cm/cm ² of a vinyl chloride resin alone composition. Examples 2 to 6 and Comparative Examples 1 to 4 Thermal stability of a vinyl chloride resin composition using an MBS resin obtained in the same manner as in Example 1 except that the composition of the stabilizer added to the MBS resin was changed, The organoreptotic properties and the amount of stabilizer extracted are shown in Table 1. The thermal stability of the MBS resin itself to which stabilizers have been added is also shown. The thermal stability of the vinyl chloride resin composition is shown by the time (minutes) required for the sheet to turn blackish brown when a rolled sheet obtained in the same manner as in Example 1 is heated to 175° C. in a gear oven. The thermal stability of MBS resin is measured by the time (minutes) it takes for the powder to turn yellow when 0.2 g of this resin powder is placed in a glass container and heated to 170°C in a gear oven. On the other hand, oreganoleptic properties were tested in the same manner as in Example 1, and the taste and odor of ion-exchanged water was given a score of 1 by 10 inspectors who were able to sharply and objectively judge the sense of taste and smell. The comparison results of each sample are shown as the average value of 10 people, with the strongest taste and smell being given 5 points in increasing scores. Note that the taste and odor intensity of the vinyl chloride resin composition not containing MBS resin were each rated 2 points. Furthermore, the amount of stabilizer extracted is shown as the value measured using gas chromatography for DL-α-tocopherol and sulfur compounds in the immersion liquid tested for organoleptic properties. As shown in Table 1, it is clear that the stabilizer compositions of the present invention (Examples 2 to 6) have excellent thermal stability and organoleptic properties. On the other hand, MBS without any stabilizers added
Vinyl chloride resin composition using resin (Comparative Example 1)
have extremely poor thermal stability and organoleptic properties, and those using MBS resin stabilized with a mixed system of DL-α-tocopherol and epoxidized soybean oil (Comparative Example 2), dilauryl thiodipropionate, Stabilized with epoxidized soybean oil mixture system
In the case where MBS resin is used (Comparative Example 3), the MBS resin itself and the resin composition obtained by mixing these MBS resins with vinyl chloride resin lack thermal stability.
On the other hand, when the conventional stabilizer 2.6-di-tert-butylpara-cresol, dilaurylthiopropionate, and epoxidized soybean oil mixture system was used (Comparative Example 4), The amount of tert-butyl para-cresol is large, and satisfactory organoleptic properties and thermal stability have not been obtained.

[Table] Examples 7 to 10 MBS stabilized in the same manner as in Example 1 except that the emulsion-dispersed particle size of the stabilizer latex was changed.
Table 2 shows the thermal stability and organoleptic properties of the vinyl chloride resin composition prepared by mixing the resins. The thermal stability of the MBS resin itself is also shown. The testing methods and indications for these thermal stability and organoreptotic properties are the same as in Example 2.

[Table] This table shows that the smaller the average particle diameter of the stabilizer latex added to the latex containing MBS resin, the better the thermal stability of the MBS resin itself and the resin composition in which it is mixed with vinyl chloride resin. It shows that the character is good.

Claims (1)

[Claims] 1. To 100 parts by weight of methyl methacrylate-butadiene-styrene graft copolymer (MBS resin)
0.001-2 parts by weight of tocopherols and 0.001-2 parts by weight
General formula for parts by weight () (m, n are integers from 1 to 4, R ₁ and R ₂ have 8 carbon atoms.
A vinyl chloride polymer or at least Vinyl chloride copolymer consisting of 70% by weight or more97~
An impact-resistant vinyl chloride resin composition prepared by mixing 70 parts by weight. 2 Methyl methacrylate-butadiene-styrene graft copolymer (MBS resin) mixture is MBS
Latex containing 100 parts by weight of resin, 0.001 to 2 parts by weight of tocopherols and 0.001 to 2 parts by weight of general formula () (m, n are integers from 1 to 4, R ₁ and R ₂ have 8 carbon atoms.
A stabilizer latex containing a sulfur-containing compound represented by an alkyl group having a linear or side chain of ~20 (alkyl group having a straight chain or side chain) and 0 to 5 parts by weight of epoxidized vegetable oil as fine particles of 10 μ or less is added and co-oxidized. The impact-resistant vinyl chloride resin composition according to claim 1, characterized in that: