JPH0637538B2 - New high nitrile resin - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel high nitrile polymer excellent in blistering resistance and environmental stress crack resistance.

[Conventional technology]

High nitrile resins are thermoplastic polymers with excellent gas and vapor barrier properties and solvent resistance, and have recently been recognized for their practical value as packaging and container materials in the fields of foods, agricultural drugs, cosmetics, etc. ing.

In the production of high nitrile resin, a method of graft polymerizing a monomer mixture containing an unsaturated nitrile as a main component in the presence of rubber for the purpose of imparting impact resistance is generally known, Further usefulness can be imparted to the obtained polymer by selecting a monomer copolymerizable with the unsaturated nitrile. For example, when the monomer copolymerizable with the unsaturated nitrile is an aromatic vinyl compound, a polymer having a high heat distortion temperature is obtained, and some techniques are shown for the production method thereof. There is.

For example, Japanese Patent Publication No. 59-37007 discloses a nitrile polymer obtained by graft-polymerizing a conjugated diene rubber with a monomer mixture mainly composed of an unsaturated nitrile and an aromatic vinyl compound in the first stage, Looking at the relationship between the content of unsaturated nitrile in each polymer produced in the second stage, a nitrile resin having a higher nitrile content in the second stage polymer has been proposed. No. 21331 also relates to a nitrile polymer obtained by graft-polymerizing an unsaturated nitrile, an aromatic vinyl compound and an unsaturated carboxylic acid ester to a diene rubber, and a graft part excluding the rubber of the graft part formed in the first half of the polymerization. A nitrile polymer has been proposed which is characterized in that the content of unsaturated nitrile in the resin is higher than the content of unsaturated nitrile in the matrix resin.

[Problems to be solved by the invention]

The above proposed polymers are all characterized in that the composition in the polymer, particularly the content of unsaturated nitrile is non-uniform, JP-B-59-37007 is a polymer initially produced by polymerization. That is, the graft resin portion that is more closely bound to the rubber is intended to impart a balance between the fluidity and the impact resistance of the resin by suppressing the proportion of unsaturated nitrile to a low level. On the contrary, the purpose of the No. 1 is to give solvent resistance by increasing the proportion of unsaturated nitrile in the resin of the graft part higher than that of the matrix resin part. It was extremely unsatisfactory with respect to tearability and swelling resistance of the molded container.

Here, environmental stress crack resistance refers to the phenomenon that cracks occur in plastic when stress is applied to the plastic under the condition that the liquid or gas of a chemical (solvent) comes into contact with the plastic. Means a phenomenon in which a plastic molded container that absorbs water under conditions of high temperature (40 ° C or higher) and high humidity (50% RH or higher) or when contacted with water is subjected to stress (for example, internal pressure), the container swells. To do.

An object of the present invention is to provide a novel high nitrile polymer excellent in environmental stress crack resistance and swelling resistance, which are extremely important for practical use.

[Means for Solving the Present Invention]

As a result of intensive studies, the present inventors have found that polymers obtained by polymerizing a monomer containing unsaturated nitrile and aromatic vinyl in the presence of a conjugated diene-based synthetic rubber are not By setting the content of the saturated nitrile and the content of the unsaturated nitrile in the matrix resin within a specific range, it is possible to obtain a novel high nitrile polymer excellent in environmental stress crack resistance and blistering resistance. Heading out, the present invention was reached.

That is, the present invention relates to a monomer mixture containing 1 to 40 parts by weight of a diene synthetic rubber containing 50% by weight or more of a conjugated diene monomer and at least 60% by weight of an unsaturated nitrile and at least 5% by weight of an aromatic vinyl compound. A polymer obtained by graft-polymerizing 60 to 99 parts by weight, in which the unsaturated nitrile in the resin grafted on the rubber is X% by weight and the unsaturated nitrile in the matrix resin is Y% by weight, A novel high nitrile resin characterized by having a relationship of 60 ≦ X ≦ Y <90 between X and Y.

The conjugated diene-based synthetic rubber used in the present invention is a conjugated diene 50
A copolymer of at least 1% by weight with at least one monomer selected from unsaturated nitriles, aromatic vinyl compounds, unsaturated carboxylic acid esters and the like copolymerizable therewith. Examples of the conjugated diene monomer include 1,3-butadiene, isoprene, chloroprene, 2,3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene and the like. From the viewpoint of easy availability and polymerizability, 1,3-butadiene and isoprene are preferable. Examples of the unsaturated nitrile include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, and the like, and acrylonitrile and methacrylonitrile are preferable. Examples of the aromatic vinyl compound include styrene, α-methylstyrene, vinyltoluenes, vinylxylenes and the like, and styrene is preferable.

Examples of the unsaturated carboxylic acid ester include esters of acrylic acid or methacrylic acid such as methyl, ethyl, propyl and butyl. Particularly preferred are methyl acrylate, ethyl acrylate, methyl methacrylate and methacrylic acid. It is ethyl.

This conjugated diene-based synthetic rubber can be produced by various known methods, but the emulsion polymerization method is preferable.

Examples of the rubber grafting monomer include unsaturated nitriles and aromatic vinyl compounds, and vinyl compounds copolymerizable therewith, such as unsaturated carboxylic acid esters, vinyl esters, vinyl ethers, and α-olefin monomers. To be

As the monomer copolymerizable with the unsaturated nitrile and the aromatic vinyl compound, unsaturated carboxylic acid ester is preferable from the viewpoint of the balance of impact resistance and processing fluidity.

As the unsaturated nitrile, aromatic vinyl compound and unsaturated carboxylic acid ester, those exemplified above as the copolymerizable monomer in the conjugated diene-based synthetic rubber can be used.

The high nitrile resin of the present invention requires that the resin portion excluding the rubber component contains at least 60% by weight or more of unsaturated nitrile, and if it is less than 60% by weight, nitrile resin such as chemical resistance and gas barrier property. Because the original characteristics are lost,
Not practically preferable, and unsaturated nitrile is 90% by weight.
If it exceeds the above range, deterioration of process fluidity, impact resistance, etc. and yellowing of the resin during molding become problems.

More specifically, assuming that the content of unsaturated nitrile in each of the resin portion grafted to rubber and the matrix resin portion is X and Y weight%, both X and Y must be in the range of 60 to 90 weight%. , And the relation between X and Y is X ≦ Y
That is, the unsaturated nitrile content in the matrix resin,
It must be at least as high as or higher than the content of unsaturated nitrile in the graft resin.

At least 5% by weight of the aromatic vinyl compound is necessary, and 10% by weight or more is practically preferable for improving the blistering resistance.

Further, the aromatic vinyl compound needs to be contained in both the graft resin portion and the matrix resin portion. The content of other vinyl compounds that can be used without impairing the object of the present invention is up to 25% by weight in the monomer mixture.

The term "monomer mixture" as used herein means substantially only vinyl-based monomers and does not include so-called diluents, but may be used in production.

The content of rubber in the total resin is 1 to 40% by weight, but the range of 5 to 30% by weight is preferable in terms of the balance between impact resistance and working fluidity.

The resin of the present invention is obtained by polymerizing a monomer mixture containing an unsaturated nitrile and an aromatic vinyl compound in the presence of a conjugated diene-based synthetic rubber, and the polymerization method is known solution polymerization, bulk polymerization, Emulsion polymerization, suspension polymerization, a polymerization method of any combination thereof, and the like are possible. From the industrial viewpoint, emulsion polymerization is preferred in terms of removal of reaction heat and ease of post-treatment after polymerization.

In emulsion polymerization, the polymer product is obtained in the form of a latex, and the polymer is coagulated by a conventionally known method, for example, an agglomeration method using an electrolyte or a solvent or a freezing method, and further washed with water and dried to give a polymer. obtain.

It is also possible to add plasticizers, stabilizers, lubricants, dyes and pigments, fillers and the like as needed during or after the polymerization.

The polymer produced by the above method is a thermoplastic resin which can be easily thermoformed by a conventional molding method using a known thermoplastic resin material, for example, extrusion molding, injection molding, blow molding, etc. Very high practical value because nitrile resin not only has high gas and vapor barrier properties and excellent chemical resistance and impact resistance, but also excellent environmental stress crack resistance and swelling resistance. It is a new resin.

〔Example〕

 Hereinafter, the present invention will be described with reference to examples.

All "parts" and "%" in the examples are based on weight.

Example 1 (A) Production of Conjugated Diene Synthetic Rubber Latex A mixture of the following components was polymerized in a stainless steel polymerization reactor under nitrogen atmosphere with stirring at 45 ° C. for 20 hours, and the polymerization was completed at a conversion of 90%. did. Unreacted monomers were removed by vacuum stripping to obtain a synthetic rubber latex having a solid content of 30%. The solid content was recovered from the latex, dried, and then the acrylonitrile content in the rubber was determined by elemental analysis. As a result, it was 38% by weight.

Acrylonitrile 40 parts Butadiene-1,3 60〃 Fatty acid soap 2.4〃 Azobisisobutyronitrile 0.3〃 t-dodecyl mercaptan 0.5〃 Water 200〃 (B) Preparation of graft polymer After charging, polymerization was started at 60 ° C. under stirring in a nitrogen atmosphere.

Water 200 parts Acrylonitrile 75〃 Styrene 25〃 Latex A above 33 parts (solid content 10 parts) Sodium dioctysulfosuccinate 1.31〃 Polyvinylpyrrolidone 0.47〃 Potassium persulfate 0.06〃 t-dodecyl mercaptan 2.00〃 Conversion of monomer The reaction was terminated when the content of 90% by weight was reached. The obtained latex had a concentration of 30% by weight, and after cooling, an aqueous solution of aluminum sulfate was added to coagulate it, followed by washing with water and drying to obtain a powdery polymer.

The obtained powdery polymer was dissolved in a mixed solvent of dimethylformamide / acetonitrile (ratio = 1/1) and separated into a solvent-insoluble graft portion and a solvent-soluble matrix portion, The composition was investigated. Than this,
Table 1 shows the composition of the resin portion excluding rubber in the graft portion, that is, the composition of the graft resin and the matrix resin. Further, the obtained polymer was pressure-molded at 170 ° C. and 140 kg / cm ² to prepare a sheet for evaluation of physical properties. Incidentally, the unsaturated nitrile component is an elemental analysis, and the aromatic vinyl component and other copolymerizable monomer components are
It was quantified by H-nuclear magnetic resonance spectrum.

(C) Physical property evaluation method (a) Environmental stress crack resistance test Ethanol and toluene were used as chemicals, and the sample was immersed in the chemicals under stress load conditions and taken out 1 hour after immersion, and cracks were generated. The critical strain (%) was determined from the state.

Bergen, which is generally known as a stress loading device
Using 1/4 oval metal fittings (SPE Journal 18 , No.6,667 (196
2)).

The larger the value of critical strain, the better the environmental stress crack resistance.

(B) Blistering resistance test Swelling refers to a phenomenon in which a molded article swells under conditions of high temperature, high humidity and pressure, and the following test method was adopted as a method for evaluating its blistering resistance.

According to ASTM D638, a test piece for tensile strength measurement was prepared and immersed in warm water at 55 ° C for 10 days. The tensile strength of the sample that was not immersed in warm water and the sample that had been immersed for 10 days was measured in a constant temperature bath at 55 ° C. to determine the difference in yield strength.

The results of the above measurements are shown in Table 2.

Examples 2 to 4 and Comparative Example 1 Polymers were prepared in the same manner as in Example 1 except that the composition of the monomer in Example 1 (B) was changed as shown in Table 1.

Table 1 shows the composition analysis results of the polymer graft resin and matrix resin, and Table 2 shows the evaluation results of the environmental stress crack resistance and the blistering resistance.

Incidentally, in Comparative Example 1, both the acrylonitrile content in the graft resin and the matrix resin was 60% by weight or less, and the polymer was outside the scope of the present invention.

Comparative Example 2 The following main and auxiliary materials were charged in a polymerization reactor, and polymerization was started at 60 ° C. under stirring in a nitrogen atmosphere.

Initial charge water 200 parts Acrylonitrile 15〃 Styrene 8〃 Methyl methacrylate 7〃 Example 1 (A) rubber latex 33 parts (solid content 10 parts) Sodium dioctisulfosuccinate 1.31〃 Polyvinylpyrrolidone 0.47〃 Potassium persulfate 0.06〃 t-dodecyl mercaptan 2.00 〃 1 hour after starting the polymerization with the above initial charge, the following monomer mixture was added and the polymerization was continued under the same conditions.

Post-added monomer mixture Acrylonitrile 55 parts Styrene 8〃 Methyl methacrylate 7〃 The reaction was terminated when 90% by weight of the total amount of the monomers was converted into the polymer, and the polymer was recovered according to the method of Example 1. , Composition analysis and evaluation of physical properties were performed.

The results are shown in Tables 1 and 2.

The contents of acrylonitrile in the graft resin and the matrix resin of the present polymer were 52% by weight and 70.4% by weight, respectively, and the nitrile content in the graft resin was a polymer having a value lower than the range of the present invention. .

Comparative Example 3 First, raw materials having the following composition were charged into a polymerization vessel, and polymerization was started at 60 ° C. under stirring in a nitrogen atmosphere.

Water 200 parts Acrylonitrile 30 〃 Rubber latex of Example 1 (A) 33 parts (solid content 10 parts) Sodium dioctysulfosuccinate 1.31 〃 Polyvinylpyrrolidone 0.47 〃 Potassium persulfate 0.06 〃 t-dodecyl mercaptan 2.00 〃 Polymerization start 30 minutes After that, 70 parts by weight of the following monomer mixture was continuously added in 6 hours. After the addition was completed, the reaction was continued for 2 hours, and the reaction was completed when 90% by weight of the total amount of the monomers was converted into a polymer.

Post-added monomer mixture Acrylonitrile 35 parts Styrene 18〃 Methyl methacrylate 17〃 The polymer was recovered by the same method as in Example 1 and the composition was analyzed. As shown in Table 1, the content of acrylonitrile in the graft resin was shown. The content was 78.5% by weight, and the acrylonitrile content in the matrix resin was 58% by weight, which was a polymer outside the scope of the present invention.

Table 2 shows the results of physical property evaluation performed in the same manner as in Example 1.

Comparative Example 4 The composition of the monomer in Example 1 (B) was changed to the composition shown in Table 1,
A polymer was prepared in the same manner as in Example 1 except for the above. Table 1 shows the results of composition analysis of the obtained polymer graft resin and matrix resin. In a test of environmental stress crack resistance, this polymer was used in a practically fragile state because a large crack was generated and damaged only by stress without immersing it in ethanol or toluene as a chemical solution. It was a resin with physical properties.

[Effects of the Invention] As is clear from Examples 1 to 4 and Comparative Examples 1 to 4, the polymers within the scope of the present invention are excellent in environmental stress crack resistance and swelling resistance, and are extremely useful in practice. It is a new high nitrile resin.

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Claims (1)

[Claims] 1. A monomer mixture 60 containing 1 to 40 parts by weight of a diene synthetic rubber containing 50% by weight or more of a conjugated diene monomer and at least 60% by weight of an unsaturated nitrile and at least 5% by weight of an aromatic vinyl compound. To 99 parts by weight of the polymer, wherein X is the unsaturated nitrile in the resin grafted to the rubber and X is Y% by weight of the unsaturated nitrile in the matrix resin. A novel high nitrile resin characterized by having a relationship of 60 ≦ X ≦ Y <90 between Y and Y.