JPS61166812A - Production of high-nitrile polymer - Google Patents

Abstract

PURPOSE:To obtain the titled polymer having improved impact resistance and suitable for the container and packaging material of food, cosmetic, etc., by compounding an acrylonitrile monomer, etc. to an aqueous medium of a conjugated diene synthetic rubber in an amount higher than the solubility in the water contained in the polymer and polymerizing the monomer. CONSTITUTION:The objective polymer can be produced by compounding (A) 100pts.wt. of a monomer mixture containing >=50wt% acrylonitrile (e.g. a mixture with vinyl acetate to an aqueous medium in an amount to exceed the solubility of acrylonitrile monomer in the medium, in the presence of (B) 1-40pts.wt. of a conjugated diene synthetic rubber produced by the copolymerization of (i) >=50wt% conjugated diene monomer (e.g. isoprene) and (ii) <=50wt% monomer copolymerizable therewith and subjecting the mixture to emulsion polymerization in the presence of a polymerization initiator (e.g. hydrogen peroxide).

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a high nitrile polymer with improved impact resistance. More specifically, the present invention relates to an improvement in a method for polymerizing acrylonitrile and a monomer copolymerizable therewith in an aqueous medium in the presence of a conjugated diene synthetic rubber.

[Conventional technology]

Rubber-reinforced high nitrile-containing resins are thermoplastic polymers with impact resistance, in addition to high gas and vapor barrier properties and excellent solvent resistance, which are inherent to high nitrile resins. It is attracting attention as a container and packaging material for cosmetics and other fields.

Regarding the production method of rubber-reinforced high nitrile-containing resin, various polymerization methods have been studied so far.

A number of improved techniques have been demonstrated.

For example, a method in which monomers consisting of unsaturated nitrile and acrylic acid alkyl ester are polymerized by batch addition to conjugated diene/nitrile copolymer rubber (Japanese Patent Publication No. 46-250
No. 05), when nitrile and a monomer copolymerizable with the nitrile are polymerized in the presence of a diene-based synthetic rubber, the rubber is preswollen with a portion of the monomer, and the remaining monomer is continuously added. A method (Japanese Unexamined Patent Publication No. 50/75294), in which monomers consisting of nitrile and aromatic vinyl are polymerized in the presence of a diene synthetic rubber, the polymer is added at a rate determined as a function of the polymerization temperature. (Japanese Patent Application Laid-open No. 50-22086)
etc.

[Problem that the invention seeks to solve]

The polymerization method used in this technology is the emulsion polymerization method, which is carried out in an aqueous medium, or the suspension polymerization method, because of the ease of reaction control due to the advantage of heat removal and the ease of post-treatment after polymerization. Generally adopted. In addition, there are two methods of adding monomers for graft polymerization to rubber: single-batch method and continuous method. The composition of the polymer produced due to the fact that the reaction occurs and it becomes difficult to remove the polymerization exotherm, requiring an external cooler or frozen water, and the difference in reactivity between the nitrile and the monomer copolymerizable with it. The disadvantage is that it is difficult to control uniformly.

Therefore, in practical terms, it is advantageous to carry out polymerization while controlling the reaction by adjusting the amount of monomers added and adding them continuously or in portions.

However, in polymerization by continuous or divided addition of monomers, the monomer concentration in the polymerization system is always diluted compared to the one-batch method, so various factors (monomer concentration, Initiator amount 4 Emulsifier amount.

There was a problem in that the amount of dispersant (1, polymerization temperature, etc.) has a complex influence, and the reproducibility of one polymerization is poor, resulting in variations in quality of polymers from batch to batch.

An object of the present invention is to solve this problem and provide a polymerization method capable of obtaining a nitrile polymer having excellent impact resistance with good reproducibility.

[Means for solving problems]

As a result of intensive research, the present inventors found that in a method of graft polymerization by adding acrylonitrile and a monomer copolymerizable with the diene synthetic rubber to diene-based synthetic rubber in an aqueous medium, The present inventors have discovered that it is necessary to use a specific amount or more of nitrile in water in order to obtain a desired high impact resistant nitrile polymer with good reproducibility, and have thus completed the present invention.

That is, 1 the present invention provides at least 5 parts by weight of a conjugated diene synthetic rubber consisting of 50% by weight or more of a conjugated diene monomer and 50% by weight or less of a monomer copolymerizable therewith.
Monomer mixture containing 0% by weight of acrylonitrile 100
This is a method for producing a high nitrile polymer, which is characterized in that when polymerizing part by weight in an aqueous medium, at the start of one polymerization, the acrylonitrile monomer is present in a polymerization system with a solubility higher than the solubility in water at the polymerization initiation temperature.

In the present invention, the impact-resistant nitrile polymer is obtained by graft polymerizing a large proportion of acrylonitrile and other monomer components copolymerizable with the same onto a preformed conjugated diene synthetic rubber. and by commonly known polymerization methods such as emulsion or suspension polymerization in an aqueous medium.
Polymerization can be carried out by batchwise, continuous or portionwise addition of monomers and other ingredients at temperatures of about 0 DEG to 100 DEG C. with the exclusion of oxygen. Preferred is an aqueous emulsion polymerization method in which monomers are added continuously or in portions.

In the present invention, in the polymerization system at the time of polymerization initiation.

It is important that the amount of acrylonitrile used in water is at least equal to or greater than the saturated dissolution amount of acrylonitrile in water at the polymerization temperature, so that the grafting reaction of acrylonitrile to rubber proceeds in a stable manner. In addition, the desired high impact strength of the final polymer can be obtained with good reproducibility.

Examples of the conjugated diene monomer used in the present invention include 1,3-butadiene, inoprene, chloroprene, etc. From the viewpoint of easy availability and polymerizability, 1,3-butadiene,
Isoprene is preferred. or.

As a monomer copolymerizable with a conjugated diene monomer.

Examples include unsaturated nitriles, unsaturated carboxylic acid esters, aromatic vinyl compounds, etc., and one or more of these may be used.

Acrylonitrile is an unsaturated nitrile.

Examples include methacrylonitrile and α-chloroacrylonitrile, with acrylonitrile being preferred.

Metagrilonitrile.

In addition, unsaturated carboxylic acid esters include methyl and ethyl acrylic acid or methacrylic acid.

Examples include esters such as propyl and butyl,
Particularly preferred is methyl acrylate.

They are acrylated ethyl, methyl methacrylate, and ethyl methacrylate.

Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, vinyltoluenes, and vinylxylenes, with styrene being preferred.

Examples of monomers to be grafted onto the rubber include acrylonitrile and monomers copolymerizable with it, such as unsaturated carboxylic acid esters and aromatic vinyl compounds.

A monomer consisting of one or more of vinyl esters, vinyl ethers, α-olefins, etc.

As for the unsaturated carboxylic acid ester and the aromatic vinyl compound, those exemplified above can be used.

Examples of vinyl esters include vinyl acetate, vinyl propionate, and vinyl roughate.

Preferred is vinyl acetate.

In addition, examples of vinyl ether include methyl vinyl ether,
Examples include ethyl vinyl ether, flobyl vinyl ethers, butyl vinyl ethers, methyl inopropenyl ether, ethyl isopropenyl ether, and the most preferred are methyl vinyl ether, ethyl vinyl ether, flobyl vinyl ethers, and butyl vinyl ethers.

α-olefins include inbutene, 2-methyl-1-
Butene, 2-methyl-1-pentene, 2-methyl-1-
hexene, 2-methyl-1-heftene, 2-methyl-1
-Octene, 2-ethyl-1-buty7,2-propyl-
Examples include 1-butene. The most preferred is Inobten.

Conjugated diene synthetic rubbers useful in the present invention include:

Conjugated diene monomer 50 represented by 1.3-butadiene
% by weight or more and a monomer copolymerizable with this, (
For example, it has a composition consisting of 50% by weight or less of acrylonitrile, preferably 60% or less of conjugated diene.
0jE amount%. It is obtained by polymerizing in an aqueous medium in the presence of an emulsifier or dispersant, a polymerization initiator, a molecular weight regulator, a pH regulator, and other additives at a desired temperature after removing oxygen. Monomer and other addition methods are single batch type.
Either a continuous type or a divided type may be used.

Emulsion or suspension polymerization is preferred as a method for polymerizing monomers mainly composed of unsaturated nitrile in the presence of the conjugated diene synthetic rubber previously produced by the above method. Polymerization is carried out with a polymerization initiator at a temperature of ~100°C. The monomer addition method may be one-time, continuous or divided, and continuous or divided is preferred for the purpose of controlling the heat of the polymerization reaction and making the composition of the resulting polymer uniform. Also, 1 emulsifier, 1 dispersant, 1 polymerization initiator.

If necessary, molecular weight regulators, pH regulators, and other additives may be added continuously or in portions.

The amount of conjugated diene synthetic rubber used is the total monomer weight lO
About 1 to 40 parts by weight, preferably 1 to 40 parts by weight,
20 parts. In general, as the relative proportion of rubber components in the final polymer increases, impact strength increases, but gas and vapor barrier properties decrease somewhat, resulting in physical properties tailored to the intended use. Just use the amount of rubber.
.

The co-supplied acrylonitrile and the monomer copolymerizable therewith preferably contain at least 50% by weight of nitrile, particularly preferably about 60 to 90% by weight, based on the total weight of the monomers.

In the present invention, the acrylonitrile/water ratio at the start of polymerization is 1. For example, when emulsion polymerization is carried out at a polymerization temperature of 60°C, the saturated solubility of acrylonitrile in water at 60°C is approximately 1. Since it is 9wt%,
It is necessary to set the amount ratio of acrylonitrile and water at the time of initiation of polymerization so that the amount is at least 9 wt % or more based on water. If we consider the solubilization of acrylonitrile in emulsifiers, etc.

Although it depends on the amount of emulsifier used, it is preferably 11 wt % or more based on water in normal emulsion polymerization.

If monopolymerization is carried out using the above method of the present invention, a nitrile thermoplastic polymer having high impact strength can be obtained.

Can it be obtained stably without variation from batch to batch?

When the saturated solubility of Aku IJ Cl nitrile is lower than the known saturated solubility, the resulting polymer has very little variation between batches in terms of impact resistance, and generally only polymers with low impact strength are obtained.

When polymerizing monomers in the presence of rubber, usable polymerization initiators (or catalysts) include peracid catalysts such as persulfate, peracetic acid, and perphthalic acid, persulfur rd potassium, etc. Persalt catalyst, hydrogen peroxide, benzoyl peroxide, chlorbenzoyl peroxide, brobenzoyl peroxide, naphthyl peroxide, acetyl peroxide, benzoylacetyl peroxide. Lauryl peroxide.

Zaku/Nil peroxide, di-t-butyl peroxide, peracid (hidicumyl, cumyl hydroperoxide, t-butyl peracetate, sodium peroxide, barium peroxide, etc.) peroxide catalyst, t-butyl hydroperoxide There are azo catalysts such as alkyl hydroperoxides such as, for example, azobisisobutyronitrile, and these can be used alone (. can be used in a mixture of two or more types.

The preferred polymerization method in the present invention is an aqueous emulsion polymerization method, and the emulsifier that can be used is myristic.

Sodium and potassium salts of lauric acid, valmitic acid, oleic acid, stearic acid, sodium, potassium and ammonium salts of lauryl sulfate, cetyl sulfate, oleyl sulfonic acid, stearyl sulfonic acid, sulfated castor oil, laurylamine hydrochloride, stearyl Higher amine salts such as amine hydropromide, polyvinylpyrrolidone.

There are polymeric substances such as sodium polyacrylate and methylcellulose.

The polymer product is obtained in the form of a latex, and the polymer is coagulated by a conventionally known method, such as a coagulation method using an electrolyte or a solvent, or a freezing method, and then washed with water and dried to obtain a polymer.

It is also possible to add plasticizers, stabilizers, lubricants, dyes and pigments, fillers, etc. during or after the polymerization, if necessary.

The polymer produced by the method of the present invention is a thermoplastic resin that can be easily thermoformed by conventional molding methods such as extrusion molding, injection molding, blow molding, etc. using known thermoplastic resin materials; High barrier properties against gas,
It has excellent solvent resistance and crushing impact resistance.
It is useful as a packaging container material for films and other types of liquids and solids.

〔Example〕

The present invention will be explained below with reference to Examples.

In the examples, "1 part" and "%" are both based on weight.

Example 1 (2) Production of conjugated diene rubber latex A mixture consisting of the following components was placed in a stainless steel polymerization reactor to remove oxygen and polymerized at 45° C. for 20 hours with stirring.

Acrylonitrile 40 parts Butadiene-1,360〃 Fatty acid soap 2.4'/Azobisinobutyronitrile 0.31/[-dodecylmercaptan 0.5#Water
200 The monomer conversion rate was 90%, and the solid content concentration of the latex was 30%.

(B) Production of graft polymer Tot of the main shaft raw material containing the rubber latex obtained in A above
The amount of al used is as follows.

Water 235 parts Acrylonitrile 70// Methyl acrylate 3011 Sodium dioctyl sulfosuccinate 1.0 parts Polyvinylpyrrolidone 0.41/Potassium persulfate 0.06 parts N-dodecyl mercaptan 1.0 parts Prepare auxiliary raw materials.

After removing oxygen, polymerization was started at 60° C. with stirring.

Sokata Iai Memorial Water 127 parts Methyl acrylate 5/1 Latex of above A 33/l Sodium dioctysulfoconodzate 0.2 parts Polyvinylpyrrolidone o, os
Partial Passage Potassium Sulfate 0.06/7 From 30 minutes after the start of polymerization, the remaining main and auxiliary raw materials listed below were continuously added over a period of 5 hours, and polymerization was continued at 60°C.

Continuous additive composition Water 108 parts Acrylonitrile 56/l Methyl acrylate 24# Sodium dioctyl sulfosuccinate 0.8 parts Polyvinylpyrrolidone 0.32 parts n-dodecyl mercaptan 1.6 parts After completing the addition of the above raw materials,
Polymerization was continued for an additional hour to achieve a monomer conversion rate of 90%. The obtained latex was coagulated with an aqueous aluminum sulfate solution.

A powdered polymer was obtained by washing with water and drying.

When this polymer was pressure-molded at 170°C and 140 kg/cd, a transparent, pale yellow sheet was obtained.

A test piece was prepared from this sheet, and the notched Izo impact value was measured at 23 DEG C. and a load of 9 at 3.828 in accordance with ASTM D256. Further, in order to examine the processability of the polymer 1, the flow rate was measured at 200 DEG C. and under a load of 12.5 kg using a melt indexer according to ASTM Di238. The measurement results are shown in Table 1.

In Example IB, the initial amount of water was changed without changing the total amount of water used (235 g), and agrilonyl/
The water ratio was 15%, 20%, and 7%, respectively.

Polymerization was carried out in the same manner as in Example 1 except that the content was changed to 8%. Table 1 shows the results of measuring the physical properties of the obtained polymer.

*1) According to AsTM D-256, 23°C.

The notched isot impact value was measured at a load of 3.828 ks.

The average value and the degree of variation (σ) of the impact values of polymers obtained by performing polymerization five times under the same conditions are shown.

*2) 200°C according to ASTM D-1238.

The amount of resin flowed out under a load of 12.5 kg was measured.

〔Effect of the invention〕

As stated in the method of the present invention, when the acrylonitrile/water ratio at the start of one polymerization is higher than the solubility of acrylonitrile in water at one polymerization stage, the resulting polymer has excellent impact resistance. , has stable high impact strength.

Claims (1)

[Claims] 1. At least 50% by weight of acrylonitrile in the presence of 1 to 40 parts by weight of a conjugated diene synthetic rubber consisting of 50% by weight or more of a conjugated diene monomer and 50% by weight or less of a monomer copolymerizable therewith. A high nitrile polymer characterized in that when 100 parts by weight of a monomer mixture containing 100 parts by weight is polymerized in an aqueous medium, the acrylonitrile monomer is present in the polymerization system at a temperature higher than its solubility in water at the polymerization initiation temperature. Production method.