KR102817999B1 - Copolymer latex composition, method for preparing the same and rubber composition comprising the same - Google Patents

Abstract

The present invention relates to a copolymer latex composition, comprising: a nitrile copolymer latex; and an acrylic copolymer latex, wherein the nitrile copolymer comprises a repeating unit derived from a conjugated diene monomer and a repeating unit derived from a nitrile monomer, and the acrylic copolymer comprises a first acrylic copolymer and a second acrylic copolymer, wherein the first acrylic copolymer comprises a repeating unit derived from a (meth)acrylic acid alkyl ester monomer and a repeating unit derived from a (meth)acrylic acid alkoxy alkyl ester monomer, and the second acrylic copolymer comprises a repeating unit derived from a (meth)acrylic acid alkyl ester monomer, a repeating unit derived from a (meth)acrylic acid alkoxy alkyl ester monomer, and a repeating unit derived from a crosslinkable monomer. The present invention can provide a copolymer latex composition, a method for preparing the same, and a rubber composition comprising the same.

Description

Copolymer latex composition, method for preparing the same and rubber composition comprising the same {COPOLYMER LATEX COMPOSITION, METHOD FOR PREPARING THE SAME AND RUBBER COMPOSITION COMPRISING THE SAME}

The present invention relates to a copolymer latex composition capable of obtaining a rubber composition having excellent heat resistance and a method for producing the same.

Nitrile rubber has excellent oil resistance, and is most desirable as an O-ring, V-packing oil seal for sealing lubricants, operating oils, fuel oils, etc. in all fields including industrial machinery, construction machinery, power generation equipment, automobiles, and aircraft, and its demand is also very high. A representative example of the nitrile rubber is acrylonitrile-butadiene rubber (NBR).

The usable temperature of the above nitrile rubber varies greatly depending on the nitrile content, but can be used from -50°C to -120°C. For example, those with a low nitrile content are used for low-temperature applications, such as in polar or cold-region equipment and aircraft. In addition, those with a high nitrile content not only have good heat resistance and mechanical properties, but also have excellent gas permeability, so they can be sufficiently used up to about 10 torr for vacuum applications. However, when the nitrile content is high, the nitrile reactivity is excellent, so there is a disadvantage that the structure of the nitrile rubber is not uniform, and it has been difficult to manufacture nitrile rubber with excellent heat resistance.

In this regard, as demand for automobile engines and electric vehicles has increased recently, excellent heat resistance is required, and research is continuing to manufacture nitrile rubber with excellent heat resistance.

KR 2012-0108055 A

The problem to be solved by the present invention is to provide a copolymer latex composition having improved heat resistance as well as oil resistance by mixing an acrylic copolymer latex with a nitrile copolymer latex, a method for producing the same, and a rubber composition comprising the same, in order to solve the problems mentioned in the background technology of the above invention.

In order to solve the above problems, the present invention provides a copolymer latex composition comprising: a nitrile copolymer latex; and an acrylic copolymer latex, wherein the nitrile copolymer comprises a repeating unit derived from a conjugated diene monomer and a repeating unit derived from a nitrile monomer, the acrylic copolymer comprises a first acrylic copolymer and a second acrylic copolymer, wherein the first acrylic copolymer comprises a repeating unit derived from a (meth)acrylic acid alkyl ester monomer and a repeating unit derived from a (meth)acrylic acid alkoxy alkyl ester monomer, and the second acrylic copolymer comprises a repeating unit derived from a (meth)acrylic acid alkyl ester monomer, a repeating unit derived from a (meth)acrylic acid alkoxy alkyl ester monomer, and a repeating unit derived from a crosslinkable monomer.

In addition, the present invention includes a step (S10) of polymerizing a conjugated diene monomer and a nitrile monomer to produce a nitrile copolymer latex; a step (S20) of producing an acrylic copolymer latex; and a step (S30) of mixing the nitrile copolymer latex and the acrylic copolymer latex, wherein step S20 includes a step (S21) of polymerizing a (meth)acrylic acid alkyl ester monomer and a (meth)acrylic acid alkoxy alkyl ester monomer at a temperature of less than 30°C to produce a first acrylic copolymer latex; a step (S22) of polymerizing a (meth)acrylic acid alkyl ester monomer, a (meth)acrylic acid alkoxy alkyl ester monomer, and a crosslinking monomer at a temperature of 30°C or higher to produce a second acrylic copolymer latex; The present invention provides a method for producing a copolymer latex composition, comprising a step (S23) of mixing the first acrylic copolymer latex and the second acrylic copolymer latex.

In addition, the present invention provides a rubber composition comprising the copolymer latex composition.

The present invention produces a copolymer latex composition by mixing a nitrile copolymer latex and an acrylic copolymer latex including a first acrylic copolymer polymerized at low temperature and a second acrylic copolymer polymerized at high temperature, thereby improving processability and obtaining a rubber composition having excellent physical properties such as oil resistance and heat resistance.

The terms or words used in the description and claims of the present invention should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of the present invention, based on the principle that the inventor can appropriately define the concept of the term in order to explain his or her own invention in the best manner.

In the present invention, the term 'derived repeating unit' may indicate a component, structure, or the substance itself derived from a certain substance. As a specific example, the 'derived repeating unit' may mean a repeating unit formed in an acrylic copolymer by a monomer introduced during a polymerization process participating in a polymerization reaction.

In the present invention, the term 'latex' may mean a polymer or copolymer polymerized by polymerization that exists in a form dispersed in water, and as a specific example, it may mean a polymer or copolymer of rubber polymerized by emulsion polymerization in a form dispersed in water in a colloidal state.

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

In the present invention, the term '(meth)acrylic acid' may mean acrylic acid or methacrylic acid.

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

According to the present invention, a copolymer latex composition can be provided, which comprises a nitrile copolymer latex; and an acrylic copolymer latex, wherein the nitrile copolymer comprises a repeating unit derived from a conjugated diene monomer and a repeating unit derived from a nitrile monomer, and the acrylic copolymer comprises a first acrylic copolymer and a second acrylic copolymer, wherein the first acrylic copolymer comprises a repeating unit derived from a (meth)acrylic acid alkyl ester monomer and a repeating unit derived from a (meth)acrylic acid alkoxy alkyl ester monomer, and the second acrylic copolymer comprises a repeating unit derived from a (meth)acrylic acid alkyl ester monomer, a repeating unit derived from a (meth)acrylic acid alkoxy alkyl ester monomer, and a repeating unit derived from a crosslinkable monomer.

According to one embodiment of the present invention, the conjugated diene monomer forming the conjugated diene monomer-derived repeating unit included in the nitrile copolymer may include at least one selected from the group consisting of 1,4-butadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,3-pentadiene, and isoprene, and as a specific example, the conjugated diene monomer may be 1,4-butadiene. In this case, the impact resistance of the rubber manufactured with the rubber composition including the copolymer latex composition according to the present invention is excellent.

The content of the repeating unit derived from the above conjugated diene monomer may be 45 parts by weight to 90 parts by weight, 50 parts by weight to 80 parts by weight, or 55 parts by weight to 75 parts by weight based on 100 parts by weight of the total monomer-derived repeating units constituting the nitrile copolymer. Within this range, the polymerization productivity is excellent, and the impact resistance of the rubber manufactured from the rubber composition including the above copolymer latex composition is excellent.

According to one embodiment of the present invention, the nitrile monomer forming the nitrile monomer-derived repeating unit included in the nitrile copolymer may include, for example, at least one selected from the group consisting of acrylonitrile, methacrylonitrile, α-chloronitrile, and α-cyanoethylacrylonitrile, and as a specific example, the nitrile monomer may be acrylonitrile. In this case, the flexibility, oil resistance, and heat resistance of the rubber manufactured with the rubber composition including the copolymer latex composition according to the present invention are excellent.

The content of the repeating unit derived from the nitrile monomer may be 15 parts by weight to 50 parts by weight, 20 parts by weight to 45 parts by weight, or 25 parts by weight to 45 parts by weight, based on 100 parts by weight of the total monomer-derived repeating units constituting the nitrile copolymer. Within this range, the polymerization productivity is excellent, and the flexibility and oil resistance of the rubber manufactured from the rubber composition including the copolymer latex composition are excellent.

According to one embodiment of the present invention, the acrylic copolymer latex may include a first acrylic copolymer and a second acrylic copolymer.

According to one embodiment of the present invention, the first acrylic copolymer may include a repeating unit derived from a (meth)acrylic acid alkyl ester monomer and a repeating unit derived from a (meth)acrylic acid alkoxy alkyl ester monomer.

According to one embodiment of the present invention, the (meth)acrylic acid alkyl ester monomer forming the repeating unit derived from the (meth)acrylic acid alkyl ester monomer contained in the first acrylic copolymer forms a main chain of the first acrylic copolymer and may be a (meth)acrylic acid alkyl ester monomer containing a linear or cyclic alkyl group having 1 to 8 carbon atoms. Here, the alkyl group contained in the (meth)acrylic acid alkyl ester monomer may be unsubstituted or substituted with a hydroxyl group (OH).

For example, the (meth)acrylic acid alkyl ester monomer contained in the first acrylic copolymer may include at least one selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-amyl (meth)acrylate, isoamyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, hydroxy methyl (meth)acrylate, hydroxy ethyl (meth)acrylate, and hydroxy propyl (meth)acrylate. As a specific example, the (meth)acrylic acid alkyl ester monomer included in the first acrylic copolymer may be a combination of ethyl (meth)acrylate, butyl (meth)acrylate, and hydroxypropyl (meth)acrylate.

The repeating unit derived from the (meth)acrylic acid alkyl ester monomer contained in the first acrylic copolymer serves to increase the low-temperature flexibility, oil resistance, heat resistance, etc. of the rubber composition. The content of the repeating unit derived from the (meth)acrylic acid alkyl ester monomer may be 80 parts by weight to 95 parts by weight, 80 parts by weight to 90 parts by weight, or 85 parts by weight to 87 parts by weight, based on 100 parts by weight of the total monomer-derived repeating units forming the first acrylic copolymer. When the content of the repeating unit derived from the (meth)acrylic acid alkyl ester monomer is within the above range, the elasticity of the first acrylic copolymer is improved, and the crosslinking density increases, thereby improving the heat resistance.

According to one embodiment of the present invention, the repeating unit derived from a (meth)acrylic acid alkoxy alkyl ester monomer included in the first acrylic copolymer forms a main chain of the first acrylic copolymer and may be a (meth)acrylic acid alkoxy alkyl ester monomer containing an alkoxy alkyl group having 1 to 8 carbon atoms.

For example, the (meth)acrylic acid alkoxy alkyl ester monomer may include at least one selected from the group consisting of methoxymethyl (meth)acrylate, ethoxymethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-propoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, and 4-methoxybutyl (meth)acrylate. As a specific example, the (meth)acrylic acid alkoxy alkyl ester monomer included in the first acrylic copolymer may be 2-methoxyethyl (meth)acrylate.

The repeating unit derived from the (meth)acrylic acid alkoxy alkyl ester monomer contained in the first acrylic copolymer serves to increase the low-temperature flexibility, oil resistance, heat resistance, etc. of the rubber composition. The content of the repeating unit derived from the (meth)acrylic acid alkoxy alkyl ester monomer may be 5 parts by weight to 20 parts by weight, 10 parts by weight to 17 parts by weight, or 13 parts by weight to 15 parts by weight, based on 100 parts by weight of the total monomer-derived repeating units forming the first acrylic copolymer. When the content of the (meth)acrylic acid alkoxy alkyl ester monomer-derived repeating unit is within the above range, the elasticity of the first acrylic copolymer is improved, and the crosslinking density increases, thereby improving heat resistance.

The weight average molecular weight of the first acrylic copolymer may be 150,000 g/mol to 1,100,000 g/mol, 200,000 g/mol to 1,000,000 g/mol, or 250,000 g/mol to 900,000 g/mol. When the weight average molecular weight of the first acrylic copolymer is within the above range, the processability of the copolymer latex composition as well as the heat resistance and mechanical properties of the rubber composition can be improved.

According to one embodiment of the present invention, the second acrylic copolymer may include a repeating unit derived from a (meth)acrylic acid alkyl ester monomer, a repeating unit derived from a (meth)acrylic acid alkoxy alkyl ester monomer, and a repeating unit derived from a crosslinkable monomer.

According to one embodiment of the present invention, the type of the (meth)acrylic acid alkyl ester monomer for forming the repeating unit derived from the (meth)acrylic acid alkyl ester monomer included in the second acrylic copolymer may be the same as the description of the type of the (meth)acrylic acid alkyl ester monomer included in the first acrylic copolymer. As a specific example, the (meth)acrylic acid alkyl ester monomer included in the second acrylic copolymer may be a combination of ethyl (meth)acrylate and butyl (meth)acrylate.

The repeating unit derived from the (meth)acrylic acid alkyl ester monomer contained in the second acrylic copolymer serves to increase the low-temperature flexibility, oil resistance, heat resistance, etc. of the rubber composition. The content of the repeating unit derived from the (meth)acrylic acid alkyl ester monomer may be 75 parts by weight to 95 parts by weight, 80 parts by weight to 90 parts by weight, or 82 parts by weight to 85 parts by weight, based on 100 parts by weight of the total monomer-derived repeating units forming the second acrylic copolymer. When the content of the repeating unit derived from the (meth)acrylic acid alkyl ester monomer is within the above range, the elasticity of the second acrylic copolymer is improved, and the crosslinking density is increased, thereby improving the heat resistance.

According to one embodiment of the present invention, the type of the (meth)acrylic acid alkoxy alkyl ester monomer for forming the repeating unit derived from the (meth)acrylic acid alkoxy alkyl ester monomer included in the second acrylic copolymer may be the same as the description of the type of the (meth)acrylic acid alkoxy alkyl ester monomer included in the first acrylic copolymer.

The repeating unit derived from the (meth)acrylic acid alkoxy alkyl ester monomer contained in the second acrylic copolymer serves to increase the low-temperature flexibility, oil resistance, heat resistance, etc. of the rubber composition. The content of the repeating unit derived from the (meth)acrylic acid alkoxy alkyl ester monomer may be 4 parts by weight to 20 parts by weight, 8 parts by weight to 17 parts by weight, or 12 parts by weight to 15 parts by weight, based on 100 parts by weight of the total monomer-derived repeating units forming the second acrylic copolymer. When the content of the (meth)acrylic acid alkoxy alkyl ester monomer-derived repeating unit is within the above range, the elasticity of the second acrylic copolymer is improved, and the crosslinking density increases, thereby improving heat resistance.

According to one embodiment of the present invention, the crosslinking monomer for forming the repeating unit derived from the crosslinking monomer included in the second acrylic copolymer is for providing a crosslinking functional group during the production of the second acrylic copolymer, and may include at least one selected from the group consisting of an epoxy group-containing monomer and a halogen-containing monomer.

The above epoxy group-containing monomer may include at least one selected from the group consisting of glycidyl (meth)acrylate, vinyl glycidyl ether, allyl glycidyl ether, and methacryl glycidyl ether.

The above halogen-containing monomer may include at least one selected from the group consisting of vinyl chloro acetate, vinyl bromo acetate, allyl chloro acetate, vinyl chloro propionate, vinyl chloro butylate, vinyl bromo butylate, 2-chloro ethyl acrylate, 3-chloro propyl acrylate, 4-chloro butyl acrylate, 2-chloro ethyl methacrylate, 2-bromo ethyl acrylate, 2-iodo ethyl acrylate, 2-chloro ethyl vinyl ether, chloro methyl vinyl ether, 4-chloro-2-butenyl acrylate, vinyl benzyl chloride, 5-chloro methyl-2-norbornene, and 5-chloro acetoxy methyl-2-norbornene. Specifically, the halogen-containing monomer may be vinyl chloro acetate.

The crosslinking monomer-derived repeating unit included in the second acrylic copolymer serves to increase the crosslinking property and heat resistance of the rubber composition. The content of the crosslinking monomer-derived repeating unit may be 1 to 10 parts by weight, 2 to 8 parts by weight, or 3 to 5 parts by weight, based on 100 parts by weight of the total monomer-derived repeating unit forming the second acrylic copolymer. When the content of the crosslinking monomer-derived repeating unit is within the above range, the crosslinking speed can be improved during the production of the second acrylic copolymer, thereby increasing the crosslinking density.

The weight average molecular weight of the second acrylic copolymer may be 50,000 g/mol to 900,000 g/mol, 100,000 g/mol to 800,000 g/mol, or 150,000 g/mol to 700,000 g/mol. When the weight average molecular weight of the second acrylic copolymer is within the above range, the processability of the copolymer latex composition as well as the heat resistance and mechanical properties of the rubber composition can be improved.

According to one embodiment of the present invention, the acrylic copolymer may include the first acrylic copolymer and the second acrylic copolymer in a weight ratio of 2:8 to 8:2, 3:7 to 7:3, or 5:5. The acrylic copolymer including the first acrylic copolymer and the second acrylic copolymer within the above range can form a rubber having excellent heat resistance and mechanical properties while improving the processability of the copolymer latex composition.

In addition, according to one embodiment of the present invention, the pattern viscosity (ML ₁₊₄ , 100° C.) of the acrylic copolymer latex in which the first acrylic copolymer and the second acrylic copolymer are mixed may be 20 to 80, 25 to 60, or 30 to 50. When the pattern viscosity of the acrylic copolymer latex is within the above range, a copolymer latex composition having excellent processability can be obtained.

According to one embodiment of the present invention, the copolymer latex composition may contain nitrile-based copolymer latex and acrylic-based copolymer latex in a weight ratio of 9:1 to 4:6, 8:2 to 5:5, or 7:3 to 5:5 based on solid content. The copolymer latex composition contains nitrile-based copolymer latex and acrylic-based copolymer latex in the above ranges, thereby exhibiting an excellent balance of oil resistance and heat resistance due to an appropriate copolymer composition.

According to the present invention, a method for producing the above-described copolymer latex composition is provided. For example, the method for producing the copolymer latex composition includes a step (S10) of polymerizing a conjugated diene monomer and a nitrile monomer to produce a nitrile copolymer latex; a step (S20) of producing an acrylic copolymer latex; and a step (S30) of mixing the nitrile copolymer latex and the acrylic copolymer latex, wherein step S20 includes a step (S21) of polymerizing a (meth)acrylic acid alkyl ester monomer and a (meth)acrylic acid alkoxy alkyl ester monomer at a temperature of less than 30° C. to produce a first acrylic copolymer latex; a step (S22) of polymerizing a (meth)acrylic acid alkyl ester monomer, a (meth)acrylic acid alkoxy alkyl ester monomer, and a crosslinking monomer at a temperature of 30° C. or higher to produce a second acrylic copolymer latex; And it may include a step (S23) of mixing the first acrylic copolymer latex and the second acrylic copolymer latex.

According to one embodiment of the present invention, the step S10 is a step for producing a nitrile-based copolymer latex included in the copolymer latex composition, and the description and content of the conjugated diene-based monomer and the nitrile-based monomer included in the nitrile-based copolymer may be the same as described above.

According to one embodiment of the present invention, the step S20 is a step for producing an acrylic copolymer latex included in the copolymer latex composition, and the description and content of the monomer included in the acrylic copolymer may be the same as described above.

The above acrylic copolymer latex can be manufactured through steps S21 to S23.

Specifically, the step S21 is a step for producing a first acrylic copolymer included in the acrylic copolymer latex, wherein the first acrylic copolymer can be produced by polymerizing a (meth)acrylic acid alkyl ester monomer and a (meth)acrylic acid alkoxy alkyl ester monomer at a temperature of less than 30° C.

In addition, the step S22 is a step for producing a second acrylic copolymer included in the acrylic copolymer latex, which can be produced by polymerizing a (meth)acrylic acid alkyl ester monomer, a (meth)acrylic acid alkoxy alkyl ester monomer, and a crosslinking monomer at a temperature of 30° C. or higher.

In addition, the step S23 may be a step of producing an acrylic copolymer latex by mixing the first acrylic copolymer latex produced in S21 and the second acrylic copolymer latex produced in S22.

When the above first acrylic copolymer is polymerized at a high temperature (i.e., 30°C or higher), there is a problem that it is difficult to manufacture the first acrylic copolymer having a uniform structure due to rapid bonding between monomers in the early stage of the reaction because the initial polymerization reaction rate is fast. In addition, when the above second acrylic copolymer is polymerized at a low temperature (i.e., less than 30°C), there is a problem that it is difficult to manufacture the second acrylic copolymer having a uniform structure because the crosslinkable monomers are non-uniformly bonded in the latter half of the polymerization conversion.

However, since the step (S20) of manufacturing the acrylic copolymer latex according to the present invention manufactures the first acrylic copolymer at a relatively low polymerization temperature (i.e., less than 30°C), it is possible to manufacture a high-viscosity first acrylic copolymer latex having a uniform structure, and since the second acrylic copolymer is manufactured at a relatively high polymerization temperature (i.e., 30°C or higher), it is possible to manufacture a low-viscosity second acrylic copolymer latex having a uniform structure.

When a high-viscosity first acrylic copolymer latex having a uniform structure is mixed with a low-viscosity second acrylic copolymer latex having a uniform structure, the low-viscosity second acrylic copolymer latex can be uniformly distributed around the high-viscosity first acrylic copolymer latex, thereby obtaining an acrylic copolymer latex having a patterned viscosity range that allows uniform mixing (or dispersion) and improves the processability of the copolymer latex composition. In addition, by manufacturing a rubber composition with the copolymer latex composition of the present invention including the acrylic copolymer latex, a rubber composition having excellent oil resistance, heat resistance, and mechanical properties can be obtained.

According to one embodiment of the present invention, the polymerization temperature in the step S21 may be less than 30° C., 5° C. to 15° C., or 8° C. to 12° C. By performing polymerization at a polymerization temperature within the above range, a first acrylic copolymer having a uniform structure can be manufactured, thereby improving the processability of the acrylic copolymer latex.

In addition, according to one embodiment of the present invention, the polymerization temperature in step S22 may be 30° C. or higher, 30° C. to 50° C., or 35° C. to 45° C. By performing polymerization at a polymerization temperature within the above range, a second acrylic copolymer having a uniform structure can be manufactured, thereby improving the processability of the acrylic copolymer latex.

The above steps S21 and S22 can be performed separately or simultaneously. That is, the above step S22 can be performed after the above step S21, the above step S22 can be performed after the above step S21, or the above steps S21 and S22 can be performed simultaneously.

In the above step S23, the mixing ratio of the first acrylic copolymer latex and the second acrylic copolymer latex may be a weight ratio of 2:8 to 8:2, a weight ratio of 3:7 to 7:3, or a weight ratio of 5:5. By mixing the first acrylic copolymer latex and the second acrylic copolymer latex within the above range, it is possible to manufacture a copolymer latex composition capable of forming a rubber composition having excellent heat resistance and mechanical properties while improving the processability of the copolymer latex composition.

Meanwhile, since the first acrylic copolymer latex and the second acrylic copolymer latex are in a latex state, they are easy to mix, and an acrylic copolymer latex that is uniformly mixed (or dispersed) can be obtained.

Meanwhile, according to one embodiment of the present invention, the pattern viscosity of the first acrylic copolymer latex manufactured in step S21 may be greater than the pattern viscosity of the second acrylic copolymer latex manufactured in step S22. Since the pattern viscosity of the first acrylic copolymer latex is greater than the pattern viscosity of the second acrylic copolymer latex, mixing between the first acrylic copolymer latex and the second acrylic copolymer latex is uniformly achieved, so that an acrylic copolymer latex having excellent processability can be obtained.

According to one embodiment of the present invention, the step S30 may be a step of producing a copolymer latex composition according to the present invention by mixing the nitrile copolymer latex produced in the step S10 and the acrylic copolymer latex produced in the step S20.

In the above step S30, the nitrile copolymer latex and the acrylic copolymer may be included in a weight ratio of 9:1 to 4:6, 8:2 to 5:5, or 7:3 to 5:5. By mixing the nitrile copolymer latex and the acrylic copolymer latex in the above range, the copolymer latex composition can produce a copolymer latex composition having excellent balance of oil resistance and heat resistance due to an appropriate copolymerization composition.

Polymerization at each step for producing the above copolymer latex composition can be carried out by a method such as emulsion polymerization, bulk polymerization, suspension polymerization, or solution polymerization. Specifically, the polymerization can be carried out by an emulsion polymerization method in a state where additives such as a polymerization initiator, an emulsifier, a polymerization terminator, an ion exchange water, a molecular weight regulator, an activator, and a redox catalyst are added.

Examples of the polymerization initiator include inorganic peroxides such as sodium persulfate, potassium persulfate, ammonium persulfate, potassium perphosphate, and hydrogen peroxide; organic peroxides such as diisopropylbenzene hydroperoxide, t-butyl hydroperoxide, cumene hydroperoxide, p-methane hydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, acetyl peroxide, isobutyl peroxide, octanoyl peroxide, benzoyl peroxide, 3,5,5-trimethylhexanol peroxide, and t-butyl peroxy isobutyrate; Alternatively, nitrogen compounds such as azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, and azobisisobutyric acid (methyl butyrate) may be used alone or in combination of two or more.

Here, when the organic peroxide or the inorganic peroxide is used as a polymerization initiator, it can be used in combination with a reducing agent. As the reducing agent, a compound containing a metal ion in a reduced state, such as ferrous sulfate or cuprous naphthenate; a sulfonic acid compound, such as sodium methanesulfonate; or an amine compound, such as dimethylaniline, can be used alone or in combination of two or more.

The polymerization terminator may include aromatic hydroxy dithiocarboxylic acids such as hydroxyl amine, hydroxy amine sulfate, diethyl hydroxy amine, hydroxy amine sulfonic acid and alkali metal ions thereof, sodium dimethyl dithio carbamate, hydroquinone derivatives, hydroxy diethyl benzene dithiocarboxylic acid, and hydroxy dibutyl benzene dithiocarboxylic acid.

Water can be used as the above ion exchange water.

The above emulsifiers include nonionic emulsifiers such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenol ether, polyoxyethylene alkyl ester, and polyoxyethylene sorbitan alkyl ester; anionic emulsifiers such as salts of fatty acids such as myristic acid, palmitic acid, oleic acid, rosin acid, linolenic acid, and stearic acid, alkyl benzene sulfonates such as sodium dodecyl benzene sulfonate, higher alcohol sulfate ester salts, and alkyl sulfosuccinate; cationic emulsifiers such as alkyl trimethyl ammonium chloride, dialkyl ammonium chloride, and benzyl ammonium chloride; or copolymerizable emulsifiers such as sulfo esters of α,β-unsaturated carboxylic acids, sulfate esters of α,β-unsaturated carboxylic acids, and sulfo alkyl aryl ethers, which can be used singly or in combination of two or more.

As the above molecular weight regulator, mercaptans such as a-methylstyrene dimer, t-dodecyl mercaptan, n-dodecyl mercaptan, and octyl mercaptan; halogenated hydrocarbons such as carbon tetrachloride, methylene chloride, and methylene bromide; or sulfur-containing compounds such as tetraethyl diuram disulfide, dipentamethylene diuram disulfide, and diisopropylxanthogen disulfide can be used.

The above activator may be sodium hydrosulfite, sodium formaldehyde sulfoxylate, sodium ethylenediamine tetraacetate, ferrous sulfate, lactose, dextrose, sodium linolenate, or sodium sulfate, either singly or in combination of two or more.

As the above redox catalyst, sodium formaldehyde sulfoxylate, ferrous sulfate, disodium ethylenediaminetetraacetate, or dibasic cupric sulfate can be used alone or in combination of two or more.

According to the present invention, a rubber composition comprising the above-described copolymer latex composition is provided. Specifically, it can be obtained by adding and mixing one or more additives into the above-described copolymer latex composition, followed by a process of heating and crosslinking.

The above additive may be at least one selected from the group consisting of reinforcing agents, anti-aging agents, light stabilizers, plasticizers, lubricants, adhesives, flame retardants, anti-fungal agents, antistatic agents, and colorants.

The above mixing can be accomplished by methods such as roll mixing, Van Barry mixing, screw mixing, or solution mixing.

The acrylic rubber composition according to the present invention can be made to have a desired shape through a molding or extrusion process after crosslinking is completed, or can be used to manufacture a product by curing simultaneously with or subsequent to crosslinking.

The above items include rubber for engine mounts, transmission seals, crankshaft seals, etc.

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 will be apparent to those skilled in the art that various changes and modifications can be made within the scope and technical idea of the present invention, and the scope of the present invention is not limited to these examples alone.

Example

Example 1

1. Manufacturing of nitrile copolymer latex

In a reaction vessel, 100 parts by weight of a monomer mixture consisting of 65 wt% of 1,4-butadiene and 35 wt% of acrylonitrile, 2.5 parts by weight of oleic acid, 0.05 parts by weight of p-methane hydroperoxide, 0.5 parts by weight of t-dodecyl mercaptan, and 200 parts by weight of water were mixed to initiate emulsion polymerization at 10°C. Then, when the polymerization conversion reached 80%, the polymerization was stopped, and a coagulation process was performed to produce a nitrile-based copolymer latex.

2. Manufacturing of acrylic copolymer latex

(1) Manufacturing of first acrylic copolymer latex

A monomer mixture was obtained by mixing 33 wt% of butyl acrylate, 49 wt% of ethyl acrylate, 3.5 wt% of 2-hydroxypropyl methacrylate, and 14.5 wt% of 2-methoxy ethyl acrylate. The obtained monomer mixture was introduced into a polymerization reactor, and 300 parts by weight of ion-exchanged water, 2.5 parts by weight of sodium lauryl sulfate, and 0.05 parts by weight of p-methane hydroperoxide were added based on 100 parts by weight of the monomer mixture, and then polymerization was initiated at a temperature of 10°C. Then, when the polymerization conversion reached 90%, the polymerization was stopped, and a coagulation process was performed to obtain a first acrylic copolymer latex.

(2) Manufacturing of second acrylic copolymer latex

A monomer mixture was obtained by mixing 32 wt% of butyl acrylate, 50 wt% of ethyl acrylate, 14.5 wt% of 2-methoxy ethyl acrylate, and 3.5 wt% of vinyl chloro acetate. The obtained monomer mixture was introduced into a polymerization reactor, and 412 wt% of ion-exchanged water, 3 wt% of sodium lauryl sulfate, and 0.02 wt% of cumene hydroperoxide were added per 100 wt% of the monomer mixture, and then polymerization was initiated at a temperature of 30°C. When the polymerization conversion reached 90%, the polymerization was stopped, and then a coagulation process was performed to obtain a second acrylic copolymer latex.

(3) Manufacturing of acrylic copolymer latex

The first acrylic copolymer latex and the second acrylic copolymer latex manufactured above were placed in a mixer at a weight ratio of 5:5 (based on solid content) and stirred at 300 rpm at 55°C for 30 minutes to manufacture an acrylic copolymer latex.

3. Preparation of copolymer latex composition

The nitrile copolymer latex and the acrylic copolymer latex prepared above were placed in a mixer at a weight ratio of 7:3 (based on solid content) and stirred at 300 rpm at 55°C for 30 minutes to prepare a copolymer latex composition.

4. Preparation of rubber composition

For 100 parts by weight of the copolymer latex composition manufactured above, 3.0 parts by weight of ZnO, 1.0 parts by weight of stearic acid, 2.0 parts by weight of antioxidant, 0.3 parts by weight of sulfur, and 2.0 parts by weight of accelerator (tetramethyl thiuram disulfide, TMTD) were added and mixed at 50°C for 8 minutes, followed by a roll mill process to manufacture a rubber composition.

Example 2

In the above Example 1, in the step of preparing the copolymer latex composition, the same method as Example 1 was performed, except that the mixing ratio of the nitrile copolymer latex and the acrylic copolymer latex was mixed at a weight ratio of 6:4 instead of 7:3.

Example 3

In the above Example 1, in the step of preparing the copolymer latex composition, the same method as Example 1 was performed, except that the mixing ratio of the nitrile copolymer latex and the acrylic copolymer latex was mixed at a weight ratio of 5:5 instead of 7:3.

Example 4

In the above Example 1, in the step of preparing the copolymer latex composition, the same method as Example 1 was performed, except that the mixing ratio of the nitrile copolymer latex and the acrylic copolymer latex was mixed at a weight ratio of 9:1 instead of 7:3.

Example 5

In the above Example 1, in the step of preparing the copolymer latex composition, the same method as Example 1 was performed, except that the mixing ratio of the nitrile copolymer latex and the acrylic copolymer latex was mixed at a weight ratio of 4:6 instead of 7:3.

Example 6

In the above Example 1, the same process as in the above Example 1 was performed, except that the polymerization temperature was set to 5°C when producing the first acrylic copolymer latex, and that the polymerization temperature was set to 50°C when producing the second acrylic copolymer latex.

Example 7

In the above Example 1, the same process as in the above Example 1 was performed, except that the first acrylic copolymer and the second acrylic copolymer were mixed in a weight ratio of 4:6 when preparing the acrylic copolymer composition.

Example 8

In the above Example 1, the same process as in the above Example 1 was performed, except that the first acrylic copolymer and the second acrylic copolymer were mixed in a weight ratio of 2:8 when producing the acrylic copolymer latex.

Example 9

In the above Example 1, the same process as in the above Example 1 was performed, except that the first acrylic copolymer and the second acrylic copolymer were mixed in a weight ratio of 8:2 when producing the acrylic copolymer latex.

Comparative example

Comparative Example 1

In the above Example 1, the same process as Example 1 was performed except that the second acrylic copolymer was used alone instead of the first acrylic copolymer when producing the acrylic copolymer latex.

Comparative Example 2

The same process as Example 1 was performed, except that the first acrylic copolymer was used alone without using the second acrylic copolymer when producing the acrylic copolymer latex.

Comparative Example 3

In the above Example 1, the same process as in the above Example 1 was performed, except that the polymerization temperature was set to 30°C when producing the first acrylic copolymer latex, and that the polymerization temperature was set to 10°C when producing the second acrylic copolymer latex.

Experimental example

Experimental Example 1

The properties of the copolymer latex composition and rubber composition manufactured in the above examples and comparative examples were evaluated by the following methods, and the results are shown in Tables 1 and 2 below.

1. Curing characteristics: For the rubber compositions manufactured in each of the above examples and comparative examples, the MH (maximum torque) value was measured after curing at 160°C for 45 minutes using a moving die rheometer (MDR), and Ts1 (time required to cure 1%) and Tc90 (time to cure 90%) were measured.

2. Hardness (HS): Measured using an automatic hardness tester (BAREISS) according to ASTM D 2240.

3. Tensile strength (TS, kgf/ ^cm2 ): Each test piece was manufactured according to ASTM D 412, and the tensile strength at the time of fracture of the test piece was measured. At this time, the tensile tester was Universal Test Machin 4204 (Instron), and the measurement was performed at a speed of 50 cm/min. In addition, the tensile stress at 50% elongation (50% modulus, M50) was measured.

4. Elongation (EB, %): The elongation at which the test piece breaks in the above tensile strength evaluation was measured.

5. Heat resistance: The tensile strength of the above tensile strength test specimen was measured before and after aging in an oven at 100°C for 72 hours, and the change rate was compared.

6. Tensile strength: The tensile strength of the above tensile strength test specimens was measured before and after aging in an oven at 120°C for 72 hours by immersing them in IRM#903, and the change rate was compared.

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Characteristics of the vulgaris
(160℃, 45 min) MH 22.2 21.1 19.51 23.6 18.9 23.1 22.8 19.1 17.6 Ts1 1.28 1.31 1.36 1.41 1.5 1.20 1.17 0.98 1.34 Tc90 21.98 18.9 15.64 12.9 17.4 20.8 19.8 17.9 19.6 Mechanical properties (160℃, 30 min) HS 70 69 69 68 66 71 71 68 65 TS 178 164 147 220 140 185 190 153 140 EB 239 220 204 390 220 244 240 170 204 M50 26 27 28 39 22 27 28 30 28 Heat resistance
(100℃, 72 min) HS 71 70 70 71 69 72 72 70 68 TS 171 158 144 213 132 174 182 144 135 EB 230 212 201 351 205 234 228 160 194 △HS 1 1 1 3 3 1 1 2 3 △TS 4 3.5 3.1 5 6 5 4 6 4 △EB 4 3.4 3.0 10 7 4 5 6 5 Oil resistance
(120℃, 72 min, IRM903) △V 11.5 12.1 12.9 12.0 13.0 11.0 11.9 12.0 11.0

Comparative Example 1 Comparative Example 2 Comparative Example 3 Characteristics of the vulgaris
(160℃, 45 min) MH 18.7 16.8 18.1 Ts1 1.02 1.4 1.7 Tc90 16.8 20.7 23.8 Mechanical properties (160℃, 30 min) HS 67 65 66 TS 150 137 140 EB 184 201 180 M50 31 24 26 Heat resistance
(100℃, 72 min) HS 70 72 73 TS 138 126 130 EB 152 154 144 △HS 3 6 7 △TS 8.3 8 7 △EB 27.3 23.4 20 Oil resistance
(120℃, 72 min, IRM903) △V 14 20 19

Referring to Tables 1 and 2 above, as a result of measuring the physical properties of a copolymer latex composition including an acrylic copolymer latex including a nitrile copolymer latex and a first acrylic copolymer polymerized at low temperature and a second acrylic copolymer polymerized at high temperature, and a rubber composition including the copolymer latex composition, it was confirmed that the vulcanization characteristics, mechanical properties, heat resistance, and oil resistance were excellent.

Specifically, depending on the weight ratio of the nitrile copolymer latex and the acrylic copolymer latex, the physical properties vary, and when the weight ratio is 9:1 to 4:6, the curing characteristics, mechanical properties, heat resistance, and oil resistance are excellent. At this time, when the weight ratio of the nitrile copolymer latex and the acrylic copolymer latex is 7:3 to 5:5, the overall physical properties are excellent, and in particular, the physical properties for oil resistance and heat resistance are excellent.

In addition, when manufacturing acrylic copolymer latex, the physical properties vary depending on the weight ratio of the first acrylic copolymer to the second acrylic copolymer, and when it is 2:8 to 8:2, it can be seen that the curing characteristics, mechanical properties, heat resistance, and oil resistance are excellent. Specifically, when the weight ratio of the first acrylic copolymer to the second acrylic copolymer is 3:7 to 7:3, it can be seen that the overall physical properties are better, and in particular, it can be seen that the physical properties for oil resistance and heat resistance are the best.

In comparison, in the case of Comparative Example 1, where the second acrylic copolymer was used alone without including the first acrylic copolymer in the production of the acrylic copolymer composition in the copolymer latex composition, it was confirmed that the physical properties for heat resistance were deteriorated due to reduced processability caused by the polymer.

In addition, in the case of Comparative Example 2, in which the first acrylic copolymer was used alone without including the second acrylic copolymer in the production of the acrylic copolymer composition in the copolymer latex composition, it was confirmed that the physical properties of the vulcanization density, tensile strength, heat resistance, and oil resistance were deteriorated due to a decrease in crosslinking density.

In addition, in the case of Comparative Example 3, in which the first acrylic copolymer was polymerized at high temperature and the second acrylic copolymer was polymerized at low temperature during the production of the acrylic copolymer composition in the copolymer latex composition, it was confirmed that the physical properties for heat resistance were deteriorated due to the decrease in polymer production and crosslinking density.

Claims (13)

Includes nitrile copolymer latex; and acrylic copolymer latex,
The above nitrile copolymer comprises a repeating unit derived from a conjugated diene monomer and a repeating unit derived from a nitrile monomer,
The above acrylic copolymer comprises a first acrylic copolymer and a second acrylic copolymer,
The above first acrylic copolymer comprises a repeating unit derived from a (meth)acrylic acid alkyl ester monomer and a repeating unit derived from a (meth)acrylic acid alkoxy alkyl ester monomer,
The above second acrylic copolymer comprises a repeating unit derived from a (meth)acrylic acid alkyl ester monomer, a repeating unit derived from a (meth)acrylic acid alkoxy alkyl ester monomer, and a repeating unit derived from a crosslinkable monomer.
The weight ratio (based on solid content) of the above nitrile copolymer latex and acrylic copolymer latex is 7:3 to 5:5,
A copolymer latex composition having a patterned viscosity (ML ₁₊₄ , 100°C) of the acrylic copolymer latex of 20 to 80. delete delete In the first paragraph,
The above acrylic copolymer latex is a copolymer latex composition comprising a first acrylic copolymer and a second acrylic copolymer in a weight ratio (based on solid content) of 2:8 to 8:2. In the first paragraph,
The above acrylic copolymer latex is a copolymer latex composition comprising a first acrylic copolymer and a second acrylic copolymer in a weight ratio (based on solid content) of 3:7 to 7:3. delete In the first paragraph,
A copolymer latex composition wherein the weight average molecular weight of the first acrylic copolymer is 150,000 g/mol to 1,100,000 g/mol. In the first paragraph,
A copolymer latex composition wherein the weight average molecular weight of the second acrylic copolymer is 50,000 g/mol to 900,000 g/mol. A step (S10) of manufacturing a nitrile copolymer latex by polymerizing a conjugated diene monomer and a nitrile monomer;
Step (S20) of manufacturing an acrylic copolymer latex; and
It includes a step (S30) of mixing the above nitrile copolymer latex and the above acrylic copolymer latex,
The above step S20 is a step (S21) of manufacturing a first acrylic copolymer latex by polymerizing a (meth)acrylic acid alkyl ester monomer and a (meth)acrylic acid alkoxy alkyl ester monomer at a temperature of less than 30°C;
Step (S22) of producing a second acrylic copolymer latex by polymerizing a (meth)acrylic acid alkyl ester monomer, a (meth)acrylic acid alkoxy alkyl ester monomer, and a crosslinking monomer at a temperature of 30° C. or higher; and
A method for producing a copolymer latex composition, comprising a step (S23) of mixing the first acrylic copolymer latex and the second acrylic copolymer latex. In Article 9,
A method for producing a copolymer latex composition having a polymerization temperature of 5° C. to 15° C. in the above step S21. In Article 9,
A method for producing a copolymer latex composition having a polymerization temperature of 30° C. to 50° C. in the above step S22. In Article 9,
A method for producing a copolymer latex composition, wherein the patterned viscosity of the first acrylic copolymer latex is greater than the patterned viscosity of the second acrylic copolymer latex. A rubber composition comprising a copolymer latex composition according to claim 1.