KR20210121546A - Method for preparing nitrile based copolymer - Google Patents

Abstract

The present invention relates to a method for preparing a nitrile-based copolymer which provides improved latex stability and improves elasticity and tensile strength of articles molded from the latex. The method includes the steps of: (S10) preparing main monomers containing a conjugated diene-based monomer and ethylenically unsaturated nitrile-based monomer; (S20) introducing a part of the main monomers prepared in step (S10), allyl (meth)acrylate and alpha-methylstyrene dimer to a reactor to carry out primary polymerization, and introducing a polymerization terminator, when the polymerization conversion reaches 35-65%, to terminate the polymerization; and (S30) introducing the remaining part of the main monomers prepared in step (S10), allyl (meth)acrylate and alpha-methylstyrene dimer, after terminating the polymerization, to carry out secondary polymerization, and introducing a polymerization terminator, when the polymerization conversion reaches 75-90%, to obtain latex containing a nitrile-based copolymer.

Description

Method for producing a nitrile-based copolymer {METHOD FOR PREPARING NITRILE BASED COPOLYMER}

The present invention uses a third monomer, a molecular weight modifier, and a specific emulsifier in the polymerization process of a nitrile-based copolymer designed in two steps to reduce the amount of emulsifier used, improve latex stability by minimizing the generation of new particles, and molded from latex It relates to a method for producing a nitrile-based copolymer with improved elasticity and tensile strength of the molded article.

In general, nitrile rubber is a polymer prepared by copolymerizing a conjugated diene-based monomer such as butadiene and an ethylenically unsaturated nitrile-based monomer such as acrylonitrile. Nitrile rubber is excellent in oil resistance and is most preferably used as an oil seal for O-rings and V-packings used in lubricating oil, hydraulic oil, fuel oil, etc. .

A common requirement of such nitrile rubber is excellent tensile strength, which is the maximum force required to rupture the rubber, and thus a high crosslinking density is required. When the crosslinking density of the rubber polymer increases, the tensile strength increases, but since the elongation decreases as the crosslinking density becomes too high, it is important to control the crosslinking density to have appropriate elasticity.

On the other hand, the usable temperature of the nitrile rubber varies greatly depending on the compounding, but in -50 ° C to - 120 ° C, low nitrile is used, particularly for low-temperature applications, in polar or cold regions equipment or aircraft. In addition, a large amount of nitrile not only has good heat resistance and mechanical properties, but also has excellent gas permeability, so that it can be used sufficiently for vacuum use up to about 10 torr. However, it is necessary to solve problems such as high crosslinking efficiency and short vulcanization time at high temperature during injection molding, and poor productivity in order to periodically remove foreign substances due to residues in the mold during manufacturing.

Therefore, the present inventor designs the polymerization process of the nitrile-based copolymer in two steps, and if a third monomer, a molecular weight regulator and a specific emulsifier are used in the polymerization process, the amount of the emulsifier is reduced and new particle generation (new particle generation) is used. ), the stability of latex can be improved by minimizing, and the elasticity and tensile strength of a molded article formed from latex can be significantly improved, and the present invention has been completed.

KR 2016-0127008 A

The problem to be solved in the present invention is to design a polymerization process of a nitrile-based copolymer in two steps in order to solve the problems mentioned in the technology that is the background of the invention, and in the polymerization process, a third monomer, a molecular weight regulator and The purpose of the use of certain emulsifiers is to reduce the emulsifier, to improve latex stability by minimizing the formation of new particles, and to improve the elasticity and tensile strength of molded articles from latex.

According to an embodiment of the present invention for solving the above problems, preparing a main monomer comprising a conjugated diene-based monomer and an ethylenically unsaturated nitrile-based monomer (S10); A part of the main monomer, allyl (meth)acrylate and α-methylstyrene dimer prepared in step (S10) are put into the reactor for primary polymerization, and the polymerization conversion rate is 35 to 65% at a time point terminating the polymerization by adding a polymerization terminator (S20); And after the polymerization is completed, the remainder of the main monomer prepared in step (S10), allyl (meth)acrylate and alpha-methylstyrene dimer are added to the reactor for secondary polymerization, and the polymerization conversion rate is 75 to 90%. It provides a method for producing a nitrile-based copolymer comprising the step (S30) of adding a polymerization terminator to terminate polymerization to prepare a latex containing the nitrile-based copolymer (S30).

In the method for producing a nitrile-based rubber according to the present invention, the polymerization process of the nitrile-based rubber is designed in two steps, and a third monomer, a molecular weight regulator, and a specific emulsifier are used in the polymerization process to reduce the amount of the emulsifier, and to reduce the amount of new particles. By minimizing the production, latex stability can be improved, and elasticity and tensile strength of a molded article molded from latex can be significantly improved.

The terms or words used in the description and claims of the present invention should not be construed as being limited to their ordinary or dictionary meanings, and the inventor should properly understand the concept of the term in order to best describe his invention. Based on the principle that can be defined, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

In the present invention, the term 'copolymer' may mean including all copolymers formed by copolymerizing comonomers, and as a specific example, may mean including both random copolymers and block copolymers.

In the present invention, the term 'rubber' refers to a plastic material having elasticity, and may mean rubber, elastomer, or synthetic latex.

Hereinafter, the present invention will be described in more detail to help the understanding of the present invention.

According to the present invention, there is provided a method for preparing a nitrile-based copolymer. The method for preparing the nitrile-based copolymer includes the steps of preparing a main monomer including a conjugated diene-based monomer and an ethylenically unsaturated nitrile-based monomer (S10); A part of the main monomer, allyl (meth)acrylate and α-methylstyrene dimer prepared in step (S10) are put into the reactor for primary polymerization, and the polymerization conversion rate is 35 to 65% at a time point terminating the polymerization by adding a polymerization terminator (S20); And after the polymerization is completed, the remainder of the main monomer prepared in step (S10), allyl (meth)acrylate and alpha-methylstyrene dimer are added to the reactor for secondary polymerization, and the polymerization conversion rate is 75 to 90%. It may include a step (S30) of preparing a latex containing a nitrile-based copolymer by adding a polymerization terminator to terminate the polymerization.

That is, in the method for preparing the core-shell copolymer according to the present invention, allyl (meth)acrylate as a third monomer and alpha-methylstyrene dimer as a molecular weight regulator are used in each step of the polymerization process of the nitrile-based copolymer designed in two steps. By dividing into the nitrile-based copolymer to improve the stability of the latex, there is an effect of further improving the elasticity and tensile strength of the molded article molded from the nitrile-based copolymer.

According to an embodiment of the present invention, in the step (S10), the main monomer is a main monomer forming a nitrile-based copolymer, and includes a conjugated diene-based monomer and an ethylenically unsaturated nitrile-based monomer, and the conjugated diene-based monomer By controlling the content of the monomer and the ethylenically unsaturated nitrile-based monomer, the physical properties of the nitrile-based copolymer can be controlled.

The conjugated diene-based monomer is 1,3-butadiene, 1,4-butadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,3-pentadiene, piperylene, It may include at least one selected from the group consisting of 3-butyl-1,3-octadiene, 2-phenyl-1,3-butadiene, and isoprene, and as a specific example, the conjugated diene-based monomer is 1,4-butadiene. can be

The content of the conjugated diene-based monomer may be 50 wt% to 90 wt%, 60 wt% to 80 wt%, or 65 wt% to 70 wt% based on the total content of the main monomer.

The ethylenically unsaturated nitrile-based monomer may include at least one selected from the group consisting of acrylonitrile, methacrylonitrile, α-chloronitrile and α-cyanoethylacrylonitrile. The sexually unsaturated nitrile-based monomer may be acrylonitrile.

The content of the ethylenically unsaturated nitrile-based monomer may be 10 wt% to 50 wt%, 20 wt% to 40 wt%, or 30 wt% to 35 wt% based on the total content of the main monomer.

By polymerizing a main monomer including a conjugated diene-based monomer and an ethylenically unsaturated nitrile-based monomer within the above range to prepare a nitrile-based copolymer, the flexibility, oil resistance and tensile strength of a molded article produced therefrom can be improved.

According to an embodiment of the present invention, in step (S20), a part of the main monomer prepared in step (S10), allyl (meth)acrylate and alpha-methylstyrene dimer are added to complete the primary polymerization and polymerization. It may be a step of preparing a pre-latex through the

Specifically, in the step (S20), a part of the main monomer including the conjugated diene-based monomer and the ethylenically unsaturated nitrile-based monomer, allyl (meth)acrylate as the third monomer, and alpha-methylstyrene dimer as a molecular weight regulator were added to the reactor. Primary polymerization may be performed by input, and polymerization may be terminated by adding a polymerization terminator when the polymerization conversion rate is 35% to 65%, 40% to 60%, or 45 to 55%. A part of the main monomer input in step (S20) may be 30 to 70 parts by weight, 40 to 60 parts by weight, or 45 to 55 parts by weight based on 100 parts by weight of the total main monomer prepared in step (S10). In addition, the time point at which the polymerization conversion rate is 35 to 65% may mean a time point at which the polymerization conversion rate is 35 to 65% based on 100 parts by weight of the total main monomer prepared in step (S10).

In the conventional seed polymerization, the size of the particles was increased by using less than 10 parts by weight of seeds with a conversion rate of 90% or more based on 100 parts by weight of the total copolymer, but this method is advantageous for increasing the size of the particles and increasing the stability of the latex. However, since gelation or non-linear polymer distribution due to high polymerization conversion is very high, it is not suitable as a method for preparing a linear polymer. For this reason, the devised methods tried to solve the above-mentioned problems through the divided input of the monomer, but the generation of new particles could not be suppressed, so the particle distribution was widened, and this made it impossible to secure the polymerization stability of the latex within the limited emulsifier content. There was a problem in that the physical properties of the copolymer were deteriorated due to the nonlinear polymer generated from the small particles.

In order to solve the above problems, in the present invention, as described above, after the primary polymerization, a polymerization terminator is added to terminate the polymerization when the polymerization conversion rate is 35% to 65%, without the process of terminating the polymerization in the middle. It suppresses the generation of relatively new particles compared to the conventional method of performing only divided input of the monomer, and the size of the particles can be uniformly increased through the seeds generated in the primary polymerization, so that more stable polymerization is possible, and linear nitrile It is possible to increase the distribution of the based copolymer.

On the other hand, according to an embodiment of the present invention, the polymerization conversion rate is obtained by taking a predetermined amount of a sample from the reactant being reacted at a predetermined time interval, calculating the TSC (Total Solid Content) of the sample, and substituting it in Equation 1 below. may have been calculated.

[Equation 1]

Polymerization conversion (%) = {(TSC x W _t,t - W _t,s )/ W _t,m } x 100

* TSC: weight of dried sample solids/weight of sample before drying

* W _t,t : Sum of the weight of monomers, water and auxiliary materials added during polymerization

* W _t,s : Sum of the weight of additives other than monomer and water

* W _t,m : Sum of the weight of the monomers added during polymerization

* Supplementary materials: Molecular weight regulators such as emulsifiers, initiators, and molecular weight regulators excluding monomers and water added during polymerization

According to an embodiment of the present invention, the step (S20) may be performed in the presence of an emulsifier. For example, the step (S20) may be performed in the presence of an emulsifier comprising at least one selected from the group consisting of fatty acid compounds and sulfonate-based compounds.

The fatty acid compound is, for example, oleic acid, rosin acid, lauric acid, myristic acid, palmitic acid, stearic acid ), naphthalene sulfonic acid, and one or more fatty acids selected from the group consisting of eicosanoic acid, or salts thereof. As a specific example, the fatty acid compound may be a mixture of one or more selected from oleic acid, palmitic acid, and stearic acid.

The sulfonate-based compound may include, for example, at least one selected from the group consisting of a sulfosuccinate-based compound, a disulfonate-based compound, and a linear alkylbenzene sulfonate-based compound. As a specific example, the sulfonate-based compound may be alkyldiphenyloxide disulfonate or sodium dodecylbenzene sulfonate.

The content of the emulsifier may be 0.3 to 3.5 parts by weight based on 100 parts by weight of the total main monomer. For example, the content of the emulsifier may be 0.4 to 2.5 parts by weight, 0.5 to 2 parts by weight, or 0.5 to 1.5 parts by weight based on 100 parts by weight of the total main monomer. As such, by performing the primary polymerization using a small amount of the emulsifier, the residual amount of the emulsifier in the nitrile-based copolymer can be reduced.

According to an embodiment of the present invention, step (S20) may be performed in the presence of an emulsifier including a mixture of a fatty acid compound and a sulfonate-based compound.

At this time, in the emulsifier, the content of the fatty acid compound may be 0.01 to 0.5 parts by weight based on 100 parts by weight of the total main monomer. For example, the content of the fatty acid compound may be 0.05 to 0.4 parts by weight, 0.05 to 0.3 parts by weight, or 0.05 to 0.15 parts by weight based on 100 parts by weight of the total main monomer.

In addition, the content of the sulfonate-based compound may be 0.4 to 1.5 parts by weight based on 100 parts by weight of the total main monomer. For example, the content of the sulfonate-based compound may be 0.4 to 1 parts by weight, 0.5 to 0.9 parts by weight, or 0.5 to 0.8 parts by weight based on 100 parts by weight of the total main monomer.

As such, by mixing the fatty acid compound and the sulfonate compound within the above range and using it as an emulsifier in step (S20), the content of the residual emulsifier in the copolymer can be reduced, and the stability of the latex can be increased.

According to an embodiment of the present invention, in the step (S20), allyl (meth)acrylate as a third monomer and alpha-methylstyrene dimer (AMSD) as a molecular weight control agent together with the above-described main monomer and emulsifier (α-methylstyrene dimer, AMSD) By adding , the polymerization reaction rate is increased to form a uniform crosslinking site in the polymer during polymerization, thereby improving the crosslinking density. Through this, while the nitrile-based copolymer has a molecular structure with high crosslinking density, the elongation of the molded article prepared from the nitrile-based copolymer can be improved.

According to an embodiment of the present invention, the content of allyl (meth)acrylate added in step (S20) is 0.1 to 0.5 parts by weight, 0.2 to 0.5 parts by weight, or 0.3 to 0.5 parts by weight based on 100 parts by weight of the total main monomer. It may be 0.5 parts by weight. When allyl (meth)acrylate is added within the above range, the crosslinking density in the nitrile-based copolymer can be improved, and the tensile strength of the molded article formed from the nitrile-based copolymer is excellent.

In addition, the content of the alpha-methylstyrene dimer added in step (S20) may be 0.1 to 0.5 parts by weight, 0.2 to 0.5 parts by weight, or 0.3 to 0.5 parts by weight based on 100 parts by weight of the total main monomer. When the alpha-methylstyrene dimer is added within the above range, the vulcanization properties of the composition including the nitrile-based copolymer may be improved, and the elongation of the molded article formed from the nitrile-based copolymer may be excellent.

According to an embodiment of the present invention, in step (S20), the polymerization may be carried out by an emulsion polymerization method for carrying out radical polymerization of each monomer, and as a specific example, carried out in the presence of ion-exchanged water and a polymerization initiator, etc. can be

According to an embodiment of the present invention, in the emulsion polymerization, water may be used as the ion-exchanged water, and the ion-exchanged water may be used in an amount of 100 to 400 parts by weight based on 100 parts by weight of the main monomer.

According to an embodiment of the present invention, during the emulsion polymerization, the polymerization initiator input may be a radical initiator. The radical initiator may include, for example, inorganic peroxides such as sodium persulfate, potassium persulfate, ammonium persulfate, potassium perphosphate and hydrogen peroxide; t-butyl peroxide, cumene hydroperoxide, p-mentane hydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, acetyl peroxide, isobutyl peroxide, octanoyl peroxide, dibenzoyl peroxide organic peroxides such as oxide, 3,5,5-trimethylhexanol peroxide and t-butyl peroxy isobutylate; It may be at least one selected from the group consisting of azobis compounds such as azobis isobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexane carbonitrile, and azobisisobutyronitrile (butyric acid) methyl. have. As a specific example, the radical initiator may be an organic peroxide, and as a more specific example, p-mentane hydroperoxide. The polymerization initiator may be added, for example, in an amount of 0.01 to 2 parts by weight, or 0.02 to 1.5 parts by weight, based on 100 parts by weight of the total of the main monomer, and within this range, the polymerization rate can be appropriately controlled, so that polymerization can be controlled. At the same time, there is an effect of excellent productivity of the nitrile-based copolymer.

According to an embodiment of the present invention, during the emulsion polymerization, an activator, a chelating agent, a dispersant, a pH adjuster, an oxygen scavenger, a particle size adjuster, an anti-aging agent, and an oxygen trap within a range that does not reduce the physical properties of the copolymer, if necessary An additive such as an oxygen scavenger may be added.

According to an embodiment of the present invention, the polymerization reaction in step (S20) may be carried out in a temperature range of 10 °C to 90 °C, more specifically 10 °C to 75 °C.

According to an embodiment of the present invention, polymerization may be terminated by adding a polymerization terminator after the primary polymerization in step (S20). At this time, the polymerization terminator is, for example, hydroxylamine, N,N-diethyl hydroxylamine, hydroxylamine sulfate, diethyl hydroxylamine, hydroxylamine sulfonic acid and its alkali metal ion, sodium dimethyl dithio aromatic hydroxy dithio carboxylic acids such as carbamates, hydroquinone derivatives, hydroxy diethyl benzene dithio carboxylic acid, hydroxy dibutyl benzene dithio carboxylic acid, and the like. As a specific example, the polymerization terminator may be N,N-diethyl hydroxylamine. The polymerization terminator may be added in an amount of 0.01 to 0.1 parts by weight, or 0.03 to 0.08 parts by weight based on 100 parts by weight of the total main monomer.

According to an embodiment of the present invention, in the step (S30), the remainder of the main monomer prepared in the step (S10), allyl (meth)acryl in the pre-latex prepared through the termination of polymerization after the primary polymerization in the step (S20) It may be a step of preparing a latex including a final nitrile-based copolymer by adding a latex and alpha-methylstyrene dimer for secondary polymerization, and adding a polymerization terminator.

Specifically, the pre-latex, which is a product prepared through the termination of polymerization after the primary polymerization in step (S20), is stirred for 10 to 60 minutes, 15 to 45 minutes, or 20 to 40 minutes, and then prepared in step (S10). After secondary polymerization by adding the remainder of the main monomer, allyl (meth)acrylate and alpha-methylstyrene dimer, polymerization at a polymerization conversion rate of 75% to 90%, 75% to 85%, or 78 to 82% The polymerization can be terminated by adding a terminator. The remainder of the main monomer input in step (S30) may mean the remainder except for a part of the main monomer input in step (S20) from the entire main monomer prepared in step (S10). The monomer balance may be 30 to 70 parts by weight, 40 to 60 parts by weight, or 45 to 55 parts by weight based on 100 parts by weight of the total main monomer prepared in step (S10). In addition, the time point at which the polymerization conversion rate is 75 to 90% in step (S30) may mean a time point when the polymerization conversion rate is 75 to 90% based on 100 parts by weight of the total main monomer prepared in step (S10).

In this way, a portion of the main monomer is added for primary polymerization, and after terminating the reaction, the remainder of the main monomer containing the same amount of monomer is added to perform secondary polymerization, and through the steps of terminating the reaction, latex of polymerization stability and storage stability can be improved.

According to an embodiment of the present invention, in the step (S30), allyl (meth)acrylate as a third monomer and alpha-methylstyrene dimer as a molecular weight regulator are added together with the above-mentioned main monomer, thereby providing a nitrile-based high crosslinking density. While having a copolymer structure, the elongation of a molded article manufactured from a nitrile-based copolymer may be improved.

According to an embodiment of the present invention, the content of allyl (meth)acrylate added in step (S30) is 0.1 to 0.5 parts by weight, 0.2 to 0.5 parts by weight, or 0.3 to 0.5 parts by weight based on 100 parts by weight of the total main monomer. It may be 0.5 parts by weight. When allyl (meth)acrylate is added within the above range, the crosslinking density in the nitrile-based copolymer can be improved, and the tensile strength of the molded article formed from the nitrile-based copolymer is excellent.

In addition, the content of the alpha-methylstyrene dimer added in step (S30) may be 0.1 to 0.5 parts by weight, 0.2 to 0.5 parts by weight, or 0.3 to 0.5 parts by weight based on 100 parts by weight of the total main monomer. When the alpha-methylstyrene dimer is added within the above range, the vulcanization properties of the composition including the nitrile-based copolymer may be improved, and the elongation of the molded article formed from the nitrile-based copolymer may be excellent.

In particular, according to the preparation method of the present invention, the above-mentioned type of emulsifier, allyl (meth)acrylate and alpha-methylstyrene dimer are added together with a part of the main monomer to perform the primary polymerization (S20), and then the main monomer When secondary polymerization (S30) is performed by adding allyl (meth)acrylate and alpha-methylstyrene dimer along with the remainder of By maximizing the particle size uniformly and at the same time increasing the polymerization reaction rate to prevent gelation during polymerization to form a uniform cross-linking site in the copolymer, the distribution of a linear nitrile-based copolymer with high cross-linking density can be increased. , it is possible to suppress the formation of coagulants in the copolymer. In addition, the content of the residual emulsifier and residual inorganic matter of the copolymer can be further reduced. Through this, the nitrile-based copolymer may have a linear molecular structure with high crosslinking density, and mechanical properties such as elongation and tensile strength of a molded article manufactured therefrom may be improved.

In addition, by dividing allyl (meth)acrylate and alpha-methylstyrene dimer in each step in steps (S20) and (S30), the size of the copolymer particles is stably maximized, and new particles are generated in the latex. can promote the formation of a copolymer having a uniform particle size by suppressing the reaction, and also has the effect of inhibiting the formation of latex coagulation by improving polymerization stability.

According to an embodiment of the present invention, in step (S30), the polymerization may be carried out by an emulsion polymerization method for carrying out radical polymerization of each monomer, and as a specific example, carried out in the presence of ion-exchanged water and a polymerization initiator, etc. can be

The type and content of the ion-exchanged water and the polymerization initiator input in the step (S30) may be the same as the type and content of the ion-exchange water and the polymerization initiator input in the step (S20).

According to an embodiment of the present invention, during the emulsion polymerization in step (S30), if necessary, an activator, a chelating agent, a dispersant, a pH adjuster, a deoxidizer, a particle size adjuster within the range that does not reduce the physical properties of the copolymer latex , antioxidants, and additives such as oxygen scavengers may be added.

According to an embodiment of the present invention, the polymerization reaction in step (S30) may be carried out in a temperature range of 10°C to 90°C, more specifically, 10°C to 75°C.

According to an embodiment of the present invention, polymerization may be terminated by adding a polymerization terminator after the secondary polymerization in step (S30). In this case, the type and content of the polymerization terminator may be the same as the type and content of the polymerization terminator input in step (S20).

According to an embodiment of the present invention, the step (S40) of coagulating the copolymer latex by adding a coagulant to the copolymer latex produced after the step (S30) may be further included.

Specifically, the step (S40) may be a step of preparing a nitrile-based latex aggregate by adding a coagulant to the latex containing the nitrile-based copolymer prepared through the steps (S20) and (S30) and agglomeration.

The coagulant may include, for example, at least one selected from monovalent, divalent and trivalent ionic metal salts. Specifically, when the metal salt is dissolved in water, at least one metal ion selected from the group consisting of a monovalent metal ion, a divalent metal ion, and a trivalent metal ion may be dissociated. For example, the monovalent ionic metal salt may include a salt containing at least one metal selected from the group consisting of lithium, sodium and potassium. As a more specific example, the monovalent ionic metal salt may be a metal chloride such as sodium chloride, lithium chloride, or lithium chloride; nitrates such as sodium acetate, potassium nitrate and lithium nitrate; It may include at least one selected from the group consisting of sulfates such as sodium sulfate, potassium sulfate and lithium sulfate. In addition, the divalent and trivalent ionic metal salts may be metal salts including one or more metals selected from the group consisting of magnesium, calcium, zinc, titanium, manganese, iron, cobalt, nickel, aluminum, and tin. The coagulant may be added in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the total main monomer. Within this range, aggregation of the nitrile-based copolymer can be effectively induced, and the residual amount of the coagulant can be lowered.

The agglomeration temperature may be, for example, 50 °C to 100 °C, 55 °C to 90 °C, or 60 °C to 80 °C. By agglomerating the copolymer latex at a temperature within this range, it is possible to improve cohesiveness and reduce the amount of residual coagulant to improve water resistance.

According to the present invention, there is provided a nitrile-based copolymer prepared by the method for producing a nitrile-based copolymer according to the present invention. The nitrile-based copolymer according to the present invention is prepared by the above-described manufacturing method, so that latex polymerization stability and storage stability are improved, the residual amount of the emulsifier is reduced, and the crosslinking density of the nitrile-based copolymer is high, while the nitrile-based copolymer is There is an excellent effect of elongation and mechanical properties of a molded article formed from

According to an embodiment of the present invention, the residual amount of the emulsifier in the nitrile-based copolymer may be 20,000 ppm or less. For example, the residual amount of the emulsifier in the nitrile-based copolymer may be 0.1 ppm to 20,000 ppm, 0.1 ppm to 19,000 ppm, or 0.1 ppm to 18,000 ppm. Contamination of the mold can be prevented during injection molding by using the nitrile-based rubber within this range.

According to an embodiment of the present invention, the Mooney viscosity (ML ₁₊₄ , 100 ℃) of the nitrile-based copolymer may be 1 to 100, 10 to 80, 20 to 80, or 25 to 50. Within this range, the workability of the copolymer composition including the nitrile-based copolymer is excellent.

According to the present invention, there is provided a nitrile-based copolymer composition comprising the nitrile-based copolymer according to the present invention. The nitrile-based copolymer composition according to the present invention includes the nitrile-based copolymer as a raw material rubber, and, if necessary, at least one selected from the group consisting of a vulcanizing agent, a vulcanization accelerator, a dispersing agent, a reinforcing filler and a dissolution accelerator. It may further include a molecular weight modifier.

The vulcanizing agent is powdered sulfur, sublimated sulfur, precipitated sulfur, surface treated sulfur, insoluble sulfur, sulfur chloride, sulfur dichloride, morpholine disulfide, alkylphenol disulfide, N,N'-dityro-bis(hexahydro-2H-a zepinone) and may include at least one selected from the group consisting of polysulfide.

The vulcanization accelerator may include at least one selected from the group consisting of zinc oxide, N-tert-butyl-2-benzothiazolesulfenamide (TBBS) and tetramethylthiuram monosulfite (TMTM).

The dispersant may include at least one selected from the group consisting of stearic acid, oleic acid, palmitic acid, and (anhydride) maleic acid.

The reinforcing filler may include at least one selected from the group consisting of carbon black, silica, limestone, mica, clay, and bentonite.

The dissolution accelerator may include at least one selected from the group consisting of di(2-ethylhexyl)adipate, di(2-ethylhexyl)phthalate, and diisodecyl phthalate.

According to the present invention, there is provided a molded article prepared from the nitrile-based copolymer composition according to the present invention. The molded article includes the nitrile-based copolymer prepared by the manufacturing method of the present invention, and thus has excellent tensile strength, hardness and vulcanization properties. The molded article may be, for example, a seal, cap, hose or diaphragm, O-ring seal, flat seal, corrugated seal ring, seal sleeve, seal cap, dust barrier cap, plug seal, insulating hose, oil cooler hose, intake hose, servo (servo) can be used as a control hose or a pump diaphragm, but is not limited thereto.

Hereinafter, the present invention will be described in more detail by way of Examples. However, the following examples are intended to illustrate the present invention, and it is clear to those skilled in the art that various changes and modifications are possible within the scope and spirit of the present invention, and the scope of the present invention is not limited thereto.

< Example >

Hereinafter, except for the main monomer used in the preparation of the acrylic copolymer, the input amounts of the third monomer and all components are shown based on 100 parts by weight of the total main monomer prepared in the step (S10) to be described later.

Example One

<Preparation of nitrile-based copolymer>

(1) Main monomer preparation step (S10)

A main monomer consisting of 66 wt% of 1,4-butadiene and 34 wt% of acrylonitrile was prepared.

(2) first polymerization and polymerization termination step (S20)

With respect to 50 parts by weight of the main monomer prepared in step (S10) and 100 parts by weight of the main monomer prepared in step (S10) in the reactor, alkyldiphenyloxide disulfonate (product name: DOWFAX 2A1, manufacturer: DOW) as an emulsifier CHEM) 0.6 parts by weight and a fatty acid compound (product name: oleic acid, palmitic acid and stearic acid mixture, manufacturer: LG Household & Health Care) 0.1 parts by weight, 0.05 parts by weight of p-mentane hydroperoxide as a polymerization initiator, as a third monomer 0.5 parts by weight of allyl methacrylate (AMA), 0.4 parts by weight of α-methylstyrene dimer (AMSD) as a molecular weight regulator, and 200 parts by weight of water were added to perform primary polymerization. Thereafter, when the polymerization conversion rate was 50%, 0.05 parts by weight of N,N-diethyl hydroxylamine as a polymerization terminator was added to terminate the polymerization.

(3) Secondary polymerization and polymerization termination step (S30)

After the product produced after the completion of the primary polymerization is stirred for 30 minutes, 50 parts by weight of the main monomer prepared in the step (S10) and 100 parts by weight of the main monomer prepared in the step (S10) in the reactor, alkyldiol as an emulsifier Phenyloxide disulfonate (product name: DOWFAX 2A1, manufacturer: DOW CHEM) 0.6 parts by weight and fatty acid compound (product name: oleic acid, palmitic acid and stearic acid mixture, manufacturer: LG Household & Health Care) 0.1 parts by weight, as a polymerization initiator 0.1 parts by weight of p-mentane hydroperoxide, 0.5 parts by weight of allyl methacrylate as a third monomer, 0.5 parts by weight of alpha-methylstyrene dimer as a molecular weight regulator, and 200 parts by weight of water were added to perform secondary polymerization. Thereafter, at a polymerization conversion rate of 80%, 0.05 parts by weight of N,N-diethyl hydroxylamine as a polymerization terminator was added to terminate the polymerization to prepare a latex containing a nitrile-based copolymer, and the reaction time was 8.3 hours in total. It took

Calcium chloride aqueous solution is added to the latex so that the latex containing the prepared nitrile-based copolymer and calcium chloride in the calcium chloride aqueous solution have a weight ratio of 100:2, and heated at 65 ° C. to proceed with agglomeration to obtain a nitrile-based copolymer latex aggregate and dried in an oven at 100° C. to prepare a nitrile-based copolymer.

Example 2

In Example 1, the first polymerization and the second polymerization were carried out in the same manner as in Example 1, except that 0.05 parts by weight instead of 0.5 parts by weight of allyl methacrylate was added.

Example 3

In Example 1, the first polymerization and the second polymerization were carried out in the same manner as in Example 1, except that 0.6 parts by weight of allyl methacrylate was added instead of 0.5 parts by weight, respectively.

Example 4

In Example 1, the secondary polymerization was carried out in the same manner as in Example 1, except that 0.08 parts by weight was added instead of 0.5 parts by weight of alpha-methylstyrene dimer.

Example 5

Example 1, except that in Example 1, 0.6 parts by weight was added instead of 0.4 parts by weight of alpha-methylstyrene dimer during the first polymerization, and 0.6 parts by weight was added instead of 0.5 parts by weight of alpha-methylstyrene dimer during the second polymerization It was carried out in the same way as

Example 6

In Example 1, the first polymerization was carried out in the same manner as in Example 1, except that 0.6 parts by weight of alkyldiphenyloxide disulfonate and 1.1 parts by weight of a fatty acid compound were used instead of 0.1 parts by weight of a fatty acid compound as an emulsifier.

Example 7

In Example 1, in the same manner as in Example 1, except that 0.6 parts by weight of alkyldiphenyloxide disulfonate and 1.0 parts by weight of sodium dodecylbenzene sulfonate were used instead of 0.1 parts by weight of a fatty acid compound as an emulsifier during the primary polymerization. carried out.

comparative example One

In Example 1, t-dodecyl mercaptane (Tert-Dodecyl mercaptane) 0.4 instead of 0.4 parts by weight of alpha-methylstyrene dimer during the first polymerization without adding allyl methacrylate during the first polymerization and the second polymerization, respectively A weight part was carried out in the same manner as in Example 1, except that 0.5 parts by weight of t-dodecyl mercaptan was added instead of 0.5 parts by weight of alpha-methylstyrene dimer during secondary polymerization.

comparative example 2

In Example 1, instead of dividing allyl methacrylate, 1 part by weight of allyl methacrylate was batched only during the primary polymerization, and t-dodecyl mercaptan was first polymerized instead of divided by alpha-methylstyrene. It was carried out in the same manner as in Example 1, except that 0.9 parts by weight was batch-injected.

comparative example 3

(1) Main monomer preparation step

A main monomer consisting of 66 wt% of 1,4-butadiene and 34 wt% of acrylonitrile was prepared.

(2) polymerization step

Based on 100 parts by weight of the prepared main monomer and 100 parts by weight of the main monomer prepared above in the reactor, 0.6 parts by weight of alkyldiphenyloxide disulfonate (product name: DOWFAX 2A1, manufacturer: DOW CHEM) as an emulsifier and a fatty acid compound (product name: oleic acid) , palmitic acid and stearic acid mixture, manufacturer: LG Household & Health Care) 0.1 parts by weight, 0.05 parts by weight of p-mentane hydroperoxide as a polymerization initiator, 0.5 parts by weight of allyl methacrylate as a third monomer, alpha- as a molecular weight regulator Polymerization was initiated by adding 0.4 parts by weight of methylstyrene dimer and 200 parts by weight of water. Thereafter, at a polymerization conversion rate of 80%, 0.05 parts by weight of N,N-diethyl hydroxylamine as a polymerization terminator was added to terminate the polymerization, and a latex containing a nitrile-based copolymer was prepared, and the reaction time was 8.2 in total. It took time.

Calcium chloride aqueous solution is added to the latex so that the latex containing the prepared nitrile-based copolymer and calcium chloride in the calcium chloride aqueous solution have a weight ratio of 100:2, and heated at 65 ° C. to proceed with agglomeration to obtain a nitrile-based copolymer latex aggregate and dried in an oven at 100° C. to prepare a nitrile-based copolymer.

comparative example 4

(1) Main monomer preparation step

A main monomer consisting of 66 wt% of 1,4-butadiene and 34 wt% of acrylonitrile was prepared.

(2) polymerization step

With respect to 50 parts by weight of the main monomer prepared in step (S10) and 100 parts by weight of the main monomer prepared in step (S10) in the reactor, alkyldiphenyloxide disulfonate (product name: DOWFAX 2A1, manufacturer: DOW) as an emulsifier CHEM) 0.6 parts by weight and a fatty acid compound (product name: oleic acid, palmitic acid and stearic acid mixture, manufacturer: LG Household & Health Care) 0.1 parts by weight, 0.05 parts by weight of p-mentane hydroperoxide as a polymerization initiator, as a third monomer 1 part by weight of allyl methacrylate, 0.9 parts by weight of alpha-methylstyrene dimer as a molecular weight regulator, and 200 parts by weight of water were added to initiate polymerization, and the polymerization conversion rate was 50% based on the input main monomer, that is, the polymerization conversion rate based on the total main monomer. At the time of 25%, the remainder (50 parts by weight) of the main monomer was added, and when the polymerization conversion rate was 80%, 0.05 parts by weight of N,N-diethyl hydroxylamine as a polymerization terminator was added to terminate the polymerization, and nitrile A latex containing the copolymer was prepared, and the reaction time was 8.3 hours in total.

Calcium chloride aqueous solution is added to the latex so that the latex containing the prepared nitrile-based copolymer and calcium chloride in the calcium chloride aqueous solution have a weight ratio of 100:2, and heated at 65 ° C. to proceed with agglomeration to obtain a nitrile-based copolymer latex aggregate and dried in an oven at 100° C. to prepare a nitrile-based copolymer.

< Experimental example >

Experimental example One

The reaction time required to prepare the latex containing the nitrile-based copolymer from Examples 1 to 7 and Comparative Examples 1 to 4 and the physical properties of the nitrile-based copolymer were measured as follows, and are shown in Table 1 below.

* Polymerization stability: After the final completion of polymerization, the resulting copolymer latex was filtered through a 200 mesh net to visually determine whether or not a coagulated product was present. The presence of coagulation was indicated by O, and the absence of coagulation was indicated by X.

* Particle size: The particle size and distribution of the copolymer were measured using Dynamic Light Scattering (DLS) equipment.

Example comparative example One 2 3 4 5 6 7 One 2 3 4 polymerization time 8.3 8.3 8.3 8.1 8.4 8.3 8.3 7.9 8.1 8.2 8.3 Whether clots are formed X X X X X X X X X O X emulsifier residue 5213 5120 5418 5326 5425 12045 10424 5591 5134 5810 5460 Mineral Residue 0.06 0.08 0.07 0.05 0.06 0.18 0.12 0.08 0.07 0.09 0.06 Particle size (nm/standard deviation (%)) 895/18.1 894/20.3 889/18.9 891/23.5 894/19.8 894/21.2 885/24.0 887/32.1 890/31.3 690/15.5 889/33.5

Referring to Table 1, it can be seen that Examples 1 to 7 according to the present invention did not form a coagulated product, so that the polymerization stability was excellent, and the particles were uniformly formed as the standard deviation of the particle size was small. On the other hand, it can be seen that Example 6 using only a fatty acid compound as an emulsifier and Example 7 using only sodium dodecylbenzene sulfonate have insignificant improvement in the residual amount of the emulsifier and the residual amount of inorganic substances, compared to the other examples.

On the other hand, in Comparative Example 1 in which t-dodecyl mercaptan was dividedly added as a molecular weight control agent without adding allyl methacrylate during the primary polymerization and secondary polymerization, respectively, allyl methacrylate and t-dode only during the primary polymerization In Comparative Example 2, in which the yarn mercaptan was batch-injected, and Comparative Example 4, in which the main monomer was dividedly added without carrying out the polymerization intermediate termination process, the particle size was sufficiently grown due to the divided injection of the main monomer, and thus a coagulated product was not formed. However, it was confirmed that the particles were formed non-uniformly, as the standard deviation was large. In addition, it was confirmed that Comparative Examples 1 and 2 using t-dodecyl mercaptan had a relatively faster reaction rate than Examples 1 to 7.

In addition, in Comparative Example 3, in which the main monomer was batch-injected without designing the polymerization step as two steps, the particle size did not grow large enough to ensure the stability of the latex, so a coagulated product was generated, and it was confirmed that the polymerization stability was lowered through this. could

Experimental example 2

A nitrile-based copolymer composition comprising the nitrile-based copolymer prepared in Examples 1 to 7 and Comparative Examples 1 to 4 as a raw rubber was prepared as shown in Table 2 below, and the processing and mechanical properties thereof were described as follows. It was measured and shown in Table 3 below.

copolymer composition parts by weight Dosage (g) Raw rubber (copolymer) NBR 100 140 vulcanization accelerator zinc oxide 3 4.2 vulcanizing agent brimstone 1.5 2.1 dispersant stearic acid One 1.4 reinforcing filler CB 40 56 vulcanization accelerator TBBS 0.7 0.98

In Table 2, NBS means each of the nitrile-based copolymers prepared in Examples 1 to 7 and Comparative Examples 1 to 4, CB means carbon black (N330??, manufactured by Showa Cabot KK), and TBBS is N -tert-butyl-2-benzothiazolesulfenamide.

*Mooney viscosity (MV(ML1+4 100℃)): The patterned viscosity of the nitrile-based copolymer is measured using a Mooney viscometer (MV2000, Alpha Technology), preheated at 100℃ with a large rotor, and the rotor starts in 1 minute. The value after 4 minutes was measured and read to measure Mooney viscosity.

* Compound Mooney viscosity (C-MV): The pattern viscosity of the nitrile-based copolymer composition is 4 after preheating with a large rotor at 100 °C using a Mooney viscometer (MV2000, Alpha Technology), and starting the rotor in 1 minute. The value after minutes was measured and read to measure Mooney viscosity.

* Delta fringe viscosity (Delta MV): It is the value obtained by subtracting the fringe viscosity from the compound fringe viscosity. In general, the higher the Delta MV, the lower the processability, which means that there are more macromolecules or less material in the low molecular weight region.

* Vulcanization characteristics: ML (minimum torque) and MH (maximum torque) values were measured after vulcanization at 160 ° C. for 45 minutes using a moving die rheometer (MDR) for the nitrile-based copolymer composition, and Ts1 (1% vulcanization) time) and Tc90 (time to vulcanize 90%) were measured.

* Tensile properties: Each test piece according to the tensile test method of ASTM 412 was prepared using a nitrile-based copolymer composition, and the tensile strength (TS, kgf/cm ² ), elongation (%) and 300% at the time of cutting the test piece Tensile stress (300% modulus) at elongation was measured. Specifically, tensile properties were measured at room temperature at a rate of 50 cm/min using a Universal Test Machin 4202 (Instron) tensile tester.

Example comparative example One 2 3 4 5 6 7 One 2 3 4 polymer
Properties MV (ML _{1+ 4} 100℃) 45 46 44 47 43 45 45 46 45 45 46 C-MV 66 67 66 68 65 68 67 67 67 77 68 Delta MV 21 21 22 21 22 23 22 21 22 32 22 vulcanization characteristics MH 33.2 32.1 30.5 31.8 32.3 32.4 31.5 28.96 31.03 29.1 31.3 ML 2.07 2.05 1.95 1.98 2.03 2.01 2.0 1.90 1.92 2.05 2.02 Ts'1(min) 1.63 1.60 1.88 1.65 1.63 1.52 1.62 1.99 1.65 1.2 1.55 Tc'90(min) 5.6 5.4 5.7 5.3 5.5 5.3 5.5 6.9 5.4 5.3 5.6 mechanical
Properties TS(kgf/cm ² ) 270 258 272 263 256 268 269 247 260 256 263 Elongation (%) 514 530 518 470 513 510 513 429 520 523 521 300% modulus 86.2 84.7 86.8 86.3 83.5 86.1 85.9 73.1 84.9 84.7 83.3

Referring to Table 3, according to the preparation method according to the present invention, in the polymerization process designed in two stages by primary and secondary polymerization, it includes the step of terminating after the primary polymerization, and allyl methacrylic in the polymerization of each stage It can be seen that Examples 1 to 7 in which the rate and alpha-methylstyrene dimers were separately added were superior in vulcanization properties and mechanical properties compared to Comparative Examples.

On the other hand, in Comparative Examples 1 to 4, both vulcanization properties and mechanical properties were significantly lowered than in Examples, and it was found that they were inferior to Examples.

Claims (11)

Preparing a main monomer comprising a conjugated diene-based monomer and an ethylenically unsaturated nitrile-based monomer (S10);
A part of the main monomer, allyl (meth)acrylate and α-methylstyrene dimer prepared in step (S10) are put into the reactor for primary polymerization, and the polymerization conversion rate is 35 to 65% at a time point terminating the polymerization by adding a polymerization terminator (S20); and
After the polymerization is completed, the remainder of the main monomer prepared in step (S10), allyl (meth)acrylate and alpha-methylstyrene dimer are added to the reactor for secondary polymerization, and the polymerization conversion rate is 75 to 90% at a time point A method for producing a nitrile-based copolymer comprising the step (S30) of adding a polymerization terminator to terminate polymerization to prepare a latex containing the nitrile-based copolymer. According to claim 1,
The main monomer is a method for producing a nitrile-based copolymer comprising 50 to 90% by weight of a conjugated diene-based monomer and 10 to 50% by weight of an ethylenically unsaturated nitrile-based monomer based on the total content of the main monomer. According to claim 1,
The (S20) step is a method for producing a nitrile-based copolymer that is carried out in the presence of an emulsifier comprising at least one selected from the group consisting of fatty acid compounds and sulfonate-based compounds. 4. The method of claim 3,
The content of the emulsifier is 0.3 parts by weight to 3.5 parts by weight based on 100 parts by weight of the total main monomer. 4. The method of claim 3,
The (S20) step is a method for producing a nitrile-based copolymer is carried out in the presence of an emulsifier comprising a mixture of a fatty acid compound and a sulfonate-based compound. 6. The method of claim 5,
In the emulsifier, the content of the fatty acid compound is 0.01 parts by weight to 0.5 parts by weight based on 100 parts by weight of the total main monomer, and the content of the sulfonate-based compound is 0.4 parts by weight to 1.5 parts by weight based on 100 parts by weight of the total main monomer. Method for producing a nitrile-based copolymer. According to claim 1,
The content of each allyl (meth)acrylate input in the steps (S20) and (S30) is 0.1 to 0.5 parts by weight based on 100 parts by weight of the total main monomer. According to claim 1,
The content of each alpha-methylstyrene dimer input in the steps (S20) and (S30) is 0.1 to 0.5 parts by weight based on 100 parts by weight of the total main monomer. According to claim 1,
In the step (S20), a method for producing a nitrile-based copolymer to terminate the polymerization by adding a polymerization terminator at a time when the polymerization conversion rate is 45% to 55%. According to claim 1,
The content of each polymerization terminator added in the steps (S20) and (S30) is 0.01 to 0.1 parts by weight based on 100 parts by weight of the total main monomer. According to claim 1,
The method for producing a nitrile-based copolymer further comprising the step (S40) of adding a coagulant to the latex after the step (S30) to agglomerate the latex.