JP2024125922A - Modifier for thermoplastic polyester resin and thermoplastic polyester resin composition - Google Patents

Abstract

[Problem] To provide a modifier made of polymer particles that can improve the impact strength of a molded article of a thermoplastic polyester resin by blending with the thermoplastic polyester resin. [Solution] The modifier for a thermoplastic polyester resin is made of polymer particles, and the polymer particles include a first core layer, a second core layer, a first shell layer, and a second shell layer having a specific configuration. [Selected Figures] None

Description

The present invention relates to a modifier for thermoplastic polyester resins and a thermoplastic polyester resin composition.

A conventional technique for improving the impact resistance of thermoplastic resins is to blend core-shell polymer particles, which have a rubber core covered with a shell, into the thermoplastic resin.

When the thermoplastic resin is a polyester resin, the polyester resin and the core-shell type polymer particles generally have low compatibility, so the core-shell type polymer particles may not be sufficiently dispersed in the polyester resin. As a result, the improvement in impact strength of the polyester resin by blending the core-shell type polymer particles is not necessarily sufficient.

Conventionally, the technology of Patent Document 1 is known as a core-shell type polymer particle, and the technologies of Patent Documents 2 and 3 are known as core-shell type polymer particles to be blended with polyester resin.

JP 2-191614 A JP 2021-155520 A International Patent Publication WO2013/157569 JP 2021-155520 A

The above-mentioned conventional technology was an improvement over typical core-shell polymer particles at the technical level at the time the conventional technology was developed. However, there is a high level of interest in the market regarding the effect of improving the impact resistance of molded articles made from polyester resin. The above-mentioned conventional technology left room for further improvement in terms of the effect of improving the impact resistance of molded articles made from polyester resin.

One embodiment of the present invention has been made in consideration of the above problems, and its purpose is to provide a modifier consisting of novel polymer particles that can be blended with a thermoplastic polyester resin to improve the impact strength of a molded article of the thermoplastic polyester resin, and a novel thermoplastic polyester resin composition containing the modifier.

The present inventors have conducted extensive research to solve the above problems, and as a result, have found that polymer particles having a core layer and a shell layer with a specific composition of structural units can improve the impact strength of a molded article of a thermoplastic polyester resin, thereby completing the present invention.
[1] A modifier for thermoplastic polyester resins, comprising polymer particles, the polymer particles having a core-shell structure including a first core layer, a second core layer formed on the outside of the first core layer, a first shell layer formed on the outside of the second core layer, and a second shell layer formed on the outside of the first shell layer, the first core layer including a crosslinked polymer _C1 including an acrylate ester unit including an alkyl group having 5 to 9 carbon atoms and a polyfunctional monomer unit, the second core layer including a crosslinked polymer C2 including an acrylate ester unit, an epoxy group-containing (meth)acrylic monomer unit, and a polyfunctional monomer _unit , the first shell layer including 60% by weight to 100% by weight of the acrylate ester unit based on 100% by weight of the first shell layer, and the second shell layer including 60% by weight to 100% by weight of the methacrylate ester unit based on 100% by weight of the second shell layer.
[2] The modifier for thermoplastic polyester resins according to [1], wherein the first shell layer further contains an epoxy group-containing (meth)acrylic monomer unit.
[3] The thermoplastic polyester resin modifier according to [1] or [2], wherein the epoxy groups contained in the polymer particles are 1.0 x 10 ⁴ to 8.0 x 10 ⁶ per particle.
[4] The thermoplastic polyester resin modifier according to [1] or [2], wherein the epoxy groups contained in the polymer particles are 2.5 x 10 ⁴ to 4.5 x 10 ⁶ per particle.
[5] The thermoplastic polyester resin modifier according to [1] or [2], wherein the epoxy groups contained in the polymer particles are 5.0 × 10 ⁴ groups/particle to 9.0 × 10 ⁵ groups/particle.
[6] The modifier for thermoplastic polyester resins according to any one of [1] to [5], wherein the second shell layer does not contain an epoxy group-containing (meth)acrylic monomer unit.
[7] The modifier for thermoplastic polyester resins according to any one of [1] to [6], wherein the first shell layer and/or the second shell layer does not contain a polyfunctional monomer unit.
[8] The modifier for thermoplastic polyester resins according to any one of [1] to [7], wherein the content ratios of the first core layer, the second core layer, the first shell layer, and the second shell layer in the polymer particles are 60% by weight to 90% by weight, 2% by weight to 30% by weight, 2% by weight to 15% by weight, and 3% by weight to 15% by weight, respectively, in 100% by weight of the polymer particles.
[9] A thermoplastic polyester resin composition comprising a thermoplastic polyester resin and the modifier for thermoplastic polyester resin according to any one of [1] to [8], wherein the thermoplastic polyester resin composition contains 2% by weight to 40% by weight of the modifier for thermoplastic polyester resin in a total of 100% by weight of the thermoplastic polyester resin and the modifier for thermoplastic polyester resin.
[10] A molded article made of the thermoplastic polyester resin composition according to [9].

According to one embodiment of the present invention, it is possible to provide a modifier made of novel polymer particles that can be blended with a thermoplastic polyester resin to improve the impact strength of a molded product of the thermoplastic polyester resin, and a novel thermoplastic polyester resin composition containing the modifier.

One embodiment of the present invention will be described below, but the present invention is not limited to this. The present invention is not limited to each of the configurations described below, and various modifications are possible within the scope of the claims. In addition, embodiments or examples obtained by combining the technical means disclosed in different embodiments or examples are also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment. All academic literature and patent documents described in this specification are incorporated herein by reference. In addition, unless otherwise specified in this specification, "A to B" representing a numerical range intends "A or more (including A and greater than A) and B or less (including B and smaller than B)."

In this specification, a "structural unit derived from an X monomer" may be referred to as an "X monomer unit" or an "X unit."

[Modifier for thermoplastic polyester resin]
The thermoplastic polyester resin modifier according to one embodiment of the present invention is composed of polymer particles which are graft copolymers. It can also be said that the thermoplastic polyester resin modifier according to one embodiment of the present invention includes polymer particles. The polymer particles have a core-shell structure including at least a first core layer, a second core layer formed on the outside of the first core layer, a first shell layer formed on the outside of the second core layer, and a second shell layer formed on the outside of the first shell layer. The first core layer includes a crosslinked polymer _C1 including an acrylic acid ester unit including an alkyl group having 5 to 9 carbon atoms, and a polyfunctional monomer unit. The second core layer includes a crosslinked polymer _C2 including an acrylic acid ester unit, an epoxy group-containing (meth)acrylic monomer unit, and a polyfunctional monomer unit. The first shell layer includes 60% to 100% by weight of an acrylic acid ester unit in 100% by weight of the first shell layer. The second shell layer includes 60% to 100% by weight of a methacrylic acid ester unit in 100% by weight of the second shell layer.

In this specification, the term "thermoplastic polyester resin modifier" may be simply referred to as "modifier", and the term "thermoplastic polyester resin modifier according to one embodiment of the present invention" may be referred to as "the present modifier". In this specification, "(meth)acrylic" refers to methacrylic and/or acrylic. For example, "(meth)acrylic monomer unit" refers to methacrylic monomer unit and/or acrylic monomer unit. Similarly, in this specification, "(meth)acrylate" refers to methacrylate and/or acrylate.

Since this modifier has the above-mentioned composition, it has the advantage that by blending this modifier with a thermoplastic polyester resin, it is possible to provide a molded product of the thermoplastic polyester resin that has excellent impact strength (in other words, excellent impact resistance).

(First Core Layer and Second Core Layer)
The first core layer may be a layer that is formed first in the production of the polymer particle, that is, the first core layer may be a particulate layer located at the innermost part of the polymer particle.

The second core layer is a layer formed on the outside of the first core layer. The second core layer may cover the outside of the first core layer. However, it does not cover the entire surface of the first core layer, but it is sufficient that the second core layer covers at least a portion of the surface of the first core layer. It is preferable that at least a portion of the polymer constituting the second core layer is graft polymerized to the polymer constituting the first core layer.

Both the first core layer and the second core layer may contain an acrylic rubber. Specifically, the first core layer contains a crosslinked polymer _C1 containing an acrylic ester unit containing an alkyl group having 5 to 9 carbon atoms and a polyfunctional monomer unit. The second core layer contains a crosslinked polymer _C2 containing an acrylic ester unit, an epoxy group-containing (meth)acrylic monomer unit, and a polyfunctional monomer unit. The first core layer may further contain a polymer other than the crosslinked polymer _C1 (e.g., a polymer not containing a polyfunctional monomer unit). The second core layer may further contain a polymer other than the crosslinked polymer _C2 (e.g., a polymer not containing a polyfunctional monomer unit).

The acrylic acid ester monomer from which the acrylic acid ester unit is derived is not particularly limited, and examples thereof include acrylic acid esters containing an alkyl group, acrylic acid esters containing an aromatic ring, and acrylic acid esters containing an alkoxy group. In the acrylic acid esters containing an alkyl group, the alkyl group may have a reactive functional group such as a hydroxyl group. Examples of the acrylic acid esters containing an alkyl group include (a) alkyl acrylates such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, dodecyl acrylate, stearyl acrylate, and behenyl acrylate, and (b) hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate. Examples of the acrylic acid esters containing an aromatic ring include phenoxyethyl acrylate and benzyl acrylate. Examples of the acrylic acid esters containing an alkoxy group include methoxy acrylate and ethoxy acrylate.

Because of the advantage of being easily available industrially, the second core layer preferably contains structural units derived from one or more monomers selected from the group consisting of acrylic esters containing alkyl groups among the above-mentioned acrylic ester monomers, and it is particularly preferable that the second core layer contains butyl acrylate units.

Among the above-mentioned acrylic acid ester monomers, examples of acrylic acid ester monomers containing an alkyl group having 5 to 9 carbon atoms include 2-ethylhexyl acrylate and octyl acrylate. Since the resulting thermoplastic polyester resin composition containing the modifier has the advantage of being able to provide a molded article having high low-temperature impact strength, it is preferable that the first core layer contains 2-ethylhexyl acrylate units among acrylic acid ester units containing an alkyl group having 5 to 9 carbon atoms.

The epoxy group-containing (meth)acrylic monomer is not particularly limited, but examples thereof include glycidyl acrylate, glycidyl alkyl acrylate, glycidyl methacrylate, and glycidyl alkyl methacrylate. Among these epoxy group-containing (meth)acrylic monomers, one or more selected from the group consisting of glycidyl acrylate and glycidyl methacrylate are preferred, and glycidyl methacrylate is particularly preferred, because they are easily available industrially.

In this specification, epoxy group-containing (meth)acrylic monomers are not included in acrylic acid ester monomers and methacrylic acid ester monomers.

The polyfunctional monomer may function as a crosslinking agent in the core layer. The polyfunctional monomer is not particularly limited, but may be allyl (meth)acrylate, allyl alkyl (meth)acrylates such as allyl alkyl (meth)acrylate, allyl oxy alkyl (meth)acrylates, polyfunctional (meth)acrylates having two or more (meth)acrylic groups such as (poly)ethylene glycol di(meth)acrylate, butane diol di(meth)acrylate, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, divinyl benzene, etc. Among these polyfunctional monomers, one or more selected from the group consisting of allyl methacrylate, triallyl isocyanurate, butane diol di(meth)acrylate, and divinyl benzene are preferred because they are easily available industrially, and allyl methacrylate is particularly preferred.

In this specification, polyfunctional monomers are not included in acrylic acid ester monomers and methacrylic acid ester monomers.

In the first core layer, in addition to the acrylic acid ester units and polyfunctional monomer units containing an alkyl group having 5 to 9 carbon atoms, the first core layer may or may not further contain structural units derived from other monomers other than the acrylic acid ester monomer containing an alkyl group having 5 to 9 carbon atoms and the polyfunctional monomer. The other monomers other than the acrylic acid ester monomer containing an alkyl group having 5 to 9 carbon atoms and the polyfunctional monomer are not particularly limited, and examples thereof include acrylic acid ester monomers containing an alkyl group having 1 to 4 carbon atoms and acrylic acid ester monomers containing an alkyl group having 10 or more carbon atoms; epoxy group-containing (meth)acrylic monomers; methacrylic acid ester monomers as described below; aromatic vinyl compounds such as styrene; cyanide vinyl compounds such as acrylonitrile; vinyl halides such as vinyl chloride; vinyl acetate; alkenes such as ethylene and propylene; and the like.

The first core layer preferably further contains butyl acrylate units, since this has the advantage that the particle size of the polymer particles is more likely to be stable. In other words, it is particularly preferable that the first core layer contains both 2-ethylhexyl acrylate units and butyl acrylate units.

In the first core layer, the content of acrylic acid ester units containing an alkyl group having 5 to 9 carbon atoms in 100% by weight of the total amount of all structural units constituting the first core layer, excluding polyfunctional monomer units, is preferably 50% by weight or more, more preferably 60% by weight or more, more preferably 70% by weight or more, even more preferably 80% by weight or more, and particularly preferably 90% by weight or more. When the content is 50% by weight or more, the obtained thermoplastic polyester resin composition containing the modifier has the advantage of being able to provide a molded product with high low-temperature impact strength. The upper limit of the content is not particularly limited, and may be 100% by weight.

It is preferable that the crosslinked polymer _C1 does not substantially contain an epoxy group-containing (meth)acrylic monomer unit. Specifically, in the crosslinked polymer _C1 , the content of the epoxy group-containing (meth)acrylic monomer unit in the total amount of 100% by weight of all the constituent units constituting the crosslinked polymer _C1 , excluding the polyfunctional monomer unit, is preferably less than 1% by weight, more preferably 0.5% by weight or less, and even more preferably 0.1% by weight or less. The lower limit of the content is not particularly limited, and may be 0% by weight. When the crosslinked polymer _C1 does not substantially contain an epoxy group-containing (meth)acrylic monomer unit, the glass transition temperature (Tg) of the core layer does not become too high, so that the obtained thermoplastic polyester resin composition containing the modifier has an advantage that it can provide a molded product having high low-temperature impact strength.

It is preferable that the first core layer does not substantially contain an epoxy group-containing (meth)acrylic monomer unit. Specifically, in the first core layer, the content of the epoxy group-containing (meth)acrylic monomer unit in the total amount of 100% by weight of all the constituent units constituting the first core layer, excluding the polyfunctional monomer unit, is preferably less than 1% by weight, more preferably 0.5% by weight or less, and even more preferably 0.1% by weight or less. The lower limit of the content is not particularly limited and may be 0% by weight. When the first core layer does not substantially contain an epoxy group-containing (meth)acrylic monomer unit or the content of the epoxy group-containing (meth)acrylic monomer unit in the first core layer is within the above-mentioned range, the glass transition temperature (Tg) of the core layer does not become too high, so that the obtained thermoplastic polyester resin composition containing the modifier has the advantage of being able to provide a molded product with high low-temperature impact strength.

In the first core layer, the content of the polyfunctional monomer unit relative to 100 parts by weight of the total amount of the constituent units excluding the polyfunctional monomer unit among all the constituent units constituting the first core layer is preferably 0.01 parts by weight to 10.00 parts by weight, more preferably 0.05 parts by weight to 5.00 parts by weight, and even more preferably 0.10 parts by weight to 3.00 parts by weight. When the content is 0.01 parts by weight or more, the first core layer can secure a graft point with the shell layer, which has the advantage of improving the granulation property of the polymer particles and the advantage of improving the dispersibility of the modifier in the thermoplastic polyester resin composition. When the content is 10.00 parts by weight or less, the elastic modulus of the core layer is not too high, which has the advantage of providing a molded product with high low-temperature impact strength from the resulting thermoplastic polyester resin composition containing the modifier.

In the first core layer, the content of the crosslinked polymer _C1 in 100% by weight of the first core layer is preferably 70% by weight or more, more preferably 80% by weight or more, more preferably 90% by weight or more, even more preferably 95% by weight or more, and particularly preferably 100% by weight. In other words, it is particularly preferable that the first core layer is composed only of the crosslinked polymer _C1 . When the content of the crosslinked polymer _C1 contained in the first core layer is within the above-mentioned range, the obtained thermoplastic polyester resin composition containing the modifier has an advantage that it can provide a molded product having high low-temperature impact strength.

In the second core layer, in addition to the acrylic acid ester units, the epoxy group-containing (meth)acrylic monomer units, and the polyfunctional monomer units, the second core layer may or may not further contain structural units derived from other monomers other than the acrylic acid ester monomers, the epoxy group-containing (meth)acrylic monomers, and the polyfunctional monomers. The other monomers other than the acrylic acid ester monomers, the epoxy group-containing (meth)acrylic monomers, and the polyfunctional monomers are not particularly limited, and examples thereof include methacrylic acid ester monomers as described below; aromatic vinyl compounds such as styrene; vinyl cyanide compounds such as acrylonitrile; vinyl halides such as vinyl chloride; vinyl acetate; alkenes such as ethylene and propylene; and the like.

In the second core layer, the content of acrylic acid ester units in the total amount of 100% by weight of all the constituent units constituting the second core layer, excluding the polyfunctional monomer units, is preferably 50% by weight or more, more preferably 60% by weight or more, more preferably 70% by weight or more, and even more preferably 80% by weight or more. When the content is 50% by weight or more, the obtained thermoplastic polyester resin composition containing the modifier has the advantage of being able to provide a molded product with high low-temperature impact strength. The upper limit of the content is preferably 99% by weight or less, more preferably 96% by weight or less, and even more preferably 90% by weight or less. When the content is 99% by weight or less, the elastic modulus of the core layer does not become too high, so that the obtained thermoplastic polyester resin composition containing the modifier has the advantage of being able to provide a molded product with high low-temperature impact strength.

In the second core layer, the content of the epoxy group-containing (meth)acrylic monomer unit in the total amount of 100% by weight of all the constituent units constituting the second core layer, excluding the polyfunctional monomer unit, is preferably 1.0% by weight or more, more preferably 2.0% by weight or more, more preferably 5.0% by weight or more, even more preferably 7.0% by weight or more, and particularly preferably 9.5% by weight or more. When the content is 1.0% by weight or more, there is an advantage that the dispersibility of the modifier in the thermoplastic polyester resin composition is good. The upper limit of the content is preferably 50.0% by weight or less, more preferably 30.0% by weight or less, and even more preferably 20.0% by weight or less. When the content is 50.0% by weight or less, there is an advantage that the resin fluidity of the thermoplastic polyester resin composition containing the obtained modifier is not deteriorated.

The content of the epoxy group-containing (meth)acrylic monomer unit contained in the second core layer is preferably 0.1% by weight or more, more preferably 0.3% by weight or more, even more preferably 0.4% by weight or more, and particularly preferably 0.5% by weight or more, based on 100% by weight of the polymer particles. When the content of the epoxy group-containing (meth)acrylic monomer unit contained in the second core layer is 0.1% by weight or more based on 100% by weight of the polymer particles, the obtained modifier has the advantage of being able to further enhance the effect of improving the impact strength of the molded body of the thermoplastic polyester resin. The content of the epoxy group-containing (meth)acrylic monomer unit contained in the second core layer is preferably 2.0% by weight or less, more preferably 1.5% by weight or less, more preferably 1.3% by weight or less, even more preferably 1.1% by weight or less, and particularly preferably 1.0% by weight or less, based on 100% by weight of the polymer particles. When the content of the epoxy group-containing (meth)acrylic monomer unit contained in the second core layer is 2.0% by weight or less based on 100% by weight of the polymer particles, when the modifier is blended with the thermoplastic polyester resin, there is no risk of the polymer particles constituting the modifier agglomerating in the resin composition, and the effect of the modifier in improving the impact strength of the molded article can be fully enjoyed.

In the second core layer, the content of the polyfunctional monomer unit relative to 100 parts by weight of the total amount of the constituent units excluding the polyfunctional monomer unit among all the constituent units constituting the second core layer is preferably 0.01 parts by weight to 10.00 parts by weight, more preferably 0.05 parts by weight to 5.00 parts by weight, and even more preferably 0.10 parts by weight to 3.00 parts by weight. When the content is 0.01 parts by weight or more, the second core layer can secure a graft point with the shell layer, which has the advantage of improving the granulation property of the polymer particles and the advantage of improving the dispersibility of the modifier in the thermoplastic polyester resin composition. When the content is 10.00 parts by weight or less, the elastic modulus of the core layer is not too high, which has the advantage of providing a molded product with high low-temperature impact strength from the resulting thermoplastic polyester resin composition containing the modifier.

In the second core layer, the content of the crosslinked polymer _C2 in 100% by weight of the second core layer is preferably 70% by weight or more, more preferably 80% by weight or more, more preferably 90% by weight or more, even more preferably 95% by weight or more, and particularly preferably 100% by weight. In other words, it is particularly preferable that the second core layer is composed only of the crosslinked polymer _C2 . When the content of the crosslinked polymer _C2 contained in the second core layer is within the above-mentioned range, there is an advantage that the balance between the melt viscosity of the thermoplastic polyester resin composition containing the obtained modifier and the impact strength of the molded body obtained from the resin composition is good (excellent melt viscosity and excellent impact strength can be achieved at the same time).

In addition to the first core layer and the second core layer, the core layer may or may not include a layer other than the first core layer and the second core layer (for example, a third core layer). The third core layer and subsequent layers are preferably layers formed between the first core layer and the second core layer. More specifically, the first core layer is preferably formed before the second core layer and the third core layer and subsequent layers, and is preferably the first layer formed in the production of the polymer particles. In other words, the first core layer is preferably a particulate layer located at the innermost part of the polymer particles. This configuration has the advantage that the particle diameter of the polymer particles is easily stabilized. In addition, the second core layer is preferably formed after the first core layer and the third core layer and subsequent layers, and is preferably the last layer formed in the production of the core layer. In other words, the second core layer is preferably the outermost layer in the core layer. This configuration has the advantage that the obtained modifier can further enhance the effect of improving the impact strength of the molded body of the thermoplastic polyester resin.

(First shell layer and second shell layer)
The first shell layer is a layer formed on the outside of the second core layer. The first shell layer may cover the outside of the first core layer and/or the second core layer, and may particularly cover the outside of the second core layer. The first shell layer does not need to cover the entire surface of the core layer including the first core layer and the second core layer, but may cover at least a part of the surface of the core layer. At least a part of the polymer constituting the first shell layer is preferably graft polymerized (graft bonded) to the polymer constituting the first core layer (e.g., crosslinked polymer C ₁ ) and/or the polymer constituting the second core layer (e.g., crosslinked polymer C ₂ ). In addition, a part of the polymer constituting the first shell layer may be present as a free polymer without being graft polymerized (graft bonded) to either the polymer constituting the first core layer or the polymer constituting the second core layer. In this specification, such a free polymer is also included in the polymer particle.

The first shell layer may contain an acrylic polymer. Specifically, the first shell layer contains 60% to 100% by weight of acrylic ester units, based on 100% by weight of the first shell layer. This configuration has the advantage that the balance between the melt viscosity of the thermoplastic polyester resin composition containing the modifier obtained and the impact strength of the molded body obtained from the resin composition is good (excellent melt viscosity and excellent impact strength can be achieved at the same time). Since this advantage can be further enjoyed, the content of the acrylic ester units in the first shell layer is preferably 60% to 99% by weight, more preferably 70% to 97% by weight, and even more preferably 75% to 95% by weight, based on 100% by weight of the first shell layer.

In addition to the acrylic acid ester units, the first shell layer may or may not contain structural units derived from other monomers other than the acrylic acid ester units. In the first shell layer, the other monomers other than the acrylic acid ester units are not particularly limited, but examples thereof include methacrylic acid ester monomers; epoxy group-containing (meth)acrylic monomers; polyfunctional monomer units; aromatic vinyl compounds such as styrene; vinyl cyanide compounds such as acrylonitrile; vinyl halides such as vinyl chloride; vinyl acetate; alkenes such as ethylene and propylene; and the like.

The second shell layer is a layer formed on the outside of the first shell layer. The second shell layer may cover the outside of the first core layer, the second core layer, and/or the first shell layer, and may particularly cover the outside of the first shell layer. The second shell layer does not need to cover the entire surface of the core layer including the first core layer and the second core layer and the first shell layer, but may cover at least a part of the surface of the core layer and the first shell layer. At least a part of the polymer constituting the second shell layer is preferably graft polymerized (graft bonded) to the polymer constituting the first core layer (e.g., crosslinked polymer C ₁ ), the polymer constituting the second core layer (e.g., crosslinked polymer C ₂ ), and/or the polymer constituting the first shell layer. In addition, a part of the polymer constituting the second shell layer may be present as a free polymer without being graft polymerized (graft bonded) to any of the polymer constituting the first core layer, the polymer constituting the second core layer, or the polymer constituting the first shell layer. In this specification, such a free polymer is also included in the polymer particle.

The second shell layer may contain a methacrylic polymer. Specifically, the second shell layer contains 60% to 100% by weight of methacrylic acid ester units in 100% by weight of the second shell layer. This configuration has the advantage that the polymer particles are less likely to become coarse in the powdering process in which a powder of polymer particles is obtained from latex containing polymer particles, and the obtained polymer particles are easily dispersed uniformly in the thermoplastic polyester resin. In addition, the configuration has the advantage that the mechanical stability of the latex containing polymer particles is improved. Since this advantage can be further enjoyed, the content of the methacrylic acid ester units in the second shell layer is preferably 70% to 100% by weight, more preferably 80% to 100% by weight, even more preferably 90% to 100% by weight, particularly preferably 95% to 100% by weight, and most preferably 100% by weight, in 100% by weight of the second shell layer. It is most preferable that the second shell layer is composed of only methacrylic acid ester units.

In the second shell layer, in addition to the methacrylic acid ester units, the second shell layer may or may not contain structural units derived from other monomers other than the methacrylic acid ester units. In the second shell layer, the other monomers other than the methacrylic acid ester units are not particularly limited, but examples thereof include acrylic acid ester monomers; epoxy group-containing (meth)acrylic monomers; polyfunctional monomer units; aromatic vinyl compounds such as styrene; vinyl cyanide compounds such as acrylonitrile; vinyl halides such as vinyl chloride; vinyl acetate; alkenes such as ethylene and propylene; and the like.

In the first and second shell layers, the acrylic acid ester monomer from which the acrylic acid ester units are derived is not particularly limited. Specific examples of acrylic acid ester monomers are the same as those described above in the section (First Core Layer and Second Core Layer), so the description is incorporated herein and will not be repeated here. Among the above-mentioned acrylic acid ester monomers, one or more selected from the group consisting of alkyl acrylates is preferred for the first and second shell layers, as it has the advantage of being easily available industrially, and butyl acrylate is particularly preferred.

The methacrylic acid ester monomer from which the methacrylic acid ester unit is derived is not particularly limited, but examples thereof include alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, dodecyl methacrylate, stearyl methacrylate, and behenyl methacrylate; aromatic ring-containing methacrylic acid esters such as phenoxyethyl methacrylate and benzyl methacrylate; hydroxyalkyl methacrylates such as 2-hydroxyethyl methacrylate and 4-hydroxybutyl methacrylate; and alkoxyalkyl methacrylates. Among these methacrylic acid ester monomers, one or more selected from the group consisting of alkyl methacrylates is preferred for the first shell layer and the second shell layer, with methyl methacrylate being particularly preferred, due to the advantages of being easily available industrially and being able to increase the Tg of the shell layer and therefore being highly compatible with the thermoplastic polyester resin.

It is preferable that the first shell layer further contains an epoxy group-containing (meth)acrylic monomer unit. According to this configuration, the modifier has the advantage of being able to provide a molded body of a thermoplastic polyester resin having superior impact strength. In order to enjoy such an advantage more, in the first shell layer, the content of the epoxy group-containing (meth)acrylic monomer unit in the total amount of 100% by weight of all the constituent units constituting the first shell layer, excluding the polyfunctional monomer unit, is preferably 0.3% by weight or more, more preferably 0.5% by weight or more, even more preferably 0.7% by weight or more, and particularly preferably 1.0% by weight or more. The upper limit of the content of the epoxy group-containing (meth)acrylic monomer unit in the first shell layer is not particularly limited. Since the resulting thermoplastic polyester resin composition containing the modifier has good fluidity, in the first shell layer, the content of the epoxy group-containing (meth)acrylic monomer unit in the total amount of 100% by weight of all the constituent units constituting the first shell layer, excluding the polyfunctional monomer unit, is preferably 50% by weight or less, more preferably 40% by weight or less, even more preferably 30% by weight or less, and particularly preferably 20% by weight or less.

In the first shell layer, the epoxy group-containing (meth)acrylic monomer is not particularly limited. Specific examples of the epoxy group-containing (meth)acrylic monomer are the same as those described in the above section (First core layer and second core layer), so the description is incorporated herein and will not be repeated here. Among the epoxy group-containing (meth)acrylic monomers in the first shell layer, one or more selected from the group consisting of glycidyl acrylate and glycidyl methacrylate are preferred, and glycidyl methacrylate is more preferred, due to their advantage of being easily available industrially.

The content of the epoxy group-containing (meth)acrylic monomer unit contained in the first shell layer is preferably 0.01% by weight or more, more preferably 0.03% by weight or more, more preferably 0.04% by weight or more, more preferably 0.05% by weight or more, more preferably 0.08% by weight or more, more preferably 0.10% by weight or more, more preferably 0.20% by weight or more, more preferably 0.30% by weight or more, more preferably 0.40% by weight or more, and even more preferably 0.50% by weight or more. When the content of the epoxy group-containing (meth)acrylic monomer unit contained in the first shell layer is 0.01% by weight or more in 100% by weight of the polymer particles, the obtained modifier has the advantage of being able to further enhance the effect of improving the impact strength of the molded body of the thermoplastic polyester resin. The content of the epoxy group-containing (meth)acrylic monomer unit contained in the first shell layer is preferably 2.00% by weight or less, more preferably 1.50% by weight or less, more preferably 1.30% by weight or less, more preferably 1.10% by weight or less, more preferably 1.00% by weight or less, more preferably 0.80% by weight or less, more preferably 0.60% by weight or less, and even more preferably 0.50% by weight or less, based on 100% by weight of the polymer particles. When the content of the epoxy group-containing (meth)acrylic monomer unit contained in the first shell layer is 2.0% by weight or less based on 100% by weight of the polymer particles, when the modifier is blended with the thermoplastic polyester resin, there is no risk of the polymer particles constituting the modifier agglomerating in the resin composition, and the effect of improving the impact strength of the molded body by the modifier can be fully enjoyed.

It is preferable that the second shell layer does not substantially contain epoxy group-containing (meth)acrylic monomer units. Specifically, in the second shell layer, the content of epoxy group-containing (meth)acrylic monomer units in the total amount of 100% by weight of all the constituent units constituting the second shell layer, excluding the polyfunctional monomer units, is preferably less than 1% by weight, more preferably 0.5% by weight or less, and even more preferably 0.1% by weight or less. The lower limit of the content is not particularly limited, and may be 0% by weight. When the second shell layer does not substantially contain epoxy group-containing (meth)acrylic monomer units or the content of the epoxy group-containing (meth)acrylic monomer units in the second shell layer is within the above-mentioned range, there is an advantage that there is no risk of deteriorating the fluidity of the thermoplastic polyester resin composition containing the obtained modifier.

It is preferable that the first shell layer does not substantially contain a polyfunctional monomer unit. In other words, it is preferable that the first shell layer is substantially non-crosslinked. Specifically, in the first shell layer, the content of the polyfunctional monomer unit relative to 100 parts by weight of the total amount of the constituent units excluding the polyfunctional monomer unit among all the constituent units constituting the first shell layer is preferably less than 1% by weight, more preferably 0.5% by weight or less, and even more preferably 0.1% by weight or less. The lower limit of the content is not particularly limited, and may be 0% by weight. When the first shell layer does not substantially contain an epoxy group-containing (meth)acrylic monomer unit, or the content of the epoxy group-containing (meth)acrylic monomer unit in the first shell layer is within the above-mentioned range, the obtained modifier has the advantage of being able to further enhance the effect of improving the impact strength of a molded body of a thermoplastic polyester resin.

It is preferable that the second shell layer does not substantially contain polyfunctional monomer units. In other words, it is preferable that the second shell layer is substantially non-crosslinked. Specifically, in the second shell layer, the content of polyfunctional monomer units relative to 100 parts by weight of the total amount of the constituent units excluding the polyfunctional monomer units among all the constituent units constituting the second shell layer is preferably less than 1% by weight, more preferably 0.5% by weight or less, and even more preferably 0.1% by weight or less. The lower limit of the content is not particularly limited, and may be 0% by weight. When the second shell layer does not substantially contain epoxy group-containing (meth)acrylic monomer units or the content of the epoxy group-containing (meth)acrylic monomer units in the second shell layer is within the above-mentioned range, it has the advantage that the granulation property of the polymer particles is good.

It is preferable that the shell layer does not substantially contain polyfunctional monomer units. In other words, it is preferable that the shell layer is substantially non-crosslinked. Specifically, in the shell layer, the content of polyfunctional monomer units relative to 100 parts by weight of the total amount of the constituent units excluding the polyfunctional monomer units among all the constituent units constituting the shell layer is preferably less than 1% by weight, more preferably 0.5% by weight or less, and even more preferably 0.1% by weight or less. The lower limit of the content is not particularly limited, and may be 0% by weight. When the shell layer does not substantially contain epoxy group-containing (meth)acrylic monomer units or the content of the epoxy group-containing (meth)acrylic monomer units in the shell layer is within the above-mentioned range, it has the advantage that the granulation property of the polymer particles is good.

In addition to the first and second shell layers, the shell layer may or may not include a layer other than the first and second shell layers (e.g., a third shell layer). The third and subsequent shell layers are preferably layers formed between the first and second shell layers. More specifically, the first shell layer is preferably formed before the second and third shell layers, and is preferably the first layer formed in the production of the shell layer (the first layer formed after the formation of the core layer). In other words, the first shell layer is preferably the innermost layer in the shell layer. According to this configuration, the obtained modifier has the advantage of being able to further enhance the effect of improving the impact strength of the molded body of the thermoplastic polyester resin. In addition, the second shell layer is preferably formed after the first and third shell layers, and is preferably the last layer formed in the production of the shell layer. In other words, the second shell layer is preferably the outermost layer in the shell layer. According to this configuration, the advantage is that the granulation property of the polymer particles is good.

The epoxy group contained in the polymer particle is preferably 1.0×10 ⁴ /particle to 8.0×10 ⁶ /particle in the polymer particle. When the content of the epoxy group in the polymer particle is 1.0×10 ⁴ /particle or more in the polymer particle, the obtained modifier has the advantage that the effect of improving the impact strength of the molded body of the thermoplastic polyester resin can be further enhanced. Since the effect of improving the impact strength of the molded body by the modifier can be further enjoyed, the epoxy group contained in the polymer particle is more preferably 2.0×10 ⁴ /particle or more in the polymer particle, more preferably 2.5×10 ⁴ /particle or more, more preferably 4.0×10 ⁴ /particle or more, more preferably 5.0×10 ⁴ /particle or more, more preferably 6.0×10 ⁴ /particle or more, and particularly preferably 6.5×10 ⁴ /particle or more. When the content of epoxy groups in the polymer particles is 8.0 × ¹⁰ /particle or less, there is an advantage that when the modifier is blended with a thermoplastic polyester resin, there is no risk of the polymer particles constituting the modifier agglomerating in the resin composition, and the effect of the modifier in improving the impact strength of the molded article can be fully enjoyed. Since the risk of aggregation of the polymer particles constituting the modifier in the resin composition can be further reduced, the epoxy groups contained in the polymer particles are more preferably 6.0 x 10 / ¹ particle or less, more preferably 5.0 x ¹⁰ / 1 particle or less, more preferably 4.5 x 10 / ¹ particle or less, more preferably 3.0 x ¹⁰ / 1 particle or less, more preferably 2.0 x ¹⁰ / 1 particle or less, more preferably 1.0 x ¹⁰ / 1 particle or less, more preferably 9.0 x ¹⁰ / ¹ particle or less, more preferably 7.5 x 10 / 1 particle or less, more preferably 5.0 x ¹⁰ / 1 particle or less, and particularly preferably 2.5 x ¹⁰ / 1 particle or less. The epoxy groups contained in the polymer particles can be calculated, for example, by the following method: {1(g)×[(parts by weight of epoxy group-containing (meth)acrylic monomer/100)/molecular weight of epoxy group-containing (meth)acrylic monomer]×Avogadro's constant}/{1( ^cm3 )/[(4/3)×π×(volume average particle size of polymer microparticles ( ^cm3 )/2)^3]}. The volume average particle size of the polymer microparticles can be measured using a dynamic light scattering particle size distribution measuring device.

(Content of each layer)
The content of each layer contained in the polymer particles is not particularly limited. Since the effect of improving the impact strength of a molded body of a thermoplastic polyester resin is more excellent, the content ratios of the first core layer, the second core layer, the first shell layer and the second shell layer in 100% by weight of the polymer particles are preferably 60% by weight to 90% by weight, 2% by weight to 30% by weight, 2% by weight to 15% by weight and 3% by weight to 15% by weight, respectively. Since the effect of improving the impact strength of a molded body of a thermoplastic polyester resin is even more excellent, the content of the first core layer in 100% by weight of the polymer microparticles is more preferably 65% by weight to 85% by weight, and even more preferably 70% by weight to 80% by weight. Since the effect of improving the impact strength of a molded body of a thermoplastic polyester resin is even more excellent, the content of the second core layer in 100% by weight of the polymer microparticles is more preferably 3% by weight to 20% by weight, more preferably 4% by weight to 15% by weight, and particularly preferably 5% by weight to 10% by weight. In order to obtain a more excellent effect of improving the impact strength of a molded article of a thermoplastic polyester resin, the content of the first shell layer in 100% by weight of the polymer microparticles is preferably 3% by weight to 13% by weight, and more preferably 4% by weight to 10% by weight. In order to obtain a more excellent effect of improving the impact strength of a molded article of a thermoplastic polyester resin, the content of the second shell layer in 100% by weight of the polymer microparticles is preferably 4% by weight to 13% by weight, and more preferably 5% by weight to 10% by weight.

(Method for producing polymer particles)
The method for producing the polymer particles can be a conventional method, and is not particularly limited. For example, any of bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization can be adopted. The method for producing the polymer particles is preferably emulsion polymerization, i.e., emulsion graft polymerization. Specifically, in emulsion graft polymerization, first, a latex of polymer particles corresponding to the first core layer is produced by emulsion polymerization, and the monomer components of the second core layer, the first shell layer, or the second shell layer, and if necessary, a polymerization initiator, etc. are sequentially added to the latex to sequentially polymerize the monomer components.

A preferred embodiment of the method for producing the polymer particles includes a method in which the following steps (1) to (4) are carried out in order: (1) A latex of polymer particles corresponding to the first core layer is produced by emulsion polymerization; (2) A monomer component of the second core layer and, if necessary, a polymerization initiator, etc. are added to the latex of polymer particles corresponding to the first core layer, and the monomer component of the second core layer is polymerized in the presence of polymer particles corresponding to the first core layer; (3) A monomer component of the first shell layer and, if necessary, a polymerization initiator, etc. are added to the latex of polymer particles including the first core layer and the second core layer, and the monomer component of the first shell layer is polymerized in the presence of polymer particles including the first core layer and the second core layer; (4) A monomer component of the second shell layer and, if necessary, a polymerization initiator, etc. are added to the latex of polymer particles including the first core layer, the second core layer, and the first shell layer, and the monomer component of the second shell layer is polymerized in the presence of polymer particles including the first core layer, the second core layer, and the first shell layer.

The emulsifier (dispersant) that can be used in emulsion polymerization is not particularly limited, and anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, etc. can be used. In addition, dispersants such as polyvinyl alcohol, alkyl-substituted cellulose, polyvinylpyrrolidone, and polyacrylic acid derivatives may be used in emulsion polymerization.

The anionic surfactant is not particularly limited, but examples thereof include the following compounds: fatty acid soaps such as potassium laurate, potassium coconut fatty acid, potassium myristate, potassium oleate, potassium oleate diethanolamine salt, sodium oleate, potassium palmitate, potassium stearate, sodium stearate, mixed fatty acid soda soap, semi-hardened beef tallow fatty acid soda soap, and castor oil potassium soap; alkyl sulfates such as sodium dodecyl sulfate, sodium higher alcohol sulfate, triethanolamine dodecyl sulfate, ammonium dodecyl sulfate, sodium polyoxyethylene alkyl ether sulfate, triethanolamine polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, and sodium 2-ethylhexyl sulfate. Ester salts; sodium alkylbenzene sulfonates such as sodium dodecylbenzene sulfonate; sodium dialkyl sulfosuccinates such as sodium di-2-ethylhexyl sulfosuccinate; sodium alkylnaphthalenesulfonates; sodium alkyldiphenyletherdisulfonates; potassium alkylphosphates; phosphate ester salts such as sodium polyoxyethylene lauryl ether phosphate; sodium salts of naphthalenesulfonic acid formalin condensates; polycarboxylate type polymeric anions; sodium acyl (beef tallow) methyl taurate; sodium acyl (coconut) methyl taurate; sodium cocoyl isethionate; sodium α-sulfo fatty acid esters; sodium amidoethersulfonates; oleyl sarcosine; sodium lauroyl sarcosine; rosin acid soap; etc.

The nonionic surfactant is not particularly limited, but examples thereof include the following compounds: polyoxyethylene alkyl allyl ethers or polyoxyethylene alkyl ethers such as polyoxyethylene nonylphenyl ether, polyoxyethylene oleyl ether, and polyoxyethylene lauryl ether; polyoxyethylene sorbitan esters such as polyoxyethylene sorbitan monolaurate and polyoxyethylene sorbitan monostearate; polyoxyethylene fatty acid esters such as polyethylene glycol monolaurate, polyethylene glycol monostearate, and polyethylene glycol monooleate; oxyethylene/oxypropylene block copolymers; and the like.

The cationic surfactant is not particularly limited, but examples thereof include the following compounds: alkylamine salts such as coconut amine acetate, stearylamine acetate, octadecylamine acetate, and tetradecylamine acetate; quaternary ammonium salts such as lauryl trimethyl ammonium chloride, stearyl trimethyl ammonium chloride, cetyl trimethyl ammonium chloride, distearyl dimethyl ammonium chloride, alkyl benzyl dimethyl ammonium chloride, hexadecyl trimethyl ammonium chloride, and behenyl trimethyl ammonium chloride; etc.

The amphoteric surfactant is not particularly limited, but examples thereof include the following compounds: alkyl betaines such as lauryl betaine, stearyl betaine, and dimethyl lauryl betaine; sodium lauryl diaminoethyl glycine; amido betaine; imidazoline; lauryl carboxymethyl hydroxyethyl imidazolinium betaine, etc.

These emulsifiers (dispersants) may be used alone or in combination of two or more. The average particle size of the polymer particles can be controlled by adjusting the amount of emulsifier used.

When an emulsion polymerization method is used as the method for producing the polymer particles, a thermally decomposable initiator can be used to produce the polymer particles. Examples of the thermally decomposable initiator include known initiators such as (a) 2,2'-azobisisobutyronitrile and (b) peroxides such as organic peroxides and inorganic peroxides. Examples of the organic peroxides include t-butylperoxyisopropyl carbonate, paramenthane hydroperoxide, cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, and t-hexyl peroxide. Examples of the inorganic peroxides include hydrogen peroxide, potassium persulfate, and ammonium persulfate.

A redox type initiator can also be used to produce polymer particles. The redox type initiator is an initiator that uses (a) a peroxide such as an organic peroxide or an inorganic peroxide in combination with (b) a transition metal salt such as iron (II) sulfate, and/or a reducing agent such as sodium formaldehyde sulfoxylate or glucose. If necessary, a chelating agent such as disodium ethylenediaminetetraacetate, and if necessary, a phosphorus-containing compound such as sodium pyrophosphate, may also be used in combination.

When a redox type initiator is used, polymerization can be carried out even at a low temperature where the peroxide does not substantially decompose thermally, and the polymerization temperature can be set in a wide range. For this reason, it is preferable to use a redox type initiator. Among redox type initiators, redox type initiators using organic peroxides such as cumene hydroperoxide, dicumyl peroxide, paramenthane hydroperoxide, and t-butyl hydroperoxide as the peroxide are preferable. The amount of the initiator used can be appropriately selected within known ranges. When a redox type initiator is used, the amounts of the reducing agent, transition metal salt, chelating agent, etc. used can be appropriately selected within known ranges.

In the production of the polymer particles, when polymerizing a monomer having two or more radically polymerizable double bonds (e.g., a polyfunctional monomer), a known chain transfer agent can be used in a known amount range.

In the production of the polymer particles, a surfactant can be used in addition to the above-mentioned components. The type and amount of the surfactant used can be appropriately selected within known ranges.

The solvent used during emulsion polymerization may be any solvent that allows the emulsion polymerization to proceed stably, and water, for example, is preferably used.

The temperature during emulsion polymerization is not particularly limited as long as the emulsifier is uniformly dissolved in the solvent. Since this can improve the polymerization conversion rate at the end of the polymerization, the temperature during emulsion polymerization is, for example, 40 to 75°C, preferably 45°C to 70°C, and more preferably 49°C to 65°C.

The case where the polymer particles are produced by emulsion polymerization (hereinafter also referred to as Case A) will be described. In Case A, for example, the latex of the polymer particles can be mixed with (i) an acid such as hydrochloric acid, and/or (ii) a divalent or higher metal salt such as calcium chloride, magnesium chloride, magnesium sulfate, aluminum chloride, calcium acetate, etc., to aggregate (coagulate) the polymer particles in the latex. Next, the obtained aggregates of polymer particles can be separated from the aqueous medium (latex) by performing each operation such as heat treatment, dehydration, washing, and drying according to a known method. The obtained polymer particles are preferably washed with water and/or an organic solvent.

In addition, in case A, the polymer particles in the latex can be precipitated by adding an alcohol such as methanol, ethanol, or propanol, and/or a water-soluble organic solvent such as acetone to the latex of the polymer particles. The precipitated polymer particles can then be separated from the solvent by centrifugation, filtration, or the like, and then dried to isolate the polymer particles. In case A, another method for isolating the polymer particles includes adding an organic solvent having a small water solubility such as methyl ethyl ketone to the latex of the polymer particles to extract the polymer particles in the latex into an organic solvent layer, separating the organic solvent layer, and then mixing the separated organic solvent layer with water or the like to precipitate the polymer particles.

In addition, in case A, the latex of the polymer particles can be directly powdered by spray drying. The obtained powder is preferably washed with water and/or an organic solvent. Alternatively, calcium chloride, magnesium chloride, magnesium sulfate, aluminum chloride, etc. can be added to the obtained powder, preferably as a solution such as an aqueous solution, and then re-dried as necessary, to obtain the same effect as the above washing.

[Thermoplastic polyester resin composition]
A thermoplastic polyester resin composition according to one embodiment of the present invention contains a thermoplastic polyester resin and the modifier for thermoplastic polyester resin according to one embodiment of the present invention described in the above section [Modifier for thermoplastic polyester resin]. The thermoplastic polyester resin composition according to one embodiment of the present invention contains 2% by weight to 40% by weight of the modifier for thermoplastic polyester resin, with the total of the thermoplastic polyester resin and the modifier for thermoplastic polyester resin being 100% by weight.

In this specification, the "thermoplastic polyester resin composition" may be simply referred to as the "resin composition," and the "thermoplastic polyester resin composition according to one embodiment of the present invention" may be referred to as the "resin composition."

Because the resin composition has the above-mentioned structure, it has the advantage of being able to provide a molded article with excellent impact strength (in other words, excellent impact resistance). In other words, by blending the present modifier with a thermoplastic polyester resin, the impact strength of a molded article of the thermoplastic polyester resin can be improved.

(Amount of modifier)
In one embodiment of the present invention, the content of the modifier in the resin composition is not particularly limited, but is preferably 2% by weight to 40% by weight in the total of 100% by weight of the thermoplastic polyester resin and the modifier. According to this configuration, it is possible to obtain the effect of improving the impact strength of the molded body by blending the modifier while maintaining the physical properties unique to the thermoplastic polyester resin. Since the impact strength of the molded body of the polyester resin can be further improved by blending the modifier, the content of the modifier in the resin composition is more preferably 3% by weight or more, more preferably 4% by weight or more, and particularly preferably 5% by weight or more in the total of 100% by weight of the thermoplastic polyester resin and the modifier. Since the physical properties unique to the thermoplastic polyester resin can be further maintained by blending the modifier, the content of the modifier in the resin composition is more preferably 30% by weight or less, more preferably 28% by weight or less, and particularly preferably 25% by weight or less in the total of 100% by weight of the thermoplastic polyester resin and the modifier.

(Thermoplastic polyester resin)
The thermoplastic polyester resin is not particularly limited, and examples thereof include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, polybutylene naphthalate, poly 1,4-cyclohexylene dimethylene terephthalate, polyethylene-1,2-bis(phenoxy)ethane-4,4'-dicarboxylate, polyethylene isophthalate/terephthalate, polybutylene terephthalate/isophthalate, polybutylene terephthalate/decane dicarboxylate, polycyclohexane dimethylene terephthalate/isophthalate, polyester/polyether, etc. From the viewpoint of moldability and/or mechanical properties, the thermoplastic polyester resin is preferably one or more selected from the group consisting of polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, polybutylene naphthalate, poly 1,4-cyclohexylene dimethylene terephthalate, and polyester/polyether, and more preferably polyethylene terephthalate and/or polybutylene terephthalate.

(Other resins)
The resin composition may or may not contain a thermoplastic resin other than the thermoplastic polyester resin. The thermoplastic resin other than the thermoplastic polyester resin is not particularly limited, but examples thereof include polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyvinyl acetate, polyurethane, polytetrafluoroethylene, ABS resin, AS resin, acrylic resin, polyacetal, polycarbonate, modified polyphenylene ether, polyamide, and cyclic polyolefin. The content of the thermoplastic resin other than the thermoplastic polyester resin in the resin composition is not particularly limited, but is preferably 0 parts by weight to 100 parts by weight, more preferably 0 parts by weight to 50 parts by weight, even more preferably 0 parts by weight to 30 parts by weight, and particularly preferably 0 parts by weight to 10 parts by weight, relative to 100 parts by weight of the thermoplastic polyester resin.

(Other Additives)
The resin composition may appropriately contain additives that can be blended into general thermoplastic resin compositions. Examples of such additives include, but are not limited to, flame retardants, flame retardant assistants, anti-dripping agents, reinforcing materials, fillers, antioxidants, pigments, dyes, conductivity imparting agents, hydrolysis inhibitors, thickeners, plasticizers, lubricants, UV absorbers, antistatic agents, flow improvers, release agents, compatibilizers, and heat stabilizers.

(Method for producing resin composition)
The method for producing the thermoplastic polyester resin composition of the present invention is not particularly limited, and a general method for producing a thermoplastic resin composition can be applied. For example, (1) each raw material (for example, a thermoplastic polyester resin, a modifier, and other resins as required, and other additives as required) is mixed using a Henschel mixer and/or a tumbler mixer, and then (2) the obtained mixture is melt-kneaded to obtain a thermoplastic polyester resin composition. For the melt-kneading, a kneader such as a single-screw or twin-screw extruder, a Banbury mixer, a pressure kneader, or a mixing roll can be used. By such melt-kneading, pellets made of a thermoplastic polyester resin composition can be produced.

[Molded body]
The molded article according to one embodiment of the present invention is a molded article made of the thermoplastic polyester resin composition according to one embodiment of the present invention described in the above section [Thermoplastic polyester resin composition]. The molded article according to one embodiment of the present invention can also be said to be a molded article obtained by molding the thermoplastic polyester resin composition according to one embodiment of the present invention described in the above section [Thermoplastic polyester resin composition].

The molded article according to one embodiment of the present invention has the above-mentioned configuration, and therefore has the advantage of having excellent impact strength (in other words, excellent impact resistance).

The molded article according to one embodiment of the present invention can be obtained by molding the resin composition into a predetermined shape. There are no particular limitations on the molding method, and for example, injection molding, extrusion molding, blow molding, calendar molding, inflation molding, rotational molding, press molding, etc. can be used.

[Application]
The present modifier, the present resin composition and the molded article according to one embodiment of the present invention are useful in: (a) automotive applications such as cylinder head covers, engine covers, intake manifolds, radiator tanks, oil pans, accelerator pedals, canisters, fuel tubes, air brake tubes, exhaust gas tubes, hydrogen injectors, ducts, industrial fasteners, door mirror stays, etc.; (b) electrical and electronic applications such as coil bobbins, connectors, gears, sockets, switches, electric blanket coated wires, optical fiber cable coating materials, power tools, and electric wire ties; and (c) hydraulic and pneumatic connectors and tubes, bearings, covers and housings, bearings. (d) building material applications such as curtain rail parts, aluminum sash corners, door rollers, handrails, curtain rollers, door handles, etc.; (e) sports and leisure applications such as sports shoe soles, ski and snowboard equipment, reels, diving snorkels, etc.; (f) packaging materials and container applications such as shrink wrapping film, food packaging film, alcoholic beverage bottles, pesticide bottles, etc.; (g) daily necessities applications such as toothbrushes, chair legs and armrests, combs, knives and forks, etc.; and (h) medical applications such as medical catheters and pipes, medical packs, sutures, etc.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

(Polymerization Conversion Rate)
A part of the polymer particle latex obtained in each Example or Comparative Example was collected and weighed, dried in a hot air dryer at 120°C for 1 hour, and the weight after drying was weighed as the solid content. Next, the ratio of the weighing results before and after drying was calculated as the solid content ratio in the latex. Finally, the polymerization conversion rate was calculated using this solid content ratio according to the following formula.
Polymerization conversion rate=(total weight of raw materials charged×ratio of solid components−total weight of raw materials other than monomers)/weight of charged monomer×100(%)
(Volume average particle size)
The polymer particle latex was used as a sample to obtain a volume-based cumulative particle size distribution of particle size using a Nanotrac UPA (dynamic light scattering particle size distribution analyzer) manufactured by Microtrac Bell Co., Ltd. In the obtained cumulative particle size distribution, the particle size at which the cumulative volume was 50% was defined as the volume average particle size of the polymer microparticles.

<Method of producing polymer particles>
The method for producing polymer particle 1 (particle 1) is described below. Polymer particles 2 to 16 were produced by the same method as described below, except that the monomer composition excluding the polyfunctional monomer was changed as shown in Table 1 or 3. However, in the production of particle 3, a NaOH saponification product of Phosphanol RD 510Y was used instead of sodium dodecyl sulfate.

The amount of polyfunctional monomer used in the production of each particle is explained below. The first core layer of particles 1, 7, 8, and 12 to 16 uses 0.40 parts by weight of allyl methacrylate, the first core layer of particles 2 to 6 uses 0.42 parts by weight of allyl methacrylate, the first core layer of particles 9 and 10 uses 0.36 parts by weight of allyl methacrylate, and the first core layer of particle 11 uses 0.32 parts by weight of allyl methacrylate. The second core layer of particles 1 to 16 uses 0.05 parts by weight of allyl methacrylate.

114 parts by weight of deionized water, 0.05 parts by weight of sodium carbonate, 0.0945 parts by weight of sodium dodecyl sulfate, 0.00576 parts by weight of disodium ethylenediaminetetraacetate, 0.00144 parts by weight of ferrous sulfate, and 0.05 parts by weight of sodium formaldehyde sulfoxylate were charged into a glass reactor equipped with a thermometer, a stirrer, a reflux condenser, a nitrogen inlet, and a device for adding monomers and emulsifiers. The mixture was heated to 35°C while stirring in a nitrogen stream. Next, a mixture of 73.54 parts by weight of butyl acrylate (hereinafter referred to as BA), 7.50 parts by weight of 2-ethylhexyl acrylate (hereinafter referred to as 2EHA), 0.40 parts by weight of allyl methacrylate, 0.028 parts by weight of cumene hydroperoxide, and 0.87 parts by weight of sodium dodecyl sulfate was added over 160 minutes, and the temperature was raised to 65°C 70 minutes after the addition of the monomer mixture. The temperature was lowered to 50°C immediately after the addition of the monomer mixture. This formed the first core layer.

Immediately after, a mixture of 4.50 parts by weight of BA, 0.50 parts by weight of glycidyl methacrylate (hereafter referred to as GMA), 0.05 parts by weight of allyl methacrylate, and 0.00572 parts by weight of cumene hydroperoxide was added over a period of 10 minutes. 15 minutes after the addition was completed, 0.0286 parts by weight of cumene hydroperoxide was added. This formed the second core layer.

After a further 30 minutes, 0.05 parts by weight of sodium formaldehyde sulfoxylate was added, followed by the addition of a mixture of 8.11 parts by weight of BA, 0.05 parts by weight of GMA, and 0.04 parts by weight of cumene hydroperoxide over a period of 30 minutes. 15 minutes after the addition was complete, 0.026 parts by weight of cumene hydroperoxide was added and stirred for 20 minutes. This formed the first shell layer.

Immediately after, 0.2 parts by weight of sodium dodecyl sulfate was added, followed by the addition of 6.00 parts by weight of methyl methacrylate (hereinafter referred to as MMA) and 0.012 parts by weight of potassium persulfate all at once, and 15 minutes later, 0.012 parts by weight of potassium persulfate was added, and after 30 minutes, the mixture was stirred to form a second shell layer. As a result, a latex containing polymer particles 1 (particles 1) was obtained. The polymerization conversion rate was 100%.

(Obtaining white resin powder of polymer particles)
After stirring 500 parts by weight of deionized water and 4.0 parts by weight of a 25% by weight aqueous calcium chloride solution, the polymer particle latex was added to obtain a slurry containing coagulated latex particles. The obtained slurry was then heated to 80° C., dehydrated, and dried to obtain a white resin powder of polymer particles.

(Examples 1 to 13 and Comparative Examples 1 to 4 (Production of Thermoplastic Polyester Resin Compositions))
According to the composition shown in Table 2 or 4, a thermoplastic polyester resin, a white resin powder of each polymer particle, and additives as necessary were mixed to obtain a thermoplastic polyester resin composition. Using the obtained resin composition, a test piece was prepared by the following method, and the Izod impact strength and MFR of the obtained test piece were measured under the following conditions. The results are shown in Tables 2 and 4. Note that "IFR168" is IRGAFOS168 manufactured by BASF, and "IRG1010" is IRGANOX1010 manufactured by BASF. Furthermore, particle 17 is IM140P manufactured by Kaneka Corporation, and is a particle having an acrylic core-shell structure that does not contain GMA units.

(Test piece (molded body) preparation conditions)
(a) Polybutylene terephthalate resin (Novaduran 5010 manufactured by Mitsubishi Engineering Corporation in Examples 1 to 4 and Comparative Examples 1 to 3; Pocan B1505 manufactured by Lanxess Corporation in Examples 5 to 13 and Comparative Example 4): 90 parts by weight (b) White resin powder of polymer particles obtained in each Example or Comparative Example: 10 parts by weight (a) and (b) were mixed and pelletized using a twin-screw extruder (TKZ25 manufactured by Technovel Corporation) under the conditions of C2/C3/C4/C5/C6/C7/ADAPTER/DIE=220/225/230/235/240/245/250/250° C. and a screw rotation speed of 200 rpm.

The pellets were dried in a vacuum dryer at 120°C for 5 hours to sufficiently reduce the moisture content, and then test pieces were made in an injection molding machine (FANUC AUTOSHOT-MODEL 100B manufactured by FANUC Corporation) under the following conditions: nozzle temperature 260°C, cylinder temperatures 250°C, 240°C, and 230°C (from the side closest to the nozzle), and a mold temperature of 80°C. The test pieces obtained in this manner can also be considered as molded articles of the resin composition. Therefore, the test pieces of Examples 1 to 13 can also be considered as molded articles according to one embodiment of the present invention.

(Izod intensity measurement conditions)
The test pieces with a width of 4.0 mm and a thickness of 1/8 inch and a V-notch prepared by the above-mentioned method were subjected to temperature tests in an absolute dry state at 23°C, 0°C or -30°C by a method conforming to JIS K 7110. The Izod impact strength (kJ/m ² ) at 10° C. was measured.

(MFR)
The pellets were dried in a vacuum dryer at 120° C. for 5 hours, and then the MFR value (g/10 min) was measured in accordance with ISO 1133-1 at a measurement temperature of 250° C. and a load of 2.16 kg. The results are shown in Table 2.

One embodiment of the present invention provides a modifier made of polymer particles that can be blended with a thermoplastic polyester resin to improve the impact strength of a molded product of the thermoplastic polyester resin, and a thermoplastic polyester resin composition containing the modifier. Therefore, one embodiment of the present invention can be suitably used in a wide range of applications, including automotive applications, electrical and electronic applications, mechanical applications, building materials, sports and leisure applications, packaging materials and containers, daily necessities, and medical applications.

Claims (10)

A modifier for thermoplastic polyester resins, comprising polymer particles,
the polymer particles have a core-shell structure including a first core layer, a second core layer formed outside the first core layer, a first shell layer formed outside the second core layer, and a second shell layer formed outside the first shell layer;
The first core layer comprises a crosslinked polymer _C1 comprising an acrylic acid ester unit having an alkyl group having 5 to 9 carbon atoms and a polyfunctional monomer unit;
The second core layer comprises a crosslinked polymer _C2 comprising an acrylic acid ester unit, an epoxy group-containing (meth)acrylic monomer unit, and a polyfunctional monomer unit;
The first shell layer contains 60% by weight to 100% by weight of an acrylic ester unit based on 100% by weight of the first shell layer,
The second shell layer contains 60% by weight to 100% by weight of methacrylic acid ester units based on 100% by weight of the second shell layer. The modifier for thermoplastic polyester resins according to claim 1, wherein the first shell layer further contains an epoxy group-containing (meth)acrylic monomer unit. The modifier for thermoplastic polyester resins according to claim 1, wherein the epoxy groups contained in the polymer particles are in a range of 1.0 x 10 ⁴ to 8.0 x 10 ⁶ per particle. The modifier for thermoplastic polyester resins according to claim 1, wherein the epoxy groups contained in the polymer particles are 2.5 x 10 ⁴ to 4.5 x 10 ⁶ per particle. The modifier for thermoplastic polyester resins according to claim 1, wherein the epoxy groups contained in the polymer particles are 5.0 x 10 ⁴ to 9.0 x 10 ⁵ per particle. The modifier for thermoplastic polyester resins according to claim 1, wherein the second shell layer does not contain an epoxy group-containing (meth)acrylic monomer unit. The modifier for thermoplastic polyester resins according to claim 1, wherein the first shell layer and/or the second shell layer does not contain a polyfunctional monomer unit. The modifier for thermoplastic polyester resins according to claim 1, wherein the content ratios of the first core layer, the second core layer, the first shell layer and the second shell layer in the polymer particles are 60% by weight to 90% by weight, 2% by weight to 30% by weight, 2% by weight to 15% by weight and 3% by weight to 15% by weight, respectively, based on 100% by weight of the polymer particles. A thermoplastic polyester resin and a modifier for thermoplastic polyester resin according to any one of claims 1 to 8 are contained,
A thermoplastic polyester resin composition comprising 2% by weight to 40% by weight of the modifier for thermoplastic polyester resin, with the total of the thermoplastic polyester resin and the modifier for thermoplastic polyester resin being 100% by weight. A molded article made of the thermoplastic polyester resin composition according to claim 9.